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Sample records for receptor ionotropic kainate

  1. 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...

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

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    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,...

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

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    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 ...

  4. 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

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

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    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. Stereostructure-activity studies on agonists at the AMPA and kainate subtypes of ionotropic glutamate receptors

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    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...

  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. Functional Validation of Heteromeric Kainate Receptor Models.

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    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.

  9. Ionotropic crustacean olfactory receptors.

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    Elizabeth A Corey

    Full Text Available The nature of the olfactory receptor in crustaceans, a major group of arthropods, has remained elusive. We report that spiny lobsters, Panulirus argus, express ionotropic receptors (IRs, the insect chemosensory variants of ionotropic glutamate receptors. Unlike insects IRs, which are expressed in a specific subset of olfactory cells, two lobster IR subunits are expressed in most, if not all, lobster olfactory receptor neurons (ORNs, as confirmed by antibody labeling and in situ hybridization. Ligand-specific ORN responses visualized by calcium imaging are consistent with a restricted expression pattern found for other potential subunits, suggesting that cell-specific expression of uncommon IR subunits determines the ligand sensitivity of individual cells. IRs are the only type of olfactory receptor that we have detected in spiny lobster olfactory tissue, suggesting that they likely mediate olfactory signaling. Given long-standing evidence for G protein-mediated signaling in activation of lobster ORNs, this finding raises the interesting specter that IRs act in concert with second messenger-mediated signaling.

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

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    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.

  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. 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.)

  13. 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.)

  14. 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...

  15. Presynaptic Ionotropic Receptors Controlling and Modulating the Rules for Spike Timing-Dependent Plasticity

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    Matthijs B. Verhoog

    2011-01-01

    Full Text Available Throughout life, activity-dependent changes in neuronal connection strength enable the brain to refine neural circuits and learn based on experience. In line with predictions made by Hebb, synapse strength can be modified depending on the millisecond timing of action potential firing (STDP. The sign of synaptic plasticity depends on the spike order of presynaptic and postsynaptic neurons. Ionotropic neurotransmitter receptors, such as NMDA receptors and nicotinic acetylcholine receptors, are intimately involved in setting the rules for synaptic strengthening and weakening. In addition, timing rules for STDP within synapses are not fixed. They can be altered by activation of ionotropic receptors located at, or close to, synapses. Here, we will highlight studies that uncovered how network actions control and modulate timing rules for STDP by activating presynaptic ionotropic receptors. Furthermore, we will discuss how interaction between different types of ionotropic receptors may create “timing” windows during which particular timing rules lead to synaptic changes.

  16. 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

  17. 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.

  18. 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...

  19. 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.

  20. 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

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

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    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...

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

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    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...

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

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    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.

  5. 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.

    Science.gov (United States)

    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.

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

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    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

  7. Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses

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    E. Popova

    2014-01-01

    Full Text Available In the vertebrate retina, visual signals are segregated into parallel ON and OFF pathways, which provide information for light increments and decrements. The segregation is first evident at the level of the ON and OFF bipolar cells in distal retina. The activity of large populations of ON and OFF bipolar cells is reflected in the b- and d-waves of the diffuse electroretinogram (ERG. The role of gamma-aminobutyric acid (GABA, acting through ionotropic GABA receptors in shaping the ON and OFF responses in distal retina, is a matter of debate. This review summarized current knowledge about the types of the GABAergic neurons and ionotropic GABA receptors in the retina as well as the effects of GABA and specific GABAA and GABAC receptor antagonists on the activity of the ON and OFF bipolar cells in both nonmammalian and mammalian retina. Special emphasis is put on the effects on b- and d-waves of the ERG as a useful tool for assessment of the overall function of distal retinal ON and OFF channels. The role of GABAergic system in establishing the ON-OFF asymmetry concerning the time course and absolute and relative sensitivity of the ERG responses under different conditions of light adaptation in amphibian retina is also discussed.

  8. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

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

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    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.

  15. 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.

  16. 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.

  17. Thermodynamics and structural analysis of positive allosteric modulation of the ionotropic glutamate receptor GluA2

    DEFF Research Database (Denmark)

    Krintel, Christian; Frydenvang, Karla; Olsen, Lars

    2012-01-01

    Positive allosteric modulators of the ionotropic glutamate receptor-2 (GluA2) are promising compounds for the treatment of cognitive disorders, e.g. Alzheimer's disease. These modulators bind within the dimer interface of the ligand-binding domain and stabilize the agonist-bound conformation slow...

  18. Synthesis of new isoxazoline-based acidic amino acids and investigation of their affinity and selectivity profile at ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Pinto, Andrea; Conti, Paola; Grazioso, Giovanni

    2011-01-01

    The synthesis of four new isoxazoline-based amino acids being analogues of previously described glutamate receptor ligands is reported and their affinity for ionotropic glutamate receptors is analyzed in comparison with that of selected model compounds. Molecular modelling investigations have been...

  19. Synthesis and pharmacological characterization of the selective GluK1 radioligand (S)-2-amino-3-(6-[3H]-2,4-dioxo-3,4-dihydrothieno[3,2-d]pyrimidin-1(2H)-yl)propanoic acid ([3H]-NF608)

    Czech Academy of Sciences Publication Activity Database

    Alcaide, A.; Marconi, L.; Marek, Aleš; Haym, I.; Nielsen, B.; Mollerud, S.; Jensen, M.; Conti, P.; Pickering, D. S.; Bunch, L.

    2016-01-01

    Roč. 7, č. 11 (2016), s. 2136-2144 ISSN 2040-2503 Institutional support: RVO:61388963 Keywords : 2,4-syn-functionalized (S)-glutamate analogs * ionotropic glutamate receptors * kainate receptor Subject RIV: CC - Organic Chemistry Impact factor: 2.608, year: 2016 http://pubs.rsc.org/en/content/articlehtml/2016/md/c6md00339g

  20. 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...

  1. 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

  2. Genome-based identification and analysis of ionotropic receptors in Spodoptera litura

    Science.gov (United States)

    Zhu, Jia-Ying; Xu, Zhi-Wen; Zhang, Xin-Min; Liu, Nai-Yong

    2018-06-01

    The ability to sense and recognize various classes of compounds is of particular importance for survival and reproduction of insects. Ionotropic receptor (IR), a sub-family of the ionotropic glutamate receptor family, has been identified as one of crucial chemoreceptor super-families, which mediates the sensing of odors and/or tastants, and serves as non-chemosensory functions. Yet, little is known about IR characteristics, evolution, and functions in Lepidoptera. Here, we identify the IR gene repertoire from a destructive polyphagous pest, Spodoptera litura. The exhaustive analyses with genome and transcriptome data lead to the identification of 45 IR genes, comprising 17 antennal IRs (A-IRs), 8 Lepidoptera-specific IRs (LS-IRs), and 20 divergent IRs (D-IRs). Phylogenetic analysis reveals that S. litura A-IRs generally retain a strict single copy within each orthologous group, and two lineage expansions are observed in the D-IR sub-family including IR100d-h and 100i-o, likely attributed to gene duplications. Results of gene structure analysis classify the SlitIRs into four types: I (intronless), II (1-3 introns), III (5-9 introns), and IV (10-18 introns). Extensive expression profiles demonstrate that the majority of SlitIRs (28/43) are enriched in adult antennae, and some are detected in gustatory-associated tissues like proboscises and legs as well as non-chemosensory organs like abdomens and reproductive tissues of both sexes. These results indicate that SlitIRs have diverse functional roles in olfaction, taste, and reproduction. Together, our study has complemented the information on chemoreceptor genes in S. litura, and meanwhile allows for target experiments to identify potential IR candidates for the control of this pest.

  3. Ancient protostome origin of chemosensory ionotropic glutamate receptors and the evolution of insect taste and olfaction.

    Directory of Open Access Journals (Sweden)

    Vincent Croset

    2010-08-01

    Full Text Available Ionotropic glutamate receptors (iGluRs are a highly conserved family of ligand-gated ion channels present in animals, plants, and bacteria, which are best characterized for their roles in synaptic communication in vertebrate nervous systems. A variant subfamily of iGluRs, the Ionotropic Receptors (IRs, was recently identified as a new class of olfactory receptors in the fruit fly, Drosophila melanogaster, hinting at a broader function of this ion channel family in detection of environmental, as well as intercellular, chemical signals. Here, we investigate the origin and evolution of IRs by comprehensive evolutionary genomics and in situ expression analysis. In marked contrast to the insect-specific Odorant Receptor family, we show that IRs are expressed in olfactory organs across Protostomia--a major branch of the animal kingdom that encompasses arthropods, nematodes, and molluscs--indicating that they represent an ancestral protostome chemosensory receptor family. Two subfamilies of IRs are distinguished: conserved "antennal IRs," which likely define the first olfactory receptor family of insects, and species-specific "divergent IRs," which are expressed in peripheral and internal gustatory neurons, implicating this family in taste and food assessment. Comparative analysis of drosophilid IRs reveals the selective forces that have shaped the repertoires in flies with distinct chemosensory preferences. Examination of IR gene structure and genomic distribution suggests both non-allelic homologous recombination and retroposition contributed to the expansion of this multigene family. Together, these findings lay a foundation for functional analysis of these receptors in both neurobiological and evolutionary studies. Furthermore, this work identifies novel targets for manipulating chemosensory-driven behaviours of agricultural pests and disease vectors.

  4. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

    Science.gov (United States)

    Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

    2016-01-01

    Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

  5. 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.

  6. Ionotropic excitatory amino acid receptor ligands. Synthesis and pharmacology of a new amino acid AMPA antagonist

    DEFF Research Database (Denmark)

    Madsen, U; Sløk, F A; Stensbøl, T B

    2000-01-01

    We have previously described the potent and selective (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA), and the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4...... excitatory amino acid (EAA) receptors using receptor binding and electrophysiological techniques, and for activity at metabotropic EAA receptors using second messenger assays. Compounds 1 and 4 were essentially inactive. (RS)-2-Amino-3-[3-(2-carboxyethyl)-5-methyl-4-isoxazolyl]propionic acid (ACMP, 2......-isoxazolyl]propionic acid (AMOA). Using these AMPA receptor ligands as leads, a series of compounds have been developed as tools for further elucidation of the structural requirements for activation and blockade of AMPA receptors. The synthesized compounds have been tested for activity at ionotropic...

  7. Role of ionotropic GABA, glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

    Directory of Open Access Journals (Sweden)

    Goodchild Ann K

    2010-10-01

    Full Text Available Abstract Background Cardiac vagal preganglionic neurons (CVPN are responsible for the tonic, reflex and respiratory modulation of heart rate (HR. Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve. Results Microinjection of the GABAA antagonist picrotoxin into CVPN decreased HR but did not affect baroreflex bradycardia. The glycine antagonist strychnine did not alter HR or baroreflex bradycardia. Combined microinjection of the NMDA antagonist, MK801, and AMPA antagonist, CNQX, into CVPN evoked a small bradycardia and abolished baroreflex bradycardia. MK801 attenuated whereas CNQX abolished baroreceptor bradycardia. Control intravenous injections of the 5-HT1A agonist 8-OH-DPAT evoked a small bradycardia and potentiated baroreflex bradycardia. These effects were still observed following microinjection of picrotoxin but not strychnine into CVPN. Conclusions We conclude that activation of GABAA receptors set the level of HR whereas AMPA to a greater extent than NMDA receptors elicit baroreflex changes in HR. Furthermore, activation of 5-HT1A receptors evokes bradycardia and enhances baroreflex changes in HR due to interactions with glycinergic neurons involving strychnine receptors. This study provides reference for future studies investigating how diseases alter neurochemical inputs to CVPN.

  8. 4-Alkylated homoibotenic acid (HIBO) analogues: versatile pharmacological agents with diverse selectivity profiles towards metabotropic and ionotropic glutamate receptor subtypes

    DEFF Research Database (Denmark)

    Madsen, Ulf; Pickering, Darryl S; Nielsen, Birgitte

    2005-01-01

    4-Alkylated analogues of homoibotenic acid (HIBO) have previously shown high potency and selectivity at ionotropic and metabotropic glutamic acid receptor (iGluR and mGluR) subtypes. Compounds with different selectivity profiles are valuable pharmacological tools for neuropharmacological studies...

  9. 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...

  10. Short-term sleep deprivation impairs spatial working memory and modulates expression levels of ionotropic glutamate receptor subunits in hippocampus.

    Science.gov (United States)

    Xie, Meilan; Yan, Jie; He, Chao; Yang, Li; Tan, Gang; Li, Chao; Hu, Zhian; Wang, Jiali

    2015-06-01

    Hippocampus-dependent learning memory is sensitive to sleep deprivation (SD). Although the ionotropic glutamate receptors play a vital role in synaptic plasticity and learning and memory, however, whether the expression of these receptor subunits is modulated by sleep loss remains unclear. In the present study, western blotting was performed by probing with specific antibodies against the ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1, GluA2, GluA3, and against the N-methyl-d-aspartate (NMDA) glutamate receptor subunits GluN1, GluN2A, GluN2B. In hippocampus, down regulation of surface GluA1 and GluN2A surface expression were observed in both SD groups. However, surface expression level of GluA2, GluA3, GluN1 and GluN2B was significantly up-regulated in 8h-SD rats when compared to the 4h-SD rats. In parallel with the complex changes in AMPA and NMDA receptor subunit expressions, we found the 8h-SD impaired rat spatial working memory in 30-s-delay T-maze task, whereas no impairment of spatial learning was observed in 4h-SD rats. These results indicate that sleep loss alters the relative expression levels of the AMPA and NMDA receptors, thus affects the synaptic strength and capacity for plasticity and partially contributes to spatial memory impairment. Copyright © 2015. Published by Elsevier B.V.

  11. 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.

  12. The low binding affinity of D-serine at the ionotropic glutamate receptor GluD2 can be attributed to the hinge region

    DEFF Research Database (Denmark)

    Tapken, Daniel; Steffensen, Thomas Bielefeldt; Leth, Rasmus

    2017-01-01

    Ionotropic glutamate receptors (iGluRs) are responsible for most of the fast excitatory communication between neurons in our brain. The GluD2 receptor is a puzzling member of the iGluR family: It is involved in synaptic plasticity, plays a role in human diseases, e.g. ataxia, binds glycine and D...

  13. Genome-wide analysis of ionotropic receptors provides insight into their evolution in Heliconius butterflies.

    Science.gov (United States)

    van Schooten, Bas; Jiggins, Chris D; Briscoe, Adriana D; Papa, Riccardo

    2016-03-22

    In a world of chemical cues, smell and taste are essential senses for survival. Here we focused on Heliconius, a diverse group of butterflies that exhibit variation in pre- and post-zygotic isolation and chemically-mediated behaviors across their phylogeny. Our study examined the ionotropic receptors, a recently discovered class of receptors that are some of the most ancient chemical receptors. We found more ionotropic receptors in Heliconius (31) than in Bombyx mori (25) or in Danaus plexippus (27). Sixteen genes in Lepidoptera were not present in Diptera. Only IR7d4 was exclusively found in butterflies and two expansions of IR60a were exclusive to Heliconius. A genome-wide comparison between 11 Heliconius species revealed instances of pseudogenization, gene gain, and signatures of positive selection across the phylogeny. IR60a2b and IR60a2d are unique to the H. melpomene, H. cydno, and H. timareta clade, a group where chemosensing is likely involved in pre-zygotic isolation. IR60a2b also displayed copy number variations (CNVs) in distinct populations of H. melpomene and was the only gene significantly higher expressed in legs and mouthparts than in antennae, which suggests a gustatory function. dN/dS analysis suggests more frequent positive selection in some intronless IR genes and in particular in the sara/sapho and melpomene/cydno/timareta clades. IR60a1 was the only gene with an elevated dN/dS along a major phylogenetic branch associated with pupal mating. Only IR93a was differentially expressed between sexes. All together these data make Heliconius butterflies one of the very few insects outside Drosophila where IRs have been characterized in detail. Our work outlines a dynamic pattern of IR gene evolution throughout the Heliconius radiation which could be the result of selective pressure to find potential mates or host-plants.

  14. 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.

  15. 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.

  16. Ionotropic glutamate receptors (iGluRs of the delta family (GluD1 and GluD2 and synaptogenesis

    Directory of Open Access Journals (Sweden)

    Muhammad Zahid Khan

    2017-08-01

    Full Text Available Glutamate delta-1 (GluD1 and glutamate delta-2 (GluD2 form the delta family of ionotropic glutamate receptors (iGluRs and are distinct from other (iGluRs in that they do not exhibit typical agonist-induced ion channel currents. Recent studies have demonstrated a crucial role of the delta receptors in synapse formation by interacting with presynaptic proteins such as Neurexin1. This review presents current knowledge regarding the expression, structure and function of Glu delta receptors (GluD1, GluD2 in brain, focusing on synapse formation, function and dysfunction.

  17. Ionotropic and Metabotropic Proton-Sensing Receptors Involved in Airway Inflammation in Allergic Asthma

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    Haruka Aoki

    2014-01-01

    Full Text Available An acidic microenvironment has been shown to evoke a variety of airway responses, including cough, bronchoconstriction, airway hyperresponsiveness (AHR, infiltration of inflammatory cells in the lung, and stimulation of mucus hyperproduction. Except for the participation of transient receptor potential vanilloid-1 (TRPV1 and acid-sensing ion channels (ASICs in severe acidic pH (of less than 6.0-induced cough and bronchoconstriction through sensory neurons, the molecular mechanisms underlying extracellular acidic pH-induced actions in the airways have not been fully understood. Recent studies have revealed that ovarian cancer G protein-coupled receptor 1 (OGR1-family G protein-coupled receptors, which sense pH of more than 6.0, are expressed in structural cells, such as airway smooth muscle cells and epithelial cells, and in inflammatory and immune cells, such as eosinophils and dendritic cells. They function in a variety of airway responses related to the pathophysiology of inflammatory diseases, including allergic asthma. In the present review, we discuss the roles of ionotropic TRPV1 and ASICs and metabotropic OGR1-family G protein-coupled receptors in the airway inflammation and AHR in asthma and respiratory diseases.

  18. Ionotropic Receptors Identified within the Tentacle of the Freshwater Snail Biomphalaria glabrata, an Intermediate Host of Schistosoma mansoni.

    Directory of Open Access Journals (Sweden)

    Di Liang

    Full Text Available Biomphalaria glabrata (B. glabrata is an air-breathing aquatic mollusc found in freshwater habitats across the Western Hemisphere. It is most well-known for its recognized capacity to act as a major intermediate host for Schistosoma mansoni, the human blood fluke parasite. Ionotropic receptors (IRs, a variant family of the ionotropic glutamate receptors (iGluR, have an evolutionary ancient function in detecting odors to initiate chemosensory signaling. In this study, we applied an array of methods towards the goal of identifying IR-like family members in B. glabrata, ultimately revealing two types, the iGluR and IR. Sequence alignment showed that three ligand-binding residues are conserved in most Biomphalaria iGluR sequences, while the IRs did exhibit a variable pattern, lacking some or all known glutamate-interactingresidues, supporting their distinct classification from the iGluRs. We show that B. glabrata contains 7 putative IRs, some of which are expressed within its chemosensory organs. To further investigate a role for the more ancient IR25a type in chemoreception, we tested its spatial distribution pattern within the snail cephalic tentacle by in situ hybridization. The presence of IR25a within presumptive sensory neurons supports a role for this receptor in olfactory processing, contributing to our understanding of the molecular pathways that are involved in Biomphalaria olfactory processing.

  19. Molecular pharmacology of 4-substituted glutamic acid analogues at ionotropic and metabotropic excitatory amino acid receptors

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Nielsen, B; Stensbøl, T B

    1997-01-01

    (subtypes 1alpha and 2), respectively, whereas (S)-4-methyleneglutamic acid showed high but rather non-selective affinity for the (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA), kainic acid, NMDA and mGlu receptors (subtypes 1alpha and 2). Although none of the compounds were specific......The pharmacology of (2S,4R)-4-methylglutamic acid, (2S,4S)-4-methylglutamic acid and (S)- and (R)-4-methyleneglutamic acids (obtained in high chemical and enantiomeric purity from racemic 4-methyleneglutamic acid by chiral HPLC using a Crownpak CR(+) column), was examined in binding experiments...... using rat brain ionotropic glutamate receptors, and in functional assays using cloned metabotropic glutamate (mGlu) receptors. As a notable result of these studies, (2S,4R)-4-methylglutamic acid and (2S,4S)-4-methylglutamic acid were shown to be selective for kainic acid receptors and mGlu receptors...

  20. 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...

  1. 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.

  2. The SOL-2/Neto auxiliary protein modulates the function of AMPA-subtype ionotropic glutamate receptors.

    Science.gov (United States)

    Wang, Rui; Mellem, Jerry E; Jensen, Michael; Brockie, Penelope J; Walker, Craig S; Hoerndli, Frédéric J; Hauth, Linda; Madsen, David M; Maricq, Andres V

    2012-09-06

    The neurotransmitter glutamate mediates excitatory synaptic transmission by gating ionotropic glutamate receptors (iGluRs). AMPA receptors (AMPARs), a subtype of iGluR, are strongly implicated in synaptic plasticity, learning, and memory. We previously discovered two classes of AMPAR auxiliary proteins in C. elegans that modify receptor kinetics and thus change synaptic transmission. Here, we have identified another auxiliary protein, SOL-2, a CUB-domain protein that associates with both the related auxiliary subunit SOL-1 and with the GLR-1 AMPAR. In sol-2 mutants, behaviors dependent on glutamatergic transmission are disrupted, GLR-1-mediated currents are diminished, and GLR-1 desensitization and pharmacology are modified. Remarkably, a secreted variant of SOL-1 delivered in trans can rescue sol-1 mutants, and this rescue depends on in cis expression of SOL-2. Finally, we demonstrate that SOL-1 and SOL-2 have an ongoing role in the adult nervous system to control AMPAR-mediated currents. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Functional characterisation of homomeric ionotropic glutamate receptors GluR1-GluR6 in a fluorescence-based high throughput screening assay

    DEFF Research Database (Denmark)

    Strange, Mette; Bräuner-Osborne, Hans; Jensen, Anders A.

    2006-01-01

    We have constructed stable HEK293 cell lines expressing the rat ionotropic glutamate receptor subtypes GluR1(i), GluR2Q(i), GluR3(i), GluR4(i), GluR5Q and GluR6Q and characterised the pharmacological profiles of the six homomeric receptors in a fluorescence-based high throughput screening assay...... assay reported to date. We propose that high throughput screening of compound libraries at the six GluR-HEK293 cell lines could be helpful in the search for structurally and pharmacologically novel ligands acting at the receptors....

  4. Ionotropic Receptor-dependent moist and dry cells control hygrosensation in Drosophila.

    Science.gov (United States)

    Knecht, Zachary A; Silbering, Ana F; Cruz, Joyner; Yang, Ludi; Croset, Vincent; Benton, Richard; Garrity, Paul A

    2017-06-16

    Insects use hygrosensation (humidity sensing) to avoid desiccation and, in vectors such as mosquitoes, to locate vertebrate hosts. Sensory neurons activated by either dry or moist air ('dry cells' and 'moist cells') have been described in many insects, but their behavioral roles and the molecular basis of their hygrosensitivity remain unclear. We recently reported that Drosophila hygrosensation relies on three Ionotropic Receptors (IRs) required for dry cell function: IR25a, IR93a and IR40a (Knecht et al., 2016). Here, we discover Drosophila moist cells and show that they require IR25a and IR93a together with IR68a, a conserved, but orphan IR. Both IR68a- and IR40a-dependent pathways drive hygrosensory behavior: each is important for dry-seeking by hydrated flies and together they underlie moist-seeking by dehydrated flies. These studies reveal that humidity sensing in Drosophila , and likely other insects, involves the combined activity of two molecularly related but neuronally distinct hygrosensing systems.

  5. 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...

  6. Expression of ionotropic receptors in terrestrial hermit crab’s olfactory sensory neurons

    Directory of Open Access Journals (Sweden)

    Katrin Christine Groh-Lunow

    2015-02-01

    Full Text Available Coenobitidae are one out of at least five crustacean lineages which independently succeeded in the transition from water to land. This change in lifestyle required adaptation of the peripheral olfactory organs, the antennules, in order to sense chemical cues in the new terrestrial habitat. Hermit crab olfactory aesthetascs are arranged in a field on the distal segment of the antennular flagellum. Aesthetascs house approximately 300 dendrites with their cell bodies arranged in spindle-like complexes of ca. 150 cell bodies each. While the aesthetascs of aquatic crustaceans have been shown to be the place of odor uptake and previous studies identified ionotropic receptors (IRs as the putative chemosensory receptors expressed in decapod antennules, the expression of IRs besides the IR co-receptors IR25a and IR93a in olfactory sensory neurons (OSNs has not been documented yet. Our goal was to reveal the expression and distribution pattern of non-co-receptor IRs in OSNs of Coenobita clypeatus, a terrestrial hermit crab, with RNA in situ hybridization. We expanded our previously published RNAseq dataset, and revealed 22 novel IR candidates in the Coenobita antennules. We then used RNA probes directed against three different IRs to visualize their expression within the OSN cell body complexes. Furthermore we aimed to characterize ligand spectra of single aesthetascs by recording local field potentials and responses from individual dendrites. This also allowed comparison to functional data from insect OSNs expressing antennal IRs. We show that this orphan receptor subgroup with presumably non-olfactory function in insects is likely the basis of olfaction in terrestrial hermit crabs.

  7. 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.

    Science.gov (United States)

    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.

  8. 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.

  9. Glutamate modulation of GABA transport in retinal horizontal cells of the skate

    Science.gov (United States)

    Kreitzer, Matthew A; Andersen, Kristen A; Malchow, Robert Paul

    2003-01-01

    Transport of the amino acid GABA into neurons and glia plays a key role in regulating the effects of GABA in the vertebrate retina. We have examined the modulation of GABA-elicited transport currents of retinal horizontal cells by glutamate, the likely neurotransmitter of vertebrate photoreceptors. Enzymatically isolated external horizontal cells of skate were examined using whole-cell voltage-clamp techniques. GABA (1 mm) elicited an inward current that was completely suppressed by the GABA transport inhibitors tiagabine (10 μm) and SKF89976-A (100 μm), but was unaffected by 100 μm picrotoxin. Prior application of 100 μm glutamate significantly reduced the GABA-elicited current. Glutamate depressed the GABA dose-response curve without shifting the curve laterally or altering the voltage dependence of the current. The ionotropic glutamate receptor agonists kainate and AMPA also reduced the GABA-elicited current, and the effects of glutamate and kainate were abolished by the ionotropic glutamate receptor antagonist 6-cyano-7-nitroquinoxaline. NMDA neither elicited a current nor modified the GABA-induced current, and metabotropic glutamate analogues were also without effect. Inhibition of the GABA-elicited current by glutamate and kainate was reduced when extracellular calcium was removed and when recording pipettes contained high concentrations of the calcium chelator BAPTA. Caffeine (5 mm) and thapsigargin (2 nm), agents known to alter intracellular calcium levels, also reduced the GABA-elicited current, but increases in calcium induced by depolarization alone did not. Our data suggest that glutamate regulates GABA transport in retinal horizontal cells through a calcium-dependent process, and imply a close physical relationship between calcium-permeable glutamate receptors and GABA transporters in these cells. PMID:12562999

  10. 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.

  11. 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.

  12. 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.

  13. Glutamatergic mechanisms for speed control and network operation in the rodent locomotor CPG

    DEFF Research Database (Denmark)

    Talpalar, Adolfo E.; Kiehn, Ole

    2010-01-01

    in mammals have produced conflicting results regarding the necessity and role of the different ionotropic glutamate receptors (GluRs) in the CPG function. Here, we use electrophysiological and pharmacological techniques in the in vitro neonatal mouse lumbar spinal cord to investigate the role of a broad...... mechanisms acting at various network levels. AMPA and kainate receptors are necessary for generating the highest locomotor frequencies. For coordination, NMDARs are more important than non-NMDARs for conveying the rhythmic signal from the network to the motor neurons during long-lasting and steady locomotor...

  14. 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

  15. Full domain closure of the ligand-binding core of the ionotropic glutamate receptor iGluR5 induced by the high affinity agonist dysiherbaine and the functional antagonist 8,9-dideoxyneodysiherbaine

    DEFF Research Database (Denmark)

    Frydenvang, Karla Andrea; Lash, L Leanne; Naur, Peter

    2009-01-01

    The prevailing structural model for ligand activation of ionotropic glutamate receptors posits that agonist efficacy arises from the stability and magnitude of induced domain closure in the ligand-binding core structure. Here we describe an exception to the correlation between ligand efficacy and...

  16. 4,4-Dimethyl- and diastereomeric 4-hydroxy-4-methyl-(2S)-glutamate analogues display distinct pharmacological profiles at ionotropic glutamate receptors and excitatory amino acid transporters

    DEFF Research Database (Denmark)

    Bunch, Lennart; Pickering, Darryl S; Gefflaut, Thierry

    2009-01-01

    this approach has provided important insight into the structure-activity relationships (SAR) for ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs), as well as the excitatory amino acid transporters (EAATs). In this work, three 4,4-disubstituted Glu analogues 1-3, which are hybrid structures......Subtype-selective ligands are of great interest to the scientific community, as they provide a tool for investigating the function of one receptor or transporter subtype when functioning in its native environment. Several 4-substituted (S)-glutamate (Glu) analogues were synthesized, and altogether...

  17. 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

  18. 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.

  19. Discovery of a New Class of Ionotropic Glutamate Receptor Antagonists by the Rational Design of (2S,3R)-3-(3-Carboxyphenyl)-pyrrolidine-2-carboxylic Acid

    DEFF Research Database (Denmark)

    Larsen, Ann Møller; Venskutonyte, Raminta; Valadés, Elena Antón

    2011-01-01

    The kainic acid (KA) receptors belong to the class of glutamate (Glu) receptors in the brain and constitute a promising target for the treatment of neurological and/ or psychiatric diseases such as schizophrenia, major depression, and epilepsy. Five KA subtypes have been identified and named GluK1......-5. In this article, we present the discovery of (2S,3R)-3-(3-carboxyphenyl)-pyrrolidine-2-carboxylic acid (1) based on a rational design process. Target compound 1 was synthesized by a stereoselective strategy in 10 steps from commercially available starting materials. Binding affinities of 1 at native ionotropic...

  20. 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.

  1. 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.

  2. Maturation profile of inferior olivary neurons expressing ionotropic glutamate receptors in rats: role in coding linear accelerations.

    Science.gov (United States)

    Li, Chuan; Han, Lei; Ma, Chun-Wai; Lai, Suk-King; Lai, Chun-Hong; Shum, Daisy Kwok Yan; Chan, Ying-Shing

    2013-07-01

    Using sinusoidal oscillations of linear acceleration along both the horizontal and vertical planes to stimulate otolith organs in the inner ear, we charted the postnatal time at which responsive neurons in the rat inferior olive (IO) first showed Fos expression, an indicator of neuronal recruitment into the otolith circuit. Neurons in subnucleus dorsomedial cell column (DMCC) were activated by vertical stimulation as early as P9 and by horizontal (interaural) stimulation as early as P11. By P13, neurons in the β subnucleus of IO (IOβ) became responsive to horizontal stimulation along the interaural and antero-posterior directions. By P21, neurons in the rostral IOβ became also responsive to vertical stimulation, but those in the caudal IOβ remained responsive only to horizontal stimulation. Nearly all functionally activated neurons in DMCC and IOβ were immunopositive for the NR1 subunit of the NMDA receptor and the GluR2/3 subunit of the AMPA receptor. In situ hybridization studies further indicated abundant mRNA signals of the glutamate receptor subunits by the end of the second postnatal week. This is reinforced by whole-cell patch-clamp data in which glutamate receptor-mediated miniature excitatory postsynaptic currents of rostral IOβ neurons showed postnatal increase in amplitude, reaching the adult level by P14. Further, these neurons exhibited subthreshold oscillations in membrane potential as from P14. Taken together, our results support that ionotropic glutamate receptors in the IO enable postnatal coding of gravity-related information and that the rostral IOβ is the only IO subnucleus that encodes spatial orientations in 3-D.

  3. 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

  4. 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

  5. (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...

  6. AMPA receptor ligands

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Mellor, Ian

    2004-01-01

    Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player in the f......Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player...... in the formation of memory. Hence, ligands affecting AMPARs are highly important for the study of the structure and function of this receptor, and in this regard polyamine-based ligands, particularly polyamine toxins, are unique as they selectively block Ca2+ -permeable AMPARs. Indeed, endogenous intracellular...

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. Design and synthesis of labeled analogs of PhTX-56, a potent and selective AMPA receptor antagonist

    DEFF Research Database (Denmark)

    Andersen, Trine F; Vogensen, Stine B; Jensen, Lars S

    2005-01-01

    Polyamines and polyamine toxins are biologically important molecules, having modulatory effects on nucleotides and proteins. The wasp toxin, philanthotoxin-433 (PhTX-433), is a non-selective and uncompetitive antagonist of ionotropic receptors, such as ionotropic glutamate receptors and nicotinic...

  13. 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.

  14. 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...

  15. 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...

  16. FMRFamide-gated sodium channel and ASIC channels: a new class of ionotropic receptors for FMRFamide and related peptides.

    Science.gov (United States)

    Lingueglia, Eric; Deval, Emmanuel; Lazdunski, Michel

    2006-05-01

    FMRFamide and related peptides typically exert their action through G-protein coupled receptors. However, two ionotropic receptors for these peptides have recently been identified. They are both members of the epithelial amiloride-sensitive Na+ channel and degenerin (ENaC/DEG) family of ion channels. The invertebrate FMRFamide-gated Na+ channel (FaNaC) is a neuronal Na+-selective channel which is directly gated by micromolar concentrations of FMRFamide and related tetrapeptides. Its response is fast and partially desensitizing, and FaNaC has been proposed to participate in peptidergic neurotransmission. On the other hand, mammalian acid-sensing ion channels (ASICs) are not gated but are directly modulated by FMRFamide and related mammalian peptides like NPFF and NPSF. ASICs are activated by external protons and are therefore extracellular pH sensors. They are expressed both in the central and peripheral nervous system and appear to be involved in many physiological and pathophysiological processes such as hippocampal long-term potentiation and defects in learning and memory, acquired fear-related behavior, retinal function, brain ischemia, pain sensation in ischemia and inflammation, taste perception, hearing functions, and mechanoperception. The potentiation of ASIC activity by endogenous RFamide neuropeptides probably participates in the response to noxious acidosis in sensory and central neurons. Available data also raises the possibility of the existence of still unknown FMRFamide related endogenous peptides acting as direct agonists for ASICs.

  17. L-Asp is a useful tool in the purification of the ionotropic glutamate receptor A2 ligand-binding domain

    DEFF Research Database (Denmark)

    Krintel, Christian; Frydenvang, Karla; Ceravalls de Rabassa, Anna

    2014-01-01

    In purification of the ionotropic glutamate receptor A2 (GluA2) ligand-binding domain (LBD), L-Glu supplemented buffers have previously been used for protein stabilization during the procedure. This sometimes hampers structural studies of low affinity ligands because L-Glu is difficult to displace...... crystallized as a mixed dimer with L-Glu present in one subunit while neither L-Asp nor L-Glu were found in the other subunit. Thus, residual L-Glu is still present from the expression. On the other hand, only L-Asp was found at the binding site when using 50 mM or 250 mM L-Asp for crystallization. The binding...... mode observed for L-Asp at the GluA2 LBD is very similar to that described for L-Glu. Taken together, we have shown that L-Asp can be used instead of L-Glu for ligand-dependent stabilization of the GluA2 LBD during purification. This will enable structural studies of low affinity ligands for lead...

  18. 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.

  19. 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...

  20. Structural and Molecular Modeling Features of P2X Receptors

    Directory of Open Access Journals (Sweden)

    Luiz Anastacio Alves

    2014-03-01

    Full Text Available Currently, adenosine 5'-triphosphate (ATP is recognized as the extracellular messenger that acts through P2 receptors. P2 receptors are divided into two subtypes: P2Y metabotropic receptors and P2X ionotropic receptors, both of which are found in virtually all mammalian cell types studied. Due to the difficulty in studying membrane protein structures by X-ray crystallography or NMR techniques, there is little information about these structures available in the literature. Two structures of the P2X4 receptor in truncated form have been solved by crystallography. Molecular modeling has proven to be an excellent tool for studying ionotropic receptors. Recently, modeling studies carried out on P2X receptors have advanced our knowledge of the P2X receptor structure-function relationships. This review presents a brief history of ion channel structural studies and shows how modeling approaches can be used to address relevant questions about P2X receptors.

  1. Genome-wide identification, characterization and classification of ionotropic glutamate receptor genes (iGluRs) in the malaria vector Anopheles sinensis (Diptera: Culicidae).

    Science.gov (United States)

    Wang, Ting-Ting; Si, Feng-Ling; He, Zheng-Bo; Chen, Bin

    2018-01-15

    Ionotropic glutamate receptors (iGluRs) are conserved ligand-gated ion channel receptors, and ionotropic receptors (IRs) were revealed as a new family of iGluRs. Their subdivision was unsettled, and their characteristics are little known. Anopheles sinensis is a major malaria vector in eastern Asia, and its genome was recently well sequenced and annotated. We identified iGluR genes in the An. sinensis genome, analyzed their characteristics including gene structure, genome distribution, domains and specific sites by bioinformatic methods, and deduced phylogenetic relationships of all iGluRs in An. sinensis, Anopheles gambiae and Drosophila melanogaster. Based on the characteristics and phylogenetics, we generated the classification of iGluRs, and comparatively analyzed the intron number and selective pressure of three iGluRs subdivisions, iGluR group, Antenna IR and Divergent IR subfamily. A total of 56 iGluR genes were identified and named in the whole-genome of An. sinensis. These genes were located on 18 scaffolds, and 31 of them (29 being IRs) are distributed into 10 clusters that are suggested to form mainly from recent gene duplication. These iGluRs can be divided into four groups: NMDA, non-NMDA, Antenna IR and Divergent IR based on feature comparison and phylogenetic analysis. IR8a and IR25a were suggested to be monophyletic, named as Putative in the study, and moved from the Antenna subfamily in the IR family to the non-NMDA group as a sister of traditional non-NMDA. The generated iGluRs of genes (including NMDA and regenerated non-NMDA) are relatively conserved, and have a more complicated gene structure, smaller ω values and some specific functional sites. The iGluR genes in An. sinensis, An. gambiae and D. melanogaster have amino-terminal domain (ATD), ligand binding domain (LBD) and Lig_Chan domains, except for IR8a that only has the LBD and Lig_Chan domains. However, the new concept IR family of genes (including regenerated Antenna IR, and Divergent

  2. The effects of conformational constraints and steric bulk in the amino acid moiety of philanthotoxins on AMPAR antagonism

    DEFF Research Database (Denmark)

    Jørgensen, Malene; Olsen, Christian A; Mellor, Ian R

    2005-01-01

    , establishing general protocols for philanthotoxin solution- and solid-phase synthesis (39-90% and 42-54% overall yields, respectively). The analogues were tested for their ability to antagonize kainate-induced currents of 2-amino-3-(3-hydroxy-5-methyl-4-isoxazoyl)propanoic acid receptors (AMPAR) expressed...... in Xenopus oocytes from rat brain mRNA. This showed that steric bulk in the amino acid moiety is well tolerated and suggests that binding to AMPAR does not involve the alpha-NHCO group as a donor in hydrogen bonding.......Philanthotoxin-343 (PhTX-343), a synthetic analogue of wasp toxin PhTX-433, is a noncompetitive antagonist at ionotropic receptors (e.g., AChR or iGluR). To determine possible effects of variations of the amino acid side chain, a library consisting of seventeen PhTX-343 analogues was prepared. Thus...

  3. 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)

  4. 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)

  5. 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)

  6. 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.

  7. 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.

  8. Glutamate as a neurotransmitter in the brain: review of physiology and pathology.

    Science.gov (United States)

    Meldrum, B S

    2000-04-01

    Glutamate is the principal excitatory neurotransmitter in brain. Our knowledge of the glutamatergic synapse has advanced enormously in the last 10 years, primarily through application of molecular biological techniques to the study of glutamate receptors and transporters. There are three families of ionotropic receptors with intrinsic cation permeable channels [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate]. There are three groups of metabotropic, G protein-coupled glutamate receptors (mGluR) that modify neuronal and glial excitability through G protein subunits acting on membrane ion channels and second messengers such as diacylglycerol and cAMP. There are also two glial glutamate transporters and three neuronal transporters in the brain. Glutamate is the most abundant amino acid in the diet. There is no evidence for brain damage in humans resulting from dietary glutamate. A kainate analog, domoate, is sometimes ingested accidentally in blue mussels; this potent toxin causes limbic seizures, which can lead to hippocampal and related pathology and amnesia. Endogenous glutamate, by activating NMDA, AMPA or mGluR1 receptors, may contribute to the brain damage occurring acutely after status epilepticus, cerebral ischemia or traumatic brain injury. It may also contribute to chronic neurodegeneration in such disorders as amyotrophic lateral sclerosis and Huntington's chorea. In animal models of cerebral ischemia and traumatic brain injury, NMDA and AMPA receptor antagonists protect against acute brain damage and delayed behavioral deficits. Such compounds are undergoing testing in humans, but therapeutic efficacy has yet to be established. Other clinical conditions that may respond to drugs acting on glutamatergic transmission include epilepsy, amnesia, anxiety, hyperalgesia and psychosis.

  9. 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....

  10. Design and Synthesis of a Series of L-trans-4-Substituted Prolines as Selective Antagonists for the Ionotropic Glutamate Receptors Including Functional and X-ray Crystallographic Studies of New Subtype Selective Kainic Acid Receptor Subtype 1 (GluK1) Antagonist (2S,4R)-4-(2-Carboxyphenoxy)pyrrolidine

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, Niels; Delgar, Claudia; Koch, Karina

    2017-01-01

    Ionotropic glutamate receptor antagonists are valuable tool compounds for studies of neurological pathways in the central nervous system. On the basis of rational ligand design, a new class of selective antagonists, represented by (2S,4R)-4-(2-carboxy-phenoxy)pyrrolidine-2-carboxylic acid (1b...... to the structure with glutamate, consistent with 1b being an antagonist. A structure-activity relationship study showed that the chemical nature of the tethering atom (C,O, or S) linking the pyrrolidine ring and the phenyl ring plays a key role in the receptor selectivity profile and that substituents......), for cloned homomeric kainic acid receptor subtype 1 (GluK1) was attained (Ki = 4 µM). In a functional assay, 1b displayed full antagonist activity with IC50 = 6 ± 2 µM. A crystal structure was obtained of 1b when bound in the ligand binding domain of GluK1. A domain opening of 13-14° was seen compared...

  11. 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.

  12. The Role of GluK4 in Synaptic Plasticity and Affective Behavior in Mice

    Science.gov (United States)

    Catches, Justin Samuel

    Kainate receptors (KARs) are glutamate-gated ion channels that signal through both ionotropic and metabotropic pathways (Contractor et al., 2011). Combinations of five KAR subunits (GluK1-5) form tetrameric receptors with GluK1, GluK2, and GluK3 able to form functional homomeric channels. The high-affinity subunits, GluK4 and GluK5, do not form homomeric channels but modify the properties of heteromeric receptors. Expression of the GluK4 receptor subunit in the forebrain is restricted to the CA3 region of the hippocampus and dentate gyrus regions where KARs modulate synaptic plasticity. In this study, ablation of Grik4, which encodes GluK4, in mice reduced KAR synaptic currents and altered activation properties of postsynaptic receptors but left two forms of presynaptic short-term plasticity intact. Disruption of both Grik4 and Grik5 caused complete loss of the postsynaptic ionotropic KAR current and impaired presynaptic frequency facilitation. Additionally, KAR surface expression was altered at pre- and postsynaptic sites at the MF synapse. Despite the loss of ionotropic signaling, KAR-mediated inhibition of the slow afterhyperpolarization current, which is dependent on metabotropic signaling, was intact in CA3 neurons. Long-term potentiation at the MF-CA3 synapse was reduced, likely through a loss of KAR modulation of excitability of the presynaptic MF axons. Genetic variants in the human GRIK4 gene alter the susceptibility for affective disorders (Bloss and Hunter, 2010). We found that ablation of Grik4 in mice resulted in reduced anxiety and an antidepressant-like phenotype. In the elevated zero-maze, a test for anxiety and risk taking behavior, and in two anxiogenic tests, marble-burying and novelty-induced suppression of feeding, anxiety-like behavior was consistently reduced in knockout animals. In the forced swim, a test of learned helplessness used to determine depression-like behavior, knockout mice demonstrated significantly less immobility suggesting

  13. Aryl- and heteroaryl-substituted phenylalanines as AMPA receptor ligands

    DEFF Research Database (Denmark)

    Szymańska, Ewa; Chałupnik, Paulina; Johansen, Tommy Nørskov

    2017-01-01

    in radioligand binding assays at native rat ionotropic glutamate receptors. The most interesting compound in this series, (RS)-2-amino-3-(3'-hydroxy-5-(1H-pyrazol-4-yl)-[1,1'-biphenyl]-3-yl)propanoic acid 7e, showed the binding affinity of 4.6 µM for native AMPA receptors and almost 5-fold lower affinity...

  14. Subtype selective kainic acid receptor agonists

    DEFF Research Database (Denmark)

    Bunch, Lennart; Krogsgaard-Larsen, Povl

    2009-01-01

    (S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors (m......GluRs). Within the iGluRs, five subtypes (KA1, KA2, iGluR5-7) show high affinity and express full agonist activity upon binding of the naturally occurring amino acid kainic acid (KA). Thus these receptors have been named the KA receptors. This review describes all-to our knowledge-published KA receptor agonists...

  15. 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

  16. 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...

  17. 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.

  18. 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...

  19. 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

  20. Evidence for a role of glutamate as an efferent transmitter in taste buds

    Directory of Open Access Journals (Sweden)

    Anderson Catherine B

    2010-06-01

    Full Text Available Abstract Background Glutamate has been proposed as a transmitter in the peripheral taste system in addition to its well-documented role as an umami taste stimulus. Evidence for a role as a transmitter includes the presence of ionotropic glutamate receptors in nerve fibers and taste cells, as well as the expression of the glutamate transporter GLAST in Type I taste cells. However, the source and targets of glutamate in lingual tissue are unclear. In the present study, we used molecular, physiological and immunohistochemical methods to investigate the origin of glutamate as well as the targeted receptors in taste buds. Results Using molecular and immunohistochemical techniques, we show that the vesicular transporters for glutamate, VGLUT 1 and 2, but not VGLUT3, are expressed in the nerve fibers surrounding taste buds but likely not in taste cells themselves. Further, we show that P2X2, a specific marker for gustatory but not trigeminal fibers, co-localizes with VGLUT2, suggesting the VGLUT-expressing nerve fibers are of gustatory origin. Calcium imaging indicates that GAD67-GFP Type III taste cells, but not T1R3-GFP Type II cells, respond to glutamate at concentrations expected for a glutamate transmitter, and further, that these responses are partially blocked by NBQX, a specific AMPA/Kainate receptor antagonist. RT-PCR and immunohistochemistry confirm the presence of the Kainate receptor GluR7 in Type III taste cells, suggesting it may be a target of glutamate released from gustatory nerve fibers. Conclusions Taken together, the results suggest that glutamate may be released from gustatory nerve fibers using a vesicular mechanism to modulate Type III taste cells via GluR7.

  1. (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.

  2. (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

  3. 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.

  4. 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

  5. To Break or to Brake Neuronal Network Accelerated by Ammonium Ions?

    Directory of Open Access Journals (Sweden)

    Vladimir V Dynnik

    Full Text Available The aim of present study was to investigate the effects of ammonium ions on in vitro neuronal network activity and to search alternative methods of acute ammonia neurotoxicity prevention.Rat hippocampal neuronal and astrocytes co-cultures in vitro, fluorescent microscopy and perforated patch clamp were used to monitor the changes in intracellular Ca2+- and membrane potential produced by ammonium ions and various modulators in the cells implicated in neural networks.Low concentrations of NH4Cl (0.1-4 mM produce short temporal effects on network activity. Application of 5-8 mM NH4Cl: invariably transforms diverse network firing regimen to identical burst patterns, characterized by substantial neuronal membrane depolarization at plateau phase of potential and high-amplitude Ca2+-oscillations; raises frequency and average for period of oscillations Ca2+-level in all cells implicated in network; results in the appearance of group of «run out» cells with high intracellular Ca2+ and steadily diminished amplitudes of oscillations; increases astrocyte Ca2+-signalling, characterized by the appearance of groups of cells with increased intracellular Ca2+-level and/or chaotic Ca2+-oscillations. Accelerated network activity may be suppressed by the blockade of NMDA or AMPA/kainate-receptors or by overactivation of AMPA/kainite-receptors. Ammonia still activate neuronal firing in the presence of GABA(A receptors antagonist bicuculline, indicating that «disinhibition phenomenon» is not implicated in the mechanisms of networks acceleration. Network activity may also be slowed down by glycine, agonists of metabotropic inhibitory receptors, betaine, L-carnitine, L-arginine, etc.Obtained results demonstrate that ammonium ions accelerate neuronal networks firing, implicating ionotropic glutamate receptors, having preserved the activities of group of inhibitory ionotropic and metabotropic receptors. This may mean, that ammonia neurotoxicity might be prevented by

  6. Modification of the philanthotoxin-343 polyamine moiety results in different structure-activity profiles at muscle nicotinic ACh, NMDA and AMPA receptors

    DEFF Research Database (Denmark)

    Mellor, I R; Brier, T J; Pluteanu, F

    2003-01-01

    Voltage-dependent, non-competitive inhibition by philanthotoxin-343 (PhTX-343) analogues, with reduced charge or length, of nicotinic acetylcholine receptors (nAChR) of TE671 cells and ionotropic glutamate receptors (N-methyl-D-aspartate receptors (NMDAR) and alpha-amino-3-hydroxy-5-methyl-4...

  7. (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.

  8. 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....

  9. General synthesis of β-alanine-containing spider polyamine toxins and discovery of nephila polyamine toxins 1 and 8 as highly potent inhibitors of ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Lucas, Simon; Poulsen, Mette H; Nørager, Niels G

    2012-01-01

    Certain spiders contain large pools of polyamine toxins, which are putative pharmacological tools awaiting further discovery. Here we present a general synthesis strategy for this class of toxins and prepare five structurally varied polyamine toxins. Electrophysiological testing at three ionotrop...

  10. The combination of glutamate receptor antagonist MK-801 with tamoxifen and its active metabolites potentiates their antiproliferative activity in mouse melanoma K1735-M2 cells

    International Nuclear Information System (INIS)

    Ribeiro, Mariana P.C.; Nunes-Correia, Isabel; Santos, Armanda E.; Custódio, José B.A.

    2014-01-01

    Recent reports suggest that N-methyl-D-aspartate receptor (NMDAR) blockade by MK-801 decreases tumor growth. Thus, we investigated whether other ionotropic glutamate receptor (iGluR) antagonists were also able to modulate the proliferation of melanoma cells. On the other hand, the antiestrogen tamoxifen (TAM) decreases the proliferation of melanoma cells, and is included in combined therapies for melanoma. As the efficacy of TAM is limited by its metabolism, we investigated the effects of the NMDAR antagonist MK-801 in combination with TAM and its active metabolites, 4-hydroxytamoxifen (OHTAM) and endoxifen (EDX). The NMDAR blockers MK-801 and memantine decreased mouse melanoma K1735-M2 cell proliferation. In contrast, the NMDAR competitive antagonist APV and the AMPA and kainate receptor antagonist NBQX did not affect cell proliferation, suggesting that among the iGluR antagonists only the NMDAR channel blockers inhibit melanoma cell proliferation. The combination of antiestrogens with MK-801 potentiated their individual effects on cell biomass due to diminished cell proliferation, since it decreased the cell number and DNA synthesis without increasing cell death. Importantly, TAM metabolites combined with MK-801 promoted cell cycle arrest in G1. Therefore, the data obtained suggest that the activity of MK-801 and antiestrogens in K1735-M2 cells is greatly enhanced when used in combination. - Highlights: • MK-801 and memantine decrease melanoma cell proliferation. • The combination of MK-801 with antiestrogens inhibits melanoma cell proliferation. • These combinations greatly enhance the effects of the compounds individually. • MK-801 combined with tamoxifen active metabolites induces cell cycle arrest in G1. • The combination of MK-801 and antiestrogens is an innovative strategy for melanoma

  11. 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....

  12. Solid-phase synthesis of polyamine toxin analogues

    DEFF Research Database (Denmark)

    Kromann, Hasse; Krikstolaityte, Sonata; Andersen, Anne J

    2002-01-01

    The wasp toxin philanthotoxin-433 (PhTX-433) is a nonselective and noncompetitive antagonist of ionotropic receptors, such as ionotropic glutamate receptors and nicotinic acetylcholine receptors. Polyamine toxins are extensively used for the characterization of subtypes of ionotropic glutamate re...

  13. 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.

  14. Stargazin Modulation of AMPA Receptors

    Directory of Open Access Journals (Sweden)

    Sana A. Shaikh

    2016-10-01

    Full Text Available Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin. Our nanopositioning data place stargazin below the AMPA receptor ligand-binding domain, where it is well poised to act as a scaffold to facilitate the long-range conformational selection observations seen in single-molecule experiments. These data support a model of stargazin acting to stabilize or select conformational states that favor activation.

  15. [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

  16. 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....

  17. A Rare Syndrome of Deletion in 2 Siblings

    Directory of Open Access Journals (Sweden)

    Aravindhan Veerapandiyan MBBS

    2017-08-01

    Full Text Available The Glutamate receptor, ionotropic, delta 2 gene codes for an ionotropic glutamate delta-2 receptor, which is selectively expressed in cerebellar Purkinje cells, and facilitates cerebellar synapse organization and transmission. The phenotype associated with the deletion of Glutamate receptor, ionotropic, delta 2 gene in humans was initially defined in 2013. In this case report, the authors describe 2 brothers who presented with developmental delay, tonic upward gaze, nystagmus, oculomotor apraxia, hypotonia, hyperreflexia, and ataxia. They were found to have a homozygous intragenic deletion within the Glutamate receptor, ionotropic, delta 2 gene at exon 2. Our patients serve as an addition to the literature of previously reported children with this rare clinical syndrome associated with Glutamate receptor, ionotropic, delta 2 deletion.

  18. 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)

  19. 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...

  20. 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.

  1. Identification of an ionotropic glutamate receptor AMPA1/GRIA1 polymorphism in crossbred beef cows differing in fertility.

    Science.gov (United States)

    Cushman, R A; Miles, J R; Rempel, L A; McDaneld, T G; Kuehn, L A; Chitko-McKown, C G; Nonneman, D; Echternkamp, S E

    2013-06-01

    A proposed functional polymorphism in the ionotropic glutamate receptor AMPA1 (GRIA1) has been reported to influence antral follicle numbers and fertility in cows. Repeat breeder cows that fail to produce a calf in multiple seasons have been reported to have reduced numbers of small (1 to 3 mm) antral follicles in their ovaries. Therefore, we tested the hypothesis that this GRIA1 polymorphism was affecting antral follicle numbers in repeat breeder cows. Repeat breeder cows (n = 64) and control cows (n = 72) that had always produced a calf were housed in a dry lot and observed twice daily for behavioral estrus. Blood samples were collected, and cows were genotyped for this GRIA1 polymorphism and for a polymorphism in the GnRH receptor (GnRHR) that was proposed to influence age at puberty. On d 3 to 8 after estrus cows were slaughtered, and reproductive organs were collected to determine antral follicle count, ovary size, and uterine horn diameter. Repeat breeder cows were older at first calving than control cows (P = 0.006). The length (P = 0.03) and height (P = 0.02) of the ovary contralateral to the corpus luteum (CL) were greater in control cows than repeat breeder cows. The endometrial diameter in the horn ipsilateral to the CL was greater in the control cows than the repeat breeder cows. Repeat breeder cows had fewer small (1 to 5 mm) antral follicles than control cows (P = 0.003); however, there was no association between GRIA1 genotype and antral follicle number. The GnRHR polymorphism was associated with age at first calving because cows that were homozygous for the C allele had a greater age at first calving than heterozygous cows or cows that were homozygous for the T allele (P = 0.01). In the granulosa cells from small (1 to 5 mm) antral follicles, mRNA abundances of 2 markers of oocyte quality, anti-Müllerian hormone and pentraxin 3, did not differ between fertility groups (P ≥ 0.12). We conclude that this GRIA1 polymorphism exists in beef cows but

  2. 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.

  3. Neuromodulation by Mg2+ and polyamines of excitatory amino acid currents in rodent neurones in culture.

    Science.gov (United States)

    Kumamoto, E

    1996-12-01

    Excitatory amino-acid currents in rodent central neurones are mediated by the activation of glutamate receptors. Ionotropic types of the receptors are divided into alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), kainate and N-methyl-D-aspartate (NMDA) receptors, and the former two are collectively called non-NMDA receptors. The NMDA receptor is modulated by a number of endogenous neuromodulators including Mg2+, polyamines, glycine and protons in extracellular solutions. Although it has been generally thought that each of the neuromodulators acts on a distinct site in the NMDA receptor, recent studies have revealed that these actions may be not necessarily independent of each other. The NMDA receptor response is not only inhibited but also potentiated by Mg2+, and the latter action is due to an interaction of a Mg2+ site with either glycine- or proton-binding site. In the presence of polyamines, a tonic inhibition by protons of the NMDA receptor response is relieved, resulting in a potentiation of the response. Alternatively, it has been recently revealed that there are some subtypes of non-NMDA receptors which are negatively modulated by polyamines in either extra- or intra cellular solutions. The difference in polyamine sensitivity among non-NMDA receptors is attributed to a distinction in their constituted subunits. The inhibition of non-NMDA receptor by intracellular polyamines results in inward rectification of the current-voltage relation which is not seen for polyamine-insensitive ones. This polyamine action is not mimicked by intracellular Mg2+.

  4. Tetrazolyl isoxazole amino acids as ionotropic glutamate receptor antagonists: synthesis, modelling and molecular pharmacology

    DEFF Research Database (Denmark)

    Frølund, Bente; Greenwood, Jeremy R; Holm, Mai Marie

    2005-01-01

    and 1b were pharmacologically characterized in receptor binding assays, and electrophysiologically on homomeric AMPA receptors (GluR1-4), homomeric (GluR5 and GluR6) and heteromeric (GluR6/KA2) kainic acid receptors, using two-electrode voltage-clamped Xenopus laevis oocytes expressing these receptors...

  5. Modern approaches to the design of memory and cognitive function stimulants based on AMPA receptor ligands

    International Nuclear Information System (INIS)

    Grigoriev, V V; Proshin, A N; Kinzirsky, A S; Bachurin, Sergey O

    2009-01-01

    Data on the structure and properties of compounds acting on AMPA receptors, the key subtype of ionotropic glutamate receptors of the mammalian central nervous system, are analyzed. Data on the role of these receptors in provision of memory and cognitive function formation and impairment processes are presented. The attention is focused on the modern views on the mechanisms of AMPA receptor desensitization and deactivation and action of substances affecting these processes. The structures of key positive modulators of AMPA receptors are given. The problems of application of these substances as therapeutic means for preventing and treating neurodegenerative and psychoneurological diseases are discussed. Bibliography - 121 references.

  6. Modern approaches to the design of memory and cognitive function stimulants based on AMPA receptor ligands

    Energy Technology Data Exchange (ETDEWEB)

    Grigoriev, V V; Proshin, A N; Kinzirsky, A S; Bachurin, Sergey O [Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2009-05-31

    Data on the structure and properties of compounds acting on AMPA receptors, the key subtype of ionotropic glutamate receptors of the mammalian central nervous system, are analyzed. Data on the role of these receptors in provision of memory and cognitive function formation and impairment processes are presented. The attention is focused on the modern views on the mechanisms of AMPA receptor desensitization and deactivation and action of substances affecting these processes. The structures of key positive modulators of AMPA receptors are given. The problems of application of these substances as therapeutic means for preventing and treating neurodegenerative and psychoneurological diseases are discussed. Bibliography - 121 references.

  7. Modern approaches to the design of memory and cognitive function stimulants based on AMPA receptor ligands

    Science.gov (United States)

    Grigoriev, V. V.; Proshin, A. N.; Kinzirsky, A. S.; Bachurin, Sergey O.

    2009-05-01

    Data on the structure and properties of compounds acting on AMPA receptors, the key subtype of ionotropic glutamate receptors of the mammalian central nervous system, are analyzed. Data on the role of these receptors in provision of memory and cognitive function formation and impairment processes are presented. The attention is focused on the modern views on the mechanisms of AMPA receptor desensitization and deactivation and action of substances affecting these processes. The structures of key positive modulators of AMPA receptors are given. The problems of application of these substances as therapeutic means for preventing and treating neurodegenerative and psychoneurological diseases are discussed. Bibliography — 121 references.

  8. Bone phenotypes of P2 receptor knockout mice

    DEFF Research Database (Denmark)

    Orriss, Isabel; Syberg, Susanne; Wang, Ning

    2011-01-01

    The action of extracellular nucleotides is mediated by ionotropic P2X receptors and G-protein coupled P2Y receptors. The human genome contains 7 P2X and 8 P2Y receptor genes. Knockout mice strains are available for most of them. As their phenotypic analysis is progressing, bone abnormalities have...... been observed in an impressive number of these mice: distinct abnormalities in P2X7-/- mice, depending on the gene targeting construct and the genetic background, decreased bone mass in P2Y1-/- mice, increased bone mass in P2Y2-/- mice, decreased bone resorption in P2Y6-/- mice, decreased bone...... formation and bone resorption in P2Y13-/- mice. These findings demonstrate the unexpected importance of extracellular nucleotide signalling in the regulation of bone metabolism via multiple P2 receptors and distinct mechanisms involving both osteoblasts and osteoclasts....

  9. 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

  10. 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.

  11. Augmentation of Anticancer Drug Efficacy in Murine Hepatocellular Carcinoma Cells by a Peripherally Acting Competitive N-Methyl-d-aspartate (NMDA) Receptor Antagonist

    DEFF Research Database (Denmark)

    Gynther, Mikko; Proietti Silvestri, Ilaria; Hansen, Jacob C

    2017-01-01

    -acting ionotropic glutamate receptor antagonist 1a. Subsequently, we demonstrate that 1l augments the cytotoxic action of sorafenib in murine hepatocellular carcinoma cells. The underlying biological mechanism was shown to be interference with the lipid signaling pathway, leading to reduced expression of MDR...

  12. Lipid raft integrity affects GABAA receptor, but not NMDA receptor modulation by psychopharmacological compounds.

    Science.gov (United States)

    Nothdurfter, Caroline; Tanasic, Sascha; Di Benedetto, Barbara; Uhr, Manfred; Wagner, Eva-Maria; Gilling, Kate E; Parsons, Chris G; Rein, Theo; Holsboer, Florian; Rupprecht, Rainer; Rammes, Gerhard

    2013-07-01

    Lipid rafts have been shown to play an important role for G-protein mediated signal transduction and the function of ligand-gated ion channels including their modulation by psychopharmacological compounds. In this study, we investigated the functional significance of the membrane distribution of NMDA and GABAA receptor subunits in relation to the accumulation of the tricyclic antidepressant desipramine (DMI) and the benzodiazepine diazepam (Diaz). In the presence of Triton X-100, which allowed proper separation of the lipid raft marker proteins caveolin-1 and flotillin-1 from the transferrin receptor, all receptor subunits were shifted to the non-raft fractions. In contrast, under detergent-free conditions, NMDA and GABAA receptor subunits were detected both in raft and non-raft fractions. Diaz was enriched in non-raft fractions without Triton X-100 in contrast to DMI, which preferentially accumulated in lipid rafts. Impairment of lipid raft integrity by methyl-β-cyclodextrine (MβCD)-induced cholesterol depletion did not change the inhibitory effect of DMI at the NMDA receptor, whereas it enhanced the potentiating effect of Diaz at the GABAA receptor at non-saturating concentrations of GABA. These results support the hypothesis that the interaction of benzodiazepines with the GABAA receptor likely occurs outside of lipid rafts while the antidepressant DMI acts on ionotropic receptors both within and outside these membrane microdomains.

  13. Synthesis of novel N1-substituted bicyclic pyrazole amino acids and evaluation of their interaction with glutamate receptors

    DEFF Research Database (Denmark)

    Conti, Paola; Grazioso, Giovanni; di Ventimiglia, Samuele Joppolo

    2005-01-01

    N1-substituted bicyclic pyrazole amino acids (S)-9a-9c and (R)-9a-9c, which are conformationally constrained analogues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested for activity at ionotropic and metabotropic glutamate receptors...

  14. Structure-Activity Relationship Study of Ionotropic Glutamate Receptor Antagonist (2S,3R)-3-(3-Carboxyphenyl)pyrrolidine-2-carboxylic Acid

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, Niels; Storgaard, Morten; Møller, Charlotte

    2015-01-01

    Herein we describe the first structure-activity relationship study of the broad-range iGluR antagonist (2S,3R)-3-(3-carboxyphenyl)pyrrolidine-2-carboxylic acid (1) by exploring the pharmacological effect of substituents in the 4, 4', or 5' positions and the bioisosteric substitution of the distal...... carboxylic acid for a phosphonic acid moiety. Of particular interest is a hydroxyl group in the 4' position 2a which induced a preference in binding affinity for homomeric GluK3 over GluK1 (Ki = 0.87 and 4.8 μM, respectively). Two X-ray structures of ligand binding domains were obtained: 2e in GluA2-LBD...... and 2f in GluK1-LBD, both at 1.9 Å resolution. Compound 2e induces a D1-D2 domain opening in GluA2-LBD of 17.3-18.8° and 2f a domain opening in GluK1-LBD of 17.0-17.5° relative to the structures with glutamate. The pyrrolidine-2-carboxylate moiety of 2e and 2f shows a similar binding mode as kainate...

  15. 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.

  16. Functional expression of ionotropic purinergic receptors on mouse taste bud cells.

    Science.gov (United States)

    Hayato, Ryotaro; Ohtubo, Yoshitaka; Yoshii, Kiyonori

    2007-10-15

    Neurotransmitter receptors on taste bud cells (TBCs) and taste nerve fibres are likely to contribute to taste transduction by mediating the interaction among TBCs and that between TBCs and taste nerve fibres. We investigated the functional expression of P2 receptor subtypes on TBCs of mouse fungiform papillae. Electrophysiological studies showed that 100 microm ATP applied to their basolateral membranes either depolarized or hyperpolarized a few cells per taste bud. Ca(2+) imaging showed that similarly applied 1 mum ATP, 30 microm BzATP (a P2X(7) agonist), or 1 microm 2MeSATP (a P2Y(1) and P2Y(11) agonist) increased intracellular Ca(2+) concentration, but 100 microm UTP (a P2Y(2) and P2Y(4) agonist) and alpha,beta-meATP (a P2X agonist except for P2X(2), P2X(4) and P2X(7)) did not. RT-PCR suggested the expression of P2X(2), P2X(4), P2X(7), P2Y(1), P2Y(13) and P2Y(14) among the seven P2X subtypes and seven P2Y subtypes examined. Immunohistostaining confirmed the expression of P2X(2). The exposure of the basolateral membranes to 3 mm ATP for 30 min caused the uptake of Lucifer Yellow CH in a few TBCs per taste bud. This was antagonized by 100 microm PPADS (a non-selective P2 blocker) and 1 microm KN-62 (a P2X(7) blocker). These results showed for the first time the functional expression of P2X(2) and P2X(7) on TBCs. The roles of P2 receptor subtypes in the taste transduction, and the renewal of TBCs, are discussed.

  17. 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...

  18. Posttranslational Modification Biology of Glutamate Receptors and Drug Addiction

    Directory of Open Access Journals (Sweden)

    Li-Min eMao

    2011-03-01

    Full Text Available Posttranslational covalent modifications of glutamate receptors remain a hot topic. Early studies have established that this family of receptors, including almost all ionotropic and metabotropic glutamate receptor subtypes, undergoes active phosphorylation at serine, threonine, or tyrosine residues on their intracellular domains. Recent evidence identifies several glutamate receptor subtypes to be direct substrates for palmitoylation at cysteine residues. Other modifications such as ubiquitination and sumoylation at lysine residues also occur to certain glutamate receptors. These modifications are dynamic and reversible in nature and are regulatable by changing synaptic inputs. The regulated modifications significantly impact the receptor in many ways, including interrelated changes in biochemistry (synthesis, subunit assembling and protein-protein interactions, subcellular redistribution (trafficking, endocytosis, synaptic delivery and clustering, and physiology, usually associated with changes in synaptic plasticity. Glutamate receptors are enriched in the striatum and cooperate closely with dopamine to regulate striatal signaling. Emerging evidence shows that modification processes of striatal glutamate receptors are sensitive to addictive drugs, such as psychostimulants (cocaine and amphetamines. Altered modifications are believed to be directly linked to enduring receptor/synaptic plasticity and drug-seeking. This review summarizes several major types of modifications of glutamate receptors and analyzes the role of these modifications in striatal signaling and in the pathogenesis of psychostimulant addiction.

  19. 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....

  20. Synthesis, binding affinity at glutamic acid receptors, neuroprotective effects, and molecular modeling investigation of novel dihydroisoxazole amino acids

    DEFF Research Database (Denmark)

    Conti, Paola; De Amici, Marco; Grazioso, Giovanni

    2005-01-01

    stereoisomers of the bicyclic analogue 5-amino-4,5,6,6a-tetrahydro-3aH-cyclopenta[d]isoxazole-3,5-dicarboxylic acid (+)-2, (-)-2, (+)-3, and (-)-3 were tested at ionotropic and metabotropic glutamate receptor subtypes. The most potent NMDA receptor antagonists [(+)-2, (-)-4, and (+)-5] showed a significant......The four stereoisomers of 5-(2-amino-2-carboxyethyl)-4,5-dihydroisoxazole-3-carboxylic acid(+)-4, (-)-4, (+)-5, and (-)-5 were prepared by stereoselective synthesis of two pairs of enantiomers, which were subsequently resolved by enzymatic procedures. These four stereoisomers and the four...

  1. 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

  2. Expression of GABAergic receptors in mouse taste receptor cells.

    Directory of Open Access Journals (Sweden)

    Margaret R Starostik

    Full Text Available BACKGROUND: Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD for gamma-aminobutyric acid (GABA is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABA(A and GABA(C or metabotropic receptors (GABA(B while it is terminated by the re-uptake of GABA through transporters (GATs. METHODOLOGY/PRINCIPAL FINDINGS: Using reverse transcriptase-PCR (RT-PCR analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs in the circumvallate papillae express multiple subunits of the GABA(A and GABA(B receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABA(A-and GABA(B- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds. CONCLUSIONS/SIGNIFICANCE: The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.

  3. Recent Progress in Understanding Subtype Specific Regulation of NMDA Receptors by G Protein Coupled Receptors (GPCRs

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2014-02-01

    Full Text Available G Protein Coupled Receptors (GPCRs are the largest family of receptors whose ligands constitute nearly a third of prescription drugs in the market. They are widely involved in diverse physiological functions including learning and memory. NMDA receptors (NMDARs, which belong to the ionotropic glutamate receptor family, are likewise ubiquitously expressed in the central nervous system (CNS and play a pivotal role in learning and memory. Despite its critical contribution to physiological and pathophysiological processes, few pharmacological interventions aimed directly at regulating NMDAR function have been developed to date. However, it is well established that NMDAR function is precisely regulated by cellular signalling cascades recruited downstream of G protein coupled receptor (GPCR stimulation. Accordingly, the downstream regulation of NMDARs likely represents an important determinant of outcome following treatment with neuropsychiatric agents that target selected GPCRs. Importantly, the functional consequence of such regulation on NMDAR function varies, based not only on the identity of the GPCR, but also on the cell type in which relevant receptors are expressed. Indeed, the mechanisms responsible for regulating NMDARs by GPCRs involve numerous intracellular signalling molecules and regulatory proteins that vary from one cell type to another. In the present article, we highlight recent findings from studies that have uncovered novel mechanisms by which selected GPCRs regulate NMDAR function and consequently NMDAR-dependent plasticity.

  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. 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

  6. Ionotropic glutamate receptors (iGluRs) of the delta family (GluD1 ...

    African Journals Online (AJOL)

    Muhammad Zahid Khan

    2016-10-20

    Oct 20, 2016 ... GluD1 knockout mice (GluD1 KO) have normal learning in the Morris water maze .... could bind and activate the receptor.5,6 D-Ser and glycine have now been identified as .... English editing of this manuscript. References. 1.

  7. 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...

  8. Cockroach GABAB receptor subtypes: molecular characterization, pharmacological properties and tissue distribution.

    Science.gov (United States)

    Blankenburg, S; Balfanz, S; Hayashi, Y; Shigenobu, S; Miura, T; Baumann, O; Baumann, A; Blenau, W

    2015-01-01

    γ-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABAA receptors or metabotropic GABAB receptors. GABAB receptors regulate, via Gi/o G-proteins, ion channels, and adenylyl cyclases. In humans, GABAB receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABAB receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABAB receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABAB receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABAB receptors act as autoreceptors in this neuron. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Ionotropic glutamate receptors (iGluRs) of the delta family (GluD1 ...

    African Journals Online (AJOL)

    ... such as Neurexin1. This review presents current knowledge regarding the expression, structure and function of Glu delta receptors (GluD1, GluD2) in brain, focusing on synapse formation, function and dysfunction. Keywords: iGluRs; GluD1; GluD2; Synaptogenesis; Autism spectrum disorder (ASD); Schizophrenia (SCZ) ...

  10. 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.

  11. Excitatory amino acid transmission in health and disease

    National Research Council Canada - National Science Library

    Balázs, R; Bridges, Richard J; Cotman, Carl W

    2006-01-01

    ... Structure of the Ionotropic Glutamate Receptors, 23 3 AMPA RECEPTORS, 36 Molecular Structure, Properties, and Regulation, 36 Distribution of AMPA Receptors, 41 AMPA Receptor Pharmacology, 46 Th...

  12. An NMDA Receptor-Dependent Mechanism Underlies Inhibitory Synapse Development

    Directory of Open Access Journals (Sweden)

    Xinglong Gu

    2016-01-01

    Full Text Available In the mammalian brain, GABAergic synaptic transmission provides inhibitory balance to glutamatergic excitatory drive and controls neuronal output. The molecular mechanisms underlying the development of GABAergic synapses remain largely unclear. Here, we report that NMDA-type ionotropic glutamate receptors (NMDARs in individual immature neurons are the upstream signaling molecules essential for GABAergic synapse development, which requires signaling via Calmodulin binding motif in the C0 domain of the NMDAR GluN1 subunit. Interestingly, in neurons lacking NMDARs, whereas GABAergic synaptic transmission is strongly reduced, the tonic inhibition mediated by extrasynaptic GABAA receptors is increased, suggesting a compensatory mechanism for the lack of synaptic inhibition. These results demonstrate a crucial role for NMDARs in specifying the development of inhibitory synapses, and suggest an important mechanism for controlling the establishment of the balance between synaptic excitation and inhibition in the developing brain.

  13. The structure and function of glutamate receptors: Mg2+ block to X-ray diffraction.

    Science.gov (United States)

    Mayer, Mark L

    2017-01-01

    Experiments on the action of glutamate on mammalian and amphibian nervous systems started back in the 1950s but decades passed before it became widely accepted that glutamate was the major excitatory neurotransmitter in the CNS. The pace of research greatly accelerated in the 1980s when selective ligands that identified glutamate receptor subtypes became widely available, and voltage clamp techniques, coupled with rapid perfusion, began to resolve the unique functional properties of what cloning subsequently revealed to be a large family of receptors with numerous subtypes. More recently the power of X-ray crystallography and cryo-EM has been applied to the study of glutamate receptors, revealing their atomic structures, and the conformational changes that underlie their gating. In this review I summarize the history of this field, viewed through the lens of a career in which I spent 3 decades working on the structure and function of glutamate receptor ion channels. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'. Published by Elsevier Ltd.

  14. Ion channels in EEG: isolating channel dysfunction in NMDA receptor antibody encephalitis.

    Science.gov (United States)

    Symmonds, Mkael; Moran, Catherine H; Leite, M Isabel; Buckley, Camilla; Irani, Sarosh R; Stephan, Klaas Enno; Friston, Karl J; Moran, Rosalyn J

    2018-04-30

    Neurological and psychiatric practice frequently lack diagnostic probes that can assess mechanisms of neuronal communication non-invasively in humans. In N-methyl-d-aspartate (NMDA) receptor antibody encephalitis, functional molecular assays are particularly important given the presence of NMDA antibodies in healthy populations, the multifarious symptomology and the lack of radiological signs. Recent advances in biophysical modelling techniques suggest that inferring cellular-level properties of neural circuits from macroscopic measures of brain activity is possible. Here, we estimated receptor function from EEG in patients with NMDA receptor antibody encephalitis (n = 29) as well as from encephalopathic and neurological patient controls (n = 36). We show that the autoimmune patients exhibit distinct fronto-parietal network changes from which ion channel estimates can be obtained using a microcircuit model. Specifically, a dynamic causal model of EEG data applied to spontaneous brain responses identifies a selective deficit in signalling at NMDA receptors in patients with NMDA receptor antibody encephalitis but not at other ionotropic receptors. Moreover, though these changes are observed across brain regions, these effects predominate at the NMDA receptors of excitatory neurons rather than at inhibitory interneurons. Given that EEG is a ubiquitously available clinical method, our findings suggest a unique re-purposing of EEG data as an assay of brain network dysfunction at the molecular level.

  15. 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.

  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. M1 muscarinic receptor facilitates cognitive function by interplay with AMPA receptor GluA1 subunit.

    Science.gov (United States)

    Zhao, Lan-Xue; Ge, Yan-Hui; Xiong, Cai-Hong; Tang, Ling; Yan, Ying-Hui; Law, Ping-Yee; Qiu, Yu; Chen, Hong-Zhuan

    2018-03-06

    M1 muscarinic acetylcholine receptors (M1 mAChRs) are the most abundant muscarinic receptors in the hippocampus and have been shown to have procognitive effects. AMPA receptors (AMPARs), an important subtype of ionotropic glutamate receptors, are key components in neurocognitive networks. However, the role of AMPARs in procognitive effects of M1 mAChRs and how M1 mAChRs affect the function of AMPARs remain poorly understood. Here, we found that basal expression of GluA1, a subunit of AMPARs, and its phosphorylation at Ser845 were maintained by M1 mAChR activity. Activation of M1 mAChRs promoted membrane insertion of GluA1, especially to postsynaptic densities. Impairment of hippocampus-dependent learning and memory by antagonism of M1 mAChRs paralleled the reduction of GluA1 expression, and improvement of learning and memory by activation of M1 mAChRs was accompanied by the synaptic insertion of GluA1 and its increased phosphorylation at Ser845. Furthermore, abrogation of phosphorylation of Ser845 residue of GluA1 ablated M1 mAChR-mediated improvement of learning and memory. Taken together, these results show a functional correlation of M1 mAChRs and GluA1 and the essential role of GluA1 in M1 mAChR-mediated cognitive improvement.-Zhao, L.-X., Ge, Y.-H., Xiong, C.-H., Tang, L., Yan, Y.-H., Law, P.-Y., Qiu, Y., Chen, H.-Z. M1 muscarinic receptor facilitates cognitive function by interplay with AMPA receptor GluA1 subunit.

  18. Putative chemosensory receptors of the codling moth, Cydia pomonella, identified by antennal transcriptome analysis.

    Directory of Open Access Journals (Sweden)

    Jonas M Bengtsson

    Full Text Available The codling moth, Cydia pomonella, is an important fruit pest worldwide. As nocturnal animals, adults depend to a large extent on olfactory cues for detection of food and mates, and, for females, oviposition sites. In insects, odor detection is mediated by odorant receptors (ORs and ionotropic receptors (IRs, which ensure the specificity of the olfactory sensory neuron responses. In this study, our aim was to identify chemosensory receptors in the codling moth as a means to uncover new targets for behavioral interference. Using next-generation sequencing techniques, we identified a total of 43 candidate ORs, one gustatory receptor and 15 IRs in the antennal transcriptome. Through Blast and sequence similarity analyses we annotated the insect obligatory co-receptor ORco, five genes clustering in a conserved clade containing sex pheromone receptors, one homolog of the Bombyx mori female-enriched receptor BmorOR30 (but no homologs of the other B. mori female-enriched receptors and one gene clustering in the sugar receptor family. Among the candidate IRs, we identified homologs of the two highly conserved co-receptors IR8a and IR25a, and one homolog of an IR involved in phenylethyl amine detection in Drosophila. Our results open for functional characterization of the chemosensory receptors of C. pomonella, with potential for new or refined applications of semiochemicals for control of this pest insect.

  19. 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.

  20. (S)-homo-AMPA, a specific agonist at the mGlu6 subtype of metabotropic glutamic acid receptors

    DEFF Research Database (Denmark)

    Ahmadian, H; Nielsen, B; Bräuner-Osborne, Hans

    1997-01-01

    of the spectroscopic configurational assignments. The activities of 6 and 7 at ionotropic EAA (iGlu) receptors and at mGlu1-7 were studied. (S)-Homo-AMPA (6) was shown to be a specific agonist at mGlu6 (EC50 = 58 +/- 11 microM) comparable in potency with the endogenous mGlu agonist (S)-glutamic acid (EC50 = 20 +/- 3......Our previous publication (J. Med. Chem. 1996, 39, 3188-3194) described (RS)-2-amino-4-(3-hydroxy-5-methylisoxazol-4-yl)butyric acid (Homo-AMPA) as a highly selective agonist at the mGlu6 subtype of metabotropic excitatory amino acid (EAA) receptors. Homo-AMPA has already become a standard agonist...... microM). Although Homo-AMPA did not show significant effects at iGlu receptors, (R)-Homo-AMPA (7), which was inactive at mGlu1-7, turned out to be a weak N-methyl-D-aspartic acid (NMDA) receptor antagonist (IC50 = 131 +/- 18 microM)....

  1. A2BR Adenosine Receptor Modulates Sweet Taste in Circumvallate Taste Buds

    Science.gov (United States)

    Yang, Dan; Shultz, Nicole; Vandenbeuch, Aurelie; Ravid, Katya; Kinnamon, Sue C.; Finger, Thomas E.

    2012-01-01

    In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3) on taste nerves as well as metabotropic (P2Y) purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR) is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate), but not anterior (fungiform, palate) taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields. PMID:22253866

  2. A2BR adenosine receptor modulates sweet taste in circumvallate taste buds.

    Science.gov (United States)

    Kataoka, Shinji; Baquero, Arian; Yang, Dan; Shultz, Nicole; Vandenbeuch, Aurelie; Ravid, Katya; Kinnamon, Sue C; Finger, Thomas E

    2012-01-01

    In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3) on taste nerves as well as metabotropic (P2Y) purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR) is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate), but not anterior (fungiform, palate) taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields.

  3. Molecular Characterization and Differential Expression of an Olfactory Receptor Gene Family in the White-Backed Planthopper Sogatella furcifera Based on Transcriptome Analysis.

    Directory of Open Access Journals (Sweden)

    Ming He

    Full Text Available The white-backed planthopper, Sogatella furcifera, a notorious rice pest in Asia, employs host plant volatiles as cues for host location. In insects, odor detection is mediated by two types of olfactory receptors: odorant receptors (ORs and ionotropic receptors (IRs. In this study, we identified 63 SfurORs and 14 SfurIRs in S. furcifera based on sequences obtained from the head transcriptome and bioinformatics analysis. The motif-pattern of 130 hemiptera ORs indicated an apparent differentiation in this order. Phylogenetic trees of the ORs and IRs were constructed using neighbor-joining estimates. Most of the ORs had orthologous genes, but a specific OR clade was identified in S. furcifera, which suggests that these ORs may have specific olfactory functions in this species. Our results provide a basis for further investigations of how S. furcifera coordinates its olfactory receptor genes with its plant hosts, thereby providing a foundation for novel pest management approaches based on these genes.

  4. Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model

    DEFF Research Database (Denmark)

    Chan, K Y; Gupta, S; de Vries, R

    2010-01-01

    During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical...

  5. Synthesis and pharmacology of 3-isoxazolol amino acids as selective antagonists at group I metabotropic glutamic acid receptors

    DEFF Research Database (Denmark)

    Madsen, U; Bräuner-Osborne, H; Frydenvang, Karla Andrea

    2001-01-01

    Using ibotenic acid (2) as a lead, two series of 3-isoxazolol amino acid ligands for (S)-glutamic acid (Glu, 1) receptors have been developed. Whereas analogues of (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid [AMPA, (RS)-3] interact selectively with ionotropic Glu receptors (i......GluRs), the few analogues of (RS)-2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid [HIBO, (RS)-4] so far known typically interact with iGluRs as well as metabotropic Glu receptors (mGluRs). We here report the synthesis and pharmacology of a series of 4-substituted analogues of HIBO. The hexyl analogue 9 was shown...... to originate in (S)-11 (EC(50) = 395 microM, K(b) = 86 and 90 microM, respectively). Compound 9, administered icv, but not sc, was shown to protect mice against convulsions induced by N-methyl-D-aspartic acid (NMDA). Compounds 9 and 11 were resolved using chiral HPLC, and the configurational assignments...

  6. A2BR adenosine receptor modulates sweet taste in circumvallate taste buds.

    Directory of Open Access Journals (Sweden)

    Shinji Kataoka

    Full Text Available In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3 on taste nerves as well as metabotropic (P2Y purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate, but not anterior (fungiform, palate taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields.

  7. P2X7 receptor-mediated calcium dynamics in HEK293 cells: experimental characterization and modelling approach

    International Nuclear Information System (INIS)

    Di Garbo, A; Alloisio, S; Nobile, M

    2012-01-01

    The P2X7 receptor (P2X7R) induces ionotropic Ca 2+  signalling in different cell types. It plays an important role in the immune response and in the nervous system. Here, the mechanisms underlying intracellular Ca 2+  variations evoked by 3′-O-(4-benzoyl)benzoyl-ATP (BzATP), a potent agonist of the P2X7R, in transfected HEK293 cells, are investigated both experimentally and theoretically. We propose a minimal model of P2X7R that is capable of reproducing, qualitatively and quantitatively, the experimental data. This approach was also adopted for the P2X7R variant, which lacks the entire C-terminus tail (trP2X7R). Then we introduce a biophysical model describing the Ca 2+  dynamics in HEK293. Our model gives an account of the ionotropic Ca 2+  influx evoked by BzATP on the basis of the kinetics model of P2X7R. To explain the complex Ca 2+  responses evoked by BzATP, the model predicted that an impairment in Ca 2+  extrusion flux through the plasma membrane is a key factor for Ca 2+ homeostasis in HEK293 cells. (paper)

  8. P2X7 receptor-mediated calcium dynamics in HEK293 cells: experimental characterization and modelling approach

    Science.gov (United States)

    Di Garbo, A.; Alloisio, S.; Nobile, M.

    2012-04-01

    The P2X7 receptor (P2X7R) induces ionotropic Ca2 + signalling in different cell types. It plays an important role in the immune response and in the nervous system. Here, the mechanisms underlying intracellular Ca2 + variations evoked by 3‧-O-(4-benzoyl)benzoyl-ATP (BzATP), a potent agonist of the P2X7R, in transfected HEK293 cells, are investigated both experimentally and theoretically. We propose a minimal model of P2X7R that is capable of reproducing, qualitatively and quantitatively, the experimental data. This approach was also adopted for the P2X7R variant, which lacks the entire C-terminus tail (trP2X7R). Then we introduce a biophysical model describing the Ca2 + dynamics in HEK293. Our model gives an account of the ionotropic Ca2 + influx evoked by BzATP on the basis of the kinetics model of P2X7R. To explain the complex Ca2 + responses evoked by BzATP, the model predicted that an impairment in Ca2 + extrusion flux through the plasma membrane is a key factor for Ca2 + homeostasis in HEK293 cells.

  9. Suppression of Human Liver Cancer Cell Migration and Invasion via the GABAA Receptor

    International Nuclear Information System (INIS)

    Chen, Zhi-ao; Bao, Mei-yan; Xu, Yong-fen; Zha, Ruo-peng; Shi, Hai-bing; Chen, Tao-yang; He, Xiang-huo

    2012-01-01

    To investigate the roles of the γ-aminobutyric acid (GABA) in the metastasis of hepatocellular carcinoma (HCC) and to explore the potential of a novel therapeutic approach for the treatment of HCC. The expression levels of GABA receptor subunit genes in various HCC cell lines and patients‘ tissues were detected by quantitative real-time polymerase chain reaction and Western blot analysis. Transwell cell migration and invasion assays were carried out for functional analysis. The effects of GABA on liver cancer cell cytoskeletal were determined by immunofluorescence staining. And the effects of GABA on HCC metastasis in nude mice were evaluated using an in vivo orthotopic model of liver cancer. The mRNA level of GABA receptor subunits varied between the primary hepatocellular carcinoma tissue and the adjacent non-tumor liver tissue. GABA inhibited human liver cancer cell migration and invasion via the ionotropic GABA A receptor as a result of the induction of liver cancer cell cytoskeletal reorganization. Pretreatment with GABA also significantly reduced intrahepatic liver metastasis and primary tumor formation in vivo. These findings introduce a potential and novel therapeutic approach for the treatment of cancer patients based on the modulation of the GABAergic system

  10. Differential alterations of cortical glutamatergic binding sites in senile dementia of the Alzheimer type

    International Nuclear Information System (INIS)

    Chalmers, D.T.; Dewar, D.; Graham, D.I.; Brooks, D.N.; McCulloch, J.

    1990-01-01

    Involvement of cortical glutamatergic mechanisms in senile dementia of the Alzheimer type (SDAT) has been investigated with quantitative ligand-binding autoradiography. The distribution and density of Na(+)-dependent glutamate uptake sites and glutamate receptor subtypes--kainate, quisqualate, and N-methyl-D-aspartate--were measured in adjacent sections of frontal cortex obtained postmortem from six patients with SDAT and six age-matched controls. The number of senile plaques was determined in the same brain region. Binding of D-[3H]aspartate to Na(+)-dependent uptake sites was reduced by approximately 40% throughout SDAT frontal cortex relative to controls, indicating a general loss of glutamatergic presynaptic terminals. [3H]Kainate receptor binding was significantly increased by approximately 70% in deep layers of SDAT frontal cortex compared with controls, whereas this binding was unaltered in superficial laminae. There was a positive correlation (r = 0.914) between kainate binding and senile plaque number in deep cortical layers. Quisqualate receptors, as assessed by 2-amino-3-hydroxy-5-[3H]methylisoxazole-4-propionic acid binding, were unaltered in SDAT frontal cortex compared with controls. There was a small reduction (25%) in N-methyl-D-aspartate-sensitive [3H]glutamate binding only in superficial cortical layers of SDAT brains relative to control subjects. [3H]Glutamate binding in SDAT subjects was unrelated to senile plaque number in superficial cortical layers (r = 0.104). These results indicate that in the presence of cortical glutamatergic terminal loss in SDAT plastic alterations occur in some glutamate receptor subtypes but not in others

  11. Distribution of the a2, a3, and a5 nicotinic acetylcholine receptor subunits in the chick brain

    Directory of Open Access Journals (Sweden)

    Torrão A.S.

    1997-01-01

    Full Text Available Nicotinic acetylcholine receptors (nAChRs are ionotropic receptors comprised of a and ß subunits. These receptors are widely distributed in the central nervous system, and previous studies have revealed specific patterns of localization for some nAChR subunits in the vertebrate brain. In the present study we used immunohistochemical methods and monoclonal antibodies to localize the a2, a3, and a5 nAChR subunits in the chick mesencephalon and diencephalon. We observed a differential distribution of these three subunits in the chick brain, and showed that the somata and neuropil of many central structures contain the a5 nAChR subunit. The a2 and a3 subunits, on the other hand, exhibited a more restricted distribution than a5 and other subunits previously studied, namely a7, a8 and ß2. The patterns of distribution of the different nAChR subunits suggest that neurons in many brain structures may contain several subtypes of nAChRs and that in a few regions one particular subtype may determine the cholinergic nicotinic responses

  12. Seizures beget seizures in temporal lobe epilepsies: the boomerang effects of newly formed aberrant kainatergic synapses.

    Science.gov (United States)

    Ben-Ari, Yehezkel; Crepel, Valérie; Represa, Alfonso

    2008-01-01

    Do temporal lobe epilepsy (TLE) seizures in adults promote further seizures? Clinical and experimental data suggest that new synapses are formed after an initial episode of status epilepticus, however their contribution to the transformation of a naive network to an epileptogenic one has been debated. Recent experimental data show that newly formed aberrant excitatory synapses on the granule cells of the fascia dentate operate by means of kainate receptor-operated signals that are not present on naive granule cells. Therefore, genuine epileptic networks rely on signaling cascades that differentiate them from naive networks. Recurrent limbic seizures generated by the activation of kainate receptors and synapses in naive animals lead to the formation of novel synapses that facilitate the emergence of further seizures. This negative, vicious cycle illustrates the central role of reactive plasticity in neurological disorders.

  13. A neuronal acetylcholine receptor regulates the balance of muscle excitation and inhibition in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Maelle Jospin

    2009-12-01

    Full Text Available In the nematode Caenorhabditis elegans, cholinergic motor neurons stimulate muscle contraction as well as activate GABAergic motor neurons that inhibit contraction of the contralateral muscles. Here, we describe the composition of an ionotropic acetylcholine receptor that is required to maintain excitation of the cholinergic motor neurons. We identified a gain-of-function mutation that leads to spontaneous muscle convulsions. The mutation is in the pore domain of the ACR-2 acetylcholine receptor subunit and is identical to a hyperactivating mutation in the muscle receptor of patients with myasthenia gravis. Screens for suppressors of the convulsion phenotype led to the identification of other receptor subunits. Cell-specific rescue experiments indicate that these subunits function in the cholinergic motor neurons. Expression of these subunits in Xenopus oocytes demonstrates that the functional receptor is comprised of three alpha-subunits, UNC-38, UNC-63 and ACR-12, and two non-alpha-subunits, ACR-2 and ACR-3. Although this receptor exhibits a partially overlapping subunit composition with the C. elegans muscle acetylcholine receptor, it shows distinct pharmacology. Recordings from intact animals demonstrate that loss-of-function mutations in acr-2 reduce the excitability of the cholinergic motor neurons. By contrast, the acr-2(gf mutation leads to a hyperactivation of cholinergic motor neurons and an inactivation of downstream GABAergic motor neurons in a calcium dependent manner. Presumably, this imbalance between excitatory and inhibitory input into muscles leads to convulsions. These data indicate that the ACR-2 receptor is important for the coordinated excitation and inhibition of body muscles underlying sinusoidal movement.

  14. Potential Involvement of P2 Receptors in the Pathological Processes of Hyperthyroidism: A Pilot Study.

    Science.gov (United States)

    Hong, Wu; Li, Guodong; Nie, Yijun; Zou, Lifang; Zhang, Xi; Liu, Shuangmei; Li, Guilin; Xu, Hong; Zhang, Chun-Ping; Liang, Shangdong

    2016-05-01

    Symptoms of hyperthyroidism manifest mainly as changes in the nervous and metabolic systems. Whether P2X receptors (ionotropic ATP purinergic receptors, including P2X3 receptor and P2X7 receptor) are involved in the alterations of these disorders still remains unclear. Thus, this study aimed to assess the association of hyperthyroidism with the expression of P2X3 and P2X7 receptors and the concentrations of ATP in blood leukocytes and catecholamine. Twelve healthy subjects and twelve patients diagnosed with hyperthyroidism were recruited. Serum free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) levels had been detected by chemiluminescence method. Meanwhile, the catecholamine levels (including adrenaline, noradrenaline, and dopamine) in plasma, ATP level and P2X receptors (including P2X3 receptor and P2X7 receptor) in peripheral blood had been detected by high performance liquid chromatography, bioluminescence method, and reverse transcription polymerase chain reaction, respectively. Levels of epinephrine and norepinephrine were significantly higher in the hyperthyroidism group compared with the control group. The concentration of ATP in the hyperthyroidism group was significantly higher than its in the control group. The expression of P2X3 mRNA and P2X7 mRNA in hyperthyroidism group were significantly increased compared with those in control group. In a conclusion, there is a relationship between the elevated expression of P2X3 receptor and P2X7 receptor in peripheral blood leukocytes and high serum epinephrine and norepinephrine levels in hyperthyroidism patients. © 2016 by the Association of Clinical Scientists, Inc.

  15. Pharmacological approaches to the study of CHOLINO- and GABA-receptor states in nerve cells after irradiation with low intensity

    International Nuclear Information System (INIS)

    Anan'eva, T.V.; Dvoretskij, A.I.

    2000-01-01

    The peculiarities of functioning specific cholino- and GABA-receptors (ChR and GABA-R) by modeling the effect of synaptic neuromediators, correspondingly acetocholine (ACh) and gamma-aminobutyric acid (GABA), in low concentrations on the K + active transport in the rats cerebral cortex after single-time or chronical total irradiation with the dose of 0.25 Gy are studied. As a result of the study of both the acetocholine (10 -10 and 10 -6 mole/l) and gamma-aminobutyric avid (10 -9 and 10 -5 mole/l) effects on the K + active transport in the rats cerebral cortex slices in presence of any selective antagonists of the choline- and GABA-receptors, it is shown, that after the whole body irradiation with 25 c Gy (1.75 m Gy/min) the metabotropic muscarinic ChR and GABA B - receptors were involved into the processes of neurotransmitter modulation, whereas under ionotropic nicotinic choline- and GAB A - receptors. The observed changes are supposed to be of adaptive character. The post irradiation structural and functional disturbances may be considered as one of the causes of essential distortions in the processes of interneuronal metabolic communication in the central nerve system [ru

  16. Prostaglandin E(2) stimulates glutamate receptor-dependent astrocyte neuromodulation in cultured hippocampal cells.

    Science.gov (United States)

    Sanzgiri, R P; Araque, A; Haydon, P G

    1999-11-05

    Recent Ca(2+) imaging studies in cell culture and in situ have shown that Ca(2+) elevations in astrocytes stimulate glutamate release and increase neuronal Ca(2+) levels, and that this astrocyte-neuron signaling can be stimulated by prostaglandin E(2) (PGE(2)). We investigated the electrophysiological consequences of the PGE(2)-mediated astrocyte-neuron signaling using whole-cell recordings on cultured rat hippocampal cells. Focal application of PGE(2) to astrocytes evoked a Ca(2+) elevation in the stimulated cell by mobilizing internal Ca(2+) stores, which further propagated as a Ca(2+) wave to neighboring astrocytes. Whole-cell recordings from neurons revealed that PGE(2) evoked a slow inward current in neurons adjacent to astrocytes. This neuronal response required the presence of an astrocyte Ca(2+) wave and was mediated through both N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors. Taken together with previous studies, these data demonstrate that PGE(2)-evoked Ca(2+) elevations in astrocyte cause the release of glutamate which activates neuronal ionotropic receptors. Copyright 1999 John Wiley & Sons, Inc.

  17. GluN2B-containing NMDA receptors and AMPA receptors in medial prefrontal cortex are necessary for odor span in rats

    Directory of Open Access Journals (Sweden)

    Don A Davies

    2013-12-01

    Full Text Available Working memory is a type of short-term memory involved in the maintenance and manipulation of information essential for complex cognition. While memory span capacity has been extensively studied in humans as a measure of working memory, it has received considerably less attention in rodents. Our aim was to examine the role of the NMDA and AMPA glutamate receptors in odor span capacity using systemic injections or infusions of receptor antagonists into the medial prefrontal cortex. Long Evans rats were trained on a well-characterized odor span task. Initially, rats were trained to dig for a food reward in sand followed by training on a non-match to sample discrimination using sand scented with household spices. The rats were then required to perform a serial delayed non-match to sample procedure which was their odor span. Systemic injection of the broad spectrum NMDA receptor antagonist CPP (10 mg/kg or the GluN2B-selective antagonist Ro25-6981 (10 mg/kg but not 6 mg/kg significantly reduced odor span capacity. Infusions of the GluN2B- selective antagonist Ro25-6981 (2.5 µg/hemisphere into medial prefrontal cortex reduced span capacity, an effect that was nearly significant (p = 0.069. Infusions of the AMPA receptor antagonist CNQX (1.25 µg/hemisphere into medial prefrontal cortex reduced span capacity and latency for the rats to make a choice in the task. These results demonstrate span capacity in rats depends on ionotropic glutamate receptor activation in the medial prefrontal cortex. Further understanding of the circuitry underlying span capacity may aid in the novel therapeutic drug development for persons with working memory impairments as a result of disorders such as schizophrenia and Alzheimer’s disease.

  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. Biological Effects of Drug-Free Alginate Beads Cross-Linked by Copper Ions Prepared Using External Ionotropic Gelation.

    Science.gov (United States)

    Pavelková, M; Kubová, K; Vysloužil, J; Kejdušová, M; Vetchý, D; Celer, V; Molinková, D; Lobová, D; Pechová, A; Vysloužil, J; Kulich, P

    2017-05-01

    External ionotropic gelation offers a unique possibility to entrap multivalent ions in a polymer structure. The aim of this experimental study was to prepare new drug-free sodium alginate (ALG) particles cross-linked by Cu 2+ ions and to investigate their technological parameters (particle size, sphericity, surface topology, swelling capacity, copper content, release of Cu 2+ ions, mucoadhesivity) and biological activity (cytotoxicity and efficiency against the most common vaginal pathogens-Herpes simplex, Escherichia coli, Candida albicans) with respect to potential vaginal administration. Beads prepared from NaALG dispersions (3 or 4%) were cross-linked by Cu 2+ ions (0.5 or 1.0 M CuCl 2 ) using external ionotropic gelation. Prepared mucoadhesive beads with particle size over 1000 μm exhibited sufficient sphericity (all ˃0.89) and copper content (214.8-249.07 g/kg), which increased with concentration of polymer and hardening solution. Dissolution behaviour was characterized by extended burst effect, followed by 2 h of copper release. The efficiency of all samples against the most common vaginal pathogens was observed at cytotoxic Cu 2+ concentrations. Anti-HSV activity was demonstrated at a Cu 2+ concentration of 546 mg/L. Antibacterial activity of beads (expressed as minimum inhibition concentration, MIC) was influenced mainly by the rate of Cu 2+ release which was controlled by the extent of swelling capacity. Lower MIC values were found for E. coli in comparison with C. albicans. Sample ALG-3_1.0 exhibited the fastest copper release and was proved to be the most effective against both bacteria. This could be a result of its lower polymer concentration in combination with smaller particle size and thus larger surface area.

  20. Modulation of [3H]-glutamate binding by serotonin in the rat hippocampus: An autoradiographic study

    International Nuclear Information System (INIS)

    Mennini, T.; Miari, A.

    1991-01-01

    Serotonin (5-HT) added in vitro increased [ 3 H]-glutamate specific binding in the rat hippocampus, reaching statistical significance in layers rich in N-Methyl-D-Aspartate sensitive glutamate receptors. This effect was explained by a significant increase in the apparent affinity of [ 3 H]-glutamate when 5-HT is added in vitro. Two days after lesion of serotonergic afferents to the hippocampus with 5,7- Dihydroxytryptamine [ 3 H]-glutamate binding was significantly decreased in the CA3 region and stratum lacunosum moleculare of the hippocampus, this reduction being reversed by in vitro addition of 10 μM 5-HT. The decrease observed is due to a significant reduction of quisqualate-insensitive (radiatum CA3) and kainate receptors (strata oriens, radiatum, pyramidal of CA3). Five days after lesion [ 3 H]-glutamate binding increased significantly in the CA3 region of the hippocampus but was not different from sham animals in the other hippocampal layers. Two weeks after lesion [ 3 H]-glutamate binding to quisqualate-insensitive receptors was increased in all the hippocampal layers, while kainate and quisqualate-sensitive receptors were not affected. These data are consistent with the possibility that 5-HT is a direct positive modulator of glutamate receptor subtypes

  1. 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...

  2. 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

  3. Rapid glutamate receptor 2 trafficking during retinal degeneration

    Directory of Open Access Journals (Sweden)

    Lin Yanhua

    2012-02-01

    Full Text Available Abstract Background Retinal degenerations, such as age-related macular degeneration (AMD and retinitis pigmentosa (RP, are characterized by photoreceptor loss and anomalous remodeling of the surviving retina that corrupts visual processing and poses a barrier to late-stage therapeutic interventions in particular. However, the molecular events associated with retinal remodeling remain largely unknown. Given our prior evidence of ionotropic glutamate receptor (iGluR reprogramming in retinal degenerations, we hypothesized that the edited glutamate receptor 2 (GluR2 subunit and its trafficking may be modulated in retinal degenerations. Results Adult albino Balb/C mice were exposed to intense light for 24 h to induce light-induced retinal degeneration (LIRD. We found that prior to the onset of photoreceptor loss, protein levels of GluR2 and related trafficking proteins, including glutamate receptor-interacting protein 1 (GRIP1 and postsynaptic density protein 95 (PSD-95, were rapidly increased. LIRD triggered neuritogenesis in photoreceptor survival regions, where GluR2 and its trafficking proteins were expressed in the anomalous dendrites. Immunoprecipitation analysis showed interaction between KIF3A and GRIP1 as well as PSD-95, suggesting that KIF3A may mediate transport of GluR2 and its trafficking proteins to the novel dendrites. However, in areas of photoreceptor loss, GluR2 along with its trafficking proteins nearly vanished in retracted retinal neurites. Conclusions All together, LIRD rapidly triggers GluR2 plasticity, which is a potential mechanism behind functionally phenotypic revisions of retinal neurons and neuritogenesis during retinal degenerations.

  4. Translational approach for gene therapy in epilepsy

    DEFF Research Database (Denmark)

    Ledri, Litsa Nikitidou; Melin, Esbjörn; Christiansen, Søren H.

    2016-01-01

    clinical trial for gene therapy of temporal lobe epilepsy was explored: We investigated (i) whether the post intrahippocampal kainate-induced status epilepticus (SE) model of chronic epilepsy in rats could be clinically relevant; and (ii) whether a translationally designed neuropeptide Y (NPY)/Y2 receptor...

  5. Redistribution of ionotropic glutamate receptors detected by laser microdissection of the rat dentate gyrus 48 h following LTP induction in vivo.

    Directory of Open Access Journals (Sweden)

    Jeremy T T Kennard

    Full Text Available The persistence and input specificity of long-term potentiation (LTP make it attractive as a mechanism of information storage. In its initial phase, both in vivo and in vitro studies have shown that LTP is associated with increased membrane localization of AMPA receptor subunits, but the molecular basis of LTP maintenance over the long-term is still unclear. We have previously shown that expression of AMPA and NMDA receptor subunits is elevated in whole homogenates prepared from dentate gyrus 48 h after LTP induction in vivo. In the present study, we utilized laser microdissection (LMD techniques to determine whether AMPA and NMDA receptor upregulation occurs specifically in the stimulated regions of the dentate gyrus dendritic arbor. Receptor proteins GluN1, GluA1 and GluA2, as well as postsynaptic density protein of 95 kDa and tubulin were detected by Western blot analysis in microdissected samples. Gradients of expression were observed for GluN1 and GluA2, decreasing from the inner to the outer zones of the molecular layer, and were independent of LTP. When induced at medial perforant path synapses, LTP was associated with an apparent specific redistribution of GluA1 and GluN1 to the middle molecular layer that contains these synapses. These data indicate that glutamate receptor proteins are delivered specifically to dendritic regions possessing LTP-expressing synapses, and that these changes are preserved for at least 48 h.

  6. Quinazolin-4-one derivatives

    DEFF Research Database (Denmark)

    Mosley, Cara A; Acker, Timothy M; Hansen, Kasper Bø

    2010-01-01

    We describe a new class of subunit-selective antagonists of N-methyl D-aspartate (NMDA)-selective ionotropic glutamate receptors that contain the (E)-3-phenyl-2-styrylquinazolin-4(3H)-one backbone. The inhibition of recombinant NMDA receptor function induced by these quinazolin-4-one derivatives...

  7. Ionotropic NMDA and P2X1/5 receptors mediate synaptically induced Ca2+ signalling in cortical astrocytes

    Czech Academy of Sciences Publication Activity Database

    Palygin, O.; Lalo, U.; Verkhratsky, Alexei; Pankratov, Y.

    2010-01-01

    Roč. 48, č. 4 (2010), s. 225-231 ISSN 0143-4160 R&D Projects: GA ČR GA305/08/1384 Institutional research plan: CEZ:AV0Z50390703 Keywords : Astroglia * Ca2+ signalling * NMDA receptors Subject RIV: FH - Neurology Impact factor: 3.553, year: 2010

  8. 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.

  9. The distribution of excitatory amino acid receptors on acutely dissociated dorsal horn neurons from postnatal rats.

    Science.gov (United States)

    Arancio, O; Yoshimura, M; Murase, K; MacDermott, A B

    1993-01-01

    Excitatory amino acid receptor distribution was mapped on acutely dissociated neurons from postnatal rat spinal cord dorsal horn. N-methyl D-aspartate, quisqualate and kainate were applied to multiple locations along the somal and dendritic surfaces of voltage-clamped neurons by means of a pressure application system. To partially compensate for the decrement of response amplitude due to current loss between the site of activation on the dendrite and the recording electrode at the soma, a solution containing 0.15 M KCl was applied on the cell bodies and dendrites of some cells to estimate an empirical length constant. In the majority of the cells tested, the dendritic membrane had regions of higher sensitivity to excitatory amino acid agonists than the somatic membrane, with dendritic response amplitudes reaching more than seven times those at the cell body. A comparison of the relative changes in sensitivity between each combination of two of the three excitatory amino acid agonists along the same dendrite showed different patterns of agonist sensitivity along the dendrite in the majority of the cells. These data were obtained from dorsal horn neurons that had developed and formed synaptic connections in vivo. They demonstrate that in contrast to observations made on ventral horn neurons, receptor density for all the excitatory amino acid receptors on dorsal horn neurons, including the N-methyl-D-aspartate receptor, are generally higher on the dendrites than on the soma. Further, these results are similar to those obtained from dorsal horn neurons grown in culture.

  10. Integrated regulation of AMPA glutamate receptor phosphorylation in the striatum by dopamine and acetylcholine.

    Science.gov (United States)

    Xue, Bing; Chen, Elton C; He, Nan; Jin, Dao-Zhong; Mao, Li-Min; Wang, John Q

    2017-01-01

    Dopamine (DA) and acetylcholine (ACh) signals converge onto protein kinase A (PKA) in medium spiny neurons of the striatum to control cellular and synaptic activities of these neurons, although underlying molecular mechanisms are less clear. Here we measured phosphorylation of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) at a PKA site (S845) as an indicator of AMPAR responses in adult rat brains in vivo to explore how DA and ACh interact to modulate AMPARs. We found that subtype-selective activation of DA D1 receptors (D1Rs), D2 receptors (D2Rs), or muscarinic M4 receptors (M4Rs) induced specific patterns of GluA1 S845 responses in the striatum. These defined patterns support a local multitransmitter interaction model in which D2Rs inhibited an intrinsic inhibitory element mediated by M4Rs to enhance the D1R efficacy in modulating AMPARs. Consistent with this, selective enhancement of M4R activity by a positive allosteric modulator resumed the cholinergic inhibition of D1Rs. In addition, D1R and D2R coactivation recruited GluA1 and PKA preferentially to extrasynaptic sites. In sum, our in vivo data support an existence of a dynamic DA-ACh balance in the striatum which actively modulates GluA1 AMPAR phosphorylation and trafficking. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. 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

  12. Changes in calcium and iron levels in the brains of rats during kainate induced epilepsy

    Science.gov (United States)

    Ren, Min-Qin; Ong, Wei-Yi; Makjanic, Jagoda; Watt, Frank

    1999-10-01

    Epilepsy is a recurrent disorder of cerebral function characterised by sudden brief attacks of altered consciousness, motor activity or sensory phenomena, and affects approximately 1% of the population. Kainic acid injection induces neuronal degeneration in rats, is associated with glial hypertrophy and proliferation in the CA3-CA4 fields of hippocampal complex, and is a model for temporal lobe epilepsy. In this study we have applied Nuclear Microscopy to the investigation of the elemental changes within the hippocampus and the cortex areas of the rat brain following kainate injection. Analyses of unstained freeze dried tissue sections taken at 1 day and 1, 2, 3 and 4 weeks following injection were carried out using the Nuclear Microscopy facility at the Research Centre for Nuclear Microscopy, National University of Singapore. Quantitative analysis and elemental mapping indicates that there are significant changes in the calcium levels and distributions in the hippocampus as early as 1 day following injection. Preliminary results indicate a rapid increase in cellular calcium. High levels of calcium can activate calcium dependent proteins and phospholipases. Activation of phospholipase A 2 can be harmful to surrounding neurons through free radical damage. In addition to observed increases in calcium, there was evidence of increases in iron levels. This is consistent with measurements in other degenerative brain disorders, and may signal a late surge in free radical production.

  13. Changes in calcium and iron levels in the brains of rats during kainate induced epilepsy

    International Nuclear Information System (INIS)

    Ren, M.-Q.; Ong, W.-Y.; Makjanic, Jagoda; Watt, Frank

    1999-01-01

    Epilepsy is a recurrent disorder of cerebral function characterised by sudden brief attacks of altered consciousness, motor activity or sensory phenomena, and affects approximately 1% of the population. Kainic acid injection induces neuronal degeneration in rats, is associated with glial hypertrophy and proliferation in the CA3-CA4 fields of hippocampal complex, and is a model for temporal lobe epilepsy. In this study we have applied Nuclear Microscopy to the investigation of the elemental changes within the hippocampus and the cortex areas of the rat brain following kainate injection. Analyses of unstained freeze dried tissue sections taken at 1 day and 1, 2, 3 and 4 weeks following injection were carried out using the Nuclear Microscopy facility at the Research Centre for Nuclear Microscopy, National University of Singapore. Quantitative analysis and elemental mapping indicates that there are significant changes in the calcium levels and distributions in the hippocampus as early as 1 day following injection. Preliminary results indicate a rapid increase in cellular calcium. High levels of calcium can activate calcium dependent proteins and phospholipases. Activation of phospholipase A 2 can be harmful to surrounding neurons through free radical damage. In addition to observed increases in calcium, there was evidence of increases in iron levels. This is consistent with measurements in other degenerative brain disorders, and may signal a late surge in free radical production

  14. Role of the NMDA receptor and iron on free radical production and brain damage following transient middle cerebral artery occlusion.

    Science.gov (United States)

    Im, Doo Soon; Jeon, Jeong Wook; Lee, Jin Soo; Won, Seok Joon; Cho, Sung Ig; Lee, Yong Beom; Gwag, Byoung Joo

    2012-05-21

    Excess activation of ionotropic glutamate receptors and iron is believed to contribute to free radical production and neuronal death following hypoxic ischemia. We examined the possibility that both NMDA receptor activation and iron overload determine spatial and temporal patterns of free radical production after transient middle cerebral artery occlusion (tMCAO) in male Sprague-Dawley rats. Mitochondrial free radical (MFR) levels were maximally increased in neurons in the core at 1 h and 24 h after tMCAO. Early MFR production was blocked by administration of MK-801, an NMDA receptor antagonist, but not deferoxamine, an iron chelator. Neither MK-801 nor deferoxamine attenuated late MFR production in the core. Increased MFRs were observed in penumbral neurons within 6 h and gradually increased over 24 h after tMCAO. Slowly-evolving MFRs in the core and penumbra were accompanied by iron overload. Deferoxamine blocked iron overload but reduced MFR production only in the penumbra. Combined MK-801/deferoxamine reduced late MFR production in both core and penumbra in an additive manner. Combination therapy significantly ameliorated infarction compared with monotherapy. These findings suggest that the NMDA receptor activation and iron overload mediate late MFR production and infarction after tMCAO. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Ipsilateral feeding-specific circuits between the nucleus accumbens shell and the lateral hypothalamus: regulation by glutamate and GABA receptor subtypes.

    Science.gov (United States)

    Urstadt, Kevin R; Kally, Peter; Zaidi, Sana F; Stanley, B Glenn

    2013-04-01

    The nucleus accumbens shell (AcbSh) and the lateral hypothalamus (LH) are both involved in the control of food intake. Activation of GABA(A) receptors or blockade of AMPA and kainate receptors within the AcbSh induces feeding, as does blockade of GABA(A) receptors or activation of NMDA receptors in the LH. Further, evidence suggests that feeding induced via the AcbSh can be suppressed by LH inhibition. However, it is unclear if this suppression is specific to feeding. Adult male Sprague-Dawley rats with 3 intracranial guide cannulas, one unilaterally into the AcbSh and two bilaterally into the LH, were used to explore this issue. DNQX (1.25 μg) or muscimol (100 ng) infused into the AcbSh unilaterally elicited feeding, and this elicited intake was suppressed by bilateral LH injection of d-AP5 (2 μg) or muscimol (25 ng). The effectiveness of d-AP5 or muscimol infusion into either the LH site ipsilateral or contralateral to the AcbSh injection was compared. Ipsilateral LH injection of d-AP5 or muscimol was significantly more effective than contralateral injection in suppressing food intake initiated by AcbSh injection of DNQX or muscimol. These results add to the prior evidence that inhibition of the LH through pharmacological modulation of NMDA or GABA(A) receptors specifically suppresses feeding initiated by AcbSh inhibition, and that these two regions communicate via an ipsilateral circuit to specifically regulate feeding. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Effect of intrathecal non-NMDA EAA receptor antagonist LY293558 in rats: a new class of drugs for spinal anesthesia.

    Science.gov (United States)

    Von Bergen, Nicholas H; Subieta, Alberto; Brennan, Timothy J

    2002-07-01

    Excitatory amino acid receptors are important for both sensory and motor function in the spinal cord. We studied the effects of intrathecal LY293558, a competitive non-N-methyl-D-aspartate excitatory amino acid receptor antagonist, on motor and sensory function in rats to determine whether drugs blocking these receptors could potentially be used as alternative agents to local anesthetics for spinal anesthesia. Rats were tested before and 15-240 min after intrathecal injection of 5 nmol (in 10 microl) LY293558. Sensory function was tested at the hind paw using withdrawal response to pin prick and withdrawal to pinch with sharp forceps. Motor performance (ambulation, placing reflex, and Rotorod time), blood pressure, and heart rate were also evaluated. Some tests were repeated the next day. Responses after LY293558 were compared to injection of 40 microl bupivacaine, 0.75%. Pin-prick responses at the forepaw, chest, abdomen, hind leg, and hind paw were also examined after intrathecal LY293558. Intrathecal LY293558 blocked both sensory and motor responses through 180 min; complete recovery was present the following day. No change in blood pressure or heart rate occurred. The effects of LY293558 were more pronounced and sustained than those of bupivacaine. Segmental blockade of the response to pin prick was present after LY293558. Drugs like LY293558 that block alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA)/kainate receptors may be an alternative to local anesthetics for spinal anesthesia in humans.

  17. Overexpressed Calponin3 by Subsonic Vibration Induces Neural Differentiation of hUC-MSCs by Regulating the Ionotropic Glutamate Receptor.

    Science.gov (United States)

    Kim, Hyun-Jung; Kim, Jin-Hee; Song, Yeo-Ju; Seo, Young-Kwon; Park, Jung-Keug; Kim, Chan-Wha

    2015-09-01

    In this study, we used proteomics to investigate the effects of sonic vibration (SV) on mesenchymal stem cells derived from human umbilical cords (hUC-MSCs) during neural differentiation to understand how SV enhances neural differentiation of hUC-MSCs. We investigated the levels of gene and protein related to neural differentiation after 3 or 5 days in a group treated with 40-Hz SV. In addition, protein expression patterns were compared between the control and the 40-Hz SV-treated hUC-MSC groups via a proteomic approach. Among these proteins, calponin3 (CNN3) was confirmed to have 299 % higher expression in the 40-Hz SV stimulated hUC-MSCs group than that in the control by Western blotting. Notably, overexpression of CNN3-GFP in Chinese hamster ovary (CHO)-K1 cells had positive effects on the stability and reorganization of F-actin compared with that in GFP-transfected cells. Moreover, CNN3 changed the morphology of the cells by making a neurite-like form. After being subjected to SV, messenger RNA (mRNA) levels of glutamate receptors such as PSD95, GluR1, and NR1 as well as intracellular calcium levels were upregulated. These results suggest that the activity of glutamate receptors increased because of CNN3 characteristics. Taken together, these results demonstrate that overexpressed CNN3 during SV increases expression of glutamate receptors and promotes functional neural differentiation of hUC-MSCs.

  18. Transmitter receptors reveal segregation of the arcopallium/amygdala complex in pigeons (Columba livia).

    Science.gov (United States)

    Herold, Christina; Paulitschek, Christina; Palomero-Gallagher, Nicola; Güntürkün, Onur; Zilles, Karl

    2018-02-15

    At the beginning of the 20th century it was suggested that a complex group of nuclei in the avian posterior ventral telencephalon is comparable to the mammalian amygdala. Subsequent findings, however, revealed that most of these structures share premotor characteristics, while some indeed constitute the avian amygdala. These developments resulted in 2004 in a change of nomenclature of these nuclei, which from then on were named arcopallial or amygdala nuclei and referred to as the arcopallium/amygdala complex. The structural basis for the similarities between avian and mammalian arcopallial and amygdala subregions is poorly understood. Therefore, we analyzed binding site densities for glutamatergic AMPA, NMDA and kainate, GABAergic GABA A , muscarinic M 1 , M 2 and nicotinic acetylcholine (nACh; α 4 β 2 subtype), noradrenergic α 1 and α 2 , serotonergic 5-HT 1A and dopaminergic D 1/5 receptors using quantitative in vitro receptor autoradiography combined with a detailed analysis of the cyto- and myelo-architecture. Our approach supports a segregation of the pigeon's arcopallium/amygdala complex into the following subregions: the arcopallium anterius (AA), the arcopallium ventrale (AV), the arcopallium dorsale (AD), the arcopallium intermedium (AI), the arcopallium mediale (AM), the arcopallium posterius (AP), the nucleus posterioris amygdalopallii pars basalis (PoAb) and pars compacta (PoAc), the nucleus taeniae amgygdalae (TnA) and the area subpallialis amygdalae (SpA). Some of these subregions showed further subnuclei and each region of the arcopallium/amygdala complex are characterized by a distinct multi-receptor density expression. Here we provide a new detailed map of the pigeon's arcopallium/amygdala complex and compare the receptor architecture of the subregions to their possible mammalian counterparts. © 2017 Wiley Periodicals, Inc.

  19. P2X4: A fast and sensitive purinergic receptor

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    Jaanus Suurväli

    2017-10-01

    Full Text Available Extracellular nucleotides have been recognized as important mediators of activation, triggering multiple responses via plasma membrane receptors known as P2 receptors. P2 receptors comprise P2X ionotropic receptors and G protein-coupled P2Y receptors. P2X receptors are expressed in many tissues, where they are involved in a number of functions including synaptic transmission, muscle contraction, platelet aggregation, inflammation, macrophage activation, differentiation and proliferation, neuropathic and inflammatory pain. P2X4 is one of the most sensitive purinergic receptors (at nanomolar ATP concentrations, about one thousand times more than the archetypal P2X7. P2X4 is widely expressed in central and peripheral neurons, in microglia, and also found in various epithelial tissues and endothelial cells. It localizes on the plasma membrane, but also in intracellular compartments. P2X4 is preferentially localized in lysosomes, where it is protected from proteolysis by its glycosylation. High ATP concentration in the lysosomes does not activate P2X4 at low pH; P2X4 gets activated by intra-lysosomal ATP only in its fully dissociated tetra-anionic form, when the pH increases to 7.4. Thus, P2X4 is functioning as a Ca2+-channel after the fusion of late endosomes and lysosomes. P2X4 modulates major neurotransmitter systems and regulates alcohol-induced responses in microglia. P2X4 is one of the key receptors mediating neuropathic pain. However, injury-induced upregulation of P2X4 expression is gender dependent and plays a key role in pain difference between males and females. P2X4 is also involved in inflammation. Extracellular ATP being a pro-inflammatory molecule, P2X4 can trigger inflammation in response to high ATP release. It is therefore involved in multiple pathologies, like post-ischemic inflammation, rheumatoid arthritis, airways inflammation in asthma, neurodegenerative diseases and even metabolic syndrome. Although P2X4 remains poorly

  20. Mutual enhancement of central neurotoxicity induced by ketamine followed by methamphetamine

    International Nuclear Information System (INIS)

    Ke, J.-J.; Chen, H.-I.; Jen, C.J.; Kuo, Y.-M.; Cherng, C.G.; Tsai, Y.-P.N.; Ho, M.-C.; Tsai, C.-W.; Lung Yu

    2008-01-01

    We hereby report that repeated administration of ketamine (350 mg/kg in total) and methamphetamine (30 mg/kg in total) causes specific glutamatergic and dopaminergic neuron deficits, respectively, in adult mouse brain. Acute ketamine did not affect basal body temperature or the later methamphetamine-induced hyperthermia. However, pretreatment with repeated doses of ketamine aggravated methamphetamine-induced dopaminergic terminal loss as evidenced by a drastic decrease in the levels of dopamine, 3,4-dihydroxyphenylacetic acid, and dopamine transporter density as well as poor gait balance performance. In contrast, methamphetamine-induced serotonergic depletion was not altered by ketamine pretreatment. Likewise, the subsequent treatment with methamphetamine exacerbated the ketamine-induced glutamatergic damage as indicated by reduced levels of the vesicular glutamate transporter in hippocampus and striatum and poor memory performance in the Morris water maze. Finally, since activation of the D1 and AMPA/kainate receptors has been known to be involved in the release of glutamate and dopamine, we examined the effects of co-administration of SCH23390, a D1 antagonist, and CNQX, an AMPA/kainate antagonist. Intraventricular CNQX infusion abolished ketamine's potentiation of methamphetamine-induced dopamine neurotoxicity, while systemic SCH23390 mitigated methamphetamine's potentiation of ketamine-induced glutamatergic toxicity. We conclude that repeated doses of ketamine potentiate methamphetamine-induced dopamine neurotoxicity via AMPA/kainate activation and that conjunctive use of methamphetamine aggravates ketamine-induced glutamatergic neurotoxicity possibly via D1 receptor activation

  1. Effects of NR1 splicing on NR1/NR3B-type excitatory glycine receptors

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    Orth Angela

    2009-04-01

    Full Text Available Abstract Background N-methyl-D-aspartate receptors (NMDARs are the most complex of ionotropic glutamate receptors (iGluRs. Subunits of this subfamily assemble into heteromers, which – depending on the subunit combination – may display very different pharmacological and electrophysiological properties. The least studied members of the NMDAR family, the NR3 subunits, have been reported to assemble with NR1 to form excitatory glycine receptors in heterologous expression systems. The heterogeneity of NMDARs in vivo is in part conferred to the receptors by splicing of the NR1 subunit, especially with regard to proton sensitivity. Results Here, we have investigated whether the NR3B subunit is capable of assembly with each of the eight functional NR1 splice variants, and whether the resulting receptors share the unique functional properties described for NR1-1a/NR3. We provide evidence that functional excitatory glycine receptors formed regardless of the NR1 isoform, and their pharmacological profile matched the one reported for NR1-1a/NR3: glycine alone fully activated the receptors, which were insensitive to glutamate and block by Mg2+. Surprisingly, amplitudes of agonist-induced currents showed little dependency on the C-terminally spliced NR1 variants in NR1/NR3B diheteromers. Even more strikingly, NR3B conferred proton sensitivity also to receptors containing NR1b variants – possibly via disturbing the "proton shield" of NR1b splice variants. Conclusion While functional assembly could be demonstrated for all combinations, not all of the specific interactions seen for NR1 isoforms with coexpressed NR2 subunits could be corroborated for NR1 assembly with NR3. Rather, NR3 abates trafficking effects mediated by the NR1 C terminus as well as the N-terminally mediated proton insensitivity. Thus, this study establishes that NR3B overrides important NR1 splice variant-specific receptor properties in NR1/NR3B excitatory glycine receptors.

  2. Muscarinic receptors modulate dendrodendritic inhibitory synapses to sculpt glomerular output.

    Science.gov (United States)

    Liu, Shaolin; Shao, Zuoyi; Puche, Adam; Wachowiak, Matt; Rothermel, Markus; Shipley, Michael T

    2015-04-08

    Cholinergic [acetylcholine (ACh)] axons from the basal forebrain innervate olfactory bulb glomeruli, the initial site of synaptic integration in the olfactory system. Both nicotinic acetylcholine receptors (nAChRs) and muscarinic acetylcholine receptors (mAChRs) are expressed in glomeruli. The activation of nAChRs directly excites both mitral/tufted cells (MTCs) and external tufted cells (ETCs), the two major excitatory neurons that transmit glomerular output. The functional roles of mAChRs in glomerular circuits are unknown. We show that the restricted glomerular application of ACh causes rapid, brief nAChR-mediated excitation of both MTCs and ETCs in the mouse olfactory bulb. This excitation is followed by mAChR-mediated inhibition, which is blocked by GABAA receptor antagonists, indicating the engagement of periglomerular cells (PGCs) and/or short axon cells (SACs), the two major glomerular inhibitory neurons. Indeed, selective activation of glomerular mAChRs, with ionotropic GluRs and nAChRs blocked, increased IPSCs in MTCs and ETCs, indicating that mAChRs recruit glomerular inhibitory circuits. Selective activation of glomerular mAChRs in the presence of tetrodotoxin increased IPSCs in all glomerular neurons, indicating action potential-independent enhancement of GABA release from PGC and/or SAC dendrodendritic synapses. mAChR-mediated enhancement of GABA release also presynaptically suppressed the first synapse of the olfactory system via GABAB receptors on sensory terminals. Together, these results indicate that cholinergic modulation of glomerular circuits is biphasic, involving an initial excitation of MTC/ETCs mediated by nAChRs followed by inhibition mediated directly by mAChRs on PGCs/SACs. This may phasically enhance the sensitivity of glomerular outputs to odorants, an action that is consistent with recent in vivo findings. Copyright © 2015 the authors 0270-6474/15/355680-13$15.00/0.

  3. Negative allosteric modulation of the mGlu7 receptor reduces visceral hypersensitivity in a stress-sensitive rat strain

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    Rachel D. Moloney

    2015-01-01

    Full Text Available Glutamate, the main excitatory neurotransmitter in the central nervous system, exerts its effect through ionotropic and metabotropic receptors. Of these, group III mGlu receptors (mGlu 4, 6, 7, 8 are among the least studied due to a lack of pharmacological tools. mGlu7 receptors, the most highly conserved isoform, are abundantly distributed in the brain, especially in regions, such as the amygdala, known to be crucial for the emotional processing of painful stimuli. Visceral hypersensitivity is a poorly understood phenomenon manifesting as an increased sensitivity to visceral stimuli. Glutamate has long been associated with somatic pain processing leading us to postulate that crossover may exist between these two modalities. Moreover, stress has been shown to exacerbate visceral pain. ADX71743 is a novel, centrally penetrant, negative allosteric modulator of mGlu7 receptors. Thus, we used this tool to explore the possible involvement of this receptor in the mediation of visceral pain in a stress-sensitive model of visceral hypersensitivity, namely the Wistar Kyoto (WKY rat. ADX71743 reduced visceral hypersensitivity in the WKY rat as exhibited by increased visceral sensitivity threshold with concomitant reductions in total number of pain behaviours. Moreover, AD71743 increased total distance and distance travelled in the inner zone of the open field. These findings show, for what is to our knowledge, the first time, that mGlu7 receptor signalling plays a role in visceral pain processing. Thus, negative modulation of the mGlu7 receptor may be a plausible target for the amelioration of stress-induced visceral pain where there is a large unmet medical need.

  4. Effects of neonatal. gamma. -ray irradiation on rat hippocampus: Pt. 2; Development of excitatory amino acid binding sites

    Energy Technology Data Exchange (ETDEWEB)

    Dessi, F; Represa, A; Ben-Ari, Y [Institut National de la Sante et de la Recherche Medicale (INSERM), 75 - Paris (France)

    1991-01-01

    In the rat, neonatal irradiation produces a destruction of denate granule cells and prevents the development of the mossy fibre-CA3 pyramidal cell synapse. The developmental increase of high affinity kainate binding sites in the stratum lucidum was reduced on the irradiated side as compared with the control side. This suggests that a proportion of high affinity kainate binding sites is associated with mossy fibres. In contrast, the development profile of N-methyl-D-aspartate binding sites, which are associated with associational and commissural synapses in CA3, was not affected by irradiation. The role that afferent fibres may play in the development of pyramidal cells is discussed in connection with the modulatory effects of glutamate receptors on the development of neurons. (author).

  5. Endogenous GABA and Glutamate Finely Tune the Bursting of Olfactory Bulb External Tufted Cells

    Science.gov (United States)

    Hayar, Abdallah; Ennis, Matthew

    2008-01-01

    In rat olfactory bulb slices, external tufted (ET) cells spontaneously generate spike bursts. Although ET cell bursting is intrinsically generated, its strength and precise timing may be regulated by synaptic input. We tested this hypothesis by analyzing whether the burst properties are modulated by activation of ionotropic γ-aminobutyric acid (GABA) and glutamate receptors. Blocking GABAA receptors increased—whereas blocking ionotropic glutamate receptors decreased—the number of spikes/burst without changing the interburst frequency. The GABAA agonist (isoguvacine, 10 μM) completely inhibited bursting or reduced the number of spikes/burst, suggesting a shunting effect. These findings indicate that the properties of ET cell spontaneous bursting are differentially controlled by GABAergic and glutamatergic fast synaptic transmission. We suggest that ET cell excitatory and inhibitory inputs may be encoded as a change in the pattern of spike bursting in ET cells, which together with mitral/tufted cells constitute the output circuit of the olfactory bulb. PMID:17567771

  6. A DFT approach to discriminate the antagonist and partial agonist activity of ligands binding to the NMDA receptor

    Science.gov (United States)

    Haslak, Zeynep Pinar; Bozkurt, Esra; Dutagaci, Bercem; De Proft, Frank; Aviyente, Viktorya; De Vleeschouwer, Freija

    2018-02-01

    The activation of N-methyl-D-aspartate receptors is found to be intimately associated with neurodegenerative diseases which make them promising therapeutic targets. Despite the significantly increasing multidisciplinary interests centred on this ionotropic channel, design of new ligands with intended functional activity remains a great challenge. In this article, a computational study based on density functional theory is presented to understand the structural factors of ligands determining their function as antagonists and partial agonists. With this aim, the GluN1 subunit is chosen as being one of the essential components in the activation mechanism, and quantum chemical calculations are implemented for 30 antagonists and 30 partial agonists known to bind to this subunit with different binding affinities. Several quantum chemical descriptors are investigated which might unlock the difference between antagonists and partial agonists.

  7. Activation of NMDA receptor by elevated homocysteine in chronic liver disease contributes to encephalopathy.

    Science.gov (United States)

    Choudhury, Sabanum; Borah, Anupom

    2015-07-01

    Liver diseases lead to a complex syndrome characterized by neurological, neuro-psychiatric and motor complications, called hepatic encephalopathy, which is prevalent in patients and animal models of acute, sub-chronic and chronic liver failure. Although alterations in GABAergic, glutamatergic, cholinergic and serotonergic neuronal functions have been implicated in HE, the molecular mechanisms that lead to HE in chronic liver disease (CLD) is least illustrated. Due to hepatocellular failure, levels of ammonia and homocysteine (Hcy), in addition to others, are found to increase in the brain as well as plasma. Hcy, a non-protein forming amino acid and an excitotoxin, activates ionotropic glutamate (n-methyl-d-aspartate; NMDA) receptors, and thereby leads to influx of Ca(2+) into neurons, which in turn activates several pathways that trigger oxidative stress, inflammation and apoptosis, collectively called excitotoxicity. Elevated levels of Hcy in the plasma and brain, a condition called Hyperhomocysteinemia (HHcy), and the resultant NMDA receptor-mediated excitotoxicity has been implicated in several diseases, including Parkinson's disease and Alzheimer's disease. Although, hyperammonemia has been shown to cause excitotoxicity, the role of HHcy in the development of behavioral and neurochemical alterations that occur in HE has not been illustrated yet. It is hypothesized that CLD-induced HHcy plays a major role in the development of HE through activation of NMDA receptors. It is further hypothesized that HHcy synergizes with hyperammonemia to activate NMDA receptor in the brain, and thereby cause oxidative stress, inflammation and apoptosis, and neuronal loss that leads to HE. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Sniffer patch laser uncaging response (SPLURgE): an assay of regional differences in allosteric receptor modulation and neurotransmitter clearance.

    Science.gov (United States)

    Christian, Catherine A; Huguenard, John R

    2013-10-01

    Allosteric modulators exert actions on neurotransmitter receptors by positively or negatively altering the effective response of these receptors to their respective neurotransmitter. γ-Aminobutyric acid (GABA) type A ionotropic receptors (GABAARs) are major targets for allosteric modulators such as benzodiazepines, neurosteroids, and barbiturates. Analysis of substances that produce similar effects has been hampered by the lack of techniques to assess the localization and function of such agents in brain slices. Here we describe measurement of the sniffer patch laser uncaging response (SPLURgE), which combines the sniffer patch recording configuration with laser photolysis of caged GABA. This methodology enables the detection of allosteric GABAAR modulators endogenously present in discrete areas of the brain slice and allows for the application of exogenous GABA with spatiotemporal control without altering the release and localization of endogenous modulators within the slice. Here we demonstrate the development and use of this technique for the measurement of allosteric modulation in different areas of the thalamus. Application of this technique will be useful in determining whether a lack of modulatory effect on a particular category of neurons or receptors is due to insensitivity to allosteric modulation or a lack of local release of endogenous ligand. We also demonstrate that this technique can be used to investigate GABA diffusion and uptake. This method thus provides a biosensor assay for rapid detection of endogenous GABAAR modulators and has the potential to aid studies of allosteric modulators that exert effects on other classes of neurotransmitter receptors, such as glutamate, acetylcholine, or glycine receptors.

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

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    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. Rapid evolution of chemosensory receptor genes in a pair of sibling species of orchid bees (Apidae: Euglossini).

    Science.gov (United States)

    Brand, Philipp; Ramírez, Santiago R; Leese, Florian; Quezada-Euan, J Javier G; Tollrian, Ralph; Eltz, Thomas

    2015-08-28

    Insects rely more on chemical signals (semiochemicals) than on any other sensory modality to find, identify, and choose mates. In most insects, pheromone production is typically regulated through biosynthetic pathways, whereas pheromone sensory detection is controlled by the olfactory system. Orchid bees are exceptional in that their semiochemicals are not produced metabolically, but instead male bees collect odoriferous compounds (perfumes) from the environment and store them in specialized hind-leg pockets to subsequently expose during courtship display. Thus, the olfactory sensory system of orchid bees simultaneously controls male perfume traits (sender components) and female preferences (receiver components). This functional linkage increases the opportunities for parallel evolution of male traits and female preferences, particularly in response to genetic changes of chemosensory detection (e.g. Odorant Receptor genes). To identify whether shifts in pheromone composition among related lineages of orchid bees are associated with divergence in chemosensory genes of the olfactory periphery, we searched for patterns of divergent selection across the antennal transcriptomes of two recently diverged sibling species Euglossa dilemma and E. viridissima. We identified 3185 orthologous genes including 94 chemosensory loci from five different gene families (Odorant Receptors, Ionotropic Receptors, Gustatory Receptors, Odorant Binding Proteins, and Chemosensory Proteins). Our results revealed that orthologs with signatures of divergent selection between E. dilemma and E. viridissima were significantly enriched for chemosensory genes. Notably, elevated signals of divergent selection were almost exclusively observed among chemosensory receptors (i.e. Odorant Receptors). Our results suggest that rapid changes in the chemosensory gene family occurred among closely related species of orchid bees. These findings are consistent with the hypothesis that strong divergent selection

  11. 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.

  12. Post-translational regulation of P2X receptor channels: modulation by phospholipids

    Directory of Open Access Journals (Sweden)

    Louis-Philippe eBernier

    2013-11-01

    Full Text Available P2X receptor channels mediate fast excitatory signaling by ATP and play major roles in sensory transduction, neuro-immune communication and inflammatory response. P2X receptors constitute a gene family of calcium-permeable ATP-gated cation channels therefore the regulation of P2X signaling is critical for both membrane potential and intracellular calcium homeostasis. Phosphoinositides (PIPn are anionic signaling phospholipids that act as functional regulators of many types of ion channels. Direct PIPn binding was demonstrated for several ligand- or voltage-gated ion channels, however no generic motif emerged to accurately predict lipid-protein binding sites. This review presents what is currently known about the modulation of the different P2X subtypes by phospholipids and about critical determinants underlying their sensitivity to PIPn levels in the plasma membrane.All functional mammalian P2X subtypes tested, with the notable exception of P2X5, have been shown to be positively modulated by PIPn, i.e. homomeric P2X1, P2X2, P2X3, P2X4, and P2X7, as well as heteromeric P2X1/5 and P2X2/3 receptors. Based on various results reported on the aforementioned subtypes including mutagenesis of the prototypical PIPn-sensitive P2X4 and PIPn-insensitive P2X5 receptor subtypes, an increasing amount of functional, biochemical and structural evidence converges on the modulatory role of a short polybasic domain located in the proximal C-terminus of P2X subunits. This linear motif, semi-conserved in the P2X family, seems necessary and sufficient for encoding direct modulation of ATP-gated channels by PIPn. Furthermore, the physiological impact of the regulation of ionotropic purinergic responses by phospholipids on pain pathways was recently revealed in the context of native crosstalks between phospholipase C-linked metabotropic receptors and P2X receptor channels in DRG sensory neurons and microglia.

  13. Glutamate may be an efferent transmitter that elicits inhibition in mouse taste buds.

    Directory of Open Access Journals (Sweden)

    Yijen A Huang

    Full Text Available Recent studies suggest that l-glutamate may be an efferent transmitter released from axons innervating taste buds. In this report, we determined the types of ionotropic synaptic glutamate receptors present on taste cells and that underlie this postulated efferent transmission. We also studied what effect glutamate exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura 2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings show that a large fraction of Presynaptic (Type III taste bud cells (∼50% respond to 100 µM glutamate, NMDA, or kainic acid (KA with an increase in intracellular Ca(2+. In contrast, Receptor (Type II taste cells rarely (4% responded to 100 µM glutamate. At this concentration and with these compounds, these agonists activate glutamatergic synaptic receptors, not glutamate taste (umami receptors. Moreover, applying glutamate, NMDA, or KA caused taste buds to secrete 5-HT, a Presynaptic taste cell transmitter, but not ATP, a Receptor cell transmitter. Indeed, glutamate-evoked 5-HT release inhibited taste-evoked ATP secretion. The findings are consistent with a role for glutamate in taste buds as an inhibitory efferent transmitter that acts via ionotropic synaptic glutamate receptors.

  14. Glutamate may be an efferent transmitter that elicits inhibition in mouse taste buds.

    Science.gov (United States)

    Huang, Yijen A; Grant, Jeff; Roper, Stephen

    2012-01-01

    Recent studies suggest that l-glutamate may be an efferent transmitter released from axons innervating taste buds. In this report, we determined the types of ionotropic synaptic glutamate receptors present on taste cells and that underlie this postulated efferent transmission. We also studied what effect glutamate exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura 2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings show that a large fraction of Presynaptic (Type III) taste bud cells (∼50%) respond to 100 µM glutamate, NMDA, or kainic acid (KA) with an increase in intracellular Ca(2+). In contrast, Receptor (Type II) taste cells rarely (4%) responded to 100 µM glutamate. At this concentration and with these compounds, these agonists activate glutamatergic synaptic receptors, not glutamate taste (umami) receptors. Moreover, applying glutamate, NMDA, or KA caused taste buds to secrete 5-HT, a Presynaptic taste cell transmitter, but not ATP, a Receptor cell transmitter. Indeed, glutamate-evoked 5-HT release inhibited taste-evoked ATP secretion. The findings are consistent with a role for glutamate in taste buds as an inhibitory efferent transmitter that acts via ionotropic synaptic glutamate receptors.

  15. Serotonergic transmission at Merkel discs: modulation by exogenously applied chemical messengers and involvement of Ih currents.

    Science.gov (United States)

    Chang, Weipang; Kanda, Hirosato; Ikeda, Ryo; Ling, Jennifer; Gu, Jianguo G

    2017-05-01

    The Merkel disc is a main type of tactile end organ consisting of Merkel cells and Aβ-afferent endings that responds to tactile stimulation with slowly adapting type 1 (SA1) afferent impulses. Our recent study has shown that Merkel discs in whisker hair follicles are serotonergic synapses using endogenous serotonin to transmit tactile signals from Merkel cells to Aβ-afferent endings. In this study, we hypothesize that tactile sensitivity of Merkel discs can be modulated by chemical messengers. We tested this hypothesis by determining whether and how SA1 responses of mouse whisker hair follicles may be affected by exogenously applied chemical messengers. We found that SA1 responses were potentiated by serotonin at low concentration (10 μM) but almost completely occluded by serotonin at high concentration (2 mM). In contrast, SA1 responses were not significantly affected by ATP and its metabolically stable analog α,β-methylene-ATP, glutamate, γ-aminobutyric acid (GABA), and histamine. SA1 responses were also not affected by antagonists for P2X receptors, ionotropic glutamate receptors, and ionotropic GABA and glycine receptors. Whole-cell patch-clamp recordings reconfirm the presence of both ionotropic and metabotropic 5-HT receptors on afferent neurons and their terminals innervating whisker hair follicles. All whisker afferent neurons expressed hyperpolarization-activated inward currents (I h ), which are potentiated by serotonin through the activation of metabotropic 5-HT receptors. Taken together, the findings substantiate the serotonergic mechanism of tactile transmission at Merkel discs and identify the involvement of I h currents in postsynaptic excitatory actions of serotonin. In addition, the findings do not favor any significant involvement of ATP, glutamate, histamine, GABA, or glycine in tactile transmission at the Merkel discs of whisker hair follicles. © 2017 International Society for Neurochemistry.

  16. Synthesis and enantiopharmacology of new AMPA-kainate receptor agonists

    DEFF Research Database (Denmark)

    Conti, P; De Amici, M; De Sarro, G

    1999-01-01

    . The convulsant properties of all the compounds were evaluated in vivo on DBA/2 mice after icv injection. CIP-A showed a convulsant activity, measured as tonus and clonus seizures, 18-65 times higher than that produced by AMPA. It was also quite active after ip administration, since it induced seizures in mice...... at doses as low as 3.2 nmol/mouse. On the basis of the above-reported results we prepared and tested the enantiomers of CIP-A and CIP-B, obtained by reacting (S)-3,4-didehydroproline and (R)-3,4-didehydroproline, respectively, with ethoxycarbonylformonitrile oxide. In all the tests the S-form, CIP...

  17. Neto2 influences on kainate receptor pharmacology and function

    DEFF Research Database (Denmark)

    Han, Liwei; Howe, James; Pickering, Darryl S

    2016-01-01

    the mechanism of Neto2 modulation is still unclear, gain-of-function results from the characterization of GluK1-GluA2 chimeras indicate that the GluK1 sequences included in these chimeras (part or all of the TMD and part of the linkers between the TMDs and LBD) play a key role in Neto2 modulation of KAR...

  18. Role of P2 Receptors as Modulators of Rat Eosinophil Recruitment in Allergic Inflammation.

    Directory of Open Access Journals (Sweden)

    Anael Viana Pinto Alberto

    Full Text Available ATP and other nucleotides are released from cells through regulated pathways or following the loss of plasma membrane integrity. Once outside the cell, these compounds can activate P2 receptors: P2X ionotropic receptors and G protein-coupled P2Y receptors. Eosinophils represent major effector cells in the allergic inflammatory response and they are, in fact, associated with several physiological and pathological processes. Here we investigate the expression of P2 receptors and roles of those receptors in murine eosinophils. In this context, our first step was to investigate the expression and functionality of the P2X receptors by patch clamping, our results showed a potency ranking order of ATP>ATPγS> 2meSATP> ADP> αβmeATP> βγmeATP>BzATP> UTP> UDP>cAMP. This data suggest the presence of P2X1, P2X2 and P2X7. Next we evaluate by microfluorimetry the expression of P2Y receptors, our results based in the ranking order of potency (UTP>ATPγS> ATP > UDP> ADP >2meSATP > αβmeATP suggests the presence of P2Y2, P2Y4, P2Y6 and P2Y11. Moreover, we confirmed our findings by immunofluorescence assays. We also did chemotaxis assays to verify whether nucleotides could induce migration. After 1 or 2 hours of incubation, ATP increased migration of eosinophils, as well as ATPγS, a less hydrolysable analogue of ATP, while suramin a P2 blocker abolished migration. In keeping with this idea, we tested whether these receptors are implicated in the migration of eosinophils to an inflammation site in vivo, using a model of rat allergic pleurisy. In fact, migration of eosinophils has increased when ATP or ATPγS were applied in the pleural cavity, and once more suramin blocked this effect. We have demonstrated that rat eosinophils express P2X and P2Y receptors. In addition, the activation of P2 receptors can increase migration of eosinophils in vitro and in vivo, an effect blocked by suramin.

  19. Serotonin receptor 3A controls interneuron migration into the neocortex

    NARCIS (Netherlands)

    Murthy, S.; Niquille, M.; Hurni, N.; Limoni, G.; Frazer, S.; Chameau, P.; van Hooft, J.A.; Vitalis, T.; Dayer, A.

    2014-01-01

    Neuronal excitability has been shown to control the migration and cortical integration of reelin-expressing cortical interneurons (INs) arising from the caudal ganglionic eminence (CGE), supporting the possibility that neurotransmitters could regulate this process. Here we show that the ionotropic

  20. Potentiation of NMDA receptor-dependent cell responses by extracellular high mobility group box 1 protein.

    Directory of Open Access Journals (Sweden)

    Marco Pedrazzi

    Full Text Available BACKGROUND: Extracellular high mobility group box 1 (HMGB1 protein can operate in a synergistic fashion with different signal molecules promoting an increase of cell Ca(2+ influx. However, the mechanisms responsible for this effect of HMGB1 are still unknown. PRINCIPAL FINDINGS: Here we demonstrate that, at concentrations of agonist per se ineffective, HMGB1 potentiates the activation of the ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR in isolated hippocampal nerve terminals and in a neuroblastoma cell line. This effect was abolished by the NMDA channel blocker MK-801. The HMGB1-facilitated NMDAR opening was followed by activation of the Ca(2+-dependent enzymes calpain and nitric oxide synthase in neuroblastoma cells, resulting in an increased production of NO, a consequent enhanced cell motility, and onset of morphological differentiation. We have also identified NMDAR as the mediator of HMGB1-stimulated murine erythroleukemia cell differentiation, induced by hexamethylenebisacetamide. The potentiation of NMDAR activation involved a peptide of HMGB1 located in the B box at the amino acids 130-139. This HMGB1 fragment did not overlap with binding sites for other cell surface receptors of HMGB1, such as the advanced glycation end products or the Toll-like receptor 4. Moreover, in a competition assay, the HMGB1((130-139 peptide displaced the NMDAR/HMGB1 interaction, suggesting that it comprised the molecular and functional site of HMGB1 regulating the NMDA receptor complex. CONCLUSION: We propose that the multifunctional cytokine-like molecule HMGB1 released by activated, stressed, and damaged or necrotic cells can facilitate NMDAR-mediated cell responses, both in the central nervous system and in peripheral tissues, independently of other known cell surface receptors for HMGB1.

  1. Differential projections of the densocellular and intermediate parts of the hyperpallium in the pigeon (Columba livia).

    Science.gov (United States)

    Atoji, Yasuro; Sarkar, Sonjoy; Wild, J Martin

    2018-01-01

    The visual Wulst in birds shows a four-layered structure: apical part of the hyperpallium (HA), interstitial part of HA (IHA), intercalated part of hyperpallium (HI), and densocellular part of hyperpallium (HD). HD also connects with the hippocampus and olfactory system. Because HD is subjacent to HI, the two have been treated as one structure in many studies, and the fiber connections of HD have been examined by afferents and efferents originating outside HD. However, to clarify the difference between these two layers, they need to be treated separately. In the present study, the fiber connections of HD and HI were analyzed with tract-tracing techniques using a combination of injections of cholera toxin subunit B (CTB) for retrograde tracing and biotinylated dextran amine (BDA) for anterograde tracing. When the two tracers were bilaterally injected in HD, a major reciprocal connection was seen with the dorsolateral subdivision (DL) of the hippocampal formation. When CTB and BDA were bilaterally injected in HI, strong reciprocal connections were found between HI and HA. Next, projection neurons in HD and HI were examined by double staining for CTB combined with vesicular glutamate transporter 2 (vGluT2) mRNA in situ hybridization. After CTB was injected in DL or HA, many neurons revealed CTB+/vGluT2+ in HD or HI, respectively. Furthermore, in situ hybridization showed that DL and HA contained neurons expressing various subunits of ionotropic glutamate receptors: AMPA, kainate, and NMDA types. These results suggest that glutamatergic neurons in HD and HI project primarily to DL and HA, respectively. © 2017 Wiley Periodicals, Inc.

  2. Chronic glutamate toxicity in neurodegenerative diseases-what is the evidence?

    Directory of Open Access Journals (Sweden)

    Pamela eMaher

    2015-12-01

    Full Text Available Together with aspartate, glutamate is the major excitatory neurotransmitter in the brain. Glutamate binds and activates both ligand-gated ion channels (ionotropic glutamate receptors and a class of G-protein coupled receptors (metabotropic glutamate receptors. Although the intracellular glutamate concentration in the brain is in the millimolar range, the extracellular glutamate concentration is kept in the low micromolar range by the action of excitatory amino acid transporters that import glutamate and aspartate into astrocytes and neurons. Excess extracellular glutamate may lead to excitotoxicity in vitro and in vivo in acute insults like ischemic stroke via the overactivation of ionotropic glutamate receptors. In addition, chronic excitotoxicity has been hypothesized to play a role in numerous neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer’s disease and Huntington’s disease. Based on this hypothesis, a good deal of effort has been devoted to develop and test drugs that either inhibit glutamate receptors or decrease extracellular glutamate. In this review, we provide an overview of the different pathways that are thought to lead to an over-activation of the glutamatergic system and glutamate toxicity in neurodegeneration. In addition, we summarize the available experimental evidence for glutamate toxicity in animal models of neurodegenerative diseases.

  3. Synthesis and anticonvulsant activity of novel bicyclic acidic amino acids

    DEFF Research Database (Denmark)

    Conti, Paola; De Amici, Marco; Joppolo Di Ventimiglia, Samuele

    2003-01-01

    Bicyclic acidic amino acids (+/-)-6 and (+/-)-7, which are conformationally constrained homologues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested toward ionotropic and metabotropic glutamate receptor subtypes; both of them...

  4. NMDA Receptor Subunits Change after Synaptic Plasticity Induction and Learning and Memory Acquisition

    Directory of Open Access Journals (Sweden)

    María Verónica Baez

    2018-01-01

    Full Text Available NMDA ionotropic glutamate receptors (NMDARs are crucial in activity-dependent synaptic changes and in learning and memory. NMDARs are composed of two GluN1 essential subunits and two regulatory subunits which define their pharmacological and physiological profile. In CNS structures involved in cognitive functions as the hippocampus and prefrontal cortex, GluN2A and GluN2B are major regulatory subunits; their expression is dynamic and tightly regulated, but little is known about specific changes after plasticity induction or memory acquisition. Data strongly suggest that following appropriate stimulation, there is a rapid increase in surface GluN2A-NMDAR at the postsynapses, attributed to lateral receptor mobilization from adjacent locations. Whenever synaptic plasticity is induced or memory is consolidated, more GluN2A-NMDARs are assembled likely using GluN2A from a local translation and GluN1 from local ER. Later on, NMDARs are mobilized from other pools, and there are de novo syntheses at the neuron soma. Changes in GluN1 or NMDAR levels induced by synaptic plasticity and by spatial memory formation seem to occur in different waves of NMDAR transport/expression/degradation, with a net increase at the postsynaptic side and a rise in expression at both the spine and neuronal soma. This review aims to put together that information and the proposed hypotheses.

  5. Phenotypic characterization of Grm1crv4 mice reveals a functional role for the type 1 metabotropic glutamate receptor in bone mineralization.

    Science.gov (United States)

    Musante, Ilaria; Mattinzoli, Deborah; Otescu, Lavinia Alexandra; Bossi, Simone; Ikehata, Masami; Gentili, Chiara; Cangemi, Giuliana; Gatti, Cinzia; Emionite, Laura; Messa, Piergiorgio; Ravazzolo, Roberto; Rastaldi, Maria Pia; Riccardi, Daniela; Puliti, Aldamaria

    2017-01-01

    Recent increasing evidence supports a role for neuronal type signaling in bone. Specifically glutamate receptors have been found in cells responsible for bone remodeling, namely the osteoblasts and the osteoclasts. While most studies have focused on ionotropic glutamate receptors, the relevance of the metabotropic glutamate signaling in bone is poorly understood. Specifically type 1 metabotropic glutamate (mGlu1) receptors are expressed in bone, but the effect of its ablation on skeletal development has never been investigated. Here we report that Grm1 crv4/crv4 mice, homozygous for an inactivating mutation of the mGlu1 receptor, and mainly characterized by ataxia and renal dysfunction, exhibit decreased body weight, bone length and bone mineral density compared to wild type (WT) animals. Blood analyses of the affected mice demonstrate the absence of changes in circulating factors, such as vitamin D and PTH, suggesting renal damage is not the main culprit of the skeletal phenotype. Cultures of osteoblasts lacking functional mGlu1 receptors exhibit less homogeneous collagen deposition than WT cells, and present increased expression of osteocalcin, a marker of osteoblast maturation. These data suggest that the skeletal damage is directly linked to the absence of the receptor, which in turn leads to osteoblasts dysfunction and earlier maturation. Accordingly, skeletal histomorphology suggests that Grm1 crv4/crv4 mice exhibit enhanced bone maturation, resulting in premature fusion of the growth plate and shortened long bones, and further slowdown of bone apposition rate compared to the WT animals. In summary, this work reveals novel functions of mGlu1 receptors in the bone and indicates that in osteoblasts mGlu1 receptors are necessary for production of normal bone matrix, longitudinal bone growth, and normal skeletal development. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Iptakalim inhibits nicotinic acetylcholine receptor-mediated currents in dopamine neurons acutely dissociated from rat substantia nigra pars compacta.

    Science.gov (United States)

    Hu, J; DeChon, J; Yan, K C; Liu, Q; Hu, G; Wu, J

    2006-07-31

    Iptakalim hydrochloride, a novel cardiovascular ATP-sensitive K(+) (K(ATP)) channel opener, has shown remarkable antihypertensive and neuroprotective effects in a variety of studies using in vivo and in vitro preparations. We recently found that iptakalim blocked human alpha4-containing nicotinic acetylcholine receptors (nAChRs) heterologously expressed in the human SH-EP1 cell line. In the present study, we examined the effects of iptakalim on several neurotransmitter-induced current responses in single DA neurons freshly dissociated from rat substantia nigra pars compacta (SNc), using perforated patch-clamp recordings combined with a U-tube rapid drug application. In identified DA neurons under voltage-clamp configuration, glutamate-, NMDA-, and GABA-induced currents were insensitive to co-application with iptakalim (100 microM), while whole-cell currents induced by ACh (1 mM+1 microM atropine) or an alpha4beta2 nicotinic acetylcholine receptors relatively selective agonist, RJR-2403 (300 microM), were eliminated by iptakalim. Iptakalim inhibited RJR-2403-induced current in a concentration-dependent manner, and reduced maximal RJR-2403-induced currents at the highest agonist concentration, suggesting a non-competitive block. In current-clamp mode, iptakalim failed to affect resting membrane potential and spontaneous action potential firing, but abolished RJR-2403-induced neuronal firing acceleration. Together, these results indicate that in dissociated SNc DA neurons, alpha4-containing nAChRs, rather than ionotropic glutamate receptors, GABA(A) receptors or perhaps K-ATP channels are the sensitive targets to mediate iptakalim's pharmacological roles.

  7. Transient receptor potential (TRP) channels as drug targets for diseases of the digestive system

    Science.gov (United States)

    Holzer, Peter

    2011-01-01

    Approximately 20 of the 30 mammalian transient receptor potential (TRP) channel subunits are expressed by specific neurons and cells within the alimentary canal. They subserve important roles in taste, chemesthesis, mechanosensation, pain and hyperalgesia and contribute to the regulation of gastrointestinal motility, absorptive and secretory processes, blood flow, and mucosal homeostasis. In a cellular perspective, TRP channels operate either as primary detectors of chemical and physical stimuli, as secondary transducers of ionotropic or metabotropic receptors, or as ion transport channels. The polymodal sensory function of TRPA1, TRPM5, TRPM8, TRPP2, TRPV1, TRPV3 and TRPV4 enables the digestive system to survey its physical and chemical environment, which is relevant to all processes of digestion. TRPV5 and TRPV6 as well as TRPM6 and TRPM7 contribute to the absorption of Ca2+ and Mg2+, respectively. TRPM7 participates in intestinal pacemaker activity, and TRPC4 transduces muscarinic acetylcholine receptor activation to smooth muscle contraction. Changes in TRP channel expression or function are associated with a variety of diseases/disorders of the digestive system, notably gastro-esophageal reflux disease, inflammatory bowel disease, pain and hyperalgesia in heartburn, functional dyspepsia and irritable bowel syndrome, cholera, hypomagnesemia with secondary hypocalcemia, infantile hypertrophic pyloric stenosis, esophageal, gastrointestinal and pancreatic cancer, and polycystic liver disease. These implications identify TRP channels as promising drug targets for the management of a number of gastrointestinal pathologies. As a result, major efforts are put into the development of selective TRP channel agonists and antagonists and the assessment of their therapeutic potential. PMID:21420431

  8. Nicotine inhibits potassium currents in Aplysia bag cell neurons

    Science.gov (United States)

    White, Sean H.; Sturgeon, Raymond M.

    2016-01-01

    Acetylcholine and the archetypal cholinergic agonist, nicotine, are typically associated with the opening of ionotropic receptors. In the bag cell neurons, which govern the reproductive behavior of the marine snail, Aplysia californica, there are two cholinergic responses: a relatively large acetylcholine-induced current and a relatively small nicotine-induced current. Both currents are readily apparent at resting membrane potential and result from the opening of distinct ionotropic receptors. We now report a separate current response elicited by applying nicotine to cultured bag cell neurons under whole cell voltage-clamp. This current was ostensibly inward, best resolved at depolarized voltages, presented a noncooperative dose-response with a half-maximal concentration near 1.5 mM, and associated with a decrease in membrane conductance. The unique nicotine-evoked response was not altered by intracellular perfusion with the G protein blocker GDPβS or exposure to classical nicotinic antagonists but was occluded by replacing intracellular K+ with Cs+. Consistent with an underlying mechanism of direct inhibition of one or more K+ channels, nicotine was found to rapidly reduce the fast-inactivating A-type K+ current as well as both components of the delayed-rectifier K+ current. Finally, nicotine increased bag cell neuron excitability, which manifested as reduction in spike threshold, greater action potential height and width, and markedly more spiking to continuous depolarizing current injection. In contrast to conventional transient activation of nicotinic ionotropic receptors, block of K+ channels could represent a nonstandard means for nicotine to profoundly alter the electrical properties of neurons over prolonged periods of time. PMID:26864763

  9. 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

  10. Neurotransmitters Drive Combinatorial Multistate Postsynaptic Density Networks

    OpenAIRE

    Coba, Marcelo P; Pocklington, Andrew J; Collins, Mark O; Kopanitsa, Maksym V; Uren, Rachel T; Swamy, Sajani; Croning, Mike D R; Choudhary, Jyoti S; Grant, Seth G N

    2009-01-01

    The mammalian postsynaptic density (PSD) comprises a complex collection of approximately 1100 proteins. Despite extensive knowledge of individual proteins, the overall organization of the PSD is poorly understood. Here, we define maps of molecular circuitry within the PSD based on phosphorylation of postsynaptic proteins. Activation of a single neurotransmitter receptor, the N-methyl-D-aspartate receptor (NMDAR), changed the phosphorylation status of 127 proteins. Stimulation of ionotropic an...

  11. 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.

  12. The Use of Adenosine Agonists to Treat Nerve Agent-Induced Seizure and Neuropathology

    Science.gov (United States)

    2016-09-01

    not be cited for purposes of advertisement . REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this...survivability. That was an important step to clinical relevancy as it was feared that ADO’s depression of cardiovascular output would exacerbate...kainate, adenosine and neuropeptide Y receptors. Neurochemical Research. 28: 1501-1515. 23. Bjorness, T. E. & R. W. Greene . 2009. Adenosine and sleep

  13. 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...

  14. Polyamine toxins

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Jensen, Lars S; Vogensen, Stine B

    2005-01-01

    Polyamine toxins, isolated from spiders and wasps, have been used as pharmacological tools for the study of ionotropic receptors, but their use have so far been hampered by their lack of selectivity. In this mini-review, we describe how careful synthetic modification of native polyamine toxins ha...

  15. Postsynaptic P2X3-containing receptors in gustatory nerve fibres mediate responses to all taste qualities in mice.

    Science.gov (United States)

    Vandenbeuch, Aurelie; Larson, Eric D; Anderson, Catherine B; Smith, Steven A; Ford, Anthony P; Finger, Thomas E; Kinnamon, Sue C

    2015-03-01

    Taste buds release ATP to activate ionotropic purinoceptors composed of P2X2 and P2X3 subunits, present on the taste nerves. Mice with genetic deletion of P2X2 and P2X3 receptors (double knockout mice) lack responses to all taste stimuli presumably due to the absence of ATP-gated receptors on the afferent nerves. Recent experiments on the double knockout mice showed, however, that their taste buds fail to release ATP, suggesting the possibility of pleiotropic deficits in these global knockouts. To test further the role of postsynaptic P2X receptors in afferent signalling, we used AF-353, a selective antagonist of P2X3-containing receptors to inhibit the receptors acutely during taste nerve recording and behaviour. The specificity of AF-353 for P2X3-containing receptors was tested by recording Ca(2+) transients to exogenously applied ATP in fura-2 loaded isolated geniculate ganglion neurons from wild-type and P2X3 knockout mice. ATP responses were completely inhibited by 10 μm or 100 μm AF-353, but neither concentration blocked responses in P2X3 single knockout mice wherein the ganglion cells express only P2X2-containing receptors. Furthermore, AF-353 had no effect on taste-evoked ATP release from taste buds. In wild-type mice, i.p. injection of AF-353 or simple application of the drug directly to the tongue, inhibited taste nerve responses to all taste qualities in a dose-dependent fashion. A brief access behavioural assay confirmed the electrophysiological results and showed that preference for a synthetic sweetener, SC-45647, was abolished following i.p. injection of AF-353. These data indicate that activation of P2X3-containing receptors is required for transmission of all taste qualities. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  16. Ionotropic Glutamate Receptor GluR1 in the Visual Cortex of Hamster: Distribution and Co-Localization with Calcium-Binding Proteins and GABA

    International Nuclear Information System (INIS)

    Ye, Eun-Ah; Kim, Tae-Jin; Choi, Jae-Sik; Jin, Mi-Joo; Jeon, Young-Ki; Kim, Moon-Sook; Jeon, Chang-Jin

    2006-01-01

    The subunit composition of the AMPA receptor is critical to its function. AMPA receptors that display very low calcium permeability include the GluR2 subunit, while AMPA receptors that contain other subunits, such as GluR1, display high calcium permeability. We have studied the distribution and morphology of neurons containing GluR1 in the hamster visual cortex with antibody immunocytochemistry. We compared this labeling to that for calbindin D28K, parvalbumin, and GABA. Anti-GluR1-immunoreactive (IR) neurons were located in all layers. The highest density of GluR1-IR neurons was found in layers II/III. The labeled neurons were non-pyramidal neurons, but were varied in morphology. The majority of the labeled neurons were round or oval cells. However, stellate, vertical fusiform, pyriform, and horizontal neurons were also labeled with the anti-GluR1 antibody. Two-color immunofluorescence revealed that many of the GluR1-IR neurons in the hamster visual cortex were double-labeled with either calbindin D28K (31.50%), or parvalbumin (22.91%), or GABA (63.89%). These results indicate that neurons in the hamster visual cortex express GluR1 differently according to different layers and selective cell types, and that many of the GluR1-IR neurons are limited to neurons that express calbindin D28K, parvalbumin, or GABA. The present study elucidates the neurochemical structure of GluR1, a useful clue in understanding the differential vulnerability of GluR1-containing neurons with regard to calcium-dependent excitotoxic mechanisms

  17. Rigid body essential X-ray crystallography

    DEFF Research Database (Denmark)

    Bjerrum, Esben Jannik; Biggin, Philip C

    2008-01-01

    The ligand-binding domain (LBD) from the ionotropic glutamate receptor subtype 2 (GluR2) has been shown to adopt a range of ligand-dependent conformational states. These states have been described in terms of the rotation required to fit subdomain (lobe) 2 following superposition of subdomain (lo...

  18. Structure of a tetrameric galectin from Cinachyrella sp. (ball sponge)

    Energy Technology Data Exchange (ETDEWEB)

    Freymann, Douglas M., E-mail: freymann@northwestern.edu [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States); Nakamura, Yuka [Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611 (Japan); Focia, Pamela J. [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States); Sakai, Ryuichi [Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611 (Japan); Swanson, Geoffrey T. [Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611 (United States)

    2012-09-01

    The structure of a tetrameric sponge galectin suggests a basis for glutamate receptor potentiation. The galectins are a family of proteins that bind with highest affinity to N-acetyllactosamine disaccharides, which are common constituents of asparagine-linked complex glycans. They play important and diverse physiological roles, particularly in the immune system, and are thought to be critical metastatic agents for many types of cancer cells, including gliomas. A recent bioactivity-based screen of marine sponge (Cinachyrella sp.) extract identified an ancestral member of the galectin family based on its unexpected ability to positively modulate mammalian ionotropic glutamate receptor function. To gain insight into the mechanistic basis of this activity, the 2.1 Å resolution X-ray structure of one member of the family, galectin CchG-1, is reported. While the protomer exhibited structural similarity to mammalian prototype galectin, CchG-1 adopts a novel tetrameric arrangement in which a rigid toroidal-shaped ‘donut’ is stabilized in part by the packing of pairs of vicinal disulfide bonds. Twofold symmetry between binding-site pairs provides a basis for a model for interaction with ionotropic glutamate receptors.

  19. Structure of a tetrameric galectin from Cinachyrella sp. (ball sponge)

    International Nuclear Information System (INIS)

    Freymann, Douglas M.; Nakamura, Yuka; Focia, Pamela J.; Sakai, Ryuichi; Swanson, Geoffrey T.

    2012-01-01

    The structure of a tetrameric sponge galectin suggests a basis for glutamate receptor potentiation. The galectins are a family of proteins that bind with highest affinity to N-acetyllactosamine disaccharides, which are common constituents of asparagine-linked complex glycans. They play important and diverse physiological roles, particularly in the immune system, and are thought to be critical metastatic agents for many types of cancer cells, including gliomas. A recent bioactivity-based screen of marine sponge (Cinachyrella sp.) extract identified an ancestral member of the galectin family based on its unexpected ability to positively modulate mammalian ionotropic glutamate receptor function. To gain insight into the mechanistic basis of this activity, the 2.1 Å resolution X-ray structure of one member of the family, galectin CchG-1, is reported. While the protomer exhibited structural similarity to mammalian prototype galectin, CchG-1 adopts a novel tetrameric arrangement in which a rigid toroidal-shaped ‘donut’ is stabilized in part by the packing of pairs of vicinal disulfide bonds. Twofold symmetry between binding-site pairs provides a basis for a model for interaction with ionotropic glutamate receptors

  20. 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

  1. The Regulation of GluN2A by Endogenous and Exogenous Regulators in the Central Nervous System.

    Science.gov (United States)

    Sun, Yongjun; Zhan, Liying; Cheng, Xiaokun; Zhang, Linan; Hu, Jie; Gao, Zibin

    2017-04-01

    The NMDA receptor is the most widely studied ionotropic glutamate receptor, and it is central to many physiological and pathophysiological processes in the central nervous system. GluN2A is one of the two main types of GluN2 NMDA receptor subunits in the forebrain. The proper activity of GluN2A is important to brain function, as the abnormal regulation of GluN2A may induce some neuropsychiatric disorders. This review will examine the regulation of GluN2A by endogenous and exogenous regulators in the central nervous system.

  2. 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.

  3. Neurotransmitter modulation of extracellular H+ fluxes from isolated retinal horizontal cells of the skate

    Science.gov (United States)

    Molina, Anthony J A; Verzi, Michael P; Birnbaum, Andrea D; Yamoah, Ebenezer N; Hammar, Katherine; Smith, Peter J S; Malchow, Robert Paul

    2004-01-01

    Self-referencing H+-selective microelectrodes were used to measure extracellular H+ fluxes from horizontal cells isolated from the skate retina. A standing H+ flux was detected from quiescent cells, indicating a higher concentration of free hydrogen ions near the extracellular surface of the cell as compared to the surrounding solution. The standing H+ flux was reduced by removal of extracellular sodium or application of 5-(N-ethyl-N-isopropyl) amiloride (EIPA), suggesting activity of a Na+–H+ exchanger. Glutamate decreased H+ flux, lowering the concentration of free hydrogen ions around the cell. AMPA/kainate receptor agonists mimicked the response, and the AMPA/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) eliminated the effects of glutamate and kainate. Metabotropic glutamate agonists were without effect. Glutamate-induced alterations in H+ flux required extracellular calcium, and were abolished when cells were bathed in an alkaline Ringer solution. Increasing intracellular calcium by photolysis of the caged calcium compound NP-EGTA also altered extracellular H+ flux. Immunocytochemical localization of the plasmalemma Ca2+–H+-ATPase (PMCA pump) revealed intense labelling within the outer plexiform layer and on isolated horizontal cells. Our results suggest that glutamate modulation of H+ flux arises from calcium entry into cells with subsequent activation of the plasmalemma Ca2+–H+-ATPase. These neurotransmitter-induced changes in extracellular pH have the potential to play a modulatory role in synaptic processing in the outer retina. However, our findings argue against the hypothesis that hydrogen ions released by horizontal cells normally act as the inhibitory feedback neurotransmitter onto photoreceptor synaptic terminals to create the surround portion of the centre-surround receptive fields of retinal neurones. PMID:15272044

  4. Acute alterations of somatodendritic action potential dynamics in hippocampal CA1 pyramidal cells after kainate-induced status epilepticus in mice.

    Directory of Open Access Journals (Sweden)

    Daniel Minge

    Full Text Available Pathophysiological remodeling processes at an early stage of an acquired epilepsy are critical but not well understood. Therefore, we examined acute changes in action potential (AP dynamics immediately following status epilepticus (SE in mice. SE was induced by intraperitoneal (i.p. injection of kainate, and behavioral manifestation of SE was monitored for 3-4 h. After this time interval CA1 pyramidal cells were studied ex vivo with whole-cell current-clamp and Ca(2+ imaging techniques in a hippocampal slice preparation. Following acute SE both resting potential and firing threshold were modestly depolarized (2-5 mV. No changes were seen in input resistance or membrane time constant, but AP latency was prolonged and AP upstroke velocity reduced following acute SE. All cells showed an increase in AP halfwidth and regular (rather than burst firing, and in a fraction of cells the notch, typically preceding spike afterdepolarization (ADP, was absent following acute SE. Notably, the typical attenuation of backpropagating action potential (b-AP-induced Ca(2+ signals along the apical dendrite was strengthened following acute SE. The effects of acute SE on the retrograde spread of excitation were mimicked by applying the Kv4 current potentiating drug NS5806. Our data unveil a reduced somatodendritic excitability in hippocampal CA1 pyramidal cells immediately after acute SE with a possible involvement of both Na(+ and K(+ current components.

  5. Involvement of N-methyl-d-aspartate receptors in the antidepressant-like effect of 5-hydroxytryptamine 3 antagonists in mouse forced swimming test and tail suspension test.

    Science.gov (United States)

    Kordjazy, Nastaran; Haj-Mirzaian, Arya; Amiri, Shayan; Ostadhadi, Sattar; Amini-Khoei, Hossein; Dehpour, Ahmad Reza

    2016-02-01

    Recent evidence indicates that 5-hydroxytryptamine 3 (5-HT3) antagonists such as ondansetron and tropisetron exert positive behavioral effects in animal models of depression. Due to the ionotropic nature of 5-HT3 and N-methyl-d-aspartate (NMDA) receptors, plus their contribution to the pathophysiology of depression, we investigated the possible role of NMDA receptors in the antidepressant-like effect of 5-HT3 receptor antagonists in male mice. In order to evaluate the animals' behavior in response to different treatments, we performed open-field test (OFT), forced swimming test (FST), and tail-suspension test (TST), which are considered as valid tasks for measuring locomotor activity and depressive-like behaviors in mice. Our data revealed that intraperitoneal (i.p.) administration of tropisetron (5, 10, and 30mg/kg) and ondansetron (0.01, and 0.1μg/kg) significantly decreased the immobility time in FST and TST. Also, co-administration of subeffective doses of tropisetron (1mg/kg, i.p.) or ondansetron (0.001μg/kg, i.p.) with subeffective doses of NMDA receptor antagonists, ketamine (1mg/kg, i.p.), MK-801 (0.05mg/kg, i.p.) and magnesium sulfate (10mg/kg, i.p.) resulted in a reduced immobility time both in FST and TST. The subeffective dose of NMDA (NMDA receptor agonist, 75mg/kg, i.p.) abolished the effects of 5-HT3 antagonists in FST and TST, further supporting the presumed interaction between 5-HT3 and NMDA receptors. These treatments did not affect the locomotor behavior of animals in OFT. Finally, the results of our study suggest that the positive effects of 5-HT3 antagonists on the coping behavior of mice in FST and TST are at least partly mediated through NMDA receptors participation. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Stereochemistry and molecular pharmacology of (S)-thio-ATPA, a new potent and selective GluR5 agonist

    DEFF Research Database (Denmark)

    Stensbøl, T B; Jensen, H S; Nielsen, B

    2001-01-01

    )-Glu) receptors (EC(50)=14 microM), comparable in potency with ATPA (EC(50)=34 microM). Recent findings, that (S)-ATPA is a potent (EC(50)=0.48 microM) and selective agonist at homomerically expressed ionotropic GluR5, prompted us to resolve thio-ATPA using chiral chromatography and pharmacologically characterize...

  7. Both neurons and astrocytes exhibited tetrodotoxin-resistant metabotropic glutamate receptor-dependent spontaneous slow Ca2+ oscillations in striatum.

    Directory of Open Access Journals (Sweden)

    Atsushi Tamura

    Full Text Available The striatum plays an important role in linking cortical activity to basal ganglia outputs. Group I metabotropic glutamate receptors (mGluRs are densely expressed in the medium spiny projection neurons and may be a therapeutic target for Parkinson's disease. The group I mGluRs are known to modulate the intracellular Ca(2+ signaling. To characterize Ca(2+ signaling in striatal cells, spontaneous cytoplasmic Ca(2+ transients were examined in acute slice preparations from transgenic mice expressing green fluorescent protein (GFP in the astrocytes. In both the GFP-negative cells (putative-neurons and astrocytes of the striatum, spontaneous slow and long-lasting intracellular Ca(2+ transients (referred to as slow Ca(2+ oscillations, which lasted up to approximately 200 s, were found. Neither the inhibition of action potentials nor ionotropic glutamate receptors blocked the slow Ca(2+ oscillation. Depletion of the intracellular Ca(2+ store and the blockade of inositol 1,4,5-trisphosphate receptors greatly reduced the transient rate of the slow Ca(2+ oscillation, and the application of an antagonist against mGluR5 also blocked the slow Ca(2+ oscillation in both putative-neurons and astrocytes. Thus, the mGluR5-inositol 1,4,5-trisphosphate signal cascade is the primary contributor to the slow Ca(2+ oscillation in both putative-neurons and astrocytes. The slow Ca(2+ oscillation features multicellular synchrony, and both putative-neurons and astrocytes participate in the synchronous activity. Therefore, the mGluR5-dependent slow Ca(2+ oscillation may involve in the neuron-glia interaction in the striatum.

  8. Synthesis and Pharmacological Evaluation of [11C]Granisetron and [18F]Fluoropalonosetron as PET Probes for 5-HT3 Receptor Imaging.

    Science.gov (United States)

    Mu, Linjing; Müller Herde, Adrienne; Rüefli, Pascal M; Sladojevich, Filippo; Milicevic Sephton, Selena; Krämer, Stefanie D; Thompson, Andrew J; Schibli, Roger; Ametamey, Simon M; Lochner, Martin

    2016-11-16

    Serotonin-gated ionotropic 5-HT 3 receptors are the major pharmacological targets for antiemetic compounds. Furthermore, they have become a focus for the treatment of irritable bowel syndrome (IBS) and there is some evidence that pharmacological modulation of 5-HT 3 receptors might alleviate symptoms of other neurological disorders. Highly selective, high-affinity antagonists, such as granisetron (Kytril) and palonosetron (Aloxi), belong to a family of drugs (the "setrons") that are well established for clinical use. To enable us to better understand the actions of these drugs in vivo, we report the synthesis of 8-fluoropalonosetron (15) that has a binding affinity (K i = 0.26 ± 0.05 nM) similar to the parent drug (K i = 0.21 ± 0.03 nM). We radiolabeled 15 by nucleophilic 18 F-fluorination of an unsymmetrical diaryliodonium palonosetron precursor and achieved the radiosynthesis of 1-(methyl- 11 C)-N-granisetron ([ 11 C]2) through N-alkylation with [ 11 C]CH 3 I, respectively. Both compounds [ 18 F]15 (chemical and radiochemical purity >95%, specific activity 41 GBq/μmol) and [ 11 C]2 (chemical and radiochemical purity ≥99%, specific activity 170 GBq/μmol) were evaluated for their utility as positron emission tomography (PET) probes. Using mouse and rat brain slices, in vitro autoradiography with both [ 18 F]15 and [ 11 C]2 revealed a heterogeneous and displaceable binding in cortical and hippocampal regions that are known to express 5-HT 3 receptors at significant levels. Subsequent PET experiments suggested that [ 18 F]15 and [ 11 C]2 are of limited utility for the PET imaging of brain 5-HT 3 receptors in vivo.

  9. Glutamate neurotransmission is affected in prenatally stressed offspring

    DEFF Research Database (Denmark)

    Adrover, Ezequiela; Pallarés, Maria Eugenia; Baier, Carlos Javier

    2015-01-01

    Previous studies from our laboratory have shown that male adult offspring of stressed mothers exhibited higher levels of ionotropic and metabotropic glutamate receptors than control rats. These offspring also showed long-lasting astroglial hypertrophy and a reduced dendritic arborization with syn......Previous studies from our laboratory have shown that male adult offspring of stressed mothers exhibited higher levels of ionotropic and metabotropic glutamate receptors than control rats. These offspring also showed long-lasting astroglial hypertrophy and a reduced dendritic arborization...... with synaptic loss. Since metabolism of glutamate is dependent on interactions between neurons and surrounding astroglia, our results suggest that glutamate neurotransmitter pathways might be impaired in the brain of prenatally stressed rats. To study the effect of prenatal stress on the metabolism...... was not affected it was found that prenatal stress (PS) changed the expression of the transporters, thus, producing a higher level of vesicular vGluT-1 in the frontal cortex (FCx) and elevated levels of GLT1 protein and messenger RNA in the hippocampus (HPC) of adult male PS offspring. We also observed increased...

  10. 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.

  11. Actions of Agonists, Fipronil and Ivermectin on the Predominant In Vivo Splice and Edit Variant (RDLbd, I/V) of the Drosophila GABA Receptor Expressed in Xenopus laevis Oocytes

    Science.gov (United States)

    Suwanmanee, Siros; Buckingham, Steven David; Biggin, Philip; Sattelle, David

    2014-01-01

    Ionotropic GABA receptors are the targets for several classes of insecticides. One of the most widely-studied insect GABA receptors is RDL (resistance to dieldrin), originally isolated from Drosophila melanogaster. RDL undergoes alternative splicing and RNA editing, which influence the potency of GABA. Most work has focussed on minority isoforms. Here, we report the first characterisation of the predominant native splice variant and RNA edit, combining functional characterisation with molecular modelling of the agonist-binding region. The relative order of agonist potency is GABA> muscimol> TACA> β-alanine. The I/V edit does not alter the potency of GABA compared to RDLbd. Docking calculations suggest that these agonists bind and activate RDLbdI/V through a similar binding mode. TACA and β-alanine are predicted to bind with lower affinity than GABA, potentially explaining their lower potency, whereas the lower potency of muscimol and isoguvacine cannot be explained structurally from the docking calculations. The A301S (resistance to dieldrin) mutation reduced the potency of antagonists picrotoxin, fipronil and pyrafluprole but the I/V edit had no measurable effect. Ivermectin suppressed responses to GABA of RDLbdI/V, RDLbd and RDLbdI/VA301S. The dieldrin resistant variant also showed reduced sensitivity to Ivermectin. This study of a highly abundant insect GABA receptor isoform will help the design of new insecticides. PMID:24823815

  12. 2-arylureidobenzoic acids

    DEFF Research Database (Denmark)

    Valgeirsson, Jon; Nielsen, Elsebet Ø; Peters, Dan

    2003-01-01

    A series of 2-arylureidobenzoic acids (AUBAs) was prepared by a short and effective synthesis, and the pharmacological activity at glutamate receptors was evaluated in vitro and in vivo. The compounds showed noncompetitive antagonistic activity at the kainate receptor subtype GluR5. The most potent...... on the benzoic acid moiety (ring A), whereas ring B tolerated a variety of substituents, but with a preference for lipophilic substituents. The most potent compounds had a 4-chloro substituent on ring A and 3-chlorobenzene (6b), 2-naphthalene (8h), or 2-indole (8k) as ring B and had IC(50) values of 1.3, 1...

  13. In vivo microdialysis studies on the effects of decortication and excitotoxic lesions on kainic acid-induced calcium fluxes, and endogenous amino acid release, in the rat striatum

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, S.P.; Lazarewicz, J.W.; Hamberger, A.

    1987-11-01

    The in vivo effects of kainate (1 mM) on fluxes of /sup 45/Ca2+, and endogenous amino acids, were examined in the rat striatum using the brain microdialysis technique. Kainate evoked a rapid decrease in dialysate /sup 45/Ca2+, and an increase in the concentration of amino acids in dialysates in Ca2+-free dialysates. Taurine was elevated six- to 10-fold, glutamate two- to threefold, and aspartate 1.5- to twofold. There was also a delayed increase in phosphoethanolamine, whereas nonneuroactive amino acids were increased only slightly. The kainic acid-evoked reduction in dialysate /sup 45/Ca2+ activity was attenuated in striata lesioned previously with kainate, suggesting the involvement of intrinsic striatal neurons in this response. The increase in taurine concentration induced by kainate was slightly smaller under these conditions. Decortication did not affect the kainate-evoked alterations in either dialysate /sup 45/Ca2+ or amino acids. These data suggest that kainate does not release acidic amino acids from their transmitter pools located in corticostriatal terminals.

  14. Electrophysiological evidence for the presence of NR2C subunits of N-methyl-D-aspartate receptors in rat neurons of the nucleus tractus solitarius

    Directory of Open Access Journals (Sweden)

    V. Baptista

    2005-01-01

    Full Text Available The nucleus tractus solitarius (NTS plays an important role in the control of autonomic reflex functions. Glutamate, acting on N-methyl-D-aspartate (NMDA and non-NMDA ionotropic receptors, is the major neurotransmitter in this nucleus, and the relative contribution of each receptor to signal transmission is unclear. We have examined NMDA excitatory postsynaptic currents (NMDA-EPSCs in the subpostremal NTS using the whole cell patch clamp technique on a transverse brainstem slice preparation. The NMDA-EPSCs were evoked by stimulation of the solitary tract over a range of membrane potentials. The NMDA-EPSCs, isolated pharmacologically, presented the characteristic outward rectification and were completely blocked by 50 µM DL-2-amino-5-phosphonopentanoic acid. The I-V relationship of the NMDA response shows that current, with a mean (± SEM amplitude of -41.2 ± 5.5 pA, is present even at a holding potential of -60 mV, suggesting that the NMDA receptors are weakly blocked by extracellular Mg2+ at near resting membrane potentials. This weak block can also be inferred from the value of 0.67 ± 0.17 for parameter delta obtained from a fit of the Woodhull equation to the I-V relationship. The maximal inward current measured on the I-V relationship was at -38.7 ± 4.2 mV. The decay phase of the NMDA currents was fitted with one exponential function with a decay time constant of 239 ± 51 and 418 ± 80 ms at a holding potential of -60 and +50 mV, respectively, which became slower with depolarization (e-fold per 145 mV. The biophysical properties of the NMDA receptors observed in the present study suggest that these receptors in the NTS contain NR2C subunits and may contribute to the synaptic signal integration.

  15. Solid-phase synthesis and biological evaluation of Joro spider toxin-4 from Nephila clavata

    DEFF Research Database (Denmark)

    Barslund, Anne Fuglsang; Poulsen, Mette Homann; Bach, Tinna Brøbech

    2011-01-01

    Polyamine toxins from orb weaver spiders are attractive pharmacological tools particularly for studies of ionotropic glutamate (iGlu) receptors in the brain. These polyamine toxins are biosynthesized in a combinatorial manner, providing a plethora of related, but structurally complex toxins...... to be exploited in biological studies. Here, we have used solid-phase synthetic methodology for the efficient synthesis of Joro spider toxin-4 (JSTX-4) (1) from Nephila clavata, providing sufficient amounts of the toxin for biological evaluation at iGlu receptor subtypes using electrophysiology. Biological...

  16. Metabotropic action of postsynaptic kainate receptors triggers hippocampal long-term potentiation

    Czech Academy of Sciences Publication Activity Database

    Petrovič, Miloš; da Silva, S. V.; Clement, J. P.; Vyklický ml., Ladislav; Mulle, C.; González-González, I. M.; Henley, J. M.

    2017-01-01

    Roč. 20, č. 4 (2017), s. 529-539 ISSN 1097-6256 R&D Projects: GA ČR(CZ) GA17-02300S Institutional support: RVO:67985823 Keywords : hippocampus * long-term potentiation * membrane proteins Subject RIV: FH - Neurology OBOR OECD: Neuroscience s (including psychophysiology Impact factor: 17.839, year: 2016

  17. 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

  18. 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.

  19. Kainate-enhanced release of D-(3H)aspartate from cerebral cortex and striatum: reversal by baclofen and pentobarbital

    Energy Technology Data Exchange (ETDEWEB)

    Potashner, S.J.; Gerard, D.

    1983-06-01

    A study was made of the actions of the excitant neurotoxin, kainic acid, on the uptake and the release of D-(2,3-3H)aspartate (D-ASP) in slices of guinea pig cerebral neocortex and striatum. The slices took up D-ASP, reaching concentrations of the amino acid in the tissue which were 14-23 times that in the medium. Subsequently, electrical stimulation of the slices evoked a Ca2+-dependent release of a portion of the D-ASP. Kainic acid (10(-5)-10(-3) M) produced a dose-dependent inhibition of D-ASP uptake. The electrically evoked release of D-ASP was increased 1.6-2.0 fold by 10(-5) and 10(-4)M kainic acid. The kainate-enlarged release was Ca2+-dependent. Dihydrokainic acid, an analogue of kainic acid with little excitatory or toxic action, did not increase D-ASP release but depressed D-ASP uptake. Attempts were made to block the action of kainic acid with baclofen and pentobarbital, compounds which depress the electrically evoked release of L-glutamate (L-GLU) and L-aspartate (L-ASP). Baclofen (4 X 10(-6)M), an antispastic drug, and pentobarbital (10(-4)M), an anesthetic agent, each inhibited the electrically evoked release of D-ASP and prevented the enhancement of the release above control levels usually produced by 10(-4)M kainic acid. It is proposed that 10(-5) and 10(-4)M kainic acid may enhance the synaptic release of L-GLU and L-ASP from neurons which use these amino acids as transmitters. This action is prevented by baclofen and pentobarbital. In view of the possibility that cell death in Huntington's disease could involve excessive depolarization of striatal and other cells by glutamate, baclofen might be effective in delaying the loss of neurons associated with this condition.

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

    OpenAIRE

    Borbély, S; Jocsak, Gergely; Moldovan, Kinga; Sedlak, Lucie; Preininger, Eva; Boldizsar, Imre; Toth, Attila; Atlason, Palmi T; Molnar, Elek; Vilagi, Ildiko

    2016-01-01

    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) t...

  1. Lessons from more than 80 structures of the GluA2 ligand-binding domain in complex with agonists, antagonists and allosteric modulators

    DEFF Research Database (Denmark)

    Pøhlsgaard, Jacob; Frydenvang, Karla Andrea; Madsen, Ulf

    2011-01-01

    Ionotropic glutamate receptors (iGluRs) constitute a family of ligand-gated ion channels that are essential for mediating fast synaptic transmission in the central nervous system. These receptors play an important role for the development and function of the nervous system, and are essential...... in learning and memory. However, iGluRs are also implicated in or have causal roles for several brain disorders, e.g. epilepsy, Alzheimer's disease, Parkinson's disease and schizophrenia. Their involvement in neurological diseases has stimulated widespread interest in their structure and function. Since...

  2. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent.

    Science.gov (United States)

    Nathan, Pradeep J; Lu, Kristy; Gray, M; Oliver, C

    2006-01-01

    L-theanine (N-ethyl-L-glutamine) or theanine is a major amino acid uniquely found in green tea. L-theanine has been historically reported as a relaxing agent, prompting scientific research on its pharmacology. Animal neurochemistry studies suggest that L-theanine increases brain serotonin, dopamine, GABA levels and has micromolar affinities for AMPA, Kainate and NMDA receptors. In addition has been shown to exert neuroprotective effects in animal models possibly through its antagonistic effects on group 1 metabotrophic glutamate receptors. Behavioural studies in animals suggest improvement in learning and memory. Overall, L-theanine displays a neuropharmacology suggestive of a possible neuroprotective and cognitive enhancing agent and warrants further investigation in animals and humans.

  3. Loss of GluN2D subunit results in social recognition deficit, social stress, 5-HT2C receptor dysfunction, and anhedonia in mice.

    Science.gov (United States)

    Yamamoto, Hideko; Kamegaya, Etsuko; Hagino, Yoko; Takamatsu, Yukio; Sawada, Wakako; Matsuzawa, Maaya; Ide, Soichiro; Yamamoto, Toshifumi; Mishina, Masayoshi; Ikeda, Kazutaka

    2017-01-01

    Issue entitled 'Ionotropic glutamate receptors'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Synthesis and pharmacological characterization of the selective GluK1 radioligand (S)-2-amino-3-(6-[3H]-2,4-dioxo-3,4-dihydrothieno.3,2-d] pyrimidin1(2H)- yl) propanoic acid ([3H]-NF608)

    DEFF Research Database (Denmark)

    Alcaide, Anna; Marconi, Laura; Marek, Ales

    2016-01-01

    The kainic acid receptors belong to the class of ionotropic glutamate receptors and comprise five subunits named GluK1-5. Radioligands are essential tools for use in binding assays aimed at ligand-receptor structure-activity-relationship studies. Previous work has led to the synthesis of GluK1...... radioligands [H-3]SYM2081, [H-3]-UBP310 and [H-3]-ATPA, however all strategies were work-intensive and thus not attractive. Herein, we report the synthesis of [H-3]-NF608 and subsequent pharmacological evaluation at homomeric recombinant rat GluK1 receptors. Binding affinities of a series of standard GluK1...... ligands were shown to be in line with previously reported affinities obtained by use of already reported radioligands....

  5. 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

  6. Effects of acute versus repeated cocaine exposure on the expression of endocannabinoid signaling-related proteins in the mouse cerebellum

    Directory of Open Access Journals (Sweden)

    Ana ePalomino

    2014-03-01

    Full Text Available Growing awareness of cerebellar involvement in addiction is based on the cerebellum’s intermediary position between motor and reward, potentially acting as an interface between motivational and cognitive functions. Here, we examined the impact of acute and repeated cocaine exposure on the two main signaling systems in the mouse cerebellum: the endocannabinoid (eCB and glutamate systems. To this end, we investigated whether eCB signaling-related gene and protein expression (CB1 receptors and enzymes that produce (DAGLα/β and NAPE-PLD and degrade (MAGL and FAAH eCB were altered. In addition, we analyzed the gene expression of relevant components of the glutamate signaling system (glutamate synthesizing enzymes LGA and KGA, mGluR3/5 metabotropic receptors, and NR1/2A/2B/2C-NMDA and GluR1/2/3/4-AMPA ionotropic receptor subunits and the gene expression of tyrosine hydroxylase (TH, the rate-limiting enzyme in catecholamine biosynthesis, because noradrenergic terminals innervate the cerebellar cortex. Results indicated that acute cocaine exposure decreased DAGLα expression, suggesting a down-regulation of 2-AG production, as well as gene expression of TH, KGA, mGluR3 and all ionotropic receptor subunits analyzed in the cerebellum. The acquisition of conditioned locomotion and sensitization after repeated cocaine exposure were associated with an increased NAPE-PLD/FAAH ratio, suggesting enhanced anandamide production, and a decreased DAGLβ/MAGL ratio, suggesting decreased 2-AG generation. Repeated cocaine also increased LGA gene expression but had no effect on glutamate receptors. These findings indicate that acute cocaine modulates the expression of the eCB and glutamate systems. Repeated cocaine results in normalization of glutamate receptor expression, although sustained changes in eCB is observed. We suggest that cocaine-induced alterations to cerebellar eCB should be considered when analyzing the adaptations imposed by psychostimulants that

  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

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    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

  8. 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

  9. The glutamate receptor GluR5 agonist (S)-2-amino-3-(3-hydroxy-7,8-dihydro-6H-cyclohepta[d]isoxazol-4-yl)propionic acid and the 8-methyl analogue

    DEFF Research Database (Denmark)

    Clausen, Rasmus Prætorius; Naur, Peter; Kristensen, Anders Skov

    2009-01-01

    The design, synthesis, and pharmacological characterization of a highly potent and selective glutamate GluR5 agonist is reported. (S)-2-Amino-3-((RS)-3-hydroxy-8-methyl-7,8-dihydro-6H-cyclohepta[d]isoxazol-4-yl)propionic acid (5) is the 8-methyl analogue of (S)-2-amino-3-(3-hydroxy-7,8-dihydro-6H......-cyclohepta[d]isoxazol-4-yl)propionic acid ((S)-4-AHCP, 4). Compound 5 displays an improved selectivity profile compared to 4. A versatile stereoselective synthetic route for this class of compounds is presented along with the characterization of the binding affinity of 5 to ionotropic glutamate receptors (i......GluRs). Functional characterization of 5 at cloned iGluRs using a calcium imaging assay and voltage-clamp recordings show a different activation of GluR5 compared to (S)-glutamic acid (Glu), kainic acid (KA, 1), and (S)-2-amino-3-(3-hydroxy-5-tert-butyl-4-isoxazolyl)propionic acid ((S)-ATPA, 3) as previously...

  10. A pharmacological profile of the high-affinity GluK5 kainate receptor

    DEFF Research Database (Denmark)

    Møllerud, Stine; Kastrup, Jette Sandholm Jensen; Pickering, Darryl S

    2016-01-01

    -hydroxyisoxazol-4-yl)propionate (ATPA), dihydrokainate and (2 S,4 R)−4-methyl-glutamate (SYM2081) have higher affinity at GluK3 compared to GluK5. Since some studies have indicated that GluK5 is associated with various diseases in the central nervous system (e.g. schizophrenia, temporal lobe epilepsy, bipolar...

  11. GABA-mediated synchronization in the human neocortex: elevations in extracellular potassium and presynaptic mechanisms.

    Science.gov (United States)

    Louvel, J; Papatheodoropoulos, C; Siniscalchi, A; Kurcewicz, I; Pumain, R; Devaux, B; Turak, B; Esposito, V; Villemeure, J G; Avoli, M

    2001-01-01

    Field potential and extracellular [K(+)] ([K(+)](o)) recordings were made in the human neocortex in an in vitro slice preparation to study the synchronous activity that occurs in the presence of 4-aminopyridine (50 microM) and ionotropic excitatory amino acid receptor antagonists. Under these experimental conditions, negative or negative-positive field potentials accompanied by rises in [K(+)](o) (up to 4.1 mM from a baseline of 3.25 mM) occurred spontaneously at intervals of 3-27 s. Both field potentials and [K(+)](o) elevations were largest at approximately 1000 microm from the pia. Similar events were induced by neocortical electrical stimuli. Application of medium containing low [Ca(2+)]/high [Mg(2+)] (n=3 slices), antagonism of the GABA(A) receptor (n=7) or mu-opioid receptor activation (n=4) abolished these events. Hence, they represented network, GABA-mediated potentials mainly reflecting the activation of type A receptors following GABA release from interneurons. The GABA(B) receptor agonist baclofen (10-100 microM, n=11) reduced and abolished the GABA-mediated potentials (ID(50)=18 microM). Baclofen effects were antagonized by the GABA(B) receptor antagonist CGP 35348 (0.1-1 mM, n=6; ID(50)=0.19 mM). CGP 38345 application to control medium increased the amplitude of the GABA-mediated potentials and the concomitant [K(+)](o) rises without modifying their rate of occurrence. The GABA-mediated potentials were not influenced by the broad-spectrum metabotropic glutamate agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (100 microM, n=10), but decreased in rate with the group I receptor agonist (S)-3,5-dihydroxyphenylglycine (10-100 microM, n=9). Our data indicate that human neocortical networks challenged with 4-aminopyridine generate glutamatergic-independent, GABA-mediated potentials that are modulated by mu-opioid and GABA(B) receptors presumably located on interneuron terminals. These events are associated with [K(+)](o) elevations that may

  12. 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.

  13. Post-Synapse Model Cell for Synaptic Glutamate Receptor (GluR-Based Biosensing: Strategy and Engineering to Maximize Ligand-Gated Ion-Flux Achieving High Signal-to-Noise Ratio

    Directory of Open Access Journals (Sweden)

    Tetsuya Haruyama

    2012-01-01

    Full Text Available Cell-based biosensing is a “smart” way to obtain efficacy-information on the effect of applied chemical on cellular biological cascade. We have proposed an engineered post-synapse model cell-based biosensors to investigate the effects of chemicals on ionotropic glutamate receptor (GluR, which is a focus of attention as a molecular target for clinical neural drug discovery. The engineered model cell has several advantages over native cells, including improved ease of handling and better reproducibility in the application of cell-based biosensors. However, in general, cell-based biosensors often have low signal-to-noise (S/N ratios due to the low level of cellular responses. In order to obtain a higher S/N ratio in model cells, we have attempted to design a tactic model cell with elevated cellular response. We have revealed that the increase GluR expression level is not directly connected to the amplification of cellular responses because the saturation of surface expression of GluR, leading to a limit on the total ion influx. Furthermore, coexpression of GluR with a voltage-gated potassium channel increased Ca2+ ion influx beyond levels obtained with saturating amounts of GluR alone. The construction of model cells based on strategy of amplifying ion flux per individual receptors can be used to perform smart cell-based biosensing with an improved S/N ratio.

  14. GLYX-13, a NMDA receptor glycine-site functional partial agonist, induces antidepressant-like effects without ketamine-like side effects.

    Science.gov (United States)

    Burgdorf, Jeffrey; Zhang, Xiao-lei; Nicholson, Katherine L; Balster, Robert L; Leander, J David; Stanton, Patric K; Gross, Amanda L; Kroes, Roger A; Moskal, Joseph R

    2013-04-01

    Recent human clinical studies with the NMDA receptor (NMDAR) antagonist ketamine have revealed profound and long-lasting antidepressant effects with rapid onset in several clinical trials, but antidepressant effects were preceded by dissociative side effects. Here we show that GLYX-13, a novel NMDAR glycine-site functional partial agonist, produces an antidepressant-like effect in the Porsolt, novelty induced hypophagia, and learned helplessness tests in rats without exhibiting substance abuse-related, gating, and sedative side effects of ketamine in the drug discrimination, conditioned place preference, pre-pulse inhibition and open-field tests. Like ketamine, the GLYX-13-induced antidepressant-like effects required AMPA/kainate receptor activation, as evidenced by the ability of NBQX to abolish the antidepressant-like effect. Both GLYX-13 and ketamine persistently (24 h) enhanced the induction of long-term potentiation of synaptic transmission and the magnitude of NMDAR-NR2B conductance at rat Schaffer collateral-CA1 synapses in vitro. Cell surface biotinylation studies showed that both GLYX-13 and ketamine led to increases in both NR2B and GluR1 protein levels, as measured by Western analysis, whereas no changes were seen in mRNA expression (microarray and qRT-PCR). GLYX-13, unlike ketamine, produced its antidepressant-like effect when injected directly into the medial prefrontal cortex (MPFC). These results suggest that GLYX-13 produces an antidepressant-like effect without the side effects seen with ketamine at least in part by directly modulating NR2B-containing NMDARs in the MPFC. Furthermore, the enhancement of 'metaplasticity' by both GLYX-13 and ketamine may help explain the long-lasting antidepressant effects of these NMDAR modulators. GLYX-13 is currently in a Phase II clinical development program for treatment-resistant depression.

  15. Gating characteristics control glutamate receptor distribution and trafficking in vivo.

    Science.gov (United States)

    Petzoldt, Astrid G; Lee, Yü-Hien; Khorramshahi, Omid; Reynolds, Eric; Plested, Andrew J R; Herzel, Hanspeter; Sigrist, Stephan J

    2014-09-08

    Glutamate-releasing synapses dominate excitatory release in the brain. Mechanisms governing their assembly are of major importance for circuit development and long-term plasticity underlying learning and memory. AMPA/Kainate-type glutamate receptors (GluRs) are tetrameric ligand-gated ion channels that open their ion-conducting pores in response to binding of the neurotransmitter. Changes in subunit composition of postsynaptic GluRs are highly relevant for plasticity and development of glutamatergic synapses [1-4]. To date, posttranslational modifications, mostly operating via the intracellular C-terminal domains (CTDs) of GluRs, are presumed to be the major regulator of trafficking [5]. In recent years, structural and electrophysiological analyses have improved our understanding of GluR gating mechanism [6-11]. However, whether conformational changes subsequent to glutamate binding may per se be able to influence GluR trafficking has remained an unaddressed question. Using a Drosophila system allowing for extended visualization of GluR trafficking in vivo, we here provide evidence that mutations changing the gating behavior alter GluR distribution and trafficking. GluR mutants associated with reduced charge transfer segregated from coexpressed wild-type GluRs on the level of individual postsynaptic densities. Segregation was lost upon blocking of evoked glutamate release. Photobleaching experiments suggested increased mobility of mutants with reduced charge transfer, which accumulated prematurely during early steps of synapse assembly, but failed to further increase their level in accordance with assembly of the presynaptic scaffold. In summary, gating characteristics seem to be a new variable for the understanding of GluR trafficking relevant to both development and plasticity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  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. Promoted neuronal differentiation after activation of alpha4/beta2 nicotinic acetylcholine receptors in undifferentiated neural progenitors.

    Directory of Open Access Journals (Sweden)

    Takeshi Takarada

    Full Text Available BACKGROUND: Neural progenitor is a generic term used for undifferentiated cell populations of neural stem, neuronal progenitor and glial progenitor cells with abilities for proliferation and differentiation. We have shown functional expression of ionotropic N-methyl-D-aspartate (NMDA and gamma-aminobutyrate type-A receptors endowed to positively and negatively regulate subsequent neuronal differentiation in undifferentiated neural progenitors, respectively. In this study, we attempted to evaluate the possible functional expression of nicotinic acetylcholine receptor (nAChR by undifferentiated neural progenitors prepared from neocortex of embryonic rodent brains. METHODOLOGY/PRINCIPAL FINDINGS: Reverse transcription polymerase chain reaction analysis revealed mRNA expression of particular nAChR subunits in undifferentiated rat and mouse progenitors prepared before and after the culture with epidermal growth factor under floating conditions. Sustained exposure to nicotine significantly inhibited the formation of neurospheres composed of clustered proliferating cells and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction activity at a concentration range of 1 µM to 1 mM without affecting cell survival. In these rodent progenitors previously exposed to nicotine, marked promotion was invariably seen for subsequent differentiation into cells immunoreactive for a neuronal marker protein following the culture of dispersed cells under adherent conditions. Both effects of nicotine were significantly prevented by the heteromeric α4β2 nAChR subtype antagonists dihydro-β-erythroidine and 4-(5-ethoxy-3-pyridinyl-N-methyl-(3E-3-buten-1-amine, but not by the homomeric α7 nAChR subtype antagonist methyllycaconitine, in murine progenitors. Sustained exposure to nicotine preferentially increased the expression of Math1 among different basic helix-loop-helix proneural genes examined. In undifferentiated progenitors from embryonic mice

  19. Sistema colinérgico: revisitando receptores, regulação e a relação com a doença de Alzheimer, esquizofrenia, epilepsia e tabagismo Colinergic system: revisiting receptors, regulation and the relationship with Alzheimer disease, schizophrenia, epilepsy and smoking

    Directory of Open Access Journals (Sweden)

    Ana L. M. Ventura

    2010-01-01

    Full Text Available OBJETIVO: Revisar a estrutura e o funcionamento do sistema colinérgico central ressaltando seu papel na fisiologia e na fisiopatologia das doenças de Alzheimer e Parkinson, esquizofrenia, epilepsia e tabagismo. MÉTODO: Foi realizada uma pesquisa bibliográfica no MedLine, LILACS, PubMed e ISI, e na Biblioteca da Fundação Oswaldo Cruz, RJ, selecionando-se o período de 1914 a 2009, utilizando os descritores: "receptors", "cholinergic", "Alzheimer disease", "schizophrenia", "epilepsy" e "smoking", além de referências cruzadas dos artigos selecionados e análise adicional de referências na literatura específica do tema. RESULTADOS: Efeitos importantes da ativação de receptores colinérgicos nicotínicos e muscarínicos sobre o desenvolvimento do sistema nervoso central (SNC têm sido descritos. A dessensibilização e a internalização dos receptores acoplados à proteína G mediadas pela ativação de proteínas cinases têm sido descritas em proliferação, diferenciação e morte celular, além de síndromes neuropsiquiátricas. CONCLUSÃO: As informações produzidas a partir de estudos do sistema de neurotransmissão colinérgica podem auxiliar no desenvolvimento de medicamentos mais específicos para o tratamento da doença de Alzheimer, esquizofrenia, epilepsia e tabagismo.OBJECTIVES: To review articles regarding important topics about cholinergic system and its ionotropic and G-protein coupled receptors as well as their regulation, also enlightening its importance in central nervous system (CNS development and in several neuropsychiatric conditions such as Alzheimer disease, schizophrenia, epilepsy and smoking. METHOD: Bibliographical research was completed through MedLine, LILACS, PubMed, ISI and the Fundação Oswaldo Cruz Library, RJ, specifically for 1914 to 2009, using the descritors: "receptors", "cholinergic", Alzheimer "disease", "schizophrenia", "epilepsy" and "smoking", in addition to the cross-reference of the

  20. Deletion of glutamate delta-1 receptor in mouse leads to aberrant emotional and social behaviors.

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    Roopali Yadav

    Full Text Available The delta family of ionotropic glutamate receptors consists of glutamate δ1 (GluD1 and glutamate δ2 (GluD2 receptors. While the role of GluD2 in the regulation of cerebellar physiology is well understood, the function of GluD1 in the central nervous system remains elusive. We demonstrate for the first time that deletion of GluD1 leads to abnormal emotional and social behaviors. We found that GluD1 knockout mice (GluD1 KO were hyperactive, manifested lower anxiety-like behavior, depression-like behavior in a forced swim test and robust aggression in the resident-intruder test. Chronic lithium rescued the depression-like behavior in GluD1 KO. GluD1 KO mice also manifested deficits in social interaction. In the sociability test, GluD1 KO mice spent more time interacting with an inanimate object compared to a conspecific mouse. D-Cycloserine (DCS administration was able to rescue social interaction deficits observed in GluD1 KO mice. At a molecular level synaptoneurosome preparations revealed lower GluA1 and GluA2 subunit expression in the prefrontal cortex and higher GluA1, GluK2 and PSD95 expression in the amygdala of GluD1 KO. Moreover, DCS normalized the lower GluA1 expression in prefrontal cortex of GluD1 KO. We propose that deletion of GluD1 leads to aberrant circuitry in prefrontal cortex and amygdala owing to its potential role in presynaptic differentiation and synapse formation. Furthermore, these findings are in agreement with the human genetic studies suggesting a strong association of GRID1 gene with several neuropsychiatric disorders including schizophrenia, bipolar disorder, autism spectrum disorders and major depressive disorder.

  1. On the ligand binding profile and desensitization of plant ionotropic glutamate receptor (iGluR)-like channels functioning in MAMP-triggered Ca2+ influx

    DEFF Research Database (Denmark)

    Kwaaitaal, Mark Adrianus Cornelis J; Maintz, Jens; Cavdar, Meltem

    2012-01-01

    in the putative agonist binding profile and potential mode of desensitization of MAMP-activated plant iGluRs. Based on results from pharmacological inhibition and desensitization experiments, we propose that plant iGluR complexes responsible for the MAMP-triggered Ca ( 2+) signature have a binding profile...... that combines the specificities of mammalian NMDA-and non-NMDA types of iGluRs, possibly reflecting the evolutionary history of plant and animal iGluRs. We further hypothesize that, analogous to the mammalian NMDA-NR1 receptor, desensitization of plant iGluR-like channels might involve binding of the ubiquitous...

  2. Effect of endurance training on seizure susceptibility, behavioral changes and neuronal damage after kainate-induced status epilepticus in spontaneously hypertensive rats.

    Science.gov (United States)

    Tchekalarova, J; Shishmanova, M; Atanasova, D; Stefanova, M; Alova, L; Lazarov, N; Georgieva, K

    2015-11-02

    The therapeutic efficacy of regular physical exercises in an animal model of epilepsy and depression comorbidity has been confirmed previously. In the present study, we examined the effects of endurance training on susceptibility to kainate (KA)-induced status epilepticus (SE), behavioral changes and neuronal damage in spontaneously hypertensive rats (SHRs). Male SHRs were randomly divided into two groups. One group was exercised on a treadmill with submaximal loading for four weeks and the other group was sedentary. Immediately after the training period, SE was evoked in half of the sedentary and trained rats by KA, while the other half of the two groups received saline. Basal systolic (SP), diastolic (DP) and mean arterial pressure (MAP) of all rats were measured at the beginning and at the end of the training period. Anxiety, memory and depression-like behaviour were evaluated a month after SE. The release of 5-HT in the hippocampus was measured using a liquid scintillation method and neuronal damage was analyzed by hematoxylin and eosin staining. SP and MAP of exercised SHRs decreased in comparison with the initial values. The increased resistance of SHRs to KA-induced SE was accompanied by an elongated latent seizure-free period, improved object recognition memory and antidepressant effect after the training program. While the anticonvulsant and positive behavioral effects of endurance training were accompanied by an increase of 5-HT release in the hippocampus, it did not exert neuroprotective activity. Our results indicate that prior exercise is an effective means to attenuate KA-induced seizures and comorbid behavioral changes in a model of hypertension and epilepsy suggesting a potential influence of hippocampal 5-HT on a comorbid depression. However, this beneficial impact does not prevent the development of epilepsy and concomitant brain damage. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Glutamate: Tastant and Neuromodulator in Taste Buds.

    Science.gov (United States)

    Vandenbeuch, Aurelie; Kinnamon, Sue C

    2016-07-01

    In taste buds, glutamate plays a double role as a gustatory stimulus and neuromodulator. The detection of glutamate as a tastant involves several G protein-coupled receptors, including the heterodimer taste receptor type 1, member 1 and 3 as well as metabotropic glutamate receptors (mGluR1 and mGluR4). Both receptor types participate in the detection of glutamate as shown with knockout animals and selective antagonists. At the basal part of taste buds, ionotropic glutamate receptors [N-methyl-d-aspartate (NMDA) and non-NMDA] are expressed and participate in the modulation of the taste signal before its transmission to the brain. Evidence suggests that glutamate has an efferent function on taste cells and modulates the release of other neurotransmitters such as serotonin and ATP. This short article reviews the recent developments in the field with regard to glutamate receptors involved in both functions as well as the influence of glutamate on the taste signal. © 2016 American Society for Nutrition.

  4. Ibotenic acid and thioibotenic acid

    DEFF Research Database (Denmark)

    Hermit, Mette B; Greenwood, Jeremy R; Nielsen, Birgitte

    2004-01-01

    In this study, we have determined and compared the pharmacological profiles of ibotenic acid and its isothiazole analogue thioibotenic acid at native rat ionotropic glutamate (iGlu) receptors and at recombinant rat metabotropic glutamate (mGlu) receptors expressed in mammalian cell lines....... Thioibotenic acid has a distinct pharmacological profile at group III mGlu receptors compared with the closely structurally related ibotenic acid; the former is a potent (low microm) agonist, whereas the latter is inactive. By comparing the conformational energy profiles of ibotenic and thioibotenic acid...... with the conformations preferred by the ligands upon docking to mGlu1 and models of the other mGlu subtypes, we propose that unlike other subtypes, group III mGlu receptor binding sites require a ligand conformation at an energy level which is prohibitively expensive for ibotenic acid, but not for thioibotenic acid...

  5. NPR-9, a Galanin-Like G-Protein Coupled Receptor, and GLR-1 Regulate Interneuronal Circuitry Underlying Multisensory Integration of Environmental Cues in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Jason C Campbell

    2016-05-01

    Full Text Available C. elegans inhabit environments that require detection of diverse stimuli to modulate locomotion in order to avoid unfavourable conditions. In a mammalian context, a failure to appropriately integrate environmental signals can lead to Parkinson's, Alzheimer's, and epilepsy. Provided that the circuitry underlying mammalian sensory integration can be prohibitively complex, we analyzed nematode behavioral responses in differing environmental contexts to evaluate the regulation of context dependent circuit reconfiguration and sensorimotor control. Our work has added to the complexity of a known parallel circuit, mediated by interneurons AVA and AIB, that integrates sensory cues and is responsible for the initiation of backwards locomotion. Our analysis of the galanin-like G-protein coupled receptor NPR-9 in C. elegans revealed that upregulation of galanin signaling impedes the integration of sensory evoked neuronal signals. Although the expression pattern of npr-9 is limited to AIB, upregulation of the receptor appears to impede AIB and AVA circuits to broadly prevent backwards locomotion, i.e. reversals, suggesting that these two pathways functionally interact. Galanin signaling similarly plays a broadly inhibitory role in mammalian models. Moreover, our identification of a mutant, which rarely initiates backwards movement, allowed us to interrogate locomotory mechanisms underlying chemotaxis. In support of the pirouette model of chemotaxis, organisms that did not exhibit reversal behavior were unable to navigate towards an attractant peak. We also assessed ionotropic glutamate receptor GLR-1 cell-specifically within AIB and determined that GLR-1 fine-tunes AIB activity to modify locomotion following reversal events. Our research highlights that signal integration underlying the initiation and fine-tuning of backwards locomotion is AIB and NPR-9 dependent, and has demonstrated the suitability of C. elegans for analysis of multisensory integration

  6. Potent homocysteine-induced ERK phosphorylation in cultured neurons depends on self-sensitization via system Xc-

    International Nuclear Information System (INIS)

    Gu Li; Hu Xiaoling; Xue Zhanxia; Yang Jun; Wan Lishu; Ren Yan; Hertz, Leif; Peng Liang

    2010-01-01

    Homocysteine is increased during pathological conditions, endangering vascular and cognitive functions, and elevated homocysteine during pregnancy may be correlated with an increased incidence of schizophrenia in the offspring. This study showed that millimolar homocysteine concentrations in saline medium cause phosphorylation of extracellular-signal regulated kinases 1 and 2 (ERK 1/2 ) in cerebellar granule neurons, inhibitable by metabotropic but not ionotropic glutamate receptor antagonists. These findings are analogous to observations by , that similar concentrations cause neuronal death. However, these concentrations are much higher than those occurring clinically during hyperhomocysteinemia. It is therefore important that a ∼ 10-fold increase in potency occurred in the presence of the glutamate precursor glutamine, when ERK 1/2 phosphorylation became inhibitable by NMDA or non-NMDA antagonists and dependent upon epidermal growth factor (EGF) receptor transactivation. However, glutamate release to the medium was reduced, suggesting that reversal of the cystine/glutamate antiporter, system X c - could be involved in potentiation of the response by causing a localized release of initially accumulated homocysteine. In agreement with this hypothesis further enhancement of ERK 1/2 phosphorylation occurred in the additional presence of cystine. Pharmacological inhibition of system X c - prevented the effect of micromolar homocysteine concentrations, and U0126-mediated inhibition of ERK 1/2 phosphorylation enhanced homocysteine-induced death. In conclusion, homocysteine interacts with system X c - like quisqualate (Venkatraman et al. 1994), by 'self-sensitization' with initial accumulation and subsequent release in exchange with cystine and/or glutamate, establishing high local homocysteine concentrations, which activate adjacent ionotropic glutamate receptors and cause neurotoxicity.

  7. Characterization of glutamate-induced formation of N- acylphosphatidylethanolamine and N-acylethanolamine in cultured neocortical neurons

    DEFF Research Database (Denmark)

    Hansen, Harald S.; Lauritzen, L.; Strand, A.M.

    1997-01-01

    ) assay). The increase in NAPE and NAE could be detected earlier than the neuronal death. Neither cyclic AMP, cyclic GMP, nitric oxide, protein kinase C, nor peroxidation appears to be involved in the formation of NAPE and NAE, as assessed by the use of different pharmacological agents. Exposure to 5 m...... receptors as seen by the inhibitory action of the NMDA-selective receptor antagonists D(-)-2-amino-5-phosphonovalerate and N- (1-(2-thienyl)-cyclohexyl)piperidine and the lack of effect of the a-amino- 3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate-receptor antagonist 6-cyano-7-nitro......-quinoxaline-2,3-dione (CNQX). In 6-day-old cultures, exposure to NMDA (100 µM for 24 h) induced a linear increase in the formation of NAPE and NAE as well as a 40-50% neuronal death, as measured by a decrease in cellular formazan formation [3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT...

  8. Hypocretin (orexin) regulates glutamate input to fast-spiking interneurons in layer V of the Fr2 region of the murine prefrontal cortex.

    Science.gov (United States)

    Aracri, Patrizia; Banfi, Daniele; Pasini, Maria Enrica; Amadeo, Alida; Becchetti, Andrea

    2015-05-01

    We studied the effect of hypocretin 1 (orexin A) in the frontal area 2 (Fr2) of the murine neocortex, implicated in the motivation-dependent goal-directed tasks. In layer V, hypocretin stimulated the spontaneous excitatory postsynaptic currents (EPSCs) on fast-spiking (FS) interneurons. The effect was accompanied by increased frequency of miniature EPSCs, indicating that hypocretin can target the glutamatergic terminals. Moreover, hypocretin stimulated the spontaneous inhibitory postsynaptic currents (IPSCs) on pyramidal neurons, with no effect on miniature IPSCs. This action was prevented by blocking 1) the ionotropic glutamatergic receptors; 2) the hypocretin receptor type 1 (HCRTR-1), with SB-334867. Finally, hypocretin increased the firing frequency in FS cells, and the effect was blocked when the ionotropic glutamate transmission was inhibited. Immunolocalization confirmed that HCRTR-1 is highly expressed in Fr2, particularly in layer V-VI. Conspicuous labeling was observed in pyramidal neuron somata and in VGLUT1+ glutamatergic terminals, but not in VGLUT2+ fibers (mainly thalamocortical afferents). The expression of HCRTR-1 in GABAergic structures was scarce. We conclude that 1) hypocretin regulates glutamate release in Fr2; 2) the effect presents a presynaptic component; 3) the peptide control of FS cells is indirect, and probably mediated by the regulation of glutamatergic input onto these cells. © The Author 2013. Published by Oxford University Press.

  9. Antennal Transcriptome Analysis of Odorant Reception Genes in the Red Turpentine Beetle (RTB, Dendroctonus valens.

    Directory of Open Access Journals (Sweden)

    Xiao-Cui Gu

    Full Text Available The red turpentine beetle (RTB, Dendroctonus valens LeConte (Coleoptera: Curculionidae, Scolytinae, is a destructive invasive pest of conifers which has become the second most important forest pest nationwide in China. Dendroctonus valens is known to use host odors and aggregation pheromones, as well as non-host volatiles, in host location and mass-attack modulation, and thus antennal olfaction is of the utmost importance for the beetles' survival and fitness. However, information on the genes underlying olfaction has been lacking in D. valens. Here, we report the antennal transcriptome of D. valens from next-generation sequencing, with the goal of identifying the olfaction gene repertoire that is involved in D. valens odor-processing.We obtained 51 million reads that were assembled into 61,889 genes, including 39,831 contigs and 22,058 unigenes. In total, we identified 68 novel putative odorant reception genes, including 21 transcripts encoding for putative odorant binding proteins (OBP, six chemosensory proteins (CSP, four sensory neuron membrane proteins (SNMP, 22 odorant receptors (OR, four gustatory receptors (GR, three ionotropic receptors (IR, and eight ionotropic glutamate receptors. We also identified 155 odorant/xenobiotic degradation enzymes from the antennal transcriptome, putatively identified to be involved in olfaction processes including cytochrome P450s, glutathione-S-transferases, and aldehyde dehydrogenase. Predicted protein sequences were compared with counterparts in Tribolium castaneum, Megacyllene caryae, Ips typographus, Dendroctonus ponderosae, and Agrilus planipennis.The antennal transcriptome described here represents the first study of the repertoire of odor processing genes in D. valens. The genes reported here provide a significant addition to the pool of identified olfactory genes in Coleoptera, which might represent novel targets for insect management. The results from our study also will assist with evolutionary

  10. Chronic ketamine reduces the peak frequency of gamma oscillations in mouse prefrontal cortex ex vivo

    Directory of Open Access Journals (Sweden)

    James M. McNally

    2013-09-01

    Full Text Available Abnormalities in EEG gamma band oscillations (GBO, 30-80 Hz serve as a prominent biomarker of schizophrenia (Sz, associated with positive, negative and cognitive symptoms. Chronic, subanesthetic administration of antagonists of N-methyl-D-aspartate receptors (NMDAR, such as ketamine, elicits behavioral effects and alterations in cortical interneurons similar to those observed in Sz. However, the chronic effects of ketamine on neocortical GBO are poorly understood. Thus, here we examine the effects of chronic (5 daily i.p. injections application of ketamine (5 and 30 mg/kg and the more specific NMDAR antagonist, MK-801 (0.02, 0.5, and 2 mg/kg, on neocortical GBO ex vivo. Oscillations were generated by focal application of the glutamate receptor agonist, kainate, in coronal brain slices containing the prelimbic cortex. This region constitutes the rodent analogue of the human dorsolateral prefrontal cortex, a brain region strongly implicated in Sz-pathophysiology. Here we report the novel finding that chronic ketamine elicits a reduction in the peak oscillatory frequency of kainate-elicited oscillations (from 47 to 40 Hz at 30 mg/kg. Moreover, the power of GBO in the 40-50 Hz band was reduced. These findings are reminiscent of both the reduced resonance frequency and power of cortical oscillations observed in Sz clinical studies. Surprisingly, MK-801 had no significant effect, suggesting care is needed when equating Sz-like behavioral effects elicited by different NMDAR antagonists to alterations in GBO activity. We conclude that chronic ketamine in the mouse mimics GBO abnormalities observed in Sz patients. Use of this ex vivo slice model may be useful in testing therapeutic compounds which rescue these GBO abnormalities.

  11. Receptor-receptor interactions within receptor mosaics. Impact on neuropsychopharmacology.

    Science.gov (United States)

    Fuxe, K; Marcellino, D; Rivera, A; Diaz-Cabiale, Z; Filip, M; Gago, B; Roberts, D C S; Langel, U; Genedani, S; Ferraro, L; de la Calle, A; Narvaez, J; Tanganelli, S; Woods, A; Agnati, L F

    2008-08-01

    Future therapies for diseases associated with altered dopaminergic signaling, including Parkinson's disease, schizophrenia and drug addiction or drug dependence may substantially build on the existence of intramembrane receptor-receptor interactions within dopamine receptor containing receptor mosaics (RM; dimeric or high-order receptor oligomers) where it is believed that the dopamine D(2) receptor may operate as the 'hub receptor' within these complexes. The constitutive adenosine A(2A)/dopamine D(2) RM, located in the dorsal striato-pallidal GABA neurons, are of particular interest in view of the demonstrated antagonistic A(2A)/D(2) interaction within these heteromers; an interaction that led to the suggestion and later demonstration that A(2A) antagonists could be used as novel anti-Parkinsonian drugs. Based on the likely existence of A(2A)/D(2)/mGluR5 RM located both extrasynaptically on striato-pallidal GABA neurons and on cortico-striatal glutamate terminals, multiple receptor-receptor interactions within this RM involving synergism between A(2A)/mGluR5 to counteract D(2) signaling, has led to the proposal of using combined mGluR5 and A(2A) antagonists as a future anti-Parkinsonian treatment. Based on the same RM in the ventral striato-pallidal GABA pathways, novel strategies for the treatment of schizophrenia, building on the idea that A(2A) agonists and/or mGluR5 agonists will help reduce the increased dopaminergic signaling associated with this disease, have been suggested. Such treatment may ensure the proper glutamatergic drive from the mediodorsal thalamic nucleus to the prefrontal cortex, one which is believed to be reduced in schizophrenia due to a dominance of D(2)-like signaling in the ventral striatum. Recently, A(2A) receptors also have been shown to counteract the locomotor and sensitizing actions of cocaine and increases in A(2A) receptors have also been observed in the nucleus accumbens after extended cocaine self-administration, probably

  12. A parallel panning scheme used for selection of a GluA4-specific Fab targeting the ligand-binding domain

    DEFF Research Database (Denmark)

    Clausen, Rasmus P; Mohr, Andreas Ø; Riise, Erik

    2016-01-01

    A method for development of murine Fab fragments towards extracellular domains of a surface receptor is presented. The GluA4 ionotropic glutamate receptor is used as a model system. Recombinant GluA4 ectodomain comprising both the N-terminal domain (NTD) and the ligand-binding domain (LBD) in one...... molecule was used for immunization. A Fab-phage library was constructed and a parallel panning approach enabled selection of murine Fab fragments towards either intact ectodomain or the isolated LBD of the GluA4 receptor. One LBD-Fab (FabL9) showed exclusive selectivity for the GluA4 LBD, over a panel...... of LBDs from GluA2, GluK1, GluK2 and GluD2. Soluble FabL9 was produced in amounts suitable for characterization. Competitive ELISA and rat-brain immunoprecipitation experiments confirmed that the FabL9 epitope is conserved in the LBD and in the intact native receptor. By an alignment of GluA2 and GluA4...

  13. Identification of Genes Involved in Chemoreception in Plutella xyllostella by Antennal Transcriptome Analysis.

    Science.gov (United States)

    Yang, Shiyong; Cao, Depan; Wang, Guirong; Liu, Yang

    2017-09-20

    Perception of environmental and habitat cues is of significance for insect survival and reproduction. Odor detection in insects is mediated by a number of proteins in antennae such as odorant receptors (ORs), ionotropic receptors (IRs), odorant binding proteins (OBPs), chemosensory proteins (CSPs), sensory neuron membrane proteins (SNMPs) and odorant degrading enzymes. In this study, we sequenced and assembled the adult male and female antennal transcriptomes of a destructive agricultural pest, the diamondback moth Plutella xyllostella. In these transcriptomes, we identified transcripts belonging to 6 chemoreception gene families related to ordor detection, including 54 ORs, 16 IRs, 7 gustatory receptors (GRs), 15 CSPs, 24 OBPs and 2 SNMPs. Semi-quantitative reverse transcription PCR analysis of expression patterns indicated that some of these ORs and IRs have clear sex-biased and tissue-specific expression patterns. Our results lay the foundation for future characterization of the functions of these P. xyllostella chemosensory receptors at the molecular level and development of novel semiochemicals for integrated control of this agricultural pest.

  14. TAURINE REGULATION OF VOLTAGE-GATED CHANNELS IN RETINAL NEURONS

    Science.gov (United States)

    Rowan, Matthew JM; Bulley, Simon; Purpura, Lauren; Ripps, Harris; Shen, Wen

    2017-01-01

    Taurine activates not only Cl−-permeable ionotropic receptors, but also receptors that mediate metabotropic responses. The metabotropic property of taurine was revealed in electrophysiological recordings obtained after fully blocking Cl−-permeable receptors with an inhibitory “cocktail” consisting of picrotoxin, SR95531, and strychnine. We found that taurine’s metabotropic effects regulate voltage-gated channels in retinal neurons. After applying the inhibitory cocktail, taurine enhanced delayed outward rectifier K+ channels preferentially in Off-bipolar cells, and the effect was completely blocked by the specific PKC inhibitor, GF109203X. Additionally, taurine also acted through a metabotropic pathway to suppress both L- and N-type Ca2+ channels in retinal neurons, which were insensitive to the potent GABAB receptor inhibitor, CGP55845. This study reinforces our previous finding that taurine in physiological concentrations produces a multiplicity of metabotropic effects that precisely govern the integration of signals being transmitted from the retina to the brain. PMID:23392926

  15. The C1q complement family of synaptic organizers: not just complementary.

    Science.gov (United States)

    Yuzaki, Michisuke

    2017-08-01

    Molecules that regulate formation, differentiation, and maintenance of synapses are called synaptic organizers. Recently, various 'C1q family' proteins have been shown to be released from neurons, and serve as a new class of synaptic organizers. Cbln1 and C1ql1 proteins regulate the formation and maintenance of parallel fiber-Purkinje cell and climbing fiber-Purkinje cell synapses, respectively, in the cerebellum. Cbln1 also modulates the function of postsynaptic delta2 glutamate receptors to regulate synaptic plasticity. C1ql2 and C1ql3, released from mossy fibers, determine the synaptic localization of postsynaptic kainate receptors in the hippocampus. C1ql3 also regulates the formation of synapses between the basolateral amygdala and the prefrontal cortex. These findings indicate the diverse functions of C1q family proteins in various brain regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Muscarinic Long-Term Enhancement of Tonic and Phasic GABAA Inhibition in Rat CA1 Pyramidal Neurons

    Science.gov (United States)

    Domínguez, Soledad; Fernández de Sevilla, David; Buño, Washington

    2016-01-01

    Acetylcholine (ACh) regulates network operation in the hippocampus by controlling excitation and inhibition in rat CA1 pyramidal neurons (PCs), the latter through gamma-aminobutyric acid type-A receptors (GABAARs). Although, the enhancing effects of ACh on GABAARs have been reported (Dominguez et al., 2014, 2015), its role in regulating tonic GABAA inhibition has not been explored in depth. Therefore, we aimed at determining the effects of the activation of ACh receptors on responses mediated by synaptic and extrasynaptic GABAARs. Here, we show that under blockade of ionotropic glutamate receptors ACh, acting through muscarinic type 1 receptors, paired with post-synaptic depolarization induced a long-term enhancement of tonic GABAA currents (tGABAA) and puff-evoked GABAA currents (pGABAA). ACh combined with depolarization also potentiated IPSCs (i.e., phasic inhibition) in the same PCs, without signs of interactions of synaptic responses with pGABAA and tGABAA, suggesting the contribution of two different GABAA receptor pools. The long-term enhancement of GABAA currents and IPSCs reduced the excitability of PCs, possibly regulating plasticity and learning in behaving animals. PMID:27833531

  17. Isobolographic analysis of the mechanisms of action of anticonvulsants from a combination effect.

    Science.gov (United States)

    Matsumura, Nobuko; Nakaki, Toshio

    2014-10-15

    The nature of the pharmacodynamic interactions of drugs is influenced by the drugs׳ mechanisms of action. It has been hypothesized that drugs with different mechanisms are likely to interact synergistically, whereas those with similar mechanisms seem to produce additive interactions. In this review, we describe an extensive investigation of the published literature on drug combinations of anticonvulsants, the nature of the interaction of which has been evaluated by type I and II isobolographic analyses and the subthreshold method. The molecular targets of antiepileptic drugs (AEDs) include Na(+) and Ca(2+) channels, GABA type-A receptor, and glutamate receptors such as NMDA and AMPA/kainate receptors. The results of this review indicate that the nature of interactions evaluated by type I isobolographic analyses but not by the two other methods seems to be consistent with the above hypothesis. Type I isobolographic analyses may be used not only for evaluating drug combinations but also for predicting the targets of new drugs. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Coenzyme Q10 instilled as eye drops on the cornea reaches the retina and protects retinal layers from apoptosis in a mouse model of kainate-induced retinal damage.

    Science.gov (United States)

    Lulli, Matteo; Witort, Ewa; Papucci, Laura; Torre, Eugenio; Schipani, Christian; Bergamini, Christian; Dal Monte, Massimo; Capaccioli, Sergio

    2012-12-17

    To evaluate if coenzyme Q10 (CoQ10) can protect retinal ganglion cells (RGCs) from apoptosis and, when instilled as eye drops on the cornea, if it can reach the retina and exert its antiapoptotic activity in this area in a mouse model of kainate (KA)-induced retinal damage. Rat primary or cultured RGCs were subjected to glutamate (50 μM) or chemical hypoxia (Antimycin A, 200 μM) or serum withdrawal (FBS, 0.5%) in the presence or absence of CoQ10 (10 μM). Cell viability was evaluated by light microscopy and fluorescence-activated cell sorting analyses. Apoptosis was evaluated by caspase 3/7 activity and mitochondrion depolarization tetramethylrhodamine ethyl ester analysis. CoQ10 transfer to the retina following its instillation as eye drops on the cornea was quantified by HPLC. Retinal protection by CoQ10 (10 μM) eye drops instilled on the cornea was then evaluated in a mouse model of KA-induced excitotoxic retinal cell apoptosis by cleaved caspase 3 immunohistofluorescence, caspase 3/7 activity assays, and quantification of inhibition of RGC loss. CoQ10 significantly increased viable cells by preventing RGC apoptosis. Furthermore, when topically applied as eye drops to the cornea, it reached the retina, thus substantially increasing local CoQ10 concentration and protecting retinal layers from apoptosis. The ability of CoQ10 eye drops to protect retinal cells from apoptosis in the mouse model of KA-induced retinal damage suggests that topical CoQ10 may be evaluated in designing therapies for treating apoptosis-driven retinopathies.

  19. Possible Relevance of Receptor-Receptor Interactions between Viral- and Host-Coded Receptors for Viral-Induced Disease

    Directory of Open Access Journals (Sweden)

    Luigi F. Agnati

    2007-01-01

    Full Text Available It has been demonstrated that some viruses, such as the cytomegalovirus, code for G-protein coupled receptors not only to elude the immune system, but also to redirect cellular signaling in the receptor networks of the host cells. In view of the existence of receptor-receptor interactions, the hypothesis is introduced that these viral-coded receptors not only operate as constitutively active monomers, but also can affect other receptor function by interacting with receptors of the host cell. Furthermore, it is suggested that viruses could also insert not single receptors (monomers, but clusters of receptors (receptor mosaics, altering the cell metabolism in a profound way. The prevention of viral receptor-induced changes in host receptor networks may give rise to novel antiviral drugs that counteract viral-induced disease.

  20. Neonatal domoic acid decreases in vivo binding of [11C]yohimbine to α2 adrenoceptors in adult rat brain

    DEFF Research Database (Denmark)

    Thomsen, Majken; Lillethorup, Thea Pinholt; Jakobsen, Steen

    day 8-14 with saline or one of two low sub-convulsive doses, 20µg/kg [DOM20] or 60µg/kg [DOM60] of DOM, an AMPA/kainate receptor agonist. The behaviour of the rats was observed in an open field test, a social interaction test and the forced swim test at day 50, 75 and 98, respectively. At ~120 days...... of age 3-4 rats per group were injected with [11C]yohimbine, an α2 adrenergic receptor antagonist and scanned in a micro positron emission tomography (PET) scanner. DOM60 spent more time in the periphery during the open field test and less time struggling in the forced swim test compared to the saline...... treated rats. microPET data revealed that DOM60 rats had a 40-47 % reduction in [11C]yohimbine binding in limbic and cortical brain regions relative to saline treated rats. We conclude that neonatal administration of DOM combined with the potential stress associated with behavioural testing results...

  1. Synthesis and pharmacology of 3-hydroxy-delta2-isoxazoline-cyclopentane analogues of glutamic acid

    DEFF Research Database (Denmark)

    Conti, P; De Amici, M; Bräuner-Osborne, Hans

    2002-01-01

    The synthesis and pharmacology of two potential glutamic acid receptor ligands are described. Preparation of the bicyclic 3-hydroxy-delta2-isoxazoline-cyclopentane derivatives (+/-)-7 and (+/-)-8 was accomplished via 1,3-dipolar cycloaddition of bromonitrile oxide to suitably protected 1-amino......-cyclopent-3-enecarboxylic acids. Their structure was established using a combination of 1H NMR spectroscopy and molecular mechanics calculations carried out on the intermediate cycloadducts (+/-)-11 and (+/-)-12. Amino acid derivatives (+/-)-7 and (+/-)-8 were assayed at ionotropic and metabotropic glutamic...... acid receptor subtypes and their activity compared with that of trans-ACPD and cis-ACPD. The results show that the replacement of the omega-carboxylic group of the model compounds with the 3-hydroxy-delta2-isoxazoline moiety abolishes or reduces drastically the activity at the metabotropic glutamate...

  2. Altered gamma oscillations during pregnancy through loss of δ subunit-containing GABAA receptors on parvalbumin interneurons

    Directory of Open Access Journals (Sweden)

    Isabella eFerando

    2013-09-01

    Full Text Available Gamma (γ oscillations (30-120 Hz, an emergent property of neuronal networks, correlate with memory, cognition and encoding. In the hippocampal CA3 region, locally generated γ oscillations emerge through feedback between inhibitory parvalbumin-positive basket cells (PV+BCs and the principal (pyramidal cells. PV+BCs express δ-subunit-containing GABAARs (-GABAARs and NMDA receptors (NMDA-Rs that balance the frequency of γ oscillations. Neuroactive steroids (NS, such as the progesterone-derived (3α,5α-3-hydroxy-pregnan-20-one (allopregnanolone; ALLO, modulate the expression of δ-GABAARs and the tonic conductance they mediate. Pregnancy produces large increases in ALLO and brain-region-specific homeostatic changes in δ-GABAARs expression. Here we show that in CA3, where most PV+ interneurons (INs express δ-GABAARs, expression of δ-GABAARs on INs diminishes during pregnancy, but reverts to control levels within 48 hours postpartum. These anatomical findings were corroborated by a pregnancy-related increase in the frequency of kainate-induced CA3 γ oscillations in vitro that could be countered by the NMDA-R antagonists D-AP5 and PPDA. Mimicking the typical hormonal conditions during pregnancy by supplementing 100 nM ALLO lowered the γ frequencies to levels found in virgin or postpartum mice. Our findings show that states of altered NS levels (e.g., pregnancy may provoke perturbations in γ oscillatory activity through direct effects on the GABAergic system, and underscore the importance of δ-GABAARs homeostatic plasticity in maintaining constant network output despite large hormonal changes. Inaccurate coupling of NS levels to δ-GABAAR expression may facilitate abnormal neurological and psychiatric conditions such as epilepsy, post-partum depression, and post-partum psychosis, thus providing insights into potential new treatments.

  3. Somatostatin receptors

    DEFF Research Database (Denmark)

    Møller, Lars Neisig; Stidsen, Carsten Enggaard; Hartmann, Bolette

    2003-01-01

    functional units, receptors co-operate. The total receptor apparatus of individual cell types is composed of different-ligand receptors (e.g. SRIF and non-SRIF receptors) and co-expressed receptor subtypes (e.g. sst(2) and sst(5) receptors) in characteristic proportions. In other words, levels of individual......-peptides, receptor agonists and antagonists. Relatively long half lives, as compared to those of the endogenous ligands, have been paramount from the outset. Motivated by theoretical puzzles or the shortcomings of present-day diagnostics and therapy, investigators have also aimed to produce subtype...

  4. Binding of L-glutamic acid to non-receptor materials

    International Nuclear Information System (INIS)

    Periyasamy, S.; Ito, M.; Chiu, T.H.

    1986-01-01

    [ 3 H]L-glutamic acid ([ 3 H]Glu) binding to microfuge tubes, glass fiber filters, and glass tubes was studied in 4 buffers (50 mM, pH 7.4 at 4 0 C). Binding assays were done at 0-4 0 C. Binding to these materials was negligible in the absence of external force, but was increased by suction or centrifugation in Tris-HCl or Tris-citrate buffer. The force-induced binding was much less or was eliminated in Tris-acetate or HEPES-KOH buffer. [ 3 H]Glu binding to microfuge tubes was inhibited by L- but not D- isomers of glutamate and aspartate. DL-2-amino-7-phosphonoheptanoic acid was without effect. Other compounds that showed low to moderate inhibitory activity were N-methyl-D-aspartate, quisqualate, L-glutamic acid diethyl ester. N-methyl-L-aspartate, kainate, and 2-amino-4-phosphonobutyrate. Binding was inhibited by denatured P 2 membrane preparation in Tris-acetate buffer was used. It is suggested that Tris-acetate or HEPES-KOH buffer should be used in the glutamate binding assay

  5. Merkel disc is a serotonergic synapse in the epidermis for transmitting tactile signals in mammals.

    Science.gov (United States)

    Chang, Weipang; Kanda, Hirosato; Ikeda, Ryo; Ling, Jennifer; DeBerry, Jennifer J; Gu, Jianguo G

    2016-09-13

    The evolution of sensory systems has let mammals develop complicated tactile end organs to enable sophisticated sensory tasks, including social interaction, environmental exploration, and tactile discrimination. The Merkel disc, a main type of tactile end organ consisting of Merkel cells (MCs) and Aβ-afferent endings, are highly abundant in fingertips, touch domes, and whisker hair follicles of mammals. The Merkel disc has high tactile acuity for an object's physical features, such as texture, shape, and edges. Mechanisms underlying the tactile function of Merkel discs are obscured as to how MCs transmit tactile signals to Aβ-afferent endings leading to tactile sensations. Using mouse whisker hair follicles, we show herein that tactile stimuli are transduced by MCs into excitatory signals that trigger vesicular serotonin release from MCs. We identify that both ionotropic and metabotropic 5-hydroxytryptamine (5-HT) receptors are expressed on whisker Aβ-afferent endings and that their activation by serotonin released from MCs initiates Aβ-afferent impulses. Moreover, we demonstrate that these ionotropic and metabotropic 5-HT receptors have a synergistic effect that is critical to both electrophysiological and behavioral tactile responses. These findings elucidate that the Merkel disc is a unique serotonergic synapse located in the epidermis and plays a key role in tactile transmission. The epidermal serotonergic synapse may have important clinical implications in sensory dysfunctions, such as the loss of tactile sensitivity and tactile allodynia seen in patients who have diabetes, inflammatory diseases, and undergo chemotherapy. It may also have implications in the exaggerated tactile sensations induced by recreational drugs that act on serotoninergic synapses.

  6. A new highly selective metabotropic excitatory amino acid agonist: 2-amino-4-(3-hydroxy-5-methylisoxazol-4-yl)butyric acid

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Sløk, F A; Skjaerbaek, N

    1996-01-01

    The homologous series of acidic amino acids, ranging from aspartic acid (1) to 2-aminosuberic acid (5), and the corresponding series of 3-isoxazolol bioisosteres of these amino acids, ranging from (RS)-2-amino-2-(3-hydroxy-5-methylisoxazol-4-yl)acetic acid (AMAA, 6) to (RS)-2-amino-6-(3-hydroxy-5......-methylisoxazol-4-yl)hexanoic acid (10), were tested as ligands for metabotropic excitatory amino acid receptors (mGlu1 alpha, mGlu2, mGlu4a, and mGlu6). Whereas AMAA (6) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propinoic acid (AMPA, 7) are potent and highly selective agonists at N......-methyl-D-aspartic acid (NMDA) and AMPA receptors, respectively, the higher homologue of AMPA (7), (RS)-2-amino-4-(3-hydroxy-5-methylisoxazol-4-yl)butyric acid (homo-AMPA, 8), is inactive at ionotropic excitatory amino acid receptors. Homo-AMPA (8), which is a 3-isoxazolol bioisostere of 2-aminoadipic acid (3), was...

  7. Monoaminergic orchestration of motor programs in a complex C. elegans behavior.

    Directory of Open Access Journals (Sweden)

    Jamie L Donnelly

    Full Text Available Monoamines provide chemical codes of behavioral states. However, the neural mechanisms of monoaminergic orchestration of behavior are poorly understood. Touch elicits an escape response in Caenorhabditis elegans where the animal moves backward and turns to change its direction of locomotion. We show that the tyramine receptor SER-2 acts through a Gαo pathway to inhibit neurotransmitter release from GABAergic motor neurons that synapse onto ventral body wall muscles. Extrasynaptic activation of SER-2 facilitates ventral body wall muscle contraction, contributing to the tight ventral turn that allows the animal to navigate away from a threatening stimulus. Tyramine temporally coordinates the different phases of the escape response through the synaptic activation of the fast-acting ionotropic receptor, LGC-55, and extrasynaptic activation of the slow-acting metabotropic receptor, SER-2. Our studies show, at the level of single cells, how a sensory input recruits the action of a monoamine to change neural circuit properties and orchestrate a compound motor sequence.

  8. Oxytocin Modulates Nociception as an Agonist of Pain-Sensing TRPV1

    Directory of Open Access Journals (Sweden)

    Yelena Nersesyan

    2017-11-01

    Full Text Available Oxytocin is a hormone with various actions. Oxytocin-containing parvocellular neurons project to the brainstem and spinal cord. Oxytocin release from these neurons suppresses nociception of inflammatory pain, the molecular mechanism of which remains unclear. Here, we report that the noxious stimulus receptor TRPV1 is an ionotropic oxytocin receptor. Oxytocin elicits TRPV1 activity in native and heterologous expression systems, regardless of the presence of the classical oxytocin receptor. In TRPV1 knockout mice, DRG neurons exhibit reduced oxytocin sensitivity relative to controls, and oxytocin injections significantly attenuate capsaicin-induced nociception in in vivo experiments. Furthermore, oxytocin potentiates TRPV1 in planar lipid bilayers, supporting a direct agonistic action. Molecular modeling and simulation experiments provide insight into oxytocin-TRPV1 interactions, which resemble DkTx. Together, our findings suggest the existence of endogenous regulatory pathways that modulate nociception via direct action of oxytocin on TRPV1, implying its analgesic effect via channel desensitization.

  9. The putative glutamate receptor 1.1 (AtGLR1.1) in Arabidopsis thaliana regulates abscisic acid biosynthesis and signaling to control development and water loss.

    Science.gov (United States)

    Kang, Jiman; Mehta, Sohum; Turano, Frank J

    2004-10-01

    The involvement of the putative glutamate receptor 1.1 (AtGLR1.1) gene in the regulation of abscisic acid (ABA) biosynthesis and signaling was investigated in Arabidopsis. Seeds from AtGLR1.1-deficient (antiAtGLR1.1) lines had increased sensitivity to exogenous ABA with regard to the effect of the hormone on the inhibition of seed germination and root growth. Seed germination, which was inhibited by an animal ionotropic glutamate receptor antagonist, 6,7-dinitroquinoxaline-2,3-[1H,4H]-dione, was restored by co-incubation with an inhibitor of ABA biosynthesis, fluridone. These results confirm that germination in antiAtGLR1.1 lines was inhibited by increased ABA. When antiAtGLR1.1 and WT seeds were co-incubated in fluridone and exogenous ABA, the antiAtGLR1.1 seeds were more sensitive to ABA. In addition, the antiAtGLR1.1 lines exhibited altered expression of ABA biosynthetic (ABA) and signaling (ABI) genes, when compared with WT. Combining the physiological and molecular results suggest that ABA biosynthesis and signaling in antiAtGLR1.1 lines are altered. ABA levels in leaves of antiAtGLR1.1 lines are higher than those in WT. In addition, the antiAtGLR1.1 lines had reduced stomatal apertures, and exhibited enhanced drought tolerance due to deceased water loss compared with WT lines. The results from these experiments imply that ABA biosynthesis and signaling can be regulated through AtGLR1.1 to trigger pre- and post-germination arrest and changes in whole plant responses to water stress. Combined with our earlier results, these findings suggest that AtGLR1.1 integrates and regulates the different aspects of C, N and water balance that are required for normal plant growth and development.

  10. Insulin receptors

    International Nuclear Information System (INIS)

    Kahn, C.R.; Harrison, L.C.

    1988-01-01

    This book contains the proceedings on insulin receptors. Part A: Methods for the study of structure and function. Topics covered include: Method for purification and labeling of insulin receptors, the insulin receptor kinase, and insulin receptors on special tissues

  11. Coping with dehydration: sympathetic activation and regulation of glutamatergic transmission in the hypothalamic PVN

    Science.gov (United States)

    Bardgett, Megan E.; Chen, Qing-Hui; Guo, Qing; Calderon, Alfredo S.; Andrade, Mary Ann

    2014-01-01

    Autonomic and endocrine profiles of chronic hypertension and heart failure resemble those of acute dehydration. Importantly, all of these conditions are associated with exaggerated sympathetic nerve activity (SNA) driven by glutamatergic activation of the hypothalamic paraventricular nucleus (PVN). Here, studies sought to gain insight into mechanisms of disease by determining the role of PVN ionotropic glutamate receptors in supporting SNA and mean arterial pressure (MAP) during dehydration and by elucidating mechanisms regulating receptor activity. Blockade of PVN N-methyl-d-aspartate (NMDA) receptors reduced (P dehydrated (DH) (48 h water deprivation) rats, but had no effect in euhydrated (EH) controls. Blockade of PVN α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors had no effect in either group. NMDA in PVN caused dose-dependent increases of renal SNA and MAP in both groups, but the maximum agonist evoked response (Emax) of the renal SNA response was greater (P dehydration increases excitatory NMDA receptor tone in PVN. Reduced glial-mediated glutamate uptake was identified as a key contributing factor. Defective glutamate uptake in PVN could therefore be an important, but as yet unexplored, mechanism driving sympathetic hyperactivity in chronic cardiovascular diseases. PMID:24671240

  12. The evolutionary origin of the need to sleep: an inevitable consequence of synaptic neurotransmission?

    Science.gov (United States)

    Cantor, Robert S

    2015-01-01

    It is proposed that the evolutionary origin of the need to sleep is the removal of neurotransmitters (NTs) that escape reuptake and accumulate in brain interstitial fluid (ISF). Recent work suggests that the activity of ionotropic postsynaptic receptors, rapidly initiated by binding of NTs to extracellular sites, is modulated over longer times by adsorption of these NTs to the lipid bilayers in which the receptors are embedded. This bilayer-mediated mechanism is far less molecularly specific than binding, so bilayer adsorption of NTs that have diffused into synapses for other receptors would modulate their activity as well. Although NTs are recycled by membrane protein reuptake, the process is less than 100% efficient; a fraction escapes the region in which these specific reuptake proteins are localized and eventually diffuses throughout the ISF. It is estimated that even if only 0.1% of NTs escape reuptake, they would accumulate and adsorb to bilayers in synapses of other receptors sufficiently to affect receptor activity, the harmful consequences of which are avoided by sleep: a period of efficient convective clearance of solutes together with greatly reduced synaptic activity.

  13. The evolutionary origin of the need to sleep: An inevitable consequence of synaptic neurotransmission?

    Directory of Open Access Journals (Sweden)

    Robert S. Cantor

    2015-09-01

    Full Text Available It is proposed that the evolutionary origin of the need to sleep is the removal of neurotransmitters (NTs that escape reuptake and accumulate in brain interstitial fluid. Recent work suggests that the activity of ionotropic postsynaptic receptors, rapidly initiated by binding of NTs to extracellular sites, is modulated over longer times by adsorption of these NTs to the lipid bilayers in which the receptors are embedded. This bilayer-mediated mechanism is far less molecularly specific than binding, so bilayer adsorption of NTs that have diffused into synapses for other receptors would modulate their activity as well. Although NTs are recycled by membrane protein reuptake, the process is less than 100% efficient; a fraction escapes the region in which these specific reuptake proteins are localized and eventually diffuses throughout the interstitial fluid. It is estimated that even if only 0.1% of NTs escape reuptake, they would accumulate and adsorb to bilayers in synapses of other receptors sufficiently to affect receptor activity, the harmful consequences of which are avoided by sleep: a period of efficient convective clearance of solutes together with greatly reduced synaptic activity.

  14. High-resolution immunogold localization of AMPA type glutamate receptor subunits at synaptic and non-synaptic sites in rat hippocampus.

    Science.gov (United States)

    Baude, A; Nusser, Z; Molnár, E; McIlhinney, R A; Somogyi, P

    1995-12-01

    The cellular and subcellular localization of the GluRA, GluRB/C and GluRD subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) type glutamate receptor was determined in the rat hippocampus using polyclonal antipeptide antibodies in immunoperoxidase and immunogold procedures. For the localization of the GluRD subunit a new polyclonal antiserum was developed using the C-terminal sequence of the protein (residues 869-881), conjugated to carrier protein and absorbed to colloidal gold for immunization. The purified antibodies immunoprecipitated about 25% of 3[H]AMPA binding activity from the hippocampus, cerebellum or whole brain, but very little from neocortex. These antibodies did not precipitate a significant amount of 3[H]kainate binding activity. The antibodies also recognize the GluRD subunit, but not the other AMPA receptor subunits, when expressed in transfected COS-7 cells and only when permeabilized with detergent, indicating an intracellular epitope. All subunits were enriched in the neuropil of the dendritic layers of the hippocampus and in the molecular layer of the dentate gyrus. The cellular distribution of the GluRD subunit was studied more extensively. The strata radiatum, oriens and the dentate molecular layer were more strongly immunoreactive than the stratum lacunosum moleculare, the stratum lucidum and the hilus. However, in the stratum lucidum of the CA3 area and in the hilus the weakly reacting dendrites were surrounded by immunopositive rosettes, shown in subsequent electron microscopic studies to correspond to complex dendritic spines. In the stratum radiatum, the weakly reacting apical dendrites contrasted with the surrounding intensely stained neuropil. The cell bodies of pyramidal and granule cells were moderately reactive. Some non-principal cells and their dendrites in the pyramidal cell layer and in the alveus also reacted very strongly for the GluRD subunit. At the subcellular level, silver intensified immunogold

  15. Sleep Control, GPCRs, and Glucose Metabolism.

    Science.gov (United States)

    Tsuneki, Hiroshi; Sasaoka, Toshiyasu; Sakurai, Takeshi

    2016-09-01

    Modern lifestyles prolong daily activities into the nighttime, disrupting circadian rhythms, which may cause sleep disturbances. Sleep disturbances have been implicated in the dysregulation of blood glucose levels and reported to increase the risk of type 2 diabetes (T2D) and diabetic complications. Sleep disorders are treated using anti-insomnia drugs that target ionotropic and G protein-coupled receptors (GPCRs), including γ-aminobutyric acid (GABA) agonists, melatonin agonists, and orexin receptor antagonists. A deeper understanding of the effects of these medications on glucose metabolism and their underlying mechanisms of action is crucial for the treatment of diabetic patients with sleep disorders. In this review we focus on the beneficial impact of sleep on glucose metabolism and suggest a possible strategy for therapeutic intervention against sleep-related metabolic disorders. Copyright © 2016. Published by Elsevier Ltd.

  16. NMDA receptor activation upstream of methyl farnesoate signaling for short day-induced male offspring production in the water flea, Daphnia pulex.

    Science.gov (United States)

    Toyota, Kenji; Miyakawa, Hitoshi; Yamaguchi, Katsushi; Shigenobu, Shuji; Ogino, Yukiko; Tatarazako, Norihisa; Miyagawa, Shinichi; Iguchi, Taisen

    2015-03-14

    The cladoceran crustacean Daphnia pulex produces female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable external stimuli, it produces male offspring (environmental sex determination: ESD). We recently established an innovative system for ESD studies using D. pulex WTN6 strain, in which the sex of the offspring can be controlled simply by changes in the photoperiod: the long-day and short-day conditions can induce female and male offspring, respectively. Taking advantage of this system, we demonstrated that de novo methyl farnesoate (MF) synthesis is necessary for male offspring production. These results indicate the key role of innate MF signaling as a conductor between external environmental stimuli and the endogenous male developmental pathway. Despite these findings, the molecular mechanisms underlying up- and downstream signaling of MF have not yet been well elucidated in D. pulex. To elucidate up- and downstream events of MF signaling during sex determination processes, we compared the transcriptomes of daphnids reared under the long-day (female) condition with short-day (male) and MF-treated (male) conditions. We found that genes involved in ionotropic glutamate receptors, known to mediate the vast majority of excitatory neurotransmitting processes in various organisms, were significantly activated in daphnids by the short-day condition but not by MF treatment. Administration of specific agonists and antagonists, especially for the N-methyl-D-aspartic acid (NMDA) receptor, strongly increased or decreased, respectively, the proportion of male-producing mothers. Moreover, we also identified genes responsible for male production (e.g., protein kinase C pathway-related genes). Such genes were generally shared between the short-day reared and MF-treated daphnids. We identified several candidate genes regulating ESD which strongly suggests that these genes may be essential factors for male offspring production as an

  17. The interleukin-4 receptor: signal transduction by a hematopoietin receptor.

    Science.gov (United States)

    Keegan, A D; Pierce, J H

    1994-02-01

    Over the last several years, the receptors for numerous cytokines have been molecularly characterized. Analysis of their amino acid sequences shows that some of these receptors bear certain motifs in their extracellular domains that define a family of receptors called the Hematopoietin receptor superfamily. Significant advances in characterizing the structure, function, and mechanisms of signal transduction have been made for several members of this family. The purpose of this review is to discuss the recent advances made for one of the family members, the interleukin (IL) 4 receptor. Other receptor systems have recently been reviewed elsewhere. The IL-4 receptor consists of, at the minimum, the cloned 140 kDa IL-4-binding chain with the potential for associating with other chains. The IL-4 receptor transduces its signal by activating a tyrosine kinase that phosphorylates cellular substrates, including the receptor itself, and the 170 kDa substrate called 4PS. Phosphorylated 4PS interacts with the SH2 domain of the enzyme PI-3'-kinase and increases its enzymatic activity. These early events in the IL-4 receptor initiated signaling pathway may trigger a series of signals that will ultimately lead to an IL-4 specific biologic outcome.

  18. The number and distribution of AMPA receptor channels containing fast kinetic GluA3 and GluA4 subunits at auditory nerve synapses depend on the target cells.

    Science.gov (United States)

    Rubio, María E; Matsui, Ko; Fukazawa, Yugo; Kamasawa, Naomi; Harada, Harumi; Itakura, Makoto; Molnár, Elek; Abe, Manabu; Sakimura, Kenji; Shigemoto, Ryuichi

    2017-11-01

    The neurotransmitter receptor subtype, number, density, and distribution relative to the location of transmitter release sites are key determinants of signal transmission. AMPA-type ionotropic glutamate receptors (AMPARs) containing GluA3 and GluA4 subunits are prominently expressed in subsets of neurons capable of firing action potentials at high frequencies, such as auditory relay neurons. The auditory nerve (AN) forms glutamatergic synapses on two types of relay neurons, bushy cells (BCs) and fusiform cells (FCs) of the cochlear nucleus. AN-BC and AN-FC synapses have distinct kinetics; thus, we investigated whether the number, density, and localization of GluA3 and GluA4 subunits in these synapses are differentially organized using quantitative freeze-fracture replica immunogold labeling. We identify a positive correlation between the number of AMPARs and the size of AN-BC and AN-FC synapses. Both types of AN synapses have similar numbers of AMPARs; however, the AN-BC have a higher density of AMPARs than AN-FC synapses, because the AN-BC synapses are smaller. A higher number and density of GluA3 subunits are observed at AN-BC synapses, whereas a higher number and density of GluA4 subunits are observed at AN-FC synapses. The intrasynaptic distribution of immunogold labeling revealed that AMPAR subunits, particularly GluA3, are concentrated at the center of the AN-BC synapses. The central distribution of AMPARs is absent in GluA3-knockout mice, and gold particles are evenly distributed along the postsynaptic density. GluA4 gold labeling was homogenously distributed along both synapse types. Thus, GluA3 and GluA4 subunits are distributed at AN synapses in a target-cell-dependent manner.

  19. The LDL receptor.

    Science.gov (United States)

    Goldstein, Joseph L; Brown, Michael S

    2009-04-01

    In this article, the history of the LDL receptor is recounted by its codiscoverers. Their early work on the LDL receptor explained a genetic cause of heart attacks and led to new ways of thinking about cholesterol metabolism. The LDL receptor discovery also introduced three general concepts to cell biology: receptor-mediated endocytosis, receptor recycling, and feedback regulation of receptors. The latter concept provides the mechanism by which statins selectively lower plasma LDL, reducing heart attacks and prolonging life.

  20. Transition from androgenic to neurosteroidal action of 5α-androstane-3α, 17β-diol through the type A γ-aminobutyric acid receptor in prostate cancer progression.

    Science.gov (United States)

    Xia, Ding; Lai, Doan V; Wu, Weijuan; Webb, Zachary D; Yang, Qing; Zhao, Lichao; Yu, Zhongxin; Thorpe, Jessica E; Disch, Bryan C; Ihnat, Michael A; Jayaraman, Muralidharan; Dhanasekaran, Danny N; Stratton, Kelly L; Cookson, Michael S; Fung, Kar-Ming; Lin, Hsueh-Kung

    2018-04-01

    Androgen ablation is the standard of care prescribed to patients with advanced or metastatic prostate cancer (PCa) to slow down disease progression. Unfortunately, a majority of PCa patients under androgen ablation progress to castration-resistant prostate cancer (CRPC). Several mechanisms including alternative intra-prostatic androgen production and androgen-independent androgen receptor (AR) activation have been proposed for CRPC progression. Aldo-keto reductase family 1 member C3 (AKR1C3), a multi-functional steroid metabolizing enzyme, is specifically expressed in the cytoplasm of PCa cells; and positive immunoreactivity of the type A γ-aminobutyric acid receptor (GABA A R), an ionotropic receptor and ligand-gated ion channel, is detected on the membrane of PCa cells. We studied a total of 72 radical prostatectomy cases by immunohistochemistry, and identified that 21 cases exhibited positive immunoreactivities for both AKR1C3 and GABA A R. In the dual positive cancer cases, AKR1C3 and GABA A R subunit α 1 were either expressed in the same cells or in neighboring cells. Among several possible substrates, AKR1C3 reduces 5α-dihydrotesterone (DHT) to form 5α-androstane-3α, 17β-diol (3α-diol). 3α-diol is a neurosteroid that acts as a positive allosteric modulator of the GABA A R in the central nervous system (CNS). We examined the hypothesis that 3α-diol-regulated pathological effects in the prostate are GABA A R-dependent, but are independent of the AR. In GABA A R-positive, AR-negative human PCa PC-3 cells, 3α-diol significantly stimulated cell growth in culture and the in ovo chorioallantoic membrane (CAM) xenograft model. 3α-diol also up-regulated expression of the epidermal growth factor (EGF) family of growth factors and activation of EGF receptor (EGFR) and Src as measured by quantitative polymerase chain reaction and immunoblotting, respectively. Inclusion of GABA A R antagonists reversed 3α-diol-stimulated tumor cell growth, expression of EGF

  1. Preparation and in vitro evaluation of amoxicillin encapsulated in ...

    African Journals Online (AJOL)

    Methods: Eighteen batches of various ratios of chitosan, sodium alginate and calcium chloride were ... emulsion, ionotropic gelation or reverse micellar methods. The method used here is ionotropic gelation method ... washed twice with distilled water and used for ..... Characterization of insulin-loaded alginate nanoparticles.

  2. The DLGAP family

    DEFF Research Database (Denmark)

    Rasmussen, Andreas H; Rasmussen, Hanne B; Silahtaroglu, Asli

    2017-01-01

    downstream signalling in the neuron. The postsynaptic density, a highly specialized matrix, which is attached to the postsynaptic membrane, controls this downstream signalling. The postsynaptic density also resets the synapse after each synaptic firing. It is composed of numerous proteins including a family...... in the postsynapse, the DLGAP family seems to play a vital role in synaptic scaling by regulating the turnover of both ionotropic and metabotropic glutamate receptors in response to synaptic activity. DLGAP family has been directly linked to a variety of psychological and neurological disorders. In this review we...... focus on the direct and indirect role of DLGAP family on schizophrenia as well as other brain diseases....

  3. 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

  4. Immunocytochemical analysis of P2X2 in rat circumvallate taste buds.

    Science.gov (United States)

    Yang, Ruibiao; Montoya, Alana; Bond, Amanda; Walton, Jenna; Kinnamon, John C

    2012-05-23

    Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3). P2X2/P2X3(Dbl-/-) mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP(3)R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, "atypical" mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis that ATP may be a key neurotransmitter in taste transduction

  5. Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors

    DEFF Research Database (Denmark)

    Xiong, Xiaofeng; Poulsen, Mette H; Hussein, Rama A

    2014-01-01

    The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only...

  6. Notch1 regulates hippocampal plasticity through interaction with the Reelin pathway, glutamatergic transmission and CREB signaling

    Directory of Open Access Journals (Sweden)

    Emanuele eBrai

    2015-11-01

    Full Text Available Notch signaling plays a crucial role in adult brain function such as synaptic plasticity, memory and olfaction. Several reports suggest an involvement of this pathway in neurodegenerative dementia. Yet, to date, the mechanism underlying Notch activity in mature neurons remains unresolved. In this work, we investigate how Notch regulates synaptic potentiation and contributes to the establishment of memory in mice. We observe that Notch1 is a postsynaptic receptor with functional interactions with the Reelin receptor, ApoER2, and the ionotropic receptor, NMDAR. Targeted loss of Notch1 in the hippocampal CA fields affects Reelin signaling by influencing Dab1 expression and impairs the synaptic potentiation achieved through Reelin stimulation. Further analysis indicates that loss of Notch1 affects the expression and composition of the NMDAR but not AMPAR. Glutamatergic signaling is further compromised through downregulation of CamKII and its secondary and tertiary messengers resulting in reduced CREB signaling. Our results identify Notch1 as an important regulator of mechanisms involved in synaptic plasticity and memory formation. These findings emphasize the possible involvement of this signaling receptor in dementia.

  7. Quantitative receptor radioautography in the study of receptor-receptor interactions in the nucleus tractus solitarii

    Directory of Open Access Journals (Sweden)

    Fior-Chadi D.R.

    1998-01-01

    Full Text Available The nucleus tractus solitarii (NTS in the dorsomedial medulla comprises a wide range of neuropeptides and biogenic amines. Several of them are related to mechanisms of central blood pressure control. Angiotensin II (Ang II, neuropeptide Y (NPY and noradrenaline (NA are found in the NTS cells, as well as their receptors. Based on this observation we have evaluated the modulatory effect of these peptide receptors on a2-adrenoceptors in the NTS. Using quantitative receptor radioautography, we observed that NPY and Ang II receptors decreased the affinity of a2-adrenoceptors for their agonists in the NTS of the rat. Cardiovascular experiments agreed with the in vitro data. Coinjection of a threshold dose of Ang II or of the NPY agonists together with an ED50 dose of adrenergic agonists such as NA, adrenaline and clonidine counteracted the depressor effect produced by the a2-agonist in the NTS. The results provide evidence for the existence of an antagonistic interaction between Ang II at1 receptors and NPY receptor subtypes with the a2-adrenoceptors in the NTS. This receptor interaction may reduce the transduction over the a2-adrenoceptors which can be important in central cardiovascular regulation and in the development of hypertension

  8. Characterization, cell-surface expression and ligand-binding properties of different truncated N-terminal extracellular domains of the ionotropic glutamate receptor subunit GluR1.

    Science.gov (United States)

    McIlhinney, R A; Molnár, E

    1996-04-01

    To identify the location of the first transmembrane segment of the GluR1 glutamate receptor subunit artificial stop codons have been introduced into the N-terminal domain at amino acid positions 442, 510, and 563, namely just before and spanning the proposed first two transmembrane regions. The resultant truncated N-terminal fragments of GluR1, termed NT1, NT2, and NT3 respectively were expressed in Cos-7 cells and their cellular distribution and cell-surface expression analysed using an N-terminal antibody to GluR1. All of the fragments were fully glycosylated and were found to be associated with cell membranes but none was secreted. Differential extraction of the cell membranes indicated that both NT1 and NT2 behave as peripheral membrane proteins. In contrast NT3, like the full subunit, has integral membrane protein properties. Furthermore only NT3 is expressed at the cell surface as determined by immunofluorescence and cell-surface biotinylation. Protease protection assays indicated that only NT3 had a cytoplasmic tail. Binding studies using the selective ligand [(3)H]alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate ([(3)H]AMPA) demonstrated that NT3 does not bind ligand. Together these results indicate that the first transmembrane domain of the GluR1 subunit lies between residues 509 and 562, that the N-terminal domain alone cannot form a functional ligand-binding site and that this domain can be targeted to the cell surface provided that it has a transmembrane-spanning region.

  9. Neonatal domoic acid decreases in vivo binding of [11C]yohimbine to α2 adrenoceptors in adult rat brain

    DEFF Research Database (Denmark)

    Thomsen, Majken; Lillethorup, Thea Pinholt; Jakobsen, Steen

    -quantitative analysis. MicroPET images were analyzed using PMOD software and registered to an average Sprague-Dawley rat MRI brain atlas to acquire data in limbic and cortical regions of interest. Results: In behavioural testing DOM60, and to a lesser extent DOM20 rats, spent more time in the periphery during the open......-Dawley rats (n=6-7 per group) were injected (s.c.) daily from postnatal day 8-14 with saline or one of two low sub-convulsive doses, 20µg/kg [DOM20] or 60µg/kg [DOM60] of DOM, an AMPA/kainate receptor agonist. The behaviour of the rats was observed in an open field test, a social interaction test...... and the forced swim test at day 50, 75 and 98, respectively. At ~120 days of age 3-4 rats per group were injected with [11C]yohimbine, an α2 adrenergic receptor antagonist, and scanned in a Mediso micro positron emission tomography (PET) scanner, to measure α2 adrenoceptor binding. The volume of distribution (VT...

  10. Characterization of neuronal intrinsic properties and synaptic transmission in layer I of anterior cingulate cortex from adult mice

    Directory of Open Access Journals (Sweden)

    Li Xiang-Yao

    2012-07-01

    Full Text Available Abstract The neurons in neocortex layer I (LI provide inhibition to the cortical networks. Despite increasing use of mice for the study of brain functions, few studies were reported about mouse LI neurons. In the present study, we characterized intrinsic properties of LI neurons of the anterior cingulate cortex (ACC, a key cortical area for sensory and cognitive functions, by using whole-cell patch clamp recording approach. Seventy one neurons in LI and 12 pyramidal neurons in LII/III were recorded. Although all of the LI neurons expressed continuous adapting firing characteristics, the unsupervised clustering results revealed five groups in the ACC, including: Spontaneous firing neurons; Delay-sAHP neurons, Delay-fAHP neurons, and two groups of neurons with ADP, named ADP1 and ADP2, respectively. Using pharmacological approaches, we found that LI neurons received both excitatory (mediated by AMPA, kainate and NMDA receptors, and inhibitory inputs (which were mediated by GABAA receptors. Our studies provide the first report characterizing the electrophysiological properties of neurons in LI of the ACC from adult mice.

  11. XMRV: usage of receptors and potential co-receptors

    Directory of Open Access Journals (Sweden)

    Gaddam Durga

    2011-09-01

    Full Text Available Abstract Background XMRV is a gammaretrovirus first identified in prostate tissues of Prostate Cancer (PC patients and later in the blood cells of patients with Chronic Fatigue Syndrome (CFS. Although XMRV is thought to use XPR1 for cell entry, it infects A549 cells that do not express XPR1, suggesting usage of other receptors or co-receptors. Methods To study the usage of different receptors and co- receptors that could play a role in XMRV infection of lymphoid cells and GHOST (GFP- Human osteosarcoma cells expressing CD4 along with different chemokine receptors including CCR1, CCR2, etc., were infected with XMRV. Culture supernatants and cells were tested for XMRV replication using real time quantitative PCR. Results Infection and replication of XMRV was seen in a variety of GHOST cells, LNCaP, DU145, A549 and Caski cell lines. The levels of XMRV replication varied in different cell lines showing differential replication in different cell lines. However, replication in A549 which lacks XPR1 expression was relatively higher than DU145 but lower than, LNCaP. XMRV replication varied in GHOST cell lines expressing CD4 and each of the co- receptors CCR1-CCR8 and bob. There was significant replication of XMRV in CCR3 and Bonzo although it is much lower when compared to DU145, A549 and LNCaP. Conclusion XMRV replication was observed in GHOST cells that express CD4 and each of the chemokine receptors ranging from CCR1- CCR8 and BOB suggesting that infectivity in hematopoietic cells could be mediated by use of these receptors.

  12. Radiolabeling of [18F]-fluoroethylnormemantine and initial in vivo evaluation of this innovative PET tracer for imaging the PCP sites of NMDA receptors

    International Nuclear Information System (INIS)

    Salabert, Anne-Sophie; Fonta, Caroline; Fontan, Charlotte; Adel, Djilali; Alonso, Mathieu; Pestourie, Carine; Belhadj-Tahar, Hafid; Tafani, Mathieu; Payoux, Pierre

    2015-01-01

    Introduction: The N-methyl-D-aspartate receptor (NMDAr) is an ionotropic receptor that mediates excitatory transmission. NMDAr overexcitation is thought to be involved in neurological and neuropsychiatric disorders such as Alzheimer disease and schizophrenia. We synthesized [ 18 F]-fluoroethylnormemantine ([ 18 F]-FNM), a memantine derivative that binds to phencyclidine (PCP) sites within the NMDA channel pore. These sites are primarily accessible when the channel is in the active and open state. Methods: Radiosynthesis was carried out using the Raytest® SynChrom R&D fluorination module. Affinity of this new compound was determined by competition assay. We ran a kinetic study in rats and computed a time–activity curve based on a volume-of-interest analysis, using CARIMAS® software. We performed an ex vivo autoradiography, exposing frozen rat brain sections to a phosphorscreen. Adjacent sections were used to detect NMDAr by immunohistochemistry with an anti-NR1 antibody. As a control of the specificity of our compound for NMDAr, we used a rat anesthetized with ketamine. Correlation analysis was performed with ImageJ software between signal of autoradiography and immunostaining. Results: Fluorination yield was 10.5% (end of synthesis), with a mean activity of 3145 MBq and a specific activity above 355 GBq/μmol. Affinity assessment allowed us to determine [ 19 F]-FNM IC50 at 6.1 10 −6 M. [ 18 F]-FMN concentration gradually increased in the brain, stabilizing at 40 minutes post injection. The brain-to-blood ratio was 6, and 0.4% of the injected dose was found in the brain. Combined ex vivo autoradiography and immunohistochemical staining demonstrated colocalization of NMDAr and [ 18 F]-FNM (r = 0.622, p < 0.0001). The highest intensity was found in the cortex and cerebellum, and the lowest in white matter. A low and homogeneous signal corresponding to unspecific binding was observed when PCP sites were blocked with ketamine. Conclusions: [ 18 F]-FNM appears to

  13. GABA receptor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Doo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA{sub A}-receptor that allows chloride to pass through a ligand gated ion channel and GABA{sub B}-receptor that uses G-proteins for signaling. The GABA{sub A}-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA{sub A}-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with {sup 11}C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, {sup 18}F-fluoroflumazenil (FFMZ) has been developed to overcome {sup 11}C's short half-life. {sup 18}F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1{sup 1}C-FMZ PET instead of {sup 18}F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA{sub A} receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

  14. GABA receptor imaging

    International Nuclear Information System (INIS)

    Lee, Jong Doo

    2007-01-01

    GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA A -receptor that allows chloride to pass through a ligand gated ion channel and GABA B -receptor that uses G-proteins for signaling. The GABA A -receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA A -receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with 11 C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, 18 F-fluoroflumazenil (FFMZ) has been developed to overcome 11 C's short half-life. 18 F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1 1 C-FMZ PET instead of 18 F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA A receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas

  15. Identification of chemosensory genes from the antennal transcriptome of Indian meal moth Plodia interpunctella.

    Directory of Open Access Journals (Sweden)

    Xiaojian Jia

    Full Text Available Olfaction plays an indispensable role in mediating insect behavior, such as locating host plants, mating partners, and avoidance of toxins and predators. Olfactory-related proteins are required for olfactory perception of insects. However, very few olfactory-related genes have been reported in Plodia interpunctella up to now. In the present study, we sequenced the antennae transcriptome of P. interpunctella using the next-generation sequencing technology, and identified 117 candidate olfactory-related genes, including 29 odorant-binding proteins (OBPs, 15 chemosensory proteins (CSPs, three sensory neuron membrane proteins (SNMPs, 47 odorant receptors (ORs, 14 ionotropic receptors (IRs and nine gustatory receptors (GRs. Further analysis of qRT-PCR revealed that nine OBPs, three CSPs, two SNMPs, nine ORs and two GRs were specifically expressed in the male antennae, whereas eight OBPs, six CSPs, one SNMP, 16 ORs, two GRs and seven IRs significantly expressed in the female antennae. Taken together, our results provided useful information for further functional studies on insect genes related to recognition of pheromone and odorant, which might be meaningful targets for pest management.

  16. Identification of chemosensory genes from the antennal transcriptome of Indian meal moth Plodia interpunctella.

    Science.gov (United States)

    Jia, Xiaojian; Zhang, Xiaofang; Liu, Hongmin; Wang, Rongyan; Zhang, Tao

    2018-01-01

    Olfaction plays an indispensable role in mediating insect behavior, such as locating host plants, mating partners, and avoidance of toxins and predators. Olfactory-related proteins are required for olfactory perception of insects. However, very few olfactory-related genes have been reported in Plodia interpunctella up to now. In the present study, we sequenced the antennae transcriptome of P. interpunctella using the next-generation sequencing technology, and identified 117 candidate olfactory-related genes, including 29 odorant-binding proteins (OBPs), 15 chemosensory proteins (CSPs), three sensory neuron membrane proteins (SNMPs), 47 odorant receptors (ORs), 14 ionotropic receptors (IRs) and nine gustatory receptors (GRs). Further analysis of qRT-PCR revealed that nine OBPs, three CSPs, two SNMPs, nine ORs and two GRs were specifically expressed in the male antennae, whereas eight OBPs, six CSPs, one SNMP, 16 ORs, two GRs and seven IRs significantly expressed in the female antennae. Taken together, our results provided useful information for further functional studies on insect genes related to recognition of pheromone and odorant, which might be meaningful targets for pest management.

  17. The two-state dimer receptor model: a general model for receptor dimers.

    Science.gov (United States)

    Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferrada, Carla; Ferré, Sergi; Fuxe, Kjell; Cortés, Antoni; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

    2006-06-01

    Nonlinear Scatchard plots are often found for agonist binding to G-protein-coupled receptors. Because there is clear evidence of receptor dimerization, these nonlinear Scatchard plots can reflect cooperativity on agonist binding to the two binding sites in the dimer. According to this, the "two-state dimer receptor model" has been recently derived. In this article, the performance of the model has been analyzed in fitting data of agonist binding to A(1) adenosine receptors, which are an example of receptor displaying concave downward Scatchard plots. Analysis of agonist/antagonist competition data for dopamine D(1) receptors using the two-state dimer receptor model has also been performed. Although fitting to the two-state dimer receptor model was similar to the fitting to the "two-independent-site receptor model", the former is simpler, and a discrimination test selects the two-state dimer receptor model as the best. This model was also very robust in fitting data of estrogen binding to the estrogen receptor, for which Scatchard plots are concave upward. On the one hand, the model would predict the already demonstrated existence of estrogen receptor dimers. On the other hand, the model would predict that concave upward Scatchard plots reflect positive cooperativity, which can be neither predicted nor explained by assuming the existence of two different affinity states. In summary, the two-state dimer receptor model is good for fitting data of binding to dimeric receptors displaying either linear, concave upward, or concave downward Scatchard plots.

  18. Azetidinic amino acids

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Bunch, Lennart; Chopin, Nathalie

    2005-01-01

    A set of ten azetidinic amino acids, that can be envisioned as C-4 alkyl substituted analogues of trans-2-carboxyazetidine-3-acetic acid (t-CAA) and/or conformationally constrained analogues of (R)- or (S)-glutamic acid (Glu) have been synthesized in a diastereo- and enantiomerically pure form from...... of two diastereoisomers that were easily separated and converted in two steps into azetidinic amino acids. Azetidines 35-44 were characterized in binding studies on native ionotropic Glu receptors and in functional assays at cloned metabotropic receptors mGluR1, 2 and 4, representing group I, II and III...... beta-amino alcohols through a straightforward five step sequence. The key step of this synthesis is an original anionic 4-exo-tet ring closure that forms the azetidine ring upon an intramolecular Michael addition. This reaction was proven to be reversible and to lead to a thermodynamic distribution...

  19. Roles and regulation of brain glutamate transporters in normal and pathological brain function

    International Nuclear Information System (INIS)

    O'Shea, R.D.

    2001-01-01

    Full text: Glutamate (Glu) is the major excitatory neurotransmitter in the mammalian CNS. Synaptically released Glu acts on both ionotropic (iGluR) and metabotropic receptors, and excessive iGluR activation results in neuronal death (termed excitotoxicity). Removal of Glu from the synapse is thus critical for normal transmission and to prevent excitotoxicity, and is performed exclusively by a family of excitatory amino acid transporters (EAATs, also known as glutamate transporters). Disregulation of Glu transport may contribute to the pathogenesis of many neurodegenerative conditions, and altered expression or function of EAATs has been identified in a number of these pathologies. These studies investigated the functional and pathological effects of EAAT inhibitors in vitro, and developed a novel screening assay for compounds with activity at EAATs. Astrocytic EAATs are responsible for the majority of Glu uptake in brain, so preparations containing both astrocytes and neurones are required to analyse the contribution of EAATs to neuroprotection. Organotypic hippocampal cultures (OHCs), which exhibit many of the features of the intact CNS, were prepared from 11-14 day old Sprague Dawley rats (anaesthetised with halothane). Hippocampal slices (350 μm thick) were maintained on culture well inserts in chemically defined medium. After 2 weeks, cultures were treated with EAAT inhibitors for 3-7 days in the presence or absence of 300 μM Glu. Treatment with most EAAT inhibitors resulted in cell death that was proportional to the Glu concentration in the medium. In contrast, (2S,3S,4R)-2-(carboxycyclopropyl)glycine (L-CCG-III), a competitive substrate at EAATs (and possibly an antagonist at the kainate subtype of iGluR), appeared to be neuroprotective: increased Glu was not toxic in the presence of this drug. These results demonstrate the sensitivity of OHCs to inhibition of Glu uptake, highlighting the importance of EAATs in preventing excitotoxicity. Since modulation of

  20. Preparation and in vitro evaluation of amoxicillin encapsulated in ...

    African Journals Online (AJOL)

    emulsion, ionotropic gelation or reverse micellar methods. The method used here is ionotropic gelation ... and deionized water (National Commission for. Energy Research and Development, University of Nigeria ... washed twice with distilled water and used for the particle size determination. A thin smear was made on a ...

  1. Receptor oligomerization in family B1 of G-protein-coupled receptors

    DEFF Research Database (Denmark)

    Roed, Sarah Norklit; Ørgaard, Anne; Jørgensen, Rasmus

    2012-01-01

    , the glucagon receptor, and the receptors for parathyroid hormone (PTHR1 and PTHR2). The dysregulation of several family B1 receptors is involved in diseases, such as diabetes, chronic inflammation, and osteoporosis which underlines the pathophysiological importance of this GPCR subfamily. In spite of this......, investigation of family B1 receptor oligomerization and especially its pharmacological importance is still at an early stage. Even though GPCR oligomerization is a well-established phenomenon, there is a need for more investigations providing a direct link between these interactions and receptor functionality......The superfamily of the seven transmembrane G-protein-coupled receptors (7TM/GPCRs) is the largest family of membrane-associated receptors. GPCRs are involved in the pathophysiology of numerous human diseases, and they constitute an estimated 30-40% of all drug targets. During the last two decades...

  2. Activation of glucocorticoid receptors increases 5-HT2A receptor levels

    DEFF Research Database (Denmark)

    Trajkovska, Viktorija; Kirkegaard, Lisbeth; Krey, Gesa

    2009-01-01

    an effect of GR activation on 5-HT2A levels, mature organotypic hippocampal cultures were exposed to corticosterone with or without GR antagonist mifepristone and mineralocorticoid receptor (MR) antagonist spironolactone. In GR under-expressing mice, hippocampal 5-HT2A receptor protein levels were decreased......Major depression is associated with both dysregulation of the hypothalamic pituitary adrenal axis and serotonergic deficiency, not the least of the 5-HT2A receptor. However, how these phenomena are linked to each other, and whether a low 5-HT2A receptor level is a state or a trait marker...... of depression is unknown. In mice with altered glucocorticoid receptor (GR) expression we investigated 5-HT2A receptor levels by Western blot and 3H-MDL100907 receptor binding. Serotonin fibre density was analyzed by stereological quantification of serotonin transporter immunopositive fibers. To establish...

  3. Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation.

    Science.gov (United States)

    Ismael, Amber; Tian, Wei; Waszczak, Nicholas; Wang, Xin; Cao, Youfang; Suchkov, Dmitry; Bar, Eli; Metodiev, Metodi V; Liang, Jie; Arkowitz, Robert A; Stone, David E

    2016-04-12

    Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion. Copyright © 2016, American Association for the Advancement of Science.

  4. Glucocorticoid receptor modulators.

    Science.gov (United States)

    Meijer, Onno C; Koorneef, Lisa L; Kroon, Jan

    2018-06-01

    The glucocorticoid hormone cortisol acts throughout the body to support circadian processes and adaptation to stress. The glucocorticoid receptor is the target of cortisol and of synthetic glucocorticoids, which are used widely in the clinic. Both agonism and antagonism of the glucocorticoid receptor may be beneficial in disease, but given the wide expression of the receptor and involvement in various processes, beneficial effects are often accompanied by unwanted side effects. Selective glucocorticoid receptor modulators are ligands that induce a receptor conformation that allows activation of only a subset of downstream signaling pathways. Such molecules thereby combine agonistic and antagonistic properties. Here we discuss the mechanisms underlying selective receptor modulation and their promise in treating diseases in several organ systems where cortisol signaling plays a role. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  5. Angiotensin type 2 receptor (AT2R) and receptor Mas

    DEFF Research Database (Denmark)

    Villela, Daniel; Leonhardt, Julia; Patel, Neal

    2015-01-01

    The angiotensin type 2 receptor (AT2R) and the receptor Mas are components of the protective arms of the renin-angiotensin system (RAS), i.e. they both mediate tissue protective and regenerative actions. The spectrum of actions of these two receptors and their signalling mechanisms display striki...

  6. A search for presynaptic inhibitory histamine receptors in guinea-pig tissues: Further H3 receptors but no evidence for H4 receptors.

    Science.gov (United States)

    Petri, Doris; Schlicker, Eberhard

    2016-07-01

    The histamine H4 receptor is coupled to Gi/o proteins and expressed on inflammatory cells and lymphoid tissues; it was suggested that this receptor also occurs in the brain or on peripheral neurones. Since many Gi/o protein-coupled receptors, including the H3 receptor, serve as presynaptic inhibitory receptors, we studied whether the sympathetic neurones supplying four peripheral tissues and the cholinergic neurones in the hippocampus from the guinea-pig are equipped with release-modulating H4 and H3 receptors. For this purpose, we preincubated tissue pieces from the aorta, atrium, renal cortex and vas deferens with (3)H-noradrenaline and hippocampal slices with (3)H-choline and determined the electrically evoked tritium overflow. The stimulation-evoked overflow in the five superfused tissues was inhibited by the muscarinic receptor agonist oxotremorine, which served as a positive control, but not affected by the H4 receptor agonist 4-methylhistamine. The H3 receptor agonist R-α-methylhistamine inhibited noradrenaline release in the peripheral tissues without affecting acetylcholine release in the hippocampal slices. Thioperamide shifted the concentration-response curve of histamine in the aorta and the renal cortex to the right, yielding apparent pA2 values of 8.0 and 8.1, respectively, which are close to its affinity at other H3 receptors but higher by one log unit than its pKi at the H4 receptor of the guinea-pig. In conclusion, histamine H4 receptors could not be identified in five experimental models of the guinea-pig that are suited for the detection of presynaptic inhibitory receptors whereas H3 receptors could be shown in the peripheral tissues but not in the hippocampus. This article is part of the Special Issue entitled 'Histamine Receptors'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Real-Time G-Protein-Coupled Receptor Imaging to Understand and Quantify Receptor Dynamics

    Directory of Open Access Journals (Sweden)

    María S. Aymerich

    2011-01-01

    Full Text Available Understanding the trafficking of G-protein-coupled receptors (GPCRs and their regulation by agonists and antagonists is fundamental to develop more effective drugs. Optical methods using fluorescent-tagged receptors and spinning disk confocal microscopy are useful tools to investigate membrane receptor dynamics in living cells. The aim of this study was to develop a method to characterize receptor dynamics using this system which offers the advantage of very fast image acquisition with minimal cell perturbation. However, in short-term assays photobleaching was still a problem. Thus, we developed a procedure to perform a photobleaching-corrected image analysis. A study of short-term dynamics of the long isoform of the dopamine type 2 receptor revealed an agonist-induced increase in the mobile fraction of receptors with a rate of movement of 0.08 μm/s For long-term assays, the ratio between the relative fluorescence intensity at the cell surface versus that in the intracellular compartment indicated that receptor internalization only occurred in cells co-expressing G protein-coupled receptor kinase 2. These results indicate that the lateral movement of receptors and receptor internalization are not directly coupled. Thus, we believe that live imaging of GPCRs using spinning disk confocal image analysis constitutes a powerful tool to study of receptor dynamics.

  8. Knock-In Mice with NOP-eGFP Receptors Identify Receptor Cellular and Regional Localization.

    Science.gov (United States)

    Ozawa, Akihiko; Brunori, Gloria; Mercatelli, Daniela; Wu, Jinhua; Cippitelli, Andrea; Zou, Bende; Xie, Xinmin Simon; Williams, Melissa; Zaveri, Nurulain T; Low, Sarah; Scherrer, Grégory; Kieffer, Brigitte L; Toll, Lawrence

    2015-08-19

    The nociceptin/orphanin FQ (NOP) receptor, the fourth member of the opioid receptor family, is involved in many processes common to the opioid receptors including pain and drug abuse. To better characterize receptor location and trafficking, knock-in mice were created by inserting the gene encoding enhanced green fluorescent protein (eGFP) into the NOP receptor gene (Oprl1) and producing mice expressing a functional NOP-eGFP C-terminal fusion in place of the native NOP receptor. The NOP-eGFP receptor was present in brain of homozygous knock-in animals in concentrations somewhat higher than in wild-type mice and was functional when tested for stimulation of [(35)S]GTPγS binding in vitro and in patch-clamp electrophysiology in dorsal root ganglia (DRG) neurons and hippocampal slices. Inhibition of morphine analgesia was equivalent when tested in knock-in and wild-type mice. Imaging revealed detailed neuroanatomy in brain, spinal cord, and DRG and was generally consistent with in vitro autoradiographic imaging of receptor location. Multicolor immunohistochemistry identified cells coexpressing various spinal cord and DRG cellular markers, as well as coexpression with μ-opioid receptors in DRG and brain regions. Both in tissue slices and primary cultures, the NOP-eGFP receptors appear throughout the cell body and in processes. These knock-in mice have NOP receptors that function both in vitro and in vivo and appear to be an exceptional tool to study receptor neuroanatomy and correlate with NOP receptor function. The NOP receptor, the fourth member of the opioid receptor family, is involved in pain, drug abuse, and a number of other CNS processes. The regional and cellular distribution has been difficult to determine due to lack of validated antibodies for immunohistochemical analysis. To provide a new tool for the investigation of receptor localization, we have produced knock-in mice with a fluorescent-tagged NOP receptor in place of the native NOP receptor. These

  9. Receptor assay

    Energy Technology Data Exchange (ETDEWEB)

    Kato, K; Ibayashi, H [Kyushu Univ., Fukuoka (Japan). Faculty of Medicine

    1975-05-01

    This paper summarized present status and problems of analysis of hormone receptor and a few considerations on clinical significance of receptor abnormalities. It was pointed that in future clinical field quantitative and qualitative analysis of receptor did not remain only in the etiological discussion, but that it was an epoch-making field of investigation which contained the possiblity of artificial change of sensitivity of living body on drugs and the development connected directly with treatment of various diseases.

  10. Lateral presynaptic inhibition mediates gain control in an olfactory circuit.

    Science.gov (United States)

    Olsen, Shawn R; Wilson, Rachel I

    2008-04-24

    Olfactory signals are transduced by a large family of odorant receptor proteins, each of which corresponds to a unique glomerulus in the first olfactory relay of the brain. Crosstalk between glomeruli has been proposed to be important in olfactory processing, but it is not clear how these interactions shape the odour responses of second-order neurons. In the Drosophila antennal lobe (a region analogous to the vertebrate olfactory bulb), we selectively removed most interglomerular input to genetically identified second-order olfactory neurons. Here we show that this broadens the odour tuning of these neurons, implying that interglomerular inhibition dominates over interglomerular excitation. The strength of this inhibitory signal scales with total feedforward input to the entire antennal lobe, and has similar tuning in different glomeruli. A substantial portion of this interglomerular inhibition acts at a presynaptic locus, and our results imply that this is mediated by both ionotropic and metabotropic receptors on the same nerve terminal.

  11. Estradiol induces dendritic spines by enhancing glutamate release independent of transcription: A mechanism for organizational sex differences

    Science.gov (United States)

    Schwarz, Jaclyn M.; Liang, Shu-Ling; Thompson, Scott M.; McCarthy, Margaret M.

    2008-01-01

    SUMMARY The naturally occurring sex difference in dendritic spine number on hypothalamic neurons offers a unique opportunity to investigate mechanisms establishing synaptic patterning during perinatal sensitive periods. A major advantage of the model is the ability to treat neonatal females with estradiol to permanently induce the male phenotype. During the development of other systems, exuberant innervation is followed by activity-dependent pruning necessary for elimination of spurious synapses. In contrast, we demonstrate that estradiol-induced organization in the hypothalamus involves the induction of new synapses on dendritic spines. Activation of estrogen receptors by estradiol triggers a non-genomic activation of PI3 kinase that results in enhanced glutamate release from presynaptic neurons. Subsequent activation of ionotropic glutamate receptors activates MAP kinases inducing dendritic spine formation. These results reveal a trans-neuronal mechanism by which estradiol acts during a sensitive period to establish a profound and lasting sex difference in hypothalamic synaptic patterning. PMID:18498739

  12. Short-term ionic plasticity at GABAergic synapses

    Directory of Open Access Journals (Sweden)

    Joseph Valentino Raimondo

    2012-10-01

    Full Text Available Fast synaptic inhibition in the brain is mediated by the pre-synaptic release of the neurotransmitter γ-Aminobutyric acid (GABA and the post-synaptic activation of GABA-sensitive ionotropic receptors. As with excitatory synapses, it is being increasinly appreciated that a variety of plastic processes occur at inhibitory synapses, which operate over a range of timescales. Here we examine a form of activity-dependent plasticity that is somewhat unique to GABAergic transmission. This involves short-lasting changes to the ionic driving force for the postsynaptic receptors, a process referred to as short-term ionic plasticity. These changes are directly related to the history of activity at inhibitory synapses and are influenced by a variety of factors including the location of the synapse and the post-synaptic cell’s ion regulation mechanisms. We explore the processes underlying this form of plasticity, when and where it can occur, and how it is likely to impact network activity.

  13. Fast inhibition of glutamate-activated currents by caffeine.

    Directory of Open Access Journals (Sweden)

    Nicholas P Vyleta

    Full Text Available BACKGROUND: Caffeine stimulates calcium-induced calcium release (CICR in many cell types. In neurons, caffeine stimulates CICR presynaptically and thus modulates neurotransmitter release. METHODOLOGY/PRINCIPAL FINDINGS: Using the whole-cell patch-clamp technique we found that caffeine (20 mM reversibly increased the frequency and decreased the amplitude of miniature excitatory postsynaptic currents (mEPSCs in neocortical neurons. The increase in mEPSC frequency is consistent with a presynaptic mechanism. Caffeine also reduced exogenously applied glutamate-activated currents, confirming a separate postsynaptic action. This inhibition developed in tens of milliseconds, consistent with block of channel currents. Caffeine (20 mM did not reduce currents activated by exogenous NMDA, indicating that caffeine block is specific to non-NMDA type glutamate receptors. CONCLUSIONS/SIGNIFICANCE: Caffeine-induced inhibition of mEPSC amplitude occurs through postsynaptic block of non-NMDA type ionotropic glutamate receptors. Caffeine thus has both pre and postsynaptic sites of action at excitatory synapses.

  14. Calcitonin and calcitonin receptor-like receptors: common themes with family B GPCRs?

    Science.gov (United States)

    Barwell, James; Gingell, Joseph J; Watkins, Harriet A; Archbold, Julia K; Poyner, David R; Hay, Debbie L

    2012-05-01

    The calcitonin receptor (CTR) and calcitonin receptor-like receptor (CLR) are two of the 15 human family B (or Secretin-like) GPCRs. CTR and CLR are of considerable biological interest as their pharmacology is moulded by interactions with receptor activity-modifying proteins. They also have therapeutic relevance for many conditions, such as osteoporosis, diabetes, obesity, lymphatic insufficiency, migraine and cardiovascular disease. In light of recent advances in understanding ligand docking and receptor activation in both the family as a whole and in CLR and CTR specifically, this review reflects how applicable general family B GPCR themes are to these two idiosyncratic receptors. We review the main functional domains of the receptors; the N-terminal extracellular domain, the juxtamembrane domain and ligand interface, the transmembrane domain and the intracellular C-terminal domain. Structural and functional findings from the CLR and CTR along with other family B GPCRs are critically appraised to gain insight into how these domains may function. The ability for CTR and CLR to interact with receptor activity-modifying proteins adds another level of sophistication to these receptor systems but means careful consideration is needed when trying to apply generic GPCR principles. This review encapsulates current thinking in the realm of family B GPCR research by highlighting both conflicting and recurring themes and how such findings relate to two unusual but important receptors, CTR and CLR. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

  15. Molecular modeling of ligand-receptor interactions in the OR5 olfactory receptor.

    Science.gov (United States)

    Singer, M S; Shepherd, G M

    1994-06-02

    Olfactory receptors belong to the superfamily of seven transmembrane domain, G protein-coupled receptors. In order to begin analysis of mechanisms of receptor activation, a computer model of the OR5 olfactory receptor has been constructed and compared with other members of this superfamily. We have tested docking of the odor molecule lyral, which is known to activate the OR5 receptor. The results point to specific ligand-binding residues on helices III through VII that form a binding pocket in the receptor. Some of these residues occupy sequence positions identical to ligand-binding residues conserved among other superfamily members. The results provide new insights into possible molecular mechanisms of odor recognition and suggest hypotheses to guide future experimental studies using site-directed mutagenesis.

  16. Receptor downregulation and desensitization enhance the information processing ability of signalling receptors

    Directory of Open Access Journals (Sweden)

    Resat Haluk

    2007-11-01

    Full Text Available Abstract Background In addition to initiating signaling events, the activation of cell surface receptors also triggers regulatory processes that restrict the duration of signaling. Acute attenuation of signaling can be accomplished either via ligand-induced internalization of receptors (endocytic downregulation or via ligand-induced receptor desensitization. These phenomena have traditionally been viewed in the context of adaptation wherein the receptor system enters a refractory state in the presence of sustained ligand stimuli and thereby prevents the cell from over-responding to the ligand. Here we use the epidermal growth factor receptor (EGFR and G-protein coupled receptors (GPCR as model systems to respectively examine the effects of downregulation and desensitization on the ability of signaling receptors to decode time-varying ligand stimuli. Results Using a mathematical model, we show that downregulation and desensitization mechanisms can lead to tight and efficient input-output coupling thereby ensuring synchronous processing of ligand inputs. Frequency response analysis indicates that upstream elements of the EGFR and GPCR networks behave like low-pass filters with the system being able to faithfully transduce inputs below a critical frequency. Receptor downregulation and desensitization increase the filter bandwidth thereby enabling the receptor systems to decode inputs in a wider frequency range. Further, system-theoretic analysis reveals that the receptor systems are analogous to classical mechanical over-damped systems. This analogy enables us to metaphorically describe downregulation and desensitization as phenomena that make the systems more resilient in responding to ligand perturbations thereby improving the stability of the system resting state. Conclusion Our findings suggest that in addition to serving as mechanisms for adaptation, receptor downregulation and desensitization can play a critical role in temporal information

  17. Modulating Estrogen Receptor-related Receptor-α Activity Inhibits Cell Proliferation*

    OpenAIRE

    Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

    2009-01-01

    High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERR...

  18. Receptor binding properties and antinociceptive effects of chimeric peptides consisting of a micro-opioid receptor agonist and an ORL1 receptor antagonist.

    Science.gov (United States)

    Kawano, Susumu; Ito, Risa; Nishiyama, Miharu; Kubo, Mai; Matsushima, Tomoko; Minamisawa, Motoko; Ambo, Akihiro; Sasaki, Yusuke

    2007-07-01

    Receptor binding properties and antinociceptive activities of chimeric peptides linked by spacers were investigated. The peptides consisted of the micro-opioid receptor ligand dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH(2)) or its analog YRFB (Tyr-D-Arg-Phe-betaAla-NH(2)) linked to the ORL1 receptor ligand Ac-Arg-Tyr-Tyr-Arg-Ile-Lys-NH(2) (Ac-RYYRIK-NH(2)). All chimeric peptides were found to possess high receptor binding affinities for both micro-opioid and ORL1 receptors in mouse brain membranes although their binding affinities for both receptors in spinal membranes were significantly lower. Among them, chimeric peptide 2, which consists of dermorphin and Ac-RYYRIK-NH(2) connected by a long spacer, had the highest binding affinity towards both receptors. In the tail-flick test following intrathecal (i.t.) administration to mice, all chimeric peptides showed potent and dose-dependent antinociceptive activities with an ED(50) of 1.34-4.51 (pmol/mouse), nearly comparable to dermorphin alone (ED(50); 1.08 pmol/mouse). In contrast to their micro-opioid receptor binding profiles, intracerebroventricular (i.c.v.) administration of the chimeric peptides resulted in much less potent antinociceptive activity (ED(50) 5.55-100peptides, and the regulation of mu-opioid receptor-mediated antinociception in brain. The present chimeric peptides may be useful as pharmacological tools for studies on micro-opioid receptor/ORL1 receptor heterodimers.

  19. Regulation of neurosteroid biosynthesis by neurotransmitters and neuropeptides

    Directory of Open Access Journals (Sweden)

    Jean-Luc eDo-Rego

    2012-01-01

    Full Text Available The enzymatic pathways leading to the synthesis of bioactive steroids in the brain are now almost completely elucidated in various groups of vertebrates and, during the last decade, the neuronal mechanisms involved in the regulation of neurosteroid production have received increasing attention. This report reviews the current knowledge concerning the effects of neurotransmitters, peptide hormones and neuropeptides on the biosynthesis of neurosteroids. Anatomical studies have been carried out to visualize the neurotransmitter- or neuropeptide-containing fibers contacting steroid-synthesizing neurons as well as the neurotransmitter, peptide hormones or neuropeptide receptors expressed in these neurons. Biochemical experiments have been conducted to investigate the effects of neurotransmitters, peptide hormones or neuropeptides on neurosteroid biosynthesis, and to characterize the type of receptors involved. Thus, it has been found that glutamate, acting through kainate and/or AMPA receptors, rapidly inactivates P450arom, and that melatonin produced by the pineal gland and eye inhibits the biosynthesis of 7-hydroxypregnenolone (7-OH-5P, while prolactin produced by the adenohypophysis enhances the formation of 7-OH-5P. It has also been demonstrated that the biosynthesis of neurosteroids is inhibited by GABA, acting through GABAA receptors, and neuropeptide Y, acting through Y1 receptors. In contrast, it has been shown that the octadecaneuropetide ODN, acting through central-type benzodiazepine receptors, the triakontatetraneuropeptide TTN, acting though peripheral-type benzodiazepine receptors, and vasotocine, acting through V1a-like receptors, stimulate the production of neurosteroids. Since neurosteroids are implicated in the control of various neurophysiological and behavioral processes, these data suggest that some of the neurophysiological effects exerted by neurotransmitters and neuropeptides may be mediated via the regulation

  20. Cocaine Inhibits Dopamine D2 Receptor Signaling via Sigma-1-D2 Receptor Heteromers

    Science.gov (United States)

    Navarro, Gemma; Moreno, Estefania; Bonaventura, Jordi; Brugarolas, Marc; Farré, Daniel; Aguinaga, David; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carmen; Ferre, Sergi

    2013-01-01

    Under normal conditions the brain maintains a delicate balance between inputs of reward seeking controlled by neurons containing the D1-like family of dopamine receptors and inputs of aversion coming from neurons containing the D2-like family of dopamine receptors. Cocaine is able to subvert these balanced inputs by altering the cell signaling of these two pathways such that D1 reward seeking pathway dominates. Here, we provide an explanation at the cellular and biochemical level how cocaine may achieve this. Exploring the effect of cocaine on dopamine D2 receptors function, we present evidence of σ1 receptor molecular and functional interaction with dopamine D2 receptors. Using biophysical, biochemical, and cell biology approaches, we discovered that D2 receptors (the long isoform of the D2 receptor) can complex with σ1 receptors, a result that is specific to D2 receptors, as D3 and D4 receptors did not form heteromers. We demonstrate that the σ1-D2 receptor heteromers consist of higher order oligomers, are found in mouse striatum and that cocaine, by binding to σ1 -D2 receptor heteromers, inhibits downstream signaling in both cultured cells and in mouse striatum. In contrast, in striatum from σ1 knockout animals these complexes are not found and this inhibition is not seen. Taken together, these data illuminate the mechanism by which the initial exposure to cocaine can inhibit signaling via D2 receptor containing neurons, destabilizing the delicate signaling balance influencing drug seeking that emanates from the D1 and D2 receptor containing neurons in the brain. PMID:23637801

  1. Enthalpy-Entropy Compensation in the Binding of Modulators at Ionotropic Glutamate Receptor GluA2

    DEFF Research Database (Denmark)

    Krintel, Christian; Francotte, Pierre; Pickering, Darryl S

    2016-01-01

    of 5 was examined with x-ray crystallography, showing that the only change compared to that of earlier compounds was the orientation of Ser-497 pointing toward the hydroxyl group of 5. The favorable enthalpy can be explained by the formation of a hydrogen bond from the side-chain hydroxyl group of Ser...... of modulators BPAM97 (2) and BPAM344 (3) into a hydroxyl group (BPAM557 (4) and BPAM521 (5), respectively), leads to a more favorable binding enthalpy (ΔH, kcal/mol) from −4.9 (2) and −7.5 (3) to −6.2 (4) and −14.5 (5), but also a less favorable binding entropy (−TΔS, kcal/mol) from −2.3 (2) and −1.3 (3) to −0......-497 to the hydroxyl group of 5, whereas the unfavorable entropy might be due to desolvation effects combined with a conformational restriction of Ser-497 and 5. In summary, this study shows a remarkable example of enthalpy-entropy compensation in drug development accompanied with a likely explanation...

  2. Function of the cytoplasmic tail of human calcitonin receptor-like receptor in complex with receptor activity-modifying protein 2

    Energy Technology Data Exchange (ETDEWEB)

    Kuwasako, Kenji, E-mail: kuwasako@fc.miyazaki-u.ac.jp [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kitamura, Kazuo; Nagata, Sayaka; Hikosaka, Tomomi [Division of Circulation and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kato, Johji [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan)

    2010-02-12

    Receptor activity-modifying protein 2 (RAMP2) enables calcitonin receptor-like receptor (CRLR) to form an adrenomedullin (AM)-specific receptor. Here we investigated the function of the cytoplasmic C-terminal tail (C-tail) of human (h)CRLR by co-transfecting its C-terminal mutants into HEK-293 cells stably expressing hRAMP2. Deleting the C-tail from CRLR disrupted AM-evoked cAMP production or receptor internalization, but did not affect [{sup 125}I]AM binding. We found that CRLR residues 428-439 are required for AM-evoked cAMP production, though deleting this region had little effect on receptor internalization. Moreover, pretreatment with pertussis toxin (100 ng/mL) led to significant increases in AM-induced cAMP production via wild-type CRLR/RAMP2 complexes. This effect was canceled by deleting CRLR residues 454-457, suggesting Gi couples to this region. Flow cytometric analysis revealed that CRLR truncation mutants lacking residues in the Ser/Thr-rich region extending from Ser{sup 449} to Ser{sup 467} were unable to undergo AM-induced receptor internalization and, in contrast to the effect on wild-type CRLR, overexpression of GPCR kinases-2, -3 and -4 failed to promote internalization of CRLR mutants lacking residues 449-467. Thus, the hCRLR C-tail is crucial for AM-evoked cAMP production and internalization of the CRLR/RAMP2, while the receptor internalization is dependent on the aforementioned GPCR kinases, but not Gs coupling.

  3. Molecular and Cellular Organization of Taste Neurons in Adult Drosophila Pharynx

    Directory of Open Access Journals (Sweden)

    Yu-Chieh David Chen

    2017-12-01

    Full Text Available Summary: The Drosophila pharyngeal taste organs are poorly characterized despite their location at important sites for monitoring food quality. Functional analysis of pharyngeal neurons has been hindered by the paucity of molecular tools to manipulate them, as well as their relative inaccessibility for neurophysiological investigations. Here, we generate receptor-to-neuron maps of all three pharyngeal taste organs by performing a comprehensive chemoreceptor-GAL4/LexA expression analysis. The organization of pharyngeal neurons reveals similarities and distinctions in receptor repertoires and neuronal groupings compared to external taste neurons. We validate the mapping results by pinpointing a single pharyngeal neuron required for feeding avoidance of L-canavanine. Inducible activation of pharyngeal taste neurons reveals functional differences between external and internal taste neurons and functional subdivision within pharyngeal sweet neurons. Our results provide roadmaps of pharyngeal taste organs in an insect model system for probing the role of these understudied neurons in controlling feeding behaviors. : Chen and Dahanukar carry out a large-scale, systematic analysis to understand the molecular organization of pharyngeal taste neurons. Taking advantage of the molecular genetic toolkit that arises from this map, they use genetic dissection strategies to probe the functional roles of selected pharyngeal neurons in food choice. Keywords: Drosophila, taste, pharynx, chemosensory receptors, gustatory receptors, ionotropic receptors, feeding

  4. Prostaglandin Receptor Signaling in Disease

    Directory of Open Access Journals (Sweden)

    Toshiyuki Matsuoka

    2007-01-01

    Full Text Available Prostanoids, consisting of the prostaglandins (PGs and the thromboxanes (TXs, are a group of lipid mediators formed in response to various stimuli. They include PGD2, PGE2, PGF2α, PGI2, and TXA2. They are released outside of the cells immediately after synthesis, and exert their actions by binding to a G-protein coupled rhodopsin-type receptor on the surface of target cells. There are eight types of the prostanoid receptors conserved in mammals from mouse to human. They are the PGD receptor (DP, four subtypes of the PGE receptor (EP1, EP2, EP3, and EP4, the PGF receptor (FP, PGI receptor (IP, and TXA receptor (TP. Recently, mice deficient in each of these prostanoid receptors were generated and subjected to various experimental models of disease. These studies have revealed the roles of PG receptor signaling in various pathological conditions, and suggest that selective manipulation of the prostanoid receptors may be beneficial in treatment of the pathological conditions. Here we review these recent findings of roles of prostanoid receptor signaling and their therapeutic implications.

  5. Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors.

    Science.gov (United States)

    Linares, Andrea; Couling, Leena E; Carrera, Eduardo J; Speth, Robert C

    2016-06-07

    This protocol describes receptor binding patterns for Angiotensin II (Ang II) in the rat brain using a radioligand specific for Ang II receptors to perform receptor autoradiographic mapping. Tissue specimens are harvested and stored at -80 °C. A cryostat is used to coronally section the tissue (brain) and thaw-mount the sections onto charged slides. The slide-mounted tissue sections are incubated in (125)I-SI-Ang II to radiolabel Ang II receptors. Adjacent slides are separated into two sets: 'non-specific binding' (NSP) in the presence of a receptor saturating concentration of non-radiolabeled Ang II, or an AT1 Ang II receptor subtype (AT1R) selective Ang II receptor antagonist, and 'total binding' with no AT1R antagonist. A saturating concentration of AT2 Ang II receptor subtype (AT2R) antagonist (PD123319, 10 µM) is also present in the incubation buffer to limit (125)I-SI-Ang II binding to the AT1R subtype. During a 30 min pre-incubation at ~22 °C, NSP slides are exposed to 10 µM PD123319 and losartan, while 'total binding' slides are exposed to 10 µM PD123319. Slides are then incubated with (125)I-SI-Ang II in the presence of PD123319 for 'total binding', and PD123319 and losartan for NSP in assay buffer, followed by several 'washes' in buffer, and water to remove salt and non-specifically bound radioligand. The slides are dried using blow-dryers, then exposed to autoradiography film using a specialized film and cassette. The film is developed and the images are scanned into a computer for visual and quantitative densitometry using a proprietary imaging system and a spreadsheet. An additional set of slides are thionin-stained for histological comparisons. The advantage of using receptor autoradiography is the ability to visualize Ang II receptors in situ, within a section of a tissue specimen, and anatomically identify the region of the tissue by comparing it to an adjacent histological reference section.

  6. Examination of Org 26576, an AMPA receptor positive allosteric modulator, in patients diagnosed with major depressive disorder: an exploratory, randomized, double-blind, placebo-controlled trial.

    Science.gov (United States)

    Nations, Kari R; Dogterom, Peter; Bursi, Roberta; Schipper, Jacques; Greenwald, Scott; Zraket, David; Gertsik, Lev; Johnstone, Jack; Lee, Allen; Pande, Yogesh; Ruigt, Ge; Ereshefsky, Larry

    2012-12-01

    Org 26576 acts by modulating ionotropic AMPA-type glutamate receptors to enhance glutamatergic neurotransmission. The aim of this Phase 1b study (N=54) was to explore safety, tolerability, pharmacokinetics, and pharmacodynamics of Org 26576 in depressed patients. Part I (N=24) evaluated the maximum tolerated dose (MTD) and optimal titration schedule in a multiple rising dose paradigm (range 100 mg BID to 600 mg BID); Part II (N=30) utilized a parallel groups design (100 mg BID, 400 mg BID, placebo) to examine all endpoints over a 28-day dosing period. Based on the number of moderate intensity adverse events reported at the 600 mg BID dose level, the MTD established in Part I was 450 mg BID. Symptomatic improvement as measured by the Montgomery-Asberg Depression Rating Scale was numerically greater in the Org 26576 groups than in the placebo group in both study parts. In Part II, the 400 mg BID dose was associated with improvements in executive functioning and speed of processing cognitive tests. Org 26576 was also associated with growth hormone increases and cortisol decreases at the end of treatment but did not influence prolactin or brain-derived neurotrophic factor. The quantitative electroencephalogram index Antidepressant Treatment Response at Week 1 was able to significantly predict symptomatic response at endpoint in the active treatment group, as was early improvement in social acuity. Overall, Org 26576 demonstrated good tolerability and pharmacokinetic properties in depressed patients, and pharmacodynamic endpoints suggested that it may show promise in future well-controlled, adequately powered proof of concept trials.

  7. A2A-D2 receptor-receptor interaction modulates gliotransmitter release from striatal astrocyte processes.

    Science.gov (United States)

    Cervetto, Chiara; Venturini, Arianna; Passalacqua, Mario; Guidolin, Diego; Genedani, Susanna; Fuxe, Kjell; Borroto-Esquela, Dasiel O; Cortelli, Pietro; Woods, Amina; Maura, Guido; Marcoli, Manuela; Agnati, Luigi F

    2017-01-01

    Evidence for striatal A2A-D2 heterodimers has led to a new perspective on molecular mechanisms involved in schizophrenia and Parkinson's disease. Despite the increasing recognition of astrocytes' participation in neuropsychiatric disease vulnerability, involvement of striatal astrocytes in A2A and D2 receptor signal transmission has never been explored. Here, we investigated the presence of D2 and A2A receptors in isolated astrocyte processes prepared from adult rat striatum by confocal imaging; the effects of receptor activation were measured on the 4-aminopyridine-evoked release of glutamate from the processes. Confocal analysis showed that A2A and D2 receptors were co-expressed on the same astrocyte processes. Evidence for A2A-D2 receptor-receptor interactions was obtained by measuring the release of the gliotransmitter glutamate: D2 receptors inhibited the glutamate release, while activation of A2A receptors, per se ineffective, abolished the effect of D2 receptor activation. The synthetic D2 peptide VLRRRRKRVN corresponding to the receptor region involved in electrostatic interaction underlying A2A-D2 heteromerization abolished the ability of the A2A receptor to antagonize the D2 receptor-mediated effect. Together, the findings are consistent with heteromerization of native striatal astrocytic A2A-D2 receptors that via allosteric receptor-receptor interactions could play a role in the control of striatal glutamatergic transmission. These new findings suggest possible new pathogenic mechanisms and/or therapeutic approaches to neuropsychiatric disorders. © 2016 International Society for Neurochemistry.

  8. Systemic injection of kainic acid: Gliosis in olfactory and limbic brain regions quantified with [3H]PK 11195 binding autoradiography

    International Nuclear Information System (INIS)

    Altar, C.A.; Baudry, M.

    1990-01-01

    Neurodegenerative diseases may result from excessive stimulation of excitatory amino acid receptors by endogenous ligands. Because neuronal degeneration is associated with glial proliferation and hypertrophy, the degenerative changes throughout rat brain following the systemic administration of kainic acid (12 mg/kg) were mapped with quantitative autoradiography of [3H]PK 11195. This radioligand binds to a mitochondrial benzodiazepine binding site (MBBS) on microglia and astrocytes. Analysis of eight horizontal and four coronal brain levels revealed up to 16-fold increases in [3H]PK 11195 binding from 1 to 5 weeks but not 1 day after kainate injection. Increases in [3H]PK 11195 binding were predominantly in ventral limbic brain regions and olfactory projections to neocortical areas, with the olfactory cortex greater than subiculum/CA1 greater than anterior olfactory nucleus, medial thalamic nucleus, and piriform cortex greater than cingulate cortex and rostral hippocampus greater than dentate gyrus, septum, and amygdala greater than entorhinal cortex and temporal cortex. Little or no enhancement of [3H]PK 11195 binding was observed in numerous regions including the caudate-putamen, substantia nigra, nucleus accumbens, olfactory tubercle, cerebellum, thalamic nuclei, choroid plexus, medulla, parietal or occipital cortex, or pons. A 2-fold greater extent of neurodegeneration was obtained in ventral portions of the olfactory bulb, entorhinal cortex, temporal cortex, and dentate gyrus compared with the dorsal portions of these structures. The pattern of increase in [3H]PK 11195 binding closely matched the patterns of neuronal degeneration reported following parenteral kainate injection. These findings strengthen the notion that quantitative autoradiography of [3H]PK 11195 is a valuable tool to quantify the extent of neuronal degeneration

  9. Bumetanide is not capable of terminating status epilepticus but enhances phenobarbital efficacy in different rat models.

    Science.gov (United States)

    Töllner, Kathrin; Brandt, Claudia; Erker, Thomas; Löscher, Wolfgang

    2015-01-05

    In about 20-40% of patients, status epilepticus (SE) is refractory to standard treatment with benzodiazepines, necessitating second- and third-line treatments that are not always successful, resulting in increased mortality. Rat models of refractory SE are instrumental in studying the changes underlying refractoriness and to develop more effective treatments for this severe medical emergency. Failure of GABAergic inhibition is a likely cause of the development of benzodiazepine resistance during SE. In addition to changes in GABAA receptor expression, trafficking, and function, alterations in Cl(-) homeostasis with increased intraneuronal Cl(-) levels may be involved. Bumetanide, which reduces intraneuronal Cl(-) by inhibiting the Cl(-) intruding Na(+), K(+), Cl(-) cotransporter NKCC1, has been reported to interrupt SE induced by kainate in urethane-anesthetized rats, indicating that this diuretic drug may be an interesting candidate for treatment of refractory SE. In this study, we evaluated the effects of bumetanide in the kainate and lithium-pilocarpine models of SE as well as a model in which SE is induced by sustained electrical stimulation of the basolateral amygdala. Unexpectedly, bumetanide alone was ineffective to terminate SE in both conscious and anesthetized adult rats. However, it potentiated the anticonvulsant effect of low doses of phenobarbital, although this was only seen in part of the animals; higher doses of phenobarbital, particularly in combination with diazepam, were more effective to terminate SE than bumetanide/phenobarbital combinations. These data do not suggest that bumetanide, alone or in combination with phenobarbital, is a valuable option in the treatment of refractory SE in adult patients. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. N-glycosylation of the β2 adrenergic receptor regulates receptor function by modulating dimerization.

    Science.gov (United States)

    Li, Xiaona; Zhou, Mang; Huang, Wei; Yang, Huaiyu

    2017-07-01

    N-glycosylation is a common post-translational modification of G-protein-coupled receptors (GPCRs). However, it remains unknown how N-glycosylation affects GPCR signaling. β 2 adrenergic receptor (β 2 AR) has three N-glycosylation sites: Asn6, Asn15 at the N-terminus, and Asn187 at the second extracellular loop (ECL2). Here, we show that deletion of the N-glycan did not affect receptor expression and ligand binding. Deletion of the N-glycan at the N-terminus rather than Asn187 showed decreased effects on isoproterenol-promoted G-protein-dependent signaling, β-arrestin2 recruitment, and receptor internalization. Both N6Q and N15Q showed decreased receptor dimerization, while N187Q did not influence receptor dimerization. As decreased β 2 AR homodimer accompanied with reduced efficiency for receptor function, we proposed that the N-glycosylation of β 2 AR regulated receptor function by influencing receptor dimerization. To verify this hypothesis, we further paid attention to the residues at the dimerization interface. Studies of Lys60 and Glu338, two residues at the receptor dimerization interface, exhibited that the K60A/E338A showed decreased β 2 AR dimerization and its effects on receptor signaling were similar to N6Q and N15Q, which further supported the importance of receptor dimerization for receptor function. This work provides new insights into the relationship among glycosylation, dimerization, and function of GPCRs. Peptide-N-glycosidase F (PNGase F, EC 3.2.2.11); endo-β-N-acetylglucosaminidase A (Endo-A, EC 3.2.1.96). © 2017 Federation of European Biochemical Societies.

  11. Prognostic Value of Estrogen Receptor alpha and Progesterone Receptor Conversion in Distant Breast Cancer Metastases

    NARCIS (Netherlands)

    Hoefnagel, Laurien D. C.; Moelans, Cathy B.; Meijer, S. L.; van Slooten, Henk-Jan; Wesseling, Pieter; Wesseling, Jelle; Westenend, Pieter J.; Bart, Joost; Seldenrijk, Cornelis A.; Nagtegaal, Iris D.; Oudejans, Joost; van der Valk, Paul; van Gils, Carla H.; van der Wall, Elsken; van Diest, Paul J.

    2012-01-01

    BACKGROUND: Changes in the receptor profile of primary breast cancers to their metastases (receptor conversion) have been described for the estrogen receptor alpha (ER alpha) and progesterone receptor (PR). The purpose of this study was to evaluate the impact of receptor conversion for ER alpha and

  12. Microarray-Based Determination of Estrogen Receptor, Progesterone Receptor, and HER2 Receptor Status in Breast Cancer

    NARCIS (Netherlands)

    Roepman, Paul; Horlings, Hugo M.; Krijgsman, Oscar; Kok, Marleen; Bueno-de-Mesquita, Jolien M.; Bender, Richard; Linn, Sabine C.; Glas, Annuska M.; van de Vijver, Marc J.

    2009-01-01

    Purpose: The level of estrogen receptor (ER), progesterone receptor (PR), and HER2 aids in the determination of prognosis and treatment of breast cancer. Immunohistochemistry is currently the predominant method for assessment, but differences in methods and interpretation can substantially affect

  13. 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier integrity through a mechanism involving P2X7 receptors.

    Science.gov (United States)

    Rubio-Araiz, Ana; Perez-Hernandez, Mercedes; Urrutia, Andrés; Porcu, Francesca; Borcel, Erika; Gutierrez-Lopez, Maria Dolores; O'Shea, Esther; Colado, Maria Isabel

    2014-08-01

    The recreational drug 3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') produces a neuro-inflammatory response in rats characterized by an increase in microglial activation and IL-1β levels. The integrity of the blood-brain barrier (BBB) is important in preserving the homeostasis of the brain and has been shown to be affected by neuro-inflammatory processes. We aimed to study the effect of a single dose of MDMA on the activity of metalloproteinases (MMPs), expression of extracellular matrix proteins, BBB leakage and the role of the ionotropic purinergic receptor P2X7 (P2X7R) in the changes induced by the drug. Adult male Dark Agouti rats were treated with MDMA (10 mg/kg, i.p.) and killed at several time-points in order to evaluate MMP-9 and MMP-3 activity in the hippocampus and laminin and collagen-IV expression and IgG extravasation in the dentate gyrus. Microglial activation, P2X7R expression and localization were also determined in the dentate gyrus. Separate groups were treated with MDMA and the P2X7R antagonists Brilliant Blue G (BBG; 50 mg/kg, i.p.) or A-438079 (30 mg/kg, i.p.). MDMA increased MMP-3 and MMP-9 activity, reduced laminin and collagen-IV expression and increased IgG immunoreactivity. In addition, MDMA increased microglial activation and P2X7R immunoreactivity in these cells. BBG suppressed the increase in MMP-9 and MMP-3 activity, prevented basal lamina degradation and IgG extravasation into the brain parenchyma. A-438079 also prevented the MDMA-induced reduction in laminin and collagen-IV immunoreactivity. These results indicate that MDMA alters BBB permeability through an early P2X7R-mediated event, which in turn leads to enhancement of MMP-9 and MMP-3 activity and degradation of extracellular matrix.

  14. Immunocytochemical analysis of P2X2 in rat circumvallate taste buds

    Directory of Open Access Journals (Sweden)

    Yang Ruibiao

    2012-05-01

    Full Text Available Abstract Background Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3. P2X2/P2X3Dbl−/− mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. Results P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP3R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, “atypical” mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Conclusions Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis

  15. The Orphan Nuclear Receptor TR4 Is a Vitamin A-activated Nuclear Receptor

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X. Edward; Suino-Powell, Kelly M.; Xu, Yong; Chan, Cee-Wah; Tanabe, Osamu; Kruse, Schoen W.; Reynolds, Ross; Engel, James Douglas; Xu, H. Eric (Michigan-Med); (Van Andel)

    2015-11-30

    Testicular receptors 2 and 4 (TR2/4) constitute a subgroup of orphan nuclear receptors that play important roles in spermatogenesis, lipid and lipoprotein regulation, and the development of the central nervous system. Currently, little is known about the structural features and the ligand regulation of these receptors. Here we report the crystal structure of the ligand-free TR4 ligand binding domain, which reveals an autorepressed conformation. The ligand binding pocket of TR4 is filled by the C-terminal half of helix 10, and the cofactor binding site is occupied by the AF-2 helix, thus preventing ligand-independent activation of the receptor. However, TR4 exhibits constitutive transcriptional activity on multiple promoters, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, or ligand binding substantially reduce the transcriptional activity of this receptor. Importantly, both retinol and retinoic acid are able to promote TR4 to recruit coactivators and to activate a TR4-regulated reporter. These findings demonstrate that TR4 is a ligand-regulated nuclear receptor and suggest that retinoids might have a much wider regulatory role via activation of orphan receptors such as TR4.

  16. Soman- or kainic acid-induced convulsions decrease muscarinic receptors but not benzodiazepine receptors

    International Nuclear Information System (INIS)

    Churchill, L.; Pazdernik, T.L.; Cross, R.S.; Nelson, S.R.; Samson, F.E.

    1990-01-01

    [3H]Quinuclidinyl benzilate (QNB) binding to muscarinic receptors decreased in the rat forebrain after convulsions induced by a single dose of either soman, a potent inhibitor of acetylcholinesterase, or kainic acid, an excitotoxin. A Rosenthal plot revealed that the receptors decreased in number rather than affinity. When the soman-induced convulsions were blocked, the decrease in muscarinic receptors at 3 days was less extensive than when convulsions occurred and at 10 days they approached control levels in most of the brain areas. The most prominent decrements in QNB binding were in the piriform cortex where the decline in QNB binding is probably related to the extensive convulsion-associated neuropathology. The decrements in QNB binding after convulsions suggest that the convulsive state leads to a down-regulation of muscarinic receptors in some brain areas. In contrast to the decrease in QNB binding after convulsions, [3H]flunitrazepam binding to benzodiazepine receptors did not change even in the piriform cortex where the loss in muscarinic receptors was most prominent. Thus, it appears that those neuronal processes that bear muscarinic receptors are more vulnerable to convulsion-induced change than those with benzodiazepine receptors

  17. Cooperative ethylene receptor signaling

    OpenAIRE

    Liu, Qian; Wen, Chi-Kuang

    2012-01-01

    The gaseous plant hormone ethylene is perceived by a family of five ethylene receptor members in the dicotyledonous model plant Arabidopsis. Genetic and biochemical studies suggest that the ethylene response is suppressed by ethylene receptor complexes, but the biochemical nature of the receptor signal is unknown. Without appropriate biochemical measures to trace the ethylene receptor signal and quantify the signal strength, the biological significance of the modulation of ethylene responses ...

  18. Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues

    International Nuclear Information System (INIS)

    Waser, Beatrice; Reubi, Jean Claude

    2014-01-01

    Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the 125 iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer 125 I-GLP-1(7-36)amide. Receptor autoradiography studies with 125 I-GLP-1(7-36)amide agonist or 125 I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. The antagonist 125 I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer 125 I-GLP-1(7-36)amide. For comparison, 125 I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. The GLP-1 receptor antagonist exendin(9-39) labelled with 125 I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients. (orig.)

  19. Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer

    International Nuclear Information System (INIS)

    Pires, L.A.; Hegg, R.; Freitas, F.R.; Tavares, E.R.; Almeida, C.P.; Baracat, E.C.; Maranhão, R.C.

    2012-01-01

    Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy

  20. Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues

    Energy Technology Data Exchange (ETDEWEB)

    Waser, Beatrice; Reubi, Jean Claude [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, PO Box 62, Berne (Switzerland)

    2014-06-15

    Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the {sup 125}iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer {sup 125}I-GLP-1(7-36)amide. Receptor autoradiography studies with {sup 125}I-GLP-1(7-36)amide agonist or {sup 125}I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. The antagonist {sup 125}I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer {sup 125}I-GLP-1(7-36)amide. For comparison, {sup 125}I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. The GLP-1 receptor antagonist exendin(9-39) labelled with {sup 125}I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients. (orig.)

  1. Dengue virus receptor

    OpenAIRE

    Hidari, Kazuya I.P.J.; Suzuki, Takashi

    2011-01-01

    Dengue virus is an arthropod-borne virus transmitted by Aedes mosquitoes. Dengue virus causes fever and hemorrhagic disorders in humans and non-human primates. Direct interaction of the virus introduced by a mosquito bite with host receptor molecule(s) is crucial for virus propagation and the pathological progression of dengue diseases. Therefore, elucidation of the molecular mechanisms underlying the interaction between dengue virus and its receptor(s) in both humans and mosquitoes is essent...

  2. Repeated blockade of mineralocorticoid receptors, but not of glucocorticoid receptors impairs food rewarded spatial learning

    NARCIS (Netherlands)

    Douma, B. R.; Korte, S. M.; Buwalda, B.; La Fleur, S. E.; Bohus, B.; Luiten, P. G.

    1998-01-01

    Corticosteroids from the adrenal cortex influence a variety of behaviours including cognition, learning and memory. These hormones act via two intracellular receptors, the mineralo-corticoid receptor (MR) and the glucocorticoid receptor (GR). These two receptor types display a high concentration and

  3. Repeated blockade of mineralocorticoid receptors, but not of glucocorticoid receptors impairs food rewarded spatial learning

    NARCIS (Netherlands)

    Douma, BRK; Korte, SM; Buwalda, B; la Fleur, SE; Bohus, B; Luiten, PGM

    Corticosteroids from the adrenal cortex influence a variety of behaviours including cognition, learning and memory. These hormones act via two intracellular receptors, the mineralo-corticoid receptor (MR) and the glucocorticoid receptor (GR). These two receptor types display a high concentration and

  4. Functional relevance of G-protein-coupled-receptor-associated proteins, exemplified by receptor-activity-modifying proteins (RAMPs).

    Science.gov (United States)

    Fischer, J A; Muff, R; Born, W

    2002-08-01

    The calcitonin (CT) receptor (CTR) and the CTR-like receptor (CRLR) are close relatives within the type II family of G-protein-coupled receptors, demonstrating sequence identity of 50%. Unlike the interaction between CT and CTR, receptors for the related hormones and neuropeptides amylin, CT-gene-related peptide (CGRP) and adrenomedullin (AM) require one of three accessory receptor-activity-modifying proteins (RAMPs) for ligand recognition. An amylin/CGRP receptor is revealed when CTR is co-expressed with RAMP1. When complexed with RAMP3, CTR interacts with amylin alone. CRLR, initially classed as an orphan receptor, is a CGRP receptor when co-expressed with RAMP1. The same receptor is specific for AM in the presence of RAMP2. Together with human RAMP3, CRLR defines an AM receptor, and with mouse RAMP3 it is a low-affinity CGRP/AM receptor. CTR-RAMP1, antagonized preferentially by salmon CT-(8-32) and not by CGRP-(8-37), and CRLR-RAMP1, antagonized by CGRP-(8-37), are two CGRP receptor isotypes. Thus amylin and CGRP interact specifically with heterodimeric complexes between CTR and RAMP1 or RAMP3, and CGRP and AM interact with complexes between CRLR and RAMP1, RAMP2 or RAMP3.

  5. Pathophysiological consequences of receptor mistraffic: Tales from the platelet P2Y12 receptor.

    Science.gov (United States)

    Cunningham, Margaret R; Aungraheeta, Riyaad; Mundell, Stuart J

    2017-07-05

    Genetic variations in G protein-coupled receptor (GPCR) genes can disrupt receptor function in a wide variety of human genetic diseases, including platelet bleeding disorders. Platelets are critical for haemostasis with inappropriate platelet activation leading to the development of arterial thrombosis, which can result in heart attack and stroke whilst decreased platelet activity is associated with an increased risk of bleeding. GPCRs expressed on the surface of platelets play key roles in regulating platelet activity and therefore function. Receptors include purinergic receptors (P2Y 1 and P2Y 12 ), proteinase-activated receptor (PAR1 and PAR4) and thromboxane receptors (TPα), among others. Pharmacological blockade of these receptors forms a powerful therapeutic tool in the treatment and prevention of arterial thrombosis. With the advance of genomic technologies, there has been a substantial increase in the identification of naturally occurring rare and common GPCR variants. These variants include single-nucleotide polymorphisms (SNPs) and insertion or deletions that have the potential to alter GPCR expression or function. A number of defects in platelet GPCRs that disrupt receptor function have now been characterized in patients with mild bleeding disorders. This review will focus on rare, function-disrupting variants of platelet GPCRs with particular emphasis upon mutations in the P2Y 12 receptor gene that affect receptor traffic to modulate platelet function. Further this review will outline how the identification and characterization of function-disrupting GPCR mutations provides an essential link in translating our detailed understanding of receptor traffic and function in cell line studies into relevant human biological systems. Copyright © 2017. Published by Elsevier B.V.

  6. The effects of glycemic control on seizures and seizure-induced excitotoxic cell death

    Directory of Open Access Journals (Sweden)

    Schauwecker Paula

    2012-08-01

    Full Text Available Abstract Background Epilepsy is the most common neurological disorder after stroke, affecting more than 50 million persons worldwide. Metabolic disturbances are often associated with epileptic seizures, but the pathogenesis of this relationship is poorly understood. It is known that seizures result in altered glucose metabolism, the reduction of intracellular energy metabolites such as ATP, ADP and phosphocreatine and the accumulation of metabolic intermediates, such as lactate and adenosine. In particular, it has been suggested that the duration and extent of glucose dysregulation may be a predictor of the pathological outcome of status. However, little is known about neither the effects of glycemic control on brain metabolism nor the effects of managing systemic glucose concentrations in epilepsy. Results In this study, we examined glycemic modulation of kainate-induced seizure sensitivity and its neuropathological consequences. To investigate the relationship between glycemic modulation, seizure susceptibility and its neuropathological consequences, C57BL/6 mice (excitotoxin cell death resistant were subjected to hypoglycemia or hyperglycemia, followed by systemic administration of kainic acid to induce seizures. Glycemic modulation resulted in minimal consequences with regard to seizure severity but increased hippocampal pathology, irrespective of whether mice were hypoglycemic or hyperglycemic prior to kainate administration. Moreover, we found that exogenous administration of glucose following kainic acid seizures significantly reduced the extent of hippocampal pathology in FVB/N mice (excitotoxin cell death susceptible following systemic administration of kainic acid. Conclusion These findings demonstrate that modulation of the glycemic index can modify the outcome of brain injury in the kainate model of seizure induction. Moreover, modulation of the glycemic index through glucose rescue greatly diminishes the extent of seizure

  7. Acetylcholine receptor antibody

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003576.htm Acetylcholine receptor antibody To use the sharing features on this page, please enable JavaScript. Acetylcholine receptor antibody is a protein found in the blood of ...

  8. L-glutamate Receptor In Paramecium

    Science.gov (United States)

    Bernal-Martínez, Juan; Ortega-Soto, Arturo

    2004-09-01

    Behavioral, electrophysiological and biochemical experiments were performed in order to establish the presence of a glutamate receptor in the ciliate Paramecium. It was found that an AMPA/KA receptor is functionally expressed in Paramecium and that this receptor is immunologically and fillogenetically related to the AMPA/KA receptor present in vertebrates.

  9. Do receptors get pregnant too? Adrenergic receptor alterations in human pregnancy.

    Science.gov (United States)

    Smiley, R M; Finster, M

    1996-01-01

    In this review we discuss adrenergic receptor number and function during pregnancy, with emphasis on evidence that pregnancy results in specific receptor alterations from the nonpregnant state. Changes in adrenergic receptor function or distribution in vascular smooth muscle may be in part responsible for the decreased vascular responsiveness seen in human pregnancy, and the lack of the normal alterations may be a part of the syndromes of gestational hypertension, including preeclampsia-eclampsia. The onset of labor may be influenced by adrenergic modulation, and receptor or postreceptor level molecular alterations may trigger or facilitate normal or preterm labor. Human studies are emphasized when possible to assess the role of adrenergic signal transduction regulation in the physiology and pathophysiology of normal and complicated human pregnancy.

  10. Melatonin Receptor Genes in Vertebrates

    Directory of Open Access Journals (Sweden)

    Hua Dong Yin

    2013-05-01

    Full Text Available Melatonin receptors are members of the G protein-coupled receptor (GPCR family. Three genes for melatonin receptors have been cloned. The MT1 (or Mel1a or MTNR1A and MT2 (or Mel1b or MTNR1B receptor subtypes are present in humans and other mammals, while an additional melatonin receptor subtype, Mel1c (or MTNR1C, has been identified in fish, amphibians and birds. Another melatonin related orphan receptor, GPR50, which does not bind melatonin, is found exclusively in mammals. The hormone melatonin is secreted primarily by the pineal gland, with highest levels occurring during the dark period of a circadian cycle. This hormone acts systemically in numerous organs. In the brain, it is involved in the regulation of various neural and endocrine processes, and it readjusts the circadian pacemaker, the suprachiasmatic nucleus. This article reviews recent studies of gene organization, expression, evolution and mutations of melatonin receptor genes of vertebrates. Gene polymorphisms reveal that numerous mutations are associated with diseases and disorders. The phylogenetic analysis of receptor genes indicates that GPR50 is an outgroup to all other melatonin receptor sequences. GPR50 may have separated from a melatonin receptor ancestor before the split between MTNR1C and the MTNR1A/B ancestor.

  11. Clinical and Genomic Crosstalk between Glucocorticoid Receptor and Estrogen Receptor α In Endometrial Cancer

    Directory of Open Access Journals (Sweden)

    Jeffery M. Vahrenkamp

    2018-03-01

    Full Text Available Summary: Steroid hormone receptors are simultaneously active in many tissues and are capable of altering each other’s function. Estrogen receptor α (ER and glucocorticoid receptor (GR are expressed in the uterus, and their ligands have opposing effects on uterine growth. In endometrial tumors with high ER expression, we surprisingly found that expression of GR is associated with poor prognosis. Dexamethasone reduced normal uterine growth in vivo; however, this growth inhibition was abolished in estrogen-induced endometrial hyperplasia. We observed low genomic-binding site overlap when ER and GR are induced with their respective ligands; however, upon simultaneous induction they co-occupy more sites. GR binding is altered significantly by estradiol with GR recruited to ER-bound loci that become more accessible upon estradiol induction. Gene expression responses to co-treatment were more similar to estradiol but with additional regulated genes. Our results suggest phenotypic and molecular interplay between ER and GR in endometrial cancer. : Estrogen receptor α (ER and glucocorticoid receptor (GR are expressed in the uterus and have differential effects on growth. Vahrenkamp et al. find that expression of both receptors is associated with poor outcome in endometrial cancer and that simultaneous induction of ER and GR leads to molecular interplay between the receptors. Keywords: estrogen receptor, glucocorticoid receptor, endometrial cancer

  12. Depolarization-induced release of [(3)H]D-aspartate from GABAergic neurons caused by reversal of glutamate transporters

    DEFF Research Database (Denmark)

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

    2000-01-01

    if glutamate in addition to gamma-aminobutyric acid (GABA) could be released from these cultures. The neurons were preloaded with [(3)H]D-aspartate and subsequently its release was followed during depolarization induced by a high potassium concentration or the alpha-amino-3-hydroxy-5-methyl-4......-isoxazolepropionic acid (AMPA) receptor agonists, AMPA and kainate. Depolarization of the neurons with 55 mM potassium increased the release of [(3)H]D-aspartate by more than 10-fold. When the non-specific calcium-channel blockers cobalt or lanthanum were included in the stimulation buffer with potassium......, the release of [(3)H]D-aspartate was decreased by about 40%. These results indicated that some of the released [(3)H]D-aspartate might originate from a vesicular pool. When AMPA was applied to the neurons, the release of [(3)H]D-aspartate was increased 2-fold and could not be prevented or decreased...

  13. 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)

  14. The lactate receptor, G-protein-coupled receptor 81/hydroxycarboxylic acid receptor 1

    DEFF Research Database (Denmark)

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

    2015-01-01

    We have proposed that lactate is a “volume transmitter” in the brain and underpinned this by showing that the lactate receptor, G-protein-coupled receptor 81 (GPR81, also known as HCA1 or HCAR1), which promotes lipid storage in adipocytes, is also active in the mammalian brain. This includes......, energy metabolism, and energy substrate availability, including a glucose- and glycogen-saving response. HCAR1 may contribute to optimizing the cAMP concentration. For instance, in the prefrontal cortex, excessively high cAMP levels are implicated in impaired cognition in old age, fatigue, stress...

  15. Adenosine receptor desensitization and trafficking.

    Science.gov (United States)

    Mundell, Stuart; Kelly, Eamonn

    2011-05-01

    As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Cocaine Disrupts Histamine H3 Receptor Modulation of Dopamine D1 Receptor Signaling: σ1-D1-H3 Receptor Complexes as Key Targets for Reducing Cocaine's Effects

    Science.gov (United States)

    Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Hoffmann, Hanne M.; Fuentes, Silvia; Rosell-Vilar, Santi; Gasperini, Paola; Rodríguez-Ruiz, Mar; Medrano, Mireia; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carme; Ferré, Sergi; Ortiz, Jordi; Canela, Enric

    2014-01-01

    The general effects of cocaine are not well understood at the molecular level. What is known is that the dopamine D1 receptor plays an important role. Here we show that a key mechanism may be cocaine's blockade of the histamine H3 receptor-mediated inhibition of D1 receptor function. This blockade requires the σ1 receptor and occurs upon cocaine binding to σ1-D1-H3 receptor complexes. The cocaine-mediated disruption leaves an uninhibited D1 receptor that activates Gs, freely recruits β-arrestin, increases p-ERK 1/2 levels, and induces cell death when over activated. Using in vitro assays with transfected cells and in ex vivo experiments using both rats acutely treated or self-administered with cocaine along with mice depleted of σ1 receptor, we show that blockade of σ1 receptor by an antagonist restores the protective H3 receptor-mediated brake on D1 receptor signaling and prevents the cell death from elevated D1 receptor signaling. These findings suggest that a combination therapy of σ1R antagonists with H3 receptor agonists could serve to reduce some effects of cocaine. PMID:24599455

  17. Receptor studies in biological psychiatry

    International Nuclear Information System (INIS)

    Fujiwara, Yutaka

    1992-01-01

    Recent advances in the pharmacological treatment of endogenous psychosis have led to the development of biological studies in psychiatry. Studies on neurotransmitter receptors were reviewed in order to apply positron-emission tomograph (PET) for biological psychiatry. The dopamine (DA) hypothesis for schizophrenia was advanced on the basis of the observed effects of neuroleptics and methamphetamine, and DA(D 2 ) receptor supersensitivity measured by PET and receptor binding in the schizophrenic brain. The clinical potencies of neuroleptics for schizophrenia were correlated with their abilities to inhibit the D 2 receptor, and not other receptors. The σ receptor was expected to be a site of antipsychotic action. However, the potency of drugs action on it was not correlated with clinical efficacy. Haloperidol binds with high affinity to the σ receptor, which may mediate acute dystonia, an extrapyramidal side effect of neuroleptics. Behavioral and neurochemical changes induced by methamphetamine treatment were studied as an animal model of schizophrenia, and both a decrease of D 2 receptor density and an increase of DA release were detected. The monoamine hypothesis for manic-depressive psychosis was advanced on the basis of the effect of reserpine, monoamine oxidase inhibitor and antidepressants. 3 H-clonidine binding sites were increased in platelet membranes of depressive patients, 3 H-imipramine binding sites were decreased. The GABA A receptor is the target site for the action of anxiolytics and antiepileptics such as benzodiazepines and barbiturates. Recent developments in molecular biology techniques have revealed the structure of receptor proteins, which are classified into two receptor families, the G-protein coupled type (D 2 ) and the ion-channel type (GABA A ). (J.P.N.)

  18. Arrestin scaffolds NHERF1 to the P2Y12 receptor to regulate receptor internalization.

    Science.gov (United States)

    Nisar, Shaista P; Cunningham, Margaret; Saxena, Kunal; Pope, Robert J; Kelly, Eamonn; Mundell, Stuart J

    2012-07-13

    We have recently shown in a patient with mild bleeding that the PDZ-binding motif of the platelet G protein-coupled P2Y(12) receptor (P2Y(12)R) is required for effective receptor traffic in human platelets. In this study we show for the first time that the PDZ motif-binding protein NHERF1 exerts a major role in potentiating G protein-coupled receptor (GPCR) internalization. NHERF1 interacts with the C-tail of the P2Y(12)R and unlike many other GPCRs, NHERF1 interaction is required for effective P2Y(12)R internalization. In vitro and prior to agonist stimulation P2Y(12)R/NHERF1 interaction requires the intact PDZ binding motif of this receptor. Interestingly on receptor stimulation NHERF1 no longer interacts directly with the receptor but instead binds to the receptor via the endocytic scaffolding protein arrestin. These findings suggest a novel model by which arrestin can serve as an adaptor to promote NHERF1 interaction with a GPCR to facilitate effective NHERF1-dependent receptor internalization.

  19. A candidate pheromone receptor and two odorant receptors of the hawkmoth Manduca sexta.

    Science.gov (United States)

    Patch, Harland M; Velarde, Rodrigo A; Walden, Kimberly K O; Robertson, Hugh M

    2009-05-01

    In this study, we cloned and characterized three Manduca sexta odorant receptors (ORs). One receptor is a putative pheromone receptor expressed exclusively in a cell associated with male-specific type-I trichoid sensilla. We describe the results of real-time PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) experiments that show MsextaOR1 is expressed only in male antennae. In situ hybridization labels a single cell associated with type-1 trichoid sensilla, which houses two neurons that have been previously determined to respond to the major components of the pheromone blend. The second receptor, MsextaOR2, was discovered using degenerate primers designed to conserved motifs of a unique group ORs that share as much as 88% identity. Comparison of RT-PCR, qRT-PCR, and in situ hybridization results with those of ORs in the Drosophila melanogaster Or83b subfamily shows a strong sequence and expression pattern similarity. The third receptor, MsextaOR3, was found by 5'-end sequencing of a normalized and subtracted cDNA library from male M. sexta antennae. RT-PCR and qRT-PCR show that this receptor is expressed only in male and female antennae. These are the first ORs, including a putative pheromone receptor, to be described from M. sexta.

  20. Transcriptional targets shared by estrogen receptor- related receptors (ERRs) and estrogen receptor (ER) alpha, but not by ERbeta.

    Science.gov (United States)

    Vanacker, J M; Pettersson, K; Gustafsson, J A; Laudet, V

    1999-01-01

    The physiological activities of estrogens are thought to be mediated by specific nuclear receptors, ERalpha and ERbeta. However, certain tissues, such as the bone, that are highly responsive to estrogens only express a low level of these receptors. Starting from this apparent contradiction, we have evaluated the potentials of two related receptors ERRalpha and ERRbeta to intervene in estrogen signaling. ERalpha, ERRalpha and ERRbeta bind to and activate transcription through both the classical estrogen response element (ERE) and the SF-1 response element (SFRE). In contrast, ERbeta DNA-binding and transcriptional activity is restricted to the ERE. Accordingly, the osteopontin gene promoter is stimulated through SFRE sequences, by ERRalpha as well as by ERalpha, but not by ERbeta. Analysis of the cross-talk within the ER/ERR subgroup of nuclear receptors thus revealed common targets but also functional differences between the two ERs. PMID:10428965

  1. Flavivirus Entry Receptors: An Update

    Directory of Open Access Journals (Sweden)

    Manuel Perera-Lecoin

    2013-12-01

    Full Text Available Flaviviruses enter host cells by endocytosis initiated when the virus particles interact with cell surface receptors. The current model suggests that flaviviruses use at least two different sets of molecules for infectious entry: attachment factors that concentrate and/or recruit viruses on the cell surface and primary receptor(s that bind to virions and direct them to the endocytic pathway. Here, we present the currently available knowledge regarding the flavivirus receptors described so far with specific attention to C-type lectin receptors and the phosphatidylserine receptors, T-cell immunoglobulin and mucin domain (TIM and TYRO3, AXL and MER (TAM. Their role in flavivirus attachment and entry as well as their implication in the virus biology will be discussed in depth.

  2. Pharmacological characterization of receptor-activity-modifying proteins (RAMPs) and the human calcitonin receptor.

    Science.gov (United States)

    Armour, S L; Foord, S; Kenakin, T; Chen, W J

    1999-12-01

    Receptor-activity-modifying proteins (RAMPs) are a family of single transmembrane domain proteins shown to be important for the transport and ligand specificity of the calcitonin gene-related peptide (CGRP) receptor. In this report, we describe the analysis of pharmacological properties of the human calcitonin receptor (hCTR) coexpressed with different RAMPs with the use of the Xenopus laevis melanophore expression system. We show that coexpression of RAMP3 with human calcitonin receptor changed the relative potency of hCTR to human calcitonin (hCAL) and rat amylin. RAMP1 and RAMP2, in contrast, had little effect on the change of hCTR potency to hCAL or rat amylin. When coexpressed with RAMP3, hCTR reversed the relative potency by a 3.5-fold loss in sensitivity to hCAL and a 19-fold increase in sensitivity to rat amylin. AC66, an inverse agonist, produced apparent simple competitive antagonism of hCAL and rat amylin, as indicated by linear Schild regressions. The potency of AC66 was changed in the blockade of rat amylin but not hCAL responses with RAMP3 coexpression. The mean pK(B) for AC66 to hCAL was 9.4 +/- 0.3 without RAMP3 and 9.45 +/- 0.07 with RAMP3. For the antagonism of AC66 to rat amylin, the pK(B) was 9.25 +/- 0.15 without RAMP3 and 8.2 +/- 0.35 with RAMP3. The finding suggests that RAMP3 might modify the active states of calcitonin receptor in such a way as to create a new receptor phenotype that is "amylin-like." Irrespective of the physiological association of the new receptor species, the finding that a coexpressed membrane protein can completely change agonist and antagonist affinities for a receptor raises implications for screening in recombinant receptor systems.

  3. Serotonin 5-HT4 receptors and forebrain cholinergic system: receptor expression in identified cell populations.

    Science.gov (United States)

    Peñas-Cazorla, Raúl; Vilaró, M Teresa

    2015-11-01

    Activation of serotonin 5-HT4 receptors has pro-cognitive effects on memory performance. The proposed underlying neurochemical mechanism is the enhancement of acetylcholine release in frontal cortex and hippocampus elicited by 5-HT4 agonists. Although 5-HT4 receptors are present in brain areas related to cognition, e.g., hippocampus and cortex, the cellular localization of the receptors that might modulate acetylcholine release is unknown at present. We have analyzed, using dual label in situ hybridization, the cellular localization of 5-HT4 receptor mRNA in identified neuronal populations of the rat basal forebrain, which is the source of the cholinergic innervation to cortex and hippocampus. 5-HT4 receptor mRNA was visualized with isotopically labeled oligonucleotide probes, whereas cholinergic, glutamatergic, GABAergic and parvalbumin-synthesizing neurons were identified with digoxigenin-labeled oligonucleotide probes. 5-HT4 receptor mRNA was not detected in the basal forebrain cholinergic cell population. In contrast, basal forebrain GABAergic, parvalbumin synthesizing, and glutamatergic cells contained 5-HT4 receptor mRNA. Hippocampal and cortical glutamatergic neurons also express this receptor. These results indicate that 5-HT4 receptors are not synthesized by cholinergic cells, and thus would be absent from cholinergic terminals. In contrast, several non-cholinergic cell populations within the basal forebrain and its target hippocampal and cortical areas express these receptors and are thus likely to mediate the enhancement of acetylcholine release elicited by 5-HT4 agonists.

  4. Photo-antagonism of the GABAA receptor.

    Science.gov (United States)

    Mortensen, Martin; Iqbal, Favaad; Pandurangan, Arun P; Hannan, Saad; Huckvale, Rosemary; Topf, Maya; Baker, James R; Smart, Trevor G

    2014-07-29

    Neurotransmitter receptor trafficking is fundamentally important for synaptic transmission and neural network activity. GABAA receptors and inhibitory synapses are vital components of brain function, yet much of our knowledge regarding receptor mobility and function at inhibitory synapses is derived indirectly from using recombinant receptors, antibody-tagged native receptors and pharmacological treatments. Here we describe the use of a set of research tools that can irreversibly bind to and affect the function of recombinant and neuronal GABAA receptors following ultraviolet photoactivation. These compounds are based on the competitive antagonist gabazine and incorporate a variety of photoactive groups. By using site-directed mutagenesis and ligand-docking studies, they reveal new areas of the GABA binding site at the interface between receptor β and α subunits. These compounds enable the selected inactivation of native GABAA receptor populations providing new insight into the function of inhibitory synapses and extrasynaptic receptors in controlling neuronal excitation.

  5. Scavenger receptors in homeostasis and immunity.

    Science.gov (United States)

    Canton, Johnathan; Neculai, Dante; Grinstein, Sergio

    2013-09-01

    Scavenger receptors were originally identified by their ability to recognize and to remove modified lipoproteins; however, it is now appreciated that they carry out a striking range of functions, including pathogen clearance, lipid transport, the transport of cargo within the cell and even functioning as taste receptors. The large repertoire of ligands recognized by scavenger receptors and their broad range of functions are not only due to the wide range of receptors that constitute this family but also to their ability to partner with various co-receptors. The ability of individual scavenger receptors to associate with different co-receptors makes their responsiveness extremely versatile. This Review highlights recent insights into the structural features that determine the function of scavenger receptors and the emerging role that these receptors have in immune responses, notably in macrophage polarization and in the pathogenesis of diseases such as atherosclerosis and Alzheimer's disease.

  6. Central alpha2 adrenergic receptors in the rat cerebral cortex: repopulation kinetics and receptor reserve

    International Nuclear Information System (INIS)

    Adler, C.H.

    1986-01-01

    The alpha 2 adrenergic receptor subtype is thought to play a role in the mechanism of action of antidepressant and antihypertensive drugs. This thesis has attempted to shed light on the regulation of central alpha 2 adrenergic receptors in the rat cerebral cortex. Repopulation kinetics analysis allows for the determination of the rate of receptor production, rate constant of degradation, and half-life of the receptor. This analysis was carried out using both radioligand binding and functional receptor assays at various times following the irreversible inactivation of central alpha 2 adrenergic receptors by in vivo administration of N-ethoxycarbonyl-2-ethyoxy-1,2-dihydroquinoline (EEDQ). Both alpha 2 agonist and antagonist ligand binding sites recovered with a t/sub 1/2/ equal to approximately 4 days. The function of alpha 2 adrenergic autoreceptors, which inhibit stimulation-evoked release of 3 H-norepinephrine ( 3 H-NE) and alpha 2 adrenergic heteroreceptors which inhibit stimulation-evoked release of 3 H-serotonin ( 3 H-5-HT) were assayed. The t/sub 1/2/ for recovery of maximal autoreceptor and heteroreceptor function was 2.4 days and 4.6 days, respectively. The demonstration of a receptor reserve is critical to the interpretation of past and future studies of the alpha 2 adrenergic receptor since it demonstrates that: (1) alterations in the number of alpha 2 adrenergic receptor binding sites cannot be extrapolated to the actual function of the alpha 2 adrenergic receptor; and (2) alterations in the number of alpha 2 receptors is not necessarily accompanied by a change in the maximum function being studied, but may only result in shifting of the dose-response curve

  7. Identifying the receptor subtype selectivity of retinoid X and retinoic acid receptors via quantum mechanics.

    Science.gov (United States)

    Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

    2017-03-01

    Understanding and identifying the receptor subtype selectivity of a ligand is an important issue in the field of drug discovery. Using a combination of classical molecular mechanics and quantum mechanical calculations, this report assesses the receptor subtype selectivity for the human retinoid X receptor (hRXR) and retinoic acid receptor (hRAR) ligand-binding domains (LBDs) complexed with retinoid ligands. The calculated energies show good correlation with the experimentally reported binding affinities. The technique proposed here is a promising method as it reveals the origin of the receptor subtype selectivity of selective ligands.

  8. Interaction of epidermal growth factor receptors with the cytoskeleton is related to receptor clustering

    NARCIS (Netherlands)

    van Belzen, N.; Spaargaren, M.; Verkleij, A. J.; Boonstra, J.

    1990-01-01

    Recently it has been established that cytoskeleton-associated epidermal growth factor (EGF) receptors are predominantly of the high-affinity class and that EGF induces a recruitment of low-affinity receptors to the cytoskeleton. The nature of this EGF-induced receptor-cytoskeleton interaction,

  9. Toll-like receptors and NOD-like receptors in rheumatic diseases.

    LENUS (Irish Health Repository)

    McCormack, William J

    2012-02-01

    The past 10 years have seen the description of families of receptors that drive proinflammatory cytokine production in infection and tissue injury. Two major classes have been examined in the context of inflammatory joint disease--the Toll-like receptors (TLRs) and NOD-like receptors (NLRs). TLRs such as TLR2 and TLR4 are being implicated in the pathology of rheumatoid arthritis, ankylosing spondylitis, lyme arthritis and osteoarthritis. Nalp3 has been identified as a key NLR for IL-1beta production and has been shown to have a particular role in gout. These findings present new therapeutic opportunities, possibly allowing for the replacement of biologics with small molecule inhibitors.

  10. Olfactory Receptor Database: a sensory chemoreceptor resource

    OpenAIRE

    Skoufos, Emmanouil; Marenco, Luis; Nadkarni, Prakash M.; Miller, Perry L.; Shepherd, Gordon M.

    2000-01-01

    The Olfactory Receptor Database (ORDB) is a WWW-accessible database that has been expanded from an olfactory receptor resource to a chemoreceptor resource. It stores data on six classes of G-protein-coupled sensory chemoreceptors: (i) olfactory receptor-like proteins, (ii) vomeronasal receptors, (iii) insect olfactory receptors, (iv) worm chemoreceptors, (v) taste papilla receptors and (vi) fungal pheromone receptors. A complementary database of the ligands of these receptors (OdorDB) has bee...

  11. Molecular characterization of opioid receptors

    Energy Technology Data Exchange (ETDEWEB)

    Howard, A.D.

    1986-01-01

    The aim of this research was to purify and characterize active opioid receptors and elucidate molecular aspects of opioid receptor heterogeneity. Purification to apparent homogeneity of an opioid binding protein from bovine caudate was achieved by solubilization in the non-ionic detergent, digitonin, followed by sequential chromatography on the opiate affinity matrix, ..beta..-naltrexylethylenediamine-CH-Sepharose 4B, and on the lectine affinity matrix, wheat germ agglutinin-agarose. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) followed by autoradiography revealed that radioiodinated purified receptor gave a single band. Purified receptor preparations showed a specific activity of 12,000-15,000 fmol of opiate bound per mg of protein. Radioiodinated human beta-endorphin (/sup 125/I-beta-end/sub H/) was used as a probe to investigate the ligand binding subunits of mu and delta opioid receptors. /sup 125/I-beta-end/sub H/ was shown to bind to a variety of opioid receptor-containing tissues with high affinity and specificity with preference for mu and delta sites, and with little, if any, binding to kappa sites. Affinity crosslinking techniques were employed to covalently link /sup 125/I-beta-end/sub H/ to opioid receptors, utilizing derivatives of bis-succinimidyl esters that are bifunctional crosslinkers with specificities for amino and sulfhydryl groups. This, and competition experiments with high type-selective ligands, permitted the assignment of two labeled peptides to their receptor types, namely a peptide of M/sub r/ = 65,000 for mu receptors and one of M/sub r/ = 53,000 for delta receptors.

  12. Modulation of GABAergic Transmission in Development and Neurodevelopmental Disorders: Investigating Physiology and Pathology to Gain Therapeutic Perspectives

    Directory of Open Access Journals (Sweden)

    Gabriele eDeidda

    2014-05-01

    Full Text Available During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis.The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions.

  13. A Molecular and Cellular Context-Dependent Role for Ir76b in Detection of Amino Acid Taste

    Directory of Open Access Journals (Sweden)

    Anindya Ganguly

    2017-01-01

    Full Text Available Amino acid taste is expected to be a universal property among animals. Although sweet, bitter, salt, and water tastes have been well characterized in insects, the mechanisms underlying amino acid taste remain elusive. From a Drosophila RNAi screen, we identify an ionotropic receptor, Ir76b, as necessary for yeast preference. Using calcium imaging, we identify Ir76b+ amino acid taste neurons in legs, overlapping partially with sweet neurons but not those that sense other tastants. Ir76b mutants have reduced responses to amino acids, which are rescued by transgenic expression of Ir76b and a mosquito ortholog AgIr76b. Co-expression of Ir20a with Ir76b is sufficient for conferring amino acid responses in sweet-taste neurons. Notably, Ir20a also serves to block salt response of Ir76b. Our study establishes the role of a highly conserved receptor in amino acid taste and suggests a mechanism for mutually exclusive roles of Ir76b in salt- and amino-acid-sensing neurons.

  14. Internalization of G-protein-coupled receptors: Implication in receptor function, physiology and diseases.

    Science.gov (United States)

    Calebiro, Davide; Godbole, Amod

    2018-04-01

    G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and mediate the effects of numerous hormones and neurotransmitters. The nearly 1000 GPCRs encoded by the human genome regulate virtually all physiological functions and are implicated in the pathogenesis of prevalent human diseases such as thyroid disorders, hypertension or Parkinson's disease. As a result, 30-50% of all currently prescribed drugs are targeting these receptors. Once activated, GPCRs induce signals at the cell surface. This is often followed by internalization, a process that results in the transfer of receptors from the plasma membrane to membranes of the endosomal compartment. Internalization was initially thought to be mainly implicated in signal desensitization, a mechanism of adaptation to prolonged receptor stimulation. However, several unexpected functions have subsequently emerged. Most notably, accumulating evidence indicates that internalization can induce prolonged receptor signaling on intracellular membranes, which is apparently required for at least some biological effects of hormones like TSH, LH and adrenaline. These findings reveal an even stronger connection between receptor internalization and signaling than previously thought. Whereas new studies are just beginning to reveal an important physiological role for GPCR signaling after internalization and ways to exploit it for therapeutic purposes, future investigations will be required to explore its involvement in human disease. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Effect of the non-NMDA receptor antagonist GYKI 52466 on the microdialysate and tissue concentrations of amino acids following transient forebrain ischaemia.

    Science.gov (United States)

    Arvin, B; Lekieffre, D; Graham, J L; Moncada, C; Chapman, A G; Meldrum, B S

    1994-04-01

    The effect of the non-N-methyl-D-aspartate (non-NMDA) receptor antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466) on ischaemia-induced changes in the microdialysate and tissue concentrations of glutamate, aspartate, and gamma-aminobutyric acid (GABA) was studied in rats. Twenty minutes of four-vessel occlusion resulted in a transient increase in microdialysate levels of glutamate, aspartate, and GABA in striatum, cortex, and hippocampus. Administration of GYKI 52466 (10 mg/kg bolus + 10 mg/kg/60 min intravenously starting 20 min before onset of ischaemia) inhibited ischaemia-induced increases in microdialysate glutamate and GABA in striatum without affecting the increases in hippocampus or cortex. Twenty minutes of four-vessel occlusion resulted in immediate small decreases and larger delayed (72 h) decreases in tissue levels of glutamate and aspartate. Transient increases in tissue levels of GABA were shown in all three structures at the end of the ischaemic period. At 72 h, after the ischaemic period, significantly reduced GABA levels were observed in striatum and hippocampus. GYKI 52466, given under identical conditions as above, augmented the ischaemia-induced decrease in striatal tissue levels of glutamate and aspartate, without significantly affecting the decreases in hippocampus and cortex. Twenty minutes of ischaemia resulted in a large increase in microdialysate dopamine in striatum. GYKI 52466 failed to inhibit this increase. Kainic acid (500 microM infused through the probe for 20 min) caused increases in microdialysate glutamate and aspartate in the striatum. GYKI 52466 (10 mg/kg bolus + 10 mg/kg/60 min) completely inhibited the kainic acid-induced glutamate release. In conclusion, the action of the non-NMDA antagonist, GYKI 52466, in the striatum is different from that in the cortex and hippocampus. The inhibition by GYKI 52466 of ischaemia-induced and kainate-induced increases in microdialysate

  16. The Cannabinoid Receptor CB1 Modulates the Signaling Properties of the Lysophosphatidylinositol Receptor GPR55*

    Science.gov (United States)

    Kargl, Julia; Balenga, Nariman; Parzmair, Gerald P.; Brown, Andrew J.; Heinemann, Akos; Waldhoer, Maria

    2012-01-01

    The G protein-coupled receptor (GPCR) 55 (GPR55) and the cannabinoid receptor 1 (CB1R) are co-expressed in many tissues, predominantly in the central nervous system. Seven transmembrane spanning (7TM) receptors/GPCRs can form homo- and heteromers and initiate distinct signaling pathways. Recently, several synthetic CB1 receptor inverse agonists/antagonists, such as SR141716A, AM251, and AM281, were reported to activate GPR55. Of these, SR141716A was marketed as a promising anti-obesity drug, but was withdrawn from the market because of severe side effects. Here, we tested whether GPR55 and CB1 receptors are capable of (i) forming heteromers and (ii) whether such heteromers could exhibit novel signaling patterns. We show that GPR55 and CB1 receptors alter each others signaling properties in human embryonic kidney (HEK293) cells. We demonstrate that the co-expression of FLAG-CB1 receptors in cells stably expressing HA-GPR55 specifically inhibits GPR55-mediated transcription factor activation, such as nuclear factor of activated T-cells and serum response element, as well as extracellular signal-regulated kinases (ERK1/2) activation. GPR55 and CB1 receptors can form heteromers, but the internalization of both receptors is not affected. In addition, we observe that the presence of GPR55 enhances CB1R-mediated ERK1/2 and nuclear factor of activated T-cell activation. Our data provide the first evidence that GPR55 can form heteromers with another 7TM/GPCR and that this interaction with the CB1 receptor has functional consequences in vitro. The GPR55-CB1R heteromer may play an important physiological and/or pathophysiological role in tissues endogenously co-expressing both receptors. PMID:23161546

  17. Mechanism of A2 adenosine receptor activation. I. Blockade of A2 adenosine receptors by photoaffinity labeling

    International Nuclear Information System (INIS)

    Lohse, M.J.; Klotz, K.N.; Schwabe, U.

    1991-01-01

    It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxy-phenylisopropyladenosine [(R)-AHPIA] into the A1 adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of cellular cAMP levels. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenylate cyclase stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies indicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase stimulation of up to 50% of the control value. Similarly, the activation via these 10-20% of receptors occurs with a half-life that is only 2 times longer than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenylate cyclase stimulation. These observations require a modification of the models of receptor-adenylate cyclase coupling

  18. The First Fifteen Years of Steroid Receptor Research in Zebrafish; Characterization and Functional Analysis of the Receptors

    Directory of Open Access Journals (Sweden)

    Marcel J. M. Schaaf

    2017-07-01

    Full Text Available Steroid hormones regulate a wide range of processes in our body, and their effects are mediated by steroid receptors. In addition to their physiological role, these receptors mediate the effects of endocrine disrupting chemicals (EDCs and are widely used targets for dugs involved in the treatment of numerous diseases, ranging from cancer to inflammatory disorders. Over the last fifteen years, the zebrafish has increasingly been used as an animal model in steroid receptor research. Orthologues of all human steroid receptor genes appear to be present in zebrafish. All zebrafish steroid receptors have been characterized in detail, and their expression patterns have been analyzed. Functional studies have been performed using morpholino knockdown of receptor expression and zebrafish lines carrying mutations in one of their steroid receptor genes. To investigate the activity of the receptors in vivo, specific zebrafish reporter lines have been developed, and transcriptomic studies have been carried out to identify biomarkers for steroid receptor action. In this review, an overview of research on steroid receptors in zebrafish is presented, and it is concluded that further exploitation of the possibilities of the zebrafish model system will contribute significantly to the advancement of steroid receptor research in the next decade.

  19. How calcium makes endocytic receptors attractive

    DEFF Research Database (Denmark)

    Andersen, Christian B F; Moestrup, Søren K

    2014-01-01

    of the receptor. Endosomal acidification and calcium efflux lead to the essential ligand-receptor affinity switch and separation. Recent data, including crystal structures of receptor-ligand complexes, now reveal how calcium, in different types of domain scaffolds, functions in a common way as a removable...... 'lynchpin' that stabilizes favorable positioning of ligand-attractive receptor residues. In addition to explaining how calcium depletion can cause ligand-receptor dissociation, the new data add further insight into how acidification contributes to dissociation through structural changes that affect...... the receptor calcium sites....

  20. Specific profiles of ion channels and ionotropic receptors define adipose- and bone marrow derived stromal cells.

    Czech Academy of Sciences Publication Activity Database

    Forostyak, Oksana; Butenko, Olena; Anděrová, Miroslava; Forostyak, Serhiy; Syková, Eva; Verkhratsky, A.; Dayanithi, Govindan

    2016-01-01

    Roč. 16, č. 3 (2016), s. 622-634 ISSN 1873-5061 R&D Projects: GA ČR(CZ) GA14-34077S; GA ČR(CZ) GAP304/11/2373; GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:68378041 Keywords : adipose derived stromal cells * bone marrow stromal cell * Ca(2+) signaling * Ion channels Subject RIV: FH - Neurology Impact factor: 3.494, year: 2016

  1. Radiosequence analysis of the human progestin receptor charged with [3H]promegestone. A comparison with the glucocorticoid receptor

    International Nuclear Information System (INIS)

    Stroemstedt, P.E.B.; Berkenstam, A.; Joernvall, H.G.; Gustafsson, J.A.; Carlstedt-Duke, J.

    1990-01-01

    Partially purified preparations of the human progestin receptor and the human and rat glucocorticoid receptor proteins were covalently charged with the synthetic progestin, [ 3 H]promegestone, by photoaffinity labeling. After labeling, the denaturated protein was cleaved and the mixture of peptides subjected to radiosequence analysis as previously described for the rat glucocorticoid receptor protein. The radioactivity labels identified, corresponded to Met-759 and Met-909 after photoaffinity labeling of the human progestin receptor, and Met-622 and Cys-754 after labeling of the rat glucocorticoid receptor. The residues labeled in the glucocorticoid receptor are the same as those previously reported to bind triamcinolone actonide. The corresponding residues were also labeled in the human glucocorticoid receptor. Met-759 of the progestin receptor and Met-622 of the rat glucocorticoid receptor are positioned within a segment with an overall high degree of sequence similarity and are equivalent. However, Met-909 (progestin receptor) and Cys-754 (glucocorticoid receptor) do not occur within equivalent segments of the two proteins. Thus, although the two classes of steroid hormone share a common structure within the A-ring, there are subtle differences in their interaction with the two separate receptor proteins

  2. Toll-like receptors in neonatal sepsis.

    LENUS (Irish Health Repository)

    O'Hare, Fiona M

    2013-06-01

    Toll-like receptors are vital transmembrane receptors that initiate the innate immune response to many micro-organisms. The discovery of these receptors has improved our understanding of host-pathogen interactions, and these receptors play an important role in the pathogenesis of multiple neonatal conditions such as sepsis and brain injury. Toll-like receptors, especially TLRs 2 and 4, are associated with necrotizing enterocolitis, periventricular leukomalacia and sepsis.

  3. Labeled receptor ligands for spect

    International Nuclear Information System (INIS)

    Kung, H.F.

    1989-01-01

    Receptor specific imaging agents for single photon emission computed tomography (SPECT) can potentially be useful in the understanding of basic biochemistry and pharmacology of receptors. SPECT images may also provide tools for evaluation of density and binding kinetics of a specific receptor, information important for diagnosis and patient management. Basic requirements for receptor imaging agents are: (a) they are labeled with short-lived isotopes, (b) they show high selectivity and specific uptake, (c) they exhibit high target/background ratio, and (d) they can be modeled to obtain quantitative information. Several good examples of CNS receptor specific ligands labeled with I-123 have been developed, including iodoQNB, iodoestrogen iodobenzadiazepine, iodobenazepine, iodobenzamides for muscarinic, estrogen benzadiazepine, D-1 and D-2 dopamine receptors. With the advent of newer and faster SPECT imaging devices, it may be feasible to quantitate the receptor density by in vivo imaging techniques. These new brain imaging agents can provide unique diagnostic information, which may not be available through other imaging modalities, such as CT and MRI

  4. The alpha-fetoprotein third domain receptor binding fragment: in search of scavenger and associated receptor targets.

    Science.gov (United States)

    Mizejewski, G J

    2015-01-01

    Recent studies have demonstrated that the carboxyterminal third domain of alpha-fetoprotein (AFP-CD) binds with various ligands and receptors. Reports within the last decade have established that AFP-CD contains a large fragment of amino acids that interact with several different receptor types. Using computer software specifically designed to identify protein-to-protein interaction at amino acid sequence docking sites, the computer searches identified several types of scavenger-associated receptors and their amino acid sequence locations on the AFP-CD polypeptide chain. The scavenger receptors (SRs) identified were CD36, CD163, Stabilin, SSC5D, SRB1 and SREC; the SR-associated receptors included the mannose, low-density lipoprotein receptors, the asialoglycoprotein receptor, and the receptor for advanced glycation endproducts (RAGE). Interestingly, some SR interaction sites were localized on the AFP-derived Growth Inhibitory Peptide (GIP) segment at amino acids #480-500. Following the detection studies, a structural subdomain analysis of both the receptor and the AFP-CD revealed the presence of epidermal growth factor (EGF) repeats, extracellular matrix-like protein regions, amino acid-rich motifs and dimerization subdomains. For the first time, it was reported that EGF-like sequence repeats were identified on each of the three domains of AFP. Thereafter, the localization of receptors on specific cell types were reviewed and their functions were discussed.

  5. Modulating Estrogen Receptor-related Receptor-α Activity Inhibits Cell Proliferation*

    Science.gov (United States)

    Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

    2009-01-01

    High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERRα-dependent manner. XCT790 induces, in a p53-independent manner, the expression of the cell cycle inhibitor p21waf/cip1 at the protein, mRNA, and promoter level, leading to an accumulation of hypophosphorylated Rb. Finally, XCT790 reduces cell tumorigenicity in Nude mice. PMID:19546226

  6. Functionally biased signalling properties of 7TM receptors - opportunities for drug development for the ghrelin receptor

    DEFF Research Database (Denmark)

    Sivertsen, B; Holliday, N; Madsen, A N

    2013-01-01

    UNLABELLED: The ghrelin receptor is a 7 transmembrane (7TM) receptor involved in a variety of physiological functions including growth hormone secretion, increased food intake and fat accumulation as well as modulation of reward and cognitive functions. Because of its important role in metabolism...... and energy expenditure, the ghrelin receptor has become an important therapeutic target for drug design and the development of anti-obesity compounds. However, none of the compounds developed so far have been approved for commercial use. Interestingly, the ghrelin receptor is able to signal through several...... review, we have described how ligands and mutations in the 7TM receptor may bias the receptors to favour either one G-protein over another or to promote G-protein independent signalling pathways rather than G-protein-dependent pathways. For the ghrelin receptor, both agonist and inverse agonists have...

  7. Dynamics of the actin cytoskeleton mediates receptor cross talk: An emerging concept in tuning receptor signaling

    Science.gov (United States)

    Mattila, Pieta K.; Batista, Facundo D.

    2016-01-01

    Recent evidence implicates the actin cytoskeleton in the control of receptor signaling. This may be of particular importance in the context of immune receptors, such as the B cell receptor, where dysregulated signaling can result in autoimmunity and malignancy. Here, we discuss the role of the actin cytoskeleton in controlling receptor compartmentalization, dynamics, and clustering as a means to regulate receptor signaling through controlling the interactions with protein partners. We propose that the actin cytoskeleton is a point of integration for receptor cross talk through modulation of protein dynamics and clustering. We discuss the implication of this cross talk via the cytoskeleton for both ligand-induced and low-level constitutive (tonic) signaling necessary for immune cell survival. PMID:26833785

  8. DMPD: Toll-like receptor 3: a link between toll-like receptor, interferon and viruses. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 15031527 Toll-like receptor 3: a link between toll-like receptor, interferon and virus... (.csml) Show Toll-like receptor 3: a link between toll-like receptor, interferon and viruses. PubmedID 1503...1527 Title Toll-like receptor 3: a link between toll-like receptor, interferon and virus

  9. Andrographolide regulates epidermal growth factor receptor and transferrin receptor trafficking in epidermoid carcinoma (A-431) cells

    Science.gov (United States)

    Tan, Y; Chiow, KH; Huang, D; Wong, SH

    2010-01-01

    Background and purpose: Andrographolide is the active component of Andrographis paniculata, a plant used in both Indian and Chinese traditional medicine, and it has been demonstrated to induce apoptosis in different cancer cell lines. However, not much is known about how it may affect the key receptors implicated in cancer. Knowledge of how andrographolide affects receptor trafficking will allow us to better understand new mechanisms by which andrographolide may cause death in cancer cells. Experimental approach: We utilized the well-characterized epidermal growth factor receptor (EGFR) and transferrin receptor (TfR) expressed in epidermoid carcinoma (A-431) cells as a model to study the effect of andrographolide on receptor trafficking. Receptor distribution, the total number of receptors and surface receptors were analysed by immunofluorescence, Western blot as well as flow-cytometry respectively. Key results: Andrographolide treatment inhibited cell growth, down-regulated EGFRs on the cell surface and affected the degradation of EGFRs and TfRs. The EGFR was internalized into the cell at an increased rate, and accumulated in a compartment that co-localizes with the lysosomal-associated membrane protein in the late endosomes. Conclusion and implications: This study sheds light on how andrographolide may affect receptor trafficking by inhibiting receptor movement from the late endosomes to lysosomes. The down-regulation of EGFR from the cell surface also indicates a new mechanism by which andrographolide may induce cancer cell death. PMID:20233216

  10. In vivo studies of opiate receptors

    International Nuclear Information System (INIS)

    Frost, J.J.; Dannals, R.F.; Duelfer, T.; Burns, H.D.; Ravert, H.T.; Langstroem, B.; Balasubramanian, V.; Wagner, H.N. Jr.

    1984-01-01

    To study opiate receptors noninvasively in vivo using positron emission tomography, techniques for preferentially labeling opiate receptors in vivo can be used. The rate at which receptor-bound ligand clears from the brain in vivo can be predicted by measuring the equilibrium dissociation constant (KD) at 37 degrees C in the presence of 100 mM sodium chloride and 100 microM guanyl-5'-imidodiphosphate, the drug distribution coefficient, and the molecular weight. A suitable ligand for labeling opiate receptors in vivo is diprenorphine, which binds to mu, delta, and kappa receptors with approximately equal affinity in vitro. However, in vivo diprenorphine may bind predominantly to one opiate receptor subtype, possibly the mu receptor. To predict the affinity for binding to the opiate receptor, a Hansch correlation was determined between the 50% inhibitory concentration for a series of halogen-substituted fentanyl analogs and electronic, lipophilic, and steric parameters. Radiochemical methods for the synthesis of carbon-11-labeled diprenorphine and lofentanil are presented

  11. In vivo studies of opiate receptors

    Energy Technology Data Exchange (ETDEWEB)

    Frost, J.J.; Dannals, R.F.; Duelfer, T.; Burns, H.D.; Ravert, H.T.; Langstroem, B.; Balasubramanian, V.; Wagner, H.N. Jr.

    1984-01-01

    To study opiate receptors noninvasively in vivo using positron emission tomography, techniques for preferentially labeling opiate receptors in vivo can be used. The rate at which receptor-bound ligand clears from the brain in vivo can be predicted by measuring the equilibrium dissociation constant (KD) at 37 degrees C in the presence of 100 mM sodium chloride and 100 microM guanyl-5'-imidodiphosphate, the drug distribution coefficient, and the molecular weight. A suitable ligand for labeling opiate receptors in vivo is diprenorphine, which binds to mu, delta, and kappa receptors with approximately equal affinity in vitro. However, in vivo diprenorphine may bind predominantly to one opiate receptor subtype, possibly the mu receptor. To predict the affinity for binding to the opiate receptor, a Hansch correlation was determined between the 50% inhibitory concentration for a series of halogen-substituted fentanyl analogs and electronic, lipophilic, and steric parameters. Radiochemical methods for the synthesis of carbon-11-labeled diprenorphine and lofentanil are presented.

  12. Differential trafficking of AMPA receptors following activation of NMDA receptors and mGluRs

    Directory of Open Access Journals (Sweden)

    Sanderson Thomas M

    2011-07-01

    Full Text Available Abstract The removal of AMPA receptors from synapses is a major component of long-term depression (LTD. How this occurs, however, is still only partially understood. To investigate the trafficking of AMPA receptors in real-time we previously tagged the GluA2 subunit of AMPA receptors with ecliptic pHluorin and studied the effects of NMDA receptor activation. In the present study we have compared the effect of NMDA receptor and group I mGluR activation, using GluA2 tagged with super ecliptic pHluorin (SEP-GluA2 expressed in cultured hippocampal neurons. Surprisingly, agonists of the two receptors, which are both able to induce chemical forms of LTD, had clearly distinct effects on AMPA receptor trafficking. In agreement with our previous work we found that transient NMDA receptor activation results in an initial decrease in surface GluA2 from extrasynaptic sites followed by a delayed reduction in GluA2 from puncta (putative synapses. In contrast, transient activation of group I mGluRs, using DHPG, led to a pronounced but more delayed decrease in GluA2 from the dendritic shafts. Surprisingly, there was no average change in the fluorescence of the puncta. Examination of fluorescence at individual puncta, however, indicated that alterations did take place, with some puncta showing an increase and others a decrease in fluorescence. The effects of DHPG were, like DHPG-induced LTD, prevented by treatment with a protein tyrosine phosphatase (PTP inhibitor. The electrophysiological correlate of the effects of DHPG in the SEP-GluA2 infected cultures was a reduction in mEPSC frequency with no change in amplitude. The implications of these findings for the initial mechanisms of expression of both NMDA receptor- and mGluR-induced LTD are discussed.

  13. Role of tonic GABAergic currents during pre- and early postnatal rodent development

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    Werner eKilb

    2013-09-01

    Full Text Available In the last three decades it became evident that the GABAergic system plays an essential role for the development of the central nervous system, by influencing the proliferation of neuronal precursors, neuronal migration and differentiation, as well as by controlling early activity patterns and thus formation of neuronal networks. GABA controls neuronal development via depolarizing membrane responses upon activation of ionotropic GABA receptors. However, many of these effects occur before the onset of synaptic GABAergic activity and thus require the presence of extrasynaptic tonic currents in neuronal precursors and immature neurons. This review summarizes our current knowledge about the role of tonic GABAergic currents during early brain development. In this review we compare the temporal sequence of the expression and functional relevance of different GABA receptor subunits, GABA synthesizing enzymes and GABA transporters. We also refer to other possible endogenous agonists of GABAA receptors. In addition, we describe functional consequences mediated by the GABAergic system during early developmental periods and discuss current models about the origin of extrasynaptic GABA and/or other endogenous GABAergic agonists during early developmental states. Finally, we present evidence that tonic GABAergic activity is also critically involved in the generation of physiological as well as pathophysiological activity patterns before and after the establishment of functional GABAergic synaptic connections.

  14. Characterization of melanocortin receptor ligands on cloned brain melanocortin receptors and on grooming behavior in the rat

    NARCIS (Netherlands)

    Gispen, W.H.; Adan, R.A.H.; Szklarczyk, A.W.; Oosterom, J.; Brakkee, J.H.; Nijenhuis, W.A.; Schaaper, W.M.; Meloen, R.H.

    1999-01-01

    Since the melanocortin MC3 and melanocortin MC4 receptors are the main melanocortin receptor subtypes expressed in rat brain, we characterized the activity and affinity of nine melanocortin receptor ligands using these receptors in vitro, as well as their activity in a well-defined

  15. A bioluminescence resonance energy transfer 2 (BRET2) assay for monitoring seven transmembrane receptor and insulin receptor crosstalk

    DEFF Research Database (Denmark)

    Sanni, Samra Joke; Kulahin, Nikolaj; Jorgensen, Rasmus

    2017-01-01

    The angiotensin AT1 receptor is a seven transmembrane (7TM) receptor, which mediates the regulation of blood pressure. Activation of angiotensin AT1 receptor may lead to impaired insulin signaling indicating crosstalk between angiotensin AT1 receptor and insulin receptor signaling pathways....... To elucidate the molecular mechanisms behind this crosstalk, we applied the BRET2 technique to monitor the effect of angiotensin II on the interaction between Rluc8 tagged insulin receptor and GFP2 tagged insulin receptor substrates 1, 4, 5 (IRS1, IRS4, IRS5) and Src homology 2 domain-containing protein (Shc......). We demonstrate that angiotensin II reduces the interaction between insulin receptor and IRS1 and IRS4, respectively, while the interaction with Shc is unaffected, and this effect is dependent on Gαq activation. Activation of other Gαq-coupled 7TM receptors led to a similar reduction in insulin...

  16. The repertoire of olfactory C family G protein-coupled receptors in zebrafish: candidate chemosensory receptors for amino acids

    Directory of Open Access Journals (Sweden)

    Ngai John

    2006-12-01

    Full Text Available Abstract Background Vertebrate odorant receptors comprise at least three types of G protein-coupled receptors (GPCRs: the OR, V1R, and V2R/V2R-like receptors, the latter group belonging to the C family of GPCRs. These receptor families are thought to receive chemosensory information from a wide spectrum of odorant and pheromonal cues that influence critical animal behaviors such as feeding, reproduction and other social interactions. Results Using genome database mining and other informatics approaches, we identified and characterized the repertoire of 54 intact "V2R-like" olfactory C family GPCRs in the zebrafish. Phylogenetic analysis – which also included a set of 34 C family GPCRs from fugu – places the fish olfactory receptors in three major groups, which are related to but clearly distinct from other C family GPCRs, including the calcium sensing receptor, metabotropic glutamate receptors, GABA-B receptor, T1R taste receptors, and the major group of V2R vomeronasal receptor families. Interestingly, an analysis of sequence conservation and selective pressure in the zebrafish receptors revealed the retention of a conserved sequence motif previously shown to be required for ligand binding in other amino acid receptors. Conclusion Based on our findings, we propose that the repertoire of zebrafish olfactory C family GPCRs has evolved to allow the detection and discrimination of a spectrum of amino acid and/or amino acid-based compounds, which are potent olfactory cues in fish. Furthermore, as the major groups of fish receptors and mammalian V2R receptors appear to have diverged significantly from a common ancestral gene(s, these receptors likely mediate chemosensation of different classes of chemical structures by their respective organisms.

  17. Intracellular insulin-receptor dissociation and segregation in a rat fibroblast cell line transfected with a human insulin receptor gene

    International Nuclear Information System (INIS)

    Levy, J.R.; Olefsky, J.M.

    1988-01-01

    The cellular processing of insulin and insulin receptors was studied using a rat fibroblast cell line that had been transfected with a normal human insulin receptor gene, expressing approximately 500 times the normal number of native fibroblasts insulin receptors. These cells bind and internalize insulin normally. Biochemically assays based on the selective precipitation by polyethylene glycol of intact insulin-receptor complexes but not of free intracellular insulin were developed to study the time course of intracellular insulin-receptor dissociation. Fibroblasts were incubated with radiolabeled insulin at 4 0 C, and internalization of insulin-receptor complexes was initiated by warming the cells to 37 0 C. Within 2 min, 90% of the internalized radioactivity was composed of intact insulin-receptor complexes. The dissociation of insulin from internalized insulin-receptor complexes was markedly inhibited by monensin and chloroquine. Furthermore, chloroquine markedly increased the number of cross-linkable intracellular insulin-receptor complexes, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiography. These findings suggest that acidification of intracellular vesicles is responsible for insulin-receptor dissociation. Physical segregation of dissociated intracellular insulin from its receptor was monitored. The results are consistent with the view that segregation of insulin and receptor occurs 5-10 min after initiation of dissociation. These studies demonstrate the intracellular itinerary of insulin-receptor complexes, including internalization, dissociation of insulin from the internalized receptor within an acidified compartment, segregation of insulin from the receptor, and subsequent ligand degradation

  18. Functional ET(A)-ET(B) Receptor Cross-talk in Basilar Artery In Situ From ET(B) Receptor Deficient Rats.

    Science.gov (United States)

    Yoon, SeongHun; Gariepy, Cheryl E; Yanagisawa, Masashi; Zuccarello, Mario; Rapoport, Robert M

    2016-03-01

    The role of endothelin (ET)(A)-ET(B) receptor cross-talk in limiting the ET(A) receptor antagonist inhibition of ET-1 constriction is revealed by the partial or complete dependency of the ET(A) receptor antagonist inhibition on functional removal of the ET(B) receptor. Although functional removal of the ET(B) receptor is generally accomplished with ET(B) receptor antagonist, a novel approach using rats containing a naturally occurring deletion mutation in the ET(B) receptor [rescued "spotting lethal" (sl) rats; ET(B)(sl/sl)] demonstrated increased ET(A) receptor antagonist inhibition of ET-1 constriction in vena cava. We investigated whether this deletion mutation was also sufficient to remove the ET(B) receptor dependency of the ET(A) receptor antagonist inhibition of ET-1 constriction in the basilar artery. Consistent with previous reports, ET-1 plasma levels were elevated in ET(B)(sl/sl) as compared with ET(B)(+/+) rats. ET(B) receptor antagonist failed to relax the ET-1 constricted basilar artery from ET(B)(+/+) and ET(B)(sl/sl) rats. Relaxation to combined ET(A) and ET(B) receptor antagonist was greater than relaxation to ET(A) receptor antagonist in the basilar artery from ET(B)(+/+) and, unexpectedly, ET(B)(sl/sl) rats. These findings confirm the presence of ET(A)-ET(B) receptor cross-talk in the basilar artery. We speculate that mutant ET(B) receptor expression produced by alternative splicing may be sufficient to allow cross-talk.

  19. Hypoxia increases pulmonary arterial thromboxane receptor internalization independent of receptor sensitization.

    Science.gov (United States)

    Fediuk, J; Sikarwar, A S; Lizotte, P P; Hinton, M; Nolette, N; Dakshinamurti, S

    2015-02-01

    Persistent Pulmonary Hypertension of the Newborn (PPHN) is characterized by sustained vasospasm and an increased thromboxane:prostacyclin ratio. Thromboxane (TP) receptors signal via Gαq to mobilize IP3 and Ca(2+), causing pulmonary arterial constriction. We have previously reported increased TP internalization in hypoxic pulmonary arterial (PA) myocytes. Serum-deprived PA myocytes were grown in normoxia (NM) or hypoxia (HM) for 72 h. TP localization was visualized in agonist-naïve and -challenged NM and HM by immunocytochemistry. Pathways for agonist-induced TP receptor internalization were determined by inhibiting caveolin- or clathrin-mediated endocytosis, and caveolar fractionation. Roles of actin and tubulin in TP receptor internalization were assessed using inhibitors of tubulin, actin-stabilizing or -destabilizing agents. PKA, PKC or GRK activation and inhibition were used to determine the kinase responsible for post-agonist receptor internalization. Agonist-naïve HM had decreased cell surface TP, and greater TP internalization after agonist challenge. TP protein did not sort with caveolin-rich fractions. Inhibition of clathrin prevented TP internalization. Both actin-stabilizing and -destabilizing agents prevented TP endocytosis in NM, while normalizing TP internalization in HM. Velocity of TP internalization was unaffected by PKA activity, but PKC activation normalized TP receptor internalization in HM. GRK inhibition had no effect. We conclude that in hypoxic myocytes, TP is internalized faster and to a greater extent than in normoxic controls. Internalization of the agonist-challenged TP requires clathrin, dynamic actin and is sensitive to PKC activity. TP receptor trafficking and signaling in hypoxia are pivotal to understanding increased vasoconstrictor sensitivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Toll-like receptor 2 or toll-like receptor 4 deficiency does not modify lupus in MRLlpr mice.

    Directory of Open Access Journals (Sweden)

    Simon J Freeley

    Full Text Available Systemic lupus erythematosus is an autoimmune disease with a high morbidity and nephritis is a common manifestation. Previous studies in murine lupus models have suggest a role for Toll-like receptor 2 and 4. We examined the role of these molecules in MRL lpr mice which is one of the most established and robust murine models. We compared disease parameters in Toll-like receptor 2 or Toll-like receptor 4 deficient mice with their littermate controls. We found no difference in the severity of glomerulonephritis as assessed by histology, serum creatinine and albuminuria when Toll-like receptor 2 or Toll-like receptor 4 deficient MRLlpr mice were compared with Toll-like receptor sufficient controls. We also found similar levels of anti-dsDNA and anti-ssDNA antibodies. These results show that Toll-like receptor 2 and Toll-like receptor 4 do not play a significant role in MRLlpr mice, and therefore they may not be important in human lupus.

  1. Involvement of direct inhibition of NMDA receptors in the effects of sigma-receptor ligands on glutamate neurotoxicity in vitro.

    Science.gov (United States)

    Nishikawa, H; Hashino, A; Kume, T; Katsuki, H; Kaneko, S; Akaike, A

    2000-09-15

    This study was performed to examine the roles of the N-methyl-D-aspartate (NMDA) receptor/phencyclidine (PCP) channel complex in the protective effects of sigma-receptor ligands against glutamate neurotoxicity in cultured cortical neurons derived from fetal rats. A 1-h exposure of cultures to glutamate caused a marked loss of viability, as determined by Trypan blue exclusion. This acute neurotoxicity of glutamate was prevented by NMDA receptor antagonists. Expression of sigma(1) receptor mRNA in cortical cultures was confirmed by reverse transcription polymerase chain reaction (RT-PCR). sigma Receptor ligands with affinity for NMDA receptor channels including the PCP site, such as (+)-N-allylnormetazocine ((+)-SKF10,047), haloperidol, and R(-)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane ((-)-PPAP), prevented glutamate neurotoxicity in a concentration-dependent manner. In contrast, other sigma-receptor ligands without affinity for NMDA receptors, such as carbetapentane and R(+)-3-(3-hydroxyphenyl)-N-propylpiperidine ((+)-3-PPP), did not show neuroprotective effects. Putative endogenous sigma receptor ligands such as pregnenolone, progesterone, and dehydroepiandrosterone did not affect glutamate neurotoxicity. The protective effects of (+)-SKF10,047, haloperidol, and (-)-PPAP were not affected by the sigma(1) receptor antagonist rimcazole. These results suggested that a direct interaction with NMDA receptors but not with sigma receptors plays a crucial role in the neuroprotective effects of sigma receptor ligands with affinity for NMDA receptors.

  2. β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo

    Science.gov (United States)

    Jiang, Youde; Zhang, Qiuhua; Ye, Eun-Ah

    2014-01-01

    Purpose Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. Methods Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1Ser307, and IRTyr960. Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. Results A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. Conclusions Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance–based retinal cell apoptosis. PMID:24966659

  3. Protein Connectivity in Chemotaxis Receptor Complexes.

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    Stephan Eismann

    2015-12-01

    Full Text Available The chemotaxis sensory system allows bacteria such as Escherichia coli to swim towards nutrients and away from repellents. The underlying pathway is remarkably sensitive in detecting chemical gradients over a wide range of ambient concentrations. Interactions among receptors, which are predominantly clustered at the cell poles, are crucial to this sensitivity. Although it has been suggested that the kinase CheA and the adapter protein CheW are integral for receptor connectivity, the exact coupling mechanism remains unclear. Here, we present a statistical-mechanics approach to model the receptor linkage mechanism itself, building on nanodisc and electron cryotomography experiments. Specifically, we investigate how the sensing behavior of mixed receptor clusters is affected by variations in the expression levels of CheA and CheW at a constant receptor density in the membrane. Our model compares favorably with dose-response curves from in vivo Förster resonance energy transfer (FRET measurements, demonstrating that the receptor-methylation level has only minor effects on receptor cooperativity. Importantly, our model provides an explanation for the non-intuitive conclusion that the receptor cooperativity decreases with increasing levels of CheA, a core signaling protein associated with the receptors, whereas the receptor cooperativity increases with increasing levels of CheW, a key adapter protein. Finally, we propose an evolutionary advantage as explanation for the recently suggested CheW-only linker structures.

  4. Structural Insights into Selective Ligand-Receptor Interactions Leading to Receptor Inactivation Utilizing Selective Melanocortin 3 Receptor Antagonists.

    Science.gov (United States)

    Cai, Minying; Marelli, Udaya Kiran; Mertz, Blake; Beck, Johannes G; Opperer, Florian; Rechenmacher, Florian; Kessler, Horst; Hruby, Victor J

    2017-08-15

    Systematic N-methylated derivatives of the melanocortin receptor ligand, SHU9119, lead to multiple binding and functional selectivity toward melanocortin receptors. However, the relationship between N-methylation-induced conformational changes in the peptide backbone and side chains and melanocortin receptor selectivity is still unknown. We conducted comprehensive conformational studies in solution of two selective antagonists of the third isoform of the melanocortin receptor (hMC3R), namely, Ac-Nle-c[Asp-NMe-His 6 -d-Nal(2') 7 -NMe-Arg 8 -Trp 9 -Lys]-NH 2 (15) and Ac-Nle-c[Asp-His 6 -d-Nal(2') 7 -NMe-Arg 8 -NMe-Trp 9 -NMe-Lys]-NH 2 (17). It is known that the pharmacophore (His 6 -DNal 7 -Arg 8 -Trp 9 ) of the SHU-9119 peptides occupies a β II-turn-like region with the turn centered about DNal 7 -Arg 8 . The analogues with hMC3R selectivity showed distinct differences in the spatial arrangement of the Trp 9 side chains. In addition to our NMR studies, we also carried out molecular-level interaction studies of these two peptides at the homology model of hMC3R. Earlier chimeric human melanocortin 3 receptor studies revealed insights regarding the binding and functional sites of hMC3R selectivity. Upon docking of peptides 15 and 17 to the binding pocket of hMC3R, it was revealed that Arg 8 and Trp 9 side chains are involved in a majority of the interactions with the receptor. While Arg 8 forms polar contacts with D154 and D158 of hMC3R, Trp 9 utilizes π-π stacking interactions with F295 and F298, located on the transmembrane domain of hMC3R. It is hypothesized that as the frequency of Trp 9 -hMC3R interactions decrease, antagonistic activity increases. The absence of any interactions of the N-methyl groups with hMC3R suggests that their primary function is to modulate backbone conformations of the ligands.

  5. Constitutive dimerization of the G-protein coupled receptor, neurotensin receptor 1, reconstituted into phospholipid bilayers.

    Science.gov (United States)

    Harding, Peter J; Attrill, Helen; Boehringer, Jonas; Ross, Simon; Wadhams, George H; Smith, Eleanor; Armitage, Judith P; Watts, Anthony

    2009-02-01

    Neurotensin receptor 1 (NTS1), a Family A G-protein coupled receptor (GPCR), was expressed in Escherichia coli as a fusion with the fluorescent proteins eCFP or eYFP. A fluorophore-tagged receptor was used to study the multimerization of NTS1 in detergent solution and in brain polar lipid bilayers, using fluorescence resonance energy transfer (FRET). A detergent-solubilized receptor was unable to form FRET-competent complexes at concentrations of up to 200 nM, suggesting that the receptor is monomeric in this environment. When reconstituted into a model membrane system at low receptor density, the observed FRET was independent of agonist binding, suggesting constitutive multimer formation. In competition studies, decreased FRET in the presence of untagged NTS1 excludes the possibility of fluorescent protein-induced interactions. A simulation of the experimental data indicates that NTS1 exists predominantly as a homodimer, rather than as higher-order multimers. These observations suggest that, in common with several other Family A GPCRs, NTS1 forms a constitutive dimer in lipid bilayers, stabilized through receptor-receptor interactions in the absence of other cellular signaling components. Therefore, this work demonstrates that well-characterized model membrane systems are useful tools for the study of GPCR multimerization, allowing fine control over system composition and complexity, provided that rigorous control experiments are performed.

  6. Principal cell spiking, postsynaptic excitation, and oxygen consumption in the rat cerebellar cortex

    DEFF Research Database (Denmark)

    Thomsen, Kirsten; Piilgaard, Henning; Gjedde, Albert

    2009-01-01

    excitatory synaptic input. Subsequent inhibition of action potential propagation and neurotransmission by blocking voltage-gated Na+-channels eliminated the increases in CMRO2 due to PF stimulation and increased PC spiking, but left a large fraction of CMRO2, i.e., basal CMRO2, intact. In conclusion, whereas......) of postsynaptic excitation and PC spiking during evoked and ongoing neuronal activity in the rat. By inhibiting excitatory synaptic input using ionotropic glutamate receptor blockers, we found that the increase in CMRO2 evoked by parallel fiber (PF) stimulation depended entirely on postsynaptic excitation...... basal CMRO2 in anesthetized animals did not seem to be related to neurosignaling, increases in CMRO2 could be induced by all aspects of neurosignaling. Our findings imply that CMRO2 responses cannot a priori be assigned to specific neuronal activities....

  7. Urotensin II modulates rapid eye movement sleep through activation of brainstem cholinergic neurons

    DEFF Research Database (Denmark)

    Huitron-Resendiz, Salvador; Kristensen, Morten Pilgaard; Sánchez-Alavez, Manuel

    2005-01-01

    administration of UII into the PPT nucleus increases REM sleep without inducing changes in the cortical blood flow. Intracerebroventricular injection of UII enhances both REM sleep and wakefulness and reduces slow-wave sleep 2. Intracerebroventricular, but not local, administration of UII increases cortical...... dorsal tegmental nuclei. This distribution suggests that the UII system is involved in functions regulated by acetylcholine, such as the sleep-wake cycle. Here, we tested the hypothesis that UII influences cholinergic PPT neuron activity and alters rapid eye movement (REM) sleep patterns in rats. Local...... synaptic transmission because it persisted in the presence of TTX and antagonists of ionotropic glutamate, GABA, and glycine receptors. Collectively, these results suggest that UII plays a role in the regulation of REM sleep independently of its cerebrovascular actions by directly activating cholinergic...

  8. The Aromatic Head Group of Spider Toxin Polyamines Influences Toxicity to Cancer Cells.

    Science.gov (United States)

    Wilson, David; Boyle, Glen M; McIntyre, Lachlan; Nolan, Matthew J; Parsons, Peter G; Smith, Jennifer J; Tribolet, Leon; Loukas, Alex; Liddell, Michael J; Rash, Lachlan D; Daly, Norelle L

    2017-10-27

    Spider venoms constitute incredibly diverse libraries of compounds, many of which are involved in prey capture and defence. Polyamines are often prevalent in the venom and target ionotropic glutamate receptors. Here we show that a novel spider polyamine, PA 366 , containing a hydroxyphenyl-based structure is present in the venom of several species of tarantula, and has selective toxicity against MCF-7 breast cancer cells. By contrast, a polyamine from an Australian funnel-web spider venom, which contains an identical polyamine tail to PA 366 but an indole-based head-group, is only cytotoxic at high concentrations. Our results suggest that the ring structure plays a role in the cytotoxicity and that modification to the polyamine head group might lead to more potent and selective compounds with potential as novel cancer treatments.

  9. The Aromatic Head Group of Spider Toxin Polyamines Influences Toxicity to Cancer Cells

    Directory of Open Access Journals (Sweden)

    David Wilson

    2017-10-01

    Full Text Available Spider venoms constitute incredibly diverse libraries of compounds, many of which are involved in prey capture and defence. Polyamines are often prevalent in the venom and target ionotropic glutamate receptors. Here we show that a novel spider polyamine, PA366, containing a hydroxyphenyl-based structure is present in the venom of several species of tarantula, and has selective toxicity against MCF-7 breast cancer cells. By contrast, a polyamine from an Australian funnel-web spider venom, which contains an identical polyamine tail to PA366 but an indole-based head-group, is only cytotoxic at high concentrations. Our results suggest that the ring structure plays a role in the cytotoxicity and that modification to the polyamine head group might lead to more potent and selective compounds with potential as novel cancer treatments.

  10. Interaction of chemokines with their receptors--from initial chemokine binding to receptor activating steps

    DEFF Research Database (Denmark)

    Thiele, Stefanie; Rosenkilde, Mette Marie

    2014-01-01

    and surveillance. Chemokines are a group of 8-12 kDa large peptides with a secondary structure consisting of a flexible N-terminus and a core-domain usually stabilized by two conserved disulfide bridges. They mainly interact with the extracellular domains of their cognate 7TM receptors. Affinityand activity......-contributing interactions are attributed to different domains and known to occur in two steps. Here, knowledge on chemokine and receptor domains involved in the first binding-step and the second activation-step is reviewed. A mechanism comprising at least two steps seems consistent; however, several intermediate...... interactions possibly occur, resulting in a multi-step process, as recently proposed for other 7TM receptors. Overall, the N-terminus of chemokine receptors is pivotal for binding of all chemokines. During receptor activation, differences between the two major chemokine subgroups occur, as CC-chemokines mainly...

  11. Crystal structure of NL63 respiratory coronavirus receptor-binding domain complexed with its human receptor

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kailang; Li, Weikai; Peng, Guiqing; Li, Fang; (Harvard-Med); (UMM-MED)

    2010-03-04

    NL63 coronavirus (NL63-CoV), a prevalent human respiratory virus, is the only group I coronavirus known to use angiotensin-converting enzyme 2 (ACE2) as its receptor. Incidentally, ACE2 is also used by group II SARS coronavirus (SARS-CoV). We investigated how different groups of coronaviruses recognize the same receptor, whereas homologous group I coronaviruses recognize different receptors. We determined the crystal structure of NL63-CoV spike protein receptor-binding domain (RBD) complexed with human ACE2. NL63-CoV RBD has a novel {beta}-sandwich core structure consisting of 2 layers of {beta}-sheets, presenting 3 discontinuous receptor-binding motifs (RBMs) to bind ACE2. NL63-CoV and SARS-CoV have no structural homology in RBD cores or RBMs; yet the 2 viruses recognize common ACE2 regions, largely because of a 'virus-binding hotspot' on ACE2. Among group I coronaviruses, RBD cores are conserved but RBMs are variable, explaining how these viruses recognize different receptors. These results provide a structural basis for understanding viral evolution and virus-receptor interactions.

  12. Fibroblast growth factor receptors in breast cancer.

    Science.gov (United States)

    Wang, Shuwei; Ding, Zhongyang

    2017-05-01

    Fibroblast growth factor receptors are growth factor receptor tyrosine kinases, exerting their roles in embryogenesis, tissue homeostasis, and development of breast cancer. Recent genetic studies have identified some subtypes of fibroblast growth factor receptors as strong genetic loci associated with breast cancer. In this article, we review the recent epidemiological findings and experiment results of fibroblast growth factor receptors in breast cancer. First, we summarized the structure and physiological function of fibroblast growth factor receptors in humans. Then, we discussed the common genetic variations in fibroblast growth factor receptors that affect breast cancer risk. In addition, we also introduced the potential roles of each fibroblast growth factor receptors isoform in breast cancer. Finally, we explored the potential therapeutics targeting fibroblast growth factor receptors for breast cancer. Based on the biological mechanisms of fibroblast growth factor receptors leading to the pathogenesis in breast cancer, targeting fibroblast growth factor receptors may provide new opportunities for breast cancer therapeutic strategies.

  13. Sigma opioid receptor: characterization and co-identity with the phencyclidine receptor

    International Nuclear Information System (INIS)

    Mendelsohn, L.G.; Kalra, V.; Johnson, B.G.; Kerchner, G.A.

    1985-01-01

    The properties of the sigma opioid receptor of rat brain cortex have been characterized using the prototypic ligand (+)-[ 3 H] SKF 10,047. Binding to this receptor was rapid, and equilibrium was obtained within 30 min at 37 degrees C. Specific binding was linear with protein concentration up to 500 micrograms/2 ml and was dependent upon protein integrity. Denaturation by boiling destroyed over 95% of the specific binding. A high-affinity binding site with a KD of 150 +/- 40 nM and a maximum binding of 2.91 +/- 0.84 pmol/mg of protein was determined from a Scatchard plot of the binding data. The addition of salt, either NaCl or CaCl 2 , to the buffers markedly decreased binding, with CaCl 2 being more potent than NaCl. A broad pH optimum for specific binding was observed; maximum binding was at pH 9.0. The affinity of a number of ligands for the sigma site and the phencyclidine receptor were compared. The binding (IC50) of 13 ligands to the sigma site showed a correlation of 0.86 (P less than .01) with binding to the phencyclidine site. The data demonstrate that the biochemical properties of the sigma and phencyclidine receptors are similar and support the view that these receptors are one and the same site

  14. A signal processing analysis of Purkinje cells in vitro

    Directory of Open Access Journals (Sweden)

    Ze'ev R Abrams

    2010-05-01

    Full Text Available Cerebellar Purkinje cells in vitro fire recurrent sequences of Sodium and Calcium spikes. Here, we analyze the Purkinje cell using harmonic analysis, and our experiments reveal that its output signal is comprised of three distinct frequency bands, which are combined using Amplitude and Frequency Modulation (AM/FM. We find that the three characteristic frequencies - Sodium, Calcium and Switching – occur in various combinations in all waveforms observed using whole-cell current clamp recordings. We found that the Calcium frequency can display a frequency doubling of its frequency mode, and the Switching frequency can act as a possible generator of pauses that are typically seen in Purkinje output recordings. Using a reversibly photo-switchable kainate receptor agonist, we demonstrate the external modulation of the Calcium and Switching frequencies. These experiments and Fourier analysis suggest that the Purkinje cell can be understood as a harmonic signal oscillator, enabling a higher level of interpretation of Purkinje signaling based on modern signal processing techniques.

  15. Adenosine Receptors and Wound Healing

    Directory of Open Access Journals (Sweden)

    Bruce N. Cronstein

    2004-01-01

    Full Text Available Recent studies have demonstrated that application of topical adenosine A2A receptor agonists promotes more rapid wound closure and clinical studies are currently underway to determine the utility of topical A2A adenosine receptor agonists in the therapy of diabetic foot ulcers. The effects of adenosine A2A receptors on the cells and tissues of healing wounds have only recently been explored. We review here the known effects of adenosine A2A receptor occupancy on the cells involved in wound healing.

  16. Receptor-targeted metalloradiopharmaceuticals. Final technical report

    International Nuclear Information System (INIS)

    Green, Mark A.

    2000-01-01

    Copper (II) and platinum (II) coordination complexes were prepared and characterized. These complexes were designed to afford structural homology with steroidal and non-steroidal estrogens for possible use as receptor-targeted radiopharmaceuticals. While weak affinity for the estrogen receptor was detectable, none would appear to have sufficient receptor-affinity for estrogen-receptor-targeted imaging or therapy

  17. Rat hepatic β2-adrenergic receptor: structural similarities to the rat fat cell β1-adrenergic receptor

    International Nuclear Information System (INIS)

    Graziano, M.P.

    1984-01-01

    The mammalian β 2 -adrenergic receptor from rat liver has been purified by sequential cycles of affinity chromatography followed by steric-exclusion high performance liquid chromatography. Electrophoresis of highly purified receptor preparations on polyacrylamide gels in the presence of sodium dodecyl sulfate under reducing conditions reveals a single peptide M/sub r/ = 67,000, as judged by silver staining. Purified β 2 -adrenergic receptor migrates on steric-exclusion high performance liquid chromatography in two peaks, with M/sub r/ = 140,000 and 67,000. Specific binding of the high affinity, β-adrenergic receptor antagonists (-)[ 3 H]dihydroalprenolol and (-)[ 125 I]iodocyanopindolol to purified rat liver β-adrenergic receptor preparations displays stereoselectivity for (-)isomers of agonists and a rank order of potencies for agonists characteristics of a β 2 -adrenergic receptor. Radioiodinated, β 1 -adrenergic receptors from rat fat cells and β 2 -adrenergic receptors from rat liver purified in the presence of protease inhibitors comigrate in electrophoretic separations on polyacrylamide gels in the presence of sodium dodecyl sulfate as 67,000-M/sub r/ peptides. Autoradiograms of two dimensional partial proteolytic digests of the purified, radioiodinated rat liver β 2 -adrenergic receptor, generated with α-chymotrypsin, S. aureus V8 protease and elastase reveal a pattern of peptide fragments essentially identical to those generated by partial proteolytic digests of the purified, radioiodinated β 1 -adrenergic receptor from rat fat cells, by these same proteases. These data indicate that a high degree of homology exists between these two pharmacologically distinct mammalian β-adrenergic receptor proteins

  18. Manipulation of Very Few Receptor Discriminator Residues Greatly Enhances Receptor Specificity of Non-visual Arrestins*

    Science.gov (United States)

    Gimenez, Luis E.; Vishnivetskiy, Sergey A.; Baameur, Faiza; Gurevich, Vsevolod V.

    2012-01-01

    Based on the identification of residues that determine receptor selectivity of arrestins and the analysis of the evolution in the arrestin family, we introduced 10 mutations of “receptor discriminator” residues in arrestin-3. The recruitment of these mutants to M2 muscarinic (M2R), D1 (D1R) and D2 (D2R) dopamine, and β2-adrenergic receptors (β2AR) was assessed using bioluminescence resonance energy transfer-based assays in cells. Seven of 10 mutations differentially affected arrestin-3 binding to individual receptors. D260K and Q262P reduced the binding to β2AR, much more than to other receptors. The combination D260K/Q262P virtually eliminated β2AR binding while preserving the interactions with M2R, D1R, and D2R. Conversely, Y239T enhanced arrestin-3 binding to β2AR and reduced the binding to M2R, D1R, and D2R, whereas Q256Y selectively reduced recruitment to D2R. The Y239T/Q256Y combination virtually eliminated the binding to D2R and reduced the binding to β2AR and M2R, yielding a mutant with high selectivity for D1R. Eleven of 12 mutations significantly changed the binding to light-activated phosphorhodopsin. Thus, manipulation of key residues on the receptor-binding surface modifies receptor preference, enabling the construction of non-visual arrestins specific for particular receptor subtypes. These findings pave the way to the construction of signaling-biased arrestins targeting the receptor of choice for research or therapeutic purposes. PMID:22787152

  19. Manipulation of very few receptor discriminator residues greatly enhances receptor specificity of non-visual arrestins.

    Science.gov (United States)

    Gimenez, Luis E; Vishnivetskiy, Sergey A; Baameur, Faiza; Gurevich, Vsevolod V

    2012-08-24

    Based on the identification of residues that determine receptor selectivity of arrestins and the analysis of the evolution in the arrestin family, we introduced 10 mutations of "receptor discriminator" residues in arrestin-3. The recruitment of these mutants to M2 muscarinic (M2R), D1 (D1R) and D2 (D2R) dopamine, and β(2)-adrenergic receptors (β(2)AR) was assessed using bioluminescence resonance energy transfer-based assays in cells. Seven of 10 mutations differentially affected arrestin-3 binding to individual receptors. D260K and Q262P reduced the binding to β(2)AR, much more than to other receptors. The combination D260K/Q262P virtually eliminated β(2)AR binding while preserving the interactions with M2R, D1R, and D2R. Conversely, Y239T enhanced arrestin-3 binding to β(2)AR and reduced the binding to M2R, D1R, and D2R, whereas Q256Y selectively reduced recruitment to D2R. The Y239T/Q256Y combination virtually eliminated the binding to D2R and reduced the binding to β(2)AR and M2R, yielding a mutant with high selectivity for D1R. Eleven of 12 mutations significantly changed the binding to light-activated phosphorhodopsin. Thus, manipulation of key residues on the receptor-binding surface modifies receptor preference, enabling the construction of non-visual arrestins specific for particular receptor subtypes. These findings pave the way to the construction of signaling-biased arrestins targeting the receptor of choice for research or therapeutic purposes.

  20. Laminar pattern of cholinergic and adrenergic receptors in rat visual cortex using quantitative receptor autoradiography

    International Nuclear Information System (INIS)

    Schliebs, R.; Walch, C.

    1989-01-01

    The laminar distribution of muscarinic acetylcholine receptors, including the M1-receptor subtype, of beta-adrenergic receptors, and noradrenaline uptake sites, was studied in the adult rat visual, frontal, somatosensory and motor cortex, using quantitative receptor autoradiography. In the visual cortex, the highest density of muscarinic acetylcholine receptors was found in layer I. From layer II/III to layer V binding decreases continueously reaching a constant binding level in layers V and VI. This laminar pattern of muscarinic receptor density differs somewhat from that observed in the non-visual cortical regions examined: layer II/III contained the highest receptor density followed by layer I and IV: lowest density was found in layer V and VI. The binding profile of the muscarinic cholinergic M1-subtype through the visual cortex shows a peak in cortical layer II and in the upper part of layer VI, whereas in the non-visual cortical regions cited the binding level was high in layer II/III, moderate in layer I and IV, and low in layer VI. Layers I to IV of the visual cortex contained the highest beta-adrenergic receptor densities, whereas only low binding levels were observed in the deeper layers. A similar laminar distribution was found also in the frontal, somatosensory and motor cortex. The density of noradrenaline uptake sites was high in all layers of the cortical regions studied, but with noradrenaline uptake sites somewhat more concentrated in the superficial layers than in deeper ones. The distinct laminar pattern of cholinergic and noradrenergic receptor sites indicates a different role for acetylcholine and noradrenaline in the functional anatomy of the cerebral cortex, and in particular, the visual cortex. (author)

  1. Laminar pattern of cholinergic and adrenergic receptors in rat visual cortex using quantitative receptor autoradiography

    Energy Technology Data Exchange (ETDEWEB)

    Schliebs, R; Walch, C [Leipzig Univ. (German Democratic Republic). Bereich Medizin; Stewart, M G [Open Univ., Milton Keynes (UK)

    1989-01-01

    The laminar distribution of muscarinic acetylcholine receptors, including the M1-receptor subtype, of beta-adrenergic receptors, and noradrenaline uptake sites, was studied in the adult rat visual, frontal, somatosensory and motor cortex, using quantitative receptor autoradiography. In the visual cortex, the highest density of muscarinic acetylcholine receptors was found in layer I. From layer II/III to layer V binding decreases continueously reaching a constant binding level in layers V and VI. This laminar pattern of muscarinic receptor density differs somewhat from that observed in the non-visual cortical regions examined: layer II/III contained the highest receptor density followed by layer I and IV: lowest density was found in layer V and VI. The binding profile of the muscarinic cholinergic M1-subtype through the visual cortex shows a peak in cortical layer II and in the upper part of layer VI, whereas in the non-visual cortical regions cited the binding level was high in layer II/III, moderate in layer I and IV, and low in layer VI. Layers I to IV of the visual cortex contained the highest beta-adrenergic receptor densities, whereas only low binding levels were observed in the deeper layers. A similar laminar distribution was found also in the frontal, somatosensory and motor cortex. The density of noradrenaline uptake sites was high in all layers of the cortical regions studied, but with noradrenaline uptake sites somewhat more concentrated in the superficial layers than in deeper ones. The distinct laminar pattern of cholinergic and noradrenergic receptor sites indicates a different role for acetylcholine and noradrenaline in the functional anatomy of the cerebral cortex, and in particular, the visual cortex. (author).

  2. Radioiodinated ligands for dopamine receptors

    International Nuclear Information System (INIS)

    Kung, H.F.

    1994-01-01

    The dopamine receptor system is important for normal brain function; it is also the apparent action site for various neuroleptic drugs for the treatment of schizophrenia and other metal disorders. In the past few years radioiodinated ligands for single photon emission tomography (SPECT) have been successfully developed and tested in humans: [ 123 I]TISCH for D1 dopamine receptors; [ 123 I]IBZM, epidepride, IBF and FIDA2, four iodobenzamide derivatives, for D2/D3 dopamine receptors. In addition, [ 123 I]β-CIT (RTI-55) and IPT, cocaine derivatives, for the dopamine reuptake site are potentially useful for diagnosis of loss of dopamine neurons. The first iodinated ligand, (R)trans-7-OH-PIPAT, for D3 dopamine receptors, was synthesized and characterized with cloned cell lines (Spodoptera frugiperda, Sf9) expressing the D2 and D3 dopamine receptors and with rat basal forebrain membrane preparations. Most of the known iodobenzamides displayed similar potency in binding to both D2 and D3 dopamine receptors expressed in the cell lines. Initial studies appear to suggest that by fine tuning the structures it may be possible to develop agents specific for D2 and D3 dopamine receptors. It is important to investigate D2/D3 selectivity for this series of potent ligands

  3. Prolactin receptor, growth hormone receptor, and putative somatolactin receptor in Mozambique tilapia: tissue specific expression and differential regulation by salinity and fasting.

    Science.gov (United States)

    Pierce, A L; Fox, B K; Davis, L K; Visitacion, N; Kitahashi, T; Hirano, T; Grau, E G

    2007-01-01

    In fish, pituitary growth hormone family peptide hormones (growth hormone, GH; prolactin, PRL; somatolactin, SL) regulate essential physiological functions including osmoregulation, growth, and metabolism. Teleost GH family hormones have both differential and overlapping effects, which are mediated by plasma membrane receptors. A PRL receptor (PRLR) and two putative GH receptors (GHR1 and GHR2) have been identified in several teleost species. Recent phylogenetic analyses and binding studies suggest that GHR1 is a receptor for SL. However, no studies have compared the tissue distribution and physiological regulation of all three receptors. We sequenced GHR2 from the liver of the Mozambique tilapia (Oreochromis mossambicus), developed quantitative real-time PCR assays for the three receptors, and assessed their tissue distribution and regulation by salinity and fasting. PRLR was highly expressed in the gill, kidney, and intestine, consistent with the osmoregulatory functions of PRL. PRLR expression was very low in the liver. GHR2 was most highly expressed in the muscle, followed by heart, testis, and liver, consistent with this being a GH receptor with functions in growth and metabolism. GHR1 was most highly expressed in fat, liver, and muscle, suggesting a metabolic function. GHR1 expression was also high in skin, consistent with a function of SL in chromatophore regulation. These findings support the hypothesis that GHR1 is a receptor for SL. In a comparison of freshwater (FW)- and seawater (SW)-adapted tilapia, plasma PRL was strongly elevated in FW, whereas plasma GH was slightly elevated in SW. PRLR expression was reduced in the gill in SW, consistent with PRL's function in freshwater adaptation. GHR2 was elevated in the kidney in FW, and correlated negatively with plasma GH, whereas GHR1 was elevated in the gill in SW. Plasma IGF-I, but not GH, was reduced by 4 weeks of fasting. Transcript levels of GHR1 and GHR2 were elevated by fasting in the muscle. However

  4. Hormonal control of spermatogenesis: expression of FSJH receptor and androgen receptor genes

    NARCIS (Netherlands)

    L.J. Blok (Leen)

    1992-01-01

    textabstractFSH and testosterone are the main hormonal regulators of spermatogenesis. The actions of androgens and FSH are mediated by their respective receptors. Receptor gene expression (mRNA and protein). is an important determinant of hormone action. Biochemical aspects of the regulation of

  5. Quantitative autoradiographic mapping of serotonin receptors in the rat brain. II. Serotonin-2 receptors

    International Nuclear Information System (INIS)

    Pazos, A.; Cortes, R.; Palacios, J.M.

    1985-01-01

    The distribution of serotonin-2 (5-HT 2 ) receptors in the rat brain was studied by light microscopic quantitative autoradiography. Receptors were labeled with four ligands: [ 3 H]ketanserin, [ 3 H]mesulergine, [ 3 H]LSD and [ 3 H]spiperone, which are reported to show high affinity for 5-HT 2 receptors. Very high concentrations were localized in the claustrum, olfactory tubercle and layer IV of the neocortex. The anterior olfactory nucleus, piriform cortex and layer I of neocortex were also rich in 5-HT 2 receptors. The specificity of the different ligands used is discussed in terms of the other populations of sites recognized by them. The distribution of 5-HT 2 receptors here reported is discussed in correlation with (a) the known distribution of serotoninergic terminals, (b) the specific anatomical systems and (c) the central effects reported to be mediated by 5-HT 2 -selective drugs. (Auth.)

  6. Neuromedin B receptor in esophagus: evidence for subtypes of bombesin receptors

    International Nuclear Information System (INIS)

    Von Schrenck, T.; Heinz-Erian, P.; Moran, T.; Mantey, S.A.; Gardner, J.D.; Jensen, R.T.

    1989-01-01

    To identify receptors for bombesin-related peptides in the rat esophagus, we measured binding of 125I-Bolton-Hunter neuromedin B (125I-BH-neuromedin B) and 125I-[Tyr4]bombesin to tissue sections from the rat esophagus and compared the results with those for rat pancreas. Esophagus bound both tracers, whereas pancreas bound only 125I-[Tyr4]bombesin. In each tissue binding was saturable, dependent on pH, on time, and on temperature, reversible, and specific. Autoradiography demonstrated binding of both tracers only to the muscularis mucosae of the esophagus and binding of 125I-[Tyr4]bombesin diffusely over pancreatic acini. In the esophagus, the relative potencies for inhibition of binding of both tracers were as follows: neuromedin B greater than bombesin greater than GRP = neuromedin C; similar relative potencies were found for causing contraction of muscle strips from whole esophagus and from the isolated muscularis mucosae. In pancreas tissue sections and dispersed acini, the relative potencies for inhibition of binding of 125I-[Tyr4]bombesin were as follows: bombesin greater than GRP = neuromedin C much greater than neuromedin B. Similar relative potencies were found for stimulation of enzyme secretion from dispersed pancreatic acini. Computer analysis in both tissues demonstrated only a single binding site. The present study demonstrates that rat esophagus muscle possesses specific receptors for bombesin-related peptides. Furthermore, this study shows that the esophageal bombesin receptors represent a previously unidentified class of bombesin receptors in that they have a higher affinity for neuromedin B than for bombesin. In contrast, the pancreatic bombesin receptors have, like all other bombesin receptors described to date, a high affinity for bombesin, but low affinity for neuromedin B

  7. 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.

  8. The importance of the adenosine A(2A) receptor-dopamine D(2) receptor interaction in drug addiction.

    Science.gov (United States)

    Filip, M; Zaniewska, M; Frankowska, M; Wydra, K; Fuxe, K

    2012-01-01

    Drug addiction is a serious brain disorder with somatic, psychological, psychiatric, socio-economic and legal implications in the developed world. Illegal (e.g., psychostimulants, opioids, cannabinoids) and legal (alcohol, nicotine) drugs of abuse create a complex behavioral pattern composed of drug intake, withdrawal, seeking and relapse. One of the hallmarks of drugs that are abused by humans is that they have different mechanisms of action to increase dopamine (DA) neurotransmission within the mesolimbic circuitry of the brain and indirectly activate DA receptors. Among the DA receptors, D(2) receptors are linked to drug abuse and addiction because their function has been proven to be correlated with drug reinforcement and relapses. The recognition that D(2) receptors exist not only as homomers but also can form heteromers, such as with the adenosine (A)(2A) receptor, that are pharmacologically and functionally distinct from their constituent receptors, has significantly expanded the range of potential drug targets and provided new avenues for drug design in the search for novel drug addiction therapies. The aim of this review is to bring current focus on A(2A) receptors, their physiology and pharmacology in the central nervous system, and to discuss the therapeutic relevance of these receptors to drug addiction. We concentrate on the contribution of A(2A) receptors to the effects of different classes of drugs of abuse examined in preclinical behavioral experiments carried out with pharmacological and genetic tools. The consequences of chronic drug treatment on A(2A) receptor-assigned functions in preclinical studies are also presented. Finally, the neurochemical mechanism of the interaction between A(2A) receptors and drugs of abuse in the context of the heteromeric A(2A)-D(2) receptor complex is discussed. Taken together, a significant amount of experimental analyses provide evidence that targeting A(2A) receptors may offer innovative translational strategies

  9. Characterization of astrocytic and neuronal benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bender, A.S.

    1988-01-01

    Primary cultures of astrocytes and neurons express benzodiazepine receptors. Neuronal benzodiazepine receptors were of high-affinity, K{sub D} values were 7.5-43 nM and the densities of receptors (B{sub max}) were 924-4131 fmol/mg protein. Astrocytes posses a high-affinity benzodiazepine receptor, K{sub D} values were 6.6-13 nM. The B{sub max} values were 6,033-12,000 fmol/mg protein. The pharmacological profile of the neuronal benzodiazepine receptor was that of the central-type benzodiazepine receptor, where clonazepam has a high-affinity and Ro 5-4864 (4{prime}-chlorodiazepam) has a low-affinity. Whereas astrocytic benzoidazepine receptor was characteristic of the so called peripheral-type benzodiazepine receptors, which shows a high-affinity towards Ro 5-4863, and a low-affinity towards clonazepam. The astrocytic benzodiazepine receptors was functionally correlated with voltage dependent calcium channels, since dihydropyridines and benzodiazepines interacted with ({sup 3}H) diazepam and ({sup 3}H) nitrendipine receptors with the same rank order of potency, showing a statistically significant correlation. No such correlation was observed in neurons.

  10. Identification of Human P2X1 Receptor-interacting Proteins Reveals a Role of the Cytoskeleton in Receptor Regulation*

    Science.gov (United States)

    Lalo, Ulyana; Roberts, Jonathan A.; Evans, Richard J.

    2011-01-01

    P2X1 receptors are ATP-gated ion channels expressed by smooth muscle and blood cells. Carboxyl-terminally His-FLAG-tagged human P2X1 receptors were stably expressed in HEK293 cells and co-purified with cytoskeletal proteins including actin. Disruption of the actin cytoskeleton with cytochalasin D inhibited P2X1 receptor currents with no effect on the time course of the response or surface expression of the receptor. Stabilization of the cytoskeleton with jasplakinolide had no effect on P2X1 receptor currents but decreased receptor mobility. P2X2 receptor currents were unaffected by cytochalasin, and P2X1/2 receptor chimeras were used to identify the molecular basis of actin sensitivity. These studies showed that the intracellular amino terminus accounts for the inhibitory effects of cytoskeletal disruption similar to that shown for lipid raft/cholesterol sensitivity. Stabilization of the cytoskeleton with jasplakinolide abolished the inhibitory effects of cholesterol depletion on P2X1 receptor currents, suggesting that lipid rafts may regulate the receptor through stabilization of the cytoskeleton. These studies show that the cytoskeleton plays an important role in P2X1 receptor regulation. PMID:21757694

  11. Serotonin Receptors in Hippocampus

    Science.gov (United States)

    Berumen, Laura Cristina; Rodríguez, Angelina; Miledi, Ricardo; García-Alcocer, Guadalupe

    2012-01-01

    Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a functional network that uses several serotonin receptors to regulate their roles in this particular part of the limbic system. PMID:22629209

  12. 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.

  13. Nuclear Receptors, RXR, and the Big Bang.

    Science.gov (United States)

    Evans, Ronald M; Mangelsdorf, David J

    2014-03-27

    Isolation of genes encoding the receptors for steroids, retinoids, vitamin D, and thyroid hormone and their structural and functional analysis revealed an evolutionarily conserved template for nuclear hormone receptors. This discovery sparked identification of numerous genes encoding related proteins, termed orphan receptors. Characterization of these orphan receptors and, in particular, of the retinoid X receptor (RXR) positioned nuclear receptors at the epicenter of the "Big Bang" of molecular endocrinology. This Review provides a personal perspective on nuclear receptors and explores their integrated and coordinated signaling networks that are essential for multicellular life, highlighting the RXR heterodimer and its associated ligands and transcriptional mechanism. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Characterization of G-protein coupled receptor kinase interaction with the neurokinin-1 receptor using bioluminescence resonance energy transfer

    DEFF Research Database (Denmark)

    Jorgensen, Rasmus; Holliday, Nicholas D; Hansen, Jakob L

    2007-01-01

    To analyze the interaction between the neurokinin-1 (NK-1) receptor and G-protein coupled receptor kinases (GRKs), we performed bioluminescence resonance energy transfer(2) (BRET(2)) measurements between the family A NK-1 receptor and GRK2 and GRK5 as well as their respective kinase-inactive muta......To analyze the interaction between the neurokinin-1 (NK-1) receptor and G-protein coupled receptor kinases (GRKs), we performed bioluminescence resonance energy transfer(2) (BRET(2)) measurements between the family A NK-1 receptor and GRK2 and GRK5 as well as their respective kinase...

  15. Signaling cross-talk between peroxisome proliferator-activated receptor/retinoid X receptor and estrogen receptor through estrogen response elements.

    Science.gov (United States)

    Keller, H; Givel, F; Perroud, M; Wahli, W

    1995-07-01

    Peroxisome proliferator-activated receptors (PPARs) and retinoid X receptors (RXRs) are nuclear hormone receptors that are activated by fatty acids and 9-cis-retinoic acid, respectively. PPARs and RXRs form heterodimers that activate transcription by binding to PPAR response elements (PPREs) in the promoter of target genes. The PPREs described thus far consist of a direct tandem repeat of the AGGTCA core element with one intervening nucleotide. We show here that the vitellogenin A2 estrogen response element (ERE) can also function as a PPRE and is bound by a PPAR/RXR heterodimer. Although this heterodimer can bind to several other ERE-related palindromic response elements containing AGGTCA half-sites, only the ERE is able to confer transactivation of test reporter plasmids, when the ERE is placed either close to or at a distance from the transcription initiation site. Examination of natural ERE-containing promoters, including the pS2, very-low-density apolipoprotein II and vitellogenin A2 genes, revealed considerable differences in the binding of PPAR/RXR heterodimers to these EREs. In their natural promoter context, these EREs did not allow transcriptional activation by PPARs/RXRs. Analysis of this lack of stimulation of the vitellogenin A2 promoter demonstrated that PPARs/RXRs bind to the ERE but cannot transactivate due to a nonpermissive promoter structure. As a consequence, PPARs/RXRs inhibit transactivation by the estrogen receptor through competition for ERE binding. This is the first example of signaling cross-talk between PPAR/RXR and estrogen receptor.

  16. Identification and mechanism of ABA receptor antagonism

    KAUST Repository

    Melcher, Karsten; Xu, Yong; Ng, Ley-Moy; Zhou, X. Edward; Soon, Fen-Fen; Chinnusamy, Viswanathan; Suino-Powell, Kelly M.; Kovach, Amanda; Tham, Fook S.; Cutler, Sean R.; Li, Jun; Yong, Eu-Leong; Zhu, Jian-Kang; Xu, H. Eric

    2010-01-01

    The phytohormone abscisic acid (ABA) functions through a family of fourteen PYR/PYL receptors, which were identified by resistance to pyrabactin, a synthetic inhibitor of seed germination. ABA activates these receptors to inhibit type 2C protein phosphatases, such as ABI1, yet it remains unclear whether these receptors can be antagonized. Here we demonstrate that pyrabactin is an agonist of PYR1 and PYL1 but is unexpectedly an antagonist of PYL2. Crystal structures of the PYL2-pyrabactin and PYL1-pyrabactin-ABI1 complexes reveal the mechanism responsible for receptor-selective activation and inhibition, which enables us to design mutations that convert PYL1 to a pyrabactin-inhibited receptor and PYL2 to a pyrabactin-activated receptor and to identify new pyrabactin-based ABA receptor agonists. Together, our results establish a new concept of ABA receptor antagonism, illustrate its underlying mechanisms and provide a rational framework for discovering novel ABA receptor ligands. © 2010 Nature America, Inc. All rights reserved.

  17. Reconstruction of the Chemotaxis Receptor-Kinase Assembly

    International Nuclear Information System (INIS)

    Park, S.; Borbat, P.; Gonzalez-Bonet, G.; Bhatnagar, J.; Pollard, A.; Freed, J.; Bilwes, A.; Crane, B.

    2006-01-01

    In bacterial chemotaxis, an assembly of transmembrane receptors, the CheA histidine kinase and the adaptor protein CheW processes environmental stimuli to regulate motility. The structure of a Thermotoga maritima receptor cytoplasmic domain defines CheA interaction regions and metal ion-coordinating charge centers that undergo chemical modification to tune receptor response. Dimeric CheA-CheW, defined by crystallography and pulsed ESR, positions two CheWs to form a cleft that is lined with residues important for receptor interactions and sized to clamp one receptor dimer. CheW residues involved in kinase activation map to interfaces that orient the CheW clamps. CheA regulatory domains associate in crystals through conserved hydrophobic surfaces. Such CheA self-contacts align the CheW receptor clamps for binding receptor tips. Linking layers of ternary complexes with close-packed receptors generates a lattice with reasonable component ratios, cooperative interactions among receptors and accessible sites for modification enzymes

  18. Identification and mechanism of ABA receptor antagonism

    KAUST Repository

    Melcher, Karsten

    2010-08-22

    The phytohormone abscisic acid (ABA) functions through a family of fourteen PYR/PYL receptors, which were identified by resistance to pyrabactin, a synthetic inhibitor of seed germination. ABA activates these receptors to inhibit type 2C protein phosphatases, such as ABI1, yet it remains unclear whether these receptors can be antagonized. Here we demonstrate that pyrabactin is an agonist of PYR1 and PYL1 but is unexpectedly an antagonist of PYL2. Crystal structures of the PYL2-pyrabactin and PYL1-pyrabactin-ABI1 complexes reveal the mechanism responsible for receptor-selective activation and inhibition, which enables us to design mutations that convert PYL1 to a pyrabactin-inhibited receptor and PYL2 to a pyrabactin-activated receptor and to identify new pyrabactin-based ABA receptor agonists. Together, our results establish a new concept of ABA receptor antagonism, illustrate its underlying mechanisms and provide a rational framework for discovering novel ABA receptor ligands. © 2010 Nature America, Inc. All rights reserved.

  19. Virally encoded 7TM receptors

    DEFF Research Database (Denmark)

    Rosenkilde, M M; Waldhoer, M; Lüttichau, H R

    2001-01-01

    expression of this single gene in certain lymphocyte cell lineages leads to the development of lesions which are remarkably similar to Kaposi's sarcoma, a human herpesvirus 8 associated disease. Thus, this and other virally encoded 7TM receptors appear to be attractive future drug targets.......A number of herpes- and poxviruses encode 7TM G-protein coupled receptors most of which clearly are derived from their host chemokine system as well as induce high expression of certain 7TM receptors in the infected cells. The receptors appear to be exploited by the virus for either immune evasion...

  20. Thyrotropin-luteinizing hormone/chorionic gonadotropin receptor extracellular domain chimeras as probes for thyrotropin receptor function

    International Nuclear Information System (INIS)

    Nagayama, Yuji; Wadsworth, H.L.; Chazenbalk, G.D.; Russo, D.; Seto, Pui; Rapoport, B.

    1991-01-01

    To define the sites in the extracellular domain of the human thyrotropin (TSH) receptor that are involved in TSH binding and signal transduction the authors constructed chimeric thyrotropin-luteinizing hormone/chorionic gonadotropin (TSH-LH/CG) receptors. The extracellular domain of the human TSH receptor was divided into five regions that were replaced, either singly or in various combinations, with homologous regions of the rat LH/CG receptor. The chimeric receptors were stably expressed in Chinese hamster ovary cells. The data obtained suggest that the carboxyl region of the extracellular domain (amino acid residues 261-418) and particularly the middle region (residues 171-260) play a role in signal transduction. The possibility is also raised of an interaction between the amino and carboxyl regions of the extracellular domain in the process of signal transduction. In summary, these studies suggest that the middle region and carboxyl half of the extracellular domain of the TSH receptor are involved in signal transduction and that the TSH-binding region is likely to span the entire extracellular domain, with multiple discontinuous contact sites