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Sample records for kainate receptor-mediated neurotransmission

  1. Effects of Chronic Alcohol Exposure on Kainate Receptor-Mediated Neurotransmission in the Hippocampus

    Science.gov (United States)

    2004-09-01

    12917-12922, 1999. Frerking M, and Nicoll RA. Synaptic kainate receptors. Cur Opin Neurobio 10:342-351, 2000. Harvey J and Lacey MG. A postsynaptic...electrophysiological research. Ironically, this preparation was originally developed for use in biochemical studies characterizing energy metabolism in neuronal

  2. Role of desensitization and subunit expression for kainate receptor-mediated neurotoxicity in murine neocortical cultures

    DEFF Research Database (Denmark)

    Jensen, J B; Schousboe, A; Pickering, D S

    1999-01-01

    ) toxicity mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors, and (3) toxicity that can be mediated by kainate receptors when desensitization of the receptors is blocked. The indirect action at NMDA receptors was discovered because (5R, 10S)-(+)-5-methyl-10,11-dihydro-5H...... nedioxy-5H-2,3-benzodiazepine (GYKI 53655), a selective AMPA receptor antagonist, abolished the remaining toxicity. These results indicated that kainate- and domoate-mediated toxicity involves both the NMDA and the AMPA receptors. Pretreatment of the cultures with concanavalin A to prevent desensitization...

  3. Lessons from crystal structures of kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Frydenvang, Karla Andrea; Pickering, Darryl S

    2017-01-01

    Kainate receptors belong to the family of ionotropic glutamate receptors. These receptors assemble from five subunits (GluK1-5) into tetrameric ion channels. Kainate receptors are located at both pre- and postsynaptic membranes in the central nervous system where they contribute to excitatory...... synaptic transmission and modulate network excitability by regulating neurotransmitter release. Dysfunction of kainate receptors has been implicated in several neurological disorders such as epilepsy, schizophrenia and depression. Here we provide a review on the current understanding of kainate receptor...

  4. Phenobarbital but not diazepam reduces AMPA/Kainate receptor mediated currents and exerts opposite actions on initial seizures in the neonatal rat hippocampus

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    Romain eNardou

    2011-07-01

    Full Text Available Diazepam (DZP and phenobarbital (PB are extensively used as first and second line drugs to treat acute seizures in neonates and their actions are thought to be mediated by increasing the actions of GABAergic signals. Yet, their efficacy is variable with occasional failure or even aggravation of recurrent seizures questioning whether other mechanisms are not involved in their actions. We have now compared the effects of DZP and PB on ictal-like events (ILEs in an in vitro model of mirror focus (MF. Using the three-compartment chamber with the two immature hippocampi and their commissural fibers placed in 3 different compartments, kainate was applied to one hippocampus and PB or DZP to the contralateral one, either after one ILE or after many recurrent ILEs that produce an epileptogenic MF. We report that in contrast to PB, DZP aggravated propagating ILEs from the start and did not prevent the formation of MF. PB reduced and DZP increased the network driven Giant Depolarising Potentials suggesting that PB may exert additional actions that are not mediated by GABA signalling. In keeping with this, PB but not DZP reduced field potentials recorded in the presence of GABA and NMDA receptor antagonists. These effects are mediated by a direct action on AMPA/Kainate receptors since PB: i reduced AMPA/Kainate receptor mediated currents induced by focal applications of glutamate ; ii reduced the amplitude and the frequency of AMPA but not NMDA receptor mediated miniature EPSCs; iii augmented the number of AMPA receptor mediated EPSCs failures evoked by minimal stimulation. These effects persisted in MF. Therefore, PB exerts its anticonvulsive actions partly by reducing AMPA/Kainate receptors mediated EPSCs in addition to the pro-GABA effects. We suggest that PB may have advantage over DZP in the treatment of initial neonatal seizures since the additional reduction of glutamate receptors mediated signals may reduce the severity of neonatal seizures.

  5. Glutamate AMPA/kainate receptors, not GABA(A) receptors, mediate estradiol-induced sex differences in the hypothalamus.

    Science.gov (United States)

    Todd, Brigitte J; Schwarz, Jaclyn M; Mong, Jessica A; McCarthy, Margaret M

    2007-02-15

    Sex differences in brain morphology underlie physiological and behavioral differences between males and females. During the critical perinatal period for sexual differentiation in the rat, gonadal steroids act in a regionally specific manner to alter neuronal morphology. Using Golgi-Cox impregnation, we examined several parameters of neuronal morphology in postnatal day 2 (PN2) rats. We found that in the ventromedial nucleus of the hypothalamus (VMN) and in areas just dorsal and just lateral to the VMN that there was a sex difference in total dendritic spine number (males greater) that was abolished by treating female neonates with exogenous testosterone. Dendritic branching was similarly sexually differentiated and hormonally modulated in the VMN and dorsal to the VMN. We then used spinophilin, a protein that positively correlates with the amount of dendritic spines, to investigate the mechanisms underlying these sex differences. Estradiol, which mediates most aspects of masculinization and is the aromatized product of testosterone, increased spinophilin levels in female PN2 rats to that of males. Muscimol, an agonist at GABA(A) receptors, did not affect spinophilin protein levels in either male or female neonates. Kainic acid, an agonist at glutamatergic AMPA/kainate receptors, mimicked the effect of estradiol in females. Antagonizing AMPA/kainate receptors with NBQX prevented the estradiol-induced increase in spinophilin in females but did not affect spinophilin level in males. (c) 2007 Wiley Periodicals, Inc.

  6. Stronger Dopamine D1 Receptor-Mediated Neurotransmission in Dyskinesia.

    Science.gov (United States)

    Farré, Daniel; Muñoz, Ana; Moreno, Estefanía; Reyes-Resina, Irene; Canet-Pons, Júlia; Dopeso-Reyes, Iria G; Rico, Alberto J; Lluís, Carme; Mallol, Josefa; Navarro, Gemma; Canela, Enric I; Cortés, Antonio; Labandeira-García, José L; Casadó, Vicent; Lanciego, José L; Franco, Rafael

    2015-12-01

    Radioligand binding assays to rat striatal dopamine D1 receptors showed that brain lateralization of the dopaminergic system were not due to changes in expression but in agonist affinity. D1 receptor-mediated striatal imbalance resulted from a significantly higher agonist affinity in the left striatum. D1 receptors heteromerize with dopamine D3 receptors, which are considered therapeutic targets for dyskinesia in parkinsonian patients. Expression of both D3 and D1-D3 receptor heteromers were increased in samples from 6-hydroxy-dopamine-hemilesioned rats rendered dyskinetic by treatment with 3, 4-dihydroxyphenyl-L-alanine (L-DOPA). Similar findings were obtained using striatal samples from primates. Radioligand binding studies in the presence of a D3 agonist led in dyskinetic, but not in lesioned or L-DOPA-treated rats, to a higher dopamine sensitivity. Upon D3-receptor activation, the affinity of agonists for binding to the right striatal D1 receptor increased. Excess dopamine coming from L-DOPA medication likely activates D3 receptors thus making right and left striatal D1 receptors equally responsive to dopamine. These results show that dyskinesia occurs concurrently with a right/left striatal balance in D1 receptor-mediated neurotransmission.

  7. Distinct Subunit Domains Govern Synaptic Stability and Specificity of the Kainate Receptor

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    Christoph Straub

    2016-07-01

    Full Text Available Synaptic communication between neurons requires the precise localization of neurotransmitter receptors to the correct synapse type. Kainate-type glutamate receptors restrict synaptic localization that is determined by the afferent presynaptic connection. The mechanisms that govern this input-specific synaptic localization remain unclear. Here, we examine how subunit composition and specific subunit domains contribute to synaptic localization of kainate receptors. The cytoplasmic domain of the GluK2 low-affinity subunit stabilizes kainate receptors at synapses. In contrast, the extracellular domain of the GluK4/5 high-affinity subunit synergistically controls the synaptic specificity of kainate receptors through interaction with C1q-like proteins. Thus, the input-specific synaptic localization of the native kainate receptor complex involves two mechanisms that underlie specificity and stabilization of the receptor at synapses.

  8. NMDA and AMPA/kainate glutamatergic receptors in the prelimbic medial prefrontal cortex modulate the elaborated defensive behavior and innate fear-induced antinociception elicited by GABAA receptor blockade in the medial hypothalamus.

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    de Freitas, Renato Leonardo; Salgado-Rohner, Carlos José; Biagioni, Audrey Francisco; Medeiros, Priscila; Hallak, Jaime Eduardo Cecílio; Crippa, José Alexandre S; Coimbra, Norberto Cysne

    2014-06-01

    The aim of the present study was to investigate the involvement of N-methyl-d-aspartate (NMDA) and amino-3-hydroxy-5-methyl-isoxazole-4-proprionate (AMPA)/kainate receptors of the prelimbic (PL) division of the medial prefrontal cortex (MPFC) on the panic attack-like reactions evoked by γ-aminobutyric acid-A receptor blockade in the medial hypothalamus (MH). Rats were pretreated with NaCl 0.9%, LY235959 (NMDA receptor antagonist), and NBQX (AMPA/kainate receptor antagonist) in the PL at 3 different concentrations. Ten minutes later, the MH was treated with bicuculline, and the defensive responses were recorded for 10 min. The antagonism of NMDA receptors in the PL decreased the frequency and duration of all defensive behaviors evoked by the stimulation of the MH and reduced the innate fear-induced antinociception. However, the pretreatment of the PL cortex with NBQX was able to decrease only part of defensive responses and innate fear-induced antinociception. The present findings suggest that the NMDA-glutamatergic system of the PL is critically involved in panic-like responses and innate fear-induced antinociception and those AMPA/kainate receptors are also recruited during the elaboration of fear-induced antinociception and in panic attack-related response. The activation of the glutamatergic neurotransmission of PL division of the MPFC during the elaboration of oriented behavioral reactions elicited by the chemical stimulation of the MH recruits mainly NMDA receptors in comparison with AMPA/kainate receptors.

  9. Functional Validation of Heteromeric Kainate Receptor Models.

    Science.gov (United States)

    Paramo, Teresa; Brown, Patricia M G E; Musgaard, Maria; Bowie, Derek; Biggin, Philip C

    2017-11-21

    Kainate receptors require the presence of external ions for gating. Most work thus far has been performed on homomeric GluK2 but, in vivo, kainate receptors are likely heterotetramers. Agonists bind to the ligand-binding domain (LBD) which is arranged as a dimer of dimers as exemplified in homomeric structures, but no high-resolution structure currently exists of heteromeric kainate receptors. In a full-length heterotetramer, the LBDs could potentially be arranged either as a GluK2 homomer alongside a GluK5 homomer or as two GluK2/K5 heterodimers. We have constructed models of the LBD dimers based on the GluK2 LBD crystal structures and investigated their stability with molecular dynamics simulations. We have then used the models to make predictions about the functional behavior of the full-length GluK2/K5 receptor, which we confirmed via electrophysiological recordings. A key prediction and observation is that lithium ions bind to the dimer interface of GluK2/K5 heteromers and slow their desensitization. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Cerebellar Kainate Receptor-Mediated Facilitation of Glutamate Release Requires Ca2+-Calmodulin and PKA

    Directory of Open Access Journals (Sweden)

    Rafael Falcón-Moya

    2018-06-01

    Full Text Available We elucidated the mechanisms underlying the kainate receptor (KAR-mediated facilitatory modulation of synaptic transmission in the cerebellum. In cerebellar slices, KA (3 μM increased the amplitude of evoked excitatory postsynaptic currents (eEPSCs at synapses between axon terminals of parallel fibers (PF and Purkinje neurons. KA-mediated facilitation was antagonized by NBQX under condition where AMPA receptors were previously antagonized. Inhibition of protein kinase A (PKA suppressed the effect of KA on glutamate release, which was also obviated by the prior stimulation of adenylyl cyclase (AC. KAR-mediated facilitation of synaptic transmission was prevented by blocking Ca2+ permeant KARs using philanthotoxin. Furthermore, depletion of intracellular Ca2+ stores by thapsigargin, or inhibition of Ca2+-induced Ca2+-release by ryanodine, abrogated the synaptic facilitation by KA. Thus, the KA-mediated modulation was conditional on extracellular Ca2+ entry through Ca2+-permeable KARs, as well as and mobilization of Ca2+ from intracellular stores. Finally, KAR-mediated facilitation was sensitive to calmodulin inhibitors, W-7 and calmidazolium, indicating that the increased cytosolic [Ca2+] sustaining KAR-mediated facilitation of synaptic transmission operates through a downstream Ca2+/calmodulin coupling. We conclude that, at cerebellar parallel fiber-Purkinje cell synapses, presynaptic KARs mediate glutamate release facilitation, and thereby enhance synaptic transmission through Ca2+-calmodulin dependent activation of adenylyl cyclase/cAMP/protein kinase A signaling.

  11. Preferential assembly of heteromeric kainate and AMPA receptor amino terminal domains.

    Science.gov (United States)

    Zhao, Huaying; Lomash, Suvendu; Chittori, Sagar; Glasser, Carla; Mayer, Mark L; Schuck, Peter

    2017-10-23

    Ion conductivity and the gating characteristics of tetrameric glutamate receptor ion channels are determined by their subunit composition. Competitive homo- and hetero-dimerization of their amino-terminal domains (ATDs) is a key step controlling assembly. Here we measured systematically the thermodynamic stabilities of homodimers and heterodimers of kainate and AMPA receptors using fluorescence-detected sedimentation velocity analytical ultracentrifugation. Measured affinities span many orders of magnitude, and complexes show large differences in kinetic stabilities. The association of kainate receptor ATD dimers is generally weaker than the association of AMPA receptor ATD dimers, but both show a general pattern of increased heterodimer stability as compared to the homodimers of their constituents, matching well physiologically observed receptor combinations. The free energy maps of AMPA and kainate receptor ATD dimers provide a framework for the interpretation of observed receptor subtype combinations and possible assembly pathways.

  12. The prostaglandin EP1 receptor potentiates kainate receptor activation via a protein kinase C pathway and exacerbates status epilepticus

    Science.gov (United States)

    Rojas, Asheebo; Gueorguieva, Paoula; Lelutiu, Nadia; Quan, Yi; Shaw, Renee; Dingledine, Raymond

    2014-01-01

    Prostaglandin E2 (PGE2) regulates membrane excitability, synaptic transmission, plasticity, and neuronal survival. The consequences of PGE2 release following seizures has been the subject of much study. Here we demonstrate that the prostaglandin E2 receptor 1 (EP1, or Ptger1) modulates native kainate receptors, a family of ionotropic glutamate receptors widely expressed throughout the central nervous system. Global ablation of the EP1 gene in mice (EP1-KO) had no effect on seizure threshold after kainate injection but reduced the likelihood to enter status epilepticus. EP1-KO mice that did experience typical status epilepticus had reduced hippocampal neurodegeneration and a blunted inflammatory response. Further studies with native prostanoid and kainate receptors in cultured cortical neurons, as well as with recombinant prostanoid and kainate receptors expressed in Xenopus oocytes, demonstrated that EP1 receptor activation potentiates heteromeric but not homomeric kainate receptors via a second messenger cascade involving phospholipase C, calcium and protein kinase C. Three critical GluK5 C-terminal serines underlie the potentiation of the GluK2/GluK5 receptor by EP1 activation. Taken together, these results indicate that EP1 receptor activation during seizures, through a protein kinase C pathway, increases the probability of kainic acid induced status epilepticus, and independently promotes hippocampal neurodegeneration and a broad inflammatory response. PMID:24952362

  13. Effects of pilocarpine and kainate-induced seizures on N-methyl-d-aspartate receptor gene expression in the rat hippocampus

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    Przewlocka, B.; Labuz, D.; Machelska, H.; Przewlocki, R.; Turchan, J.; Lason, W. [Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow (Poland)

    1997-04-14

    The effects of pilocarpine- and kainate-induced seizures on N-methyl-d-aspartate receptor subunit-1 messenger RNA and [{sup 3}H]dizocilpine maleate binding were studied in the rat hippocampal formation. Pilocarpine- but not kainate-induced seizures decreased N-methyl-d-aspartate receptor subunit-1 messenger RNA level in dentate gyrus at 24 and 72 h after drug injection. Both convulsants decreased the messenger RNA level in CA1 pyramidal cells at 24 and 72 h, the effects of kainate being more profound. Kainate also decreased the N-methyl-d-aspartate receptor subunit-1 messenger RNA level in CA3 region after 24 and 72 h, whereas pilocarpine decreased the messenger RNA level at 72 h only. At 3 h after kainate, but not pilocarpine, an increased binding of [{sup 3}H]dizocilpine maleate in several apical dendritic fields of pyramidal cells was found. Pilocarpine reduced the [{sup 3}H]dizocilpine maleate binding in stratum lucidum only at 3 and 24 h after the drug injection. Pilocarpine but not kainate induced prolonged decrease in N-methyl-d-aspartate receptor subunit-1 gene expression in dentate gyrus. However, at the latest time measured, kainate had the stronger effect in decreasing both messenger RNA N-methyl-d-aspartate receptor subunit-1 and [{sup 3}H]dizocilpine maleate binding in CA1 and CA3 hippocampal pyramidal cells. The latter changes corresponded, however, to neuronal loss and may reflect higher neurotoxic potency of kainate.These data point to some differences in hippocampal N-methyl-d-aspartate receptor regulation in pilocarpine and kainate models of limbic seizures. Moreover, our results suggest that the N-methyl-d-aspartate receptor subunit-1 messenger RNA level is more susceptible to limbic seizures than is [{sup 3}H]dizocilpine maleate binding in the rat hippocampal formation. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Effects of pilocarpine and kainate-induced seizures on N-methyl-d-aspartate receptor gene expression in the rat hippocampus

    International Nuclear Information System (INIS)

    Przewlocka, B.; Labuz, D.; Machelska, H.; Przewlocki, R.; Turchan, J.; Lason, W.

    1997-01-01

    The effects of pilocarpine- and kainate-induced seizures on N-methyl-d-aspartate receptor subunit-1 messenger RNA and [ 3 H]dizocilpine maleate binding were studied in the rat hippocampal formation. Pilocarpine- but not kainate-induced seizures decreased N-methyl-d-aspartate receptor subunit-1 messenger RNA level in dentate gyrus at 24 and 72 h after drug injection. Both convulsants decreased the messenger RNA level in CA1 pyramidal cells at 24 and 72 h, the effects of kainate being more profound. Kainate also decreased the N-methyl-d-aspartate receptor subunit-1 messenger RNA level in CA3 region after 24 and 72 h, whereas pilocarpine decreased the messenger RNA level at 72 h only. At 3 h after kainate, but not pilocarpine, an increased binding of [ 3 H]dizocilpine maleate in several apical dendritic fields of pyramidal cells was found. Pilocarpine reduced the [ 3 H]dizocilpine maleate binding in stratum lucidum only at 3 and 24 h after the drug injection. Pilocarpine but not kainate induced prolonged decrease in N-methyl-d-aspartate receptor subunit-1 gene expression in dentate gyrus. However, at the latest time measured, kainate had the stronger effect in decreasing both messenger RNA N-methyl-d-aspartate receptor subunit-1 and [ 3 H]dizocilpine maleate binding in CA1 and CA3 hippocampal pyramidal cells. The latter changes corresponded, however, to neuronal loss and may reflect higher neurotoxic potency of kainate.These data point to some differences in hippocampal N-methyl-d-aspartate receptor regulation in pilocarpine and kainate models of limbic seizures. Moreover, our results suggest that the N-methyl-d-aspartate receptor subunit-1 messenger RNA level is more susceptible to limbic seizures than is [ 3 H]dizocilpine maleate binding in the rat hippocampal formation. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  15. N1-Substituted 2,3-Quinoxalinediones as Kainate Receptor Antagonists: X-ray Crystallography, Structure-Affinity Relationships and in vitro Pharmacology

    DEFF Research Database (Denmark)

    Pallesen, Jakob Staun; Møllerud, Stine; Frydenvang, Karla Andrea

    2018-01-01

    Among the ionotropic glutamate receptors, the physiological role of kainate receptors is less well understood than AMPA and NMDA receptors, partly due to a lack of selective pharmacological tool compounds. Although ligands with selectivity towards the kainate receptor subtype GluK1 are available,...

  16. β adrenergic receptor modulation of neurotransmission to cardiac vagal neurons in the nucleus ambiguus.

    Science.gov (United States)

    Bateman, R J; Boychuk, C R; Philbin, K E; Mendelowitz, D

    2012-05-17

    β-adrenergic receptors are a class of G protein-coupled receptors that have essential roles in regulating heart rate, blood pressure, and other cardiorespiratory functions. Although the role of β adrenergic receptors in the peripheral nervous system is well characterized, very little is known about their role in the central nervous system despite being localized in many brain regions involved in autonomic activity and regulation. Since parasympathetic activity to the heart is dominated by cardiac vagal neurons (CVNs) originating in the nucleus ambiguus (NA), β adrenergic receptors localized in the NA represent a potential target for modulating cardiac vagal activity and heart rate. This study tests the hypothesis that activation of β adrenergic receptors alters the membrane properties and synaptic neurotransmission to CVNs. CVNs were identified in brainstem slices, and membrane properties and synaptic events were recorded using the whole-cell voltage-clamp technique. The nonselective β agonist isoproterenol significantly decreased inhibitory GABAergic and glycinergic as well as excitatory glutamatergic neurotransmission to CVNs. In addition, the β(1)-selective receptor agonist dobutamine, but not β(2) or β(3) receptor agonists, significantly decreased inhibitory GABAergic and glycinergic and excitatory glutamatergic neurotransmission to CVNs. These decreases in neurotransmission to CVNs persisted in the presence of tetrodotoxin (TTX). These results provide a mechanism by which activation of adrenergic receptors in the brainstem can alter parasympathetic activity to the heart. Likely physiological roles for this adrenergic receptor activation are coordination of parasympathetic-sympathetic activity and β receptor-mediated increases in heart rate upon arousal. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Evidence for a Specific Integrative Mechanism for Episodic Memory Mediated by AMPA/kainate Receptors in a Circuit Involving Medial Prefrontal Cortex and Hippocampal CA3 Region.

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    de Souza Silva, Maria A; Huston, Joseph P; Wang, An-Li; Petri, David; Chao, Owen Yuan-Hsin

    2016-07-01

    We asked whether episodic-like memory requires neural mechanisms independent of those that mediate its component memories for "what," "when," and "where," and if neuronal connectivity between the medial prefrontal cortex (mPFC) and the hippocampus (HPC) CA3 subregion is essential for episodic-like memory. Unilateral lesion of the mPFC was combined with unilateral lesion of the CA3 in the ipsi- or contralateral hemispheres in rats. Episodic-like memory was tested using a task, which assesses the integration of memories for "what, where, and when" concomitantly. Tests for novel object recognition (what), object place (where), and temporal order memory (when) were also applied. Bilateral disconnection of the mPFC-CA3 circuit by N-methyl-d-aspartate (NMDA) lesions disrupted episodic-like memory, but left the component memories for object, place, and temporal order, per se, intact. Furthermore, unilateral NMDA lesion of the CA3 plus injection of (6-cyano-7-nitroquinoxaline-2,3-dione) (CNQX) (AMPA/kainate receptor antagonist), but not AP-5 (NMDA receptor antagonist), into the contralateral mPFC also disrupted episodic-like memory, indicating the mPFC AMPA/kainate receptors as critical for this circuit. These results argue for a selective neural system that specifically subserves episodic memory, as it is not critically involved in the control of its component memories for object, place, and time. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Structure and assembly mechanism for heteromeric kainate receptors.

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    Kumar, Janesh; Schuck, Peter; Mayer, Mark L

    2011-07-28

    Native glutamate receptor ion channels are tetrameric assemblies containing two or more different subunits. NMDA receptors are obligate heteromers formed by coassembly of two or three divergent gene families. While some AMPA and kainate receptors can form functional homomeric ion channels, the KA1 and KA2 subunits are obligate heteromers which function only in combination with GluR5-7. The mechanisms controlling glutamate receptor assembly involve an initial step in which the amino terminal domains (ATD) assemble as dimers. Here, we establish by sedimentation velocity that the ATDs of GluR6 and KA2 coassemble as a heterodimer of K(d) 11 nM, 32,000-fold lower than the K(d) for homodimer formation by KA2; we solve crystal structures for the GluR6/KA2 ATD heterodimer and heterotetramer assemblies. Using these structures as a guide, we perform a mutant cycle analysis to probe the energetics of assembly and show that high-affinity ATD interactions are required for biosynthesis of functional heteromeric receptors. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Design, synthesis and structure-activity relationships of novel phenylalanine-based amino acids as kainate receptors ligands

    DEFF Research Database (Denmark)

    Szymańska, Ewa; Chałupnik, Paulina; Szczepańska, Katarzyna

    2016-01-01

    A new series of carboxyaryl-substituted phenylalanines was designed, synthesized and pharmacologically characterized in vitro at native rat ionotropic glutamate receptors as well as at cloned homomeric kainate receptors GluK1-GluK3. Among them, six compounds bound to GluK1 receptor subtypes with ...

  20. Increased NMDA and AMPA receptor densities in the anterior cingulate cortex in schizophrenia

    International Nuclear Information System (INIS)

    Zavitsanou, K.; Huang, X.-F.

    2002-01-01

    Full text: The anterior cingulate cortex (ACC) is a brain area of potential importance to our understanding of the pathophysiology of schizophrenia. Since a disturbed balance between excitatory and inhibitory activity is suggested to occur in the ACC in schizophrenia, the present study has focused on the analysis of binding of [ 3 H]MK801, [ 3 H]AMPA and [ 3 H]kainate, radioligands which respectively label the NMDA, AMPA and kainate receptors of the ionotropic glutamate receptor family in the ACC of 10 schizophrenia patients and 10 matched controls, using quantitative autoradiography. AMPA receptor densities were higher in cortical layer II whereas NMDA receptor densities were higher in cortical layers II-III in the ACC of both control and schizophrenia group. In contrast, kainate receptors displayed the highest density in cortical layer V. [ 3 H]AMPA binding was significantly increased by 25% in layer II in the schizophrenia group as compared to the control group. Similarly, a significant 17% increase of [ 3 H]MK801 binding was observed in layers II-III in the schizophrenia group. No statistically significant differences were observed for [ 3 H] kainate binding between the two groups. These results suggest that ionotropic glutamate receptors are differentially altered in the ACC of schizophrenia. The increase in [ 3 H]AMPA and [ 3 H]MK801 binding points to a postsynaptic compensation for impaired glutamatergic neurotransmission in the ACC in schizophrenia. Such abnormality could lead to an imbalance between the excitatory and inhibitory neurotransmission in this brain area that may contribute to the emergence of some schizophrenia symptoms. Copyright (2002) Australian Neuroscience Society

  1. Prenatal Alcohol Exposure Increases Histamine H3 Receptor-Mediated Inhibition of Glutamatergic Neurotransmission in Rat Dentate Gyrus.

    Science.gov (United States)

    Varaschin, Rafael K; Allen, Nyika A; Rosenberg, Martina J; Valenzuela, C Fernando; Savage, Daniel D

    2018-02-01

    We have reported that prenatal alcohol exposure (PAE)-induced deficits in dentate gyrus, long-term potentiation (LTP), and memory are ameliorated by the histamine H 3 receptor inverse agonist ABT-239. Curiously, ABT-239 did not enhance LTP or memory in control offspring. Here, we initiated an investigation of how PAE alters histaminergic neurotransmission in the dentate gyrus and other brain regions employing combined radiohistochemical and electrophysiological approaches in vitro to examine histamine H 3 receptor number and function. Long-Evans rat dams voluntarily consumed either a 0% or 5% ethanol solution 4 hours each day throughout gestation. This pattern of drinking, which produces a mean peak maternal serum ethanol concentration of 60.8 ± 5.8 mg/dl, did not affect maternal weight gain, litter size, or offspring birthweight. Radiohistochemical studies in adult offspring revealed that specific [ 3 H]-A349821 binding to histamine H 3 receptors was not different in PAE rats compared to controls. However, H 3 receptor-mediated G i /G o protein-effector coupling, as measured by methimepip-stimulated [ 35 S]-GTPγS binding, was significantly increased in cerebral cortex, cerebellum, and dentate gyrus of PAE rats compared to control. A LIGAND analysis of detailed methimepip concentration-response curves in dentate gyrus indicated that PAE significantly elevates receptor-effector coupling by a lower affinity H 3 receptor population without significantly altering the affinities of H 3 receptor subpopulations. In agreement with the [ 35 S]-GTPγS studies, a similar range of methimepip concentrations also inhibited electrically evoked field excitatory postsynaptic potential responses and increased paired-pulse ratio, a measure of decreased glutamate release, to a significantly greater extent in dentate gyrus slices from PAE rats than in controls. These results suggest that a PAE-induced elevation in H 3 receptor-mediated inhibition of glutamate release from

  2. The metabolic impact of β-hydroxybutyrate on neurotransmission: Reduced glycolysis mediates changes in calcium responses and KATP channel receptor sensitivity

    DEFF Research Database (Denmark)

    Lund, Trine Meldgaard; Ploug, K.B.; Iversen, Anne

    2015-01-01

    -hydroxybutyrate might change neuronal function as there is a known coupling between metabolism and neurotransmission. The purpose of this study was to shed light on the effects of the ketone body β-hydroxybutyrate on glycolysis and neurotransmission in cultured murine glutamatergic neurons. Previous studies have shown...... an effect of β-hydroxybutyrate on glucose metabolism, and the present study further specified this by showing attenuation of glycolysis when β-hydroxybutyrate was present in these neurons. In addition, the NMDA receptor-induced calcium responses in the neurons were diminished in the presence of β...... to a combination of glucose and R-β-hydroxybutyrate in cultured neurons. Using the latter combination, glycolysis was diminished, NMDA receptor-induced calcium responses were lower, and the KATP channel blocker glibenclamide caused a higher transmitter release....

  3. Striatal dopamine D2/3 receptor-mediated neurotransmission in major depression: Implications for anhedonia, anxiety and treatment response.

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    Peciña, Marta; Sikora, Magdalena; Avery, Erich T; Heffernan, Joseph; Peciña, Susana; Mickey, Brian J; Zubieta, Jon-Kar

    2017-10-01

    Dopamine (DA) neurotransmission within the brain's reward circuit has been implicated in the pathophysiology of depression and in both, cognitive and pharmacological mechanisms of treatment response. Still, a direct relationship between measures of DA neurotransmission and reward-related deficits in patients with depression has not been demonstrated. To gain insight into the symptom-specific alterations in the DA system in patients with depression, we used positron emission tomography (PET) and the D 2/3 receptor-selective radiotracer [ 11 C]raclopride in twenty-three non-smoking un-medicated Major Depressive Disorder (MDD) patients and sixteen healthy controls (HC). We investigated the relationship between D 2/3 receptor availability and baseline measures of depression severity, anxiety, anhedonia, and cognitive and pharmacological mechanisms of treatment response. We found that, compared to controls, patients with depression showed greater D 2/3 receptor availability in several striatal regions, including the bilateral ventral pallidum/nucleus accumbens (vPAL/NAc), and the right ventral caudate and putamen. In the depressed sample, D 2/3 receptor availability in the caudal portion of the ventral striatum (NAc/vPAL) correlated with higher anxiety symptoms, whereas D 2/3 receptor availability in the rostral area of the ventral striatum correlated negatively with the severity of motivational anhedonia. Finally, MDD non-remitters showed greater baseline anxiety, greater D 2/3 availability in the NAc/vPAL, and greater placebo-induced DA release in the bilateral NAc. Our results demonstrate abnormally high D 2/3 receptor availability in the ventral striatum of patients with MDD, which seem to be associated with comorbid anxiety symptoms and lack of response to antidepressants. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

  4. Cell and receptor type-specific alterations in markers of GABA neurotransmission in the prefrontal cortex of subjects with schizophrenia.

    Science.gov (United States)

    Lewis, David A; Hashimoto, Takanori; Morris, Harvey M

    2008-10-01

    Impairments in cognitive control, such as those involved in working memory, are associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC) in individuals with schizophrenia. This dysfunction appears to result, at least in part, from abnormalities in GABA-mediated neurotransmission. In this paper, we review recent findings indicating that the altered DLPFC circuitry in subjects with schizophrenia reflects changes in the expression of genes that encode selective presynaptic and postsynaptic components of GABA neurotransmission. Specifically, using a combination of methods, we found that subjects with schizophrenia exhibited expression deficits in GABA-related transcripts encoding presynaptic regulators of GABA neurotransmission, neuropeptide markers of specific subpopulations of GABA neurons, and certain subunits of the GABA(A) receptor. In particular, alterations in the expression of the neuropeptide somatostatin suggested that GABA neurotransmission is impaired in the Martinotti subset of GABA neurons that target the dendrites of pyramidal cells. In contrast, none of the GABA-related transcripts assessed to date were altered in the DLPFC of monkeys chronically exposed to antipsychotic medications, suggesting that the effects observed in the human studies reflect the disease process and not its treatment. In concert with previous findings, these data suggest that working memory dysfunction in schizophrenia may be attributable to altered GABA neurotransmission in specific DLPFC microcircuits.

  5. Type II and III Taste Bud Cells Preferentially Expressed Kainate Glutamate Receptors in Rats.

    Science.gov (United States)

    Lee, Sang-Bok; Lee, Cil-Han; Kim, Se-Nyun; Chung, Ki-Myung; Cho, Young-Kyung; Kim, Kyung-Nyun

    2009-12-01

    Glutamate-induced cobalt uptake reveals that non-NMDA glutamate receptors (GluRs) are present in rat taste bud cells. Previous studies involving glutamate induced cobalt staining suggest this uptake mainly occurs via kainate type GluRs. It is not known which of the 4 types of taste bud cells express subunits of kainate GluR. Circumvallate and foliate papillae of Sprague-Dawley rats (45~60 days old) were used to search for the mRNAs of subunits of non-NMDA GluRs using RT-PCR with specific primers for GluR1-7, KA1 and KA2. We also performed RT-PCR for GluR5, KA1, PLCbeta2, and NCAM/SNAP 25 in isolated single cells from taste buds. Taste epithelium, including circumvallate or foliate papilla, express mRNAs of GluR5 and KA1. However, non-taste tongue epithelium expresses no subunits of non-NMDA GluRs. Isolated single cell RT-PCR reveals that the mRNAs of GluR5 and KA1 are preferentially expressed in Type II and Type III cells over Type I cells.

  6. Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

    Directory of Open Access Journals (Sweden)

    Dickenson Anthony H

    2009-02-01

    Full Text Available Abstract Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1 has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal

  7. Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

    Science.gov (United States)

    Nguyen, David; Deng, Ping; Matthews, Elizabeth A; Kim, Doo-Sik; Feng, Guoping; Dickenson, Anthony H; Xu, Zao C; Luo, Z David

    2009-01-01

    Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1) has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia) similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR) neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal horn neurons to innocuous

  8. NMDA and kainate receptor expression, long-term potentiation, and neurogenesis in the hippocampus of long-lived Ames dwarf mice.

    Science.gov (United States)

    Sharma, Sunita; Darland, Diane; Lei, Saobo; Rakoczy, Sharlene; Brown-Borg, Holly M

    2012-06-01

    In the current study, we investigated changes in N-methyl D-aspartate (NMDA) and kainate receptor expression, long-term potentiation (LTP), and neurogenesis in response to neurotoxic stress in long-living Ames dwarf mice. We hypothesized that Ames dwarf mice have enhanced neurogenesis that enables retention of spatial learning and memory with age and promotes neurogenesis in response to injury. Levels of the NMDA receptors (NR)1, NR2A, NR2B, and the kainate receptor (KAR)2 were increased in Ames dwarf mice, relative to wild-type littermates. Quantitative assessment of the excitatory postsynaptic potential in Schaffer collaterals in hippocampal slices from Ames dwarf mice showed an increased response in high-frequency induced LTP over time compared with wild type. Kainic acid (KA) injection was used to promote neurotoxic stress-induced neurogenesis. KA mildly increased the number of doublecortin-positive neurons in wild-type mice, but the response was significantly enhanced in the Ames dwarf mice. Collectively, these data support our hypothesis that the enhanced learning and memory associated with the Ames dwarf mouse may be due to elevated levels of NMDA and KA receptors in hippocampus and their ability to continue producing new neurons in response to neuronal damage.

  9. The metabolic impact of β-hydroxybutyrate on neurotransmission: Reduced glycolysis mediates changes in calcium responses and KATP channel receptor sensitivity.

    Science.gov (United States)

    Lund, Trine M; Ploug, Kenneth B; Iversen, Anne; Jensen, Anders A; Jansen-Olesen, Inger

    2015-03-01

    Glucose is the main energy substrate for neurons, and ketone bodies are known to be alternative substrates. However, the capacity of ketone bodies to support different neuronal functions is still unknown. Thus, a change in energy substrate from glucose alone to a combination of glucose and β-hydroxybutyrate might change neuronal function as there is a known coupling between metabolism and neurotransmission. The purpose of this study was to shed light on the effects of the ketone body β-hydroxybutyrate on glycolysis and neurotransmission in cultured murine glutamatergic neurons. Previous studies have shown an effect of β-hydroxybutyrate on glucose metabolism, and the present study further specified this by showing attenuation of glycolysis when β-hydroxybutyrate was present in these neurons. In addition, the NMDA receptor-induced calcium responses in the neurons were diminished in the presence of β-hydroxybutyrate, whereas a direct effect of the ketone body on transmitter release was absent. However, the presence of β-hydroxybutyrate augmented transmitter release induced by the KATP channel blocker glibenclamide, thus giving an indirect indication of the involvement of KATP channels in the effects of ketone bodies on transmitter release. Energy metabolism and neurotransmission are linked and involve ATP-sensitive potassium (KATP ) channels. However, it is still unclear how and to what degree available energy substrate affects this link. We investigated the effect of changing energy substrate from only glucose to a combination of glucose and R-β-hydroxybutyrate in cultured neurons. Using the latter combination, glycolysis was diminished, NMDA receptor-induced calcium responses were lower, and the KATP channel blocker glibenclamide caused a higher transmitter release. © 2014 International Society for Neurochemistry.

  10. Orexin A-induced anxiety-like behavior is mediated through GABA-ergic, α- and β-adrenergic neurotransmissions in mice.

    Science.gov (United States)

    Palotai, Miklós; Telegdy, Gyula; Jászberényi, Miklós

    2014-07-01

    Orexins are hypothalamic neuropeptides, which are involved in several physiological functions of the central nervous system, including anxiety and stress. Several studies provide biochemical and behavioral evidence about the anxiogenic action of orexin A. However, we have little evidence about the underlying neuromodulation. Therefore, the aim of the present study was to investigate the involvement of neurotransmitters in the orexin A-induced anxiety-like behavior in elevated plus maze (EPM) test in mice. Accordingly, mice were pretreated with a non-selective muscarinic cholinergic antagonist, atropine; a γ-aminobutyric acid subunit A (GABA-A) receptor antagonist, bicuculline; a D2, D3, D4 dopamine receptor antagonist, haloperidol; a non-specific nitric oxide synthase (NOS) inhibitor, nitro-l-arginine; a nonselective α-adrenergic receptor antagonist, phenoxybenzamine and a β-adrenergic receptor antagonist, propranolol 30min prior to the intracerebroventricular administration of orexin A. The EPM test started 30min after the i.c.v. injection of the neuropeptide. Our results show that orexin A decreases significantly the time spent in the arms (open/open+closed) and this action is reversed by bicuculline, phenoxybenzamine and propranolol, but not by atropine, haloperidol or nitro-l-arginine. Our results provide evidence for the first time that the orexin A-induced anxiety-like behavior is mediated through GABA-A-ergic, α- and β-adrenergic neurotransmissions, whereas muscarinic cholinergic, dopaminergic and nitrergic neurotransmissions may not be implicated. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Ion Channels and Zinc: Mechanisms of Neurotoxicity and Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Deborah R. Morris

    2012-01-01

    Full Text Available Ionotropic glutamate receptors, such as NMDA, AMPA and kainate receptors, are ligand-gated ion channels that mediate much of the excitatory neurotransmission in the brain. Not only do these receptors bind glutamate, but they are also regulated by and facilitate the postsynaptic uptake of the trace metal zinc. This paper discusses the role of the excitotoxic influx and accumulation of zinc, the mechanisms responsible for its cytotoxicity, and a number of disorders of the central nervous system that have been linked to these neuronal ion channels and zinc toxicity including ischemic brain injury, traumatic brain injury, and epilepsy.

  12. VMAT2-mediated neurotransmission from midbrain leptin receptor neurons in feeding regulation

    Science.gov (United States)

    Leptin receptors (LepRs) expressed in the midbrain contribute to the action of leptin on feeding regulation. The midbrain neurons release a variety of neurotransmitters including dopamine (DA), glutamate and GABA. However, which neurotransmitter mediates midbrain leptin action on feeding remains unc...

  13. Neuropeptide Y-stimulated [(35) S]GTPγs functional binding is reduced in the hippocampus after kainate-induced seizures in mice

    DEFF Research Database (Denmark)

    Elbrønd-Bek, Heidi; Olling, Janne Damm; Gøtzsche, Casper René

    2014-01-01

    , in this study, we explored functional NPY receptor activity in the mouse hippocampus and neocortex after kainate-induced seizures using NPY-stimulated [(35) S]GTPγS binding. Moreover, we also studied levels of [(125) I]-peptide YY (PYY) binding and NPY, Y1, Y2, and Y5 receptor mRNA in these kainate-treated mice...

  14. Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus.

    Science.gov (United States)

    Chen, Z L; Huang, R Q

    2014-06-20

    Changes in extracellular pH have a modulatory effect on GABAA receptor function. It has been reported that pH sensitivity of the GABA receptor is dependent on subunit composition and GABA concentration. Most of previous investigations focused on GABA-evoked currents, which only reflect the postsynaptic receptors. The physiological relevance of pH modulation of GABAergic neurotransmission is not fully elucidated. In the present studies, we examined the influence of extracellular pH on the GABAA receptor-mediated inhibitory neurotransmission in rat hypothalamic neurons. The inhibitory postsynaptic currents (IPSCs), tonic currents, and the GABA-evoked currents were recorded with whole-cell patch techniques on the hypothalamic slices from Sprague-Dawley rats at 15-26 postnatal days. The amplitude and frequency of spontaneous GABA IPSCs were significantly increased while the external pH was changed from 7.3 to 8.4. In the acidic pH (6.4), the spontaneous GABA IPSCs were reduced in amplitude and frequency. The pH induced changes in miniature GABA IPSCs (mIPSCs) similar to that in spontaneous IPSCs. The pH effect on the postsynaptic GABA receptors was assessed with exogenously applied varying concentrations of GABA. The tonic currents and the currents evoked by sub-saturating concentration of GABA ([GABA]) (10 μM) were inhibited by acidic pH and potentiated by alkaline pH. In contrast, the currents evoked by saturating [GABA] (1mM) were not affected by pH changes. We also investigated the influence of pH buffers and buffering capacity on pH sensitivity of GABAA receptors on human recombinant α1β2γ2 GABAA receptors stably expressed in HEK 293 cells. The pH influence on GABAA receptors was similar in HEPES- and MES-buffered media, and not dependent on protonated buffers, suggesting that the observed pH effect on GABA response is a specific consequence of changes in extracellular protons. Our data suggest that the hydrogen ions suppress the GABAergic neurotransmission

  15. Glufosinate ammonium induces convulsion through N-methyl-D-aspartate receptors in mice.

    Science.gov (United States)

    Matsumura, N; Takeuchi, C; Hishikawa, K; Fujii, T; Nakaki, T

    2001-05-18

    Glufosinate ammonium, a broad-spectrum herbicide, causes convulsion in rodents and humans. Because of the structural similarities between glufosinate and glutamate, the convulsion induced by glufosinate ammonium may be ascribed to glutamate receptor activation. Three N-methyl-D-asparate (NMDA) receptor antagonists, dizocilpine, LY235959, and Compound 40, and an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor antagonist, NBQX, were coadministrated with glufosinate ammonium (80 mg/kg, intraperitoneally) in mice. Statistical analyses showed that the NMDA receptor antagonists markedly inhibited the convulsions, while the AMPA/kainate receptor antagonist had no effect on the convulsion. These results suggest that the convulsion caused by glufosinate ammonium is mediated through NMDA receptors.

  16. Anticonvulsant effect of AMP by direct activation of adenosine A1 receptor.

    Science.gov (United States)

    Muzzi, Mirko; Coppi, Elisabetta; Pugliese, Anna Maria; Chiarugi, Alberto

    2013-12-01

    Purinergic neurotransmission mediated by adenosine (Ado) type 1 receptors (A1Rs) plays pivotal roles in negative modulation of epileptic seizures, and Ado is thought to be a key endogenous anticonvulsant. Recent evidence, however, indicates that AMP, the metabolic precursor of Ado, also activate A1Rs. Here, we evaluated the antiepileptic effects of AMP adopting in vitro and in vivo models of epilepsy. We report that AMP reversed the increase in population spike (PS) amplitude and the decrease in PS latency induced by a Mg(2+)-free extracellular solution in CA1 neurons of mouse hippocampal slices. The AMP effects were inhibited by the A1R antagonist DPCPX, but not prevented by inhibiting conversion of AMP into Ado, indicating that AMP inhibited per se sustained hippocampal excitatory neurotransmission by directly activating A1Rs. AMP also reduced seizure severity and mortality in a model of audiogenic convulsion. Of note, the anticonvulsant effects of AMP were potentiated by preventing its conversion into Ado and inhibited by DPCPX. When tested in a model of kainate-induced seizure, AMP prolonged latency of convulsions but had no effects on seizure severity and mortality. Data provide the first evidence that AMP is an endogenous anticonvulsant acting at A1Rs. © 2013.

  17. The dextromethorphan analog dimemorfan attenuates kainate-induced seizures via σ1 receptor activation: comparison with the effects of dextromethorphan

    OpenAIRE

    Shin, Eun-Joo; Nah, Seung-Yeol; Kim, Won-Ki; Ko, Kwang Ho; Jhoo, Wang-Kee; Lim, Yong-Kwang; Cha, Joo Young; Chen, Chieh-Fu; Kim, Hyoung-Chun

    2005-01-01

    In a previous study, we demonstrated that a dextromethorphan analog, dimemorfan, has neuroprotective effects.Dextromethorphan and dimemorfan are high-affinity ligands at σ1 receptors. Dextromethorphan has moderate affinities for phencyclidine sites, while dimemorfan has very low affinities for such sites, suggesting that these sites are not essential for the anticonvulsant actions of dimemorfan.Kainate (KA) administration (10 mg kg−1, i.p.) produced robust convulsions lasting 4–6 h in rats. P...

  18. Glutamatergic neurotransmission modulation and the mechanisms of antipsychotic atypicality.

    Science.gov (United States)

    Heresco-Levy, Uriel

    2003-10-01

    The neurotransmission mediated by the excitatory amino acids (EAA) glutamate (GLU) and aspartate is of interest to the pharmacotherapy of psychosis due to its role in neurodevelopment and neurotoxicity, its complex interactions with dopaminergic and other neurotransmitter systems and its pivotal importance in recent models of schizophrenia. Accumulating evidence indicates that modulation of glutamatergic neurotransmission may play an important role in the mechanisms of action of atypical antipsychotic drugs. The principles of the phencyclidine (PCP) model of schizophrenia suggest that conventional neuroleptics cannot counteract all aspects of schizophrenia symptomatology, while a more favorable outcome, including anti-negative and cognitive symptoms effects, would be expected with the use of treatment modalities targeting glutamatergic neurotransmission. Clozapine and other presently used atypical antipsychotics differ from conventional neuroleptics in the way they affect various aspects of glutamatergic receptors function. In this context, a specific hypothesis suggesting an agonistic role of clozapine at the N-methyl-D-aspartate (NMDA) subtype of GLU receptors has been postulated. Furthermore, the results of the first generation of clinical trials with glycine (GLY) site agonists of the NMDA receptor in schizophrenia suggest that this type of compounds (1) have efficacy and side effects profiles different than those of conventional neuroleptics and (2) differ in their synergic effects when used in addition to conventional neuroleptics versus clozapine and possibly additional atypical antipsychotics. These findings (1) bring further support to the hypothesis that glutamatergic effects may play an important role in the mechanism of action of atypical antipsychotics, (2) help explain the unique clinical profile of clozapine, and (3) suggest that GLY site agonists of the NMDA receptor may represent a new class of atypical antipsychotic medication. Future research in

  19. GLP-1 receptor stimulation depresses heart rate variability and inhibits neurotransmission to cardiac vagal neurons.

    Science.gov (United States)

    Griffioen, Kathleen J; Wan, Ruiqian; Okun, Eitan; Wang, Xin; Lovett-Barr, Mary Rachael; Li, Yazhou; Mughal, Mohamed R; Mendelowitz, David; Mattson, Mark P

    2011-01-01

    glucagon-like peptide 1 (GLP-1) is an incretin hormone released from the gut in response to food intake. Whereas GLP-1 acts in the periphery to inhibit glucagon secretion and stimulate insulin release, it also acts in the central nervous system to mediate autonomic control of feeding, body temperature, and cardiovascular function. Because of its role as an incretin hormone, GLP-1 receptor analogs are used as a treatment for type 2 diabetes. Central or peripheral administration of GLP-1 increases blood pressure and heart rate, possibly by activating brainstem autonomic nuclei and increasing vagus nerve activity. However, the mechanism(s) by which GLP-1 receptor stimulation affects cardiovascular function are unknown. We used the long-lasting GLP-1 receptor agonist Exendin-4 (Ex-4) to test the hypothesis that GLP-1 signalling modulates central parasympathetic control of heart rate. using a telemetry system, we assessed heart rate in mice during central Ex-4 administration. Heart rate was increased by both acute and chronic central Ex-4 administration. Spectral analysis indicated that the high frequency and low frequency powers of heart rate variability were diminished by Ex-4 treatment. Finally, Ex-4 decreased both excitatory glutamatergic and inhibitory glycinergic neurotransmission to preganglionic parasympathetic cardiac vagal neurons. these data suggest that central GLP-1 receptor stimulation diminishes parasympathetic modulation of the heart thereby increasing heart rate.

  20. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  1. Endothelial and Neuronal Nitric Oxide Activate Distinct Pathways on Sympathetic Neurotransmission in Rat Tail and Mesenteric Arteries.

    Directory of Open Access Journals (Sweden)

    Joana Beatriz Sousa

    Full Text Available Nitric oxide (NO seems to contribute to vascular homeostasis regulating neurotransmission. This work aimed at assessing the influence of NO from different sources and respective intracellular pathways on sympathetic neurotransmission, in two vascular beds. Electrically-evoked [3H]-noradrenaline release was assessed in rat mesenteric and tail arteries in the presence of NO donors or endothelial/neuronal nitric oxide synthase (NOS inhibitors. The influence of NO on adenosine-mediated effects was also studied using selective antagonists for adenosine receptors subtypes. Location of neuronal NOS (nNOS was investigated by immunohistochemistry (with specific antibodies for nNOS and for Schwann cells and Confocal Microscopy. Results indicated that: 1 in mesenteric arteries, noradrenaline release was reduced by NO donors and it was increased by nNOS inhibitors; the effect of NO donors was only abolished by the adenosine A1 receptors antagonist; 2 in tail arteries, noradrenaline release was increased by NO donors and it was reduced by eNOS inhibitors; adenosine receptors antagonists were devoid of effect; 3 confocal microscopy showed nNOS staining in adventitial cells, some co-localized with Schwann cells. nNOS staining and its co-localization with Schwann cells were significantly lower in tail compared to mesenteric arteries. In conclusion, in mesenteric arteries, nNOS, mainly located in Schwann cells, seems to be the main source of NO influencing perivascular sympathetic neurotransmission with an inhibitory effect, mediated by adenosine A1 receptors activation. Instead, in tail arteries endothelial NO seems to play a more relevant role and has a facilitatory effect, independent of adenosine receptors activation.

  2. Zinc movement in the brain under kainate-induced seizures.

    Science.gov (United States)

    Takeda, Atsushi; Hirate, Maki; Tamano, Haruna; Oku, Naoto

    2003-05-01

    On the basis of the evidence that elimination of 65Zn from the brain of epilepsy (EL) mice is facilitated by induction of seizures, zinc movement in the brain was studied in mice injected with kainate (12 mg/kg x 3), which exhibited status epilepticus within 120 min after the last injection of kainate. Zinc concentrations in the brain were determined 24 h after the last injection of kainate. Zinc concentrations in the hippocampus, amygdala and cerebral cortex, in which zinc-containing glutamatergic neuron terminals exist, were significantly decreased by the treatment with kainate, while that in the cerebellum was not decreased. Timm's stain in the brain was extensively attenuated 24 h after the last injection of kainate. These results indicate that zinc homeostasis in the brain is affected by kainate-induced seizures. In the hippocampus of rats injected with kainate (10 mg/kg), furthermore, the release of zinc and glutamate into the extracellular fluid was studied using in vivo microdialysis. The levels of zinc and glutamate in the perfusate were increased along with seizure severity after injection of kainate. It is likely that zinc concentration in the synaptic vesicles is decreased by the excess excitation of glutamatergic neurons. The present study suggests that the excessive release of zinc and glutamate from the neuron terminals under kainate-induced seizures is associated with the loss of zinc from the brain.

  3. Cognitive Function and Monoamine Neurotransmission in Schizophrenia: Evidence From Positron Emission Tomography Studies

    Directory of Open Access Journals (Sweden)

    Harumasa Takano

    2018-05-01

    Full Text Available Positron emission tomography (PET is a non-invasive imaging technique used to assess various brain functions, including cerebral blood flow, glucose metabolism, and neurotransmission, in the living human brain. In particular, neurotransmission mediated by the monoamine neurotransmitters dopamine, serotonin, and norepinephrine, has been extensively examined using PET probes, which specifically bind to the monoamine receptors and transporters. This useful tool has revealed the pathophysiology of various psychiatric disorders, including schizophrenia, and the mechanisms of action of psychotropic drugs. Because monoamines are implicated in various cognitive processes such as memory and executive functions, some PET studies have directly investigated the associations between monoamine neurotransmission and cognitive functions in healthy individuals and patients with psychiatric disorders. In this mini review, I discuss the findings of PET studies that investigated monoamine neurotransmission under resting conditions, specifically focusing on cognitive functions in patients with schizophrenia. With regard to the dopaminergic system, some studies have examined the association of dopamine D1 and D2/D3 receptors, dopamine transporters, and dopamine synthesis capacity with various cognitive functions in schizophrenia. With regard to the serotonergic system, 5-HT1A and 5-HT2A receptors have been studied in the context of cognitive functions in schizophrenia. Although relatively few PET studies have examined cognitive functions in patients with psychiatric disorders, these approaches can provide useful information on enhancing cognitive functions by administering drugs that modulate monoamine transmission. Moreover, another paradigm of techniques such as those exploring the release of neurotransmitters and further development of radiotracers for novel targets are warranted.

  4. Neuropeptide Y Y1 receptor hippocampal overexpression via viral vectors is associated with modest anxiolytic-like and proconvulsant effects in mice

    DEFF Research Database (Denmark)

    Olesen, Mikkel V; Christiansen, Søren Hofman Oliveira; Gøtzsche, Casper René

    2012-01-01

    overexpression was found to be associated with modest anxiolytic-like effect in the open field and elevated plus maze tests, but no effect was seen on depression-like behavior using the tail suspension and forced swim tests. However, the rAAV-Y1 vector modestly aggravated kainate-induced seizures. These data...... in the hippocampus of adult mice and tested the animals in anxiety- and depression-like behavior. Hippocampal Y1 receptors have been suggested to mediate seizure-promoting effect, so the effects of rAAV-induced Y1 receptor overexpression were also tested in kainate-induced seizures. Y1 receptor transgene...

  5. Effects of caffeine on striatal neurotransmission: focus on cannabinoid CB1 receptors.

    Science.gov (United States)

    Rossi, Silvia; De Chiara, Valentina; Musella, Alessandra; Mataluni, Giorgia; Sacchetti, Lucia; Siracusano, Alberto; Bernardi, Giorgio; Usiello, Alessandro; Centonze, Diego

    2010-04-01

    Caffeine is the most commonly self-administered psychoactive substance worldwide. At usual doses, the effects of caffeine on vigilance, attention, mood and arousal largely depend on the modulation of central adenosine receptors. The present review article describes the action of caffeine within the striatum, to provide a possible molecular mechanism at the basis of the psychomotor and reinforcing properties of this pharmacological agent. The striatum is in fact a subcortical area involved in sensorimotor, cognitive, and emotional processes, and recent experimental findings showed that chronic caffeine consumption enhances the sensitivity of striatal GABAergic synapses to the stimulation of cannabinoid CB1 receptors. The endocannabinoid system is involved in the psychoactive effects of many compounds, and adenosine A2A receptors (the main receptor target of caffeine) elicit a permissive effect towards CB1 receptors, thus suggesting that A2A-CB1 receptor interaction plays a major role in the generation and maintenance of caffeine reinforcing behavior. Aim of this review is to describe the effects of caffeine on striatal neurotransmission with special reference to the modulation of the endocannabinoid system.

  6. Copper: From neurotransmission to neuroproteostasis

    Directory of Open Access Journals (Sweden)

    Carlos M Opazo

    2014-07-01

    Full Text Available Copper is critical for the Central Nervous System (CNS development and function. In particular, different studies have shown the effect of copper at brain synapses, where it inhibits Long Term Potentation (LTP and receptor pharmacology. Paradoxically, according to recent studies copper is required for a normal LTP response. Copper is released at the synaptic cleft, where it blocks glutamate receptors, which explain its blocking effects on excitatory neurotransmission. Our results indicate that copper also enhances neurotransmission through the accumulation of PSD95 protein, which increase the levels of AMPA receptors located at the plasma membrane of the post-synaptic density. Thus, our findings represent a novel mechanism for the action of copper, which may have implications for the neurophysiology and neuropathology of the CNS. These data indicate that synaptic configuration is sensitive to transient changes in transition metal homeostasis. Our results suggest that copper increases GluA1 subunit levels of the AMPA receptor through the anchorage of AMPA receptors to the plasma membrane as a result of PSD-95 accumulation. Here, we will review the role of copper on neurotransmission of CNS neurons. In addition, we will discuss the potential mechanisms by which copper could modulate neuronal proteostasis (neuroproteostasis in the CNS with focus in the Ubiquitin Proteasome System, which is particularly relevant to neurological disorders such Alzheimer’s disease (AD where copper and protein dyshomeostasis may contribute to neurodegeneration. An understanding of these mechanisms may ultimately lead to the development of novel therapeutic approaches to control metal and synaptic alterations observed in AD patients.

  7. Molecular pharmacology of human NMDA receptors

    DEFF Research Database (Denmark)

    Hedegaard, Maiken; Hansen, Kasper Bø; Andersen, Karen Toftegaard

    2012-01-01

    N-methyl-d-aspartate (NMDA) receptors are ionotropic glutamate receptors that mediate excitatory neurotransmission. NMDA receptors are also important drug targets that are implicated in a number of pathophysiological conditions. To facilitate the transition from lead compounds in pre-clinical ani...

  8. [Schizophrenia and cortical GABA neurotransmission].

    Science.gov (United States)

    Hashimoto, Takanori; Matsubara, Takuro; Lewis, David A

    2010-01-01

    Individuals with schizophrenia show disturbances in a number of brain functions that regulate cognitive, affective, motor, and sensory processing. The cognitive deficits associated with dysfunction of the dorsolateral prefrontal cortex result, at least in part, from abnormalities in GABA neurotransmission, as reflected in a specific pattern of altered expression of GABA-related molecules. First, mRNA levels for the 67-kilodalton isoform of glutamic acid decarboxylase (GAD67), an enzyme principally responsible for GABA synthesis, and the GABA membrane transporter GAT1, which regulates the reuptake of synaptically released GABA, are decreased in a subset of GABA neurons. Second, affected GABA neurons include those that express the calcium-binding protein parvalbumin (PV), because PV mRNA levels are decreased in the prefrontal cortex of subjects with schizophrenia and GAD67 mRNA is undetectable in almost half of PV-containing neurons. These changes are accompanied by decreased GAT1 expression in the presynaptic terminals of PV-containing neurons and by increased postsynaptic GABA-A receptor alpha2 subunit expression at the axon initial segments of pyramidal neurons. These findings indicate decreased GABA synthesis/release by PV-containing GABA neurons and compensatory changes at synapses formed by these neurons. Third, another subset of GABA neurons that express the neuropeptide somatostatin (SST) also appear to be affected because their specific markers, SST and neuropeptide Y mRNAs, are decreased in a manner highly correlated with the decreases in GAD67 mRNA. Finally, mRNA levels for GABA-A receptor subunits for synaptic (alpha1 and gamma2) and extra-synaptic (delta) receptors are decreased, indicating alterations in both synaptic and extra-synaptic GABA neurotransmission. Together, this pattern of changes indicates that the altered GABA neurotransmission is specific to PV-containing and SST-containing GABA neuron subsets and involves both synaptic and extra

  9. Neurotransmission imaging by PET

    International Nuclear Information System (INIS)

    Takano, Akihiro; Suhara, Tetsuya

    2001-01-01

    PET studies on neurotransmission in psychological disorders to evaluate abnormal neurotransmission and therapeutic effects are thoroughly reviewed by type of major neurotransmitters. Studies on dopaminergic neurotransmission have focused on the function of dopamine D 2 receptors, receptor subtypes, such as the D 1 receptor, and ligands, such as transporters. PET studies of dopamine D 2 receptor, which began in the early 1980s, have predominantly been performed in schizophrenia, and most have failed to detect any statistically significant differences between schizophrenia patients and controls. The studies in the early 1980s were performed by using [ 11 C]N-methyl-spiperone (NMSP) and [ 11 C]raclopride, ligands for striatal dopamine D 2 receptors. [ 11 C]FLB457, which has much higher affinity for D 2 receptors than raclopride, began to be used in the 1990s. Dopamine D 2 occupancy after drug ingestion has also been investigated to clarify the mechanisms and effects of antipsychotic drugs, and there have also been studies on the effect of aging and personality traits on dopamine D 2 receptor levels in healthy subjects. In studies on dopamine receptor subtypes other than D 2 , dopamine D 1 receptors have been studied in connection with assessments of cognitive functions. Most studies on dopamine transporters have been related to drug dependence. Serotonin 5-HT 2A receptors have been studied with [ 11 C]NMSP in schizophrenia patients, while studies of another serotonin receptor subtype, 5-HT 1A receptors, have been mainly conducted in patients with depression. [ 11 C]NMSP PET showed no difference between schizophrenia patients who had not undergone phamacotherapy and normal subjects. Because serotonin selective reuptake inhibitors (SSRIs) affect serotonin transporters, and abnormalities in serotonin transporters detected in mood disorders, PET ligands for serotonin transporters have increasingly been developed, and serotonin transporters have recently begun to be

  10. Selective kainate receptor (GluK1) ligands structurally based upon1H-Cyclopentapyrimidin-2,4(1H,3H)-dione: synthesis, molecular modeling, and pharmacological and biostructural characterization

    DEFF Research Database (Denmark)

    Venskutonyte, Raminta; Butini, Stefania; Coccone, Salvatore Sanna

    2011-01-01

    The physiological function of kainate receptors (GluK1- GluK5) in the central nervous system is not fully understood yet. With the aim of developing potent and selective GluK1 ligands, we have synthesized a series of new thiophene-based GluK1 agonists (6a-c) and antagonists (7a-d). Pharmacologica...

  11. Neurotransmission imaging by PET

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Akihiro; Suhara, Tetsuya [National Inst. of Radiological Sciences, Chiba (Japan)

    2001-08-01

    PET studies on neurotransmission in psychological disorders to evaluate abnormal neurotransmission and therapeutic effects are thoroughly reviewed by type of major neurotransmitters. Studies on dopaminergic neurotransmission have focused on the function of dopamine D{sub 2} receptors, receptor subtypes, such as the D{sub 1} receptor, and ligands, such as transporters. PET studies of dopamine D{sub 2} receptor, which began in the early 1980s, have predominantly been performed in schizophrenia, and most have failed to detect any statistically significant differences between schizophrenia patients and controls. The studies in the early 1980s were performed by using [{sup 11}C]N-methyl-spiperone (NMSP) and [{sup 11}C]raclopride, ligands for striatal dopamine D{sub 2} receptors. [{sup 11}C]FLB457, which has much higher affinity for D{sub 2} receptors than raclopride, began to be used in the 1990s. Dopamine D{sub 2} occupancy after drug ingestion has also been investigated to clarify the mechanisms and effects of antipsychotic drugs, and there have also been studies on the effect of aging and personality traits on dopamine D{sub 2} receptor levels in healthy subjects. In studies on dopamine receptor subtypes other than D{sub 2}, dopamine D{sub 1} receptors have been studied in connection with assessments of cognitive functions. Most studies on dopamine transporters have been related to drug dependence. Serotonin 5-HT{sub 2A} receptors have been studied with [{sup 11}C]NMSP in schizophrenia patients, while studies of another serotonin receptor subtype, 5-HT{sub 1A} receptors, have been mainly conducted in patients with depression. [{sup 11}C]NMSP PET showed no difference between schizophrenia patients who had not undergone phamacotherapy and normal subjects. Because serotonin selective reuptake inhibitors (SSRIs) affect serotonin transporters, and abnormalities in serotonin transporters detected in mood disorders, PET ligands for serotonin transporters have increasingly

  12. Dopamine modulation of avoidance behavior in Caenorhabditis elegans requires the NMDA receptor NMR-1.

    Directory of Open Access Journals (Sweden)

    Melvin Baidya

    Full Text Available The nematode C. elegans utilizes a relatively simple neural circuit to mediate avoidance responses to noxious stimuli such as the volatile odorant octanol. This avoidance behavior is modulated by dopamine. cat-2 mutant animals that are deficient in dopamine biosynthesis have an increased response latency to octanol compared to wild type animals, and this defect can be fully restored with the application of exogenous dopamine. Because this avoidance behavior is mediated by glutamatergic signaling between sensory neurons and premotor interneurons, we investigated the genetic interactions between dopaminergic signaling and ionotropic glutamate receptors. cat-2 mutant animals lacking either the GLR-1 or GLR-2 AMPA/kainate receptors displayed an increased response latency to octanol, which could be restored via exogenous dopamine. However, whereas cat-2 mutant animals lacking the NMR-1 NMDA receptor had increased response latency to octanol they were insensitive to exogenous dopamine. Mutants that lacked both AMPA/kainate and NMDA receptors were also insensitive to exogenous dopamine. Our results indicate that dopamine modulation of octanol avoidance requires NMR-1, consistent with NMR-1 as a potential downstream signaling target for dopamine.

  13. Elimination of zinc-65 from the brain under kainate-induced seizures.

    Science.gov (United States)

    Takeda, Atsushi; Hirate, Maki; Oku, Naoto

    2004-04-01

    On the basis of the previous evidence that 65Zn concentrations in the brain of EL (epilepsy) mice was affected by induction of seizures, 65Zn movement in the brain was quantitatively evaluated in ddY mice treated with kainate. Six days after intravenous injection of 65ZnCl2, mice were intraperitoneally injected with kainate (10 mg/kg x 6 times in 2 weeks). Myoclonic jerks were observed during treatment with kainate. Twenty days after 65Zn injection, 65Zn distribution in the brain was compared between the kainite-treated and control mice. 65Zn distribution in the brain of the kainate-treated mice was overall lower than in the control mice. 65Zn concentration was significantly decreased in the frontal cortex, hippocampal CA1, thalamus and hypothalamus by treatment with kainate. These results demonstrate that kainate-induced seizures are linked to decreased zinc concentrations in the brain.

  14. Different structural requirements for functional ion pore transplantation suggest different gating mechanisms of NMDA and kainate receptors.

    Science.gov (United States)

    Villmann, Carmen; Hoffmann, Jutta; Werner, Markus; Kott, Sabine; Strutz-Seebohm, Nathalie; Nilsson, Tanja; Hollmann, Michael

    2008-10-01

    Although considerable progress has been made in characterizing the physiological function of the high-affinity kainate (KA) receptor subunits KA1 and KA2, no homomeric ion channel function has been shown. An ion channel transplantation approach was employed in this study to directly test if homomerically expressed KA1 and KA2 pore domains are capable of conducting currents. Transplantation of the ion pore of KA1 or KA2 into GluR6 generated perfectly functional ion channels that allowed characterization of those electrophysiological and pharmacological properties that are determined exclusively by the ion pore of KA1 or KA2. This demonstrates for the first time that KA1 and KA2 ion pore domains are intrinsically capable of conducting ions even in homomeric pore assemblies. NMDA receptors, similar to KA1- or KA2-containing receptors, function only as heteromeric complexes. They are composed of NR1 and NR2 subunits, which both are non-functional when expressed homomerically. In contrast to NR1, the homomeric NR2B ion pore failed to translate ligand binding into pore opening when transplanted into GluR6. Similarly, heteromeric coexpression of the ion channel domains of both NR1 and NR2 inserted into GluR6 failed to produce functional channels. Therefore, we conclude that the mechanism underlying the ion channel opening in the obligatorily heterotetrameric NMDA receptors differs significantly from that in the facultatively heterotetrameric alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate and KA receptors.

  15. What would 5-HT do? Regional diversity of 5-HT1 receptor modulation of primary afferent neurotransmission

    OpenAIRE

    Connor, Mark

    2012-01-01

    5-HT (serotonin) is a significant modulator of sensory input to the CNS, but the only analgesics that selectively target G-protein-coupled 5-HT receptors are highly specific for treatment of headache. Two recent papers in BJP shed light on this puzzling situation by showing that primary afferent neurotransmission to the superficial layers of the spinal and trigeminal dorsal is inhibited by different subtypes of the 5-HT1 receptor – 5-HT1B(and 1D) in the trigeminal dorsal horn and 5-HT1A in th...

  16. Clonidine, an alpha2-receptor agonist, diminishes GABAergic neurotransmission to cardiac vagal neurons in the nucleus ambiguus.

    Science.gov (United States)

    Philbin, Kerry E; Bateman, Ryan J; Mendelowitz, David

    2010-08-06

    In hypertension, there is an autonomic imbalance in which sympathetic activity dominates over parasympathetic control. Parasympathetic activity to the heart originates from cardiac vagal neurons located in the nucleus ambiguus. Presympathetic neurons that project to sympathetic neurons in the spinal cord are located in the ventral brainstem in close proximity to cardiac vagal neurons, and many of these presympathetic neurons are catecholaminergic. In addition to their projection to the spinal cord, many of these presympathetic neurons have axon collaterals that arborize into neighboring cardiorespiratory locations and likely release norepinephrine onto nearby neurons. Activation of alpha(2)-adrenergic receptors in the central nervous system evokes a diverse range of physiological effects, including reducing blood pressure. This study tests whether clonidine, an alpha(2)-adrenergic receptor agonist, alters excitatory glutamatergic, and/or inhibitory GABAergic or glycinergic synaptic neurotransmission to cardiac vagal neurons in the nucleus ambiguus. Cardiac vagal neurons were identified in an in vitro brainstem slice preparation, and synaptic events were recording using whole cell voltage clamp methodologies. Clonidine significantly inhibited GABAergic neurotransmission but had no effect on glycinergic or glutamatergic pathways to cardiac vagal neurons. This diminished inhibitory GABAergic neurotransmission to cardiac vagal neurons would increase parasympathetic activity to the heart, decreasing heart rate and blood pressure. The results presented here provide a cellular substrate for the clinical use of clonidine as a treatment for hypertension as well as a role in alleviating posttraumatic stress disorder by evoking an increase in parasympathetic cardiac vagal activity, and a decrease in heart rate and blood pressure. Copyright 2010 Elsevier B.V. All rights reserved.

  17. Stimulation of accumbal GABAA receptors inhibits delta2-, but not delta1-, opioid receptor-mediated dopamine efflux in the nucleus accumbens of freely moving rats.

    Science.gov (United States)

    Aono, Yuri; Kiguchi, Yuri; Watanabe, Yuriko; Waddington, John L; Saigusa, Tadashi

    2017-11-15

    The nucleus accumbens contains delta-opioid receptors that may reduce inhibitory neurotransmission. Reduction in GABA A receptor-mediated inhibition of accumbal dopamine release due to delta-opioid receptor activation should be suppressed by stimulating accumbal GABA A receptors. As delta-opioid receptors are divided into delta2- and delta1-opioid receptors, we analysed the effects of the GABA A receptor agonist muscimol on delta2- and delta1-opioid receptor-mediated accumbal dopamine efflux in freely moving rats using in vivo microdialysis. Drugs were administered intracerebrally through the dialysis probe. Doses of compounds indicate total amount administered (mol) during 25-50min infusions. The delta2-opioid receptor agonist deltorphin II (25.0nmol)- and delta1-opioid receptor agonist DPDPE (5.0nmol)-induced increases in dopamine efflux were inhibited by the delta2-opioid receptor antagonist naltriben (1.5nmol) and the delta1-opioid receptor antagonist BNTX (150.0pmol), respectively. Muscimol (250.0pmol) inhibited deltorphin II (25.0nmol)-induced dopamine efflux. The GABA A receptor antagonist bicuculline (50.0pmol), which failed to affect deltorphin II (25.0nmol)-induced dopamine efflux, counteracted the inhibitory effect of muscimol on deltorphin II-induced dopamine efflux. Neither muscimol (250.0pmol) nor bicuculline (50.0 and 500.0pmol) altered DPDPE (5.0nmol)-induced dopamine efflux. The present results show that reduction in accumbal GABA A receptor-mediated inhibition of dopaminergic activity is necessary to produce delta2-opioid receptor-induced increase in accumbal dopamine efflux. This study indicates that activation of delta2- but not delta1-opioid receptors on the cell bodies and/or terminals of accumbal GABAergic interneurons inhibits GABA release and, accordingly, decreases GABA A receptor-mediated inhibition of dopaminergic terminals, resulting in enhanced accumbal dopamine efflux. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Inhibitory neurotransmission and olfactory memory in honeybees.

    Science.gov (United States)

    El Hassani, Abdessalam Kacimi; Giurfa, Martin; Gauthier, Monique; Armengaud, Catherine

    2008-11-01

    In insects, gamma-aminobutyric acid (GABA) and glutamate mediate fast inhibitory neurotransmission through ligand-gated chloride channel receptors. Both GABA and glutamate have been identified in the olfactory circuit of the honeybee. Here we investigated the role of inhibitory transmission mediated by GABA and glutamate-gated chloride channels (GluCls) in olfactory learning and memory in honeybees. We combined olfactory conditioning with injection of ivermectin, an agonist of GluCl receptors. We also injected a blocker of glutamate transporters (L-trans-PDC) or a GABA analog (TACA). We measured acquisition and retention 1, 24 and 48 h after the last acquisition trial. A low dose of ivermectin (0.01 ng/bee) impaired long-term olfactory memory (48 h) while a higher dose (0.05 ng/bee) had no effect. Double injections of ivermectin and L-trans-PDC or TACA had different effects on memory retention, depending on the doses and agents combined. When the low dose of ivermectin was injected after Ringer, long-term memory was again impaired (48 h). Such an effect was rescued by injection of both TACA and L-trans-PDC. A combination of the higher dose of ivermectin and TACA decreased retention at 48 h. We interpret these results as reflecting the involvement of both GluCl and GABA receptors in the impairment of olfactory long-term memory induced by ivermectin. These results illustrate the diversity of inhibitory transmission and its implication in long-term olfactory memory in honeybees.

  19. Neto2 Assembles with Kainate Receptors in DRG Neurons during Development and Modulates Neurite Outgrowth in Adult Sensory Neurons.

    Science.gov (United States)

    Vernon, Claire G; Swanson, Geoffrey T

    2017-03-22

    Peripheral sensory neurons in the dorsal root ganglia (DRG) are the initial transducers of sensory stimuli, including painful stimuli, from the periphery to central sensory and pain-processing centers. Small- to medium-diameter non-peptidergic neurons in the neonatal DRG express functional kainate receptors (KARs), one of three subfamilies of ionotropic glutamate receptors, as well as the putative KAR auxiliary subunit Neuropilin- and tolloid-like 2 (Neto2). Neto2 alters recombinant KAR function markedly but has yet to be confirmed as an auxiliary subunit that assembles with and alters the function of endogenous KARs. KARs in neonatal DRG require the GluK1 subunit as a necessary constituent, but it is unclear to what extent other KAR subunits contribute to the function and proposed roles of KARs in sensory ganglia, which include promotion of neurite outgrowth and modulation of glutamate release at the DRG-dorsal horn synapse. In addition, KARs containing the GluK1 subunit are implicated in modes of persistent but not acute pain signaling. We show here that the Neto2 protein is highly expressed in neonatal DRG and modifies KAR gating in DRG neurons in a developmentally regulated fashion in mice. Although normally at very low levels in adult DRG neurons, Neto2 protein expression can be upregulated via MEK/ERK signaling and after sciatic nerve crush and Neto2 -/- neurons from adult mice have stunted neurite outgrowth. These data confirm that Neto2 is a bona fide KAR auxiliary subunit that is an important constituent of KARs early in sensory neuron development and suggest that Neto2 assembly is critical to KAR modulation of DRG neuron process outgrowth. SIGNIFICANCE STATEMENT Pain-transducing peripheral sensory neurons of the dorsal root ganglia (DRG) express kainate receptors (KARs), a subfamily of glutamate receptors that modulate neurite outgrowth and regulate glutamate release at the DRG-dorsal horn synapse. The putative KAR auxiliary subunit Neuropilin- and

  20. Hippocampal N-methyl-d-aspartate and kainate binding in response to entorhinal cortex aspiration or 192 IgG-saporin lesions of the basal forebrain

    International Nuclear Information System (INIS)

    Gallagher, M.; Gill, T.M.; Shivers, A.; Nicolle, M.M.

    1997-01-01

    Lesion models in the rat were used to examine the effects of removing innervation of the hippocampal formation on glutamate receptor binding in that system. Bilateral aspiration of the entorhinal cortex was used to remove the cortical innervation of the hippocampal formation and the dentate gyrus. The subcortical input to the hippocampus from cholinergic neurons of the basal forebrain was lesioned by microinjection of the immunotoxin 192 IgG-saporin into the medial septum and vertical limb of diagonal band. After a 30-day postlesion survival, the effects of these lesions on N-methyl-d-aspartate-displaceable [ 3 H]glutamate and [ 3 H]kainate binding in the hippocampus were quantified using in vitro autoradiography. The bilateral entorhinal lesion induced a sprouting response in the dentate gyrus, measured by an increase in the width of [ 3 H]kainate binding. It also induced an increase in the density of [ 3 H]kainate binding in CA3 stratum lucidum and an increase in N-methyl-d-aspartate binding throughout the hippocampus proper and the dentate gyrus. The selective lesion of cholinergic septal input did not have any effect on hippocampal [ 3 H]kainate binding and induced only a moderate decrease in N-methyl-d-aspartate binding that was not statistically reliable.The entorhinal and cholinergic lesions were used as in vivo models of the degeneration of hippocampal input that occurs in normal aging and Alzheimer's disease. The results from the present lesion study suggest that some, but not all, of the effects on hippocampal [ 3 H]kainate and N-methyl-d-aspartate binding induced by the lesions are consistent with the status of binding to these receptors in aging and Alzheimer's disease. Consistent with the effects of aging and Alzheimer's disease is an altered topography of [ 3 H]kainate binding after entorhinal cortex lesion and a modest decline in N-methyl-d-aspartate binding after lesions of the cholinergic septal input to the hippocampus. (Copyright (c) 1997

  1. The GABAA receptor agonist THIP is neuroprotective in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, Jens; Zimmer, Jens

    2003-01-01

    The potential neuroprotective effects of the GABA(A) receptor agonists THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and muscimol, and the selective GluR5 kainate receptor agonist ATPA ((RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid), which activates GABAergic interneu......The potential neuroprotective effects of the GABA(A) receptor agonists THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) and muscimol, and the selective GluR5 kainate receptor agonist ATPA ((RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid), which activates GABAergic...... interneurons, were examined in hippocampal slice cultures exposed to N-methyl-D-aspartate (NMDA). The NMDA-induced excitotoxicity was quantified by densitometric measurements of propidium iodide (PI) uptake. THIP (100-1000 microM) was neuroprotective in slice cultures co-exposed to NMDA (10 microM) for 48 h......, while muscimol (100-1000 microM) and ATPA (1-3 microM) were without effect. The results demonstrate that direct GABA(A) agonism can mediate neuroprotection in the hippocampus in vitro as previously suggested in vivo....

  2. AMPA/kainate glutamate receptors contribute to inflammation, degeneration and pain related behaviour in inflammatory stages of arthritis

    Science.gov (United States)

    Bonnet, Cleo S; Williams, Anwen S; Gilbert, Sophie J; Harvey, Ann K; Evans, Bronwen A; Mason, Deborah J

    2015-01-01

    Objectives Synovial fluid glutamate concentrations increase in arthritis. Activation of kainate (KA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors (GluRs) increase interleukin-6 (IL-6) release and cause arthritic pain, respectively. We hypothesised that AMPA and KA GluRs are expressed in human arthritis, and that intra-articular NBQX (AMPA/KA GluR antagonist) prevents pain and pathology in antigen-induced arthritis (AIA). Methods GluR immunohistochemistry was related to synovial inflammation and degradation in osteoarthritis (OA) and rheumatoid arthritis (RA). A single intra-articular NBQX injection was given at induction, and knee swelling and gait of AIA and AIA+NBQX rats compared over 21 days, before imaging, RT-qPCR, histology and immunohistochemistry of joints. Effects of NBQX on human primary osteoblast (HOB) activity were determined. Results AMPAR2 and KA1 immunolocalised to remodelling bone, cartilage and synovial cells in human OA and RA, and rat AIA. All arthritic tissues showed degradation and synovial inflammation. NBQX reduced GluR abundance, knee swelling (parthritis. PMID:24130267

  3. Genetic ablation of the GluK4 kainate receptor subunit causes anxiolytic and antidepressant-like behavior in mice.

    Science.gov (United States)

    Catches, Justin S; Xu, Jian; Contractor, Anis

    2012-03-17

    There is a clear link between dysregulation of glutamatergic signaling and mood disorders. Genetic variants in the glutamate receptor gene GRIK4, which encodes the kainate receptor subunit GluK4, alter the susceptibility for depression, bipolar disorder and schizophrenia. Here we demonstrate that Grik4(-/-) mice have reduced anxiety and an antidepressant-like phenotype. In the elevated zero-maze, a test for anxiety and risk taking behavior, Grik4(-/-) mice spent significantly more time exploring the open areas of the maze. In anxiogenic tests of marble-burying and novelty-induced suppression of feeding, anxiety-like behavior was consistently reduced in knockout animals. In the forced swim test, a test of learned helplessness that is used to determine depression-like behavior, knockout mice demonstrated significantly less immobility suggesting that Grik4 ablation has an antidepressant-like effect. Finally, in the sucrose preference test, a test for anhedonia in rodents, Grik4(-/-) mice demonstrated increased sucrose preference. Expression of the GluK4 receptor subunit in the forebrain is restricted to the CA3 region of the hippocampus and dentate gyrus regions where KARs are known to modulate synaptic plasticity. We tested whether Grik4 ablation had effects on mossy fiber (MF) plasticity and found there to be a significant impairment in LTP likely through a loss of KAR modulation of excitability of the presynaptic MF axons. These studies demonstrate a clear anxiolytic and antidepressant phenotype associated with ablation of Grik4 and a parallel disruption in hippocampal plasticity, providing support for the importance of this receptor subunit in mood disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. [Functional properties of taste bud cells. Mechanisms of afferent neurotransmission in Type II taste receptor cells].

    Science.gov (United States)

    Romanov, R A

    2013-01-01

    Taste Bud cells are heterogeneous in their morphology and functionality. These cells are responsible for sensing a wide variety of substances and for associating detected compounds with a different taste: bitter, sweet, salty, sour and umami. Today we know that each of the five basic tastes corresponds to distinct cell populations organized into three basic morpho-functional cell types. In addition, some receptor cells of the taste bud demonstrate glia-related functions. In this article we expand on some properties of these three morphological receptor cell types. Main focus is devoted to the Type II cells and unusual mechanism for afferent neurotransmission in these cells. Taste cells of the Type II consist of three populations detecting bitter, sweet and umami tastes, and, thus, evoke a serious scientific interest.

  5. High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors.

    Science.gov (United States)

    Lecker, Irene; Wang, Dian-Shi; Kaneshwaran, Kirusanthy; Mazer, C David; Orser, Beverley A

    2017-07-01

    The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors. Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons. Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5). Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.

  6. Differences in kainate receptor involvement in hippocampal mossy fibre long-term potentiation depending on slice orientation.

    Science.gov (United States)

    Sherwood, John L; Amici, Mascia; Dargan, Sheila L; Culley, Georgia R; Fitzjohn, Stephen M; Jane, David E; Collingridge, Graham L; Lodge, David; Bortolotto, Zuner A

    2012-09-01

    Long-term potentiation (LTP) is a well-established experimental model used to investigate the synaptic basis of learning and memory. LTP at mossy fibre - CA3 synapses in the hippocampus is unusual because it is normally N-methyl-d-aspartate (NMDA) receptor-independent. Instead it seems that the trigger for mossy fibre LTP involves kainate receptors (KARs). Although it is generally accepted that pre-synaptic KARs play an essential role in frequency facilitation and LTP, their subunit composition remains a matter of significant controversy. We have reported previously that both frequency facilitation and LTP can be blocked by selective antagonism of GluK1 (formerly GluR5/Glu(K5))-containing KARs, but other groups have failed to reproduce this effect. Moreover, data from receptor knockout and mRNA expression studies argue against a major role of GluK1, supporting a more central role for GluK2 (formerly GluR6/Glu(K6)). A potential reason underlying the controversy in the pharmacological experiments may reside in differences in the preparations used. Here we show differences in pharmacological sensitivity of synaptic plasticity at mossy fibre - CA3 synapses depend critically on slice orientation. In transverse slices, LTP of fEPSPs was invariably resistant to GluK1-selective antagonists whereas in parasagittal slices LTP was consistently blocked by GluK1-selective antagonists. In addition, there were pronounced differences in the magnitude of frequency facilitation and the sensitivity to the mGlu2/3 receptor agonist DCG-IV. Using anterograde labelling of granule cells we show that slices of both orientations possess intact mossy fibres and both large and small presynaptic boutons. Transverse slices have denser fibre tracts but a smaller proportion of giant mossy fibre boutons. These results further demonstrate a considerable heterogeneity in the functional properties of the mossy fibre projection. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Effect of the AT1-receptor antagonists losartan, irbesartan, and telmisartan on angiotensin II-induced facilitation of sympathetic neurotransmission in the rat mesenteric artery

    NARCIS (Netherlands)

    Balt, J. C.; Mathy, M. J.; Nap, A.; Pfaffendorf, M.; van Zwieten, P. A.

    2001-01-01

    SUMMARY: The effect of the AT1-receptor antagonists losartan, irbesartan, and telmisartan on angiotensin II (Ang II)-induced facilitation of noradrenergic neurotransmission was investigated in the isolated rat mesenteric artery under isometric conditions. Electrical field stimulation (2, 4, and 8

  8. The role of cortical and hypothalamic histamine-3 receptors in the modulation of central histamine neurotransmission : an in vivo electrophysiology and microdialysis study

    NARCIS (Netherlands)

    Flik, Gunnar; Dremencov, Eliyahu; Cremers, Thomas I. H. F.; Folgering, Joost H. A.; Westerink, Ben H. C.

    2011-01-01

    The current study aimed to investigate the effect of histamine-3 (H3) receptors, expressed in the tuberomammillary nucleus (TMN) of the hypothalamus and in the prefrontal cortex (PFC), on histamine neurotransmission in the rat brain. The firing activity of histamine neurons in the TMN was measured

  9. Autistic-like behaviour in Scn1a+/- mice and rescue by enhanced GABA-mediated neurotransmission.

    Science.gov (United States)

    Han, Sung; Tai, Chao; Westenbroek, Ruth E; Yu, Frank H; Cheah, Christine S; Potter, Gregory B; Rubenstein, John L; Scheuer, Todd; de la Iglesia, Horacio O; Catterall, William A

    2012-09-20

    Haploinsufficiency of the SCN1A gene encoding voltage-gated sodium channel Na(V)1.1 causes Dravet's syndrome, a childhood neuropsychiatric disorder including recurrent intractable seizures, cognitive deficit and autism-spectrum behaviours. The neural mechanisms responsible for cognitive deficit and autism-spectrum behaviours in Dravet's syndrome are poorly understood. Here we report that mice with Scn1a haploinsufficiency exhibit hyperactivity, stereotyped behaviours, social interaction deficits and impaired context-dependent spatial memory. Olfactory sensitivity is retained, but novel food odours and social odours are aversive to Scn1a(+/-) mice. GABAergic neurotransmission is specifically impaired by this mutation, and selective deletion of Na(V)1.1 channels in forebrain interneurons is sufficient to cause these behavioural and cognitive impairments. Remarkably, treatment with low-dose clonazepam, a positive allosteric modulator of GABA(A) receptors, completely rescued the abnormal social behaviours and deficits in fear memory in the mouse model of Dravet's syndrome, demonstrating that they are caused by impaired GABAergic neurotransmission and not by neuronal damage from recurrent seizures. These results demonstrate a critical role for Na(V)1.1 channels in neuropsychiatric functions and provide a potential therapeutic strategy for cognitive deficit and autism-spectrum behaviours in Dravet's syndrome.

  10. Adenosine Receptor Heteromers and their Integrative Role in Striatal Function

    Directory of Open Access Journals (Sweden)

    Sergi Ferré

    2007-01-01

    Full Text Available By analyzing the functional role of adenosine receptor heteromers, we review a series of new concepts that should modify our classical views of neurotransmission in the central nervous system (CNS. Neurotransmitter receptors cannot be considered as single functional units anymore. Heteromerization of neurotransmitter receptors confers functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Some of these characteristics can be used as a “biochemical fingerprint” to identify neurotransmitter receptor heteromers in the CNS. This is exemplified by changes in binding characteristics that are dependent on coactivation of the receptor units of different adenosine receptor heteromers. Neurotransmitter receptor heteromers can act as “processors” of computations that modulate cell signaling, sometimes critically involved in the control of pre- and postsynaptic neurotransmission. For instance, the adenosine A1-A2A receptor heteromer acts as a concentration-dependent switch that controls striatal glutamatergic neurotransmission. Neurotransmitter receptor heteromers play a particularly important integrative role in the “local module” (the minimal portion of one or more neurons and/or one or more glial cells that operates as an independent integrative unit, where they act as processors mediating computations that convey information from diverse volume-transmitted signals. For instance, the adenosine A2A-dopamine D2 receptor heteromers work as integrators of two different neurotransmitters in the striatal spine module.

  11. Cocaine Dysregulates Opioid Gating of GABA Neurotransmission in the Ventral Pallidum

    Science.gov (United States)

    Scofield, Michael D.; Rice, Kenner C.; Cheng, Kejun; Roques, Bernard P.

    2014-01-01

    The ventral pallidum (VP) is a target of dense nucleus accumbens projections. Many of these projections coexpress GABA and the neuropeptide enkephalin, a δ and μ opioid receptor (MOR) ligand. Of these two, the MOR in the VP is known to be involved in reward-related behaviors, such as hedonic responses to palatable food, alcohol intake, and reinstatement of cocaine seeking. Stimulating MORs in the VP decreases extracellular GABA, indicating that the effects of MORs in the VP on cocaine seeking are via modulating GABA neurotransmission. Here, we use whole-cell patch-clamp on a rat model of withdrawal from cocaine self-administration to test the hypothesis that MORs presynaptically regulate GABA transmission in the VP and that cocaine withdrawal changes the interaction between MORs and GABA. We found that in cocaine-extinguished rats pharmacological activation of MORs no longer presynaptically inhibited GABA release, whereas blocking the MORs disinhibited GABA release. Moreover, MOR-dependent long-term depression of GABA neurotransmission in the VP was lost in cocaine-extinguished rats. Last, GABA neurotransmission was found to be tonically suppressed in cocaine-extinguished rats. These substantial synaptic changes indicated that cocaine was increasing tone on MOR receptors. Accordingly, increasing endogenous tone by blocking the enzymatic degradation of enkephalin inhibited GABA neurotransmission in yoked saline rats but not in cocaine-extinguished rats. In conclusion, our results indicate that following withdrawal from cocaine self-administration enkephalin levels in the VP are elevated and the opioid modulation of GABA neurotransmission is impaired. This may contribute to the difficulties withdrawn addicts experience when trying to resist relapse. PMID:24431463

  12. Memory retrieval in response to partial cues requires NMDA receptor-dependent neurotransmission in the medial prefrontal cortex.

    Science.gov (United States)

    Jo, Yong Sang; Choi, June-Seek

    2014-03-01

    The medial prefrontal cortex (mPFC) has been suggested to play a crucial role in retrieving detailed contextual information about a previous learning episode in response to a single retrieval cue. However, few studies investigated the neurochemical mechanisms that mediate the prefrontal retrieval process. In the current study, we examined whether N-methyl-D-aspartate receptors (NMDARs) in the mPFC were necessary for retrieval of a well-learned spatial location on the basis of partial or degraded spatial cues. Rats were initially trained to find a hidden platform in the Morris water maze using four extramaze cues in the surrounding environment. Their retrieval performance was subsequently tested under different cue conditions. Infusions of DL-2-amino-5-phosphonovaleric acid (APV), a NMDAR antagonist, significantly disrupted memory retrieval when three of the original cues were removed. By contrast, APV injections into the mPFC did not affect animals' retrieval performance when the original cues were presented or when three novels landmarks were added alongside the original cues. These results indicate that prefrontal NMDARs are required for memory retrieval when allocentric spatial information is degraded. NMDAR-dependent neurotransmission in the mPFC may facilitate an active retrieval process to reactivate complete contextual representations associated with partial retrieval cues. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Kainate-induced network activity in the anterior cingulate cortex.

    Science.gov (United States)

    Shinozaki, R; Hojo, Y; Mukai, H; Hashizume, M; Murakoshi, T

    2016-06-14

    Anterior cingulate cortex (ACC) plays a pivotal role in higher order processing of cognition, attention and emotion. The network oscillation is considered an essential means for integration of these CNS functions. The oscillation power and coherence among related areas are often dis-regulated in several psychiatric and pathological conditions with a hemispheric asymmetric manner. Here we describe the network-based activity of field potentials recorded from the superficial layer of the mouse ACC in vitro using submerged type recordings. A short activation by kainic acid administration to the preparation induced populational activities ranging over several frequency bands including theta (3-8Hz), alpha (8-12Hz), beta (13-30Hz), low gamma (30-50Hz) and high gamma (50-80Hz). These responses were repeatable and totally abolished by tetrodotoxin, and greatly diminished by inhibitors of ionotropic and metabotropic glutamate receptors, GABAA receptor or gap-junctions. These observations suggest that the kainate-induced network activity can be a useful model of the network oscillation in the ACC circuit. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  14. Effects of Docosahexaenoic Acid on Neurotransmission

    OpenAIRE

    Tanaka, Kazuhiro; Farooqui, Akhlaq A.; Siddiqi, Nikhat J.; Alhomida, Abdullah S.; Ong, Wei-Yi

    2012-01-01

    Docosahexaenoic acid (DHA) is the major polyunsaturated fatty acid (PUFA) in the brain and a structural component of neuronal membranes. Changes in DHA content of neuronal membranes lead to functional changes in the activity of receptors and other proteins which might be associated with synaptic function. Accumulating evidence suggests the beneficial effects of dietary DHA supplementation on neurotransmission. This article reviews the beneficial effects of DHA on the brain; uptake, incorporat...

  15. Cell and Receptor Type-Specific Alterations in Markers of GABA Neurotransmission in the Prefrontal Cortex of Subjects with Schizophrenia

    OpenAIRE

    Lewis, David A.; Hashimoto, Takanori; Morris, Harvey M.

    2008-01-01

    Impairments in cognitive control, such as those involved in working memory, are associated with dysfunction of the dorsolateral prefrontal cortex (DLPFC) in individuals with schizophrenia. This dysfunction appears to result, at least in part, from abnormalities in GABA-mediated neurotransmission. In this paper, we review recent findings indicating that the altered DLPFC circuitry in subjects with schizophrenia reflects changes in the expression of genes that encode selective presynaptic and p...

  16. The dextromethorphan analog dimemorfan attenuates kainate-induced seizures via σ1 receptor activation: comparison with the effects of dextromethorphan

    Science.gov (United States)

    Shin, Eun-Joo; Nah, Seung-Yeol; Kim, Won-Ki; Ko, Kwang Ho; Jhoo, Wang-Kee; Lim, Yong-Kwang; Cha, Joo Young; Chen, Chieh-Fu; Kim, Hyoung-Chun

    2005-01-01

    In a previous study, we demonstrated that a dextromethorphan analog, dimemorfan, has neuroprotective effects. Dextromethorphan and dimemorfan are high-affinity ligands at σ1 receptors. Dextromethorphan has moderate affinities for phencyclidine sites, while dimemorfan has very low affinities for such sites, suggesting that these sites are not essential for the anticonvulsant actions of dimemorfan. Kainate (KA) administration (10 mg kg−1, i.p.) produced robust convulsions lasting 4–6 h in rats. Pre-treatment with dimemorfan (12 or 24 mg kg−1) reduced seizures in a dose-dependent manner. Dimemorfan pre-treatment also attenuated the KA-induced increases in c-fos/c-jun expression, activator protein (AP)-1 DNA-binding activity, and loss of cells in the CA1 and CA3 fields of the hippocampus. These effects of dimemorfan were comparable to those of dextromethorphan. The anticonvulsant action of dextromethorphan or dimemorfan was significantly counteracted by a selective σ1 receptor antagonist BD 1047, suggesting that the anticonvulsant action of dextromethorphan or dimemorfan is, at least in part, related to σ1 receptor-activated modulation of AP-1 transcription factors. We asked whether dimemorfan produces the behavioral side effects seen with dextromethorphan or dextrorphan (a phencyclidine-like metabolite of dextromethorphan). Conditioned place preference and circling behaviors were significantly increased in mice treated with phencyclidine, dextrorphan or dextromethorphan, while mice treated with dimemorfan showed no behavioral side effects. Our results suggest that dimemorfan is equipotent to dextromethorphan in preventing KA-induced seizures, while it may lack behavioral effects, such as psychotomimetic reactions. PMID:15723099

  17. Kainate receptors in the rat hippocampus: A distribution and time course of changes in response to unilateral lesions of the entorhinal cortex

    International Nuclear Information System (INIS)

    Ulas, J.; Monaghan, D.T.; Cotman, C.W.

    1990-01-01

    The response of kainate receptors to deafferentation and subsequent reinnervation following unilateral entorhinal cortex lesions was studied in the rat hippocampus using quantitative in vitro autoradiography. The binding levels of [3H]kainic acid (KA) and changes in the distribution of KA sites were investigated in the dentate gyrus molecular layer (ML) and in various terminal zones in the CA1 field at 1, 3, 7, 14, 21, 30, and 60 d postlesion. The data from both the ipsilateral and contralateral hippocampus were compared with those from unoperated controls. The first changes in KA receptor distribution were observed 21 d postlesion when the dense band of KA receptors occupying the inner one-third of the ML expanded into the denervated outer two-thirds of the ipsilateral ML. The spreading of the KA receptor field into previously unoccupied zones continued 30 and 60 d postlesion. At these time points, the zone enriched in [3H]KA binding sites became significantly (on average 50%) wider than in unoperated controls. No changes were observed in either the distribution or binding levels in other hippocampal areas or in the contralateral hippocampus at any studied time point. Saturation analysis of binding in the ipsilateral ML 60 d postlesion revealed changes in the maximum number of receptor sites (Bmax) without changes in KA receptor affinity (Kd). The data suggest that the elevation of the [3H]KA binding in the outer two-thirds of the ML reflects an increase in the number of both low and high affinity receptor binding sites. The pattern of KA receptor redistribution was similar to the well-characterized pattern of sprouting of commissural/associational systems from the inner one-third into the outer two-thirds of the ML after entorhinal lesions

  18. P2X receptor-mediated ATP purinergic signaling in health and disease

    Directory of Open Access Journals (Sweden)

    Jiang LH

    2012-09-01

    Full Text Available Lin-Hua JiangSchool of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United KingdomAbstract: Purinergic P2X receptors are plasma membrane proteins present in a wide range of mammalian cells where they act as a cellular sensor, enabling cells to detect and respond to extracellular adenosine triphosphate (ATP, an important signaling molecule. P2X receptors function as ligand-gated Ca2+-permeable cationic channels that open upon ATP binding to elevate intracellular Ca2+ concentrations and cause membrane depolarization. In response to sustained activation, P2X receptors induce formation of a pore permeable to large molecules. P2X receptors also interact with distinct functional proteins and membrane lipids to form specialized signaling complexes. Studies have provided compelling evidence to show that such P2X receptor-mediated ATP-signaling mechanisms determine and regulate a growing number and diversity of important physiological processes, including neurotransmission, muscle contraction, and cytokine release. There is accumulating evidence to support strong causative relationships of altered receptor expression and function with chronic pain, inflammatory diseases, cancers, and other pathologies or diseases. Numerous high throughput screening drug discovery programs and preclinical studies have thus far demonstrated the proof of concepts that the P2X receptors are druggable targets and selective receptor antagonism is a promising therapeutics approach. This review will discuss the recent progress in understanding the mammalian P2X receptors with respect to the ATP-signaling mechanisms, physiological and pathophysiological roles, and development and preclinical studies of receptor antagonists.Keywords: extracellular ATP, ion channel, large pore, signaling complex, chronic pain, inflammatory diseases

  19. Oxytocin receptor neurotransmission in the dorsolateral bed nucleus of the stria terminalis facilitates the acquisition of cued fear in the fear-potentiated startle paradigm in rats.

    Science.gov (United States)

    Moaddab, Mahsa; Dabrowska, Joanna

    2017-07-15

    Oxytocin (OT) is a hypothalamic neuropeptide that modulates fear and anxiety-like behaviors. Dorsolateral bed nucleus of the stria terminalis (BNST dl ) plays a critical role in the regulation of fear and anxiety, and expresses high levels of OT receptor (OTR). However, the role of OTR neurotransmission within the BNST dl in mediating these behaviors is unknown. Here, we used adult male Sprague-Dawley rats to investigate the role of OTR neurotransmission in the BNST dl in the modulation of the acoustic startle response, as well as in the acquisition and consolidation of conditioned fear using fear potentiated startle (FPS) paradigm. Bilateral intra-BNST dl administration of OT (100 ng) did not affect the acquisition of conditioned fear response. However, intra-BNST dl administration of specific OTR antagonist (OTA), (d(CH 2 ) 5 1 , Tyr(Me) 2 , Thr 4 , Orn 8 , des-Gly-NH 2 9 )-vasotocin, (200 ng), prior to the fear conditioning session, impaired the acquisition of cued fear, without affecting a non-cued fear component of FPS. Neither OTA, nor OT affected baseline startle or shock reactivity during fear conditioning. Therefore, the observed impairment of cued fear after OTA infusion resulted from the specific effect on the formation of cued fear. In contrast to the acquisition, neither OTA nor OT affected the consolidation of FPS, when administered after the completion of fear conditioning session. Taken together, these results reveal the important role of OTR neurotransmission in the BNST dl in the formation of conditioned fear to a discrete cue. This study also highlights the role of the BNST dl in learning to discriminate between threatening and safe stimuli. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Nitric oxide and the non-adrenergic non-cholinergic neurotransmission

    NARCIS (Netherlands)

    Boeckxstaens, G. E.; Pelckmans, P. A.

    1997-01-01

    In the early 1960s, the first evidence was reported demonstrating neurally mediated responses in the presence of adrenergic and cholinergic antagonists, leading to the introduction of the concept of non-adrenergic non-cholinergic neurotransmission. The inhibitory component of this part of the

  1. Structural basis of ligand recognition in 5-HT(3) receptors

    NARCIS (Netherlands)

    Kesters, D.; Thompson, A.J.; Brams, M.; van Elk, R.; Spurny, R.; Geitmann, M.; Villalgordo, J.M.; Guskov, A.; Danielson, U.H.; Lummis, S.C.R.; Smit, A.B.; Ulens, C.

    2013-01-01

    The 5-HT 3 receptor is a pentameric serotonin-gated ion channel, which mediates rapid excitatory neurotransmission and is the target of a therapeutically important class of anti-emetic drugs, such as granisetron. We report crystal structures of a binding protein engineered to recognize the agonist

  2. Mediator-dependent Nuclear Receptor Functions

    Science.gov (United States)

    Chen, Wei; Roeder, Robert

    2011-01-01

    As gene-specific transcription factors, nuclear hormone receptors are broadly involved in many important biological processes. Their function on target genes requires the stepwise assembly of different coactivator complexes that facilitate chromatin remodeling and subsequent preinitiation complex (PIC) formation and function. Mediator has proved to be a crucial, and general, nuclear receptor-interacting coactivator, with demonstrated functions in transcription steps ranging from chromatin remodeling to subsequent PIC formation and function. Here we discuss (i) our current understanding of pathways that nuclear receptors and other interacting cofactors employ to recruit Mediator to target gene enhancers and promoters, including conditional requirements for the strong NR-Mediator interactions mediated by the NR AF2 domain and the MED1 LXXLLL motifs and (ii) mechanisms by which Mediator acts to transmit signals from enhancer-bound nuclear receptors to the general transcription machinery at core promoters to effect PIC formation and function. PMID:21854863

  3. Glutamate receptor agonists

    DEFF Research Database (Denmark)

    Vogensen, Stine Byskov; Greenwood, Jeremy R; Bunch, Lennart

    2011-01-01

    The neurotransmitter (S)-glutamate [(S)-Glu] is responsible for most of the excitatory neurotransmission in the central nervous system. The effect of (S)-Glu is mediated by both ionotropic and metabotropic receptors. Glutamate receptor agonists are generally a-amino acids with one or more...... stereogenic centers due to strict requirements in the agonist binding pocket of the activated state of the receptor. By contrast, there are many examples of achiral competitive antagonists. The present review addresses how stereochemistry affects the activity of glutamate receptor ligands. The review focuses...... mainly on agonists and discusses stereochemical and conformational considerations as well as biostructural knowledge of the agonist binding pockets, which is useful in the design of glutamate receptor agonists. Examples are chosen to demonstrate how stereochemistry not only determines how the agonist...

  4. Increased cocaine self-administration in M4 muscarinic acetylcholine receptor knockout mice

    DEFF Research Database (Denmark)

    Schmidt, Lene Sørensen; Thomsen, Morgane; Weikop, Pia

    2011-01-01

    Rationale The reinforcing effects of cocaine are mediated by the mesolimbic dopamine system. Behavioral and neurochemical studies have shown that the cholinergic muscarinic M4 receptor subtype plays an important role in regulation of dopaminergic neurotransmission. Objectives Here we investigated...... of drug addiction...

  5. A subconvulsive dose of kainate selectively compromises astrocytic metabolism in the mouse brain in vivo.

    Science.gov (United States)

    Walls, Anne B; Eyjolfsson, Elvar M; Schousboe, Arne; Sonnewald, Ursula; Waagepetersen, Helle S

    2014-08-01

    Despite the well-established use of kainate as a model for seizure activity and temporal lobe epilepsy, most studies have been performed at doses giving rise to general limbic seizures and have mainly focused on neuronal function. Little is known about the effect of lower doses of kainate on cerebral metabolism and particularly that associated with astrocytes. We investigated astrocytic and neuronal metabolism in the cerebral cortex of adult mice after treatment with saline (controls), a subconvulsive or a mildly convulsive dose of kainate. A combination of [1,2-(13)C]acetate and [1-(13)C]glucose was injected and subsequent nuclear magnetic resonance spectroscopy of cortical extracts was employed to distinctively map astrocytic and neuronal metabolism. The subconvulsive dose of kainate led to an instantaneous increase in the cortical lactate content, a subsequent reduction in the amount of [4,5-(13)C]glutamine and an increase in the calculated astrocytic TCA cycle activity. In contrast, the convulsive dose led to decrements in the cortical content and (13)C labeling of glutamate, glutamine, GABA, and aspartate. Evidence is provided that astrocytic metabolism is affected by a subconvulsive dose of kainate, whereas a higher dose is required to affect neuronal metabolism. The cerebral glycogen content was dose-dependently reduced by kainate supporting a role for glycogen during seizure activity.

  6. Glutamate Receptors within the Mesolimbic Dopamine System Mediate Alcohol Relapse Behavior.

    Science.gov (United States)

    Eisenhardt, Manuela; Leixner, Sarah; Luján, Rafael; Spanagel, Rainer; Bilbao, Ainhoa

    2015-11-25

    Glutamatergic input within the mesolimbic dopamine (DA) pathway plays a critical role in the development of addictive behavior. Although this is well established for some drugs of abuse, it is not known whether glutamate receptors within the mesolimbic system are involved in mediating the addictive properties of chronic alcohol use. Here we evaluated the contribution of mesolimbic NMDARs and AMPARs in mediating alcohol-seeking responses induced by environmental stimuli and relapse behavior using four inducible mutant mouse lines lacking the glutamate receptor genes Grin1 or Gria1 in either DA transporter (DAT) or D1R-expressing neurons. We first demonstrate the lack of GluN1 or GluA1 in either DAT- or D1R-expressing neurons in our mutant mouse lines by colocalization studies. We then show that GluN1 and GluA1 receptor subunits within these neuronal subpopulations mediate the alcohol deprivation effect, while having no impact on context- plus cue-induced reinstatement of alcohol-seeking behavior. We further validated these results pharmacologically by demonstrating similar reductions in the alcohol deprivation effect after infusion of the NMDAR antagonist memantine into the nucleus accumbens and ventral tegmental area of control mice, and a rescue of the mutant phenotype via pharmacological potentiation of AMPAR activity using aniracetam. In conclusion, dopamine neurons as well as D1R-expressing medium spiny neurons and their glutamatergic inputs via NMDARs and AMPARs act in concert to influence relapse responses. These results provide a neuroanatomical and molecular substrate for relapse behavior and emphasize the importance of glutamatergic drugs in modulating relapse behavior. Here we provide genetic and pharmacological evidence that glutamate receptors within the mesolimbic dopamine system play an essential role in alcohol relapse. Using various inducible and site-specific transgenic mouse models and pharmacological validation experiments, we show that critical

  7. Endogenous opioid peptide-mediated neurotransmission in central and pericentral nuclei of the inferior colliculus recruits μ1-opioid receptor to modulate post-ictal antinociception.

    Science.gov (United States)

    Felippotti, Tatiana Tocchini; de Freitas, Renato Leonardo; Coimbra, Norberto Cysne

    2012-02-01

    The aim of the present work was to investigate the involvement of the μ1-endogenous opioid peptide receptor-mediated system in post-ictal antinociception. Antinociceptive responses were determined by the tail-flick test after pre-treatment with the selective μ1-opioid receptor antagonist naloxonazine, peripherally or centrally administered at different doses. Peripheral subchronic (24 h) pre-treatment with naloxonazine antagonised the antinociception elicited by tonic-clonic seizures. Acute (10 min) pre-treatment, however, did not have the same effect. In addition, microinjections of naloxonazine into the central, dorsal cortical and external cortical nuclei of the inferior colliculus antagonised tonic-clonic seizure-induced antinociception. Neither acute (10-min) peripheral pre-treatment with naloxonazine nor subchronic intramesencephalic blockade of μ1-opioid receptors resulted in consistent statistically significant differences in the severity of tonic-clonic seizures shown by Racine's index (1972), although the intracollicular specific antagonism of μ1-opioid receptor decreased the duration of seizures. μ1-Opioid receptors and the inferior colliculus have been implicated in several endogenous opioid peptide-mediated responses such as antinociception and convulsion. The present findings suggest the involvement of μ1-opiate receptors of central and pericentral nuclei of the inferior colliculus in the modulation of tonic-clonic seizures and in the organisation of post-ictal antinociception. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Anatomical and pharmacological characterization of excitatory amino acid receptors

    International Nuclear Information System (INIS)

    Monaghan, D.T.

    1985-01-01

    The majority of the excitatory neurotransmission in the vertebrate Central Nervous System is thought to be mediated by acidic amino acid neurotransmitters. However, relatively little is known about the excitatory amino acid receptors and their distribution within the CNS. By analyzing radioligand binding to purified synaptic plasma membranes and to thin tissue sections processed for autoradiography, multiple distinct binding sites were found. These binding sites exhibited the pharmacological properties indicative of the excitatory amino acid receptors, which had been identified by electrophysiological techniques. Specifically, L-[ 3 H]-glutamate and D-[ 3 H]-amino-5-phosphonopentanoate appear to label N-methyl-D-aspartate receptors, L-[ 3 H]-glutamate and [ 3 H]-kainic acid appear to label kainic acid receptors, and L-[ 3 H]-glutamate and [ 3 H]-amino-3-hydroxy-5-methyl-4-isoxazolepropionate appear to label quisqualate receptors. Together, these results confirm the three receptor scheme proposed for excitatory amino acid neurotransmission. These results also show that these transmitter-receptor systems are differentially distributed in the brain, and that the total distribution is consistent with that found by other markers for excitatory amino acid-using neurons

  9. Imaging of nitric oxide in nitrergic neuromuscular neurotransmission in the gut.

    Directory of Open Access Journals (Sweden)

    Hemant S Thatte

    Full Text Available Numerous functional studies have shown that nitrergic neurotransmission plays a central role in peristalsis and sphincter relaxation throughout the gut and impaired nitrergic neurotransmission has been implicated in clinical disorders of all parts of the gut. However, the role of nitric oxide (NO as a neurotransmitter continues to be controversial because: 1 the cellular site of production during neurotransmission is not well established; 2 NO may interacts with other inhibitory neurotransmitter candidates, making it difficult to understand its precise role.Imaging NO can help resolve many of the controversies regarding the role of NO in nitrergic neurotransmission. Imaging of NO and its cellular site of production is now possible. NO forms quantifiable fluorescent compound with diaminofluorescein (DAF and allows imaging of NO with good specificity and sensitivity in living cells. In this report we describe visualization and regulation of NO and calcium (Ca(2+ in the myenteric nerve varicosities during neurotransmission using multiphoton microscopy. Our results in mice gastric muscle strips provide visual proof that NO is produced de novo in the nitrergic nerve varicosities upon nonadrenergic noncholinergic (NANC nerve stimulation. These studies show that NO is a neurotransmitter rather than a mediator. Changes in NO production in response to various pharmacological treatments correlated well with changes in slow inhibitory junction potential of smooth muscles.Dual imaging and electrophysiologic studies provide visual proof that during nitrergic neurotransmission NO is produced in the nerve terminals. Such studies may help define whether NO production or its signaling pathway is responsible for impaired nitrergic neurotransmission in pathological states.

  10. Anxiety and Depression: Mouse Genetics and Pharmacological Approaches to the Role of GABAA Receptor Subtypes

    Science.gov (United States)

    Smith, Kiersten S.; Rudolph, Uwe

    2012-01-01

    GABAA receptors mediate fast synaptic inhibitory neurotransmission throughout the central nervous system. Recent work indicates a role for GABAA receptors in physiologically modulating anxiety and depression levels. In this review, we summarize research that led to the identification of the essential role of GABAA receptors in counteracting trait anxiety and depression-related behaviors, and research aimed at identifying individual GABAA receptor subtypes involved in physiological and pharmacological modulation of emotions. PMID:21810433

  11. Inhibition of GABAergic Neurotransmission by HIV-1 Tat and Opioid Treatment in the Striatum Involves μ-opioid Receptors

    Directory of Open Access Journals (Sweden)

    Changqing Xu

    2016-11-01

    Full Text Available Due to combined antiretroviral therapy (cART, human immunodeficiency virus type 1 (HIV-1 is considered a chronic disease with high prevalence of mild forms of neurocognitive impairments, also referred to as HIV-associated neurocognitive disorders (HAND. Although opiate drug use can exacerbate HIV-1 Tat-induced neuronal damage, it remains unknown how and to what extent opioids interact with Tat on the GABAergic system. We conducted whole-cell recordings in mouse striatal slices and examined the effects of HIV-1 Tat in the presence and absence of morphine (1 μM and damgo (1 μM on GABAergic neurotransmission. Results indicated a decrease in the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs and miniature IPSCs (mIPSCs by Tat (5 – 50 nM in a concentration-dependent manner. The significant Tat-induced decrease in IPSCs was abolished when removing extracellular and/or intracellular calcium. Treatment with morphine or damgo alone significantly decreased the frequency, but not amplitude of IPSCs. Interestingly, morphine but not damgo indicated an additional downregulation of the mean frequency of mIPSCs in combination with Tat. Pretreatment with naloxone (1 μM and CTAP (1 μM prevented the Tat-induced decrease in sIPSCs frequency but only naloxone prevented the combined Tat and morphine effect on mIPSCs frequency. Results indicate a Tat- or opioid-induced decrease in GABAergic neurotransmission via µ-opioid receptors with combined Tat and morphine effects involving additional opioid receptor-related mechanisms. Exploring the interactions between Tat and opioids on the GABAergic system may help to guide future research on HAND in the context of opiate drug use.

  12. Medicinal Chemistry of Competitive Kainate Receptor Antagonists

    Science.gov (United States)

    2010-01-01

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1−5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure−activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

  13. Selective increases of AMPA, NMDA and kainate receptor subunit mRNAs in the hippocampus and orbitofrontal cortex but not in prefrontal cortex of human alcoholics

    Directory of Open Access Journals (Sweden)

    Zhe eJin

    2014-01-01

    Full Text Available Glutamate is the main excitatory transmitter in the human brain. Drugs that affect the glutamatergic signaling will alter neuronal excitability. Ethanol inhibits glutamate receptors. We examined the expression level of glutamate receptor subunit mRNAs in human post-mortem samples from alcoholics and compared the results to brain samples from control subjects. RNA from hippocampal dentate gyrus (HP-DG, orbitofrontal cortex (OFC, and dorso-lateral prefrontal cortex (DL-PFC samples from 21 controls and 19 individuals with chronic alcohol dependence were included in the study. Total RNA was assayed using quantitative RT-PCR. Out of the 16 glutamate receptor subunits, mRNAs encoding two AMPA (2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-ylpropanoic acid receptor subunits GluA2 and GluA3; three kainate receptor subunits GluK2, GluK3 and GluK5 and five NMDA (N-methyl-D-aspartate receptor subunits GluN1, GluN2A, GluN2C, GluN2D and GluN3A were significantly increased in the HP-DG region in alcoholics. In the OFC, mRNA encoding the NMDA receptor subunit GluN3A was increased, whereas in the DL-PFC, no differences in mRNA levels were observed. Our laboratory has previously shown that the expression of genes encoding inhibitory GABA-A receptors is altered in the HP-DG and OFC of alcoholics (Jin et al., 2011. Whether the changes in one neurotransmitter system drives changes in the other or if they change independently is currently not known. The results demonstrate that excessive long-term alcohol consumption is associated with altered expression of genes encoding glutamate receptors in a brain region-specific manner. It is an intriguing possibility that genetic predisposition to alcoholism may contribute to these gene expression changes.

  14. Hypothesis: The Psychedelic Ayahuasca Heals Traumatic Memories via a Sigma 1 Receptor-Mediated Epigenetic-Mnemonic Process

    Directory of Open Access Journals (Sweden)

    Antonio Inserra

    2018-04-01

    Full Text Available Ayahuasca ingestion modulates brain activity, neurotransmission, gene expression and epigenetic regulation. N,N-Dimethyltryptamine (DMT, one of the alkaloids in Ayahuasca activates sigma 1 receptor (SIGMAR1 and others. SIGMAR1 is a multi-faceted stress-responsive receptor which promotes cell survival, neuroprotection, neuroplasticity, and neuroimmunomodulation. Simultaneously, monoamine oxidase inhibitors (MAOIs also present in Ayahuasca prevent the degradation of DMT. One peculiarity of SIGMAR1 activation and MAOI activity is the reversal of mnemonic deficits in pre-clinical models. Since traumatic memories in post-traumatic stress disorder (PTSD are often characterised by “repression” and PTSD patients ingesting Ayahuasca report the retrieval of such memories, it cannot be excluded that DMT-mediated SIGMAR1 activation and the concomitant MAOIs effects during Ayahuasca ingestion might mediate such “anti-amnesic” process. Here I hypothesise that Ayahuasca, via hyperactivation of trauma and emotional memory-related centres, and via its concomitant SIGMAR1- and MAOIs- induced anti-amnesic effects, facilitates the retrieval of traumatic memories, in turn making them labile (destabilised. As Ayahuasca alkaloids enhance synaptic plasticity, increase neurogenesis and boost dopaminergic neurotransmission, and those processes are involved in memory reconsolidation and fear extinction, the fear response triggered by the memory can be reprogramed and/or extinguished. Subsequently, the memory is stored with this updated significance. To date, it is unclear if new memories replace, co-exist with or bypass old ones. Although the mechanisms involved in memory are still debated, they seem to require the involvement of cellular and molecular events, such as reorganisation of homo and heteroreceptor complexes at the synapse, synaptic plasticity, and epigenetic re-modulation of gene expression. Since SIGMAR1 mobilises synaptic receptor, boosts synaptic

  15. Hypothesis: The Psychedelic Ayahuasca Heals Traumatic Memories via a Sigma 1 Receptor-Mediated Epigenetic-Mnemonic Process.

    Science.gov (United States)

    Inserra, Antonio

    2018-01-01

    Ayahuasca ingestion modulates brain activity, neurotransmission, gene expression and epigenetic regulation. N,N -Dimethyltryptamine (DMT, one of the alkaloids in Ayahuasca) activates sigma 1 receptor (SIGMAR1) and others. SIGMAR1 is a multi-faceted stress-responsive receptor which promotes cell survival, neuroprotection, neuroplasticity, and neuroimmunomodulation. Simultaneously, monoamine oxidase inhibitors (MAOIs) also present in Ayahuasca prevent the degradation of DMT. One peculiarity of SIGMAR1 activation and MAOI activity is the reversal of mnemonic deficits in pre-clinical models. Since traumatic memories in post-traumatic stress disorder (PTSD) are often characterised by "repression" and PTSD patients ingesting Ayahuasca report the retrieval of such memories, it cannot be excluded that DMT-mediated SIGMAR1 activation and the concomitant MAOIs effects during Ayahuasca ingestion might mediate such "anti-amnesic" process. Here I hypothesise that Ayahuasca, via hyperactivation of trauma and emotional memory-related centres, and via its concomitant SIGMAR1- and MAOIs- induced anti-amnesic effects, facilitates the retrieval of traumatic memories, in turn making them labile (destabilised). As Ayahuasca alkaloids enhance synaptic plasticity, increase neurogenesis and boost dopaminergic neurotransmission, and those processes are involved in memory reconsolidation and fear extinction, the fear response triggered by the memory can be reprogramed and/or extinguished. Subsequently, the memory is stored with this updated significance. To date, it is unclear if new memories replace, co-exist with or bypass old ones. Although the mechanisms involved in memory are still debated, they seem to require the involvement of cellular and molecular events, such as reorganisation of homo and heteroreceptor complexes at the synapse, synaptic plasticity, and epigenetic re-modulation of gene expression. Since SIGMAR1 mobilises synaptic receptor, boosts synaptic plasticity and modulates

  16. Glutamate Receptors in the Central Nucleus of the Amygdala Mediate Cisplatin-Induced Malaise and Energy Balance Dysregulation through Direct Hindbrain Projections.

    Science.gov (United States)

    Alhadeff, Amber L; Holland, Ruby A; Nelson, Alexandra; Grill, Harvey J; De Jonghe, Bart C

    2015-08-05

    Cisplatin chemotherapy is used commonly to treat a variety of cancers despite severe side effects such as nausea, vomiting, and anorexia that compromise quality of life and limit treatment adherence. The neural mechanisms mediating these side effects remain elusive despite decades of clinical use. Recent data highlight the dorsal vagal complex (DVC), lateral parabrachial nucleus (lPBN), and central nucleus of the amygdala (CeA) as potential sites of action in mediating the side effects of cisplatin. Here, results from immunohistochemical studies in rats identified a population of cisplatin-activated DVC neurons that project to the lPBN and a population of cisplatin-activated lPBN calcitonin gene-related peptide (CGRP, a marker for glutamatergic neurons in the lPBN) neurons that project to the CeA, outlining a neuroanatomical circuit that is activated by cisplatin. CeA gene expressions of AMPA and NMDA glutamate receptor subunits were markedly increased after cisplatin treatment, suggesting that CeA glutamate receptor signaling plays a role in mediating cisplatin side effects. Consistent with gene expression results, behavioral/pharmacological data showed that CeA AMPA/kainate receptor blockade attenuates cisplatin-induced pica (a proxy for nausea/behavioral malaise in nonvomiting laboratory rodents) and that CeA NMDA receptor blockade attenuates cisplatin-induced anorexia and body weight loss in addition to pica, demonstrating that glutamate receptor signaling in the CeA is critical for the energy balance dysregulation caused by cisplatin treatment. Together, these data highlight a novel circuit and CGRP/glutamatergic mechanism through which cisplatin-induced malaise and energy balance dysregulation are mediated. To treat cancer effectively, patients must follow prescribed chemotherapy treatments without interruption, yet most cancer treatments produce side effects that devastate quality of life (e.g., nausea, vomiting, anorexia, weight loss). Although hundreds of

  17. Glutamate Receptors in the Central Nucleus of the Amygdala Mediate Cisplatin-Induced Malaise and Energy Balance Dysregulation through Direct Hindbrain Projections

    Science.gov (United States)

    Alhadeff, Amber L.; Holland, Ruby A.; Nelson, Alexandra; Grill, Harvey J.

    2015-01-01

    Cisplatin chemotherapy is used commonly to treat a variety of cancers despite severe side effects such as nausea, vomiting, and anorexia that compromise quality of life and limit treatment adherence. The neural mechanisms mediating these side effects remain elusive despite decades of clinical use. Recent data highlight the dorsal vagal complex (DVC), lateral parabrachial nucleus (lPBN), and central nucleus of the amygdala (CeA) as potential sites of action in mediating the side effects of cisplatin. Here, results from immunohistochemical studies in rats identified a population of cisplatin-activated DVC neurons that project to the lPBN and a population of cisplatin-activated lPBN calcitonin gene-related peptide (CGRP, a marker for glutamatergic neurons in the lPBN) neurons that project to the CeA, outlining a neuroanatomical circuit that is activated by cisplatin. CeA gene expressions of AMPA and NMDA glutamate receptor subunits were markedly increased after cisplatin treatment, suggesting that CeA glutamate receptor signaling plays a role in mediating cisplatin side effects. Consistent with gene expression results, behavioral/pharmacological data showed that CeA AMPA/kainate receptor blockade attenuates cisplatin-induced pica (a proxy for nausea/behavioral malaise in nonvomiting laboratory rodents) and that CeA NMDA receptor blockade attenuates cisplatin-induced anorexia and body weight loss in addition to pica, demonstrating that glutamate receptor signaling in the CeA is critical for the energy balance dysregulation caused by cisplatin treatment. Together, these data highlight a novel circuit and CGRP/glutamatergic mechanism through which cisplatin-induced malaise and energy balance dysregulation are mediated. SIGNIFICANCE STATEMENT To treat cancer effectively, patients must follow prescribed chemotherapy treatments without interruption, yet most cancer treatments produce side effects that devastate quality of life (e.g., nausea, vomiting, anorexia, weight loss

  18. Morphology and kainate-receptor immunoreactivity of identified neurons within the entorhinal cortex projecting to superior temporal sulcus in the cynomolgus monkey

    Science.gov (United States)

    Good, P. F.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    Projections of the entorhinal cortex to the hippocampus are well known from the classical studies of Cajal (Ramon y Cajal, 1904) and Lorente de No (1933). Projections from the entorhinal cortex to neocortical areas are less well understood. Such connectivity is likely to underlie the consolidation of long-term declarative memory in neocortical sites. In the present study, a projection arising in layer V of the entorhinal cortex and terminating in a polymodal association area of the superior temporal gyrus has been identified with the use of retrograde tracing. The dendritic arbors of neurons giving rise to this projection were further investigated by cell filling and confocal microscopy with computer reconstruction. This analysis demonstrated that the dendritic arbor of identified projection neurons was largely confined to layer V, with the exception of a solitary, simple apical dendrite occasionally ascending to superficial laminae but often confined to the lamina dissecans (layer IV). Finally, immunoreactivity for glutamate-receptor subunit proteins GluR 5/6/7 of the dendritic arbor of identified entorhinal projection neurons was examined. The solitary apical dendrite of identified entorhinal projection neurons was prominently immunolabeled for GluR 5/6/7, as was the dendritic arbor of basilar dendrites of these neurons. The restriction of the large bulk of the dendritic arbor of identified entorhinal projection neurons to layer V implies that these neurons are likely to be heavily influenced by hippocampal output arriving in the deep layers of the entorhinal cortex. Immunoreactivity for GluR 5/6/7 throughout the dendritic arbor of such neurons indicates that this class of glutamate receptor is in a position to play a prominent role in mediating excitatory neurotransmission within hippocampal-entorhinal circuits.

  19. D-aspartate and NMDA, but not L-aspartate, block AMPA receptors in rat hippocampal neurons

    DEFF Research Database (Denmark)

    Gong, Xiang-Qun; Frandsen, Anne; Lu, Wei-Yang

    2005-01-01

    1 The amino acid, D-aspartate, exists in the mammalian brain and is an agonist at the N-methyl-D-aspartate (NMDA) subtype of ionotropic glutamate receptors. Here, for the first time, we studied the actions of D-aspartate on alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptors (AMPARs......) in acutely isolated rat hippocampal neurons. 2 In the presence of the NMDA receptor channel blocker, MK801, D-aspartate inhibited kainate-induced AMPAR current in hippocampal neurons. The inhibitory action of D-aspartate on kainate-induced AMPAR current was concentration-dependent and was voltage......-independent in the tested voltage range (-80 to +60 mV). 3 The estimated EC50 of the L-glutamate-induced AMPAR current was increased in the presence of D-aspartate, while the estimated maximum L-glutamate-induced AMPAR current was not changed. D-aspartate concentration-dependently shifted the dose-response curve of kainate...

  20. Novel Functional Properties of Drosophila CNS Glutamate Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Dharkar, Poorva; Han, Tae-Hee; Serpe, Mihaela; Lee, Chi-Hon; Mayer, Mark L.

    2016-12-01

    Phylogenetic analysis reveals AMPA, kainate, and NMDA receptor families in insect genomes, suggesting conserved functional properties corresponding to their vertebrate counterparts. However, heterologous expression of the Drosophila kainate receptor DKaiR1D and the AMPA receptor DGluR1A revealed novel ligand selectivity at odds with the classification used for vertebrate glutamate receptor ion channels (iGluRs). DKaiR1D forms a rapidly activating and desensitizing receptor that is inhibited by both NMDA and the NMDA receptor antagonist AP5; crystallization of the KaiR1D ligand-binding domain reveals that these ligands stabilize open cleft conformations, explaining their action as antagonists. Surprisingly, the AMPA receptor DGluR1A shows weak activation by its namesake agonist AMPA and also by quisqualate. Crystallization of the DGluR1A ligand-binding domain reveals amino acid exchanges that interfere with binding of these ligands. The unexpected ligand-binding profiles of insect iGluRs allows classical tools to be used in novel approaches for the study of synaptic regulation.

  1. A subconvulsive dose of kainate selectively compromises astrocytic metabolism in the mouse brain in vivo

    DEFF Research Database (Denmark)

    Walls, Anne B; Eyjolfsson, Elvar M; Schousboe, Arne

    2014-01-01

    Despite the well-established use of kainate as a model for seizure activity and temporal lobe epilepsy, most studies have been performed at doses giving rise to general limbic seizures and have mainly focused on neuronal function. Little is known about the effect of lower doses of kainate on cere...

  2. Elevated dopamine D1 receptor availability in striatum of Göttingen minipigs after electroconvulsive therapy

    DEFF Research Database (Denmark)

    Landau, Anne M; Alstrup, Aage Ko; Audrain, Helene

    2018-01-01

    Electroconvulsive therapy (ECT), a direct form of brain stimulation, is an effective antidepressant. We hypothesized that the beneficial effects of ECT are mediated by increased dopaminergic neurotransmission, in which the baseline activity of D1 receptors may predict the response to ECT. We esta......, the baseline binding capacity of D1 receptors predicts the magnitude of increased binding, up to a maximum binding capacity....

  3. Pesticides Drive Stochastic Changes in the Chemoreception and Neurotransmission System of Marine Ectoparasites

    Directory of Open Access Journals (Sweden)

    Gustavo Núñez-Acuña

    2016-05-01

    Full Text Available Scientific efforts to elucidate the mechanisms of chemical communication between organisms in marine environments are increasing. This study applied novel molecular technology to outline the effects of two xenobiotic drugs, deltamethrin (DM and azamethiphos (AZA, on the neurotransmission system of the copepod ectoparasite Caligus rogercresseyi. Transcriptome sequencing and bioinformatics analyses were conducted to evaluate treatment effects on the glutamatergic synaptic pathway of the parasite, which is closely related to chemoreception and neurotransmission. After drug treatment with DM or AZA, stochastic mRNA expression patterns of glutamatergic synapse pathway components were observed. Both DM and AZA promoted a down-regulation of the glutamate-ammonia ligase, and DM activated a metabotropic glutamate receptor that is a suggested inhibitor of neurotransmission. Furthermore, the delousing drugs drove complex rearrangements in the distribution of mapped reads for specific metabotropic glutamate receptor domains. This study introduces a novel methodological approach that produces high-quality results from transcriptomic data. Using this approach, DM and AZA were found to alter the expression of numerous mRNAs tightly linked to the glutamatergic signaling pathway. These data suggest possible new targets for xenobiotic drugs that play key roles in the delousing effects of antiparasitics in sea lice.

  4. Presynaptic Glycine Receptors Increase GABAergic Neurotransmission in Rat Periaqueductal Gray Neurons

    Directory of Open Access Journals (Sweden)

    Kwi-Hyung Choi

    2013-01-01

    Full Text Available The periaqueductal gray (PAG is involved in the central regulation of nociceptive transmission by affecting the descending inhibitory pathway. In the present study, we have addressed the functional role of presynaptic glycine receptors in spontaneous glutamatergic transmission. Spontaneous EPSCs (sEPSCs were recorded in mechanically dissociated rat PAG neurons using a conventional whole-cell patch recording technique under voltage-clamp conditions. The application of glycine (100 µM significantly increased the frequency of sEPSCs, without affecting the amplitude of sEPSCs. The glycine-induced increase in sEPSC frequency was blocked by 1 µM strychnine, a specific glycine receptor antagonist. The results suggest that glycine acts on presynaptic glycine receptors to increase the probability of glutamate release from excitatory nerve terminals. The glycine-induced increase in sEPSC frequency completely disappeared either in the presence of tetrodotoxin or Cd2+, voltage-gated Na+, or Ca2+ channel blockers, suggesting that the activation of presynaptic glycine receptors might depolarize excitatory nerve terminals. The present results suggest that presynaptic glycine receptors can regulate the excitability of PAG neurons by enhancing glutamatergic transmission and therefore play an important role in the regulation of various physiological functions mediated by the PAG.

  5. Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB₁ receptor blockade.

    Science.gov (United States)

    Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

    2013-03-19

    Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.

  6. Clinical results of neurotransmission SPECT in extra-pyramidal diseases; Resultats cliniques de la TEMP de la neurotransmission en pathologie extra-pyramidale

    Energy Technology Data Exchange (ETDEWEB)

    Baulieu, J.L.; Prunier, C.; Tranquart, F.; Guilloteau, D. [Centre Hospitalier Universitaire Bretonneau, Service de Medecine Nucleaire in vitro, INSERM U316, 37 - Tours (France)

    1999-12-01

    We present some methodological aspects and clinical applications of dopamine D2 receptor and transporter SPECT using new radiotracers radiolabeled with iodine 123. The gamma camera quality control and standardisation has to be adapted to the small volume and deep location of striata, where receptors and transporters are present. Phantom containing hollow spheres of different diameters which can be filled with different amounts of {sup 99m}Tc or {sup 123}I. The semi quantitation of receptor and transporter molecular concentration is based on an equilibrium binding model. According to this model, the binding potential (Bmax. Ka) is equal to the ratio between specific binding in the striatum and circulating activity in a reference region of interest in the occipital cortex. By comparing ECD and ILIS SPECT, it has been shown that striatal ILIS binding does not depend on the local perfusion. The clinical applications mainly concern the extra-pyramidal pathology: ILIS and IBZM SPECT are able to differentiate pre- and post-synaptic lesions. In Parkinson disease the nigrostriatal pathway is damaged and D2 receptors are normal or increased, as shown by normal or elevated IBZM or ILIS uptake. In other extra pyramidal degenerative diseases as progressive supra nuclear palsy or multiple system atrophy striatal D2 receptors are damaged as shown by decreased IBZM or ILIS uptake. In our experience, 88 per cent of patients are correctly classified by ILIS SPECT and 86 per cent with IBZM SPECT. Dopamine transporter SPECT with {beta}CIT and PE2I provides an evaluation of the presynaptic neuronal density in the striatum. One can expect an help for the early diagnosis and the evaluation of Parkinson disease. Another potential application of dopaminergic neurotransmission SPECT is the evaluation of neuronal loss after hypoxo-ischemia. We conclude that dopaminergic neurotransmission SPECT using specific ligands should become a useful diagnosis tool to study a large number of brain

  7. Interplay between glutamatergic and GABAergic neurotransmission alterations in cognitive and motor impairment in minimal hepatic encephalopathy.

    Science.gov (United States)

    Llansola, Marta; Montoliu, Carmina; Agusti, Ana; Hernandez-Rabaza, Vicente; Cabrera-Pastor, Andrea; Gomez-Gimenez, Belen; Malaguarnera, Michele; Dadsetan, Sherry; Belghiti, Majedeline; Garcia-Garcia, Raquel; Balzano, Tiziano; Taoro, Lucas; Felipo, Vicente

    2015-09-01

    The cognitive and motor alterations in hepatic encephalopathy (HE) are the final result of altered neurotransmission and communication between neurons in neuronal networks and circuits. Different neurotransmitter systems cooperate to modulate cognitive and motor function, with a main role for glutamatergic and GABAergic neurotransmission in different brain areas and neuronal circuits. There is an interplay between glutamatergic and GABAergic neurotransmission alterations in cognitive and motor impairment in HE. This interplay may occur: (a) in different brain areas involved in specific neuronal circuits; (b) in the same brain area through cross-modulation of glutamatergic and GABAergic neurotransmission. We will summarize some examples of the (1) interplay between glutamatergic and GABAergic neurotransmission alterations in different areas in the basal ganglia-thalamus-cortex circuit in the motor alterations in minimal hepatic encephalopathy (MHE); (2) interplay between glutamatergic and GABAergic neurotransmission alterations in cerebellum in the impairment of cognitive function in MHE through altered function of the glutamate-nitric oxide-cGMP pathway. We will also comment the therapeutic implications of the above studies and the utility of modulators of glutamate and GABA receptors to restore cognitive and motor function in rats with hyperammonemia and hepatic encephalopathy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. The effect of Vitamin E on learning and memory deficits in intrahippocampal kainate-induced temporal lobe epilepsy in rats.

    Science.gov (United States)

    Kiasalari, Zahra; Khalili, Mohsen; Shafiee, Samaneh; Roghani, Mehrdad

    2016-01-01

    Since temporal lobe epilepsy (TLE) is associated with learning and memory impairment, we investigated the beneficial effect of Vitamin E on the impaired learning and memory in the intrahippocampal kainate model of TLE in rats. Rats were divided into sham, Vitamin E-treated sham, kainate, and Vitamin E-treated kainate. Intrahippocampal kainate was used for induction of epilepsy. Vitamin E was injected intraperitoneal (i.p.) at a dose of 200 mg/kg/day started 1 week before surgery until 1 h presurgery. Initial and step-through latencies in the passive avoidance test and alternation behavior percentage in Y-maze were finally determined in addition to measurement of some oxidative stress markers. Kainate injection caused a higher severity and rate of seizures and deteriorated learning and memory performance in passive avoidance paradigm and spontaneous alternation as an index of spatial recognition memory in Y-maze task. Intrahippocampal kainate also led to the elevation of malondialdehyde (MDA) and nitrite and reduced activity of superoxide dismutase (SOD). Vitamin E pretreatment significantly attenuated severity and incidence rate of seizures, significantly improved retrieval and recall in passive avoidance, did not ameliorate spatial memory deficit in Y-maze, and lowered MDA and enhanced SOD activity. Vitamin E improves passive avoidance learning and memory and part of its beneficial effect is due to its potential to mitigate hippocampal oxidative stress.

  9. γ1-Containing GABA-A Receptors Cluster at Synapses Where they Mediate Slower Synaptic Currents than γ2-Containing GABA-A Receptors

    Directory of Open Access Journals (Sweden)

    Christine L. Dixon

    2017-06-01

    Full Text Available GABA-A receptors (GABAARs are pentameric ligand-gated ion channels that are assembled mainly from α (α1–6, β (β1–3 and γ (γ1–3 subunits. Although GABAARs containing γ2L subunits mediate most of the inhibitory neurotransmission in the brain, significant expression of γ1 subunits is seen in the amygdala, pallidum and substantia nigra. However, the location and function of γ1-containing GABAARs in these regions remains unclear. In “artificial” synapses, where the subunit composition of postsynaptic receptors is specifically controlled, γ1 incorporation slows the synaptic current decay rate without affecting channel deactivation, suggesting that γ1-containing receptors are not clustered and therefore activated by diffuse neurotransmitter. However, we show that γ1-containing receptors are localized at neuronal synapses and form clusters in both synaptic and extrasynaptic regions. In addition, they exhibit rapid membrane diffusion and a higher frequency of exchange between synaptic and perisynaptic populations compared to γ2L-containing GABAARs. A point mutation in the large intracellular domain and a pharmacological analysis reveal that when a single non-conserved γ2L residue is mutated to its γ1 counterpart (T349L, the synaptic current decay is slowed from γ2L- to γ1-like without changing the clustering or diffusion properties of the receptors. In addition, previous fast perfusion and single channel kinetic experiments revealed no difference in the intrinsic closing rates of γ2L- and γ1-containing receptors when expressed in HEK293 cells. These observations together with Monte Carlo simulations of synaptic function confirm that decreased clustering does not control γ1-containing GABAAR kinetics. Rather, they suggest that γ1- and γ2L-containing receptors exhibit differential synaptic current decay rates due to differential gating dynamics when localized at the synapse.

  10. Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB1 receptor blockade

    Science.gov (United States)

    Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

    2013-01-01

    Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors. PMID:23487769

  11. Intracellular Physiology of the Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators

    Science.gov (United States)

    1992-01-10

    Physiology of the Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators . I-f 12. PERSONAL AUTHOR(S) F...interplay between intrinsic electrophysiological properties, amino-acid-mediated synaptic transmission, and neuromodulation . We have continued to study the

  12. An N-methyl-D-aspartate receptor mediated large, low-frequency, spontaneous excitatory postsynaptic current in neonatal rat spinal dorsal horn neurons.

    Science.gov (United States)

    Thomson, L M; Zeng, J; Terman, G W

    2006-09-01

    Examples of spontaneous oscillating neural activity contributing to both pathological and physiological states are abundant throughout the CNS. Here we report a spontaneous oscillating intermittent synaptic current located in lamina I of the neonatal rat spinal cord dorsal horn. The spontaneous oscillating intermittent synaptic current is characterized by its large amplitude, slow decay time, and low-frequency. We demonstrate that post-synaptic N-methyl-D-aspartate receptors (NMDARs) mediate the spontaneous oscillating intermittent synaptic current, as it is inhibited by magnesium, bath-applied d-2-amino-5-phosphonovalerate (APV), or intracellular MK-801. The NR2B subunit of the NMDAR appears important to this phenomenon, as the NR2B subunit selective NMDAR antagonist, alpha-(4-hydroxphenyl)-beta-methyl-4-benzyl-1-piperidineethanol tartrate (ifenprodil), also partially inhibited the spontaneous oscillating intermittent synaptic current. Inhibition of spontaneous glutamate release by the AMPA/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or the mu-opioid receptor agonist [D-Ala2, N-Me-Phe4, Gly5] enkephalin-ol (DAMGO) inhibited the spontaneous oscillating intermittent synaptic current frequency. Marked inhibition of spontaneous oscillating intermittent synaptic current frequency by tetrodotoxin (TTX), but not post-synaptic N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium bromide (QX-314), suggests that the glutamate release important to the spontaneous oscillating intermittent synaptic current is dependent on active neural processes. Conversely, increasing dorsal horn synaptic glutamate release by GABAA or glycine inhibition increased spontaneous oscillating intermittent synaptic current frequency. Moreover, inhibiting glutamate transporters with threo-beta-benzyloxyaspartic acid (DL-TBOA) increased spontaneous oscillating intermittent synaptic current frequency and decay time. A possible functional role of this spontaneous NMDAR-mediated

  13. Pathological effects of chronic myocardial infarction on peripheral neurons mediating cardiac neurotransmission.

    Science.gov (United States)

    Nakamura, Keijiro; Ajijola, Olujimi A; Aliotta, Eric; Armour, J Andrew; Ardell, Jeffrey L; Shivkumar, Kalyanam

    2016-05-01

    To determine whether chronic myocardial infarction (MI) induces structural and neurochemical changes in neurons within afferent and efferent ganglia mediating cardiac neurotransmission. Neuronal somata in i) right atrial (RAGP) and ii) ventral interventricular ganglionated plexi (VIVGP), iii) stellate ganglia (SG) and iv) T1-2 dorsal root ganglia (DRG) bilaterally derived from normal (n=8) vs. chronic MI (n=8) porcine subjects were studied. We examined whether the morphology and neuronal nitric oxide synthase (nNOS) expression in soma of RAGP, VIVGP, DRG and SG neurons were altered as a consequence of chronic MI. In DRG, we also examined immunoreactivity of calcitonin gene related peptide (CGRP), a marker of afferent neurons. Chronic MI increased neuronal size and nNOS immunoreactivity in VIVGP (but not RAGP), as well as in the SG bilaterally. Across these ganglia, the increase in neuronal size was more pronounced in nNOS immunoreactive neurons. In the DRG, chronic MI also caused neuronal enlargement, and increased CGRP immunoreactivity. Further, DRG neurons expressing both nNOS and CGRP were increased in MI animals compared to controls, and represented a shift from double negative neurons. Chronic MI impacts diverse elements within the peripheral cardiac neuraxis. That chronic MI imposes such widespread, diverse remodeling of the peripheral cardiac neuraxis must be taken into consideration when contemplating neuronal regulation of the ischemic heart. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. PATHOLOGICAL EFFECTS OF CHRONIC MYOCARDIAL INFARCTION ON PERIPHERAL NEURONS MEDIATING CARDIAC NEUROTRANSMISSION

    Science.gov (United States)

    Nakamura, Keijiro; Ajijola, Olujimi A.; Aliotta, Eric; Armour, J. Andrew; Ardell, Jeffrey L.; Shivkumar, Kalyanam

    2016-01-01

    Objective To determine whether chronic myocardial infarction (MI) induces structural and neurochemical changes in neurons within afferent and efferent ganglia mediating cardiac neurotransmission. Methods Neuronal somata in i) right atrial (RAGP) and ii) ventral interventricular ganglionated plexi (VIVGP), iii) stellate ganglia (SG) and iv) T1-2 dorsal root ganglia (DRG) bilaterally derived from normal (n = 8) vs. chronic MI (n = 8) porcine subjects were studied. We examined whether the morphology and neuronal nitric oxide synthase (nNOS) expression in soma of RAGP, VIVGP, DRG and SG neurons were altered as a consequence of chronic MI. In DRG, we also examined immunoreactivity of calcitonin gene related peptide (CGRP), a marker of afferent neurons. Results Chronic MI increased neuronal size and nNOS immunoreactivity in VIVGP (but not RAGP), as well as in the SG bilaterally. Across these ganglia, the increase in neuronal size was more pronounced in nNOS immunoreacitive neurons. In the DRG, chronic MI also caused neuronal enlargement, and increased CGRP immunoreactivity. Further, DRG neurons expressing both nNOS and CGRP were increased in MI animals compared to controls, and represented a shift from double negative neurons. Conclusions Chronic MI impacts diverse elements within the peripheral cardiac neuraxis. That chronic MI imposes such widespread, diverse remodeling of the peripheral cardiac neuraxis must be taken into consideration when contemplating neuronal regulation of the ischemic heart. PMID:27209472

  15. Receptor-heteromer mediated regulation of endocannabinoid signaling in activated microglia. Role of CB1 and CB2 receptors and relevance for Alzheimer's disease and levodopa-induced dyskinesia.

    Science.gov (United States)

    Navarro, Gemma; Borroto-Escuela, Dasiel; Angelats, Edgar; Etayo, Íñigo; Reyes-Resina, Irene; Pulido-Salgado, Marta; Rodríguez-Pérez, Ana I; Canela, Enric I; Saura, Josep; Lanciego, José Luis; Labandeira-García, José Luis; Saura, Carlos A; Fuxe, Kjell; Franco, Rafael

    2018-01-01

    Endocannabinoids are important regulators of neurotransmission and, acting on activated microglia, they are postulated as neuroprotective agents. Endocannabinoid action is mediated by CB 1 and CB 2 receptors, which may form heteromeric complexes (CB 1 -CB 2 Hets) with unknown function in microglia. We aimed at establishing the expression and signaling properties of cannabinoid receptors in resting and LPS/IFN-γ-activated microglia. In activated microglia mRNA transcripts increased (2 fold for CB 1 and circa 20 fold for CB 2 ), whereas receptor levels were similar for CB 1 and markedly upregulated for CB 2 ; CB 1 -CB 2 Hets were also upregulated. Unlike in resting cells, CB 2 receptors became robustly coupled to G i in activated cells, in which CB 1 -CB 2 Hets mediated a potentiation effect. Hence, resting cells were refractory while activated cells were highly responsive to cannabinoids. Interestingly, similar results were obtained in cultures treated with ß-amyloid (Aß 1-42 ). Microglial activation markers were detected in the striatum of a Parkinson's disease (PD) model and, remarkably, in primary microglia cultures from the hippocampus of mutant β-amyloid precursor protein (APP Sw,Ind ) mice, a transgenic Alzheimer's disease (AD) model. Also of note was the similar cannabinoid receptor signaling found in primary cultures of microglia from APP Sw,Ind and in cells from control animals activated using LPS plus IFN-γ. Expression of CB 1 -CB 2 Hets was increased in the striatum from rats rendered dyskinetic by chronic levodopa treatment. In summary, our results showed sensitivity of activated microglial cells to cannabinoids, increased CB 1 -CB 2 Het expression in activated microglia and in microglia from the hippocampus of an AD model, and a correlation between levodopa-induced dyskinesia and striatal microglial activation in a PD model. Cannabinoid receptors and the CB 1 -CB 2 heteroreceptor complex in activated microglia have potential as targets in the

  16. 5-Hydroxytryptamine 1A/7 and 4alpha receptors differentially prevent opioid-induced inhibition of brain stem cardiorespiratory function.

    Science.gov (United States)

    Wang, Xin; Dergacheva, Olga; Kamendi, Harriet; Gorini, Christopher; Mendelowitz, David

    2007-08-01

    Opioids evoke respiratory depression, bradycardia, and reduced respiratory sinus arrhythmia, whereas serotonin (5-HT) agonists stimulate respiration and cardiorespiratory interactions. This study tested whether serotonin agonists can prevent the inhibitory effects of opioids on cardiorespiratory function. Spontaneous and rhythmic inspiratory-related activity and gamma-aminobutyric acid (GABA) neurotransmission to premotor parasympathetic cardioinhibitory neurons in the nucleus ambiguus were recorded simultaneously in an in vitro thick slice preparation. The mu-opioid agonist fentanyl inhibited respiratory frequency. The 5-hydroxytryptamine 1A/7 receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin increased respiratory frequency by itself and also prevented the fentanyl-induced respiratory depression. The 5-hydroxytryptamine 4alpha agonist BIMU-8 did not by itself change inspiratory activity but prevented the mu-opioid-mediated respiratory depression. Both spontaneous and inspiratory-evoked GABAergic neurotransmission to cardiac vagal neurons were inhibited by fentanyl. 8-Hydroxy-2-(di-n-propylamino)tetralin inhibited spontaneous but not inspiratory-evoked GABAergic activity to parasympathetic cardiac neurons. However, 8-hydroxy-2-(di-n-propylamino)tetralin differentially altered the opioid-mediated depression of inspiratory-evoked GABAergic activity but did not change the opioid-induced reduction in spontaneous GABAergic neurotransmission. In contrast, BIMU-8 did not alter GABAergic neurotransmission to cardiac vagal neurons by itself but prevented the fentanyl depression of both spontaneous and inspiratory-elicited GABAergic neurotransmission to cardiac vagal neurons. In the presence of tetrodotoxin, the inhibition of GABAergic inhibitory postsynaptic currents with fentanyl is prevented by coapplication of BIMU-8, indicating that BIMU-8 acts at presynaptic GABAergic terminals to prevent fentanyl-induced depression. These results suggest that activation of 5

  17. Aspects of dopamine and acetylcholine release induced by glutamate receptors; Aspectos das liberacoes de dopamina e acetilcolina mediadas por receptores de glutamato

    Energy Technology Data Exchange (ETDEWEB)

    Paes, Paulo Cesar de Arruda

    2002-07-01

    The basal ganglia play an important role in the motor control of rats and humans. This control involves different neurotransmitters and the mutual control of these key elements has been subject to several studies. In this work we determined the role of glutamate on the release of radioactively labelled dopamine and acetylcholine from chopped striatal tissue in vitro. The values of Effective Concentration 50% for glutamate, NMDA, kainic, quisqualic acids and AMPA on the release of dopamine and acetylcholine were obtained. The inhibitory effects of magnesium, tetrodotoxin, MK-801, AP5 and MCPG, as well as the effects of glycin were evaluated. The results suggested that dopamine is influenced by the NMDA type glutamate receptor while acetylcholine seems to be influenced by NMDA, kainate and AMPA receptors. Tetrodotoxin experiments suggested that kainate receptors are both present in cholinergic terminals and cell bodies while AMPA and NMDA receptors are preferentially distributed in cell bodies. Magnesium effectively blocked the NMDA stimulation and unexpectedly also AMPA- and quisqualate-induced acetylcholine release. The latter could not be blocked by MCPG ruling out the participation of methabotropic receptors. MK-801 also blocked NMDA-receptors. Results point out the importance of the glutamic acid control of dopamine and acetylcholine release in striatal tissue. (author)

  18. Serotonergic Regulation of Prefrontal Cortical Circuitries Involved in Cognitive Processing: A Review of Individual 5-HT Receptor Mechanisms and Concerted Effects of 5-HT Receptors Exemplified by the Multimodal Antidepressant Vortioxetine.

    Science.gov (United States)

    Leiser, Steven C; Li, Yan; Pehrson, Alan L; Dale, Elena; Smagin, Gennady; Sanchez, Connie

    2015-07-15

    It has been known for several decades that serotonergic neurotransmission is a key regulator of cognitive function, mood, and sleep. Yet with the relatively recent discoveries of novel serotonin (5-HT) receptor subtypes, as well as an expanding knowledge of their expression level in certain brain regions and localization on certain cell types, their involvement in cognitive processes is still emerging. Of particular interest are cognitive processes impacted in neuropsychiatric and neurodegenerative disorders. The prefrontal cortex (PFC) is critical to normal cognitive processes, including attention, impulsivity, planning, decision-making, working memory, and learning or recall of learned memories. Furthermore, serotonergic dysregulation within the PFC is implicated in many neuropsychiatric disorders associated with prominent symptoms of cognitive dysfunction. Thus, it is important to better understand the overall makeup of serotonergic receptors in the PFC and on which cell types these receptors mediate their actions. In this Review, we focus on 5-HT receptor expression patterns within the PFC and how they influence cognitive behavior and neurotransmission. We further discuss the net effects of vortioxetine, an antidepressant acting through multiple serotonergic targets given the recent findings that vortioxetine improves cognition by modulating multiple neurotransmitter systems.

  19. Protein kinase A mediates adenosine A2a receptor modulation of neurotransmitter release via synapsin I phosphorylation in cultured cells from medulla oblongata.

    Science.gov (United States)

    Matsumoto, Joao Paulo Pontes; Almeida, Marina Gomes; Castilho-Martins, Emerson Augusto; Costa, Maisa Aparecida; Fior-Chadi, Debora Rejane

    2014-08-01

    Synaptic transmission is an essential process for neuron physiology. Such process is enabled in part due to modulation of neurotransmitter release. Adenosine is a synaptic modulator of neurotransmitter release in the Central Nervous System, including neurons of medulla oblongata, where several nuclei are involved with neurovegetative reflexes. Adenosine modulates different neurotransmitter systems in medulla oblongata, specially glutamate and noradrenaline in the nucleus tractussolitarii, which are involved in hypotensive responses. However, the intracellular mechanisms involved in this modulation remain unknown. The adenosine A2a receptor modulates neurotransmitter release by activating two cAMP protein effectors, the protein kinase A and the exchange protein activated by cAMP. Therefore, an in vitro approach (cultured cells) was carried out to evaluate modulation of neurotransmission by adenosine A2a receptor and the signaling intracellular pathway involved. Results show that the adenosine A2a receptor agonist, CGS 21680, increases neurotransmitter release, in particular, glutamate and noradrenaline and such response is mediated by protein kinase A activation, which in turn increased synapsin I phosphorylation. This suggests a mechanism of A2aR modulation of neurotransmitter release in cultured cells from medulla oblongata of Wistar rats and suggest that protein kinase A mediates this modulation of neurotransmitter release via synapsin I phosphorylation. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  20. Altered brain serotonergic neurotransmission following caffeine withdrawal produces behavioral deficits in rats.

    Science.gov (United States)

    Khaliq, Saima; Haider, Saida; Naqvi, Faizan; Perveen, Tahira; Saleem, Sadia; Haleem, Darakhshan Jabeen

    2012-01-01

    Caffeine administration has been shown to enhance performance and memory in rodents and humans while its withdrawal on the other hand produces neurobehavioral deficits which are thought to be mediated by alterations in monoamines neurotransmission. A role of decreased brain 5-HT (5-hydroxytryptamine, serotonin) levels has been implicated in impaired cognitive performance and depression. Memory functions of rats were assessed by Water Maze (WM) and immobility time by Forced Swim Test (FST). The results of this study showed that repeated caffeine administration for 6 days at 30 mg/kg dose significantly increases brain 5-HT (pcaffeine. Withdrawal of caffeine however produced memory deficits and significantly increases the immobility time of rats in FST. The results of this study are linked with caffeine induced alterations in serotonergic neurotransmission and its role in memory and depression.

  1. Role of glutamatergic receptors located in the nucleus raphe magnus on antinociceptive effect of morphine microinjected into the nucleus cuneiformis of rat.

    Science.gov (United States)

    Haghparast, Abbas; Soltani-Hekmat, Ava; Khani, Abbas; Komaki, Alireza

    2007-10-29

    Neurons in the nucleus cuneiformis (CnF), located just ventrolateral to the periaqueductal gray, project to medullary nucleus raphe magnus (NRM), which is a key medullary relay for descending pain modulation and is critically involved in opioid-induced analgesia. Previous studies have shown that antinociceptive response of CnF-microinjected morphine can be modulated by the specific subtypes of glutamatergic receptors within the CnF. In this study, we evaluated the role of NMDA and kainate/AMPA receptors that are widely distributed within the NRM on morphine-induced antinociception elicited from the CnF. Hundred and five male Wistar rats weighing 250-300 g were used. Morphine (10, 20 and 40 microg) and NMDA receptor antagonist, MK-801 (10 microg) or kainate/AMPA receptor antagonist, DNQX (0.5 microg) in 0.5 microl saline were stereotaxically microinjected into the CnF and NRM, respectively. The latency of tail-flick response was measured at set intervals (2, 7, 12, 17, 22, 27 min after microinjection) by using an automated tail-flick analgesiometer. The results showed that morphine microinjection into the CnF dose-dependently causes increase in tail-flick latency (TFL). MK-801 microinjected into the NRM, just 1 min before morphine injection into the CnF, significantly attenuated antinociceptive effects of morphine. On the other hand, DNQX microinjected into the NRM, significantly increased TFL after local application of morphine into the CnF. We suggest that morphine related antinociceptive effect elicited from the CnF is mediated, in part, by NMDA receptor at the level of the NRM whereas kainite/AMPA receptor has a net inhibitory influence at the same pathway.

  2. Aspects of dopamine and acetylcholine release induced by glutamate receptors

    International Nuclear Information System (INIS)

    Paes, Paulo Cesar de Arruda

    2002-01-01

    The basal ganglia play an important role in the motor control of rats and humans. This control involves different neurotransmitters and the mutual control of these key elements has been subject to several studies. In this work we determined the role of glutamate on the release of radioactively labelled dopamine and acetylcholine from chopped striatal tissue in vitro. The values of Effective Concentration 50% for glutamate, NMDA, kainic, quisqualic acids and AMPA on the release of dopamine and acetylcholine were obtained. The inhibitory effects of magnesium, tetrodotoxin, MK-801, AP5 and MCPG, as well as the effects of glycin were evaluated. The results suggested that dopamine is influenced by the NMDA type glutamate receptor while acetylcholine seems to be influenced by NMDA, kainate and AMPA receptors. Tetrodotoxin experiments suggested that kainate receptors are both present in cholinergic terminals and cell bodies while AMPA and NMDA receptors are preferentially distributed in cell bodies. Magnesium effectively blocked the NMDA stimulation and unexpectedly also AMPA- and quisqualate-induced acetylcholine release. The latter could not be blocked by MCPG ruling out the participation of methabotropic receptors. MK-801 also blocked NMDA-receptors. Results point out the importance of the glutamic acid control of dopamine and acetylcholine release in striatal tissue. (author)

  3. Interactions of neurotoxins with non-NMDA glutamate receptors: an autoradiographic study

    International Nuclear Information System (INIS)

    Kuenig, G.; Niedermeyer, B.; Krause, F.; Hartmann, J.; Deckert, J.; Heinsen, H.; Beckmann, H.; Riederer, P.; Ransmayr, G.

    1994-01-01

    Neurotoxic substances are discussed to cause neurode-generation by acting as excitotoxins on glutamate receptors. We investigated the properties of L-beta-oxalyl-amino-alanine (L-BOAA) and 3,4,6-trihydroxyphenlyalanine (6-OH-Dopa) at the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) glutamate receptor and that of L-BOAA and domoic acid at the kainate glutamate receptor in human hippocampus. (3 H)AMPA binding in hippocampal subfields was inhibited by L-BOAA and 6-OH-Dopa with mean IC50-values in the low micromolar range. (3H)Kainate binding was inhibited by L-BOAA with similar potency as (3H)AMPA binding and by domoic acid with mean IC50-values in the low nanomolar range. These results support the notion that symptoms like anterograde amnesia and epileptic seizures seen in domoic acid intoxication and limbic symptoms, e.g. cognitive and mood impairment observed in neurolathyrism may be caused by excitotoxic action on non-NMDA receptors. The potent interaction of 6-OH-Dopa with the AMPA-receptor may point to a possible dopaminergic-glutamatergic interaction in the development of neurodegenerative diseases like Parkinson's and Huntington's disease. (author)

  4. Ionotropic glutamate receptors mediate inducible defense in the water flea Daphnia pulex.

    Directory of Open Access Journals (Sweden)

    Hitoshi Miyakawa

    Full Text Available Phenotypic plasticity is the ability held in many organisms to produce different phenotypes with a given genome in response to environmental stimuli, such as temperature, nutrition and various biological interactions. It seems likely that environmental signals induce a variety of mechanistic responses that influence ontogenetic processes. Inducible defenses, in which prey animals alter their morphology, behavior and/or other traits to help protect against direct or latent predation threats, are among the most striking examples of phenotypic plasticity. The freshwater microcrustacean Daphnia pulex forms tooth-like defensive structures, "neckteeth," in response to chemical cues or signals, referred to as "kairomones," in this case released from phantom midge larvae, a predator of D. pulex. To identify factors involved in the reception and/or transmission of a kairomone, we used microarray analysis to identify genes up-regulated following a short period of exposure to the midge kairomone. In addition to identifying differentially expressed genes of unknown function, we also found significant up-regulation of genes encoding ionotropic glutamate receptors, which are known to be involved in neurotransmission in many animal species. Specific antagonists of these receptors strongly inhibit the formation of neckteeth in D. pulex, although agonists did not induce neckteeth by themselves, indicating that ionotropic glutamate receptors are necessary but not sufficient for early steps of neckteeth formation in D. pulex. Moreover, using co-exposure of D. pulex to antagonists and juvenile hormone (JH, which physiologically mediates neckteeth formation, we found evidence suggesting that the inhibitory effect of antagonists is not due to direct inhibition of JH synthesis/secretion. Our findings not only provide a candidate molecule required for the inducible defense response in D. pulex, but also will contribute to the understanding of complex mechanisms

  5. Glufosinate ammonium stimulates nitric oxide production through N-methyl D-aspartate receptors in rat cerebellum.

    Science.gov (United States)

    Nakaki, T; Mishima, A; Suzuki, E; Shintani, F; Fujii, T

    2000-09-01

    Glufosinate ammonium, a structural analogue of glutamate, is an active herbicidal ingredient. The neuronal activities of this compound were investigated by use of a microdialysis system that allowed us to measure nitric oxide production in the rat cerebellum in vivo. Kainate (0.3-30 nmol/10 microliter), N-methyl-D-aspartate (NMDA) (3-300 nmol/10 microliter) and glufosinate ammonium (30-3000 nmol/10 microliter), which were administered through the microdialysis probe at a rate of 1 microliter/min for 10 min, stimulated nitric oxide production. The glufosinate ammonium-elicited increase in nitric oxide production was suppressed by an inhibitor of nitric oxide synthase and was antagonized by NMDA receptor antagonists, but not by a kainate/(+/-)-alphaamino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist. These results suggest that glufosinate ammonium stimulates nitric oxide production through NMDA receptors.

  6. Facilitation and inhibition by capsaicin of cholinergic neurotransmission in the guinea-pig small intestine.

    Science.gov (United States)

    Geber, Christian; Mang, Christian F; Kilbinger, Heinz

    2006-01-01

    The effects of capsaicin on [3H]acetylcholine release and muscle contraction were studied on the myenteric plexus-longitudinal muscle preparation of the guinea-pig ileum preincubated with [3H]choline. Capsaicin concentration-dependently increased both basal [3H]acetylcholine release (pEC50 7.0) and muscle tone (pEC50 6.1). The facilitatory effects of capsaicin were antagonized by 1 microM capsazepine (pK (B) 7.0 and 7.6), and by the combined blockade of NK1 and NK3 tachykinin receptors with the antagonists CP99994 plus SR142801 (each 0.1 microM). This suggests that stimulation by capsaicin of TRPV1 receptors on primary afferent fibres causes a release of tachykinins which, in turn, mediate via NK1 and NK3 receptors an increase in acetylcholine release. The capsaicin-induced acetylcholine release was significantly enhanced by the NO synthase inhibitor L-NG-nitroarginine (100 microM). This indicates that tachykinins released from sensory neurons also stimulate nitrergic neurons and thus lead, via NO release, to inhibition of acetylcholine release. Capsaicin concentration-dependently reduced the electrically-evoked [3H]acetylcholine release (pEC50 6.4) and twitch contractions (pEC50 5.9). The inhibitory effects were not affected by either capsazepine, NK1 and NK3 receptor antagonists, the cannabinoid CB1 antagonist SR141716A or by L-NG-nitroarginine. Desensitization of TRPV1 receptors by a short exposure to 3 microM capsaicin abolished the facilitatory responses to a subsequent administration, but did not modify the inhibitory effects. In summary, capsaicin has a dual effect on cholinergic neurotransmission. The facilitatory effect is indirect and involves tachykinin release and excitation of NK1 and NK3 receptors on cholinergic neurons. The inhibition of acetylcholine release may be due to a decrease of Ca2+ influx into cholinergic neurons.

  7. Extrasynaptic neurotransmission in the modulation of brain function. Focus on the striatal neuronal-glial networks

    Directory of Open Access Journals (Sweden)

    Kjell eFuxe

    2012-06-01

    Full Text Available Extrasynaptic neurotransmission is an important short distance form of volume transmission (VT and describes the extracellular diffusion of transmitters and modulators after synaptic spillover or extrasynaptic release in the local circuit regions binding to and activating mainly extrasynaptic neuronal and glial receptors in the neuroglial networks of the brain. Receptor-receptor interactions in G protein-coupled receptor (GPCR heteromers play a major role, on dendritic spines and nerve terminals including glutamate synapses, in the integrative processes of the extrasynaptic signaling. Heteromeric complexes between GPCR and ion-channel receptors play a special role in the integration of the synaptic and extrasynaptic signals. Changes in extracellular concentrations of the classical synaptic neurotransmitters glutamate and GABA found with microdialysis is likely an expression of the activity of the neuron-astrocyte unit of the brain and can be used as an index of VT-mediated actions of these two neurotransmitters in the brain. Thus, the activity of neurons may be functionally linked to the activity of astrocytes, which may release glutamate and GABA to the extracellular space where extrasynaptic glutamate and GABA receptors do exist. Wiring transmission (WT and VT are fundamental properties of all neurons of the CNS but the balance between WT and VT varies from one nerve cell population to the other. The focus is on the striatal cellular networks, and the WT and VT and their integration via receptor heteromers are described in the GABA projection neurons, the glutamate, dopamine, 5-hydroxytryptamine (5-HT and histamine striatal afferents, the cholinergic interneurons and different types of GABA interneurons. In addition, the role in these networks of VT signaling of the energy-dependent modulator adenosine and of endocannabinoids mainly formed in the striatal projection neurons will be underlined to understand the communication in the striatal

  8. Arctigenin reduces neuronal responses in the somatosensory cortex via the inhibition of non-NMDA glutamate receptors.

    Science.gov (United States)

    Borbély, Sándor; Jócsák, Gergely; Moldován, Kinga; Sedlák, Éva; Preininger, Éva; Boldizsár, Imre; Tóth, Attila; Atlason, Palmi T; Molnár, Elek; Világi, Ildikó

    2016-07-01

    Lignans are biologically active phenolic compounds related to lignin, produced in different plants. Arctigenin, a dibenzylbutyrolactone-type lignan, has been used as a neuroprotective agent for the treatment of encephalitis. Previous studies of cultured rat cerebral cortical neurones raised the possibility that arctigenin inhibits kainate-induced excitotoxicity. The aims of the present study were: 1) to analyse the effect of arctigenin on normal synaptic activity in ex vivo brain slices, 2) to determine its receptor binding properties and test the effect of arctigenin on AMPA/kainate receptor activation and 3) to establish its effects on neuronal activity in vivo. Arctigenin inhibited glutamatergic transmission and reduced the evoked field responses. The inhibitory effect of arctigenin on the evoked field responses proved to be substantially dose dependent. Our results indicate that arctigenin exerts its effects under physiological conditions and not only on hyper-excited neurons. Furthermore, arctigenin can cross the blood-brain barrier and in the brain it interacts with kainate sensitive ionotropic glutamate receptors. These results indicate that arctigenin is a potentially useful new pharmacological tool for the inhibition of glutamate-evoked responses in the central nervous system in vivo. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Antagonism of ionotropic glutamate receptors attenuates chemical ischemia-induced injury in rat primary cultured myenteric ganglia.

    Directory of Open Access Journals (Sweden)

    Elisa Carpanese

    Full Text Available Alterations of the enteric glutamatergic transmission may underlay changes in the function of myenteric neurons following intestinal ischemia and reperfusion (I/R contributing to impairment of gastrointestinal motility occurring in these pathological conditions. The aim of the present study was to evaluate whether glutamate receptors of the NMDA and AMPA/kainate type are involved in myenteric neuron cell damage induced by I/R. Primary cultured rat myenteric ganglia were exposed to sodium azide and glucose deprivation (in vitro chemical ischemia. After 6 days of culture, immunoreactivity for NMDA, AMPA and kainate receptors subunits, GluN(1 and GluA(1-3, GluK(1-3 respectively, was found in myenteric neurons. In myenteric cultured ganglia, in normal metabolic conditions, -AP5, an NMDA antagonist, decreased myenteric neuron number and viability, determined by calcein AM/ethidium homodimer-1 assay, and increased reactive oxygen species (ROS levels, measured with hydroxyphenyl fluorescein. CNQX, an AMPA/kainate antagonist exerted an opposite action on the same parameters. The total number and viability of myenteric neurons significantly decreased after I/R. In these conditions, the number of neurons staining for GluN1 and GluA(1-3 subunits remained unchanged, while, the number of GluK(1-3-immunopositive neurons increased. After I/R, -AP5 and CNQX, concentration-dependently increased myenteric neuron number and significantly increased the number of living neurons. Both -AP5 and CNQX (100-500 µM decreased I/R-induced increase of ROS levels in myenteric ganglia. On the whole, the present data provide evidence that, under normal metabolic conditions, the enteric glutamatergic system exerts a dualistic effect on cultured myenteric ganglia, either by improving or reducing neuron survival via NMDA or AMPA/kainate receptor activation, respectively. However, blockade of both receptor pathways may exert a protective role on myenteric neurons following and I

  10. Topiramate via NMDA, AMPA/kainate, GABAA and Alpha2 receptors and by modulation of CREB/BDNF and Akt/GSK3 signaling pathway exerts neuroprotective effects against methylphenidate-induced neurotoxicity in rats.

    Science.gov (United States)

    Motaghinejad, Majid; Motevalian, Manijeh; Fatima, Sulail; Beiranvand, Tabassom; Mozaffari, Shiva

    2017-11-01

    Chronic abuse of methylphenidate (MPH) often causes neuronal cell death. Topiramate (TPM) carries neuroprotective effects, but its exact mechanism of action remains unclear. In the present study, the role of various doses of TPM and its possible mechanisms, receptors and signaling pathways involved against MPH-induced hippocampal neurodegeneration were evaluated in vivo. Thus, domoic acid (DOM) was used as AMPA/kainate receptor agonist, bicuculline (BIC) as GABA A receptor antagonist, ketamine (KET) as NMDA receptor antagonist, yohimbine (YOH) as α 2 adrenergic receptor antagonist and haloperidol (HAL) was used as dopamine D 2 receptor antagonist. Open field test (OFT) was used to investigate the disturbances in motor activity. Hippocampal neurodegenerative parameters were evaluated. Protein expressions of CREB/BDNF and Akt/GSK3 signaling pathways were also evaluated. Cresyl violet staining was performed to show and confirm the changes in the shape of the cells. TPM (70 and 100 mg/kg) reduced MPH-induced rise in lipid peroxidation, oxidized form of glutathione (GSSG), IL-1β and TNF-α levels, Bax expression and motor activity disturbances. In addition, TPM treatment increased Bcl-2 expression, the level of reduced form of glutathione (GSH) and the levels and activities of superoxide dismutase, glutathione peroxidase and glutathione reductase enzymes. TPM also inhibited MPH-induced hippocampal degeneration. Pretreatment of animals with DOM, BIC, KET and YOH inhibited TPM-induced neuroprotection and increased oxidative stress, neuroinflammation, neuroapoptosis and neurodegeneration while reducing CREB, BDNF and Akt protein expressions. Also pretreatment with DOM, BIC, KET and YOH inhibited TPM-induced decreases in GSK3. It can be concluded that the mentioned receptors by modulation of CREB/BDNF and Akt/GSK3 pathways, are involved in neuroprotection of TPM against MPH-induced neurodegeneration.

  11. Identification of AICP as a GluN2C-Selective N-Methyl-d-Aspartate Receptor Superagonist at the GluN1 Glycine Site

    DEFF Research Database (Denmark)

    Jessen, Maja; Frederiksen, Kristen; Yi, Feng

    2017-01-01

    N-methyl-d-aspartate (NMDA)-type ionotropic glutamate receptors mediate excitatory neurotransmission in the central nervous system and are critically involved in brain function. NMDA receptors are also implicated in psychiatric and neurological disorders and have received considerable attention....../2A-D), in which DCS is a superagonist at GluN2C-containing receptors compared with glycine and a partial agonist at GluN2B-containing receptors. Here, we identify (R)-2-amino-3-(4-(2-ethylphenyl)-1H-indole-2-carboxamido)propanoic acid (AICP) as a glycine site agonist with unique GluN2-dependent...

  12. [Neurotransmission in developmental disorders].

    Science.gov (United States)

    Takeuchi, Yoshihiro

    2008-11-01

    Attention deficit/hyperactivity disorder (AD/HD) is a heterogeneous developmental disorder with an etiology that is not fully understood. AD/HD has been considered to occur due to a disturbance in cathecholaminergic neurotransmission, with particular emphasis on dopamine. The neurotransmission of dopamine in subcortical regions such as the basal ganglia and limbic areas is synaptic; on the other hand, dopamine neurotransmission in the frontal cortex is quite different, because there are very few dopamine transporters (DAT) in the frontal cortex that allow dopamine to diffuse away from the dopamine synapse ("volume transmission"). It is now clear that noradrenergic neurons play a key regulatory role in dopaminergic function in the frontal cortex. Furthermore, serotonergic neurons exert an inhibitory effect on midbrain dopamine cell bodies, and they have an influence on dopamine release in terminal regions. There is accumulating neurobiological evidence pointing toward a role of the serotonin system in AD/HD. The etiology of autism spectrum disorders (ASD) is still unclear, but information from genetics, neuropathology, brain imaging, and basic neuroscience has provided insights into the understanding of this developmental disorder. In addition to abnormal circuitry in specific limbic and neocortical areas of the cerebral cortex, impairments in brainstem, cerebellar, thalamic, and basal ganglia connections have been reported. Numerous studies have pointed to abnormalities in serotonin and glutamate neurotransmission. Three important aspects involved in the pathophysiology of ASD have been proposed. The first is cell migration, the second is unbalanced excitatory-inhibitory networks, and the third is synapse formation and pruning, the key factors being reelin, neurexin, and neuroligin. Serotonin is considered to play an important role in all of these aspects of the pathophysiology of ASD. Finally, I would like to emphasize that it is crucial in the field of child

  13. Cell-specific cre recombinase expression allows selective ablation of glutamate receptors from mouse horizontal cells.

    Directory of Open Access Journals (Sweden)

    Sebastian Ströh

    Full Text Available In the mouse retina, horizontal cells form an electrically coupled network and provide feedback signals to photoreceptors and feedforward signals to bipolar cells. Thereby, horizontal cells contribute to gain control at the first visual synapse and to the antagonistic organization of bipolar and ganglion cell receptive fields. However, the nature of horizontal cell output remains a matter of debate, just as the exact contribution of horizontal cells to center-surround antagonism. To facilitate studying horizontal cell function, we developed a knockin mouse line which allows ablating genes exclusively in horizontal cells. This knockin line expresses a Cre recombinase under the promoter of connexin57 (Cx57, a gap junction protein only expressed in horizontal cells. Consistently, in Cx57+/Cre mice, Cre recombinase is expressed in almost all horizontal cells (>99% and no other retinal neurons. To test Cre activity, we crossbred Cx57+/Cre mice with a mouse line in which exon 11 of the coding sequence for the ionotropic glutamate receptor subunit GluA4 was flanked by two loxP sites (GluA4fl/fl. In GluA4fl/fl:Cx57+/Cre mice, GluA4 immunoreactivity was significantly reduced (∼ 50% in the outer retina where horizontal cells receive photoreceptor inputs, confirming the functionality of the Cre/loxP system. Whole-cell patch-clamp recordings from isolated horizontal cell somata showed a reduction of glutamate-induced inward currents by ∼ 75%, suggesting that the GluA4 subunit plays a major role in mediating photoreceptor inputs. The persistent current in GluA4-deficient cells is mostly driven by AMPA and to a very small extent by kainate receptors as revealed by application of the AMPA receptor antagonist GYKI52466 and concanavalin A, a potentiator of kainate receptor-mediated currents. In summary, the Cx57+/Cre mouse line provides a versatile tool for studying horizontal cell function. GluA4fl/fl:Cx57+/Cre mice, in which horizontal cells receive less

  14. Cell-Specific Cre Recombinase Expression Allows Selective Ablation of Glutamate Receptors from Mouse Horizontal Cells

    Science.gov (United States)

    Janssen-Bienhold, Ulrike; Schultz, Konrad; Cimiotti, Kerstin; Weiler, Reto; Willecke, Klaus; Dedek, Karin

    2013-01-01

    In the mouse retina, horizontal cells form an electrically coupled network and provide feedback signals to photoreceptors and feedforward signals to bipolar cells. Thereby, horizontal cells contribute to gain control at the first visual synapse and to the antagonistic organization of bipolar and ganglion cell receptive fields. However, the nature of horizontal cell output remains a matter of debate, just as the exact contribution of horizontal cells to center-surround antagonism. To facilitate studying horizontal cell function, we developed a knockin mouse line which allows ablating genes exclusively in horizontal cells. This knockin line expresses a Cre recombinase under the promoter of connexin57 (Cx57), a gap junction protein only expressed in horizontal cells. Consistently, in Cx57+/Cre mice, Cre recombinase is expressed in almost all horizontal cells (>99%) and no other retinal neurons. To test Cre activity, we crossbred Cx57+/Cre mice with a mouse line in which exon 11 of the coding sequence for the ionotropic glutamate receptor subunit GluA4 was flanked by two loxP sites (GluA4fl/fl). In GluA4fl/fl:Cx57+/Cre mice, GluA4 immunoreactivity was significantly reduced (∼50%) in the outer retina where horizontal cells receive photoreceptor inputs, confirming the functionality of the Cre/loxP system. Whole-cell patch-clamp recordings from isolated horizontal cell somata showed a reduction of glutamate-induced inward currents by ∼75%, suggesting that the GluA4 subunit plays a major role in mediating photoreceptor inputs. The persistent current in GluA4-deficient cells is mostly driven by AMPA and to a very small extent by kainate receptors as revealed by application of the AMPA receptor antagonist GYKI52466 and concanavalin A, a potentiator of kainate receptor-mediated currents. In summary, the Cx57+/Cre mouse line provides a versatile tool for studying horizontal cell function. GluA4fl/fl:Cx57+/Cre mice, in which horizontal cells receive less excitatory input

  15. Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

    International Nuclear Information System (INIS)

    Xu, Yuan; Cardell, Lars-Olaf

    2014-01-01

    Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B 2 receptor agonist) and des-Arg 9 -bradykinin- (selective B 1 receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE 2 . The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg 9 -bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B 2 receptors, but not those on B 1 . Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in some patients with asthma

  16. Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuan, E-mail: yuan.xu@ki.se; Cardell, Lars-Olaf

    2014-02-15

    Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B{sub 2} receptor agonist) and des-Arg{sup 9}-bradykinin- (selective B{sub 1} receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE{sub 2}. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg{sup 9}-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B{sub 2} receptors, but not those on B{sub 1}. Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in

  17. Melanocortin MC(4) receptor-mediated feeding and grooming in rodents.

    Science.gov (United States)

    Mul, Joram D; Spruijt, Berry M; Brakkee, Jan H; Adan, Roger A H

    2013-11-05

    Decades ago it was recognized that the pharmacological profile of melanocortin ligands that stimulated grooming behavior in rats was strikingly similar to that of Xenopus laevis melanophore pigment dispersion. After cloning of the melanocortin MC1 receptor, expressed in melanocytes, and the melanocortin MC4 receptor, expressed mainly in brain, the pharmacological profiles of these receptors appeared to be very similar and it was demonstrated that these receptors mediate melanocortin-induced pigmentation and grooming respectively. Grooming is a low priority behavior that is concerned with care of body surface. Activation of central melanocortin MC4 receptors is also associated with meal termination, and continued postprandial stimulation of melanocortin MC4 receptors may stimulate natural postprandial grooming behavior as part of the behavioral satiety sequence. Indeed, melanocortins fail to suppress food intake or induce grooming behavior in melanocortin MC4 receptor-deficient rats. This review will focus on how melanocortins affect grooming behavior through the melanocortin MC4 receptor, and how melanocortin MC4 receptors mediate feeding behavior. This review also illustrates how melanocortins were the most likely candidates to mediate grooming and feeding based on the natural behaviors they induced. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Omega-3 polyunsaturated fatty acids and chronic stress-induced modulations of glutamatergic neurotransmission in the hippocampus.

    Science.gov (United States)

    Hennebelle, Marie; Champeil-Potokar, Gaëlle; Lavialle, Monique; Vancassel, Sylvie; Denis, Isabelle

    2014-02-01

    Chronic stress causes the release of glucocorticoids, which greatly influence cerebral function, especially glutamatergic transmission. These stress-induced changes in neurotransmission could be counteracted by increasing the dietary intake of omega-3 polyunsaturated fatty acids (n-3 PUFAs). Numerous studies have described the capacity of n-3 PUFAs to help protect glutamatergic neurotransmission from damage induced by stress and glucocorticoids, possibly preventing the development of stress-related disorders such as depression or anxiety. The hippocampus contains glucocorticoid receptors and is involved in learning and memory. This makes it particularly sensitive to stress, which alters certain aspects of hippocampal function. In this review, the various ways in which n-3 PUFAs may prevent the harmful effects of chronic stress, particularly the alteration of glutamatergic synapses in the hippocampus, are summarized. © 2014 International Life Sciences Institute.

  19. Membrane cholesterol mediates the cellular effects of monolayer graphene substrates.

    Science.gov (United States)

    Kitko, Kristina E; Hong, Tu; Lazarenko, Roman M; Ying, Da; Xu, Ya-Qiong; Zhang, Qi

    2018-02-23

    Graphene possesses extraordinary properties that promise great potential in biomedicine. However, fully leveraging these properties requires close contact with the cell surface, raising the concern of unexpected biological consequences. Computational models have demonstrated that graphene preferentially interacts with cholesterol, a multifunctional lipid unique to eukaryotic membranes. Here we demonstrate an interaction between graphene and cholesterol. We find that graphene increases cell membrane cholesterol and potentiates neurotransmission, which is mediated by increases in the number, release probability, and recycling rate of synaptic vesicles. In fibroblasts grown on graphene, we also find an increase in cholesterol, which promotes the activation of P2Y receptors, a family of receptor regulated by cholesterol. In both cases, direct manipulation of cholesterol levels elucidates that a graphene-induced cholesterol increase underlies the observed potentiation of each cell signaling pathway. These findings identify cholesterol as a mediator of graphene's cellular effects, providing insight into the biological impact of graphene.

  20. Biochemical characterization of an autoradiographic method for studying excitatory amino acid receptors using L-[3H]glutamate

    International Nuclear Information System (INIS)

    Cincotta, M.; Summers, R.J.; Beart, P.M.

    1989-01-01

    A method was developed for radiolabeling excitatory amino acid receptors of rat brain with L-[ 3 H]glutamate. Effective labeling of glutamate receptors in slide-mounted 10-microns sections was obtained using a low incubation volume (0.15 ml) and rapid washing: a procedure where high ligand concentrations were achieved with minimal waste. Saturation experiments using [ 3 H]glutamate revealed a single binding site of micromolar affinity. The Bmax was trebled in the presence of Ca2+ (2.5 mM) and Cl- (20 mM) with no change in the Kd. Binding was rapid, saturable, stereospecific, and sensitive to glutamate receptor agonists. The proportions of [ 3 H]glutamate binding sensitive to N-methyl-D-aspartate (NMDA), kainate, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) were 34, 54, and 51%, respectively. NMDA inhibited binding at a distinct subset of L-[ 3 H]glutamate sites, whereas AMPA and kainate competed for some common sites. Labeling of sections with L-[ 3 H]glutamate in the presence of the selective agonists allowed autoradiographic visualization of glutamate receptor subtypes in brain tissue

  1. Fcγ receptor-mediated inflammation inhibits axon regeneration.

    Directory of Open Access Journals (Sweden)

    Gang Zhang

    Full Text Available Anti-glycan/ganglioside antibodies are the most common immune effectors found in patients with Guillain-Barré Syndrome, which is a peripheral autoimmune neuropathy. We previously reported that disease-relevant anti-glycan autoantibodies inhibited axon regeneration, which echo the clinical association of these antibodies and poor recovery in Guillain-Barré Syndrome. However, the specific molecular and cellular elements involved in this antibody-mediated inhibition of axon regeneration are not previously defined. This study examined the role of Fcγ receptors and macrophages in the antibody-mediated inhibition of axon regeneration. A well characterized antibody passive transfer sciatic nerve crush and transplant models were used to study the anti-ganglioside antibody-mediated inhibition of axon regeneration in wild type and various mutant and transgenic mice with altered expression of specific Fcγ receptors and macrophage/microglia populations. Outcome measures included behavior, electrophysiology, morphometry, immunocytochemistry, quantitative real-time PCR, and western blotting. We demonstrate that the presence of autoantibodies, directed against neuronal/axonal cell surface gangliosides, in the injured mammalian peripheral nerves switch the proregenerative inflammatory environment to growth inhibitory milieu by engaging specific activating Fcγ receptors on recruited monocyte-derived macrophages to cause severe inhibition of axon regeneration. Our data demonstrate that the antibody orchestrated Fcγ receptor-mediated switch in inflammation is one mechanism underlying inhibition of axon regeneration. These findings have clinical implications for nerve repair and recovery in antibody-mediated immune neuropathies. Our results add to the complexity of axon regeneration in injured peripheral and central nervous systems as adverse effects of B cells and autoantibodies on neural injury and repair are increasingly recognized.

  2. Endogenous cholinergic neurotransmission contributes to behavioral sensitization to morphine.

    Directory of Open Access Journals (Sweden)

    Dusica Bajic

    Full Text Available Neuroplasticity in the mesolimbic dopaminergic system is critical for behavioral adaptations associated with opioid reward and addiction. These processes may be influenced by cholinergic transmission arising from the laterodorsal tegmental nucleus (LDTg, a main source of acetylcholine to mesolimbic dopaminergic neurons. To examine this possibility we asked if chronic systemic morphine administration affects expression of genes in ventral and ventrolateral periaqueductal gray at the level of the LDTg using rtPCR. Specifically, we examined gene expression changes in the area of interest using Neurotransmitters and Receptors PCR array between chronic morphine and saline control groups. Analysis suggested that chronic morphine administration led to changes in expression of genes associated, in part, with cholinergic neurotransmission. Furthermore, using a quantitative immunofluorescent technique, we found that chronic morphine treatment produced a significant increase in immunolabeling of the cholinergic marker (vesicular acetylcholine transporter in neurons of the LDTg. Finally, systemic administration of the nonselective and noncompetitive neuronal nicotinic antagonist mecamylamine (0.5 or 2 mg/kg dose-dependently blocked the expression, and to a lesser extent the development, of locomotor sensitization. The same treatment had no effect on acute morphine antinociception, antinociceptive tolerance or dependence to chronic morphine. Taken together, the results suggest that endogenous nicotinic cholinergic neurotransmission selectively contributes to behavioral sensitization to morphine and this process may, in part, involve cholinergic neurons within the LDTg.

  3. Ablation of NMDA receptors enhances the excitability of hippocampal CA3 neurons.

    Directory of Open Access Journals (Sweden)

    Fumiaki Fukushima

    Full Text Available Synchronized discharges in the hippocampal CA3 recurrent network are supposed to underlie network oscillations, memory formation and seizure generation. In the hippocampal CA3 network, NMDA receptors are abundant at the recurrent synapses but scarce at the mossy fiber synapses. We generated mutant mice in which NMDA receptors were abolished in hippocampal CA3 pyramidal neurons by postnatal day 14. The histological and cytological organizations of the hippocampal CA3 region were indistinguishable between control and mutant mice. We found that mutant mice lacking NMDA receptors selectively in CA3 pyramidal neurons became more susceptible to kainate-induced seizures. Consistently, mutant mice showed characteristic large EEG spikes associated with multiple unit activities (MUA, suggesting enhanced synchronous firing of CA3 neurons. The electrophysiological balance between fast excitatory and inhibitory synaptic transmission was comparable between control and mutant pyramidal neurons in the hippocampal CA3 region, while the NMDA receptor-slow AHP coupling was diminished in the mutant neurons. In the adult brain, inducible ablation of NMDA receptors in the hippocampal CA3 region by the viral expression vector for Cre recombinase also induced similar large EEG spikes. Furthermore, pharmacological blockade of CA3 NMDA receptors enhanced the susceptibility to kainate-induced seizures. These results raise an intriguing possibility that hippocampal CA3 NMDA receptors may suppress the excitability of the recurrent network as a whole in vivo by restricting synchronous firing of CA3 neurons.

  4. Milrinone attenuates thromboxane receptor-mediated hyperresponsiveness in hypoxic pulmonary arterial myocytes.

    Science.gov (United States)

    Santhosh, K T; Elkhateeb, O; Nolette, N; Outbih, O; Halayko, A J; Dakshinamurti, S

    2011-07-01

    Neonatal pulmonary hypertension (PPHN) is characterized by pulmonary vasoconstriction, due in part to dysregulation of the thromboxane prostanoid (TP) receptor. Hypoxia induces TP receptor-mediated hyperresponsiveness, whereas serine phosphorylation mediates desensitization of TP receptors. We hypothesized that prostacyclin (IP) receptor activity induces TP receptor phosphorylation and decreases ligand affinity; that TP receptor sensitization in hypoxic myocytes is due to IP receptor inactivation; and that this would be reversible by the cAMP-specific phosphodiesterase inhibitor milrinone. We examined functional regulation of TP receptors by serine phosphorylation and effects of IP receptor stimulation and protein kinase A (PKA) activity on TP receptor sensitivity in myocytes from neonatal porcine resistance pulmonary arteries after 72 h hypoxia in vitro. Ca(2+) response curves to U46619 (TP receptor agonist) were determined in hypoxic and normoxic myocytes incubated with or without iloprost (IP receptor agonist), forskolin (adenylyl cyclase activator), H8 (PKA inhibitor) or milrinone. TP and IP receptor saturation binding kinetics were measured in presence of iloprost or 8-bromo-cAMP. Ligand affinity for TP receptors was normalized in vitro by IP receptor signalling intermediates. However, IP receptor affinity was compromised in hypoxic myocytes, decreasing cAMP production. Milrinone normalized TP receptor sensitivity in hypoxic myocytes by restoring PKA-mediated regulatory TP receptor phosphorylation. TP receptor sensitivity and EC(50) for TP receptor agonists was regulated by PKA, as TP receptor serine phosphorylation by PKA down-regulated Ca(2+) mobilization. Hypoxia decreased IP receptor activity and cAMP generation, inducing TP receptor hyperresponsiveness, which was reversed by milrinone. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  5. Combined gene overexpression of neuropeptide Y and its receptor Y5 in the hippocampus suppresses seizures

    DEFF Research Database (Denmark)

    Gøtzsche, Casper René; Nikitidou, Litsa; Sørensen, Andreas Toft

    2012-01-01

    We recently demonstrated that recombinant adeno-associated viral vector-induced hippocampal overexpression of neuropeptide Y receptor, Y2, exerts a seizure-suppressant effect in kindling and kainate-induced models of epilepsy in rats. Interestingly, additional overexpression of neuropeptide Y...

  6. Functional relevance of neurotransmitter receptor heteromers in the central nervous system.

    Science.gov (United States)

    Ferré, Sergi; Ciruela, Francisco; Woods, Amina S; Lluis, Carme; Franco, Rafael

    2007-09-01

    The existence of neurotransmitter receptor heteromers is becoming broadly accepted and their functional significance is being revealed. Heteromerization of neurotransmitter receptors produces functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Neurotransmitter receptor heteromers can function as processors of computations that modulate cell signaling. Thus, the quantitative or qualitative aspects of the signaling generated by stimulation of any of the individual receptor units in the heteromer are different from those obtained during coactivation. Furthermore, recent studies demonstrate that some neurotransmitter receptor heteromers can exert an effect as processors of computations that directly modulate both pre- and postsynaptic neurotransmission. This is illustrated by the analysis of striatal receptor heteromers that control striatal glutamatergic neurotransmission.

  7. Expression and localization of ionotropic glutamate receptor subunits in the goldfish retina--an in situ hybridization and immunocytochemical study

    NARCIS (Netherlands)

    Vandenbranden, C. A.; Kamphuis, W.; Nunes Cardozo, B.; Kamermans, M.

    2000-01-01

    The expression and distribution of AMPA, kainate and NMDA glutamate receptor subunits was studied in the goldfish retina. For the immunocytochemical localization of the AMPA receptor antisera against GluR2, GluR2/3 and GluR4 were used, and for in situ hybridization rat specific probes for GluR1 and

  8. Applications of SPECT imaging of dopaminergic neurotransmission in neuropsychiatric disorders

    Energy Technology Data Exchange (ETDEWEB)

    Kugaya, Akira; Fujita, Masahiro; Innis, R.B. [Yale Univ., New Haven, CT (United States). School of Medicine

    2000-02-01

    Single photon emission computed tomography (SPECT) tracers selective for pre- and post-synaptic targets have allowed measurements of several aspects of dopaminergic (DA) neurotransmission. In this article, we will first review our DA transporter imaging in Parkinson's disease. We have developed the in vivo dopamine transporter (DAT) imaging with [{sup 123}I]{beta}-CIT ((1R)-2{beta}-Carbomethoxy-3{beta}-(4-iodophenyl)tropane). This method showed that patients with Parkinson's disease have markedly reduced DAT levels in striatum, which correlated with disease severity and disease progression. Second, we applied DA imaging techniques in patients with schizophrenia. Using amphetamine as a releaser of DA, we observed the enhanced DA release, which was measured by imaging D2 receptors with [{sup 123}I]IBZM (iodobenzamide), in schizophrenics. Further we developed the measurement of basal synaptic DA levels by AMPT (alpha-methyl-paratyrosine)-induced unmasking of D2 receptors. Finally, we expanded our techniques to the measurement of extrastriatal DA receptors using [{sup 123}I]epidepride. The findings suggest that SPECT is a useful technique to measure DA transmission in human brain and may further our understanding of the pathophysiology of neuropsychiatric disorders. (author)

  9. Cholinergic neurotransmission in human corpus cavernosum. II. Acetylcholine synthesis

    International Nuclear Information System (INIS)

    Blanco, R.; De Tejada, S.; Goldstein, I.; Krane, R.J.; Wotiz, H.H.; Cohen, R.A.

    1988-01-01

    Physiological and histochemical evidence indicates that cholinergic nerves may participate in mediating penile erection. Acetylcholine synthesis and release was studied in isolated human corporal tissue. Human corpus cavernosum incubated with [ 3 H]choline accumulated [ 3 H]choline and synthesized [ 3 H]acethylcholine in an concentration-dependent manner. [ 3 H]Acetylcholine accumulation by the tissue was inhibited by hemicholinium-3, a specific antagonist of the high-affinity choline transport in cholinergic nerves. Transmural electrical field stimulation caused release of [ 3 H]acetylcholine which was significantly diminished by inhibiting neurotransmission with calcium-free physiological salt solution or tetrodotoxin. These observations provide biochemical and physiological evidence for the existence of cholinergic innervation in human corpus cavernosum

  10. Cell cycle-dependent regulation of kainate-induced inward currents in microglia

    International Nuclear Information System (INIS)

    Yamada, Jun; Sawada, Makoto; Nakanishi, Hiroshi

    2006-01-01

    Microglia are reported to have α-amino-hydroxy-5-methyl-isoxazole-4-propionate/kainate (KA) types. However, only small population of primary cultured rat microglia (approximately 20%) responded to KA. In the present study, we have attempted to elucidate the regulatory mechanism of responsiveness to KA in GMIR1 rat microglial cell line. When the GMIR1 cells were plated at a low density in the presence of granulocyte macrophage colony-stimulating factor, the proliferation rate increased and reached the peak after 2 days in culture and then gradually decreased because of density-dependent inhibition. At cell proliferation stage, approximately 80% of the GMIR1 cells exhibited glutamate (Glu)- and KA-induced inward currents at cell proliferation stage, whereas only 22.5% of the cells showed responsiveness to Glu and KA at cell quiescent stage. Furthermore, the mean amplitudes of inward currents induced by Glu and KA at cell proliferation stage (13.8 ± 3.0 and 8.4 ± 0.6 pA) were significantly larger than those obtained at cell quiescent stage (4.7 ± 0.8 and 6.2 ± 1.2 pA). In the GMIR1 cells, KA-induced inward currents were markedly inhibited by (RS)-3-(2-carboxybenzyl) willardiine (UBP296), a selective antagonist for KA receptors. The KA-responsive cells also responded to (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), a selective agonist for GluR5, in both GMIR1 cells and primary cultured rat microglia. Furthermore, mRNA levels of the KA receptor subunits, GluR5 and GluR6, at the cell proliferation stage were significantly higher than those at the cell quiescent stage. Furthermore, the immunoreactivity for GluR6/7 was found to increase in activated microglia in the post-ischemic hippocampus. These results strongly suggest that microglia have functional KA receptors mainly consisting of GluR5 and GluR6, and the expression levels of these subunits are closely regulated by the cell cycle mechanism

  11. In vitro autoradiography of ionotropic glutamate receptors in hippocampus and striatum of aged Long-Evans rats: relationship to spatial learning

    International Nuclear Information System (INIS)

    Gallagher, M.; Bizon, J.L.; Nicolle, M.M.

    1996-01-01

    Using in vitro autoradiography, we investigated [ 3 H]α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate, [ 3 H]kainate and [ 3 H]N-methyl-d-aspartate binding in two forebrain regions, the hippocampus and striatum, of young (four months of age) and aged (24-25 months of age) Long-Evans rats that had previously been tested for spatial learning ability in the Morris water maze. Although there was substantial preservation of binding in the aged rats, reductions in binding were present in the aged rats that were specific to ligand and anatomical region. In the hippocampus of aged rats, [ 3 H]α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate binding in CA1 and [ 3 H]kainate binding in CA3 were reduced. In contrast, N-methyl-d-aspartate binding was not significantly different between age groups. There was evidence of sprouting in the dentate gyrus molecular layer of aged rats, indicated by changes in the topography of [ 3 H]kainate binding. Binding density was analysed with respect to patch/matrix compartmentalization in the striatum. The most striking result was a large decrease in N-methyl-d-aspartate binding in aged rats that was not limited to any dorsal/ventral or patch/matrix area of the striatum. Additionally, [ 3 H]kainate binding in striatal matrix was modestly reduced in aged rats. Of these age effects, only N-methyl-d-aspartate binding in the striatum and [ 3 H]kainate binding in the CA3 region of the hippocampus were correlated with spatial learning, with lower binding in the aged rats associated with better spatial learning ability.Age-related alterations in ionotropic glutamate receptors differ with respect to the receptor subtype and anatomical region examined. The age effects were not neccessarily indicative of cognitive decline, as only two age-related binding changes were correlated with spatial learning. Interestingly, in these instances, lower binding in the aged rats was associated with preserved spatial learning, suggesting a compensatory reduction

  12. Inhibition of facilitation of sympathetic neurotransmission and angiotensin II-induced pressor effects in the pithed rat: comparison between valsartan, candesartan, eprosartan and embusartan

    NARCIS (Netherlands)

    Balt, J. C.; Mathy, M. J.; Pfaffendorf, M.; van Zwieten, P. A.

    2001-01-01

    In the pithed rat model, endogenously generated angiotensin (Ang) II can enhance sympathetic neurotransmission by acting on Ang II type 1 (AT1) receptors that are located on sympathetic nerve terminals. To compare the inhibitory potency of candesartan, valsartan, eprosartan and embusartan in

  13. Scavenger receptor-mediated endocytosis by sinusoidal cells in rat bone marrow

    International Nuclear Information System (INIS)

    Geoffroy, J.S.

    1987-01-01

    Endocytosis of serum albumin by sinusoidal endothelial cells in rat bone marrow was investigated initially at the ultrastructural level with subsequent biochemical investigation of the specificity mediating this event. Bovine serum albumin adsorbed to 20nm colloidal gold particles (AuBSA) was chosen as the electron microscopic probe. Morphological data strongly suggested that a receptor was involved in uptake of AuBSA. Confirmation of receptor involvement in the uptake of AuBSA by marrow sinusoidal endothelial cells was achieved utilizing an in situ isolated hind limb perfusion protocol in conjunction with unlabeled, radiolabeled, and radio-/colloidal gold labeled probes. The major findings of competition and saturation experiments were: (1) endocytosis of AuBSA was mediated by a receptor for modified/treated serum albumin; (2) endocytosis of formaldehyde-treated serum albumin was mediated by a binding site which may be the same or closely related to the site responsible for the uptake of AuBSA; and (3) endocytosis of native untreated albumin was not mediated by receptor and probably represents fluid-phase pinocitosis

  14. Neurotransmission to parasympathetic cardiac vagal neurons in the brain stem is altered with left ventricular hypertrophy-induced heart failure.

    Science.gov (United States)

    Cauley, Edmund; Wang, Xin; Dyavanapalli, Jhansi; Sun, Ke; Garrott, Kara; Kuzmiak-Glancy, Sarah; Kay, Matthew W; Mendelowitz, David

    2015-10-01

    Hypertension, cardiac hypertrophy, and heart failure (HF) are widespread and debilitating cardiovascular diseases that affect nearly 23 million people worldwide. A distinctive hallmark of these cardiovascular diseases is autonomic imbalance, with increased sympathetic activity and decreased parasympathetic vagal tone. Recent device-based approaches, such as implantable vagal stimulators that stimulate a multitude of visceral sensory and motor fibers in the vagus nerve, are being evaluated as new therapeutic approaches for these and other diseases. However, little is known about how parasympathetic activity to the heart is altered with these diseases, and this lack of knowledge is an obstacle in the goal of devising selective interventions that can target and selectively restore parasympathetic activity to the heart. To identify the changes that occur within the brain stem to diminish the parasympathetic cardiac activity, left ventricular hypertrophy was elicited in rats by aortic pressure overload using a transaortic constriction approach. Cardiac vagal neurons (CVNs) in the brain stem that generate parasympathetic activity to the heart were identified with a retrograde tracer and studied using patch-clamp electrophysiological recordings in vitro. Animals with left cardiac hypertrophy had diminished excitation of CVNs, which was mediated both by an augmented frequency of spontaneous inhibitory GABAergic neurotransmission (with no alteration of inhibitory glycinergic activity) as well as a diminished amplitude and frequency of excitatory neurotransmission to CVNs. Opportunities to alter these network pathways and neurotransmitter receptors provide future targets of intervention in the goal to restore parasympathetic activity and autonomic balance to the heart in cardiac hypertrophy and other cardiovascular diseases. Copyright © 2015 the American Physiological Society.

  15. Contributions of conserved residues at the gating interface of glycine receptors

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Leung, Ada W Y; Galpin, Jason D

    2011-01-01

    and the in vivo nonsense suppression method to incorporate unnatural amino acids to probe the electrostatic and hydrophobic contributions of five highly conserved side chains near the interface, Glu-53, Phe-145, Asp-148, Phe-187, and Arg-218. Our results suggest a salt bridge between Asp-148 in loop 7 and Arg-218......Glycine receptors (GlyRs) are chloride channels that mediate fast inhibitory neurotransmission and are members of the pentameric ligand-gated ion channel (pLGIC) family. The interface between the ligand binding domain and the transmembrane domain of pLGICs has been proposed to be crucial...

  16. (R-[11C]Verapamil PET studies to assess changes in P-glycoprotein expression and functionality in rat blood-brain barrier after exposure to kainate-induced status epilepticus

    Directory of Open Access Journals (Sweden)

    Lammertsma Adriaan A

    2011-01-01

    Full Text Available Abstract Background Increased functionality of efflux transporters at the blood-brain barrier may contribute to decreased drug concentrations at the target site in CNS diseases like epilepsy. In the rat, pharmacoresistant epilepsy can be mimicked by inducing status epilepticus by intraperitoneal injection of kainate, which leads to development of spontaneous seizures after 3 weeks to 3 months. The aim of this study was to investigate potential changes in P-glycoprotein (P-gp expression and functionality at an early stage after induction of status epilepticus by kainate. Methods (R-[11C]verapamil, which is currently the most frequently used positron emission tomography (PET ligand for determining P-gp functionality at the blood-brain barrier, was used in kainate and saline (control treated rats, at 7 days after treatment. To investigate the effect of P-gp on (R-[11C]verapamil brain distribution, both groups were studied without or with co-administration of the P-gp inhibitor tariquidar. P-gp expression was determined using immunohistochemistry in post mortem brains. (R-[11C]verapamil kinetics were analyzed with approaches common in PET research (Logan analysis, and compartmental modelling of individual profiles as well as by population mixed effects modelling (NONMEM. Results All data analysis approaches indicated only modest differences in brain distribution of (R-[11C]verapamil between saline and kainate treated rats, while tariquidar treatment in both groups resulted in a more than 10-fold increase. NONMEM provided most precise parameter estimates. P-gp expression was found to be similar for kainate and saline treated rats. Conclusions P-gp expression and functionality does not seem to change at early stage after induction of anticipated pharmacoresistant epilepsy by kainate.

  17. (R)-[11C]Verapamil PET studies to assess changes in P-glycoprotein expression and functionality in rat blood-brain barrier after exposure to kainate-induced status epilepticus

    International Nuclear Information System (INIS)

    Syvänen, Stina; Luurtsema, Gert; Molthoff, Carla FM; Windhorst, Albert D; Huisman, Marc C; Lammertsma, Adriaan A; Voskuyl, Rob A; Lange, Elizabeth C de

    2011-01-01

    Increased functionality of efflux transporters at the blood-brain barrier may contribute to decreased drug concentrations at the target site in CNS diseases like epilepsy. In the rat, pharmacoresistant epilepsy can be mimicked by inducing status epilepticus by intraperitoneal injection of kainate, which leads to development of spontaneous seizures after 3 weeks to 3 months. The aim of this study was to investigate potential changes in P-glycoprotein (P-gp) expression and functionality at an early stage after induction of status epilepticus by kainate. (R)-[ 11 C]verapamil, which is currently the most frequently used positron emission tomography (PET) ligand for determining P-gp functionality at the blood-brain barrier, was used in kainate and saline (control) treated rats, at 7 days after treatment. To investigate the effect of P-gp on (R)-[ 11 C]verapamil brain distribution, both groups were studied without or with co-administration of the P-gp inhibitor tariquidar. P-gp expression was determined using immunohistochemistry in post mortem brains. (R)-[ 11 C]verapamil kinetics were analyzed with approaches common in PET research (Logan analysis, and compartmental modelling of individual profiles) as well as by population mixed effects modelling (NONMEM). All data analysis approaches indicated only modest differences in brain distribution of (R)-[ 11 C]verapamil between saline and kainate treated rats, while tariquidar treatment in both groups resulted in a more than 10-fold increase. NONMEM provided most precise parameter estimates. P-gp expression was found to be similar for kainate and saline treated rats. P-gp expression and functionality does not seem to change at early stage after induction of anticipated pharmacoresistant epilepsy by kainate

  18. Visualization of spatiotemporal energy dynamics of hippocampal neurons by mass spectrometry during a kainate-induced seizure.

    Directory of Open Access Journals (Sweden)

    Yuki Sugiura

    Full Text Available We report the use of matrix-assisted laser desorption/ionization (MALDI imaging mass spectrometry combined with capillary electrophoresis (CE mass spectrometry to visualize energy metabolism in the mouse hippocampus by imaging energy-related metabolites. We show the distribution patterns of ATP, ADP, and AMP in the hippocampus as well as changes in their amounts and distribution patterns in a murine model of limbic, kainate-induced seizure. As an acute response to kainate administration, we found massive and moderate reductions in ATP and ADP levels, respectively, but no significant changes in AMP levels--especially in cells of the CA3 layer. The results suggest the existence of CA3 neuron-selective energy metabolism at the anhydride bonds of ATP and ADP in the hippocampal neurons during seizure. In addition, metabolome analysis of energy synthesis pathways indicates accelerated glycolysis and possibly TCA cycle activity during seizure, presumably due to the depletion of ATP. Consistent with this result, the observed energy depletion significantly recovered up to 180 min after kainate administration. However, the recovery rate was remarkably low in part of the data-pixel population in the CA3 cell layer region, which likely reflects acute and CA3-selective neural death. Taken together, the present approach successfully revealed the spatiotemporal energy metabolism of the mouse hippocampus at a cellular resolution--both quantitatively and qualitatively. We aim to further elucidate various metabolic processes in the neural system.

  19. A new potential AED, carisbamate, substantially reduces spontaneous motor seizures in rats with kainate-induced epilepsy

    Science.gov (United States)

    Grabenstatter, Heidi L.; Dudek, F. Edward

    2010-01-01

    Purpose Animal models with spontaneous epileptic seizures may be useful in the discovery of new antiepileptic drugs (AEDs). The purpose of the present study was to evaluate the efficacy of carisbamate on spontaneous motor seizures in rats with kainate-induced epilepsy. Methods Repeated, low-dose (5 mg/kg), intraperitoneal injections of kainate were administered every hour until each male Sprague-Dawley rat had experienced convulsive status epilepticus for at least 3 h. Five 1-month trials (n= 8–10 rats) assessed the effects of 0.3, 1, 3, 10 and 30 mg/kg carisbamate on spontaneous seizures. Each trial involved six AED-versus-vehicle tests comprised of carisbamate or 10% solutol-HS-15 treatments administered as intraperitoneal injections on alternate days with a recovery day between each treatment day. Results Carisbamate significantly reduced motor seizure frequency at doses of 10 and 30 mg/kg, and caused complete seizure cessation during the 6-h post-drug epoch in 7 of 8 animals at 30 mg/kg. The effects of carisbamate (0.3–30 mg/kg) on spontaneous motor seizures appeared dose dependent. Conclusions These data support the hypothesis that a repeated-measures, cross-over protocol in animal models with spontaneous seizures is an effective method for testing AEDs. Carisbamate reduced the frequency of spontaneous motor seizures in a dose-dependent manner, and was more effective than topiramate at reducing seizures in rats with kainate-induced epilepsy. PMID:18494790

  20. Crosstalk between G protein-coupled receptors (GPCRs and tyrosine kinase receptor (TXR in the heart after morphine withdrawal

    Directory of Open Access Journals (Sweden)

    Pilar eAlmela

    2013-12-01

    Full Text Available G protein-coupled receptors (GPCRs comprise a large family of membrane receptors involved in signal transduction. These receptors are linked to a variety of physiological and biological processes such as regulation of neurotransmission, growth and cell differentiation among others. Some of the effects of GPCRs are known to be mediated by the activation of mitogen-activated extracellular kinase (MAPK pathways. Cross-talk among various signal pathways plays an important role in activation of intracellular and intranuclear signal transduction cascades. Naloxone-induced morphine withdrawal leads to an up-regulation of adenyl cyclase-mediated signalling, resulting in high expression of protein kinase (PK A. In addition, there is also an increased expression of extracellular signal regulated kinase (ERK, one member of MAPK. For this reason, the crosstalk between these GPCRs and receptors with tyrosine kinase activity (TKR can be considered a possible mechanism for adaptive changes that occurs after morphine withdrawal. Morphine withdrawal activates ERK1/2 and phosphorylated tyrosine hydroxylase (TH at Ser31 in the right and left ventricle. When N-(2-guanidinoethyl-5-isoquinolinesulfonamide (HA-1004, a PKA inhibitor was infused, the ability of morphine withdrawal to activate ERK, which phosphorylates TH at Ser31, was reduced. The present finding demonstrated that the enhancement of ERK1/2 expression and the phosphorylation state of TH at Ser31 during morphine withdrawal are dependent on PKA and suggest cross-talk between PKA and ERK1/2 transduction pathway mediating morphine withdrawal-induced activation of TH. Increasing understanding of the mechanisms that interconnect the two pathway regulated by GPCRs and TKRs may facilitate the design of new therapeutic strategies.

  1. Facilitation of granule cell epileptiform activity by mossy fiber-released zinc in the pilocarpine model of temporal lobe epilepsy.

    Science.gov (United States)

    Timofeeva, Olga; Nadler, J Victor

    2006-03-17

    Recurrent mossy fiber synapses in the dentate gyrus of epileptic brain facilitate the synchronous firing of granule cells and may promote seizure propagation. Mossy fiber terminals contain and release zinc. Released zinc inhibits the activation of NMDA receptors and may therefore oppose the development of granule cell epileptiform activity. Hippocampal slices from rats that had experienced pilocarpine-induced status epilepticus and developed a recurrent mossy fiber pathway were used to investigate this possibility. Actions of released zinc were inferred from the effects of chelation with 1 mM calcium disodium EDTA (CaEDTA). When granule cell population bursts were evoked by mossy fiber stimulation in the presence of 6 mM K(+) and 30 microM bicuculline, CaEDTA slowed the rate at which evoked bursting developed, but did not change the magnitude of the bursts once they had developed fully. The effects of CaEDTA were then studied on the pharmacologically isolated NMDA receptor- and AMPA/kainate receptor-mediated components of the fully developed bursts. CaEDTA increased the magnitude of NMDA receptor-mediated bursts and reduced the magnitude of AMPA/kainate receptor-mediated bursts. CaEDTA did not affect the granule cell bursts evoked in slices from untreated rats by stimulating the perforant path in the presence of bicuculline and 6 mM K(+). These results suggest that zinc released from the recurrent mossy fibers serves mainly to facilitate the recruitment of dentate granule cells into population bursts.

  2. Plant cell surface receptor-mediated signaling - a common theme amid diversity.

    Science.gov (United States)

    He, Yunxia; Zhou, Jinggeng; Shan, Libo; Meng, Xiangzong

    2018-01-29

    Sessile plants employ a diverse array of plasma membrane-bound receptors to perceive endogenous and exogenous signals for regulation of plant growth, development and immunity. These cell surface receptors include receptor-like kinases (RLKs) and receptor-like proteins (RLPs) that harbor different extracellular domains for perception of distinct ligands. Several RLK and RLP signaling pathways converge at the somatic embryogenesis receptor kinases (SERKs), which function as shared co-receptors. A repertoire of receptor-like cytoplasmic kinases (RLCKs) associate with the receptor complexes to relay intracellular signaling. Downstream of the receptor complexes, mitogen-activated protein kinase (MAPK) cascades are among the key signaling modules at which the signals converge, and these cascades regulate diverse cellular and physiological responses through phosphorylation of different downstream substrates. In this Review, we summarize the emerging common theme that underlies cell surface receptor-mediated signaling pathways in Arabidopsis thaliana : the dynamic association of RLKs and RLPs with specific co-receptors and RLCKs for signal transduction. We further discuss how signaling specificities are maintained through modules at which signals converge, with a focus on SERK-mediated receptor signaling. © 2018. Published by The Company of Biologists Ltd.

  3. Neuropharmacology of purinergic receptors in human submucous plexus: Involvement of P2X₁, P2X₂, P2X₃ channels, P2Y and A₃ metabotropic receptors in neurotransmission.

    Science.gov (United States)

    Liñán-Rico, A; Wunderlich, J E; Enneking, J T; Tso, D R; Grants, I; Williams, K C; Otey, A; Michel, K; Schemann, M; Needleman, B; Harzman, A; Christofi, F L

    2015-08-01

    The role of purinergic signaling in human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. LSCM-Fluo-4/(Ca(2+))-imaging of postsynaptic Ca(2+) transients (PSCaTs) was used as a reporter of synaptic transmission evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons (identified by HuC/D-immunoreactivity) in 235 ganglia from 107 patients; P2XR-immunoreactivity was evaluated in 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging tested effects of adenosine on fast excitatory synaptic potentials (fEPSPs). Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines: Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50 = 25 µM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50 = 111 nM) in neurons without stimulatory ADPbS responses (EC50 = 960 nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca(2+) transients or Ca(2+) oscillations (ATP,EC50 = 400 mM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20 nM) or high (5 µM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-immunoreactivity follow the order P2X2 > P2X1 > P2X3; P2X1 + P2X2 and P2X3 + P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7, P2Y1,2,12-14R. Purines are critical regulators of neurotransmission in human ENS. Purinergic signaling involves P2X1, P2X2, P2X3 channels, P2X1 + P2X2 co-localization and inhibitory P2Y or A3 receptors. These are

  4. Safeguards of Neurotransmission: Endocytic Adaptors as Regulators of Synaptic Vesicle Composition and Function

    Directory of Open Access Journals (Sweden)

    Natalie Kaempf

    2017-10-01

    Full Text Available Communication between neurons relies on neurotransmitters which are released from synaptic vesicles (SVs upon Ca2+ stimuli. To efficiently load neurotransmitters, sense the rise in intracellular Ca2+ and fuse with the presynaptic membrane, SVs need to be equipped with a stringently controlled set of transmembrane proteins. In fact, changes in SV protein composition quickly compromise neurotransmission and most prominently give rise to epileptic seizures. During exocytosis SVs fully collapse into the presynaptic membrane and consequently have to be replenished to sustain neurotransmission. Therefore, surface-stranded SV proteins have to be efficiently retrieved post-fusion to be used for the generation of a new set of fully functional SVs, a process in which dedicated endocytic sorting adaptors play a crucial role. The question of how the precise reformation of SVs is achieved is intimately linked to how SV membranes are retrieved. For a long time both processes were believed to be two sides of the same coin since Clathrin-mediated endocytosis (CME, the proposed predominant SV recycling mode, will jointly retrieve SV membranes and proteins. However, with the recent proposal of Clathrin-independent SV recycling pathways SV membrane retrieval and SV reformation turn into separable events. This review highlights the progress made in unraveling the molecular mechanisms mediating the high-fidelity retrieval of SV proteins and discusses how the gathered knowledge about SV protein recycling fits in with the new notions of SV membrane endocytosis.

  5. (R)-[{sup 11}C]Verapamil PET studies to assess changes in P-glycoprotein expression and functionality in rat blood-brain barrier after exposure to kainate-induced status epilepticus

    Energy Technology Data Exchange (ETDEWEB)

    Syvänen, Stina [Division of Pharmacology, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Luurtsema, Gert [Department of Nuclear Medicine & Molecular Imaging, Groningen University Medical Center, P.O. Box 30.001 9700 RB Groningen (Netherlands); Molthoff, Carla FM; Windhorst, Albert D; Huisman, Marc C; Lammertsma, Adriaan A [Department of Nuclear Medicine & PET Research, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam (Netherlands); Voskuyl, Rob A [Division of Pharmacology, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Epilepsy Institute of The Netherlands Foundation (SEIN), P.O. Box 21, 2100 AA, Heemstede (Netherlands); Lange, Elizabeth C de [Division of Pharmacology, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands)

    2011-01-03

    Increased functionality of efflux transporters at the blood-brain barrier may contribute to decreased drug concentrations at the target site in CNS diseases like epilepsy. In the rat, pharmacoresistant epilepsy can be mimicked by inducing status epilepticus by intraperitoneal injection of kainate, which leads to development of spontaneous seizures after 3 weeks to 3 months. The aim of this study was to investigate potential changes in P-glycoprotein (P-gp) expression and functionality at an early stage after induction of status epilepticus by kainate. (R)-[{sup 11}C]verapamil, which is currently the most frequently used positron emission tomography (PET) ligand for determining P-gp functionality at the blood-brain barrier, was used in kainate and saline (control) treated rats, at 7 days after treatment. To investigate the effect of P-gp on (R)-[{sup 11}C]verapamil brain distribution, both groups were studied without or with co-administration of the P-gp inhibitor tariquidar. P-gp expression was determined using immunohistochemistry in post mortem brains. (R)-[{sup 11}C]verapamil kinetics were analyzed with approaches common in PET research (Logan analysis, and compartmental modelling of individual profiles) as well as by population mixed effects modelling (NONMEM). All data analysis approaches indicated only modest differences in brain distribution of (R)-[{sup 11}C]verapamil between saline and kainate treated rats, while tariquidar treatment in both groups resulted in a more than 10-fold increase. NONMEM provided most precise parameter estimates. P-gp expression was found to be similar for kainate and saline treated rats. P-gp expression and functionality does not seem to change at early stage after induction of anticipated pharmacoresistant epilepsy by kainate.

  6. Excitatory and inhibitory pathways modulate kainate excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Rai, R

    1993-01-01

    In organotypic hippocampal slice cultures, kainate (KA) specifically induces cell loss in the CA3 region while N-methyl-D-aspartate induces cell loss in the CA1 region. The sensitivity of slice cultures to KA toxicity appears only after 2 weeks in vitro which parallels the appearance of mossy...... fibers. KA toxicity is potentiated by co-application with the GABA-A antagonist, picrotoxin. These data suggest that the excitotoxicity of KA in slice cultures is modulated by both excitatory and inhibitory synapses....

  7. Somatostatin receptor-mediated imaging and therapy: basic science, current knowledge, limitations and future perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Breeman, W.A.P.; Jong, M. de; Kwekkeboom, D.J.; Valkema, R.; Bakker, W.H.; Kooij, P.P.M. [Dept. of Nuclear Medicine, Erasmus Medical Centre Rotterdam (Netherlands); Visser, T.J. [Dept. of Internal Medicine, Erasmus Medical Centre Rotterdam (Netherlands); Krenning, E.P. [Dept. of Nuclear Medicine, Erasmus Medical Centre Rotterdam (Netherlands); Dept. of Internal Medicine, Erasmus Medical Centre Rotterdam (Netherlands)

    2001-09-01

    In vivo somatostatin receptor-mediated scintigraphy has proven to be a valuable method for the visualisation of neuroendocrine tumours and their metastases. A new application is the use of radiolabelled analogues for somatostatin receptor-mediated therapy. This paper presents a review on the basic science, historical background and current knowledge of somatostatin receptor subtypes and their expression in neuroendocrine tumours. New somatostatin analogues, new chelators, ''new'' radionuclides and combinations thereof are also discussed. Due attention is given to limitations and future perspectives of somatostatin receptor-mediated imaging and therapy. (orig.)

  8. Somatostatin receptor-mediated imaging and therapy: basic science, current knowledge, limitations and future perspectives

    International Nuclear Information System (INIS)

    Breeman, W.A.P.; Jong, M. de; Kwekkeboom, D.J.; Valkema, R.; Bakker, W.H.; Kooij, P.P.M.; Visser, T.J.; Krenning, E.P.

    2001-01-01

    In vivo somatostatin receptor-mediated scintigraphy has proven to be a valuable method for the visualisation of neuroendocrine tumours and their metastases. A new application is the use of radiolabelled analogues for somatostatin receptor-mediated therapy. This paper presents a review on the basic science, historical background and current knowledge of somatostatin receptor subtypes and their expression in neuroendocrine tumours. New somatostatin analogues, new chelators, ''new'' radionuclides and combinations thereof are also discussed. Due attention is given to limitations and future perspectives of somatostatin receptor-mediated imaging and therapy. (orig.)

  9. Selective effect of cell membrane on synaptic neurotransmission

    DEFF Research Database (Denmark)

    Postila, Pekka A.; Vattulainen, Ilpo; Róg, Tomasz

    2016-01-01

    Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic membr...... the importance of cell membrane and specific lipids for neurotransmission, should to be of interest to neuroscientists, drug industry and the general public alike.......Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic...... membrane surface whenever the ligand-binding sites of their synaptic receptors are buried in the lipid bilayer. In contrast, NTs that have extracellular ligand-binding sites do not have a similar tendency to adhere to the membrane surface. This finding is a seemingly simple yet important addition...

  10. Pacemaker activity and inhibitory neurotransmission in the colon of Ws/Ws mutant rats

    DEFF Research Database (Denmark)

    Albertí, Elena; Mikkelsen, Hanne Birte; Wang, Xuanyu

    2007-01-01

    The aim of this study was to characterize the pacemaker activity and inhibitory neurotransmission in the colon of Ws/Ws mutant rats, which harbor a mutation in the c-kit gene that affects development of interstitial cells of Cajal (ICC). In Ws/Ws rats, the density of KIT-positive cells was markedly...... as indirect innervation via ICC. In summary, loss of ICC markedly affects pacemaker and motor activities of the rat colon. Inhibitory innervation is largely maintained but nitrergic innervation is reduced possibly related to the loss of ICC-mediated relaxation....

  11. Activation of GABAB receptors inhibits protein kinase B /Glycogen Synthase Kinase 3 signaling

    Directory of Open Access Journals (Sweden)

    Lu Frances Fangjia

    2012-11-01

    Full Text Available Abstract Accumulated evidence has suggested that potentiation of cortical GABAergic inhibitory neurotransmission may be a key mechanism in the treatment of schizophrenia. However, the downstream molecular mechanisms related to GABA potentiation remain unexplored. Recent studies have suggested that dopamine D2 receptor antagonists, which are used in the clinical treatment of schizophrenia, modulate protein kinase B (Akt/glycogen synthase kinase (GSK-3 signaling. Here we report that activation of GABAB receptors significantly inhibits Akt/GSK-3 signaling in a β-arrestin-dependent pathway. Agonist stimulation of GABAB receptors enhances the phosphorylation of Akt (Thr-308 and enhances the phosphorylation of GSK-3α (Ser-21/β (Ser-9 in both HEK-293T cells expressing GABAB receptors and rat hippocampal slices. Furthermore, knocking down the expression of β-arrestin2 using siRNA abolishes the GABAB receptor-mediated modulation of GSK-3 signaling. Our data may help to identify potentially novel targets through which GABAB receptor agents may exert therapeutic effects in the treatment of schizophrenia.

  12. Ablation of the auditory cortex results in changes in the expression of neurotransmission-related mRNAs in the cochlea.

    Science.gov (United States)

    Lamas, Verónica; Juiz, José M; Merchán, Miguel A

    2017-03-01

    The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the α10 nicotinic acetylcholine receptor (nAchR). In this report, we show that descending connections from AC to olivocochlear neurons are necessary to regulate the expression of molecules involved in cochlear afferent signaling. RT-qPCR was performed in rats at 1, 7 and 15 days after unilateral ablation of the AC, and analyzed the time course changes in gene transcripts involved in neurotransmission at the first auditory synapse. This included the glutamate metabolism enzyme glutamate decarboxylase 1 (glud1) and AMPA glutamate receptor subunits GluA2-4. In addition, gene transcripts involved in efferent regulation of type I spiral ganglion neuron (SGN) excitability mediated by LOC, such as the α7 nAchR, the D2 dopamine receptor, and the α1, and γ2 GABAA receptor subunits, were also investigated. Unilateral AC ablation induced up-regulation of GluA3 receptor subunit transcripts, whereas both GluA2 and GluA4 mRNA receptors were down-regulated already at 1 day after the ablation. Unilateral removal of the AC also resulted in up-regulation of the transcripts for α7 nAchR subunit, D2 dopamine receptor, and α1 GABAA receptor subunit at 1 day after the ablation. Fifteen days after the injury, AC ablations induced an up-regulation of glud1 transcripts. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  13. The endocannabinoid anandamide regulates the peristaltic reflex by reducing neuro-neuronal and neuro-muscular neurotransmission in ascending myenteric reflex pathways in rats.

    Science.gov (United States)

    Sibaev, Andrei; Yuece, Birol; Allescher, Hans Dieter; Saur, Dieter; Storr, Martin; Kurjak, Manfred

    2014-04-01

    Endocannabinoids (EC) and the cannabinoid-1 (CB1) receptor are involved in the regulation of motility in the gastrointestinal (GI) tract. However, the underlying physiological mechanisms are not completely resolved. The purpose of this work was to study the physiological influence of the endocannabinoid anandamide, the putative endogenous CB1 active cannabinoid, and of the CB1 receptor on ascending peristaltic activity and to identify the involved neuro-neuronal, neuro-muscular and electrophysiological mechanisms. The effects of anandamide and the CB1 receptor antagonist SR141716A were investigated on contractions of the circular smooth muscle of rat ileum and in longitudinal rat ileum segments where the ascending myenteric part of the peristaltic reflex was studied in a newly designed organ bath. Additionally intracellular recordings were performed in ileum and colon. Anandamide significantly reduced cholinergic twitch contractions of ileum smooth muscle whereas SR141716A caused an increase. Anandamide reduced the ascending peristaltic contraction by affecting neuro-neuronal and neuro-muscular neurotransmission. SR141716A showed opposite effects and all anandamide effects were antagonized by SR141716A (1 μM). Anandamide reduced excitatory junction potentials (EJP) and inhibitory junction potentials (IJP), whereas intestinal slow waves were not affected. CB1 receptors regulate force and timing of the intestinal peristaltic reflex and these actions involve interneurons and motor-neurons. The endogenous cannabinoid anandamide mediates these effects by activation of CB1 receptors. The endogenous cannabinoid system is permanently active, suggesting the CB1 receptor being a possible target for the treatment of motility related disorders. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  14. D-Serine and Glycine Differentially Control Neurotransmission during Visual Cortex Critical Period.

    Directory of Open Access Journals (Sweden)

    Claire N J Meunier

    Full Text Available N-methyl-D-aspartate receptors (NMDARs play a central role in synaptic plasticity. Their activation requires the binding of both glutamate and d-serine or glycine as co-agonist. The prevalence of either co-agonist on NMDA-receptor function differs between brain regions and remains undetermined in the visual cortex (VC at the critical period of postnatal development. Here, we therefore investigated the regulatory role that d-serine and/or glycine may exert on NMDARs function and on synaptic plasticity in the rat VC layer 5 pyramidal neurons of young rats. Using selective enzymatic depletion of d-serine or glycine, we demonstrate that d-serine and not glycine is the endogenous co-agonist of synaptic NMDARs required for the induction and expression of Long Term Potentiation (LTP at both excitatory and inhibitory synapses. Glycine on the other hand is not involved in synaptic efficacy per se but regulates excitatory and inhibitory neurotransmission by activating strychnine-sensitive glycine receptors, then producing a shunting inhibition that controls neuronal gain and results in a depression of synaptic inputs at the somatic level after dendritic integration. In conclusion, we describe for the first time that in the VC both D-serine and glycine differentially regulate somatic depolarization through the activation of distinct synaptic and extrasynaptic receptors.

  15. DMPD: Modulation of Toll-interleukin 1 receptor mediated signaling. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 15662540 Modulation of Toll-interleukin 1 receptor mediated signaling. Li X, Qin J.... J Mol Med. 2005 Apr;83(4):258-66. Epub 2005 Jan 21. (.png) (.svg) (.html) (.csml) Show Modulation of Toll-i...nterleukin 1 receptor mediated signaling. PubmedID 15662540 Title Modulation of Toll-interleukin 1 receptor

  16. Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects.

    Science.gov (United States)

    Salomone, Salvatore; Waeber, Christian

    2011-01-01

    Receptors for sphingosine-1-phosphate (S1P) have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444), used extensively as specific S1P(2) and S1P(3) receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P(2) receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca(2+) concentration via P(2) receptor or α(1A)-adrenoceptor stimulation and α(1A)-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P(3)-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P(1/3) receptor antagonist, VPC23019, does not inhibit S1P(3)-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

  17. Selectivity and specificity of sphingosine-1-phosphate receptor ligands: caveats and critical thinking in characterizing receptor-mediated effects

    Directory of Open Access Journals (Sweden)

    Christian eWaeber

    2011-02-01

    Full Text Available Receptors for sphingosine-1-phosphate (S1P have been identified only recently. Their medicinal chemistry is therefore still in its infancy, and few selective agonists or antagonists are available. Furthermore, the selectivity of S1P receptor agonists or antagonists is not well established. JTE-013 and BML-241 (also known as CAY10444, used extensively as specific S1P2 and S1P3 receptors antagonists respectively, are cases in point. When analyzing S1P-induced vasoconstriction in mouse basilar artery, we observed that JTE-013 inhibited not only the effect of S1P, but also the effect of U46619, endothelin-1 or high KCl; JTE-013 strongly inhibited responses to S1P in S1P2 receptor knockout mice. Similarly, BML-241 has been shown to inhibit increases in intracellular Ca2+ concentration via P2 receptor or α1A-adrenoceptor stimulation and α1A-adrenoceptor-mediated contraction of rat mesenteric artery, while it did not affect S1P3-mediated decrease of forskolin-induced cyclic AMP accumulation. Another putative S1P1/3 receptor antagonist, VPC23019, does not inhibit S1P3-mediated vasoconstriction. With these examples in mind, we discuss caveats about relying on available pharmacological tools to characterize receptor subtypes.

  18. Pharmacology and crystal structure of novel 2,3-quinoxalinediones at kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Pallesen, Jakob Staun; Pasini, Diletta

    2017-01-01

    , within the KA receptor family (GluK1-5) only compounds with selectivity towards GluK1 exist [1]. Thus, there is an unmet need for Tool compounds with selectivity towards the remaining KA receptor subunits. Here we report the pharmacology of a series of novel N1-substituted 2,3-quinoxalinediones, as well....... Functional electrophysiological (TEVC) experiments indeed showed these compounds to be antagonists at cloned, homomeric KA receptors. The structure and pharmacology will be valuable for design of new and more GluK3-selective quinoxalinedione analogues....

  19. Alternative Splicing of AMPA subunits in Prefrontal Cortical Fields of Cynomolgus Monkeys following Chronic Ethanol Self-Administration

    Directory of Open Access Journals (Sweden)

    Glen eAcosta

    2012-01-01

    Full Text Available Functional impairment of the orbital and medial prefrontal cortex underlies deficits in executive control that characterize addictive disorders, including alcohol addiction. Previous studies indicate that alcohol alters glutamate neurotransmission and one substrate of these effects may be through the reconfiguration of the subunits constituting ionotropic glutamate receptor (iGluR complexes. Glutamatergic transmission is integral to cortico-cortical and cortico-subcortical communication and alcohol-induced changes in the abundance of the receptor subunits and/or their splice variants may result in critical functional impairments of prefrontal cortex in alcohol dependence. To this end, the effects of chronic ethanol self-administration on glutamate receptor ionotropic AMPA (GRIA subunit variant and kainate (GRIK subunit mRNA expression were studied in the orbitofrontal cortex (OFC, dorsolateral prefrontal cortex (DLPFC and anterior cingulate cortex (ACC of male cynomolgus monkeys. In DLPFC, total AMPA splice variant expression and total kainate receptor subunit expression were significantly decreased in alcohol drinking monkeys. Expression levels of GRIA3 flip and flop and GRIA4 flop mRNAs in this region were positively correlated with daily ethanol intake and blood ethanol concentrations averaged over the six months prior to necropsy. In OFC, AMPA subunit splice variant expression was reduced in the alcohol treated group. GRIA2 flop mRNA levels in this region were positively correlated with daily ethanol intake and blood ethanol concentrations averaged over the six months prior to necropsy. Results from these studies provide further evidence of transcriptional regulation of iGluR subunits in the primate brain following chronic alcohol self-administration. Additional studies examining the cellular localization of such effects in the framework of primate prefrontal cortical circuitry are warranted.

  20. Bidirectional modulation of hippocampal gamma (20-80 Hz) frequency activity in vitro via alpha(α)- and beta(β)-adrenergic receptors (AR).

    Science.gov (United States)

    Haggerty, D C; Glykos, V; Adams, N E; Lebeau, F E N

    2013-12-03

    Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  1. Microglia P2Y13 Receptors Prevent Astrocyte Proliferation Mediated by P2Y1 Receptors

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    Clara Quintas

    2018-05-01

    Full Text Available Cerebral inflammation is a common feature of several neurodegenerative diseases that requires a fine interplay between astrocytes and microglia to acquire appropriate phenotypes for an efficient response to neuronal damage. During brain inflammation, ATP is massively released into the extracellular medium and converted into ADP. Both nucleotides acting on P2 receptors, modulate astrogliosis through mechanisms involving microglia-astrocytes communication. In previous studies, primary cultures of astrocytes and co-cultures of astrocytes and microglia were used to investigate the influence of microglia on astroglial proliferation induced by ADPβS, a stable ADP analog. In astrocyte cultures, ADPβS increased cell proliferation through activation of P2Y1 and P2Y12 receptors, an effect abolished in co-cultures (of astrocytes with ∼12.5% microglia. The possibility that the loss of the ADPβS-mediated effect could have been caused by a microglia-induced degradation of ADPβS or by a preferential microglial localization of P2Y1 or P2Y12 receptors was excluded. Since ADPβS also activates P2Y13 receptors, the contribution of microglial P2Y13 receptors to prevent the proliferative effect of ADPβS in co-cultures was investigated. The results obtained indicate that P2Y13 receptors are low expressed in astrocytes and mainly expressed in microglia. Furthermore, in co-cultures, ADPβS induced astroglial proliferation in the presence of the selective P2Y13 antagonist MRS 2211 (3 μM and of the selective P2Y12 antagonist AR-C66096 (0.1 μM, suggesting that activation of microglial P2Y12 and P2Y13 receptors may induce the release of messengers that inhibit astroglial proliferation mediated by P2Y1,12 receptors. In this microglia-astrocyte paracrine communication, P2Y12 receptors exert opposite effects in astroglial proliferation as a result of its cellular localization: cooperating in astrocytes with P2Y1 receptors to directly stimulate proliferation and in

  2. Actions of Bupivacaine, a Widely Used Local Anesthetic, on NMDA Receptor Responses

    Science.gov (United States)

    Paganelli, Meaghan A.

    2015-01-01

    NMDA receptors mediate excitatory neurotransmission in brain and spinal cord and play a pivotal role in the neurological disease state of chronic pain, which is caused by central sensitization. Bupivacaine is the indicated local anesthetic in caudal, epidural, and spinal anesthesia and is widely used clinically to manage acute and chronic pain. In addition to blocking Na+ channels, bupivacaine affects the activity of many other channels, including NMDA receptors. Importantly, bupivacaine inhibits NMDA receptor-mediated synaptic transmission in the dorsal horn of the spinal cord, an area critically involved in central sensitization. We used recombinant NMDA receptors expressed in HEK293 cells and found that increasing concentrations of bupivacaine decreased channel open probability in GluN2 subunit- and pH-independent manner by increasing the mean duration of closures and decreasing the mean duration of openings. Using kinetic modeling of one-channel currents, we attributed the observed current decrease to two main mechanisms: a voltage-dependent “foot-in-the-door” pore block and an allosteric gating effect. Further, the inhibition was state-independent because it occurred to the same degree whether the drug was applied before or after glutamate stimulation and was mediated by extracellular and intracellular inhibitory sites, via hydrophilic and hydrophobic pathways. These results predict that clinical doses of bupivacaine would decrease the peak and accelerate the decay of synaptic NMDA receptor currents during normal synaptic transmission. These quantitative predictions inform possible applications of bupivacaine as preventative and therapeutic approaches in chronic pain. PMID:25589775

  3. Negative modulation of the GABAA ρ1 receptor function by l-cysteine.

    Science.gov (United States)

    Beltrán González, Andrea N; Vicentini, Florencia; Calvo, Daniel J

    2018-01-01

    l-Cysteine is an endogenous sulfur-containing amino acid with multiple and varied roles in the central nervous system, including neuroprotection and the maintenance of the redox balance. However, it was also suggested as an excitotoxic agent implicated in the pathogenesis of neurological disorders such as Parkinson's and Alzheimer's disease. l-Cysteine can modulate the activity of ionic channels, including voltage-gated calcium channels and glutamatergic NMDA receptors, whereas its effects on GABAergic neurotransmission had not been studied before. In the present work, we analyzed the effects of l-cysteine on responses mediated by homomeric GABA A ρ1 receptors, which are known for mediating tonic γ-aminobutyric acid (GABA) responses in retinal neurons. GABA A ρ1 receptors were expressed in Xenopus laevis oocytes and GABA-evoked chloride currents recorded by two-electrode voltage-clamp in the presence or absence of l-cysteine. l-Cysteine antagonized GABA A ρ1 receptor-mediated responses; inhibition was dose-dependent, reversible, voltage independent, and susceptible to GABA concentration. Concentration-response curves for GABA were shifted to the right in the presence of l-cysteine without a substantial change in the maximal response. l-Cysteine inhibition was insensitive to chemical protection of the sulfhydryl groups of the ρ1 subunits by the irreversible alkylating agent N-ethyl maleimide. Our results suggest that redox modulation is not involved during l-cysteine actions and that l-cysteine might be acting as a competitive antagonist of the GABA A ρ1 receptors. © 2017 International Society for Neurochemistry.

  4. Induction of aryl hydrocarbon receptor-mediated and estrogen receptor-mediated activities, and modulation of cell proliferation by dinaphthofurans

    Czech Academy of Sciences Publication Activity Database

    Vondráček, Jan; Chramostová, Kateřina; Plíšková, M.; Bláha, L.; Brack, W.; Kozubík, Alois; Machala, M.

    2004-01-01

    Roč. 23, č. 9 (2004), s. 2214-2220 ISSN 0730-7268 R&D Projects: GA ČR GA525/03/1527 Institutional research plan: CEZ:AV0Z5004920 Keywords : aryl hydrocarbon receptor-mediated activity * estrogenicity * intercellular communication inhibition Subject RIV: BO - Biophysics Impact factor: 2.121, year: 2004

  5. Crystal structure and pharmacological characterization of a novel N-methyl-D-aspartate (NMDA) receptor antagonist at the GluN1 glycine binding site

    DEFF Research Database (Denmark)

    Kvist, Trine; Steffensen, Thomas Bielefeldt; Greenwood, Jeremy R

    2013-01-01

    NMDA receptors are ligand-gated ion channels that mediate excitatory neurotransmission in the brain. They are tetrameric complexes composed of glycine-binding GluN1 and GluN3 subunits together with glutamate-binding GluN2 subunits. Subunit-selective antagonists that discriminate between the glyci...... screening. Furthermore, the structure reveals that the imino acetamido group of TK40 acts as an α-amino acid bioisostere, which could be of importance in bioisosteric replacement strategies for future ligand design....

  6. Nuclear Receptor Cofactors in PPARγ-Mediated Adipogenesis and Adipocyte Energy Metabolism

    Directory of Open Access Journals (Sweden)

    Emily Powell

    2007-01-01

    Full Text Available Transcriptional cofactors are integral to the proper function and regulation of nuclear receptors. Members of the peroxisome proliferator-activated receptor (PPAR family of nuclear receptors are involved in the regulation of lipid and carbohydrate metabolism. They modulate gene transcription in response to a wide variety of ligands, a process that is mediated by transcriptional coactivators and corepressors. The mechanisms by which these cofactors mediate transcriptional regulation of nuclear receptor function are still being elucidated. The rapidly increasing array of cofactors has brought into focus the need for a clear understanding of how these cofactors interact in ligand- and cell-specific manners. This review highlights the differential effects of the assorted cofactors regulating the transcriptional action of PPARγ and summarizes the recent advances in understanding the physiological functions of corepressors and coactivators.

  7. Cyto- and receptor architecture of area 32 in human and macaque brains.

    Science.gov (United States)

    Palomero-Gallagher, Nicola; Zilles, Karl; Schleicher, Axel; Vogt, Brent A

    2013-10-01

    Human area 32 plays crucial roles in emotion and memory consolidation. It has subgenual (s32), pregenual (p32), dorsal, and midcingulate components. We seek to determine whether macaque area 32 has subgenual and pregenual subdivisions and the extent to which they are comparable to those in humans by means of NeuN immunohistochemistry and multireceptor analysis of laminar profiles. The macaque has areas s32 and p32. In s32, layer IIIa/b neurons are larger than those of layer IIIc. This relationship is reversed in p32. Layer Va is thicker and Vb thinner in s32. Area p32 contains higher kainate, benzodiazepine (BZ), and serotonin (5-HT)1A but lower N-methyl-D-aspartate (NMDA) and α2 receptor densities. Most differences were found in layers I, II, and VI. Together, these differences support the dual nature of macaque area 32. Comparative analysis of human and macaque s32 and p32 supports equivalences in cyto- and receptor architecture. Although there are differences in mean areal receptor densities, there are considerable similarities at the layer level. Laminar receptor distribution patterns in each area are comparable in the two species in layers III-Va for kainate, NMDA, γ-aminobutyric acid (GABA)B , BZ, and 5-HT1A receptors. Multivariate statistical analysis of laminar receptor densities revealed that human s32 is more similar to macaque s32 and p32 than to human p32. Thus, macaque 32 is more complex than hitherto known. Our data suggest a homologous neural architecture in anterior cingulate s32 and p32 in human and macaque brains. © 2013 Wiley Periodicals, Inc.

  8. The TIM and TAM families of phosphatidylserine receptors mediate dengue virus entry.

    Science.gov (United States)

    Meertens, Laurent; Carnec, Xavier; Lecoin, Manuel Perera; Ramdasi, Rasika; Guivel-Benhassine, Florence; Lew, Erin; Lemke, Greg; Schwartz, Olivier; Amara, Ali

    2012-10-18

    Dengue viruses (DVs) are responsible for the most medically relevant arboviral diseases. However, the molecular interactions mediating DV entry are poorly understood. We determined that TIM and TAM proteins, two receptor families that mediate the phosphatidylserine (PtdSer)-dependent phagocytic removal of apoptotic cells, serve as DV entry factors. Cells poorly susceptible to DV are robustly infected after ectopic expression of TIM or TAM receptors. Conversely, DV infection of susceptible cells is inhibited by anti-TIM or anti-TAM antibodies or knockdown of TIM and TAM expression. TIM receptors facilitate DV entry by directly interacting with virion-associated PtdSer. TAM-mediated infection relies on indirect DV recognition, in which the TAM ligand Gas6 acts as a bridging molecule by binding to PtdSer within the virion. This dual mode of virus recognition by TIM and TAM receptors reveals how DVs usurp the apoptotic cell clearance pathway for infectious entry. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. 1H-cyclopentapyrimidine-2,4(1H,3H)-dione-related ionotropic glutamate receptors ligands. Structure-activity relationships and identification of potent and selective iGluR5 modulators

    DEFF Research Database (Denmark)

    Butini, Stefania; Pickering, Darryl S; Morelli, Elena

    2008-01-01

    (S)-CPW399 ((S)-1) is a potent and excitotoxic AMPA receptor partial agonist. Modifying the cyclopentane ring of (S)-1, we developed two of the most potent and selective functional antagonists (5 and 7) for kainate receptor (KA-R) subunit iGluR5. Derivatives 5 and 7, with their unique pharmacolog...

  10. Enhancement of inhibitory neurotransmission and inhibition of excitatory mechanisms underlie the anticonvulsant effects of Mallotus oppositifolius

    Directory of Open Access Journals (Sweden)

    Kennedy Kwami Edem Kukuia

    2016-01-01

    Full Text Available Context: Mallotus oppositifolius is a shrub that is used traditionally to treat epilepsy, but its potential has not been scientifically validated. Aims: This study investigated the anticonvulsant properties and possible mechanism of action of the 70% v/v hydroalcoholic extract of the leaves of M. oppositifolius.Materials and Methods: Inprinting control region (ICR mice (25–30 g were pretreated with the M. oppositifolius leaf extract (10–100 mg/kg before administering the respective convulsants (pentylenetetrazole [PTZ], picrotoxin [PTX], strychnine [STR], 4-aminopyridine [4-AP], and pilocarpine. The effect of the extract in maximal electroshock seizure (MES model was investigated also. Statistical Analysis: Data were presented as mean ± standard error of the mean and were analyzed with one-way analysis of variance (ANOVA or two-way ANOVA where appropriate with Newman–Keuls or Bonferroni post hoc test respectively. P< 0.05 was considered significant. Results: In both PTX and PTZ test, extract delayed the onset of seizures and reduced the frequency and duration of seizures. In the STR-induced seizure test, the extract significantly delayed the onset of seizures and reduced the duration of seizures. The extract also delayed the onset of clonic and tonic seizures as well as increasing the survival of mice in the 4-AP-induced seizure test. It further reduced the duration of tonic limb extensions in the MES test. In the pilocarpine-induced status epilepticus, the extract significantly delayed the onset of clonic convulsions and reduced the frequency and duration of seizures. Moreover, the anticonvulsant effect of the extract was attenuated by flumazenil, a benzodiazepine/gamma-aminobutyric acid (GABA receptor antagonist. Conclusion: These findings show that the extract has anticonvulsant effect possible mediated by GABAergic, glycinergic neurotransmission, and potassium channel conductions. It may also be acting by antagonizing muscarinic

  11. Structure and organization of heteromeric AMPA-type glutamate receptors.

    Science.gov (United States)

    Herguedas, Beatriz; García-Nafría, Javier; Cais, Ondrej; Fernández-Leiro, Rafael; Krieger, James; Ho, Hinze; Greger, Ingo H

    2016-04-29

    AMPA-type glutamate receptors (AMPARs), which are central mediators of rapid neurotransmission and synaptic plasticity, predominantly exist as heteromers of the subunits GluA1 to GluA4. Here we report the first AMPAR heteromer structures, which deviate substantially from existing GluA2 homomer structures. Crystal structures of the GluA2/3 and GluA2/4 N-terminal domains reveal a novel compact conformation with an alternating arrangement of the four subunits around a central axis. This organization is confirmed by cysteine cross-linking in full-length receptors, and it permitted us to determine the structure of an intact GluA2/3 receptor by cryogenic electron microscopy. Two models in the ligand-free state, at resolutions of 8.25 and 10.3 angstroms, exhibit substantial vertical compression and close associations between domain layers, reminiscent of N-methyl-D-aspartate receptors. Model 1 resembles a resting state and model 2 a desensitized state, thus providing snapshots of gating transitions in the nominal absence of ligand. Our data reveal organizational features of heteromeric AMPARs and provide a framework to decipher AMPAR architecture and signaling. Copyright © 2016, American Association for the Advancement of Science.

  12. Hyperexcitability and cell loss in kainate-treated hippocampal slice cultures

    DEFF Research Database (Denmark)

    Benedikz, Eirikur; Casaccia-Bonnefil, P; Stelzer, A

    1993-01-01

    Loss of hippocampal interneurons has been reported in patients with severe temporal lobe epilepsy and in animals treated with kainate. We investigated the relationship between KA induced epileptiform discharge and loss of interneurons in hippocampal slice cultures. Application of KA (1 micro......M) produced reversible epileptiform discharge without neurotoxicity. KA (5 microM), in contrast, produced irreversible epileptiform discharge and neurotoxicity, suggesting that the irreversible epileptiform discharge was required for the neuronal loss. Loss of CA3 pyramidal cells and parvalbumin......-like immunoreactive (PV-I) interneurons preceded loss of somatostatin-like immunoreactive (SS-I) interneurons suggesting a different time course of KA neurotoxicity in these subpopulations of interneurons....

  13. Pharmacological significance of the interplay between angiotensin receptors: MAS receptors as putative final mediators of the effects elicited by angiotensin AT1 receptors antagonists.

    Science.gov (United States)

    Pernomian, Larissa; Pernomian, Laena; Gomes, Mayara S; da Silva, Carlos H T P

    2015-12-15

    The interplay between angiotensin AT1 receptors and MAS receptors relies on several inward regulatory mechanisms from renin-angiotensin system (RAS) including the functional crosstalk between angiotensin II and angiotensin-(1-7), the competitive AT1 antagonism exhibited by angiotensin-(1-7), the antagonist feature assigned to AT1/MAS heterodimerization on AT1 signaling and the AT1-mediated downregulation of angiotensin-converting enzyme 2 (ACE2). Recently, such interplay has acquired an important significance to RAS Pharmacology since a few studies have supporting strong evidences that MAS receptors mediate the effects elicited by AT1 antagonists. The present Perspective provides an overview of the regulatory mechanisms involving AT1 and MAS receptors, their significance to RAS Pharmacology and the future directions on the interplay between angiotensin receptors. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Nootropic agents enhance the recruitment of fast GABAA inhibition in rat neocortex.

    Science.gov (United States)

    Ling, Douglas S F; Benardo, Larry S

    2005-07-01

    It is widely believed that nootropic (cognition-enhancing) agents produce their therapeutic effects by augmenting excitatory synaptic transmission in cortical circuits, primarily through positive modulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors (AMPARs). However, GABA-mediated inhibition is also critical for cognition, and enhanced GABA function may be likewise therapeutic for cognitive disorders. Could nootropics act through such a mechanism as well? To address this question, we examined the effects of nootropic agents on excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) recorded from layer V pyramidal cells in acute slices of somatosensory cortex. Aniracetam, a positive modulator of AMPA/kainate receptors, increased the peak amplitude of evoked EPSCs and the amplitude and duration of polysynaptic fast IPSCs, manifested as a greater total charge carried by IPSCs. As a result, the EPSC/IPSC ratio of total charge was decreased, representing a shift in the excitation-inhibition balance that favors inhibition. Aniracetam did not affect the magnitude of either monosynaptic IPSCs (mono-IPSCs) recorded in the presence of excitatory amino acid receptor antagonists, or miniature IPSCs (mIPSCs) recorded in the presence of tetrodotoxin. However, the duration of both mono-IPSCs and mIPSCs was prolonged, suggesting that aniracetam also directly modulates GABAergic transmission. Cyclothiazide, a preferential modulator of AMPAR function, enhanced the magnitude and duration of polysynaptic IPSCs, similar to aniracetam, but did not affect mono-IPSCs. Concanavalin A, a kainate receptor modulator, had little effect on EPSCs or IPSCs, suggesting there was no contribution from kainate receptor activity. These findings indicate that AMPAR modulators strengthen inhibition in neocortical pyramidal cells, most likely by altering the kinetics of AMPARs on synaptically connected interneurons and possibly by modulating GABA(A) receptor responses

  15. Loss of nitric oxide-mediated inhibition of purine neurotransmitter release in the colon in the absence of interstitial cells of Cajal.

    Science.gov (United States)

    Durnin, Leonie; Lees, Andrea; Manzoor, Sheerien; Sasse, Kent C; Sanders, Kenton M; Mutafova-Yambolieva, Violeta N

    2017-11-01

    Regulation of colonic motility depends on the integrity of enteric inhibitory neurotransmission mediated by nitric oxide (NO), purine neurotransmitters, and neuropeptides. Intramuscular interstitial cells of Cajal (ICC-IM) and platelet-derived growth factor receptor-α-positive (PDGFRα + ) cells are involved in generating responses to NO and purine neurotransmitters, respectively. Previous studies have suggested a decreased nitrergic and increased purinergic neurotransmission in Kit W /Kit W-v ( W/W v ) mice that display lesions in ICC-IM along the gastrointestinal tract. However, contributions of NO to these phenotypes have not been evaluated. We used small-chamber superfusion assays and HPLC to measure the spontaneous and electrical field stimulation (EFS)-evoked release of nicotinamide adenine dinucleotide (NAD + )/ADP-ribose, uridine adenosine tetraphosphate (Up4A), adenosine 5'-triphosphate (ATP), and metabolites from the tunica muscularis of human, monkey, and murine colons and circular muscle of monkey colon, and we tested drugs that modulate NO levels or blocked NO receptors. NO inhibited EFS-evoked release of purines in the colon via presynaptic neuromodulation. Colons from W/W v , Nos1 -/- , and Prkg1 -/- mice displayed augmented neural release of purines that was likely due to altered nitrergic neuromodulation. Colons from W/W v mice demonstrated decreased nitrergic and increased purinergic relaxations in response to nerve stimulation. W/W v mouse colons demonstrated reduced Nos1 expression and reduced NO release. Our results suggest that enhanced purinergic neurotransmission may compensate for the loss of nitrergic neurotransmission in muscles with partial loss of ICC. The interactions between nitrergic and purinergic neurotransmission in the colon provide novel insight into the role of neurotransmitters and effector cells in the neural regulation of gastrointestinal motility. NEW & NOTEWORTHY This is the first study investigating the role of nitric

  16. Serotonin and brain function: a tale of two receptors.

    Science.gov (United States)

    Carhart-Harris, R L; Nutt, D J

    2017-09-01

    Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain's default response to adversity but that an improved ability to change one's situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important - and increasingly so as the level of adversity reaches a critical point. We propose that the 5-HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.

  17. Kainate toxicity in energy-compromised rat hippocampal slices: differences between oxygen and glucose deprivation.

    Science.gov (United States)

    Schurr, A; Rigor, B M

    1993-06-18

    The effects of kainate (KA) on the recovery of neuronal function in rat hippocampal slices after hypoxia or glucose deprivation (GD) were investigated and compared to those of (R,S)-alpha-amino-3-hydroxy-5-methyl-4- isoxazoleproprionate (AMPA). KA and AMPA were found to be more toxic than either N-methyl-D-aspartate (NMDA), quinolinate, or glutamate, both under normal conditions and under states of energy deprivation. Doses as low as 1 microM KA or AMPA were sufficient to significantly reduce the recovery rate of neuronal function in slices after a standardized period of hypoxia or GD. The enhancement of hypoxic neuronal damage by both agonists could be partially blocked by the antagonist kynurenate, by the NMDA competitive antagonist AP5, and by elevating [Mg2+] in or by omitting Ca2+ from the perfusion medium. The AMPA antagonist glutamic acid diethyl ester was ineffective in preventing the enhanced hypoxic neuronal damage by either KA or AMPA. The antagonist of the glycine modulatory site on the NMDA receptor, 7-chlorokynurenate, did not block the KA toxicity but was able to block the toxicity of AMPA. 2,3-Dihydroxyquinoxaline completely blocked the KA- and AMPA-enhanced hypoxic neuronal damage. The KA-enhanced, GD-induced neuronal damage was prevented by Ca2+ depletion and partially antagonized by kynurenate but not by AP5 or elevated [Mg2+]. The results of the present study indicate that the KA receptor is involved in the mechanism of neuronal damage induced by hypoxia and GD, probably allowing Ca2+ influx and subsequent intracellular Ca2+ overload.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Secretory phospholipase A2-mediated neuronal cell death involves glutamate ionotropic receptors

    DEFF Research Database (Denmark)

    Kolko, Miriam; de Turco, Elena B; Diemer, Nils Henrik

    2002-01-01

    To define the significance of glutamate ionotropic receptors in sPLA -mediated neuronal cell death we used the NMDA receptor antagonist MK-801 and the AMPA receptor antagonist PNQX. In primary neuronal cell cultures both MK-801 and PNQX inhibited sPLA - and glutamate-induced neuronal death. [ H...

  19. Azadirachtin interacts with retinoic acid receptors and inhibits retinoic acid-mediated biological responses.

    Science.gov (United States)

    Thoh, Maikho; Babajan, Banaganapalli; Raghavendra, Pongali B; Sureshkumar, Chitta; Manna, Sunil K

    2011-02-11

    Considering the role of retinoids in regulation of more than 500 genes involved in cell cycle and growth arrest, a detailed understanding of the mechanism and its regulation is useful for therapy. The extract of the medicinal plant Neem (Azadirachta indica) is used against several ailments especially for anti-inflammatory, anti-itching, spermicidal, anticancer, and insecticidal activities. In this report we prove the detailed mechanism on the regulation of retinoic acid-mediated cell signaling by azadirachtin, active components of neem extract. Azadirachtin repressed all trans-retinoic acid (ATRA)-mediated nuclear transcription factor κB (NF-κB) activation, not the DNA binding but the NF-κB-dependent gene expression. It did not inhibit IκBα degradation, IκBα kinase activity, or p65 phosphorylation and its nuclear translocation but inhibited NF-κB-dependent reporter gene expression. Azadirachtin inhibited TRAF6-mediated, but not TRAF2-mediated NF-κB activation. It inhibited ATRA-induced Sp1 and CREB (cAMP-response element-binding protein) DNA binding. Azadirachtin inhibited ATRA binding with retinoid receptors, which is supported by biochemical and in silico evidences. Azadirachtin showed strong interaction with retinoid receptors. It suppressed ATRA-mediated removal of retinoid receptors, bound with DNA by inhibiting ATRA binding to its receptors. Overall, our data suggest that azadirachtin interacts with retinoic acid receptors and suppresses ATRA binding, inhibits falling off the receptors, and activates transcription factors like CREB, Sp1, NF-κB, etc. Thus, azadirachtin exerts anti-inflammatory and anti-metastatic responses by a novel pathway that would be beneficial for further anti-inflammatory and anti-cancer therapies.

  20. Azadirachtin Interacts with Retinoic Acid Receptors and Inhibits Retinoic Acid-mediated Biological Responses*

    Science.gov (United States)

    Thoh, Maikho; Babajan, Banaganapalli; Raghavendra, Pongali B.; Sureshkumar, Chitta; Manna, Sunil K.

    2011-01-01

    Considering the role of retinoids in regulation of more than 500 genes involved in cell cycle and growth arrest, a detailed understanding of the mechanism and its regulation is useful for therapy. The extract of the medicinal plant Neem (Azadirachta indica) is used against several ailments especially for anti-inflammatory, anti-itching, spermicidal, anticancer, and insecticidal activities. In this report we prove the detailed mechanism on the regulation of retinoic acid-mediated cell signaling by azadirachtin, active components of neem extract. Azadirachtin repressed all trans-retinoic acid (ATRA)-mediated nuclear transcription factor κB (NF-κB) activation, not the DNA binding but the NF-κB-dependent gene expression. It did not inhibit IκBα degradation, IκBα kinase activity, or p65 phosphorylation and its nuclear translocation but inhibited NF-κB-dependent reporter gene expression. Azadirachtin inhibited TRAF6-mediated, but not TRAF2-mediated NF-κB activation. It inhibited ATRA-induced Sp1 and CREB (cAMP-response element-binding protein) DNA binding. Azadirachtin inhibited ATRA binding with retinoid receptors, which is supported by biochemical and in silico evidences. Azadirachtin showed strong interaction with retinoid receptors. It suppressed ATRA-mediated removal of retinoid receptors, bound with DNA by inhibiting ATRA binding to its receptors. Overall, our data suggest that azadirachtin interacts with retinoic acid receptors and suppresses ATRA binding, inhibits falling off the receptors, and activates transcription factors like CREB, Sp1, NF-κB, etc. Thus, azadirachtin exerts anti-inflammatory and anti-metastatic responses by a novel pathway that would be beneficial for further anti-inflammatory and anti-cancer therapies. PMID:21127062

  1. Relations between immune and mediator receptors of mouse lymphocytes

    International Nuclear Information System (INIS)

    Ado, A.D.; Alekseeva, T.A.; Kravchenko, S.A.

    1985-01-01

    This paper examines the action of the specific muscarinic antogonist tritium-quinuclidinyl benzilate (tritium-QNB) on immune rosette formation in mice. It is shown that since the specific muscarini antagonist tritium-QNB inhibits immune rosette formation, this process must be regarded as interconnected with muscarinic receptors of lymphocytes. Interaction of immune (antigen-binding) and mediator receptors, however, is an important factor maintaining immune homeostasis at a certain level

  2. Regionally Selective Requirement for D[subscript 1]/D[subscript 5] Dopaminergic Neurotransmission in the Medial Prefrontal Cortex in Object-in-Place Associative Recognition Memory

    Science.gov (United States)

    Savalli, Giorgia; Bashir, Zafar I.; Warburton, E. Clea

    2015-01-01

    Object-in-place (OiP) memory is critical for remembering the location in which an object was last encountered and depends conjointly on the medial prefrontal cortex, perirhinal cortex, and hippocampus. Here we examined the role of dopamine D[subscript 1]/D[subscript 5] receptor neurotransmission within these brain regions for OiP memory. Bilateral…

  3. Upregulation of Cannabinoid Type 1 Receptors in Dopamine D2 Receptor Knockout Mice Is Reversed by Chronic Forced Ethanol Consumption

    Energy Technology Data Exchange (ETDEWEB)

    Thanos, P.K.; Wang, G.; Thanos, P.K.; Gopez, V.; Delis, F.; Michaelides, M.; Grand, D.K.; Wang, G.-J.; Kunos, G.; Volkow, N.D.

    2011-01-01

    The anatomical proximity of the cannabinoid type 1 (CNR1/CB1R) and the dopamine D2 receptors (DRD2), their ability to form CB1R-DRD2 heteromers, their opposing roles in locomotion, and their involvement in ethanol's reinforcing and addictive properties prompted us to study the levels and distribution of CB1R after chronic ethanol intake, in the presence and absence of DRD2. We monitored the drinking patterns and locomotor activity of Drd2+/+ and Drd2-/- mice consuming either water or a 20% (v/v) ethanol solution (forced ethanol intake) for 6 months and used the selective CB1 receptor antagonist [{sup 3}H]SR141716A to quantify CB1R levels in different brain regions with in vitro receptor autoradiography. We found that the lack of DRD2 leads to a marked upregulation (approximately 2-fold increase) of CB1R in the cerebral cortex, the caudate-putamen, and the nucleus accumbens, which was reversed by chronic ethanol intake. The results suggest that DRD2-mediated dopaminergic neurotransmission and chronic ethanol intake exert an inhibitory effect on cannabinoid receptor expression in cortical and striatal regions implicated in the reinforcing and addictive properties of ethanol.

  4. Development of calcium-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in cultured neocortical neurons visualized by cobalt staining

    DEFF Research Database (Denmark)

    Jensen, J B; Schousboe, A; Pickering, D S

    1998-01-01

    The developmental expression of calcium (Ca2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate receptors in cultured neocortical neurons was evaluated by using cobalt uptake, a histochemical method that identifies cells expressing Ca2+-permeable, non-N-methyl-D-aspartate...

  5. Central 5-HT Neurotransmission Modulates Weight Loss following Gastric Bypass Surgery in Obese Individuals

    DEFF Research Database (Denmark)

    Haahr, M. E.; Hansen, D. L.; Fisher, P. M.

    2015-01-01

    The cerebral serotonin (5-HT) system shows distinct differences in obesity compared with the lean state. Here, it was investigated whether serotonergic neurotransmission in obesity is a stable trait or changes in association with weight loss induced by Roux-in-Y gastric bypass (RYGB) surgery....... In vivo cerebral 5-HT2A receptor and 5-HT transporter binding was determined by positron emission tomography in 21 obese [four men; body mass index (BMI), 40.1 ± 4.1 kg/m(2)] and 10 lean (three men; BMI, 24.6 ± 1.5 kg/m(2)) individuals. Fourteen obese individuals were re-examined after RYGB surgery. First...

  6. Complement-mediated solubilization of immune complexes and their interaction with complement C3 receptors

    DEFF Research Database (Denmark)

    Petersen, Ivan; Baatrup, Gunnar; Jepsen, H H

    1985-01-01

    Some of the molecular events in the complement (C)-mediated solubilization of immune complexes (IC) have been clarified in recent years. The solubilization is primarily mediated by alternative C pathway proteins whereas factors in the classical pathway accelerate the process. Components of the me......Some of the molecular events in the complement (C)-mediated solubilization of immune complexes (IC) have been clarified in recent years. The solubilization is primarily mediated by alternative C pathway proteins whereas factors in the classical pathway accelerate the process. Components...... of the cellular localization, expression and structure of the C3 receptors, especially the C3b (CR1) receptor, has been considerably extended in the last few years, whereas our understanding of the physiological role of these receptors is still fragmentary. However, it is becoming increasingly evident...

  7. Biological functionalization of drug delivery carriers to bypass size restrictions of receptor-mediated endocytosis independently from receptor targeting.

    Science.gov (United States)

    Ansar, Maria; Serrano, Daniel; Papademetriou, Iason; Bhowmick, Tridib Kumar; Muro, Silvia

    2013-12-23

    Targeting of drug carriers to cell-surface receptors involved in endocytosis is commonly used for intracellular drug delivery. However, most endocytic receptors mediate uptake via clathrin or caveolar pathways associated with ≤200-nm vesicles, restricting carrier design. We recently showed that endocytosis mediated by intercellular adhesion molecule 1 (ICAM-1), which differs from clathrin- and caveolae-mediated pathways, allows uptake of nano- and microcarriers in cell culture and in vivo due to recruitment of cellular sphingomyelinases to the plasmalemma. This leads to ceramide generation at carrier binding sites and formation of actin stress-fibers, enabling engulfment and uptake of a wide size-range of carriers. Here we adapted this paradigm to enhance uptake of drug carriers targeted to receptors associated with size-restricted pathways. We coated sphingomyelinase onto model (polystyrene) submicro- and microcarriers targeted to clathrin-associated mannose-6-phosphate receptor. In endothelial cells, this provided ceramide enrichment at the cell surface and actin stress-fiber formation, modifying the uptake pathway and enhancing carrier endocytosis without affecting targeting, endosomal transport, cell-associated degradation, or cell viability. This improvement depended on the carrier size and enzyme dose, and similar results were observed for other receptors (transferrin receptor) and cell types (epithelial cells). This phenomenon also enhanced tissue accumulation of carriers after intravenous injection in mice. Hence, it is possible to maintain targeting toward a selected receptor while bypassing natural size restrictions of its associated endocytic route by functionalization of drug carriers with biological elements mimicking the ICAM-1 pathway. This strategy holds considerable promise to enhance flexibility of design of targeted drug delivery systems.

  8. Generation of functional inhibitory synapses incorporating defined combinations of GABA(A or glycine receptor subunits

    Directory of Open Access Journals (Sweden)

    Christine Laura Dixon

    2015-12-01

    Full Text Available Fast inhibitory neurotransmission in the brain is mediated by wide range of GABAA receptor (GABAAR and glycine receptor (GlyR isoforms, each with different physiological and pharmacological properties. Because multiple isoforms are expressed simultaneously in most neurons, it is difficult to define the properties of inhibitory postsynaptic currents mediated by individual isoforms in vivo. Although recombinant expression systems permit the expression of individual isoforms in isolation, they require exogenous agonist application which cannot mimic the dynamic neurotransmitter profile characteristic of native synapses. We describe a neuron-HEK293 cell co-culture technique for generating inhibitory synapses incorporating defined combinations of GABAAR or GlyR subunits. Primary neuronal cultures, prepared from embryonic rat cerebral cortex or spinal cord, are used to provide presynaptic GABAergic and glycinergic terminals, respectively. When the cultures are mature, HEK293 cells expressing the subunits of interest plus neuroligin 2A are plated onto the neurons, which rapidly form synapses onto HEK293 cells. Patch clamp electrophysiology is then used to analyze the physiological and pharmacological properties of the inhibitory postsynaptic currents mediated by the recombinant receptors. The method is suitable for investigating the kinetic properties or the effects of drugs on inhibitory postsynaptic currents mediated by defined GABAAR or GlyR isoforms of interest, the effects of hereditary disease mutations on the formation and function of both types of synapses, and synaptogenesis and synaptic clustering mechanisms. The entire cell preparation procedure takes 2 – 5 weeks.

  9. P2X receptors in the cardiovascular system and their potential as therapeutic targets in disease.

    Science.gov (United States)

    Ralevic, Vera

    2015-01-01

    This review considers the expression and roles of P2X receptors in the cardiovascular system in health and disease and their potential as therapeutic targets. P2X receptors are ligand gated ion channels which are activated by the endogenous ligand ATP. They are formed from the assembly of three P2X subunit proteins from the complement of seven (P2X1-7), which can associate to form homomeric or heteromeric P2X receptors. The P2X1 receptor is widely expressed in the cardiovascular system, being located in the heart, in the smooth muscle of the majority of blood vessels and in platelets. P2X1 receptors expressed in blood vessels can be activated by ATP coreleased with noradrenaline as a sympathetic neurotransmitter, leading to smooth muscle depolarisation and contraction. There is evidence that the purinergic component of sympathetic neurotransmission is increased in hypertension, identifying P2X1 receptors as a possible therapeutic target in this disorder. P2X3 and P2X2/3 receptors are expressed on cardiac sympathetic neurones and may, through positive feedback of neuronal ATP at this prejunctional site, amplify sympathetic neurotransmission. Activation of P2X receptors expressed in the heart increases cardiac myocyte contractility, and an important role of the P2X4 receptor in this has been identified. Deletion of P2X4 receptors in the heart depresses contractile performance in models of heart failure, while overexpression of P2X4 receptors has been shown to be cardioprotective, thus P2X4 receptors may be therapeutic targets in the treatment of heart disease. P2X receptors have been identified on endothelial cells. Although immunoreactivity for all P2X1-7 receptor proteins has been shown on the endothelium, relatively little is known about their function, with the exception of the endothelial P2X4 receptor, which has been shown to mediate endothelium-dependent vasodilatation to ATP released during shear stress. The potential of P2X receptors as therapeutic targets

  10. The Role of Cgrp-Receptor Component Protein (Rcp in Cgrp-Mediated Signal Transduction

    Directory of Open Access Journals (Sweden)

    M. A. Prado

    2001-01-01

    Full Text Available The calcitonin gene-related peptide (CGRP-receptor component protein (RCP is a 17-kDa intracellular peripheral membrane protein required for signal transduction at CGRP receptors. To determine the role of RCP in CGRP-mediated signal transduction, RCP was depleted from NIH3T3 cells using antisense strategy. Loss of RCP protein correlated with loss of cAMP production by CGRP in the antisense cells. In contrast, loss of RCP had no effect on CGRP-mediated binding; therefore RCP is not acting as a chaperone for the CGRP receptor. Instead, RCP is a novel signal transduction molecule that couples the CGRP receptor to the cellular signal transduction machinery. RCP thus represents a prototype for a new class of signal transduction proteins that are required for regulation of G protein-coupled receptors.

  11. Cross-talk between an activator of nuclear receptors-mediated transcription and the D1 dopamine receptor signaling pathway.

    Science.gov (United States)

    Schmidt, Azriel; Vogel, Robert; Rutledge, Su Jane; Opas, Evan E; Rodan, Gideon A; Friedman, Eitan

    2005-03-01

    Nuclear receptors are transcription factors that usually interact, in a ligand-dependent manner, with specific DNA sequences located within promoters of target genes. The nuclear receptors can also be controlled in a ligand-independent manner via the action of membrane receptors and cellular signaling pathways. 5-Tetradecyloxy-2-furancarboxylic acid (TOFA) was shown to stimulate transcription from the MMTV promoter via chimeric receptors that consist of the DNA binding domain of GR and the ligand binding regions of the PPARbeta or LXRbeta nuclear receptors (GR/PPARbeta and GR/LXRbeta). TOFA and hydroxycholesterols also modulate transcription from NF-kappaB- and AP-1-controlled reporter genes and induce neurite differentiation in PC12 cells. In CV-1 cells that express D(1) dopamine receptors, D(1) dopamine receptor stimulation was found to inhibit TOFA-stimulated transcription from the MMTV promoter that is under the control of chimeric GR/PPARbeta and GR/LXRbeta receptors. Treatment with the D(1) dopamine receptor antagonist, SCH23390, prevented dopamine-mediated suppression of transcription, and by itself increased transcription controlled by GR/LXRbeta. Furthermore, combined treatment of CV-1 cells with TOFA and SCH23390 increased transcription controlled by the GR/LXRbeta chimeric receptor synergistically. The significance of this in vitro synergy was demonstrated in vivo, by the observation that SCH23390 (but not haloperidol)-mediated catalepsy in rats was potentiated by TOFA, thus showing that an agent that mimics the in vitro activities of compounds that activate members of the LXR and PPAR receptor families can influence D1 dopamine receptor elicited responses.

  12. Co-induction of p75(NTR) and the associated death executor NADE in degenerating hippocampal neurons after kainate-induced seizures in the rat.

    Science.gov (United States)

    Yi, Jung-Sun; Lee, Soon-Keum; Sato, Taka-Aki; Koh, Jae-Young

    2003-08-21

    Zinc induces in cultured cortical neurons both p75(NTR) and p75(NTR)-associated death executor (NADE), which together contribute to caspase-dependent neuronal apoptosis. Since zinc neurotoxicity may contribute to neuronal death following seizures, we examined whether p75(NTR) and NADE are co-induced also in rat hippocampal neurons degenerating after seizures. Staining of brain sections with a zinc-specific fluorescent dye (N-(6-methoxy-8-quinolyl)-p-carboxybenzoylsulphonamide) and acid fuchsin revealed zinc accumulation in degenerating neuronal cell bodies in CA1 and CA3 of hippocampus 24 h after kainate injection. Both anti-p75(NTR) and anti-NADE immunoreactivities appeared in zinc-accumulating/degenerating neurons in both areas. Intraventricular injection of CaEDTA, without altering the severity or time course of kainate-induced seizures, markedly attenuated the induction of p75(NTR)/NADE in hippocampus, which correlated with the decrease of caspase-3 activation and zinc accumulation/cell death. The present study has demonstrated that p75(NTR) and NADE are co-induced in neurons degenerating after kainate-induced seizures in rats, likely in a zinc-dependent manner.

  13. Differential regulation of synaptic and extrasynaptic α4 GABA(A) receptor populations by protein kinase A and protein kinase C in cultured cortical neurons.

    Science.gov (United States)

    Bohnsack, John Peyton; Carlson, Stephen L; Morrow, A Leslie

    2016-06-01

    The GABAA α4 subunit exists in two distinct populations of GABAA receptors. Synaptic GABAA α4 receptors are localized at the synapse and mediate phasic inhibitory neurotransmission, while extrasynaptic GABAA receptors are located outside of the synapse and mediate tonic inhibitory transmission. These receptors have distinct pharmacological and biophysical properties that contribute to interest in how these different subtypes are regulated under physiological and pathological states. We utilized subcellular fractionation procedures to separate these populations of receptors in order to investigate their regulation by protein kinases in cortical cultured neurons. Protein kinase A (PKA) activation decreases synaptic α4 expression while protein kinase C (PKC) activation increases α4 subunit expression, and these effects are associated with increased β3 S408/409 or γ2 S327 phosphorylation respectively. In contrast, PKA activation increases extrasynaptic α4 and δ subunit expression, while PKC activation has no effect. Our findings suggest synaptic and extrasynaptic GABAA α4 subunit expression can be modulated by PKA to inform the development of more specific therapeutics for neurological diseases that involve deficits in GABAergic transmission. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. G-protein mediates voltage regulation of agonist binding to muscarinic receptors: effects on receptor-Na+ channel interaction

    International Nuclear Information System (INIS)

    Cohen-Armon, M.; Garty, H.; Sokolovsky, M.

    1988-01-01

    The authors previous experiments in membranes prepared from rat heart and brain led them to suggest that the binding of agonist to the muscarinic receptors and to the Na + channels is a coupled event mediated by guanine nucleotide binding protein(s) [G-protein(s)]. These in vitro findings prompted us to employ synaptoneurosomes from brain stem tissue to examine (i) the binding properties of [ 3 H] acetylcholine at resting potential and under depolarization conditions in the absence and presence of pertussis toxin; (ii) the binding of [ 3 H]batrachotoxin to Na + channel(s) in the presence of the muscarinic agonists; and (iii) muscarinically induced 22 Na + uptake in the presence and absence of tetrodotoxin, which blocks Na + channels. The findings indicate that agonist binding to muscarinic receptors is voltage dependent, that this process is mediated by G-protein(s), and that muscarinic agonists induce opening of Na + channels. The latter process persists even after pertussis toxin treatment, indicating that it is not likely to be mediated by pertussis toxin sensitive G-protein(s). The system with its three interacting components-receptor, G-protein, and Na + channel-is such that at resting potential the muscarinic receptor induces opening of Na + channels; this property may provide a possible physiological mechanism for the depolarization stimulus necessary for autoexcitation or repetitive firing in heart or brain tissues

  15. Properties of GluR3 receptors tagged with GFP at the amino or carboxyl terminus.

    Science.gov (United States)

    Limon, Agenor; Reyes-Ruiz, Jorge Mauricio; Eusebi, Fabrizio; Miledi, Ricardo

    2007-09-25

    Anatomical visualization of neurotransmitter receptor localization is facilitated by tagging receptors, but this process can alter their functional properties. We have evaluated the distribution and properties of WT glutamate receptor 3 (GluR3) alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (WT GluR3) and two receptors in which GFP was tagged to the amino terminus (GFP-GluR3) or to the carboxyl terminus (GluR3-GFP). Although the fluorescence in Xenopus oocytes was stronger in the vegetal hemisphere because of localization of internal structures (probable sites of production, storage or recycling of receptors), the insertion of receptors into the plasma membrane was polarized to the animal hemisphere. The fluorescence intensity of oocytes injected with GluR3-GFP RNA was approximately double that of oocytes injected with GFP-GluR3 RNA. Accordingly, GluR3-GFP oocytes generated larger kainate-induced currents than GFP-GluR3 oocytes, with similar EC(50) values. Currents elicited by glutamate, or AMPA coapplied with cyclothiazide, were also larger in GluR3-GFP oocytes. The glutamate- to kainate-current amplitude ratios differed, with GluR3-GFP being activated more efficiently by glutamate than the WT or GFP-GluR3 receptors. This pattern correlates with the slower decay of glutamate-induced currents generated by GluR3-GFP receptors. These changes were not observed when GFP was tagged to the amino terminus, and these receptors behaved like the WT. The antagonistic effects of 6-nitro-7-sulfamoylbenzo[f]quinoxaline-2,3-dione (NBQX) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) were not altered in any of the tagged receptors. We conclude that GFP is a useful and convenient tag for visualizing these proteins. However, the effects of different sites of tag insertion on receptor characteristics must be taken into account in assessing the roles played by these receptor proteins.

  16. Structure and affinity of two bicyclic glutamate analogues at AMPA and kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Pinto, Andrea; Marconi, Laura

    2017-01-01

    Ionotropic glutamate receptors (iGluRs) are involved in most of the fast excitatory synaptic transmission in the central nervous system. These receptors are important for learning and memory formation, but are also involved in the development of diseases such as Alzheimer’s disease, epilepsy...

  17. GABA type a receptor trafficking and the architecture of synaptic inhibition.

    Science.gov (United States)

    Lorenz-Guertin, Joshua M; Jacob, Tija C

    2018-03-01

    Ubiquitous expression of GABA type A receptors (GABA A R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABA A Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABA A R function. Here we review the current understanding of how GABA A Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABA A R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABA A R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018. © 2017 Wiley Periodicals, Inc.

  18. Glutamatergic induction of CREB phosphorylation and Fos expression in primary cultures of the suprachiasmatic hypothalamus in vitro is mediated by co-ordinate activity of NMDA and non-NMDA receptors.

    Science.gov (United States)

    Schurov, I L; McNulty, S; Best, J D; Sloper, P J; Hastings, M H

    1999-01-01

    Exposure of Syrian hamsters to light 1 h after lights-off rapidly (10 min) induced nuclear immunoreactivity (-ir) to the phospho-Ser133 form of the Ca2+/cAMP response element (CRE) binding protein (pCREB) in the retinorecipient zone of the suprachiasmatic nuclei (SCN). Light also induced nuclear Fos-ir in the same region of the SCN after 1 h. The glutamatergic N-methyl-D-aspartate (NMDA) receptor blocker MK801 attenuated the photic induction of both factors. To investigate glutamatergic regulation of pCREB and Fos further, tissue blocks and primary cultures of neonatal hamster SCN were examined by Western blotting and immunocytochemistry in vitro. On Western blots of SCN tissue, the pCREB-ir signal at 45 kDa was enhanced by glutamate or a mixture of glutamatergic agonists (NMDA, amino-methyl proprionic acid (AMPA), and Kainate (KA)), whereas total CREB did not change. Glutamate or the mixture of agonists also induced a 56 kDa band identified as Fos protein in SCN tissue. In dissociated cultures of SCN, glutamate caused a rapid (15 min) induction of nuclear pCREB-ir and Fos-ir (after 60 min) exclusively in neurones, both GABA-ir and others. Treatment with NMDA alone had no effect on pCREB-ir. AMPA alone caused a slight increase in pCREB-ir. However, kainate alone or in combination with NMDA and AMPA induced nuclear pCREB-ir equal to that induced by glutamate. The effects of glutamate on pCREB-ir and Fos-ir were blocked by antagonists of both NMDA (MK801) and AMPA/KA (NBQX) receptors. In the absence of extracellular Mg2+, MK801 blocked glutamatergic induction of Fos-ir. However, the AMPA/KA receptor antagonist was no longer effective at blocking glutamatergic induction of either Fos-ir or pCREB-ir, consistent with the model that glutamate regulates gene expression in the SCN by a co-ordinate action through both NMDA and AMPA/KA receptors. Glutamatergic induction of nuclear pCREB-ir in GABA-ir neurones was blocked by KN-62 an inhibitor of Ca2+/Calmodulin (Ca

  19. The serotonin receptor mediates changes in autonomic neurotransmission and gastrointestinal transit induced by heat-killed Lactobacillus brevis SBC8803.

    Science.gov (United States)

    Horii, Y; Nakakita, Y; Misonou, Y; Nakamura, T; Nagai, K

    2015-01-01

    Lactobacilli exhibit several health benefits in mammals, including humans. Our previous reports established that heat-killed Lactobacillus brevis SBC8803 (SBC8803) increased both efferent gastric vagal nerve activity and afferent intestinal vagal nerve activity in rats. We speculated that this strain could be useful for the treatment of gastrointestinal (GI) disorders. In this study, we examined the effects of SBC8803 on peristalsis and the activity of the efferent celiac vagal nerve innervating the intestine in rats. First, we examined the effects of intraduodenal (ID) administration of SBC8803 on efferent celiac vagal nerve activity (efferent CVNA) in urethane-anesthetised rats using electrophysiological studies. The effects of intravenous injection of the serotonin 5-HT3 receptor antagonist granisetron on changes in efferent CVNA due to ID administration of SBC8803 were also investigated. Finally, the effects of oral gavage of SBC8803 on GI transit were analysed using the charcoal propulsion method in conscious rats treated with or without granisetron. ID administration of SBC8803 increased efferent CVNA. Pretreatment with granisetron eliminated SBC8803-dependent changes in efferent CVNA. Furthermore, oral gavage of SBC8803 significantly accelerated GI transit, while pretreatment with granisetron inhibited GI transit. Our findings suggested that SBC8803 increased efferent CVNA and GI transit of charcoal meal via 5-HT3 receptors. Moreover, SBC8803 enhanced the activity of efferent vagal nerve innervating the intestine and promoted peristalsis via 5-HT3 receptors.

  20. ZINC-INDUCED EGF RECEPTOR SIGNALING REQUIRES SRC-MEDIATED PHOSPHORYLATION OF THE EGF RECEPTOR ON TYROSINE 845 (Y845)

    Science.gov (United States)

    ZINC-INDUCED EGF RECEPTOR SIGNALING REQUIRES Src-MEDIATED PHOSPHORYLATION OF THE EGF RECEPTOR ON TYROSINE 845 (Y845)Weidong Wu1, Lee M. Graves2, Gordon N. Gill3 and James M. Samet4 1Center for Environmental Medicine and Lung Biology; 2Department of Pharmacology, University o...

  1. In vitro binding and receptor-mediated activity of terlipressin at vasopressin receptors V1 and V2.

    Science.gov (United States)

    Jamil, Khurram; Pappas, Stephen Chris; Devarakonda, Krishna R

    2018-01-01

    Terlipressin, a synthetic, systemic vasoconstrictor with selective activity at vasopressin-1 (V 1 ) receptors, is a pro-drug for the endogenous/natural porcine hormone [Lys 8 ]-vasopressin (LVP). We investigated binding and receptor-mediated cellular activities of terlipressin, LVP, and endogenous human hormone [Arg 8 ]-vasopressin (AVP) at V 1 and vasopressin-2 (V 2 ) receptors. Cell membrane homogenates of Chinese hamster ovary cells expressing human V 1 and V 2 receptors were used in competitive binding assays to measure receptor-binding activity. These cells were used in functional assays to measure receptor-mediated cellular activity of terlipressin, LVP, and AVP. Binding was measured by [ 3 H]AVP counts, and the activity was measured by fluorometric detection of intracellular calcium mobilization (V 1 ) and cyclic adenosine monophosphate (V 2 ). Binding potency at V 1 and V 2 was AVP>LVP>terlipressin. LVP and terlipressin had approximately sixfold higher affinity for V 1 than for V 2 . Cellular activity potency was also AVP>LVP>terlipressin. Terlipressin was a partial agonist at V 1 and a full agonist at V 2 ; LVP was a full agonist at both V 1 and V 2 . The in vivo response to terlipressin is likely due to the partial V 1 agonist activity of terlipressin and full V 1 agonist activity of its metabolite, LVP. These results provide supportive evidence for previous findings and further establish terlipressin pharmacology for vasopressin receptors.

  2. Intrinsic neuromodulation in the Tritonia swim CPG: serotonin mediates both neuromodulation and neurotransmission by the dorsal swim interneurons.

    Science.gov (United States)

    Katz, P S; Frost, W N

    1995-12-01

    1. Neuromodulation has previously been shown to be intrinsic to the central pattern generator (CPG) circuit that generates the escape swim of the nudibranch mollusk Tritonia diomedea; the dorsal swim interneurons (DSIs) make conventional monosynaptic connections and evoke neuromodulatory effects within the swim motor circuit. The conventional synaptic potentials evoked by a DSI onto cerebral neuron 2 (C2) and onto the dorsal flexion neurons (DFNs) consist of a fast excitatory postsynaptic potential (EPSP) followed by a prolonged slow EPSP. In their neuromodulatory role, the DSIs produce an enhancement of the monosynaptic connections made by C2 onto other CPG circuit interneurons and onto efferent flexion neurons. Previous work showed that the DSIs are immunoreactive for serotonin. Here we provide evidence that both the neurotransmission and the neuromodulation evoked by the DSIs are produced by serotonin, and that these effects may be pharmacologically separable. 2. Previously it was shown that bath-applied serotonin both mimics and occludes the modulation of the C2 synapses by the DSIs. Here we find that pressure-applied puffs of serotonin mimic both the fast and slow EPSPs evoked by a DSI onto a DFN, whereas high concentrations of bath-applied serotonin occlude both of these synaptic components. 3. Consistent with the hypothesis that serotonin mediates the actions of the DSIs, the serotonin reuptake inhibitor imipramine prolongs the duration of the fast DSI-DFN EPSP, increases the amplitude of the slow DSI-DFN EPSP, and increases both the amplitude and duration of the modulation of the C2-DFN synapse by the DSIs. 4. Two serotonergic antagonists were found that block the actions of the DSIs. Gramine blocks the fast DSI-DFN EPSP, and has far less of an effect on the slow EPSP and the modulation. Gramine also diminishes the depolarization evoked by pressure-applied serotonin, showing that it is a serotonin antagonist in this system. In contrast, methysergide greatly

  3. The pathophysiological functions mediated by D-1 dopamine receptors

    International Nuclear Information System (INIS)

    Goldstein, M.; Kuga, S.; Meller, E.; SHimizu, Y.

    1986-01-01

    This chapter describes some behavioral responses which might be mediated by D 1 and D 2 DA receptors, and the authors discuss their clinical relevance. It was of considerable interest to determine whether a selective D 1 DA antagonist, such as SCH 23390, will induce catalepsy and whether this behavior is mediated by D 1 , or by both D 1 and D 2 DA receptors. Rats were used in the experiments. The authors examined whether the addition of the S 2 antagonist ketanserin affects the displacement of 3 H-Spi by SCH 23390. Induction of self-mutilating biting (SMB) behavior in monkeys with unilateral ventromedial tegmental (VMT) lesions by DA agonists and its prevention by DA antagonists is examined. The authors also discuss the possible relationships between abnormal guanine nucleotide metabolism and dopaminergic neuronal function through the implications in LeschNyhan syndrome and in some mental disorders

  4. Ligand-mediated negative regulation of a chimeric transmembrane receptor tyrosine phosphatase

    DEFF Research Database (Denmark)

    Desai, D M; Sap, J; Schlessinger, J

    1993-01-01

    CD45, a transmembrane protein tyrosine phosphatase (PTPase), is required for TCR signaling. Multiple CD45 isoforms, differing in the extracellular domain, are expressed in a tissue- and activation-specific manner, suggesting an important function for this domain. We report that a chimeric protein...... that ligand-mediated regulation of receptor-PTPases may have mechanistic similarities with receptor tyrosine kinases....

  5. Metabotropic glutamatergic receptors and their ligands in drug addiction.

    Science.gov (United States)

    Pomierny-Chamioło, Lucyna; Rup, Kinga; Pomierny, Bartosz; Niedzielska, Ewa; Kalivas, Peter W; Filip, Małgorzata

    2014-06-01

    Glutamatergic excitatory transmission is implicated in physiological and pathological conditions like learning, memory, neuronal plasticity and emotions, while glutamatergic abnormalities are reported in numerous neurological and psychiatric disorders, including neurodegenerative diseases, epilepsy, stroke, traumatic brain injury, depression, anxiety, schizophrenia and pain. Also, several lines of evidence have accumulated indicating a pivotal role for glutamatergic neurotransmission in mediating addictive behaviors. Among the proteins regulating glutamatergic transmission, the metabotropic glutamate receptors (mGluR) are being developed as pharmacological targets for treating many neuropsychiatric disorders, including drug addiction. In this review we describe the molecular structure of mGluRs and their distribution, physiology and pharmacology in the central nervous system, as well as their use as targets in preclinical studies of drug addiction. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Comparison of lentiviral and sleeping beauty mediated αβ T cell receptor gene transfer.

    Directory of Open Access Journals (Sweden)

    Anne-Christine Field

    Full Text Available Transfer of tumour antigen-specific receptors to T cells requires efficient delivery and integration of transgenes, and currently most clinical studies are using gamma retroviral or lentiviral systems. Whilst important proof-of-principle data has been generated for both chimeric antigen receptors and αβ T cell receptors, the current platforms are costly, time-consuming and relatively inflexible. Alternative, more cost-effective, Sleeping Beauty transposon-based plasmid systems could offer a pathway to accelerated clinical testing of a more diverse repertoire of recombinant high affinity T cell receptors. Nucleofection of hyperactive SB100X transposase-mediated stable transposition of an optimised murine-human chimeric T cell receptor specific for Wilm's tumour antigen from a Sleeping Beauty transposon plasmid. Whilst transfer efficiency was lower than that mediated by lentiviral transduction, cells could be readily enriched and expanded, and mediated effective target cells lysis in vitro and in vivo. Integration sites of transposed TCR genes in primary T cells were almost randomly distributed, contrasting the predilection of lentiviral vectors for transcriptionally active sites. The results support exploitation of the Sleeping Beauty plasmid based system as a flexible and adaptable platform for accelerated, early-phase assessment of T cell receptor gene therapies.

  7. GABA-A Receptors Mediate Tonic Inhibition and Neurosteroid Sensitivity in the Brain.

    Science.gov (United States)

    Reddy, Doodipala Samba

    2018-01-01

    Neurosteroids like allopregnanolone (AP) are positive allosteric modulators of synaptic and extrasynaptic GABA-A receptors. AP and related neurosteroids exhibit a greater potency for δ-containing extrasynaptic receptors. The δGABA-A receptors, which are expressed extrasynaptically in the dentate gyrus and other regions, contribute to tonic inhibition, promoting network shunting as well as reducing seizure susceptibility. Levels of endogenous neurosteroids fluctuate with ovarian cycle. Natural and synthetic neurosteroids maximally potentiate tonic inhibition in the hippocampus and provide robust protection against a variety of limbic seizures and status epilepticus. Recently, a consensus neurosteroid pharmacophore model has been proposed at extrasynaptic δGABA-A receptors based on structure-activity relationship for functional activation of tonic currents and seizure protection. Aside from anticonvulsant actions, neurosteroids have been found to be powerful anxiolytic and anesthetic agents. Neurosteroids and Zn 2+ have preferential affinity for δ-containing receptors. Thus, Zn 2+ can prevent neurosteroid activation of extrasynaptic δGABA-A receptor-mediated tonic inhibition. Recently, we demonstrated that Zn 2+ selectively inhibits extrasynaptic δGABA-A receptors and thereby fully prevents AP activation of tonic inhibition and seizure protection. We confirmed that neurosteroids exhibit greater sensitivity at extrasynaptic δGABA-A receptors. Overall, extrasynaptic GABA-A receptors are primary mediators of tonic inhibition in the brain and play a key role in the pathophysiology of epilepsy and other neurological disorders. © 2018 Elsevier Inc. All rights reserved.

  8. Vascular endothelin ET(B) receptor-mediated contraction requires phosphorylation of ERK1/2 proteins

    DEFF Research Database (Denmark)

    Luo, Guogang; Jamali, Roya; Cao, Yong-Xiao

    2006-01-01

    In cardiovascular diseases, endothelin type B (ET(B)) receptors in arterial smooth muscle cells are upregulated. The present study revealed that organ culture of rat mesenteric artery segments enhanced endothelin ET(B) receptor-mediated contraction paralleled with increase in the receptor mRNA an...

  9. Vitamin E-Mediated Modulation of Glutamate Receptor Expression in an Oxidative Stress Model of Neural Cells Derived from Embryonic Stem Cell Cultures

    Directory of Open Access Journals (Sweden)

    Afifah Abd Jalil

    2017-01-01

    Full Text Available Glutamate is the primary excitatory neurotransmitter in the central nervous system. Excessive concentrations of glutamate in the brain can be excitotoxic and cause oxidative stress, which is associated with Alzheimer’s disease. In the present study, the effects of vitamin E in the form of tocotrienol-rich fraction (TRF and alpha-tocopherol (α-TCP in modulating the glutamate receptor and neuron injury markers in an in vitro model of oxidative stress in neural-derived embryonic stem (ES cell cultures were elucidated. A transgenic mouse ES cell line (46C was differentiated into a neural lineage in vitro via induction with retinoic acid. These cells were then subjected to oxidative stress with a significantly high concentration of glutamate. Measurement of reactive oxygen species (ROS was performed after inducing glutamate excitotoxicity, and recovery from this toxicity in response to vitamin E was determined. The gene expression levels of glutamate receptors and neuron-specific enolase were elucidated using real-time PCR. The results reveal that neural cells derived from 46C cells and subjected to oxidative stress exhibit downregulation of NMDA, kainate receptor, and NSE after posttreatment with different concentrations of TRF and α-TCP, a sign of neurorecovery. Treatment of either TRF or α-TCP reduced the levels of ROS in neural cells subjected to glutamate-induced oxidative stress; these results indicated that vitamin E is a potent antioxidant.

  10. Testin, a novel binding partner of the calcium-sensing receptor, enhances receptor-mediated Rho-kinase signalling

    International Nuclear Information System (INIS)

    Magno, Aaron L.; Ingley, Evan; Brown, Suzanne J.; Conigrave, Arthur D.; Ratajczak, Thomas; Ward, Bryan K.

    2011-01-01

    Highlights: → A yeast two-hybrid screen revealed testin bound to the calcium-sensing receptor. → The second zinc finger of LIM domain 1 of testin is critical for interaction. → Testin bound to a region of the receptor tail important for cell signalling. → Testin and receptor interaction was confirmed in mammalian (HEK293) cells. → Overexpression of testin enhanced receptor-mediated Rho signalling in HEK293 cells. -- Abstract: The calcium-sensing receptor (CaR) plays an integral role in calcium homeostasis and the regulation of other cellular functions including cell proliferation and cytoskeletal organisation. The multifunctional nature of the CaR is manifested through ligand-dependent stimulation of different signalling pathways that are also regulated by partner binding proteins. Following a yeast two-hybrid library screen using the intracellular tail of the CaR as bait, we identified several novel binding partners including the focal adhesion protein, testin. Testin has not previously been shown to interact with cell surface receptors. The sites of interaction between the CaR and testin were mapped to the membrane proximal region of the receptor tail and the second zinc-finger of LIM domain 1 of testin, the integrity of which was found to be critical for the CaR-testin interaction. The CaR-testin association was confirmed in HEK293 cells by coimmunoprecipitation and confocal microscopy studies. Ectopic expression of testin in HEK293 cells stably expressing the CaR enhanced CaR-stimulated Rho activity but had no effect on CaR-stimulated ERK signalling. These results suggest an interplay between the CaR and testin in the regulation of CaR-mediated Rho signalling with possible effects on the cytoskeleton.

  11. Upregulation of endothelin ETB receptor-mediated vasoconstriction in rat coronary artery after organ culture

    DEFF Research Database (Denmark)

    Eskesen, Karen; Edvinsson, Lars

    2006-01-01

    The aim of this study was to examine if endothelin ET(B) receptor-mediated contraction occurred in isolated segments of rat coronary arteries during organ culture. Presence of contractile endothelin ET(B) receptors was studied by measuring the change in isometric tension in rings of left anterior......(+)-solution was not modified after 1 day in culture medium. The experiments indicate that organ culture of rat coronary arteries upregulate endothelin ET(B) receptor-mediated contraction by inducing synthesis of new protein....... descending coronary arteries isolated from hearts of rats as response to application of the selective endothelin ET(B) receptor agonist, Sarafotoxin 6c and endothelin-1. In segments cultured 1 day in serum free Dulbecco's Modified Eagle's Medium, Sarafotoxin 6c induced a concentration dependent contraction...

  12. Distinct structural features of cyclothiazide are responsible for effects on peak current amplitude and desensitization kinetics at iGluR2

    DEFF Research Database (Denmark)

    Hald, Helle; Ahring, Philip Kiær; Timmermann, Daniel Brunicardi

    2009-01-01

    Ionotropic glutamate receptors (iGluRs) mediate fast excitatory neurotransmission. Upon glutamate application, 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid receptors undergo rapid and almost complete desensitization that can be attenuated by positive allosteric modulators. The molecu......Ionotropic glutamate receptors (iGluRs) mediate fast excitatory neurotransmission. Upon glutamate application, 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid receptors undergo rapid and almost complete desensitization that can be attenuated by positive allosteric modulators......) in micromolar: 10 (CTZ), 26 (NS1493), 43 (NS5206), and 48 (NS5217)]. The four modulators divide into three groups according to efficacy and desensitization kinetics: (1) CTZ increases the peak current efficacy twice as much as the three analogues and nearly completely blocks receptor desensitization; (2) NS5206...... and NS5217 have low efficacy and only attenuate desensitization partially; (3) NS1493 has low efficacy but nearly completely blocks receptor desensitization. A hydrophobic substituent at the 3-position of the 1,1-dioxo-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine ring system is important for compound...

  13. Interacting cannabinoid and opioid receptors in the nucleus accumbens core control adolescent social play

    Directory of Open Access Journals (Sweden)

    Antonia Manduca

    2016-11-01

    Full Text Available Social play behavior is a highly rewarding, developmentally important form of social interaction in young mammals. However, its neurobiological underpinnings remain incompletely understood. Previous work has suggested that opioid and endocannabinoid neurotransmission interact in the modulation of social play. Therefore, we combined behavioral, pharmacological, electrophysiological and genetic approaches to elucidate the role of the endocannabinoid 2-arachidonoylglycerol (2-AG in social play, and how cannabinoid and opioid neurotransmission interact to control social behavior in adolescent rodents. Systemic administration of the 2-AG hydrolysis inhibitor JZL184 or the opioid receptor agonist morphine increased social play behavior in adolescent rats. These effects were blocked by systemic pretreatment with either CB1 cannabinoid receptor (CB1R or mu-opioid receptor (MOR antagonists. The social play-enhancing effects of systemic morphine or JZL184 treatment were also prevented by direct infusion of the CB1R antagonist SR141716 and the MOR antagonist naloxone into the nucleus accumbens core (NAcC. Searching for synaptic correlates of these effects in adolescent NAcC excitatory synapses, we observed that CB1R antagonism blocked the effect of the MOR agonist DAMGO and, conversely, that naloxone reduced the effect of a cannabinoid agonist. These results were recapitulated in mice, and completely abolished in CB1R and MOR knockout mice, suggesting that the functional interaction between CB1R and MOR in the NAcC in the modulation of mediates social behavior is widespread in rodents. The data shed new light on the mechanism by which endocannabinoid lipids and opioid peptides interact to orchestrate rodent socioemotional behaviors.

  14. Of pheromones and kairomones: what receptors mediate innate emotional responses?

    Science.gov (United States)

    Fortes-Marco, Lluis; Lanuza, Enrique; Martinez-Garcia, Fernando

    2013-09-01

    Some chemicals elicit innate emotionally laden behavioral responses. Pheromones mediate sexual attraction, parental care or agonistic confrontation, whereas predators' kairomones elicit defensive behaviors in their preys. This essay explores the hypothesis that the detection of these semiochemicals relies on highly specific olfactory and/or vomeronasal receptors. The V1R, V2R, and formyl-peptide vomeronasal receptors bind their ligands in highly specific and sensitive way, thus being good candidates for pheromone- or kairomone-detectors (e.g., secreted and excreted proteins, peptides and lipophilic volatiles). The olfactory epithelium also expresses specific receptors, for example trace amine-associated receptors (TAAR) and guanylyl cyclase receptors (GC-D and other types), some of which bind kairomones and putative pheromones. However, most of the olfactory neurons express canonical olfactory receptors (ORs) that bind many ligands with different affinity, being not suitable for mediating responses to pheromones and kairomones. In this respect, trimethylthiazoline (TMT) is considered a fox-derived kairomone for mice and rats, but it seems to be detected by canonical ORs. Therefore, we have reassessed the kairomonal nature of TMT by analyzing the behavioral responses of outbred (CD1) and inbred mice (C57BL/J6) to TMT. Our results confirm that both mouse strains avoid TMT, which increases immobility in C57BL/J6, but not CD1 mice. However, mice of both strains sniff at TMT throughout the test and show no trace of TMT-induced contextual conditioning (immobility or avoidance). This suggests that TMT is not a kairomone but, similar to a loud noise, in high concentrations it induces aversion and stress as unspecific responses to a strong olfactory stimulation. Copyright © 2013 Wiley Periodicals, Inc.

  15. AMPA receptor mediated excitotoxicity in neocortical neurons is developmentally regulated and dependent upon receptor desensitization

    DEFF Research Database (Denmark)

    Jensen, J B; Schousboe, A; Pickering, D S

    1998-01-01

    with a fast and rapidly desensitizing response, this could explain the relatively low toxicity produced by 500 microM AMPA. This was investigated by blocking AMPA receptor desensitization with cyclothiazide. Using a lower concentration (25 microM) of AMPA, addition of 50 microM cyclothiazide increased...... the AMPA induced excitotoxicity in cultured cortical neurons at all DIV except for DIV 2. This combination of AMPA + cyclothiazide yielded 77% cell death for DIV 12 cultures. In contrast to the results observed with 500 microM AMPA, the neurotoxicity mediated directly by AMPA receptors when desensitization...

  16. Neuropharmacology of Purinergic Receptors in Human Submucous Plexus: Involvement of P2X1, P2X2, P2X3 Channels, P2Y and A3 Metabotropic Receptors in Neurotransmission

    Science.gov (United States)

    Liñán-Rico, A.; Wunderlich, JE.; Enneking, JT.; Tso, DR.; Grants, I.; Williams, KC.; Otey, A.; Michel, K.; Schemann, M.; Needleman, B.; Harzman, A.; Christofi, FL.

    2015-01-01

    Rationale The role of purinergic signaling in the human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission. Experimental Approach LSCM-Fluo-4-(Ca2+)-imaging of postsynaptic Ca2+ transients (PSCaTs) was used as a reporter of neural activity. Synaptic transmission was evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons from 234 separate ganglia 107 patients; immunochemical labeling for P2XRs of neurons in ganglia from 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging was used to test effects of adenosine on fast excitatory synaptic potentials (fEPSPs). Results Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines. Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-β,γ-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50=25μM), sensitive to MRS1220-antagonism (A3AR). A P2Y agonist ADPβS inhibits PSCaTs (IC50=111nM) in neurons without stimulatory ADPβS responses (EC50=960nM). ATP or a P2X1,2,2/3 (α,β-MeATP) agonist evokes fast, slow, biphasic Ca2+ transients or Ca2+ oscillations (EC50=400μM). PSCaTs are sensitive to P2X1 antagonist NF279. Low (20nM) or high (5μM) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-ir follow the order P2X2>P2X1≫P2X3; P2X1+ P2X2 and P2X3+P2X2 are co-localized. RT-PCR identified mRNA-transcripts for P2X1-7,P2Y1,2,12-14R. Responsive neurons were also identified by HuC/D-ir. Conclusions Purines are critical regulators of neurotransmission in the human enteric nervous system. Purinergic signaling involves

  17. Negative modulation of NMDA receptor channel function by DREAM/calsenilin/KChIP3 provides neuroprotection?

    Science.gov (United States)

    Wang, KeWei; Wang, Yun

    2012-01-01

    N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels highly permeable to calcium and essential to excitatory neurotransmission. The NMDARs have attracted much attention because of their role in synaptic plasticity and excitotoxicity. Evidence has recently accumulated that NMDARs are negatively regulated by intracellular calcium binding proteins. The calcium-dependent suppression of NMDAR function serves as a feedback mechanism capable of regulating subsequent Ca2+ entry into the postsynaptic cell, and may offer an alternative approach to treating NMDAR-mediated excitotoxic injury. This short review summarizes the recent progress made in understanding the negative modulation of NMDAR function by DREAM/calsenilin/KChIP3, a neuronal calcium sensor (NCS) protein. PMID:22518099

  18. [Glutamate receptors genes polymorphism and the risk of paranoid schizophrenia in Russians and tatars from the Republic of Bashkortostan].

    Science.gov (United States)

    Gareeva, A E; Khusnutdinova, E K

    2014-01-01

    Schizophrenia is a severe mental disorder that affects about 1% of the world population, leading to disability and social exclusion. Glutamatergic neurotransmission is a violation of one of the main hypotheses put forward to explain the neurobiological mechanisms of schizophrenia. Post mortem studies have found changes in the degree of affinity glutamate receptors, their transcription, and altered expression of their subunits in the prefrontal cortex, hippocampus, and thalamus in patients with schizophrenia. As a result of genetic studies of gene family encoding ionotropic AMPA and kainate glutamate receptors in schizophrenia, ambiguous results were received. The association of polymorphic variants of genes GRIA2 and GRIK2 with paranoid schizophrenia and response to therapy with haloperidol in Russian and Tatar of the Republic of Bashkortostan was conducted in the present study. DNA samples of 257 patients with paranoid schizophrenia and of 349 healthy controls of Russian and Tatar ethnic group living in the Republic of Bashkortostan were involved into the present study. In the result of the present study: (1) high risk genetic markers of paranoid schizophrenia (PSZ) were obtained: in Russians-GR4IA2*CCC (OR = 9.60) and in Tatars-GRIK2*ATG (OR = 3.5), GRIK2*TGG (OR = 3.12) (2) The following low risk genetic markers of PSZ were revealed: in Tatars-GRIA2*T/T (rs43025506) of GRIA2 gene (OR = 0.34); in Russians.- GRIA2*CCT (OR = 0.481). (3) Genetic markers of low haloperido! treatment efficacy in respect of negative and positive symptoms GRIK2*T/T (rs2227281) of GRIK2 gene and GRAL42*C/C in Russians, GRIK2*A/A (rs995640) of GRIK2 gene in Tatars. (4) Genetic markers of low haloperidol treatment efficacy in respect of positive symptoms GRL42*C/C in Russians. The results of the present study support the hypothesis of the involvement of glutamate receptor genes in schizophrenia pathway. Considerable inter-ethnic'diversity of genetic risk factors for this disease was

  19. Illuminating the multifaceted roles of neurotransmission in shaping neuronal circuitry.

    Science.gov (United States)

    Okawa, Haruhisa; Hoon, Mrinalini; Yoshimatsu, Takeshi; Della Santina, Luca; Wong, Rachel O L

    2014-09-17

    Across the nervous system, neurons form highly stereotypic patterns of synaptic connections that are designed to serve specific functions. Mature wiring patterns are often attained upon the refinement of early, less precise connectivity. Much work has led to the prevailing view that many developing circuits are sculpted by activity-dependent competition among converging afferents, which results in the elimination of unwanted synapses and the maintenance and strengthening of desired connections. Studies of the vertebrate retina, however, have recently revealed that activity can play a role in shaping developing circuits without engaging competition among converging inputs that differ in their activity levels. Such neurotransmission-mediated processes can produce stereotypic wiring patterns by promoting selective synapse formation rather than elimination. We discuss how the influence of transmission may also be limited by circuit design and further highlight the importance of transmission beyond development in maintaining wiring specificity and synaptic organization of neural circuits. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Adaptive increase in D3 dopamine receptors in the brain reward circuits of human cocaine fatalities.

    Science.gov (United States)

    Staley, J K; Mash, D C

    1996-10-01

    The mesolimbic dopaminergic system plays a primary role in mediating the euphoric and rewarding effects of most abused drugs. Chronic cocaine use is associated with an increase in dopamine neurotransmission resulting from the blockade of dopamine uptake and is mediated by the activation of dopamine receptors. Recent studies have suggested that the D3 receptor subtype plays a pivotal role in the reinforcing effects of cocaine. The D3 receptor-preferring agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) is a reinforcer in rhesus monkeys trained to self-administer cocaine, but not in cocainenaive monkeys. In vitro autoradiographic localization of [3H]-(+)-7-OH-DPAT binding in the human brain demonstrated that D3 receptors were prevalent and highly localized over the ventromedial sectors of the striatum. Pharmacological characterization of [3H]-(+)-7-OH-DPAT binding to the human nucleus accumbens demonstrated a rank order of potency similar to that observed for binding to the cloned D3 receptor expressed in transfected cell lines. Region-of-interest analysis of [3H]-(+)-7-OH-DPAT binding to the D3 receptor demonstrated a one- to threefold elevation in the number of binding sites over particular sectors of the striatum and substantia nigra in cocaine overdose victims as compared with age-matched and drug-free control subjects. The elevated number of [3H]-(+)-7-OH-DPAT binding sites demonstrates that adaptive changes in the D3 receptor in the reward circuitry of the brain are associated with chronic cocaine abuse. These results suggest that the D3 receptor may be a useful target for drug development of anticocaine medications.

  1. Estrogen-mediated inactivation of FOXO3a by the G protein-coupled estrogen receptor GPER

    International Nuclear Information System (INIS)

    Zekas, Erin; Prossnitz, Eric R.

    2015-01-01

    Estrogen (17β-estradiol) promotes the survival and proliferation of breast cancer cells and its receptors represent important therapeutic targets. The cellular actions of estrogen are mediated by the nuclear estrogen receptors ERα and ERβ as well as the 7-transmembrane spanning G protein-coupled estrogen receptor (GPER). We previously reported that estrogen activates the phosphoinositide 3-kinase (PI3Kinase) pathway via GPER, resulting in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) production within the nucleus of breast cancer cells; however, the mechanisms and consequences of this activity remained unclear. MCF7 breast cancer cells were transfected with GFP-fused Forkhead box O3 (FOXO3) as a reporter to assess localization in response to estrogen stimulation. Inhibitors of PI3Kinases and EGFR were employed to determine the mechanisms of estrogen-mediated FOXO3a inactivation. Receptor knockdown with siRNA and the selective GPER agonist G-1 elucidated the estrogen receptor(s) responsible for estrogen-mediated FOXO3a inactivation. The effects of selective estrogen receptor modulators and downregulators (SERMs and SERDs) on FOXO3a in MCF7 cells were also determined. Cell survival (inhibition of apoptosis) was assessed by caspase activation. In the estrogen-responsive breast cancer cell line MCF7, FOXO3a inactivation occurs on a rapid time scale as a result of GPER, but not ERα, stimulation by estrogen, established by the GPER-selective agonist G-1 and knockdown of GPER and ERα. GPER-mediated inactivation of FOXO3a is effected by the p110α catalytic subunit of PI3Kinase as a result of transactivation of the EGFR. The SERMs tamoxifen and raloxifene, as well as the SERD ICI182,780, were active in mediating FOXO3a inactivation in a GPER-dependent manner. Additionally, estrogen-and G-1-mediated stimulation of MCF7 cells results in a decrease in caspase activation under proapoptotic conditions. Our results suggest that non-genomic signaling by GPER contributes

  2. β-Adrenergic Receptor Mediation of Stress-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in Mice: Roles for β1 and β2 Adrenergic Receptors

    Science.gov (United States)

    Vranjkovic, Oliver; Hang, Shona; Baker, David A.

    2012-01-01

    Stress can trigger the relapse of drug use in recovering cocaine addicts and reinstatement in rodent models through mechanisms that may involve norepinephrine release and β-adrenergic receptor activation. The present study examined the role of β-adrenergic receptor subtypes in the stressor-induced reinstatement of extinguished cocaine-induced (15 mg/kg i.p.) conditioned place preference in mice. Forced swim (6 min at 22°C) stress or activation of central noradrenergic neurotransmission by administration of the selective α2 adrenergic receptor antagonist 2-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-2,3-dihydro-1-methyl-1H-isoindole (BRL-44,408) (10 mg/kg i.p.) induced reinstatement in wild-type, but not β- adrenergic receptor-deficient Adrb1/Adrb2 double-knockout, mice. In contrast, cocaine administration (15 mg/kg i.p.) resulted in reinstatement in both wild-type and β-adrenergic receptor knockout mice. Stress-induced reinstatement probably involved β2 adrenergic receptors. The β2 adrenergic receptor antagonist -(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI-118,551) (1 or 2 mg/kg i.p.) blocked reinstatement by forced swim or BRL-44,408, whereas administration of the nonselective β-adrenergic receptor agonist isoproterenol (2 or 4 mg/kg i.p.) or the β2 adrenergic receptor-selective agonist clenbuterol (2 or 4 mg/kg i.p.) induced reinstatement. Forced swim-induced, but not BRL-44,408-induced, reinstatement was also blocked by a high (20 mg/kg) but not low (10 mg/kg) dose of the β1 adrenergic receptor antagonist betaxolol, and isoproterenol-induced reinstatement was blocked by pretreatment with either ICI-118,551 or betaxolol, suggesting a potential cooperative role for β1 and β2 adrenergic receptors in stress-induced reinstatement. Overall, these findings suggest that targeting β-adrenergic receptors may represent a promising pharmacotherapeutic strategy for preventing drug relapse, particularly in cocaine addicts whose drug use is stress

  3. Dynamic changes in extracellular release of GABA and glutamate in the lateral septum during social play behavior in juvenile rats: Implications for sex-specific regulation of social play behavior

    Science.gov (United States)

    Bredewold, Remco; Schiavo, Jennifer K.; van der Hart, Marieke; Verreij, Michelle; Veenema, Alexa H.

    2015-01-01

    Social play is a motivated and rewarding behavior that is displayed by nearly all mammals and peaks in the juvenile period. Moreover, social play is essential for the development of social skills and is impaired in social disorders like autism. We recently showed that the lateral septum (LS) is involved in the regulation of social play behavior in juvenile male and female rats. The LS is largely modulated by GABA and glutamate neurotransmission, but their role in social play behavior is unknown. Here, we determined whether social play behavior is associated with changes in the extracellular release of GABA and glutamate in the LS and to what extent such changes modulate social play behavior in male and female juvenile rats. Using intracerebral microdialysis in freely behaving rats, we found no sex difference in extracellular GABA concentrations, but extracellular glutamate concentrations are higher in males than in females under baseline condition and during social play. This resulted in a higher glutamate/GABA concentration ratio in males versus females and thus, an excitatory predominance in the LS of males. Furthermore, social play behavior in both sexes is associated with significant increases in extracellular release of GABA and glutamate in the LS. Pharmacological blockade of GABA-A receptors in the LS with bicuculline (100 ng/0.5 µl, 250 ng/0.5 µl) dose-dependently decreased the duration of social play behavior in both sexes. In contrast, pharmacological blockade of ionotropic glutamate receptors (NMDA and AMPA/kainate receptors) in the LS with AP-5 + CNQX (2 mM+0.4 mM/0.5 µl, 30 mM+3 mM/0.5 µl) dose-dependently decreased the duration of social play behavior in females, but did not alter social play behavior in males. Together, these data suggest a role for GABA neurotransmission in the LS in the regulation of juvenile social play behavior in both sexes, while glutamate neurotransmission in the LS is involved in the sex-specific regulation of juvenile

  4. Altered cortical GABA neurotransmission in schizophrenia: insights into novel therapeutic strategies.

    Science.gov (United States)

    Stan, Ana D; Lewis, David A

    2012-06-01

    Altered markers of cortical GABA neurotransmission are among the most consistently observed abnormalities in postmortem studies of schizophrenia. The altered markers are particularly evident between the chandelier class of GABA neurons and their synaptic targets, the axon initial segment (AIS) of pyramidal neurons. For example, in the dorsolateral prefrontal cortex of subjects with schizophrenia immunoreactivity for the GABA membrane transporter is decreased in presynaptic chandelier neuron axon terminals, whereas immunoreactivity for the GABAA receptor α2 subunit is increased in postsynaptic AIS. Both of these molecular changes appear to be compensatory responses to a presynaptic deficit in GABA synthesis, and thus could represent targets for novel therapeutic strategies intended to augment the brain's own compensatory mechanisms. Recent findings that GABA inputs from neocortical chandelier neurons can be powerfully excitatory provide new ideas about the role of these neurons in the pathophysiology of cortical dysfunction in schizophrenia, and consequently in the design of pharmacological interventions.

  5. Profiling neurotransmitter receptor expression in the Ambystoma mexicanum brain.

    Science.gov (United States)

    Reyes-Ruiz, Jorge Mauricio; Limon, Agenor; Korn, Matthew J; Nakamura, Paul A; Shirkey, Nicole J; Wong, Jamie K; Miledi, Ricardo

    2013-03-22

    Ability to regenerate limbs and central nervous system (CNS) is unique to few vertebrates, most notably the axolotl (Ambystoma sp.). However, despite the fact the neurotransmitter receptors are involved in axonal regeneration, little is known regarding its expression profile. In this project, RT-PCR and qPCR were performed to gain insight into the neurotransmitter receptors present in Ambystoma. Its functional ability was studied by expressing axolotl receptors in Xenopus laevis oocytes by either injection of mRNA or by direct microtransplantation of brain membranes. Oocytes injected with axolotl mRNA expressed ionotropic receptors activated by GABA, aspartate+glycine and kainate, as well as metabotropic receptors activated by acetylcholine and glutamate. Interestingly, we did not see responses following the application of serotonin. Membranes from the axolotl brain were efficiently microtransplanted into Xenopus oocytes and two types of native GABA receptors that differed in the temporal course of their responses and affinities to GABA were observed. Results of this study are necessary for further characterization of axolotl neurotransmitter receptors and may be useful for guiding experiments aimed at understanding activity-dependant limb and CNS regeneration. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  6. Epigenetic regulation of enteric neurotransmission by gut bacteria.

    Directory of Open Access Journals (Sweden)

    Tor eSavidge

    2016-01-01

    Full Text Available The Human Microbiome Project defined microbial community interactions with the human host, and provided important molecular insight into how epigenetic factors can influence intestinal ecosystems. Given physiological context, changes in gut microbial community structure are increasingly found to associate with alterations in enteric neurotransmission and disease. At present, it is not known whether shifts in microbial community dynamics represent cause or consequence of disease pathogenesis. The discovery of bacterial-derived neurotransmitters suggests further studies are needed to establish their role in enteric neuropathy. This mini-review highlights recent advances in bacterial communications to the autonomic nervous system and discusses emerging epigenetic data showing that diet, probiotic and antibiotic use may regulate enteric neurotransmission through modulation of microbial communities. Because of its limited scope, a particular emphasis is placed on bacterial regulation of enteric nervous system function in the intestine.

  7. The anticonvulsant action of the galanin receptor agonist NAX-5055 involves modulation of both excitatory- and inhibitory neurotransmission

    DEFF Research Database (Denmark)

    Walls, Anne B; Flynn, Sean P; West, Peter J

    2016-01-01

    -based anti-convulsant drugs was prompted. Based on this, a rationally designed GalR1 preferring galanin analogue, NAX-5055, was synthesized. This compound demonstrates anti-convulsant actions in several animal models of epilepsy. However, the alterations at the cellular level leading to this anti......-convulsant action of NAX-5055 are not known. Here we investigate the action of NAX-5055 at the cellular level by determining its effects on excitatory and inhibitory neurotransmission, i.e. vesicular release of glutamate and GABA, respectively, in cerebellar, neocortical and hippocampal preparations. In addition...

  8. Radial symmetry in a chimeric glutamate receptor pore

    Science.gov (United States)

    Wilding, Timothy J.; Lopez, Melany N.; Huettner, James E.

    2014-02-01

    Ionotropic glutamate receptors comprise two conformationally different A/C and B/D subunit pairs. Closed channels exhibit fourfold radial symmetry in the transmembrane domain (TMD) but transition to twofold dimer-of-dimers symmetry for extracellular ligand binding and N-terminal domains. Here, to evaluate symmetry in open pores we analysed interaction between the Q/R editing site near the pore loop apex and the transmembrane M3 helix of kainate receptor subunit GluK2. Chimeric subunits that combined the GluK2 TMD with extracellular segments from NMDA receptors, which are obligate heteromers, yielded channels made up of A/C and B/D subunit pairs with distinct substitutions along M3 and/or Q/R site editing status, in an otherwise identical homotetrameric TMD. Our results indicate that Q/R site interaction with M3 occurs within individual subunits and is essentially the same for both A/C and B/D subunit conformations, suggesting that fourfold pore symmetry persists in the open state.

  9. The role of excitatory amino acids and substance P in the mediation of the cough reflex within the nucleus tractus solitarii of the rabbit.

    Science.gov (United States)

    Mutolo, Donatella; Bongianni, Fulvia; Fontana, Giovanni A; Pantaleo, Tito

    2007-09-28

    We hypothesized that cough evoked by mechanical stimulation of the tracheobronchial tree in the rabbit is primarily mediated by glutamatergic neurotransmission at the level of the caudal portions of the medial subnucleus of the nucleus tractus solitarii (NTS) and the lateral commissural NTS where cough-related afferents terminate, and that this reflex is potentiated by local release of substance P. To test our hypothesis, we performed bilateral microinjections (30-50 nl) of ionotropic glutamate receptor antagonists or substance P into these locations in pentobarbitone anaesthetized, spontaneously breathing rabbits. Blockade of NMDA and non-NMDA receptors by 50mM kynurenic acid abolished the cough reflex without affecting the Breuer-Hering inflation reflex or the pulmonary chemoreflex. Blockade of non-NMDA receptors using 10mM CNQX or 5mM NBQX caused identical effects. Blockade of NMDA receptors by 10mM D-AP5 strongly reduced, but did not abolish cough responses. Microinjections of 1mM substance P increased peak and rate of rise of abdominal muscle activity as well as cough number. These results are the first to provide evidence that ionotropic glutamate receptors, especially non-NMDA receptors, located within specific regions of NTS are primarily involved in the mediation of cough evoked by mechanical stimulation of the tracheobronchial tree in the rabbit. Present findings on substance P cough-enhancing effects extend previous observations and are relevant to the tachykinin-mediated central sensitization of the cough reflex. They also may provide hints for further studies on centrally acting antitussive drugs.

  10. Astrocytes protect neurons against methylmercury via ATP/P2Y(1) receptor-mediated pathways in astrocytes.

    Science.gov (United States)

    Noguchi, Yusuke; Shinozaki, Youichi; Fujishita, Kayoko; Shibata, Keisuke; Imura, Yoshio; Morizawa, Yosuke; Gachet, Christian; Koizumi, Schuichi

    2013-01-01

    Methylmercury (MeHg) is a well known environmental pollutant that induces serious neuronal damage. Although MeHg readily crosses the blood-brain barrier, and should affect both neurons and glial cells, how it affects glia or neuron-to-glia interactions has received only limited attention. Here, we report that MeHg triggers ATP/P2Y1 receptor signals in astrocytes, thereby protecting neurons against MeHg via interleukin-6 (IL-6)-mediated pathways. MeHg increased several mRNAs in astrocytes, among which IL-6 was the highest. For this, ATP/P2Y1 receptor-mediated mechanisms were required because the IL-6 production was (i) inhibited by a P2Y1 receptor antagonist, MRS2179, (ii) abolished in astrocytes obtained from P2Y1 receptor-knockout mice, and (iii) mimicked by exogenously applied ATP. In addition, (iv) MeHg released ATP by exocytosis from astrocytes. As for the intracellular mechanisms responsible for IL-6 production, p38 MAP kinase was involved. MeHg-treated astrocyte-conditioned medium (ACM) showed neuro-protective effects against MeHg, which was blocked by anti-IL-6 antibody and was mimicked by the application of recombinant IL-6. As for the mechanism of neuro-protection by IL-6, an adenosine A1 receptor-mediated pathway in neurons seems to be involved. Taken together, when astrocytes sense MeHg, they release ATP that autostimulates P2Y1 receptors to upregulate IL-6, thereby leading to A1 receptor-mediated neuro-protection against MeHg.

  11. Stress-induced decrease of uterine blood flow in sheep is mediated by alpha 1-adrenergic receptors.

    Science.gov (United States)

    Dreiling, Michelle; Bischoff, Sabine; Schiffner, Rene; Rupprecht, Sven; Kiehntopf, Michael; Schubert, Harald; Witte, Otto W; Nathanielsz, Peter W; Schwab, Matthias; Rakers, Florian

    2016-09-01

    Prenatal maternal stress can be transferred to the fetus via a catecholamine-dependent decrease of uterine blood flow (UBF). However, it is unclear which group of adrenergic receptors mediates this mechanism of maternal-fetal stress transfer. We hypothesized that in sheep, alpha 1-adrenergic receptors may play a key role in catecholamine mediated UBF decrease, as these receptors are mainly involved in peripheral vasoconstriction and are present in significant number in the uterine vasculature. After chronic instrumentation at 125 ± 1 days of gestation (dGA; term 150 dGA), nine pregnant sheep were exposed at 130 ± 1 dGA to acute isolation stress for one hour without visual, tactile, or auditory contact with their flockmates. UBF, blood pressure (BP), heart rate (HR), stress hormones, and blood gases were determined before and during this isolation challenge. Twenty-four hours later, experiments were repeated during alpha 1-adrenergic receptor blockage induced by a continuous intravenous infusion of urapidil. In both experiments, ewes reacted to isolation with an increase in serum norepinephrine, cortisol, BP, and HR as typical signs of activation of sympatho-adrenal and the hypothalamic-pituitary-adrenal axis. Stress-induced UBF decrease was prevented by alpha 1-adrenergic receptor blockage. We conclude that UBF decrease induced by maternal stress in sheep is mediated by alpha 1-adrenergic receptors. Future studies investigating prevention strategies of impact of prenatal maternal stress on fetal health should consider selective blockage of alpha 1-receptors to interrupt maternal-fetal stress transfer mediated by utero-placental malperfusion.

  12. Synaptic neurotransmission depression in ventral tegmental dopamine neurons and cannabinoid-associated addictive learning.

    Science.gov (United States)

    Liu, Zhiqiang; Han, Jing; Jia, Lintao; Maillet, Jean-Christian; Bai, Guang; Xu, Lin; Jia, Zhengping; Zheng, Qiaohua; Zhang, Wandong; Monette, Robert; Merali, Zul; Zhu, Zhou; Wang, Wei; Ren, Wei; Zhang, Xia

    2010-12-20

    Drug addiction is an association of compulsive drug use with long-term associative learning/memory. Multiple forms of learning/memory are primarily subserved by activity- or experience-dependent synaptic long-term potentiation (LTP) and long-term depression (LTD). Recent studies suggest LTP expression in locally activated glutamate synapses onto dopamine neurons (local Glu-DA synapses) of the midbrain ventral tegmental area (VTA) following a single or chronic exposure to many drugs of abuse, whereas a single exposure to cannabinoid did not significantly affect synaptic plasticity at these synapses. It is unknown whether chronic exposure of cannabis (marijuana or cannabinoids), the most commonly used illicit drug worldwide, induce LTP or LTD at these synapses. More importantly, whether such alterations in VTA synaptic plasticity causatively contribute to drug addictive behavior has not previously been addressed. Here we show in rats that chronic cannabinoid exposure activates VTA cannabinoid CB1 receptors to induce transient neurotransmission depression at VTA local Glu-DA synapses through activation of NMDA receptors and subsequent endocytosis of AMPA receptor GluR2 subunits. A GluR2-derived peptide blocks cannabinoid-induced VTA synaptic depression and conditioned place preference, i.e., learning to associate drug exposure with environmental cues. These data not only provide the first evidence, to our knowledge, that NMDA receptor-dependent synaptic depression at VTA dopamine circuitry requires GluR2 endocytosis, but also suggest an essential contribution of such synaptic depression to cannabinoid-associated addictive learning, in addition to pointing to novel pharmacological strategies for the treatment of cannabis addiction.

  13. Synaptic neurotransmission depression in ventral tegmental dopamine neurons and cannabinoid-associated addictive learning.

    Directory of Open Access Journals (Sweden)

    Zhiqiang Liu

    2010-12-01

    Full Text Available Drug addiction is an association of compulsive drug use with long-term associative learning/memory. Multiple forms of learning/memory are primarily subserved by activity- or experience-dependent synaptic long-term potentiation (LTP and long-term depression (LTD. Recent studies suggest LTP expression in locally activated glutamate synapses onto dopamine neurons (local Glu-DA synapses of the midbrain ventral tegmental area (VTA following a single or chronic exposure to many drugs of abuse, whereas a single exposure to cannabinoid did not significantly affect synaptic plasticity at these synapses. It is unknown whether chronic exposure of cannabis (marijuana or cannabinoids, the most commonly used illicit drug worldwide, induce LTP or LTD at these synapses. More importantly, whether such alterations in VTA synaptic plasticity causatively contribute to drug addictive behavior has not previously been addressed. Here we show in rats that chronic cannabinoid exposure activates VTA cannabinoid CB1 receptors to induce transient neurotransmission depression at VTA local Glu-DA synapses through activation of NMDA receptors and subsequent endocytosis of AMPA receptor GluR2 subunits. A GluR2-derived peptide blocks cannabinoid-induced VTA synaptic depression and conditioned place preference, i.e., learning to associate drug exposure with environmental cues. These data not only provide the first evidence, to our knowledge, that NMDA receptor-dependent synaptic depression at VTA dopamine circuitry requires GluR2 endocytosis, but also suggest an essential contribution of such synaptic depression to cannabinoid-associated addictive learning, in addition to pointing to novel pharmacological strategies for the treatment of cannabis addiction.

  14. Synaptic Neurotransmission Depression in Ventral Tegmental Dopamine Neurons and Cannabinoid-Associated Addictive Learning

    Science.gov (United States)

    Liu, Zhiqiang; Han, Jing; Jia, Lintao; Maillet, Jean-Christian; Bai, Guang; Xu, Lin; Jia, Zhengping; Zheng, Qiaohua; Zhang, Wandong; Monette, Robert; Merali, Zul; Zhu, Zhou; Wang, Wei; Ren, Wei; Zhang, Xia

    2010-01-01

    Drug addiction is an association of compulsive drug use with long-term associative learning/memory. Multiple forms of learning/memory are primarily subserved by activity- or experience-dependent synaptic long-term potentiation (LTP) and long-term depression (LTD). Recent studies suggest LTP expression in locally activated glutamate synapses onto dopamine neurons (local Glu-DA synapses) of the midbrain ventral tegmental area (VTA) following a single or chronic exposure to many drugs of abuse, whereas a single exposure to cannabinoid did not significantly affect synaptic plasticity at these synapses. It is unknown whether chronic exposure of cannabis (marijuana or cannabinoids), the most commonly used illicit drug worldwide, induce LTP or LTD at these synapses. More importantly, whether such alterations in VTA synaptic plasticity causatively contribute to drug addictive behavior has not previously been addressed. Here we show in rats that chronic cannabinoid exposure activates VTA cannabinoid CB1 receptors to induce transient neurotransmission depression at VTA local Glu-DA synapses through activation of NMDA receptors and subsequent endocytosis of AMPA receptor GluR2 subunits. A GluR2-derived peptide blocks cannabinoid-induced VTA synaptic depression and conditioned place preference, i.e., learning to associate drug exposure with environmental cues. These data not only provide the first evidence, to our knowledge, that NMDA receptor-dependent synaptic depression at VTA dopamine circuitry requires GluR2 endocytosis, but also suggest an essential contribution of such synaptic depression to cannabinoid-associated addictive learning, in addition to pointing to novel pharmacological strategies for the treatment of cannabis addiction. PMID:21187978

  15. Tissue-type plasminogen activator-binding RNA aptamers inhibiting low-density lipoprotein receptor family-mediated internalisation.

    Science.gov (United States)

    Bjerregaard, Nils; Bøtkjær, Kenneth A; Helsen, Nicky; Andreasen, Peter A; Dupont, Daniel M

    2015-07-01

    Recombinant tissue-type plasminogen activator (tPA, trade name Alteplase), currently the only drug approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of cerebral ischaemic stroke, has been implicated in a number of adverse effects reportedly mediated by interactions with the low-density lipoprotein (LDL) family receptors, including neuronal cell death and an increased risk of cerebral haemorrhage. The tissue-type plasminogen activator is the principal initiator of thrombolysis in human physiology, an effect that is mediated directly via localised activation of the plasmin zymogen plasminogen at the surface of fibrin clots in the vascular lumen. Here, we sought to identify a ligand to tPA capable of inhibiting the relevant LDL family receptors without interfering with the fibrinolytic activity of tPA. Systematic evolution of ligands by exponential enrichment (SELEX) was employed to isolate tPA-binding RNA aptamers, which were characterised in biochemical assays of tPA association to low density lipoprotein receptor-related protein-1 (LRP-1, an LDL receptor family member); tPA-mediated in vitro and ex vivo clot lysis; and tPA-mediated plasminogen activation in the absence and presence of a stimulating soluble fibrin fragment. Two aptamers, K18 and K32, had minimal effects on clot lysis, but were able to efficiently inhibit tPA-LRP-1 association and LDL receptor family-mediated endocytosis in human vascular endothelial cells and astrocytes. These observations suggest that coadministration alongside tPA may be a viable strategy to improve the safety of thrombolytic treatment of cerebral ischaemic stroke by restricting tPA activity to the vascular lumen.

  16. Identification of potential pathway mediation targets in Toll-like receptor signaling.

    Directory of Open Access Journals (Sweden)

    Fan Li

    2009-02-01

    Full Text Available Recent advances in reconstruction and analytical methods for signaling networks have spurred the development of large-scale models that incorporate fully functional and biologically relevant features. An extended reconstruction of the human Toll-like receptor signaling network is presented herein. This reconstruction contains an extensive complement of kinases, phosphatases, and other associated proteins that mediate the signaling cascade along with a delineation of their associated chemical reactions. A computational framework based on the methods of large-scale convex analysis was developed and applied to this network to characterize input-output relationships. The input-output relationships enabled significant modularization of the network into ten pathways. The analysis identified potential candidates for inhibitory mediation of TLR signaling with respect to their specificity and potency. Subsequently, we were able to identify eight novel inhibition targets through constraint-based modeling methods. The results of this study are expected to yield meaningful avenues for further research in the task of mediating the Toll-like receptor signaling network and its effects.

  17. Estudio computacional de las relaciones evolutivas de los receptores ionotrópicos NMDA, AMPA y kainato en cuatro especies de primates

    Directory of Open Access Journals (Sweden)

    Francy Johanna Moreno-Pedraza

    2010-12-01

    Full Text Available Computational study of the evolutionary relationships of the ionotropic receptors NMDA, AMPA and kainate in four species ofprimates. Objective. To identify the influence of changes on the secondary structure and evolutionary relationship of NMDA, AMPA andkainate receptors in Homo sapiens, Pan troglodytes, Pongo pygmaeus and Macaca mulatta. Materials and methods. We identified 91sequences for NMDA, AMPA and kainate receptors and analyzed with software for predicting secondary structure, phosphorylation sites,multiple alignments, selection of protein evolution models and phylogenetic prediction. Results. We found that subunits GLUR5, NR2A,NR2C and NR3A showed structural changes in the C-terminal region and formation or loss of phosphorylation sites in this zone.Additionally the phylogenetic prediction suggests that the NMDA NR2 subunits are the closest to the ancestral node that gives rise to theother subunits. Conclusions. Changes in structure and phosphorylation sites in GLUR5, NR2A, NR2C and NR3A subunits suggestvariations in the interaction of the C-terminal region with kinase proteins and with proteins with PDZ domains, which could affect thetrafficking and anchoring of the subunits. On the other hand, the phylogenetic prediction suggests that the changes that occurred in the NR2subunits gave rise to the other subunits of glutamate ionotropic receptors, primarily because the NMDA and particularly the NR2D subunitsare the most closely related to the ancestral node that possibly gave rise to the iGluRs.

  18. Reaching Out to Send a Message: Proteins Associated with Neurite Outgrowth and Neurotransmission are Altered with Age in the Long-Lived Naked Mole-Rat.

    Science.gov (United States)

    Triplett, Judy C; Swomley, Aaron M; Kirk, Jessime; Grimes, Kelly M; Lewis, Kaitilyn N; Orr, Miranda E; Rodriguez, Karl A; Cai, Jian; Klein, Jon B; Buffenstein, Rochelle; Butterfield, D Allan

    2016-07-01

    Aging is the greatest risk factor for developing neurodegenerative diseases, which are associated with diminished neurotransmission as well as neuronal structure and function. However, several traits seemingly evolved to avert or delay age-related deterioration in the brain of the longest-lived rodent, the naked mole-rat (NMR). The NMR remarkably also exhibits negligible senescence, maintaining an extended healthspan for ~75 % of its life span. Using a proteomic approach, statistically significant changes with age in expression and/or phosphorylation levels of proteins associated with neurite outgrowth and neurotransmission were identified in the brain of the NMR and include: cofilin-1; collapsin response mediator protein 2; actin depolymerizing factor; spectrin alpha chain; septin-7; syntaxin-binding protein 1; synapsin-2 isoform IIB; and dynamin 1. We hypothesize that such changes may contribute to the extended lifespan and healthspan of the NMR.

  19. Tachykinin NK₁ receptor antagonist co-administration attenuates opioid withdrawal-mediated spinal microglia and astrocyte activation.

    Science.gov (United States)

    Tumati, Suneeta; Largent-Milnes, Tally M; Keresztes, Attila I; Yamamoto, Takashi; Vanderah, Todd W; Roeske, William R; Hruby, Victor J; Varga, Eva V

    2012-06-05

    Prolonged morphine treatment increases pain sensitivity in many patients. Enhanced spinal Substance P release is one of the adaptive changes associated with sustained opioid exposure. In addition to pain transmitting second order neurons, spinal microglia and astrocytes also express functionally active Tachykinin NK₁ (Substance P) receptors. In the present work we investigated the role of glial Tachykinin NK₁ receptors in morphine withdrawal-mediated spinal microglia and astrocyte activation. Our data indicate that intrathecal co-administration (6 days, twice daily) of a selective Tachykinin NK₁ receptor antagonist (N-acetyl-L-tryptophan 3,5-bis(trifluoromethyl)benzylester (L-732,138; 20 μg/injection)) attenuates spinal microglia and astrocyte marker and pro-inflammatory mediator immunoreactivity as well as hyperalgesia in withdrawn rats. Furthermore, covalent linkage of the opioid agonist with a Tachykinin NK₁ antagonist pharmacophore yielded a bivalent compound that did not augment spinal microglia or astrocyte marker or pro-inflammatory mediator immunoreactivity and did not cause paradoxical pain sensitization upon drug withdrawal. Thus, bivalent opioid/Tachykinin NK₁ receptor antagonists may provide a novel paradigm for long-term pain management.

  20. SR-B1 Is a Silica Receptor that Mediates Canonical Inflammasome Activation

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    Misato Tsugita

    2017-01-01

    Full Text Available The inhalation of silica dust is associated with fibrosis and lung cancer, which are triggered by macrophage inflammatory responses; however, how macrophages recognize silica remains largely unknown. Here, we identify by functional expression cloning the class B scavenger receptor SR-B1 as a silica receptor. Through an extracellular α-helix, both mouse and human SR-B1 specifically recognized amorphous and crystalline silica, but not titanium dioxide nanoparticles, latex nanoparticles, or monosodium urate crystals, although all particles exhibited negative surface potentials. Genetic deletion of SR-B1 and masking of SR-B1 by monoclonal antibodies showed that SR-B1-mediated recognition of silica is associated with caspase-1-mediated inflammatory responses in mouse macrophages and human peripheral blood monocytes. Furthermore, SR-B1 was involved in silica-induced pulmonary inflammation in mice. These results indicate that SR-B1 is a silica receptor associated with canonical inflammasome activation.

  1. Mitochondria and Neurotransmission: Evacuating the Synapse

    OpenAIRE

    Hollenbeck, Peter J.

    2005-01-01

    An abundance of mitochondria has been the hallmark of synapses since their first ultrastructural description 50 years ago. Mitochondria have been shown to be essential for synaptic form and function in many systems, but until recently it has not been clear exactly what role(s) they play in neurotransmission. Now, evidence from the nervous system of Drosophila identifies the specific subcellular events that are most dependent upon nearby mitochondria.

  2. p-Coumaric acid activates the GABA-A receptor in vitro and is orally anxiolytic in vivo.

    Science.gov (United States)

    Scheepens, Arjan; Bisson, Jean-Francois; Skinner, Margot

    2014-02-01

    The increasing prevalence and social burden of subclinical anxiety in the western world represents a significant psychosocial and financial cost. Consumers are favouring a more natural and nonpharmacological approach for alleviating the effects of everyday stress and anxiety. The gamma-aminobutyric acid (GABA) receptor is the primary mediator of central inhibitory neurotransmission, and GABA-receptor agonists are well known to convey anxiolytic effects. Using an in vitro screening approach to identify naturally occurring phytochemical GABA agonists, we discovered the plant secondary metabolite p-coumaric acid to have significant GABAergic activity, an effect that could be blocked by co-administration of the specific GABA-receptor antagonist, picrotoxin. Oral administration of p-coumaric acid to rodents induced a significant anxiolytic effect in vivo as measured using the elevated plus paradigm, in line with the effects of oral diazepam. Given that p-coumaric acid is reasonably well absorbed following oral consumption in man and is relatively nontoxic, it may be suitable for the formulation of a safe and effective anxiolytic functional food. Copyright © 2013 John Wiley & Sons, Ltd.

  3. Systemic administration of kainic acid induces selective time dependent decrease in [125I]insulin-like growth factor I, [125I]insulin-like growth factor II and [125I]insulin receptor binding sites in adult rat hippocampal formation

    International Nuclear Information System (INIS)

    Quirion, R.; Chabot, J.-G.; Dore, S.; Seto, D.; Kar, S.

    1997-01-01

    Administration of kainic acid evokes acute seizure in hippocampal pathways that results in a complex sequence of functional and structural alterations resembling human temporal lobe epilepsy. The structural alterations induced by kainic acid include selective loss of neurones in CA1-CA3 subfields and the hilar region of the dentate gyrus followed by sprouting and permanent reorganization of the synaptic connections of the mossy fibre pathways. Although the neuronal degeneration and process of reactive synaptogenesis have been extensively studied, at present little is known about means to prevent pathological conditions leading to kainate-induced cell death. In the present study, to address the role of insulin-like growth factors I and II, and insulin in neuronal survival as well as synaptic reorganization following kainate-induced seizure, the time course alterations of the corresponding receptors were evaluated. Additionally, using histological preparations, the temporal profile of neuronal degeneration and hypertrophy of resident astroglial cells were also studied. [ 125 I]Insulin-like growth factor I binding was found to be decreased transiently in almost all regions of the hippocampal formation at 12 h following treatment with kainic acid. The dentate hilar region however, exhibited protracted decreases in [ 125 I]insulin-like growth factor I receptor sites throughout (i.e. 30 days) the study. [ 125 I]Insulin-like growth factor II receptor binding sites in the hippocampal formation were found to be differentially altered following systemic administration of kainic acid. A significant decrease in [ 125 I]insulin-like growth factor II receptor sites was observed in CA1 subfield and the pyramidal cell layer of the Ammon's horn at all time points studied whereas the hilar region and the stratum radiatum did not exhibit alteration at any time. A kainate-induced decrease in [ 125 I]insulin receptor binding was noted at all time points in the molecular layer of the

  4. Purinergic Receptors: Key Mediators of HIV-1 infection and inflammation

    Directory of Open Access Journals (Sweden)

    Talia H Swartz

    2015-11-01

    Full Text Available Human immunodeficiency virus (HIV-1 causes a chronic infection that afflicts more than 38 million individuals worldwide. While the infection can be suppressed with potent anti-retroviral therapies, individuals infected with HIV have elevated levels of inflammation as indicated by increased T cell activation, soluble biomarkers, and associated morbidity and mortality. A single mechanism linking HIV pathogenesis to this inflammation has yet to be identified. Purinergic receptors are known to mediate inflammation and have been shown to be required for HIV-1 infection at the level of HIV-1 membrane fusion. Here we review the literature on the role of purinergic receptors in HIV-1 infection and associated inflammation and describe a role for these receptors as potential therapeutic targets.

  5. Sigma-1 Receptor Plays a Negative Modulation on N-type Calcium Channel

    Directory of Open Access Journals (Sweden)

    Kang Zhang

    2017-05-01

    Full Text Available The sigma-1 receptor is a 223 amino acids molecular chaperone with a single transmembrane domain. It is resident to eukaryotic mitochondrial-associated endoplasmic reticulum and plasma membranes. By chaperone-mediated interactions with ion channels, G-protein coupled receptors and cell-signaling molecules, the sigma-1 receptor performs broad physiological and pharmacological functions. Despite sigma-1 receptors have been confirmed to regulate various types of ion channels, the relationship between the sigma-1 receptor and N-type Ca2+ channel is still unclear. Considering both sigma-1 receptors and N-type Ca2+ channels are involved in intracellular calcium homeostasis and neurotransmission, we undertake studies to explore the possible interaction between these two proteins. In the experiment, we confirmed the expression of the sigma-1 receptors and the N-type calcium channels in the cholinergic interneurons (ChIs in rat striatum by using single-cell reverse transcription-polymerase chain reaction (scRT-PCR and immunofluorescence staining. N-type Ca2+ currents recorded from ChIs in the brain slice of rat striatum was depressed when sigma-1 receptor agonists (SKF-10047 and Pre-084 were administrated. The inhibition was completely abolished by sigma-1 receptor antagonist (BD-1063. Co-expression of the sigma-1 receptors and the N-type calcium channels in Xenopus oocytes presented a decrease of N-type Ca2+ current amplitude with an increase of sigma-1 receptor expression. SKF-10047 could further depress N-type Ca2+ currents recorded from oocytes. The fluorescence resonance energy transfer (FRET assays and co-immunoprecipitation (Co-IP demonstrated that sigma-1 receptors and N-type Ca2+ channels formed a protein complex when they were co-expressed in HEK-293T (Human Embryonic Kidney -293T cells. Our results revealed that the sigma-1 receptors played a negative modulation on N-type Ca2+ channels. The mechanism for the inhibition of sigma-1 receptors on

  6. Receptor-Mediated Endocytosis and Brain Delivery of Therapeutic Biologics

    Directory of Open Access Journals (Sweden)

    Guangqing Xiao

    2013-01-01

    Full Text Available Transport of macromolecules across the blood-brain-barrier (BBB requires both specific and nonspecific interactions between macromolecules and proteins/receptors expressed on the luminal and/or the abluminal surfaces of the brain capillary endothelial cells. Endocytosis and transcytosis play important roles in the distribution of macromolecules. Due to the tight junction of BBB, brain delivery of traditional therapeutic proteins with large molecular weight is generally not possible. There are multiple pathways through which macromolecules can be taken up into cells through both specific and nonspecific interactions with proteins/receptors on the cell surface. This review is focused on the current knowledge of receptor-mediated endocytosis/transcytosis and brain delivery using the Angiopep-2-conjugated system and the molecular Trojan horses. In addition, the role of neonatal Fc receptor (FcRn in regulating the efflux of Immunoglobulin G (IgG from brain to blood, and approaches to improve the pharmacokinetics of therapeutic biologics by generating Fc fusion proteins, and increasing the pH dependent binding affinity between Fc and FcRn, are discussed.

  7. Receptor-mediated gene delivery using chemically modified chitosan

    International Nuclear Information System (INIS)

    Kim, T H; Jiang, H L; Nah, J W; Cho, M H; Akaike, T; Cho, C S

    2007-01-01

    Chitosan has been investigated as a non-viral vector because it has several advantages such as biocompatibility, biodegradability and low toxicity with high cationic potential. However, the low specificity and low transfection efficiency of chitosan need to be solved prior to clinical application. In this paper, we focused on the galactose or mannose ligand modification of chitosan for enhancement of cell specificity and transfection efficiency via receptor-mediated endocytosis in vitro and in vivo

  8. The brain cytoplasmic RNA BC1 regulates dopamine D2 receptor-mediated transmission in the striatum.

    Science.gov (United States)

    Centonze, Diego; Rossi, Silvia; Napoli, Ilaria; Mercaldo, Valentina; Lacoux, Caroline; Ferrari, Francesca; Ciotti, Maria Teresa; De Chiara, Valentina; Prosperetti, Chiara; Maccarrone, Mauro; Fezza, Filomena; Calabresi, Paolo; Bernardi, Giorgio; Bagni, Claudia

    2007-08-15

    Dopamine D(2) receptor (D(2)DR)-mediated transmission in the striatum is remarkably flexible, and changes in its efficacy have been heavily implicated in a variety of physiological and pathological conditions. Although receptor-associated proteins are clearly involved in specific forms of synaptic plasticity, the molecular mechanisms regulating the sensitivity of D(2) receptors in this brain area are essentially obscure. We have studied the physiological responses of the D(2)DR stimulations in mice lacking the brain cytoplasmic RNA BC1, a small noncoding dendritically localized RNA that is supposed to play a role in mRNA translation. We show that the efficiency of D(2)-mediated transmission regulating striatal GABA synapses is under the control of BC1 RNA, through a negative influence on D(2) receptor protein level affecting the functional pool of receptors. Ablation of the BC1 gene did not result in widespread dysregulation of synaptic transmission, because the sensitivity of cannabinoid CB(1) receptors was intact in the striatum of BC1 knock-out (KO) mice despite D(2) and CB(1) receptors mediated similar electrophysiological actions. Interestingly, the fragile X mental retardation protein FMRP, one of the multiple BC1 partners, is not involved in the BC1 effects on the D(2)-mediated transmission. Because D(2)DR mRNA is apparently equally translated in the BC1-KO and wild-type mice, whereas the protein level is higher in BC1-KO mice, we suggest that BC1 RNA controls D(2)DR indirectly, probably regulating translation of molecules involved in D(2)DR turnover and/or stability.

  9. Effects of HZE irradiation on chemical neurotransmission in rodent hippocampus

    Science.gov (United States)

    Machida, Mayumi

    Space radiation represents a significant risk to the CNS (central nervous system) during space missions. Most harmful are the HZE (high mass, highly charged (Z), high energy) particles, e.g. 56Fe, which possess high ionizing ability, dense energy deposition pattern, and high penetrance. Accumulating evidence suggests that radiation has significant impact on cognitive functions. In ground-base experiments, HZE radiation induces pronounced deficits in hippocampus dependent learning and memory in rodents. However, the mechanisms underlying these impairments are mostly unknown. Exposure to HZE radiation elevates the level of oxidation, resulting in cell loss, tissue damage and functional deficits through direct ionization and generation of reactive oxygen species (ROS). When hippocampal slices were exposed to ROS, neuronal excitability was reduced. My preliminary results showed enhanced radio-vulnerability of the hippocampus and reduction in basal and depolarization-evoked [3H]-norepinephrine release after HZE exposure. These results raised the possibility that HZE radiation deteriorates cognitive function through radiation-induced impairments in hippocampal chemical neurotransmission, the hypothesis of this dissertation. In Aim 1 I have focused on the effects of HZE radiation on release of major neurotransmitter systems in the hippocampus. I have further extended my research on the levels of receptors of these systems in Aim 2. In Aim 3, I have studied the level of oxidation in membranes of my samples. My research reveals that HZE radiation significantly reduces hyperosmotic sucrose evoked [3H]-glutamate and [14C]-GABA release both three and six months post irradiation. The same radiation regimen also significantly enhances oxidative stress as indicated by increased levels of lipid peroxidation in the hippocampus, suggesting that increased levels of lipid peroxidation may play a role in reduction of neurotransmitter release. HZE radiation also significantly reduces

  10. Environmental phthalate monoesters activate pregnane X receptor-mediated transcription

    International Nuclear Information System (INIS)

    Hurst, Christopher H.; Waxman, David J.

    2004-01-01

    Phthalate esters, widely used as plasticizers in the manufacture of products made of polyvinyl chloride, induce reproductive and developmental toxicities in rodents. The mechanism that underlies these effects of phthalate exposure, including the potential role of members of the nuclear receptor superfamily, is not known. The present study investigates the effects of phthalates on the pregnane X receptor (PXR), which mediates the induction of enzymes involved in steroid metabolism and xenobiotic detoxification. The ability of phthalate monoesters to activate PXR-mediated transcription was assayed in a HepG2 cell reporter assay following transfection with mouse PXR (mPXR), human PXR (hPXR), or the hPXR allelic variants V140M, D163G, and A370T. Mono-2-ethylhexyl phthalate (MEHP) increased the transcriptional activity of both mPXR and hPXR (5- and 15-fold, respectively) with EC 50 values of 7-8 μM. mPXR and hPXR were also activated by monobenzyl phthalate (MBzP, up to 5- to 6-fold) but were unresponsive to monomethyl phthalate and mono-n-butyl phthalate (M(n)BP) at the highest concentrations tested (300 μM). hPXR-V140M and hPXR-A370T exhibited patterns of phthalate responses similar to the wild-type receptor. By contrast, hPXR-D163G was unresponsive to all phthalate monoesters tested. Further studies revealed that hPXR-D163G did respond to rifampicin, but required approximately 40-fold higher concentrations than wild-type receptor, suggesting that the ligand-binding domain D163G variant has impaired ligand-binding activity. The responsiveness of PXR to activation by phthalate monoesters demonstrated here suggests that these ubiquitous environmental chemicals may, in part, exhibit their endocrine disruptor activities by altering PXR-regulated steroid hormone metabolism with potential adverse health effects in exposed individuals

  11. Sympatho-inhibitory properties of various AT1 receptor antagonists

    NARCIS (Netherlands)

    Balt, Jippe C.; Mathy, Marie-Jeanne; Pfaffendorf, Martin; van Zwieten, Peter A.

    2002-01-01

    It is well known that angiotensin II (Ang II) can facilitate the effects of sympathetic neurotransmission. In the present study, using various experimental models, we investigated the inhibitory effects of several Ang II subtype 1 receptor (AT1) antagonists on this Ang II-induced facilitation. We

  12. Sexual-incentive motivation and paced sexual behavior in female rats after treatment with drugs modifying dopaminergic neurotransmission.

    Science.gov (United States)

    Ellingsen, Ellinor; Agmo, Anders

    2004-03-01

    The effects of the dopamine receptor agonist apomorphine, the dopamine releaser amphetamine, and the dopamine receptor antagonist cis(Z)-flupenthixol on sexual-incentive motivation and on paced-mating behavior were studied in female rats. Apomorphine, in the doses of 0.125 and 0.5 mg/kg, showed a tendency to reduce incentive motivation. Ambulatory activity was inhibited, evidenced both by diminished distance moved and reduced velocity of movement. Amphetamine (0.25 and 1 mg/kg) and flupenthixol (0.25 and 0.5 mg/kg) failed to modify incentive motivation while stimulating and reducing ambulatory activity, respectively. In the mating test, apomorphine enhanced the latency to enter the male's half and reduced the number of proceptive behaviors. However, these effects were associated with the appearance of stereotyped sniffing. Amphetamine increased the propensity to escape from the male after a mount without having other effects. Flupenthixol augmented the duration of the lordosis posture. Neither amphetamine nor flupenthixol affected sniffing. These data show that facilitated dopaminergic neurotransmission stimulates neither paced female sexual behavior nor sexual-incentive motivation. Dopamine receptor blockade has slight consequences. It is concluded that dopamine is not a transmitter of major importance for unconditioned female sexual motivation and behavior.

  13. β1-adrenergic receptors activate two distinct signaling pathways in striatal neurons

    Science.gov (United States)

    Meitzen, John; Luoma, Jessie I.; Stern, Christopher M.; Mermelstein, Paul G.

    2010-01-01

    Monoamine action in the dorsal striatum and nucleus accumbens plays essential roles in striatal physiology. Although research often focuses on dopamine and its receptors, norepinephrine and adrenergic receptors are also crucial in regulating striatal function. While noradrenergic neurotransmission has been identified in the striatum, little is known regarding the signaling pathways activated by β-adrenergic receptors in this brain region. Using cultured striatal neurons, we characterized a novel signaling pathway by which activation of β1-adrenergic receptors leads to the rapid phosphorylation of cAMP Response Element Binding Protein (CREB), a transcription-factor implicated as a molecular switch underlying long-term changes in brain function. Norepinephrine-mediated CREB phosphorylation requires β1-adrenergic receptor stimulation of a receptor tyrosine kinase, ultimately leading to the activation of a Ras/Raf/MEK/MAPK/MSK signaling pathway. Activation of β1-adrenergic receptors also induces CRE-dependent transcription and increased c-fos expression. In addition, stimulation of β1-adrenergic receptors produces cAMP production, but surprisingly, β1-adrenergic receptor activation of adenylyl cyclase was not functionally linked to rapid CREB phosphorylation. These findings demonstrate that activation of β1-adrenergic receptors on striatal neurons can stimulate two distinct signaling pathways. These adrenergic actions can produce long-term changes in gene expression, as well as rapidly modulate cellular physiology. By elucidating the mechanisms by which norepinephrine and β1-adrenergic receptor activation affects striatal physiology, we provide the means to more fully understand the role of monoamines in modulating striatal function, specifically how norepinephrine and β1-adrenergic receptors may affect striatal physiology. PMID:21143600

  14. Genetic evidence for role of integration of fast and slow neurotransmission in schizophrenia.

    Science.gov (United States)

    Devor, A; Andreassen, O A; Wang, Y; Mäki-Marttunen, T; Smeland, O B; Fan, C-C; Schork, A J; Holland, D; Thompson, W K; Witoelar, A; Chen, C-H; Desikan, R S; McEvoy, L K; Djurovic, S; Greengard, P; Svenningsson, P; Einevoll, G T; Dale, A M

    2017-06-01

    The most recent genome-wide association studies (GWAS) of schizophrenia (SCZ) identified hundreds of risk variants potentially implicated in the disease. Further, novel statistical methodology designed for polygenic architecture revealed more potential risk variants. This can provide a link between individual genetic factors and the mechanistic underpinnings of SCZ. Intriguingly, a large number of genes coding for ionotropic and metabotropic receptors for various neurotransmitters-glutamate, γ-aminobutyric acid (GABA), dopamine, serotonin, acetylcholine and opioids-and numerous ion channels were associated with SCZ. Here, we review these findings from the standpoint of classical neurobiological knowledge of neuronal synaptic transmission and regulation of electrical excitability. We show that a substantial proportion of the identified genes are involved in intracellular cascades known to integrate 'slow' (G-protein-coupled receptors) and 'fast' (ionotropic receptors) neurotransmission converging on the protein DARPP-32. Inspection of the Human Brain Transcriptome Project database confirms that that these genes are indeed expressed in the brain, with the expression profile following specific developmental trajectories, underscoring their relevance to brain organization and function. These findings extend the existing pathophysiology hypothesis by suggesting a unifying role of dysregulation in neuronal excitability and synaptic integration in SCZ. This emergent model supports the concept of SCZ as an 'associative' disorder-a breakdown in the communication across different slow and fast neurotransmitter systems through intracellular signaling pathways-and may unify a number of currently competing hypotheses of SCZ pathophysiology.

  15. Age-dependent effects on social interaction of NMDA GluN2A receptor subtype-selective antagonism.

    Science.gov (United States)

    Green, Torrian L; Burket, Jessica A; Deutsch, Stephen I

    2016-07-01

    NMDA receptor-mediated neurotransmission is implicated in the regulation of normal sociability in mice. The heterotetrameric NMDA receptor is composed of two obligatory GluN1 and either two "modulatory" GluN2A or GluN2B receptor subunits. GluN2A and GluN2B-containing receptors differ in terms of their developmental expression, distribution between synaptic and extrasynaptic locations, and channel kinetic properties, among other differences. Because age-dependent differences in disruptive effects of GluN2A and GluN2B subtype-selective antagonists on sociability and locomotor activity have been reported in rats, the current investigation explored age-dependent effects of PEAQX, a GluN2A subtype-selective antagonist, on sociability, stereotypic behaviors emerging during social interaction, and spatial working memory in 4- and 8-week old male Swiss Webster mice. The data implicate an age-dependent contribution of GluN2A-containing NMDA receptors to the regulation of normal social interaction in mice. Specifically, at a dose of PEAQX devoid of any effect on locomotor activity and mouse rotarod performance, the social interaction of 8-week old mice was disrupted without any effect on the social salience of a stimulus mouse. Moreover, PEAQX attenuated stereotypic behavior emerging during social interaction in 4- and 8-week old mice. However, PEAQX had no effect on spontaneous alternations, a measure of spatial working memory, suggesting that neural circuits mediating sociability and spatial working memory may be discrete and dissociable from each other. Also, the data suggest that the regulation of stereotypic behaviors and sociability may occur independently of each other. Because expression of GluN2A-containing NMDA receptors occurs at a later developmental stage, they may be more involved in mediating the pathogenesis of ASDs in patients with histories of "regression" after a period of normal development than GluN2B receptors. Copyright © 2016 Elsevier Inc. All rights

  16. Lactate Receptor Sites Link Neurotransmission, Neurovascular Coupling, and Brain Energy Metabolism

    DEFF Research Database (Denmark)

    Lauritzen, Knut H; Morland, Cecilie; Puchades, Maja

    2013-01-01

    The G-protein-coupled lactate receptor, GPR81 (HCA1), is known to promote lipid storage in adipocytes by downregulating cAMP levels. Here, we show that GPR81 is also present in the mammalian brain, including regions of the cerebral neocortex and hippocampus, where it can be activated by physiolog......The G-protein-coupled lactate receptor, GPR81 (HCA1), is known to promote lipid storage in adipocytes by downregulating cAMP levels. Here, we show that GPR81 is also present in the mammalian brain, including regions of the cerebral neocortex and hippocampus, where it can be activated...

  17. The role of 5-HT(1A) receptors in learning and memory.

    Science.gov (United States)

    Ogren, Sven Ove; Eriksson, Therese M; Elvander-Tottie, Elin; D'Addario, Claudio; Ekström, Joanna C; Svenningsson, Per; Meister, Björn; Kehr, Jan; Stiedl, Oliver

    2008-12-16

    The ascending serotonin (5-HT) neurons innervate the cerebral cortex, hippocampus, septum and amygdala, all representing brain regions associated with various domains of cognition. The 5-HT innervation is diffuse and extensively arborized with few synaptic contacts, which indicates that 5-HT can affect a large number of neurons in a paracrine mode. Serotonin signaling is mediated by 14 receptor subtypes with different functional and transductional properties. The 5-HT(1A) subtype is of particular interest, since it is one of the main mediators of the action of 5-HT. Moreover, the 5-HT(1A) receptor regulates the activity of 5-HT neurons via autoreceptors, and it regulates the function of several neurotransmitter systems via postsynaptic receptors (heteroreceptors). This review assesses the pharmacological and genetic evidence that implicates the 5-HT(1A) receptor in learning and memory. The 5-HT(1A) receptors are in the position to influence the activity of glutamatergic, cholinergic and possibly GABAergic neurons in the cerebral cortex, hippocampus and in the septohippocampal projection, thereby affecting declarative and non-declarative memory functions. Moreover, the 5-HT(1A) receptor regulates several transduction mechanisms such as kinases and immediate early genes implicated in memory formation. Based on studies in rodents the stimulation of 5-HT(1A) receptors generally produces learning impairments by interfering with memory-encoding mechanisms. In contrast, antagonists of 5-HT(1A) receptors facilitate certain types of memory by enhancing hippocampal/cortical cholinergic and/or glutamatergic neurotransmission. Some data also support a potential role for the 5-HT(1A) receptor in memory consolidation. Available results also implicate the 5-HT(1A) receptor in the retrieval of aversive or emotional memories, supporting an involvement in reconsolidation. The contribution of 5-HT(1A) receptors in cognitive impairments in various psychiatric disorders is still

  18. Adenosine A2A receptor-dependent proliferation of pulmonary endothelial cells is mediated through calcium mobilization, PI3-kinase and ERK1/2 pathways

    International Nuclear Information System (INIS)

    Ahmad, Aftab; Schaack, Jerome B.; White, Carl W.; Ahmad, Shama

    2013-01-01

    Highlights: •A 2A receptor-induced pulmonary endothelial growth is mediated by PI3K and ERK1/2. •Cytosolic calcium mobilization is also critical for pulmonary endothelial growth. •Effectors of A 2A receptor, like tyrosine kinases and cAMP increase PI3K/Akt signaling. •Activation of A 2A receptor can contribute to vascular remodeling. -- Abstract: Hypoxia and HIF-2α-dependent A 2A receptor expression and activation increase proliferation of human lung microvascular endothelial cells (HLMVECs). This study was undertaken to investigate the signaling mechanisms that mediate the proliferative effects of A 2A receptor. A 2A receptor-mediated proliferation of HLMVECs was inhibited by intracellular calcium chelation, and by specific inhibitors of ERK1/2 and PI3-kinase (PI3K). The adenosine A 2A receptor agonist CGS21680 caused intracellular calcium mobilization in controls and, to a greater extent, in A 2A receptor-overexpressing HLMVECs. Adenoviral-mediated A 2A receptor overexpression as well as receptor activation by CGS21680 caused increased PI3K activity and Akt phosphorylation. Cells overexpressing A 2A receptor also manifested enhanced ERK1/2 phosphorylation upon CGS21680 treatment. A 2A receptor activation also caused enhanced cAMP production. Likewise, treatment with 8Br-cAMP increased PI3K activity. Hence A 2A receptor-mediated cAMP production and PI3K and Akt phosphorylation are potential mediators of the A 2A -mediated proliferative response of HLMVECs. Cytosolic calcium mobilization and ERK1/2 phosphorylation are other critical effectors of HLMVEC proliferation and growth. These studies underscore the importance of adenosine A 2A receptor in activation of survival and proliferative pathways in pulmonary endothelial cells that are mediated through PI3K/Akt and ERK1/2 pathways

  19. Developmental changes in human dopamine neurotransmission: cortical receptors and terminators

    Directory of Open Access Journals (Sweden)

    Rothmond Debora A

    2012-02-01

    Full Text Available Abstract Background Dopamine is integral to cognition, learning and memory, and dysfunctions of the frontal cortical dopamine system have been implicated in several developmental neuropsychiatric disorders. The dorsolateral prefrontal cortex (DLPFC is critical for working memory which does not fully mature until the third decade of life. Few studies have reported on the normal development of the dopamine system in human DLPFC during postnatal life. We assessed pre- and postsynaptic components of the dopamine system including tyrosine hydroxylase, the dopamine receptors (D1, D2 short and D2 long isoforms, D4, D5, catechol-O-methyltransferase, and monoamine oxidase (A and B in the developing human DLPFC (6 weeks -50 years. Results Gene expression was first analysed by microarray and then by quantitative real-time PCR. Protein expression was analysed by western blot. Protein levels for tyrosine hydroxylase peaked during the first year of life (p O-methyltransferase (p = 0.024 were significantly higher in neonates and infants as was catechol-O-methyltransferase protein (32 kDa, p = 0.027. In contrast, dopamine D1 receptor mRNA correlated positively with age (p = 0.002 and dopamine D1 receptor protein expression increased throughout development (p Conclusions We find distinct developmental changes in key components of the dopamine system in DLPFC over postnatal life. Those genes that are highly expressed during the first year of postnatal life may influence and orchestrate the early development of cortical neural circuitry while genes portraying a pattern of increasing expression with age may indicate a role in DLPFC maturation and attainment of adult levels of cognitive function.

  20. Dose-Dependent Effect of Curcumin on Learning and Memory Deficit in Kainate-Epileptic Rats

    Directory of Open Access Journals (Sweden)

    Zahra Kiasalari

    2014-09-01

    Full Text Available Background & objectives : Epileptic seizures accompany disturbances in learning, memory, and cognitive skills. With regard to antiepileptic potential of curcumin and its beneficial effect on memory, the effect of its administration on learning and memory in kainate-epileptic rats was investigated.   Methods: Forty male rats were divided into sham, positive control ( valproate-treated epileptic, epileptic, and two curcumin-treated epileptic groups. Rat model of epilepsy was induced by unilateral intrahippocampal administration of 4 μg of kainate per rat. Rats received intraperitoneal injection of curcumin (50 and 100 mg/kg daily for 1 week before surgery. For evaluation of learning and memory, initial (IL and step-through latencies (STL were determined using passive avoidance test and alternation behavior percentage was obtained according to Y maze test.   Results: Regarding IL, there was no significant difference between the groups. In contrast, STL significantly decreased in curcumin-50-treated epileptic group (p<0.05 (a change from 263.1 to 184.5 s. However, this parameter significantly increased in curcumin-100-treated epileptic group as compared to epileptic group (p<0.01 (a change from 263.1 to 220.3 s. In addition, STL was also significantly higher in valproic acid-treated epileptic group versus epileptic group (p<0.05 (a change from 145.7 to 210.3 s. Alternation percentage was also significantly higher in curcumin-50- and curcumin-100-treated epileptic groups relative to epileptic group (p<0.05 (a change from 60.5 to 77.6 and 80.3%.   Conclusion: Curcumin could dose-dependently enhance the consolidation and recall in epileptic animals and could improve spatial memory in such animals.

  1. A pp32-retinoblastoma protein complex modulates androgen receptor-mediated transcription and associates with components of the splicing machinery

    International Nuclear Information System (INIS)

    Adegbola, Onikepe; Pasternack, Gary R.

    2005-01-01

    We have previously shown pp32 and the retinoblastoma protein interact. pp32 and the retinoblastoma protein are nuclear receptor transcriptional coregulators: the retinoblastoma protein is a coactivator for androgen receptor, the major regulator of prostate cancer growth, while pp32, which is highly expressed in prostate cancer, is a corepressor of the estrogen receptor. We now show pp32 increases androgen receptor-mediated transcription and the retinoblastoma protein modulates this activity. Using affinity purification and mass spectrometry, we identify members of the pp32-retinoblastoma protein complex as PSF and nonO/p54nrb, proteins implicated in coordinate regulation of nuclear receptor-mediated transcription and splicing. We show that the pp32-retinoblastoma protein complex is modulated during TPA-induced K562 differentiation. Present evidence suggests that nuclear receptors assemble multiprotein complexes to coordinately regulate transcription and mRNA processing. Our results suggest that pp32 and the retinoblastoma protein may be part of a multiprotein complex that coordinately regulates nuclear receptor-mediated transcription and mRNA processing

  2. Dopamine D3 receptors mediate the discriminative stimulus effects of quinpirole in free-feeding rats.

    Science.gov (United States)

    Baladi, Michelle G; Newman, Amy H; France, Charles P

    2010-01-01

    The discriminative stimulus effects of dopamine (DA) D3/D2 receptor agonists are thought to be mediated by D2 receptors. To maintain responding, access to food is often restricted, which can alter neurochemical and behavioral effects of drugs acting on DA systems. This study established stimulus control with quinpirole in free-feeding rats and tested the ability of agonists to mimic and antagonists to attenuate the effects of quinpirole. The same antagonists were studied for their ability to attenuate quinpirole-induced yawning and hypothermia. DA receptor agonists apomorphine and lisuride, but not amphetamine and morphine, occasioned responding on the quinpirole lever. The discriminative stimulus effects of quinpirole were attenuated by the D3 receptor-selective antagonist N-{4-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-trans-but-2-enyl}-4-pyridine-2-yl-benzamide HCl (PG01037) and the nonselective D3/D2 receptor antagonist raclopride, but not by the D2 receptor-selective antagonist 3-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]methyl-1H-indole (L-741,626); the potencies of PG01037 and raclopride to antagonize this effect of quinpirole paralleled their potencies to antagonize the ascending limb of the quinpirole yawning dose-response curve (thought to be mediated by D3 receptors). L-741,626 selectively antagonized the descending limb of the quinpirole yawning dose-response curve, and both L-741,626 and raclopride, but not PG01037, antagonized the hypothermic effects of quinpirole (thought to be mediated by D2 receptors). Food restriction (10 g/day/7 days) significantly decreased quinpirole-induced yawning without affecting the quinpirole discrimination. Many discrimination studies on DA receptor agonists use food-restricted rats; together with those studies, the current experiment using free-feeding rats suggests that feeding conditions affecting the behavioral effects of direct-acting DA receptor agonists might also have an impact on the effects of indirect

  3. Killing of intracellular Mycobacterium tuberculosis by receptor-mediated drug delivery

    International Nuclear Information System (INIS)

    Majumdar, S.; Basu, S.K.

    1991-01-01

    p-Aminosalicylic acid (PAS) conjugated to maleylated bovine serum albumin (MBSA) was taken up efficiently through high-affinity MBSA-binding sites on macrophages. Binding of the radiolabeled conjugate to cultured mouse peritoneal macrophages at 4 degrees C was competed for by MBSA but not by PAS. At 37 degrees C, the radiolabeled conjugate was rapidly degraded by the macrophages, leading to release of acid-soluble degradation products in the medium. The drug conjugate was nearly 100 times as effective as free PAS in killing the intracellular mycobacteria in mouse peritoneal macrophages infected in culture with Mycobacterium tuberculosis. The killing of intracellular mycobacteria mediated by the drug conjugate was effectively prevented by simultaneous addition of excess MBSA (100 micrograms/ml) or chloroquine (3 microM) to the medium, whereas these agents did not affect the microbicidal action of free PAS. These results suggest that (i) uptake of the PAS-MBSA conjugate was mediated by cell surface receptors on macrophages which recognize MBSA and (ii) lysosomal hydrolysis of the internalized conjugate resulted in intracellular release of a pharmacologically active form of the drug, which led to selective killing of the M. tuberculosis harbored by mouse macrophages infected in culture. This receptor-mediated modality of delivering drugs to macrophages could contribute to greater therapeutic efficacy and minimization of toxic side effects in the management of tuberculosis and other intracellular mycobacterial infections

  4. Influence of ER leak on resting cytoplasmic Ca2+ and receptor-mediated Ca2+ signalling in human macrophage.

    Science.gov (United States)

    Layhadi, Janice A; Fountain, Samuel J

    2017-06-03

    Mechanisms controlling endoplasmic reticulum (ER) Ca 2+ homeostasis are important regulators of resting cytoplasmic Ca 2+ concentration ([Ca 2+ ] cyto ) and receptor-mediated Ca 2+ signalling. Here we investigate channels responsible for ER Ca 2+ leak in THP-1 macrophage and human primary macrophage. In the absence of extracellular Ca 2+ we employ ionomycin action at the plasma membrane to stimulate ER Ca 2+ leak. Under these conditions ionomycin elevates [Ca 2+ ] cyto revealing a Ca 2+ leak response which is abolished by thapsigargin. IP 3 receptors (Xestospongin C, 2-APB), ryanodine receptors (dantrolene), and translocon (anisomycin) inhibition facilitated ER Ca 2+ leak in model macrophage, with translocon inhibition also reducing resting [Ca 2+ ] cyto . In primary macrophage, translocon inhibition blocks Ca 2+ leak but does not influence resting [Ca 2+ ] cyto . We identify a role for translocon-mediated ER Ca 2+ leak in receptor-mediated Ca 2+ signalling in both model and primary human macrophage, whereby the Ca 2+ response to ADP (P2Y receptor agonist) is augmented following anisomycin treatment. In conclusion, we demonstrate a role of ER Ca 2+ leak via the translocon in controlling resting cytoplasmic Ca 2+ in model macrophage and receptor-mediated Ca 2+ signalling in model macrophage and primary macrophage. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. FBXO22 Protein Is Required for Optimal Synthesis of the N-Methyl-d-Aspartate (NMDA) Receptor Coagonist d-Serine

    DEFF Research Database (Denmark)

    Dikopoltsev, Elena; Foltyn, Veronika N; Zehl, Martin

    2014-01-01

    d-Serine is a physiological activator of NMDA receptors (NMDARs) in the nervous system that mediates several NMDAR-mediated processes ranging from normal neurotransmission to neurodegeneration. d-Serine is synthesized from l-serine by serine racemase (SR), a brain-enriched enzyme. However, little......, SR interacts preferentially with free FBXO22 species. In vivo ubiquitination and SR half-life determination indicate that FBXO22 does not target SR to the proteasome system. FBXO22 primarily affects SR subcellular localization and seems to increase d-serine synthesis by preventing the association...... is known about the regulation of d-serine synthesis. We now demonstrate that the F-box only protein 22 (FBXO22) interacts with SR and is required for optimal d-serine synthesis in cells. Although FBXO22 is classically associated with the ubiquitin system and is recruited to the Skip1-Cul1-F-box E3 complex...

  6. Prostaglandin E2 potentiation of P2X3 receptor mediated currents in dorsal root ganglion neurons

    Directory of Open Access Journals (Sweden)

    Huang Li-Yen

    2007-08-01

    Full Text Available Abstract Prostaglandin E2 (PGE2 is a well-known inflammatory mediator that enhances the excitability of DRG neurons. Homomeric P2X3 and heteromeric P2X2/3 receptors are abundantly expressed in dorsal root ganglia (DRG neurons and participate in the transmission of nociceptive signals. The interaction between PGE2 and P2X3 receptors has not been well delineated. We studied the actions of PGE2 on ATP-activated currents in dissociated DRG neurons under voltage-clamp conditions. PGE2 had no effects on P2X2/3 receptor-mediated responses, but significantly potentiated fast-inactivating ATP currents mediated by homomeric P2X3 receptors. PGE2 exerted its action by activating EP3 receptors. To study the mechanism underlying the action of PGE2, we found that the adenylyl cyclase activator, forskolin and the membrane-permeable cAMP analogue, 8-Br-cAMP increased ATP currents, mimicking the effect of PGE2. In addition, forskolin occluded the enhancement produced by PGE2. The protein kinase A (PKA inhibitors, H89 and PKA-I blocked the PGE2 effect. In contrast, the PKC inhibitor, bisindolymaleimide (Bis did not change the potentiating action of PGE2. We further showed that PGE2 enhanced α,β-meATP-induced allodynia and hyperalgesia and the enhancement was blocked by H89. These observations suggest that PGE2 binds to EP3 receptors, resulting in the activation of cAMP/PKA signaling pathway and leading to an enhancement of P2X3 homomeric receptor-mediated ATP responses in DRG neurons.

  7. Perirhinal Cortex Muscarinic Receptor Blockade Impairs Taste Recognition Memory Formation

    Science.gov (United States)

    Gutierrez, Ranier; De la Cruz, Vanesa; Rodriguez-Ortiz, Carlos J.; Bermudez-Rattoni, Federico

    2004-01-01

    The relevance of perirhinal cortical cholinergic and glutamatergic neurotransmission for taste recognition memory and learned taste aversion was assessed by microinfusions of muscarinic (scopolamine), NMDA (AP-5), and AMPA (NBQX) receptor antagonists. Infusions of scopolamine, but not AP5 or NBQX, prevented the consolidation of taste recognition…

  8. Regulated internalization of NMDA receptors drives PKD1-mediated suppression of the activity of residual cell-surface NMDA receptors.

    Science.gov (United States)

    Fang, Xiao-Qian; Qiao, Haifa; Groveman, Bradley R; Feng, Shuang; Pflueger, Melissa; Xin, Wen-Kuan; Ali, Mohammad K; Lin, Shuang-Xiu; Xu, Jindong; Duclot, Florian; Kabbaj, Mohamed; Wang, Wei; Ding, Xin-Sheng; Santiago-Sim, Teresa; Jiang, Xing-Hong; Salter, Michael W; Yu, Xian-Min

    2015-11-19

    Constitutive and regulated internalization of cell surface proteins has been extensively investigated. The regulated internalization has been characterized as a principal mechanism for removing cell-surface receptors from the plasma membrane, and signaling to downstream targets of receptors. However, so far it is still not known whether the functional properties of remaining (non-internalized) receptor/channels may be regulated by internalization of the same class of receptor/channels. The N-methyl-D-aspartate receptor (NMDAR) is a principal subtype of glutamate-gated ion channel and plays key roles in neuronal plasticity and memory functions. NMDARs are well-known to undergo two types of regulated internalization - homologous and heterologous, which can be induced by high NMDA/glycine and DHPG, respectively. In the present work, we investigated effects of regulated NMDAR internalization on the activity of residual cell-surface NMDARs and neuronal functions. In electrophysiological experiments we discovered that the regulated internalization of NMDARs not only reduced the number of cell surface NMDARs but also caused an inhibition of the activity of remaining (non-internalized) surface NMDARs. In biochemical experiments we identified that this functional inhibition of remaining surface NMDARs was mediated by increased serine phosphorylation of surface NMDARs, resulting from the activation of protein kinase D1 (PKD1). Knockdown of PKD1 did not affect NMDAR internalization but prevented the phosphorylation and inhibition of remaining surface NMDARs and NMDAR-mediated synaptic functions. These data demonstrate a novel concept that regulated internalization of cell surface NMDARs not only reduces the number of NMDARs on the cell surface but also causes an inhibition of the activity of remaining surface NMDARs through intracellular signaling pathway(s). Furthermore, modulating the activity of remaining surface receptors may be an effective approach for treating receptor

  9. Acetylcholine receptors in the human retina

    International Nuclear Information System (INIS)

    Hutchins, J.B.; Hollyfield, J.G.

    1985-01-01

    Evidence for a population of acetylcholine (ACh) receptors in the human retina is presented. The authors have used the irreversible ligand 3 H-propylbenzilylcholine mustard ( 3 H-PrBCM) to label muscarinic receptors. 3 H- or 125 I-alpha-bungarotoxin (alpha-BTx) was used to label putative nicotinic receptors. Muscarinic receptors are apparently present in the inner plexiform layer of the retina. Autoradiographic grain densities are reduced in the presence of saturating concentrations of atropine, quinuclidinyl benzilate or scopolamine; this indicates that 3 H-PrBCM binding is specific for a population of muscarinic receptors in the human retina. Binding sites for radiolabeled alpha-BTx are found predominantly in the inner plexiform layer of the retina. Grain densities are reduced in the presence of d-tubocurarine, indicating that alpha-BTx may bind to a pharmacologically relevant nicotinic ACh receptor. This study provides evidence for cholinergic neurotransmission in the human retina

  10. Glucocorticoid receptor, but not mineralocorticoid receptor, mediates cortisol regulation of epidermal ionocyte development and ion transport in zebrafish (danio rerio.

    Directory of Open Access Journals (Sweden)

    Shelly Abad Cruz

    Full Text Available Cortisol is the major endogenous glucocorticoid (GC both in human and fish, mediated by corticosteroid receptors. Due to the absence of aldosterone production in teleost fish, cortisol is also traditionally accepted to function as mineralocorticoid (MC; but whether it acts through the glucocorticoid receptor (GR or the mineralocorticoid receptor (MR remains a subject of debate. Here, we used loss-of-function and rescue assays to determine whether cortisol affects zebrafish epidermal ionocyte development and function via the GR and/or the MR. GR knockdown morphants displayed a significant decrease in the major ionocytes, namely Na(+-K(+-ATPase-rich cells (NaRCs and H(+-ATPase-rich cells (HRCs, as well as other cells, including epidermal stem cells (ESCs, keratinocytes, and mucus cells; conversely, cell numbers were unaffected in MR knockdown morphants. In agreement, GR morphants, but not MR morphants, exhibited decreased NaRC-mediated Ca(2+ uptake and HRC-mediated H(+ secretion. Rescue via GR capped mRNA injection or exogenous cortisol incubation normalized the number of epidermal ionocytes in GR morphants. We also provide evidence for GR localization in epidermal cells. At the transcript level, GR mRNA is ubiquitously expressed in gill sections and present in both NaRCs and HRCs, supporting the knockdown and functional assay results in embryo. Altogether, we have provided solid molecular evidence that GR is indeed present on ionocytes, where it mediates the effects of cortisol on ionocyte development and function. Hence, cortisol-GR axis performs the roles of both GC and MC in zebrafish skin and gills.

  11. Positron emission tomography studies of brain receptors

    International Nuclear Information System (INIS)

    Maziere, B.; Maziere, M.

    1991-01-01

    Probing the regional distribution and affinity of receptors in the brain, in vivo, in human and non human primates has become possible with the use of selective ligands labelled with positron emitting radionuclides and positron emission tomography (PET). After describing the techniques used in positron emission tomography to characterize a ligand receptor binding and discussing the choice of the label and the limitations and complexities of the in vivo approach, the results obtained in the PET studies of various neurotransmission systems: dopaminergic, opiate, benzodiazepine, serotonin and cholinergic systems are reviewed

  12. Extracellular collagenases and the endocytic receptor, urokinase plasminogen activator receptor-associated protein/Endo180, cooperate in fibroblast-mediated collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Engelholm, Lars H; Ingvarsen, Signe

    2007-01-01

    in these events. A recently discovered turnover route with importance for tumor growth involves intracellular collagen degradation and is governed by the collagen receptor, urokinase plasminogen activator receptor-associated protein (uPARAP or Endo180). The interplay between this mechanism and extracellular...... collagenolysis is not known. In this report, we demonstrate the existence of a new, composite collagen breakdown pathway. Thus, fibroblast-mediated collagen degradation proceeds preferentially as a sequential mechanism in which extracellular collagenolysis is followed by uPARAP/Endo180-mediated endocytosis......The collagens of the extracellular matrix are the most abundant structural proteins in the mammalian body. In tissue remodeling and in the invasive growth of malignant tumors, collagens constitute an important barrier, and consequently, the turnover of collagen is a rate-limiting process...

  13. Receptor-mediated targeting of 67Ga-Deferoxamine-Folate to folate-receptor-positive human kb tumor xenografts

    International Nuclear Information System (INIS)

    Mathias, Carla J.; Wang, Susan; Low, Philip S.; Waters, David J.; Green, Mark A.

    1999-01-01

    The radiochemical synthesis and stability of 67 Ga-deferoxamine-folate ([ 67 Ga]Ga-DF-Folate) were examined as a function of DF-Folate concentration. Optimal labeling occurred at DF-Folate concentrations ≥2.5 μg/mL. To define the possible biological significance of variations in product formulation, the biodistribution of [ 67 Ga]Ga-DF-Folate was examined as a function of administered deferoxamine-folate dose in an athymic mouse KB tumor model. The folate-receptor-positive KB tumors were found to concentrate the 67 Ga radiolabel in a dose-dependent fashion, consistent with saturable involvement of the folate receptor in mediating tumor accumulation of the radiopharmaceutical

  14. Med1 subunit of the mediator complex in nuclear receptor-regulated energy metabolism, liver regeneration, and hepatocarcinogenesis.

    Science.gov (United States)

    Jia, Yuzhi; Viswakarma, Navin; Reddy, Janardan K

    2014-01-01

    Several nuclear receptors regulate diverse metabolic functions that impact on critical biological processes, such as development, differentiation, cellular regeneration, and neoplastic conversion. In the liver, some members of the nuclear receptor family, such as peroxisome proliferator-activated receptors (PPARs), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), liver X receptor (LXR), pregnane X receptor (PXR), glucocorticoid receptor (GR), and others, regulate energy homeostasis, the formation and excretion of bile acids, and detoxification of xenobiotics. Excess energy burning resulting from increases in fatty acid oxidation systems in liver generates reactive oxygen species, and the resulting oxidative damage influences liver regeneration and liver tumor development. These nuclear receptors are important sensors of exogenous activators as well as receptor-specific endogenous ligands. In this regard, gene knockout mouse models revealed that some lipid-metabolizing enzymes generate PPARα-activating ligands, while others such as ACOX1 (fatty acyl-CoA oxidase1) inactivate these endogenous PPARα activators. In the absence of ACOX1, the unmetabolized ACOX1 substrates cause sustained activation of PPARα, and the resulting increase in energy burning leads to hepatocarcinogenesis. Ligand-activated nuclear receptors recruit the multisubunit Mediator complex for RNA polymerase II-dependent gene transcription. Evidence indicates that the Med1 subunit of the Mediator is essential for PPARα, PPARγ, CAR, and GR signaling in liver. Med1 null hepatocytes fail to respond to PPARα activators in that these cells do not show induction of peroxisome proliferation and increases in fatty acid oxidation enzymes. Med1-deficient hepatocytes show no increase in cell proliferation and do not give rise to liver tumors. Identification of nuclear receptor-specific coactivators and Mediator subunits should further our understanding of the complexities of metabolic

  15. Receptor-Mediated Drug Delivery to Macrophages in Chemotherapy of Leishmaniasis

    Science.gov (United States)

    Mukhopadhyay, Amitabha; Chaudhuri, Gautam; Arora, Sunil K.; Sehgal, Shobha; Basu, Sandip K.

    1989-05-01

    Methotrexate coupled to maleylated bovine serum albumin was taken up efficiently through the ``scavenger'' receptors present on macrophages and led to selective killing of intracellular Leishmania mexicana amazonensis amastigotes in cultured hamster peritoneal macrophages. The drug conjugate was nearly 100 times as effective as free methotrexate in eliminating the intracellular parasites. Furthermore, in a model of experimental cutaneous leishmaniasis in hamsters, the drug conjugate brought about more than 90% reduction in the size of footpad lesions within 11 days. In contrast, the free drug at a similar concentration did not significantly affect lesion size. These studies demonstrate the potential of receptor-mediated drug delivery in the therapy of macrophage-associated diseases.

  16. Synaptic impairment in layer 1 of the prefrontal cortex induced by repeated stress during adolescence is reversed in adulthood

    Directory of Open Access Journals (Sweden)

    Ignacio eNegron-Oyarzo

    2015-11-01

    Full Text Available Chronic stress is a risk factor for the development of psychiatric disorders, some of which involve dysfunction of the prefrontal cortex (PFC. There is a higher prevalence of these chronic stress-related psychiatric disorders during adolescence, when the PFC has not yet fully matured. In the present work we studied the effect of repeated stress during adolescence on synaptic function in the PFC in adolescence and adulthood. To this end, adolescent Sprague-Dawley rats were subjected to seven consecutive days of restraint stress. Afterward, both synaptic transmission and short- and long-term synaptic plasticity were evaluated in layer 1 of medial-PFC (mPFC slices from adolescent and adult rats. We found that repeated stress significantly reduced the amplitude of evoked field excitatory postsynaptic potential (fEPSP in the mPFC. Isolation of excitatory transmission reveled that lower-amplitude fEPSPs were associated with a reduction in AMPA/kainate receptor-mediated transmission. We also found that repeated stress significantly decreased long-term depression (LTD. Interestingly, AMPA/kainate receptor-mediated transmission and LTD were recovered in adult animals that experienced a three-week stress-free recovery period. The data indicates that the changes in synaptic transmission and plasticity in the mPFC induced by repeated stress during adolescence are reversed in adulthood after a stress-free period.

  17. Role of the hinge region of glucocorticoid receptor for HEXIM1-mediated transcriptional repression

    International Nuclear Information System (INIS)

    Yoshikawa, Noritada; Shimizu, Noriaki; Sano, Motoaki; Ohnuma, Kei; Iwata, Satoshi; Hosono, Osamu; Fukuda, Keiichi; Morimoto, Chikao

    2008-01-01

    We previously reported that HEXIM1 (hexamethylene bisacetamide-inducible protein 1), which suppresses transcription elongation via sequestration of positive transcription elongation factor b (P-TEFb) using 7SK RNA as a scaffold, directly associates with glucocorticoid receptor (GR) to suppress glucocorticoid-inducible gene activation. Here, we revealed that the hinge region of GR is essential for its interaction with HEXIM1, and that oxosteroid receptors including GR show sequence homology in their hinge region and interact with HEXIM1, whereas the other members of nuclear receptors do not. We also showed that HEXIM1 suppresses GR-mediated transcription in two ways: sequestration of P-TEFb by HEXIM1 and direct interaction between GR and HEXIM1. In contrast, peroxisome proliferator-activated receptor γ-dependent gene expression is negatively modulated by HEXIM1 solely via sequestration of P-TEFb. We, therefore, conclude that HEXIM1 may act as a gene-selective transcriptional regulator via direct interaction with certain transcriptional regulators including GR and contribute to fine-tuning of, for example, glucocorticoid-mediated biological responses

  18. Endoglin-mediated suppression of prostate cancer invasion is regulated by activin and bone morphogenetic protein type II receptors.

    Directory of Open Access Journals (Sweden)

    Michael J Breen

    Full Text Available Mortality from prostate cancer (PCa is due to the formation of metastatic disease. Understanding how that process is regulated is therefore critical. We previously demonstrated that endoglin, a type III transforming growth factor β (TGFβ superfamily receptor, suppresses human PCa cell invasion and metastasis. Endoglin-mediated suppression of invasion was also shown by us to be dependent upon the type I TGFβ receptor, activin receptor-like kinase 2 (ALK2, and the downstream effector, Smad1. In this study we demonstrate for the first time that two type II TGFβ receptors are required for endoglin-mediated suppression of invasion: activin A receptor type IIA (ActRIIA and bone morphogenetic protein receptor type II (BMPRII. Downstream signaling through these receptors is predominantly mediated by Smad1. ActRIIA stimulates Smad1 activation in a kinase-dependent manner, and this is required for suppression of invasion. In contrast BMPRII regulates Smad1 in a biphasic manner, promoting Smad1 signaling through its kinase domain but suppressing it through its cytoplasmic tail. BMPRII's Smad1-regulatory effects are dependent upon its expression level. Further, its ability to suppress invasion is independent of either kinase function or tail domain. We demonstrate that ActRIIA and BMPRII physically interact, and that each also interacts with endoglin. The current findings demonstrate that both BMPRII and ActRIIA are necessary for endoglin-mediated suppression of human PCa cell invasion, that they have differential effects on Smad1 signaling, that they make separate contributions to regulation of invasion, and that they functionally and physically interact.

  19. DHA involvement in neurotransmission process

    Directory of Open Access Journals (Sweden)

    Vancassel Sylvie

    2007-05-01

    Full Text Available The very high enrichment of the nervous system in the polyunsaturated fatty acids, arachidonic (AA, 20: 4n-6 and docosahexaenoic acids (DHA, 22: 6n-3, is dependant of the dietary availability of their respective precursors, linoleic (18: 2n-6 and_-linolenic acids (18: 3n-3. Inadequate amounts of DHA in brain membranes have been linked to a wide variety of abnormalities ranging from visual acuity and learning irregularities, to psychopathologies. However, the molecular mechanisms involved remain unknown. Several years ago, we hypothesized that a modification of DHA contents of neuronal membranes by dietary modulation could change the neurotransmission function and then underlie inappropriate behavioural response. We showed that, in parallel to a severe loss of brain DHA concomitant to a compensatory substitution by 22:5n-6, the dietary lack of α-linolenic acid during development induced important changes in the release of neurotransmitters (dopamine, serotonin, acetylcholine in cerebral areas specifically involved in learning, memory and reward processes. Data suggested alteration of presynaptic storage process and dysregulations of reciprocal functional interactions between monoaminergic and cholinergic pathways. Moreover, we showed that recovery of these neurochemical changes was possible when the deficient diet was switched to a diet balanced in n-3 and n-6 PUFA before weaning. The next step is to understand the mechanism involved. Particularly, we focus on the study of the metabolic cooperation between the endothelial cell, the astrocyte and the neuron which regulate synaptic transmission.These works could contribute to the understanding of the link between some neuropsychiatric disorders and the metabolism of n-3 PUFA, through their action on neurotransmission.

  20. Neurotensin enhances glutamatergic EPSCs in VTA neurons by acting on different neurotensin receptors.

    Science.gov (United States)

    Bose, Poulomee; Rompré, Pierre-Paul; Warren, Richard A

    2015-11-01

    Neurotensin (NT) is an endogenous neuropeptide that modulates dopamine and glutamate neurotransmission in several limbic regions innervated by neurons located in the ventral tegmental area (VTA). While several studies showed that NT exerted a direct modulation on VTA dopamine neurons less is known about its role in the modulation of glutamatergic neurotransmission in this region. The present study was aimed at characterising the effects of NT on glutamate-mediated responses in different populations of VTA neurons. Using whole cell patch clamp recording technique in horizontal rat brain slices, we measured the amplitude of glutamatergic excitatory post-synaptic currents (EPSCs) evoked by electrical stimulation of VTA afferents before and after application of different concentrations of NT1-13 or its C-terminal fragment, NT8-13. Neurons were classified as either Ih(+) or Ih(-) based on the presence or absence of a hyperpolarisation activated cationic current (Ih). We found that NT1-13 and NT8-13 produced comparable concentration dependent increase in the amplitude of EPSCs in both Ih(+) and Ih(-) neurons. In Ih(+) neurons, the enhancement effect of NT8-13 was blocked by both antagonists, while in Ih(-) neurons it was blocked by the NTS1/NTS2 antagonist, SR142948A, but not the preferred NTS1 antagonist, SR48692. In as much as Ih(-) neurons are non-dopaminergic neurons and Ih(+) neurons represent both dopamine and non-dopamine neurons, we can conclude that NT enhances glutamatergic mediated responses in dopamine, and in a subset of non-dopamine, neurons by acting respectively on NTS1 and an NT receptor other than NTS1. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Effects of sarcosine and N, N-dimethylglycine on NMDA receptor-mediated excitatory field potentials.

    Science.gov (United States)

    Lee, Mei-Yi; Lin, Yi-Ruu; Tu, Yi-Shu; Tseng, Yufeng Jane; Chan, Ming-Huan; Chen, Hwei-Hsien

    2017-02-28

    Sarcosine, a glycine transporter type 1 inhibitor and an N-methyl-D-aspartate (NMDA) receptor co-agonist at the glycine binding site, potentiates NMDA receptor function. Structurally similar to sarcosine, N,N-dimethylglycine (DMG) is also N-methyl glycine-derivative amino acid and commonly used as a dietary supplement. The present study compared the effects of sarcosine and DMG on NMDA receptor-mediated excitatory field potentials (EFPs) in mouse medial prefrontal cortex brain slices using a multi-electrode array system. Glycine, sarcosine and DMG alone did not alter the NMDA receptor-mediated EFPs, but in combination with glutamate, glycine and its N-methyl derivatives significantly increased the frequency and amplitude of EFPs. The enhancing effects of glycine analogs in combination with glutamate on EFPs were remarkably reduced by the glycine binding site antagonist 7-chlorokynurenate (7-CK). However, DMG, but not sarcosine, reduced the frequency and amplitude of EFPs elicited by co-application of glutamate plus glycine. D-cycloserine, a partial agonist at the glycine binding site on NMDA receptors, affected EFPs in a similar manner to DMG. Furthermore, DMG, but not sarcosine, reduced the frequencies and amplitudes of EFPs elicited by glutamate plus D-serine, another endogenous ligand for glycine binding site. These findings suggest that sarcosine acts as a full agonist, yet DMG is a partial agonist at glycine binding site of NMDA receptors. The molecular docking analysis indicated that the interactions of glycine, sarcosine, and DMG to NMDA receptors are highly similar, supporting that the glycine binding site of NMDA receptors is a critical target site for sarcosine and DMG.

  2. Nicotinic and muscarinic cholinergic receptors are recruited by acetylcholine-mediated neurotransmission within the locus coeruleus during the organisation of post-ictal antinociception.

    Science.gov (United States)

    de Oliveira, Rithiele Cristina; de Oliveira, Ricardo; Biagioni, Audrey Franceschi; Falconi-Sobrinho, Luiz Luciano; Dos Anjos-Garcia, Tayllon; Coimbra, Norberto Cysne

    2016-10-01

    Post-ictal antinociception is characterised by an increase in the nociceptive threshold that accompanies tonic and tonic-clonic seizures (TCS). The locus coeruleus (LC) receives profuse cholinergic inputs from the pedunculopontine tegmental nucleus. Different concentrations (1μg, 3μg and 5μg/0.2μL) of the muscarinic cholinergic receptor antagonist atropine and the nicotinic cholinergic receptor antagonist mecamylamine were microinjected into the LC of Wistar rats to investigate the role of cholinergic mechanisms in the severity of TCS and the post-ictal antinociceptive response. Five minutes later, TCS were induced by systemic administration of pentylenetetrazole (PTZ) (64mg/kg). Seizures were recorded inside the open field apparatus for an average of 10min. Immediately after seizures, the nociceptive threshold was recorded for 130min using the tail-flick test. Pre-treatment of the LC with 1μg, 3μg and 5μg/0.2μL concentrations of both atropine and mecamylamine did not cause a significant effect on seizure severity. However, the same treatments decreased the post-ictal antinociceptive phenomenon. In addition, mecamylamine caused an earlier decrease in the post-ictal antinociception compared to atropine. These results suggest that muscarinic and mainly nicotinic cholinergic receptors of the LC are recruited to organise tonic-clonic seizure-induced antinociception. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Endogenous plasma estradiol in healthy men is positively correlated with cerebral cortical serotonin 2A receptor binding

    DEFF Research Database (Denmark)

    Frokjaer, Vibe G.; Erritzoe, David; Juul, Anders

    2010-01-01

    the effect of plasma sex hormone levels on neocortical 5-HT2A receptor binding as imaged with [18F]altanserin PET. The effect of endogenous sex-hormone levels was evaluated by multiple linear regression analysis. Results: Mean neocortical 5-HT2A receptor binding was positively correlated with estradiol (p......Background: Sex-hormones influence brain function and are likely to play a role in the gender predisposition to mood and anxiety disorders. Acute fluctuations of sex-hormone levels including hormonal replacement therapy appear to affect serotonergic neurotransmission, but it is unknown if baseline...... levels affect serotonergic neurotransmission. This study was undertaken to examine if baseline levels of endogenous sex hormones are associated with cerebral serotonin 2A (5-HT2A) receptor binding in men. Methods: In a group of 72 healthy men (mean age 37.5 years ±17.4 SD, range 19.6–81.7) we studied...

  4. Receptor visualization and the atomic bomb. A historical account of the development of the chemical neuroanatomy of receptors for neurotransmitters and drugs during the Cold War.

    Science.gov (United States)

    Palacios, J M; Mengod, G

    2018-03-01

    This is a historical account of how receptors for neurotransmitters and drugs got to be seen at the regional, cellular, and subcellular levels in brain, in the years going from the end of the World War II until the collapse of the Soviet Union, the Cold War (1945-1991). The realization in the US of the problem of mental health care, as a consequence of the results of medical evaluation for military service during the war, let the US Government to act creating among other things the National Institute for Mental Health (NIMH). Coincident with that, new drug treatments for these disorders were introduced. War science also created an important number of tools and instruments, such as the radioisotopes, that played a significant role in the development of our story. The scientific context was marked by the development of Biochemistry, Molecular Biology and the introduction in the early 80's of the DNA recombinant technologies. The concepts of chemical neurotransmission in the brain and of receptors for drugs and transmitters, although proposed before the war, where not generally accepted. Neurotransmitters were identified and the mechanisms of biosynthesis, storage, release and termination of action by mechanisms such as reuptake, elucidated. Furthermore, the synapse was seen with the electron microscope and more important for our account, neurons and their processes visualized in the brain first by fluorescence histochemistry, then using radioisotopes and autoradiography, and later by immunohistochemistry (IHC), originating the Chemical Neuroanatomy. The concept of chemical neurotransmission evolved from the amines, expanded to excitatory and inhibitory amino acids, then to neuropeptides and finally to gases and other "atypical" neurotransmitters. In addition, coexpression of more than one transmitter in a neuron, changed the initial ideas of neurotransmission. The concept of receptors for these and other messengers underwent a significant evolution from an abstract

  5. Mannose Receptor Mediates the Immune Response to Ganoderma atrum Polysaccharides in Macrophages.

    Science.gov (United States)

    Li, Wen-Juan; Tang, Xiao-Fang; Shuai, Xiao-Xue; Jiang, Cheng-Jia; Liu, Xiang; Wang, Le-Feng; Yao, Yu-Fei; Nie, Shao-Ping; Xie, Ming-Yong

    2017-01-18

    The ability of mannose receptor (MR) to recognize the carbohydrate structures is well-established. Here, we reported that MR was crucial for the immune response to a Ganoderma atrum polysaccharide (PSG-1), as evidenced by elevation of MR in association with increase of phagocytosis and concentrations of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in normal macrophages. Elevation of MR triggered by PSG-1 also led to control lipopolysaccharide (LPS)-triggered inflammatory response via the increase of interleukin-10 (IL-10) and inhibition of phagocytosis and IL-1β. Anti-MR antibody partly attenuated PSG-1-mediated anti-inflammatory responses, while it could not affect TNF-α secretion, suggesting that another receptor was involved in PSG-1-triggered immunomodulatory effects. MR and toll-like receptor (TLR)4 coordinated the influences on the TLR4-mediated signaling cascade by the nuclear factor-κB (NF-κB) pathway in LPS-stimulated macrophages subjected to PSG-1. Collectively, immune response to PSG-1 required recognition by MR in macrophages. The NF-κB pathway served as a central role for the coordination of MR and TLR4 to elicit immune response to PSG-1.

  6. Optical modulation of neurotransmission using calcium photocurrents through the ion channel LiGluR

    Directory of Open Access Journals (Sweden)

    Mercè eIzquierdo-Serra

    2013-03-01

    Full Text Available A wide range of light-activated molecules (photoswitches and phototriggers have been used to the study of computational properties of an isolated neuron by acting pre and postsynaptically. However, new tools are being pursued to elicit a presynaptic calcium influx that triggers the release of neurotransmitters, most of them based in calcium-permeable Channelrhodopsin-2 mutants. Here we describe a method to control exocytosis of synaptic vesicles through the use of a light-gated glutamate receptor (LiGluR, which has recently been demonstrated that supports secretion by means of calcium influx in chromaffin cells. Expression of LiGluR in hippocampal neurons enables reversible control of neurotransmission with light, and allows modulating the firing rate of the postsynaptic neuron with the wavelength of illumination. This method may be useful for the determination of the complex transfer function of individual synapses.

  7. Estrogen receptormediates the detrimental effects of neonatal diethylstilbestrol (DES) exposure in the murine reproductive tract

    International Nuclear Information System (INIS)

    Couse, John F.; Korach, Kenneth S.

    2004-01-01

    It is generally believed that estrogen receptor-dependent and -independent pathways are involved in mediating the developmental effects of the synthetic estrogen, diethylstilbestrol (DES). However, the precise role and extent to which each pathway contributes to the resulting pathologies remains unknown. We have employed the estrogen receptor knockout (ERKO) mice, which lack either estrogen receptor-α (αERKO or estrogen receptor-β (βERKO), to gain insight into the contribution of each ER-dependent pathway in mediating the effects of neonatal DES exposure in the female and male reproductive tract tissues of the mouse. Estrogen receptor-α female mice exhibited complete resistance to the chronic effects of neonatal DES exposure that were obvious in exposed wild-type animals, including atrophy and epithelial squamous metaplasia in the uterus; proliferative lesions of the oviduct; and persistent cornification of the vaginal epithelium. DES-mediated reduction in uterine Hoxa10, Hoxa11 and Wnt7a expression that occurs wild-type females during the time of exposure was also absent in αERKO females. In the male, αERKO mice exhibited complete resistance to the chronic effects of neonatal DES exposure on the prostate, including decreased androgen receptor levels, epithelial hyperplasia, and increased basal cell proliferation. Although ERβ is highly expressed in the prostate epithelium, DES-exposed βERKO males exhibited all of the effects of neonatal DES exposure that were observed in similarly exposed wild-type males. Therefore, the lack of DES-effects on gene expression and tissue differentiation in the αERKO uterus and prostate provides unequivocal evidence of an obligatory role for ERα in mediating the detrimental actions of neonatal DES exposure in the murine reproductive tract

  8. The essential role of G protein-coupled receptor (GPCR) signaling in regulating T cell immunity.

    Science.gov (United States)

    Wang, Dashan

    2018-06-01

    The aim of this paper is to clarify the critical role of GPCR signaling in T cell immunity. The G protein-coupled receptors (GPCRs) are the most common targets in current pharmaceutical industry, and represent the largest and most versatile family of cell surface communicating molecules. GPCRs can be activated by a diverse array of ligands including neurotransmitters, chemokines as well as sensory stimuli. Therefore, GPCRs are involved in many key cellular and physiological processes, such as sense of light, taste and smell, neurotransmission, metabolism, endocrine and exocrine secretion. In recent years, GPCRs have been found to play an important role in immune system. T cell is an important type of immune cell, which plays a central role in cell-mediated immunity. A variety of GPCRs and their signaling mediators (RGS proteins, GRKs and β-arrestin) have been found to express in T cells and involved T cell-mediated immunity. We will summarize the role of GPCR signaling and their regulatory molecules in T cell activation, homeostasis and function in this article. GPCR signaling plays an important role in T cell activation, homeostasis and function. GPCR signaling is critical in regulating T cell immunity.

  9. NMDA Receptor-Dependent Synaptic Activity in Dorsal Motor Nucleus of Vagus Mediates the Enhancement of Gastric Motility by Stimulating ST36

    Directory of Open Access Journals (Sweden)

    Xinyan Gao

    2012-01-01

    Full Text Available Previous studies have demonstrated the efficacy of electroacupuncture at ST36 for patients with gastrointestinal motility disorders. While several lines of evidence suggest that the effect may involve vagal reflex, the precise molecular mechanism underlying this process still remains unclear. Here we report that the intragastric pressure increase induced by low frequency electric stimulation at ST36 was blocked by AP-5, an antagonist of N-methyl-D-aspartate receptors (NMDARs. Indeed, stimulating ST36 enhanced NMDAR-mediated, but not 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-ylpropanoic-acid-(AMPA- receptor-(AMPAR- mediated synaptic transmission in gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV. We also identified that suppression of presynaptic μ-opioid receptors may contribute to upregulation of NMDAR-mediated synaptic transmission induced by electroacupuncture at ST36. Furthermore, we determined that the glutamate-receptor-2a-(NR2A- containing NMDARs are essential for NMDAR-mediated enhancement of gastric motility caused by stimulating ST36. Taken together, our results reveal an important role of NMDA receptors in mediating enhancement of gastric motility induced by stimulating ST36.

  10. Alpha-Adrenoceptor Antagonists Improve Memory by Activating -methyl-D-Aspartate-Induced Ion Currents in the Rat Hippocampus

    Directory of Open Access Journals (Sweden)

    Chang Hee Kim

    2015-12-01

    Full Text Available Purpose: Alpha1 (α1-adrenoceptor antagonists are widely used to treat lower urinary tract symptoms. These drugs not only act on peripheral tissues, but also cross the blood-brain barrier and affect the central nervous system. Therefore, α1-adrenoceptor antagonists may enhance brain functions. In the present study, we investigated the effects of tamsulosin, an α1-adrenoceptor antagonist, on short-term memory, as well as spatial learning and memory, in rats. Methods: The step-down avoidance test was used to evaluate short-term memory, and an eight-arm radial maze test was used to evaluate spatial learning and memory. TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling staining was performed in order to evaluate the effect of tamsulosin on apoptosis in the hippocampal dentate gyrus. Patch clamp recordings were used to evaluate the effect of tamsulosin on ionotropic glutamate receptors, such as N-methyl-D-aspartate (NMDA, amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA, and kainate receptors, in hippocampal CA1 neurons. Results: Tamsulosin treatment improved short-term memory, as well as spatial learning and memory, without altering apoptosis. The amplitudes of NMDA-induced ion currents were dose-dependently increased by tamsulosin. However, the amplitudes of AMPA- and kainate-induced ion currents were not affected by tamsulosin. Conclusions: Tamsulosin enhanced memory function by activating NMDA receptor-mediated ion currents in the hippocampus without initiating apoptosis. The present study suggests the possibility of using tamsulosin to enhance memory under normal conditions, in addition to its use in treating overactive bladder.

  11. Platelet alpha-2 adrenergic receptor-mediated phosphoinositide responses in endogenous depression

    International Nuclear Information System (INIS)

    Mori, Hideki; Koyama, Tsukasa; Yamashita, Itaru

    1991-01-01

    We have previously indicated that epinephrine stimulates phosphoinositide (PI) hydrolysis by activating alpha-2 adrenergic receptors in human platelets. This method involves the measurement of the accumulation of [ 3 H]-inositol-1-phosphate (IP-1) as an index of Pl hydrolysis; lithium is added to inhibit the metabolism of IP-1, thus giving an enhanced signal. In the present study, we assessed the platelet alpha-2 adrenergic receptor-mediated PI responses in samples from 15 unmedicated patients with endogenous depression and 15 age- and sex-matched control subjects. The responses to epinephrine in the depressed patients were significantly higher than those of the controls, whereas the basal values did not differ significantly. These results support the hypothesis that platelet alpha-2 adrenergic receptors may be supersensitive in patients with endogenous depression

  12. The orphan receptor ALK7 and the Activin receptor ALK4 mediate signaling by Nodal proteins during vertebrate development

    Science.gov (United States)

    Reissmann, Eva; Jörnvall, Henrik; Blokzijl, Andries; Andersson, Olov; Chang, Chenbei; Minchiotti, Gabriella; Persico, M. Graziella; Ibáñez, Carlos F.; Brivanlou, Ali H.

    2001-01-01

    Nodal proteins have crucial roles in mesendoderm formation and left–right patterning during vertebrate development. The molecular mechanisms of signal transduction by Nodal and related ligands, however, are not fully understood. In this paper, we present biochemical and functional evidence that the orphan type I serine/threonine kinase receptor ALK7 acts as a receptor for mouse Nodal and Xenopus Nodal-related 1 (Xnr1). Receptor reconstitution experiments indicate that ALK7 collaborates with ActRIIB to confer responsiveness to Xnr1 and Nodal. Both receptors can independently bind Xnr1. In addition, Cripto, an extracellular protein genetically implicated in Nodal signaling, can independently interact with both Xnr1 and ALK7, and its expression greatly enhances the ability of ALK7 and ActRIIB to respond to Nodal ligands. The Activin receptor ALK4 is also able to mediate Nodal signaling but only in the presence of Cripto, with which it can also interact directly. A constitutively activated form of ALK7 mimics the mesendoderm-inducing activity of Xnr1 in Xenopus embryos, whereas a dominant-negative ALK7 specifically blocks the activities of Nodal and Xnr1 but has little effect on other related ligands. In contrast, a dominant-negative ALK4 blocks all mesoderm-inducing ligands tested, including Nodal, Xnr1, Xnr2, Xnr4, and Activin. In agreement with a role in Nodal signaling, ALK7 mRNA is localized to the ectodermal and organizer regions of Xenopus gastrula embryos and is expressed during early stages of mouse embryonic development. Therefore, our results indicate that both ALK4 and ALK7 can mediate signal transduction by Nodal proteins, although ALK7 appears to be a receptor more specifically dedicated to Nodal signaling. PMID:11485994

  13. β-Nicotinamide adenine dinucleotide acts at prejunctional adenosine A1 receptors to suppress inhibitory musculomotor neurotransmission in guinea pig colon and human jejunum

    Science.gov (United States)

    Wang, Guo-Du; Wang, Xi-Yu; Liu, Sumei; Xia, Yun; Zou, Fei; Qu, Meihua; Needleman, Bradley J.; Mikami, Dean J.

    2015-01-01

    Intracellular microelectrodes were used to record neurogenic inhibitory junction potentials in the intestinal circular muscle coat. Electrical field stimulation was used to stimulate intramural neurons and evoke contraction of the smooth musculature. Exposure to β-nicotinamide adenine dinucleotide (β-NAD) did not alter smooth muscle membrane potential in guinea pig colon or human jejunum. ATP, ADP, β-NAD, and adenosine, as well as the purinergic P2Y1 receptor antagonists MRS 2179 and MRS 2500 and the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine, each suppressed inhibitory junction potentials in guinea pig and human preparations. β-NAD suppressed contractile force of twitch-like contractions evoked by electrical field stimulation in guinea pig and human preparations. P2Y1 receptor antagonists did not reverse this action. Stimulation of adenosine A1 receptors with 2-chloro-N6-cyclopentyladenosine suppressed the force of twitch contractions evoked by electrical field stimulation in like manner to the action of β-NAD. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine suppressed the inhibitory action of β-NAD on the force of electrically evoked contractions. The results do not support an inhibitory neurotransmitter role for β-NAD at intestinal neuromuscular junctions. The data suggest that β-NAD is a ligand for the adenosine A1 receptor subtype expressed by neurons in the enteric nervous system. The influence of β-NAD on intestinal motility emerges from adenosine A1 receptor-mediated suppression of neurotransmitter release at inhibitory neuromuscular junctions. PMID:25813057

  14. Impacts of stress and sex hormones on dopamine neurotransmission in the adolescent brain.

    Science.gov (United States)

    Sinclair, Duncan; Purves-Tyson, Tertia D; Allen, Katherine M; Weickert, Cynthia Shannon

    2014-04-01

    Adolescence is a developmental period of complex neurobiological change and heightened vulnerability to psychiatric illness. As a result, understanding factors such as sex and stress hormones which drive brain changes in adolescence, and how these factors may influence key neurotransmitter systems implicated in psychiatric illness, is paramount. In this review, we outline the impact of sex and stress hormones at adolescence on dopamine neurotransmission, a signaling pathway which is critical to healthy brain function and has been implicated in psychiatric illness. We review normative developmental changes in dopamine, sex hormone, and stress hormone signaling during adolescence and throughout postnatal life, then highlight the interaction of sex and stress hormones and review their impacts on dopamine neurotransmission in the adolescent brain. Adolescence is a time of increased responsiveness to sex and stress hormones, during which the maturing dopaminergic neural circuitry is profoundly influenced by these factors. Testosterone, estrogen, and glucocorticoids interact with each other and have distinct, brain region-specific impacts on dopamine neurotransmission in the adolescent brain, shaping brain maturation and cognitive function in adolescence and adulthood. Some effects of stress/sex hormones on cortical and subcortical dopamine parameters bear similarities with dopaminergic abnormalities seen in schizophrenia, suggesting a possible role for sex/stress hormones at adolescence in influencing risk for psychiatric illness via modulation of dopamine neurotransmission. Stress and sex hormones may prove useful targets in future strategies for modifying risk for psychiatric illness.

  15. Proteinase-activated receptors - mediators of early and delayed normal tissue radiation responses

    International Nuclear Information System (INIS)

    Hauer-Jensen, M.

    2003-01-01

    Proteinase-activated receptors (PARs) are G-protein coupled receptors that are activated by proteolytic exposure of a receptor-tethered ligand. The discovery of this receptor family represents one of the most intriguing recent developments in signal transduction. PARs are involved in the regulation of many normal and pathophysiological processes, notably inflammatory and fibroproliferative responses to injury. Preclinical studies performed in our laboratory suggest that proteinase-activated receptor-1 (PAR-1) plays a critical role in the mechanism of chronicity of radiation fibrosis, while proteinase-activated receptor-2 (PAR-2) may mediate important fibroproliferative responses in irradiated intestine. Specifically, activation of PAR-1 by thrombin, and PAR-2 by pancreatic trypsin and mast cell proteinases, appears to be involved in acute radiation-induced inflammation, as well as in subsequent extracellular matrix deposition, leading to the development of intestinal wall fibrosis and clinical complications. Pharmacological modulators of PAR-1 or PAR-2 expression or activation would be potentially useful as preventive or therapeutic agents in patients who receive radiation therapy, especially if blockade could be targeted to specific tissues or cellular compartments

  16. Sympatholytic properties of several AT(1)-receptor antagonists in the isolated rabbit thoracic aorta

    NARCIS (Netherlands)

    Nap, Alexander; Balt, Jippe C.; Pfaffendorf, Martin; van Zwieten, Pieter A.

    2002-01-01

    Objective To evaluate the facilitating effect of angiotensin II on sympathetic neurotransmission to quantitatively compare the sympatho-inhibitory potencies of the selective AT(1)-receptor antagonists losartan, irbesartan and telmisartan in the isolated rabbit thoracic aorta. Design To investigate

  17. Adeno-associated viral vector-induced overexpression of neuropeptide Y Y2 receptors in the hippocampus suppresses seizures

    DEFF Research Database (Denmark)

    Woldbye, David Paul Drucker; Ängehagen, Mikael; Gøtzsche, Casper René

    2010-01-01

    Gene therapy using recombinant adeno-associated viral vectors overexpressing neuropeptide Y in the hippocampus exerts seizure-suppressant effects in rodent epilepsy models and is currently considered for clinical application in patients with intractable mesial temporal lobe epilepsy. Seizure...... recombinant adeno-associated viral vectors. In two temporal lobe epilepsy models, electrical kindling and kainate-induced seizures, vector-based transduction of Y2 receptor complementary DNA in the hippocampus of adult rats exerted seizure-suppressant effects. Simultaneous overexpression of Y2...... and neuropeptide Y had a more pronounced seizure-suppressant effect. These results demonstrate that overexpression of Y2 receptors (alone or in combination with neuropeptide Y) could be an alternative strategy for epilepsy treatment....

  18. Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor α-Dependent Transcription with Chromatin Templates

    OpenAIRE

    Acevedo, Mari Luz; Kraus, W. Lee

    2003-01-01

    Ligand-dependent transcriptional activation by nuclear receptors involves the recruitment of various coactivators to the promoters of hormone-regulated genes assembled into chromatin. Nuclear receptor coactivators include histone acetyltransferase complexes, such as p300/CBP-steroid receptor coactivator (SRC), as well as the multisubunit mediator complexes (“Mediator”), which may help recruit RNA polymerase II to the promoter. We have used a biochemical approach, including an in vitro chromat...

  19. Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B4-negative Medium-sized Trigeminal Ganglion Neurons.

    Science.gov (United States)

    Sato, Masaki; Ogura, Kazuhiro; Kimura, Maki; Nishi, Koichi; Ando, Masayuki; Tazaki, Masakazu; Shibukawa, Yoshiyuki

    2018-04-27

    Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X 3 ), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B 4 -negative medium-sized neurons. Action potentials in these isolectin B 4 -negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X 3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X 3 receptors induced an action potential

  20. Understanding magnetic nanoparticle osteoblast receptor-mediated endocytosis using experiments and modeling

    International Nuclear Information System (INIS)

    Tran, Nhiem; Webster, Thomas J

    2013-01-01

    Iron oxide nanoparticles are promising candidates for controlling drug delivery through an external magnetic force to treat a wide range of diseases, including osteoporosis. Previous studies have demonstrated that in the presence of hydroxyapatite coated magnetite (Fe 3 O 4 ) nanoparticles, osteoblast (or bone forming cell) proliferation and long-term functions (such as calcium deposition) were significantly enhanced. Hydroxyapatite is the major inorganic component of bone. As a further attempt to understand why, in the current study, the uptake of such nanoparticles into osteoblasts was experimentally investigated and mathematically modeled. Magnetite nanoparticles were synthesized using a co-precipitation method and were coated with hydroxyapatite. A cellular uptake experiment at low temperatures indicated that receptor-mediated endocytosis contributed to the internalization of the magnetic nanoparticles into osteoblasts. A model was further developed to explain the uptake of magnetic nanoparticles into osteoblasts using receptor-mediated endocytosis. This model may explain the internalization of hydroxyapatite into osteoblasts to elevate intracellular calcium levels necessary to promote osteoblast functions to treat a wide range of orthopedic problems, including osteoporosis. (paper)

  1. Glutamatergic neurotransmission modulates hypoxia-induced hyperventilation but not anapyrexia

    Directory of Open Access Journals (Sweden)

    Paula P.M. de

    2004-01-01

    Full Text Available The interaction between pulmonary ventilation (V E and body temperature (Tb is essential for O2 delivery to match metabolic rate under varying states of metabolic demand. Hypoxia causes hyperventilation and anapyrexia (a regulated drop in Tb, but the neurotransmitters responsible for this interaction are not well known. Since L-glutamate is released centrally in response to peripheral chemoreceptor stimulation and glutamatergic receptors are spread in the central nervous system we tested the hypothesis that central L-glutamate mediates the ventilatory and thermal responses to hypoxia. We measured V E and Tb in 40 adult male Wistar rats (270 to 300 g before and after intracerebroventricular injection of kynurenic acid (KYN, an ionotropic glutamatergic receptor antagonist, alpha-methyl-4-carboxyphenylglycine (MCPG, a metabotropic glutamatergic receptor antagonist or vehicle (saline, followed by a 1-h period of hypoxia (7% inspired O2 or normoxia (humidified room air. Under normoxia, KYN (N = 5 or MCPG (N = 8 treatment did not affect V E or Tb compared to saline (N = 6. KYN and MCPG injection caused a decrease in hypoxia-induced hyperventilation (595 ± 49 for KYN, N = 7 and 525 ± 84 ml kg-1 min-1 for MCPG, N = 6; P < 0.05 but did not affect anapyrexia (35.3 ± 0.2 for KYN and 34.7 ± 0.4ºC for MCPG compared to saline (912 ± 110 ml kg-1 min-1 and 34.8 ± 0.2ºC, N = 8. We conclude that glutamatergic receptors are involved in hypoxic hyperventilation but do not affect anapyrexia, indicating that L-glutamate is not a common mediator of this interaction.

  2. Vagal gustatory reflex circuits for intraoral food sorting behavior in the goldfish: cellular organization and neurotransmitters.

    Science.gov (United States)

    Ikenaga, Takanori; Ogura, Tatsuya; Finger, Thomas E

    2009-09-20

    The sense of taste is crucial in an animal's determination as to what is edible and what is not. This gustatory function is especially important in goldfish, who utilize a sophisticated oropharyngeal sorting mechanism to separate food from substrate material. The computational aspects of this detection are carried out by the medullary vagal lobe, which is a large, laminated structure combining elements of both the gustatory nucleus of the solitary tract and the nucleus ambiguus. The sensory layers of the vagal lobe are coupled to the motor layers via a simple reflex arc. Details of this reflex circuit were investigated with histology and calcium imaging. Biocytin injections into the motor layer labeled vagal reflex interneurons that have radially directed dendrites ramifying within the layers of primary afferent terminals. Axons of reflex interneurons extend radially inward to terminate onto both vagal motoneurons and small, GABAergic interneurons in the motor layer. Functional imaging shows increases in intracellular Ca++ of vagal motoneurons following electrical stimulation in the sensory layer. These responses were suppressed under Ca(++)-free conditions and by interruption of the axons bridging between the sensory and motor layers. Pharmacological experiments showed that glutamate acting via (+/-)-alpha-amino-3-hydroxy- 5-ethylisoxazole-4-propioinc acid (AMPA)/kainate and N-methyl-D-aspartic acid (NMDA) receptors mediate neurotransmission between reflex interneurons and vagal motoneurons. Thus, the vagal gustatory portion of the viscerosensory complex is linked to branchiomotor neurons of the pharynx via a glutamatergic interneuronal system.

  3. Vagal gustatory reflex circuits for intraoral food sorting behavior in the goldfish Cellular organization and neurotransmitters

    Science.gov (United States)

    Ikenaga, Takanori; Ogura, Tatsuya; Finger, Thomas E.

    2009-01-01

    The sense of taste is crucial in an animal’s determination as to what is edible and what is not. This gustatory function is especially important in goldfish who utilize a sophisticated oropharyngeal sorting mechanism to separate food from substrate material. The computational aspects of this detection are carried out by the medullary vagal lobe which is a large, laminated structure combining elements of both the gustatory nucleus of the solitary tract and the nucleus ambiguus. The sensory layers of the vagal lobe are coupled to the motor layers via a simple reflex arc. Details of this reflex circuit were investigated with histology and calcium imaging. Biocytin injections into the motor layer labeled vagal reflex interneurons which have radially-directed dendrites ramifying within the layers of primary afferent terminals. Axons of reflex interneurons extend radially inward to terminate onto both vagal motoneurons and small, GABAergic interneurons in the motor layer. Functional imaging shows increases in intracellular Ca++ of vagal motoneurons following electrical stimulation in the sensory layer. These responses were suppressed under Ca++-free conditions and by interruption of the axons bridging between the sensory and motor layers. Pharmacological experiments showed that glutamate acting via (±)-α-amino-3-hydroxy-5-ethylisoxazole-4-propioinc acid (AMPA)/kainate and N-methyl-D-aspartic acid (NMDA) receptors mediates neurotransmission between reflex interneurons and vagal motoneurons. Thus the vagal gustatory portion of the viscerosensory complex is linked to branchiomotor neurons of the pharynx via a glutamatergic interneuronal system. PMID:19598285

  4. DARPP-32: from neurotransmission to cancer

    Science.gov (United States)

    Belkhiri, Abbes; Zhu, Shoumin; El-Rifai, Wael

    2016-01-01

    Dopamine and cAMP-regulated phosphoprotein Mr 32,000 (DARPP-32), also known as phosphoprotein phosphatase-1 regulatory subunit 1B (PPP1R1B), was initially discovered as a substrate of dopamine-activated protein kinase A (PKA) in the neostriatum in the brain. While phosphorylation at Thr-34 by PKA converts DARPP-32 into a potent inhibitor of protein phosphatase 1 (PP1), phosphorylation at Thr-75 transforms DARPP-32 into an inhibitor of PKA. Through regulation of DARPP-32 phosphorylation and modulation of protein phosphatase and kinase activities, DARPP-32 plays a critical role in mediating the biochemical, electrophysiological, and behavioral effects controlled by dopamine and other neurotransmitters in response to drugs of abuse and psychostimulants. Altered expression of DARPP-32 and its truncated isoform (t-DARPP), specifically in the prefrontal cortex, has been associated with schizophrenia and bipolar disorder. Moreover, cleavage of DARPP-32 by calpain has been implicated in Alzheimer's disease. Amplification of the genomic locus of DARPP-32 at 17q12 has been described in several cancers. DARPP-32 and t-DARPP are frequently overexpressed at the mRNA and protein levels in adenocarcinomas of the breast, prostate, colon, and stomach. Several studies demonstrated the pro-survival, pro-invasion, and pro-angiogenic functions of DARPP-32 in cancer. Overexpression of DARPP-32 and t-DARPP also promotes chemotherapeutic drug resistance and cell proliferation in gastric and breast cancers through regulation of pro-oncogenic signal transduction pathways. The expansion of DARPP-32 research from neurotransmission to cancer underscores the broad scope and implication of this protein in disparate human diseases. PMID:26872373

  5. Regulation of GABA and benzodiazepine receptors following neurotoxin-induced striatal and medial forebrain bundle lesions

    International Nuclear Information System (INIS)

    Pan, H.S.I.

    1985-01-01

    GABA, a major inhibitory transmitter, is used by many projection neurons of the striatum. To investigate the role of GABA in striatal function, the GABA receptor complex was studied after lesions of the striatum or the nigrostriatal neurons. Quantitative receptor autoradiography using thaw-mounted tissue slices was developed for the study of GABA and benzodiazepine (BDZ) receptors. With the technique established, binding to GABA and BDZ receptors after unilateral striatal kainate lesions was examined. Subsequently, changes in GABA and BDZ receptors were studied following the destruction of dopaminergic nigrostriatal cells by unilateral 6-hydroxydopamine lesion of the medial forebrain bundle. In summary, quantitative receptor autoradiography allowed the detection of GABA and BDZ receptor changes in multiple small areas in each lesioned brain. This technique made it feasible to carry out kinetic saturation, and competition studies using less than 1 mg of tissue. The data suggest that dopamine is functionally inhibitory on striatopallidal neurons but is functionally excitatory on striatoentopeduncular and striatonigral cells which in turn inhibit the thalamus. This quantitative autoradiographic technique can be generalized to study other transmitter receptors and can be combined with 2-deoxyglucose uptake studies

  6. Contribution of non-genetic factors to dopamine and serotonin receptor availability in the adult human brain

    DEFF Research Database (Denmark)

    Borg, J; Cervenka, S; Kuja-Halkola, R

    2016-01-01

    The dopamine (DA) and serotonin (5-HT) neurotransmission systems are of fundamental importance for normal brain function and serve as targets for treatment of major neuropsychiatric disorders. Despite central interest for these neurotransmission systems in psychiatry research, little is known about...... and environmental factors, respectively, on dopaminergic and serotonergic markers in the living human brain. Eleven monozygotic and 10 dizygotic healthy male twin pairs were examined with PET and [(11)C]raclopride binding to the D2- and D3-dopamine receptor and [(11)C]WAY100635 binding to the serotonin 5-HT1A...

  7. Muscarinic receptor M4 positive allosteric modulators attenuate central effects of cocaine

    DEFF Research Database (Denmark)

    Dall, Camilla; Weikop, Pia; Dencker, Ditte

    2017-01-01

    BACKGROUND: Cocaine addiction is a chronic brain disease affecting neurotransmission. Muscarinic cholinergic receptors modulate dopaminergic signaling in the reward system, and muscarinic receptor stimulation can block direct reinforcing effects of cocaine. Here, we tested the hypothesis...... that specific muscarinic M4receptor stimulation can attenuate the discriminative stimulus effects and conditioned rewarding effects of cocaine, measures believed to predict the ability of cocaine and cocaine-associated cues to elicit relapse to drug taking. METHODS: We tested the M4-selective positive...

  8. RIG-I-like receptor-induced IRF3 mediated pathway of apoptosis (RIPA: a new antiviral pathway

    Directory of Open Access Journals (Sweden)

    Saurabh Chattopadhyay

    2016-11-01

    Full Text Available Abstract The innate immune response is the first line of host defense to eliminate viral infection. Pattern recognition receptors in the cytosol, such as RIG-I-like receptors (RLR and Nod-like receptors (NLR, and membrane bound Toll like receptors (TLR detect viral infection and initiate transcription of a cohort of antiviral genes, including interferon (IFN and interferon stimulated genes (ISGs, which ultimately block viral replication. Another mechanism to reduce viral spread is through RIPA, the RLR-induced IRF3-mediated pathway of apoptosis, which causes infected cells to undergo premature death. The transcription factor IRF3 can mediate cellular antiviral responses by both inducing antiviral genes and triggering apoptosis through the activation of RIPA. The mechanism of IRF3 activation in RIPA is distinct from that of transcriptional activation; it requires linear polyubiquitination of specific lysine residues of IRF3. Using RIPA-active, but transcriptionally inactive, IRF3 mutants, it was shown that RIPA can prevent viral replication and pathogenesis in mice.

  9. Basolateral P2X receptors mediate inhibition of NaCl transport in mouse medullary thick ascending limb (mTAL)

    DEFF Research Database (Denmark)

    Marques, Rita D; de Bruijn, Pauline I.A.; Sørensen, Mads Vaarby

    2012-01-01

    Extracellular nucleotides regulate epithelial transport via luminal and basolateral P2 receptors. Renal epithelia express multiple P2 receptors, which mediate significant inhibition of solute absorption. Recently, we identified several P2 receptors in the medullary thick ascending limb (m...

  10. Corticotropin-Releasing Factor Mediates Pain-Induced Anxiety through the ERK1/2 Signaling Cascade in Locus Coeruleus Neurons

    Science.gov (United States)

    Borges, Gisela Patrícia; Micó, Juan Antonio; Neto, Fani Lourença

    2015-01-01

    Background: The corticotropin-releasing factor is a stress-related neuropeptide that modulates locus coeruleus activity. As locus coeruleus has been involved in pain and stress-related patologies, we tested whether the pain-induced anxiety is a result of the corticotropin-releasing factor released in the locus coeruleus. Methods: Complete Freund’s adjuvant-induced monoarthritis was used as inflammatory chronic pain model. α-Helical corticotropin-releasing factor receptor antagonist was microinjected into the contralateral locus coeruleus of 4-week-old monoarthritic animals. The nociceptive and anxiety-like behaviors, as well as phosphorylated extracellular signal-regulated kinases 1/2 and corticotropin-releasing factor receptors expression, were quantified in the paraventricular nucleus and locus coeruleus. Results: Monoarthritic rats manifested anxiety and increased phosphorylated extracellular signal-regulated kinases 1/2 levels in the locus coeruleus and paraventricular nucleus, although the expression of corticotropin-releasing factor receptors was unaltered. α-Helical corticotropin-releasing factor antagonist administration reversed both the anxiogenic-like behavior and the phosphorylated extracellular signal-regulated kinases 1/2 levels in the locus coeruleus. Conclusions: Pain-induced anxiety is mediated by corticotropin-releasing factor neurotransmission in the locus coeruleus through extracellular signal-regulated kinases 1/2 signaling cascade. PMID:25716783

  11. Cerebral 5-HT2A receptor binding is increased in patients with Tourette's syndrome

    DEFF Research Database (Denmark)

    Haugbøl, Steven; Pinborg, Lars H.; Regeur, Lisbeth

    2007-01-01

    Experimental and clinical data have suggested that abnormalities in the serotonergic neurotransmissions in frontal-subcortical circuits are involved in Tourette's syndrome. To test the hypothesis that the brain's 5-HT2A receptor binding is increased in patients with Tourette's syndrome, PET imagi...

  12. (S)-2-Amino-3-(3-hydroxy-7,8-dihydro-6H-cyclohepta[d]isoxazol-4-yl)propionic acid, a potent and selective agonist at the GluR5 subtype of ionotropic glutamate receptors. Synthesis, modeling, and molecular pharmacology

    DEFF Research Database (Denmark)

    Brehm, Lotte; Greenwood, Jeremy R; Hansen, Kasper B

    2003-01-01

    )propionic acid (AMPA) but inactive at NMDA receptors. However, 4-AHCP was found to be much weaker than AMPA as an inhibitor of [(3)H]AMPA binding and to have limited effect in a [(3)H]kainic acid binding assay using rat cortical membranes. To shed light on the mechanism(s) underlying this quite enigmatic......, activated cloned AMPA receptor subunits GluR1o, GluR3o, and GluR4o with EC(50) values in the range 4.5-15 microM and the coexpressed kainate-preferring subunits GluR6 + KA2 (EC(50) = 6.4 microM). Compound 6, but not 7, proved to be a very potent agonist (EC(50) = 0.13 microM) at the kainate-preferring GluR5...... subunit, equipotent with (S)-2-amino-3-(5-tert-butyl-3-hydroxyisothiazol-4-yl)propionic acid [(S)-Thio-ATPA, 4] and almost 4 times more potent than (S)-2-amino-3-(5-tert-butyl-3-hydroxyisoxazol-4-yl)propionic acid [(S)-ATPA, 3]. Compound 6 thus represents a new structural class of GluR5 agonists...

  13. Neuropeptide Y restores non-receptor-mediated vasoconstrictive action in superior mesenteric arteries in portal hypertension.

    Science.gov (United States)

    Hartl, Johannes; Dietrich, Peter; Moleda, Lukas; Müller-Schilling, Martina; Wiest, Reiner

    2015-12-01

    Vascular hyporeactivity to vasoconstrictors contributes to splanchnic arterial vasodilatation and hemodynamic dysregulation in portal hypertension. Neuropeptide Y (NPY), a sympathetic cotransmitter, has been shown to improve adrenergic vascular contractility in portal hypertensive rats and markedly attenuate hyperdynamic circulation. To further characterize the NPY-effects in portal hypertension, we investigated its role for non-receptor-mediated vasoconstriction in the superior mesenteric artery (SMA) of portal vein ligated (PVL) and sham-operated rats. Ex vivo SMA perfusion of PVL and sham rats was used to analyse the effects of NPY on pressure response to non-receptor-mediated vasoconstriction. Dose-response curves to KCl (30-300 mM) were used to bypass G protein-coupled receptor mechanisms. Potential involvement of the cyclooxygenase-pathway was tested by non-selective cyclooxygenase-inhibition using indomethacin. KCl-induced vascular contractility but not vascular sensitivity was significantly attenuated in PVL rats as compared with sham rats. Administration of NPY resulted in an augmentation of KCl-evoked vascular sensitivity being not different between study groups. However, KCl-induced vascular contractility was markedly more enhanced in PVL rats, thus, vascular response was no more significantly different between PVL and sham rats after addition of NPY. Administration of indomethacin abolished the NPY-induced enhancement of vasoconstriction. Receptor-independent vascular contractility is impaired in mesenteric arteries in portal hypertension. NPY improves non-receptor mediated mesenteric vasoconstriction more effective in portal hypertension than in healthy conditions correcting splanchnic vascular hyporesponsiveness. This beneficial vasoactive action of NPY adds to its well known more pronounced effects on adrenergic vasoconstriction in portal hypertension making it a promising therapeutic agent in portal hypertension. © 2015 John Wiley & Sons A

  14. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    International Nuclear Information System (INIS)

    Junker, L.H.; Davis, R.A.

    1989-01-01

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of [14C]cholesterol from [2-14C]acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of [14C]cholesterol from [2-14C]acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis

  15. Zebrafish Get Connected: Investigating Neurotransmission Targets and Alterations in Chemical Toxicity

    Directory of Open Access Journals (Sweden)

    Katharine A. Horzmann

    2016-08-01

    Full Text Available Neurotransmission is the basis of neuronal communication and is critical for normal brain development, behavior, learning, and memory. Exposure to drugs and chemicals can alter neurotransmission, often through unknown pathways and mechanisms. The zebrafish (Danio rerio model system is increasingly being used to study the brain and chemical neurotoxicity. In this review, the major neurotransmitter systems, including glutamate, GABA, dopamine, norepinephrine, serotonin, acetylcholine, histamine, and glutamate are surveyed and pathways of synthesis, transport, metabolism, and action are examined. Differences between human and zebrafish neurochemical pathways are highlighted. We also review techniques for evaluating neurological function, including the measurement of neurotransmitter levels, assessment of gene expression through transcriptomic analysis, and the recording of neurobehavior. Finally examples of chemical toxicity studies evaluating alterations in neurotransmitter systems in the zebrafish model are reviewed.

  16. Inorganic phosphate inhibits sympathetic neurotransmission in canine saphenous veins

    International Nuclear Information System (INIS)

    Edoute, Y.; Vanhoutte, P.M.; Shepherd, J.T.

    1987-01-01

    Inorganic phosphate has been proposed as the initiator of metabolic vasodilatation in active skeletal muscle. The present study was primarily designed to determine if this substance has an inhibitory effect on adrenergic neurotransmission. Rings of canine saphenous veins were suspended for isometric tension recording in organ chambers. A comparison was made of the ability of inorganic phosphate (3 to 14 mM) to relax rings contracted to the same degree by electrical stimulation, exogenous norepinephrine, and prostaglandin F/sub 2α/. The relaxation during electrical stimulation was significantly greater at all concentrations of phosphate. In strips of saphenous veins previously incubated with [ 3 H]norepinephrine, the depression of the contractile response caused by phosphate during electrical stimulated was accompanied by a significant reduction in the overflow of labeled neurotransmitter. Thus inorganic phosphate inhibits sympathetic neurotransmission and hence may have a key role in the sympatholysis in the active skeletal muscles during exercise. By contrast, in this preparation, it has a modest direct relaxing action on the vascular smooth muscle

  17. Natural products as tools for studies of ligand-gated ion channels

    DEFF Research Database (Denmark)

    Strømgaard, Kristian

    2005-01-01

    Ligand-gated ion channels, or ionotropic receptors, constitute a group of membrane-bound proteins that regulate the flux of ions across the cell membrane. In the brain, ligand-gated ion channels mediate fast neurotransmission. They are crucial for normal brain function and involved in many diseases...

  18. Decrease in benzodiazepine receptor binding in a patient with Angelman syndrome detected by iodine-123 iomazenil and single-photon emission tomography

    International Nuclear Information System (INIS)

    Odano, Ikuo; Anezaki, Toshiharu; Ohkubo, Masaki; Yonekura, Yoshiharu; Onishi, Yoshihiro; Inuzuka, Takashi; Takahashi, Makoto; Tsuji, Shoji

    1996-01-01

    A receptor mapping technique using iodine-123 iomazenil and single-photon emission tomography (SPET) was employed to examine benzodiazepine receptor binding in a patient with Angelman syndrome (AS). AS is characterized by developmental delay, seizures, inappropriate laughter and ataxic movement. In this entity there is a cytogenic deletion of the proximal long arm of chromosome 15q11-q13, where the gene encoding the GABA A receptor β3 subunit (GABRB3) is located. Since the benzodiazepine receptor is constructed as a receptor-ionophore complex that contains the GABA A receptor, it is a suitable marker for GABA-ergic synapsis. To determine whether benzodiazepine receptor density, which indirectly indicates changes in GABA A receptor density, is altered in the brain in patients with AS, we investigated a 27-year-old woman with AS using 123 I-iomazenil and SPET. Receptor density was quantitatively assessed by measuring the binding potential using a simplified method. Regional cerebral blood flow was also measured with N-isopropyl-p- 123 iodoamphetamine. We demonstrated that benzodiazepiine receptor density is severely decreased in the cerebellum, and mildly decreased in the frontal and temporal cortices and basal ganglia, a result which is considered to indicate decreased GABA A receptor density in these regions. Although the deletion of GABRB3 was not observed in the present study, we indirectly demonstrated the disturbance of inhibitory neurotransmission mediated by the GABA A receptor in the investigated patient. 123 I-iomazenil with SPET was useful to map benzodiazepine receptors, which indicate GABA A receptor distribution and their density. (orig.)

  19. ARF6 and GASP-1 are post-endocytic sorting proteins selectively involved in the intracellular trafficking of dopamine D2 receptors mediated by GRK and PKC in transfected cells

    Science.gov (United States)

    Cho, DI; Zheng, M; Min, C; Kwon, KJ; Shin, CY; Choi, HK; Kim, KM

    2013-01-01

    Background and Purpose GPCRs undergo both homologous and heterologous regulatory processes in which receptor phosphorylation plays a critical role. The protein kinases responsible for each pathway are well established; however, other molecular details that characterize each pathway remain unclear. In this study, the molecular mechanisms that determine the differences in the functional roles and intracellular trafficking between homologous and PKC-mediated heterologous internalization pathways for the dopamine D2 receptor were investigated. Experimental Approach All of the S/T residues located within the intracellular loops of D2 receptor were mutated, and the residues responsible for GRK- and PKC-mediated internalization were determined in HEK-293 cells and SH-SY5Y cells. The functional role of receptor internalization and the cellular components that determine the post-endocytic fate of internalized D2 receptors were investigated in the transfected cells. Key Results T134, T225/S228/S229 and S325 were involved in PKC-mediated D2 receptor desensitization. S229 and adjacent S/T residues mediated the PKC-dependent internalization of D2 receptors, which induced down-regulation and desensitization. S/T residues within the second intracellular loop and T225 were the major residues involved in GRK-mediated internalization of D2 receptors, which induced receptor resensitization. ARF6 mediated the recycling of D2 receptors internalized in response to agonist stimulation. In contrast, GASP-1 mediated the down-regulation of D2 receptors internalized in a PKC-dependent manner. Conclusions and Implications GRK- and PKC-mediated internalizations of D2 receptors occur through different intracellular trafficking pathways and mediate distinct functional roles. Distinct S/T residues within D2 receptors and different sorting proteins are involved in the dissimilar regulation of D2 receptors by GRK2 and PKC. PMID:23082996

  20. The Influence of Receptor-Mediated Interactions on Reaction-Diffusion Mechanisms of Cellular Self-organisation

    KAUST Repository

    Klika, Vá clav; Baker, Ruth E.; Headon, Denis; Gaffney, Eamonn A.

    2011-01-01

    formation, motivating numerous theoretical and experimental studies, though its verification at the molecular level in biological systems has remained elusive. In this work, we consider the influence of receptor-mediated dynamics within the framework

  1. Receptor-independent, vacuolar ATPase-mediated cellular uptake of histamine receptor-1 ligands: Possible origin of pharmacological distortions and side effects

    International Nuclear Information System (INIS)

    Morissette, Guillaume; Lodge, Robert; Bouthillier, Johanne; Marceau, Francois

    2008-01-01

    The aims of this study were to investigate whether several histamine receptor agonists and antagonists are subjected to receptor-independent ion trapping into acidic organelles, and whether this sequestration influences their pharmacological or toxicological properties. Vacuolar (V)-ATPase-dependent intracellular sequestration of agonists was recognized as morphological alterations (large fluid-filled vacuoles for betahistine and 1-methylhistamine, granular uptake for fluorescent BODIPY FL histamine) prevented by the specific V-ATPase inhibitor bafilomycin A1 in rabbit vascular smooth muscle cells. Lipophilicity was the major determinant of these cellular effects (order of potency: BODIPY FL histamine > betahistine > 1-methylhistamine > histamine) that occurred at high concentrations. This ranking was dissociable from the potency order for H 1 receptor-mediated contraction of the rabbit aorta, a response uninfluenced by bafilomycin. Antihistamines are inherently more lipophilic and caused vacuolization of a proportion of cells at 5-500 μM. Agonist or antagonist-induced vacuoles were of macroautophagic nature (labeled with GFP-conjugated LC3, Rab7 and CD63; detection of LC3 II). Further, the 2 most lipophilic antihistamines tested, astemizole and terfenadine, were potentiated by V-ATPase blockade in the aortic contractility assay (13- and 3.6-fold more potent, respectively, pA 2 scale), suggesting that V-ATPase-mediated cation trapping sequesters these antagonists from the vicinity of H 1 receptors in the therapeutic concentration range. This potentiation did not apply to less lipophilic antagonists (pyrilamine, diphenhydramine). While some agonists and all tested antagonists of the histamine H 1 receptors induce the V-ATPase-dependent vacuolar and autophagic cytopathology, sequestration affects the pharmacology of only the most lipophilic antagonists, the ones prone to off-target arrhythmogenic side effects

  2. Characterization of GABA/sub A/ receptor-mediated 36chloride uptake in rat brain synaptoneurosomes

    International Nuclear Information System (INIS)

    Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.

    1987-01-01

    γ-Aminobutyric acid (GABA) receptor-mediated 36 chloride ( 36 Cl - ) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated 36 Cl - uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated 36 Cl - uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated 36 Cl - uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br - >Cl - ≥NO 3 - >I - ≥SCN - >>C 3 H 5 OO - ≥ClO 4 - >F - , consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl - channel. 43 references, 4 figures, 3 tables

  3. Locus Coeruleus and Tuberomammillary Nuclei Ablations Attenuate Hypocretin/Orexin Antagonist-Mediated REM Sleep.

    Science.gov (United States)

    Schwartz, Michael D; Nguyen, Alexander T; Warrier, Deepti R; Palmerston, Jeremiah B; Thomas, Alexia M; Morairty, Stephen R; Neylan, Thomas C; Kilduff, Thomas S

    2016-01-01

    Hypocretin 1 and 2 (Hcrts; also known as orexin A and B), excitatory neuropeptides synthesized in cells located in the tuberal hypothalamus, play a central role in the control of arousal. Hcrt inputs to the locus coeruleus norepinephrine (LC NE) system and the posterior hypothalamic histaminergic tuberomammillary nuclei (TMN HA) are important efferent pathways for Hcrt-induced wakefulness. The LC expresses Hcrt receptor 1 (HcrtR1), whereas HcrtR2 is found in the TMN. Although the dual Hcrt/orexin receptor antagonist almorexant (ALM) decreases wakefulness and increases NREM and REM sleep time, the neural circuitry that mediates these effects is currently unknown. To test the hypothesis that ALM induces sleep by selectively disfacilitating subcortical wake-promoting populations, we ablated LC NE neurons (LCx) or TMN HA neurons (TMNx) in rats using cell-type-specific saporin conjugates and evaluated sleep/wake following treatment with ALM and the GABAA receptor modulator zolpidem (ZOL). Both LCx and TMNx attenuated the promotion of REM sleep by ALM without affecting ALM-mediated increases in NREM sleep. Thus, eliminating either HcrtR1 signaling in the LC or HcrtR2 signaling in the TMN yields similar effects on ALM-induced REM sleep without affecting NREM sleep time. In contrast, neither lesion altered ZOL efficacy on any measure of sleep-wake regulation. These results contrast with those of a previous study in which ablation of basal forebrain cholinergic neurons attenuated ALM-induced increases in NREM sleep time without affecting REM sleep, indicating that Hcrt neurotransmission influences distinct aspects of NREM and REM sleep at different locations in the sleep-wake regulatory network.

  4. Role of glutamate receptors and nitric oxide on the effects of glufosinate ammonium, an organophosphate pesticide, on in vivo dopamine release in rat striatum.

    Science.gov (United States)

    Faro, Lilian R F; Ferreira Nunes, Brenda V; Alfonso, Miguel; Ferreira, Vania M; Durán, Rafael

    2013-09-15

    The purpose of the present work was to assess the possible role of glutamatergic receptors and nitric oxide (NO) production on effects of glufosinate ammonium (GLA), an organophosphate pesticide structurally related to glutamate, on in vivo striatal dopamine release in awake and freely moving rats. For this, we used antagonists of NMDA (MK-801 and AP5) or AMPA/kainate (CNQX) receptors, or nitric oxide synthase (NOS) inhibitors (l-NAME and 7-NI), to study the effects of GLA on release of dopamine from rat striatum. So, intrastriatal infusion of 10mM GLA significantly increased dopamine levels (1035±140%, compared with basal levels) and administration of GLA to MK-801 (250μM) or AP5 (650μM) pretreated animals, produced increases in dopamine overflow that were ∼40% and ∼90% smaller than those observed in animals not pretreated with MK-801 or AP5. Administration of GLA to CNQX (500μM) pretreated animals produced an effect that was not significantly different from the one produced in animals not pretreated with CNQX. On the other hand, administration of GLA to l-NAME (100μM) or 7-NI (100μM) pretreated animals, produced increases in dopamine overflow that were ∼80% and ∼75% smaller than those observed in animals not pretreated with these inhibitors. In summary, GLA appears to act, at least in part, through an overstimulation of NMDA (and not AMPA/kainate) receptors with possible NO production to induce in vivo dopamine release. Administration of NMDA receptor antagonists and NOS inhibitors partially blocks the release of dopamine from rat striatum. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  5. Dopamine D2 receptors mediate two-odor discrimination and reversal learning in C57BL/6 mice

    Directory of Open Access Journals (Sweden)

    Grandy David K

    2004-04-01

    Full Text Available Abstract Background Dopamine modulation of neuronal signaling in the frontal cortex, midbrain, and striatum is essential for processing and integrating diverse external sensory stimuli and attaching salience to environmental cues that signal causal relationships, thereby guiding goal-directed, adaptable behaviors. At the cellular level, dopamine signaling is mediated through D1-like or D2-like receptors. Although a role for D1-like receptors in a variety of goal-directed behaviors has been identified, an explicit involvement of D2 receptors has not been clearly established. To determine whether dopamine D2 receptor-mediated signaling contributes to associative and reversal learning, we compared C57Bl/6J mice that completely lack functional dopamine D2 receptors to wild-type mice with respect to their ability to attach appropriate salience to external stimuli (stimulus discrimination and disengage from inappropriate behavioral strategies when reinforcement contingencies change (e.g. reversal learning. Results Mildly food-deprived female wild-type and dopamine D2 receptor deficient mice rapidly learned to retrieve and consume visible food reinforcers from a small plastic dish. Furthermore, both genotypes readily learned to dig through the same dish filled with sterile sand in order to locate a buried food pellet. However, the dopamine D2 receptor deficient mice required significantly more trials than wild-type mice to discriminate between two dishes, each filled with a different scented sand, and to associate one of the two odors with the presence of a reinforcer (food. In addition, the dopamine D2 receptor deficient mice repeatedly fail to alter their response patterns during reversal trials where the reinforcement rules were inverted. Conclusions Inbred C57Bl/6J mice that develop in the complete absence of functional dopamine D2 receptors are capable of olfaction but display an impaired ability to acquire odor-driven reinforcement contingencies

  6. The brain cytoplasmic RNA BC1 regulates dopamine D-2 receptor-mediated transmission in the striatum

    OpenAIRE

    Centonze, Diego; Rossi, Silvia; Napoli, Ilaria; Mercaldo, Valentina; Lacoux, Caroline; Ferrari, Francesca; Ciotti, Maria Teresa; De Chiara, Valentina; Prosperetti, Chiara; Maccarrone, Mauro; Fezza, Filomena; Calabresi, Paolo; Bernardi, Giorgio; Bagni, Claudia

    2007-01-01

    Dopamine D-2 receptor (D2DR)-mediated transmission in the striatum is remarkably flexible, and changes in its efficacy have been heavily implicated in a variety of physiological and pathological conditions. Although receptor-associated proteins are clearly involved in specific forms of synaptic plasticity, the molecular mechanisms regulating the sensitivity of D-2 receptors in this brain area are essentially obscure. We have studied the physiological responses of the D2DR stimulations in mice...

  7. Glutamate mediates the function of melanocortin receptor 4 on sim1 neurons in body weight regulation

    Science.gov (United States)

    The melanocortin receptor 4 (MC4R) is a well-established mediator of body weight homeostasis. However, the neurotransmitter(s) that mediate MC4R function remain largely unknown; as a result, little is known about the second-order neurons of the MC4R neural pathway. Single-minded 1 (Sim1)-expressing ...

  8. Endogenous 24S-hydroxycholesterol modulates NMDAR-mediated function in hippocampal slices.

    Science.gov (United States)

    Sun, Min-Yu; Izumi, Yukitoshi; Benz, Ann; Zorumski, Charles F; Mennerick, Steven

    2016-03-01

    N-methyl-D-aspartate receptors (NMDARs), a major subtype of glutamate receptors mediating excitatory transmission throughout the central nervous system (CNS), play critical roles in governing brain function and cognition. Because NMDAR dysfunction contributes to the etiology of neurological and psychiatric disorders including stroke and schizophrenia, NMDAR modulators are potential drug candidates. Our group recently demonstrated that the major brain cholesterol metabolite, 24S-hydroxycholesterol (24S-HC), positively modulates NMDARs when exogenously administered. Here, we studied whether endogenous 24S-HC regulates NMDAR activity in hippocampal slices. In CYP46A1(-/-) (knockout; KO) slices where endogenous 24S-HC is greatly reduced, NMDAR tone, measured as NMDAR-to-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) excitatory postsynaptic current (EPSC) ratio, was reduced. This difference translated into more NMDAR-driven spiking in wild-type (WT) slices compared with KO slices. Application of SGE-301, a 24S-HC analog, had comparable potentiating effects on NMDAR EPSCs in both WT and KO slices, suggesting that endogenous 24S-HC does not saturate its NMDAR modulatory site in ex vivo slices. KO slices did not differ from WT slices in either spontaneous neurotransmission or in neuronal intrinsic excitability, and exhibited LTP indistinguishable from WT slices. However, KO slices exhibited higher resistance to persistent NMDAR-dependent depression of synaptic transmission induced by oxygen-glucose deprivation (OGD), an effect restored by SGE-301. Together, our results suggest that loss of positive NMDAR tone does not elicit compensatory changes in excitability or transmission, but it protects transmission against NMDAR-mediated dysfunction. We expect that manipulating this endogenous NMDAR modulator may offer new treatment strategies for neuropsychiatric dysfunction. Copyright © 2016 the American Physiological Society.

  9. Identification of phenylalanine 346 in the rat growth hormone receptor as being critical for ligand-mediated internalization and down-regulation

    DEFF Research Database (Denmark)

    Allevato, G; Billestrup, N; Goujon, L

    1995-01-01

    The functional significance of growth hormone (GH) receptor (GHR) internalization is unknown; therefore, we have analyzed domains and individual amino acids in the cytoplasmic region of the rat GHR required for ligand-mediated receptor internalization, receptor down-regulation, and transcriptiona...

  10. Discoidin Domain Receptor 1 Mediates Myosin-Dependent Collagen Contraction

    Directory of Open Access Journals (Sweden)

    Nuno M. Coelho

    2017-02-01

    Full Text Available Discoidin domain receptor 1 (DDR1 is a tyrosine kinase collagen adhesion receptor that mediates cell migration through association with non-muscle myosin IIA (NMIIA. Because DDR1 is implicated in cancer fibrosis, we hypothesized that DDR1 interacts with NMIIA to enable collagen compaction by traction forces. Mechanical splinting of rat dermal wounds increased DDR1 expression and collagen alignment. In periodontal ligament of DDR1 knockout mice, collagen mechanical reorganization was reduced >30%. Similarly, cultured cells with DDR1 knockdown or expressing kinase-deficient DDR1d showed 50% reduction of aligned collagen. Tractional remodeling of collagen was dependent on DDR1 clustering, activation, and interaction of the DDR1 C-terminal kinase domain with NMIIA filaments. Collagen remodeling by traction forces, DDR1 tyrosine phosphorylation, and myosin light chain phosphorylation were increased on stiff versus soft substrates. Thus, DDR1 clustering, activation, and interaction with NMIIA filaments enhance the collagen tractional remodeling that is important for collagen compaction in fibrosis.

  11. Epilepsy, Regulation of Brain Energy Metabolism and Neurotransmission

    OpenAIRE

    Cloix, Jean-Fran?ois; H?vor, Tobias

    2009-01-01

    Seizures are the result of a sudden and temporary synchronization of neuronal activity, the reason for which is not clearly understood. Astrocytes participate in the control of neurotransmitter storage and neurotransmission efficacy. They provide fuel to neurons, which need a high level of energy to sustain normal and pathological neuronal activities, such as during epilepsy. Various genetic or induced animal models have been developed and used to study epileptogenic mechanisms. Methionine su...

  12. The liver taxis of receptor mediated lactosaminated human growth hormone

    International Nuclear Information System (INIS)

    Chen Zelian; Shi Lin; Li Tongling; Pang Qijie; He Juying; Guan Changtian

    2002-01-01

    Radiography imaging is used to assess liver taxis mechanism of anti-dwarfism drug lactosaminated human growth hormone (L-rhGH). Both L-rhGH and rhGH labelled with 131 I are used to study their biodistribution in animals (including rabbits, cocks and rats). The results show that L-rhGH is of specific hepatic targeting property, and the maximum hepatic concentration rate is 76.8%, which is two times of rhGH. Its hepatic binding is receptor mediated

  13. Influence of gallamine, pancuronium, d-tubocurarine and succinylcholine on adrenergic neurotransmission

    NARCIS (Netherlands)

    Vercruysse, P.; Bossuyt, P.; Verbeuren, T. J.; Vanhoutte, P. M.; Hanegreefs, G.

    1979-01-01

    The influence of gallamine, pancuronium, d-tubocurarine and succinylcholine on adrenergic neurotransmission was studied in the isolated saphenous vein of the dog. Pancuronium increased the response of vascular smooth muscle to adrenergic nerve stimulation and to exogenous norepinephrine; gallamine,

  14. Interactions Between SNAP-25 and Synaptotagmin-1 Are Involved in Vesicle Priming, Clamping Spontaneous and Stimulating Evoked Neurotransmission

    DEFF Research Database (Denmark)

    Schupp, Melanie; Malsam, Jörg; Ruiter, Marvin

    2016-01-01

    between region I (vesicle priming) and region II (evoked release). Spontaneous release was disinhibited by region I mutations and found to correlate with defective complexin (Cpx) clamping in an in vitro fusion assay, pointing to an interdependent role of synaptotagmin and Cpx in release clamping...... triggering, depend on direct SNARE complex interaction. SIGNIFICANCE STATEMENT: The function of synaptotagmin-1 (syt-1):soluble NSF attachment protein receptor (SNARE) interactions during neurotransmission remains unclear. We mutated SNAP-25 within the recently identified region I and region II...... was disinhibited by region I mutation and found to correlate with defective complexin (Cpx) clamping in vitro, pointing to an interdependent role of synaptotagmin and Cpx in release clamping. Therefore, vesicle priming, clamping spontaneous release, and eliciting evoked release are three different functions of syt...

  15. Neurosteroid modulation of neuronal excitability and synaptic transmission in the rat medial vestibular nuclei.

    Science.gov (United States)

    Grassi, Silvarosa; Frondaroli, Adele; Dieni, Cristina; Dutia, Mayank B; Pettorossi, Vito E

    2007-07-01

    In rat brainstem slices, we investigated the influence of the neurosteroids tetrahydrodeoxycorticosterone (THDOC) and allopregnanolone (ALLO) on the synaptically driven and spontaneous activity of vestibular neurons, by analysing their effects on the amplitude of the field potentials evoked in the medial vestibular nuclei (MVN) by vestibular afferent stimulation and on the spontaneous firing rate of MVN neurons. Furthermore, the interaction with gamma-aminobutyric acid (GABA) and glutamate receptors was analysed by using specific antagonists for GABA(A) (bicuculline), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/ kainate [2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo(f)quinoxaline-7-sulphonamide disodium salt (NBQX)], N-methyl-D-aspartate (NMDA) [D-(-)-2-amino-5-phosphonopentanoic acid (AP-5)] and group I metabotropic glutamate receptors (mGlu-I) [(R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA)] receptors. THDOC and ALLO evoked two opposite long-lasting effects, consisting of either a potentiation or a reduction of field potential and firing rate, which showed early and late components, occurring in conjunction or separately after neurosteroid application. The depressions depended on GABA(A) receptors, as they were abolished by bicuculline, while early potentiation involved glutamate AMPA/kainate receptors, as NBQX markedly reduced the incidence of early firing rate enhancement and, in the case of ALLO, even provoked depression. This suggests that THDOC and ALLO enhance the GABA(A) inhibitory influence on the MVN neurons and facilitate the AMPA/kainate facilitatory one. Conversely, a late potentiation effect, which was still induced after glutamate and GABA(A) receptor blockade, might involve a different mechanism. We conclude that the modulation of neuronal activity in the MVN by THDOC and ALLO, through their actions on GABA(A) and AMPA/kainate receptors, may have a physiological role in regulating the vestibular system function under normal

  16. Protease activated receptors (PARS) mediation in gyroxin biological activity

    International Nuclear Information System (INIS)

    Silva, Jose Alberto Alves da

    2009-01-01

    Gyroxin is a serine protease enzyme from the South American rattlesnake (Crotalus durissus terrificus) venom; it is only partially characterized and has multiple activities. Gyroxin induces blood coagulation, blood pressure decrease and a neurotoxic behavior named barrel rotation. The mechanisms involved in this neurotoxic activity are not known. Whereas gyroxin is a member of enzymes with high potential to become a new drug with clinical applications such as thrombin, batroxobin, ancrod, tripsyn and kalicrein, it is important to find out how gyroxin works. The analysis on agarose gel electrophoresis and circular dichroism confirmed the molecules' integrity and purity. The gyroxin intravenous administration in mice proved its neurotoxicity (barrel rotation). In vivo studies employing intravital microscopy proved that gyroxin induces vasodilation with the participation of protease activated receptors (PARs), nitric oxide and Na+K+ATPase. The leukocytes' adherence and rolling counting indicated that gyroxin has no pro inflammatory activity. Gyroxin induced platelet aggregation, which was blocked by inhibitors of PAR1 and PAR4 receptors (SCH 79797 and tcY-NH 2 , respectively). Finally, it was proved that the gyroxin temporarily alter the permeability of the blood brain barrier (BBB). Our study has shown that both the protease-activated receptors and nitric oxide are mediators involved in the biological activities of gyroxin. (author)

  17. High throughput techniques for discovering new glycine receptor modulators and their binding sites

    Directory of Open Access Journals (Sweden)

    Daniel F Gilbert

    2009-10-01

    Full Text Available The inhibitory glycine receptor (GlyR is a member of the Cys-loop receptor family that mediates inhibitory neurotransmission in the central nervous system. These receptors are emerging as potential drug targets for inflammatory pain, immunomodulation, spasticity and epilepsy. Antagonists that specifically inhibit particular GlyR isoforms are also required as pharmacological probes for elucidating the roles of particular GlyR isoforms in health and disease. Although a substantial number of both positive and negative GlyR modulators have been identified, very few of these are specific for the GlyR over other receptor types. Thus, the potential of known compounds as either therapeutic leads or pharmacological probes is limited. It is therefore surprising that there have been few published studies describing attempts to discover novel GlyR isoform-specific compounds. The first aim of this review is to consider various methods for efficiently screening compounds against these receptors. We conclude that an anion sensitive yellow fluorescent protein is optimal for primary screening and that automated electrophysiology of cells stably expressing GlyRs is useful for confirming hits and quantitating the actions of identified compounds. The second aim of this review is to demonstrate how these techniques are used in our laboratory for the purpose of both discovering novel GlyR-active compounds and characterizing their binding sites. We also describe a reliable, cost effective method for transfecting HEK293 cells in single wells of a 384 well plate using nanogram quantities of cDNA.

  18. Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

    Directory of Open Access Journals (Sweden)

    Stephan Schmidt

    2015-05-01

    Full Text Available Many biological functions at cell level are mediated by the glycocalyx, a dense carbohydrate-presenting layer. In this layer specific interactions between carbohydrate ligands and protein receptors are formed to control cell–cell recognition, cell adhesion and related processes. The aim of this work is to shed light on the principles of complex formation between surface anchored carbohydrates and receptor surfaces by measuring the specific adhesion between surface bound mannose on a concanavalin A (ConA layer via poly(ethylene glycol-(PEG-based soft colloidal probes (SCPs. Special emphasis is on the dependence of multivalent presentation and density of carbohydrate units on specific adhesion. Consequently, we first present a synthetic strategy that allows for controlled density variation of functional groups on the PEG scaffold using unsaturated carboxylic acids (crotonic acid, acrylic acid, methacrylic acid as grafting units for mannose conjugation. We showed by a range of analytic techniques (ATR–FTIR, Raman microscopy, zeta potential and titration that this synthetic strategy allows for straightforward variation in grafting density and grafting length enabling the controlled presentation of mannose units on the PEG network. Finally we determined the specific adhesion of PEG-network-conjugated mannose units on ConA surfaces as a function of density and grafting type. Remarkably, the results indicated the absence of a molecular-level enhancement of mannose/ConA interaction due to chelate- or subsite-binding. The results seem to support the fact that weak carbohydrate interactions at mechanically flexible interfaces hardly undergo multivalent binding but are simply mediated by the high number of ligand–receptor interactions.

  19. The CB1 Receptor as an Important Mediator of Hedonic Reward Processing

    Science.gov (United States)

    Friemel, Chris M; Zimmer, Andreas; Schneider, Miriam

    2014-01-01

    The endocannabinoid (ECB) system has emerged recently as a key mediator for reward processing. It is well known that cannabinoids affect appetitive learning processes and can induce reinforcing and rewarding effects. However, the involvement of the ECB system in hedonic aspects of reward-related behavior is not completely understood. With the present study, we investigated the modulatory role of the ECB system on hedonic perception, measured by the pleasure attenuated startle (PAS) paradigm for a palatable food reward. Here, a conditioned odor is thought to induce a pleasant affective state that attenuates an aversive reflex—the acoustic startle response. Modulatory effects of the CB1 receptor antagonist/inverse agonist SR1411716 and the cannabinoid agonist WIN 55 212-2 on PAS were examined in rats. PAS was also measured in CB1 receptor knockout (KO) and wild-type (WT) mice. Pharmacological inhibition as well as the absence of CB1 receptors was found to reduce PAS, whereas WIN 55 212-2 administration increased PAS. Finally, presentation of a conditioned reward cue was found to induce striatal FosB/ΔFosB expression in WT mice, but not in KO mice, indicating a reduced stimulation of reward-related brain regions in conditioned KO mice by odor presentation. We here show that in addition to our previous studies in rats, PAS may also serve as a valuable and suitable measure to assess hedonic processing in mice. Our data further indicate that the ECB system, and in particular CB1 receptor signaling, appears to be highly important for the mediation of hedonic aspects of reward processing. PMID:24718372

  20. Beta receptor-mediated modulation of the late positive potential in humans.

    Science.gov (United States)

    de Rover, Mischa; Brown, Stephen B R E; Boot, Nathalie; Hajcak, Greg; van Noorden, Martijn S; van der Wee, Nic J A; Nieuwenhuis, Sander

    2012-02-01

    Electrophysiological studies have identified a scalp potential, the late positive potential (LPP), which is modulated by the emotional intensity of observed stimuli. Previous work has shown that the LPP reflects the modulation of activity in extrastriate visual cortical structures, but little is known about the source of that modulation. The present study investigated whether beta-adrenergic receptors are involved in the generation of the LPP. We used a genetic individual differences approach (experiment 1) and a pharmacological manipulation (experiment 2) to test the hypothesis that the LPP is modulated by the activation of β-adrenergic receptors. In experiment 1, we found that LPP amplitude depends on allelic variation in the β1-receptor gene polymorphism. In experiment 2, we found that LPP amplitude was modulated by the β-blocker propranolol in a direction dependent on subjects' level of trait anxiety: In participants with lower trait anxiety, propranolol led to a (nonsignificant) decrease in the LPP modulation; in participants with higher trait anxiety, propranolol increased the emotion-related LPP modulation. These results provide initial support for the hypothesis that the LPP reflects the downstream effects, in visual cortical areas, of β-receptor-mediated activation of the amygdala.

  1. Functional characterization and expression of thalamic GABA(B) receptors in a rodent model of Parkinson's disease

    NARCIS (Netherlands)

    de Groote, C; Wullner, U; Loschmann, PA; Luiten, PGM; Klockgether, T

    1999-01-01

    Increased GABAergic neurotransmission of the basal ganglia output nuclei projecting to the motor thalamus is thought to contribute to the pathophysiology of Parkinson's disease. We investigated the functional role of thalamic GABA(B) receptors in a rodent model of Parkinson's disease. First, we

  2. Serotonergic neurotransmission in emotional processing

    DEFF Research Database (Denmark)

    Laursen, Helle Ruff; Henningsson, Susanne; Macoveanu, Julian

    2016-01-01

    ,4-methylene-dioxymethamphetamine [MDMA]) induces alterations in serotonergic neurotransmission that are comparable to those observed in a depleted state. In this functional magnetic resonance imaging (fMRI) study, we investigated the responsiveness of the amygdala to emotional face stimuli in recreational...... ecstasy users as a model of long-term serotonin depletion. Fourteen ecstasy users and 12 non-using controls underwent fMRI to measure the regional neural activity elicited in the amygdala by male or female faces expressing anger, disgust, fear, sadness, or no emotion. During fMRI, participants made a sex...... judgement on each face stimulus. Positron emission tomography with (11)C-DASB was additionally performed to assess serotonin transporter (SERT) binding in the brain. In the ecstasy users, SERT binding correlated negatively with amygdala activity, and accumulated lifetime intake of ecstasy tablets...

  3. Investigation of the GPR39 zinc receptor following inhibition of monoaminergic neurotransmission and potentialization of glutamatergic neurotransmission

    DEFF Research Database (Denmark)

    Młyniec, Katarzyna; Gaweł, Magdalena; Librowski, Tadeusz

    2015-01-01

    Zinc can regulate neural function in the brain via the GPR39 receptor. In the present study we investigated whether inhibition of serotonin, noradrenaline and dopamine synthesis and potentialization of glutamate, via administration of p-chlorophenylalanine (pCPA), α-methyl-p-tyrosine (αMT) and N......-methyl-d-aspartatic acid (NMDA), respectively, would cause changes in GPR39 levels. Western blot analysis showed GPR39 up-regulation following 3-day administration of αMT and NMDA in the frontal cortex, and GPR39 down-regulation following 10-day administration of pCPA, αMT, and NMDA in the hippocampus of CD-1 mice....... There were no changes in serum zinc levels. Additionally, we investigated tryptophan, tyrosine and glutamate concentrations in the hippocampus and frontal cortex of GPR39 knockout (GPR39 KO) mice. Liquid chromatography-mass spectrometry (LC-MS) showed a significant decrease in tryptophan and tyrosine...

  4. The overexpressed human 46-kDa mannose 6-phosphate receptor mediates endocytosis and sorting of β-glucuronidase

    International Nuclear Information System (INIS)

    Watanabe, H.; Grubb, J.H.; Sly, W.S.

    1990-01-01

    The authors studied the function of the human small (46-kDa) mannose 6-phosphate receptor (SMPR) in transfected mouse L cells that do not express the larger insulin-like growth factor II/mannose 6-phosphate receptor. Cells overexpressing human SMPR were studied for enzyme binding to cell surface receptors, for binding to intracellular receptors in permeabilized cells, and for receptor-mediated endocytosis of recombinant human β-glucuronidase. Specific binding to human SMPR in permeabilized cells showed a pH optimum between pH 6.0 and pH 6.5. Binding was significant in the present of EDTA but was enhanced by added divalent cations. Up to 2.3% of the total functional receptor could be detected on the cell surface by enzyme binding. They present experiments showing that at very high levels of overexpression, and at pH 6.5, human SMPR mediated the endocytosis of β-glucuronidase. At pH 7.5, the rate of endocytosis was only 14% the rate seen at pH 6.5. Cells overexpressing human SMPR also showed reduced secretion of newly synthesized β-glucuronidase when compared to cells transfected with vector only, suggesting that overexpressed human SMPR can participate in sorting of newly synthesized β-glucuronidase and partially correct the sorting defect in mouse L cells that do not express the insulin-like growth factor II/mannose 6-phosphate receptor

  5. The Role of Adenosine Receptors in Psychostimulant Addiction

    Directory of Open Access Journals (Sweden)

    Inmaculada Ballesteros-Yáñez

    2018-01-01

    Full Text Available Adenosine receptors (AR are a family of G-protein coupled receptors, comprised of four members, named A1, A2A, A2B, and A3 receptors, found widely distributed in almost all human body tissues and organs. To date, they are known to participate in a large variety of physiopathological responses, which include vasodilation, pain, and inflammation. In particular, in the central nervous system (CNS, adenosine acts as a neuromodulator, exerting different functions depending on the type of AR and consequent cellular signaling involved. In terms of molecular pathways and second messengers involved, A1 and A3 receptors inhibit adenylyl cyclase (AC, through Gi/o proteins, while A2A and A2B receptors stimulate it through Gs proteins. In the CNS, A1 receptors are widely distributed in the cortex, hippocampus, and cerebellum, A2A receptors are localized mainly in the striatum and olfactory bulb, while A2B and A3 receptors are found at low levels of expression. In addition, AR are able to form heteromers, both among themselves (e.g., A1/A2A, as well as with other subtypes (e.g., A2A/D2, opening a whole range of possibilities in the field of the pharmacology of AR. Nowadays, we know that adenosine, by acting on adenosine A1 and A2A receptors, is known to antagonistically modulate dopaminergic neurotransmission and therefore reward systems, being A1 receptors colocalized in heteromeric complexes with D1 receptors, and A2A receptors with D2 receptors. This review documents the present state of knowledge of the contribution of AR, particularly A1 and A2A, to psychostimulants-mediated effects, including locomotor activity, discrimination, seeking and reward, and discuss their therapeutic relevance to psychostimulant addiction. Studies presented in this review reinforce the potential of A1 agonists as an effective strategy to counteract psychostimulant-induced effects. Furthermore, different experimental data support the hypothesis that A2A/D2 heterodimers are

  6. Glutamate requires NMDA receptors to modulate alpha2 adrenoceptor in medulla oblongata cultured cells of newborn rats.

    Science.gov (United States)

    Marinho da Silva, Sergio; Carrettiero, Daniel C; Chadi, Débora R F

    2014-04-03

    α2 Adrenoceptors (α2-ARs) are important in regulating the central control of blood pressure in medulla oblongata. However, it is unclear how this receptor is modulated by different receptors, especially the glutamatergic. In the present study, we studied the influence of ionotropic glutamatergic receptors over the α2-ARs in cultured cells of the medulla oblongata of newborn rats. For this purpose, the protein level of the α2-ARs was assessed after administration to the cultured cells of glutamate (glu), the agonists NMDA and kainate (KA), the NMDA receptor antagonist MK801 and the KA receptor antagonist DNQX. Results indicate that the α2-AR protein levels were increased after the treatments with glu and NMDA, and the addition of MK801 to this treatment thwarted this increase. Notwithstanding the fact that KA did not alter the receptor protein level, the combined treatment of DNQX with glu prevented the α2-AR protein modulation. In conclusion, the present study suggests that ionotropic glutamatergic receptors could be related to the α2-AR protein regulation in the medulla oblongata. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. {delta}-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Anika; Ammer, Hermann [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany); Eisinger, Daniela A., E-mail: eisinger@pharmtox.vetmed.uni-muenchen.de [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany)

    2009-07-15

    {delta}-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen{sup 2,5}]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G{sub i/o} proteins, because pre-treatment with pertussis toxin, but not over-expression of the G{sub q/11} scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the G{beta}{gamma} scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  8. δ-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    International Nuclear Information System (INIS)

    Heiss, Anika; Ammer, Hermann; Eisinger, Daniela A.

    2009-01-01

    δ-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen 2,5 ]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G i/o proteins, because pre-treatment with pertussis toxin, but not over-expression of the G q/11 scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the Gβγ scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  9. Effects of LHRH and ANG II on prolactin stimulation are mediated by hypophysial AT1 receptor subtype.

    Science.gov (United States)

    Becú-Villalobos, D; Lacau-Mengido, I M; Thyssen, S M; Díaz-Torga, G S; Libertun, C

    1994-02-01

    We have used the nonpeptide angiotensin II (ANG II) receptor antagonists losartan (receptor subtype AT1) and PD-123319 (AT2) to determine the participation of ANG II receptor subtypes in luteinizing hormone-releasing hormone (LHRH)-induced prolactin release in a perifusion study using intact pituitaries in vitro. LHRH (1.85 x 10(-7) M) released prolactin consistently, whereas losartan (10(-5) M) abolished prolactin response without modifying basal prolactin or luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. PD-123319 (10(-5) M) had no effect on basal or LHRH-induced prolactin, LH, or FSH release. We also determined that the effect of ANG II on prolactin release was mediated by the same receptor subtype. In adenohypophysial cells dispersed in vitro ANG II (10(-8) M) released prolactin. Losartan (10(-7) and 10(-6) M), but not PD-123319, inhibited this effect. We conclude that in intact hypophyses of 15-day-old female rats the effect of LHRH on prolactin release is readily demonstrated. LHRH-induced prolactin release appears to be mediated by ANG II acting in a paracrine manner on AT1 receptors located on lactotrophs.

  10. Multifunctional pH-Responsive Folate Receptor Mediated Polymer Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Cai, Xiaoqing; Yang, Xiaoye; Wang, Fang; Zhang, Chen; Sun, Deqing; Zhai, Guangxi

    2016-07-01

    Multifunctional pH-responsive folate receptor mediated targeted polymer nanoparticles (TPNps) were developed for docetaxel (DTX) delivery based on poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)poly (β-amino ester) (P123-PAE) and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)-folate (P123-FA) copolymers. The DTX was loaded into the TPNps with a decent drug loading content of 15.02 ± 0.14 wt%. In vitro drug release results showed that the DTX was released from the TPNps at a pH-dependent manner. Tetrazolium dye (MTT) assay revealed that the bland polymer nanoparticles displayed almost nontoxicity at 200 μg/mL concentration. However, the DTX-loaded TPNps showed high anti-tumor activity at low IC50 (0.72 μg/mL) for MCF-7 cells following 48 h incubation. Cellular uptake experiments revealed that the TPNps had higher degree of cellular uptake than nontargeted polymer nanoparticles, indicating that the nanoparticles were internalized into the cells via FA receptor-mediated endocytosis. Moreover, the cellular uptake pathways for the FA grafted polymer were involved in energy-dependent, clathrin-mediated and caveolae-mediated endocytosis. The cell killing effect and cellular uptake of the DTX-TPNps by the MCF-7 cells were all enhanced by about two folds at pH 5.5 when compared with pH 7.4. The TPNps also significantly prolonged the in vivo retention time for the DTX. These results suggest that the biocompatible pH responsive folate-modified polymer nanoparticles present a promising safe nanosystem for intracellular targeted delivery of DTX.

  11. GABA(A) receptors mediate orexin-A induced stimulation of food intake.

    Science.gov (United States)

    Kokare, Dadasaheb M; Patole, Angad M; Carta, Anna; Chopde, Chandrabhan T; Subhedar, Nishikant K

    2006-01-01

    Although the role of orexins in sleep/wake cycle and feeding behavior is well established, underlying mechanisms have not been fully understood. An attempt has been made to investigate the role of GABA(A) receptors and their benzodiazepine site on the orexin-A induced response to feeding. Different groups of rats were food deprived overnight and next day injected intracerebroventricularly (icv) with vehicle (artificial CSF; 5 microl/rat) or orexin-A (20-50 nM/rat) and the animals were given free access to food. Cumulative food intake was measured during light phase of light/dark cycle at 1-, 2-, 4- and 6-h post-injection time points. Orexin-A (30-50 nM/rat, icv) stimulated food intake at all the time points (P GABA(A) receptor agonists muscimol (25 ng/rat, icv) and diazepam (0.5 mg/kg, ip) at subeffective doses significantly potentiated the hyperphagic effect of orexin-A (30 nM/rat, icv). However, the effect was negated by the GABA(A) receptor antagonist bicuculline (1 mg/kg, ip). Interestingly, benzodiazepine receptor antagonist flumazenil (5 ng/rat, icv), augmented the orexin-A (30 nM/rat, icv) induced hyperphagia; the effect may be attributed to the intrinsic activity of the agent. The results suggest that the hyperphagic effect of orexin-A, at least in part, is mediated by enhanced GABA(A) receptor activity.

  12. Dopamine and μ-opioid receptor dysregulation in the brains of binge-eating female rats - possible relevance in the psychopathology and treatment of binge-eating disorder.

    Science.gov (United States)

    Heal, David J; Hallam, Michelle; Prow, Michael; Gosden, Jane; Cheetham, Sharon; Choi, Yong K; Tarazi, Frank; Hutson, Peter

    2017-06-01

    Adult, female rats given irregular, limited access to chocolate develop binge-eating behaviour with normal bodyweight and compulsive/perseverative and impulsive behaviours similar to those in binge-eating disorder. We investigated whether (a) dysregulated central nervous system dopaminergic and opioidergic systems are part of the psychopathology of binge-eating and (b) these neurotransmitter systems may mediate the actions of drugs ameliorating binge-eating disorder psychopathology. Binge-eating produced a 39% reduction of striatal D 1 receptors with 22% and 23% reductions in medial and lateral caudate putamen and a 22% increase of striatal μ-opioid receptors. There was no change in D 1 receptor density in nucleus accumbens, medial prefrontal cortex or dorsolateral frontal cortex, striatal D 2 receptors and dopamine reuptake transporter sites, or μ-opioid receptors in frontal cortex. There were no changes in ligand affinities. The concentrations of monoamines, metabolites and estimates of dopamine (dopamine/dihydroxyphenylacetic acid ratio) and serotonin/5-hydroxyindolacetic acid ratio turnover rates were unchanged in striatum and frontal cortex. However, turnover of dopamine and serotonin in the hypothalamus was increased ~20% and ~15%, respectively. Striatal transmission via D 1 receptors is decreased in binge-eating rats while μ-opioid receptor signalling may be increased. These changes are consistent with the attenuation of binge-eating by lisdexamfetamine, which increases catecholaminergic neurotransmission, and nalmefene, a μ-opioid antagonist.

  13. Action of naftopidil on spinal serotonergic neurotransmission for inhibition of the micturition reflex in rats.

    Science.gov (United States)

    Sugaya, Kimio; Nishijima, Saori; Kadekawa, Katsumi; Ashitomi, Katsuhiro; Ueda, Tomoyuki; Yamamoto, Hideyuki; Hattori, Tsuyoshi

    2017-03-01

    We examined the mechanism of action of naftopidil, an α1D/A blocker, on spinal descending serotonergic neurotransmission for the micturition reflex. We examined (1) urinary 5-hydroxyindole acetic acid (5-HIAA) after intraperitoneal administration of saline, para-chlorophenylalanine (PCPA; a serotonin synthetic enzyme inhibitor), and/or 5-hydroxytryptophan (5-HTP; a serotonin precursor); (2) isovolumetric cystometry after intraperitoneal administration of saline, PCPA, and/or 5-HTP and intravenous injection of naftopidil; and (3) isovolumetric cystometry before and after intrathecal administration of serotonin (5-HT) receptor antagonists and intravenous injection of naftopidil. PCPA decreased and 5-HTP increased urinary 5-HIAA/creatinine. Intraperitoneal injection of PCPA did not influence cystometric parameters. Intraperitoneal injection of 5-HTP significantly shortened the interval between bladder contractions. Intravenous injection of naftopidil transiently abolished bladder contractions. However, the duration of abolishment of bladder contractions after injection of naftopidil in rats given PCPA was significantly shorter than that in rats given vehicle, but significantly longer than that in rats given PCPA and 5-HTP. Intrathecal injection of 5-HT1B, 5-HT3, or 5-HT7 receptor antagonists significantly prolonged the interval between bladder contractions. Intrathecal injection of 5-HT1D or 5-HT2B receptor antagonists significantly shortened the interval between bladder contractions. Combined administration of the maximum non-effective dose of 5-HT1D, 5-HT2A, 5-HT2B, 5-HT2C, or 5-HT3 receptor antagonists and intravenous injection of naftopidil significantly shortened the duration of abolishment of bladder contraction compared to intravenous injection of naftopidil alone. Naftopidil may inhibit the micturition reflex via 5-HT1D, 5-HT2A, 5-HT2B, 5-HT2C, and 5-HT3 receptors in the spinal cord. Neurourol. Urodynam. 36:604-609, 2017. © 2016 Wiley Periodicals, Inc.

  14. TRIM32 promotes retinoic acid receptor α-mediated differentiation in human promyelogenous leukemic cell line HL60

    International Nuclear Information System (INIS)

    Sato, Tomonobu; Okumura, Fumihiko; Iguchi, Akihiro; Ariga, Tadashi; Hatakeyama, Shigetsugu

    2012-01-01

    Highlights: ► TRIM32 enhanced RARα-mediated transcriptional activity even in the absence of RA. ► TRIM32 stabilized RARα in the human promyelogenous leukemic cell line HL60. ► Overexpression of TRIM32 in HL60 cells induced granulocytic differentiation. ► TRIM32 may function as a coactivator for RARα-mediated transcription in APL cells. -- Abstract: Ubiquitination, one of the posttranslational modifications, appears to be involved in the transcriptional activity of nuclear receptors including retinoic acid receptor α (RARα). We previously reported that an E3 ubiquitin ligase, TRIM32, interacts with several important proteins including RARα and enhances transcriptional activity of RARα in mouse neuroblastoma cells and embryonal carcinoma cells. Retinoic acid (RA), which acts as a ligand to nuclear receptors including RARα, plays crucial roles in development, differentiation, cell cycles and apoptosis. In this study, we found that TRIM32 enhances RARα-mediated transcriptional activity even in the absence of RA and stabilizes RARα in the human promyelogenous leukemic cell line HL60. Moreover, we found that overexpression of TRIM32 in HL60 cells suppresses cellular proliferation and induces granulocytic differentiation even in the absence of RA. These findings suggest that TRIM32 functions as one of the coactivators for RARα-mediated transcription in acute promyelogenous leukemia (APL) cells, and thus TRIM32 may become a potentially therapeutic target for APL.

  15. Autocrine EGF receptor activation mediates endothelial cell migration and vascular morphogenesis induced by VEGF under interstitial flow

    International Nuclear Information System (INIS)

    Semino, Carlos E.; Kamm, Roger D.; Lauffenburger, Douglas A.

    2006-01-01

    We show here that autocrine ligand activation of epidermal growth factor (EGF) receptor in combination with interstitial flow is critically involved in the morphogenetic response of endothelial cells to VEGF stimulation. Human umbilical vein endothelial cell (HUVEC) monolayers cultured on a collagen gel and exposed to low interstitial flow in the absence of EGF and VEGF remained viable and mitotic but exhibited little evidence of vascular morphogenesis. Addition of VEGF produced a flow-dependent morphogenetic response within 48 to 72 h, characterized by branched capillary-like structures. The response was substantially abolished by inhibitors related to the autocrine EGF receptor pathway including Galardin, AG1478, PD98059, and an EGF receptor-blocking antibody, indicating that regulation of the morphogenetic process operates via autocrine EGF receptor activation. Moreover, we observed that in our system the EGF receptor was always activated independently of the interstitial flow, and, in addition, the EGF receptor inhibitors used above reduced the phosphorylation state of the receptor, correlating with inhibition of capillary morphogenesis. Finally, 5'bromo-2'-deoxyuridine (BrdU) labeling identified dividing cells at the monolayer but not in the extending capillary-like structures. EGF pathway inhibitors Galardin and AG1478 did not reduce BrdU incorporation in the monolayer, indicating that the EGF-receptor-mediated morphogenetic behavior is mainly due to cell migration rather than proliferation. Based on these results, we propose a two-step model for in vitro capillary morphogenesis in response to VEGF stimulation with interstitial fluid flow: monolayer maintenance by mitotic activity independent of EGF receptors and a migratory response mediated by autocrine EGF receptor activation wherein cells establish capillary-like structures

  16. Synthesis and in vitro pharmacology at AMPA and kainate preferring glutamate receptors of 4-heteroarylmethylidene glutamate analogues

    DEFF Research Database (Denmark)

    Valgeirsson, Jon; Christensen, Jeppe K; Kristensen, Anders S

    2003-01-01

    affinity for the GluR2 subtype of AMPA receptors. As an attempt to develop new pharmacological tools for studies of GluR5 receptors, (S)-E-4-(2-thiazolylmethylene)glutamic acid (4a) was designed as a structural hybrid between 1 and 3. 4a was shown to be a potent GluR5 agonist and a high affinity ligand...

  17. Developmental changes in GABAergic neurotransmission to presympathetic and cardiac parasympathetic neurons in the brainstem.

    Science.gov (United States)

    Dergacheva, Olga; Boychuk, Carie R; Mendelowitz, David

    2013-08-01

    Cardiovascular function is regulated by a dynamic balance composed of sympathetic and parasympathetic activity. Sympathoexcitatory presympathetic neurons (PSNs) in the rostral ventrolateral medulla project directly to cardiac and vasomotor sympathetic preganglionic neurons in the spinal cord. In proximity to the PSNs in the medulla, there are preganglionic cardiac vagal neurons (CVNs) within the nucleus ambiguus, which are critical for parasympathetic control of heart rate. Both CVNs and PSNs receive GABAergic synaptic inputs that change with challenges such as hypoxia and hypercapnia (H/H). Autonomic control of cardiovascular function undergoes significant changes during early postnatal development; however, little is known regarding postnatal maturation of GABAergic neurotransmission to these neurons. In this study, we compared changes in GABAergic inhibitory postsynaptic currents (IPSCs) in CVNs and PSNs under control conditions and during H/H in postnatal day 2-5 (P5), 16-20 (P20), and 27-30 (P30) rats using an in vitro brainstem slice preparation. There was a significant enhancement in GABAergic neurotransmission to both CVNs and PSNs at age P20 compared with P5 and P30, with a more pronounced increase in PSNs. H/H did not significantly alter this enhanced GABAergic neurotransmission to PSNs in P20 animals. However, the frequency of GABAergic IPSCs in PSNs was reduced by H/H in P5 and P30 animals. In CVNs, H/H elicited an inhibition of GABAergic neurotransmission in all ages studied, with the most pronounced inhibition occurring at P20. In conclusion, there are critical development periods at which significant rearrangement occurs in the central regulation of cardiovascular function.

  18. Bicarbonate Contributes to GABAA Receptor-Mediated Neuronal Excitation in Surgically-Resected Human Hypothalamic Hamartomas

    Science.gov (United States)

    Do-Young, Kim; Fenoglio, Kristina A.; Kerrigan, John F.; Rho, Jong M.

    2009-01-01

    SUMMARY The role of bicarbonate (HCO3-) in GABAA receptor-mediated depolarization of human hypothalamic hamartoma (HH) neurons was investigated using cellular electrophysiological and calcium imaging techniques. Activation of GABAA receptors with muscimol (30 μM) provoked neuronal excitation in over 70% of large (18-22 μM) HH neurons in HCO3- buffer. Subsequent perfusion of HCO3--free HEPES buffer produced partial suppression of muscimol-induced excitation. Additionally, 53% of large HH neurons under HCO3--free conditions exhibited reduced intracellular calcium accumulation by muscimol. These results suggest that HCO3- efflux through GABAA receptors on a subpopulation of large HH neurons may contribute to membrane depolarization and subsequent activation of L-type calcium channels. PMID:19022626

  19. Evidence that 5-hydroxytryptamine3 receptors mediate cytotoxic drug and radiation-evoked emesis

    International Nuclear Information System (INIS)

    Miner, W.D.; Sanger, G.J.; Turner, D.H.

    1987-01-01

    The involvement of 5-hydroxytryptamine (5-HT) 5-HT 3 receptors in the mechanisms of severe emesis evoked by cytotoxic drugs or by total body irradiation have been studied in ferrets. Anti-emetic compounds tested were domperidone (a dopamine antagonist), metoclopramide (a gastric motility stimulant and dopamine antagonist at conventional doses, a 5-HT 3 receptor antagonist at higher doses) and BRL 24924 (a potent gastric motility stimulant and a 5-HT 3 receptor antagonist). Domperidone or metoclopramide prevented apomorphine-evoked emesis, whereas BRL 24924 did not. Similar doses of domperidone did not prevent emesis evoked by cis-platin or by total body irradiation, whereas metoclopramide or BRL 24924 greatly reduced or prevented these types of emesis. Metoclopramide and BRL 24924 also prevented emesis evoked by a combination of doxorubicin and cyclophosphamide. These results are discussed in terms of a fundamental role for 5-HT 3 receptors in the mechanisms mediating severely emetogenic cancer treatment therapies. (author)

  20. Prefrontal gamma-aminobutyric acid type A receptor insertion controls cue-induced relapse to nicotine seeking.

    Science.gov (United States)

    Lubbers, Bart R; van Mourik, Yvar; Schetters, Dustin; Smit, August B; De Vries, Taco J; Spijker, Sabine

    2014-11-01

    Current smoking cessation therapies offer limited success, as relapse rates remain high. Nicotine, which is the major component of tobacco smoke, is thought to be primarily responsible for the addictive properties of tobacco. However, little is known about the molecular mechanisms underlying nicotine relapse, hampering development of more effective therapies. The objective of this study was to elucidate the role of medial prefrontal cortex (mPFC) glutamatergic and gamma-aminobutyric acid (GABA)ergic receptors in controlling relapse to nicotine seeking. Using an intravenous self-administration model, we studied glutamate and gamma-aminobutyric acid receptor regulation in the synaptic membrane fraction of the rat mPFC following extinction and cue-induced relapse to nicotine seeking. Subsequently, we locally intervened at the level of GABAergic signaling by using a mimetic peptide of the GABA receptor associated protein-interacting domain of GABA type A (GABAA) receptor subunit γ2 (TAT-GABAγ2) and muscimol, a GABAA receptor agonist. Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and N-methyl-D-aspartate receptors were not regulated after the 30-min relapse test. However, GABAA receptor subunits α1 and γ2 were upregulated, and interference with GABAA receptor insertion in the cell membrane using the TAT-GABAγ2 peptide in the dorsal mPFC, but not the ventral mPFC, significantly increased responding during relapse. Increasing GABAA transmission with muscimol in the dorsal and ventral mPFC attenuated relapse. These data indicate that cue-induced relapse entails a GABAergic plasticity mechanism that limits nicotine seeking by restoring inhibitory control in the dorsal mPFC. GABAA receptor-mediated neurotransmission in the dorsal mPFC constitutes a possible future therapeutic target for maintaining smoking abstinence. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Modulation of Network Oscillatory Activity and GABAergic Synaptic Transmission by CB1 Cannabinoid Receptors in the Rat Medial Entorhinal Cortex

    Directory of Open Access Journals (Sweden)

    Nicola H. Morgan

    2008-01-01

    Full Text Available Cannabinoids modulate inhibitory GABAergic neurotransmission in many brain regions. Within the temporal lobe, cannabinoid receptors are highly expressed, and are located presynaptically at inhibitory terminals. Here, we have explored the role of type-1 cannabinoid receptors (CB1Rs at the level of inhibitory synaptic currents and field-recorded network oscillations. We report that arachidonylcyclopropylamide (ACPA; 10 M, an agonist at CB1R, inhibits GABAergic synaptic transmission onto both superficial and deep medial entorhinal (mEC neurones, but this has little effect on network oscillations in beta/gamma frequency bands. By contrast, the CB1R antagonist/inverse agonist LY320135 (500 nM, increased GABAergic synaptic activity and beta/gamma oscillatory activity in superficial mEC, was suppressed, whilst that in deep mEC was enhanced. These data indicate that cannabinoid-mediated effects on inhibitory synaptic activity may be constitutively active in vitro, and that modulation of CB1R activation using inverse agonists unmasks complex effects of CBR function on network activity.

  2. Effect of ARA9 on dioxin receptor mediated transcription

    International Nuclear Information System (INIS)

    Lees, M.J.; Whitelaw, M.L.

    2002-01-01

    The dioxin (Aryl hydrocarbon) receptor (DR) is a unique bHLH transcription factor which is activated by binding of planar aromatic hydrocarbons typified by dioxin (TCDD). The active receptor is key to metabolism of aryl hydrocarbon xenobiotics by being a potent inducer of CYP1A1 gene activity. Chlorinated dioxins are inert to metabolism and initiate multifarious toxicities, including potent tumour promotion. These ill-effects are mediated by the activated DR and we are studying the mechanisms by which the ligand binding domain of the DR controls activity of the protein. The DR ligand binding domain resides within a PAS (Per/Arnt/Sim homology) region which is contiguous with the bHLH. The latent bHLH/PAS dioxin receptor (DR) is found in the cytoplasm of most mammalian cell types in a complex with heat shock protein 90, a novel immunophilin like protein termed ARA9/XAP2/AIP, and the co-chaperone p23. Here we use antisense ARA9 constructs to reveal that in the absence of ARA9, the DR is unable to form a transcriptionally active complex. Co-expression of antisense ARA9 with a form of the DR which is constitutively targeted to the nucleus leads to dramatically decreased levels of the nuclear DR protein, implying that ARA9 may function beyond its currently proposed role in cytoplasmic retention of the latent DR

  3. Differential modulation of expression of nuclear receptor mediated genes by tris(2-butoxyethyl) phosphate (TBOEP) on early life stages of zebrafish (Danio rerio)

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhiyuan, E-mail: zhiyuan_nju@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Yu, Yijun, E-mail: yjun.yu@gmail.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Tang, Song [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Liu, Hongling, E-mail: hlliu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Su, Guanyong; Xie, Yuwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Giesy, John P. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Hecker, Markus [School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3 (Canada); Yu, Hongxia [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023 (China)

    2015-12-15

    Highlights: • Effects of TBOEP on expression of genes of several nuclear hormone receptors and their relationship with adverse effect pathways in zebrafish. • TBOEP was neither an agonist nor antagonist of AR or AhR as determined by use of in vitro mammalian cell-based receptor transactivation assays. • Modulation of ER- and MR-dependent pathways allowed for development of feasible receptor-mediated, critical mechanisms of toxic action. - Abstract: As one substitute for phased-out brominated flame retardants (BFRs), tris(2-butoxyethyl) phosphate (TBOEP) is frequently detected in aquatic organisms. However, knowledge about endocrine disrupting mechanisms associated with nuclear receptors caused by TBOEP remained restricted to results from in vitro studies with mammalian cells. In the study, results of which are presented here, embryos/larvae of zebrafish (Danio rerio) were exposed to 0.02, 0.1 or 0.5 μM TBOEP to investigate expression of genes under control of several nuclear hormone receptors (estrogen receptors (ERs), androgen receptor (AR), thyroid hormone receptor alpha (TRα), mineralocorticoid receptor (MR), glucocorticoid receptor (GR), aryl hydrocarbon (AhR), peroxisome proliferator-activated receptor alpha (PPARα), and pregnane × receptor (P × R)) pathways at 120 hpf. Exposure to 0.5 μM TBOEP significantly (p < 0.05, one-way analysis of variance) up-regulated expression of estrogen receptors (ERs, er1, er2a, and er2b) genes and ER-associated genes (vtg4, vtg5, pgr, ncor, and ncoa3), indicating TBOEP modulates the ER pathway. In contrast, expression of most genes (mr, 11βhsd, ube2i,and adrb2b) associated with the mineralocorticoid receptor (MR) pathway were significantly down-regulated. Furthermore, in vitro mammalian cell-based (MDA-kb2 and H4IIE-luc) receptor transactivation assays, were also conducted to investigate possible agonistic or antagonistic effects on AR- and AhR-mediated pathways. In mammalian cells, none of these pathways were

  4. Ligand Receptor-Mediated Regulation of Growth in Plants.

    Science.gov (United States)

    Haruta, Miyoshi; Sussman, Michael R

    2017-01-01

    Growth and development of multicellular organisms are coordinately regulated by various signaling pathways involving the communication of inter- and intracellular components. To form the appropriate body patterns, cellular growth and development are modulated by either stimulating or inhibiting these pathways. Hormones and second messengers help to mediate the initiation and/or interaction of the various signaling pathways in all complex multicellular eukaryotes. In plants, hormones include small organic molecules, as well as larger peptides and small proteins, which, as in animals, act as ligands and interact with receptor proteins to trigger rapid biochemical changes and induce the intracellular transcriptional and long-term physiological responses. During the past two decades, the availability of genetic and genomic resources in the model plant species, Arabidopsis thaliana, has greatly helped in the discovery of plant hormone receptors and the components of signal transduction pathways and mechanisms used by these immobile but highly complex organisms. Recently, it has been shown that two of the most important plant hormones, auxin and abscisic acid (ABA), act through signaling pathways that have not yet been recognized in animals. For example, auxins stimulate cell elongation by bringing negatively acting transcriptional repressor proteins to the proteasome to be degraded, thus unleashing the gene expression program required for increasing cell size. The "dormancy" inducing hormone, ABA, binds to soluble receptor proteins and inhibits a specific class of protein phosphatases (PP2C), which activates phosphorylation signaling leading to transcriptional changes needed for the desiccation of the seeds prior to entering dormancy. While these two hormone receptors have no known animal counterparts, there are also many similarities between animal and plant signaling pathways. For example, in plants, the largest single gene family in the genome is the protein kinase

  5. Stereostructure-activity studies on agonists at the AMPA and kainate subtypes of ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Johansen, Tommy N; Greenwood, Jeremy R; Frydenvang, Karla Andrea

    2003-01-01

    (S)-Glutamic acid (Glu), the major excitatory neurotransmitter in the central nervous system, operates through ionotropic as well as metabotropic receptors and is considered to be involved in certain neurological disorders and degenerative brain diseases that are currently without any satisfactory...

  6. NK cell cytotoxicity mediated by 2B4 and NTB-A is dependent on SAP acting downstream of receptor phosphorylation

    Directory of Open Access Journals (Sweden)

    Stephan eMeinke

    2013-01-01

    Full Text Available 2B4 (CD244 and NK-T-B-antigen (NTB-A, CD352 are activating receptors on human NK cells and belong to the family of SLAM-related receptors. Engagement of these receptors leads to phosphorylation of their cytoplasmic tails and recruitment of the adapter proteins SAP and EAT-2. X-linked lymphoproliferative syndrome (XLP is a severe immunodeficiency that results from mutations in the SAP gene. 2B4 and NTB-A-mediated cytotoxicity are abrogated in XLP NK cells. To elucidate the molecular basis for this defect we analyzed early signaling events in SAP knockdown cells. Similar to XLP NK cells, knockdown of SAP in primary human NK cells leads to a reduction of 2B4 and NTB-A-mediated cytotoxicity. We found that early signaling events such as raft recruitment and receptor phosphorylation are not affected by the absence of SAP, indicating the defect in the absence of SAP is downstream of these events. In addition, knockdown of EAT-2 does not impair 2B4 or NTB-A-mediated cytotoxicity. Surprisingly, EAT-2 recruitment to both receptors is abrogated in the absence of SAP, revealing a novel cooperativity between these adapters.

  7. Abnormal striatal dopaminergic neurotransmission during rest and task production in spasmodic dysphonia.

    Science.gov (United States)

    Simonyan, Kristina; Berman, Brian D; Herscovitch, Peter; Hallett, Mark

    2013-09-11

    Spasmodic dysphonia is a primary focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. The pathophysiology of spasmodic dysphonia is thought to involve structural and functional abnormalities in the basal ganglia-thalamo-cortical circuitry; however, neurochemical correlates underpinning these abnormalities as well as their relations to spasmodic dysphonia symptoms remain unknown. We used positron emission tomography with the radioligand [(11)C]raclopride (RAC) to study striatal dopaminergic neurotransmission at the resting state and during production of symptomatic sentences and asymptomatic finger tapping in spasmodic dysphonia patients. We found that patients, compared to healthy controls, had bilaterally decreased RAC binding potential (BP) to striatal dopamine D2/D3 receptors on average by 29.2%, which was associated with decreased RAC displacement (RAC ΔBP) in the left striatum during symptomatic speaking (group average difference 10.2%), but increased RAC ΔBP in the bilateral striatum during asymptomatic tapping (group average difference 10.1%). Patients with more severe voice symptoms and subclinically longer reaction time to initiate the tapping sequence had greater RAC ΔBP measures, while longer duration of spasmodic dysphonia was associated with a decrease in task-induced RAC ΔBP. Decreased dopaminergic transmission during symptomatic speech production may represent a disorder-specific pathophysiological trait involved in symptom generation, whereas increased dopaminergic function during unaffected task performance may be explained by a compensatory adaptation of the nigrostriatal dopaminergic system possibly due to decreased striatal D2/D3 receptor availability. These changes can be linked to the clinical and subclinical features of spasmodic dysphonia and may represent the neurochemical basis of basal ganglia alterations in this disorder.

  8. Functional characterization of GABAA receptor-mediated modulation of cortical neuron network activity in microelectrode array recordings

    DEFF Research Database (Denmark)

    Bader, Benjamin M; Steder, Anne; Klein, Anders Bue

    2017-01-01

    The numerous γ-aminobutyric acid type A receptor (GABAAR) subtypes are differentially expressed and mediate distinct functions at neuronal level. In this study we have investigated GABAAR-mediated modulation of the spontaneous activity patterns of primary neuronal networks from murine frontal...... of the information extractable from the MEA recordings offers interesting insights into the contributions of various GABAAR subtypes/subgroups to cortical network activity and the putative functional interplay between these receptors in these neurons....... cortex by characterizing the effects induced by a wide selection of pharmacological tools at a plethora of activity parameters in microelectrode array (MEA) recordings. The basic characteristics of the primary cortical neurons used in the recordings were studied in some detail, and the expression levels...

  9. Induction of osteoblast differentiation by selective activation of kinase-mediated actions of the estrogen receptor.

    Science.gov (United States)

    Kousteni, Stavroula; Almeida, Maria; Han, Li; Bellido, Teresita; Jilka, Robert L; Manolagas, Stavros C

    2007-02-01

    Estrogens control gene transcription by cis or trans interactions of the estrogen receptor (ER) with target DNA or via the activation of cytoplasmic kinases. We report that selective activation of kinase-mediated actions of the ER with 4-estren-3alpha,17beta-diol (estren) or an estradiol-dendrimer conjugate, each a synthetic compound that stimulates kinase-mediated ER actions 1,000 to 10,000 times more potently than direct DNA interactions, induced osteoblastic differentiation in established cell lines of uncommitted osteoblast precursors and primary cultures of osteoblast progenitors by stimulating Wnt and BMP-2 signaling in a kinase-dependent manner. In sharp contrast, 17beta-estradiol (E(2)) suppressed BMP-2-induced osteoblast progenitor commitment and differentiation. Consistent with the in vitro findings, estren, but not E(2), stimulated Wnt/beta-catenin-mediated transcription in T-cell factor-lacZ transgenic mice. Moreover, E(2) stimulated BMP signaling in mice in which ERalpha lacks DNA binding activity and classical estrogen response element-mediated transcription (ERalpha(NERKI/-)) but not in wild-type controls. This evidence reveals for the first time the existence of a large signalosome in which inputs from the ER, kinases, bone morphogenetic proteins, and Wnt signaling converge to induce differentiation of osteoblast precursors. ER can either induce it or repress it, depending on whether the activating ligand (and presumably the resulting conformation of the receptor protein) precludes or accommodates ERE-mediated transcription.

  10. Functional significance of brain glycogen in sustaining glutamatergic neurotransmission.

    Science.gov (United States)

    Sickmann, Helle M; Walls, Anne B; Schousboe, Arne; Bouman, Stephan D; Waagepetersen, Helle S

    2009-05-01

    The involvement of brain glycogen in sustaining neuronal activity has previously been demonstrated. However, to what extent energy derived from glycogen is consumed by astrocytes themselves or is transferred to the neurons in the form of lactate for oxidative metabolism to proceed is at present unclear. The significance of glycogen in fueling glutamate uptake into astrocytes was specifically addressed in cultured astrocytes. Moreover, the objective was to elucidate whether glycogen derived energy is important for maintaining glutamatergic neurotransmission, induced by repetitive exposure to NMDA in co-cultures of cerebellar neurons and astrocytes. In the astrocytes it was shown that uptake of the glutamate analogue D-[3H]aspartate was impaired when glycogen degradation was inhibited irrespective of the presence of glucose, signifying that energy derived from glycogen degradation is important for the astrocytic compartment. By inhibiting glycogen degradation in co-cultures it was evident that glycogen provides energy to sustain glutamatergic neurotransmission, i.e. release and uptake of glutamate. The relocation of glycogen derived lactate to the neuronal compartment was investigated by employing d-lactate, a competitive substrate for the monocarboxylate transporters. Neurotransmitter release was affected by the presence of d-lactate indicating that glycogen derived energy is important not only in the astrocytic but also in the neuronal compartment.

  11. Serotonin 5HT1A receptor availability and pathological crying after stroke

    DEFF Research Database (Denmark)

    Møller, Mette; Andersen, G; Gjedde, A

    2007-01-01

    OBJECTIVES: Post-stroke depression and pathological crying (PC) implicate an imbalance of serotonergic neurotransmission. We claim that PC follows serotonin depletion that raises the binding potential (p(B)) of the 5-HT(1A) receptor antagonist [carbonyl-(11)C]WAY-100635, which is reversible...... by selective serotonin re-uptake inhibitor (SSRI) treatment. MATERIALS AND METHODS: We PET scanned patients with acute stroke and PC and age-matched control subjects. Maps of receptor availability were generated from the images of eight cortical regions and raphe nuclei. RESULTS: The maps showed highest...

  12. Type 1 cannabinoid receptor mapping with [18F]MK-9470 PET in the rat brain after quinolinic acid lesion: a comparison to dopamine receptors and glucose metabolism

    International Nuclear Information System (INIS)

    Casteels, Cindy; Martinez, Emili; Camon, Lluisa; Vera, Nuria de; Planas, Anna M.; Bormans, Guy; Baekelandt, Veerle; Laere, Koen van

    2010-01-01

    Several lines of evidence imply early alterations in metabolic, dopaminergic and endocannabinoid neurotransmission in Huntington's disease (HD). Using [ 18 F]MK-9470 and small animal PET, we investigated cerebral changes in type 1 cannabinoid (CB 1 ) receptor binding in the quinolinic acid (QA) rat model of HD in relation to glucose metabolism, dopamine D 2 receptor availability and amphetamine-induced turning behaviour. Twenty-one Wistar rats (11 QA and 10 shams) were investigated. Small animal PET acquisitions were conducted on a Focus 220 with approximately 18 MBq of [ 18 F]MK-9470, [ 18 F]FDG and [ 11 C]raclopride. Relative glucose metabolism and parametric CB 1 receptor and D 2 binding images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping (SPM2). In the QA model, [ 18 F]MK-9470 uptake, glucose metabolism and D 2 receptor binding were reduced in the ipsilateral caudate-putamen by 7, 35 and 77%, respectively (all p -5 ), while an increase for these markers was observed on the contralateral side (>5%, all p -4 ). [ 18 F]MK-9470 binding was also increased in the cerebellum (p = 2.10 -5 ), where it was inversely correlated to the number of ipsiversive turnings (p = 7.10 -6 ), suggesting that CB 1 receptor upregulation in the cerebellum is related to a better functional outcome. Additionally, glucose metabolism was relatively increased in the contralateral hippocampus, thalamus and sensorimotor cortex (p = 1.10 -6 ). These data point to in vivo changes in endocannabinoid transmission, specifically for CB 1 receptors in the QA model, with involvement of the caudate-putamen, but also distant regions of the motor circuitry, including the cerebellum. These data also indicate the occurrence of functional plasticity on metabolism, D 2 and CB 1 neurotransmission in the contralateral hemisphere. (orig.)

  13. Increased presynaptic regulation of dopamine neurotransmission in the nucleus accumbens core following chronic ethanol self-administration in female macaques

    Science.gov (United States)

    Siciliano, Cody A.; Calipari, Erin S.; Yorgason, Jordan T.; Lovinger, David M.; Mateo, Yolanda; Jimenez, Vanessa A.; Helms, Christa M.; Grant, Kathleen A.; Jones, Sara R.

    2016-01-01

    Rationale Hypofunction of striatal dopamine neurotransmission, or hypodopaminergia, is a consequence of excessive ethanol use, and is hypothesized to be a critical component of alcoholism, driving alcohol intake in an attempt to restore dopamine levels; however, the neurochemical mechanisms involved in these dopaminergic deficiencies are unknown. Objective Here we examined the specific dopaminergic adaptations that produce hypodopaminergia and contribute to alcohol use disorders using direct, sub-second measurements of dopamine signaling in nonhuman primates following chronic ethanol self-administration. Methods Female rhesus macaques completed one year of daily (22 hr/day) ethanol self-administration. Subsequently, fast-scan cyclic voltammetry was used in nucleus accumbens core brain slices to determine alterations in dopamine terminal function, including release and uptake kinetics, and sensitivity to quinpirole (D2/D3 dopamine receptor agonist) and U50,488 (kappa-opioid receptor agonist) induced inhibition of dopamine release. Results Ethanol drinking greatly increased uptake rates, which were positively correlated with lifetime ethanol intake. Furthermore, the sensitivity of dopamine D2/D3 autoreceptors and kappa-opioid receptors, which both act as negative regulators of presynaptic dopamine release, were moderately and robustly enhanced in ethanol drinkers. Conclusions Greater uptake rates and sensitivity to D2-type autoreceptor and kappa-opioid receptor agonists could converge to drive a hypodopaminergic state, characterized by reduced basal dopamine and an inability to mount appropriate dopaminergic responses to salient stimuli. Together, we outline the specific alterations to dopamine signaling that may drive ethanol-induced hypofunction of the dopamine system, and suggest that the dopamine and dynorphin/kappa-opioid receptor systems may be efficacious pharmcotherapeutic targets in the treatment of alcohol use disorders. PMID:26892380

  14. Increased presynaptic regulation of dopamine neurotransmission in the nucleus accumbens core following chronic ethanol self-administration in female macaques.

    Science.gov (United States)

    Siciliano, Cody A; Calipari, Erin S; Yorgason, Jordan T; Lovinger, David M; Mateo, Yolanda; Jimenez, Vanessa A; Helms, Christa M; Grant, Kathleen A; Jones, Sara R

    2016-04-01

    Hypofunction of striatal dopamine neurotransmission, or hypodopaminergia, is a consequence of excessive ethanol use and is hypothesized to be a critical component of alcoholism, driving alcohol intake in an attempt to restore dopamine levels; however, the neurochemical mechanisms involved in these dopaminergic deficiencies are not fully understood. Here we examined the specific dopaminergic adaptations that produce hypodopaminergia and contribute to alcohol use disorders using direct, sub-second measurements of dopamine signaling in nonhuman primates following chronic ethanol self-administration. Female rhesus macaques completed 1 year of daily (22 h/day) ethanol self-administration. Subsequently, fast-scan cyclic voltammetry was used in nucleus accumbens core brain slices to determine alterations in dopamine terminal function, including release and uptake kinetics, and sensitivity to quinpirole (D2/D3 dopamine receptor agonist) and U50,488 (kappa opioid receptor agonist) induced inhibition of dopamine release. Ethanol drinking greatly increased uptake rates, which were positively correlated with lifetime ethanol intake. Furthermore, the sensitivity of dopamine D2/D3 autoreceptors and kappa opioid receptors, which both act as negative regulators of presynaptic dopamine release, was moderately and robustly enhanced in ethanol drinkers. Greater uptake rates and sensitivity to D2-type autoreceptor and kappa opioid receptor agonists could converge to drive a hypodopaminergic state, characterized by reduced basal dopamine and an inability to mount appropriate dopaminergic responses to salient stimuli. Together, we outline the specific alterations to dopamine signaling that may drive ethanol-induced hypofunction of the dopamine system and suggest that the dopamine and dynorphin/kappa opioid receptor systems may be efficacious pharmacotherapeutic targets in the treatment of alcohol use disorders.

  15. Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat.

    Science.gov (United States)

    Korim, Willian Seiji; Ferreira-Neto, Marcos L; Pedrino, Gustavo R; Pilowsky, Paul M; Cravo, Sergio L

    2012-12-01

    In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.

  16. Enhanced NMDA receptor-mediated intracellular calcium signaling in magnocellular neurosecretory neurons in heart failure rats.

    Science.gov (United States)

    Stern, Javier E; Potapenko, Evgeniy S

    2013-08-15

    An enhanced glutamate excitatory function within the hypothalamic supraoptic and paraventricluar nuclei is known to contribute to increased neurosecretory and presympathetic neuronal activity, and hence, neurohumoral activation, during heart failure (HF). Still, the precise mechanisms underlying enhanced glutamate-driven neuronal activity in HF remain to be elucidated. Here, we performed simultaneous electrophysiology and fast confocal Ca²⁺ imaging to determine whether altered N-methyl-d-aspartate (NMDA) receptor-mediated changes in intracellular Ca²⁺ levels (NMDA-ΔCa²⁺) occurred in hypothalamic magnocellular neurosecretory cells (MNCs) in HF rats. We found that activation of NMDA receptors resulted in a larger ΔCa²⁺ in MNCs from HF when compared with sham rats. The enhanced NMDA-ΔCa²⁺ was neither dependent on the magnitude of the NMDA-mediated current (voltage clamp) nor on the degree of membrane depolarization or firing activity evoked by NMDA (current clamp). Differently from NMDA receptor activation, firing activity evoked by direct membrane depolarization resulted in similar changes in intracellular Ca²⁺ in sham and HF rats. Taken together, our results support a relatively selective alteration of intracellular Ca²⁺ homeostasis and signaling following activation of NMDA receptors in MNCs during HF. The downstream functional consequences of such altered ΔCa²⁺ signaling during HF are discussed.

  17. Hormonally-mediated Epigenetic Changes to Steroid Receptors in the Developing Brain: Implications for Sexual Differentiation

    Science.gov (United States)

    Nugent, Bridget M.; Schwarz, Jaclyn M.; McCarthy, Margaret M.

    2010-01-01

    The establishment of sex-specific neural morphology, which underlies sex-specific behaviors, occurs during a perinatal sensitive window in which brief exposure to gonadal steroid hormones produces permanent masculinization of the brain. In the rodent, estradiol derived from testicular androgens is a principle organizational hormone. The mechanism by which transient estradiol exposure induces permanent differences in neuronal anatomy has been widely investigated, but remains elusive. Epigenetic changes, such as DNA methylation, allow environmental influences to alter long-term gene expression patterns and therefore may be a potential mediator of estradiol-induced organization of the neonatal brain. Here we review data that demonstrate sex and estradiol-induced differences in DNA methylation on the estrogen receptor α (ERα), estrogen receptor β (ERβ), and progesterone receptor (PR) promoters in sexually dimorphic brain regions across development. Contrary to the overarching view of DNA methylation as a permanent modification directly tied to gene expression, these data demonstrate that methylation patterns on steroid hormone receptors change across the life span and do not necessarily predict expression. Although further exploration into the mechanism and significance of estradiol-induced alterations in DNA methylation patterns in the neonatal brain is necessary, these results provide preliminary evidence that epigenetic alterations can occur in response to early hormone exposure and may mediate estradiol-induced organization of sex differences in the neonatal brain. PMID:20800064

  18. Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons

    Science.gov (United States)

    Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Hirata, Hiromi; Moorhouse, Andrew J.; Ishibashi, Hitoshi

    2017-01-01

    Abstract Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system. PMID:28197549

  19. NR4A nuclear receptors mediate carnitine palmitoyltransferase 1A gene expression by the rexinoid HX600

    Energy Technology Data Exchange (ETDEWEB)

    Ishizawa, Michiyasu [Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchi-kamicho, Itabashi-ku, Tokyo 173-8610 (Japan); Kagechika, Hiroyuki [Graduate School of Biomedical Science, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062 (Japan); Makishima, Makoto, E-mail: makishima.makoto@nihon-u.ac.jp [Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchi-kamicho, Itabashi-ku, Tokyo 173-8610 (Japan)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer The function of RXR heterodimers with NR4 receptors remains unknown. Black-Right-Pointing-Pointer The RXR ligand HX600 induces expression of carnitine palmitoyltransferase 1A (CPT1A). Black-Right-Pointing-Pointer HX600-induced CPT1A expression is mediated by the NR4 receptors, Nur77 and NURR1. Black-Right-Pointing-Pointer CPT1A induction by HX600 is not mediated by de novo protein synthesis. Black-Right-Pointing-Pointer CPT1A could be a target of the Nur77-RXR and NURR1-RXR heterodimers. -- Abstract: Retinoid X receptors (RXRs) are members of the nuclear receptor superfamily and can be activated by 9-cis retinoic acid (9CRA). RXRs form homodimers and heterodimers with other nuclear receptors such as the retinoic acid receptor and NR4 subfamily nuclear receptors, Nur77 and NURR1. Potential physiological roles of the Nur77-RXR and NURR1-RXR heterodimers have not been elucidated. In this study, we identified a gene regulated by these heterodimers utilizing HX600, a selective RXR agonist for Nur77-RXR and NURR1-RXR. While 9CRA induced many genes, including RAR-target genes, HX600 effectively induced only carnitine palmitoyltransferase 1A (CPT1A) in human teratocarcinoma NT2/D1 cells, which express RXR{alpha}, Nur77 and NURR1. HX600 also increased CPT1A expression in human embryonic kidney (HEK) 293 cells and hepatocyte-derived HepG2 cells. Although HX600 induced CPT1A less effectively than 9CRA, overexpression of Nur77 or NURR1 increased the HX600 response to levels similar to 9CRA in NT2/D1 and HEK293 cells. A dominant-negative form of Nur77 or NURR1 repressed the induction of CPT1A by HX600. A protein synthesis inhibitor did not alter HX600-dependent CPT1A induction. Thus, the rexinoid HX600 directly induces expression of CPT1A through a Nur77 or NURR1-mediated mechanism. CPT1A, a gene involved in fatty acid {beta}-oxidation, could be a target of RXR-NR4 receptor heterodimers.

  20. Low-frequency stimulation in anterior nucleus of thalamus alleviates kainate-induced chronic epilepsy and modulates the hippocampal EEG rhythm.

    Science.gov (United States)

    Wang, Yi; Liang, Jiao; Xu, Cenglin; Wang, Ying; Kuang, Yifang; Xu, Zhenghao; Guo, Yi; Wang, Shuang; Gao, Feng; Chen, Zhong

    2016-02-01

    High-frequency stimulation (HFS) of the anterior nucleus of thalamus (ANT) is a new and alternative option for the treatment of intractable epilepsy. However, the responder rate is relatively low. The present study was designed to determine the effect of low-frequency stimulation (LFS) in ANT on chronic spontaneous recurrent seizures and related pathological pattern in intra-hippocampal kainate mouse model. We found that LFS (1 Hz, 100 μs, 300 μA), but not HFS (100 Hz, 100 μs, 30 μA), in bilateral ANT significantly decreased the frequency of spontaneous recurrent seizures, either non-convulsive focal seizures or tonic-clonic generalized seizures. The anti-epileptic effect persisted for one week after LFS cessation, which manifested as a long-term inhibition of the frequency of seizures with short (20-60 s) and intermediate duration (60-120 s). Meanwhile, LFS decreased the frequency of high-frequency oscillations (HFOs) and interictal spikes, two indicators of seizure severity, whereas HFS increased the HFO frequency. Furthermore, LFS decreased the power of the delta band and increased the power of the gamma band of hippocampal background EEG. In addition, LFS, but not HFS, improved the performance of chronic epileptic mice in objection-location task, novel objection recognition and freezing test. These results provide the first evidence that LFS in ANT alleviates kainate-induced chronic epilepsy and cognitive impairment, which may be related to the modulation of the hippocampal EEG rhythm. This may be of great therapeutic significance for clinical treatment of epilepsy with deep brain stimulation. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Acute running stimulates hippocampal dopaminergic neurotransmission in rats, but has no influence on brain-derived neurotrophic factor

    OpenAIRE

    Goekint, Maaike; Bos, Inge; Heyman, Elsa; Meeusen, Romain; Michotte, Yvette; Sarre, Sophie

    2011-01-01

    Hippocampal brain-derived neurotrophic factor (BDNF) protein is increased with exercise in rats. Monoamines seem to play a role in the regulation of BDNF, and monoamine neurotransmission is known to increase with exercise. The purpose of this study was to examine the influence of acute exercise on monoaminergic neurotransmission and BDNF protein concentrations. Hippocampal microdialysis was performed in rats that were subjected to 60 min of treadmill running at 20 m/min or rest. Two hours pos...

  2. Inositol trisphosphate receptor mediated spatiotemporal calcium signalling.

    Science.gov (United States)

    Miyazaki, S

    1995-04-01

    Spatiotemporal Ca2+ signalling in the cytoplasm is currently understood as an excitation phenomenon by analogy with electrical excitation in the plasma membrane. In many cell types, Ca2+ waves and Ca2+ oscillations are mediated by inositol 1,4,5-trisphosphate (IP3) receptor/Ca2+ channels in the endoplasmic reticulum membrane, with positive feedback between cytosolic Ca2+ and IP3-induced Ca2+ release creating a regenerative process. Remarkable advances have been made in the past year in the analysis of subcellular Ca2+ microdomains using confocal microscopy and of Ca2+ influx pathways that are functionally coupled to IP3-induced Ca2+ release. Ca2+ signals can be conveyed into the nucleus and mitochondria. Ca2+ entry from outside the cell allows repetitive Ca2+ release by providing Ca2+ to refill the endoplasmic reticulum stores, thus giving rise to frequency-encoded Ca2+ signals.

  3. Phytomelatonin receptor PMTR1-mediated signaling regulates stomatal closure in Arabidopsis thaliana.

    Science.gov (United States)

    Wei, Jian; Li, Dong-Xu; Zhang, Jia-Rong; Shan, Chi; Rengel, Zed; Song, Zhong-Bang; Chen, Qi

    2018-04-27

    Melatonin has been detected in plants in 1995; however, the function and signaling pathway of this putative phytohormone are largely undetermined due to a lack of knowledge about its receptor. Here, we discovered the first phytomelatonin receptor (CAND2/PMTR1) in Arabidopsis thaliana and found that melatonin governs the receptor-dependent stomatal closure. The application of melatonin induced stomatal closure through the heterotrimeric G protein α subunit-regulated H 2 O 2 and Ca 2+ signals. The Arabidopsis mutant lines lacking AtCand2 that encodes a candidate G protein-coupled receptor were insensitive to melatonin-induced stomatal closure. Accordingly, the melatonin-induced H 2 O 2 production and Ca 2+ influx were completely abolished in cand2. CAND2 is a membrane protein that interacts with GPA1 and the expression of AtCand2 was tightly regulated by melatonin in various organs and guard cells. CAND2 showed saturable and specific 125 I-melatonin binding, with apparent K d (dissociation constant) of 0.73 ± 0.10 nmol/L (r 2  = .99), demonstrating this protein is a phytomelatonin receptor (PMTR1). Our results suggest that the phytomelatonin regulation of stomatal closure is dependent on its receptor CAND2/PMTR1-mediated H 2 O 2 and Ca 2+ signaling transduction cascade. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. A novel ecdysone receptor mediates steroid-regulated developmental events during the mid-third instar of Drosophila.

    Directory of Open Access Journals (Sweden)

    Benjamin F B Costantino

    2008-06-01

    Full Text Available The larval salivary gland of Drosophila melanogaster synthesizes and secretes glue glycoproteins that cement developing animals to a solid surface during metamorphosis. The steroid hormone 20-hydroxyecdysone (20E is an essential signaling molecule that modulates most of the physiological functions of the larval gland. At the end of larval development, it is known that 20E--signaling through a nuclear receptor heterodimer consisting of EcR and USP--induces the early and late puffing cascade of the polytene chromosomes and causes the exocytosis of stored glue granules into the lumen of the gland. It has also been reported that an earlier pulse of hormone induces the temporally and spatially specific transcriptional activation of the glue genes; however, the receptor responsible for triggering this response has not been characterized. Here we show that the coordinated expression of the glue genes midway through the third instar is mediated by 20E acting to induce genes of the Broad Complex (BRC through a receptor that is not an EcR/USP heterodimer. This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component.

  5. Scavenger receptors mediate the role of SUMO and Ftz-f1 in Drosophila steroidogenesis.

    Directory of Open Access Journals (Sweden)

    Ana Talamillo

    2013-04-01

    Full Text Available SUMOylation participates in ecdysteroid biosynthesis at the onset of metamorphosis in Drosophila melanogaster. Silencing the Drosophila SUMO homologue smt3 in the prothoracic gland leads to reduced lipid content, low ecdysone titers, and a block in the larval-pupal transition. Here we show that the SR-BI family of Scavenger Receptors mediates SUMO functions. Reduced levels of Snmp1 compromise lipid uptake in the prothoracic gland. In addition, overexpression of Snmp1 is able to recover lipid droplet levels in the smt3 knockdown prothoracic gland cells. Snmp1 expression depends on Ftz-f1 (an NR5A-type orphan nuclear receptor, the expression of which, in turn, depends on SUMO. Furthermore, we show by in vitro and in vivo experiments that Ftz-f1 is SUMOylated. RNAi-mediated knockdown of ftz-f1 phenocopies that of smt3 at the larval to pupal transition, thus Ftz-f1 is an interesting candidate to mediate some of the functions of SUMO at the onset of metamorphosis. Additionally, we demonstrate that the role of SUMOylation, Ftz-f1, and the Scavenger Receptors in lipid capture and mobilization is conserved in other steroidogenic tissues such as the follicle cells of the ovary. smt3 knockdown, as well as ftz-f1 or Scavenger knockdown, depleted the lipid content of the follicle cells, which could be rescued by Snmp1 overexpression. Therefore, our data provide new insights into the regulation of metamorphosis via lipid homeostasis, showing that Drosophila Smt3, Ftz-f1, and SR-BIs are part of a general mechanism for uptake of lipids such as cholesterol, required during development in steroidogenic tissues.

  6. Perirhinal Cortex Muscarinic Receptor Blockade Impairs Taste Recognition Memory Formation

    OpenAIRE

    Gutiérrez, Ranier; De la Cruz, Vanesa; Rodriguez-Ortiz, Carlos J.; Bermudez-Rattoni, Federico

    2004-01-01

    The relevance of perirhinal cortical cholinergic and glutamatergic neurotransmission for taste recognition memory and learned taste aversion was assessed by microinfusions of muscarinic (scopolamine), NMDA (AP-5), and AMPA (NBQX) receptor antagonists. Infusions of scopolamine, but not AP5 or NBQX, prevented the consolidation of taste recognition memory using attenuation of neophobia as an index. In addition, learned taste aversion in both short- and long-term memory tests was exclusively impa...

  7. Muscarinic receptors mediate cold stress-induced detrusor overactivity in type 2 diabetes mellitus rats.

    Science.gov (United States)

    Imamura, Tetsuya; Ishizuka, Osamu; Ogawa, Teruyuki; Yamagishi, Takahiro; Yokoyama, Hitoshi; Minagawa, Tomonori; Nakazawa, Masaki; Gautam, Sudha Silwal; Nishizawa, Osamu

    2014-10-01

    This study determined if muscarinic receptors could mediate the cold stress-induced detrusor overactivity induced in type 2 diabetes mellitus rats. Ten-week-old female Goto-Kakizaki diabetic rats (n = 12) and Wister Kyoto non-diabetic rats (n = 12) were maintained on a high-fat diet for 4 weeks. Cystometric investigations of the unanesthetized rats were carried out at room temperature (27 ± 2°C) for 20 min. They were intravenously administered imidafenacin (0.3 mg/kg, n = 6) or vehicle (n = 6). After 5 min, the rats were transferred to a low temperature (4 ± 2°C) for 40 min where the cystometry was continued. The rats were then returned to room temperature for the final cystometric measurements. Afterwards, expressions of bladder muscarinic receptor M3 and M2 messenger ribonucleic acids and proteins were assessed by reverse transcription polymerase chain reaction and immunohistochemistry. In non-diabetic Wister Kyoto rats, imidafenacin did not reduce cold stress-induced detrusor overactivity. In diabetic Goto-Kakizaki rats, just after transfer to a low temperature, the cold stress-induced detrusor overactivity in imidafenacin-treated rats was reduced compared with vehicle-treated rats. Within the urinary bladders, the ratio of M3 to M2 receptor messenger ribonucleic acid in the diabetic Goto-Kakizaki rats was significantly higher than that of the non-diabetic Wister Kyoto rats. The proportion of muscarinic M3 receptor-positive area within the detrusor in diabetic Goto-Kakizaki rats was also significantly higher than that in non-diabetic Wister Kyoto rats. Imidafenacin partially inhibits cold stress-induced detrusor overactivity in diabetic Goto-Kakizaki rats. In this animal model, muscarinic M3 receptors partially mediate cold stress-induced detrusor overactivity. © 2014 The Japanese Urological Association.

  8. The 5-HT₁A receptor CG polymorphism influences the intravaginal ejaculation latency time in Dutch Caucasian men with lifelong premature ejaculation

    NARCIS (Netherlands)

    Janssen, Paddy K C; van Schaik, R; Zwinderman, Aeilko H; Olivier, Berend|info:eu-repo/dai/nl/073067199; Waldinger, Marcel D|info:eu-repo/dai/nl/163958564

    INTRODUCTION: Lifelong premature ejaculation (LPE) is characterized by persistent intravaginal ejaculation latency times (IELTs) of less than 1 min, and has been postulated as a neurobiological dysfunction related to diminished serotonergic neurotransmission with 5-HT₁A receptor hyperfunction and

  9. A History of Depression in Women is Associated with an Altered GABAergic Neuroactive Steroid Profile

    OpenAIRE

    Girdler, Susan S.; Lindgren, Monica; Porcu, Patrizia; Rubinow, D.R.; Johnson, J. L.; Morrow, A. Leslie

    2011-01-01

    The 3α,5α- and 3α,5β-reduced metabolites of progesterone, deoxycorticosterone, and dehydroepiandrosterone (DHEA) have potent effects on neurotransmission mediated by GABAA receptors, and dysregulation of these receptors has been implicated in depression. Using gas chromatography-mass spectrometry, we compared neuroactive steroid concentrations in women with a history of depressive disorders, but who were in full remission at the time of testing (n=11) to never depressed women (n=17) both befo...

  10. Novel time-dependent vascular actions of Δ9-tetrahydrocannabinol mediated by peroxisome proliferator-activated receptor gamma

    International Nuclear Information System (INIS)

    O'Sullivan, Saoirse E.; Tarling, Elizabeth J.; Bennett, Andrew J.; Kendall, David A.; Randall, Michael D.

    2005-01-01

    Cannabinoids have widespread effects on the cardiovascular system, only some of which are mediated via G-protein-coupled cell surface receptors. The active ingredient of cannabis, Δ 9 -tetrahydrocannabinol (THC), causes acute vasorelaxation in various arteries. Here we show for the first time that THC also causes slowly developing vasorelaxation through activation of peroxisome proliferator-activated receptors gamma (PPARγ). In vitro, THC (10 μM) caused time-dependent vasorelaxation of rat isolated arteries. Time-dependent vasorelaxation to THC was similar to that produced by the PPARγ agonist rosiglitazone and was inhibited by the PPARγ antagonist GW9662 (1 μM), but not the cannabinoid CB 1 receptor antagonist AM251 (1 μM). Time-dependent vasorelaxation to THC requires an intact endothelium, nitric oxide, production of hydrogen peroxide, and de novo protein synthesis. In transactivation assays in cultured HEK293 cells, THC-activated PPARγ, transiently expressed in combination with retinoid X receptor α and a luciferase reporter gene, in a concentration-dependent manner (100 nM-10 μM). In vitro incubation with THC (1 or 10 μM, 8 days) stimulated adipocyte differentiation in cultured 3T3L1 cells, a well-accepted property of PPARγ ligands. The present results provide strong evidence that THC is a PPARγ ligand, stimulation of which causes time-dependent vasorelaxation, implying some of the pleiotropic effects of cannabis may be mediated by nuclear receptors

  11. Chronic intermittent hypoxia-hypercapnia blunts heart rate responses and alters neurotransmission to cardiac vagal neurons.

    Science.gov (United States)

    Dyavanapalli, Jhansi; Jameson, Heather; Dergacheva, Olga; Jain, Vivek; Alhusayyen, Mona; Mendelowitz, David

    2014-07-01

    Patients with obstructive sleep apnoea experience chronic intermittent hypoxia-hypercapnia (CIHH) during sleep that elicit sympathetic overactivity and diminished parasympathetic activity to the heart, leading to hypertension and depressed baroreflex sensitivity. The parasympathetic control of heart rate arises from pre-motor cardiac vagal neurons (CVNs) located in nucleus ambiguus (NA) and dorsal motor nucleus of the vagus (DMNX). The mechanisms underlying diminished vagal control of heart rate were investigated by studying the changes in blood pressure, heart rate, and neurotransmission to CVNs evoked by acute hypoxia-hypercapnia (H-H) and CIHH. In vivo telemetry recordings of blood pressure and heart rate were obtained in adult rats during 4 weeks of CIHH exposure. Retrogradely labelled CVNs were identified in an in vitro brainstem slice preparation obtained from adult rats exposed either to air or CIHH for 4 weeks. Postsynaptic inhibitory or excitatory currents were recorded using whole cell voltage clamp techniques. Rats exposed to CIHH had increases in blood pressure, leading to hypertension, and blunted heart rate responses to acute H-H. CIHH induced an increase in GABAergic and glycinergic neurotransmission to CVNs in NA and DMNX, respectively; and a reduction in glutamatergic neurotransmission to CVNs in both nuclei. CIHH blunted the bradycardia evoked by acute H-H and abolished the acute H-H evoked inhibition of GABAergic transmission while enhancing glycinergic neurotransmission to CVNs in NA. These changes with CIHH inhibit CVNs and vagal outflow to the heart, both in acute and chronic exposures to H-H, resulting in diminished levels of cardioprotective parasympathetic activity to the heart as seen in OSA patients. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

  12. Receptor-mediated endocytosis of trichosanthin in choriocarcinoma cells

    International Nuclear Information System (INIS)

    Chan, W.Y.; Huang Hai; Tam, S.-C.

    2003-01-01

    Trichosanthin (TCS) is a ribosome inactivating protein (RIP). It is generally believed that its many biological activities act through inhibition of ribosomes resulting in a decrease in protein synthesis. It has been hypothesized that the rate of entry of TCS into cells to reach ribosomes is an important factor in determining its biological activity. To prove this hypothesis, we have mapped out and compared the intracellular routing of TCS in two cell lines, namely the choriocarcinoma JAR cell line, which is known to be highly sensitive to the toxic effects of TCS, and the hepatoma H35 cell line, to which TCS shows minimal toxicity. Results from laser scanning confocal microscopy indicated that fluorescein isothiocyanate labeled TCS quickly accumulated inside JAR cells within 4 h of incubation while only a low level of fluorescent signals was detected in H35 cells during the same period of time. When TCS was conjugated with gold particles (Au) and its intracellular locations were traced with a transmission electron microscope, it was found that most of TCS were bound to coated pits on the JAR cell surface and were rapidly internalized within an hour. By 4 h, TCS reached almost every cytoplasmic region including ribosomes, and the JAR cell began to degenerate. In H35 cells, however, the binding of TCS to coated pits was not observed, but instead, a small amount of TCS was found to penetrate the cell non-specifically by direct diffusion across the cell membrane. Our observations suggest that most of TCS enter JAR cells via a specific receptor mediated pathway, which allows a swift transport of TCS across the membrane and a rapid accumulation of intracellular TCS, while in H35 cells, TCS takes a slow and non-specific route. The receptor-mediated uptake together with the specific intracellular routing of TCS may partly account for the differential vulnerability of the choriocarcinoma cell line towards the toxicity of TCS

  13. Toll-like receptor 9 mediated responses in cardiac fibroblasts.

    Directory of Open Access Journals (Sweden)

    Ingrid Kristine Ohm

    Full Text Available Altered cardiac Toll-like receptor 9 (TLR9 signaling is important in several experimental cardiovascular disorders. These studies have predominantly focused on cardiac myocytes or the heart as a whole. Cardiac fibroblasts have recently been attributed increasing significance in mediating inflammatory signaling. However, putative TLR9-signaling through cardiac fibroblasts remains non-investigated. Thus, our aim was to explore TLR9-signaling in cardiac fibroblasts and investigate the consequence of such receptor activity on classical cardiac fibroblast cellular functions. Cultivated murine cardiac fibroblasts were stimulated with different TLR9 agonists (CpG A, B and C and assayed for the secretion of inflammatory cytokines (tumor necrosis factor α [TNFα], CXCL2 and interferon α/β. Expression of functional cardiac fibroblast TLR9 was proven as stimulation with CpG B and -C caused significant CXCL2 and TNFα-release. These responses were TLR9-specific as complete inhibition of receptor-stimulated responses was achieved by co-treatment with a TLR9-antagonist (ODN 2088 or chloroquine diphosphate. TLR9-stimulated responses were also found more potent in cardiac fibroblasts when compared with classical innate immune cells. Stimulation of cardiac fibroblasts TLR9 was also found to attenuate migration and proliferation, but did not influence myofibroblast differentiation in vitro. Finally, results from in vivo TLR9-stimulation with subsequent fractionation of specific cardiac cell-types (cardiac myocytes, CD45+ cells, CD31+ cells and cardiac fibroblast-enriched cell-fractions corroborated our in vitro data and provided evidence of differentiated cell-specific cardiac responses. Thus, we conclude that cardiac fibroblast may constitute a significant TLR9 responder cell within the myocardium and, further, that such receptor activity may impact important cardiac fibroblast cellular functions.

  14. Oméga 3 et neurotransmission cérébrale

    Directory of Open Access Journals (Sweden)

    Vancassel Sylvie

    2004-01-01

    Full Text Available Les acides gras polyinsaturés (AGPI sont des constituants structuraux fondamentaux du système nerveux central (SNC dont la teneur conditionne le fonctionnement des cellules neuronales. Ils sont des acteurs de la communication intercellulaire, notamment à travers les processus de neurotransmission. De nombreuses études ont montré chez l’animal que le déficit des membranes cérébrales en oméga 3, et plus particulièrement en acide docosahexaénoïque (22 : 6ω-3 ou DHA induit par une carence alimentaire spécifique en cette famille d’AGPI, s’accompagne de troubles de l’apprentissage. Un support neurochimique a été avancé, impliquant les processus de libération de neurotransmetteurs, notamment les monoamines et l’acétylcholine. Cette relation entre AGPI ω3 et neurotransmission est d’autant plus intéressante qu’elle pourrait être également impliquée chez l’Homme dans l’apparition et\\\\ou la sévérité de certains troubles neuropsychiatriques dans lesquels des dysfonctionnements de la neurotransmission sont constatés (schizophrénie, dépression, hyperactivité chez l’enfant. En effet, de nombreuses études révèlent un déficit du statut corporel en AGPI oméga 3 (20 : 5 et 22 : 6 mais aussi en oméga 6, qui peut être corrigé par voie nutritionnelle, permettant alors de réduire significativement certains des symptômes pathologiques. Dans ce contexte, nous développons au laboratoire des recherches visant à comprendre les mécanismes d’action des oméga 3, et en particulier du DHA, dans les membranes nerveuses et l’incidence sur le fonctionnement de ces cellules.

  15. Evidence that 5-hydroxytryptamine/sub 3/ receptors mediate cytotoxic drug and radiation-evoked emesis

    Energy Technology Data Exchange (ETDEWEB)

    Miner, W.D.; Sanger, G.J.; Turner, D.H.

    1987-08-01

    The involvement of 5-hydroxytryptamine (5-HT) 5-HT/sub 3/ receptors in the mechanisms of severe emesis evoked by cytotoxic drugs or by total body irradiation have been studied in ferrets. Anti-emetic compounds tested were domperidone (a dopamine antagonist), metoclopramide (a gastric motility stimulant and dopamine antagonist at conventional doses, a 5-HT/sub 3/ receptor antagonist at higher doses) and BRL 24924 (a potent gastric motility stimulant and a 5-HT/sub 3/ receptor antagonist). Domperidone or metoclopramide prevented apomorphine-evoked emesis, whereas BRL 24924 did not. Similar doses of domperidone did not prevent emesis evoked by cis-platin or by total body irradiation, whereas metoclopramide or BRL 24924 greatly reduced or prevented these types of emesis. Metoclopramide and BRL 24924 also prevented emesis evoked by a combination of doxorubicin and cyclophosphamide. These results are discussed in terms of a fundamental role for 5-HT/sub 3/ receptors in the mechanisms mediating severely emetogenic cancer treatment therapies.

  16. The 5-HT₁A receptor CG polymorphism influences the intravaginal ejaculation latency time in Dutch Caucasian men with lifelong premature ejaculation

    NARCIS (Netherlands)

    Janssen, Paddy K. C.; van Schaik, R.; Zwinderman, Aeilko H.; Olivier, Berend; Waldinger, Marcel D.

    2014-01-01

    Lifelong premature ejaculation (LPE) is characterized by persistent intravaginal ejaculation latency times (IELTs) of less than 1 min, and has been postulated as a neurobiological dysfunction related to diminished serotonergic neurotransmission with 5-HT₁A receptor hyperfunction and 5-HT₂C

  17. Loss of Progesterone Receptor-Mediated Actions Induce Preterm Cellular and Structural Remodeling of the Cervix and Premature Birth

    Science.gov (United States)

    Yellon, Steven M.; Dobyns, Abigail E.; Beck, Hailey L.; Kurtzman, James T.; Garfield, Robert E.; Kirby, Michael A.

    2013-01-01

    A decline in serum progesterone or antagonism of progesterone receptor function results in preterm labor and birth. Whether characteristics of premature remodeling of the cervix after antiprogestins or ovariectomy are similar to that at term was the focus of the present study. Groups of pregnant rats were treated with vehicle, a progesterone receptor antagonist (onapristone or mifepristone), or ovariectomized on day 17 postbreeding. As expected, controls given vehicle delivered at term while rats delivered preterm after progesterone receptor antagonist treatment or ovariectomy. Similar to the cervix before term, the preterm cervix of progesterone receptor antagonist-treated rats was characterized by reduced cell nuclei density, decreased collagen content and structure, as well as a greater presence of macrophages per unit area. Thus, loss of nuclear progesterone receptor-mediated actions promoted structural remodeling of the cervix, increased census of resident macrophages, and preterm birth much like that found in the cervix at term. In contrast to the progesterone receptor antagonist-induced advance in characteristics associated with remodeling, ovariectomy-induced loss of systemic progesterone did not affect hypertrophy, extracellular collagen, or macrophage numbers in the cervix. Thus, the structure and macrophage census in the cervix appear sufficient for premature ripening and birth to occur well before term. With progesterone receptors predominantly localized on cells other than macrophages, the findings suggest that interactions between cells may facilitate the loss of progesterone receptor-mediated actions as part of a final common mechanism that remodels the cervix in certain etiologies of preterm and with parturition at term. PMID:24339918

  18. Deletion of P2X2 and P2X3 receptor subunits does not alter motility of the mouse colon

    Directory of Open Access Journals (Sweden)

    Matthew DeVries

    2010-03-01

    Full Text Available Purinergic P2X receptors contribute to neurotransmission in the gut. P2X receptors are ligand-gated cation channels that mediate synaptic excitation in subsets of enteric neurons. The present study evaluated colonic motility in vitro and in vivo in wild type (WT and P2X2 and P2X3 subunit knockout (KO mice. The muscarinic receptor agonist, bethanechol (0.3-3 micromolar, caused similar contractions of the longitudinal muscle in colon segments from WT, P2X2 and P2X3 subunit KO mice. Nicotine (1-300 micromolar, acting at neuronal nicotinic receptors, caused similar longitudinal muscle relaxations in colonic segments from WT and P2X2 and P2X3 subunit KO mice. Nicotine-induced relaxations were inhibited by nitro-L-arginine (NLA, 100 micromolar and apamin (0.1 micromolar which block inhibitory neuromuscular transmission. ATP (1-1000 micromolar caused contractions only in the presence of NLA and apamin. ATP-induced contractions were similar in colon segments from WT, P2X2 and P2X3 KO mice. The mouse colon generates spontaneous migrating motor complexes (MMCs in vitro. The MMC frequency was higher in P2X2 KO compared to WT tissues; other parameters of the MMC were similar in colon segments from WT, P2X2 and P2X3 KO mice. 5-Hydroxytryptophan-induced fecal output was similar in WT, P2X2 and P2X3 KO mice. These data indicate that nicotinic receptors are located predominately on inhibitory motor neurons supplying the longitudinal muscle in the mouse colon. P2X2 or P2X3 subunit containing receptors are not localized to motorneurons supplying the longitudinal muscle. Synaptic transmission mediated by P2X2 or P2X3 subunit containing receptors is not required for propulsive motility in the mouse colon.

  19. Oxidative stress augments toll-like receptor 8 mediated neutrophilic responses in healthy subjects

    Directory of Open Access Journals (Sweden)

    Matsunaga Kazuto

    2009-06-01

    Full Text Available Abstract Background Excessive oxidative stress has been reported to be generated in inflamed tissues and contribute to the pathogenesis of inflammatory lung diseases, exacerbations of which induced by viral infections are associated with toll-like receptor (TLR activation. Among these receptors, TLR8 has been reported as a key receptor that recognizes single-strand RNA virus. However, it remains unknown whether TLR8 signaling is potentiated by oxidative stress. The aim of this study is to examine whether oxidative stress modulates TLR8 signaling in vitro. Methods Human peripheral blood neutrophils were obtained from healthy non-smokers and stimulated with TLR 7/8 agonist imidazoquinoline resiquimod (R848 in the presence or absence of hydrogen peroxide (H2O2. Neutrophilic responses including cytokine release, superoxide production and chemotaxis were examined, and the signal transduction was also analyzed. Results Activation of TLR8, but not TLR7, augmented IL-8 release. The R848-augmented IL-8 release was significantly potentiated by pretreatment with H2O2 (p L-cysteine reversed this potentiation. The combination of H2O2 and R848 significantly potentiated NF-kB phosphorylation and IkBα degradation. The H2O2-potentiated IL-8 release was suppressed by MG-132, a proteosome inhibitor, and by dexamethasone. The expressions of TLR8, myeloid differentiation primary response gene 88 (MyD88, and tumor necrosis factor receptor-associated factor 6 (TRAF6 were not affected by H2O2. Conclusion TLR8-mediated neutrophilic responses were markedly potentiated by oxidative stress, and the potentiation was mediated by enhanced NF-kB activation. These results suggest that oxidative stress might potentiate the neutrophilic inflammation during viral infection.

  20. The Influence of Receptor-Mediated Interactions on Reaction-Diffusion Mechanisms of Cellular Self-organisation

    Czech Academy of Sciences Publication Activity Database

    Klika, Václav; Baker, R. E.; Headon, D.; Gaffney, E. A.

    2012-01-01

    Roč. 74, č. 4 (2012), s. 935-957 ISSN 0092-8240 Institutional research plan: CEZ:AV0Z20760514 Keywords : reaction-diffusion * receptor-mediated patterning * turing models Subject RIV: BO - Biophysics Impact factor: 2.023, year: 2012 http://www.springerlink.com/content/9713544x6871w4n6/?MUD=MP

  1. Opposing functions of two sub-domains of the SNARE-complex in neurotransmission

    DEFF Research Database (Denmark)

    Weber, Jens P; Reim, Kerstin; Sørensen, Jakob B

    2010-01-01

    The SNARE-complex consisting of synaptobrevin-2/VAMP-2, SNAP-25 and syntaxin-1 is essential for evoked neurotransmission and also involved in spontaneous release. Here, we used cultured autaptic hippocampal neurons from Snap-25 null mice rescued with mutants challenging the C-terminal, N-terminal...

  2. IL-6 Overexpression in ERG-Positive Prostate Cancer Is Mediated by Prostaglandin Receptor EP2.

    Science.gov (United States)

    Merz, Constanze; von Mässenhausen, Anne; Queisser, Angela; Vogel, Wenzel; Andrén, Ove; Kirfel, Jutta; Duensing, Stefan; Perner, Sven; Nowak, Michael

    2016-04-01

    Prostate cancer is the most diagnosed cancer in men and multiple risk factors and genetic alterations have been described. The TMPRSS2-ERG fusion event and the overexpression of the transcription factor ERG are present in approximately 50% of all prostate cancer patients, however, the clinical outcome is still controversial. Prostate tumors produce various soluble factors, including the pleiotropic cytokine IL-6, regulating cellular processes such as proliferation and metastatic segregation. Here, we used prostatectomy samples in a tissue microarray format and analyzed the co-expression and the clinicopathologic data of ERG and IL-6 using immunohistochemical double staining and correlated the read-out with clinicopathologic data. Expression of ERG and IL-6 correlated strongly in prostate tissue samples. Forced expression of ERG in prostate tumor cell lines resulted in significantly increased secretion of IL-6, whereas the down-regulation of ERG decreased IL-6 secretion. By dissecting the underlying mechanism in prostate tumor cell lines we show the ERG-mediated up-regulation of the prostanoid receptors EP2 and EP3. The prostanoid receptor EP2 was overexpressed in human prostate cancer tissue. Furthermore, the proliferation rate and IL-6 secretion in DU145 cells was reduced after treatment with EP2-receptor antagonist. Collectively, our study shows that the expression of ERG in prostate cancer is linked to the expression of IL-6 mediated by the prostanoid receptor EP2. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  3. Alpha 1-adrenergic receptor-mediated phosphoinositide hydrolysis and prostaglandin E2 formation in Madin-Darby canine kidney cells. Possible parallel activation of phospholipase C and phospholipase A2

    International Nuclear Information System (INIS)

    Slivka, S.R.; Insel, P.A.

    1987-01-01

    alpha 1-Adrenergic receptors mediate two effects on phospholipid metabolism in Madin-Darby canine kidney (MDCK-D1) cells: hydrolysis of phosphoinositides and arachidonic acid release with generation of prostaglandin E2 (PGE2). The similarity in concentration dependence for the agonist (-)-epinephrine in eliciting these two responses implies that they are mediated by a single population of alpha 1-adrenergic receptors. However, we find that the kinetics of the two responses are quite different, PGE2 production occurring more rapidly and transiently than the hydrolysis of phosphoinositides. The antibiotic neomycin selectively decreases alpha 1-receptor-mediated phosphatidylinositol 4,5-bisphosphate hydrolysis without decreasing alpha 1-receptor-mediated arachidonic acid release and PGE2 generation. In addition, receptor-mediated inositol trisphosphate formation is independent of extracellular calcium, whereas release of labeled arachidonic acid is largely calcium-dependent. Moreover, based on studies obtained with labeled arachidonic acid, receptor-mediated generation of arachidonic acid cannot be accounted for by breakdown of phosphatidylinositol monophosphate, phosphatidylinositol bisphosphate, or phosphatidic acid. Further studies indicate that epinephrine produces changes in formation or turnover of several classes of membrane phospholipids in MDCK cells. We conclude that alpha 1-adrenergic receptors in MDCK cells appear to regulate phospholipid metabolism by the parallel activation of phospholipase C and phospholipase A2. This parallel activation of phospholipases contrasts with models described in other systems which imply sequential activation of phospholipase C and diacylglycerol lipase or phospholipase A2

  4. NMDA receptors mediate neuron-to-glia signaling in mouse cortical astrocytes.

    Science.gov (United States)

    Lalo, Ulyana; Pankratov, Yuri; Kirchhoff, Frank; North, R Alan; Verkhratsky, Alexei

    2006-03-08

    Chemical transmission between neurons and glial cells is an important element of integration in the CNS. Here, we describe currents activated by NMDA in cortical astrocytes, identified in transgenic mice that express enhanced green fluorescent protein under control of the human glial fibrillary acidic protein promoter. Astrocytes were studied by whole-cell voltage clamp either in slices or after gentle nonenzymatic mechanical dissociation. Acutely isolated astrocytes showed a three-component response to glutamate. The initial rapid component was blocked by 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX), which is an antagonist of AMPA receptors (IC50, 2 microM), and the NMDA receptor antagonist D-AP-5 blocked the later sustained component (IC50, 0.6 microM). The third component of glutamate application response was sensitive to D,L-threo-beta-benzyloxyaspartate, a glutamate transporter blocker. Fast application of NMDA evoked concentration-dependent inward currents (EC50, 0.3 microM); these showed use-dependent block by (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate (MK-801). These NMDA-evoked currents were linearly dependent on membrane potential and were not affected by extracellular magnesium at concentrations up to 10 mM. Electrical stimulation of axons in layer IV-VI induced a complex inward current in astrocytes situated in the cortical layer II, part of which was sensitive to MK-801 at holding potential -80 mV and was not affected by the AMPA glutamate receptor antagonist NBQX. The fast miniature spontaneous currents were observed in cortical astrocytes in slices as well. These currents exhibited both AMPA and NMDA receptor-mediated components. We conclude that cortical astrocytes express functional NMDA receptors that are devoid of Mg2+ block, and these receptors are involved in neuronal-glial signal transmission.

  5. Caffeine and an adenosine A(2A) receptor antagonist prevent memory impairment and synaptotoxicity in adult rats triggered by a convulsive episode in early life.

    Science.gov (United States)

    Cognato, Giana P; Agostinho, Paula M; Hockemeyer, Jörg; Müller, Christa E; Souza, Diogo O; Cunha, Rodrigo A

    2010-01-01

    Seizures early in life cause long-term behavioral modifications, namely long-term memory deficits in experimental animals. Since caffeine and adenosine A(2A) receptor (A(2A)R) antagonists prevent memory deficits in adult animals, we now investigated if they also prevented the long-term memory deficits caused by a convulsive period early in life. Administration of kainate (KA, 2 mg/kg) to 7-days-old (P7) rats caused a single period of self-extinguishable convulsions which lead to a poorer memory performance in the Y-maze only when rats were older than 90 days, without modification of locomotion or anxiety-like behavior in the elevated-plus maze. In accordance with the relationship between synaptotoxicity and memory dysfunction, the hippocampus of these adult rats treated with kainate at P7 displayed a lower density of synaptic proteins such as SNAP-25 and syntaxin (but not synaptophysin), as well as vesicular glutamate transporters type 1 (but not vesicular GABA transporters), with no changes in PSD-95, NMDA receptor subunits (NR1, NR2A, NR2B) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunits (GluR1, GluR2) compared with controls. Caffeine (1 g/L) or the A(2A)R antagonist, KW6002 (3 mg/kg) applied in the drinking water from P21 onwards, prevented these memory deficits in P90 rats treated with KA at P7, as well as the accompanying synaptotoxicity. These results show that a single convulsive episode in early life causes a delayed memory deficit in adulthood accompanied by a glutamatergic synaptotoxicity that was prevented by caffeine or adenosine A(2A)R antagonists.

  6. The 5-HT2A receptor binding pattern in the human brain is strongly genetically determined

    DEFF Research Database (Denmark)

    Pinborg, Lars H; Arfan, Haroon; Haugbol, Steven

    2007-01-01

    With the appropriate radiolabeled tracers, positron emission tomography (PET) enables in vivo human brain imaging of markers for neurotransmission, including neurotransmitter synthesis, receptors, and transporters. Whereas structural imaging studies have provided compelling evidence that the human...... brain anatomy is largely genetically determined, it is currently unknown to what degree neuromodulatory markers are subjected to genetic and environmental influence. Changes in serotonin 2A (5-HT(2A)) receptors have been reported to occur in various neuropsychiatric disorders and an association between...

  7. Thyrotropin modulates receptor-mediated processing of the atrial natriuretic peptide receptor in cultured thyroid cells

    International Nuclear Information System (INIS)

    Tseng, Y.L.; Burman, K.D.; Lahiri, S.; Abdelrahim, M.M.; D'Avis, J.C.; Wartofsky, L.

    1991-01-01

    In a prior study of atrial natriuretic peptide (ANP) binding to cultured thyroid cells, we reported that at 4 C, more than 95% of bound ANP is recovered on cell membranes, with negligible ANP internalization observed. Since ANP binding was inhibited by TSH, we have further studied TSH effects on postbinding ANP processing to determine whether this phenomenon reflects enhanced endocytosis of the ANP-receptor complex. An ANP chase study was initiated by binding [125I] ANP to thyroid cells at 4 C for 2 h, followed by incubation at 37 C. ANP processing was then traced by following 125I activity at various time intervals in three fractions: cell surface membranes, incubation medium, and inside the cells. Radioactivity released into medium represented processed ANP rather than ANP dissociated from surface membranes, since prebound [125I]ANP could not be competitively dissociated by a high concentration of ANP (1 mumol/L) at 37 C. Chase study results showed that prebound ANP quickly disappeared from cell membranes down to 34% by 30 min. Internalized ANP peaked at 10 min, with 21% of initial prebound ANP found inside the cells. At the same time, radioactivity recovered in incubation medium sharply increased between 10-30 min from 8% to 52%. Preincubation of cells with chloroquine (which blocks degradation of the ANP-receptor complex by inhibiting lysosomal hydrolase) caused a 146% increase in internalized [125I]ANP by 30 min (39% compared to 15% control), while medium radioactivity decreased from 52% to 16%, suggesting that processing of the receptor complex is mediated via lysosomal enzymes. In chase studies employing cells pretreated with chloroquine, TSH stimulated the internalization rate of ANP-receptor complex. By 30 min, TSH significantly reduced the membrane-bound ANP, and the decrease was inversely correlated to the increase in internalized radioactivity

  8. Epilepsy, regulation of brain energy metabolism and neurotransmission.

    Science.gov (United States)

    Cloix, Jean-François; Hévor, Tobias

    2009-01-01

    Seizures are the result of a sudden and temporary synchronization of neuronal activity, the reason for which is not clearly understood. Astrocytes participate in the control of neurotransmitter storage and neurotransmission efficacy. They provide fuel to neurons, which need a high level of energy to sustain normal and pathological neuronal activities, such as during epilepsy. Various genetic or induced animal models have been developed and used to study epileptogenic mechanisms. Methionine sulfoximine induces both seizures and the accumulation of brain glycogen, which might be considered as a putative energy store to neurons in various animals. Animals subjected to methionine sulfoximine develop seizures similar to the most striking form of human epilepsy, with a long pre-convulsive period of several hours, a long convulsive period during up to 48 hours and a post convulsive period during which they recover normal behavior. The accumulation of brain glycogen has been demonstrated in both the cortex and cerebellum as early as the pre-convulsive period, indicating that this accumulation is not a consequence of seizures. The accumulation results from an activation of gluconeogenesis specifically localized to astrocytes, both in vivo and in vitro. Both seizures and brain glycogen accumulation vary when using different inbred strains of mice. C57BL/6J is the most "resistant" strain to methionine sulfoximine, while CBA/J is the most "sensitive" one. The present review describes the data obtained on methionine sulfoximine dependent seizures and brain glycogen in the light of neurotransmission, highlighting the relevance of brain glycogen content in epilepsies.

  9. The involvement of the sigma-1 receptor in neurodegeneration and neurorestoration.

    Science.gov (United States)

    Ruscher, Karsten; Wieloch, Tadeusz

    2015-01-01

    The sigma-1 receptor (Sig-1R) is a single 25 kD polypeptide and a chaperone protein immersed in lipid rafts of the endoplasmic reticulum (ER) where it interacts with mitochondria at the mitochondria-associated ER membrane domain (MAM). Upon activation, the Sig-1R binds to the inositol trisphosphate receptor (IP3R), and modulates cellular calcium (Ca(2+)) homeostasis. Also, the activated Sig-1R modulates plasma membrane receptor and ion channel functions, and may regulate cellular excitability. Further, the Sig-1R promotes trafficking of lipids and proteins essential for neurotransmission, cell growth and motility. Activation of the Sig-1R provides neuroprotection and is neurorestorative in cellular and animal models of neurodegenerative diseases and brain ischaemia. Neuroprotection appears to be due to inhibition of cellular Ca(2+) toxicity and/or inflammation, and neurorestoration may include balancing abberant neurotransmission or stimulation of synaptogenesis, thus remodelling brain connectivity. Single nucleotide polymorphisms and mutations of the SIGMAR1 gene worsen outcome in Alzheimer's disease and myotrophic lateral sclerosis supporting a role of Sig-1R in neurodegenerative disease. The combined neuroprotective and neurorestorative actions of the Sig-1R, provide a broad therapeutic time window of Sig-1R agonists. The Sig-1R is therefore a strong therapeutic target for the development of new treatments for neurodegenerative diseases and stroke. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

  10. Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium.

    LENUS (Irish Health Repository)

    Dooley, Ruth

    2012-02-01

    BACKGROUND: Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation. RESULTS: Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells. CONCLUSION: Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.

  11. Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium

    LENUS (Irish Health Repository)

    Dooley, Ruth

    2011-08-22

    Abstract Background Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation. Results Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells. Conclusion Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.

  12. Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium

    Directory of Open Access Journals (Sweden)

    Hatt Hanns

    2011-08-01

    Full Text Available Abstract Background Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation. Results Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells. Conclusion Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.

  13. Monoclonal antibody to the type I insulin-like growth factor (IGF-I) receptor blocks IGF-I receptor-mediated DNA synthesis: clarification of the mitogenic mechanisms of IGF-I and insulin in human skin fibroblasts

    International Nuclear Information System (INIS)

    Flier, J.S.; Usher, P.; Moses, A.C.

    1986-01-01

    Insulin and insulin-like growth factor type I (IGF-I) stimulate an overlapping spectrum of biological responses in human skin fibroblasts. Although insulin and IGF-I are known to stimulate the incorporation of [ 3 H]thymidine into DNA in these cells, the identify of the receptor(s) that mediates this effect has not been fully clarified. The mouse anti-human IGF-I receptor antibody αIR-3 binds with specificity to IGF-I but not to insulin receptors in human placental membranes; it also specifically inhibits the binding of 125 I-labeled IGF-I but not 125 I-labeled insulin to suspensions of human skin fibroblasts in a dose-dependent manner. αIR-3 competitively inhibits IGF-I-mediated stimulation of [ 3 H]thymidine incorporation into DNA. This inhibition is dependent on the concentration of αIR-3 and in the presence of a fixed antibody concentration can be partially overcome by high concentrations of IGF-I. In contrast, at concentrations of 3 H]thymidine incorporation is not inhibited by αIR-3. However, the incremental effects of higher concentrations (> 1 μg/ml) of insulin on [ 3 H]thymidine incorporation are inhibited by αIR-3. αIR-3 is a highly specific antagonist of IGF-I receptor-mediated mitogenesis in human skin fibroblasts. By using this antibody, it is shown directly that insulin can act through the IGF-I receptor to stimulate DNA synthesis but can also activate this effect through the insulin receptor itself

  14. Receptor binding radiotracers for the angiotensin II receptor: radioiodinated [Sar1, Ile8]angiotensin II

    International Nuclear Information System (INIS)

    Gibson, R.E.; Beauchamp, H.T.; Fioravanti, C.; Brenner, N.; Burns, H.D.

    1994-01-01

    The potential for imaging the angiotensin II receptor was evaluated using the radioiodinated peptide antagonist [ 125 I][Sar 1 , Ile 8 ]angiotensin II. The radioligand provides a receptor-mediated signal in several tissues in rat (kidneys, adrenal and liver). The receptor-mediated signal of 3% ID/g kidney cortex should be sufficient to permit imaging, at least via SPECT. The radiotracer is sensitive to reductions in receptor concentration and can be used to define in vivo dose-occupancy curves of angiotensin II receptor ligands. Receptor-mediated images of [ 123 I][Sar 1 , Ile 8 ]angiotensin II were obtained in the rat kidney and Rhesus monkey liver. (author)

  15. A role for inflammatory mediators in heterologous desensitization of CysLT1 receptor in human monocytes

    Science.gov (United States)

    Capra, Valérie; Accomazzo, Maria Rosa; Gardoni, Fabrizio; Barbieri, Silvia; Rovati, G. Enrico

    2010-01-01

    Cysteinyl-leukotrienes (cysteinyl-LT) are rapidly generated at sites of inflammation and, in addition to their role in asthma, rhinitis, and other immune disorders, are increasingly regarded as significant inflammatory factors in cancer, gastrointestinal, cardiovascular diseases. We recently demonstrated that in monocyte/macrophage–like U937 cells, extracellular nucleotides heterologously desensitize CysLT1 receptor (CysLT1R)-induced Ca2+ transients. Given that monocytes express a number of other inflammatory and chemoattractant receptors, this study was aimed at characterizing transregulation between these different stimuli. We demonstrate that in U937 cells and in primary human monocytes, a series of inflammatory mediators activating Gi-coupled receptor (FPR1, BLT1) desensitize CysLT1R-induced Ca2+ response unidirectionally through activation of PKC. Conversely, PAF-R, exclusively coupled to Gq, cross-desensitizes CysLT1R without the apparent involvement of any kinase. Interestingly, Gs-coupled receptors (β2AR, H1/2R, EP2/4R) are also able to desensitize CysLT1R response through activation of PKA. Heterologous desensitization seems to affect mostly the Gi-mediated signaling of the CysLT1R. The hierarchy of desensitization among agonists may be important for leukocyte signal processing at the site of inflammation. Considering that monocytes/macrophages are likely to be the major source of cysteinyl-LT in many immunological and inflammatory processes, shedding light on how their receptors are regulated will certainly help to better understand the role of these cells in orchestrating this complex network of integrated signals. PMID:19965602

  16. Changes in flip/flop splicing of astroglial AMPA receptors in human temporal lobe epilepsy.

    Science.gov (United States)

    Seifert, Gerald; Schröder, Wolfgang; Hinterkeuser, Stefan; Schumacher, Thekla; Schramm, Johannes; Steinhäuser, Christian

    2002-01-01

    Recent data suggested a role for glial cells in epilepsy. This study sought to identify and functionally characterize AMPA receptors expressed by astrocytes in human hippocampal tissue resected from patients with intractable temporal lobe epilepsy. Patch-clamp and fast application methods were combined to investigate astrocytes in situ and after fresh isolation from the stratum radiatum of the hippocampal CA1 subfield. Relying on presurgical and histopathologic analysis, we divided human specimens into two groups, Ammon's horn sclerosis (AHS) and lesion-associated epilepsy. Fast application of glutamate and kainate evoked receptor currents in all cells studied. Reversal-potential analysis revealed an intermediate Ca2+ permeability of the receptor channels that did not vary between the two groups of patients. However, preapplication of the AMPA receptor-specific modulator, cyclothiazide, disclosed differences in flip-flop splicing. This treatment considerably enhanced the receptor conductance, with potentiation being significantly stronger in cells from AHS specimens compared with lesion-associated cells, suggesting upregulation of AMPA receptor flip splice variants in astrocytes of the sclerotic tissue. Compelling evidence has been accumulated showing direct and rapid signaling between neurons and glial cells. Our data suggest that in AHS patients, neuronally released glutamate will lead to an enhanced and prolonged depolarization of astrocytes, which might be involved in seizure generation and spread in this particular condition of human temporal lobe epilepsy.

  17. Ran GTPase promotes cancer progression via Met receptor-mediated downstream signaling

    Science.gov (United States)

    Yuen, Hiu-Fung; Chan, Ka-Kui; Platt-Higgins, Angela; Dakir, El-Habib; Matchett, Kyle B.; Haggag, Yusuf Ahmed; Jithesh, Puthen V.; Habib, Tanwir; Faheem, Ahmed; Dean, Fennell A.; Morgan, Richard; Rudland, Philip S.; El-Tanani, Mohamed

    2016-01-01

    It has been shown previously that cancer cells with an activated oncogenic pathway, including Met activation, require Ran for growth and survival. Here, we show that knockdown of Ran leads to a reduction of Met receptor expression in several breast and lung cancer cell lines. This, in turn suppressed HGF expression and the Met-mediated activation of the Akt pathway, as well as cell adhesion, migration, and invasion. In a cell line model where Met amplification has previously been shown to contribute to gefitinib resistance, Ran knockdown sensitized cells to gefitinib-mediated inhibition of Akt and ERK1/2 phosphorylation and consequently reduced cell proliferation. We further demonstrate that Met reduction-mediated by knockdown of Ran, occurs at the post-transcriptional level, probably via a matrix metalloproteinase. Moreover, the level of immunoreactive Ran and Met are positively associated in human breast cancer specimens, suggesting that a high level of Ran may be a pre-requisite for Met overexpression. Interestingly, a high level of immunoreactive Ran dictates the prognostic significance of Met, indicating that the co-overexpression of Met and Ran may be associated with cancer progression and could be used in combination as a prognostic indicator. PMID:27716616

  18. Shc adaptor proteins are key transducers of mitogenic signaling mediated by the G protein-coupled thrombin receptor

    DEFF Research Database (Denmark)

    Chen, Y; Grall, D; Salcini, A E

    1996-01-01

    The serine protease thrombin activates G protein signaling systems that lead to Ras activation and, in certain cells, proliferation. Whereas the steps leading to Ras activation by G protein-coupled receptors are not well defined, the mechanisms of Ras activation by receptor tyrosine kinases have......-insensitive proteins appear to mediate this effect, since (i) pertussis toxin pre-treatment of cells does not blunt the action of thrombin and (ii) Shc phosphorylation on tyrosine can be stimulated by the muscarinic m1 receptor. Shc phosphorylation does not appear to involve protein kinase C, since the addition of 4...

  19. Effects of Ketamine and Ketamine Metabolites on Evoked Striatal Dopamine Release, Dopamine Receptors, and Monoamine Transporters

    Science.gov (United States)

    Can, Adem; Zanos, Panos; Moaddel, Ruin; Kang, Hye Jin; Dossou, Katinia S. S.; Wainer, Irving W.; Cheer, Joseph F.; Frost, Douglas O.; Huang, Xi-Ping

    2016-01-01

    Following administration at subanesthetic doses, (R,S)-ketamine (ketamine) induces rapid and robust relief from symptoms of depression in treatment-refractory depressed patients. Previous studies suggest that ketamine’s antidepressant properties involve enhancement of dopamine (DA) neurotransmission. Ketamine is rapidly metabolized to (2S,6S)- and (2R,6R)-hydroxynorketamine (HNK), which have antidepressant actions independent of N-methyl-d-aspartate glutamate receptor inhibition. These antidepressant actions of (2S,6S;2R,6R)-HNK, or other metabolites, as well as ketamine’s side effects, including abuse potential, may be related to direct effects on components of the dopaminergic (DAergic) system. Here, brain and blood distribution/clearance and pharmacodynamic analyses at DA receptors (D1–D5) and the DA, norepinephrine, and serotonin transporters were assessed for ketamine and its major metabolites (norketamine, dehydronorketamine, and HNKs). Additionally, we measured electrically evoked mesolimbic DA release and decay using fast-scan cyclic voltammetry following acute administration of subanesthetic doses of ketamine (2, 10, and 50 mg/kg, i.p.). Following ketamine injection, ketamine, norketamine, and multiple hydroxynorketamines were detected in the plasma and brain of mice. Dehydronorketamine was detectable in plasma, but concentrations were below detectable limits in the brain. Ketamine did not alter the magnitude or kinetics of evoked DA release in the nucleus accumbens in anesthetized mice. Neither ketamine’s enantiomers nor its metabolites had affinity for DA receptors or the DA, noradrenaline, and serotonin transporters (up to 10 μM). These results suggest that neither the side effects nor antidepressant actions of ketamine or ketamine metabolites are associated with direct effects on mesolimbic DAergic neurotransmission. Previously observed in vivo changes in DAergic neurotransmission following ketamine administration are likely indirect. PMID

  20. Receptor-mediated endocytosis of low density lipoproteins in aortic endothelial cells

    International Nuclear Information System (INIS)

    Sanan, D.A.

    1986-04-01

    Lipoprotein binding and metabolism in actively-dividing (subconfluent) and quiescent (postconfluent) bovine aortic endothelial cells (ECs) were qualitatively investigated by fluorescence microscopy using dioctadecylindocarbocyanine-labelled lipoproteins and by indirect immunofluorescence microscopy. LDL and acetylated-LDL (AcLDL) were seen bound to the surfaces of subconfluent ECs (at 4 degrees C or at 37 degrees C), as a random distribution of punctate foci. ECs therefore closely resembled fibroblasts in the distribution of LDL receptors on their surfaces. No binding of LDL was seen on postconfluent EC surfaces by either direct or indirect fluorescence microscopy. The patterns of AcLDL binding on postconfluent ECs resembled those on subconfluent ECs. Intracellular LDL and AcLDL occurred as perinuclear accumulations of large fluorescent disc-shaped profiles in subconfluent ECs. These accumulations were shown to arise from surface-bound material by pulse-chase experiments. Intracellular LDL was absent in the majority of postconfluent ECs, while AcLDL accumulation was massive. 'Wounding' of cultures allowed simultaneous assessment of lipoprotein metabolism in quiescent and actively-dividing areas of the same culture. It is concluded that postconfluent quiescent bovine aortic ECs in vitro metabolise virtually no LDL via the LDL-receptor pathway due to a vanishingly low number of LDL receptors. This contrasts with the ability of postconfluent cells to metabolise relatively large amounts of AcLDL via a receptor-mediated mechanism. The significance of these conclusions is discussed with respect to the interaction of plasma lipoproteins with the endothelium in vivo. 301 refs

  1. Activation of Brain Somatostatin Signaling Suppresses CRF Receptor-Mediated Stress Response.

    Science.gov (United States)

    Stengel, Andreas; Taché, Yvette F

    2017-01-01

    Corticotropin-releasing factor (CRF) is the hallmark brain peptide triggering the response to stress and mediates-in addition to the stimulation of the hypothalamus-pituitary-adrenal (HPA) axis-other hormonal, behavioral, autonomic and visceral components. Earlier reports indicate that somatostatin-28 injected intracerebroventricularly counteracts the acute stress-induced ACTH and catecholamine release. Mounting evidence now supports that activation of brain somatostatin signaling exerts a broader anti-stress effect by blunting the endocrine, autonomic, behavioral (with a focus on food intake) and visceral gastrointestinal motor responses through the involvement of distinct somatostatin receptor subtypes.

  2. Nitric Oxide Orchestrates a Power-Law Modulation of Sympathetic Firing Behaviors in Neonatal Rat Spinal Cords

    Directory of Open Access Journals (Sweden)

    Chun-Kuei Su

    2018-03-01

    Full Text Available Nitric oxide (NO is a diffusible gas and has multifarious effects on both pre- and postsynaptic events. As a consequence of complex excitatory and inhibitory integrations, NO effects on neuronal activities are heterogeneous. Using in vitro preparations of neonatal rats that retain the splanchnic sympathetic nerves and the thoracic spinal cord as an experimental model, we report here that either enhancement or attenuation of NO production in the neonatal rat spinal cords could increase, decrease, or not change the spontaneous firing behaviors recorded from splanchnic sympathetic single fibers. To elucidate the mathematical features of NO-mediated heterogeneous responses, the ratios of changes in firing were plotted against their original firing rates. In log-log plots, a linear data distribution demonstrated that NO-mediated heterogeneity in sympathetic firing responses was well described by a power function. Selective antagonists were applied to test if glycinergic, GABAergic, glutamatergic, and cholinergic neurotransmission in the spinal cord are involved in NO-mediated power-law firing modulations (plFM. NO-mediated plFM diminished in the presence of mecamylamine (an open-channel blocker of nicotinic cholinergic receptors, indicating that endogenous nicotinic receptor activities were essential for plFM. Applications of strychnine (a glycine receptor blocker, gabazine (a GABAA receptor blocker, or kynurenate (a broad-spectrum ionotropic glutamate receptor blocker also caused plFM. However, strychnine- or kynurenate-induced plFM was diminished by L-NAME (an NO synthase inhibitor pretreatments, indicating that the involvements of glycine or ionotropic glutamate receptor activities in plFM were secondary to NO signaling. To recapitulate the arithmetic natures of the plFM, the plFM were simulated by firing changes in two components: a step increment and a fractional reduction of their basal firing activities. Ionotropic glutamate receptor

  3. Inhibition of IL-1β Signaling Normalizes NMDA-Dependent Neurotransmission and Reduces Seizure Susceptibility in a Mouse Model of Creutzfeldt-Jakob Disease.

    Science.gov (United States)

    Bertani, Ilaria; Iori, Valentina; Trusel, Massimo; Maroso, Mattia; Foray, Claudia; Mantovani, Susanna; Tonini, Raffaella; Vezzani, Annamaria; Chiesa, Roberto

    2017-10-25

    brain levels of the inflammatory cytokine IL-1β. Here we show that blocking IL-1β receptors with anakinra, the human recombinant form of the endogenous IL-1 receptor antagonist used to treat rheumatoid arthritis, normalizes hippocampal neurotransmission and reduces seizure susceptibility in a CJD mouse model. These results link neuroinflammation to defective neurotransmission and the enhanced susceptibility to seizures in CJD and raise the possibility that targeting IL-1β with clinically available drugs may be beneficial for symptomatic treatment of the disease. Copyright © 2017 the authors 0270-6474/17/3710278-12$15.00/0.

  4. Cortical inhibition, pH and cell excitability in epilepsy: what are optimal targets for antiepileptic interventions?

    Science.gov (United States)

    Pavlov, Ivan; Kaila, Kai; Kullmann, Dimitri M; Miles, Richard

    2013-01-01

    Epilepsy is characterised by the propensity of the brain to generate spontaneous recurrent bursts of excessive neuronal activity, seizures. GABA-mediated inhibition is critical for restraining neuronal excitation in the brain, and therefore potentiation of GABAergic neurotransmission is commonly used to prevent seizures. However, data obtained in animal models of epilepsy and from human epileptic tissue suggest that GABA-mediated signalling contributes to interictal and ictal activity. Prolonged activation of GABAA receptors during epileptiform bursts may even initiate a shift in GABAergic neurotransmission from inhibitory to excitatory and so have a proconvulsant action. Direct targeting of the membrane mechanisms that reduce spiking in glutamatergic neurons may better control neuronal excitability in epileptic tissue. Manipulation of brain pH may be a promising approach and recent advances in gene therapy and optogenetics seem likely to provide further routes to effective therapeutic intervention. PMID:22890709

  5. The SRC homology 2 domain of Rin1 mediates its binding to the epidermal growth factor receptor and regulates receptor endocytosis.

    Science.gov (United States)

    Barbieri, M Alejandro; Kong, Chen; Chen, Pin-I; Horazdovsky, Bruce F; Stahl, Philip D

    2003-08-22

    Activated epidermal growth factor receptors (EGFRs) recruit intracellular proteins that mediate receptor signaling and endocytic trafficking. Rin1, a multifunctional protein, has been shown to regulate EGFR internalization (1). Here we show that EGF stimulation induces a specific, rapid, and transient membrane recruitment of Rin1 and that recruitment is dependent on the Src homology 2 (SH2) domain of Rin1. Immunoprecipitation of EGFR is accompanied by co-immunoprecipitation of Rin1 in a time- and ligand-dependent manner. Association of Rin1 and specifically the SH2 domain of Rin1 with the EGFR was dependent on tyrosine phosphorylation of the intracellular domain of the EGFR. The recruitment of Rin1, observed by light microscopy, indicated that although initially cytosolic, Rin1 was recruited to both plasma membrane and endosomes following EGF addition. Moreover, the expression of the SH2 domain of Rin1 substantially impaired the internalization of EGF without affecting internalization of transferrin. Finally, we found that Rin1 co-immunoprecipitated with a number of tyrosine kinase receptors but not with cargo endocytic receptors. These results indicate that Rin1 provides a link via its SH2 domain between activated tyrosine kinase receptors and the endocytic pathway through the recruitment and activation of Rab5a.

  6. Disrupted Co-activation of Interneurons and Hippocampal Network after Focal Kainate Lesion

    Directory of Open Access Journals (Sweden)

    Lim-Anna Sieu

    2017-11-01

    Full Text Available GABAergic interneurons are known to control activity balance in physiological conditions and to coordinate hippocampal networks during cognitive tasks. In temporal lobe epilepsy interneuron loss and consecutive network imbalance could favor pathological hypersynchronous epileptic discharges. We tested this hypothesis in mice by in vivo unilateral epileptogenic hippocampal kainate lesion followed by in vitro recording of extracellular potentials and patch-clamp from GFP-expressing interneurons in CA3, in an optimized recording chamber. Slices from lesioned mice displayed, in addition to control synchronous events, larger epileptiform discharges. Despite some ipsi/contralateral and layer variation, interneuron density tended to decrease, average soma size to increase. Their membrane resistance decreased, capacitance increased and contralateral interneuron required higher current intensity to fire action potentials. Examination of synchronous discharges of control and larger amplitudes, revealed that interneurons were biased to fire predominantly with the largest population discharges. Altogether, these observations suggest that the overall effect of reactive cell loss, hypertrophy and reduced contralateral excitability corresponds to interneuron activity tuning to fire with larger population discharges. Such cellular and network mechanisms may contribute to a runaway path toward epilepsy.

  7. Novel time-dependent vascular actions of {delta}{sup 9}-tetrahydrocannabinol mediated by peroxisome proliferator-activated receptor gamma

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, Saoirse E [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Tarling, Elizabeth J [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Bennett, Andrew J [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Kendall, David A [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Randall, Michael D [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom)

    2005-11-25

    Cannabinoids have widespread effects on the cardiovascular system, only some of which are mediated via G-protein-coupled cell surface receptors. The active ingredient of cannabis, {delta}{sup 9}-tetrahydrocannabinol (THC), causes acute vasorelaxation in various arteries. Here we show for the first time that THC also causes slowly developing vasorelaxation through activation of peroxisome proliferator-activated receptors gamma (PPAR{gamma}). In vitro, THC (10 {mu}M) caused time-dependent vasorelaxation of rat isolated arteries. Time-dependent vasorelaxation to THC was similar to that produced by the PPAR{gamma} agonist rosiglitazone and was inhibited by the PPAR{gamma} antagonist GW9662 (1 {mu}M), but not the cannabinoid CB{sub 1} receptor antagonist AM251 (1 {mu}M). Time-dependent vasorelaxation to THC requires an intact endothelium, nitric oxide, production of hydrogen peroxide, and de novo protein synthesis. In transactivation assays in cultured HEK293 cells, THC-activated PPAR{gamma}, transiently expressed in combination with retinoid X receptor {alpha} and a luciferase reporter gene, in a concentration-dependent manner (100 nM-10 {mu}M). In vitro incubation with THC (1 or 10 {mu}M, 8 days) stimulated adipocyte differentiation in cultured 3T3L1 cells, a well-accepted property of PPAR{gamma} ligands. The present results provide strong evidence that THC is a PPAR{gamma} ligand, stimulation of which causes time-dependent vasorelaxation, implying some of the pleiotropic effects of cannabis may be mediated by nuclear receptors.

  8. Astrocytic β2-adrenergic receptors mediate hippocampal long-term memory consolidation

    KAUST Repository

    Gao, Virginia; Suzuki, Akinobu; Magistretti, Pierre J.; Lengacher, Sylvain; Pollonini, Gabriella; Steinman, Michael Q.; Alberini, Cristina M.

    2016-01-01

    Emotionally relevant experiences form strong and long-lasting memories by critically engaging the stress hormone/neurotransmitter noradrenaline, which mediates and modulates the consolidation of these memories. Noradrenaline acts through adrenergic receptors (ARs), of which β2- Adrenergic receptors (βARs) are of particular importance. The differential anatomical and cellular distribution of βAR subtypes in the brain suggests that they play distinct roles in memory processing, although much about their specific contributions and mechanisms of action remains to be understood. Here we show that astrocytic rather than neuronal β2ARs in the hippocampus play a key role in the consolidation of a fear-based contextual memory. These hippocampal β2ARs, but not β1ARs, are coupled to the training-dependent release of lactate from astrocytes, which is necessary for long- Term memory formation and for underlying molecular changes. This key metabolic role of astrocytic β2ARs may represent a novel target mechanism for stress-related psychopathologies and neurodegeneration.

  9. Astrocytic β2-adrenergic receptors mediate hippocampal long-term memory consolidation

    KAUST Repository

    Gao, Virginia

    2016-07-12

    Emotionally relevant experiences form strong and long-lasting memories by critically engaging the stress hormone/neurotransmitter noradrenaline, which mediates and modulates the consolidation of these memories. Noradrenaline acts through adrenergic receptors (ARs), of which β2- Adrenergic receptors (βARs) are of particular importance. The differential anatomical and cellular distribution of βAR subtypes in the brain suggests that they play distinct roles in memory processing, although much about their specific contributions and mechanisms of action remains to be understood. Here we show that astrocytic rather than neuronal β2ARs in the hippocampus play a key role in the consolidation of a fear-based contextual memory. These hippocampal β2ARs, but not β1ARs, are coupled to the training-dependent release of lactate from astrocytes, which is necessary for long- Term memory formation and for underlying molecular changes. This key metabolic role of astrocytic β2ARs may represent a novel target mechanism for stress-related psychopathologies and neurodegeneration.

  10. Dopamine D4 receptor activation increases hippocampal gamma oscillations by enhancing synchronization of fast-spiking interneurons.

    Directory of Open Access Journals (Sweden)

    Richard Andersson

    Full Text Available BACKGROUND: Gamma oscillations are electric activity patterns of the mammalian brain hypothesized to serve attention, sensory perception, working memory and memory encoding. They are disrupted or altered in schizophrenic patients with associated cognitive deficits, which persist in spite of treatment with antipsychotics. Because cognitive symptoms are a core feature of schizophrenia it is relevant to explore signaling pathways that potentially regulate gamma oscillations. Dopamine has been reported to decrease gamma oscillation power via D1-like receptors. Based on the expression pattern of D4 receptors (D4R in hippocampus, and pharmacological effects of D4R ligands in animals, we hypothesize that they are in a position to regulate gamma oscillations as well. METHODOLOGY/PRINCIPAL FINDINGS: To address this hypothesis we use rat hippocampal slices and kainate-induced gamma oscillations. Local field potential recordings as well as intracellular recordings of pyramidal cells, fast-spiking and non-fast-spiking interneurons were carried out. We show that D4R activation with the selective ligand PD168077 increases gamma oscillation power, which can be blocked by the D4R-specific antagonist L745,870 as well as by the antipsychotic drug Clozapine. Pyramidal cells did not exhibit changes in excitatory or inhibitory synaptic current amplitudes, but inhibitory currents became more coherent with the oscillations after application of PD168077. Fast-spiking, but not non-fast spiking, interneurons, increase their action potential phase-coupling and coherence with regard to ongoing gamma oscillations in response to D4R activation. Among several possible mechanisms we found that the NMDA receptor antagonist AP5 also blocks the D4R mediated increase in gamma oscillation power. CONCLUSIONS/SIGNIFICANCE: We conclude that D4R activation affects fast-spiking interneuron synchronization and thereby increases gamma power by an NMDA receptor-dependent mechanism. This

  11. The cannabinoid receptor 2 agonist, β-caryophyllene, reduced voluntary alcohol intake and attenuated ethanol-induced place preference and sensitivity in mice.

    Science.gov (United States)

    Al Mansouri, Shamma; Ojha, Shreesh; Al Maamari, Elyazia; Al Ameri, Mouza; Nurulain, Syed M; Bahi, Amine

    2014-09-01

    Several recent studies have suggested that brain CB2 cannabinoid receptors play a major role in alcohol reward. In fact, the implication of cannabinoid neurotransmission in the reinforcing effects of ethanol (EtOH) is becoming increasingly evident. The CB2 receptor agonist, β-caryophyllene (BCP) was used to investigate the role of the CB2 receptors in mediating alcohol intake and ethanol-induced conditioned place preference (EtOH-CPP) and sensitivity in mice. The effect of BCP on alcohol intake was evaluated using the standard two-bottle choice drinking method. The mice were presented with increasing EtOH concentrations and its consumption was measured daily. Consumption of saccharin and quinine solutions was measured following the EtOH preference tests. Finally, the effect of BCP on alcohol reward and sensitivity was tested using an unbiased EtOH-CPP and loss of righting-reflex (LORR) procedures, respectively. BCP dose-dependently decreased alcohol consumption and preference. Additionally, BCP-injected mice did not show any difference from vehicle mice in total fluid intake in a 24-hour paradigm nor in their intake of graded concentrations of saccharin or quinine, suggesting that the CB2 receptor activation did not alter taste function. More importantly, BCP inhibited EtOH-CPP acquisition and exacerbated LORR duration. Interestingly, these effects were abrogated when mice were pre-injected with a selective CB2 receptor antagonist, AM630. Overall, the CB2 receptor system appears to be involved in alcohol dependence and sensitivity and may represent a potential pharmacological target for the treatment of alcoholism. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Distinct phosphotyrosines on a growth factor receptor bind to specific molecules that mediate different signaling pathways.

    Science.gov (United States)

    Fantl, W J; Escobedo, J A; Martin, G A; Turck, C W; del Rosario, M; McCormick, F; Williams, L T

    1992-05-01

    The receptor for platelet-derived growth factor (PDGF) binds two proteins containing SH2 domains, GTPase activating protein (GAP) and phosphatidylinositol 3-kinase (PI3-kinase). The sites on the receptor that mediate this interaction were identified by using phosphotyrosine-containing peptides representing receptor sequences to block specifically binding of either PI3-kinase or GAP. These results suggested that PI3-kinase binds two phosphotyrosine residues, each located in a 5 aa motif with an essential methionine at the fourth position C-terminal to the tyrosine. Point mutations at these sites caused a selective elimination of PI3-kinase binding and loss of PDGF-stimulated DNA synthesis. Mutation of the binding site for GAP prevented the receptor from associating with or phosphorylating GAP, but had no effect on PI3-kinase binding and little effect on DNA synthesis. Therefore, GAP and PI3-kinase interact with the receptor by binding to different phosphotyrosine-containing sequence motifs.

  13. Adenosine A₁ and A₂A receptor-mediated modulation of acetylcholine release in the mice neuromuscular junction.

    Science.gov (United States)

    Garcia, Neus; Priego, Mercedes; Obis, Teresa; Santafe, Manel M; Tomàs, Marta; Besalduch, Nuria; Lanuza, M Angel; Tomàs, Josep

    2013-07-01

    Immunocytochemistry shows that purinergic receptors (P1Rs) type A1 and A2A (A1 R and A2 A R, respectively) are present in the nerve endings at the P6 and P30 Levator auris longus (LAL) mouse neuromuscular junctions (NMJs). As described elsewhere, 25 μm adenosine reduces (50%) acetylcholine release in high Mg(2+) or d-tubocurarine paralysed muscle. We hypothesize that in more preserved neurotransmission machinery conditions (blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB) the physiological role of the P1Rs in the NMJ must be better observed. We found that the presence of a non-selective P1R agonist (adenosine) or antagonist (8-SPT) or selective modulators of A1 R or A2 A R subtypes (CCPA and DPCPX, or CGS-21680 and SCH-58261, respectively) does not result in any changes in the evoked release. However, P1Rs seem to be involved in spontaneous release (miniature endplate potentials MEPPs) because MEPP frequency is increased by non-selective block but decreased by non-selective stimulation, with A1 Rs playing the main role. We assayed the role of P1Rs in presynaptic short-term plasticity during imposed synaptic activity (40 Hz for 2 min of supramaximal stimuli). Depression is reduced by micromolar adenosine but increased by blocking P1Rs with 8-SPT. Synaptic depression is not affected by the presence of selective A1 R and A2 A R modulators, which suggests that both receptors need to collaborate. Thus, A1 R and A2 A R might have no real effect on neuromuscular transmission in resting conditions. However, these receptors can conserve resources by limiting spontaneous quantal leak of acetylcholine and may protect synaptic function by reducing the magnitude of depression during repetitive activity. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  14. Receptor-mediated internalization of [3H]-neurotensin in synaptosomal preparations from rat neostriatum.

    Science.gov (United States)

    Nguyen, Ha Minh Ky; Cahill, Catherine M; McPherson, Peter S; Beaudet, Alain

    2002-06-01

    Following its binding to somatodendritic receptors, the neuropeptide neurotensin (NT) internalizes via a clathrin-mediated process. In the present study, we investigated whether NT also internalizes presynaptically using synaptosomes from rat neostriatum, a region in which NT1 receptors are virtually all presynaptic. Binding of [(3)H]-NT to striatal synaptosomes in the presence of levocabastine to block NT2 receptors is specific, saturable, and has NT1 binding properties. A significant fraction of the bound radioactivity is resistant to hypertonic acid wash indicating that it is internalized. Internalization of [(3)H]-NT, like that of [(125)I]-transferrin, is blocked by sucrose and low temperature, consistent with endocytosis occurring via a clathrin-dependent pathway. However, contrary to what was reported at the somatodendritic level, neither [(3)H]-NT nor [(125)I]-transferrin internalization in synaptosomes is sensitive to the endocytosis inhibitor phenylarsine oxide. Moreover, treatment of synaptosomes with monensin, which prevents internalized receptors from recycling to the plasma membrane, reduces [(3)H]-NT binding and internalization, suggesting that presynaptic NT1 receptors, in contrast to somatodendritic ones, are recycled back to the plasma membrane. Taken together, these results suggest that NT internalizes in nerve terminals via an endocytic pathway that is related to, but is mechanistically distinct from that responsible for NT internalization in nerve cell bodies.

  15. Synaptic glutamate spillover increases NMDA receptor reliability at the cerebellar glomerulus

    OpenAIRE

    Mitchell, Cassie S.; Lee, Robert H.

    2011-01-01

    Glutamate spillover in the mossy fiber to granule cell cerebellar glomeruli has been hypothesized to increase neurotransmission reliability. In this study, we evaluate this hypothesis using an experimentally-based quantitative model of glutamate spillover on the N-methyl-d-aspartate receptors (NMDA-Rs) at the cerebellar glomerulus. The transient and steady-state responses of NMDA-Rs were examined over a physiological range of firing rates. Examined cases included direct glutamate release acti...

  16. Cell-cell adhesion mediated by binding of membrane-anchored transforming growth factor α to epidermal growth factor receptors promotes cell proliferation

    International Nuclear Information System (INIS)

    Anklesaria, P.; Greenberger, J.S.; Teixido, J.; Laiho, M.; Massague, J.; Pierce, J.H.

    1990-01-01

    The precursor for transforming growth factor α, pro-TGF-α, is a cell surface glycoprotein that can establish contact with epidermal growth factor (EGF) receptors on adjacent cells. To examine whether the pro-TGF-α/EGF receptor pair can simultaneously mediate cell adhesion and promote cell proliferation, the authors have expressed pro-TGF-α in a bone marrow stromal cell line labeled with [ 35 S] cysteine. Expression of pro-TGF-α allows these cells to support long-term attachment of an EGF/interleukin-3-dependent hematopoietic progenitor cell line that expresses EGF receptors but is unable to adhere to normal stroma. This interaction is inhibited by soluble EGF receptor ligands. Further, the hematopoietic progenitor cells replicate their DNA while they are attached to the stromal cell layer and become foci of sustained cell proliferation. Thus, pro-TGF-α and the EGF receptor can function as mediators of intercellular adhesion and this interaction may promote a mitogenic response. They propose the term juxtacrine to designate this form of stimulation between adjacent cells

  17. Ketamine and ketamine metabolites as novel estrogen receptor ligands: Induction of cytochrome P450 and AMPA glutamate receptor gene expression.

    Science.gov (United States)

    Ho, Ming-Fen; Correia, Cristina; Ingle, James N; Kaddurah-Daouk, Rima; Wang, Liewei; Kaufmann, Scott H; Weinshilboum, Richard M

    2018-04-03

    Major depressive disorder (MDD) is the most common psychiatric illness worldwide, and it displays a striking sex-dependent difference in incidence, with two thirds of MDD patients being women. Ketamine treatment can produce rapid antidepressant effects in MDD patients, effects that are mediated-at least partially-through glutamatergic neurotransmission. Two active metabolites of ketamine, (2R,6R)-hydroxynorketamine (HNK) and (2S,6S)-HNK, also appear to play a key role in ketamine's rapid antidepressant effects through the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors. In the present study, we demonstrated that estrogen plus ketamine or estrogen plus active ketamine metabolites displayed additive effects on the induction of the expression of AMPA receptor subunits. In parallel, the expression of estrogen receptor alpha (ERα) was also significantly upregulated. Even more striking, radioligand binding assays demonstrated that [ 3 H]-ketamine can directly bind to ERα (K D : 344.5 ± 13 nM). Furthermore, ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites displayed similar affinity for ERα (IC 50 : 2.31 ± 0.1, 3.40 ± 0.2, and 3.53 ± 0.2 µM, respectively) as determined by [ 3 H]-ketamine displacement assays. Finally, induction of AMPA receptors by either estrogens or ketamine and its metabolites was lost when ERα was knocked down or silenced pharmacologically. These results suggest a positive feedback loop by which estrogens can augment the effects of ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites on the ERα-induced transcription of CYP2A6 and CYP2B6, estrogen inducible enzymes that catalyze ketamine's biotransformation to form the two active metabolites. These observations provide novel insight into ketamine's molecular mechanism(s) of action and have potential implications for the treatment of MDD. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Androgen Receptor Deregulation Drives Bromodomain-Mediated Chromatin Alterations in Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Alfonso Urbanucci

    2017-06-01

    Full Text Available Global changes in chromatin accessibility may drive cancer progression by reprogramming transcription factor (TF binding. In addition, histone acetylation readers such as bromodomain-containing protein 4 (BRD4 have been shown to associate with these TFs and contribute to aggressive cancers including prostate cancer (PC. Here, we show that chromatin accessibility defines castration-resistant prostate cancer (CRPC. We show that the deregulation of androgen receptor (AR expression is a driver of chromatin relaxation and that AR/androgen-regulated bromodomain-containing proteins (BRDs mediate this effect. We also report that BRDs are overexpressed in CRPCs and that ATAD2 and BRD2 have prognostic value. Finally, we developed gene stratification signature (BROMO-10 for bromodomain response and PC prognostication, to inform current and future trials with drugs targeting these processes. Our findings provide a compelling rational for combination therapy targeting bromodomains in selected patients in which BRD-mediated TF binding is enhanced or modified as cancer progresses.

  19. Respiratory Plasticity Following Spinal Injury: Role of Chloride-Dependent Inhibitory Neurotransmission

    Science.gov (United States)

    2016-12-01

    the extent of injury to determine if variable severity of injury might account for these conflicting responses. Our work on this project has...of phrenic motor output post-CSC; we are currently determining if variability in injury severity can account for these conflicting findings. These...Award Number: W81XWH-13-1-0410 TITLE: Respiratory Plasticity Following Spinal Injury: Role of Chloride-Dependent Inhibitory Neurotransmission

  20. The Role of PPAR Receptors and Leukotriene B4 Receptors in Mediating the Effects of LY293111 in Pancreatic Cancer

    Directory of Open Access Journals (Sweden)

    Thomas E. Adrian

    2008-01-01

    Full Text Available Pancreatic cancer is a devastating disease in which current therapies are inadequate. Separate lines of research have identified the 5-lipoxygenase/leukotriene B4 receptor pathway and the PPAR pathway as potential targets for prevention or treatment of this disease. LY293111 was originally designed as a potent leukotriene B4 receptor antagonist for treatment of inflammatory conditions. LY293111 was also known to have inhibitory effects on 5-lipoxygenase, which is upstream of the production of leukotrienes. LY293111 was shown to have potent anticancer effects in pancreatic cancer and several other solid malignancies, where it caused cell cycle arrest and marked apoptosis. Subsequently, it came to light that LY293111 exhibited PPAR agonist activity in addition to its effects on the 5-lipoxygenase pathway. This raises the question of which of the two targets is of greatest importance with regard to the anticancer effects of this agent. The evidence to date is not conclusive, but suggests that the effects of LY293111 may be mediated by both LTB4 receptors and PPAR.

  1. Decreased α1-adrenergic receptor-mediated inositide hydrolysis in neurons from hypertensive rat brain

    International Nuclear Information System (INIS)

    Feldstein, J.B.; Gonzales, R.A.; Baker, S.P.; Sumners, C.; Crews, F.T.; Raizada, M.K.

    1986-01-01

    The expression of α 1 -adrenergic receptors and norepinephrine (NE)-stimulated hydrolysis of inositol phospholipid has been studied in neuronal cultures from the brains of normotensive (Wistar-Kyoto, WKY) and spontaneously hypertensive (SH) rats. Binding of 125 I-1-[β-(4-hydroxyphenyl)-ethyl-aminomethyl] tetralone (HEAT) to neuronal membranes was 68-85% specific and was rapid. Competition-inhibition experiments with various agonists and antagonists suggested that 125 I-HEAT bound selectively to α 1 -adrenergic receptors. Specific binding of 125 I-HEAT to neuronal membranes from SH rat brain cultures was 30-45% higher compared with binding in WKY normotensive controls. This increase was attributed to an increase in the number of α 1 -adrenergic receptors on SH rat brain neurons. Incubation of neuronal cultures of rat brain from both strains with NE resulted in a concentration-dependent stimulation of release of inositol phosphates, although neurons from SH rat brains were 40% less responsive compared with WKY controls. The decrease in responsiveness of SH rat brain neurons to NE, even though the α 1 -adrenergic receptors are increased, does not appear to be due to a general defect in membrane receptors and postreceptor signal transduction mechanisms. This is because neither the number of muscarinic-cholinergic receptors nor the carbachol-stimulated release of inositol phosphates is different in neuronal cultures from the brains of SH rats compared with neuronal cultures from the brains of WKY rats. These observations suggest that the increased expression of α 1 -adrenergic receptors does not parallel the receptor-mediated inositol phosphate hydrolysis in neuronal cultures from SH rat brain

  2. Estrogen promotes megakaryocyte polyploidization via estrogen receptor beta-mediated transcription of GATA1.

    Science.gov (United States)

    Du, C; Xu, Y; Yang, K; Chen, S; Wang, X; Wang, S; Wang, C; Shen, M; Chen, F; Chen, M; Zeng, D; Li, F; Wang, T; Wang, F; Zhao, J; Ai, G; Cheng, T; Su, Y; Wang, J

    2017-04-01

    Estrogen is reported to be involved in thrombopoiesis and the disruption of its signaling may cause myeloproliferative disease, yet the underlying mechanisms remain largely unknown. GATA-binding factor 1 (GATA1) is a key regulator of megakaryocyte (MK) differentiation and its deficiency will lead to megakaryoblastic leukemia. Here we show that estrogen can dose-dependently promote MK polyploidization and maturation via activation of estrogen receptor beta (ERβ), accompanied by a significant upregulation of GATA1. Chromatin immunoprecipitation and a dual luciferase assay demonstrate that ERβ can directly bind the promoter region of GATA1 and activate its transcription. Steroid receptor coactivator 3 (SRC3) is involved in ERβ-mediated GATA1 transcription. The deficiency of ERβ or SRC3, similar to the inhibition of GATA1, leads to the impediment of estrogen-induced MK polyploidization and platelet production. Further investigations reveal that signal transducer and activator of transcription 1 signaling pathway downstream of GATA1 has a crucial role in estrogen-induced MK polyploidization, and ERβ-mediated GATA1 upregulation subsequently enhances nuclear factor erythroid-derived 2 expression, thereby promoting proplatelet formation and platelet release. Our study provides a deep insight into the molecular mechanisms of estrogen signaling in regulating thrombopoiesis and the pathogenesis of ER deficiency-related leukemia.

  3. Activation of somatostatin 2 receptors in the brain and the periphery induces opposite changes in circulating ghrelin levels: functional implications

    Directory of Open Access Journals (Sweden)

    Andreas eStengel

    2013-01-01

    Full Text Available Somatostatin is an important modulator of neurotransmission in the central nervous system and acts as a potent inhibitor of hormone and exocrine secretion and regulator of cell proliferation in the periphery. These pleiotropic actions occur through interaction with five G-protein coupled somatostatin receptor subtypes (sst1-5 that are widely expressed in the brain and peripheral organs. The characterization of somatostatin’s effects can be investigated by pharmacological or genetic approaches using newly developed selective sst agonists and antagonists and mice lacking specific sst subtypes. Recent evidence points towards a divergent action of somatostatin in the brain and in the periphery to regulate circulating levels of ghrelin, an orexigenic hormone produced by the endocrine X/A-like cells in the gastric mucosa. Somatostatin interacts with the sst2 in the brain to induce an increase in basal ghrelin plasma levels and counteracts the visceral stress-related decrease in circulating ghrelin in rats. By contrast, stimulation of peripheral somatostatin-sst2 signaling results in the inhibition of basal ghrelin release and mediates the postoperative decrease in circulating ghrelin in rats. The peripheral sst2-mediated reduction of plasma ghrelin is likely to involve a paracrine action of D-cell derived somatostatin acting on sst2 bearing X/A-like ghrelin cells in the gastric mucosa. The other member of the somatostatin family, named cortistatin, in addition to binding to sst1-5 also directly interacts with the ghrelin receptor and therefore may simultaneously modulate ghrelin release and actions at target sites bearing ghrelin receptors representing a link between the ghrelin and somatostatin systems.

  4. β-Adrenergic receptor-mediated suppression of interleukin 2 receptors in human lymphocytes

    International Nuclear Information System (INIS)

    Feldman, R.D.; Hunninghake, G.W.; McArdle, W.L.

    1987-01-01

    Adrenergic receptor agonists are know to attenuate the proliferative response of human lymphocytes after activation; however, their mechanism of action is unknown. Since expression of interleukin 2 (IL-2) receptors is a prerequisite for proliferation, the effect of β-adrenergic receptor agonists on lymphocyte IL-2 receptors was studied on both mitogen-stimulated lymphocytes and IL-2-dependent T lymphocyte cell lines. In both cell types the β-adrenergic receptor agonist isoproterenol blocked the expression of IL-2 receptors, as determined with the IL-2 receptor anti-TAC antibody. To determine the effect of β-adrenergic agonists on expression of the high affinity IL-2 receptors, [ 125 I]IL-2 binding studies were performed at concentrations selective for high affinity sites. No significant effect of β-adrenergic agonists on high affinity IL-2 receptor sites could be detected. The data demonstrate that β-adrenergic receptor agonists down-regulate IL-2 receptors primarily affecting low affinity sites

  5. MEL-18 loss mediates estrogen receptor-α downregulation and hormone independence.

    Science.gov (United States)

    Lee, Jeong-Yeon; Won, Hee-Young; Park, Ji-Hye; Kim, Hye-Yeon; Choi, Hee-Joo; Shin, Dong-Hui; Kang, Ju-Hee; Woo, Jong-Kyu; Oh, Seung-Hyun; Son, Taekwon; Choi, Jin-Woo; Kim, Sehwan; Kim, Hyung-Yong; Yi, Kijong; Jang, Ki-Seok; Oh, Young-Ha; Kong, Gu

    2015-05-01

    The polycomb protein MEL-18 has been proposed as a tumor suppressor in breast cancer; however, its functional relevance to the hormonal regulation of breast cancer remains unknown. Here, we demonstrated that MEL-18 loss contributes to the hormone-independent phenotype of breast cancer by modulating hormone receptor expression. In multiple breast cancer cohorts, MEL-18 was markedly downregulated in triple-negative breast cancer (TNBC). MEL-18 expression positively correlated with the expression of luminal markers, including estrogen receptor-α (ER-α, encoded by ESR1). MEL-18 loss was also associated with poor response to antihormonal therapy in ER-α-positive breast cancer. Furthermore, whereas MEL-18 loss in luminal breast cancer cells resulted in the downregulation of expression and activity of ER-α and the progesterone receptor (PR), MEL-18 overexpression restored ER-α expression in TNBC. Consistently, in vivo xenograft experiments demonstrated that MEL-18 loss induces estrogen-independent growth and tamoxifen resistance in luminal breast cancer, and that MEL-18 overexpression confers tamoxifen sensitivity in TNBC. MEL-18 suppressed SUMOylation of the ESR1 transactivators p53 and SP1, thereby driving ESR1 transcription. MEL-18 facilitated the deSUMOylation process by inhibiting BMI-1/RING1B-mediated ubiquitin-proteasomal degradation of SUMO1/sentrin-specific protease 1 (SENP1). These findings demonstrate that MEL-18 is a SUMO-dependent regulator of hormone receptors and suggest MEL-18 expression as a marker for determining the antihormonal therapy response in patients with breast cancer.

  6. Serotonin(2) receptors mediate respiratory recovery after cervical spinal cord hemisection in adult rats.

    Science.gov (United States)

    Zhou, S Y; Basura, G J; Goshgarian, H G

    2001-12-01

    The aim of the present study was to specifically investigate the involvement of serotonin [5-hydroxytryptamine (5-HT(2))] receptors in 5-HT-mediated respiratory recovery after cervical hemisection. Experiments were conducted on C(2) spinal cord-hemisected, anesthetized (chloral hydrate, 400 mg/kg ip), vagotomized, pancuronium- paralyzed, and artificially ventilated female Sprague-Dawley rats in which CO(2) levels were monitored and maintained. Twenty-four hours after spinal hemisection, the ipsilateral phrenic nerve displayed no respiratory-related activity indicative of a functionally complete hemisection. Intravenous administration of the 5-HT(2A/2C)-receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) induced respiratory-related activity in the phrenic nerve ipsilateral to hemisection under conditions in which CO(2) was maintained at constant levels and augmented the activity induced under conditions of hypercapnia. The effects of DOI were found to be dose dependent, and the recovery of activity could be maintained for up to 2 h after a single injection. DOI-induced recovery was attenuated by the 5-HT(2)-receptor antagonist ketanserin but not with the 5-HT(2C)-receptor antagonist RS-102221, suggesting that 5-HT(2A) and not necessarily 5-HT(2C) receptors may be involved in the induction of respiratory recovery after cervical spinal cord injury.

  7. Halothane inhibits the cholinergic-receptor-mediated influx of calcium in primary culture of bovine adrenal medulla cells

    International Nuclear Information System (INIS)

    Yashima, N.; Wada, A.; Izumi, F.

    1986-01-01

    Adrenal medulla cells are cholinoceptive cells. Stimulation of the acetylcholine receptor causes the influx of Ca to the cells, and Ca acts as the coupler of the stimulus-secretion coupling. In this study, the authors investigated the effects of halothane on the receptor-mediated influx of 45 Ca using cultured bovine adrenal medulla cells. Halothane at clinical concentrations (0.5-2%) inhibited the influx of 45 Ca caused by carbachol, with simultaneous inhibition of catecholamine secretion. The influx of 45 Ca and the secretion of catecholamines caused by K depolarization were inhibited by a large concentration of Mg, which competes with Ca at Ca channels, but not inhibited by halothane. Inhibition of the 45 Ca influx by halothane was not overcome by increase in the carbachol concentration. Inhibition of the 45 Ca influx by halothane was examined in comparison with that caused by a large concentration of Mg by the application of Scatchard analysis as the function of the external Ca concentration. Halothane decreased the maximal influx of 45 Ca without altering the apparent kinetic constant of Ca to Ca channels. On the contrary, a large concentration of Mg increased the apparent kinetic constant without altering the maximal influx of 45 Ca. Based on these findings, the authors suggest that inhibition of the 45 Ca influx by halothane was not due to the direct competitive inhibition of Ca channels, nor to the competitive antagonism of agonist-receptor interaction. As a possibility, halothane seems to inhibit the receptor-mediated activation of Ca channels through the interference of coupling between the receptor and Ca channels

  8. Activation of synaptic and extrasynaptic glycine receptors by taurine in preoptic hypothalamic neurons.

    Science.gov (United States)

    Bhattarai, Janardhan Prasad; Park, Soo Joung; Chun, Sang Woo; Cho, Dong Hyu; Han, Seong Kyu

    2015-11-03

    Taurine is an essential amino-sulfonic acid having a fundamental function in the brain, participating in both cell volume regulation and neurotransmission. Using a whole cell voltage patch clamp technique, the taurine-activated neurotransmitter receptors in the preoptic hypothalamic area (PHA) neurons were investigated. In the first set of experiments, different concentrations of taurine were applied on PHA neurons. Taurine-induced responses were concentration-dependent. Taurine-induced currents were action potential-independent and sensitive to strychnine, suggesting the involvement of glycine receptors. In addition, taurine activated not only α-homomeric, but also αβ-heteromeric glycine receptors in PHA neurons. Interestingly, a low concentration of taurine (0.5mM) activated glycine receptors, whereas a higher concentration (3mM) activated both glycine and gamma-aminobutyric acid A (GABAA) receptors in PHA neurons. These results suggest that PHA neurons are influenced by taurine and respond via glycine and GABAA receptors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Rac-mediated Stimulation of Phospholipase Cγ2 Amplifies B Cell Receptor-induced Calcium Signaling*♦

    Science.gov (United States)

    Walliser, Claudia; Tron, Kyrylo; Clauss, Karen; Gutman, Orit; Kobitski, Andrei Yu.; Retlich, Michael; Schade, Anja; Röcker, Carlheinz; Henis, Yoav I.; Nienhaus, G. Ulrich; Gierschik, Peter

    2015-01-01

    The Rho GTPase Rac is crucially involved in controlling multiple B cell functions, including those regulated by the B cell receptor (BCR) through increased cytosolic Ca2+. The underlying molecular mechanisms and their relevance to the functions of intact B cells have thus far remained unknown. We have previously shown that the activity of phospholipase Cγ2 (PLCγ2), a key constituent of the BCR signalosome, is stimulated by activated Rac through direct protein-protein interaction. Here, we use a Rac-resistant mutant of PLCγ2 to functionally reconstitute cultured PLCγ2-deficient DT40 B cells and to examine the effects of the Rac-PLCγ2 interaction on BCR-mediated changes of intracellular Ca2+ and regulation of Ca2+-regulated and nuclear-factor-of-activated-T-cell-regulated gene transcription at the level of single, intact B cells. The results show that the functional Rac-PLCγ2 interaction causes marked increases in the following: (i) sensitivity of B cells to BCR ligation; (ii) BCR-mediated Ca2+ release from intracellular stores; (iii) Ca2+ entry from the extracellular compartment; and (iv) nuclear translocation of the Ca2+-regulated nuclear factor of activated T cells. Hence, Rac-mediated stimulation of PLCγ2 activity serves to amplify B cell receptor-induced Ca2+ signaling. PMID:25903139

  10. The Pyrexia transient receptor potential channel mediates circadian clock synchronization to low temperature cycles in Drosophila melanogaster.

    Science.gov (United States)

    Wolfgang, Werner; Simoni, Alekos; Gentile, Carla; Stanewsky, Ralf

    2013-10-07

    Circadian clocks are endogenous approximately 24 h oscillators that temporally regulate many physiological and behavioural processes. In order to be beneficial for the organism, these clocks must be synchronized with the environmental cycles on a daily basis. Both light : dark and the concomitant daily temperature cycles (TCs) function as Zeitgeber ('time giver') and efficiently entrain circadian clocks. The temperature receptors mediating this synchronization have not been identified. Transient receptor potential (TRP) channels function as thermo-receptors in animals, and here we show that the Pyrexia (Pyx) TRP channel mediates temperature synchronization in Drosophila melanogaster. Pyx is expressed in peripheral sensory organs (chordotonal organs), which previously have been implicated in temperature synchronization. Flies deficient for Pyx function fail to synchronize their behaviour to TCs in the lower range (16-20°C), and this deficit can be partially rescued by introducing a wild-type copy of the pyx gene. Synchronization to higher TCs is not affected, demonstrating a specific role for Pyx at lower temperatures. In addition, pyx mutants speed up their clock after being exposed to TCs. Our results identify the first TRP channel involved in temperature synchronization of circadian clocks.

  11. The GPCR membrane receptor, DopEcR, mediates the actions of both dopamine and ecdysone to control sex pheromone perception in an insect

    Directory of Open Access Journals (Sweden)

    Antoine eAbrieux

    2014-09-01

    Full Text Available Olfactory information mediating sexual behavior is crucial for reproduction in many animals, including insects. In male moths, the macroglomerular complex of the primary olfactory center, the antennal lobe (AL is specialized in the treatment of information on the female-emitted sex pheromone. Evidence is accumulating that modulation of behavioral pheromone responses occurs through neuronal plasticity via the action of hormones and/or catecholamines. We recently showed that a G-protein-coupled receptor (GPCR, AipsDopEcR, with its homologue known in Drosophila for its double affinity to the main insect steroid hormone 20-hydroxyecdysone (20E, and dopamine (DA, present in the ALs, is involved in the behavioral response to pheromone in the moth, Agrotis ipsilon. Here we tested the role of AipsDopEcR as compared to nuclear 20E receptors in central pheromone processing combining receptor inhibition with intracellular recordings of AL neurons. We show that the sensitivity of AL neurons for the pheromone in males decreases strongly after AipsDopEcR-dsRNA injection but also after inhibition of nuclear 20E receptors. Moreover we tested the involvement of 20E and DA in the receptor-mediated behavioral modulation in wind tunnel experiments, using ligand applications and receptor inhibition treatments. We show that both ligands are necessary and act on AipsDopEcR-mediated behavior. Altogether these results indicate that the GPCR membrane receptor, AipsDopEcR, controls sex pheromone perception through the action of both 20E and DA in the central nervous system, probably in concert with 20E action through nuclear receptors.

  12. Receptor-mediated endocytosis of polypeptide hormones is a regulated process: inhibition of [125I]iodoinsulin internalization in hypoinsulinemic diabetes of rat and man

    International Nuclear Information System (INIS)

    Carpentier, J.L.; Robert, A.; Grunberger, G.; van Obberghen, E.; Freychet, P.; Orci, L.; Gorden, P.

    1986-01-01

    Much data suggest that receptor-mediated endocytosis is regulated in states of hormone excess. Thus, in hyperinsulinemic states there is an accelerated loss of cell surface insulin receptors. In the present experiments we addressed this question in hypoinsulinemic states, in which insulin binding to cell surface receptors is generally increased. In hepatocytes obtained from hypoinsulinemic streptozotocin-induced diabetic rats, [ 125 I]iodoglucagon internalization was increased, while at the same time [ 125 I]iodoinsulin internalization was decreased. The defect in [ 125 I]iodoinsulin internalization was corrected by insulin treatment of the animal. In peripheral blood monocytes from patients with type I insulinopenic diabetes, internalization of [ 125 I]iodoinsulin was impaired; this defect was not present in insulin-treated patients. These data in the hypoinsulinemic rat and human diabetes suggest that receptor-mediated endocytosis is regulated in states of insulin deficiency as well as insulin excess. Delayed or reduced internalization of the insulin-receptor complex could amplify the muted signal caused by deficient hormone secretion

  13. Alterations in brain extracellular dopamine and glycine levels following combined administration of the glycine transporter type-1 inhibitor Org-24461 and risperidone.

    Science.gov (United States)

    Nagy, Katalin; Marko, Bernadett; Zsilla, Gabriella; Matyus, Peter; Pallagi, Katalin; Szabo, Geza; Juranyi, Zsolt; Barkoczy, Jozsef; Levay, Gyorgy; Harsing, Laszlo G

    2010-12-01

    The most dominant hypotheses for the pathogenesis of schizophrenia have focused primarily upon hyperfunctional dopaminergic and hypofunctional glutamatergic neurotransmission in the central nervous system. The therapeutic efficacy of all atypical antipsychotics is explained in part by antagonism of the dopaminergic neurotransmission, mainly by blockade of D(2) dopamine receptors. N-methyl-D-aspartate (NMDA) receptor hypofunction in schizophrenia can be reversed by glycine transporter type-1 (GlyT-1) inhibitors, which regulate glycine concentrations at the vicinity of NMDA receptors. Combined drug administration with D(2) dopamine receptor blockade and activation of hypofunctional NMDA receptors may be needed for a more effective treatment of positive and negative symptoms and the accompanied cognitive deficit in schizophrenia. To investigate this type of combined drug administration, rats were treated with the atypical antipsychotic risperidone together with the GlyT-1 inhibitor Org-24461. Brain microdialysis was applied in the striatum of conscious rats and determinations of extracellular dopamine, DOPAC, HVA, glycine, glutamate, and serine concentrations were carried out using HPLC/electrochemistry. Risperidone increased extracellular concentrations of dopamine but failed to influence those of glycine or glutamate measured in microdialysis samples. Org-24461 injection reduced extracellular dopamine concentrations and elevated extracellular glycine levels but the concentrations of serine and glutamate were not changed. When risperidone and Org-24461 were added in combination, a decrease in extracellular dopamine concentrations was accompanied with sustained elevation of extracellular glycine levels. Interestingly, the extracellular concentrations of glutamate were also enhanced. Our data indicate that coadministration of an antipsychotic with a GlyT-1 inhibitor may normalize hypofunctional NMDA receptor-mediated glutamatergic neurotransmission with reduced

  14. The α7-nACh nicotinic receptor and its role in memory and selected diseases of the central nervous system

    Directory of Open Access Journals (Sweden)

    Urszula Baranowska

    2017-07-01

    Full Text Available α7-nACh is one of the major nicotinic cholinergic receptor subtypes found in the brain. It is broadly expressed in the hippocampal and cortical neurons, the regions which play a key role in memory formation. Although α7-nACh receptors may serve as postsynaptic receptors mediating classical neurotransmission, they usually function as presynaptic modulators responsible for the release of other neurotransmitters, such as glutamate, γ-aminobutyric acid, dopamine, and norepinephrine. They can, therefore, affect a wide array of neurobiological functions. In recent years, research has found that a large number of agonists and positive allosteric modulators of α7-nAChR induce beneficial effects on learning and memory. Consistently, mice deficient in chrna7 (the gene encoding α7-nAChR protein, are characterized by memory deficits. In addition, decreased expression and function of α7-nAChR is associated agoniwith many neurological diseases including schizophrenia, bipolar disorder, learning disability, attention deficit hyperactivity disorder, Alzheimer disease, autism, and epilepsy. In the recent years many animal experiments and clinical trials using α7-nAChR ligands were conducted. The results of these studies strongly indicate that agonists and positive allosteric modulators of α7-nAChR are promising therapeutic agents for diseases associated with cognitive deficits.

  15. Localization of brain-derived neurotrophic factor, neurotrophin-4, tropomyosin-related kinase b receptor, and p75 NTR receptor by high-resolution immunohistochemistry on the adult mouse neuromuscular junction.

    Science.gov (United States)

    Garcia, Neus; Tomàs, Marta; Santafe, Manel M; Lanuza, M Angel; Besalduch, Nuria; Tomàs, Josep

    2010-03-01

    Neurotrophins and their receptors, the trk receptor tyrosine kinases (trks) and p75(NTR), are differentially expressed among the cell types that make up synapses. It is important to determine the precise location of these molecules involved in neurotransmission. Here we use immunostaining and Western blotting to study the localization and expression of neurotrophin brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) and the receptors tropomyosin-related kinase b (trkB) and p75(NTR) at the adult neuromuscular junction. Our confocal immunofluorescence results on the whole mounts of the mouse Levator auris longus muscle and on semithin cross-sections showed that BDNF, NT-4, trkB, and p75(NTR) were localized on the three cells in the neuromuscular synapse (motor axons, post-synaptic muscle and Schwann cells).

  16. A nonlinear relationship between cerebral serotonin transporter and 5-HT(2A) receptor binding: an in vivo molecular imaging study in humans

    DEFF Research Database (Denmark)

    Erritzoe, David; Holst, Klaus; Frokjaer, Vibe G.

    2010-01-01

    Serotonergic neurotransmission is involved in the regulation of physiological functions such as mood, sleep, memory, and appetite. Within the serotonin transmitter system, both the postsynaptically located serotonin 2A (5-HT2A) receptor and the presynaptic serotonin transporter (SERT) are sensitive...... tomography. Within each individual, a regional intercorrelation for the various brain regions was seen with both markers, most notably for 5-HT2A receptor binding. An inverted U-shaped relationship between the 5-HT2A receptor and the SERT binding was identified. The observed regional intercorrelation...

  17. Role of astrocytic transport processes in glutamatergic and GABAergic neurotransmission

    DEFF Research Database (Denmark)

    Schousboe, A; Sarup, A; Bak, L K

    2004-01-01

    The fine tuning of both glutamatergic and GABAergic neurotransmission is to a large extent dependent upon optimal function of astrocytic transport processes. Thus, glutamate transport in astrocytes is mandatory to maintain extrasynaptic glutamate levels sufficiently low to prevent excitotoxic...... neuronal damage. In GABA synapses hyperactivity of astroglial GABA uptake may lead to diminished GABAergic inhibitory activity resulting in seizures. As a consequence of this the expression and functional activity of astrocytic glutamate and GABA transport is regulated in a number of ways...

  18. The TAM-family receptor Mer mediates production of HGF through the RhoA-dependent pathway in response to apoptotic cells.

    Science.gov (United States)

    Park, Hyun-Jung; Baen, Ji-Yeon; Lee, Ye-Ji; Choi, Youn-Hee; Kang, Jihee Lee

    2012-08-01

    The TAM receptor protein tyrosine kinases Tyro3, Axl, and Mer play important roles in macrophage function. We investigated the roles of the TAM receptors in mediating the induction of hepatocyte growth factor (HGF) during the interaction of macrophages with apoptotic cells. Mer-specific neutralizing antibody, small interfering RNA (siRNA), and a recombinant Mer protein (Mer/Fc) inhibited HGF mRNA and protein expression, as well as activation of RhoA, Akt, and specific mitogen-activated protein (MAP) kinases in response to apoptotic cells. Inhibition of Axl or Tyro3 with specific antibodies, siRNA, or Fc-fusion proteins did not prevent apoptotic cell-induced HGF mRNA and protein expression and did not inhibit activation of the postreceptor signaling molecules RhoA and certain MAP kinases, including extracellular signal-regulated protein kinase and c-Jun NH(2)-terminal kinase. However, Axl- and Tyro3-specific blockers did inhibit the activation of Akt and p38 MAP kinase in response to apoptotic cells. In addition, none of the TAM receptors mediated the effects of apoptotic cells on transforming growth factor-β or epidermal growth factor mRNA expression. However, they were involved in the induction of vascular endothelial growth factor mRNA expression. Our data provide evidence that when macrophages interact with apoptotic cells, only Mer of the TAM-family receptors is responsible for mediating transcriptional HGF production through a RhoA-dependent pathway.

  19. Drosophila lipophorin receptors mediate the uptake of neutral lipids in oocytes and imaginal disc cells by an endocytosis-independent mechanism.

    Directory of Open Access Journals (Sweden)

    Esmeralda Parra-Peralbo

    2011-02-01

    Full Text Available Lipids are constantly shuttled through the body to redistribute energy and metabolites between sites of absorption, storage, and catabolism in a complex homeostatic equilibrium. In Drosophila, lipids are transported through the hemolymph in the form of lipoprotein particles, known as lipophorins. The mechanisms by which cells interact with circulating lipophorins and acquire their lipidic cargo are poorly understood. We have found that lipophorin receptor 1 and 2 (lpr1 and lpr2, two partially redundant genes belonging to the Low Density Lipoprotein Receptor (LDLR family, are essential for the efficient uptake and accumulation of neutral lipids by oocytes and cells of the imaginal discs. Females lacking the lpr2 gene lay eggs with low lipid content and have reduced fertility, revealing a central role for lpr2 in mediating Drosophila vitellogenesis. lpr1 and lpr2 are transcribed into multiple isoforms. Interestingly, only a subset of these isoforms containing a particular LDLR type A module mediate neutral lipid uptake. Expression of these isoforms induces the extracellular stabilization of lipophorins. Furthermore, our data indicate that endocytosis of the lipophorin receptors is not required to mediate the uptake of neutral lipids. These findings suggest a model where lipophorin receptors promote the extracellular lipolysis of lipophorins. This model is reminiscent of the lipolytic processing of triglyceride-rich lipoproteins that occurs at the mammalian capillary endothelium, suggesting an ancient role for LDLR-like proteins in this process.

  20. Posttraumatic Propofol Neurotoxicity Is Mediated via the Pro-Brain-Derived Neurotrophic Factor-p75 Neurotrophin Receptor Pathway in Adult Mice.

    Science.gov (United States)

    Sebastiani, Anne; Granold, Matthias; Ditter, Anja; Sebastiani, Philipp; Gölz, Christina; Pöttker, Bruno; Luh, Clara; Schaible, Eva-Verena; Radyushkin, Konstantin; Timaru-Kast, Ralph; Werner, Christian; Schäfer, Michael K; Engelhard, Kristin; Moosmann, Bernd; Thal, Serge C

    2016-02-01

    The gamma-aminobutyric acid modulator propofol induces neuronal cell death in healthy immature brains by unbalancing neurotrophin homeostasis via p75 neurotrophin receptor signaling. In adulthood, p75 neurotrophin receptor becomes down-regulated and propofol loses its neurotoxic effect. However, acute brain lesions, such as traumatic brain injury, reactivate developmental-like programs and increase p75 neurotrophin receptor expression, probably to foster reparative processes, which in turn could render the brain sensitive to propofol-mediated neurotoxicity. This study investigates the influence of delayed single-bolus propofol applications at the peak of p75 neurotrophin receptor expression after experimental traumatic brain injury in adult mice. Randomized laboratory animal study. University research laboratory. Adult C57BL/6N and nerve growth factor receptor-deficient mice. Sedation by IV propofol bolus application delayed after controlled cortical impact injury. Propofol sedation at 24 hours after traumatic brain injury increased lesion volume, enhanced calpain-induced αII-spectrin cleavage, and increased cell death in perilesional tissue. Thirty-day postinjury motor function determined by CatWalk (Noldus Information Technology, Wageningen, The Netherlands) gait analysis was significantly impaired in propofol-sedated animals. Propofol enhanced pro-brain-derived neurotrophic factor/brain-derived neurotrophic factor ratio, which aggravates p75 neurotrophin receptor-mediated cell death. Propofol toxicity was abolished both by pharmacologic inhibition of the cell death domain of the p75 neurotrophin receptor (TAT-Pep5) and in mice lacking the extracellular neurotrophin binding site of p75 neurotrophin receptor. This study provides first evidence that propofol sedation after acute brain lesions can have a deleterious impact and implicates a role for the pro-brain-derived neurotrophic factor-p75 neurotrophin receptor pathway. This observation is important as sedation

  1. Role of Ca+2 and other second messengers in excitatory amino acid receptor mediated neurodegeneration: clinical perspectives

    DEFF Research Database (Denmark)

    Schousboe, A; Belhage, B; Frandsen, A

    1997-01-01

    Neurodegeneration associated with neurological disorders such as epilepsy, Huntington's Chorea, Alzheimer's disease, and olivoponto cerebellar atrophy or with energy failure such as ischemia, hypoxia, and hypoglycemia proceeds subsequent to overexposure of neurons to excitatory amino acids of which...... glutamate and aspartate may be quantitatively the most important. The toxic action of glutamate and aspartate is mediated through activation of glutamate receptors of the N-methyl-D-aspartate (NMDA) and non-NMDA subtypes. Antagonists for these receptors can act as neuroprotectants both in in vitro model...

  2. Discovery of a novel site of opioid action at the innate immune pattern-recognition receptor TLR4 and its role in addiction.

    Science.gov (United States)

    Jacobsen, Jonathan Henry W; Watkins, Linda R; Hutchinson, Mark R

    2014-01-01

    Opioids have historically, and continue to be, an integral component of pain management. However, despite pharmacokinetic and dynamic optimization over the past 100 years, opioids continue to produce many undesirable side effects such as tolerance, reward, and dependence. As such, opioids are liable for addiction. Traditionally, opioid addiction was viewed as a solely neuronal process, and while substantial headway has been made into understanding the molecular and cellular mechanisms mediating this process, research has however, been relatively ambivalent to how the rest of the central nervous system (CNS) responds to opioids. Evidence over the past 20 years has clearly demonstrated the importance of the immunocompetent cells of the CNS (glia) in many aspects of opioid pharmacology. Particular focus has been placed on microglia and astrocytes, who in response to opioids, become activated and release inflammatory mediators. Importantly, the mechanism underlying immune activation is beginning to be elucidated. Evidence suggests an innate immune pattern-recognition receptor (toll-like receptor 4) as an integral component underlying opioid-induced glial activation. The subsequent proinflammatory response may be viewed akin to neurotransmission creating a process termed central immune signaling. Translationally, we are beginning to appreciate the importance of central immune signaling as it contributes to many behavioral actions of addiction including reward, withdrawal, and craving. As such, the aim of this chapter is to review and integrate the neuronal and central immune signaling perspective of addiction. © 2014 Elsevier Inc. All rights reserved.

  3. EANM procedure guidelines for brain neurotransmission SPECT/PET using dopamine D2 receptor ligands, version 2

    DEFF Research Database (Denmark)

    Van Laere, Koen; Varrone, Andrea; Booij, Jan

    2010-01-01

    receptor SPECT or PET studies, and to achieve a high quality standard of dopamine D2 receptor imaging, which will increase the impact of this technique in neurological practice.The present document is an update of the first guidelines for SPECT using D2 receptor ligands labelled with (123)I [1......The guidelines summarize the current views of the European Association of Nuclear Medicine Neuroimaging Committee (ENC). The aims of the guidelines are to assist nuclear medicine practitioners in making recommendations, performing, interpreting and reporting the results of clinical dopamine D2......] and was guided by the views of the Society of Nuclear Medicine Brain Imaging Council [2], and the individual experience of experts in European countries. The guidelines intend to present information specifically adapted to European practice. The information provided should be taken in the context of local...

  4. [A study on toxic effects of sodium salicylate on rat cochlear spiral ganglion neurons: dopamine receptors mediate expressions of NMDA and GABAA receptors].

    Science.gov (United States)

    Wei, Ting-Jia; Chen, Hui-Ying; Huang, Xi; Weng, Jing-Jin; Qin, Jiang-Yuan; Su, Ji-Ping

    2017-06-25

    The aim of the present study was to observe whether dopamine receptor (DR) was involved in the effects of sodium salicylate (SS) on the expressions of N-methyl-D-aspartic acid (NMDA) and γ-aminobutyric acid (GABA) receptors in rat cochlear spiral ganglion neurons (SGNs). Forty-eight hours after primary culture of rat SGNs, immunofluorescence technique was applied to detect expressions of DR1 and DR2, the two subtypes of dopamine receptors. Western blot was performed to assess NMDA receptor NR1 subunit and GABA A receptor subunit α2 (GABRα2) protein expressions in the SGNs after the treatments of SS alone or in combination with DR antagonists. The results demonstrated that: (1) The DR1 and DR2 were expressed in the bodies and axons of the SGN; (2) After the treatment with SS, the surface protein expressions of GABRα2 and NR1 were decreased by 44.69% and 21.57%, respectively, while the total protein expressions showed no significant changes; (3) Neither SS + SCH23390 (DR1 antagonist) group nor SS + Eticlopride (DR2 antagonist) group showed significant differences in GABRα2 and NR1 surface protein expressions compared with the control group. These results suggest that SS regulates the surface GABA A and NMDA receptors trafficking on SGN, and the mechanism may involve DR mediation.

  5. Adaptor Protein Complex-2 (AP-2) and Epsin-1 Mediate Protease-activated Receptor-1 Internalization via Phosphorylation- and Ubiquitination-dependent Sorting Signals*

    Science.gov (United States)

    Chen, Buxin; Dores, Michael R.; Grimsey, Neil; Canto, Isabel; Barker, Breann L.; Trejo, JoAnn

    2011-01-01

    Signaling by protease-activated receptor-1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, is regulated by desensitization and internalization. PAR1 desensitization is mediated by β-arrestins, like most classic GPCRs. In contrast, internalization of PAR1 occurs through a clathrin- and dynamin-dependent pathway independent of β-arrestins. PAR1 displays two modes of internalization. Constitutive internalization of unactivated PAR1 is mediated by the clathrin adaptor protein complex-2 (AP-2), where the μ2-adaptin subunit binds directly to a tyrosine-based motif localized within the receptor C-tail domain. However, AP-2 depletion only partially inhibits agonist-induced internalization of PAR1, suggesting a function for other clathrin adaptors in this process. Here, we now report that AP-2 and epsin-1 are both critical mediators of agonist-stimulated PAR1 internalization. We show that ubiquitination of PAR1 and the ubiquitin-interacting motifs of epsin-1 are required for epsin-1-dependent internalization of activated PAR1. In addition, activation of PAR1 promotes epsin-1 de-ubiquitination, which may increase its endocytic adaptor activity to facilitate receptor internalization. AP-2 also regulates activated PAR1 internalization via recognition of distal C-tail phosphorylation sites rather than the canonical tyrosine-based motif. Thus, AP-2 and epsin-1 are both required to promote efficient internalization of activated PAR1 and recognize discrete receptor sorting signals. This study defines a new pathway for internalization of mammalian GPCRs. PMID:21965661

  6. Angiotensin type 2 receptors

    DEFF Research Database (Denmark)

    Sumners, Colin; de Kloet, Annette D; Krause, Eric G

    2015-01-01

    In most situations, the angiotensin AT2-receptor (AT2R) mediates physiological actions opposing those mediated by the AT1-receptor (AT1R), including a vasorelaxant effect. Nevertheless, experimental evidence vastly supports that systemic application of AT2R-agonists is blood pressure neutral...

  7. Quantitative autoradiography of ligands for dopamine receptors and transporters in brain of Göttingen minipig

    DEFF Research Database (Denmark)

    Minuzzi, Luciano; Olsen, Aage Kristian; Bender, Dirk

    2006-01-01

    The pig has been used as animal model for positron emission tomography (PET) studies of dopamine (DA) receptors and pharmacological perturbations of DA neurotransmission. However, the binding properties of DA receptors and transporters in pig brain have not been characterized in vitro. Therefore...... in young and old pigs, and were close to those reported for rat and human brain. Furthermore, gradients in the concentrations of D1 and D2/3 sites in striatum measured in vitro agreed with earlier findings in PET studies. However, the dopamine transporter (DAT) ligand [3H]GBR12935 did not bind in pig brain...

  8. Receptor-mediated photo-cytotoxicity: synthesis of a photoactivatable psoralen derivative conjugated to insulin.

    Science.gov (United States)

    Gasparro, F P; Knobler, R M; Yemul, S S; Bisaccia, E; Edelson, R L

    1986-12-15

    4'-Aminomethyl-4,5',8-trimethylpsoralen has been chemically conjugated to insulin using a carbodiimide derivative. The psoralen moiety retains its photochemical reactivity as evidenced by its ability to crosslink DNA after exposure to long wavelength ultraviolet light (UVA, 320-400 nm). This chimeric molecule has been used to selectively kill a population of lymphocytes whose expression of insulin receptors has been stimulated with phytohemagglutinin. Insulin carries the psoralen into the cell via receptor-mediated endocytosis, where it is subsequently activated by exposure to UVA light. The UVA induced activity of AMT-insulin can be blocked by the presence of native insulin. The viability of unstimulated lymphocytes was not affected by AMT-insulin and UVA light. The hybrid insulin-psoralen molecule may be a prototype for a family of phototoxic drugs which can be selectively delivered to subsets of lymphocytes.

  9. Steroid influences on GABAergic neurotransmission: A behavioral and biochemical approach

    International Nuclear Information System (INIS)

    McCarthy, M.M.

    1989-01-01

    Steroid influences on GABAergic neurotransmission are varied and complex. However, there has been little investigation into the behavioral relevance of steroid effects on GABA. GABA had been implicated in the control of lordosis, a steroid dependent posture exhibited by sexually receptive female rats, but with conflicting results. This data demonstrated that GABA plays a dual role in the regulation of lordosis; stimulation of GABAergic transmission in the medial hypothalamus enhances lordosis whereas stimulation of GABA in the preoptic area inhibits lordosis. In separate experiments it was determined that progesterone enhances binding of the GABA A agonist, muscimol, in an in vitro exchange assay utilizing synaptic membranes prepared from the hypothalamus of ovariectomized rats. Scatchard analysis revealed a difference in affinity of the GABA A receptor between ovariectomized, receptive and post receptive females. In the preoptic area there was a significant decrease in the binding of 3 H-muscimol in receptive females versus post-receptive and ovariectomized rats. In other behavioral experiments, the influence of estrogen and progesterone on GABA-induced analgesia was assessed. Intrathecal infusion of a low dose of muscimol at the lumbar level of the spinal cord did not alter nociceptive thresholds in ovariectomized rats. However, when intact females were administered the same dose of muscimol, they exhibited differential responses over the estrous cycle. Females in estrus were analgesic after muscimol, whereas diestrus females did not differ from ovariectomized controls. Ovariectomized rats injected s.c. with progesterone (2mg) exhibited a pronounced analgesia after intrathecal muscimol beginning 15 minutes after steroid treatment, whereas similar treatment with estrogen (10ug) was without effect

  10. Exploring in vivo cholesterol-mediated interactions between activated EGF receptors in plasma membrane with single-molecule optical tracking

    International Nuclear Information System (INIS)

    Lin, Chien Y.; Huang, Jung Y.; Lo, Leu-Wei

    2016-01-01

    The first step in many cellular signaling processes occurs at various types of receptors in the plasma membrane. Membrane cholesterol can alter these signaling pathways of living cells. However, the process in which the interaction of activated receptors is modulated by cholesterol remains unclear. In this study, we measured single-molecule optical trajectories of epidermal growth factor receptors moving in the plasma membranes of two cancerous cell lines and one normal endothelial cell line. A stochastic model was developed and applied to identify critical information from single-molecule trajectories. We discovered that unliganded epidermal growth factor receptors may reside nearby cholesterol-riched regions of the plasma membrane and can move into these lipid domains when subjected to ligand binding. The amount of membrane cholesterol considerably affects the stability of correlated motion of activated epidermal growth factor receptors. Our results provide single-molecule evidence of membrane cholesterol in regulating signaling receptors. Because the three cell lines used for this study are quite diverse, our results may be useful to shed light on the mechanism of cholesterol-mediated interaction between activated receptors in live cells

  11. Novel positive regulatory role for the SPL6 transcription factor in the N TIR-NB-LRR receptor-mediated plant innate immunity.

    Directory of Open Access Journals (Sweden)

    Meenu S Padmanabhan

    2013-03-01

    Full Text Available Following the recognition of pathogen-encoded effectors, plant TIR-NB-LRR immune receptors induce defense signaling by a largely unknown mechanism. We identify a novel and conserved role for the SQUAMOSA PROMOTER BINDING PROTEIN (SBP-domain transcription factor SPL6 in enabling the activation of the defense transcriptome following its association with a nuclear-localized immune receptor. During an active immune response, the Nicotiana TIR-NB-LRR N immune receptor associates with NbSPL6 within distinct nuclear compartments. NbSPL6 is essential for the N-mediated resistance to Tobacco mosaic virus. Similarly, the presumed Arabidopsis ortholog AtSPL6 is required for the resistance mediated by the TIR-NB-LRR RPS4 against Pseudomonas syringae carrying the avrRps4 effector. Transcriptome analysis indicates that AtSPL6 positively regulates a subset of defense genes. A pathogen-activated nuclear-localized TIR-NB-LRR like N can therefore regulate defense genes through SPL6 in a mechanism analogous to the induction of MHC genes by mammalian immune receptors like CIITA and NLRC5.

  12. Role of receptor-mediated endocytosis in the antiangiogenic effects of human T lymphoblastic cell-derived microparticles.

    Science.gov (United States)

    Yang, Chun; Xiong, Wei; Qiu, Qian; Shao, Zhuo; Shao, Zuo; Hamel, David; Tahiri, Houda; Leclair, Grégoire; Lachapelle, Pierre; Chemtob, Sylvain; Hardy, Pierre

    2012-04-15

    Microparticles possess therapeutic potential regarding angiogenesis. We have demonstrated the contribution of apoptotic human CEM T lymphocyte-derived microparticles (LMPs) as inhibitors of angiogenic responses in animal models of inflammation and tumor growth. In the present study, we characterized the antivascular endothelial growth factor (VEGF) effects of LMPs on pathological angiogenesis in an animal model of oxygen-induced retinopathy and explored the role of receptor-mediated endocytosis in the effects of LMPs on human retinal endothelial cells (HRECs). LMPs dramatically inhibited cell growth of HRECs, suppressed VEGF-induced cell migration in vitro experiments, and attenuated VEGF-induced retinal vascular leakage in vivo. Intravitreal injections of fluorescently labeled LMPs revealed accumulation of LMPs in retinal tissue, with more than 60% reductions of the vascular density in retinas of rats with oxygen-induced neovascularization. LMP uptake experiments demonstrated that the interaction between LMPs and HRECs is dependent on temperature. In addition, endocytosis is partially dependent on extracellular calcium. RNAi-mediated knockdown of low-density lipoprotein receptor (LDLR) reduced the uptake of LMPs and attenuated the inhibitory effects of LMPs on VEGF-A protein expression and HRECs cell growth. Intravitreal injection of lentivirus-mediated RNA interference reduced LDLR protein expression in retina by 53% and significantly blocked the antiangiogenic effects of LMPs on pathological vascularization. In summary, the potent antiangiogenic LMPs lead to a significant reduction of pathological retinal angiogenesis through modulation of VEGF signaling, whereas LDLR-mediated endocytosis plays a partial, but pivotal, role in the uptake of LMPs in HRECs.

  13. Caenorhabditis elegans reveals a FxNPxY-independent low-density lipoprotein receptor internalization mechanism mediated by epsin1

    Science.gov (United States)

    Kang, Yuan-Lin; Yochem, John; Bell, Leslie; Sorensen, Erika B.; Chen, Lihsia; Conner, Sean D.

    2013-01-01

    Low-density lipoprotein receptor (LDLR) internalization clears cholesterol-laden LDL particles from circulation in humans. Defects in clathrin-dependent LDLR endocytosis promote elevated serum cholesterol levels and can lead to atherosclerosis. However, our understanding of the mechanisms that control LDLR uptake remains incomplete. To identify factors critical to LDLR uptake, we pursued a genome-wide RNA interference screen using Caenorhabditis elegans LRP-1/megalin as a model for LDLR transport. In doing so, we discovered an unanticipated requirement for the clathrin-binding endocytic adaptor epsin1 in LDLR endocytosis. Epsin1 depletion reduced LDLR internalization rates in mammalian cells, similar to the reduction observed following clathrin depletion. Genetic and biochemical analyses of epsin in C. elegans and mammalian cells uncovered a requirement for the ubiquitin-interaction motif (UIM) as critical for receptor transport. As the epsin UIM promotes the internalization of some ubiquitinated receptors, we predicted LDLR ubiquitination as necessary for endocytosis. However, engineered ubiquitination-impaired LDLR mutants showed modest internalization defects that were further enhanced with epsin1 depletion, demonstrating epsin1-mediated LDLR endocytosis is independent of receptor ubiquitination. Finally, we provide evidence that epsin1-mediated LDLR uptake occurs independently of either of the two documented internalization motifs (FxNPxY or HIC) encoded within the LDLR cytoplasmic tail, indicating an additional internalization mechanism for LDLR. PMID:23242996

  14. Decrement of GABAA receptor-mediated inhibitory postsynaptic currents in dentate granule cells in epileptic hippocampus.

    Science.gov (United States)

    Isokawa, M

    1996-05-01

    1. Inhibitory postsynaptic currents (IPSCs) were studied in hippocampal dentate granule cells (DGCs) in the pilocarpine model and human temporal lobe epilepsy, with the use of the whole cell patch-clamp recording technique in slice preparations. 2. In the pilocarpine model, hippocampal slices were prepared from rats that were allowed to experience spontaneous seizures for 2 mo. Human hippocampal specimens were obtained from epileptic patients who underwent surgical treatment for medically intractable seizures. 3. IPSCs were generated by single perforant path stimulation and recorded at a membrane potential (Vm) of 0 mV near the reversal potential of glutamate excitatory postsynaptic currents in the voltage-clamp recording. IPSCs were pharmacologically identified as gamma-aminobutyric acid-A (GABAA) IPSCs by 10 microM bicuculline methiodide. 4. During low-frequency stimulation, IPSCs were not different in amplitude among non-seizure-experienced rat hippocampi, human nonsclerotic hippocampi, seizure-experienced rat hippocampi, and human sclerotic hippocampi. In the last two groups of DGCs, current-clamp recordings indicated the presence of prolonged excitatory postsynaptic potentials (EPSPs) mediated by the N-methyl-D-aspartate (NMDA) receptor. 5. High-frequency stimulation, administered at Vm = -30 mV to activate NMDA currents, reduced GABAA IPSC amplitude specifically in seizure-experienced rat hippocampi (t = 2.5, P < 0.03) and human sclerotic hippocampi (t = 7.7, P < 0.01). This reduction was blocked by an NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV) (50 microM). The time for GABAA IPSCs to recover to their original amplitude was also shortened by the application of APV. 6. I conclude that, when intensively activated, NMDA receptor-mediated excitatory transmission may interact with GABAergic synaptic inhibition in DGCs in seizure-experienced hippocampus to transiently reduce GABA(A) receptor-channel function. Such interactions may contribute to

  15. Mac-1 (CD11b/CD18) is essential for Fc receptor-mediated neutrophil cytotoxicity and immunologic synapse formation.

    Science.gov (United States)

    van Spriel, A B; Leusen, J H; van Egmond, M; Dijkman, H B; Assmann, K J; Mayadas, T N; van de Winkel, J G

    2001-04-15

    Receptors for human immunoglobulin (Ig)G and IgA initiate potent cytolysis of antibody (Ab)-coated targets by polymorphonuclear leukocytes (PMNs). Mac-1 (complement receptor type 3, CD11b/CD18) has previously been implicated in receptor cooperation with Fc receptors (FcRs). The role of Mac-1 in FcR-mediated lysis of tumor cells was characterized by studying normal human PMNs, Mac-1-deficient mouse PMNs, and mouse PMNs transgenic for human FcR. All PMNs efficiently phagocytosed Ab-coated particles. However, antibody-dependent cellular cytotoxicity (ADCC) was abrogated in Mac-1(-/-) PMNs and in human PMNs blocked with anti-Mac-1 monoclonal Ab (mAb). Mac-1(-/-) PMNs were unable to spread on Ab-opsonized target cells and other Ab-coated surfaces. Confocal laser scanning and electron microscopy revealed a striking difference in immunologic synapse formation between Mac-1(-/-) and wild-type PMNs. Also, respiratory burst activity could be measured outside membrane-enclosed compartments by using Mac-1(-/-) PMNs bound to Ab-coated tumor cells, in contrast to wild-type PMNs. In summary, these data document an absolute requirement of Mac-1 for FcR-mediated PMN cytotoxicity toward tumor targets. Mac-1(-/-) PMNs exhibit defective spreading on Ab-coated targets, impaired formation of immunologic synapses, and absent tumor cytolysis.

  16. Ketamine attenuates the glutamatergic neurotransmission in the ventral posteromedial nucleus slices of rats.

    Science.gov (United States)

    Fu, Bao; Liu, Chengxi; Zhang, Yajun; Fu, Xiaoyun; Zhang, Lin; Yu, Tian

    2017-08-23

    Ketamine is a frequently used intravenous anesthetic, which can reversibly induce loss of consciousness (LOC). Previous studies have demonstrated that thalamocortical system is critical for information transmission and integration in the brain. The ventral posteromedial nucleus (VPM) is a critical component of thalamocortical system. Glutamate is an important excitatory neurotransmitter in the brain and may be involved in ketamine-induced LOC. The study used whole-cell patch-clamp to observe the effect of ketamine (30 μM-1000 μM) on glutamatergic neurotransmission in VPM slices. Ketamine significantly decreased the amplitude of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs), but only higher concentration of ketamine (300 μM and 1000 μM) suppressed the frequency of sEPSCs. Ketamine (100 μM-1000 μM) also decreased the amplitude of glutamatergic miniature excitatory postsynaptic currents (mEPSCs), without altering the frequency. In VPM neurons, ketamine attenuates the glutamatergic neurotransmission mainly through postsynaptic mechanism and action potential may be involved in the process.

  17. Modulation of GABA receptors expressed in Xenopus oocytes by 13-L-hydroxylinoleic acid and food additives.

    Science.gov (United States)

    Aoshima, H; Tenpaku, Y

    1997-12-01

    To study the effects of 13-L-hydroxylinoleic acid (LOH) and food additives on gamma-aminobutyric acid (GABA) receptors, ionotropic GABA receptors were expressed in Xenopus oocytes by injecting mRNAs prepared from rat whole brain. LOH, which was prepared by reduction of 13-L-hydroperoxylinoleic acid (LOOH), inhibited the response of GABA receptors in the presence of high concentrations of GABA. LOH also inhibited nicotinic acetylcholine, glycine, and kainate receptors, while it had little effect on NMDA receptors expressed in Xenopus oocytes. However, LOH potentiated the response of GABA receptors as well as LOOH in the presence of low concentrations of GABA, possibly increasing the affinity of GABA for the receptors, while linoleic acid did not. Since some modification of the compounds seemed to change their effects on GABA receptors, the responses of GABA receptors elicited by 10 microM GABA were measured in the presence of compounds with various kinds of functional groups or the structural isomers of pentanol. Potentiation of GABA receptors depended strongly on the species of functional groups and also depended on the structure of the isomers. Then effects of various kinds of food additives on GABA receptors were also examined; perfumes such as alcohols or esters potentiated the responses strongly, while hexylamine, nicotinamide, or caffeine inhibited the responses, mainly in a competitive manner, and vanillin inhibited the responses noncompetitively. These results suggest the possibility that production of LOOH and LOH, or intake of much of some food additives, modulates the neural transmission in the brain, especially through ionotropic GABA receptors and changes the frame of the human mind, as alcohol or tobacco does.

  18. Risperidone increases the cortical silent period in drug-naive patients with first-episode schizophrenia: A transcranial magnetic stimulation study.

    Science.gov (United States)

    Ustohal, Libor; Mayerova, Michaela; Hublova, Veronika; Prikrylova Kucerova, Hana; Ceskova, Eva; Kasparek, Tomas

    2017-04-01

    Schizophrenia is accompanied by impaired cortical inhibition, as measured by several markers including the cortical silent period (CSP). It is thought that CSP measures gamma-aminobutyric acid receptors B (GABA B ) mediated inhibitory activity. But the mutual roles of schizophrenia as a disease and the drugs used for the treatment of psychosis on GABA mediated neurotransmission are not clear. We recruited 13 drug-naive patients with first-episode schizophrenia. We used transcranial magnetic stimulation to assess CSP prior to initiating risperidone monotherapy and again four weeks later. At the same time, we rated the severity of psychopathology using the Positive and Negative Syndrome Scale (PANSS). We obtained data from 12 patients who showed a significant increase in CSP, from 134.20±41.81 ms to 162.95±61.98 ms ( p=0.041; Cohen's d=0.544). After the treatment, the PANSS total score was significantly lower, as were the individual subscores ( pschizophrenia demonstrated an association between risperidone monotherapy and an increase in GABA B mediated inhibitory neurotransmission.

  19. Comparative effects of chlorpyrifos in wild type and cannabinoid Cb1 receptor knockout mice

    Energy Technology Data Exchange (ETDEWEB)

    Baireddy, Praveena; Liu, Jing; Hinsdale, Myron; Pope, Carey, E-mail: carey.pope@okstate.edu

    2011-11-15

    Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55.212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (-/-) mice. Mice of both genotypes (n = 5-6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82-95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 {mu}M) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20-23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner. -- Highlights: Black-Right-Pointing-Pointer C57Bl/6 mice showed dose-related cholinergic toxicity following subcutaneous chlorpyrifos exposure. Black-Right-Pointing-Pointer Wild type and

  20. Comparative effects of chlorpyrifos in wild type and cannabinoid Cb1 receptor knockout mice

    International Nuclear Information System (INIS)

    Baireddy, Praveena; Liu, Jing; Hinsdale, Myron; Pope, Carey

    2011-01-01

    Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55.212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (−/−) mice. Mice of both genotypes (n = 5–6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82–95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 μM) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20–23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner. -- Highlights: ► C57Bl/6 mice showed dose-related cholinergic toxicity following subcutaneous chlorpyrifos exposure. ► Wild type and cannabinoid CB1 receptor knockout littermates