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Sample records for glutamate 5a receptors

  1. Glutamate receptors

    DEFF Research Database (Denmark)

    Kristensen, Anders S; Geballe, Matthew T; Snyder, James P

    2006-01-01

    Fast excitatory synaptic transmission in the CNS relies almost entirely on the neurotransmitter glutamate and its family of ion channel receptors. An appreciation of the coupling between agonist binding and channel opening has advanced rapidly during the past five years, largely as a result of ne...

  2. Metabotropic glutamate receptor 5 - a promising target in drug development and neuroimaging

    Energy Technology Data Exchange (ETDEWEB)

    Pillai, Rajapillai L.I.; Tipre, Dnyanesh N. [Stony Brook University Health Science Center, Department of Psychiatry, Stony Brook, NY (United States)

    2016-06-15

    This review summarizes the contributions by various teams of scientists in assessing the metabotropic glutamate receptor 5 (mGluR5) as a biomarker in neuropsychiatric disorders and diseases. Development of positive and negative allosteric modulators of mGluR5 is reviewed, as is the development of PET radioligands that have the potential to measure mGluR5 receptor density in neurological disorders and during therapeutic interventions. PET imaging provides an effective tool to assess the specificity of new drugs, select dose regimens in clinical trials, and study drug mechanisms of action. We summarize and deliver comparative analyses of mGluR5-specific PET radiotracers and their applications in understanding the pathophysiology of mGluR5-related nervous system disorders and to speed up drug development. (orig.)

  3. Glutamate receptor agonists

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  4. Glutamate receptor agonists

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  5. Glutamate receptor ligands

    DEFF Research Database (Denmark)

    Guldbrandt, Mette; Johansen, Tommy N; Frydenvang, Karla Andrea

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA...... or slightly lower potencies than (S)-AA [e.g., EC(50) = 76 microM for (2S,4S)-4-methyl-AA (5a) as compared to EC(50) = 35 microM for (S)-AA]. The position of the methyl substituent had a profound effect on the observed pharmacology, whereas the absolute stereochemistry at the methylated carbon atom had a very......) analogs, and the synthesis, stereochemistry, and enantiopharmacology of 3-methyl-AA (4a-d), 4-methyl-AA (5a-d), 5-methyl-AA (6a-d), and (E)-Delta(4)-5-methyl-AA (7a and 7b) are reported. The compounds were resolved using chiral HPLC and the configurational assignments of the enantiomers were based on X...

  6. Metabotropic glutamate receptors in glial cells

    NARCIS (Netherlands)

    D'Antoni, Simona; Berretta, Antonio; Bonaccorso, Carmela Maria; Bruno, Valeria; Aronica, Eleonora; Nicoletti, Ferdinando; Catania, Maria Vincenza

    2008-01-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS) and exerts its actions via a number of ionotropic glutamate receptors/channels and metabotropic glutamate (mGlu) receptors. In addition to being expressed in neurons, glutamate receptors are expressed in

  7. Group I Metabotropic Glutamate Receptors

    DEFF Research Database (Denmark)

    Erichsen, Julie Ladeby; Blaabjerg, Morten; Bogetofte Thomasen, Helle

    2015-01-01

    is, however, needed to realise their therapeutic potential. Glutamate and group I metabotropic glutamate receptors (mGluRs) affect proliferation and survival of rodent NSCs both during embryonic and postnatal development. To investigate the role of group I mGluRs (mGluR1 and mGluR5) on human NSCs, we...... differentiated an immortalized, forebrain-derived stem cell line in the presence or absence of glutamate and with addition of either the group I mGluR agonist DHPG or the selective antagonists; MPEP (mGluR5) and LY367385 (mGluR1). Characterization of differentiated cells revealed that both mGluR1 and mGluR5 were...... present on the cells. Addition of glutamate to the growth medium significantly increased cell proliferation and reduced cell death, resulting in increased cell numbers. In the presence of glutamate, selective activation of group I mGluRs reduced gliogenesis, whereas selective inhibition of group I m...

  8. Mechanism for the activation of glutamate receptors

    Science.gov (United States)

    Scientists at the NIH have used a technique called cryo-electron microscopy to determine a molecular mechanism for the activation and desensitization of ionotropic glutamate receptors, a prominent class of neurotransmitter receptors in the brain and spina

  9. 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.

  10. Desensitization of metabotropic glutamate receptors in neuronal cultures

    NARCIS (Netherlands)

    Catania, M. V.; Aronica, E.; Sortino, M. A.; Canonico, P. L.; Nicoletti, F.

    1991-01-01

    Preexposure of cultured cerebellar neurons to glutamate reduced the stimulation of polyphosphoinositide (PPI) hydrolysis induced by subsequent addition of glutamate without affecting the response to the muscarinic receptor agonist carbamylcholine. Desensitization of glutamate-stimulated PPI

  11. Glutamate Receptors in Neuroinflammatory Demyelinating Disease

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Multiple sclerosis (MS is a chronic demyelinating disease of the human central nervous system (CNS. The condition predominantly affects young adults and is characterised by immunological and inflammatory changes in the periphery and CNS that contribute to neurovascular disruption, haemopoietic cell invasion of target tissues, and demyelination of nerve fibres which culminate in neurological deficits that relapse and remit or are progressive. The main features of MS can be reproduced in the inducible animal counterpart, experimental autoimmune encephalomyelitis (EAE. The search for new MS treatments invariably employs EAE to determine drug activity and provide a rationale for exploring clinical efficacy. The preclinical development of compounds for MS has generally followed a conventional, immunotherapeutic route. However, over the past decade, a group of compounds that suppress EAE but have no apparent immunomodulatory activity have emerged. These drugs interact with the N-methyl-D-aspartate (NMDA and α -amino-3-hydroxy-5-isoxazolepropionic acid (AMPA/kainate family of glutamate receptors reported to control neurovascular permeability, inflammatory mediator synthesis, and resident glial cell functions including CNS myelination. The review considers the importance of the glutamate receptors in EAE and MS pathogenesis. The use of receptor antagonists to control EAE is also discussed together with the possibility of therapeutic application in demyelinating disease.

  12. 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.

  13. Glutamate Receptor Stimulation Up-Regulates Glutamate Uptake in Human Müller Glia Cells.

    Science.gov (United States)

    López-Colomé, Ana María; López, Edith; Mendez-Flores, Orquidia G; Ortega, Arturo

    2016-07-01

    Glutamate, the main excitatory amino acid in the vertebrate retina, is a well know activator of numerous signal transduction pathways, and has been critically involved in long-term synaptic changes acting through ionotropic and metabotropic glutamate receptors. However, recent findings underlining the importance of intensity and duration of glutamate stimuli for specific neuronal responses, including excitotoxicity, suggest a crucial role for Na(+)-dependent glutamate transporters, responsible for the removal of this neurotransmitter from the synaptic cleft, in the regulation of glutamate-induced signaling. Transporter proteins are expressed in neurons and glia cells, albeit most of glutamate uptake occurs in the glial compartment. Within the retina, Müller glia cells are in close proximity to glutamatergic synapses and participate in the recycling of glutamate through the glutamate/glutamine shuttle. In this context, we decided to investigate a plausible role of glutamate as a regulatory signal for its own transport in human retinal glia cells. To this end, we determined [(3)H]-D-aspartate uptake in cultures of spontaneously immortalized human Müller cells (MIO-M1) exposed to distinct glutamatergic ligands. A time and dose-dependent increase in the transporter activity was detected. This effect was dependent on the activation of the N-methyl D-aspartate subtype of glutamate receptors, due to a dual effect: an increase in affinity and an augmented expression of the transporter at the plasma membrane, as established via biotinylation experiments. Furthermore, a NMDA-dependent association of glutamate transporters with the cystoskeletal proteins ezrin and glial fibrillary acidic protein was also found. These results add a novel mediator of the glutamate transporter modulation and further strengthen the notion of the critical involvement of glia cells in synaptic function.

  14. Metabotropic glutamate receptor 5 neuroimaging in schizophrenia.

    Science.gov (United States)

    Akkus, Funda; Treyer, Valerie; Ametamey, Simon M; Johayem, Anass; Buck, Alfred; Hasler, Gregor

    2017-05-01

    The metabotropic glutamate receptor 5 (mGluR5) is a promising drug target for the treatment of schizophrenia. In this study, we compared mGluR5 distribution volume ration (DVR) in subjects with schizophrenia and healthy controls. Given our previous findings, we matched samples for gender, age, and smoking status. Binding to mGluR5 was determined using positron emission tomography and [ 11 C]ABP688, which binds to an allosteric site with high selectivity. DVR in the 15 individuals with schizophrenia did not differ from that of the 15 controls. In both groups, smoking was associated with marked global reductions in mGluR5 availability (on average 23.8%). In nonsmoking subjects with schizophrenia, there was a positive correlation between mGluR5 DVR in the medial orbitofrontal cortex and the use of antipsychotic drugs (r=0.9, p=0.019). Because antipsychotic drugs such as clozapine appeared to have indirect effects on mGluR5 signaling, our findings may be clinically relevant. They also provide promising leads for elucidating the high comorbidity between schizophrenia and tobacco addiction. Low mGluR5 DVR in smokers my represent a risk factor for schizophrenia. Alternatively, smoking may counteract the potential upregulation of mGluR5 by antipsychotic drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. 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)

  16. Glutamate receptors: variation in structure-function coupling

    DEFF Research Database (Denmark)

    Kristensen, Anders Skov; Geballe, Matthew; Snyder, James P

    2006-01-01

    Fast excitatory synaptic transmission in the CNS relies almost entirely on the neurotransmitter glutamate and its family of ion channel receptors. An appreciation of the coupling between agonist binding and channel opening has advanced rapidly during the past five years, largely as a result of ne...

  17. Modafinil attenuates reinstatement of cocaine seeking: role for cystine-glutamate exchange and metabotropic glutamate receptors.

    Science.gov (United States)

    Mahler, Stephen V; Hensley-Simon, Megan; Tahsili-Fahadan, Pouya; LaLumiere, Ryan T; Thomas, Charles; Fallon, Rebecca V; Kalivas, Peter W; Aston-Jones, Gary

    2014-01-01

    Modafinil may be useful for treating stimulant abuse, but the mechanisms by which it acts to do so are unknown. Indeed, a primary effect of modafinil is to inhibit dopamine transport, which typically promotes rather than inhibits motivated behavior. Therefore, we examined the role of nucleus accumbens extracellular glutamate and the group II metabotropic glutamate receptor (mGluR2/3) in modafinil effects. One group of rats was trained to self-administer cocaine for 10 days and extinguished, then given priming injections of cocaine to elicit reinstatement. Modafinil (300 mg/kg, intraperitoneal) inhibited reinstated cocaine seeking (but did not alter extinction responding by itself), and this effect was prevented by pre-treatment with bilateral microinjections of the mGluR2/3 antagonist LY-341495 (LY) into nucleus accumbens core. No reversal of modafinil effects was seen after unilateral accumbens core LY, or bilateral LY in the rostral pole of accumbens. Next, we sought to explore effects of modafinil on extracellular glutamate levels in accumbens after chronic cocaine. Separate rats were administered non-contingent cocaine, and after 3 weeks of withdrawal underwent accumbens microdialysis. Modafinil increased extracellular accumbens glutamate in chronic cocaine, but not chronic saline-pre-treated animals. This increase was prevented by reverse dialysis of cystine-glutamate exchange or voltage-dependent calcium channel antagonists. Voltage-dependent sodium channel blockade partly attenuated the increase in glutamate, but mGluR1 blockade did not. We conclude that modafinil increases extracellular glutamate in nucleus accumbens from glial and neuronal sources in cocaine-exposed rats, which may be important for its mGluR2/3-mediated antirelapse properties. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

  18. Metabotropic glutamate receptor 5 may be involved in macrophage plasticity

    Directory of Open Access Journals (Sweden)

    Lali Shanshiashvili

    Full Text Available Abstract Background Macrophages are a functionally heterogeneous cell population and depending on microenvironments they polarize in two main groups: M1 and M2. Glutamic acid and glutamate receptors may participate in the regulation of macrophage plasticity. To investigate the role of glutamatergic systems in macrophages physiology, we performed the transfection of mGluR5 cDNAs into RAW-264.7 cells. Results Comparative analysis of modified (RAW-mGluR5 macrophages and non-modified macrophages (RAW-macrophages has shown that the RAW-mGluR5 macrophages absorbed more glutamate than control cells and the amount of intracellular glutamate correlated with the expression of excitatory amino acid transporters -2 (EAAT-2. Besides, our results have shown that RAW-mGluR5 macrophages expressed a higher level of peroxisome proliferator-activated receptor γ (PPAR-γ and secreted more IL-10, high mobility group box 1 proteins (HMGB1 and Galectin-3 than control RAW-macrophages. Conclusions We propose that elevation of intracellular glutamate and expression of mGluR5 may initiate the metabolic rearrangement in macrophages that could contribute to the formation of an immunosuppressive phenotype.

  19. Glutamate receptors in glia: new cells, new inputs and new functions.

    Science.gov (United States)

    Gallo, V; Ghiani, C A

    2000-07-01

    Functional glutamate receptors are expressed on the majority of glial cell types in the developing and mature brain. Although glutamate receptors on glia are activated by glutamate released from neurons, their physiological role remains largely unknown. Potential roles for these receptors in glia include regulation of proliferation and differentiation, and modulation of synaptic efficacy. Recent anatomical and functional evidence indicates that glutamate receptors on immature glia are activated through direct synaptic inputs. Therefore, glutamate and its receptors appear to be involved in a continuous crosstalk between neurons and glia during development and also in the mature brain.

  20. Molecular cloning and chromosomal localization of one of the human glutamate receptor genes

    OpenAIRE

    Puckett, Carmie; Gomez, Christopher M.; Korenberg, Julie R.; Tung, Howard; Meier, Timothy J.; Chen, Xiao Ning; Hood, Leroy

    1991-01-01

    Glutamate receptors are the predominant excitatory neurotransmitter receptors in the mammalian brain and are classified on the basis of their activation by different agonists. The agonists kainate and alpha-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid define a class of glutamate receptors termed kainate receptors. We have isolated and sequenced a human glutamate receptor (GluHI) cDNA and determined the chromosomal localization of its gene. The DNA sequence of GluHI would encode a 907-am...

  1. Glutamate receptors and the airways hyperreactivity.

    Science.gov (United States)

    Strapkova, Anna; Antosova, Martina

    2012-03-01

    It is proposed the link between the hyperactivity of NMDA receptors and airway hyperresponsiveness. We investigated the effect of agents modulating the activity of NMDA receptors in the ovalbumin-induced airway hyperreactivity in guinea pigs. The airways hyperreactivity was influenced by the agonist (NMDA) and selective antagonist - competitive (AP-5) and non-competitive (MK-801) of NMDA receptors. Airway responsiveness to histamine or acetylcholine was evaluated in in vitro conditions. NMDA administration caused the increase of tracheal smooth muscle response in ovalbumin-induced hyperreactivity to acetylcholine. MK 801 as well as AP-5 provoked the decrease of reactivity mainly to acetylcholine in tracheal smooth muscle, while the former, non-competitive antagonist was more effective. We recorded more pronounced response in tracheal than in lung tissue smooth muscle with more considerable response to acetylcholine than to histamine. The results of experiments show the modification of airway smooth muscles responses by agents modulating the activity of NMDA receptors. They confirm the possibility of NMDA receptors participation in experimental airway hyperreactivity. The results enlarge information regarding the link of the inflammatory diseases and glutamatergic system.

  2. Coantagonism of Glutamate Receptors and Nicotinic Acetylcholinergic Receptors Disrupts Fear Conditioning and Latent Inhibition of Fear Conditioning

    Science.gov (United States)

    Gould, Thomas J.; Lewis, Michael C.

    2005-01-01

    The present study investigated the hypothesis that both nicotinic acetylcholinergic receptors (nAChRs) and glutamate receptors ([alpha]-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-D-aspartate glutamate receptors (NMDARs)) are involved in fear conditioning, and may modulate similar processes. The effects of the…

  3. Glutamate receptors in NG2-glial cells: gene profiling and functional changes after ischemic brain injury

    OpenAIRE

    Waloschková, Eliška

    2017-01-01

    Glutamate is the main excitatory neurotransmitter in the mammalian brain and its transmission is responsible for higher brain functions, such as learning, memory and cognition. Glutamate action is mediated by a variety of glutamate receptors, though their properties were until now studied predominantly in neurons. Glutamate receptors are expressed also in NG2-glia, however their role under physiological conditions as well as in pathological states of the central nervous system is not fully un...

  4. Specific labelling of brain receptors with [3H]N-acetyl-aspartyl-glutamate

    International Nuclear Information System (INIS)

    Koller, K.J.; Coyle, J.T.

    1984-01-01

    N-Acetyl-aspartyl glutamate (NAAG) is a peptide endogenous to brain that exhibits high affinity for a subpopulation of brain receptor sites labeled with ( 3 H)L-glutamate. The excitatory effects of NAAG are, unlike those of l-glutamate itself, antagonized by 2-amino-5-phosphono-butyric acid (APB). The authors' results indicate that [ 3 H]NAAG is a useful ligand for characterizing this subpopulation of glutamate receptors. (Auth.)

  5. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE, IN VIVO

    Science.gov (United States)

    In vitro, toluene disrupts the function of NMDA-glutamate receptors, indicating that effects on NMDA receptor function may contribute to toluene neurotoxicity. NMDA-glutamate receptors are widely present in the visual system and contribute to pattern-elicited visual evoked potent...

  6. New 4-Functionalized Glutamate Analogues Are Selective Agonists at Metabotropic Glutamate Receptor Subtype 2 or Selective Agonists at Metabotropic Glutamate Receptor Group III

    DEFF Research Database (Denmark)

    Huynh, Tri H. V.; Erichsen, Mette N.; Tora, Amelie S.

    2016-01-01

    The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6–8). In this article, we present a L-2...

  7. 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.

  8. Metabotropic glutamate receptor-mediated signaling in neuroglia

    Science.gov (United States)

    Loane, David J.; Stoica, Bogdan A.; Faden, Alan I.

    2011-01-01

    Metabotropic glutamate (mGlu) receptors are G-protein-coupled receptors, which include eight subtypes that have been classified into three groups (I–III) based upon sequence homology, signal transduction mechanism and pharmacological profile. Although most studied with regard to neuronal function and modulation, mGlu receptors are also expressed by neuroglia-including astrocytes, microglia and oligodendrocytes. Activation of mGlu receptors on neuroglia under both physiologic and pathophysiologic conditions mediates numerous actions that are essential for intrinsic glial cell function, as well as for glial–neuronal interactions. Astrocyte mGlu receptors play important physiological roles in regulating neurotransmission and maintaining neuronal homeostasis. However, mGlu receptors on astrocytes and microglia also serve to modulate cell death and neurological function in a variety of pathophysiological conditions such as acute and chronic neurodegenerative disorders. The latter effects are complex and bi-directional, depending on which mGlu receptor sub-types are activated. PMID:22662309

  9. Glutamate receptor antagonists with the potential for migraine treatment.

    Science.gov (United States)

    Ferrari, Anna; Rustichelli, Cecilia; Baraldi, Carlo

    2017-12-01

    Preclinical, clinical, and other (e.g., genetic) evidence support the concept that migraine susceptibility may at least partially result from a glutamatergic system disorder. Therefore, the receptors of the glutamatergic system are considered relatively new targets for investigational drugs to treat migraine. Investigational and established glutamate receptor antagonists (GluRAs) have been shown to possess antinociceptive properties in preclinical models of trigeminovascular nociception and have been evaluated in clinical trials. This review focuses on preclinical and clinical studies of GluRAs for the treatment of migraine. Areas covered: A PubMed database search (from 1987 to December 2016) and a review of published studies on GluRAs in migraine were conducted. Expert opinion: All published clinical trials of investigational GluRAs have been unsuccessful in establishing benefit for acute migraine treatment. Clinical trial results contrast with the preclinical data, suggesting that glutamate (Glu) does not play a decisive role after the attack has already been triggered. These antagonists may instead be useful for migraine prophylaxis. Improving patient care requires further investigating and critically analyzing the role of Glu in migraine, designing experimental models to study more receptors and their corresponding antagonists, and identifying biomarkers to facilitate trials designed to target specific subgroups of migraine patients.

  10. 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.

  11. 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.

  12. Neurosteroid modulation of ionotropic glutamate receptors and excitatory synaptic transmission

    Czech Academy of Sciences Publication Activity Database

    Sedláček, Miloslav; Kořínek, Miroslav; Petrovič, Miloš; Cais, Ondřej; Adamusová, Eva; Chodounská, Hana; Vyklický ml., Ladislav

    2008-01-01

    Roč. 57, Suppl.3 (2008), S49-S57 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) 1M0517; GA MŠk(CZ) LC554; GA ČR(CZ) GA309/07/0271; GA ČR GA203/08/1498 Grant - others:GA ČR(CZ) GD309/08/H079; EC(XE) LSHM-CT-2007-037765 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z40550506 Keywords : AMPA receptor * glutamate Subject RIV: ED - Physiology Impact factor: 1.653, year: 2008

  13. 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

    studies have shown that glutamate receptor antagonists affect the pathophysiology of migraine. This study investigated whether antagonists of NMDA (ketamine and MK801), AMPA (GYKI52466) and kainate (LY466195) glutamate receptors affected dural vasodilatation induced by alpha-CGRP, capsaicin...

  14. Coantagonism of glutamate receptors and nicotinic acetylcholinergic receptors disrupts fear conditioning and latent inhibition of fear conditioning

    OpenAIRE

    Gould, Thomas J.; Lewis, Michael C.

    2005-01-01

    The present study investigated the hypothesis that both nicotinic acetylcholinergic receptors (nAChRs) and glutamate receptors (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-d-aspartate glutamate receptors (NMDARs)) are involved in fear conditioning, and may modulate similar processes. The effects of the nAChR antagonist mecamylamine administered alone, the AMPAR antagonist NBQX administered alone, and the NMDAR antagonist MK-801 administered alone on cued ...

  15. 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

    2-Amino-3-[3-hydroxy-5-(2-thiazolyl)-4-isoxazolyl]propionic acid (1) is a potent AMPA receptor agonist with moderate affinity for native kainic acid (KA) receptors, whereas (S)-E-4-(2,2-dimethylpropylidene)glutamic acid (3) show high affinity for the GluR5 subtype of KA receptors and much lower...... 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...

  16. 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.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

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

  18. 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...

  19. Dual Effects of TARP γ-2 on Glutamate Efficacy Can Account for AMPA Receptor Autoinactivation

    Directory of Open Access Journals (Sweden)

    Ian D. Coombs

    2017-08-01

    Full Text Available Fast excitatory transmission in the CNS is mediated mainly by AMPA-type glutamate receptors (AMPARs associated with transmembrane AMPAR regulatory proteins (TARPs. At the high glutamate concentrations typically seen during synaptic transmission, TARPs slow receptor desensitization and enhance mean channel conductance. However, their influence on channels gated by low glutamate concentrations, as encountered during delayed transmitter clearance or synaptic spillover, is poorly understood. We report here that TARP γ-2 reduces the ability of low glutamate concentrations to cause AMPAR desensitization and enhances channel gating at low glutamate occupancy. Simulations show that, by shifting the balance between AMPAR activation and desensitization, TARPs can markedly facilitate the transduction of spillover-mediated synaptic signaling. Furthermore, the dual effects of TARPs can account for biphasic steady-state glutamate concentration-response curves—a phenomenon termed “autoinactivation,” previously thought to reflect desensitization-mediated AMPAR/TARP dissociation.

  20. Pharmacological or genetic orexin 1 receptor inhibition attenuates MK-801 induced glutamate release in mouse cortex

    Directory of Open Access Journals (Sweden)

    Leah eAluisio

    2014-05-01

    Full Text Available The orexin/hypocretin neuropeptides are produced by a cluster of neurons within the lateral posterior hypothalamus and participate in neuronal regulation by activating their receptors (OX1 and OX2 receptors. The orexin system projects widely through the brain and functions as an interface between multiple regulatory systems including wakefulness, energy balance, stress, reward and emotion. Recent studies have demonstrated that orexins and glutamate interact at the synaptic level and that orexins facilitate glutamate actions. We tested the hypothesis that orexins modulate glutamate signaling via OX1 receptors by monitoring levels of glutamate in frontal cortex of freely moving mice using enzyme coated biosensors under inhibited OX1 receptor conditions. MK-801, an NMDA receptor antagonist, was administered subcutaneously (0.178 mg/kg to indirectly disinhibit pyramidal neurons and therefore increase cortical glutamate release. In wild-type mice, pretreatment with the OX1 receptor antagonist GSK-1059865 (10 mg/kg S.C. which had no effect by itself, significantly attenuated the cortical glutamate release elicited by MK-801. OX1 receptor knockout mice had a blunted glutamate release response to MK-801 and exhibited about half of the glutamate release observed in wild-type mice in agreement with the data obtained with transient blockade of OX1 receptors. These results indicate that pharmacological (transient or genetic (permanent inhibition of the OX1 receptor similarly interfere with glutamatergic function in the cortex. Selectively targeting the OX1 receptor with an antagonist may normalize hyperglutamatergic states and thus may represent a novel therapeutic strategy for the treatment of various psychiatric disorders associated with hyperactive states.

  1. Complex formation and functional interaction between adenosine A1 receptor and type-1 metabotropic glutamate receptor

    Directory of Open Access Journals (Sweden)

    Yuji Kamikubo

    2015-07-01

    Full Text Available The adenosine A1 receptor (A1R is a G protein-coupled receptor (GPCR for adenosine, a ubiquitous neuromodulator, and thus regulates neuronal excitability, as well as arousal and sensitivity to pain. In addition, we have previously described a new mode of action for A1R: in cerebellar Purkinje cells, its activation attenuates neuronal responses to glutamate, as mediated by the type-1 metabotropic glutamate receptor (mGluR1. mGluR1 is also a GPCR, and elicits such responses as long-term depression of the postsynaptic response to glutamate, a cellular basis for cerebellar motor learning. Here, we explore in greater detail the interaction between A1R and mGluR1 using non-neuronal cells. Co-immunoprecipitation and Förster resonance energy transfer (FRET analysis reveal that A1R and mGluR1 form a complex. Furthermore, we found that mGluR1 activation inhibits A1R signaling, as measured by changes in intracellular cAMP. These findings demonstrate that A1R and mGluR1 have the intrinsic ability to form a heteromeric complex and mutually modulate signaling. This interaction may represent a new form of intriguing GPCR-mediated cellular responses.

  2. The N-terminal domain of GluR6-subtype glutamate receptor ion channels

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Janesh; Schuck, Peter; Jin, Rongsheng; Mayer, Mark L.; (NIH); (Burnham)

    2009-09-25

    The amino-terminal domain (ATD) of glutamate receptor ion channels, which controls their selective assembly into AMPA, kainate and NMDA receptor subtypes, is also the site of action of NMDA receptor allosteric modulators. Here we report the crystal structure of the ATD from the kainate receptor GluR6. The ATD forms dimers in solution at micromolar protein concentrations and crystallizes as a dimer. Unexpectedly, each subunit adopts an intermediate extent of domain closure compared to the apo and ligand-bound complexes of LIVBP and G protein-coupled glutamate receptors (mGluRs), and the dimer assembly has a markedly different conformation from that found in mGluRs. This conformation is stabilized by contacts between large hydrophobic patches in the R2 domain that are absent in NMDA receptors, suggesting that the ATDs of individual glutamate receptor ion channels have evolved into functionally distinct families.

  3. Regulation of dopamine D1 receptor dynamics within the postsynaptic density of hippocampal glutamate synapses.

    Directory of Open Access Journals (Sweden)

    Laurent Ladepeche

    Full Text Available Dopamine receptor potently modulates glutamate signalling, synaptic plasticity and neuronal network adaptations in various pathophysiological processes. Although key intracellular signalling cascades have been identified, the cellular mechanism by which dopamine and glutamate receptor-mediated signalling interplay at glutamate synapse remain poorly understood. Among the cellular mechanisms proposed to aggregate D1R in glutamate synapses, the direct interaction between D1R and the scaffold protein PSD95 or the direct interaction with the glutamate NMDA receptor (NMDAR have been proposed. To tackle this question we here used high-resolution single nanoparticle imaging since it provides a powerful way to investigate at the sub-micron resolution the dynamic interaction between these partners in live synapses. We demonstrate in hippocampal neuronal networks that dopamine D1 receptors (D1R laterally diffuse within glutamate synapses, in which their diffusion is reduced. Disrupting the interaction between D1R and PSD95, through genetical manipulation and competing peptide, did not affect D1R dynamics in glutamatergic synapses. However, preventing the physical interaction between D1R and the GluN1 subunit of NMDAR abolished the synaptic stabilization of diffusing D1R. Together, these data provide direct evidence that the interaction between D1R and NMDAR in synapses participate in the building of the dopamine-receptor-mediated signalling, and most likely to the glutamate-dopamine cross-talk.

  4. Crambescidin 816 induces calcium influx though glutamate receptors in primary cultures of cortical neurons

    Directory of Open Access Journals (Sweden)

    Víctor Martín Vázquez

    2014-06-01

    In summary, our data suggest that the cytotoxic effect of 10 μM Cramb816 in cortical neurons may be related to an increase in the cytosolic calcium concentration elicited by the toxin, which is shown to be mediated by glutamate receptor activation. Further studies analyzing the effect of glutamate receptor blockers on the cytotoxic effect of Cramb816 are needed to confirm this hypothesis.

  5. Reelin secreted by GABAergic neurons regulates glutamate receptor homeostasis.

    Directory of Open Access Journals (Sweden)

    Cecilia Gonzalez Campo

    Full Text Available BACKGROUND: Reelin is a large secreted protein of the extracellular matrix that has been proposed to participate to the etiology of schizophrenia. During development, reelin is crucial for the correct cytoarchitecture of laminated brain structures and is produced by a subset of neurons named Cajal-Retzius. After birth, most of these cells degenerate and reelin expression persists in postnatal and adult brain. The phenotype of neurons that bind secreted reelin and whether the continuous secretion of reelin is required for physiological functions at postnatal stages remain unknown. METHODOLOGY/PRINCIPAL FINDINGS: Combining immunocytochemical and pharmacological approaches, we first report that two distinct patterns of reelin expression are present in cultured hippocampal neurons. We show that in hippocampal cultures, reelin is secreted by GABAergic neurons displaying an intense reelin immunoreactivity (IR. We demonstrate that secreted reelin binds to receptors of the lipoprotein family on neurons with a punctate reelin IR. Secondly, using calcium imaging techniques, we examined the physiological consequences of reelin secretion blockade. Blocking protein secretion rapidly and reversibly changes the subunit composition of N-methyl-D-aspartate glutamate receptors (NMDARs to a predominance of NR2B-containing NMDARs. Addition of recombinant or endogenously secreted reelin rescues the effects of protein secretion blockade and reverts the fraction of NR2B-containing NMDARs to control levels. Therefore, the continuous secretion of reelin is necessary to control the subunit composition of NMDARs in hippocampal neurons. CONCLUSIONS/SIGNIFICANCE: Our data show that the heterogeneity of reelin immunoreactivity correlates with distinct functional populations: neurons synthesizing and secreting reelin and/or neurons binding reelin. Furthermore, we show that continuous reelin secretion is a strict requirement to maintain the composition of NMDARs. We propose

  6. 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.

  7. Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures

    DEFF Research Database (Denmark)

    Zimmer, J; Kristensen, Bjarne Winther; Jakobsen, B

    2000-01-01

    Using organotypic slice cultures of hippocampus and cortex-striatum from newborn to 7 day old rats, we are currently studying the excitotoxic effects of kainic acid (KA), AMPA and NMDA and the neuroprotective effects of glutamate receptor blockers, like NBQX. For detection and quantitation......-induced excitotoxicity and KA-glutamate receptor subunit mRNA expression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardized procedures for quantitation of cell damage and receptor subunit changes is of great potential use...... for studies of excitotoxic, glutamate receptor-induced neuronal cell death, receptor modulation and related neuroprotection....

  8. Allosteric activation of membrane-bound glutamate receptors using coordination chemistry within living cells

    Science.gov (United States)

    Kiyonaka, Shigeki; Kubota, Ryou; Michibata, Yukiko; Sakakura, Masayoshi; Takahashi, Hideo; Numata, Tomohiro; Inoue, Ryuji; Yuzaki, Michisuke; Hamachi, Itaru

    2016-10-01

    The controlled activation of proteins in living cells is an important goal in protein-design research, but to introduce an artificial activation switch into membrane proteins through rational design is a significant challenge because of the structural and functional complexity of such proteins. Here we report the allosteric activation of two types of membrane-bound neurotransmitter receptors, the ion-channel type and the G-protein-coupled glutamate receptors, using coordination chemistry in living cells. The high programmability of coordination chemistry enabled two His mutations, which act as an artificial allosteric site, to be semirationally incorporated in the vicinity of the ligand-binding pockets. Binding of Pd(2,2‧-bipyridine) at the allosteric site enabled the active conformations of the glutamate receptors to be stabilized. Using this approach, we were able to activate selectively a mutant glutamate receptor in live neurons, which initiated a subsequent signal-transduction pathway.

  9. Biomimicry-Based Strategy Towards the Development of a Structure-Function Map of the Glutamate Receptor Pore

    National Research Council Canada - National Science Library

    Montal, Mauricio

    2001-01-01

    .... The functional assay to identify channel blockers from synthetic combinatorial libraries involved blockade of the glutamate-evoked current from Xenopus oocytes expressing recombinant NMDA receptors...

  10. Receptor changes and LTP: an analysis using aniracetam, a drug that reversibly modifies glutamate (AMPA) receptors.

    Science.gov (United States)

    Staubli, U; Ambros-Ingerson, J; Lynch, G

    1992-01-01

    The hypothesis that long-term potentiation (LTP) involves receptor modifications was tested with aniracetam, a nootropic drug that selectively increases currents mediated by the AMPA subclass of glutamate receptors. Aniracetam had different effects on the waveform of synaptic potentials in hippocampus before and after induction of LTP: (1) the drug caused a slight reduction (or delay) of the initial segment of the response after LTP; and (2) the facilitatory effects of aniracetam occurred at a later time point in the response after LTP than before. The interactions between LTP and aniracetam were still present when synaptic responses were greatly reduced by partial blockade of postsynaptic receptors and were not reproduced by increasing release or the number of stimulated synapses. A mathematical treatment of synaptic currents produced the following results: (1) if aniracetam facilitates AMPA receptor currents simply by reducing desensitization, then its complex interaction with LTP emerges when potentiation changes the kinetic and conductance properties of receptor channels; (2) if aniracetam also significantly increases conductance, then the experimental data can be reproduced by modeling LTP as an increase in channel conductance alone.

  11. Aqueous and Ethanolic Valeriana officinalis Extracts Change the Binding of Ligands to Glutamate Receptors

    Science.gov (United States)

    Del Valle-Mojica, Lisa M.; Cordero-Hernández, José M.; González-Medina, Giselle; Ramos-Vélez, Igmeris; Berríos-Cartagena, Nairimer; Torres-Hernández, Bianca A.; Ortíz, José G.

    2011-01-01

    The effects of two valerian extracts (aqueous and hydroalcoholic) were investigated through [3H]Glutamate ([3H]Glu) and [3H]Fluorowillardine ([3H]FW) receptor binding assays using rat synaptic membranes in presence of different receptor ligands. In addition, the extract stability was monitored spectrophotometrically. Both extracts demonstrated interaction with ionotropic glutamate receptors (iGluRs). However, the extracts displayed considerable differences in receptor selectivity. The hydroalcoholic extract selectively interacted with quisqualic acid (QA), group I metabotropic glutamate receptor (mGluR) ligand, while the aqueous extract did not alter the binding of QA. The stability of the extracts was examined during several weeks. Freshly prepared extract inhibited 38–60% of [3H]FW binding (AMPA). After 10 days, the aqueous extract inhibited 85% of [3H]FW binding while the hydroalcoholic extract markedly potentiated (200%) [3H]FW binding to AMPA receptors. Thus, our results showed that factors such as extraction solvent and extract stability determine the selectivity for glutamate receptor (GluR) interactions. PMID:21151614

  12. Glutamate receptor properties of human mesencephalic neural progenitor cells: NMDA enhances dopaminergic neurogenesis in vitro.

    Science.gov (United States)

    Wegner, Florian; Kraft, Robert; Busse, Kathy; Schaarschmidt, Grit; Härtig, Wolfgang; Schwarz, Sigrid C; Schwarz, Johannes

    2009-10-01

    Human midbrain-derived neural progenitor cells (NPCs) may serve as a continuous source of dopaminergic neurons for the development of novel regenerative therapies in Parkinson's disease. However, the molecular and functional characteristics of glutamate receptors in human NPCs are largely unknown. Here, we show that differentiated human mesencepahlic NPCs display a distinct pattern of glutamate receptors. In whole-cell patch-clamp recordings, l-glutamate and NMDA elicited currents in 93% of NPCs after 3 weeks of differentiation in vitro. The concentration-response plots of differentiated NPCs yielded an EC(50) of 2.2 microM for glutamate and an EC(50) of 36 microM for NMDA. Glutamate-induced currents were markedly inhibited by memantine in contrast to 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) suggesting a higher density of functional NMDA than alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate receptors. NMDA-evoked currents and calcium signals were blocked by the NR2B-subunit specific antagonist ifenprodil indicating functional expression of NMDA receptors containing subunits NR1 and NR2B. In calcium imaging experiments, the blockade of voltage-gated calcium channels by verapamil abolished AMPA-induced calcium responses but only partially reduced NMDA-evoked transients suggesting the expression of calcium-impermeable, GluR2-containing AMPA receptors. Quantitative real-time PCR showed a predominant expression of subunits NR2A and NR2B (NMDA), GluR2 (AMPA), GluR7 (kainate), and mGluR3 (metabotropic glutamate receptor). Treatment of NPCs with 100 microM NMDA in vitro during proliferation (2 weeks) and differentiation (1 week) increased the amount of tyrosine hydroxylase-immunopositive cells significantly, which was reversed by addition of memantine. These data suggest that NMDA receptors in differentiating human mesencephalic NPCs are important regulators of dopaminergic neurogenesis in vitro.

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

    DEFF Research Database (Denmark)

    Johansen, Tommy N; Greenwood, Jeremy R; Frydenvang, Karla Andrea

    2003-01-01

    (S)-Glutamic acid (Glu), the major excitatory neurotransmitter in the central nervous system, operates through ionotropic as well as metabotropic receptors and is considered to be involved in certain neurological disorders and degenerative brain diseases that are currently without any satisfactory...... design of ligands, especially for the AMPA and kainate subtypes of ionotropic Glu receptors. This mini-review will focus on structure-activity relationships on AMPA and kainate receptor agonists with special emphasis on stereochemical and three-dimensional aspects....

  14. GLUTAMATE-DEHYDROGENASE IMPROVES BINDING OF [H-3] CGP39653 TO NMDA RECEPTORS IN THE AUTORADIOGRAPHIC ASSAY

    NARCIS (Netherlands)

    JAARSMA, D; SEBENS, JB; KORF, J

    The novel high-affinity competitive NMDA receptor antagonist, CGP39653, is employed as radioligand to autoradiographically label the NMDA receptor in rat and human brain. Glutamate dehydrogenase (GlDH; E.C.1.4.1.3) was added to the incubation buffer to degrade residual endogenous L-glutamate, which

  15. Plasticity of glutamate and GABAA receptors in the hippocampus of patients with Alzheimer's disease.

    Science.gov (United States)

    Armstrong, David M; Sheffield, Roxanne; Mishizen-Eberz, Amanda J; Carter, Troy L; Rissman, Robert A; Mizukami, Katsuyoshi; Ikonomovic, Milos D

    2003-10-01

    In Alzheimer's disease (AD) it is well known that specific regions of the brain are particularly vulnerable to the pathologic insults of the disease. In particular, the hippocampus is affected very early in the disease and by end stage AD is ravaged by neurofibrillary tangles and senile plaques (i.e., the pathologic hallmarks of AD). Throughout the past several years our laboratory has sought to determine the molecular mechanisms underlying the selective vulnerability of neurons in AD. To this end, we employed immunohistochemical, biochemical, and in situ hybrization methods to examine glutamate and gamma-aminobutyric acid (GABAA) receptor subtypes in the hippocampus of patients displaying the full spectrum of AD pathology. Despite the fact that the hippocampus is characterized by a marked loss of neurons in the late stages of the disease, our data demonstrate a rather remarkable preservation among some glutamate and GABAA receptor subtypes. Collectively, our data support the view that the relatively constant levels of selected receptor subtypes represent a compensatory up-regulation of these receptors subunits in surviving neurons. The demonstration that glutamate and GABA receptor subunits are comparably unaffected implies that even in the terminal stages of the discase the brain is "attempting" to maintain a balance in excitatory and inhibitory tone. Our data also support the concept that receptor subunits are differentially affected in AD with some subunits displaying no change while others display alterations in protein and mRNA levels within selected regions of the hippocampus. Although many of these changes are modest, they do suggest that the subunit composition of these receptors may be altered and hence affect the pharmacokinetic and physiological properties of the receptor. The latter findings stress the importance of understanding the subunit composition of individual glutamate/GABA receptors in the diseased brain prior to the development of drugs

  16. Modulation of gene expression of adenosine and metabotropic glutamate receptors in rat's neuronal cells exposed to L-glutamate and [60]fullerene.

    Science.gov (United States)

    Giust, Davide; Da Ros, Tatiana; Martín, Mairena; Albasanz, José Luis

    2014-08-01

    L-Glutamate (L-Glu) has been often associated not only to fundamental physiological roles, as learning and memory, but also to neuronal cell death and the genesis and development of important neurodegenerative diseases. Herein we studied the variation in the adenosine and metabotropic glutamate receptors expression induced by L-Glu treatment in rat's cortical neurons. The possibility to have structural alteration of the cells induced by L-Glu (100 nM, 1 and 10 microM) has been addressed, studying the modulation of microtubule associated protein-2 (MAP-2) and neurofilament heavy polypeptide (NEFH), natively associated proteins to the dendritic shape maintenance. Results showed that the proposed treatments were not destabilizing the cells, so the L-Glu concentrations were acceptable to investigate fluctuation in receptors expression, which were studied by RT-PCR. Interestingly, C60 fullerene derivative t3ss elicited a protective effect against glutamate toxicity, as demonstrated by MTT assay. In addition, t3ss compound exerted a different effect on the adenosine and metabotropic glutamate receptors analyzed. Interestingly, A(2A) and mGlu1 mRNAs were significantly decreased in conditions were t3ss neuroprotected cortical neurons from L-Glu toxicity. In summary, t3ss protects neurons from glutamate toxicity in a process that appears to be associated with the modulation of the gene expression of adenosine and metabotropic glutamate receptors.

  17. A new metabotropic glutamate receptor agonist with in vivo anti-allodynic activity

    DEFF Research Database (Denmark)

    Stanley, Nathan J; Hutchinson, Mark R; Kvist, Trine

    2010-01-01

    -substituted carboxycyclopropylglycines, utilizing novel synthetic chemistry. The reaction between substituted 1,2-dioxines and an aminophosphonate furnished the cyclopropane core in a single step with all required stereochemistry of pendant groups. In vitro binding assays at metabotropic glutamate receptors revealed selective activity...

  18. Selective Negative Allosteric Modulation Of Metabotropic Glutamate Receptors - A Structural Perspective of Ligands and Mutants

    DEFF Research Database (Denmark)

    Harpsøe, Kasper; Isberg, Vignir; Tehan, Benjamin G

    2015-01-01

    The metabotropic glutamate receptors have a wide range of modulatory functions in the central nervous system. They are among the most highly pursued drug targets, with relevance for several neurological diseases, and a number of allosteric modulators have entered clinical trials. However, so far ...

  19. Age-dependent anticonvulsant action of antagonists of group I glutamate metabotropic receptors in rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2009-01-01

    Roč. 83, 2-3 (2009), s. 215-223 ISSN 0920-1211 R&D Projects: GA ČR(CZ) GA305/06/1188 Institutional research plan: CEZ:AV0Z50110509 Keywords : metabotropic glutamate receptors * anticonvulsan effect * ontogeny Subject RIV: FH - Neuro logy Impact factor: 2.479, year: 2009

  20. Antagonists of group I metabotropic glutamate receptors and cortical afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Lojková-Janečková, Denisa; Ng, Jessica; Mareš, Pavel

    2009-01-01

    Roč. 50, č. 9 (2009), s. 2123-2129 ISSN 0013-9580 R&D Projects: GA ČR(CZ) GA305/06/1188 Institutional research plan: CEZ:AV0Z50110509 Keywords : cortical seizures * metabotropic glutamate receptors * development Subject RIV: FH - Neurology Impact factor: 4.052, year: 2009

  1. The glutamate receptor delta 2 in relation to cerebellar development and plasticity

    NARCIS (Netherlands)

    Gounko, Natalia V.; Gramsbergen, Albert; van der Want, Johannes J. L.

    2007-01-01

    Understanding what are the mechanisms that strengthen, stabilize and restrict synaptic innervation is a relevant topic in glutamate receptor delta 2 (GluR delta 2)-related research. It also involves targeting and selection of afferent input during formation of the neuronal circuitry in the

  2. New analogues of ACPD with selective activity for group II metabotropic glutamate receptors

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Madsen, U; Mikiciuk-Olasik, E

    1997-01-01

    In this study we have determined the pharmacology of a series of 1-aminocyclopentane-1,3-dicarboxylic acid (1,3-ACPD) analogues at cloned metabotropic glutamic acid (mGlu) receptors. The new analogues comprise the four possible stereoisomers of 1-amino-1-carboxycyclopentane-3-acetic acid (1,3-hom...

  3. Metabotropic glutamate receptors as a target for anticonvulsant and anxiolytic action in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Mikulecká, Anna; Tichá, Kateřina; Lojková-Janečková, Denisa; Kubová, Hana

    2010-01-01

    Roč. 51, Suppl.3 (2010), s. 24-26 ISSN 0013-9580 Institutional research plan: CEZ:AV0Z50110509 Keywords : metabotropic glutamate receptors * pharmacology * development Subject RIV: FH - Neurology Impact factor: 3.955, year: 2010

  4. Mechanisms underlying developmental changes in the expression of metabotropic glutamate receptors in cultured cerebellar granule cells: homologous desensitization and interactive effects involving N-methyl-D-aspartate receptors

    NARCIS (Netherlands)

    Aronica, E.; Dell'Albani, P.; Condorelli, D. F.; Nicoletti, F.; Hack, N.; Balázs, R.

    1993-01-01

    Glutamate receptors coupled to polyphosphoinositide (PPI) hydrolysis (metabotropic glutamate receptors, mGluR), are highly efficient during the early stages of postnatal life and are thought to be involved in developmental plasticity. The dramatic decrease with age in mGluR activity suggests the

  5. Sequential inter- and intrasubunit rearrangements during activation of dimeric metabotropic glutamate receptor 1

    Czech Academy of Sciences Publication Activity Database

    Hlaváčková, Veronika; Zabel, U.; Franková, Daniela; Batz, J.; Hoffmann, C.; Prezeau, L.; Pin, J. P.; Blahoš, Jaroslav; Lohse, M. J.

    2012-01-01

    Roč. 5, č. 237 (2012), ra59 ISSN 1937-9145 R&D Projects: GA ČR GA303/08/1591; GA MŠk(CZ) LC06063; GA ČR GAP303/12/2408 Institutional research plan: CEZ:AV0Z50520514 Keywords : G-protein coupled receptor * metabotropic glutamate receptor 1 * class C GPCR Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.648, year: 2012

  6. Oxytocin Reduces Cocaine Seeking and Reverses Chronic Cocaine-Induced Changes in Glutamate Receptor Function

    Science.gov (United States)

    Zhou, Luyi; Sun, Wei-Lun; Young, Amy B.; Lee, Kunhee; McGinty, Jacqueline F.

    2015-01-01

    Background: Oxytocin, a neurohypophyseal neuropeptide, is a potential mediator and regulator of drug addiction. However, the cellular mechanisms of oxytocin in drug seeking remain unknown. Methods: In the present study, we used a self-administration/reinstatement model to study the effects of oxytocin on cocaine seeking and its potential interaction with glutamate function at the receptor level. Results: Systemic oxytocin dose-dependently reduced cocaine self-administration during various schedules of reinforcement, including fixed ratio 1, fixed ratio 5, and progressive ratio. Oxytocin also attenuated reinstatement to cocaine seeking induced by cocaine prime or conditioned cues. Western-blot analysis indicated that oxytocin increased phosphorylation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptor GluA1 subunit at the Ser 845 site with or without accompanying increases in phosphorylation of extracellular signal-regulated kinase, in several brain regions, including the prefrontal cortex, bed nucleus of the stria terminalis, amygdala, and dorsal hippocampus. Immunoprecipitation of oxytocin receptor and GluA1 subunit receptors further demonstrated a physical interaction between these 2 receptors, although the interaction was not influenced by chronic cocaine or oxytocin treatment. Oxytocin also attenuated sucrose seeking in a GluA1- or extracellular-signal-regulated kinase-independent manner. Conclusions: These findings suggest that oxytocin mediates cocaine seeking through interacting with glutamate receptor systems via second messenger cascades in mesocorticolimbic regions. PMID:25539504

  7. [Studying specific effects of nootropic drugs on glutamate receptors in the rat brain].

    Science.gov (United States)

    Firstova, Iu Iu; Vasil'eva, E V; Kovalev, G I

    2011-01-01

    The influence of nootropic drugs of different groups (piracetam, phenotropil, nooglutil, noopept, semax, meclofenoxate, pantocalcine, and dimebon) on the binding of the corresponding ligands to AMPA, NMDA, and mGlu receptors of rat brain has been studied by the method of radio-ligand binding in vitro. It is established that nooglutil exhibits pharmacologically significant competition with a selective agonist of AMPA receptors ([G-3H]Ro 48-8587) for the receptor binding sites (with IC50 = 6.4 +/- 0.2 microM), while the competition of noopept for these receptor binding sites was lower by an order of magnitude (IC50 = 80 +/- 5.6 microM). The heptapeptide drug semax was moderately competitive with [G-3H]LY 354740 for mGlu receptor sites (IC50 = 33 +/- 2.4 microM). Dimebon moderately influenced the specific binding of the ligand of NMDA receptor channel ([G-3H]MK-801) at IC50 = 59 +/- 3.6 microM. Nootropic drugs of the pyrrolidone group (piracetam, phenotropil) as well as meclofenoxate, pantocalcine (pantogam) in a broad rage of concentrations (10(-4)-10(-10) M) did not affect the binding of the corresponding ligands to glutamate receptors (IC50 100 pM). Thus, the direct neurochemical investigation was used for the first time to qualitatively characterize the specific binding sites for nooglutil and (to a lower extent) noopept on AMPA receptors, for semax on metabotropic glutamate receptors, and for dimebon on the channel region of NMDA receptors. The results are indicative of a selective action of some nootropes on the glutamate family.

  8. The association of metabotropic glutamate receptor type 5 with the neuronal Ca2+-binding protein 2 modulates receptor function.

    Science.gov (United States)

    Canela, Laia; Fernández-Dueñas, Víctor; Albergaria, Catarina; Watanabe, Masahiko; Lluís, Carme; Mallol, Josefa; Canela, Enric I; Franco, Rafael; Luján, Rafael; Ciruela, Francisco

    2009-10-01

    Metabotropic glutamate (mGlu) receptors mediate in part the CNS effects of glutamate. These receptors interact with a large array of intracellular proteins in which the final role is to regulate receptor function. Here, using co-immunoprecipitation and pull-down experiments we showed a close and specific interaction between mGlu(5) receptor and NECAB2 in both transfected human embryonic kidney cells and rat hippocampus. Interestingly, in pull-down experiments increasing concentrations of calcium drastically reduced the ability of these two proteins to interact, suggesting that NECAB2 binds to mGlu(5) receptor in a calcium-regulated manner. Immunoelectron microscopy detection of NECAB2 and mGlu(5) receptor in the rat hippocampal formation indicated that both proteins are codistributed in the same subcellular compartment of pyramidal cells. In addition, the NECAB2/mGlu(5) receptor interaction regulated mGlu(5b)-mediated activation of both inositol phosphate accumulation and the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. Overall, these findings indicate that NECAB2 by its physical interaction with mGlu(5b) receptor modulates receptor function.

  9. Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures

    DEFF Research Database (Denmark)

    Zimmer, J; Kristensen, Bjarne Winther; Jakobsen, B

    2000-01-01

    Using organotypic slice cultures of hippocampus and cortex-striatum from newborn to 7 day old rats, we are currently studying the excitotoxic effects of kainic acid (KA), AMPA and NMDA and the neuroprotective effects of glutamate receptor blockers, like NBQX. For detection and quantitation...... of the induced neurodegeneration, we have developed standardized protocols, including--a) densitometric measurements of the cellular uptake of propidium iodide (PI), --b) histological staining by Flouro-Jade, --c) lactate dehydrogenase (LDH) release to the culture medium, --d) immunostaining for microtubulin......-induced excitotoxicity and KA-glutamate receptor subunit mRNA expression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardized procedures for quantitation of cell damage and receptor subunit changes is of great potential use...

  10. X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor

    Energy Technology Data Exchange (ETDEWEB)

    Sobolevsky, Alexander I.; Rosconi, Michael P.; Gouaux, Eric; (Vollum)

    2010-02-02

    Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system and function by opening a transmembrane ion channel upon binding of glutamate. Despite their crucial role in neurobiology, the architecture and atomic structure of an intact ionotropic glutamate receptor are unknown. Here we report the crystal structure of the {alpha}-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-sensitive, homotetrameric, rat GluA2 receptor at 3.6 {angstrom} resolution in complex with a competitive antagonist. The receptor harbours an overall axis of two-fold symmetry with the extracellular domains organized as pairs of local dimers and with the ion channel domain exhibiting four-fold symmetry. A symmetry mismatch between the extracellular and ion channel domains is mediated by two pairs of conformationally distinct subunits, A/C and B/D. Therefore, the stereochemical manner in which the A/C subunits are coupled to the ion channel gate is different from the B/D subunits. Guided by the GluA2 structure and site-directed cysteine mutagenesis, we suggest that GluN1 and GluN2A NMDA (N-methyl-D-aspartate) receptors have a similar architecture, with subunits arranged in a 1-2-1-2 pattern. We exploit the GluA2 structure to develop mechanisms of ion channel activation, desensitization and inhibition by non-competitive antagonists and pore blockers.

  11. 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)

  12. Agonist- and subunit-dependent potentiation of glutamate receptors by a nootropic drug aniracetam.

    Science.gov (United States)

    Tsuzuki, K; Takeuchi, T; Ozawa, S

    1992-11-01

    GluR1 and GluR2 cDNAs encoding non-NMDA subtypes of glutamate receptor were isolated from a rat brain cDNA library by Boulter et al. (Science, 249 (1990) 1033-1037). Functional receptors activated by kainate, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and glutamate were expressed in Xenopus oocytes injected with GluR1, GluR2 or a mixture of GluR1 and GluR2 RNAs. In GluR1-expressed oocytes, 1 mM aniracetam potentiated AMPA-induced currents by 99 +/- 10% (mean +/- S.E.M., n = 5) and glutamate-induced currents by 140 +/- 8% (n = 4), but little affected kainate-induced currents. Aniracetam was effective from a concentration of 0.1 mM, and it exhibited more conspicuous effects with the increase of the dose. In oocytes injected with GluR1 plus GluR2 RNAs, aniracetam more markedly potentiated current responses to AMPA and glutamate than those in oocytes injected with GluR1 RNA alone. For example, 1 mM aniracetam potentiated AMPA-induced currents by 396 +/- 76% (n = 4) and glutamate-induced currents by 970 +/- 65% (n = 5) in oocytes injected with 10% GluR1 and 90% GluR2 RNAs. In these oocytes, however, the potentiation of kainate-induced currents by 1 mM aniracetam was only 8 +/- 5% (n = 4). Thus, we conclude that the potentiation of the AMPA/kainate receptor by aniracetam depends on both species of agonists and subunit composition of the receptor.

  13. Metabotropic glutamate receptors as a strategic target for the treatment of epilepsy.

    Science.gov (United States)

    Alexander, Georgia M; Godwin, Dwayne W

    2006-09-01

    Epilepsy is a chronic neurological disorder that has many known types, including generalized epilepsies that involve cortical and subcortical structures. A proportion of patients have seizures that are resistant to traditional anti-epilepsy drugs, which mainly target ion channels or postsynaptic receptors. This resistance to conventional therapies makes it important to identify novel targets for the treatment of epilepsy. Given the involvement of the neurotransmitter glutamate in the etiology of epilepsy, targets that control glutamatergic neurotransmission are of special interest. The metabotropic glutamate receptors (mGluRs) are of a family of eight G-protein-coupled receptors that serve unique regulatory functions at synapses that use the neurotransmitter glutamate. Their distribution within the central nervous system provides a platform for both presynaptic control of glutamate release, as well as postsynaptic control of neuronal responses to glutamate. In recent years, substantial efforts have been made towards developing selective agonists and antagonists which may be useful for targeting specific receptor subtypes in an attempt to harness the therapeutic potential of these receptors. We examine the possibility of intervening at these receptors by considering the specific example of absence seizures, a form of generalized, non-convulsive seizure that involves the thalamus. Views of the etiology of absence seizures have evolved over time from the "centrencephalic" concept of a diffuse subcortical pacemaker toward the "cortical focus" theory in which cortical hyperexcitability leads the thalamus into the 3-4 Hz rhythms that are characteristic of absence seizures. Since the cortex communicates with the thalamus via a massive glutamatergic projection, ionotropic glutamate receptor (iGluR) blockade has held promise, but the global nature of iGluR intervention has precluded the clinical effectiveness of drugs that block iGluRs. In contrast, mGluRs, because they

  14. The Challenge of Interpreting Glutamate-Receptor Ion-Channel Structures.

    Science.gov (United States)

    Mayer, Mark L

    2017-11-21

    Ion channels activated by glutamate mediate excitatory synaptic transmission in the central nervous system. Similar to other ligand-gated ion channels, their gating cycle begins with transitions from a ligand-free closed state to glutamate-bound active and desensitized states. In an attempt to reveal the molecular mechanisms underlying gating, numerous structures for glutamate receptors have been solved in complexes with agonists, antagonists, allosteric modulators, and auxiliary proteins. The embarrassingly rich library of structures emerging from this work reveals very dynamic molecules with a more complex conformational spectrum than anticipated from functional studies. Unanticipated conformations solved for complexes with competitive antagonists and a lack of understanding of the structural basis for ion channel subconductance states further highlight challenges that have yet to be addressed. Published by Elsevier Inc.

  15. Soluble ectodomain of neuroligin 1 decreases synaptic activity by activating metabotropic glutamate receptor 2

    DEFF Research Database (Denmark)

    Gjørlund, Michelle D.; Carlsen, Eva Maria Meier; Kønig, Andreas Bay

    2017-01-01

    -dependent manner, releasing a soluble extracellular fragment and membrane-tethered C-terminal fragment. The cleavage of NL1 depresses synaptic transmission, but the mechanism by which this occurs is unknown. Metabotropic glutamate receptor 2 (mGluR2) are located primarily at the periphery of presynaptic terminals......, where they inhibit the formation of cyclic adenosine monophosphate (cAMP) and consequently suppress the release of glutamate and decrease synaptic transmission. In the present study, we found that the soluble ectodomain of NL1 binds to and activates mGluR2 in both neurons and heterologous cells......, resulting in a decrease in cAMP formation. In a slice preparation from the hippocampus of mice, NL1 inhibited the release of glutamate from mossy fibers that project to CA3 pyramidal neurons. The presynaptic effect of NL1 was abolished in the presence of a selective antagonist for mGluR2. Thus, our data...

  16. NMDA-Type Glutamate Receptor Activation Promotes Vascular Remodeling and Pulmonary Arterial Hypertension.

    Science.gov (United States)

    Dumas, Sébastien J; Bru-Mercier, Gilles; Courboulin, Audrey; Quatredeniers, Marceau; Rücker-Martin, Catherine; Antigny, Fabrice; Nakhleh, Morad K; Ranchoux, Benoit; Gouadon, Elodie; Vinhas, Maria-Candida; Vocelle, Matthieu; Raymond, Nicolas; Dorfmüller, Peter; Fadel, Elie; Perros, Frédéric; Humbert, Marc; Cohen-Kaminsky, Sylvia

    2018-02-14

    Background -Excessive proliferation and apoptosis resistance in pulmonary vascular cells underlie vascular remodeling in pulmonary arterial hypertension (PAH). Specific treatments for PAH exist, mostly targeting endothelial dysfunction, but high pulmonary arterial pressure still causes heart failure and death. Pulmonary vascular remodeling may be driven by metabolic reprogramming of vascular cells to increase glutaminolysis and glutamate production. The N-methyl-D-aspartate receptor (NMDAR), a major neuronal glutamate receptor, is also expressed on vascular cells, but its role in PAH is unknown. Methods -We assessed the status of the glutamate-NMDAR axis in the pulmonary arteries of PAH patients and controls, through mass spectrometry imaging, western blotting and immunohistochemistry. We measured the glutamate release from cultured pulmonary vascular cells using enzymatic assays, and analyzed NMDAR regulation/phosphorylation through western blot experiments. The effect of NMDAR blockade on human pulmonary arterial smooth muscle cell (hPASMC) proliferation was determined using a BrdU incorporation assay. We assessed the role of NMDARs in vascular remodeling associated to pulmonary hypertension (PH), both in smooth muscle-specific NMDAR knockout mice exposed to chronic hypoxia and in the monocrotaline rat model of PH using NMDAR blockers. Results -We report glutamate accumulation, upregulation of the NMDAR, and NMDAR engagement reflected by increases in GluN1-subunit phosphorylation, in the pulmonary arteries of human PAH patients. K v channel inhibition and ETAR activation amplified calcium-dependent glutamate release from hPASMCs, and ETAR and PDGFR activation led to NMDAR engagement, highlighting crosstalk between the glutamate-NMDAR axis and major PAH-associated pathways. The PDGF-BB-induced proliferation of hPASMCs involved NMDAR activation and phosphorylated GluN1 subunit localization to cell-cell contacts, consistent with glutamatergic communication between

  17. 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...

  18. Biostructural and pharmacological studies of bicyclic analogues of the 3-isoxazolol glutamate receptor agonist ibotenic acid

    DEFF Research Database (Denmark)

    Frydenvang, Karla Andrea; Pickering, Darryl S; Greenwood, Jeremy R

    2010-01-01

    We describe an improved synthesis and detailed pharmacological characterization of the conformationally restricted analogue of the naturally occurring nonselective glutamate receptor agonist ibotenic acid (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-7-carboxylic acid (7-HPCA, 5......) at AMPA receptor subtypes. Compound 5 was shown to be a subtype-discriminating agonist at AMPA receptors with higher binding affinity and functional potency at GluA1/2 compared to GluA3/4, unlike the isomeric analogue (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-5-carboxylic acid (5-HPCA, 4...

  19. 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

  20. Blockade and enhancement of glutamate receptor responses in Xenopus oocytes by methylated arsenicals

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Katharina; Gruner, Janina; Madeja, Michael; Musshoff, Ulrich [Universitaetsklinikum Muenster, Institut fuer Physiologie I, Muenster (Germany); Hartmann, Louise M.; Hirner, Alfred V. [Universitaet Duisburg-Essen, Institut fuer Umweltanalytik, Essen (Germany); Binding, Norbert [Universitaetsklinikum Muenster, Institut fuer Arbeitsmedizin, Muenster (Germany)

    2006-08-15

    Pentavalent and trivalent organoarsenic compounds belong to the major metabolites of inorganic arsenicals detected in humans. Recently, the question was raised whether the organic arsenicals represent metabolites of a detoxification process or methylated species with deleterious biological effects. In this study, the effects of trivalent arsenite (AsO{sub 3} {sup 3-}; iA{sup III}), the pentavalent organoarsenic compounds monomethylarsonic acid (CH{sub 3}AsO(OH){sub 2}; MMA{sup V}) and dimethylarsinic acid ((CH{sub 3}){sub 2}AsO(OH); DMA{sup V}) and the trivalent compounds monomethylarsonous acid (CH{sub 3}As(OH){sub 2}, MMA{sup III}) and dimethylarsinous acid ((CH{sub 3}){sub 2}As(OH); DMA{sup III}) were tested on glutamate receptors and on voltage-operated potassium and sodium channels heterologously expressed in Xenopus oocytes. Membrane currents of ion channels were measured by conventional two-electrode voltage-clamp techniques. The effects of arsenite were tested in concentrations of 1-1,000 {mu}mol/l and the organic arsenical compounds were tested in concentrations of 0.1-100 {mu}mol/l. We found no significant effects on voltage-operated ion channels; however, the arsenicals exert different effects on glutamate receptors. While MMA{sup V} and MMA{sup III} significantly enhanced ion currents through N-methyl-d-aspartate (NMDA) receptor ion channels with threshold concentrations <10 {mu}mol/l, DMA{sup V} and DMA{sup III} significantly reduced NMDA-receptor mediated responses with threshold concentrations <0.1 {mu}mol/l; iA{sup III} had no effects on glutamate receptors of the NMDA type. MMA{sup III} and DMA{sup V} significantly reduced ion currents through {alpha}-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-receptor ion channels with threshold concentrations <10 {mu}mol/l (MMA{sup III}) and <1 {mu}mol/l (DMA{sup V}). MMA{sup V} and iA{sup III} had no significant effects on glutamate receptors of the AMPA type. The effects of MMA{sup V}, MMA

  1. GABA and glutamate receptors have different effects on excitability and are differentially regulated by calcium in spider mechanosensory neurons.

    Science.gov (United States)

    Torkkeli, Päivi H; Meisner, Shannon; Pfeiffer, Keram; French, Andrew S

    2012-12-01

    GABA and glutamate receptors belonging to the ligand-gated chloride-channel family are primary targets of insecticides and antiparasitics, so their molecular structure, pharmacology and biophysical properties have attracted significant attention. However, little is known about the physiological roles of these channels or how they regulate neuronal excitability and animal behavior. Mechanosensory neurons of VS-3 slit sensilla in the patella of the tropical wandering spider, Cupiennius salei, react to the GABA(A)-receptor agonists, GABA and muscimol, with depolarization and an increase in intracellular [Ca(2+)] and, during random noise stimulation, with a mixed inhibitory-excitatory response. We established that the GABA(A)-receptors in all VS-3 neurons are identical, but there are at least two types of glutamate receptors and some neurons do not respond to glutamate at all. Immunohistochemistry with antibodies against Drosophila inhibitory glutamate receptor (GluCls) α-subunit suggests that in addition to VS-3 neurons, these receptors may also be present in the efferent neurons surrounding the sensory neurons. Most VS-3 neurons were inhibited but not depolarized by glutamate during random stimulation, but some depolarized and had a similar excitatory-inhibitory response to glutamate as to muscimol. The membrane-permeable Ca(2+)-chelator BAPTA-AM abolished muscimol effects but potentiated glutamate effects, indicating that GABA and glutamate receptors are differentially modulated by Ca(2+), leading to diverse regulation of neuronal excitability. We hypothesize that this could be achieved by different Ca(2+)-triggered phosphorylation processes at each receptor type. These findings are important for understanding the significance of Ca(2+)-mediated regulation of transmitter receptor molecules and its role in controlling excitability. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  2. Involvement of multiple taste receptors in umami taste: analysis of gustatory nerve responses in metabotropic glutamate receptor 4 knockout mice.

    Science.gov (United States)

    Yasumatsu, Keiko; Manabe, Tomohiro; Yoshida, Ryusuke; Iwatsuki, Ken; Uneyama, Hisayuki; Takahashi, Ichiro; Ninomiya, Yuzo

    2015-02-15

    The taste receptor T1R1 + T1R3 heterodimer and metabotropic glutamate receptors (mGluR) may function as umami taste receptors. Here, we used mGluR4 knockout (mGluR4-KO) mice and examined the function of mGluR4 in peripheral taste responses of mice. The mGluR4-KO mice showed reduced responses to glutamate and L-AP4 (mGluR4 agonist) in the chorda tympani and glossopharyngeal nerves without affecting responses to other taste stimuli. Residual glutamate responses in mGluR4-KO mice were suppressed by gurmarin (T1R3 blocker) and AIDA (group I mGluR antagonist). The present study not only provided functional evidence for the involvement of mGluR4 in umami taste responses, but also suggested contributions of T1R1 + T1R3 and mGluR1 receptors in glutamate responses. Umami taste is elicited by L-glutamate and some other amino acids and is thought to be initiated by G-protein-coupled receptors. Proposed umami receptors include heterodimers of taste receptor type 1, members 1 and 3 (T1R1 + T1R3), and metabotropic glutamate receptors 1 and 4 (mGluR1 and mGluR4). Accumulated evidences support the involvement of T1R1 + T1R3 in umami responses in mice. However, little is known about the in vivo function of mGluR in umami taste. Here, we examined taste responses of the chorda tympani (CT) and the glossopharyngeal (GL) nerves in wild-type mice and mice genetically lacking mGluR4 (mGluR4-KO). Our results indicated that compared to wild-type mice, mGluR4-KO mice showed significantly smaller gustatory nerve responses to glutamate and L-(+)-2-amino-4-phosphonobutyrate (an agonist for group III mGluR) in both the CT and GL nerves without affecting responses to other taste stimuli. Residual glutamate responses in mGluR4-KO mice were not affected by (RS)-alpha-cyclopropyl-4-phosphonophenylglycine (an antagonist for group III mGluR), but were suppressed by gurmarin (a T1R3 blocker) in the CT and (RS)-1-aminoindan-1,5-dicarboxylic acid (an antagonist for group I mGluR) in the CT and GL nerve

  3. Fine tuning of sub-millisecond conformational dynamics controls metabotropic glutamate receptors agonist efficacy.

    Science.gov (United States)

    Olofsson, Linnea; Felekyan, Suren; Doumazane, Etienne; Scholler, Pauline; Fabre, Ludovic; Zwier, Jurriaan M; Rondard, Philippe; Seidel, Claus A M; Pin, Jean-Philippe; Margeat, Emmanuel

    2014-10-17

    Efficient cell-to-cell communication relies on the accurate signalling of cell surface receptors. Understanding the molecular bases of their activation requires the characterization of the dynamic equilibrium between active and resting states. Here, we monitor, using single-molecule Förster resonance energy transfer, the kinetics of the reorientation of the extracellular ligand-binding domain of the metabotropic glutamate receptor (mGluR), a class C G-protein-coupled receptor. We demonstrate that most receptors oscillate between a resting- and an active-conformation on a sub-millisecond timescale. Interestingly, we demonstrate that differences in agonist efficacies stem from differing abilities to shift the conformational equilibrium towards the fully active state, rather than from the stabilization of alternative static conformations, which further highlights the dynamic nature of mGluRs and revises our understanding of receptor activation and allosteric modulation.

  4. Picosecond dynamics of the glutamate receptor in response to agonist-induced vibrational excitation.

    Science.gov (United States)

    Kubo, Minoru; Shiomitsu, Eiji; Odai, Kei; Sugimoto, Tohru; Suzuki, Hideo; Ito, Etsuro

    2004-02-01

    Conformational changes of proteins are dominated by the excitation and relaxation processes of their vibrational states. To elucidate the mechanism of receptor activation, the conformation dynamics of receptors must be analyzed in response to agonist-induced vibrational excitation. In this study, we chose the bending vibrational mode of the guanidinium group of Arg485 of the glutamate receptor subunit GluR2 based on our previous studies, and we investigated picosecond dynamics of the glutamate receptor caused by the vibrational excitation of Arg485 via molecular dynamics simulations. The vibrational excitation energy in Arg485 in the ligand-binding site initially flowed into Lys730, and then into the J-helix at the subunit interface of the ligand-binding domain. Consequently, the atomic displacement in the subunit interface around an intersubunit hydrogen bond was evoked in about 3 ps. This atomic displacement may perturb the subunit packing of the receptor, triggering receptor activation. Copyright 2003 Wiley-Liss, Inc.

  5. Cloning and Characterization of Glutamate Receptors in Californian Sea Lions (Zalophus californianus)

    OpenAIRE

    Gill; Goldstein; Situ; Zabka; Gulland; Mueller

    2010-01-01

    Domoic acid produced by marine algae has been shown to cause acute and chronic neurologic sequelae in Californian sea lions following acute or low-dose exposure. Histological findings in affected animals included a degenerative cardiomyopathy that was hypothesized to be caused by over-excitation of the glutamate receptors (GluRs) speculated to be present in the sea lion heart. Thus tissues from five sea lions without lesions associated with domoic acid toxicity and one animal with domoic acid...

  6. Main subunits of ionotropic glutamate receptors are expressed in isolated rat brain microvessels

    Czech Academy of Sciences Publication Activity Database

    Šťastný, František; Schwendt, M.; Lisý, Václav; Ježová, D.

    2002-01-01

    Roč. 24, č. 1 (2002), s. 93-96 ISSN 0161-6412 R&D Projects: GA ČR GA305/99/1317; GA ČR GA309/99/0211 Grant - others:VEGA(SK) 2/6084 Institutional research plan: CEZ:AV0Z5011922 Keywords : Glutamate receptor * gene expression and binding * blood-brain barrier Subject RIV: FH - Neurology Impact factor: 0.969, year: 2002

  7. Age-dependent suppression of hippocampal epileptic afterdischarges by metabotropic glutamate receptor 5 antagonist MTEP

    Czech Academy of Sciences Publication Activity Database

    Zavala-Tecuapetla, Cecília; Kubová, Hana; Otáhal, Jakub; Tsenov, Grygoriy; Mareš, Pavel

    2014-01-01

    Roč. 66, č. 5 (2014), s. 927-930 ISSN 1734-1140 R&D Projects: GA ČR(CZ) GA305/09/0846; GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : epileptic afterdischarge * hippocampus * rat * ontogeny * metabotropic glutamate receptor 5 Subject RIV: FH - Neurology Impact factor: 1.928, year: 2014

  8. Glutamate receptors in the nucleus tractus solitarius contribute to ventilatory acclimatization to hypoxia in rat.

    Science.gov (United States)

    Pamenter, Matthew E; Carr, J Austin; Go, Ariel; Fu, Zhenxing; Reid, Stephen G; Powell, Frank L

    2014-04-15

    When exposed to a hypoxic environment the body's first response is a reflex increase in ventilation, termed the hypoxic ventilatory response (HVR). With chronic sustained hypoxia (CSH), such as during acclimatization to high altitude, an additional time-dependent increase in ventilation occurs, which increases the HVR. This secondary increase persists after exposure to CSH and involves plasticity within the circuits in the central nervous system that control breathing. Currently these mechanisms of HVR plasticity are unknown and we hypothesized that they involve glutamatergic synapses in the nucleus tractus solitarius (NTS), where afferent endings from arterial chemoreceptors terminate. To test this, we treated rats held in normoxia (CON) or 10% O2 (CSH) for 7 days and measured ventilation in conscious, unrestrained animals before and after microinjecting glutamate receptor agonists and antagonists into the NTS. In normoxia, AMPA increased ventilation 25% and 50% in CON and CSH, respectively, while NMDA doubled ventilation in both groups (P e. acute hypoxia in CON and CSH, and normoxia in CSH. These results support our hypothesis that glutamate receptors in the NTS contribute to plasticity in the HVR with CSH. The mechanism underlying this synaptic plasticity is probably glutamate receptor modification, as in CSH rats the expression of phosphorylated NR1 and GluR1 proteins in the NTS increased 35% and 70%, respectively, relative to that in CON rats.

  9. ACh receptors link two signaling pathways to neuroprotection against glutamate-induced excitotoxicity in isolated RGCs.

    Science.gov (United States)

    Asomugha, Chinwe O; Linn, David M; Linn, Cindy L

    2010-01-01

    Previous studies have reported that activation of nicotinic acetylcholine (ACh) receptors (nAChRs) on cultured pig retinal ganglion cells (RGCs) has a neuroprotective effect against glutamate-induced excitotoxicity. However, the mechanism linking nAChRs to neuroprotection is unknown. Here, we tested the hypothesis that signaling cascades involving p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) --> Akt are involved in linking activation of nAChRs to neuroprotection in isolated pig RGCs. In ELISA studies, regulation of phosphorylated p38 MAPK and Akt were analyzed after inducing excitotoxicity or neuroprotection in the presence and absence of specific inhibitors for p38 MAPK and PI3K. ELISA results demonstrated that ACh significantly increased phosphorylated Akt and decreased p38 MAPK. Glutamate increased phosphorylated p38 MAPK but had no significant effect on phosphorylated Akt. Other ELISA studies using p38 MAPK and PI3K inhibitors also supported the hypothesis that ACh up-regulated Bcl-2 levels downstream from PI3K and Akt, whereas glutamate down-regulated Bcl-2 levels downstream from p38 MAPK. RGC survival was subsequently assessed by culturing RGCs in conditions to induce excitotoxicity or neuroprotection in the presence or absence of specific inhibitors of p38 MAPK or PI3K. The p38 MAPK inhibitor significantly decreased the number of RGCs that died by glutamate-induced excitotoxicity but had no effect on the number of cells that survived because of ACh-induced neuroprotection. PI3K inhibitors significantly decreased cell survival caused by ACh-induced neuroprotection but had no effect on cell death caused by glutamate-induced excitotoxicity. These results demonstrate that glutamate mediates excitotoxicity through the p38 MAPK signaling pathway and that ACh provides neuroprotection by stimulating the PI3K --> Akt --> Bcl-2 signaling pathway and inhibiting the p38 MAPK --> Bcl-2 pathway.

  10. Synaptic NR2A- but not NR2B-containing NMDA receptors increase with blockade of ionotropic glutamate receptors

    Directory of Open Access Journals (Sweden)

    Jakob Von Engelhardt

    2009-10-01

    Full Text Available NMDA receptors are key molecules involved in physiological and pathophysiological brain processes such as plasticity and excitotoxicity. Neuronal activity regulates NMDA receptor levels in the cell membrane. However, little is known on which time scale this regulation occurs and whether the two main diheteromeric NMDA receptor subtypes in forebrain, NR1/NR2A and NR1/NR2B, are regulated in a similar fashion. As these differ considerably in their electrophysiological properties, the NR2A/NR2B ratio affects the neurons’ reaction to NMDA receptor activation. Here we provide evidence that the basal turnover rate in the cell membrane of NR2A- and NR2B-containing receptors is comparable. However, the level of the NR2A subtype in the cell membrane is highly regulated by NMDA receptor activity, resulting in a several-fold increased insertion of new receptors after blocking NMDA receptors for 8 hours. Blocking AMPA receptors also increases the delivery of NR2A-containing receptors to the cell membrane. In contrast, the amount of NR2B-containing receptors in the cell membrane is not affected by ionotropic glutamate receptor block. Moreover, electrophysiological analysis of synaptic currents in hippocampal cultures and CA1 neurons of hippocampal slices revealed that after 8 hours of NMDA receptor blockade the NMDA EPSCs increase as a result of augmented NMDA receptor-mediated currents. In conclusion, synaptic NR2A- but not NR2B-containing receptors are dynamically regulated, enabling neurons to change their NR2A/NR2B ratio within a time scale of hours.

  11. Α-amino-β-fluorocyclopropanecarboxylic acids as a new tool for drug development: synthesis of glutamic acid analogs and agonist activity towards metabotropic glutamate receptor 4.

    Science.gov (United States)

    Lemonnier, Gérald; Lion, Cédric; Quirion, Jean-Charles; Pin, Jean-Philippe; Goudet, Cyril; Jubault, Philippe

    2012-08-01

    Herein we describe the diastereoselective synthesis of glutamic acid analogs and the evaluation of their agonist activity towards metabotropic glutamate receptor subtype 4 (mGluR4). These analogs are based on a monofluorinated cyclopropane core substituted with an α-aminoacid function. The potential of this new building block as a tool for the development of a novel class of drugs is demonstrated with racemic analog 11a that displayed the best agonist activity with an EC50 of 340 nM. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Recent Advances in the Medicinal Chemistry of the Metabotropic Glutamate Receptor 1 (mGlu1)

    Science.gov (United States)

    2011-01-01

    This Review summarizes the medicinal chemistry found in publications on both orthosteric and allosteric modulators of the metabotropic glutamate receptor 1 (mGlu1) from 2005 to the present. The time period covered by the scope of this current review has been particularly rich in mGlu1-related publications with numbers quadrupling when compared to the preceding five year period of 2000−2005. Publications in the field peaked in 2007 with over 35 articles appearing in the peer reviewed literature in the course of that year. Given that glutamate is one of the primary excitatory neurotransmitters in the mammalian central nervous system (CNS), it is unsurprising that it acts upon several receptors that are considered to be of potential therapeutic interest for many indications. Orthosteric and allosteric modulation of the receptor is possible, with a logical extrapolation to the chemotypes used for each strategy. The last five years of publications have yielded many mGlu1 selective antagonist chemotypyes, most of which have shown efficacy in pain in vivo models. However, the primary impact of these compounds has been to highlight the mechanistic safety risks of mGlu1 antagonism, independent of chemotype. As a review in medicinal chemistry, the primary focus of this paper will be on the design and, to a lesser degree, synthetic strategies for the delivery of subtype selective, CNS penetrant, druglike compounds through a “medchem” program, targeting modulators of the mGlu1 receptor. PMID:22860168

  13. The 5-HT2A receptor antagonist M100907 produces antiparkinsonian effects and decreases striatal glutamate

    Directory of Open Access Journals (Sweden)

    Twum eAnsah

    2011-06-01

    Full Text Available 5-HT plays a regulatory role in voluntary movements of the basal ganglia and have a major impact on disorders of the basal ganglia such as Parkinson’s disease (PD. Clinical studies have suggested that 5-HT2 receptor antagonists may be useful in the treatment of the motor symptoms of PD. We hypothesized that 5-HT2A receptor antagonists may restore motor function by regulating glutamatergic activity in the striatum. Mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP exhibited decreased performance on the beam-walking apparatus. Peripheral administration of the 5-HT2A receptor antagonist M100907 improved performance of MPTP-treated mice on the beam-walking apparatus. In vivo microdialysis revealed an increase in striatal extracellular glutamate in MPTP-treated mice and local perfusion of M100907 into the dorsal striatum significantly decreased extracellular glutamate levels in saline and MPTP-treated mice. Our studies suggest that blockade of 5-HT2A receptors may represent a novel therapeutic target for the motor symptoms of Parkinson’s disease.

  14. Molecular mechanism of ligand recognition by NR3 subtype glutamate receptors

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yongneng; Harrison, Chris B.; Freddolino, Peter L.; Schulten, Klaus; Mayer, Mark L. (UIUC); (NIH)

    2008-10-27

    NR3 subtype glutamate receptors have a unique developmental expression profile, but are the least well-characterized members of the NMDA receptor gene family, which have key roles in synaptic plasticity and brain development. Using ligand binding assays, crystallographic analysis, and all atom MD simulations, we investigate mechanisms underlying the binding by NR3A and NR3B of glycine and D-serine, which are candidate neurotransmitters for NMDA receptors containing NR3 subunits. The ligand binding domains of both NR3 subunits adopt a similar extent of domain closure as found in the corresponding NR1 complexes, but have a unique loop 1 structure distinct from that in all other glutamate receptor ion channels. Within their ligand binding pockets, NR3A and NR3B have strikingly different hydrogen bonding networks and solvent structures from those found in NR1, and fail to undergo a conformational rearrangement observed in NR1 upon binding the partial agonist ACPC. MD simulations revealed numerous interdomain contacts, which stabilize the agonist-bound closed-cleft conformation, and a novel twisting motion for the loop 1 helix that is unique in NR3 subunits.

  15. Recent advances in the medicinal chemistry of the metabotropic glutamate receptor 1 (mGlu₁).

    Science.gov (United States)

    Owen, Dafydd R

    2011-08-17

    This Review summarizes the medicinal chemistry found in publications on both orthosteric and allosteric modulators of the metabotropic glutamate receptor 1 (mGlu(1)) from 2005 to the present. The time period covered by the scope of this current review has been particularly rich in mGlu(1)-related publications with numbers quadrupling when compared to the preceding five year period of 2000-2005. Publications in the field peaked in 2007 with over 35 articles appearing in the peer reviewed literature in the course of that year. Given that glutamate is one of the primary excitatory neurotransmitters in the mammalian central nervous system (CNS), it is unsurprising that it acts upon several receptors that are considered to be of potential therapeutic interest for many indications. Orthosteric and allosteric modulation of the receptor is possible, with a logical extrapolation to the chemotypes used for each strategy. The last five years of publications have yielded many mGlu(1) selective antagonist chemotypyes, most of which have shown efficacy in pain in vivo models. However, the primary impact of these compounds has been to highlight the mechanistic safety risks of mGlu(1) antagonism, independent of chemotype. As a review in medicinal chemistry, the primary focus of this paper will be on the design and, to a lesser degree, synthetic strategies for the delivery of subtype selective, CNS penetrant, druglike compounds through a "medchem" program, targeting modulators of the mGlu(1) receptor.

  16. The Effect of Glutamate Receptor Agonists on Mouse Retinal Astrocyte [Ca2+]i

    Directory of Open Access Journals (Sweden)

    Stephanie N. Blandford

    2016-01-01

    Full Text Available Calcium-imaging techniques were used to determine if mouse retinal astrocytes in situ respond to agonists of ionotropic (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA; N-methyl-D-aspartate, NMDA and metabotropic (S-3,5-dihydroxyphenylglycine, DHPG; trans-1-amino-1,3-cyclopentanedicarboxylic acid, ACPD glutamate receptors. In most cases we found no evidence that retinal astrocyte intracellular calcium ion concentration (Ca2+i increased in response to these glutamate agonists. The one exception was AMPA that increased Ca2+i in some, but not all, mouse retinal astrocytes in situ. However, AMPA did not increase Ca2+i in mouse retinal astrocytes in vitro, suggesting that the effect of AMPA in situ may be indirect.

  17. The Effect of Glutamate Receptor Agonists on Mouse Retinal Astrocyte [Ca(2+)]i.

    Science.gov (United States)

    Blandford, Stephanie N; Baldridge, William H

    2016-01-01

    Calcium-imaging techniques were used to determine if mouse retinal astrocytes in situ respond to agonists of ionotropic (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA; N-methyl-D-aspartate, NMDA) and metabotropic (S-3,5-dihydroxyphenylglycine, DHPG; trans-1-amino-1,3-cyclopentanedicarboxylic acid, ACPD) glutamate receptors. In most cases we found no evidence that retinal astrocyte intracellular calcium ion concentration ([Ca(2+)]i) increased in response to these glutamate agonists. The one exception was AMPA that increased [Ca(2+)]i in some, but not all, mouse retinal astrocytes in situ. However, AMPA did not increase [Ca(2+)]i in mouse retinal astrocytes in vitro, suggesting that the effect of AMPA in situ may be indirect.

  18. Metabotropic and ionotropic glutamate receptors mediate the modulation of acetylcholine release at the frog neuromuscular junction.

    Science.gov (United States)

    Tsentsevitsky, Andrei; Nurullin, Leniz; Nikolsky, Evgeny; Malomouzh, Artem

    2017-07-01

    There is some evidence that glutamate (Glu) acts as a signaling molecule at vertebrate neuromuscular junctions where acetylcholine (ACh) serves as a neurotransmitter. In this study, performed on the cutaneous pectoris muscle of the frog Rana ridibunda, Glu receptor mechanisms that modulate ACh release processes were analyzed. Electrophysiological experiments showed that Glu reduces both spontaneous and evoked quantal secretion of ACh and synchronizes its release in response to electrical stimulation. Quisqualate, an agonist of ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptors and metabotropic Group I mGlu receptors, also exerted Glu-like inhibitory effects on the secretion of ACh but had no effect on the kinetics of quantal release. Quisqualate's inhibitory effect did not occur when a blocker of Group I mGlu receptors (LY 367385) or an inhibitor of phospholipase C (U73122) was present. An increase in the degree of synchrony of ACh quantal release, such as that produced by Glu, was obtained after application of N-methyl-D-aspartic acid (NMDA). The presence of Group I mGlu and NMDA receptors in the neuromuscular synapse was confirmed by immunocytochemistry. Thus, the data suggest that both metabotropic Group I mGlu receptors and ionotropic NMDA receptors are present at the neuromuscular synapse of amphibians, and that the activation of these receptors initiates different mechanisms for the regulation of ACh release from motor nerve terminals. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Expression of group III metabotropic glutamate receptors in the reproductive system of male mice.

    Science.gov (United States)

    Marciniak, Marcin; Chruścicka, Barbara; Lech, Tomasz; Burnat, Grzegorz; Pilc, Andrzej

    2016-03-01

    Although the presence of metabotropic glutamate (mGlu) receptors in the central nervous system is well documented, they have recently been found in peripheral and non-neuronal tissues. In the present study we investigated the expression of group III mGlu receptors in the reproductive system of male mice. Reverse transcription-polymerase chain reaction analysis revealed the presence of mGlu6, mGlu7 and mGlu8 (but not mGlu4) receptor transcripts in testes and epididymides from adult mice. In addition, expression of mGlu6 (Grm6) and mGlu8 receptor (Grm8) mRNA was detected in spermatozoa isolated from the vas deferens. The vas deferens was found to contain only mGlu7 receptor (Grm7) mRNA, which was particularly intense in 21-day-old male mice. In penile homogenates, only the mGlu7 receptor signal was detected. Genetic ablation of the mGlu7 receptor in males led to fertility disorders manifested by decreased insemination capability as well as deterioration of sperm parameters, particularly sperm motility, vitality, sperm membrane integrity and morphology, with a simultaneous increase in sperm concentration. These results indicate that constitutively expressed mGlu receptors in the male reproductive system may play an important role in ejaculation and/or erection processes, as well as in the formation and maturation of spermatozoa.

  20. In vivo microdialysis and immunohistochemical analyses of tendon tissue demonstrated high amounts of free glutamate and glutamate NMDAR1 receptors, but no signs of inflammation, in Jumper's knee.

    Science.gov (United States)

    Alfredson, H; Forsgren, S; Thorsen, K; Lorentzon, R

    2001-09-01

    This investigation describes, to our knowledge, the first experiment where the microdialysis technique was used to study certain metabolic events in human patellar tendons in combination with immunohistochemical analyses of tendon biopsies. In five patients (four men and one woman) with a long duration (range 12-36 months) of pain symptoms from Jumper's knee (localized tenderness in the patellar tendon verified as tendon changes with ultrasonography or MRI), and in five controls (four men and one woman) with normal patellar tendons, a standard microdialysis catheter was inserted into the patellar tendon under local anestesia. The local concentrations of glutamate (excitatory neurotransmitter) and prostaglandin E2 (PGE2) were registered under resting conditions. Samplings were done every 15 min during a 2 h period. In all individuals (patients and controls) biopsies were taken for immunohistochemical analyses. The results showed that it was possible to detect and measure the concentrations of glutamate and PGE2 in the patellar tendon with the use of microdialysis technique. There were significantly higher concentrations of free glutamate, but not PGE2, in tendons with tendinosis compared to normal tendons. In the biopsies, there were no inflammatory cell infiltrates, but, for the first time, it was shown that there was immunoreaction for the glutamate receptor NMDAR1 in association with nerve structures in human patellar tendons. These findings altogether indicate that glutamate might be involved in painful Jumper's knee, and further emphasizes that there is no chemical inflammation (normal PGE2 levels) in this chronic condition.

  1. Quantitative Analysis of Glutamate Receptors in Glial Cells from the Cortex of GFAP/EGFP Mice Following Ischemic Injury: Focus on NMDA Receptors.

    Science.gov (United States)

    Dzamba, David; Honsa, Pavel; Valny, Martin; Kriska, Jan; Valihrach, Lukas; Novosadova, Vendula; Kubista, Mikael; Anderova, Miroslava

    2015-11-01

    Cortical glial cells contain both ionotropic and metabotropic glutamate receptors. Despite several efforts, a comprehensive analysis of the entire family of glutamate receptors and their subunits present in glial cells is still missing. Here, we provide an overall picture of the gene expression of ionotropic (AMPA, kainate, NMDA) and the main metabotropic glutamate receptors in cortical glial cells isolated from GFAP/EGFP mice before and after focal cerebral ischemia. Employing single-cell RT-qPCR, we detected the expression of genes encoding subunits of glutamate receptors in GFAP/EGFP-positive (GFAP/EGFP(+)) glial cells in the cortex of young adult mice. Most of the analyzed cells expressed mRNA for glutamate receptor subunits, the expression of which, in most cases, even increased after ischemic injury. Data analyses disclosed several classes of GFAP/EGFP(+) glial cells with respect to glutamate receptors and revealed in what manner their expression correlates with the expression of glial markers prior to and after ischemia. Furthermore, we also examined the protein expression and functional significance of NMDA receptors in glial cells. Immunohistochemical analyses of all seven NMDA receptor subunits provided direct evidence that the GluN3A subunit is present in GFAP/EGFP(+) glial cells and that its expression is increased after ischemia. In situ and in vitro Ca(2+) imaging revealed that Ca(2+) elevations evoked by the application of NMDA were diminished in GFAP/EGFP(+) glial cells following ischemia. Our results provide a comprehensive description of glutamate receptors in cortical GFAP/EGFP(+) glial cells and may serve as a basis for further research on glial cell physiology and pathophysiology.

  2. Group I mGlu receptors potentiate synaptosomal [3H]glutamate release independently of exogenously applied arachidonic acid

    International Nuclear Information System (INIS)

    Reid, M.E.; Toms, N.J.; Bedingfield, J.S.; Roberts, P.J.

    1999-01-01

    In the current study, we have characterized group I metabotropic glutamate (mGlu) receptor enhancement of 4-aminopyridine (4AP)-evoked [ 3 H]glutamate release from rat cerebrocortical synaptosomes. The broad spectrum mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD, 10 μM) increased 4AP-evoked [ 3 H]glutamate release (143.32±2.73% control) only in the presence of exogenously applied arachidonic acid; an effect reversed by the inclusion of bovine serum albumin (BSA, fatty acid free). In contrast, the selective group I mGlu receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated (EC 50 =1.60±0.25 μM; E max =147.61±10.96% control) 4AP-evoked [ 3 H]glutamate release, in the absence of arachidonic acid. This potentiation could be abolished by either the selective mGlu 1 receptor antagonist (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA, 1 mM) or the selective PKC inhibitor (Ro 31-8220, 10 μM) and was BSA-insensitive. The selective mGlu 5 receptor agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG, 300μM) was without effect. DHPG (100 μM) also potentiated both 30 mM and 50 mM K + -evoked [ 3 H]glutamate release (121.60±12.77% and 121.50±4.45% control, respectively). DHPG (100 μM) failed to influence both 4AP-stimulated 45 Ca 2+ influx and 50 mM K + -induced changes in synaptosomal membrane potential. Possible group I mGlu receptor suppression of tonic adenosine A 1 receptor, group II/III mGlu receptors or GABA B receptor activity is unlikely since 4AP-evoked [ 3 H]glutamate release was insensitive to the selective inhibitory receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine, (R,S)-α-cyclopropyl-4-phosphonophenylglycine or CGP55845A, respectively. These data suggest an 'mGlu 1 receptor-like' receptor potentiates [ 3 H]glutamate release from cerebrocortical synaptosomes in the absence of exogenously applied arachidonic acid. This PKC dependent effect is unlikely to be via modulation of synaptosomal membrane

  3. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE USING PATTERN ELICITED VISUAL EVOKED POTENTIALS.

    Science.gov (United States)

    In vitro studies have demonstrated that toluene disrupts the function of NMDA-glutamate receptors, as well as other channels. This has led to the hypothesis that effects on NMDA receptor function may contribute to toluene neurotoxicity, CNS depression, and altered visual evoked ...

  4. Modulation of desensitization at glutamate receptors in isolated crucian carp horizontal cells by concanavalin A, cyclothiazide, aniracetam and PEPA.

    Science.gov (United States)

    Shen, Y; Lu, T; Yang, X L

    1999-03-01

    In horizontal cells freshly dissociated from crucian carp (Carassius auratus) retina, we examined the effects of modulators of glutamate receptor desensitization, concanavalin A, cyclothiazide, aniracetam and 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetam ide (PEPA), on responses to rapid application of glutamate and kainate, using whole-cell voltage-clamp techniques. Incubation of concanavalin A suppressed the peak response but weakly potentiated the equilibrium response of horizontal cells to glutamate. Cyclothiazide blocked glutamate-induced desensitization in a dose-dependent manner, which resulted in a steady increase of the equilibrium current. The concentration of cyclothiazide causing a half-maximal potentiation for the equilibrium response was 85 microM. Furthermore, cyclothiazide shifted the dose-response relationship of the equilibrium current to the right, but slightly suppressed the kainate-induced sustained current. These effects of concanavalin A and cyclothiazide are consistent with the supposition that glutamate receptors of carp horizontal cells may be an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-preferring subtype. In order to further characterize the AMPA receptors of horizontal cells, modulation by aniracetam and PEPA of glutamate- and kainate-induced currents was studied. Aniracetam, a preferential modulator of flop variants of AMPA receptors, considerably blocked desensitization of glutamate-induced currents, but only slightly potentiated kainate-induced currents. It was further found that PEPA, a flop-preferring allosteric modulator of AMPA receptor desensitization, slightly suppressed the peak current, while it dramatically potentiated the equilibrium current induced by glutamate in a dose-dependent manner. PEPA was much potent than aniracetam at these receptors and showed the effect on glutamate-induced desensitization even at a concentration as low as 3 microM. PEPA also potentiated non

  5. 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.

  6. A Genome Wide Association Study Links Glutamate Receptor Pathway to Sporadic Creutzfeldt-Jakob Disease Risk

    Science.gov (United States)

    Sanchez-Juan, Pascual; Bishop, Matthew T.; Kovacs, Gabor G.; Calero, Miguel; Aulchenko, Yurii S.; Ladogana, Anna; Boyd, Alison; Lewis, Victoria; Ponto, Claudia; Calero, Olga; Poleggi, Anna; Carracedo, Ángel; van der Lee, Sven J.; Ströbel, Thomas; Rivadeneira, Fernando; Hofman, Albert; Haïk, Stéphane; Combarros, Onofre; Berciano, José; Uitterlinden, Andre G.; Collins, Steven J.; Budka, Herbert; Brandel, Jean-Philippe; Laplanche, Jean Louis; Pocchiari, Maurizio; Zerr, Inga; Knight, Richard S. G.; Will, Robert G.; van Duijn, Cornelia M.

    2015-01-01

    We performed a genome-wide association (GWA) study in 434 sporadic Creutzfeldt-Jakob disease (sCJD) patients and 1939 controls from the United Kingdom, Germany and The Netherlands. The findings were replicated in an independent sample of 1109 sCJD and 2264 controls provided by a multinational consortium. From the initial GWA analysis we selected 23 SNPs for further genotyping in 1109 sCJD cases from seven different countries. Five SNPs were significantly associated with sCJD after correction for multiple testing. Subsequently these five SNPs were genotyped in 2264 controls. The pooled analysis, including 1543 sCJD cases and 4203 controls, yielded two genome wide significant results: rs6107516 (p-value=7.62x10-9) a variant tagging the prion protein gene (PRNP); and rs6951643 (p-value=1.66x10-8) tagging the Glutamate Receptor Metabotropic 8 gene (GRM8). Next we analysed the data stratifying by country of origin combining samples from the pooled analysis with genotypes from the 1000 Genomes Project and imputed genotypes from the Rotterdam Study (Total n=12967). The meta-analysis of the results showed that rs6107516 (p-value=3.00x10-8) and rs6951643 (p-value=3.91x10-5) remained as the two most significantly associated SNPs. Rs6951643 is located in an intronic region of GRM8, a gene that was additionally tagged by a cluster of 12 SNPs within our top100 ranked results. GRM8 encodes for mGluR8, a protein which belongs to the metabotropic glutamate receptor family, recently shown to be involved in the transduction of cellular signals triggered by the prion protein. Pathway enrichment analyses performed with both Ingenuity Pathway Analysis and ALIGATOR postulates glutamate receptor signalling as one of the main pathways associated with sCJD. In summary, we have detected GRM8 as a novel, non-PRNP, genome-wide significant marker associated with heightened disease risk, providing additional evidence supporting a role of glutamate receptors in sCJD pathogenesis. PMID:25918841

  7. Molecular pharmacology of homologues of ibotenic acid at cloned metabotropic glutamic acid receptors

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Nielsen, B; Krogsgaard-Larsen, P

    1998-01-01

    We have studied the effects of the enantiomers of 2-amino-3-(3-hydroxyisoxazol-5-yl)propionic acid (homoibotenic acid, HIBO) and analogues substituted with a methyl, bromo or butyl group in the four position of the ring at cloned metabotropic glutamate (mGlu) receptors expressed in Chinese hamster...... ovary (CHO) cells. In contrast to the parent compound ibotenic acid, which is a potent group I and II agonist, the (S)-forms of homoibotenic acid and its analogues are selective and potent group I antagonists whereas the (R)-forms are inactive both as agonists and antagonists at group I, II, and III m...

  8. Metabotropic glutamate 5 receptor antagonism is associated with antidepressant-like effects in mice.

    Science.gov (United States)

    Li, Xia; Need, Anne B; Baez, Melvyn; Witkin, Jeffrey M

    2006-10-01

    Antidepressant-like effects of metabotropic glutamate (mGlu)5 receptor antagonists have been reported previously. We now provide definitive identification of mGlu5 receptors as a target for these effects through the combined use of selective antagonists and mice with targeted deletion of the mGlu5 protein. In these experiments, the mGlu5 receptor antagonists 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and the more selective and metabolically stable analog 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP) decreased immobility in the mouse forced swim test, a test predictive of antidepressant efficacy in humans. mGlu5 receptor knockout mice had a phenotype in the forced swim test that was congruent with the effects of receptor blockade; mGlu5 receptor knockout mice were significantly less immobile than their wild-type counterparts. Consistent with mGlu5 receptor mediation of the antidepressant-like effects of MPEP, the effects of MPEP were not observed in mGlu5 receptor knockout mice, whereas comparable effects of the tricyclic antidepressant imiprimine remained active in the mutant mice. MPEP and imiprimine resulted in a synergistic antidepressant-like effect in the forced swim test. The drug interaction was not likely because of increased levels of drugs in the brain, suggesting a pharmacodynamic interaction of mGlu5 and monoaminergic systems in this effect. Thus, the present findings substantiate the hypothesis that mGlu5 receptor antagonism is associated with antidepressant-like effects. This mechanism may not only provide a novel approach to the therapeutic management of depressive disorders but also may be useful in the augmentation of effects of traditional antidepressant agents.

  9. Anticonvulsant activity of artificial sweeteners: a structural link between sweet-taste receptor T1R3 and brain glutamate receptors.

    Science.gov (United States)

    Talevi, Alan; Enrique, Andrea V; Bruno-Blanch, Luis E

    2012-06-15

    A virtual screening campaign based on application of a topological discriminant function capable of identifying novel anticonvulsant agents indicated several widely-used artificial sweeteners as potential anticonvulsant candidates. Acesulfame potassium, cyclamate and saccharin were tested in the Maximal Electroshock Seizure model (mice, ip), showing moderate anticonvulsant activity. We hypothesized a probable structural link between the receptor responsible of sweet taste and anticonvulsant molecular targets. Bioinformatic tools confirmed a highly significant sequence-similarity between taste-related protein T1R3 and several metabotropic glutamate receptors from different species, including glutamate receptors upregulated in epileptogenesis and certain types of epilepsy. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. The metabotropic glutamate receptor agonist 1S,3R-ACPD stimulates and modulates NMDA receptor mediated excitotoxicity in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Blaabjerg, M; Kristensen, Bjarne Winther; Bonde, C

    2001-01-01

    The potential toxic effects of the metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) and its interactions with the N-methyl-D-aspartate (NMDA) receptor were studied in hippocampal brain slice cultures, using densitometric measurements of the cellular...

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Posttraumatic secondary brain insults exacerbates neuronal injury by altering Metabotropic Glutamate Receptors

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    Li Xia

    2007-11-01

    Full Text Available Abstract Background Our previous studies indicated that metabotropic glutamate receptors (mGluRs are deeply involved in the secondary processes after diffuse brain injury (DBI. In the present study, we used a rodent DBI model to determine whether hypotension exacerbates neuronal injury as a secondary brain insult (SBI after traumatic brain injury (TBI by changing the expression of metabotropic glutamate receptors (mGluRs in the cerebral cortex. Results Three hundred and eleven male Sprague-Dawley rats were randomly assigned into five groups: normal control, sham-operated control, SBI alone, DBI alone, or DBI with SBI. DBI was produced in rats by Marmarou's methods and the SBI model was produced by hypotension. The alteration of neuronal expression of mGluRs after DBI and DBI coupled with SBI was observed by hybridization in situ at different time points in the experiment. We found a higher mortality and neurological severity score (NSS for rats in the DBI with SBI group compared with those in the DBI alone group. Although there was a significant rise in the expression of group I and group III mGluRs (except mGluR6 and a decrease in the expression of group II mGluRs after DBI (P Conclusion The results suggest posttraumatic SBI may exacerbate neuronal injury or brain injury by altering expression of mGluRs, and more emphasis should therefore be put on the prevention and treatment of SBI.

  13. Anxiolytic properties of Valeriana officinalis in the zebrafish: a possible role for metabotropic glutamate receptors.

    Science.gov (United States)

    Del Valle-Mojica, Lisa M; Ortíz, José G

    2012-11-01

    Valerian extract is used in complementary and alternative medicine for its anxiolytic and sedative properties. Our previous research demonstrated valerian interactions with glutamate receptors. The purpose of this study was to determine if valerian anxiolytic properties are mediated by metabotropic glutamate receptors (mGluR) such as mGluR (1/5) (mGluR I) and mGluR (2/3) (mGluR II). Adult wild-type zebrafish (Danio rerio) prefer the black compartment and avoid the white compartment in the dark/light preference task. Zebrafish exposed to 1 mg/mL of valerian extract or 0.00117 mg/mL valerenic acid increased their residence time in the white side by 84.61 ± 6.55 % and 58.30 ± 8.97 %, respectively. LAP3 (mGluR I antagonist) and EGLU (mGluR II antagonist) significantly inhibited the effects of valerian and valerenic acid. These results demonstrated that valerian and valerenic acid have anxiolytic properties in the zebrafish. Moreover, the selective interaction of valerian with mGluR I and II represent an alternative explanation for the anxiolytic properties of this plant and support the role of mGluR in anxiety. Georg Thieme Verlag KG Stuttgart · New York.

  14. Novel expression patterns of metabotropic glutamate receptor 6 in the zebrafish nervous system.

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    Ying-Yu Huang

    Full Text Available The metabotropic glutamate receptor 6 (mGluR6 or GRM6 belongs to the class III of the metabotropic glutamate receptor family. It is the only known mGluR that mediates direct synaptic transmission in the nervous system and is thought to mediate the ON-response in the ON-pathway of the vertebrate retina. Phylogenetic and gene structure analysis indicated that the zebrafish genome harbours two mglur6 paralogs, mglur6a and mglur6b. Besides expression in the inner nuclear layer and distinct regions in the brain, both mglur6 paralogs are expressed in ganglion cells of the retina, an expression pattern which can also be observed in the downstream effector molecules gnaoa and gnaob. This unexpected expression pattern is consistent with immunohistological labeling using a peptide antibody specific for the mGluR6b paralog. These expression patterns contradict the existing view that mGluR6 is solely located on ON-bipolar cells where it functions in signal transmission. Consistent with expression in ON-bipolar cells, we report a decreased b-wave amplitude in the electroretinogram after morpholino-based downregulation of mGluR6b, showing a function in the ON response. Our data suggest more widespread functions of mGluR6 mediated signaling in the central nervous system, possibly including sign reversing synapses in the inner retina.

  15. 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.

  16. A Toolkit for Orthogonal and in vivo Optical Manipulation of Ionotropic Glutamate Receptors.

    Science.gov (United States)

    Levitz, Joshua; Popescu, Andrei T; Reiner, Andreas; Isacoff, Ehud Y

    2016-01-01

    The ability to optically manipulate specific neuronal signaling proteins with genetic precision paves the way for the dissection of their roles in brain function, behavior, and disease. Chemical optogenetic control with photoswitchable tethered ligands (PTLs) enables rapid, reversible and reproducible activation or block of specific neurotransmitter-gated receptors and ion channels in specific cells. In this study, we further engineered and characterized the light-activated GluK2 kainate receptor, LiGluR, to develop a toolbox of LiGluR variants. Low-affinity LiGluRs allow for efficient optical control of GluK2 while removing activation by native glutamate, whereas variant RNA edited versions enable the synaptic role of receptors with high and low Ca(2+) permeability to be assessed and spectral variant photoswitches provide flexibility in illumination. Importantly, we establish that LiGluR works efficiently in the cortex of awake, adult mice using standard optogenetic techniques, thus opening the door to probing the role of specific synaptic receptors and cellular signals in the neural circuit operations of the mammalian brain in normal conditions and in disease. The principals developed in this study are widely relevant to the engineering and in vivo use of optically controllable proteins, including other neurotransmitter receptors.

  17. Role of the NR2A/2B subunits of the N-methyl-D-aspartate receptor in glutamate-induced glutamic acid decarboxylase alteration in cortical GABAergic neurons in vitro.

    Science.gov (United States)

    Monnerie, H; Hsu, F-C; Coulter, D A; Le Roux, P D

    2010-12-29

    The vulnerability of brain neuronal cell subpopulations to neurologic insults varies greatly. Among cells that survive a pathological insult, for example ischemia or brain trauma, some may undergo morphological and/or biochemical changes that may compromise brain function. The present study is a follow-up of our previous studies that investigated the effect of glutamate-induced excitotoxicity on the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67)'s expression in surviving DIV 11 cortical GABAergic neurons in vitro [Monnerie and Le Roux, (2007) Exp Neurol 205:367-382, (2008) Exp Neurol 213:145-153]. An N-methyl-D-aspartate receptor (NMDAR)-mediated decrease in GAD expression was found following glutamate exposure. Here we examined which NMDAR subtype(s) mediated the glutamate-induced change in GAD protein levels. Western blotting techniques on cortical neuron cultures showed that glutamate's effect on GAD proteins was not altered by NR2B-containing diheteromeric (NR1/NR2B) receptor blockade. By contrast, blockade of triheteromeric (NR1/NR2A/NR2B) receptors fully protected against a decrease in GAD protein levels following glutamate exposure. When receptor location on the postsynaptic membrane was examined, extrasynaptic NMDAR stimulation was observed to be sufficient to decrease GAD protein levels similar to that observed after glutamate bath application. Blocking diheteromeric receptors prevented glutamate's effect on GAD proteins after extrasynaptic NMDAR stimulation. Finally, NR2B subunit examination with site-specific antibodies demonstrated a glutamate-induced, calpain-mediated alteration in NR2B expression. These results suggest that glutamate-induced excitotoxic NMDAR stimulation in cultured GABAergic cortical neurons depends upon subunit composition and receptor location (synaptic vs. extrasynaptic) on the neuronal membrane. Biochemical alterations in surviving cortical GABAergic neurons in various disease states may contribute to the altered

  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. Valerian extract and valerenic acid are partial agonists of the 5-HT5a receptor in vitro

    Science.gov (United States)

    Dietz, Birgit M.; Mahady, Gail B.; Pauli, Guido F.; Farnsworth, Norman R.

    2018-01-01

    Insomnia is the most frequently encountered sleep complaint worldwide. While many prescription drugs are used to treat insomnia, extracts of valerian (Valeriana officinalis L., Valerianaceae) are also used for the treatment of insomnia and restlessness. To determine novel mechanisms of action, radioligand binding studies were performed with valerian extracts (100% methanol, 50% methanol, dichloromethane [DCM], and petroleum ether [PE]) at the melatonin, glutamate, and GABAA receptors, and 8 serotonin receptor subtypes. Both DCM and PE extracts had strong binding affinity to the 5-HT5a receptor, but only weak binding affinity to the 5-HT2b and the serotonin transporter. Subsequent binding studies focused on the 5-HT5a receptor due to the distribution of this receptor in the suprachiasmatic nucleus of the brain, which is implicated in the sleep–wake cycle. The PE extract inhibited [3H]lysergic acid diethylamide (LSD) binding to the human 5-HT5a receptor (86% at 50 μg/ml) and the DCM extract inhibited LSD binding by 51%. Generation of an IC50 curve for the PE extract produced a biphasic curve, thus GTP shift experiments were also performed. In the absence of GTP, the competition curve was biphasic (two affinity sites) with an IC50 of 15.7 ng/ml for the high-affinity state and 27.7 μg/ml for the low-affinity state. The addition of GTP (100 AM) resulted in a right-hand shift of the binding curve with an IC50 of 11.4 μg/ml. Valerenic acid, the active constituent of both extracts, had an IC50 of 17.2 AM. These results indicate that valerian and valerenic acid are new partial agonists of the 5-HT5a receptor. PMID:15921820

  20. α2-Adrenergic modulation of the glutamate receptor and transporter function in a chronic ocular hypertension model.

    Science.gov (United States)

    Jung, Kyoung In; Kim, Jie Hyun; Park, Chan Kee

    2015-10-15

    Excitotoxicity, glutamate-induced toxic effects to retinal ganglion cells (RGCs), is one of several mechanisms of RGC loss suggested in glaucoma. In this study, we focused on the role of glutamate transporter of glial cells as well as N-methyl-d-aspartate (NMDA) receptor with regard to glutamate toxicity in glaucoma. We also investigated whether α2-adrenoceptor activation could modulate glutamate transporters and NMDA receptors in a chronic ocular hypertension model. Brimonidine 0.15% was administered topically to the eyes of experimental glaucoma and control animals twice daily. After 8 weeks of intraocular pressure (IOP) elevation, staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) revealed an increase in the ganglion cell layer, and the number of TUNEL-positive cells was reduced by brimonidine treatment (P<0.05). Animals with experimentally induced glaucoma exhibited an increase in retinal stress marker glial fibrillary acidic protein (GFAP) immunoreactivity; brimonidine treatment reduced GFAP. Excitatory amino acid transporter 1(EAAT1) expression remained stable throughout the period of chronic ocular hypertension. α2-Adrenergic treatment upregulated EAAT1 protein levels (P<0.05). NMDA receptor (GluN1) expression was stimulated by chronic elevation of IOP, and GluN1-positive cells in ganglion cell layer were co-localized with TUNEL staining. Brimonidine administration suppressed GluN1 levels (P<0.05). These results indicate that brimonidine decreased RGC apoptosis, upregulating EAAT1 and downregulating NMDA receptors. We suggest that topical brimonidine treatment may decrease the glutamate excitotoxicity through modulation of glutamate transporter and NMDA receptor in glaucoma. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Task-specific enhancement of short-term, but not long-term, memory by class I metabotropic glutamate receptor antagonist 1-aminoindan-1,5-dicarboxylic acid in rats

    DEFF Research Database (Denmark)

    Christoffersen, G.R.J.; Christensen, Lone H.; Harrington, Nicholas R.

    1999-01-01

    Metabotropic glutamate receptors; Class I antagonist; 1-aminoindan-1,5-dicarboxylic acid; spatial learning; contextual conditioning; rats......Metabotropic glutamate receptors; Class I antagonist; 1-aminoindan-1,5-dicarboxylic acid; spatial learning; contextual conditioning; rats...

  2. 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.

  3. Monosodium glutamate alters the response properties of rat trigeminovascular neurons through activation of peripheral NMDA receptors.

    Science.gov (United States)

    O'Brien, Melissa; Cairns, Brian E

    2016-10-15

    Ingestion of monosodium glutamate (MSG) has been shown to cause headaches in healthy individuals and trigger migraine-like headaches in migraine sufferers. We combined immunohistochemistry, in vivo electrophysiology, and laser Doppler recordings of dural vasculature to investigate the effect of systemic administration of MSG on the trigeminovascular pathway. Immunohistochemical analysis confirmed the expression of NMDA receptors on nerve fibers innervating dural blood vessels and excitatory amino acid transporter 2 on dural blood vessels. Systemic administration of MSG (50mg/kg) evoked an increase in ongoing discharge in 5/6 spinal trigeminal subnucleus caudalis (SpVc) neurons with dural input recorded from male and female rats, respectively, as well as lowering their mechanical activation threshold. There were no sex-related differences in these effects of MSG. Neuronal discharge and mechanical sensitization were significantly attenuated by co-injection with the peripherally restricted NMDA receptor antagonist (2R)-amino-5-phosphonovaleric acid (APV) in both sexes. Systemic administration of MSG induced a 24.5% and 20.6% increase in dural flux in male and female rats, respectively. These results suggest that MSG-induced headache is mediated by the activation of peripheral NMDA receptors and subsequent dural vasodilation. Peripheral NMDA receptors are a potential target for the development of new drugs to treat headaches. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  4. 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)

  5. Environmental Enrichment Ameliorates Behavioral Impairments Modeling Schizophrenia in Mice Lacking Metabotropic Glutamate Receptor 5.

    Science.gov (United States)

    Burrows, Emma L; McOmish, Caitlin E; Buret, Laetitia S; Van den Buuse, Maarten; Hannan, Anthony J

    2015-07-01

    Schizophrenia arises from a complex interplay between genetic and environmental factors. Abnormalities in glutamatergic signaling have been proposed to underlie the emergence of symptoms, in light of various lines of evidence, including the psychotomimetic effects of NMDA receptor antagonists. Metabotropic glutamate receptor 5 (mGlu5) has also been implicated in the disorder, and has been shown to physically interact with NMDA receptors. To clarify the role of mGlu5-dependent behavioral expression by environmental factors, we assessed mGlu5 knockout (KO) mice after exposure to environmental enrichment (EE) or reared under standard conditions. The mGlu5 KO mice showed reduced prepulse inhibition (PPI), long-term memory deficits, and spontaneous locomotor hyperactivity, which were all attenuated by EE. Examining the cellular impact of genetic and environmental manipulation, we show that EE significantly increased pyramidal cell dendritic branching and BDNF protein levels in the hippocampus of wild-type mice; however, mGlu5 KO mice were resistant to these alterations, suggesting that mGlu5 is critical to these responses. A selective effect of EE on the behavioral response to the NMDA receptor antagonist MK-801 in mGlu5 KO mice was seen. MK-801-induced hyperlocomotion was further potentiated in enriched mGlu5 KO mice and treatment with MK-801 reinstated PPI disruption in EE mGlu5 KO mice only, a response that is absent under standard housing conditions. Together, these results demonstrate an important role for mGlu5 in environmental modulation of schizophrenia-related behavioral impairments. Furthermore, this role of the mGlu5 receptor is mediated by interaction with NMDA receptor function, which may inform development of novel therapeutics.

  6. Deletion of Type 2 Metabotropic Glutamate Receptor Decreases Sensitivity to Cocaine Reward in Rats.

    Science.gov (United States)

    Yang, Hong-Ju; Zhang, Hai-Ying; Bi, Guo-Hua; He, Yi; Gao, Jun-Tao; Xi, Zheng-Xiong

    2017-07-11

    Cocaine users show reduced expression of the metabotropic glutamate receptor (mGluR2), but it is not clear whether this is a predisposing trait for addiction or a consequence of drug exposure. In this study, we found that a nonsense mutation at the mGluR2 gene decreased mGluR2 expression and altered the seeking and taking of cocaine. mGluR2 mutant rats show reduced sensitivity to cocaine reward, requiring more cocaine to reach satiation when it was freely available and ceasing their drug-seeking behavior sooner than controls when the response requirement was increased. mGluR2 mutant rats also show a lower propensity to relapse after a period of cocaine abstinence, an effect associated with reduced cocaine-induced dopamine and glutamate overflow in the nucleus accumbens. These findings suggest that mGluR2 polymorphisms or reduced availability of mGluR2 might be risk factors for the initial development of cocaine use but could actually protect against addiction by reducing sensitivity to cocaine reward. Published by Elsevier Inc.

  7. Deletion of Type 2 Metabotropic Glutamate Receptor Decreases Sensitivity to Cocaine Reward in Rats

    Directory of Open Access Journals (Sweden)

    Hong-Ju Yang

    2017-07-01

    Full Text Available Cocaine users show reduced expression of the metabotropic glutamate receptor (mGluR2, but it is not clear whether this is a predisposing trait for addiction or a consequence of drug exposure. In this study, we found that a nonsense mutation at the mGluR2 gene decreased mGluR2 expression and altered the seeking and taking of cocaine. mGluR2 mutant rats show reduced sensitivity to cocaine reward, requiring more cocaine to reach satiation when it was freely available and ceasing their drug-seeking behavior sooner than controls when the response requirement was increased. mGluR2 mutant rats also show a lower propensity to relapse after a period of cocaine abstinence, an effect associated with reduced cocaine-induced dopamine and glutamate overflow in the nucleus accumbens. These findings suggest that mGluR2 polymorphisms or reduced availability of mGluR2 might be risk factors for the initial development of cocaine use but could actually protect against addiction by reducing sensitivity to cocaine reward.

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

    Science.gov (United States)

    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 (1-3 mm) antral ...

  9. Interleukin-1 beta down-regulates the expression of metabotropic glutamate receptor 5 in cultured human astrocytes

    NARCIS (Netherlands)

    Aronica, E.; Gorter, J.A.; Rozemuller, A.J.M.; Yankaya, B.; Troost, D.

    2005-01-01

    Expression of metabotropic glutamate receptor 5 (mGluR5) protein is known to be plastic and to depend critically on the astrocytes' microenvironment. In the present study we investigated whether interleukins, which are involved in the immune response following brain injury, could contribute to the

  10. Interleukin-1 beta down-regulates the expression of metabotropic glutamate receptor 5 in cultured human astrocytes

    NARCIS (Netherlands)

    Aronica, Eleonora; Gorter, Jan A.; Rozemuller, Annemieke J.; Yankaya, Bulent; Troost, Dirk

    2005-01-01

    Expression of metabotropic glutamate receptor 5 (mGluR5) protein is known to be plastic and to depend critically oil the astrocytes' microenvironment. In the present study we investigated whether interleukins, which are involved in the immune response following brain injury, could contribute to the

  11. 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

    The 1,2,4-benzothiadiazine 1,1-dioxide type of positive allosteric modulators of the ionotropic glutamate receptor A2 (GluA2) are promising lead compounds for the treatment of cognitive disorders, e.g., Alzheimer’s disease. The modulators bind in a cleft formed by the interface of two neighboring...

  12. Selective antagonists at group I metabotropic glutamate receptors: synthesis and molecular pharmacology of 4-aryl-3-isoxazolol amino acids

    DEFF Research Database (Denmark)

    Kromann, Hasse; Sløk, Frank A; Stensbøl, Tine B

    2002-01-01

    Homologation of (S)-glutamic acid (Glu, 1) and Glu analogues has previously provided ligands with activity at metabotropic Glu receptors (mGluRs). The homologue of ibotenic acid (7), 2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid (HIBO, 8), and the 4-phenyl derivative of 8, compound 9a, are bot...

  13. Metabotropic Glutamate2 Receptors Play a Key Role in Modulating Head Twitches Induced by a Serotonergic Hallucinogen in Mice

    Directory of Open Access Journals (Sweden)

    Mark J. Benvenga

    2018-03-01

    Full Text Available There is substantial evidence that glutamate can modulate the effects of 5-hydroxytryptamine2A (5-HT2A receptor activation through stimulation of metabotropic glutamate2/3 (mGlu2/3 receptors in the prefrontal cortex. Here we show that constitutive deletion of the mGlu2 gene profoundly attenuates an effect of 5-HT2A receptor activation using the mouse head twitch response (HTR. MGlu2 and mGlu3 receptor knockout (KO as well as age-matched ICR (CD-1 wild type (WT mice were administered (±1-(2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI and observed for head twitch activity. DOI failed to produce significant head twitches in mGlu2 receptor KO mice at a dose 10-fold higher than the peak effective dose in WT or mGlu3 receptor KO mice. In addition, the mGlu2/3 receptor agonist LY379268, and the mGlu2 receptor positive allosteric modulator (PAM CBiPES, potently blocked the HTR to DOI in WT and mGlu3 receptor KO mice. Conversely, the mGlu2/3 receptor antagonist LY341495 (10 mg/kg increased the HTR produced by DOI (3 mg/kg in mGlu3 receptor KO mice. Finally, the mGlu2 receptor potentiator CBiPES was able to attenuate the increase in the HTR produced by LY341495 in mGlu3 receptor KO mice. Taken together, all of these results are consistent with the hypothesis that that DOI-induced head twitches are modulated by mGlu2 receptor activation. These results also are in keeping with a critical autoreceptor function for mGlu2 receptors in the prefrontal cortex with differential effects of acute vs. chronic perturbation (e.g., constitutive mGlu2 receptor KO mice. The robust attenuation of DOI-induced head twitches in the mGlu2 receptor KO mice appears to reflect the critical role of glutamate in ongoing regulation of 5-HT2A receptors in the prefrontal cortex. Future experiments with inducible knockouts for the mGlu2 receptor and/or selective mGlu3 receptor agonists/PAMs/antagonists could provide an important tools in understanding glutamatergic modulation of

  14. Localization of CGRP, CGRP receptor, PACAP and glutamate in trigeminal ganglion. Relation to the blood-brain barrier

    DEFF Research Database (Denmark)

    Eftekhari, Sajedeh; Salvatore, Christopher A; Johansson, Sara

    2015-01-01

    Calcitonin gene-related peptide (CGRP) receptor antagonists have demonstrated anti-migraine efficacy. One remaining question is where do these blockers act? We hypothesized that the trigeminal ganglion could be one possible site. We examined the binding sites of a CGRP receptor antagonist (MK-3207......) and related this to the expression of CGRP and its receptor in rhesus trigeminal ganglion. Pituitary adenylate cyclase-activating polypeptide (PACAP) and glutamate were examined and related to the CGRP system. Furthermore, we examined if the trigeminal ganglion is protected by the blood-brain barrier (BBB......). Autoradiography was performed with [(3)H]MK-3207 to demonstrate receptor binding sites in rhesus trigeminal ganglion (TG). Immunofluorescence was used to correlate binding and the presence of CGRP and its receptor components, calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1...

  15. Group I metabotropic glutamate receptors reduce excitotoxic injury and may facilitate neurogenesis

    DEFF Research Database (Denmark)

    Baskys, Andrius; Bayazitov, Ildar; Fang, Liwei

    2005-01-01

    neuroprotective activation of group I metabotropic glutamate receptors. Brain Research, Molecular Brain Research 117, 196-205.]. In the present study, we used organotypic hippocampal culture preparation to examine specific phospholipase C (PLC) inhibitor U73122 effects on DHPG-induced neuroprotection, changes......-CA1 pathway. The fEPSP depression was not affected by the PLC inhibitor U73122. In contrast, prolonged (2-h) treatment of cultures with DHPG induced a significant protective effect that was blocked by a PLC inhibitor U73122 but not by its inactive analog U73343. Voltage-clamp measurements...... a PLC involvement. Since activation of PLC is thought to be associated with cell proliferation, we investigated whether group I mGluR agonist DHPG or subtype antagonists LY367385 and MPEP have an effect on dentate granule cells expressing immature neuronal marker TOAD-64. DHPG (100 microM, 72 h...

  16. Induction of an Olfactory Memory by the Activation of a Metabotropic Glutamate Receptor

    Science.gov (United States)

    Kaba, Hideto; Hayashi, Yasunori; Higuchi, Takashi; Nakanishi, Shigetada

    1994-07-01

    Female mice form an olfactory memory of male pheromones at mating; exposure to the pheromones of a strange male after that mating will block pregnancy. The formation of this memory is mediated by the accessory olfactory system, in which an increase in norepinephrine after mating reduces inhibitory transmission of γ-aminobutyric acid from the granule cells to the mitral cells. This study shows that the activation of mGluR2, a metabotropic glutamate receptor that suppresses the γ-aminobutyric acid inhibition of the mitral cells, permits the formation of a specific olfactory memory without the occurrence of mating by infusion of mGluR2 agonists into the female's accessory olfactory bulb. This memory faithfully reflects the memory formed at mating.

  17. Fractalkine/CX3CL1 engages different neuroprotective responses upon selective glutamate receptor overactivation.

    Directory of Open Access Journals (Sweden)

    Clotilde eLauro

    2015-01-01

    Full Text Available Neuronal death induced by overactivation of N-methyl-d-aspartate receptors (NMDARs is implicated in the pathophysiology of many neurodegenerative diseases such as stroke, epilepsy and traumatic brain injury. This toxic effect is mainly mediated by NR2B-containing extrasynaptic NMDARs, while NR2A-containing synaptic NMDARs contribute to cell survival, suggesting the possibility of therapeutic approaches targeting specific receptor subunits. We report that fractalkine/CX3CL1 protects hippocampal neurons from NMDA-induced cell death with a mechanism requiring the adenosine receptors type 2A (A2AR. This is different from CX3CL1-induced protection from glutamate-induced cell death, that fully depends on A1R and requires in part A3R. We show that CX3CL1 neuroprotection against NMDA excitotoxicity involves D-serine, a co-agonist of NR2A/NMDAR, resulting in cyclic AMP-dependent transcription factor (CREB phosphorylation.

  18. Glutamate receptors within the nucleus of solitary tract contribute to pancreatic secretion stimulated by intraduodenal hypertonic saline.

    Science.gov (United States)

    Liao, Zhuan; Li, Zhao-Shen; Lu, Yan; Wang, Wei-Zhong

    2005-06-15

    It is well known that central transmission of vago-vagal reflex within the nucleus of solitary tract (NST) plays an important role in the regulation of gastrointestinal functions. The present study was designed to assess the role of NST glutamate receptor mechanism in pancreatic secretion evoked by intraduodenal hypertonic saline (HS) in anesthetized rats. Intraduodenal infusion of HS significantly (PmNST) produced a significant increase of pancreatic protein secretion (from 2.65+/-0.12 to 4.80+/-0.34 mg/15 min, PmNST completely abolished the increase of pancreatic protein output stimulated by intraduodenal HS (from 4.28+/-0.21 to 2.83+/-0.19 mg/15 min). Either NMDA receptor antagonist dl-2-amino-5-phosphonopentanoic acid (AP5, 1.5 nmol) or AMPA/Kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 1.5 nmol) injected into the mNST markedly attenuated (P<0.05) the pancreatic protein secretion stimulated by intraduodenal HS. In conclusion, these findings showed that blockade of the NST glutamate receptors, including NMDA and AMPA/Kainate receptors antagonized pancreatic secretion evoked by intraduodenal osmolality factor, and suggested that glutamate receptor mechanism within the NST contributed to the central regulation of pancreatic secretion.

  19. Membrane Estrogen Receptor-α Interacts with Metabotropic Glutamate Receptor Type 1a to Mobilize Intracellular Calcium in Hypothalamic Astrocytes

    Science.gov (United States)

    Kuo, John; Hariri, Omid R.; Bondar, Galyna; Ogi, Julie; Micevych, Paul

    2009-01-01

    Estradiol, acting on a membrane-associated estrogen receptor-α (mERα), induces an increase in free cytoplasmic calcium concentration ([Ca2+]i) needed for progesterone synthesis in hypothalamic astrocytes. To determine whether rapid estradiol signaling involves an interaction of mERα with metabotropic glutamate receptor type 1a (mGluR1a), changes in [Ca2+]i were monitored with the calcium indicator, Fluo-4 AM, in primary cultures of female postpubertal hypothalamic astrocytes. 17β-Estradiol over a range of 1 nm to 100 nm induced a maximal increase in [Ca2+]i flux measured as a change in relative fluorescence [ΔF Ca2+ = 615 ± 36 to 641 ± 47 relative fluorescent units (RFU)], whereas 0.1 nm of estradiol stimulated a moderate [Ca2+]i increase (275 ± 16 RFU). The rapid estradiol-induced [Ca2+]i flux was blocked with 1 μm of the estrogen receptor antagonist ICI 182,780 (635 ± 24 vs. 102 ± 11 RFU, P estradiol-induced membrane signaling in astrocytes. PMID:18948402

  20. 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

  1. Molecular dynamics in an optical trap of glutamate receptors labeled with quantum-dots on living neurons

    Science.gov (United States)

    Kishimoto, Tatsunori; Maezawa, Yasuyo; Kudoh, Suguru N.; Taguchi, Takahisa; Hosokawa, Chie

    2017-04-01

    Molecular dynamics of glutamate receptor, which is major neurotransmitter receptor at excitatory synapse located on neuron, is essential for synaptic plasticity in the complex neuronal networks. Here we studied molecular dynamics in an optical trap of AMPA-type glutamate receptor (AMPAR) labeled with quantum-dot (QD) on living neuronal cells with fluorescence imaging and fluorescence correlation spectroscopy (FCS). When a 1064-nm laser beam for optical trapping was focused on QD-AMPARs located on neuronal cells, the fluorescence intensity of QD-AMPARs gradually increased at the focal spot. Using single-particle tracking of QD-AMPARs on neurons, the average diffusion coefficient decreased in an optical trap. Moreover, the decay time obtained from FCS analysis increased with the laser power and the initial assembling state of AMPARs depended on culturing day, suggesting that the motion of QD-AMPAR was constrained in an optical trap.

  2. Coordinating structural and functional synapse development: postsynaptic p21-activated kinase independently specifies glutamate receptor abundance and postsynaptic morphology.

    Science.gov (United States)

    Albin, Stephanie D; Davis, Graeme W

    2004-08-04

    Here, we show that postsynaptic p21-activated kinase (Pak) signaling diverges into two genetically separable pathways at the Drosophila neuromuscular junction. One pathway controls glutamate receptor abundance. Pak signaling within this pathway is specified by a required interaction with the adaptor protein Dreadlocks (Dock). We demonstrate that Dock is localized to the synapse via an Src homology 2-mediated protein interaction. Dock is not necessary for Pak localization but is necessary to restrict Pak signaling to control glutamate receptor abundance. A second genetically separable function of Pak kinase signaling controls muscle membrane specialization through the regulation of synaptic Discs-large. In this pathway, Dock is dispensable. We present a model in which divergent Pak signaling is able to coordinate two different features of postsynaptic maturation, receptor abundance, and muscle membrane specialization.

  3. Chimeric Glutamate Receptor Subunits Reveal the Transmembrane Domain Is Sufficient for NMDA Receptor Pore Properties but Some Positive Allosteric Modulators Require Additional Domains.

    Science.gov (United States)

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

    2016-08-24

    NMDA receptors are ligand-gated ion channels that underlie transmission at excitatory synapses and play an important role in regulating synaptic strength and stability. Functional NMDA receptors require two copies of the GluN1 subunit coassembled with GluN2 (and/or GluN3) subunits into a heteromeric tetramer. A diverse array of allosteric modulators can upregulate or downregulate NMDA receptor activity. These modulators include both synthetic compounds and endogenous modulators, such as cis-unsaturated fatty acids, 24(S)-hydroxycholesterol, and various neurosteroids. To evaluate the structural requirements for the formation and allosteric modulation of NMDA receptor pores, we have replaced portions of the rat GluN1, GluN2A, and GluN2B subunits with homologous segments from the rat GluK2 kainate receptor subunit. Our results with these chimeric constructs show that the NMDA receptor transmembrane domain is sufficient to account for most pore properties, but that regulation by some allosteric modulators requires additional cytoplasmic or extracellular domains. Glutamate receptors mediate excitatory synaptic transmission by forming cation channels through the membrane that open upon glutamate binding. Although many compounds have been identified that regulate glutamate receptor activity, in most cases the detailed mechanisms that underlie modulation are poorly understood. To identify what parts of the receptor are essential for pore formation and sensitivity to allosteric modulators, we generated chimeric subunits that combined segments from NMDA and kainate receptors, subtypes with distinct pharmacological profiles. Surprisingly, our results identify separate domain requirements for allosteric potentiation of NMDA receptor pores by pregnenolone sulfate, 24(S)-hydroxycholesterol, and docosahexaenoic acid, three endogenous modulators derived from membrane constituents. Understanding where and how these compounds act on NMDA receptors should aid in designing better

  4. Regulated Release of BDNF by Cortical Oligodendrocytes is Mediated Through Metabotropic Glutamate Receptors and the PLC Pathway

    Directory of Open Access Journals (Sweden)

    Issa P Bagayogo

    2009-02-01

    Full Text Available A number of studies suggest that OLGs (oligodendrocytes, the myelinating cells of the central nervous system, are also a source of trophic molecules, such as neurotrophins that may influence survival of proximate neurons. What is less clear is how the release of these molecules may be regulated. The present study investigated the effects of BDNF (brain-derived neurotrophic factor derived from cortical OLGs on proximate neurons, as well as regulatory mechanisms mediating BDNF release. Initial work determined that BDNF derived from cortical OLGs increased the numbers of VGLUT1 (vesicular glutamate transporter 1-positive glutamatergic cortical neurons. Furthermore, glutamate acting through metabotropic, and not AMPA/kainate or NMDA (N-methyl-D-aspartate, receptors increased BDNF release. The PLC (phospholipase C pathway is a key mediator of metabotropic actions to release BDNF in astrocytes and neurons. Treatment of OLGs with the PLC activator m-3M3FBS [N-(3-trifluoromethylphenyl-2,4,6-trimethylbenzenesulfonamide] induced robust release of BDNF. Moreover, release elicited by the metabotropic receptor agonist ACPD [trans-(1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid] was inhibited by the PLC antagonist U73122, the IP3 (inositol triphosphate 3 receptor inhibitor 2-APB (2-aminoethoxydiphenylborane and the intracellular calcium chelator BAPTA/AM [1,2-bis-(o-aminophenoxyethane-N,N,N′,N′-tetra-acetic acid tetrakis(acetoxymethyl ester]. Taken together, these results suggest that OLG lineage cells release BDNF, a molecule trophic for proximate neurons. BDNF release is regulated by glutamate acting through mGluRs (metabotropic glutamate receptors and the PLC pathway. Thus glutamate and BDNF may be molecules that support neuron–OLG interactions in the cortex.

  5. Metabotropic glutamate receptor-1 contributes to progression in triple negative breast cancer.

    Directory of Open Access Journals (Sweden)

    Malathi Banda

    Full Text Available TNBC is an aggressive breast cancer subtype that does not express hormone receptors (estrogen and progesterone receptors, ER and PR or amplified human epidermal growth factor receptor type 2 (HER2, and there currently exist no targeted therapies effective against it. Consequently, finding new molecular targets in triple negative breast cancer (TNBC is critical to improving patient outcomes. Previously, we have detected the expression of metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1 in TNBC and observed that targeting glutamatergic signaling inhibits TNBC growth both in vitro and in vivo. In this study, we explored how mGluR1 contributes to TNBC progression, using the isogenic MCF10 progression series, which models breast carcinogenesis from nontransformed epithelium to malignant basal-like breast cancer. We observed that mGluR1 is expressed in human breast cancer and that in MCF10A cells, which model nontransformed mammary epithelium, but not in MCF10AT1 cells, which model atypical ductal hyperplasia, mGluR1 overexpression results in increased proliferation, anchorage-independent growth, and invasiveness. In contrast, mGluR1 knockdown results in a decrease in these activities in malignant MCF10CA1d cells. Similarly, pharmacologic inhibition of glutamatergic signaling in MCF10CA1d cells results in a decrease in proliferation and anchorage-independent growth. Finally, transduction of MCF10AT1 cells, which express c-Ha-ras, using a lentiviral construct expressing GRM1 results in transformation to carcinoma in 90% of resultant xenografts. We conclude that mGluR1 cooperates with other factors in hyperplastic mammary epithelium to contribute to TNBC progression and therefore propose that glutamatergic signaling represents a promising new molecular target for TNBC therapy.

  6. Glutamate Increases In Vitro Survival and Proliferation and Attenuates Oxidative Stress-Induced Cell Death in Adult Spinal Cord-Derived Neural Stem/Progenitor Cells via Non-NMDA Ionotropic Glutamate Receptors.

    Science.gov (United States)

    Hachem, Laureen D; Mothe, Andrea J; Tator, Charles H

    2016-08-15

    Traumatic spinal cord injury (SCI) leads to a cascade of secondary chemical insults, including oxidative stress and glutamate excitotoxicity, which damage host neurons and glia. Transplantation of exogenous neural stem/progenitor cells (NSPCs) has shown promise in enhancing regeneration after SCI, although survival of transplanted cells remains poor. Understanding the response of NSPCs to the chemical mediators of secondary injury is essential in finding therapies to enhance survival. We examined the in vitro effects of glutamate and glutamate receptor agonists on adult rat spinal cord-derived NSPCs. NSPCs isolated from the periventricular region of the adult rat spinal cord were exposed to various concentrations of glutamate for 96 h. We found that glutamate treatment (500 μM) for 96 h significantly increased live cell numbers, reduced cell death, and increased proliferation, but did not significantly alter cell phenotype. Concurrent glutamate treatment (500 μM) in the setting of H2O2 exposure (500 μM) for 10 h increased NSPC survival compared to H2O2 exposure alone. The effects of glutamate on NSPCs were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist GYKI-52466, but not by the N-methyl-D-aspartic acid receptor antagonist MK-801 or DL-AP5, or the mGluR3 antagonist LY-341495. Furthermore, treatment of NSPCs with AMPA, kainic acid, or the kainate receptor-specific agonist (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid mimicked the responses seen with glutamate both alone and in the setting of oxidative stress. These findings offer important insights into potential mechanisms to enhance NSPC survival and implicate a potential role for glutamate in promoting NSPC survival and proliferation after traumatic SCI.

  7. Double Dissociation of the Roles of Metabotropic Glutamate Receptor 5 and Oxytocin Receptor in Discrete Social Behaviors.

    Science.gov (United States)

    Mesic, Ivana; Guzman, Yomayra F; Guedea, Anita L; Jovasevic, Vladimir; Corcoran, Kevin A; Leaderbrand, Katherine; Nishimori, Katsuhiko; Contractor, Anis; Radulovic, Jelena

    2015-09-01

    Social interactions in vertebrates are complex phenomena based on affective and cognitive processes. Multiple brain regions and neurotransmitter systems are involved in the expression of social behaviors, but their individual roles in specific aspects of social interactions are not well understood. Here we investigated how Gq-protein-coupled metabotropic glutamate receptor 5 (mGluR5) and oxytocin receptor (Oxtr) affect social affiliation and social memory. We used conditional genetic approaches in which the genes coding for these receptors were knocked out in the lateral septum by infusion of recombinant adeno-associated viral vectors containing Cre recombinase (AAV-Cre). Social behavior was assessed 2 weeks later using a three-chamber paradigm for sociability and preference for social novelty. Septal deletion of mGluR5 abolished sociability while leaving preference for social novelty intact. In contrast, deletion of Oxtr did not affect sociability but significantly impaired preference for social novelty. Nonsocial behaviors or memories, including novel object recognition or fear conditioning, were not affected by these genetic manipulations. Immunohistochemical analyses of the distribution of mGluR5 and Oxtr revealed non-overlapping localization of these receptors within the lateral septum, suggesting that not only different neurotransmitters but also different neuronal types contribute to sociability versus preference for social novelty. Our findings identify highly specialized roles of lateral septal mGluR5 and Oxtr in the the regulation of discrete social behaviors, and suggest that deficits in social interactions, which accompany many mental illnesses, would benefit from comprehensive treatments targeting different components of social functioning.

  8. Preferential binding of allosteric modulators to active and inactive conformational states of metabotropic glutamate receptors

    Directory of Open Access Journals (Sweden)

    Klein-Seetharaman Judith

    2008-02-01

    Full Text Available Abstract Metabotropic glutamate receptors (mGluRs are G protein coupled receptors that play important roles in synaptic plasticity and other neuro-physiological and pathological processes. Allosteric mGluR ligands are particularly promising drug targets because of their modulatory effects – enhancing or suppressing the response of mGluRs to glutamate. The mechanism by which this modulation occurs is not known. Here, we propose the hypothesis that positive and negative modulators will differentially stabilize the active and inactive conformations of the receptors, respectively. To test this hypothesis, we have generated computational models of the transmembrane regions of different mGluR subtypes in two different conformations. The inactive conformation was modeled using the crystal structure of the inactive, dark state of rhodopsin as template and the active conformation was created based on a recent model of the light-activated state of rhodopsin. Ligands for which the nature of their allosteric effects on mGluRs is experimentally known were docked to the modeled mGluR structures using ArgusLab and Autodock softwares. We find that the allosteric ligand binding pockets of mGluRs are overlapping with the retinal binding pocket of rhodopsin, and that ligands have strong preferences for the active and inactive states depending on their modulatory nature. In 8 out of 14 cases (57%, the negative modulators bound the inactive conformations with significant preference using both docking programs, and 6 out of 9 cases (67%, the positive modulators bound the active conformations. Considering results by the individual programs only, even higher correlations were observed: 12/14 (86% and 8/9 (89% for ArgusLab and 10/14 (71% and 7/9 (78% for AutoDock. These findings strongly support the hypothesis that mGluR allosteric modulation occurs via stabilization of different conformations analogous to those identified in rhodopsin where they are induced by

  9. Conformational Plasticity in the Transsynaptic Neurexin-Cerebellin-Glutamate Receptor Adhesion Complex

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shouqiang; Seven, Alpay B.; Wang, Jing; Skiniotis, Georgios; Özkan, Engin (UC); (Michigan)

    2016-12-01

    Synaptic specificity is a defining property of neural networks. In the cerebellum, synapses between parallel fiber neurons and Purkinje cells are specified by the simultaneous interactions of secreted protein cerebellin with pre-synaptic neurexin and post-synaptic delta-type glutamate receptors (GluD). Here, we determined the crystal structures of the trimeric C1q-like domain of rat cerebellin-1, and the first complete ectodomain of a GluD, rat GluD2. Cerebellin binds to the LNS6 domain of α- and β-neurexin-1 through a high-affinity interaction that involves its highly flexible N-terminal domain. In contrast, we show that the interaction of cerebellin with isolated GluD2 ectodomain is low affinity, which is not simply an outcome of lost avidity when compared with binding with a tetrameric full-length receptor. Rather, high-affinity capture of cerebellin by post-synaptic terminals is likely controlled by long-distance regulation within this transsynaptic complex. Altogether, our results suggest unusual conformational flexibility within all components of the complex.

  10. The metabotropic glutamate 5 receptor modulates extinction and reinstatement of methamphetamine-seeking in mice.

    Directory of Open Access Journals (Sweden)

    Rose Chesworth

    Full Text Available Methamphetamine (METH is a highly addictive psychostimulant with no therapeutics registered to assist addicts in discontinuing use. Glutamatergic dysfunction has been implicated in the development and maintenance of addiction. We sought to assess the involvement of the metabotropic glutamate 5 receptor (mGlu5 in behaviours relevant to METH addiction because this receptor has been implicated in the actions of other drugs of abuse, including alcohol, cocaine and opiates. mGlu5 knockout (KO mice were tested in intravenous self-administration, conditioned place preference and locomotor sensitization. Self-administration of sucrose was used to assess the response of KO mice to a natural reward. Acquisition and maintenance of self-administration, as well as the motivation to self-administer METH was intact in mGlu5 KO mice. Importantly, mGlu5 KO mice required more extinction sessions to extinguish the operant response for METH, and exhibited an enhanced propensity to reinstate operant responding following exposure to drug-associated cues. This phenotype was not present when KO mice were tested in an equivalent paradigm assessing operant responding for sucrose. Development of conditioned place preference and locomotor sensitization were intact in KO mice; however, conditioned hyperactivity to the context previously paired with drug was elevated in KO mice. These data demonstrate a role for mGlu5 in the extinction and reinstatement of METH-seeking, and suggests a role for mGlu5 in regulating contextual salience.

  11. Operant sensation seeking requires metabotropic glutamate receptor 5 (mGluR5.

    Directory of Open Access Journals (Sweden)

    Christopher M Olsen

    2010-11-01

    Full Text Available Pharmacological and genetic studies have suggested that the metabotropic glutamate receptor 5 (mGluR5 is critically involved in mediating the reinforcing effects of drugs of abuse, but not food. The purpose of this study was to use mGluR5 knockout (KO, heterozygous (Het, and wildtype (WT mice to determine if mGluR5 modulates operant sensation seeking (OSS, an operant task that uses varied sensory stimuli as a reinforcer. We found that mGluR5 KO mice had significantly reduced OSS responding relative to WT mice, while Het mice displayed a paradoxical increase in OSS responding. Neither KO nor Het mice exhibited altered operant responding for food as a reinforcer. Further, we assessed mGluR5 KO, Het and WT mice across a battery of cocaine locomotor, place preference and anxiety related tests. Although KO mice showed expected differences in some locomotor and anxiety measures, Het mice either exhibited no phenotype or an intermediate one. In total, these data demonstrate a key role for mGluR5 in OSS, indicating an important role for this receptor in reinforcement-based behavior.

  12. Extracellular ATP modulates synaptic plasticity induced by activation of metabotropic glutamate receptors in the hippocampus.

    Science.gov (United States)

    Yamazaki, Yoshihiko; Fujii, Satoshi

    2015-01-01

    Synaptic plasticity is believed to be a cellular mechanism for memory formation in the brain. It has been known that the metabotropic glutamate receptor (mGluR) is required for persistent forms of memory and induction of synaptic plasticity. Application of mGluR agonists induces synaptic plasticity in the absence of electrical conditioning stimulation, such as high or low frequency stimulation. The direction of the mGluR-induced synaptic plasticity, i.e., either long-term potentiation (LTP) or long-term-depression (LTD), is dependent on whether N-methyl-D-aspartate receptors (NMDARs) are co-activated with mGluRs. ATP has modulatory effects on neuronal functions and, in particular, there is increasing evidence that it plays a crucial role in synaptic plasticity. LTP can be induced by application of ATP, and this effect is inhibited by NMDAR antagonist. Although cooperative effects of NMDARs and mGluRs and of NMDARs and extracellular ATP in synaptic plasticity have been revealed, the effect of extracellular ATP on mGluR-induced synaptic plasticity is unknown. In this article, we summarize published data on mGluR- and ATP-induced synaptic plasticity, and present new data showing that extracellular ATP facilitates both the LTP and LTD induced by mGluR activation.

  13. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics

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    Zhe eJin

    2014-09-01

    Full Text Available The central nucleus of amygdala (CeA has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n=9 and matched controls (n=9 were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR. Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-ylpropanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence.

  14. Differential expression of metabotropic glutamate and GABAB receptors at neocortical glutamatergic and GABAergic axon terminals

    Directory of Open Access Journals (Sweden)

    Luca eBragina

    2015-09-01

    Full Text Available Metabotropic glutamate receptors (mGluRs and GABAB receptors are highly expressed at presynaptic sites. To verify the possibility that the two classes of metabotropic receptors contribute to axon terminals heterogeneity, we studied the localization of mGluR1α, mGluR5, mGluR2/3, mGluR7 and GABAB1 in VGLUT1-, VGLUT2- and VGAT-positive terminals in the cerebral cortex of adult rats. VGLUT1-positive puncta expressed mGluR1α (~5%, mGluR5 (~6%, mGluR2/3 (~22%, mGluR7 (~17%, and GABAB1 (~40%; VGLUT2-positive terminals expressed mGluR1α (~10%, mGluR5 (~11%, mGluR2/3 (~20%, mGluR7 (~28%, and GABAB1 (~25%; whereas VGAT-positive puncta expressed mGluR1α (~27%, mGluR5 (~24%, mGluR2/3 (~38%, mGluR7 (~31%, and GABAB1 (~19%. Control experiments ruled out the possibility that post-synaptic mGluRs and GABAB1 might have significantly biased our results. We also performed functional assays in synaptosomal preparations, and showed that all agonists modify Glu and GABA levels, which return to baseline upon exposure to antagonists.Overall, these findings indicate that mGluR1α, mGluR5, mGluR2/3, mGluR7 and GABAB1 expression differ significantly between glutamatergic and GABAergic axon terminals, and that the robust expression of heteroreceptors may contribute to the homeostatic regulation of the balance between excitation and inhibition.

  15. Attenuation of excitatory amino acid toxicity by metabotropic glutamate receptor agonists and aniracetam in primary cultures of cerebellar granule cells.

    Science.gov (United States)

    Pizzi, M; Fallacara, C; Arrighi, V; Memo, M; Spano, P F

    1993-08-01

    Activation of glutamate ionotropic receptors represents the primary event in the neurotoxicity process triggered by excitatory amino acids. We demonstrate here that the concentration-dependent stimulation of metabotropic glutamate receptor (mGluR) by the selective agonist trans-1-aminocyclopentane-1,3-dicarboxylate or by quisqualate counteracts both glutamate- and kainate-induced neurotoxicity in primary cultures of rat cerebellar granule cells. The mGluR-evoked responses are potentiated by aniracetam, which per se also elicits neuroprotection. Aniracetam concentration-dependently counteracted glutamate-, kainate-, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced cell death and greatly facilitated neuroprotective response achieved by different concentrations of both quisqualate and trans-1-aminocyclopentane-1,3-dicarboxylate. In addition, aniracetam potentiated the mGluR-coupled stimulation of phospholipase C, as revealed by the measurement of 3H-inositol phosphate formation. Thus, mGluRs could be a suitable target for novel pharmacological strategies pointing to the treatment of neurodegenerative diseases.

  16. Chemo-enzymatic synthesis of a series of 2,4-syn-functionalized (S)-glutamate analogues: new insight into the structure-activity relation of ionotropic glutamate receptor subtypes 5, 6, and 7

    DEFF Research Database (Denmark)

    Sagot, Emanuelle; Pickering, Darryl S; Pu, Xiaosui

    2008-01-01

    ( S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of five...

  17. Binding site and interlobe interactions of the ionotropic glutamate receptor GluK3 ligand binding domain revealed by high resolution crystal structure in complex with (S)-glutamate

    DEFF Research Database (Denmark)

    Venskutonyte, Raminta; Frydenvang, Karla; Gajhede, Michael

    2011-01-01

    Ionotropic glutamate receptors (iGluRs) are involved in excitatory signal transmission throughout the central nervous system and their malfunction is associated with various health disorders. GluK3 is a subunit of iGluRs, belonging to the subfamily of kainate receptors (GluK1-5). Several crystal...

  18. Effect of metabotropic glutamate receptor 3 genotype on N-acetylaspartate levels and neurocognition in non-smoking, active alcoholics

    OpenAIRE

    Xia, Yan; Ma, Dongying; Hu, Jian; Tang, Chunling; Wu, Zheng; Liu, Lei; Xin, Feng

    2012-01-01

    Abstract Background We studied the effects of single nucleotide polymorphisms (SNPs) in the metabotropic glutamate receptor 3 (GRM3) gene on brain N-acetylaspartate (NAA) concentrations and executive function (EF) skills in non-smoking, active alcoholics, and evaluated associations between these variables. Methods SNPs (rs6465084, rs1468412, and rs2299225) in GRM3 were genotyped in 49 male, non-smoking, alcohol-dependent patients and 45 healthy control subjects using ligase detection reaction...

  19. Aniracetam reduces glutamate receptor desensitization and slows the decay of fast excitatory synaptic currents in the hippocampus.

    OpenAIRE

    Isaacson, J S; Nicoll, R A

    1991-01-01

    Aniracetam is a nootropic drug that has been shown to selectively enhance quisqualate receptor-mediated responses in Xenopus oocytes injected with brain mRNA and in hippocampal pyramidal cells [Ito, I., Tanabe, S., Kohda, A. & Sugiyama, H. (1990) J. Physiol. (London) 424, 533-544]. We have used patch clamp recording techniques in hippocampal slices to elucidate the mechanism for this selective action. We find that aniracetam enhances glutamate-evoked currents in whole-cell recordings and, in ...

  20. New caged neurotransmitter analogs selective for glutamate receptor sub-types based on methoxynitroindoline and nitrophenylethoxycarbonyl caging groups

    Czech Academy of Sciences Publication Activity Database

    Palma-Cerda, F.; Auger, C.; Crawford, D.J.; Hodgson, A.C.C.; Reynolds, S.J.; Cowell, J.K.; Swift, K.A.D.; Cais, Ondřej; Vyklický ml., Ladislav; Corrie, J.E.T.; Ogden, D.

    2012-01-01

    Roč. 63, č. 4 (2012), s. 624-634 ISSN 0028-3908 R&D Projects: GA ČR(CZ) GA309/07/0271 Grant - others:EC(XE) LSHM-CT-2007-037765 Institutional research plan: CEZ:AV0Z50110509 Keywords : photolysis * glutamate receptors * caged neurotransmitters Subject RIV: ED - Physiology Impact factor: 4.114, year: 2012

  1. Activation of metabotropic glutamate receptor 3 enhances interleukin (IL)-1beta-stimulated release of IL-6 in cultured human astrocytes

    NARCIS (Netherlands)

    Aronica, E.; Gorter, J. A.; Rozemuller, A. J.; Yankaya, B.; Troost, D.

    2005-01-01

    Previous studies have demonstrated that human astrocytes express mRNA and receptor protein for group I and II metabotropic glutamate receptors (mGluRs). Whether these receptors can influence the inflammatory and immune response and can modulate the capacity of astrocytes to produce inflammatory

  2. 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.

  3. Metabotropic glutamate receptor 5 (mGluR5 regulates bladder nociception

    Directory of Open Access Journals (Sweden)

    Crock Lara W

    2012-03-01

    Full Text Available Abstract Background Interstitial cystitis/painful bladder syndrome (IC/PBS, is a severely debilitating chronic condition that is frequently unresponsive to conventional pain medications. The etiology is unknown, however evidence suggests that nervous system sensitization contributes to enhanced pain in IC/PBS. In particular, central nervous system plasticity of glutamatergic signaling involving NMDA and metabotropic glutamate receptors (mGluRs has been implicated in a variety of chronic pain conditions. Here, we test the hypothesis that mGluR5 mediates both non-inflammatory and inflammatory bladder pain or nociception in a mouse model by monitoring the visceromotor response (VMR during graded bladder distention. Results Using a combination of genetic and pharmacologic approaches, we provide evidence indicating that mGluR5 is necessary for the full expression of VMR in response to bladder distention in the absence of inflammation. Furthermore, we observed that mice infected with a uropathogenic strain of Escherichia coli (UPEC develop inflammatory hyperalgesia to bladder distention, and that the selective mGluR5 antagonist fenobam [N-(3-chlorophenyl-N'-(4,5-dihydro-1-methyl-4-oxo-1H-imidazole-2-yl urea], reduces the VMR to bladder distention in UPEC-infected mice. Conclusions Taken together, these data suggest that mGluR5 modulates both inflammatory and non-inflammatory bladder nociception, and highlight the therapeutic potential for mGluR5 antagonists in the alleviation of bladder pain.

  4. Mechanism-Based Mathematical Model for Gating of Ionotropic Glutamate Receptors.

    Science.gov (United States)

    Dai, Jian; Wollmuth, Lonnie P; Zhou, Huan-Xiang

    2015-08-27

    We present a mathematical model for ionotropic glutamate receptors (iGluR's) that is built on mechanistic understanding and yields a number of thermodynamic and kinetic properties of channel gating. iGluR's are ligand-gated ion channels responsible for the vast majority of fast excitatory neurotransmission in the central nervous system. The effects of agonist-induced closure of the ligand-binding domain (LBD) are transmitted to the transmembrane channel (TMC) via interdomain linkers. Our model demonstrates that, relative to full agonists, partial agonists may reduce either the degree of LBD closure or the curvature of the LBD free energy basin, leading to less stabilization of the channel open state and hence lower channel open probability. A rigorous relation is derived between the channel closed-to-open free energy difference and the tension within the linker. Finally, by treating LBD closure and TMC opening as diffusive motions, we obtain gating trajectories that resemble stochastic current traces from single-channel recordings and calculate the rate constants for transitions between the channel open and closed states. Our model can be implemented by molecular dynamics simulations to realistically depict iGluR gating and may guide functional experiments in gaining deeper insight into this essential family of channel proteins.

  5. Characteristics of gait ataxia in δ2 glutamate receptor mutant mice, ho15J.

    Directory of Open Access Journals (Sweden)

    Eri Takeuchi

    Full Text Available The cerebellum plays a fundamental, but as yet poorly understood, role in the control of locomotion. Recently, mice with gene mutations or knockouts have been used to investigate various aspects of cerebellar function with regard to locomotion. Although many of the mutant mice exhibit severe gait ataxia, kinematic analyses of limb movements have been performed in only a few cases. Here, we investigated locomotion in ho15J mice that have a mutation of the δ2 glutamate receptor. The cerebellum of ho15J mice shows a severe reduction in the number of parallel fiber-Purkinje synapses compared with wild-type mice. Analysis of hindlimb kinematics during treadmill locomotion showed abnormal hindlimb movements characterized by excessive toe elevation during the swing phase, and by severe hyperflexion of the ankles in ho15J mice. The great trochanter heights in ho15J mice were lower than in wild-type mice throughout the step cycle. However, there were no significant differences in various temporal parameters between ho15J and wild-type mice. We suggest that dysfunction of the cerebellar neuronal circuits underlies the observed characteristic kinematic abnormality of hindlimb movements during locomotion of ho15J mice.

  6. Cloning and Characterization of Glutamate Receptors in Californian Sea Lions (Zalophus californianus

    Directory of Open Access Journals (Sweden)

    Santokh Gill

    2010-05-01

    Full Text Available Domoic acid produced by marine algae has been shown to cause acute and chronic neurologic sequelae in Californian sea lions following acute or low-dose exposure. Histological findings in affected animals included a degenerative cardiomyopathy that was hypothesized to be caused by over-excitation of the glutamate receptors (GluRs speculated to be present in the sea lion heart. Thus tissues from five sea lions without lesions associated with domoic acid toxicity and one animal with domoic acid-induced chronic neurologic sequelae and degenerative cardiomyopathy were examined for the presence of GluRs. Immunohistochemistry localized mGluR 2/3, mGluR 5, GluR 2/3 and NMDAR 1 in structures of the conducting system and blood vessels. NMDAR 1 and GluR 2/3 were the most widespread as immunoreactivity was observed within sea lion conducting system structures. PCR analysis, cloning and subsequent sequencing of the seal lion GluRs showed only 80% homology to those from rats, but more than 95% homologous to those from dogs. The cellular distribution and expression of subtypes of GluRs in the sea lion hearts suggests that exposure to domoic acid may induce cardiac damage and functional disturbances.

  7. The metabotropic glutamate receptor subtype 5 mediates sensitivity to the sedative properties of ethanol.

    Science.gov (United States)

    Downing, Chris; Marks, Michael J; Larson, Colin; Johnson, Thomas E

    2010-09-01

    Inbred long-sleep and short-sleep mice (ILS and ISS) were selectively bred for differential sensitivity to the sedative effects of ethanol. Lines of mice derived from these progenitors have been used to identify several quantitative trait loci (QTLs) mediating loss of the righting reflex due to ethanol (LORE). This study investigated the metabotropic glutamate receptor subtype 5 (mGluR5) as a candidate gene underlying Lore7, a QTL mediating differential LORE sensitivity. We used knockout mice, a quantitative complementation test, pharmacological antagonism of mGluR5, real-time quantitative PCR, radioligand binding, DNA sequencing, and bioinformatics to examine the role of mGluR5 in ethanol-induced sedation. mGluR5 knockout mice had a significantly longer LORE duration than wildtype controls. Administration of the mGluR5 antagonist 2-methyl-6-(phenylethyl)-pyridine (MPEP) had differential effects on LORE in ILS and ISS mice. A quantitative complementation test also supported mGluR5 mediating LORE. Two intronic single-nucleotide polymorphisms in mGluR5 were highly correlated with LORE in recombinant inbred mice derived from a cross between ILS and ISS (LXS RIs). Differences in mGluR5 mRNA level and receptor density were observed between ILS and ISS in distinct brain regions. Finally, data from WebQTL showed that mGluR5 expression was highly correlated with several LORE phenotypes in the LXS RIs. Altogether, this data provides convincing evidence that mGluR5 mediates differential sensitivity to the sedative effects of ethanol. Studies from the human literature have also identified mGluR5 as a potential candidate gene for ethanol sensitivity.

  8. Metabotropic glutamate receptor 5 as a potential target for smoking cessation.

    Science.gov (United States)

    Chiamulera, Cristiano; Marzo, Claudio Marcello; Balfour, David J K

    2017-05-01

    Most habitual smokers find it difficult to quit smoking because they are dependent upon the nicotine present in tobacco smoke. Tobacco dependence is commonly treated pharmacologically using nicotine replacement therapy or drugs, such as varenicline, that target the nicotinic receptor. Relapse rates, however, remain high, and there remains a need to develop novel non-nicotinic pharmacotherapies for the dependence that are more effective than existing treatments. The purpose of this paper is to review the evidence from preclinical and clinical studies that drugs that antagonise the metabotropic glutamate receptor 5 (mGluR5) in the brain are likely to be efficacious as treatments for tobacco dependence. Imaging studies reveal that chronic exposure to tobacco smoke reduces the density of mGluR5s in human brain. Preclinical results demonstrate that negative allosteric modulators (NAMs) at mGluR5 attenuate both nicotine self-administration and the reinstatement of responding evoked by exposure to conditioned cues paired with nicotine delivery. They also attenuate the effects of nicotine on brain dopamine pathways implicated in addiction. Although mGluR5 NAMs attenuate most of the key facets of nicotine dependence, they potentiate the symptoms of nicotine withdrawal. This may limit their value as smoking cessation aids. The NAMs that have been employed most widely in preclinical studies of nicotine dependence have too many "off-target" effects to be used clinically. However, newer mGluR5 NAMs have been developed for clinical use in other indications. Future studies will determine if these agents can also be used effectively and safely to treat tobacco dependence.

  9. Group II metabotropic glutamate receptors as targets for novel antipsychotic drugs

    Directory of Open Access Journals (Sweden)

    Carolina eMuguruza

    2016-05-01

    Full Text Available Schizophrenia is a chronic psychiatric disorder which substantially impairs patients’ quality of life. Despite the extensive research in this field, the pathophysiology and aetiology of schizophrenia remain unknown. Different neurotransmitter systems and functional networks have been found to be affected in the brain of patients with schizophrenia. In this context, postmortem brain studies as well as genetic assays have suggested alterations in Group II metabotropic glutamate receptors (mGluRs in schizophrenia.Despite many years of drug research, several needs in the treatment of schizophrenia have not been addressed sufficiently. In fact, only 5-10% of patients with schizophrenia successfully achieve a full recovery after treatment. In recent years mGluRs have turned up as novel targets for the design of new antipsychotic medications for schizophrenia. Concretely, Group II mGluRs are of particular interest due to their regulatory role in neurotransmission modulating glutamatergic activity in brain synapses. Preclinical studies have demonstrated that orthosteric Group II mGluR agonists exhibit antipsychotic-like properties in animal models of schizophrenia. However, when these compounds have been tested in human clinical studies with schizophrenic patients results have been inconclusive. Nevertheless, it has been recently suggested that this apparent lack of efficacy in schizophrenic patients may be related to previous exposure to atypical antipsychotics. Moreover, the role of the functional heterocomplex formed by 5-HT2A and mGlu2 receptors in the clinical response to Group II mGluR agonists is currently under study.

  10. Monosodium glutamate intake affect the function of the kidney through NMDA receptor.

    Science.gov (United States)

    Mahieu, Stella; Klug, Maximiliano; Millen, Néstor; Fabro, Ana; Benmelej, Adriana; Contini, Maria Del Carmen

    2016-03-15

    We investigated whether the chronic intake of monosodium glutamate (MSG) with food affects kidney function, and renal response to glycine. We also established if the NMDA receptors are involved in the changes observed. Male Wistar rats (5weeks old) were fed a diet supplemented with MSG (3g/kg b.w./day), five days a week, and spontaneous ingestion of a 1% MSG solution during 16weeks. NaCl rats were fed a diet with NaCl (1g/kg b.w./day) and 0.35% NaCl solution at the same frequency and time. Control group was fed with normal chow and tap water. We utilized clearance techniques to examine glomerular filtration rate (GFR) and cortical renal plasma flow (CRPF) response to glycine and glycine+MK-801 (antagonist NMDA-R), and we determined NMDA-R1 in kidney by immunohistochemistry. The addition of MSG in the diet of rats increased both GFR and CRPF with an increase of absolute sodium reabsorption. However, hyperfiltration was accompanied with a normal response to glycine infusion. Immunostain of kidney demonstrate that the NMDA receptor is upregulated in rats fed with MSG diet. NMDA-R antagonist MK-801 significantly reduced both the GFR and CRPF; however the percentage of reduction was significantly higher in the group MSG. MK-801 also reduces fractional excretion of water, sodium and potassium in the three groups. Renal NMDAR may be conditioned by the addition of MSG in the diet, favoring the hyperfiltration and simultaneously Na retention in the body. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Antipsychotic profiles of TASP0443294, a novel and orally active positive allosteric modulator of metabotropic glutamate 2 receptor

    Directory of Open Access Journals (Sweden)

    Hirohiko Hikichi

    2015-03-01

    Full Text Available Glutamatergic dysfunction has been implicated in psychiatric disorders such as schizophrenia. The stimulation of metabotropic glutamate (mGlu 2 receptor has been shown to be effective in a number of animal models of schizophrenia. In this study, we investigated the antipsychotic profiles of (2S-5-methyl-2-{[4-(1,1,1-trifluoro-2-methylpropan-2-ylphenoxy]methyl}-2,3-dihydroimidazo[2,1-b][1,3]oxazole-6-carboxamide (TASP0443294, a newly synthesized positive allosteric modulator of the mGlu2 receptor. TASP0443294 potentiated the response of human mGlu2 and rat mGlu2 receptors to glutamate with EC50 values of 277 and 149 nM, respectively, without affecting the glutamate response of human mGlu3 receptor. TASP0443294 was distributed in the brain and cerebrospinal fluid after peroral administration in rats. The peroral administration of TASP0443294 inhibited methamphetamine-induced hyperlocomotion in rats, which was attenuated by an mGlu2/3 receptor antagonist, and improved social memory impairment induced by 5R,10S-(+-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801 in rats. Furthermore, TASP0443294 reduced the ketamine-induced basal gamma hyperactivity in the prefrontal cortex and suppressed rapid eye movement (REM sleep in rats. These findings indicate that TASP0443294 is an mGlu2 receptor positive allosteric modulator with antipsychotic activity, and that the suppression of aberrant gamma oscillations and REM sleep could be considered as neurophysiological biomarkers for TASP0443294.

  12. Ketamine and ketamine metabolites as novel estrogen receptor ligands: Induction of cytochrome P450 and AMPA glutamate receptor gene expression.

    Science.gov (United States)

    Ho, Ming-Fen; Correia, Cristina; Ingle, James N; Kaddurah-Daouk, Rima; Wang, Liewei; Kaufmann, Scott H; Weinshilboum, Richard M

    2018-04-03

    Major depressive disorder (MDD) is the most common psychiatric illness worldwide, and it displays a striking sex-dependent difference in incidence, with two thirds of MDD patients being women. Ketamine treatment can produce rapid antidepressant effects in MDD patients, effects that are mediated-at least partially-through glutamatergic neurotransmission. Two active metabolites of ketamine, (2R,6R)-hydroxynorketamine (HNK) and (2S,6S)-HNK, also appear to play a key role in ketamine's rapid antidepressant effects through the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors. In the present study, we demonstrated that estrogen plus ketamine or estrogen plus active ketamine metabolites displayed additive effects on the induction of the expression of AMPA receptor subunits. In parallel, the expression of estrogen receptor alpha (ERα) was also significantly upregulated. Even more striking, radioligand binding assays demonstrated that [ 3 H]-ketamine can directly bind to ERα (K D : 344.5 ± 13 nM). Furthermore, ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites displayed similar affinity for ERα (IC 50 : 2.31 ± 0.1, 3.40 ± 0.2, and 3.53 ± 0.2 µM, respectively) as determined by [ 3 H]-ketamine displacement assays. Finally, induction of AMPA receptors by either estrogens or ketamine and its metabolites was lost when ERα was knocked down or silenced pharmacologically. These results suggest a positive feedback loop by which estrogens can augment the effects of ketamine and its (2R,6R)-HNK and (2S,6S)-HNK metabolites on the ERα-induced transcription of CYP2A6 and CYP2B6, estrogen inducible enzymes that catalyze ketamine's biotransformation to form the two active metabolites. These observations provide novel insight into ketamine's molecular mechanism(s) of action and have potential implications for the treatment of MDD. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. TiO2 nanoparticle-induced neurotoxicity may be involved in dysfunction of glutamate metabolism and its receptor expression in mice.

    Science.gov (United States)

    Ze, Xiao; Su, Mingyu; Zhao, Xiaoyang; Jiang, Hao; Hong, Jie; Yu, Xiaohong; Liu, Dong; Xu, Bingqing; Sheng, Lei; Zhou, Qiuping; Zhou, Junling; Cui, Jingwen; Li, Kai; Wang, Ling; Ze, Yuguan; Hong, Fashui

    2016-06-01

    Titanium dioxide nanoparticles (TiO2 NPs) have been used in environmental management, food, medicine, and industry. But TiO2 NPs have been demonstrated to cross the blood-brain barrier and store up in the brain organization, leading to glutamate-mediated neurotoxicity. However, the neurotoxicity in the brain is not well understood. In this study, mice were exposed to 1.25, 2.5, or 5 mg/kg body weight TiO2 NPs for 9 months, and the glutamate-glutamine cyclic pathway and expressions of glutamate receptors associated with the hippocampal neurotoxicity were investigated. Our findings showed elevations of glutamate release and phosphate-activated glutaminase activity, and reductions in glutamine and glutamine synthetase in the hippocampus following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly inhibited the expression of N-methyl-d-aspartate receptor subunits (including NR1, NR2A, and NR2B) and metabotropic glutamate receptor 2 in mouse hippocampus. These findings suggest that the imbalance of glutamate metabolism triggered inhibitions of glutamate receptor expression in the TiO2 NP-exposed hippocampus. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 655-662, 2016. © 2014 Wiley Periodicals, Inc.

  14. Effects of LY354740, a selective agonist of Glutamate metabotropic group II receptors, on aggressive behavior in mice

    OpenAIRE

    De Castro, Vanessa; Universidad de Málaga; Martín-López, Mercedes; Universidad de Málaga; Navarro, José Francisco; Universidad de Málaga

    2010-01-01

    Recent studies have demonstrated that glutamate metabotropic receptors mGlu1 and mGlu5 are involved in the regulation of aggressive behaviour. This study examines the effect of the administration of LY354740 (4-16 mg/kg i.p.), a selective group II metabotropic receptors agonist (mGlu2/3), using an isolation-induced aggression model. Individually housed mice were exposed to anosmic opponents 30 min after drug administration. Ten min of diadic interactions were staged between a singly housed an...

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    ]Arachidonic acid release induced by both sPLA and glutamate was partially blocked by MK-801, indicating that the glutamate-NMDA-cPLA pathway contributes to sPLA -induced arachidonic acid release. Systemic administration of MK-801 to rats that had sPLA injected into the right striatum significantly decreased...

  16. Modulation of PTZ induced seizures by Citrus aurantium in zebrafish: role of NMDA and metabotropic glutamate receptors.

    Directory of Open Access Journals (Sweden)

    Coral eRosa-Falero

    2015-02-01

    Full Text Available Citrus aurantium (CA, commonly known as bitter orange, is used in folk medicine to treat anxiety and insomnia. Studies performed with Essential oils from the peel of the fruit have shown to increase seizure latency to pentylenetetrazole (PTZ and maximal electroshock seizure in animal models. With these experiments, we assessed a possible role of an aqueous extract from the leaf of the Citrus aurantium tree. Anticonvulsant properties of C. aurantium extracts were tested using adult zebrafish (Danio rerio. Zebrafish exposed to C. aurantium 28 mg/ml showed a 119 % increase on seizure latency compared to controls. We evaluated GABAA and glutamate receptors as mediators of this increase in seizure latency. We used the selective antagonist gabazine to rule out GABAA receptors as targets for the C. aurantium extract. With glutamate receptors, we used two approaches, an In vitro ligand binding assay and the In vitro model of PTZ induced seizures in zebrafish combined with selective receptor antagonists. The ligand binding assay revealed C. aurantium extracts at concentrations of 0.42mg/ml to 5.6mg/ml significantly reduced [3H]Glu binding and this interaction showed to be selective for iGluR and mGluR group II and III. This pattern of interactions was evaluated In vivo pretreating zebrafish with glutamate receptor antagonists and we confirmed NMDA and mGluR’s I and II are involved with the mechanism of C. aurantium extract. These study results support the relevance of natural products as feasible alternatives for drug development providing evidence of effectiveness and possible mechanism of action for the extract.

  17. Intracellular metabotropic glutamate receptor 5 (mGluR5) activates signaling cascades distinct from cell surface counterparts.

    Science.gov (United States)

    Jong, Yuh-Jiin I; Kumar, Vikas; O'Malley, Karen L

    2009-12-18

    G-protein-coupled receptors are thought to transmit extracellular signals to the cytoplasm from their position on the cell surface. Some receptors, including the metabotropic glutamate receptor 5 (mGluR5), are also highly expressed on intracellular membranes where they serve unknown functions. Here, we show that activation of cell surface versus intracellular mGluR5 results in unique Ca(2+) signatures leading to unique cellular responses. Specifically, activation of either cell surface or intracellular mGluR5 leads to JNK, Ca(2+)/calmodulin-dependent protein kinase (CaMK), and cyclic adenosine 3',5'-monophosphate-responsive element-binding protein phosphorylation, whereas activation of only intracellular mGluR5 leads to ERK1/2 and Elk-1 phosphorylation. Using pharmacological and genetic approaches, the present findings support a role for CaMK kinase in mediating mGluR5-dependent cyclic adenosine 3',5'-monophosphate-responsive element-binding protein phosphorylation, whereas CaMKII is upstream of intracellular mGluR5-mediated Elk-1 phosphorylation. Consistent with models showing Elk-1 regulating cascades of gene expression, the known Elk-1 targets c-fos and egr1 were up-regulated following intracellular mGluR5 activation, whereas a representative non-Elk-1 target, c-jun, was not. These findings emphasize that glutamate not only serves as a neurotransmitter for cell surface receptors but, when transported into the cell, can also activate intracellular receptors such as mGluR5. Glutamate activation of intracellular mGluR5 serves an important role in the regulation of nuclear Ca(2+), transcriptional activation, and gene expression necessary for physiological processes such as synaptic plasticity.

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

    Directory of Open Access Journals (Sweden)

    Afifah Abd Jalil

    2017-01-01

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

  19. Negative Allosteric Modulators of Metabotropic Glutamate Receptors Subtype 5 in Addiction: a Therapeutic Window

    Science.gov (United States)

    2016-01-01

    Background: Abundant evidence at the anatomical, electrophysiological, and molecular levels implicates metabotropic glutamate receptor subtype 5 (mGluR5) in addiction. Consistently, the effects of a wide range of doses of different mGluR5 negative allosteric modulators (NAMs) have been tested in various animal models of addiction. Here, these studies were subjected to a systematic review to find out if mGluR5 NAMs have a therapeutic potential that can be translated to the clinic. Methods: Literature on consumption/self-administration and reinstatement of drug seeking as outcomes of interest published up to April 2015 was retrieved via PubMed. The review focused on the effects of systemic (i.p., i.v., s.c.) administration of the mGluR5 NAMs 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) and 2-Methyl-6-(phenylethynyl)pyridine (MPEP) on paradigms with cocaine, ethanol, nicotine, and food in rats. Results: MTEP and MPEP were found to reduce self-administration of cocaine, ethanol, and nicotine at doses ≥1mg/kg and 2.5mg/kg, respectively. Dose-response relationship resembled a sigmoidal curve, with low doses not reaching statistical significance and high doses reliably inhibiting self-administration of drugs of abuse. Importantly, self-administration of cocaine, ethanol, and nicotine, but not food, was reduced by MTEP and MPEP in the dose range of 1 to 2mg/kg and 2.5 to 3.2mg/kg, respectively. This dose range corresponds to approximately 50% to 80% mGluR5 occupancy. Interestingly, the limited data found in mice and monkeys showed a similar therapeutic window. Conclusion: Altogether, this review suggests a therapeutic window for mGluR5 NAMs that can be translated to the treatment of substance-related and addictive disorders. PMID:26802568

  20. Blocking metabotropic glutamate receptor subtype 5 relieves maladaptive chronic stress consequences.

    Science.gov (United States)

    Peterlik, Daniel; Stangl, Christina; Bauer, Amelie; Bludau, Anna; Keller, Jana; Grabski, Dominik; Killian, Tobias; Schmidt, Dominic; Zajicek, Franziska; Jaeschke, Georg; Lindemann, Lothar; Reber, Stefan O; Flor, Peter J; Uschold-Schmidt, Nicole

    2017-01-01

    Etiology and pharmacotherapy of stress-related psychiatric conditions and somatoform disorders are areas of high unmet medical need. Stressors holding chronic plus psychosocial components thereby bear the highest health risk. Although the metabotropic glutamate receptor subtype 5 (mGlu5) is well studied in the context of acute stress-induced behaviors and physiology, virtually nothing is known about its potential involvement in chronic psychosocial stress. Using the mGlu5 negative allosteric modulator CTEP (2-chloro-4-[2-[2,5-dimethyl-1-[4-(trifluoromethoxy)phenyl]imidazol-4yl]ethynyl]pyridine), a close analogue of the clinically active drug basimglurant - but optimized for rodent studies, as well as mGlu5-deficient mice in combination with a mouse model of male subordination (termed CSC, chronic subordinate colony housing), we demonstrate that mGlu5 mediates multiple physiological, immunological, and behavioral consequences of chronic psychosocial stressor exposure. For instance, CTEP dose-dependently relieved hypothalamo-pituitary-adrenal axis dysfunctions, colonic inflammation as well as the CSC-induced increase in innate anxiety; genetic ablation of mGlu5 in mice largely reproduced the stress-protective effects of CTEP and additionally ameliorated CSC-induced physiological anxiety. Interestingly, CSC also induced an upregulation of mGlu5 in the hippocampus, a stress-regulating brain area. Taken together, our findings provide evidence that mGlu5 is an important mediator for a wide range of chronic psychosocial stress-induced alterations and a potentially valuable drug target for the treatment of chronic stress-related pathologies in man. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Metabotrobic Glutamate Receptor mGluR4 as a Novel Target for Parkinson's Disease

    National Research Council Canada - National Science Library

    Levey, Alan

    2000-01-01

    ...) as a novel target for the treatment of PD. We have localized mGluP4 in basal ganglia structures, and explored its role in mediating the electrophysiological effects of glutamate in rat brain slices...

  2. Metabotropic Glutamate Receptor mGluR4 as a Novel Target for Parkinson's Disease

    National Research Council Canada - National Science Library

    Levey, Allan

    2001-01-01

    ...) as a novel target for the treatment of PD. We have localized mGluR4 in basal ganglia structures, and explored its role in mediating the electrophysiological effects of glutamate in rat brain slices...

  3. Metabotrobic Glutamate Receptor mGluR4 as a Novel Target for Parkinson's Disease

    National Research Council Canada - National Science Library

    Levy, Allan

    1999-01-01

    .... other subtypes in mediating the electrophysiological effects of glutamate in rat brain slices, and to determine the efficacy of drugs aimed mGluRs in relieving motor symptoms in hemi-parkinsonian monkeys...

  4. Nicotinic receptor activation contrasts pathophysiological bursting and neurodegeneration evoked by glutamate uptake block on rat hypoglossal motoneurons.

    Science.gov (United States)

    Corsini, Silvia; Tortora, Maria; Nistri, Andrea

    2016-11-15

    Impaired uptake of glutamate builds up the extracellular level of this excitatory transmitter to trigger rhythmic neuronal bursting and delayed cell death in the brainstem motor nucleus hypoglossus. This process is the expression of the excitotoxicity that underlies motoneuron degeneration in diseases such as amyotrophic lateral sclerosis affecting bulbar motoneurons. In a model of motoneuron excitotoxicity produced by pharmacological block of glutamate uptake in vitro, rhythmic bursting is suppressed by activation of neuronal nicotinic receptors with their conventional agonist nicotine. Emergence of bursting is facilitated by nicotinic receptor antagonists. Following excitotoxicity, nicotinic receptor activity decreases mitochondrial energy dysfunction, endoplasmic reticulum stress and production of toxic radicals. Globally, these phenomena synergize to provide motoneuron protection. Nicotinic receptors may represent a novel target to contrast pathological overactivity of brainstem motoneurons and therefore to prevent their metabolic distress and death. Excitotoxicity is thought to be one of the early processes in the onset of amyotrophic lateral sclerosis (ALS) because high levels of glutamate have been detected in the cerebrospinal fluid of such patients due to dysfunctional uptake of this transmitter that gradually damages brainstem and spinal motoneurons. To explore potential mechanisms to arrest ALS onset, we used an established in vitro model of rat brainstem slice preparation in which excitotoxicity is induced by the glutamate uptake blocker dl-threo-β-benzyloxyaspartate (TBOA). Because certain brain neurons may be neuroprotected via activation of nicotinic acetylcholine receptors (nAChRs) by nicotine, we investigated if nicotine could arrest excitotoxic damage to highly ALS-vulnerable hypoglossal motoneurons (HMs). On 50% of patch-clamped HMs, TBOA induced intense network bursts that were inhibited by 1-10 μm nicotine, whereas nAChR antagonists

  5. Nicotinic receptor activation contrasts pathophysiological bursting and neurodegeneration evoked by glutamate uptake block on rat hypoglossal motoneurons

    Science.gov (United States)

    Corsini, Silvia; Tortora, Maria

    2016-01-01

    Key points Impaired uptake of glutamate builds up the extracellular level of this excitatory transmitter to trigger rhythmic neuronal bursting and delayed cell death in the brainstem motor nucleus hypoglossus.This process is the expression of the excitotoxicity that underlies motoneuron degeneration in diseases such as amyotrophic lateral sclerosis affecting bulbar motoneurons.In a model of motoneuron excitotoxicity produced by pharmacological block of glutamate uptake in vitro, rhythmic bursting is suppressed by activation of neuronal nicotinic receptors with their conventional agonist nicotine. Emergence of bursting is facilitated by nicotinic receptor antagonists.Following excitotoxicity, nicotinic receptor activity decreases mitochondrial energy dysfunction, endoplasmic reticulum stress and production of toxic radicals. Globally, these phenomena synergize to provide motoneuron protection.Nicotinic receptors may represent a novel target to contrast pathological overactivity of brainstem motoneurons and therefore to prevent their metabolic distress and death. Abstract Excitotoxicity is thought to be one of the early processes in the onset of amyotrophic lateral sclerosis (ALS) because high levels of glutamate have been detected in the cerebrospinal fluid of such patients due to dysfunctional uptake of this transmitter that gradually damages brainstem and spinal motoneurons. To explore potential mechanisms to arrest ALS onset, we used an established in vitro model of rat brainstem slice preparation in which excitotoxicity is induced by the glutamate uptake blocker dl‐threo‐β‐benzyloxyaspartate (TBOA). Because certain brain neurons may be neuroprotected via activation of nicotinic acetylcholine receptors (nAChRs) by nicotine, we investigated if nicotine could arrest excitotoxic damage to highly ALS‐vulnerable hypoglossal motoneurons (HMs). On 50% of patch‐clamped HMs, TBOA induced intense network bursts that were inhibited by 1–10 μm nicotine

  6. Involvement of medial septal glutamate and GABA(A) receptors in behaviour-induced acetylcholine release in the hippocampus : A dual probe microdialysis study

    NARCIS (Netherlands)

    Moor, E; Schirm, E; Jacso, J; Westerink, BHC

    1998-01-01

    In the present study, the role of medial septal receptors in behaviour-induced increase in acetylcholine (ACh) release in hippocampus was investigated using dual-probe microdialysis in combination with a simple behavioural procedure, gamma-Aminobutyric acid (GABA) and glutamate receptor agonists and

  7. 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...

  8. 4-hydroxy-1,2,5-oxadiazol-3-yl moiety as bioisoster of the carboxy function. Synthesis, ionization constants, and molecular pharmacological characterization at ionotropic glutamate receptors of compounds related to glutamate and its homologues

    DEFF Research Database (Denmark)

    Lolli, Marco L; Giordano, Cecilia; Pickering, Darryl S

    2010-01-01

    In order to investigate the 4-hydroxy-1,2,5-oxadiazol-3-yl moiety as a carboxylic acid bioisoster at ionotropic glutamate receptors (iGluRs), a series of acidic alpha-aminocarboxylic acids in which the distal carboxy group was replaced by the 4-hydroxy-1,2,5-oxadiazol-3-yl group was synthesized...

  9. Type-1, but Not Type-5, Metabotropic Glutamate Receptors are Coupled to Polyphosphoinositide Hydrolysis in the Retina.

    Science.gov (United States)

    Romano, Maria Rosaria; Di Menna, Luisa; Scarselli, Pamela; Mascio, Giada; Madonna, Michele; Notartomaso, Serena; Puliti, Aldamaria; Bruno, Valeria; Battaglia, Giuseppe; Nicoletti, Ferdinando

    2016-04-01

    mGlu1 and mGlu5 metabotropic glutamate receptors are expressed in the vertebrate retina, and are co-localized in some retinal neurons. It is believed that both receptors are coupled to polyphosphoinositide (PI) hydrolysis in the retina and their function may diverge in some cells because of a differential engagement of downstream signaling molecules. Here, we show that it is only the mGlu1 receptor that is coupled to PI hydrolysis in the retina. We used either bovine retinal slices or intact mouse retinas challenged with the mixed mGlu1/5 receptor agonist, DHPG. In both models, DHPG-stimulated PI hydrolysis was abrogated by the selective mGlu1 receptor antagonist, JNJ16259685, but was insensitive to the mGlu5 receptor antagonist, MPEP. In addition, the PI response to DHPG was unchanged in the retina of mGlu5(-/-) mice but was abolished in the retina of crv4 mice lacking mGlu1 receptors. Stimulation of the mitogen-activated protein kinase pathway by DHPG in intact mouse retinas were also entirely mediated by mGlu1 receptors. Our data provide the first example of a tissue in which a biochemically detectable PI response is mediated by mGlu1, but not mGlu5, receptors. Hence, bovine retinal slices might be used as a model for the functional screening of mGlu1 receptor ligands. In addition, the mGlu1 receptor caters the potential as a drug target in the experimental treatment of degenerative disorders of the retina.

  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. Effects of cannabinoid and glutamate receptor antagonists and their interactions on learning and memory in male rats.

    Science.gov (United States)

    Barzegar, Somayeh; Komaki, Alireza; Shahidi, Siamak; Sarihi, Abdolrahman; Mirazi, Naser; Salehi, Iraj

    2015-04-01

    Despite previous findings on the effects of cannabinoid and glutamatergic systems on learning and memory, the effects of the combined stimulation or the simultaneous inactivation of these two systems on learning and memory have not been studied. In addition, it is not clear whether the effects of the cannabinoid system on learning and memory occur through the modulation of glutamatergic synaptic transmission. Hence, in this study, we examined the effects of the simultaneous inactivation of the cannabinoid and glutamatergic systems on learning and memory using a passive avoidance (PA) test in rats. On the test day, AM251, which is a CB1 cannabinoid receptor antagonist; MK-801, which is a glutamate receptor antagonist; or both substances were injected intraperitoneally into male Wistar rats 30min before placing the animal in a shuttle box. A learning test (acquisition) was then performed, and a retrieval test was performed the following day. Learning and memory in the PA test were significantly different among the groups. The CB1 receptor antagonist improved the scores on the PA acquisition and retention tests. However, the glutamatergic receptor antagonist decreased the acquisition and retrieval scores on the PA task. The CB1 receptor antagonist partly decreased the glutamatergic receptor antagonist effects on PA learning and memory. These results indicated that the acute administration of a CB1 antagonist improved cognitive performance on a PA task in normal rats and that a glutamate-related mechanism may underlie the antagonism of cannabinoid by AM251 in learning and memory. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Purification of the active C5a receptor from human polymorphonuclear leukocytes as a receptor - G sub i complex

    Energy Technology Data Exchange (ETDEWEB)

    Rollins, T.E.; Siciliano, S.; Kobayashi, S.; Cianciarulo, D.N.; Bonilla-Argudo, V.; Collier, K.; Springer, M.S. (Merck Sharp and Dohme Research Lab., Rahway, NJ (United States))

    1991-02-01

    The authors have isolated, in an active state, the C5a receptor from human polymorphonuclear leukocytes. The purification was achieved in a single step using a C5a affinity column in which the C5a molecule was coupled to the resin through its N terminus. The purified receptor, like the crude solubilized molecule, exhibited a single class of high-affinity binding sites with a K{sub d} of 30 pM. Further, the binding of C5a retained its sensitivity to guanine nucleotides, implying that the purified receptor contained a guanine nucleotide-binding protein (G protein). SDS/PAGE revealed the presence of three polypeptides with molecular masses of 42, 40, and 36 kDa, which were determined to be the C5a-binding subunit and the {alpha} and {beta} subunits of G{sub i}, respectively. The 36- and 40-kDa polypeptides were identified by immunoblotting and by the ability of pertussis toxin to ADP-ribosylate the 40-kDa molecule. These results confirm their earlier hypothesis that the receptor exists as a complex with a G protein in the presence or absence of C5a. The tight coupling between the receptor and G protein should make possible the identification of the G protein(s) involved in the transduction pathways used by C5a to produce its many biological effects.

  13. Purification of the active C5a receptor from human polymorphonuclear leukocytes as a receptor - Gi complex

    International Nuclear Information System (INIS)

    Rollins, T.E.; Siciliano, S.; Kobayashi, S.; Cianciarulo, D.N.; Bonilla-Argudo, V.; Collier, K.; Springer, M.S.

    1991-01-01

    The authors have isolated, in an active state, the C5a receptor from human polymorphonuclear leukocytes. The purification was achieved in a single step using a C5a affinity column in which the C5a molecule was coupled to the resin through its N terminus. The purified receptor, like the crude solubilized molecule, exhibited a single class of high-affinity binding sites with a K d of 30 pM. Further, the binding of C5a retained its sensitivity to guanine nucleotides, implying that the purified receptor contained a guanine nucleotide-binding protein (G protein). SDS/PAGE revealed the presence of three polypeptides with molecular masses of 42, 40, and 36 kDa, which were determined to be the C5a-binding subunit and the α and β subunits of G i , respectively. The 36- and 40-kDa polypeptides were identified by immunoblotting and by the ability of pertussis toxin to ADP-ribosylate the 40-kDa molecule. These results confirm their earlier hypothesis that the receptor exists as a complex with a G protein in the presence or absence of C5a. The tight coupling between the receptor and G protein should make possible the identification of the G protein(s) involved in the transduction pathways used by C5a to produce its many biological effects

  14. Aniracetam reduces glutamate receptor desensitization and slows the decay of fast excitatory synaptic currents in the hippocampus.

    Science.gov (United States)

    Isaacson, J S; Nicoll, R A

    1991-12-01

    Aniracetam is a nootropic drug that has been shown to selectively enhance quisqualate receptor-mediated responses in Xenopus oocytes injected with brain mRNA and in hippocampal pyramidal cells [Ito, I., Tanabe, S., Kohda, A. & Sugiyama, H. (1990) J. Physiol. (London) 424, 533-544]. We have used patch clamp recording techniques in hippocampal slices to elucidate the mechanism for this selective action. We find that aniracetam enhances glutamate-evoked currents in whole-cell recordings and, in outside-out patches, strongly reduces glutamate receptor desensitization. In addition, aniracetam selectively prolongs the time course and increases the peak amplitude of fast synaptic currents. These findings indicate that aniracetam slows the kinetics of fast synaptic transmission and are consistent with the proposal [Trussell, L. O. & Fischbach, G. D. (1989) Neuron 3, 209-218; Tang, C.-M., Dichter, M. & Morad, M. (1989) Science 243, 1474-1477] that receptor desensitization governs the strength of fast excitatory synaptic transmission in the brain.

  15. 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.

  16. Relief from detrimental consequences of chronic psychosocial stress in mice deficient for the metabotropic glutamate receptor subtype 7.

    Science.gov (United States)

    Peterlik, Daniel; Stangl, Christina; Bludau, Anna; Grabski, Dominik; Strasser, Robert; Schmidt, Dominic; Flor, Peter J; Uschold-Schmidt, Nicole

    2017-03-15

    Chronic stress-related psychiatric conditions and comorbid somatic pathologies are an enormous public health concern in modern society. The etiology of these disorders is complex, with stressors holding a chronic and psychosocial component representing the most acknowledged risk factor. During the last decades, research on the metabotropic glutamate receptor (mGlu) system advanced dramatically and much attention was given to the role of the metabotropic glutamate receptor subtype 7 (mGlu7) in acute stress-related behavior and physiology. However, virtually nothing is known about the potential involvement of mGlu7 in chronic psychosocial stress-related conditions. Using the chronic subordinate colony housing (CSC, 19 days) in male mice, we addressed whether central mGlu7 is altered upon chronic psychosocial stressor exposure and whether genetic ablation of mGlu7 interferes with the multitude of chronic stress-induced alterations. CSC exposure resulted in a downregulation of mGlu7 mRNA transcript levels in the prefrontal cortex, a brain region relevant for stress-related behaviors and physiology. Interestingly, mGlu7 deficiency relieved multiple chronic stress-induced alterations including the CSC-induced anxiety-prone phenotype; mGlu7 ablation also ameliorated CSC-induced physiological and immunological consequences such as hypothalamo-pituitary-adrenal (HPA) axis dysfunctions and colonic inflammation, respectively. Together, our findings provide first evidence for the involvement of mGlu7 in a wide range of behavioral and physiological alterations in response to chronic psychosocial stressor exposure. Moreover, the stress-protective phenotype of genetic mGlu7 ablation suggests mGlu7 pharmacological blockade to be a relevant option for the treatment of chronic stress-related emotional and somatic dysfunctions. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Selective antagonists at group I metabotropic glutamate receptors: synthesis and molecular pharmacology of 4-aryl-3-isoxazolol amino acids

    DEFF Research Database (Denmark)

    Kromann, Hasse; Sløk, Frank A; Stensbøl, Tine B

    2002-01-01

    Homologation of (S)-glutamic acid (Glu, 1) and Glu analogues has previously provided ligands with activity at metabotropic Glu receptors (mGluRs). The homologue of ibotenic acid (7), 2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid (HIBO, 8), and the 4-phenyl derivative of 8, compound 9a, are bot...... antagonists at group I mGluRs. Here we report the synthesis and molecular pharmacology of HIBO analogues 9b-h containing different 4-aryl substituents. All of these compounds possess antagonist activity at group I mGluRs but are inactive at group II and III mGluRs....

  18. Glutamate receptor antagonists and growth factors modulate dentate granule cell neurogenesis in organotypic, rat hippocampal slice cultures

    DEFF Research Database (Denmark)

    Poulsen, Frantz Rom; Blaabjerg, Morten; Montero, Maria

    2005-01-01

    Generation of dentate granule cells and its modulation by glutamate receptor antagonists, growth factors and pilocarpine-induced seizure-like activity was investigated in rat hippocampal slice cultures derived from 1-week-old rats and grown for 2 weeks. Focussing on the dentate granule cell layer...... the number of TUC-4-positive cells, just as combining pilocarpine with the neurogenesis-stimulating compounds, prevented or reduced the increase of TUC-4-positive cells. None of the treatments were found to induce dentate granule cell death within the observed period. Labeling of dividing cells by adding 5...

  19. Metabotropic glutamate receptor 5 activation enhances tyrosine phosphorylation of the N-methyl-D-aspartate (NMDA) receptor and NMDA-induced cell death in hippocampal cultured neurons.

    Science.gov (United States)

    Takagi, Norio; Besshoh, Shintaro; Marunouchi, Tetsuro; Takeo, Satoshi; Tanonaka, Kouichi

    2012-01-01

    The activation of group I metabotropic glutamate receptors (mGluRs), which are coupled with Gq-protein, initiates a variety physiological responses in different types of cells. While Gq-protein-coupled receptors can upregulate N-methyl-D-aspartate (NMDA) receptor function, group I mGluR-mediated regulations of NMDA receptor function are not fully understood. To determine biochemical roles of group I mGluRs in the regulation of the NMDA receptor, we have investigated changes in tyrosine phosphorylation of NMDA receptor subunits NR2A and NR2B induced by a selective mGluR5 agonist, (RS)-chloro-5-hydroxyphenylglycine (CHPG) in hippocampal neuronal cultures. Activation of mGluR5 by CHPG increased active-forms of Src. CHPG also enhanced tyrosine phosphorylation of NR2A and NR2B in hippocampal neuronal cultures. In addition, NMDA-induced cell death was enhanced by CHPG-induced mGluR5 stimulation at the concentration, which increased tyrosine phosphorylation of Src and NR2A/2B but did not induce cell death. This effect was inhibited by selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP). The results suggest that in hippocampal neurons, mGluR5 may regulate NMDA receptor activity, involving tyrosine phosphorylation of NR2A and NR2B and may be involved in NMDA receptor-mediated cell injury.

  20. [Metabotropic glutamate receptor 8 activation promotes the apoptosis of lung carcinoma A549 cells in vitro].

    Science.gov (United States)

    Li, Tian-Jiao; Huang, Yan-Hong; Chen, Xi; Zhou, Zhou; Luo, Si-Wei; Feng, Dan-Dan; Han, Jian-Zhong; Luo, Zi-Qiang

    2015-10-25

    This study aims to detect the expression of metabotropic glutamate receptors (mGluRs) in lung carcinoma A549 cells, and to investigate the effects of mGluR8 and mGluR4 activation on the growth of A549 cells in vitro. The mRNA expression levels of the 8 subtypes of mGluRs in A549 cells were determined by real-time PCR. Immunohistochemistry was used to analyze the protein expression of mGluR4 and mGluR8 in A549 cells and lung tissue sections obtained from lung adenocarcinoma patients. To observe the effects of mGluR8 and mGluR4 activation on the growth of A549 cells, the cultured cells were treated with (S)-3,4-DCPG (an agonist of mGluR8) and VU0155041 (an agonist of mGluR4), respectively, and then the cell viability was analyzed by CCK-8 kit, the percentage of DNA synthesis was detected by EdU incorporation, and the apoptosis of the cells was measured by hoechst 33258 staining and flow cytometry. The results showed that there were low expressions of mGluR1, mGluR5, mGluR6, mGluR7 mRNA, no expression of mGluR2 and mGluR3 mRNA, and high expressions of mGluR8 and mGluR4 mRNA in A549 cells. Accordingly, there were also mGluR4 and mGluR8 protein expressions in the A549 cells and the lung adenocarcinoma tissue sections. VU0155041 had no effect on the growth of A549 cells, but (S)-3,4-DCPG significantly decreased the cells' growth in a dose-dependent manner and increased the apoptosis of the cells. The results revealed a role of mGluR8 in the growth and apoptosis of A549 cells and suggested a potential target for clinical treatment of lung cancer.

  1. Interactions of a Dopamine D1 Receptor Agonist with Glutamate NMDA Receptor Antagonists on the Volitional Consumption of Ethanol by the mHEP Rat

    Directory of Open Access Journals (Sweden)

    Helen L. Williams

    2013-03-01

    Full Text Available Stimulation of the dopamine D1 receptor is reported to cause the phosphorylation of DARPP-32 at the thre34 position and activates the protein. If intracellular Ca2+ is increased, such as after activation of the glutamate NMDA receptor, calcineurin activity increases and the phosphates will be removed. This balance of phosphorylation control suggests that a D1 receptor agonist and a NMDA glutamate receptor antagonist should have additive or synergistic actions to increase activated DARPP-32 and consequent behavioral effects. This hypothesis was tested in a volitional consumption of ethanol model: the selectively bred Myers’ high ethanol preferring (mHEP rat. A 3-day baseline period was followed by 3-days of twice daily injections of drug(s or vehicle(s and then a 3-day post-treatment period. Vehicle, the D1 agonist SKF 38393, the non-competitive NMDA receptor antagonist memantine, or their combination were injected 2 h before and after lights out. The combination of 5.0 mg/kg SKF 38393 with either 3.0 or 10 mg/kg memantine did not produce an additive or synergistic effect. For example, 5.0 mg/kg SKF reduced consumption of ethanol by 27.3% and 10 mg/kg memantine by 39.8%. When combined, consumption declined by 48.2% and the proportion of ethanol solution to total fluids consumed declined by 17%. However, the consumption of food also declined by 36.6%. The latter result indicates that this dose combination had a non-specific effect. The combination of SKF 38393 with (+-MK-801, another NMDA receptor antagonist, also failed to show an additive effect. The lack of additivity and specificity suggests that the hypothesis may not be correct for this in vivo model.  The interaction of these different receptor systems with intraneuronal signaling and behaviors needs to be studied further.

  2. Role of retinal glial cell glutamate transporters in retinal ganglion cell survival following stimulation of NMDA receptor.

    Science.gov (United States)

    Furuya, Toshie; Pan, Zhiying; Kashiwagi, Kenji

    2012-03-01

    To investigate the role of glutamate transporters (GLTs)in retinal glial cells that were treated with N-methyl-D-aspartate (NMDA), in retinal ganglion cell (RGC) survival. Primary cultures of retinal glial cells or RGCs from 3-day-old Sprague-Dawley rats were employed in the present study. Retinal glial cells were treated with NMDA and changes in GLT mRNA and protein expression were analyzed. The effects of pretreating retinal glial cells with the GLAST-specific inhibitor, rottlerin (ROT), and the GLT-1-specific inhibitor, dihydrokainic acid (DHK), on RGC survival were investigated under exposure to NMDA. The amount of glutamate in the culture medium of retinal glial cells was measured by high-performance liquid chromatography. NMDA treatment increased GLAST and GLT-1 expression. GLAST and GLT-1 mRNA expression increased by 2.94-fold and 3.36-fold at 12 h after treatment with the highest concentration of NMDA (33 mM), and by 1.41-fold and 1.39-fold at 24 h, respectively. GLT-1 and GLAST protein expression also increased. MK801, an NMDA-receptor antagonist, inhibited the NMDA-induced upregulation of GLT mRNA expression. Co-culture with retinal glial cells increased the survival rate of RGCs. ROT decreased the survival rate of RGCs, whereas DHK significantly increased the survival rate of RGCs treated with 33 mM NMDA. NMDA treatment reduced the total amount of glutamate in the culture medium, particularly when 33 mM NMDA was added to the medium. ROT pretreatment increased the amount of glutamate in the culture medium, whereas DHK pretreatment decreased it. GLAST and GLT-1 may have different roles in the survival of RGCs mediated by retinal glial cells. These results suggest that the NMDA-associated induction of GLTs plays an important role in RGC survival.

  3. Riluzole and gabapentinoids activate glutamate transporters to facilitate glutamate-induced glutamate release from cultured astrocytes

    OpenAIRE

    Yoshizumi, Masaru; Eisenach, James. C.; Hayashida, Ken-ichiro

    2011-01-01

    We have recently demonstrated that the glutamate transporter activator riluzole paradoxically enhanced glutamate-induced glutamate release from cultured astrocytes. We further showed that both riluzole and the α2δ subunit ligand gabapentin activated descending inhibition in rats by increasing glutamate receptor signaling in the locus coeruleus and hypothesized that these drugs share common mechanisms to enhance glutamate release from astrocytes. In the present study, we examined the effects o...

  4. Repeated potentiation of the metabotropic glutamate receptor 5 and the alpha 7 nicotinic acetylcholine receptor modulates behavioural and GABAergic deficits induced by early postnatal phencyclidine (PCP) treatment

    DEFF Research Database (Denmark)

    Kjaerby, Celia; Bundgaard, Christoffer; Fejgin, Kim

    2013-01-01

    whether behavioural and GABAergic functional deficits induced by the NMDA receptor channel blocker, phencyclidine (PCP), could be reversed by repeated administration of two drugs known to enhance GABAergic transmission: the positive allosteric modulator (PAM) of the metabotropic glutamate receptor 5 (m......GluR5), ADX47273, and the partial agonist of the α7 nicotinic acetylcholine receptor (α7 nAChR), SSR180711. Adolescent rats (4-5 weeks) subjected to PCP treatment during the second postnatal week displayed a consistent deficit in prepulse inhibition (PPI), which was reversed by a one-week treatment...... with ADX47273 and SSR180711 decreased the induction of spontaneous inhibitory current caused by acute and direct agonism of mGluR5s and α7 nAChRs in slices. These results show that repeated administration of ADX47273 or SSR180711 reverses certain behavioural and functional deficits induced by PCP, likely...

  5. Spinal intracellular metabotropic glutamate receptor 5 (mGluR5) contributes to pain and c-fos expression in a rat model of inflammatory pain.

    Science.gov (United States)

    Vincent, Kathleen; Wang, Shu Fan; Laferrière, André; Kumar, Naresh; Coderre, Terence J

    2017-04-01

    Metabotropic glutamate receptor 5 (mGluR5) is an excitatory G-protein-coupled receptor (GPCR) present in the spinal cord dorsal horn (SCDH) where it has a well-established role in pain. In addition to its traditional location on the cytoplasmic membrane, recent evidence shows that these receptors are present intracellularly on the nuclear membrane in the spinal cord dorsal horn and are implicated in neuropathic pain. Nuclear mGluR5 is a functional receptor that binds glutamate entering the cell through the neuronal glutamate transporter (GT) EAAT3 and activates transcription factor c-fos, whereas plasma membrane mGluR5 is responsible for c-jun activation. Here, we extend these findings to a model of inflammatory pain using complete Freund's adjuvant (CFA) and show that nuclear mGluR5 is also upregulated in the spinal cord dorsal horn following inflammation. We also show that pretreatment with an excitatory amino acid transporter (EAAT) inhibitor attenuates pain and decreases Fos, but not Jun, expression in complete Freund's adjuvant rats. In contrast, selective glial glutamate transporter inhibitors are pronociceptive and increase spinal glutamate concentrations. Additionally, we found that permeable mGluR5 antagonists are more effective at attenuating pain and Fos expression than nonpermeable group I mGluR antagonists. Taken together, these results suggest that under inflammatory conditions, intracellular mGluR5 is actively involved in the relay of nociceptive information in the spinal cord.

  6. N-Acetyl-cysteine causes analgesia by reinforcing the endogenous activation of type-2 metabotropic glutamate receptors

    Directory of Open Access Journals (Sweden)

    Bernabucci Matteo

    2012-10-01

    Full Text Available Abstract Background Pharmacological activation of type-2 metabotropic glutamate receptors (mGlu2 receptors causes analgesia in experimental models of inflammatory and neuropathic pain. Presynaptic mGlu2 receptors are activated by the glutamate released from astrocytes by means of the cystine/glutamate antiporter (System xc- or Sxc-. We examined the analgesic activity of the Sxc- activator, N-acetyl-cysteine (NAC, in mice developing inflammatory or neuropathic pain. Results A single injection of NAC (100 mg/kg, i.p. reduced nocifensive behavior in the second phase of the formalin test. NAC-induced analgesia was abrogated by the Sxc- inhibitor, sulphasalazine (8 mg/kg, i.p. or by the mGlu2/3 receptor antagonist, LY341495 (1 mg/kg, i.p.. NAC still caused analgesia in mGlu3−/− mice, but was inactive in mGlu2−/− mice. In wild-type mice, NAC retained the analgesic activity in the formalin test when injected daily for 7 days, indicating the lack of tolerance. Both single and repeated injections of NAC also caused analgesia in the complete Freund’s adjuvant (CFA model of chronic inflammatory pain, and, again, analgesia was abolished by LY341495. Data obtained in mice developing neuropathic pain in response to chronic constriction injury (CCI of the sciatic nerve were divergent. In this model, a single injection of NAC caused analgesia that was reversed by LY341495, whereas repeated injections of NAC were ineffective. Thus, tolerance to NAC-induced analgesia developed in the CCI model, but not in models of inflammatory pain. The CFA and CCI models differed with respect to the expression levels of xCT (the catalytic subunit of Sxc- and activator of G-protein signaling type-3 (AGS3 in the dorsal portion of the lumbar spinal cord. CFA-treated mice showed no change in either protein, whereas CCI mice showed an ipislateral reduction in xCT levels and a bilateral increase in AGS3 levels in the spinal cord. Conclusions These data demonstrate that

  7. 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

    , and the series of 4-alkyl-HIBO analogues have been extended in this paper in the search for versatile agents. Pharmacological characterization of five new analogues, branched and unbranched 4-alkyl-HIBO analogues, have been carried out. The present compounds are all weak antagonists at Group I mGluRs (mGluR1......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...... and 5) presenting only small differences in potencies (Ki values ranging from 89 to 670 microM). Affinities were studied at native and cloned iGluRs, and the compounds described show preference for the AMPA receptor subtypes GluR1 and 2 over GluR3 and 4. However, compared to previous 4-alkyl...

  8. Long-term activation of group I metabotropic glutamate receptors increases functional TRPV1-expressing neurons in mouse dorsal root ganglia

    Directory of Open Access Journals (Sweden)

    Takayoshi eMasuoka

    2016-03-01

    Full Text Available Damaged tissues release glutamate and other chemical mediators for several hours. These chemical mediators contribute to modulation of pruritus and pain. Herein, we investigated the effects of long-term activation of excitatory glutamate receptors on functional expression of transient receptor potential vaniloid type 1 (TRPV1 in dorsal root ganglion (DRG neurons and then on thermal pain behavior. In order to detect the TRPV1-mediated responses in cultured DRG neurons, we monitored intracellular calcium responses to capsaicin, a TRPV1 agonist, with Fura-2. Long-term (4 h treatment with glutamate receptor agonists (glutamate, quisqualate or DHPG increased the proportion of neurons responding to capsaicin through activation of metabotropic glutamate receptor mGluR1, and only partially through the activation of mGluR5; engagement of these receptors was evident in neurons responding to allylisothiocyanate (AITC, a transient receptor potential ankyrin type 1 (TRPA1 agonist. Increase in the proportion was suppressed by phospholipase C, protein kinase C, mitogen/extracellular signal-regulated kinase, p38 mitogen-activated protein kinase or transcription inhibitors. Whole-cell recording was performed to record TRPV1-mediated membrane current; TRPV1 current density significantly increased in the AITC-sensitive neurons after the quisqualate treatment. To elucidate the physiological significance of this phenomenon, a hot plate test was performed. Intraplantar injection of quisqualate or DHPG induced heat hyperalgesia that lasted for 4 h post injection. This chronic hyperalgesia was attenuated by treatment with either mGluR1 or mGluR5 antagonists. These results suggest that long-term activation of mGluR1/5 by peripherally released glutamate may increase the number of neurons expressing functional TRPV1 in DRG, which may be strongly associated with chronic hyperalgesia.

  9. Genome-wide copy number variation study associates metabotropic glutamate receptor gene networks with attention deficit hyperactivity disorder

    Science.gov (United States)

    Elia, Josephine; Glessner, Joseph T; Wang, Kai; Takahashi, Nagahide; Shtir, Corina J; Hadley, Dexter; Sleiman, Patrick M A; Zhang, Haitao; Kim, Cecilia E; Robison, Reid; Lyon, Gholson J; Flory, James H; Bradfield, Jonathan P; Imielinski, Marcin; Hou, Cuiping; Frackelton, Edward C; Chiavacci, Rosetta M; Sakurai, Takeshi; Rabin, Cara; Middleton, Frank A; Thomas, Kelly A; Garris, Maria; Mentch, Frank; Freitag, Christine M; Steinhausen, Hans-Christoph; Todorov, Alexandre A; Reif, Andreas; Rothenberger, Aribert; Franke, Barbara; Mick, Eric O; Roeyers, Herbert; Buitelaar, Jan; Lesch, Klaus-Peter; Banaschewski, Tobias; Ebstein, Richard P; Mulas, Fernando; Oades, Robert D; Sergeant, Joseph; Sonuga-Barke, Edmund; Renner, Tobias J; Romanos, Marcel; Romanos, Jasmin; Warnke, Andreas; Walitza, Susanne; Meyer, Jobst; Pálmason, Haukur; Seitz, Christiane; Loo, Sandra K; Smalley, Susan L; Biederman, Joseph; Kent, Lindsey; Asherson, Philip; Anney, Richard J L; Gaynor, J William; Shaw, Philip; Devoto, Marcella; White, Peter S; Grant, Struan F A; Buxbaum, Joseph D; Rapoport, Judith L; Williams, Nigel M; Nelson, Stanley F; Faraone, Stephen V; Hakonarson, Hakon

    2014-01-01

    Attention deficit hyperactivity disorder (ADHD) is a common, heritable neuropsychiatric disorder of unknown etiology. We performed a whole-genome copy number variation (CNV) study on 1,013 cases with ADHD and 4,105 healthy children of European ancestry using 550,000 SNPs. We evaluated statistically significant findings in multiple independent cohorts, with a total of 2,493 cases with ADHD and 9,222 controls of European ancestry, using matched platforms. CNVs affecting metabotropic glutamate receptor genes were enriched across all cohorts (P = 2.1 × 10−9). We saw GRM5 (encoding glutamate receptor, metabotropic 5) deletions in ten cases and one control (P = 1.36 × 10−6). We saw GRM7 deletions in six cases, and we saw GRM8 deletions in eight cases and no controls. GRM1 was duplicated in eight cases. We experimentally validated the observed variants using quantitative RT-PCR. A gene network analysis showed that genes interacting with the genes in the GRM family are enriched for CNVs in ~10% of the cases (P = 4.38 × 10−10) after correction for occurrence in the controls. We identified rare recurrent CNVs affecting glutamatergic neurotransmission genes that were overrepresented in multiple ADHD cohorts. PMID:22138692

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

    DEFF Research Database (Denmark)

    Møllerud, Stine; Pinto, Andrea; Marconi, Laura

    2017-01-01

    and depression. In order to understand the function of different types of iGluRs, selective agonists are invaluable as pharmacological tool compounds. Here, we report binding affinities of two bicyclic, conformationally restricted analogues of glutamate (CIP-AS and LM-12b) at AMPA (GluA2 and GluA3) and kainate...

  11. 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

  12. Importance of GluA1 subunit-containing AMPA glutamate receptors for morphine state-dependency.

    Directory of Open Access Journals (Sweden)

    Teemu Aitta-aho

    Full Text Available In state-dependency, information retrieval is most efficient when the animal is in the same state as it was during the information acquisition. State-dependency has been implicated in a variety of learning and memory processes, but its mechanisms remain to be resolved. Here, mice deficient in AMPA-type glutamate receptor GluA1 subunits were first conditioned to morphine (10 or 20 mg/kg s.c. during eight sessions over four days using an unbiased procedure, followed by testing for conditioned place preference at morphine states that were the same as or different from the one the mice were conditioned to. In GluA1 wildtype littermate mice the same-state morphine dose produced the greatest expression of place preference, while in the knockout mice no place preference was then detected. Both wildtype and knockout mice expressed moderate morphine-induced place preference when not at the morphine state (saline treatment at the test; in this case, place preference was weaker than that in the same-state test in wildtype mice. No correlation between place preference scores and locomotor activity during testing was found. Additionally, as compared to the controls, the knockout mice showed unchanged sensitization to morphine, morphine drug discrimination and brain regional μ-opioid receptor signal transduction at the G-protein level. However, the knockout mice failed to show increased AMPA/NMDA receptor current ratios in the ventral tegmental area dopamine neurons of midbrain slices after a single injection of morphine (10 mg/kg, s.c., sliced prepared 24 h afterwards, in contrast to the wildtype mice. The results indicate impaired drug-induced state-dependency in GluA1 knockout mice, correlating with impaired opioid-induced glutamate receptor neuroplasticity.

  13. 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...

  14. Tolerance to LSD and DOB induced shaking behaviour: differential adaptations of frontocortical 5-HT(2A) and glutamate receptor binding sites.

    Science.gov (United States)

    Buchborn, Tobias; Schröder, Helmut; Dieterich, Daniela C; Grecksch, Gisela; Höllt, Volker

    2015-03-15

    Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD) and dimethoxy-bromoamphetamine (DOB), provoke stereotype-like shaking behaviour in rodents, which is hypothesised to engage frontocortical glutamate receptor activation secondary to serotonin2A (5-HT2A) related glutamate release. Challenging this hypothesis, we here investigate whether tolerance to LSD and DOB correlates with frontocortical adaptations of 5-HT2A and/or overall-glutamate binding sites. LSD and DOB (0.025 and 0.25 mg/kg, i.p.) induce a ketanserin-sensitive (0.5 mg/kg, i.p., 30-min pretreatment) increase in shaking behaviour (including head twitches and wet dog shakes), which with repeated application (7× in 4 ds) is undermined by tolerance. Tolerance to DOB, as indexed by DOB-sensitive [(3)H]spiroperidol and DOB induced [(35)S]GTP-gamma-S binding, is accompanied by a frontocortical decrease in 5-HT2A binding sites and 5-HT2 signalling, respectively; glutamate-sensitive [(3)H]glutamate binding sites, in contrast, remain unchanged. As to LSD, 5-HT2 signalling and 5-HT2A binding, respectively, are not or only marginally affected, yet [(3)H]glutamate binding is significantly decreased. Correlation analysis interrelates tolerance to DOB to the reduced 5-HT2A (r=.80) as well as the unchanged [(3)H]glutamate binding sites (r=.84); tolerance to LSD, as opposed, shares variance with the reduction in [(3)H]glutamate binding sites only (r=.86). Given that DOB and LSD both induce tolerance, one correlating with 5-HT2A, the other with glutamate receptor adaptations, it might be inferred that tolerance can arise at either level. That is, if a hallucinogen (like LSD in our study) fails to induce 5-HT2A (down-)regulation, glutamate receptors (activated postsynaptic to 5-HT2A related glutamate release) might instead adapt and thus prevent further overstimulation of the cortex. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Allosteric and orthosteric sites in CC chemokine receptor (CCR5), a chimeric receptor approach

    DEFF Research Database (Denmark)

    Thiele, Stefanie; Steen, Anne; Jensen, Pia C

    2011-01-01

    molecules often act more deeply in an allosteric mode. However, opposed to the well described molecular interaction of allosteric modulators in class C 7-transmembrane helix (7TM) receptors, the interaction in class A, to which the chemokine receptors belong, is more sparsely described. Using the CCR5...... chemokine receptor as a model system, we studied the molecular interaction and conformational interchange required for proper action of various orthosteric chemokines and allosteric small molecules, including the well known CCR5 antagonists TAK-779, SCH-C, and aplaviroc, and four novel CCR5 ago......-allosteric molecules. A chimera was successfully constructed between CCR5 and the closely related CCR2 by transferring all extracellular regions of CCR2 to CCR5, i.e. a Trojan horse that resembles CCR2 extracellularly but signals through a CCR5 transmembrane unit. The chimera bound CCR2 (CCL2 and CCL7), but not CCR5...

  16. Reduced expression of C5a receptors on neutrophils from cord blood

    DEFF Research Database (Denmark)

    Nybo, Mads; Sørensen, O; Leslie, R

    1998-01-01

    AIM: To describe further functional deficiencies of neonatal neutrophils by measuring the expression of C5a receptors. METHODS: C5a uptake was measured using flow cytometry with fluorescein isothiocynate labelled recombinant C5a. The response of neutrophils to stimulation with C5a and fMLP...... was tested by measuring migration and exocytosis of myeloperoxidase and lactoferrin. RESULTS: C5a mean fluorescence on neutrophils from neonates was significantly lower (22.4 (SD 3.5)) than in adult controls (31.5 (3.1)). Neutrophils from neonates migrated poorly towards both C5a and fMLP compared with those...... from adult controls. Exocytosis of myeloperoxidase, but not lactoferrin from neonatal neutrophils stimulated with C5a, was significantly lower than in adult controls. fMLP stimulation, on the other hand, resulted in significantly higher exocytosis in neonates. CONCLUSION: The lower expression of C5a...

  17. 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.

  18. (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)....

  19. Targeting mGlu5 Metabotropic Glutamate Receptors in the Treatment of Cognitive Dysfunction in a Mouse Model of Phenylketonuria

    Directory of Open Access Journals (Sweden)

    Francesca Nardecchia

    2018-03-01

    Full Text Available We studied group-I metabotropic glutamate (mGlu receptors in Pahenu2 (ENU2 mice, which mimic the genetics and neurobiology of human phenylketonuria (PKU, a metabolic disorder characterized, if untreated, by autism, and intellectual disability (ID. Male ENU2 mice showed increased mGlu5 receptor protein levels in the hippocampus and corpus striatum (but not in the prefrontal cortex whereas the transcript of the mGlu5 receptor was unchanged. No changes in mGlu1 receptor mRNA and protein levels were found in any of the three brain regions of ENU2 mice. We extended the analysis to Homer proteins, which act as scaffolds by linking mGlu1 and mGlu5 receptors to effector proteins. Expression of the long isoforms of Homer was significantly reduced in the hippocampus of ENU2 mice, whereas levels of the short Homer isoform (Homer 1a were unchanged. mGlu5 receptors were less associated to immunoprecipitated Homer in the hippocampus of ENU2 mice. The lack of mGlu5 receptor-mediated long-term depression (LTD in wild-type mice (of BTBR strain precluded the analysis of hippocampal synaptic plasticity in ENU2 mice. We therefore performed a behavioral analysis to examine whether pharmacological blockade of mGlu5 receptors could correct behavioral abnormalities in ENU2 mice. Using the same apparatus we sequentially assessed locomotor activity, object exploration, and spatial object recognition (spatial novelty test after displacing some of the objects from their original position in the arena. Systemic treatment with the mGlu5 receptor antagonist, MPEP (20 mg/kg, i.p., had a striking effect in the spatial novelty test by substantially increasing the time spent in exploring the displaced objects in ENU2 mice (but not in wild-type mice. These suggest a role for mGlu5 receptors in the pathophysiology of ID in PKU and suggest that, also in adult untreated animals, cognitive dysfunction may be improved by targeting these receptors with an appropriate therapy.

  20. The Modulatory Effect of Metabotropic Glutamate Receptor Type-1α on Spike-Wave Discharges in WAG/Rij Rats.

    Science.gov (United States)

    Karimzadeh, Fariba; Modarres Mousavi, Sayed Mostafa; Ghadiri, Tahereh; Jafarian, Maryam; Soleimani, Mansoureh; Sadeghi, Shahin Mohammad; Mesgari, Masoud; Joghataei, Mohammad-Taghi; Gorji, Ali

    2017-03-01

    Modulatory function of metabotropic glutamate type 1 (mGlu1) receptors plays a crucial role in the pathophysiology of some neurological disorders, including schizophrenia and epilepsy. In this study, the expression of mGlu1α receptors in the thalamic nuclei was assessed during development of absence seizures in the WAG/Rij rats, a valid genetic animal model of absence epilepsy. In addition, the effect of pharmacological modulation of mGlu1α receptors in the laterodorsal (LD) nucleus of the thalamus on the characteristic features of bioelectrical brain activities in the WAG/Rij rats was assessed. The expression of mGlu1α receptors in the LD was assessed in four experimental groups of both WAG/Rij and Wistar rats with 2 and 6 months of age. Agonist and antagonist of mGlu1α receptors were infused in LD in the six months old WAG/Rij (epileptic) rats. The protein level of mGlu1α receptors in the thalamus of the 6-month-old WAG/Rij rats was lower than non-epileptic animals. In addition, the distribution of mGlu1α receptors in different thalamic nuclei was lower in the 6-month-old WAG/Rij compared to age-matched Wistar rats. The gene expression of mGlu1α receptor was also significantly lower in 6-month-old WAG/Rij rats in the LD compared to other animal groups. The microinjection of mGlu1α receptors agonist and antagonist in the LD reduced the duration of spike-wave discharges (SWDs) and increased the amplitude and duration of SWDs, respectively, in 6-month-old WAG/Rij rats. The alterations of mGlu1α receptors expression in the thalamus of epileptic WAG/Rij rats as well as its modulatory effects in the generation of SWDs suggest the potential of mGlu1 receptors as a therapeutic target in absence epilepsy.

  1. Effects of rasagiline, its metabolite aminoindan and selegiline on glutamate receptor mediated signalling in the rat hippocampus slice in vitro

    Science.gov (United States)

    2011-01-01

    Background Rasagiline, a new drug developed to treat Parkinson's disease, is known to inhibit monoamine oxidase B. However, its metabolite R-(-)-aminoindan does not show this kind of activity. The present series of in vitro experiments using the rat hippocampal slice preparation deals with effects of both compounds on the pyramidal cell response after electric stimulation of the Schaffer Collaterals in comparison to selegiline, another MAO B inhibitor. Method Stimulation of the Schaffer Collaterals by single stimuli (SS) or theta burst stimulation (TBS) resulted in stable responses of pyramidal cells measured as population spike amplitude (about 1 mV under control SS conditions or about 2 mV after TBS). Results During the first series, this response was attenuated in the presence of rasagiline and aminoindan-to a lesser degree of selegiline-in a concentration dependent manner (5-50 μM) after single stimuli as well as under TBS. During oxygen/glucose deprivation for 10 min the amplitude of the population spike breaks down by 75%. The presence of rasagiline and aminoindan, but rarely the presence of selegiline, prevented this break down. Following glutamate receptor mediated enhancements of neuronal transmission in a second series of experiments very clear differences could be observed in comparison to the action of selegiline: NMDA receptor, AMPA receptor as well as metabotropic glutamate receptor mediated increases of transmission were concentration dependently (0,3 - 2 μM) antagonized by rasagiline and aminoindan, but not by selegiline. On the opposite, only selegiline attenuated kainate receptor mediated increases of excitability. Thus, both monoamino oxidase (MAO) B inhibitors show attenuation of glutamatergic transmission in the hippocampus but interfere with different receptor mediated excitatory modulations at low concentrations. Conclusions Since aminoindan does not induce MAO B inhibition, these effects must be regarded as being independent from MAO B

  2. CLEC5A is a critical receptor in innate immunity against Listeria infection.

    Science.gov (United States)

    Chen, Szu-Ting; Li, Fei-Ju; Hsu, Tzy-Yun; Liang, Shu-Mei; Yeh, Yi-Chen; Liao, Wen-Yu; Chou, Teh-Ying; Chen, Nien-Jun; Hsiao, Michael; Yang, Wen-Bin; Hsieh, Shie-Liang

    2017-08-21

    The C-type lectin member 5A (CLEC5A) is a pattern recognition receptor for members of the Flavivirus family and has critical functions in response to dengue virus and Japanese encephalitis virus. Here we show that CLEC5A is involved in neutrophil extracellular trap formation and the production of reactive oxygen species and proinflammatory cytokines in response to Listeria monocytogenes. Inoculation of Clec5a -/- mice with L. monocytogenes causes rapid bacterial spreading, increased bacterial loads in the blood and liver, and severe liver necrosis. In these mice, IL-1β, IL-17A, and TNF expression is inhibited, CCL2 is induced, and large numbers of CD11b + Ly6C hi CCR2 hi CX3CR1 low inflammatory monocytes infiltrate the liver. By day 5 of infection, these mice also have fewer IL-17A + γδ T cells, severe liver necrosis and a higher chance of fatality. Thus, CLEC5A has a pivotal function in the activation of multiple aspects of innate immunity against bacterial invasion.The lectin receptor CLEC5A is a pattern recognition receptor that has been shown to detect dengue and Japanese encephalitis virus. Here the authors show that CLEC5A is needed for optimal ROS production, NET formation and other immune responses to Listeria monocytogenes in mice.

  3. [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

  4. Targeting Sentinel Proteins and Extrasynaptic Glutamate Receptors: a Therapeutic Strategy for Preventing the Effects Elicited by Perinatal Asphyxia?

    Science.gov (United States)

    Herrera-Marschitz, Mario; Perez-Lobos, Ronald; Lespay-Rebolledo, Carolyne; Tapia-Bustos, Andrea; Casanova-Ortiz, Emmanuel; Morales, Paola; Valdes, Jose-Luis; Bustamante, Diego; Cassels, Bruce K

    2018-02-01

    Perinatal asphyxia (PA) is a relevant cause of death at the time of labour, and when survival is stabilised, associated with short- and long-term developmental disabilities, requiring inordinate care by health systems and families. Its prevalence is high (1 to 10/1000 live births) worldwide. At present, there are few therapeutic options, apart from hypothermia, that regrettably provides only limited protection if applied shortly after the insult.PA implies a primary and a secondary insult. The primary insult relates to the lack of oxygen, and the secondary one to the oxidative stress triggered by re-oxygenation, formation of reactive oxygen (ROS) and reactive nitrogen (RNS) species, and overactivation of glutamate receptors and mitochondrial deficiencies. PA induces overactivation of a number of sentinel proteins, including hypoxia-induced factor-1α (HIF-1α) and the genome-protecting poly(ADP-ribose) polymerase-1 (PARP-1). Upon activation, PARP-1 consumes high amounts of ATP at a time when this metabolite is scarce, worsening in turn the energy crisis elicited by asphyxia. The energy crisis also impairs ATP-dependent transport, including glutamate re-uptake by astroglia. Nicotinamide, a PARP-1 inhibitor, protects against the metabolic cascade elicited by the primary stage, avoiding NAD + exhaustion and the energetic crisis. Upon re-oxygenation, however, oxidative stress leads to nuclear translocation of the NF-κB subunit p65, overexpression of the pro-inflammatory cytokines IL-1β and TNF-α, and glutamate-excitotoxicity, due to impairment of glial-glutamate transport, extracellular glutamate overflow, and overactivation of NMDA receptors, mainly of the extrasynaptic type. This leads to calcium influx, mitochondrial impairment, and inactivation of antioxidant enzymes, increasing further the activity of pro-oxidant enzymes, thereby making the surviving neonate vulnerable to recurrent metabolic insults whenever oxidative stress is involved. Here, we discuss

  5. Reverse microdialysis of a 5-HT2A receptor antagonist alters extracellular glutamate levels in the striatum of the MPTP mouse model of Parkinson's disease.

    Science.gov (United States)

    Ferguson, Marcus C; Nayyar, Tultul; Ansah, Twum A

    2014-05-01

    Clinical observations have suggested that antagonism of 5-HT2A receptors may benefit patients with parkinsonian symptomatology. The mechanism of the antiparkinsonian effects of 5-HT2A receptor antagonists has not been fully elucidated. We have shown that the selective 5-HT2A receptor antagonist M100907 [R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenethyl)]-4-piperidinemethanol] improved motor impairments in mice treated with the parkinsonian neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In Parkinson's disease (PD) patients and animal models of parkinsonism dopamine denervation is associated with increased cortico-striatal glutamatergic transmission. We hypothesized that 5-HT2A receptor antagonists may exert their antiparkinsonian effects by decreasing striatal glutamate. Here, using in vivo microdialysis, we have shown an increased basal level of extracellular striatal glutamate when measured 3weeks after MPTP administration. The local administration of M100907 to the striatum significantly decreased striatal extracellular glutamate levels in MPTP-treated and saline treated mice. Basal extracellular serotonin (5-HT) levels were also elevated, whereas dopamine (DA) levels were significantly reduced in the striatum of MPTP-treated mice. Infusion of M100907 into the striatum produced no effect on dopamine or 5-HT levels. Local application of tetrodotoxin suppressed glutamate, 5-HT and DA concentrations in striatal dialysates in the presence or absence of M100907. The striatal expression of the glutamate transporter GLT1 was unchanged. However, there was an upregulation of the expression of 5-HT2A receptors in the striatum of MPTP-treated animals. Our data provide further evidence of enhanced glutamatergic neurotransmission in parkinsonism and demonstrate that blocking 5-HT2A receptors in the striatum will normalize glutamatergic neurotransmission. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Efficacy of glutamate receptor antagonists in the management of functional disorders in cytotoxic brain oedema induced by hexachlorophene.

    Science.gov (United States)

    Häntzschel, A; Andreas, K

    1998-02-01

    The hexachlorophene-induced cytotoxic brain oedema is an experimental model of brain damage, suitable for testing cerebroprotective substances (Andreas 1993). In order to examine whether glutamate receptors are involved in mediating functional disorders due to neurotoxic brain damage, we have studied the protective effects of several competitive and non-competitive antagonists using adult male Wistar rats in a simple "ladder-test" for assessing coordinative motor behaviour. Hexachlorophene-induced brain damage was verified by histological examination of the cerebellum with vacuolation of white matter, astrocyte hypertrophy and astrocyte proliferation taken as signs of neurotoxic injury. The non-competitive N-methyl-D-aspartate (NMDA) antagonist dizocilpine maleate (MK-801) decreased the motor disturbance on the first and second day of the "ladder-test" when applied in the doses 0.1 mg/kg and 0.2 mg/kg intraperitoneally for 3 weeks during the hexachlorophene treatment. Acute MK-801 administration (0.1 mg/kg intraperitoneally) after 3 weeks hexachlorophene exposure improved the coordinative motor response only on the first day. When testing the competitive NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP-5) in the dose 1.0 mg/kg intraperitoneally the motor disturbance was lowered significantly earlier than in spontaneous remission. Similar effects were observed with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in the dose of 0.8 mg/kg intraperitoneally, an antagonist interacting both with the strychnine-insensitive binding site for glycine within the NMDA receptor complex and with the kainate(+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor complex. Concurrent MK-801 administration decreased the vacuolation of white matter. The results suggest that NMDA receptors and non-NMDA receptors are involved in development of functional disorders induced by hexachlorophene.

  7. Effect of metabotropic glutamate receptor 3 genotype on N-acetylaspartate levels and neurocognition in non-smoking, active alcoholics

    Directory of Open Access Journals (Sweden)

    Xia Yan

    2012-08-01

    Full Text Available Abstract Background We studied the effects of single nucleotide polymorphisms (SNPs in the metabotropic glutamate receptor 3 (GRM3 gene on brain N-acetylaspartate (NAA concentrations and executive function (EF skills in non-smoking, active alcoholics, and evaluated associations between these variables. Methods SNPs (rs6465084, rs1468412, and rs2299225 in GRM3 were genotyped in 49 male, non-smoking, alcohol-dependent patients and 45 healthy control subjects using ligase detection reactions. NAA/creatine (Cr ratios in left prefrontal gray matter (GM and white matter (WM, left parietal GM, left parietal WM, and cerebellar vermis regions were measured by Proton 1 H Magnetic resonance spectroscopy (MRS. EF was measured by the Wisconsin Card Sorting Test (WCST. Results Compared to controls, alcoholics had lower NAA/Cr ratios in prefrontal GM and WM regions and performed more poorly on all EF tests (P P P P P P  Conclusions Our results provide evidence that glutamate system dysfunction may play a role in the prefrontal functional abnormalities seen in alcohol dependence. It is possible that certain GRM3 SNP genotypes (the A/A genotype of rs6465084 and the T allele of rs1468412 may further lower NAA/Cr levels and EF skills in addition to the effect of alcohol.

  8. Functional properties of a metabotropic glutamate receptor at dendritic synapses of ON bipolar cells in the amphibian retina.

    Science.gov (United States)

    Tian, N; Slaughter, M M

    1995-01-01

    Perforated patch-voltage and current-clamp recordings were obtained from ON bipolar cells in the amphibian retinal slice preparation. The currents produced by the photoreceptor transmitter were compared to the currents produced by selective metabotropic glutamate agonists: L-2-amino-4-phosphonobutyrate (L-AP4, APB) and IS,3R 1-amino-1,3 cyclopentanedicarboxylic acid (1S, 3R ACPD). Both agonists produced currents that were very similar to that produced by the photoreceptor transmitter in terms of conductance and reversal potential. The similarities suggest that the metabotropic glutamate receptors are functionally localized to the synaptic region of ON bipolar dendrites. The synaptic conductance rarely exceeded the non-synaptic conductance. The mean input resistance of ON bipolar neurons was 770 M omega in the light and 1.2 G omega in the dark. The average light-regulated synaptic conductance was 57% of the non-synaptic conductance. The L-AP4 regulated conductance averaged 77% of the non-synaptic conductance, while the 1S, 3R ACPD regulated conductance averaged 95% of the non-synaptic conductance. This balance between synaptic and non-synaptic conductance indicates that the synapse will not shunt the cell and the conductance ratio serves to maximize incremental gain at the photoreceptor to ON bipolar synapse. This conductance mechanism makes the ON bipolar cell well equipped to relay rod signals.

  9. 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

  10. Activation of Metabotropic Glutamate Receptor Type 2/3 Supports the Involvement of the Hippocampal Mossy Fiber Pathway on Contextual Fear Memory Consolidation

    Science.gov (United States)

    Daumas, Stephanie; Ceccom, Johnatan; Halley, Helene; Frances, Bernard; Lassalle, Jean-Michel

    2009-01-01

    Elucidating the functional properties of the dentate gyrus (DG), CA3, and CA1 areas is critical for understanding the role of the dorsal hippocampus in contextual fear memory processing. In order to specifically disrupt various hippocampal inputs, we used region-specific infusions of DCG-IV, the metabotropic glutamate receptor agonist, which…

  11. Controversial action of positive modulator of subtype 7 of metabotropic glutamate receptors AMN082 on cortical epileptic afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Szczurowska, Ewa; Mareš, Pavel

    2009-01-01

    Roč. 623, 1-3 (2009), s. 37-40 ISSN 0014-2999 R&D Projects: GA ČR(CZ) GA305/06/1188 Institutional research plan: CEZ:AV0Z50110509 Keywords : epileptic afterdischarges * glutamate receptors * rat Subject RIV: FH - Neurology Impact factor: 2.585, year: 2009

  12. MacMARCKS interacts with the metabotropic glutamate receptor type 7 and modulates G protein-mediated constitutive inhibition of calcium channels

    Czech Academy of Sciences Publication Activity Database

    Bertaso, F.; Lill, Y.; Airas, J.M.; Espeut, J.; Blahoš, Jaroslav; Bockaert, J.; Fagni, L.; Betz, H.; Far, O.E.

    2006-01-01

    Roč. 99, - (2006), s. 288-298 ISSN 0022-3042 R&D Projects: GA ČR GA204/05/0920 Institutional research plan: CEZ:AV0Z50390512 Keywords : calmodulin * metabotropic glutamate receptor * calcium channel Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.260, year: 2006

  13. Expression patterns of group III metabotropic glutamate receptors mGluR4 and mGluR8 in multiple sclerosis lesions

    NARCIS (Netherlands)

    Geurts, J. J. G.; Wolswijk, G.; Bö, L.; Redeker, S.; Ramkema, M.; Troost, D.; Aronica, E.

    2005-01-01

    Recent evidence supports a role for metabotropic glutamate receptors (mGluRs) in neuroinflammatory diseases. In the present study, we have investigated whether the group III mGluR subtypes mGluR4 and mGluR8 are expressed in MS lesions at various stages of evolution. In control patient tissue and in

  14. Type-1 metabotropic glutamate receptor signaling in cerebellar Purkinje cells in health and disease [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Masanobu Kano

    2017-04-01

    Full Text Available The cerebellum is a brain structure involved in coordination, control, and learning of movements, as well as certain aspects of cognitive function. Purkinje cells are the sole output neurons from the cerebellar cortex and therefore play crucial roles in the overall function of the cerebellum. The type-1 metabotropic glutamate receptor (mGluR1 is a key “hub” molecule that is critically involved in the regulation of synaptic wiring, excitability, synaptic response, and synaptic plasticity of Purkinje cells. In this review, we aim to highlight how mGluR1 controls these events in Purkinje cells. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunctions in several clinically relevant mouse models of human ataxias.

  15. Construction of a high affinity zinc binding site in the metabotropic glutamate receptor mGluR1

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Sheppard, P O; Jensen, L B

    2001-01-01

    The metabotropic glutamate receptors (mGluRs) belong to family C of the G-protein-coupled receptor (GPCR) superfamily. The receptors are characterized by having unusually long amino-terminal domains (ATDs), to which agonist binding has been shown to take place. Previously, we have constructed...... created a Zn(2+) binding site in mGluR1b by mutating the residue Lys(260) to a histidine. Zinc acts as a noncompetitive antagonist of agonist-induced IP accumulation on the K260H mutant with an IC(50) value of 2 microm. Alanine mutations of three potential "zinc coligands" in proximity to the introduced...... of a "closed" conformation, and thus stabilizing a more or less inactive "open" form of the ATD. This study presents the first metal ion site constructed in a family C GPCR. Furthermore, it is the first time a metal ion site has been created in a region outside of the seven transmembrane regions of a GPCR...

  16. 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

    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......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...... 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...

  17. 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...

  18. Blood glutamate scavenging: Insight into neuro protection

    OpenAIRE

    Leibowitz, A; Boyko, M; Shapira, Y; Zlotnik, A

    2012-01-01

    Brain insults are characterized by a multitude of complex processes, of which glutamate release plays a major role. Deleterious excess of glutamate in the brain's extracellular fluids stimulates glutamate receptors, which in turn lead to cell swelling, apoptosis, and neuronal death. These exacerbate neurological outcome. Approaches aimed at antagonizing the astrocytic and glial glutamate receptors have failed to demonstrate clinical benefit. Alternatively, eliminating excess glutamate from br...

  19. Blood Glutamate Scavenging: Insight into Neuroprotection

    OpenAIRE

    Leibowitz, Akiva; Boyko, Matthew; Shapira, Yoram; Zlotnik, Alexander

    2012-01-01

    Brain insults are characterized by a multitude of complex processes, of which glutamate release plays a major role. Deleterious excess of glutamate in the brain’s extracellular fluids stimulates glutamate receptors, which in turn lead to cell swelling, apoptosis, and neuronal death. These exacerbate neurological outcome. Approaches aimed at antagonizing the astrocytic and glial glutamate receptors have failed to demonstrate clinical benefit. Alternatively, eliminating excess glutamate from br...

  20. Group II metabotropic glutamate receptor type 2 allosteric potentiators prevent sodium lactate-induced panic-like response in panic-vulnerable rats.

    Science.gov (United States)

    Johnson, Philip L; Fitz, Stephanie D; Engleman, Eric A; Svensson, Kjell A; Schkeryantz, Jeffrey M; Shekhar, Anantha

    2013-02-01

    Rats with chronic inhibition of GABA synthesis by infusion of l-allyglycine, a glutamic acid decarboxylase inhibitor, into their dorsomedial/perifornical hypothalamus are anxious and exhibit panic-like cardio-respiratory responses to treatment with intravenous (i.v.) sodium lactate (NaLac) infusions, in a manner similar to what occurs in patients with panic disorder. We previously showed that either NMDA receptor antagonists or metabotropic glutamate receptor type 2/3 receptor agonists can block such a NaLac response, suggesting that a glutamate mechanism is contributing to this panic-like state. Using this animal model of panic, we tested the efficacy of CBiPES and THIIC, which are selective group II metabotropic glutamate type 2 receptor allosteric potentiators (at 10-30 mg/kg i.p.), in preventing NaLac-induced panic-like behavioral and cardiovascular responses. The positive control was alprazolam (3mg/kg i.p.), a clinically effective anti-panic benzodiazepine. As predicted, panic-prone rats given a NaLac challenge displayed NaLac-induced panic-like cardiovascular (i.e. tachycardia and hypertensive) responses and "anxiety" (i.e. decreased social interaction time) and "flight" (i.e. increased locomotion) -associated behaviors; however, systemic injection of the panic-prone rats with CBiPES, THIIC or alprazolam prior to the NaLac dose blocked all NaLac-induced panic-like behaviors and cardiovascular responses. These data suggested that in a rat animal model, selective group II metabotropic glutamate type 2 receptor allosteric potentiators show an anti-panic efficacy similar to alprazolam.

  1. Metabotropic glutamate receptor 5 shows different patterns of localization within the parallel visual pathways in macaque and squirrel monkeys

    Directory of Open Access Journals (Sweden)

    Shostak Y

    2014-09-01

    Full Text Available Yuri Shostak,1,5 Ashley Wenger,4 Julia Mavity-Hudson,1 Vivien A Casagrande1–3 1Department of Cell and Developmental Biology, 2Department of Psychology, 3Department of Ophthalmology and Visual Sciences, 4Undergraduate Neuroscience Program, Vanderbilt University, Nashville, TN, USA; 5Foreign Trade Unitary Enterprise, Minsk, Belarus Abstract: Glutamate is used as an excitatory neurotransmitter by the koniocellular (K, magnocellular (M, and parvocellular (P pathways to transfer signals from the primate lateral geniculate nucleus (LGN to primary visual cortex (V1. Glutamate acts through both fast ionotropic receptors, which appear to carry the main sensory message, and slower, modulatory metabotropic receptors (mGluRs. In this study, we asked whether mGluR5 relates in distinct ways to the K, M, and P LGN axons in V1. To answer this question, we used light microscopic immunocytochemistry and preembedding electron microscopic immunogold labeling to determine the localization of mGluR5 within the layers of V1 in relation to the K, M, and P pathways in macaque and squirrel monkeys. These pathways were labeled separately via wheat germ agglutinin–horseradish peroxidase (WGA–HRP injections targeting the LGN layers. mGluR5 is of interest because it: 1 has been shown to be expressed in the thalamic input layers; 2 appears to be responsible for some types of oscillatory firing, which could be important in the binding of visual features; and 3 has been associated with a number of sensory-motor gating-related pathologies, including schizophrenia and autism. Our results demonstrated the presence of mGluR5 in the neuropil of all V1 layers. This protein was lowest in IVCa (M input and the infragranular layers. In layer IVC, mGluR5 also was found postsynaptic to about 30% of labeled axons, but the distribution was uneven, such that postsynaptic mGluR5 label tended to occur opposite smaller (presumed P, and not larger (presumed M axon terminals. Only in the K

  2. Revisiting the Quinoxalinedione scaffold in the Construction of New Ligands for the Ionotropic Glutamate Receptors

    DEFF Research Database (Denmark)

    Demmer, Charles Sylvain; Rombach, David; Liu, Na

    2017-01-01

    of the study of 44 new analogs are compound 2m being a high affinity ligand for native AMPA receptors (IC50= 0.48 µM), analogs 2e,f,h,k,v all displayed selectivity for native NMDA receptors, compounds 2s,t,u are selective ligand for the GluK1 receptor. Most interestingly compound 2w was shown to be a GluK3...

  3. Chronic morphine selectively sensitizes the effect of D1 receptor agonist on presynaptic glutamate release in basolateral amygdala neurons that project to prelimbic cortex.

    Science.gov (United States)

    Song, Jiaojiao; Chen, Ming; Dong, Yi; Lai, Bin; Zheng, Ping

    2018-05-01

    Drug addiction is a brain disorder characterized by chronic, compulsive use of drugs. Previous studies have found a number of chronic morphine-induced changes in the brain at molecular levels. A study from our lab showed that chronic morphine-induced increase in the expression of presynaptic D1 receptors in basolateral amygdala (BLA) neurons played an important role in environmental cue-induced retrieval of morphine withdrawal memory. However, the downstream neurocircuitry of chronic morphine-induced increase presynaptic D1 receptors in the BLA remains to be elucidated. Using retrogradely labelling technique combined with whole-cell patch-clamp methods, our results showed that (1) chronic morphine sensitized the effect of D1 receptor agonist on presynaptic glutamate release in BLA neurons that projected to the prelimbic cortex (PrL), but had no influence on that in BLA neurons that projected to the nucleus accumbens (NAc) or the CA1 of the hippocampus; (2) chronic morphine sensitized the effect of D1 receptor agonist on action potential firing in BLA neurons that projected to the PrL, but without affecting the intrinsic excitability and the sensitivity of postsynaptic glutamate receptors to glutamate in BLA neurons that projected to the PrL. These results suggest that chronic morphine selectively sensitizes the effect of D1 receptor agonist on presynaptic glutamate release in BLA neurons that project to PrL and induces a sensitization of the effect of D1 receptor agonist on action potential firing in BLA neurons that project to the PrL. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Blockade of the N-Methyl-D-Aspartate Glutamate Receptor Ameliorates Lipopolysaccharide-Induced Renal Insufficiency.

    Science.gov (United States)

    Lin, Chian-Shiung; Hung, Shun-Fa; Huang, Ho-Shiang; Ma, Ming-Chieh

    2015-01-01

    N-methyl-D-aspartate (NMDA) receptor activation in rat kidney reduces renal perfusion and ultrafiltration. Hypoperfusion-induced ischemia is the most frequent cause of functional insufficiency in the endotoxemic kidney. Here, we used non-hypotensive rat model of lipopolysaccharide-induced endotoxemia to examine whether NMDA receptor hyperfunction contributes to acute kidney injury. Lipopolysaccharide-induced renal damage via increased enzymuria and hemodynamic impairments were ameliorated by co-treatment with the NMDA receptor blocker, MK-801. The NMDA receptor NR1 subunit in the rat kidney mainly co-localized with serine racemase, an enzyme responsible for synthesizing the NMDA receptor co-agonist, D-serine. The NMDA receptor hyperfunction in lipopolysaccharide-treated kidneys was demonstrated by NR1 and serine racemase upregulation, particularly in renal tubules, and by increased D-serine levels. Lipopolysaccharide also induced cell damage in cultured tubular cell lines and primary rat proximal tubular cells. This damage was mitigated by MK-801 and by small interfering RNA targeting NR1. Lipopolysaccharide increased cytokine release in tubular cell lines via toll-like receptor 4. The release of interleukin-1β from these cells are the most abundant. An interleukin-1 receptor antagonist not only attenuated cell death but also abolished lipopolysaccharide-induced NR1 and serine racemase upregulation and increases in D-serine secretion, suggesting that interleukin-1β-mediated NMDA receptor hyperfunction participates in lipopolysaccharide-induced tubular damage. The results of this study indicate NMDA receptor hyperfunction via cytokine effect participates in lipopolysaccharide-induced renal insufficiency. Blockade of NMDA receptors may represent a promising therapeutic strategy for the treatment of sepsis-associated renal failure.

  5. Heteroreceptor Complexes Formed by Dopamine D1, Histamine H3, and N-Methyl-D-Aspartate Glutamate Receptors as Targets to Prevent Neuronal Death in Alzheimer's Disease.

    Science.gov (United States)

    Rodríguez-Ruiz, Mar; Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Mallol, Josefa; Cortés, Antonio; Lluís, Carme; Canela, Enric I; Casadó, Vicent; McCormick, Peter J; Franco, Rafael

    2017-08-01

    Alzheimer's disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D 1 , histamine H 3 , and N-methyl-D-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by co-immunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H 3 receptor agonists, via negative cross-talk, and H 3 receptor antagonists, via cross-antagonism, decreased D 1 receptor agonist signaling determined by ERK1/2 or Akt phosphorylation, and counteracted D 1 receptor-mediated excitotoxic cell death. Both D 1 and H 3 receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D 1 -H 3 receptor heteromer function. Likely due to heteromerization, H 3 receptors act as allosteric regulator for D 1 and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D 1 or H 3 receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D 1 -H 3 -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H 3 receptor antagonists reduced NMDA or D 1 receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H 3 receptor antagonists reverted the toxicity induced by ß 1-42 -amyloid peptide. Thus, histamine H 3 receptors in D 1 -H 3 -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration.

  6. Assessment of structurally diverse philanthotoxin analogues for inhibitory activity on ionotropic glutamate receptor subtypes

    DEFF Research Database (Denmark)

    Frølund, Sidsel; Bella, Angelo; Kristensen, Anders Skov

    2010-01-01

    -electrode voltage-clamp electrophysiology employing Xenopus laevis oocytes expressing GluA1(i) AMPA or GluN1/2A NMDA receptors. Several of the analogues showed significantly increased inhibition of the GluN1/2A NMDA receptor. Thus, an analogue containing N-(1-naphtyl)acetyl group showed an IC(50) value of 47 n...

  7. An investigation of interactions between hypocretin/orexin signaling and glutamate receptor surface expression in the rat nucleus accumbens under basal conditions and after cocaine exposure.

    Science.gov (United States)

    Plaza-Zabala, Ainhoa; Li, Xuan; Milovanovic, Mike; Loweth, Jessica A; Maldonado, Rafael; Berrendero, Fernando; Wolf, Marina E

    2013-12-17

    Hypocretin peptides are critical for the effects of cocaine on excitatory synaptic strength in the ventral tegmental area (VTA). However, little is known about their role in cocaine-induced synaptic plasticity in the nucleus accumbens (NAc). First, we tested whether hypocretin-1 by itself could acutely modulate glutamate receptor surface expression in the NAc, given that hypocretin-1 in the VTA reproduces cocaine's effects on glutamate transmission. We found no effect of hypocretin-1 infusion on AMPA or NMDA receptor surface expression in the NAc, measured by biotinylation, either 30 min or 3h after the infusion. Second, we were interested in whether changes in hypocretin receptor-2 (Hcrtr-2) expression contribute to cocaine-induced plasticity in the NAc. As a first step towards addressing this question, Hcrtr-2 surface expression was compared in the NAc after withdrawal from extended-access self-administration of saline (control) versus cocaine. We found that surface Hcrtr-2 levels remain unchanged following 14, 25 or 48 days of withdrawal from cocaine, a time period in which high conductance GluA2-lacking AMPA receptors progressively emerge in the NAc. Overall, our results fail to support a role for hypocretins in acute modulation of glutamate receptor levels in the NAc or a role for altered Hcrtr-2 expression in withdrawal-dependent synaptic adaptations in the NAc following cocaine self-administration. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Dual effect of 17β-estradiol on NMDA-induced neuronal death: involvement of metabotropic glutamate receptor 1.

    Science.gov (United States)

    Spampinato, Simona Federica; Merlo, Sara; Molinaro, Gemma; Battaglia, Giuseppe; Bruno, Valeria; Nicoletti, Ferdinando; Sortino, Maria Angela

    2012-12-01

    Pretreatment with 10 nm 17β-estradiol (17βE2) or 100 μm of the metabotropic glutamate 1 receptor (mGlu1R) agonist, dihydroxyphenylglycine (DHPG), protected neurons against N-methyl-d-aspartate (NMDA) toxicity. This effect was sensitive to blockade of both estrogen receptors and mGlu1R by their respective antagonists. In contrast, 17βE2 and/or DHPG, added after a low-concentration NMDA pulse (45 μm), produced an opposite effect, i.e. an exacerbation of NMDA toxicity. Again this effect was prevented by both receptor antagonists. In support of an interaction of estrogen receptors and mGlu1R in mediating a neurotoxic response, exacerbation of NMDA toxicity by 17βE2 disappeared when cultures were treated with DHPG prior to NMDA challenge, and conversely, potentiation of NMDA-induced cell death by DHPG was prevented by pretreatment with 17βE2. Addition of calpain III inhibitor (10 μm), 2 h before NMDA, prevented the increased damage induced by the two agonists, an affect that can be secondary to cleavage of mGlu1R by calpain. Accordingly, NMDA stimulation reduced expression of the full-length (140 kDa) mGluR1, an effect partially reversed by calpain inhibitor. Finally, in the presence of NMDA, the ability of 17βE2 to stimulate phosphorylation of AKT and ERK was impaired. Pretreatment with calpain inhibitor prevented the reduction of phosphorylated ERK but had no significant effect on phosphorylated AKT. Accordingly, the inhibition of ERK signaling by U0126 (1 μm) counteracted the effect of calpain inhibition on 17βE2-induced exacerbation of NMDA toxicity. The present data confirm the dual role of estrogens in neurotoxicity/neuroprotection and highlight the role of the timing of exposure to estrogens.

  9. Protection by imidazol(ine) drugs and agmatine of glutamate-induced neurotoxicity in cultured cerebellar granule cells through blockade of NMDA receptor.

    Science.gov (United States)

    Olmos, G; DeGregorio-Rocasolano, N; Paz Regalado, M; Gasull, T; Assumpció Boronat, M; Trullas, R; Villarroel, A; Lerma, J; García-Sevilla, J A

    1999-07-01

    This study was designed to assess the potential neuroprotective effect of several imidazol(ine) drugs and agmatine on glutamate-induced necrosis and on apoptosis induced by low extracellular K+ in cultured cerebellar granule cells. Exposure (30 min) of energy deprived cells to L-glutamate (1-100 microM) caused a concentration-dependent neurotoxicity, as determined 24 h later by a decrease in the ability of the cells to metabolize 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) into a reduced formazan product. L-glutamate-induced neurotoxicity (EC50=5 microM) was blocked by the specific NMDA receptor antagonist MK-801 (dizocilpine). Imidazol(ine) drugs and agmatine fully prevented neurotoxicity induced by 20 microM (EC100) L-glutamate with the rank order (EC50 in microM): antazoline (13)>cirazoline (44)>LSL 61122 [2-styryl-2-imidazoline] (54)>LSL 60101 [2-(2-benzofuranyl) imidazole] (75)>idazoxan (90)>LSL 60129 [2-(1,4-benzodioxan-6-yl)-4,5-dihydroimidazole](101)>RX82 1002 (2-methoxy idazoxan) (106)>agmatine (196). No neuroprotective effect of these drugs was observed in a model of apoptotic neuronal cell death (reduction of extracellular K+) which does not involve stimulation of NMDA receptors. Imidazol(ine) drugs and agmatine fully inhibited [3H]-(+)-MK-801 binding to the phencyclidine site of NMDA receptors in rat brain. The profile of drug potency protecting against L-glutamate neurotoxicity correlated well (r=0.90) with the potency of the same compounds competing against [3H]-(+)-MK-801 binding. In HEK-293 cells transfected to express the NR1-1a and NR2C subunits of the NMDA receptor, antazoline and agmatine produced a voltage- and concentration-dependent block of glutamate-induced currents. Analysis of the voltage dependence of the block was consistent with the presence of a binding site for antazoline located within the NMDA channel pore with an IC50 of 10-12 microM at 0 mV. It is concluded that imidazol(ine) drugs and agmatine are

  10. Differences in glutamate receptors and inflammatory cell numbers are associated with the resolution of pain in human rotator cuff tendinopathy.

    Science.gov (United States)

    Dean, Benjamin John Floyd; Snelling, Sarah J B; Dakin, Stephanie G; Murphy, Richard J; Javaid, Muhammad Kassim; Carr, Andrew Jonathan

    2015-07-10

    The relationship between peripheral tissue characteristics and pain symptoms in soft tissue inflammation is poorly understood. The primary aim of this study was to determine immunohistochemical differences in tissue obtained from patients with persistent pain and patients who had become pain-free after surgical treatment for rotator cuff tendinopathy. The secondary aim was to investigate whether there would be differences in glutaminergic and inflammatory gene expression between disease-derived and healthy control cells in vitro. Supraspinatus tendon biopsies were obtained from nine patients with tendon pain before shoulder surgery and from nine further patients whose pain had resolved completely following shoulder surgery. Histological markers relating to the basic tendon characteristics, inflammation and glutaminergic signalling were quantified by immunohistochemical analysis. Gene expression of glutaminergic and inflammatory markers was determined in tenocyte explants derived from painful rotator cuff tendon tears in a separate cohort of patients and compared to that of explants from healthy control tendons. Dual labelling was performed to identify cell types expressing nociceptive neuromodulators. Tendon samples from patients with persistent pain demonstrated increased levels of metabotropic glutamate receptor 2 (mGluR2), kainate receptor 1 (KA1), protein gene product 9.5 (PGP9.5), CD206 (macrophage marker) and CD45 (pan-leucocyte marker) versus pain-free controls (p shoulder pain in rotator cuff tendinopathy, and that disease-derived cells exhibit a distinctly different neuro-inflammatory gene expression profile to healthy control cells.

  11. Changes in Glutamate/NMDA Receptor Subunit 1 Expression in Rat Brain after Acute and Subacute Exposure to Methamphetamine

    Directory of Open Access Journals (Sweden)

    Walailuk Kerdsan

    2009-01-01

    Full Text Available Methamphetamine (METH is a psychostimulant drug of abuse that produces long-term behavioral changes including behavioral sensitization, tolerance, and dependence. METH has been reported to induce neurotoxic effects in several areas of the brain via the dopaminergic system. Changes of dopamine function can induce malfunction of the glutamatergic system. Therefore, the aim of the present study was to examine the effects of METH administration on the expression of glutamate N-methyl-D-aspartate receptor subunit 1 (NMDAR1 in frontal cortex, striatum, and hippocampal formation after acute and subacute exposure to METH by western blotting. Male Sprague-Dawley rats were injected intraperitoneally with a single dose of 8 mg/kg METH, 4 mg/kg/day METH for 14 days and saline in acute, subacute, and control groups, respectively. A significant increase in NMDAR1 immunoreactive protein was found in frontal cortex in the subacute group (P=.036 but not in the acute group (P=.580. Moreover, a significant increase in NMDAR1 was also observed in striatum in both acute (P=.025 and subacute groups (P=.023. However, no significant differences in NMDAR1 in hippocampal formation were observed in either acute or subacute group. The results suggest that an upregulation of NMDA receptor expression may be a consequence of glutamatergic dysfunction induced by METH.

  12. 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...

  13. Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia-reperfusion injury

    NARCIS (Netherlands)

    Poppelaars, Felix; van Werkhoven, Maaike B; Kotimaa, Juha; Veldhuis, Zwanida J; Ausema, Albertina; Broeren, Stefan G M; Damman, Jeffrey; Hempel, Julia C.; Leuvenink, Henri G D; Daha, Mohamed R; van Son, Willem J; van Kooten, Cees; van Os, Ronald P; Hillebrands, Jan-Luuk; Seelen, Marc A

    The complement system, and specifically C5a, is involved in renal ischemia-reperfusion (IR) injury. The 2 receptors for complement anaphylatoxin C5a (C5aR1 and C5aR2) are expressed on leukocytes as well as on renal epithelium. Extensive evidence shows that C5aR1 inhibition protects kidneys from IR

  14. Complement C5a receptor and polymorphonuclear neutrophils- accomplices in atherosclerotic lesion formation

    OpenAIRE

    Vijayan, Santosh

    2012-01-01

    This study focuses on understanding the role of complement C5a receptors (C5aR and C5L2), release of neutrophil extracellular traps (NETs) and the role of neutrophil granule protein (CRAMP in mouse) in atherosclerosis. Atherosclerosis is agreed to be a chronic inflammatory disease of the arterial vessel wall involving both innate and adaptive immunity. Despite considerable progress in the field of medicine, cardiovascular diseases are a major cause of death world-wide. The complement system i...

  15. 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

    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). 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. 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 (pinflammation (pinflammation after NBQX treatment. NBQX reduced HOB number and prevented mineralisation. AMPA/KA GluRs are expressed in human OA and RA, and in AIA, where a single intra-articular injection of NBQX reduced swelling by 33%, and inflammation and degeneration scores by 34% and 27%, respectively, exceeding the efficacy of approved drugs in the same model. AMPA/KA GluR antagonists represent a potential treatment for arthritis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  16. C5a receptor deficiency alters energy utilization and fat storage.

    Directory of Open Access Journals (Sweden)

    Christian Roy

    Full Text Available To investigate the impact of whole body C5a receptor (C5aR deficiency on energy metabolism and fat storage.Male wildtype (WT and C5aR knockout (C5aRKO mice were fed a low fat (CHOW or a high fat high sucrose diet-induced obesity (DIO diet for 14 weeks. Body weight and food intake were measured weekly. Indirect calorimetry, dietary fatload clearance, insulin and glucose tolerance tests were also evaluated. Liver, muscle and adipose tissue mRNA gene expression were measured by RT-PCR.At week one and 12, C5aRKO mice on DIO had increased oxygen consumption. After 12 weeks, although food intake was comparable, C5aRKO mice had lower body weight (-7% CHOW, -12% DIO as well as smaller gonadal (-38% CHOW, -36% DIO and inguinal (-29% CHOW, -30% DIO fat pads than their WT counterparts. Conversely, in WT mice, C5aR was upregulated in DIO vs CHOW diets in gonadal adipose tissue, muscle and liver, while C5L2 mRNA expression was lower in C5aRKO on both diet. Furthermore, blood analysis showed lower plasma triglyceride and non-esterified fatty acid levels in both C5aRKO groups, with faster postprandial triglyceride clearance after a fatload. Additionally, C5aRKO mice showed lower CD36 expression in gonadal and muscle on both diets, while DGAT1 expression was higher in gonadal (CHOW and liver (CHOW and DIO and PPARγ was increased in muscle and liver.These observations point towards a role (either direct or indirect for C5aR in energy expenditure and fat storage, suggesting a dual role for C5aR in metabolism as well as in immunity.

  17. The complement anaphylatoxin C5a receptor contributes to obese adipose tissue inflammation and insulin resistance.

    Science.gov (United States)

    Phieler, Julia; Chung, Kyoung-Jin; Chatzigeorgiou, Antonios; Klotzsche-von Ameln, Anne; Garcia-Martin, Ruben; Sprott, David; Moisidou, Maria; Tzanavari, Theodora; Ludwig, Barbara; Baraban, Elena; Ehrhart-Bornstein, Monika; Bornstein, Stefan R; Mziaut, Hassan; Solimena, Michele; Karalis, Katia P; Economopoulou, Matina; Lambris, John D; Chavakis, Triantafyllos

    2013-10-15

    Obese adipose tissue (AT) inflammation contributes critically to development of insulin resistance. The complement anaphylatoxin C5a receptor (C5aR) has been implicated in inflammatory processes and as regulator of macrophage activation and polarization. However, the role of C5aR in obesity and AT inflammation has not been addressed. We engaged the model of diet-induced obesity and found that expression of C5aR was significantly upregulated in the obese AT, compared with lean AT. In addition, C5a was present in obese AT in the proximity of macrophage-rich crownlike structures. C5aR-sufficient and -deficient mice were fed a high-fat diet (HFD) or a normal diet (ND). C5aR deficiency was associated with increased AT weight upon ND feeding in males, but not in females, and with increased adipocyte size upon ND and HFD conditions in males. However, obese C5aR(-/-) mice displayed improved systemic and AT insulin sensitivity. Improved AT insulin sensitivity in C5aR(-/-) mice was associated with reduced accumulation of total and proinflammatory M1 macrophages in the obese AT, increased expression of IL-10, and decreased AT fibrosis. In contrast, no difference in β cell mass was observed owing to C5aR deficiency under an HFD. These results suggest that C5aR contributes to macrophage accumulation and M1 polarization in the obese AT and thereby to AT dysfunction and development of AT insulin resistance.

  18. Pregnanolone glutamate, a novel use-dependent NMDA receptor inhibitor, exerts antidepressant-like properties in animal models.

    Directory of Open Access Journals (Sweden)

    Karel eVales

    2014-04-01

    Full Text Available A number of studies demonstrated a rapid onset of an antidepressant effect of non-competitive NMDA receptor antagonists. Nonetheless, its therapeutic potential is rather limited, due to a high coincidence of negative side-effects. Therefore, the challenge seems to be in the development of NMDA receptor (NMDAR antagonists displaying antidepressant properties, and at the same time maintaining regular physiological function of the NMDAR. Previous results demonstrated that naturally occurring neurosteroid 3α5β-pregnanolone sulfate shows pronounced inhibitory action by a use-dependent mechanism on the tonically active NMDAR. The aim of the present experiments is to find out whether the treatment with pregnanolone 3αC derivatives affects behavioral response to chronic and acute stress in an animal model of depression. Adult male mice were used throughout the study. Repeated social defeat and forced swimming tests were used as animal models of depression. The effect of the drugs on the locomotor/exploratory activity in the open-field test was also tested together with an effect on anxiety in the elevated plus maze. Results showed that pregnanolone glutamate (PG did not induce hyperlocomotion, whereas both dizocilpine and ketamine significantly increased spontaneous locomotor activity in the open field. In the elevated plus maze PG displayed anxiolytic-like properties. In forced swimming PG prolonged time to the first floating. Acute treatment of PG disinhibited suppressed locomotor activity in the repeatedly defeated group-housed mice. Aggressive behavior of isolated mice was reduced after the chronic 30-day administration of PG. PG showed antidepressant-like and anxiolytic-like properties in the used tests, with minimal side-effects. Since PG combines GABAA receptor potentiation and use-dependent NMDAR inhibition, synthetic derivatives of neuroactive steroids present a promising strategy for the treatment of mood disorders.

  19. The DAF-7/TGF-β signaling pathway regulates abundance of the C. elegans glutamate receptor GLR-1

    Science.gov (United States)

    McGehee, Annette M.; Moss, Benjamin J.; Juo, Peter

    2015-01-01

    Transforming growth factor-β (TGF-β) family signaling pathways have roles in both neuronal development and the regulation of synaptic function. Here we identify a novel role for the C. elegans DAF-7/TGF-β signaling pathway in the regulation of the AMPA-type glutamate receptor GLR-1. We found that the abundance of GLR-1 increases at synapses in the ventral nerve cord (VNC) of animals with loss-of-function mutations in multiple DAF-7/TGF-β pathway components including the TGF-β ligand DAF-7, the type I receptor DAF-1, and the Smads DAF-8 and DAF-14. The GLR-1 defect can be rescued by expression of daf-8 specifically in glr-1-expressing interneurons. The effect on GLR-1 was specific for the DAF-7 pathway because mutations in the DBL-1/TGF-β family pathway did not increase GLR-1 levels in the VNC. Immunoblot analysis indicates that total levels of GLR-1 protein are increased in neurons of DAF-7/TGF-β pathway mutants. The increased abundance of GLR-1 in the VNC of daf-7 pathway mutants is dependent on the transcriptional regulator DAF-3/Smad suggesting that DAF-3-dependent transcription controls GLR-1 levels. Furthermore, we found that glr-1 transcription is increased in daf-7 mutants based on a glr-1 transcriptional reporter. Together these results suggest that the DAF-7/TGF-β signaling pathway functions in neurons and negatively regulates the abundance of GLR-1, in part, by controlling transcription of the receptor itself. Finally, DAF-7/TGF-β pathway mutants exhibit changes in spontaneous locomotion that are dependent on endogenous GLR-1 and consistent with increased glutamatergic signaling. These results reveal a novel mechanism by which TGF-β signaling functions in the nervous system to regulate behavior. PMID:26054666

  20. The DAF-7/TGF-β signaling pathway regulates abundance of the Caenorhabditis elegans glutamate receptor GLR-1.

    Science.gov (United States)

    McGehee, Annette M; Moss, Benjamin J; Juo, Peter

    2015-07-01

    Transforming growth factor-β (TGF-β) family signaling pathways have roles in both neuronal development and the regulation of synaptic function. Here we identify a novel role for the Caenorhabditis elegans DAF-7/TGF-β signaling pathway in the regulation of the AMPA-type glutamate receptor GLR-1. We found that the abundance of GLR-1 increases at synapses in the ventral nerve cord (VNC) of animals with loss-of-function mutations in multiple DAF-7/TGF-β pathway components including the TGF-β ligand DAF-7, the type I receptor DAF-1, and the Smads DAF-8 and DAF-14. The GLR-1 defect can be rescued by expression of daf-8 specifically in glr-1-expressing interneurons. The effect on GLR-1 was specific for the DAF-7 pathway because mutations in the DBL-1/TGF-β family pathway did not increase GLR-1 levels in the VNC. Immunoblot analysis indicates that total levels of GLR-1 protein are increased in neurons of DAF-7/TGF-β pathway mutants. The increased abundance of GLR-1 in the VNC of daf-7 pathway mutants is dependent on the transcriptional regulator DAF-3/Smad suggesting that DAF-3-dependent transcription controls GLR-1 levels. Furthermore, we found that glr-1 transcription is increased in daf-7 mutants based on a glr-1 transcriptional reporter. Together these results suggest that the DAF-7/TGF-β signaling pathway functions in neurons and negatively regulates the abundance of GLR-1, in part, by controlling transcription of the receptor itself. Finally, DAF-7/TGF-β pathway mutants exhibit changes in spontaneous locomotion that are dependent on endogenous GLR-1 and consistent with increased glutamatergic signaling. These results reveal a novel mechanism by which TGF-β signaling functions in the nervous system to regulate behavior. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Sex-specific effects of prenatal chronic mild stress on adult spatial learning capacity and regional glutamate receptor expression profiles.

    Science.gov (United States)

    Wang, Yan; Ma, Yuchao; Hu, Jingmin; Zhang, Xinxin; Cheng, Wenwen; Jiang, Han; Li, Min; Ren, Jintao; Zhang, Xiaosong; Liu, Mengxi; Sun, Anji; Wang, Qi; Li, Xiaobai

    2016-07-01

    Both animal experiments and clinical studies have demonstrated that prenatal stress can cause cognitive disorders in offspring. To explore the scope of these deficits and identify potential underlying mechanisms, we examined the spatial learning and memory performance and glutamate receptor (GluR) expression patterns of adult rats exposed to prenatal chronic mild stress (PCMS). Principal component analysis (PCA) was employed to reveal the interrelationships among spatial learning indices and GluR expression changes. Female PCMS-exposed offspring exhibited markedly impaired spatial learning and memory in the Morris water maze (MWM) task compared to control females, while PCMS-exposed males showed better initial spatial learning in the MWM compared to control males. PCMS also altered basal and post-MWM glutamate receptor expression patterns, but these effects differed markedly between sexes. Male PCMS-exposed offspring exhibited elevated basal expression of NR1, mGluR5, and mGluR2/3 in the prefrontal cortex (PFC), whereas females showed no basal expression changes. Following MWM training, PCMS-exposed males expressed higher NR1 in the PFC and mammillary body (MB), higher mGluR2/3 in PFC, and lower NR2B in the hippocampus (HIP), PFC, and MB compared to unstressed MWM-trained males. Female PCMS-exposed offspring showed strongly reduced NR1 in MB and NR2B in the HIP, PFC, and MB, and increased mGluR2/3 in PFC compared to unstressed MWM-trained females. This is the first report suggesting that NMDA subunits in the MB are involved in spatial learning. Additionally, PCA further suggests that the NR1-NR2B form is the most important for spatial memory formation. These results reveal long-term sex-specific effects of PCMS on spatial learning and memory performance in adulthood and implicate GluR expression changes within HIP, PFC, and MB as possible molecular mechanisms underlying cognitive dysfunction in offspring exposed to prenatal stress. Copyright © 2016 Elsevier Inc

  2. Investigating the expression of metabotropic glutamate receptors in trigeminal ganglion neurons and satellite glial cells: implications for craniofacial pain.

    Science.gov (United States)

    Boye Larsen, Dennis; Ingemann Kristensen, Gunda; Panchalingam, Vinodenee; Laursen, Jens Christian; Nørgaard Poulsen, Jeppe; Skallerup Andersen, Maria; Kandiah, Aginsha; Gazerani, Parisa

    2014-08-01

    Previous studies have demonstrated that various subtypes of the metabotropic glutamate receptors (mGluRs) are expressed in the dorsal root ganglion (DRG) of the peripheral nervous system (PNS), implicating that glutamate potentially contributes to sensory transmission through these receptors. While mGluR expression has been investigated largely in the DRG, the present study focused on mGluR expression on neurons and satellite glial cells (SGCs) of the trigeminal ganglion (TG). To address the presence of mGluRs in rat TG neurons and their corresponding SGCs, the trigeminal ganglia from six adult male Wistar rats were isolated and immunohistochemistry and immunocytochemistry were performed. The expression of mGluR1α-, mGluR2/3- and mGluR8 on TG neurons and SGCs was investigated in tissue slices and isolated cells. 35.1 ± 6.0% of the TG neurons were positive for mGluR1α, whereas 39.9 ± 7.7% and 55.5 ± 6.3% were positive for mGluR2/3 and mGluR8, respectively. Immunoreactive neurons expressing mGluRs were mainly medium- to large sized, with a smaller population of small-sized neurons showing immunoreactivity. The SGCs showed immunoreactivity toward mGluR1α and mGluR8, but not mGluR2/3, both in the tissue and in isolated cells. Findings from the present study showed that trigeminal neurons express mGluR1α, mGluR2/3 and mGluR8, while SGCs only express mGluR1α and mGluR8. This novel evidence may advance investigations on a possible role of mGluRs in relation to trigeminal pain transmission within the craniofacial region.

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

    Science.gov (United States)

    Krintel, Christian; Francotte, Pierre; Pickering, Darryl S; Juknaitė, Lina; Pøhlsgaard, Jacob; Olsen, Lars; Frydenvang, Karla; Goffin, Eric; Pirotte, Bernard; Kastrup, Jette S

    2016-06-07

    The 1,2,4-benzothiadiazine 1,1-dioxide type of positive allosteric modulators of the ionotropic glutamate receptor A2 (GluA2) are promising lead compounds for the treatment of cognitive disorders, e.g., Alzheimer's disease. The modulators bind in a cleft formed by the interface of two neighboring ligand binding domains and act by stabilizing the agonist-bound open-channel conformation. The driving forces behind the binding of these modulators can be significantly altered with only minor substitutions to the parent molecules. In this study, we show that changing the 7-fluorine substituent 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 -0.5 (4) and 4.8 (5). Thus, the dissociation constants (Kd, μM) of 4 (11.2) and 5 (0.16) are similar to those of 2 (5.6) and 3 (0.35). Functionally, 4 and 5 potentiated responses of 10 μM L-glutamate at homomeric rat GluA2(Q)i receptors with EC50 values of 67.3 and 2.45 μM, respectively. The binding mode 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-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 of the underlying structural mechanism. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  4. Selective Disruption of Metabotropic Glutamate Receptor 5-Homer Interactions Mimics Phenotypes of Fragile X Syndrome in Mice.

    Science.gov (United States)

    Guo, Weirui; Molinaro, Gemma; Collins, Katie A; Hays, Seth A; Paylor, Richard; Worley, Paul F; Szumlinski, Karen K; Huber, Kimberly M

    2016-02-17

    Altered function of the Gq-coupled, Group 1 metabotropic glutamate receptors, specifically mGlu5, is implicated in multiple mouse models of autism and intellectual disability. mGlu5 dysfunction has been most well characterized in the fragile X syndrome mouse model, the Fmr1 knock-out (KO) mouse, where pharmacological and genetic reduction of mGlu5 reverses many phenotypes. mGlu5 is less associated with its scaffolding protein Homer in Fmr1 KO mice, and restoration of mGlu5-Homer interactions by genetic deletion of a short, dominant negative of Homer, H1a, rescues many phenotypes of Fmr1 KO mice. These results suggested that disruption of mGlu5-Homer leads to phenotypes of FXS. To test this idea, we examined mice with a knockin mutation of mGlu5 (F1128R; mGlu5(R/R)) that abrogates binding to Homer. Although FMRP levels were normal, mGlu5(R/R) mice mimicked multiple phenotypes of Fmr1 KO mice, including reduced mGlu5 association with the postsynaptic density, enhanced constitutive mGlu5 signaling to protein synthesis, deficits in agonist-induced translational control, protein synthesis-independent LTD, neocortical hyperexcitability, audiogenic seizures, and altered behaviors, including anxiety and sensorimotor gating. These results reveal new roles for the Homer scaffolds in regulation of mGlu5 function and implicate a specific molecular mechanism in a complex brain disease. Abnormal function of the metabotropic, or Gq-coupled, glutamate receptor 5 (mGlu5) has been implicated in neurodevelopmental disorders, including a genetic cause of intellectual disability and autism called fragile X syndrome. In brains of a mouse model of fragile X, mGlu5 is less associated with its binding partner Homer, a scaffolding protein that regulates mGlu5 localization to synapses and its ability to activate biochemical signaling pathways. Here we show that a mouse expressing a mutant mGlu5 that cannot bind to Homer is sufficient to mimic many of the biochemical, neurophysiological, and

  5. Glutamate mediates the function of melanocortin receptor 4 on sim1 neurons in body weight regulation

    Science.gov (United States)

    The melanocortin receptor 4 (MC4R) is a well-established mediator of body weight homeostasis. However, the neurotransmitter(s) that mediate MC4R function remain largely unknown; as a result, little is known about the second-order neurons of the MC4R neural pathway. Single-minded 1 (Sim1)-expressing ...

  6. 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) ...

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

    African Journals Online (AJOL)

    Muhammad Zahid Khan

    2016-10-20

    Oct 20, 2016 ... pyramidal neurons.10,34,33 Original studies of delta subunits. mRNA distribution in the .... Figure 2. Signaling pathway of GluD1 receptor in the pyramidal neurons in medial prefrontal cortex (mPFC) and hippocampus. A ... year Plan ''Major Scientific and Technological Special Project for Significant New ...

  8. Rapid glucocorticoid-induced activation of TRP and CB1 receptors causes biphasic modulation of glutamate release in gastric-related hypothalamic preautonomic neurons

    Directory of Open Access Journals (Sweden)

    Carie R. Boychuk

    2013-01-01

    Full Text Available Glucocorticoids rapidly regulate synaptic input to neuroendocrine cells in the hypothalamic paraventricular nucleus (PVN by inducing the retrograde release of endogenous messengers. Here we investigated the rapid effects of dexamethasone (DEX on excitatory synaptic input to feeding-related, preautonomic PVN neurons using whole-cell patch-clamp recordings. In ~50% of identified gastric-related preautonomic PVN neurons, DEX elicited a biphasic synaptic response characterized by an initial rapid and transient increase in the frequency of miniature excitatory postsynaptic currents (mEPSCs, followed by a decrease in mEPSC frequency within 9 min; remaining cells displayed only a decrease in mEPSC frequency. The late-phase decrease in mEPSC frequency was mimicked by the cannabinoid receptor agonists anandamide and WIN 55,212-2, and it was blocked by the CB1 receptor antagonist AM251. The biphasic DEX effect was mimicked by anandamide (AEA. The early increase in mEPSCs was mimicked by activation of transient receptor potential vanilloid type 1 (TRPV1 receptors with capsaicin and by activation of TRPV4 receptors with 4-α-PDD. The increase was reduced, but not blocked, by selective TRPV1 antagonists and in TRPV1-knockout mice; it was blocked completely by the broad-spectrum TRPV antagonist ruthenium red and by combined application of selective TRPV1 and TRPV4 antagonists. The DEX effects were prevented entirely by intracellular infusion of the G-protein inhibitor, GDPβS. Thus, DEX biphasically modulates synaptic glutamate onto a subset of gastric-related PVN neurons, which is likely mediated by induction of a retrograde messenger. The effect includes a TRPV1/4 receptor-mediated transient increase and subsequent CB1 receptor-mediated suppression of glutamate release. Multiphasic modulation of glutamate input to PVN neurons represents a previously unappreciated complexity of control of autonomic output by glucocorticoids and eCBs.

  9. Blockade of group II metabotropic glutamate receptors produces hyper-locomotion in cocaine pre-exposed rats by interactions with dopamine receptors.

    Science.gov (United States)

    Yoon, Hyung Shin; Jang, Ju Kyong; Kim, Jeong-Hoon

    2008-09-01

    It was previously reported that blockade of group II metabotropic glutamate receptors (mGluRs) produces hyper-locomotion in rats previously exposed to amphetamine, indicating that group II mGluRs are well positioned to modulate the expression of behavioral sensitization by amphetamine. The present study further examined the locomotor activating effects of specific blockade of these receptors after cocaine pre-exposures. First, rats were pre-exposed to seven daily injections of cocaine (15mg/kg, IP). When challenged the next day with an injection of either saline or the group II mGluR antagonist LY341495 (0.5, 1.0 or 2.5mg/kg, IP), they produced hyper-locomotor activity, measured by infrared beam interruptions, to LY341495 compared to saline in a dose-dependent manner. Second, rats were pre-exposed to either saline or seven daily injections of cocaine (15mg/kg, IP). Three weeks later, when they were challenged with an injection of either saline or LY341495 (1.0mg/kg, IP), only rats pre-exposed to cocaine produced hyper-locomotor activity to LY341495 compared to saline. These effects, however, were not present when dopamine D1 (SCH23390; 5 or 10microg/kg), but not D2 (eticlopride; 10 or 50microg/kg), receptor antagonist was pre-injected, indicating that this cocaine-induced hyper-locomotor activity to LY341495 may be mediated in dopamine D1 receptor-dependent manner. These results suggest that group II mGluRs may be adapted to interact with dopaminergic neuronal signaling in mediating the sensitized locomotor activity produced by repeated cocaine pre-exposures.

  10. Synthesis and pharmacological characterization at glutamate receptors of the four enantiopure isomers of tricholomic acid

    DEFF Research Database (Denmark)

    Pinto, Andrea; Conti, Paola; De Amici, Marco

    2008-01-01

    The two enantiomeric pairs of erythro- and threo-amino-(3'-hydroxy-4',5'-dihydro-isoxazol-5'-yl)-acetic acids were synthesized via the 1,3-dipolar cycloaddition of bromonitrile oxide to ( R)- or ( S)-3-( tert-butoxycarbonyl)-2,2-dimethyl-4-vinyloxazolidine. The pharmacological profiles of the stu......The two enantiomeric pairs of erythro- and threo-amino-(3'-hydroxy-4',5'-dihydro-isoxazol-5'-yl)-acetic acids were synthesized via the 1,3-dipolar cycloaddition of bromonitrile oxide to ( R)- or ( S)-3-( tert-butoxycarbonyl)-2,2-dimethyl-4-vinyloxazolidine. The pharmacological profiles...... of the studied amino acids reflect the relationship between the activity/selectivity and the stereochemistry of the two stereogenic centers: while the (2 S,5' S) stereoisomer is an agonist at the AMPA and KA receptors, its (2 R,5' R) enantiomer interacts selectively with the NMDA receptors; the (2 S,5' R...

  11. 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

    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...... for any of the receptor subtypes, the results demonstrate that each of these structurally related compounds has a distinct pharmacological profile....

  12. Plasticity of Signaling by Spinal Estrogen Receptor α, κ-Opioid Receptor, and Metabotropic Glutamate Receptors over the Rat Reproductive Cycle Regulates Spinal Endomorphin 2 Antinociception: Relevance of Endogenous-Biased Agonism.

    Science.gov (United States)

    Liu, Nai-Jiang; Murugaiyan, Vijaya; Storman, Emiliya M; Schnell, Stephen A; Kumar, Arjun; Wessendorf, Martin W; Gintzler, Alan R

    2017-11-15

    We previously showed that intrathecal application of endomorphin 2 [EM2; the highly specific endogenous μ-opioid receptor (MOR) ligand] induces antinociception that varies with stage of the rat estrous cycle: minimal during diestrus and prominent during proestrus. Earlier studies, however, did not identify proestrus-activated signaling strategies that enable spinal EM2 antinociception. We now report that in female rats, increased spinal dynorphin release and κ-opioid receptor (KOR) signaling, as well as the emergence of glutamate-activated metabotropic glutamate receptor 1 (mGluR 1 ) signaling, are critical to the transition from an EM2 nonresponsive state (during diestrus) to an analgesically responsive state (during proestrus). Differential signaling by mGluR 1 , depending on its activation by membrane estrogen receptor α (mERα; during diestrus) versus glutamate (during proestrus), concomitant with the ebb and flow of spinal dynorphin/KOR signaling, functions as a switch, preventing or promoting, respectively, spinal EM2 antinociception. Importantly, EM2 and glutamate-containing varicosities appose spinal neurons that express MOR along with mGluRs and mERα, suggesting that signaling mechanisms regulating analgesic effectiveness of intrathecally applied EM2 also pertain to endogenous EM2. Regulation of spinal EM2 antinociception by both the nature of the endogenous mGluR 1 activator (i.e., endogenous biased agonism at mGluR 1 ) and changes in spinal dynorphin/KOR signaling represent a novel mechanism for modulating analgesic responsiveness to endogenous EM2 (and perhaps other opioids). This points the way for developing noncanonical pharmacological approaches to pain management by harnessing endogenous opioids for pain relief. SIGNIFICANCE STATEMENT The current prescription opioid abuse epidemic underscores the urgency to develop alternative pharmacotherapies for managing pain. We find that the magnitude of spinal endomorphin 2 (EM2) antinociception not only

  13. Imaging for metabotropic glutamate receptor subtype 1 in rat and monkey brains using PET with [{sup 18}F]FITM

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, Tomoteru [National Institute of Radiological Sciences, Molecular Imaging Centre, Chiba (Japan); Tohoku University, Graduate School of Pharmaceutical Sciences, Sendai (Japan); Fujinaga, Masayuki; Maeda, Jun; Kawamura, Kazunori; Yui, Joji; Hatori, Akiko; Nagai, Yuji; Tokunaga, Masaki; Higuchi, Makoto; Suhara, Tetsuya; Fukumura, Toshimitsu [National Institute of Radiological Sciences, Molecular Imaging Centre, Chiba (Japan); Yoshida, Yuichiro [SHI Accelerator Service Co. Ltd., Tokyo (Japan); Zhang, Ming-Rong [National Institute of Radiological Sciences, Molecular Imaging Centre, Chiba (Japan); National Institute of Radiological Sciences, Department of Molecular Probes, Molecular Imaging Centre, Chiba (Japan)

    2012-04-15

    In this study, we evaluate the utility of 4-[{sup 18}F]fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide ([{sup 18}F]FITM) as a positron emission tomography (PET) ligand for imaging of the metabotropic glutamate receptor subtype 1 (mGluR1) in rat and monkey brains. In vivo distribution of [{sup 18}F]FITM in brains was evaluated by PET scans with or without the mGluR1-selective antagonist (JNJ16259685). Kinetic parameters of monkey PET data were obtained using the two-tissue compartment model with arterial blood sampling. In PET studies in rat and monkey brains, the highest uptake of radioactivity was in the cerebellum, followed by moderate uptake in the thalamus, hippocampus and striatum. The lowest uptake of radioactivity was detected in the pons. These uptakes in all brain regions were dramatically decreased by pre-administration of JNJ16259685. In kinetic analysis of monkey PET, the highest volume of distribution (V{sub T}) was detected in the cerebellum (V{sub T} = 11.5). [{sup 18}F ]FITM has an excellent profile as a PET ligand for mGluR1 imaging. PET with [{sup 18}F ]FITM may prove useful for determining the regional distribution and density of mGluR1 and the mGluR1 occupancy of drugs in human brains. (orig.)

  14. Evaluation of [{sup 3}H]LY341495 for labeling group II metabotropic glutamate receptors in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Waterhouse, Rikki N. E-mail: rnw7@columbia.edu; Schmidt, Mark E.; Sultana, Abida; Schoepp, Darryle D.; Wheeler, William J.; Mozley, P. David; Laruelle, Marc

    2003-02-01

    New glutamatergic drugs are being developed as potential therapies for neurodegenerative disorders, anxiety disorders, and psychoses. The development of effective mGluR radiotracers would provide essential tools with which to probe these sites in living humans, providing critical information about certain disease processes involving the glutamaterigic system and its regulation in humans. As a first step towards this goal, the tritiated form of the high affinity group II metabotropic glutamate receptor (mGluR) antagonist LY341495 [K{sub D} (mGluR{sub 2}) = 1.67{+-}0.20 nM, K{sub D} (mGluR{sub 3})=0.75{+-}0.43 nM] was evaluated to determine its potential to label mGluRs in vivo. Dissection analysis of the regional brain distribution over time of [{sup 3}H]LY341495 in male rats revealed low brain uptake and no significant demonstrable saturable binding of this tracer. A group II mGluR tracer possessing higher affinity than [{sup 3}H]LY341495 and an absence of carboxylic acid groups is likely required for in vivo PET imaging purposes.

  15. Integrative Model for Differential Signaling Pathways of the Ionotropic Glutamate Receptor Activated by N-methyl-D-aspartate

    Directory of Open Access Journals (Sweden)

    Sonia Luz Albarracín, MSc

    2007-09-01

    Full Text Available The ionotropic glutamate receptor activated byN-methyl-D-aspartate (iGluR-NMDA is amultiheteromeric complex constituted from bythree to five subunits belonging to by threedifferent kinds of subunits known as NR1, NR2ADy NR3A y B. It is well established the participationof iGluR-NMDA complexes in a broadrange of physiological, pathological, and as intermediaryin pharmacological processes of neuralsystems.In the CNS, iGluR-NMDA participates inlearning, memory, plasticity, neural differentiation,neural migration, and apoptosis, amongothers. In addition, from the pharmacologicalpoint of view the iGluR-NMDA is playing a rolein excitotoxicity, drugs-addiction and otherdependences. How the same complex can participatein a significant broad group of neuralactivities is a valid question after a literaturereview.A carefully analysis shows that iGluR-NMDAinteracts, at some level, with a big number ofintracellular proteins belonging to signaling proteinsfamily, support proteins, modulatorproteins, cytoskeleton, and enzymes, resultingin interactions with more than a 160 proteins, atdifferent interaction levels and acting with intracellularproteins.In this work we report a proposal for amodel of differential signaling cascade pathwaysgenerated by the iGluR-NMDA gating.The model shows at least the possibility of threedifferent signaling pathways.

  16. Involvement of NMDA glutamate receptors in the acquisition and reinstatement of the conditioned place preference induced by MDMA.

    Science.gov (United States)

    García-Pardo, Maria P; Escobar-Valero, Carla; Rodríguez-Arias, Marta; Miñarro, Jose; Aguilar, Maria A

    2015-08-01

    Some 3,4-methylenedioxymethamphetamine (MDMA) users become dependent as a result of chronic consumption. A greater understanding of the neurobiological basis of the rewarding effects of MDMA could contribute to developing effective pharmacotherapies for MDMA-related problems. The present study evaluated the role of N-methyl-D-aspartate (NMDA) glutamate receptors (NMDARs) in the acquisition and reinstatement of conditioned place preference (CPP) induced by MDMA. Adolescent male mice were conditioned with 1 or 10 mg/kg MDMA and pretreated with 5 or 10 mg/kg of the NMDAR antagonist memantine during acquisition of conditioning (experiment 1), or before a reinstatement test (experiment 2). In addition, the effects of memantine on acquisition of chocolate-induced CPP and the effects of memantine and MDMA on a passive avoidance task were evaluated. Memantine did not exert any motivational effects, but blocked the acquisition of MDMA-induced CPP. Moreover, following acquisition and extinction of MDMA-induced CPP, memantine did not induce reinstatement but blocked reinstatement of the CPP induced by priming with MDMA. Memantine did not block the CPP induced by chocolate, and it partially reversed the impairing effects of MDMA on memory. Our results demonstrate that NMDARs are involved in acquisition of the conditioned rewarding effects of MDMA and in priming-induced reinstatement of CPP following extinction. Moreover, they suggest the validity of memantine for the treatment of MDMA abuse.

  17. Defense reaction induced by a metabotropic glutamate receptor agonist microinjected into the dorsal periaqueductal gray of rats

    Directory of Open Access Journals (Sweden)

    M.L. Molchanov

    1999-12-01

    Full Text Available The behavioral effects of trans-(±-1-amino-1,3-cyclopentanedicarboxylic acid (t-ACPD, a metabotropic glutamate receptor (mGluR agonist, or 0.9% (w/v saline, injected into the dorsal periaqueductal gray (DPAG, was investigated. Male Wistar rats showed defense reactions characterized by jumps toward the top edges of the cages (saline = 0 vs t-ACPD = 6.0, medians P<0.05 and gallops (saline = 0 vs t-ACPD = 10.0, medians P<0.05 during the 60-s period after the beginning of the injection. In another experiment animals were placed inside an open arena for 5 min immediately after injection. Their behavior was recorded by a video camera and a computer program analyzed the videotapes. Eleven of fifteen rats injected with t-ACPD showed a short-lasting (about 1 min flight reaction. No saline-treated animal showed this reaction (P<0.0005, chi-square test. The drug induced an increase in turning behavior (P = 0.002, MANOVA and a decrease in the number of rearings (P<0.001, MANOVA and grooming episodes (P<0.001, MANOVA. These results suggest that mGluRs play a role in the control of defense reactions in the DPAG.

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

    Science.gov (United States)

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

    2007-02-15

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

  19. The role of metabotropic glutamate receptor 5 in the pathogenesis of mood disorders and addiction:Combining preclinical evidence with human Positron Emission Tomography (PET studies

    Directory of Open Access Journals (Sweden)

    Sylvia eTerbeck

    2015-03-01

    Full Text Available In the present review, we deliver an overview of the involvement of metabotropic glutamate receptor 5 (mGluR5 activity and density in pathological anxiety, mood disorders and addiction. Specifically, we will describe mGluR5 studies in humans that employed Positron Emission Tomography (PET and combined the findings with preclinical animal research. This combined view of different methodological approaches — from basic neurobiological approaches to human studies — might give a more comprehensive and clinically relevant view of mGluR5 function in mental health than the view on preclinical data alone. We will also review the current research data on mGluR5 along the Research Domain Criteria (RDoC. Firstly, we found evidence of abnormal glutamate activity related to the positive and negative valence systems, which would suggest that antagonistic mGluR5 intervention has prominent anti-addictive, anti-depressive and anxiolytic effects. Secondly, there is evidence that mGluR5 plays in important role in systems for social functioning and the response to social stress. Finally, mGluR5’s important role in sleep homeostasis suggests that this glutamate receptor may play an important role in RDoC’s arousal and modulatory systems domain. Glutamate was previously mostly investigate in non-human studies, however initial human clinical PET research now also supports the hypothesis that, by mediating brain excitability, neuroplasticity and social cognition, abnormal metabotropic glutamate activity might predispose individuals to a broad range of psychiatric problems.

  20. Structure-activity relationship studies of N-methylated and N-hydroxylated spider polyamine toxins as inhibitors of ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Nørager, Niels G; Poulsen, Mette H; Jensen, Anna G

    2014-01-01

    Polyamine toxins from spiders and wasps are potent open-channel blockers of ionotropic glutamate (iGlu) receptors. It is well-established that secondary amino groups in the polyamine moiety of these toxins are key to both selectivity and potency at iGlu receptors, still some native spider polyamine...... toxins comprise both N-methyl and N-hydroxy functionalities. Here, we investigate the effect of both N-methylation and N-hydroxylation of spider polyamine toxins by the synthesis and biological evaluation of the naturally occurring N-methylated argiopinines and pseudoargiopinines I and II, N...

  1. 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...

  2. 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 recepto...

  3. Chemoenzymatic synthesis of new 2,4-syn-functionalized (S)-glutamate analogues and structure-activity relationship studies at ionotropic glutamate receptors and excitatory amino acid transporters.

    Science.gov (United States)

    Assaf, Zeinab; Larsen, Anja P; Venskutonytė, Raminta; Han, Liwei; Abrahamsen, Bjarke; Nielsen, Birgitte; Gajhede, Michael; Kastrup, Jette S; Jensen, Anders A; Pickering, Darryl S; Frydenvang, Karla; Gefflaut, Thierry; Bunch, Lennart

    2013-02-28

    In the mammalian central nervous system, (S)-glutamate (Glu) is released from the presynaptic neuron where it activates a plethora of pre- and postsynaptic Glu receptors. The fast acting ionotropic Glu receptors (iGluRs) are ligand gated ion channels and are believed to be involved in a vast number of neurological functions such as memory and learning, synaptic plasticity, and motor function. The synthesis of 14 enantiopure 2,4-syn-Glu analogues 2b-p is accessed by a short and efficient chemoenzymatic approach starting from readily available cyclohexanone 3. Pharmacological characterization at the iGluRs and EAAT1-3 subtypes revealed analogue 2i as a selective GluK1 ligand with low nanomolar affinity. Two X-ray crystal structures of the key analogue 2i in the ligand-binding domain (LBD) of GluA2 and GluK3 were determined. Partial domain closure was seen in the GluA2-LBD complex with 2i comparable to that induced by kainate. In contrast, full domain closure was observed in the GluK3-LBD complex with 2i, similar to that of GluK3-LBD with glutamate bound.

  4. Selective enhancement of glutamate-mediated pressor responses after GABAA receptor blockade in the RVLM of sedentary versus spontaneous wheel running rats

    Science.gov (United States)

    Mueller, Patrick J.; Mischel, Nicholas A.

    2012-01-01

    Overactivity of the sympathetic nervous system (SNS) is a hallmark of many cardiovascular diseases. It is also well-known that physical inactivity independently contributes to cardiovascular diseases, likely in part via increased SNS activity. Recent work from our laboratory has demonstrated increased SNS responses in sedentary animals following either direct activation or disinhibition of the rostral ventrolateral medulla (RVLM), an integral cardiovascular brainstem region. These data led us to hypothesize that the interaction between excitation and inhibition of the RVLM is altered in sedentary versus physically active animals. To test this hypothesis, we recorded mean arterial pressure (MAP) and lumbar sympathetic nerve activity (LSNA) in Inactin anesthetized rats that were housed for 8–12 weeks with or without access to a running wheel. Pressor responses to direct activation of the RVLM with glutamate were similar between groups under intact conditions. However, blockade of γ-aminobutyric acid (GABA)A receptors with bicuculline selectively enhanced pressor responses to glutamate in sedentary animals. Interestingly, LSNA responses to glutamate were not enhanced in sedentary versus active animals in the presence or absence of tonic GABAergic tone. These results suggest that sedentary compared to active conditions enhance GABAergic inhibition of glutamate-sensitive neurons in the RVLM that are involved in blood pressure regulation, and by mechanisms that do not involve LSNA. We also speculate that regular physical activity has differential effects on SNS activity to specific vascular beds and may reduce the risk of developing cardiovascular diseases via changes occurring in the RVLM. PMID:23189062

  5. Rigid nonproteinogenic cyclic amino acids as ligands for glutamate receptors: trans-tris(homoglutamic) acids

    DEFF Research Database (Denmark)

    Meyer, Udo; Bisel, Philippe; Bräuner-Osborne, Hans

    2005-01-01

    of the trans-1S,2R-configured secondary alpha-amino amido-ester. In receptor binding assays and functional tests, trans-1S,2R-1-amino-2-carboxymethylcyclopentanecarboxylic acid hydrochloride was found to behave as a selective mGluR(2)-antagonist without relevant binding properties at iGluRs.......The second-generation asymmetric synthesis of the trans-tris(homoglutamic) acids reported herein proceeds via Strecker reaction of chiral ketimines, obtained from condensation of racemic 2-ethoxycarbonylmethylcyclopentanone and commercially available (S)- and (R)-1-phenylethylamine, respectively......) yielded diastereomeric mixtures of secondary alpha-amino amido-esters, which after separation were hydrogenolyzed and hydrolyzed each to the enantiomeric trans-1-amino-2-carboxymethylcyclopentanecarboxylic acids. Their configuration was completely established by NMR methods, CD spectra, and X-ray analysis...

  6. Coordinated activation of distinct Ca2+ sources and metabotropic glutamate receptors encodes Hebbian synaptic plasticity

    Science.gov (United States)

    Tigaret, Cezar M.; Olivo, Valeria; Sadowski, Josef H.L.P.; Ashby, Michael C.; Mellor, Jack R.

    2016-01-01

    At glutamatergic synapses, induction of associative synaptic plasticity requires time-correlated presynaptic and postsynaptic spikes to activate postsynaptic NMDA receptors (NMDARs). The magnitudes of the ensuing Ca2+ transients within dendritic spines are thought to determine the amplitude and direction of synaptic change. In contrast, we show that at mature hippocampal Schaffer collateral synapses the magnitudes of Ca2+ transients during plasticity induction do not match this rule. Indeed, LTP induced by time-correlated pre- and postsynaptic spikes instead requires the sequential activation of NMDARs followed by voltage-sensitive Ca2+ channels within dendritic spines. Furthermore, LTP requires inhibition of SK channels by mGluR1, which removes a negative feedback loop that constitutively regulates NMDARs. Therefore, rather than being controlled simply by the magnitude of the postsynaptic calcium rise, LTP induction requires the coordinated activation of distinct sources of Ca2+ and mGluR1-dependent facilitation of NMDAR function. PMID:26758963

  7. Transient focal ischemia results in persistent and widespread neuroinflammation and loss of glutamate NMDA receptors

    Energy Technology Data Exchange (ETDEWEB)

    Dhawan, J.; Biegon, A.; Dhawan, J.; Benveniste, H.; Nawrocky, M.; Smith, S.D.; Biegon, A.

    2010-03-04

    Stroke is accompanied by neuroinflammation in humans and animal models. To examine the temporal and anatomical profile of neuroinflammation and NMDA receptors (NMDAR) in a stroke model, rats (N = 17) were subjected to a 90 min occlusion of the middle cerebral artery (MCAO) and compared to sham (N = 5) and intact (N = 4) controls. Striatal and parietal cortical infarction was confirmed by MRI 24 h after reperfusion. Animals were killed 14 or 30-40 days later and consecutive coronal cryostat sections were processed for quantitative autoradiography with the neuroinflammation marker [{sup 3}H]PK11195 and the NMDAR antagonist [{sup 3}H]MK801. Significantly increased specific binding of [{sup 3}H]PK11195 relative to non-ischemic controls was observed in the ipsilateral striatum (> 3 fold, p < 0.0001), substantia innominata (> 2 fold) with smaller (20%-80%) but statistically significant (p = 0.002-0.04) ipsilateral increases in other regions partially involved in the infarct such as the parietal and piriform cortex, and in the lateral septum, which was not involved in the infarct. Trends for increases in PBR density were also observed in the contralateral hemisphere. In the same animals, NMDAR specific binding was significantly decreased bilaterally in the septum, substantia innominata and ventral pallidum. Significant decreases were also seen in the ipsilateral striatum, accumbens, frontal and parietal cortex. The different anatomical distribution of the two phenomena suggests that neuroinflammation does not cause the observed reduction in NMDAR, though loss of NMDAR may be locally augmented in ipsilateral regions with intense neuroinflammation. Persistent, bilateral loss of NMDAR, probably reflecting receptor down regulation and internalization, may be responsible for some of the effects of stroke on cognitive function which cannot be explained by infarction alone.

  8. METABOTROPIC GLUTAMATE TYPE 5, DOPAMINE D2 AND ADENOSINE A2A RECEPTORS FORM HIGHER-ORDER OLIGOMERS IN LIVING CELLS

    Science.gov (United States)

    Cabello, Nuria; Gandía, Jorge; Bertarelli, Daniela C. G.; Watanabe, Masahiko; Lluís, Carme; Franco, Rafael; Ferré, Sergi; Luján, Rafael; Ciruela, Francisco

    2009-01-01

    G protein-coupled receptors are known to form homo- and heteromers at the plasma membrane, but the stoichiometry of these receptor oligomers are relatively unknown. Here, by using bimolecular fluorescence complementation, we visualized for the first time the occurrence of heterodimers of metabotropic glutamate mGlu5 receptors (mGlu5R) and dopamine D2 receptors (D2R) in living cells. Furthermore, the combination of bimolecular fluorescence complementation and bioluminescence resonance energy transfer techniques, as well as the sequential resonance energy transfer (SRET) technique, allowed us to detect the occurrence receptor oligomers containing more than two protomers, mGlu5R, D2R and adenosine A2A receptor (A2AR). Interestingly, by using high-resolution immunoelectron microscopy we could confirm that the three receptors co-distribute within the extrasynaptic plasma membrane of the same dendritic spines of asymmetrical, putative glutamatergic, striatal synapses. Also, co-immunoprecipitation experiments in native tissue demonstrated the existence of an association of mGlu5R, D2R and A2AR in rat striatum homogenates. Overall, these results provide new insights into the molecular composition of G protein-coupled receptor oligomers in general and the mGlu5R/D2R/A2AR oligomer in particular, a receptor oligomer that might constitute an important target for the treatment of some neuropsychiatric disorders. PMID:19344374

  9. Plasticity of calcium-permeable AMPA glutamate receptors in Pro-opiomelanocortin neurons.

    Science.gov (United States)

    Suyama, Shigetomo; Ralevski, Alexandra; Liu, Zhong-Wu; Dietrich, Marcelo O; Yada, Toshihiko; Simonds, Stephanie E; Cowley, Michael A; Gao, Xiao-Bing; Diano, Sabrina; Horvath, Tamas L

    2017-08-01

    POMC neurons integrate metabolic signals from the periphery. Here, we show in mice that food deprivation induces a linear current-voltage relationship of AMPAR-mediated excitatory postsynaptic currents (EPSCs) in POMC neurons. Inhibition of EPSCs by IEM-1460, an antagonist of calcium-permeable (Cp) AMPARs, diminished EPSC amplitude in the fed but not in the fasted state, suggesting entry of GluR2 subunits into the AMPA receptor complex during food deprivation. Accordingly, removal of extracellular calcium from ACSF decreased the amplitude of mEPSCs in the fed but not the fasted state. Ten days of high-fat diet exposure, which was accompanied by elevated leptin levels and increased POMC neuronal activity, resulted in increased expression of Cp-AMPARs on POMC neurons. Altogether, our results show that entry of calcium via Cp-AMPARs is inherent to activation of POMC neurons, which may underlie a vulnerability of these neurons to calcium overload while activated in a sustained manner during over-nutrition.

  10. The identification and functional implications of human-specific "fixed" amino acid substitutions in the glutamate receptor family

    Directory of Open Access Journals (Sweden)

    Fujiyama Asao

    2009-09-01

    Full Text Available Abstract Background The glutamate receptors (GluRs play a vital role in the mediation of excitatory synaptic transmission in the central nervous system. To clarify the evolutionary dynamics and mechanisms of the GluR genes in the lineage leading to humans, we determined the complete sequences of the coding regions and splice sites of 26 chimpanzee GluR genes. Results We found that all of the reading frames and splice sites of these genes reported in humans were completely conserved in chimpanzees, suggesting that there were no gross structural changes in humans after their divergence from the human-chimpanzee common ancestor. We observed low KA/KS ratios in both humans and chimpanzees, and we found no evidence of accelerated evolution. We identified 30 human-specific "fixed" amino acid substitutions in the GluR genes by analyzing 80 human samples of seven different populations worldwide. Grantham's distance analysis showed that GRIN2C and GRIN3A are the most and the second most diverged GluR genes between humans and chimpanzees. However, most of the substitutions are non-radical and are not clustered in any particular region. Protein motif analysis assigned 11 out of these 30 substitutions to functional regions. Two out of these 11 substitutions, D71G in GRIN3A and R727H in GRIN3B, caused differences in the functional assignments of these genes between humans and other apes. Conclusion We conclude that the GluR genes did not undergo drastic changes such as accelerated evolution in the human lineage after the divergence of chimpanzees. However, there remains a possibility that two human-specific "fixed" amino acid substitutions, D71G in GRIN3A and R727H in GRIN3B, are related to human-specific brain function.

  11. Effects of glutamate receptor agonists on the P13 auditory evoked potential and startle response in the rat

    Directory of Open Access Journals (Sweden)

    Christen eSimon

    2011-01-01

    Full Text Available The P13 potential is the rodent equivalent of the P50 potential, which is an evoked response recorded at the vertex (Vx 50 msec following an auditory stimulus in humans. Both the P13 and P50 potentials are only present during waking and rapid eye movement (REM sleep, and are considered to be measures of level of arousal. The source of the P13 and P50 potentials appears to be the pedunculopontine nucleus (PPN, a brainstem nucleus with indirect ascending projections to the cortex through the intralaminar thalamus (ILT, mediating arousal, and descending inhibitory projections to the caudal pontine reticular formation (CPRF, which mediates the auditory startle response (SR. We tested the hypothesis that intracranial microinjection (ICM of glutamate (GLU or GLU receptor agonists will increase the activity of PPN neurons, resulting in an increased P13 potential response, and decreased SR due to inhibitory projections from the PPN to the CPRF, in freely moving animals. Cannulae were inserted into the PPN to inject neuroactive agents, screws were inserted into the Vx in order to record the P13 potential, and electrodes inserted into the dorsal nuchal muscle to record electromyograms (EMGs and SR amplitude. Our results showed that ICM of GLU into the PPN dose-dependently increased the amplitude of the P13 potential and decreased the amplitude of the SR. Similarly, ICM of NMDA or KA into the PPN increased the amplitude of the P13 potential. These findings indicate that glutamatergic input to the PPN plays a role in arousal control in vivo, and changes in glutamatergic input, or excitability of PPN neurons, could be implicated in a number of neuropsychiatric disorders with the common symptoms of hyperarousal and REM sleep dysregulation.

  12. Fragile X syndrome: a preclinical review on metabotropic glutamate receptor 5 (mGluR5) antagonists and drug development.

    Science.gov (United States)

    Pop, Andreea S; Gomez-Mancilla, Baltazar; Neri, Giovanni; Willemsen, Rob; Gasparini, Fabrizio

    2014-03-01

    Fragile X syndrome (FXS) is considered the leading inherited cause of intellectual disability and autism. In FXS, the fragile X mental retardation 1 (FMR1) gene is silenced and the fragile X mental retardation protein (FMRP) is not expressed, resulting in the characteristic features of the syndrome. Despite recent advances in understanding the pathophysiology of FXS, there is still no cure for this condition; current treatment is symptomatic. Preclinical research is essential in the development of potential therapeutic agents. This review provides an overview of the preclinical evidence supporting metabotropic glutamate receptor 5 (mGluR5) antagonists as therapeutic agents for FXS. According to the mGluR theory of FXS, the absence of FMRP leads to enhanced glutamatergic signaling via mGluR5, which leads to increased protein synthesis and defects in synaptic plasticity including enhanced long-term depression. As such, efforts to develop agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. Animal models, particularly the Fmr1 knockout mouse model, have become invaluable in exploring therapeutic approaches on an electrophysiological, behavioral, biochemical, and neuroanatomical level. Two direct approaches are currently being investigated for FXS treatment: reactivating the FMR1 gene and compensating for the lack of FMRP. The latter approach has yielded promising results, with mGluR5 antagonists showing efficacy in clinical trials. Targeting mGluR5 is a valid approach for the development of therapeutic agents that target the underlying pathophysiology of FXS. Several compounds are currently in development, with encouraging results.

  13. Cannabidiol induces rapid-acting antidepressant-like effects and enhances cortical 5-HT/glutamate neurotransmission: role of 5-HT1A receptors.

    Science.gov (United States)

    Linge, Raquel; Jiménez-Sánchez, Laura; Campa, Leticia; Pilar-Cuéllar, Fuencisla; Vidal, Rebeca; Pazos, Angel; Adell, Albert; Díaz, Álvaro

    2016-04-01

    Cannabidiol (CBD), the main non-psychotomimetic component of marihuana, exhibits anxiolytic-like properties in many behavioural tests, although its potential for treating major depression has been poorly explored. Moreover, the mechanism of action of CBD remains unclear. Herein, we have evaluated the effects of CBD following acute and chronic administration in the olfactory bulbectomy mouse model of depression (OBX), and investigated the underlying mechanism. For this purpose, we conducted behavioural (open field and sucrose preference tests) and neurochemical (microdialysis and autoradiography of 5-HT1A receptor functionality) studies following treatment with CBD. We also assayed the pharmacological antagonism of the effects of CBD to dissect out the mechanism of action. Our results demonstrate that CBD exerts fast and maintained antidepressant-like effects as evidenced by the reversal of the OBX-induced hyperactivity and anhedonia. In vivo microdialysis revealed that the administration of CBD significantly enhanced serotonin and glutamate levels in vmPFCx in a different manner depending on the emotional state and the duration of the treatment. The potentiating effect upon neurotransmitters levels occurring immediately after the first injection of CBD might underlie the fast antidepressant-like actions in OBX mice. Both antidepressant-like effect and enhanced cortical 5-HT/glutamate neurotransmission induced by CBD were prevented by 5-HT1A receptor blockade. Moreover, adaptive changes in pre- and post-synaptic 5-HT1A receptor functionality were also found after chronic CBD. In conclusion, our findings indicate that CBD could represent a novel fast antidepressant drug, via enhancing both serotonergic and glutamate cortical signalling through a 5-HT1A receptor-dependent mechanism. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Nicotinic receptors modulate the onset of reactive oxygen species production and mitochondrial dysfunction evoked by glutamate uptake block in the rat hypoglossal nucleus.

    Science.gov (United States)

    Tortora, Maria; Corsini, Silvia; Nistri, Andrea

    2017-02-03

    In several neurodegenerative diseases, glutamate-mediated excitotoxicity is considered to be a major process to initiate cell degeneration. Indeed, subsequent to excessive glutamate receptor stimulation, reactive oxygen species (ROS) generation and mitochondrial dysfunction are regarded as two major gateways leading to neuron death. These processes are mimicked in an in vitro model of rat brainstem slice when excitotoxicity is induced by DL-threo-β-benzyloxyaspartate (TBOA), a specific glutamate-uptake blocker that increases extracellular glutamate. Our recent study has demonstrated that brainstem hypoglossal motoneurons, which are very vulnerable to this damage, were neuroprotected from excitotoxicity with nicotine application through the activation of nicotinic acetylcholine receptors (nAChRs) and subsequent inhibition of ROS and mitochondrial dysfunction. The present study examined if endogenous cholinergic activity exerted any protective effect in this pathophysiological model and how ROS production (estimated with rhodamine fluorescence) and mitochondrial dysfunction (measured as methyltetrazolium reduction) were time-related during the early phase of excitotoxicity (0-4h). nAChR antagonists did not modify TBOA-evoked ROS production (that was nearly doubled over control) or mitochondrial impairment (25% decline), suggesting that intrinsic nAChR activity was insufficient to contrast excitotoxicity and needed further stimulation with nicotine to become effective. ROS production always preceded mitochondrial dysfunction by about 2h. Nicotine prevented both ROS production and mitochondrial metabolic depression with a delayed action that alluded to a complex chain of events targeting these two lesional processes. The present data indicate a relatively wide time frame during which strong nAChR activation can arrest a runaway neurotoxic process leading to cell death. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Resolution, configurational assignment, and enantiopharmacology at glutamate receptors of 2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA) and demethyl-ACPA

    DEFF Research Database (Denmark)

    Johansen, T N; Stensbøl, T B; Nielsen, B

    2001-01-01

    We have previously described (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA) as a potent agonist at the (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor subtype of (S)-glutamic acid (Glu) receptors. We now report the chromatographic resolution...... of ACPA and (RS)-2-amino-3-(3-carboxy-4-isoxazolyl)propionic acid (demethyl-ACPA) using a Sumichiral OA-5000 column. The configuration of the enantiomers of both compounds have been assigned based on X-ray crystallographic analyses, supported by circular dichroism spectra and elution orders on chiral HPLC...... columns. Furthermore, the enantiopharmacology of ACPA and demethyl-ACPA was investigated using radioligand binding and cortical wedge electrophysiological assay systems and cloned metabotropic Glu receptors. (S)-ACPA showed high affinity in AMPA binding (IC(50) = 0.025 microM), low affinity in kainic acid...

  16. Involvement of serotonergic system in the effect of a metabotropic glutamate 5 receptor antagonist in the novelty-suppressed feeding test

    Directory of Open Access Journals (Sweden)

    Kenichi Fukumoto

    2015-01-01

    Full Text Available The blockade of metabotropic glutamate 5 (mGlu5 receptor has been reported to exert antidepressant effects in several animal models. We previously reported that both ketamine and an mGlu5 receptor antagonist exerted an effect in a novelty-suppressed feeding (NSF test, and that the effect of ketamine may be mediated through an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA receptor-dependent increase in serotonergic transmission. However, the involvement of the serotonergic system in the effect of mGlu5 receptor antagonists in the NSF test is not well understood. Therefore, we examined the roles of the serotonergic system in the effect of an mGlu5 receptor antagonist, 6-methyl-2-(phenylethynylpyridine hydrochloride (MPEP, in the NSF test in mice. The administration of MPEP significantly shortened the latency to feed, which was not attenuated by the AMPA receptor antagonist, 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX. The effect of MPEP was abolished by the tryptophan hydroxylase inhibitor, para-chlorophenylalanine (PCPA. Moreover, the effect of MPEP was blocked by a serotonin (5-HT2A/2C receptor antagonist, ritanserin, but not by a 5-HT1A receptor antagonist, N-{2-[4-(2-methoxyphenyl-1-piperazinyl]ethyl}-N-(2-pyridynyl cyclohexane-carboxamide (WAY100635. These results suggest that the effect of an mGlu5 receptor antagonist may be mediated by the serotonergic system, including the stimulation of the 5-HT2A/2C receptor, in an AMPA receptor-independent manner in the NSF test.

  17. Involvement of serotonergic system in the effect of a metabotropic glutamate 5 receptor antagonist in the novelty-suppressed feeding test.

    Science.gov (United States)

    Fukumoto, Kenichi; Chaki, Shigeyuki

    2015-01-01

    The blockade of metabotropic glutamate 5 (mGlu5) receptor has been reported to exert antidepressant effects in several animal models. We previously reported that both ketamine and an mGlu5 receptor antagonist exerted an effect in a novelty-suppressed feeding (NSF) test, and that the effect of ketamine may be mediated through an α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor-dependent increase in serotonergic transmission. However, the involvement of the serotonergic system in the effect of mGlu5 receptor antagonists in the NSF test is not well understood. Therefore, we examined the roles of the serotonergic system in the effect of an mGlu5 receptor antagonist, 6-methyl-2-(phenylethynyl)pyridine hydrochloride (MPEP), in the NSF test in mice. The administration of MPEP significantly shortened the latency to feed, which was not attenuated by the AMPA receptor antagonist, 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX). The effect of MPEP was abolished by the tryptophan hydroxylase inhibitor, para-chlorophenylalanine (PCPA). Moreover, the effect of MPEP was blocked by a serotonin (5-HT)2A/2C receptor antagonist, ritanserin, but not by a 5-HT1A receptor antagonist, N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridynyl) cyclohexane-carboxamide (WAY100635). These results suggest that the effect of an mGlu5 receptor antagonist may be mediated by the serotonergic system, including the stimulation of the 5-HT2A/2C receptor, in an AMPA receptor-independent manner in the NSF test. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

  18. Proteasomal degradation of the metabotropic glutamate receptor 1α is mediated by Homer-3 via the proteasomal S8 ATPase: Signal transduction and synaptic transmission.

    Science.gov (United States)

    Rezvani, Khosrow; Baalman, Kelli; Teng, Yanfen; Mee, Maureen P; Dawson, Simon P; Wang, Hongmin; De Biasi, Mariella; Mayer, R John

    2012-07-01

    The metabotropic glutamate receptors (mGluRs) fine-tune the efficacy of synaptic transmission. This unique feature makes mGluRs potential targets for the treatment of various CNS disorders. There is ample evidence to show that the ubiquitin proteasome system mediates changes in synaptic strength leading to multiple forms of synaptic plasticity. The present study describes a novel interaction between post-synaptic adaptors, long Homer-3 proteins, and one of the 26S proteasome regulatory subunits, the S8 ATPase, that influences the degradation of the metabotropic glutamate receptor 1α (mGluR1α). We have shown that the two human long Homer-3 proteins specifically interact with human proteasomal S8 ATPase. We identified that mGluR1α and long Homer-3s immunoprecipitate with the 26S proteasome both in vitro and in vivo. We further found that the mGluR1α receptor can be ubiquitinated and degraded by the 26S proteasome and that Homer-3A facilitates this process. Furthermore, the siRNA mediated silencing of Homer-3 led to increased levels of total and plasma membrane-associated mGluR1α receptors. These results suggest that long Homer-3 proteins control the degradation of mGluR1α receptors by shuttling ubiquitinated mGluR-1α receptors to the 26S proteasome via the S8 ATPase which may modulate synaptic transmission. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

  19. Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice.

    Science.gov (United States)

    Liu, Xinhuai; Porteous, Robert; Herbison, Allan E

    2017-01-01

    Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABA A and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABA A -mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.

  20. 5-Hydroxytryptamine2A (5-HT2A) receptor regulation in rat prefrontal cortex: interaction of a phenethylamine hallucinogen and the metabotropic glutamate2/3 receptor agonist LY354740.

    Science.gov (United States)

    Marek, Gerard J; Wright, Rebecca A; Schoepp, Darryle D

    2006-08-07

    5-Hydroxytryptamine2A (5-HT2A) receptor regulation is atypical compared to most other monoaminergic receptors in that chronic administration of both antagonists and agonists results in down-regulation of cortical 5-HT2A receptor number and the functional in vitro and in vivo effects. We have recently found that midline thalamic lesions, which appeared to block glutamate release induced by activation of 5-HT2A receptors, also increased 5-HT2A receptor binding in layers I and Va of the medial prefrontal cortex (mPFC). These layers contain the highest density of both 5-HT2A receptors and thalamocortical terminals from the midline and intralaminar thalamic nuclei. These findings suggest the hypothesis that excitatory amino acid release plays a role in regulation of postsynaptic 5-HT2A receptors, and that down-regulation of 5-HT2A receptors by 5-HT2A agonists may not be attributed only to simple occupancy of the receptor by direct agonists. Therefore, we examined the effect of a single 30 min pretreatment with the metabotropic glutamate2/3 (mGlu2/3) receptor agonist (1S,2S,5R,6S)-2-aminobicyclo[3.1.0] hexane-2,6-dicarboxylate monohydrate (LY354740; 10 mg/kg, i.p.) on the second of three consecutive days of 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI) treatment (1.25 mg/kg, i.p.). The subchronic DOI administration significantly decreased binding of [125I]DOI to 5-HT2A receptors in layers I and Va of the mPFC by approximately 25%. In contrast, a single dose of LY354740 on Day 2 of this regimen completely blocked the DOI-induced down-regulation. Thus, a presumed hypoglutamatergic state secondary to thalamic lesions and increased glutamate release induced by a subchronic regimen of a 5-HT2A agonist (and hallucinogenic drug) differentially regulate prefrontal cortical 5-HT2A receptor binding.

  1. Facilitation of glutamate and GABA release by P2X receptor activation in supraoptic neurons from freshly isolated rat brain slices

    Czech Academy of Sciences Publication Activity Database

    Vávra, Vojtěch; Bhattacharya, Anirban; Zemková, Hana

    2011-01-01

    Roč. 188, - (2011), s. 1-12 ISSN 0306-4522 R&D Projects: GA AV ČR(CZ) IAA500110910; GA ČR(CZ) GA305/07/0681; GA ČR(CZ) GD305/08/H037; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : ATP * purinergic P2X receptors * GABA * glutamate * supraoptic nucleus * patch clamp Subject RIV: ED - Physiology Impact factor: 3.380, year: 2011

  2. Metabotropic glutamate receptor 3 is associated with heroin dependence but not depression or schizophrenia in a Chinese population.

    Directory of Open Access Journals (Sweden)

    Wei Jia

    Full Text Available Metabotropic glutamate receptor subtype 3 (mGluR3, encoded by GRM3 plays important roles in the pathophysiology of schizophrenia, depression, and drug dependence. GRM3 polymorphisms were reported to be associated with prefrontal activity, cognitive shifting, and memory capability in healthy subjects, as well as susceptibility to schizophrenia and depression. The goal of this study was to replicate the association of GRM3 with schizophrenia and depression and to explore GRM3's potential association with heroin dependence (HD in a Chinese population. Seventeen SNPs throughout the GRM3 gene were genotyped using MALDI-TOF within the MassARRAY system, and the allele and genotype distributions were compared between 619 healthy controls and 433 patients with schizophrenia, 409 patients with major depression, and 584 unrelated addicts. We found that GRM3 polymorphisms modulate the susceptibility to HD but do not significantly influence the risk for schizophrenia or depression. An increased risk of HD was significantly associated with the minor alleles of two GRM3 SNPs, including the T allele of rs274618 (Odds ratio (OR = 1.631, 95% confidence interval (95%CI: 1.317-2.005, the T allele of rs274622 (OR = 1.652, 95% CI: 1.336-2.036, compared with the major alleles. The addicts carrying the minor allele of rs274618 or rs274622 had a shortened duration for transition from first use to dependence (DTFUD in comparison to homozygote for major allele (P<0.0001 for each SNP using log rank test. Additionally, a 6-SNP haplotype within 5' region of the GRM3 including the minor alleles of the two aforementioned SNPs was significantly associated with an increased risk of HD (P = 0.00001, OR = 1.668, 95% CI: 1.335-2.084. Our data indicated that GRM3 polymorphisms do not contribute to genetic susceptibility to schizophrenia and depression, but they confer an increased risk of HD in a Chinese population.

  3. Metabotropic glutamate receptor subtype 7 has critical roles in regulation of the endocrine system and social behaviours.

    Science.gov (United States)

    Masugi-Tokita, M; Yoshida, T; Kageyama, S; Kawata, M; Kawauchi, A

    2018-03-01

    Metabotropic glutamate receptor subtype 7 (mGluR7) is one of the group III mGluRs, which are negatively coupled to adenylate cyclase via Gi/Go proteins and localised to presynaptic active zones of the mammalian central nervous system. We previously reported that mGluR7 is essential for intermale aggression and amygdala-dependent fear learning. To elucidate the role of mGluR7 in the neuroendocrine system, we performed biochemical analyses and found a significant reduction of testosterone levels in mGluR7 knockout (KO) mice. Testosterone replacement restored intermale aggressive behaviour in castrated wild-type mice to the level of gonadally intact wild-type mice. However, given the same dosage of testosterone replacement, mGluR7 KO mice showed almost no aggressive behaviour. These results indicate that reduction of plasma testosterone is unrelated to the deficit in intermale aggression in mGluR7 KO mice. Social investigating behaviour of intact mGluR7 KO mice also differed from that of wild-type mice; e.g. the KO mice showing less frequent anogenital sniffing and more frequent grooming behaviour. Testosterone replacement increased anogenital sniffing and grooming behaviour in castrated mGluR7 KO mice, while the differences were still present between castrated wild-type mice and KO mice after both underwent testosterone replacement. These results imply that reduction of plasma testosterone may partially inhibit social investigating behaviours in intact mGluR7 KO mice. Furthermore, castrated mGluR7 KO mice have smaller seminal vesicles than those of castrated wild-type mice, although seminal vesicle weights were normal in intact mice. These observations suggest that, besides testicular testosterone, some other hormone levels may be dysregulated in mGluR7 KO mice, and indicate a critical role of mGluR7 in the endocrine system. Taken together, our findings demonstrate that mGluR7 is essential for the regulation of the endocrine system, in addition to innate behaviours

  4. The negative effects of alcohol hangover on high-anxiety phenotype rats are influenced by the glutamate receptors of the dorsal midbrain.

    Science.gov (United States)

    Ezequiel Leite, L; Nobre, M J

    2012-06-28

    Alcoholism is a chronic disorder characterized by the appearance of a withdrawal syndrome following the abrupt cessation of alcohol intake that includes symptoms of physical and emotional disturbances, anxiety being the most prevalent symptom. In humans, it was shown that anxiety may increase the probability of relapse. In laboratory animals, however, the use of anxiety to predict alcohol preference has remained difficult. Excitatory amino acids as glutamate have been implicated in alcohol hangover and may be responsible for the seizures and anxiety observed during withdrawal. The dorsal periaqueductal gray (DPAG) is a midbrain region critical for the modulation/expression of anxiety- and fear-related behaviors and the propagation of seizures induced by alcohol withdrawal, the glutamate neurotransmission being one of the most affected. The present study was designed to evaluate whether low- (LA) and high-anxiety rats (HA), tested during the alcohol hangover phase, in which anxiety is the most prevalent symptom, are more sensitive to the reinforcing effects of alcohol when tested in a voluntary alcohol drinking procedure. Additionally, we were interested in investigating the main effects of reducing the excitatory tonus of the dorsal midbrain, after the blockade of the ionotropic glutamate receptors into the DPAG, on the voluntary alcohol intake of HA and LA motivated rats that were made previously experienced with the free operant response of alcohol drinking. For this purpose, we used local infusions of the N-metil D-Aspartato (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-kainate receptors antagonist DL-2-Amino-7-phosphonoheptanoic acid - DL-AP7 (10 nmol/0.2 μl) and l-glutamic acid diethyl ester - GDEE (160 nmol/0.2 μl), respectively. Alcohol intoxication was produced by 10 daily bolus intraperitonial (IP) injections of alcohol (2.0 g/kg). Peak-blood alcohol levels were determined by gas-chromatography analysis in order to assess blood

  5. Estrogen enhances expression of the complement C5a receptor and the C5a-agonist evoked calcium influx in hormone secreting neurons of the hypothalamus.

    Science.gov (United States)

    Farkas, Imre; Varju, Patricia; Szabo, Emese; Hrabovszky, Erik; Okada, Noriko; Okada, Hidechika; Liposits, Zsolt

    2008-01-01

    In the present study we examined presence of the complement C5a receptor (C5aR) in hypothalamic neurosecretory neurons of the rodent brain and effect of estrogen on C5aR expression. Whole cell patch clamp measurements revealed that magnocellular neurons in the supraoptic and paraventricular nuclei of hypothalamic slices of the rats responded to the C5aR-agonist PL37-MAP peptide with calcium ion current pulses. Gonadotropin-releasing hormone (GnRH) producing neurons in slices of the preoptic area of the mice also reacted to the peptide treatment with inward calcium current. PL37-MAP was able to evoke the inward ion current of GnRH neurons in slices from ovariectomized animals. The amplitude of the inward pulses became higher in slices obtained from 17beta-estradiol (E2) substituted mice. Calcium imaging experiments demonstrated that PL37-MAP increased the intracellular calcium content in the culture of the GnRH-producing GT1-7 cell line in a concentration-dependent manner. Calcium imaging also showed that E2 pretreatment elevated the PL37-MAP evoked increase of the intracellular calcium content in the GT1-7 cells. The estrogen receptor blocker Faslodex in the medium prevented the E2-evoked increase of the PL37-MAP-triggered elevation of the intracellular calcium content in the GT1-7 cells demonstrating that the effect of E2 might be related to the presence of estrogen receptor. Real-time PCR experiments revealed that E2 increased the expression of C5aR mRNA in GT1-7 neurons, suggesting that an increased C5aR synthesis could be involved in the estrogenic modulation of calcium response. These data indicate that hypothalamic neuroendocrine neurons can integrate immune and neuroendocrine functions. Our results may serve a better understanding of the inflammatory and neurodegeneratory diseases of the hypothalamus and the related neuroendocrine and autonomic compensatory responses.

  6. Cloning, expression, cellular distribution, and role in chemotaxis of a C5a receptor in rainbow trout: the first identification of a C5a receptor in a nonmammalian species

    Science.gov (United States)

    Boshra, Hani; Li, Jun; Peters, Rodney; Hansen, John; Matlapudi, Anjan; Sunyer, J. Oriol

    2004-01-01

    C3a, C4a, and C5a anaphylatoxins generated during complement activation play a key role in inflammation. C5a is the most potent of the three anaphylatoxins in eliciting biological responses. The effects of C5a are mediated by its binding to C5a receptor (C5aR, CD88). To date, C5aR has only been identified and cloned in mammalian species, and its evolutionary history remains ill-defined. To gain insights into the evolution, conserved structural domains, and functions of C5aR, we have cloned and characterized a C5aR in rainbow trout, a teleost fish. The isolated cDNA encoded a 350-aa protein that showed the highest sequence similarity to C5aR from other species. Genomic analysis revealed the presence of one continuous exon encoding the entire open reading frame. Northern blot analysis showed significant expression of the trout C5a receptor (TC5aR) message in PBLs and kidney. Flow cytometric analysis showed that two Abs generated against two different areas of the extracellular N-terminal region of TC5aR positively stained the same leukocyte populations from PBLs. B lymphocytes and granulocytes comprised the majority of cells recognized by the anti-TC5aR. More importantly, these Abs inhibited chemotaxis of PBLs toward a chemoattractant fraction purified from complement-activated trout serum. Our data suggest that the split between C5aR and C3aR from a common ancestral molecule occurred before the emergence of teleost fish. Moreover, we demonstrate that the overall structure of C5aR as well as its role in chemotaxis have remained conserved for >300 million years.

  7. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    Science.gov (United States)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-04-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1-3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.

  8. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    Science.gov (United States)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-01-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1–3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents. PMID:27094554

  9. Arabidopsis Glutamate Receptor Homolog3.5 Modulates Cytosolic Ca2+ Level to Counteract Effect of Abscisic Acid in Seed Germination1[OPEN

    Science.gov (United States)

    Kong, Dongdong; Ju, Chuanli; Parihar, Aisha; Kim, So; Cho, Daeshik; Kwak, June M.

    2015-01-01

    Seed germination is a critical step in a plant’s life cycle that allows successful propagation and is therefore strictly controlled by endogenous and environmental signals. However, the molecular mechanisms underlying germination control remain elusive. Here, we report that the Arabidopsis (Arabidopsis thaliana) glutamate receptor homolog3.5 (AtGLR3.5) is predominantly expressed in germinating seeds and increases cytosolic Ca2+ concentration that counteracts the effect of abscisic acid (ABA) to promote germination. Repression of AtGLR3.5 impairs cytosolic Ca2+ concentration elevation, significantly delays germination, and enhances ABA sensitivity in seeds, whereas overexpression of AtGLR3.5 results in earlier germination and reduced seed sensitivity to ABA. Furthermore, we show that Ca2+ suppresses the expression of ABSCISIC ACID INSENSITIVE4 (ABI4), a key transcription factor involved in ABA response in seeds, and that ABI4 plays a fundamental role in modulation of Ca2+-dependent germination. Taken together, our results provide molecular genetic evidence that AtGLR3.5-mediated Ca2+ influx stimulates seed germination by antagonizing the inhibitory effects of ABA through suppression of ABI4. These findings establish, to our knowledge, a new and pivotal role of the plant glutamate receptor homolog and Ca2+ signaling in germination control and uncover the orchestrated modulation of the AtGLR3.5-mediated Ca2+ signal and ABA signaling via ABI4 to fine-tune the crucial developmental process, germination, in Arabidopsis. PMID:25681329

  10. Metabotropic glutamate receptor antagonists but not NMDA antagonists affect conditioned taste aversion acquisition in the parabrachial nucleus of rats

    Czech Academy of Sciences Publication Activity Database

    Valeš, Karel; Zach, P.; Bielavská, Edita

    2006-01-01

    Roč. 169, č. 1 (2006), s. 50-57 ISSN 0014-4819 R&D Projects: GA MŠk(CZ) 1M0517 Institutional research plan: CEZ:AV0Z5011922 Keywords : learning * microdialysis * glutamate antagonists Subject RIV: FH - Neurology Impact factor: 1.959, year: 2006

  11. 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.

  12. Wnt-5a/Frizzled9 Receptor Signaling through the Gαo-Gβγ Complex Regulates Dendritic Spine Formation*

    Science.gov (United States)

    Ramírez, Valerie T.; Ramos-Fernández, Eva; Henríquez, Juan Pablo; Lorenzo, Alfredo; Inestrosa, Nibaldo C.

    2016-01-01

    Wnt ligands play crucial roles in the development and regulation of synapse structure and function. Specifically, Wnt-5a acts as a secreted growth factor that regulates dendritic spine formation in rodent hippocampal neurons, resulting in postsynaptic development that promotes the clustering of the PSD-95 (postsynaptic density protein 95). Here, we focused on the early events occurring after the interaction between Wnt-5a and its Frizzled receptor at the neuronal cell surface. Additionally, we studied the role of heterotrimeric G proteins in Wnt-5a-dependent synaptic development. We report that FZD9 (Frizzled9), a Wnt receptor related to Williams syndrome, is localized in the postsynaptic region, where it interacts with Wnt-5a. Functionally, FZD9 is required for the Wnt-5a-mediated increase in dendritic spine density. FZD9 forms a precoupled complex with Gαo under basal conditions that dissociates after Wnt-5a stimulation. Accordingly, we found that G protein inhibition abrogates the Wnt-5a-dependent pathway in hippocampal neurons. In particular, the activation of Gαo appears to be a key factor controlling the Wnt-5a-induced dendritic spine density. In addition, we found that Gβγ is required for the Wnt-5a-mediated increase in cytosolic calcium levels and spinogenesis. Our findings reveal that FZD9 and heterotrimeric G proteins regulate Wnt-5a signaling and dendritic spines in cultured hippocampal neurons. PMID:27402827

  13. Test-retest reproducibility of the metabotropic glutamate receptor 5 ligand [{sup 18}F]FPEB with bolus plus constant infusion in humans

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eunkyung; Sullivan, Jenna M.; Planeta, Beata; Gallezot, Jean-Dominique; Lim, Keunpoong; Lin, Shu-Fei; Ropchan, Jim; Huang, Yiyun; Carson, Richard E. [Yale School of Medicine, PET Center, Department of Diagnostic Radiology, 801 Howard Avenue, PO Box 208048, New Haven, CT (United States); McCarthy, Timothy J. [Pfizer Worldwide Research and Development, Cambridge, MA (United States); Ding, Yu-Shin [New York University School of Medicine, Department of Radiology, New York, NY (United States); Morris, Evan D.; Williams, Wendol A. [Yale School of Medicine, PET Center, Department of Diagnostic Radiology, 801 Howard Avenue, PO Box 208048, New Haven, CT (United States); Yale School of Medicine, Department of Psychiatry, New Haven, CT (United States)

    2015-09-15

    [{sup 18}F]FPEB is a promising PET radioligand for the metabotropic glutamate receptor 5 (mGluR5), a potential target for the treatment of neuropsychiatric diseases. The purpose of this study was to evaluate the test-retest reproducibility of [{sup 18}F]FPEB in the human brain. Seven healthy male subjects were scanned twice, 3 - 11 weeks apart. Dynamic data were acquired using bolus plus infusion of 162 ± 32 MBq [{sup 18}F]FPEB. Four methods were used to estimate volume of distribution (V{sub T}): equilibrium analysis (EQ) using arterial (EQ{sub A}) or venous input data (EQ{sub V}), MA1, and a two-tissue compartment model (2 T). Binding potential (BP{sub ND}) was also estimated using cerebellar white matter (CWM) or gray matter (CGM) as the reference region using EQ, 2 T and MA1. Absolute test-retest variability (aTRV) of V{sub T} and BP{sub ND} were calculated for each method. Venous blood measurements (C{sub V}) were compared with arterial input (C{sub A}) to examine their usability in EQ analysis. Regional V{sub T} estimated by the four methods displayed a high degree of agreement (r{sup 2} ranging from 0.83 to 0.99 among the methods), although EQ{sub A} and EQ{sub V} overestimated V{sub T} by a mean of 9 % and 7 %, respectively, compared to 2 T. Mean values of aTRV of V{sub T} were 11 % by EQ{sub A}, 12 % by EQ{sub V}, 14 % by MA1 and 14 % by 2 T. Regional BP{sub ND} also agreed well among the methods and mean aTRV of BP{sub ND} was 8 - 12 % (CWM) and 7 - 9 % (CGM). Venous and arterial blood concentrations of [{sup 18}F]FPEB were well matched during equilibrium (C{sub V} = 1.01 . C{sub A}, r{sup 2} = 0.95). [{sup 18}F]FPEB binding shows good TRV with minor differences among analysis methods. Venous blood can be used as an alternative for input function measurement instead of arterial blood in EQ analysis. Thus, [{sup 18}F]FPEB is an excellent PET imaging tracer for mGluR5 in humans. (orig.)

  14. Involvement of neuronal and glial activities in control of the extracellular d-serine concentrations by the AMPA glutamate receptor in the mouse medial prefrontal cortex.

    Science.gov (United States)

    Ishiwata, Sayuri; Umino, Asami; Nishikawa, Toru

    2017-09-28

    It has been well accepted that d-serine may be an exclusive endogenous coagonist for the N-methyl-d-aspartate (NMDA)-type glutamate receptor in mammalian forebrain regions. We have recently found by using an in vivo dialysis method that an intra-medial prefrontal cortex infusion of S-α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (S-AMPA), a selective AMPA-type glutamate receptor agonist, causes a reduction in the extracellular levels of d-serine in a calcium-permeable AMPA receptor antagonist-sensitive manner. The inhibitory influence by the AMPA receptor on the extracellular d-serine, however, contradicts the data obtained from in vitro experiments that the AMPA receptor stimulation leads to facilitation of the d-serine liberation. This discrepancy appears to be due to the different cell setups between the in vivo and in vitro preparations. From the viewpoints of the previous reports indicating (1) the neuronal presence of d-serine synthesizing enzyme, serine racemase, and d-serine-like immunoreactivity and (2) the same high tissue concentrations of d-serine in the glia-enriched white matter and in the neuron-enriched gray matter of the mammalian neocortex, we have now investigated in the mouse medial prefrontal cortex, the effects of attenuation of neuronal and glial activities, by tetrodotoxin or fluorocitrate, respectively, on the S-AMPA-induced downregulation of the extracellular d-serine contents. In vivo dialysis studies revealed that a local infusion of tetrodotoxin or fluorocitrate eliminated the ability of S-AMPA given intra-cortically to cause a significant decrease in the dialysate concentrations of d-serine without affecting the elevating effects of S-AMPA on those of glycine, another intrinsic coagonist for the NMDA receptor. These findings suggest that the control by the AMPA receptor of the extracellular d-serine levels could be modulated by the neuronal and glial activities in the prefrontal cortex. It cannot be excluded that

  15. Complement factor 5a receptor chimeras reveal the importance of lipid-facing residues in transport competence

    DEFF Research Database (Denmark)

    Klco, Jeffery M; Sen, Saurabh; Hansen, Jakob L

    2009-01-01

    oligomerization studies demonstrated energy transfer between the wild-type complement factor 5a receptor and the lipid-facing chimeras, suggesting that the lipid-facing residues within a single TM segment are not essential for oligomerization. These studies highlight the importance of the lipid-facing residues...

  16. N-methyl-D-aspartate receptor-mediated glutamate transmission in nucleus accumbens plays a more important role than that in dorsal striatum in cognitive flexibility

    Directory of Open Access Journals (Sweden)

    Xuekun eDing

    2014-09-01

    Full Text Available Cognitive flexibility is a critical ability for adapting to an ever-changing environment in humans and animals. Deficits in cognitive flexibility are observed in most schizophrenia patients. Previous studies reported that the medial prefrontal cortex-to-ventral striatum and orbital frontal cortex-to-dorsal striatum circuits play important roles in extra- and intra-dimensional strategy switching, respectively. However, the precise function of striatal subregions in flexible behaviors is still unclear. N-methyl-D-aspartate receptors (NMDARs are major glutamate receptors in the striatum that receive glutamatergic projections from the frontal cortex. The membrane insertion of Ca2+-permeable α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors (AMPARs depends on NMDAR activation and is required in learning and memory processes. In the present study, we measured set-shifting and reversal learning performance in operant chambers in rats and assessed the effects of blocking NMDARs and Ca2+-permeable AMPARs in striatal subregions on behavioral flexibility. The blockade of NMDARs in the nucleus accumbens (NAc core by AP5 impaired set-shifting ability by causing a failure to modify prior learning. The suppression of NMDAR-mediated transmission in the NAc shell induced a deficit in set-shifting by disrupting the learning and maintenance of novel strategies. During reversal learning, infusions of AP5 into the NAc shell and core impaired the ability to learn and maintain new strategies. However, behavioral flexibility was not significantly affected by blocking NMDARs in the dorsal striatum. We also found that the blockade of Ca2+-permeable AMPARs by NASPM in any subregion of the striatum did not affect strategy switching. These findings suggest that NMDAR-mediated glutamate transmission in the NAc contributes more to cognitive execution compared with the dorsal striatum.

  17. Methamphetamine-induced short-term increase and long-term decrease in spatial working memory affects protein Kinase M zeta (PKMζ), dopamine, and glutamate receptors.

    Science.gov (United States)

    Braren, Stephen H; Drapala, Damian; Tulloch, Ingrid K; Serrano, Peter A

    2014-01-01

    Methamphetamine (MA) is a toxic, addictive drug shown to modulate learning and memory, yet the neural mechanisms are not fully understood. We investigated the effects of 2 weekly injections of MA (30 mg/kg) on working memory using the radial 8-arm maze (RAM) across 5 weeks in adolescent-age mice. MA-treated mice show a significant improvement in working memory performance 1 week following the first MA injection compared to saline-injected controls. Following 5 weeks of MA abstinence mice were re-trained on a reference and working memory version of the RAM to assess cognitive flexibility. MA-treated mice show significantly more working memory errors without effects on reference memory performance. The hippocampus and dorsal striatum were assessed for expression of glutamate receptors subunits, GluA2 and GluN2B; dopamine markers, dopamine 1 receptor (D1), dopamine transporter (DAT) and tyrosine hydroxylase (TH); and memory markers, protein kinase M zeta (PKMζ) and protein kinase C zeta (PKCζ). Within the hippocampus, PKMζ and GluA2 are both significantly reduced after MA supporting the poor memory performance. Additionally, a significant increase in GluN2B and decrease in D1 identifies dysregulated synaptic function. In the striatum, MA treatment increased cytosolic DAT and TH levels associated with dopamine hyperfunction. MA treatment significantly reduced GluN2B while increasing both PKMζ and PKCζ within the striatum. We discuss the potential role of PKMζ/PKCζ in modulating dopamine and glutamate receptors after MA treatment. These results identify potential underlying mechanisms for working memory deficits induced by MA.

  18. Methamphetamine-induced short-term increase and long-term decrease in spatial working memory affects Protein Kinase M zeta (PKMζ, dopamine, and glutamate receptors

    Directory of Open Access Journals (Sweden)

    Stephen H Braren

    2014-12-01

    Full Text Available Methamphetamine (MA is a toxic, addictive drug shown to modulate learning and memory, yet the neural mechanisms are not fully understood. We investigated the effects of 2 weekly injections of MA (30 mg/kg on working memory using the radial 8-arm maze (RAM across 5 weeks in adolescent-age mice. MA-treated mice show a significant improvement in working memory performance 1 week following the first MA injection compared to saline-injected controls. Following 5 weeks of MA abstinence mice were re-trained on a reference and working memory version of the RAM to assess cognitive flexibility. MA-treated mice show significantly more working memory errors without effects on reference memory performance. The hippocampus and dorsal striatum were assessed for expression of glutamate receptors subunits, GluA2 and GluN2B; dopamine markers, dopamine 1 receptor (D1, dopamine transporter (DAT and tyrosine hydroxylase (TH; and memory markers, protein kinase M zeta (PKMζ and protein kinase C zeta (PKCζ. Within the hippocampus, PKMζ and GluA2 are both significantly reduced after MA supporting the poor memory performance. Additionally, a significant increase in GluN2B and decrease in D1 identifies dysregulated synaptic function. In the striatum, MA treatment increased cytosolic DAT and TH levels associated with dopamine hyperfunction. MA treatment significantly reduced GluN2B while increasing both PKMζ and PKCζ within the striatum. We discuss the potential role of PKMζ/PKCζ in modulating dopamine and glutamate receptors after MA treatment. These results identify potential underlying mechanisms for working memory deficits induced by MA.

  19. Modafinil restores methamphetamine induced object-in-place memory deficits in rats independent of glutamate N-methyl d-aspartate receptor expression

    Science.gov (United States)

    Reichel, Carmela M.; Gilstrap, Meghin G.; Ramsey, Lauren A.; See, Ronald E.

    2013-01-01

    Background Chronic methamphetamine (meth) abuse in humans can lead to various cognitive deficits, including memory loss. We previously showed that chronic meth self-administration impairs memory for objects relative to their location and surrounding objects. Here, we demonstrate that the cognitive enhancer, modafinil, reversed this cognitive impairment independent of glutamate N-methyl d-aspartate (GluN) receptor expression. Methods Male, Long-Evans rats underwent a noncontingent (Experiment 1) or contingent (Experiment 2) meth regimen. After one week of abstinence, rats were tested for object-in-place recognition memory. Half the rats received either vehicle or modafinil (100 mg/kg) immediately after object familiarization. Rats (Experiment 2) were sacrificed immediately after the test and brain areas that comprise the key circuitry for object in place performance were manually dissected. Subsequently, glutamate receptor expression was measured from a crude membrane fraction using western blot procedures. Results Saline-treated rats spent more time interacting with the objects in changed locations, while meth-treated rats distributed their time equally among all objects. Meth-treated rats that received modafinil showed a reversal in the deficit, whereby they spent more time exploring the objects in the new locations. GluN2B receptor subtype was decreased in the perirhinal cortex, yet remained unaffected in the prefrontal cortex and hippocampus of meth rats. This meth-induced down regulation occurred whether or not meth experienced rats received vehicle or modafinil. Conclusions These data support the use of modafinil for memory impairment in meth addiction. Further studies are needed to elucidate the neural mechanisms of modafinil reversal of cognitive impairments. PMID:24120858

  20. Determination of binding capacity and adsorption enthalpy between Human Glutamate Receptor (GluR1) peptide fragments and kynurenic acid by surface plasmon resonance experiments.

    Science.gov (United States)

    Csapó, E; Majláth, Z; Juhász, Á; Roósz, B; Hetényi, A; Tóth, G K; Tajti, J; Vécsei, L; Dékány, I

    2014-11-01

    The interaction between kynurenic acid (KYNA) and two peptide fragments (ca. 30 residues) of Human Glutamate Receptor 201-300 (GluR1) using surface plasmon resonance (SPR) spectroscopy was investigated. Because of the medical interest in the neuroscience, GluR1 is one of the important subunits of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR). AMPARs are ionotoropic glutamate receptors, which are mediating fast synaptic transmission and are crucial for plasticity in the brain. On the other hand, KYNA has been suggested to have neuroprotective activity and it has been considered for apply in therapy in certain neurobiological disorders. In this article the adsorption of the GluR1201-230 and GluR1231-259 peptides were studied on gold biosensor chip. The peptides were chemically bonded onto the gold surface via thiol group of L-cysteine resulted in the formation of peptide monolayer on the SPR chip surface. Because the GluR1231-259 peptide does not contain L-cysteine the Val256 was replaced by Cys256. The cross sectional area and the surface orientation of the studied peptides were determined by SPR and theoretical calculations (LOMETS) as well. The binding capability of KYNA on the peptide monolayer was studied in the concentration range of 0.1-5.0 mM using 150 mM NaCl ionic strength at pH 7.4 (±0.02) in phosphate buffer solutions. In order to determine the binding enthalpy the experiments were carried out between +10°C and +40°C. The heat of adsorption was calculated by using adsorption isotherms at different surface loading of KYNA on the SPR chip. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. The ketamine analogue methoxetamine and 3- and 4-methoxy analogues of phencyclidine are high affinity and selective ligands for the glutamate NMDA receptor.

    Directory of Open Access Journals (Sweden)

    Bryan L Roth

    Full Text Available In this paper we determined the pharmacological profiles of novel ketamine and phencyclidine analogues currently used as 'designer drugs' and compared them to the parent substances via the resources of the National Institute of Mental Health Psychoactive Drug Screening Program. The ketamine analogues methoxetamine ((RS-2-(ethylamino-2-(3-methoxyphenylcyclohexanone and 3-MeO-PCE (N-ethyl-1-(3-methoxyphenylcyclohexanamine and the 3- and 4-methoxy analogues of phencyclidine, (1-[1-(3-methoxyphenylcyclohexyl]piperidine and 1-[1-(4-methoxyphenylcyclohexyl]piperidine, were all high affinity ligands for the PCP-site on the glutamate NMDA receptor. In addition methoxetamine and PCP and its analogues displayed appreciable affinities for the serotonin transporter, whilst the PCP analogues exhibited high affinities for sigma receptors. Antagonism of the NMDA receptor is thought to be the key pharmacological feature underlying the actions of dissociative anaesthetics. The novel ketamine and PCP analogues had significant affinities for the NMDA receptor in radioligand binding assays, which may explain their psychotomimetic effects in human users. Additional actions on other targets could be important for delineating side-effects.

  2. Synergy between L-DOPA and a novel positive allosteric modulator of metabotropic glutamate receptor 4: implications for Parkinson's disease treatment and dyskinesia.

    Science.gov (United States)

    Bennouar, Khaled-Ezaheir; Uberti, Michelle A; Melon, Christophe; Bacolod, Maria D; Jimenez, Hermogenes N; Cajina, Manuel; Kerkerian-Le Goff, Lydia; Doller, Darío; Gubellini, Paolo

    2013-03-01

    Group III metabotropic glutamate (mGlu) receptors are localized in presynaptic terminals within basal ganglia (BG) circuitry that become hyperactive due to dopamine depletion in Parkinson's disease (PD). For this reason, group III mGlu receptors, in particular mGlu4, have been considered as key strategic targets for non-dopaminergic pharmacological treatments aimed at modulating these synapses, without producing the well known side-effects of l-DOPA, in particular the highly disabling l-DOPA-induced dyskinesia (LID). Herein we add physiological and functional support to this hypothesis using Lu AF21934, a novel selective and brain-penetrant mGlu4 receptor positive allosteric modulator (PAM) tool compound. By in vitro electrophysiological recordings we demonstrate that Lu AF21934 inhibits corticostriatal synaptic transmission and enhances the effect of the orthosteric mGlu4 receptor-preferred agonist LSP1-2111. In naïve rats, Lu AF21934 dose-dependently (10 and 30 mg/kg) alleviated haloperidol-induced catalepsy. In hemiparkinsonian rats (unilateral 6-hydroxydopamine lesion of the substantia nigra pars compacta), Lu AF21934 alone did not affect akinesia at the doses tested (10 and 30 mg/kg). However, when Lu AF21934 was combined with sub-threshold doses of l-DOPA (1 and 5 mg/kg), it acted synergistically in alleviating akinesia in a dose-dependent manner and, notably, also reduced the incidence of LID but not its severity. Interestingly, these effects occurred at Lu AF21934 brain free concentrations that showed functional activity in in vitro screens (calcium flux and electrophysiology assays). These results support the potential for antiparkinsonian clinical use of a combined treatment consisting in l-DOPA and a mGlu4 receptor PAM to reduce efficacious l-DOPA doses (generally known as l-DOPA sparing), while maintaining the same benefit on PD motor troubles, and at the same time minimizing the development of LID. This article is part of a Special Issue entitled

  3. fMRI study of the role of glutamate NMDA receptor in the olfactory adaptation in rats: Insights into cellular and molecular mechanisms of olfactory adaptation.

    Science.gov (United States)

    Zhao, Fuqiang; Wang, Xiaohai; Zariwala, Hatim A; Uslaner, Jason M; Houghton, Andrea K; Evelhoch, Jeffrey L; Hostetler, Eric; Winkelmann, Christopher T; Hines, Catherine D G

    2017-04-01

    Olfactory adaptation, characterized by attenuation of response to repeated odor stimulations or continuous odor exposure, is an intrinsic feature of olfactory processing. Adaptation can be induced by either "synaptic depression" due to depletion of neurotransmitters, or "enhanced inhibition" onto principle neurons by local inhibitory interneurons in olfactory structures. It is not clear which mechanism plays a major role in olfactory adaptation. More importantly, molecular sources of enhanced inhibition have not been identified. In this study, olfactory responses to either repeated 40-s stimulations with interstimulus intervals (ISI) of 140-s or 30-min, or a single prolonged 200-s stimulus were measured by fMRI in different naïve rats. Olfactory adaptations in the olfactory bulb (OB), anterior olfactory nucleus (AON), and piriform cortex (PC) were observed only with repeated 40-s odor stimulations, and no olfactory adaptations were detected during the prolonged 200-s stimulation. Interestingly, in responses to repeated 40-s odor stimulations in the PC, the first odor stimulation induced positive activations, and odor stimulations under adapted condition induced negative activations. The negative activations suggest that "sparse coding" and "global inhibition" are the characteristics of olfactory processing in PC, and the global inhibition manifests only under an adapted condition, not a naïve condition. Further, we found that these adaptations were NMDA receptor dependent; an NMDA receptor antagonist (MK801) blocked the adaptations. Based on the mechanism that glutamate NMDA receptor plays a role in the inhibition onto principle neurons by interneurons, our data suggest that the olfactory adaptations are caused by enhanced inhibition from interneurons. Combined with the necessity of the interruption of odor stimulation to observe the adaptations, the molecular source for the enhanced inhibition is most likely an increased glutamate release from presynaptic

  4. Association of Immune and Metabolic Receptors C5aR and C5L2 with Adiposity in Women

    Science.gov (United States)

    Rezvani, Reza; Gupta, Abhishek; Marceau, Picard; Tchernof, André

    2014-01-01

    Adipose tissue receptors C5aR and C5L2 and their heterodimerization/functionality and interaction with ligands C5a and acylation stimulating protein (ASP) have been evaluated in cell and rodent studies. Their contribution to obesity factors in humans remains unclear. We hypothesized that C5a receptors, classically required for host defense, are also associated with adiposity. Anthropometry and fasting blood parameters were measured in 136 women divided by body mass index (BMI): normal/overweight (≤30 kg/m2; n = 34), obese I (≤45 kg/m2; n = 33), obese II (≤51 kg/m2; n = 33), and obese III (≤80 kg/m2; n = 36). Subcutaneous and omental adipose tissue C5aR and C5L2 expression were analysed. C5L2 expression was comparable between subcutaneous and omental across all BMI groups. Plasma ASP and ASP/omental C5L2 expression increased with BMI (P correlations between C5L2/C5aR and waist circumference, HDL-C, and adiponectin. Tissue and BMI differences in receptors and ligands, particularly in omental, suggest relationship to metabolic disturbances and highlight adipose-immune interactions. PMID:24523571

  5. Metabotrobic Glutamate Receptor mGluR4 as a Novel Target for Parkinson’s Disease.

    Science.gov (United States)

    1999-10-01

    mGIu RECEPTOR AGONISTS G.J. Marek, Dept. of Psychiatry, Yale School of Medicine, New Haven, CT 06508. Serotonin (5-HT), via 5- HT2A receptors...atypical antidepressant and antipsychotic drugs block 5- HT2A receptors, group II and/or HI metabotropic agonists have a potentially promising

  6. Paradoxical sleep deprivation in rats causes a selective reduction in the expression of type-2 metabotropic glutamate receptors in the hippocampus.

    Science.gov (United States)

    Panaccione, Isabella; Iacovelli, Luisa; di Nuzzo, Luigi; Nardecchia, Francesca; Mauro, Gianluca; Janiri, Delfina; De Blasi, Antonio; Sani, Gabriele; Nicoletti, Ferdinando; Orlando, Rosamaria

    2017-03-01

    Paradoxical sleep deprivation in rats is considered as an experimental animal model of mania endowed with face, construct, and pharmacological validity. We induced paradoxical sleep deprivation by placing rats onto a small platform surrounded by water. This procedure caused the animal to fall in the water at the onset of REM phase of sleep. Control rats were either placed onto a larger platform (which allowed them to sleep) or maintained in their home cage. Sleep deprived rats showed a substantial reduction in type-2 metabotropic glutamate (mGlu2) receptors mRNA and protein levels in the hippocampus, but not in the prefrontal cortex or corpus striatum, as compared to both groups of control rats. No changes in the expression of mGlu3 receptor mRNA levels or mGlu1α and mGlu5 receptor protein levels were found with exception of an increase in mGlu1α receptor levels in the striatum of SD rats. Moving from these findings we treated SD and control rats with the selective mGlu2 receptor enhancer, BINA (30mg/kg, i.p.). SD rats were also treated with sodium valproate (300mg/kg, i.p.) as an active comparator. Both BINA and sodium valproate were effective in reversing the manic-like phenotype evaluated in an open field arena in SD rats. BINA treatment had no effect on motor activity in control rats, suggesting that our findings were not biased by a non-specific motor-lowering activity of BINA. These findings suggest that changes in the expression of mGlu2 receptors may be associated with the enhanced motor activity observed with mania. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Dominant negative mutant of ionotropic glutamate receptor subunit GluR3: implications for the role of a cysteine residue for its channel activity and pharmacological properties.

    Science.gov (United States)

    Watase, K; Sekiguchi, M; Matsui, T A; Tagawa, Y; Wada, K

    1997-01-01

    We reported that a 33-amino-acid deletion (from tyrosine-715 to glycine-747) in a putative extracellular loop of GluR3 produced a mutant that exhibited dominant negative effects upon the functional expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors [Sekiguchi et al. (1994) J. Biol. Chem. 269, 14559-14565]. In this study, we searched for a key residue in the dominant negative effects to explore the mechanism and examined the role of the residue in the function of the AMPA receptor. We prepared 20 GluR3 mutants with amino acid substitutions within the 33-amino-acid-region, and dominant negative effects were tested electrophysiologically in Xenopus oocytes co-expressing the mutant and normal subunits. Among the mutants, only a GluR3 mutant in which an original cysteine (Cys)-722 was replaced by alanine exhibited a dominant negative effect comparable with that of the original mutant in which the entire 33-amino-acid segment is deleted. The co-expression of the Cys-722 mutant did not inhibit the translation of normal subunits in oocytes. The Cys-722 mutant formed a functional homomeric receptor with significantly higher affinity for glutamate or kainate than a homomeric GluR3 receptor. The Cys-722 mutation greatly enhanced the sensitivity of GluR3 for aniracetam, which alters kinetic properties of AMPA receptors. The kainate-induced currents in oocytes expressing the Cys-722 mutant alone showed strong inward rectification. These results suggest that the Cys-722 in GluR3 is important for dominant negative effects and plays a crucial role in the determination of pharmacological properties in AMPA receptor function. PMID:9065754

  8. Association of Immune and Metabolic Receptors C5aR and C5L2 with Adiposity in Women

    Directory of Open Access Journals (Sweden)

    Pegah Poursharifi

    2014-01-01

    Full Text Available Adipose tissue receptors C5aR and C5L2 and their heterodimerization/functionality and interaction with ligands C5a and acylation stimulating protein (ASP have been evaluated in cell and rodent studies. Their contribution to obesity factors in humans remains unclear. We hypothesized that C5a receptors, classically required for host defense, are also associated with adiposity. Anthropometry and fasting blood parameters were measured in 136 women divided by body mass index (BMI: normal/overweight (≤30 kg/m2; n = 34, obese I (≤45 kg/m2; n = 33, obese II (≤51 kg/m2; n = 33, and obese III (≤80 kg/m2; n = 36. Subcutaneous and omental adipose tissue C5aR and C5L2 expression were analysed. C5L2 expression was comparable between subcutaneous and omental across all BMI groups. Plasma ASP and ASP/omental C5L2 expression increased with BMI (P < 0.001 and P < 0.01, resp.. While plasma C5a was unchanged, C5aR expression decreased with increasing BMI in subcutaneous and omental tissues (P < 0.01 and P < 0.05, resp., with subcutaneous omental depots. Omental C5L2/C5aR ratio increased with BMI (P < 0.01 with correlations between C5L2/C5aR and waist circumference, HDL-C, and adiponectin. Tissue and BMI differences in receptors and ligands, particularly in omental, suggest relationship to metabolic disturbances and highlight adipose-immune interactions.

  9. Selective agonists at group II metabotropic glutamate receptors: synthesis, stereochemistry, and molecular pharmacology of (S)- and (R)-2-amino-4-(4-hydroxy[1,2,5]thiadiazol-3-yl)butyric acid

    DEFF Research Database (Denmark)

    Clausen, Rasmus P; Bräuner-Osborne, Hans; Greenwood, Jeremy R

    2002-01-01

    Homologation of analogues of the central excitatory neurotransmitter glutamic acid (Glu), in which the distal carboxy group has been bioisosterically replaced by acidic heterocyclic units, has previously provided subtype selective ligands for metabotropic Glu receptors (mGluRs). The (S)-form of t...

  10. Metabotropic glutamate receptor 1 splice variants mGluR1a and mGluR1b combine in mGluR1a/b dimers in vivo

    Czech Academy of Sciences Publication Activity Database

    Techlovská, Šárka; Chambers, Jayne Nicole; Dvořáková, Michaela; Petralia, R.S.; Wang, Y.X.; Hájková, Alena; Franková, Daniela; Prezeau, L.; Blahoš, Jaroslav

    2014-01-01

    Roč. 86, November (2014), s. 329-326 ISSN 0028-3908 R&D Projects: GA ČR GAP303/12/2408 Institutional support: RVO:68378050 Keywords : Glutamate receptors * GPCR * alternative splicing Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.106, year: 2014

  11. Long-term, repeated dose in vitro neurotoxicity of the glutamate receptor antagonist L-AP3, demonstrated in rat hippocampal slice cultures by using continuous propidium iodide incubation

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Blaabjerg, Morten; Noraberg, Jens

    2007-01-01

    Most in vitro models are only used to assess short-term effects of test compounds. However, as demonstrated here, hippocampal slice cultures can be used for long-term studies. The test compound used was the metabotropic glutamate receptor antagonist, L(+)-2-amino-3-phosphonopropionic acid (L-AP3...

  12. 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...

  13. The respective N-hydroxypyrazole analogues of the classical glutamate receptor ligands ibotenic acid and (RS)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid

    DEFF Research Database (Denmark)

    Clausen, Rasmus P; Hansen, Kasper B; Calí, Patrizia

    2004-01-01

    We have determined the pharmacological activity of N-hydroxypyrazole analogues (3a and 4a) of the classical glutamate receptor ligands ibotenic acid and (RS)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid (AMAA), as well as substituted derivatives of these two compounds. The pharmacological...... partial agonism to antagonism with increasing substituent size, substitution abolishes affinity for mglu1 and mglu4 receptors. Ligand- and receptor-based modelling approaches assist in explaining these pharmacological trends among the metabotropic receptors and suggest a mechanism of partial agonism...

  14. Dual effect of beta-amyloid on α7 and α4β2 nicotinic receptors controlling the release of glutamate, aspartate and GABA in rat hippocampus.

    Directory of Open Access Journals (Sweden)

    Elisa Mura

    Full Text Available BACKGROUND: We previously showed that beta-amyloid (Aβ, a peptide considered as relevant to Alzheimer's Disease, is able to act as a neuromodulator affecting neurotransmitter release in absence of evident sign of neurotoxicity in two different rat brain areas. In this paper we focused on the hippocampus, a brain area which is sensitive to Alzheimer's Disease pathology, evaluating the effect of Aβ (at different concentrations on the neurotransmitter release stimulated by the activation of pre-synaptic cholinergic nicotinic receptors (nAChRs, α4β2 and α7 subtypes. Particularly, we focused on some neurotransmitters that are usually involved in learning and memory: glutamate, aspartate and GABA. METHODOLOGY/FINDINGS: WE USED A DUAL APPROACH: in vivo experiments (microdialysis technique on freely moving rats in parallel to in vitro experiments (isolated nerve endings derived from rat hippocampus. Both in vivo and in vitro the administration of nicotine stimulated an overflow of aspartate, glutamate and GABA. This effect was greatly inhibited by the highest concentrations of Aβ considered (10 µM in vivo and 100 nM in vitro. In vivo administration of 100 nM Aβ (the lowest concentration considered potentiated the GABA overflow evoked by nicotine. All these effects were specific for Aβ and for nicotinic secretory stimuli. The in vitro administration of either choline or 5-Iodo-A-85380 dihydrochloride (α7 and α4β2 nAChRs selective agonists, respectively elicited the hippocampal release of aspartate, glutamate, and GABA. High Aβ concentrations (100 nM inhibited the overflow of all three neurotransmitters evoked by both choline and 5-Iodo-A-85380 dihydrochloride. On the contrary, low Aβ concentrations (1 nM and 100 pM selectively acted on α7 subtypes potentiating the choline-induced release of both aspartate and glutamate, but not the one of GABA. CONCLUSIONS/SIGNIFICANCE: The results reinforce the concept that Aβ has relevant

  15. Chronic SSRI stimulation of astrocytic 5-HT2B receptors change multiple gene expressions/editings and metabolism of glutamate, glucose and glycogen: a potential paradigm shift

    Directory of Open Access Journals (Sweden)

    Leif eHertz

    2015-02-01

    Full Text Available It is firmly believed that the mechanism of action of SSRIs in major depression is to inhibit the serotonin transporter, SERT, and increase extracellular concentration of serotonin. However, this undisputed observation does not prove that SERT inhibition is the mechanism, let alone the only mechanism, by which SSRI’s exert their therapeutic effects. It has recently been demonstrated that 5-HT2B receptor stimulation is needed for the antidepressant effect of fluoxetine in vivo. The ability of all 5 currently used SSRIs to stimulate the 5-HT2B receptor equipotentially incultured astrocyteshas been known for several years,and increasing evidence has shown the importance of astrocytes and astrocyte-neuronal interactions for neuroplasticity and complex brain activity. This paper reviews acute and chronic effects of 5-HT2B receptor stimulation in cultured astrocytes and in astrocytes freshly isolated from brains of mice treated with fluoxetine for 14 daystogether with effects ofanti-depressant therapy on turnover of glutamate and GABA and metabolism of glucose and glycogen. It is suggested that these events are causally related to the mechanism of action of SSRIs and of interest for development of newer antidepressant drugs.

  16. Fragment Based Optimization of Metabotropic Glutamate Receptor 2 (mGluR2) Positive Allosteric Modulators in the Absence of Structural Information.

    Science.gov (United States)

    Szabó, György; Túrós, György I; Kolok, Sándor; Vastag, Mónika; Sánta, Zsuzsanna; Dékány, Miklós; Lévay, György I; Greiner, István; Natsumi, Minami; Tatsuya, Watanabe; Keserű, György M

    2018-03-14

    Metabotropic glutamate receptor 2 (mGluR2) positive allosteric modulators (PAMs) have been implicated as potential pharmacotherapy for psychiatric conditions. Screening our corporate compound deck, we identified a benzotriazole fragment (4) that was rapidly optimized to a potent and metabolically stable early lead (16). The highly lipophilic character of 16, together with its limited solubility, permeability, and high protein binding, however, did not allow reaching of the proof of concept in vivo. Since further attempts on the optimization of druglike properties were unsuccessful, the original hit 4 has been revisited and was optimized following the principles of fragment based drug discovery (FBDD). Lacking structural information on the receptor-ligand complex, we implemented a group efficiency (GE) based strategy and identified a new fragment like lead (60) with more balanced profile. Significant improvement achieved on the druglike properties nominated the compound for in vivo proof of concept studies that revealed the chemotype being a promising PAM lead targeting mGluR2 receptors.

  17. Positive Allosteric Modulators of Type 5 Metabotropic Glutamate Receptors (mGluR5 and Their Therapeutic Potential for the Treatment of CNS Disorders

    Directory of Open Access Journals (Sweden)

    Richard M. Cleva

    2011-03-01

    Full Text Available Studies utilizing selective pharmacological antagonists or targeted gene deletion have demonstrated thattype 5 metabotropic glutamate receptors (mGluR5 are critical mediators and potential therapeutic targets for the treatment of numerous disorders of the central nervous system (CNS, including depression, anxiety, drug addiction, chronic pain, Fragile X syndrome, Parkinson’s disease, and gastroesophageal reflux disease. However, in recent years, the development of positive allosteric modulators (PAMs of the mGluR5 receptor have revealed that allosteric activation of this receptor may also be of potential therapeutic benefit for the treatment of other CNS disorders, including schizophrenia, cognitive deficits associated with chronic drug use, and deficits in extinction learning. Here we summarize the discovery and characterization of various mGluR5 PAMs, with an emphasis on those that are systemically active. We will also review animal studies showing that these molecules have potential efficacy as novel antipsychotic agents. Finally, we will summarize findings that suggest that mGluR5 PAMs have pro-cognitive effects such as the ability toenhance synaptic plasticity, improve performance in various learning and memory tasks, including extinction of drug-seeking behavior, and reverse cognitive deficits produced by chronic drug use.

  18. Fear potentiated startle increases phospholipase D (PLD) expression/activity and PLD-linked metabotropic glutamate receptor mediated post-tetanic potentiation in rat amygdala.

    Science.gov (United States)

    Krishnan, Balaji; Scott, Michael T; Pollandt, Sebastian; Schroeder, Bradley; Kurosky, Alexander; Shinnick-Gallagher, Patricia

    2016-02-01

    Long-term memory (LTM) of fear stores activity dependent modifications that include changes in amygdala signaling. Previously, we identified an enhanced probability of release of glutamate mediated signaling to be important in rat fear potentiated startle (FPS), a well-established translational behavioral measure of fear. Here, we investigated short- and long-term synaptic plasticity in FPS involving metabotropic glutamate receptors (mGluRs) and associated downstream proteomic changes in the thalamic-lateral amygdala pathway (Th-LA). Aldolase A, an inhibitor of phospholipase D (PLD), expression was reduced, concurrent with significantly elevated PLD protein expression. Blocking the PLD-mGluR signaling significantly reduced PLD activity. While transmitter release probability increased in FPS, PLD-mGluR agonist and antagonist actions were occluded. In the unpaired group (UNP), blocking the PLD-mGluR increased while activating the receptor decreased transmitter release probability, consistent with decreased synaptic potentials during tetanic stimulation. FPS Post-tetanic potentiation (PTP) immediately following long-term potentiation (LTP) induction was significantly increased. Blocking PLD-mGluR signaling prevented PTP and reduced cumulative PTP probability but not LTP maintenance in both groups. These effects are similar to those mediated through mGluR7, which is co-immunoprecipitated with PLD in FPS. Lastly, blocking mGluR-PLD in the rat amygdala was sufficient to prevent behavioral expression of fear memory. Thus, our study in the Th-LA pathway provides the first evidence for PLD as an important target of mGluR signaling in amygdala fear-associated memory. Importantly, the PLD-mGluR provides a novel therapeutic target for treating maladaptive fear memories in posttraumatic stress and anxiety disorders. Published by Elsevier Inc.

  19. Effect of the Novel Positive Allosteric Modulator of Metabotropic Glutamate Receptor 2 AZD8529 on Incubation of Methamphetamine Craving After Prolonged Voluntary Abstinence in a Rat Model.

    Science.gov (United States)

    Caprioli, Daniele; Venniro, Marco; Zeric, Tamara; Li, Xuan; Adhikary, Sweta; Madangopal, Rajtarun; Marchant, Nathan J; Lucantonio, Federica; Schoenbaum, Geoffrey; Bossert, Jennifer M; Shaham, Yavin

    2015-10-01

    Cue-induced methamphetamine craving increases after prolonged forced (experimenter-imposed) abstinence from the drug (incubation of methamphetamine craving). Here, we determined whether this incubation phenomenon would occur under conditions that promote voluntary (self-imposed) abstinence. We also determined the effect of the novel metabotropic glutamate receptor 2 positive allosteric modulator, AZD8529, on incubation of methamphetamine craving after forced or voluntary abstinence. We trained rats to self-administer palatable food (6 sessions) and then to self-administer methamphetamine under two conditions: 12 sessions (9 hours/day) or 50 sessions (3 hours/day). We then assessed cue-induced methamphetamine seeking in extinction tests after 1 or 21 abstinence days. Between tests, the rats underwent either forced abstinence (no access to the food- or drug-paired levers) or voluntary abstinence (achieved via a discrete choice procedure between methamphetamine and palatable food; 20 trials per day) for 19 days. We also determined the effect of subcutaneous injections of AZD8529 (20 and 40 mg/kg) on cue-induced methamphetamine seeking 1 day or 21 days after forced or voluntary abstinence. Under both training and abstinence conditions, cue-induced methamphetamine seeking in the extinction tests was higher after 21 abstinence days than after 1 day (incubation of methamphetamine craving). AZD8529 decreased cue-induced methamphetamine seeking on day 21 but not day 1 of forced or voluntary abstinence. We introduce a novel animal model to study incubation of drug craving and cue-induced drug seeking after prolonged voluntary abstinence, mimicking the human condition of relapse after successful contingency management treatment. Our data suggest that positive allosteric modulators of metabotropic glutamate receptor 2 should be considered for relapse prevention. Published by Elsevier Inc.

  20. Crystal Structures of the Glutamate Receptor Ion Channel GluK3 and GluK5 Amino-Terminal Domains

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Janesh; Mayer, Mark L. (NIH)

    2010-11-30

    Ionotropic glutamate receptors (iGluRs) mediate the majority of fast excitatory synaptic neurotransmission in the central nervous system. The selective assembly of iGluRs into AMPA, kainate, and N-methyl-d-aspartic acid (NMDA) receptor subtypes is regulated by their extracellular amino-terminal domains (ATDs). Kainate receptors are further classified into low-affinity receptor families (GluK1-GluK3) and high-affinity receptor families (GluK4-GluK5) based on their affinity for the neurotoxin kainic acid. These two families share a 42% sequence identity for the intact receptor but only a 27% sequence identity at the level of ATD. We have determined for the first time the high-resolution crystal structures of GluK3 and GluK5 ATDs, both of which crystallize as dimers but with a strikingly different dimer assembly at the R1 interface. By contrast, for both GluK3 and GluK5, the R2 domain dimer assembly is similar to those reported previously for other non-NMDA iGluRs. This observation is consistent with the reports that GluK4-GluK5 cannot form functional homomeric ion channels and require obligate coassembly with GluK1-GluK3. Our analysis also reveals that the relative orientation of domains R1 and R2 in individual non-NMDA receptor ATDs varies by up to 10{sup o}, in contrast to the 50{sup o} difference reported for the NMDA receptor GluN2B subunit. This restricted domain movement in non-NMDA receptor ATDs seems to result both from extensive intramolecular contacts between domain R1 and domain R2 and from their assembly as dimers, which interact at both R1 and R2 domains. Our results provide the first insights into the structure and function of GluK4-GluK5, the least understood family of iGluRs.

  1. Pregnanolone glutamate, a novel use-dependent NMDA receptor inhibitor, exerts antidepressant-like properties in animal models

    Czech Academy of Sciences Publication Activity Database

    Holubová, Kristína; Nekovářová, Tereza; Pistovčáková, J.; Šulcová, A.; Stuchlík, Aleš; Valeš, Karel

    2014-01-01

    Roč. 8, Apr 16 (2014), s. 130 ISSN 1662-5153 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP303/12/1464; GA MZd(CZ) NT13403; GA TA ČR(CZ) TE01020028 Grant - others:GA MŠk(CZ) LM2011017; GA MŠk(CZ) ED1.1.00/02.0068 Program:ED Institutional support: RVO:67985823 Keywords : depression * anxiety * NMDA channel blocker * neuroactive steroid * 3a5b-pregnanolone glutamate Subject RIV: FH - Neurology Impact factor: 3.270, year: 2014

  2. Disturbance of Metabotropic Glutamate Receptor-Mediated Long-Term Depression (mGlu-LTD) of Excitatory Synaptic Transmission in the Rat Hippocampus After Prenatal Immune Challenge.

    Science.gov (United States)

    Cavalier, Mélanie; Ben Sedrine, Azza; Thevenet, Lea; Crouzin, Nadine; Guiramand, Janique; de Jésus Ferreira, Marie-Céleste; Cohen-Solal, Catherine; Barbanel, Gérard; Vignes, Michel

    2018-01-20

    Maternal immune challenge has proved to induce moderate to severe behavioral disabilities in the offspring. Cognitive/behavioral deficits are supported by changes in synaptic plasticity in different brain areas. We have reported previously that prenatal exposure to bacterial LPS could induce inhibition of hippocampal long-term potentiation (LTP) in the CA1 area of the juvenile/adult male offspring associated with spatial learning inabilities. Nevertheless, deficits in plasticity could be observed at earlier stages as shown by the early loss of long-term depression (LTD) in immature animals. Moreover, aberrant forms of plasticity were also evidenced such as the transient occurrence of LTP instead of LTD in 15-25 day-old animals. This switch from LTD to LTP seemed to involve the activation of metabotropic glutamate receptor subtype 1 and 5 (mGlu1/5). We have thus investigated here whether the long-term depression elicited by the direct activation of these receptors (mGlu-LTD) with a selective agonist was also disturbed after prenatal stress. We find that in prenatally stressed rats, mGlu1/5 stimulation elicits long-term potentiation (mGlu-LTP) independently of N-methyl-D-aspartate receptors. Both mGlu5 and mGlu1 receptors are involved in this switch of plasticity. Moreover, this mGlu-LTP is still observed at later developmental stages than previously reported, i.e. after 25 day-old. In addition, increasing synaptic GABA with tiagabine tends to inhibit mGlu-LTP occurrence. By contrast, long-term depression induced with the activation of CB1 cannabinoid receptor is unaffected by prenatal stress. Therefore, prenatal stress drastically alters mGlu1/5-associated plasticity throughout development. MGlu-mediated plasticity is an interesting parameter to probe the long-lasting deficits reported in this model.

  3. Synthesis of C5-tetrazole derivatives of 2-amino-adipic acid displaying NMDA glutamate receptor antagonism.

    Science.gov (United States)

    Lenda, Fatimazohra; Crouzin, Nadine; Cavalier, Mélanie; Guiramand, Janique; Lanté, Fabien; Barbanel, Gérard; Cohen-Solal, Catherine; Martinez, Jean; Guenoun, Farhate; Lamaty, Frédéric; Vignes, Michel

    2011-03-01

    Five derivatives of 2-amino-adipic acid bearing a tetrazole-substituted in C5 position were synthesized. These compounds displayed selective antagonism towards N-methyl-D: -aspartate (NMDA) receptors compared with AMPA receptors, and they were devoid of any neurotoxicity. Among these five analogues, one exhibited a higher affinity for synaptic NMDA responses than the other four. Therefore, C5 tetrazole-substituted of 2-amino-adipic acid represent an interesting series of new NMDA receptor antagonists. This approach may be considered as a new strategy to develop ligands specifically targeted to synaptic or extra-synaptic NMDA receptors.

  4. Novel 5-HT5A receptor antagonists ameliorate scopolamine-induced working memory deficit in mice and reference memory impairment in aged rats

    Directory of Open Access Journals (Sweden)

    Mayako Yamazaki

    2015-03-01

    Full Text Available Despite the human 5-HT5A receptor being cloned in 1994, the biological function of this receptor has not been extensively characterized due to a lack of specific ligands. We recently reported that the selective 5-HT5A receptor antagonist ASP5736 ameliorated cognitive impairment in several animal models of schizophrenia. Given that areas of the brain with high levels of 5-HT5A receptor expression, such as the hippocampus and cerebral cortex, have important functions in cognition and memory, we evaluated the chemically diverse, potent and brain-penetrating 5-HT5A receptor antagonists ASP5736, AS2030680, and AS2674723 in rodent models of cognitive dysfunction associated with dementia. Each of these compounds exhibited a high affinity for recombinant 5-HT5A receptors that was comparable to that of the non-selective ligand of this receptor, lysergic acid diethylamide (LSD. Although each compound had a low affinity for other receptors, 5-HT5A was the only receptor for which all three compounds had a high affinity. Each of the three compounds ameliorated scopolamine-induced working memory deficit in mice and improved reference memory impairment in aged rats at similar doses. Further, ASP5736 decreased the binding of LSD to 5-HT5A receptors in the olfactory bulb of rats in a dose-dependent manner and occupied 15%–50% of brain 5-HT5A receptors at behaviorally effective doses. These results indicate that the 5-HT5A receptor is involved in learning and memory and that treatment with 5-HT5A receptor antagonists might be broadly effective for cognitive impairment associated with not only schizophrenia but also dementia.

  5. Novel 5-HT5A receptor antagonists ameliorate scopolamine-induced working memory deficit in mice and reference memory impairment in aged rats.

    Science.gov (United States)

    Yamazaki, Mayako; Okabe, Mayuko; Yamamoto, Noriyuki; Yarimizu, Junko; Harada, Katsuya

    2015-03-01

    Despite the human 5-HT5A receptor being cloned in 1994, the biological function of this receptor has not been extensively characterized due to a lack of specific ligands. We recently reported that the selective 5-HT5A receptor antagonist ASP5736 ameliorated cognitive impairment in several animal models of schizophrenia. Given that areas of the brain with high levels of 5-HT5A receptor expression, such as the hippocampus and cerebral cortex, have important functions in cognition and memory, we evaluated the chemically diverse, potent and brain-penetrating 5-HT5A receptor antagonists ASP5736, AS2030680, and AS2674723 in rodent models of cognitive dysfunction associated with dementia. Each of these compounds exhibited a high affinity for recombinant 5-HT5A receptors that was comparable to that of the non-selective ligand of this receptor, lysergic acid diethylamide (LSD). Although each compound had a low affinity for other receptors, 5-HT5A was the only receptor for which all three compounds had a high affinity. Each of the three compounds ameliorated scopolamine-induced working memory deficit in mice and improved reference memory impairment in aged rats at similar doses. Further, ASP5736 decreased the binding of LSD to 5-HT5A receptors in the olfactory bulb of rats in a dose-dependent manner and occupied 15%-50% of brain 5-HT5A receptors at behaviorally effective doses. These results indicate that the 5-HT5A receptor is involved in learning and memory and that treatment with 5-HT5A receptor antagonists might be broadly effective for cognitive impairment associated with not only schizophrenia but also dementia. Copyright © 2015 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  6. Regulation of Synaptic Transmission by Ambient Extracellular Glutamate

    OpenAIRE

    FEATHERSTONE, DAVID E.; SHIPPY, SCOTT A.

    2007-01-01

    Many neuroscientists assume that ambient extracellular glutamate concentrations in the nervous system are biologically negligible under nonpathological conditions. This assumption is false. Hundreds of studies over several decades suggest that ambient extracellular glutamate levels in the intact mammalian brain are ~0.5 to ~5 μM. This has important implications. Glutamate receptors are desensitized by glutamate concentrations significantly lower than needed for receptor activation; 0.5 to 5 μ...

  7. Api5 a new cofactor of estrogen receptor alpha involved in breast cancer outcome

    OpenAIRE

    Basset, C?line; Bonnet-Magnaval, Florence; Navarro, Marina Garcia-Jove; Touriol, Christian; Courtade, Monique; Prats, Herv?; Garmy-Susini, Barbara; Lacazette, Eric

    2017-01-01

    Api5 (Apoptosis inhibitor 5) is an anti-apoptotic factor that confers resistance to genotoxic stress in human cancer. Api5 is also expressed in endothelial cells and participates to the Estrogen Receptor ? (ER?) signaling to promote cell migration. In this study, we found an over expression of Api5 in human breast cancer. Given that we show that high expression of Api5 in breast cancer patients is associated with shorter recurrence free survival, we investigated the relationship between ER? a...

  8. Iterative use of nuclear receptor Nr5a2 regulates multiple stages of liver and pancreas development.

    Science.gov (United States)

    Nissim, Sahar; Weeks, Olivia; Talbot, Jared C; Hedgepeth, John W; Wucherpfennig, Julia; Schatzman-Bone, Stephanie; Swinburne, Ian; Cortes, Mauricio; Alexa, Kristen; Megason, Sean; North, Trista E; Amacher, Sharon L; Goessling, Wolfram

    2016-10-01

    The stepwise progression of common endoderm progenitors into differentiated liver and pancreas organs is regulated by a dynamic array of signals that are not well understood. The nuclear receptor subfamily 5, group A, member 2 gene nr5a2, also known as Liver receptor homolog-1 (Lrh-1) is expressed in several tissues including the developing liver and pancreas. Here, we interrogate the role of Nr5a2 at multiple developmental stages using genetic and chemical approaches and uncover novel pleiotropic requirements during zebrafish liver and pancreas development. Zygotic loss of nr5a2 in a targeted genetic null mutant disrupted the development of the exocrine pancreas and liver, while leaving the endocrine pancreas intact. Loss of nr5a2 abrogated exocrine pancreas markers such as trypsin, while pancreas progenitors marked by ptf1a or pdx1 remained unaffected, suggesting a role for Nr5a2 in regulating pancreatic acinar cell differentiation. In the developing liver, Nr5a2 regulates hepatic progenitor outgrowth and differentiation, as nr5a2 mutants exhibited reduced hepatoblast markers hnf4α and prox1 as well as differentiated hepatocyte marker fabp10a. Through the first in vivo use of Nr5a2 chemical antagonist Cpd3, the iterative requirement for Nr5a2 for exocrine pancreas and liver differentiation was temporally elucidated: chemical inhibition of Nr5a2 function during hepatopancreas progenitor specification was sufficient to disrupt exocrine pancreas formation and enhance the size of the embryonic liver, suggesting that Nr5a2 regulates hepatic vs. pancreatic progenitor fate choice. Chemical inhibition of Nr5a2 at a later time during pancreas and liver differentiation was sufficient to block the formation of mature acinar cells and hepatocytes. These findings define critical iterative and pleiotropic roles for Nr5a2 at distinct stages of pancreas and liver organogenesis, and provide novel perspectives for interpreting the role of Nr5a2 in disease. Copyright © 2016

  9. Methods for antagonizing glutamate neurotoxicity.

    Science.gov (United States)

    Choi, D W

    1990-01-01

    Recent evidence suggests that glutamate-induced neuronal damage may contribute importantly to neuronal death in several neurological diseases, including cerebral hypoxia-ischemia. This review outlines a range of measures that might be used to protect neurons from such excitotoxic damage. The organizing thesis is a speculative consideration of glutamate neurotoxicity as a sequential three-stage process--induction, amplification, and expression--each perhaps specifically amenable to therapeutic interference. Overstimulation of glutamate receptors likely induces the intracellular accumulation of several substances, including Ca2+, Na+, inositol-1,4,5-trisphosphate, and diacylglycerol. Blockade of this induction might be accomplished most easily by antagonizing postsynaptic glutamate receptors, but also might be accomplished by reducing glutamate release from presynaptic terminals, or improving glutamate clearance from synaptic clefts. Following induction, several steps may importantly amplify the resultant rise in intracellular free Ca2+, and promote the spread of excessive excitation to other circuit neurons. Protective strategies operative at this level might include blockade of additional Ca2+ influx, blockade of Ca2+ release from intracellular stores, and interference with the mechanisms coupling glutamate receptor stimulation to lasting enhancements of excitatory synaptic efficacy. Following amplification, toxic levels of intracellular free Ca2+ might trigger destructive cascades bearing direct responsibility for resultant neuronal degeneration--the expression of excitotoxicity. The most important cascades to block may be those related to the activation of catabolic enzymes, and the generation of free radicals. Broad consideration of possible methods for antagonizing glutamate neurotoxicity may be needed to develop therapies with the greatest efficacy, and least adverse consequences for brain function.

  10. Investigating Metabotropic Glutamate Receptor 5 Allosteric Modulator Cooperativity, Affinity, and Agonism: Enriching Structure-Function Studies and Structure-Activity Relationships

    Science.gov (United States)

    Gregory, Karen J.; Noetzel, Meredith J.; Rook, Jerri M.; Vinson, Paige N.; Stauffer, Shaun R.; Rodriguez, Alice L.; Emmitte, Kyle A.; Zhou, Ya; Chun, Aspen C.; Felts, Andrew S.; Chauder, Brian A.; Lindsley, Craig W.; Niswender, Colleen M.

    2012-01-01

    Drug discovery programs increasingly are focusing on allosteric modulators as a means to modify the activity of G protein-coupled receptor (GPCR) targets. Allosteric binding sites are topographically distinct from the endogenous ligand (orthosteric) binding site, which allows for co-occupation of a single receptor with the endogenous ligand and an allosteric modulator that can alter receptor pharmacological characteristics. Negative allosteric modulators (NAMs) inhibit and positive allosteric modulators (PAMs) enhance the affinity and/or efficacy of orthosteric agonists. Established approaches for estimation of affinity and efficacy values for orthosteric ligands are not appropriate for allosteric modulators, and this presents challenges for fully understanding the actions of novel modulators of GPCRs. Metabotropic glutamate receptor 5 (mGlu5) is a family C GPCR for which a large array of allosteric modulators have been identified. We took advantage of the many tools for probing allosteric sites on mGlu5 to validate an operational model of allosterism that allows quantitative estimation of modulator affinity and cooperativity values. Affinity estimates derived from functional assays fit well with affinities measured in radioligand binding experiments for both PAMs and NAMs with diverse chemical scaffolds and varying degrees of cooperativity. We observed modulation bias for PAMs when we compared mGlu5-mediated Ca2+ mobilization and extracellular signal-regulated kinase 1/2 phosphorylation data. Furthermore, we used this model to quantify the effects of mutations that reduce binding or potentiation by PAMs. This model can be applied to PAM and NAM potency curves in combination with maximal fold-shift data to derive reliable estimates of modulator affinities. PMID:22863693

  11. Selectivity and evolutionary divergence of metabotropic glutamate receptors for endogenous ligands and G proteins coupled to phospholipase C or TRP channels.

    Science.gov (United States)

    Kang, Hye Jin; Menlove, Kit; Ma, Jianpeng; Wilkins, Angela; Lichtarge, Olivier; Wensel, Theodore G

    2014-10-24

    To define the upstream and downstream signaling specificities of metabotropic glutamate receptors (mGluR), we have examined the ability of representative mGluR of group I, II, and III to be activated by endogenous amino acids and catalyze activation of G proteins coupled to phospholipase C (PLC), or activation of G(i/o) proteins coupled to the ion channel TRPC4β. Fluorescence-based assays have allowed us to observe interactions not previously reported or clearly identified. We have found that the specificity for endogenous amino acids is remarkably stringent. Even at millimolar levels, structurally similar compounds do not elicit significant activation. As reported previously, the clear exception is L-serine-O-phosphate (L-SOP), which strongly activates group III mGluR, especially mGluR4,-6,-8 but not group I or II mGluR. Whereas L-SOP cannot activate mGluR1 or mGluR2, it acts as a weak antagonist for mGluR1 and a potent antagonist for mGluR2, suggesting that co-recognition of L-glutamate and L-SOP arose early in evolution, and was followed later by divergence of group I and group II mGluR versus group III in l-SOP responses. mGluR7 has low affinity and efficacy for activation by both L-glutamate and L-SOP. Molecular docking studies suggested that residue 74 corresponding to lysine in mGluR4 and asparagine in mGluR7 might play a key role, and, indeed, mutagenesis experiments demonstrated that mutating this residue to lysine in mGluR7 enhances the potency of L-SOP. Experiments with pertussis toxin and dominant-negative Gα(i/o) proteins revealed that mGluR1 couples strongly to TRPC4β through Gα(i/o), in addition to coupling to PLC through Gα(q/11). © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Selectivity and Evolutionary Divergence of Metabotropic Glutamate Receptors for Endogenous Ligands and G Proteins Coupled to Phospholipase C or TRP Channels*

    Science.gov (United States)

    Kang, Hye Jin; Menlove, Kit; Ma, Jianpeng; Wilkins, Angela; Lichtarge, Olivier; Wensel, Theodore G.

    2014-01-01

    To define the upstream and downstream signaling specificities of metabotropic glutamate receptors (mGluR), we have examined the ability of representative mGluR of group I, II, and III to be activated by endogenous amino acids and catalyze activation of G proteins coupled to phospholipase C (PLC), or activation of Gi/o proteins coupled to the ion channel TRPC4β. Fluorescence-based assays have allowed us to observe interactions not previously reported or clearly identified. We have found that the specificity for endogenous amino acids is remarkably stringent. Even at millimolar levels, structurally similar compounds do not elicit significant activation. As reported previously, the clear exception is l-serine-O-phosphate (l-SOP), which strongly activates group III mGluR, especially mGluR4,-6,-8 but not group I or II mGluR. Whereas l-SOP cannot activate mGluR1 or mGluR2, it acts as a weak antagonist for mGluR1 and a potent antagonist for mGluR2, suggesting that co-recognition of l-glutamate and l-SOP arose early in evolution, and was followed later by divergence of group I and group II mGluR versus group III in l-SOP responses. mGluR7 has low affinity and efficacy for activation by both l-glutamate and l-SOP. Molecular docking studies suggested that residue 74 corresponding to lysine in mGluR4 and asparagine in mGluR7 might play a key role, and, indeed, mutagenesis experiments demonstrated that mutating this residue to lysine in mGluR7 enhances the potency of l-SOP. Experiments with pertussis toxin and dominant-negative Gαi/o proteins revealed that mGluR1 couples strongly to TRPC4β through Gαi/o, in addition to coupling to PLC through Gαq/11. PMID:25193666

  13. The metabotropic glutamate receptor, mGlu5, is required for extinction learning that occurs in the absence of a context change.

    Science.gov (United States)

    André, Marion Agnes Emma; Güntürkün, Onur; Manahan-Vaughan, Denise

    2015-02-01

    The metabotropic glutamate (mGlu) receptors and, in particular, mGlu5 are crucially involved in multiple forms of synaptic plasticity that are believed to underlie explicit memory. MGlu5 is also required for information transfer through neuronal oscillations and for spatial memory. Furthermore, mGlu5 is involved in extinction of implicit forms of learning. This places this receptor in a unique position with regard to information encoding. Here, we explored the role of this receptor in context-dependent extinction learning under constant, or changed, contextual conditions. Animals were trained over 3 days to take a left turn under 25% reward probability in a T-maze with a distinct floor pattern (Context A). On Day 4, they experienced either a floor pattern change (Context B) or the same floor pattern (Context A) in the absence of reward. After acquisition of the task, the animals were returned to the maze once more on Day 5 (Context A, no reward). Treatment with the mGlu5 antagonist, 2-methyl-6-(phenylethynyl) pyridine, before maze exposure on Day 4 completely inhibited extinction learning in the AAA paradigm but had no effect in the ABA paradigm. A subsequent return to the original context (A, on Day 5) revealed successful extinction in the AAA paradigm, but impairment of extinction in the ABA paradigm. These data support that although extinction learning in a new context is unaffected by mGlu5 antagonism, extinction of the consolidated context is impaired. This suggests that mGlu5 is intrinsically involved in enabling learning that once-relevant information is no longer valid. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc.

  14. Identification of single nucleotide polymorphisms of the human metabotropic glutamate receptor 1 gene and pharmacological characterization of a P993S variant.

    Science.gov (United States)

    Downey, Patrick M; Petrò, Roberta; Simon, Jason S; Devlin, David; Lozza, Gianluca; Veltri, Alessio; Beltramo, Massimiliano; Bertorelli, Rosalia; Reggiani, Angelo

    2009-04-01

    mGluR1 receptors are believed to play major roles in the pathophysiology of diseases such as anxiety and chronic pain and are being actively investigated as targets for drug development. Sequence polymorphisms can potentially influence the efficacy of drugs in patient populations and are therefore an important consideration in the drug development process. To identify DNA sequence variants of the mGluR1 receptor, comparative DNA sequencing was performed on DNA samples (n=186) from apparently healthy subjects representing two ethnic groups. In total, eight non-synonymous single nucleotide polymorphisms (SNPs) were identified and one SNP (c2977>T) was found to be particularly common, this SNP results in a proline to serine substitution at residue 993 (P993S). The WT (P993) and S993 variants were expressed in an inducible system which allowed us to titrate gene expression to equivalent levels and were pharmacologically characterized. We determined the potency and affinity of standard antagonist compounds as well as the potency and efficacy of the endogenous ligand glutamate and other agonist compounds at both receptor variants. Agonist evoked increases in intracellular Ca(2+) were measured by fluorometric imaging plate reader (FLIPR). The potency of mGluR1 antagonists was evaluated by their ability to inhibit quisqualate induced increases in intracellular Ca(2+), while their affinities were determined by radio-ligand binding studies. This study demonstrates that the Pro993Ser amino acid exchange is highly frequent in the human mGluR1 gene. This polymorphism however, does not appear to affect the potency of agonist compounds or the potencies or affinities of small molecule antagonist compounds.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Mariana P.C. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal); Nunes-Correia, Isabel [Center for Neuroscience and Cell Biology, Flow Cytometry Unit, University of Coimbra, 3000-354 Coimbra (Portugal); Santos, Armanda E., E-mail: aesantos@ci.uc.pt [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal); Custódio, José B.A. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal)

    2014-02-15

    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.

  16. Propranolol decreases retention of fear memory by modulating the stability of surface glutamate receptor GluA1 subunits in the lateral amygdala.

    Science.gov (United States)

    Zhou, Jun; Luo, Yi; Zhang, Jie-Ting; Li, Ming-Xing; Wang, Can-Ming; Guan, Xin-Lei; Wu, Peng-Fei; Hu, Zhuang-Li; Jin, You; Ni, Lan; Wang, Fang; Chen, Jian-Guo

    2015-11-01

    Posttraumatic stress disorder (PTSD) is a mental disorder with enhanced retention of fear memory and has profound impact on quality of life for millions of people worldwide. The β-adrenoceptor antagonist propranolol has been used in preclinical and clinical studies for the treatment of PTSD, but the mechanisms underlying its potential efficacy on fear memory retention remain to be elucidated. We investigated the action of propranolol on the retention of conditioned fear memory, the surface expression of glutamate receptor GluA1 subunits of AMPA receptors and synaptic adaptation in the lateral amygdala (LA) of rats. Propranolol attenuated reactivation-induced strengthening of fear retention while reducing enhanced surface expression of GluA1 subunits and restoring the impaired long-term depression in LA. These effects of propranolol were mediated by antagonizing reactivation-induced enhancement of adrenergic signalling, which activates PKA and calcium/calmodulin-dependent protein kinase II and then regulates the trafficking of AMPA receptors via phosphorylation of GluA1 subunits at the C-terminus. Both i.p. injection and intra-amygdala infusion of propranolol attenuated reactivation-induced enhancement of fear retention. Reactivation strengthens fear retention by increasing the level of noradrenaline and promotes the surface expression of GluA1 subunits and the excitatory synaptic transmission in LA. These findings uncover one mechanism underlying the efficiency of propranolol on retention of fear memories and suggest that β-adrenoceptor antagonists, which act centrally, may be more suitable for the treatment of PTSD. © 2015 The British Pharmacological Society.

  17. Molecular Characterization of Native and Recom­binant Ionotrophic Glutamate Receptors Expressed in Neurons and Heterologous Systems

    DEFF Research Database (Denmark)

    Drasbek, Kim Ryun

    2005-01-01

    trafficking mediating the continuous replacement of synaptic receptors and is important for receptor tetramerization in the endoplasmatic reticulum. Given the many important properties of the GluR2 subunit, it was of great interest to investigate and compare synaptic properties in neuronal populations...... in synaptic currents of receptors from these neuronal preparations, miniature excitatory postsynaptic currents (mEPSCs) were recorded followed by single cell RT-PCR of the same neuron. Unfortunately, no population of GluR2 lacking neurons was detected by single cell RT-PCR, but a higher detection frequency...... expressing AMPARs with or without the GluR2 subunits. Earlier findings suggested that neurons cultured from spinal cord were devoid of GluR2 and expressed high amounts of GluR4. In contrast, GluR2 was detected in almost all cells from cortical cultures (Dai et al., 2001). To investigate differences...

  18. Metabotropic glutamate receptor 2 and corticotrophin-releasing factor receptor-1 gene expression is differently regulated by BDNF in rat primary cortical neurons

    DEFF Research Database (Denmark)

    Jørgensen, Christinna V; Klein, Anders B; El-Sayed, Mona

    2013-01-01

    Brain-derived neurotrophic factor (BDNF) is important for neuronal survival and plasticity. Incorporation of matured receptor proteins is an integral part of synapse formation. However, whether BDNF increases synthesis and integration of receptors in functional synapses directly is unclear. We...

  19. Activation of nuclear receptor NR5A2 increases Glut4 expression and glucose metabolism in muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Bolado-Carrancio, A. [Department of Molecular Biology, University of Cantabria, IDIVAL, Santander (Spain); Riancho, J.A. [Department of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL, University of Cantabria, RETICEF, Santander (Spain); Sainz, J. [Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC-University of Cantabria, Santander (Spain); Rodríguez-Rey, J.C., E-mail: rodriguj@unican.es [Department of Molecular Biology, University of Cantabria, IDIVAL, Santander (Spain)

    2014-04-04

    Highlights: • NR5A2 expression in C2C12 is associated with myotube differentiation. • DLPC induces an increase in GLUT4 levels and glucose uptake in C2C12 myotubes. • In high glucose conditions the activation of NR5A2 inhibits fatty acids oxidation. - Abstract: NR5A2 is a nuclear receptor which regulates the expression of genes involved in cholesterol metabolism, pluripotency maintenance and cell differentiation. It has been recently shown that DLPC, a NR5A2 ligand, prevents liver steatosis and improves insulin sensitivity in mouse models of insulin resistance, an effect that has been associated with changes in glucose and fatty acids metabolism in liver. Because skeletal muscle is a major tissue in clearing glucose from blood, we studied the effect of the activation of NR5A2 on muscle metabolism by using cultures of C2C12, a mouse-derived cell line widely used as a model of skeletal muscle. Treatment of C2C12 with DLPC resulted in increased levels of expression of GLUT4 and also of several genes related to glycolysis and glycogen metabolism. These changes were accompanied by an increased glucose uptake. In addition, the activation of NR5A2 produced a reduction in the oxidation of fatty acids, an effect which disappeared in low-glucose conditions. Our results suggest that NR5A2, mostly by enhancing glucose uptake, switches muscle cells into a state of glucose preference. The increased use of glucose by muscle might constitute another mechanism by which NR5A2 improves blood glucose levels and restores insulin sensitivity.

  20. Restraint stress differentially regulates inflammation and glutamate receptor gene expression in the hippocampus of C57BL/6 and BALB/c mice.

    Science.gov (United States)

    Sathyanesan, Monica; Haiar, Jacob M; Watt, Michael J; Newton, Samuel S

    2017-03-01

    The inbred mouse strains, C57BL/6 and BALB/c have been used widely in preclinical psychiatric research. The differences in stress susceptibility of available strains has provided a useful platform to test pharmacological agents and behavioral responses. Previous brain gene profiling efforts have indicated that the inflammation and immune response gene pathway is the predominant gene network in the differential stress response of BALB/c and C57BL/6 mice. The implication is that a composite stress paradigm that includes a sequence of extended, varied and unpredictable stressors induces inflammation-related genes in the hippocampus. We hypothesized that the regulation of inflammation genes in the brain could constitute a primary stress response and tested this by employing a simple stress protocol, repeated exposure to the same stressor for 10 days, 2 h of restraint per day. We examined stress-induced regulation of 13 proinflammatory cytokine genes in male BALB/c and C57BL/6 mice using quantitative PCR. Elevated cytokine genes included tumor necrosis factor alpha (TNFα), interleukin 6 (IL6), interleukin 10 (IL10), tumor necrosis factor (TNF) super family members and interleukin 1 receptor 1 (IL1R1). In addition, we examined restraint stress-induced regulation of 12 glutamate receptor genes in both strains. Our results show that restraint stress is sufficient to elevate the expression of inflammation-related genes in the hippocampus of both BABLB/c and C57BL/6 mice, but they differ in the genes that are induced and the magnitude of change. Cell types that are involved in this response include endothelial cells and astrocytes. Lay summary Repeated exposure to a simple restraint stress altered the activities of genes involved in inflammation and the functions of the excitatory neurotransmitter, glutamate. These changes in the hippocampus of the mouse brain showed differences that were dependent on the strain of mice and the length of the stress exposure. The effects

  1. Synthesis of (3-hydroxy-pyrazolin-5-yl)glycine based ligands interacting with ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Pinto, A; Tamborini, L; Mastronardi, F

    2014-01-01

    Following the concept that increasing the molecular complexity may enhance the receptor selectivity, we replaced the 3-hydroxy-isoxazoline ring of model compound tricholomic acid with a 3-hydroxy-pyrazoline ring, which could be variously decorated at the N1 position, inserting groups characterize...

  2. Modulation of the dimer interface at ionotropic glutamate-like receptor d2 by D-serine and extracellular calcium

    DEFF Research Database (Denmark)

    Hansen, Kasper Bø; Naur, Peter; Kurtkaya, Natalie L

    2009-01-01

    GluRdelta2 is a member of the iGluR family, but despite a prominent role in cerebellar synaptic plasticity, this receptor does not appear to function as an ion channel. Endogenous ligands that modulate the activity of native GluRdelta2 in the cerebellum have not been identified, but two candidate...

  3. 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

    neuroprotective effect when tested in an oxygen glucose deprivation (OGD) cell culture test. The same compounds were preliminarily assayed using Xenopus oocytes expressing cloned rat NMDA receptors containing the NR1 subunit in combination with either NR2A, NR2B, NR2C, or NR2D subunit. In this assay, all three...

  4. Neuroexcitatory amino acids: 4-methylene glutamic acid derivatives : Short Communication.

    Science.gov (United States)

    Receveur, J M; Roumestant, M L; Viallefont, P

    1995-12-01

    A short synthesis of 4-methylene glutamic acid was achieved. Under thermal conditions the corresponding anhydride reacted with 2,3 dimethylbutadiene to afford the corresponding DIELS-ALDER adduct in good yield. L-4-methylene glutamic acid essentially acts on glutamate metabotropic receptors and is as potent as L-Glu in producing IPs.

  5. Glutamate Receptor Antagonists as Fast-Acting Therapeutic Alternatives for the Treatment of Depression: Ketamine and Other Compounds

    Science.gov (United States)

    Niciu, Mark J.; Henter, Ioline D.; Luckenbaugh, David A.; Zarate, Carlos A.; Charney, Dennis S.

    2014-01-01

    The N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has rapid and potent antidepressant effects in treatment-resistant major depressive disorder and bipolar depression. These effects are in direct contrast to the more modest effects seen after weeks of treatment with classic monoaminergic antidepressants. Numerous open-label and case studies similarly validate ketamine’s antidepressant properties. These clinical findings have been reverse-translated into preclinical models in an effort to elucidate ketamine’s antidepressant mechanism of action, and three important targets have been identified: mammalian target of rapamycin (mTOR), eukaryotic elongation factor 2 (eEF2), and glycogen synthase kinase-3 (GSK-3). Current clinical and preclinical research is focused on (a) prolonging/maintaining ketamine’s antidepressant effects, (b) developing more selective NMDA receptor antagonists free of ketamine’s adverse effects, and (c) identifying predictor, mediator/moderator, and treatment response biomarkers of ketamine’s antidepressant effects. PMID:24392693

  6. Molecular characterization of the gerbil C5a receptor and identification of a transmembrane domain V amino acid that is crucial for small molecule antagonist interaction.

    Science.gov (United States)

    Waters, Stephen M; Brodbeck, Robbin M; Steflik, Jeremy; Yu, Jianying; Baltazar, Carolyn; Peck, Amy E; Severance, Daniel; Zhang, Lu Yan; Currie, Kevin; Chenard, Bertrand L; Hutchison, Alan J; Maynard, George; Krause, James E

    2005-12-09

    Anaphylatoxin C5a is a potent inflammatory mediator associated with pathogenesis and progression of several inflammation-associated disorders. Small molecule C5a receptor (C5aR) antagonist development is hampered by species-specific receptor biology and the associated inability to use standard rat and mouse in vivo models. Gerbil is one rodent species reportedly responsive to small molecule C5aR antagonists with human C5aR affinity. We report the identification of the gerbil C5aR cDNA using a degenerate primer PCR cloning strategy. The nucleotide sequence revealed an open reading frame encoding a 347-amino acid protein. The cloned receptor (expressed in Sf9 cells) bound recombinant human C5a with nanomolar affinity. Alignment of the gerbil C5aR sequence with those from other species showed that a Trp residue in transmembrane domain V is the only transmembrane domain amino acid unique to small molecule C5aR antagonist-responsive species (i.e. gerbil, human, and non-human primate). Site-directed mutagenesis was used to generate human and mouse C5aRs with a residue exchange of this Trp residue. Mutation of Trp to Leu in human C5aR completely eliminated small molecule antagonist-receptor interaction. In contrast, mutation of Leu to Trp in mouse C5aR enabled small molecule antagonist-receptor interaction. This crucial Trp residue is located deeper within transmembrane domain V than residues reportedly involved in C5a- and cyclic peptide C5a antagonist-receptor interaction, suggesting a novel interaction site(s) for small molecule antagonists. These data provide insight into the basis for small molecule antagonist species selectivity and further define sites critical for C5aR activation and function.

  7. Pharmacological modulation of metabotropic glutamate receptor subtype 5 and 7 impairs extinction of social fear in a time-point-dependent manner.

    Science.gov (United States)

    Slattery, David A; Neumann, Inga D; Flor, Peter J; Zoicas, Iulia

    2017-06-15

    Pharmacological modulation of metabotropic glutamate receptor subtype 5 (mGluR5) and 7 (mGluR7) was shown to attenuate the acquisition and to facilitate the extinction of cued and contextual, non-social, fear. Using the allosteric mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and the allosteric mGluR7 agonist N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082), we aimed to study how pharmacological blockade of mGluR5 and activation of mGluR7 influence acquisition and extinction of social fear in mice. We could show that when administered before social fear conditioning, neither MPEP nor AMN082 affected acquisition and extinction of social fear, suggesting that mGluR5 inactivation and mGluR7 activation do not alter social fear. However, when administered before social fear extinction, both MPEP and AMN082 impaired social fear extinction and extinction recall. These findings suggest that mGluR5 inactivation and mGluR7 activation are unlikely to prevent the formation of traumatic social memories. Furthermore, medication strategies aimed at augmenting exposure-based therapies for psychiatric disorders associated with social deficits via modulation of mGluR5 and mGluR7 must be pursued cautiously because of their potential to delay social fear extinction processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. A case-control study of the relationship between the metabotropic glutamate receptor 3 gene and schizophrenia in the Chinese population.

    Science.gov (United States)

    Chen, Qi; He, Guang; Chen, Qingying; Wu, Shengnan; Xu, Yifeng; Feng, Guoyin; Li, Yucheng; Wang, Lijun; He, Lin

    2005-02-01

    Recent studies of the association between the metabotropic glutamate receptor 3 gene (GRM3) and schizophrenia have produced conflicting results, although GRM3 is a promising candidate gene. Fujii et al. found a single nuclear polymorphism (SNP) for within this gene, rs1468412 to have a positive association to schizophrenia in Japanese patients. To investigate this further, we genotyped 7 SNPs around GRM3 including rs1468412, in 752 Chinese patients with schizophrenia and 752 controls using Taqman technology. We did not detect any association between rs1468412 and schizophrenia, however we found differences in the allele frequency distribution of SNP rs2299225 (p=0.0297, odds ration [OR]=1.44, 95% confidence interval 1.05-1.99) between cases and controls. Moreover, the overall frequency of haplotypes constructed from three SNPs including rs2299225 showed significant differences between cases and controls (p=0.0017). Our results partially support the previous studies in other ethnic groups and indicate that the GRM3 gene may play an important role in the etiology of schizophrenia in the Han Chinese.

  9. 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...

  10. In Vitro and Clinical Evaluations of the Drug-Drug Interaction Potential of a Metabotropic Glutamate 2/3 Receptor Agonist Prodrug with Intestinal Peptide Transporter 1.

    Science.gov (United States)

    Pak, Y Anne; Long, Amanda J; Annes, William F; Witcher, Jennifer W; Knadler, Mary Pat; Ayan-Oshodi, Mosun A; Mitchell, Malcolm I; Leese, Phillip; Hillgren, Kathleen M

    2017-02-01

    Despite peptide transporter 1 (PEPT1) being responsible for the bioavailability for a variety of drugs, there has been little study of its potential involvement in drug-drug interactions. Pomaglumetad methionil, a metabotropic glutamate 2/3 receptor agonist prodrug, utilizes PEPT1 to enhance absorption and bioavailability. In vitro studies were conducted to guide the decision to conduct a clinical drug interaction study and to inform the clinical study design. In vitro investigations determined the prodrug (LY2140023 monohydrate) is a substrate of PEPT1 with K m value of approximately 30 µM, whereas the active moiety (LY404039) is not a PEPT1 substrate. In addition, among the eight known PEPT1 substrates evaluated in vitro, valacyclovir was the most potent inhibitor (IC 50 = 0.46 mM) of PEPT1-mediated uptake of the prodrug. Therefore, a clinical drug interaction study was conducted to evaluate the potential interaction between the prodrug and valacyclovir in healthy subjects. No effect of coadministration was observed on the pharmacokinetics of the prodrug, valacyclovir, or either of their active moieties. Although in vitro studies showed potential for the prodrug and valacyclovir interaction via PEPT1, an in vivo study showed no interaction between these two drugs. PEPT1 does not appear to easily saturate because of its high capacity and expression in the intestine. Thus, a clinical interaction at PEPT1 is unlikely even with a compound with high affinity for the transporter. Copyright © 2017 by The Author(s).

  11. No improvement of functional and histological outcome after application of the metabotropic glutamate receptor 5 agonist CHPG in a model of endothelin-1-induced focal ischemia in rats.

    Science.gov (United States)

    Riek-Burchardt, M; Henrich-Noack, P; Reymann, K G

    2007-04-01

    The role of group I metabotropic glutamate receptors (mGluRs) in neurodegeneration is as yet unclear as mGluR1/5 antagonists and agonists yielded contradictory effects in different disease models. In the present study, we examined the neuroprotective potency of the selective mGluR5 agonist, (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG), in endothelin-1(ET-1)-induced focal ischemia in rats. In addition to the effect of CHPG on the histologically defined infarct size, we studied its influence on sensorimotor impairments in the ladder rung walking test at late time points up to 4 weeks after the ischemic insult. Rats were treated i.c.v. with an injection of 1mM CHPG beginning 10min after the application of ET-1. Histological analyses 4 weeks after ET-1-induced ischemia demonstrated only a small, insignificant reduction in infarct size after CHPG application. In accordance with this result, there were no significant effects of the used CHPG concentration on sensorimotor impairments in the ladder rung walking test. In conclusion, our data point to the restricted value of CHPG as a neuroprotectant after transient focal ischemia and to the importance of evaluating neuroprotective effects at late post-ischemic time points.

  12. Effects of the metabotropic glutamate receptor 5 positive allosteric modulator CDPPB on rats tested with the paired associates learning task in touchscreen-equipped operant conditioning chambers.

    Science.gov (United States)

    Lins, Brittney R; Howland, John G

    2016-03-15

    Effective treatments for the cognitive symptoms of schizophrenia are critically needed. Positive allosteric modulation (PAM) of metabotropic glutamate receptor subtype 5 (mGluR5) is one strategy currently under investigation to improve these symptoms. Examining cognition using touchscreen-equipped operant chambers may increase translation between preclinical and clinical research through analogous behavioral testing paradigms in rodents and humans. We used acute CDPPB (1-30mg/kg) treatment to examine the effects of mGluR5 PAM in the touchscreen paired associates learning (PAL) task using well-trained rats with and without co-administration of acute MK-801 (0.15mg/kg). CDPPB had no consistent effects on task performance when administered alone and failed to reverse the MK-801 induced impairments at any of the examined doses. Overall, the disruptive effects of MK-801 on PAL were consistent with previous research but increasing mGluR5 signaling is not beneficial in the PAL task. Future research should test whether administration of CDPPB during PAL acquisition increases performance. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. β-Arrestin2 Couples Metabotropic Glutamate Receptor 5 to Neuronal Protein Synthesis and Is a Potential Target to Treat Fragile X.

    Science.gov (United States)

    Stoppel, Laura J; Auerbach, Benjamin D; Senter, Rebecca K; Preza, Anthony R; Lefkowitz, Robert J; Bear, Mark F

    2017-03-21

    Synaptic protein synthesis is essential for modification of the brain by experience and is aberrant in several genetically defined disorders, notably fragile X (FX), a heritable cause of autism and intellectual disability. Neural activity directs local protein synthesis via activation of metabotropic glutamate receptor 5 (mGlu 5 ), yet how mGlu 5 couples to the intracellular signaling pathways that regulate mRNA translation is poorly understood. Here, we provide evidence that β-arrestin2 mediates mGlu 5 -stimulated protein synthesis in the hippocampus and show that genetic reduction of β-arrestin2 corrects aberrant synaptic plasticity and cognition in the Fmr1 -/y mouse model of FX. Importantly, reducing β-arrestin2 does not induce psychotomimetic activity associated with full mGlu 5 inhibitors and does not affect G q signaling. Thus, in addition to identifying a key requirement for mGlu 5 -stimulated protein synthesis, these data suggest that β-arrestin2-biased negative modulators of mGlu 5 offer significant advantages over first-generation inhibitors for the treatment of FX and related disorders. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  14. β-Arrestin2 Couples Metabotropic Glutamate Receptor 5 to Neuronal Protein Synthesis and Is a Potential Target to Treat Fragile X

    Directory of Open Access Journals (Sweden)

    Laura J. Stoppel

    2017-03-01

    Full Text Available Synaptic protein synthesis is essential for modification of the brain by experience and is aberrant in several genetically defined disorders, notably fragile X (FX, a heritable cause of autism and intellectual disability. Neural activity directs local protein synthesis via activation of metabotropic glutamate receptor 5 (mGlu5, yet how mGlu5 couples to the intracellular signaling pathways that regulate mRNA translation is poorly understood. Here, we provide evidence that β-arrestin2 mediates mGlu5-stimulated protein synthesis in the hippocampus and show that genetic reduction of β-arrestin2 corrects aberrant synaptic plasticity and cognition in the Fmr1−/y mouse model of FX. Importantly, reducing β-arrestin2 does not induce psychotomimetic activity associated with full mGlu5 inhibitors and does not affect Gq signaling. Thus, in addition to identifying a key requirement for mGlu5-stimulated protein synthesis, these data suggest that β-arrestin2-biased negative modulators of mGlu5 offer significant advantages over first-generation inhibitors for the treatment of FX and related disorders.

  15. Mutation-induced quisqualic acid and ibotenic acid affinity at the metabotropic glutamate receptor subtype 4: ligand selectivity results from a synergy of several amino acid residues

    DEFF Research Database (Denmark)

    Hermit, Mette B; Greenwood, Jeremy R; Bräuner-Osborne, Hans

    2004-01-01

    The metabotropic glutamate receptors (mGluRs) are key modulators of excitatory neurotransmission in the central nervous system. The eight mGluR subtypes are seven trans-membrane-spanning proteins that possess a large extracellular amino-terminal domain in which the endogenous ligand binding pocket...... resides. In this study, we have identified four non-conserved amino acid residues that are essential for differentiating mGluR1 from mGluR4. Our approach has been to increase the affinity of the classic mGluR1 agonists, quisqualic acid and ibotenic acid, at mGluR4 by making various point mutations......, the mutations K74Y and K317R induced dramatic triple-order-of-magnitude increases in the affinity of ibotenic acid at mGluR4, making the affinity equivalent to that of mGluR1. Furthermore, the affinity of quisqualic acid at mGluR4 was increased to the same level as mGluR1 by the two double mutations, K74Y/K317R...

  16. Memantine, an antagonist of the NMDA glutamate receptor, affects cell proliferation, differentiation and the intracellular cycle and induces apoptosis in Trypanosoma cruzi.

    Directory of Open Access Journals (Sweden)

    Flávia Silva Damasceno

    2014-02-01

    Full Text Available Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi and affects approximately 10 million people in endemic areas of Mexico and Central and South America. Currently available chemotherapies are limited to two compounds: Nifurtimox and Benznidazole. Both drugs reduce the symptoms of the disease and mortality among infected individuals when used during the acute phase, but their efficacy during the chronic phase (during which the majority of cases are diagnosed remains controversial. Moreover, these drugs have several side effects. The aim of this study was to evaluate the effect of Memantine, an antagonist of the glutamate receptor in the CNS of mammals, on the life cycle of T. cruzi. Memantine exhibited a trypanocidal effect, inhibiting the proliferation of epimastigotes (IC50 172.6 µM. Furthermore, this compound interfered with metacyclogenesis (approximately 30% reduction and affected the energy metabolism of the parasite. In addition, Memantine triggered mechanisms that led to the apoptosis-like cell death of epimastigotes, with extracellular exposure of phosphatidylserine, increased production of reactive oxygen species, decreased ATP levels, increased intracellular Ca(2+ and morphological changes. Moreover, Memantine interfered with the intracellular cycle of the parasite, specifically the amastigote stage (IC50 31 µM. Interestingly, the stages of the parasite life cycle that require more energy (epimastigote and amastigote were more affected as were the processes of differentiation and cell invasion.

  17. Acquisition and expression of Conditioned Taste Aversion differentially affects Extracellular signal Regulated Kinase and Glutamate receptor phosphorylation in rat Prefrontal Cortex and Nucleus Accumbens

    Directory of Open Access Journals (Sweden)

    Roberto eMarotta

    2014-05-01

    Full Text Available Conditioned taste aversion (CTA can be applied to study associative learning and its relevant underpinning molecular mechanisms in discrete brain regions. The present study examined, by immunohistochemistry and immunocytochemistry, the effects of acquisition and expression of lithium-induced CTA on activated Extracellular signal Regulated Kinase (p-ERK in the prefrontal cortex (PFCx and nucleus accumbens (Acb of male Sprague-Dawley rats. The study also examined, by immunoblotting, whether acquisition and expression of lithium-induced CTA resulted in modified levels of phosphorylation of glutamate receptor subunits (NR1 and GluR1 and Thr34- and Thr75-Dopamine-and-cAMP-Regulated PhosphoProtein (DARPP-32. CTA acquisition was associated with an increase of p-ERK-positive neurons and phosphorylated NR1 receptor subunit (p-NR1 in the PFCx, whereas p-GluR1, p-Thr34- and p-Thr75-DARPP-32 levels were not changed in this brain region. CTA expression increased the number of p-ERK-positive neurons in the shell (AcbSh and core (AcbC but left unmodified p-NR1, p-GluR1, p-Thr34- and p-Thr75-DARPP-32 levels. Furthermore, post-embedding immunogold quantitative analysis in AcbSh revealed that CTA expression significantly increased nuclear p-ERK immunostaining as well as p-ERK-labeled axo-spinous contacts. Overall, these results indicate that ERK and NR1, but not GluR1 and DARPP-32, are differentially phosphorylated as a consequence of acquisition and expression of aversive associative learning. Moreover, these results confirm that CTA represents an useful approach to study the molecular basis of associative learning in rats and suggest the involvement of ERK cascade in learning-associated synaptic plasticity.

  18. Involvement of AMPA/Kainate Glutamate Receptor in the Extinction and Reinstatement of Morphine-Induced Conditioned Place Preference: A Behavioral and Molecular Study.

    Science.gov (United States)

    Siahposht-Khachaki, Ali; Fatahi, Zahra; Yans, Asal; Khodagholi, Fariba; Haghparast, Abbas

    2017-03-01

    Glutamate receptors in mesolimbic areas such as the nucleus accumbens, ventral tegmental area, prefrontal cortex (PFC), and hippocampus (HIP) are a component of the mechanisms of drug-induced reward and can modulate the firing pattern of dopaminergic neurons in the reward system. In addition, several lines of study have indicated that cAMP response element-binding protein (CREB) and c-fos have important role in morphine-induced conditioned place preference (CPP) induced by drugs of abuse, such as morphine, cocaine, nicotine, and alcohol. Therefore, in the present study, we investigated the changes in phosphorylated CREB (p-CREB) and c-fos induction within the nucleus accumbens (NAc), HIP, and PFC after intracerebroventricular (ICV) administration of different doses of CNQX or vehicle during extinction period or reinstatement of morphine-induced CPP. In all groups, the CPP procedure was done; afterward, the conditioning scores were recorded by Ethovision software. After behavioral test recording, we dissected out the NAc, HIP, and PFC regions and measured the p-CREB/CREB ratio and c-fos level by Western blot analysis. Our results showed that administration of CNQX significantly shortened the extinction of morphine CPP. Besides, ICV microinjection of CNQX following extinction period decreased the reinstatement of morphine CPP in extinguished rats. In molecular section, in treatment group, all mentioned factors were dose-dependently decreased in comparison with vehicle group (DMSO) after ICV microinjection of different doses of CNQX but not in pre-extinction microinjection. These findings suggested that antagonism of AMPA receptor decreased p-CREB/CREB ratio and c-fos level in the PFC, NAc, and HIP. Modulation of the drug memory reconsolidation may be useful for faster extinction of drug-induced reward and attenuation of drug-seeking behavior.

  19. Genome-wide gene-environment study identifies glutamate receptor gene GRIN2A as a Parkinson's disease modifier gene via interaction with coffee.

    Science.gov (United States)

    Hamza, Taye H; Chen, Honglei; Hill-Burns, Erin M; Rhodes, Shannon L; Montimurro, Jennifer; Kay, Denise M; Tenesa, Albert; Kusel, Victoria I; Sheehan, Patricia; Eaaswarkhanth, Muthukrishnan; Yearout, Dora; Samii, Ali; Roberts, John W; Agarwal, Pinky; Bordelon, Yvette; Park, Yikyung; Wang, Liyong; Gao, Jianjun; Vance, Jeffery M; Kendler, Kenneth S; Bacanu, Silviu-Alin; Scott, William K; Ritz, Beate; Nutt, John; Factor, Stewart A; Zabetian, Cyrus P; Payami, Haydeh

    2011-08-01

    Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD). We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC), and we performed a genome-wide association and interaction study (GWAIS), testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS) in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication) were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P(2df) = 10(-6), GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10(-7)) but not in light coffee-drinkers. The a priori Replication hypothesis that "Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers" was confirmed: OR(Replication) = 0.59, P(Replication) = 10(-3); OR(Pooled) = 0.51, P(Pooled) = 7×10(-8). Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10(-3)), whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10(-13)). Imputation revealed a block of SNPs that achieved P(2df)coffee-drinkers. This study is proof of concept that inclusion of environmental factors can help identify

  20. Genome-Wide Gene-Environment Study Identifies Glutamate Receptor Gene GRIN2A as a Parkinson's Disease Modifier Gene via Interaction with Coffee

    Science.gov (United States)

    Hamza, Taye H.; Chen, Honglei; Hill-Burns, Erin M.; Rhodes, Shannon L.; Montimurro, Jennifer; Kay, Denise M.; Tenesa, Albert; Kusel, Victoria I.; Sheehan, Patricia; Eaaswarkhanth, Muthukrishnan; Yearout, Dora; Samii, Ali; Roberts, John W.; Agarwal, Pinky; Bordelon, Yvette; Park, Yikyung; Wang, Liyong; Gao, Jianjun; Vance, Jeffery M.; Kendler, Kenneth S.; Bacanu, Silviu-Alin; Scott, William K.; Ritz, Beate; Nutt, John; Factor, Stewart A.; Zabetian, Cyrus P.; Payami, Haydeh

    2011-01-01

    Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD). We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC), and we performed a genome-wide association and interaction study (GWAIS), testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS) in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication) were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P2df = 10−6, GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10−7) but not in light coffee-drinkers. The a priori Replication hypothesis that “Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers” was confirmed: ORReplication = 0.59, PReplication = 10−3; ORPooled = 0.51, PPooled = 7×10−8. Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10−3), whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10−13). Imputation revealed a block of SNPs that achieved P2dfcoffee-drinkers. This study is proof of concept that inclusion of environmental factors can help identify genes that

  1. Genome-wide gene-environment study identifies glutamate receptor gene GRIN2A as a Parkinson's disease modifier gene via interaction with coffee.

    Directory of Open Access Journals (Sweden)

    Taye H Hamza

    2011-08-01

    Full Text Available Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD. We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC, and we performed a genome-wide association and interaction study (GWAIS, testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P(2df = 10(-6, GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10(-7 but not in light coffee-drinkers. The a priori Replication hypothesis that "Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers" was confirmed: OR(Replication = 0.59, P(Replication = 10(-3; OR(Pooled = 0.51, P(Pooled = 7×10(-8. Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10(-3, whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10(-13. Imputation revealed a block of SNPs that achieved P(2df<5×10(-8 in GWAIS, and OR = 0.41, P = 3×10(-8 in heavy coffee-drinkers. This study is proof of

  2. ATP induces NO production in hippocampal neurons by P2X(7 receptor activation independent of glutamate signaling.

    Directory of Open Access Journals (Sweden)

    Juan Francisco Codocedo

    Full Text Available To assess the putative role of adenosine triphosphate (ATP upon nitric oxide (NO production in the hippocampus, we used as a model both rat hippocampal slices and isolated hippocampal neurons in culture, lacking glial cells. In hippocampal slices, additions of exogenous ATP or 2'(3'-O-(4-Benzoylbenzoyl ATP (Bz-ATP elicited concentration-dependent NO production, which increased linearly within the first 15 min and plateaued thereafter; agonist EC50 values were 50 and 15 µM, respectively. The NO increase evoked by ATP was antagonized in a concentration-dependent manner by Coomassie brilliant blue G (BBG or by N(ω-propyl-L-arginine, suggesting the involvement of P2X7Rs and neuronal NOS, respectively. The ATP induced NO production was independent of N-methyl-D-aspartic acid (NMDA receptor activity as effects were not alleviated by DL-2-Amino-5-phosphonopentanoic acid (APV, but antagonized by BBG. In sum, exogenous ATP elicited NO production in hippocampal neurons independently of NMDA receptor activity.

  3. Identification of Three Residues Essential for 5-Hydroxytryptamine 2A-Metabotropic Glutamate 2 (5-HT2A·mGlu2) Receptor Heteromerization and Its Psychoactive Behavioral Function*

    Science.gov (United States)

    Moreno, José L.; Muguruza, Carolina; Umali, Adrienne; Mortillo, Steven; Holloway, Terrell; Pilar-Cuéllar, Fuencisla; Mocci, Giuseppe; Seto, Jeremy; Callado, Luis F.; Neve, Rachael L.; Milligan, Graeme; Sealfon, Stuart C.; López-Giménez, Juan F.; Meana, J. Javier; Benson, Deanna L.; González-Maeso, Javier

    2012-01-01

    Serotonin and glutamate G protein-coupled receptor (GPCR) neurotransmission affects cognition and perception in humans and rodents. GPCRs are capable of forming heteromeric complexes that differentially alter cell signaling, but the role of this structural arrangement in modulating behavior remains unknown. Here, we identified three residues located at the intracellular end of transmembrane domain four that are necessary for the metabotropic glutamate 2 (mGlu2) receptor to be assembled as a GPCR heteromer with the serotonin 5-hydroxytryptamine 2A (5-HT2A) receptor in the mouse frontal cortex. Substitution of these residues (Ala-6774.40, Ala-6814.44, and Ala-6854.48) leads to absence of 5-HT2A·mGlu2 receptor complex formation, an effect that is associated with a decrease in their heteromeric ligand binding interaction. Disruption of heteromeric expression with mGlu2 attenuates the psychosis-like effects induced in mice by hallucinogenic 5-HT2A agonists. Furthermore, the ligand binding interaction between the components of the 5-HT2A·mGlu2 receptor heterocomplex is up-regulated in the frontal cortex of schizophrenic subjects as compared with controls. Together, these findings provide structural evidence for the unique behavioral function of a GPCR heteromer. PMID:23129762

  4. 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-2-carboxylic Acid

    DEFF Research Database (Denmark)

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

    2017-01-01

    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...

  5. How microelectrode array-based chick forebrain neuron biosensors respond to glutamate NMDA receptor antagonist AP5 and GABAA receptor antagonist musimol

    Directory of Open Access Journals (Sweden)

    Serena Y. Kuang

    2016-09-01

    Full Text Available We have established a long-term, stable primary chick forebrain neuron (FBN culture on a microelectrode array platform as a biosensor system for neurotoxicant screening and for neuroelectrophysiological studies for multiple purposes. This paper reports some of our results, which characterize the biosensor pharmacologically. Dose-response experiments were conducted using NMDA receptor antagonist AP5 and GABAA receptor agonist musimol (MUS. The chick FBN biosensor (C-FBN-biosensor responds to the two agents in a pattern similar to that of rodent counterparts; the estimated EC50s (the effective concentration that causes 50% inhibition of the maximal effect are 2.3 μM and 0.25 μM, respectively. Intercultural and intracultural reproducibility and long-term reusability of the C-FBN-biosensor are addressed and discussed. A phenomenon of sensitization of the biosensor that accompanies intracultural reproducibility in paired dose-response experiments for the same agent (AP5 or MUS is reported. The potential application of the C-FBN-biosensor as an alternative to rodent biosensors in shared sensing domains (NMDA receptor and GABAA receptor is suggested. Keywords: Biosensor, Microelectrode array, Neurotoxicity, Chick forebrain neuron, AP5, Musimol

  6. Aldehyde dehydrogenase 2 deficiency increases resting-state glutamate and expression of the GluN1 subunit of N-methyl-D-aspartate receptor in the frontal cortex of mice.

    Science.gov (United States)

    Jamal, Mostofa; Ono, Junichiro; Ameno, Kiyoshi; Shirakami, Gotaro; Tanaka, Naoko; Takakura, Ayaka; Kinoshita, Hiroshi

    2015-01-15

    Our previous study showed that Aldh2-knockout (Aldh2-KO) mice, an animal model of inactive aldehyde dehydrogenase 2 (ALDH2), have better spatial memory when compared with wild-type (WT) mice. Given that the neurotransmitter glutamate has been associated with learning and memory, the goal of the present study was to investigate whether the strain-dependent difference in spatial memory was associated with changes in glutamate transmitter levels or receptor function in the frontal cortex of Aldh2-KO and WT mice. Thus, we first measured extracellular glutamate levels in free-moving mice using microdialysis. Second, we studied protein expression of the N-methyl-D-aspartate (NMDA) receptor (GluN1) subunit and the α-amino-3-hydroxy-5 methylisoxazole-4-propionic acid (AMPA) receptor (GluA1) subunit in lipid raft fractions using Western blot (WB). The samples were collected for WB, and lipid rafts were prepared from the insoluble fraction of homogenate tissue. Protein concentration was measured in the whole cell lysate (WCL) and in five separate lipid raft fractions. Cholesterol was also measured in all fractions 1-5. The microdialysis study revealed that basal glutamate concentration in the dialysates was approximately three-fold (0.27 ± 0.12 μM) higher in Aldh2-KO mice than in WT (0.10 ± 0.03 μM) mice. We also found an increase in the expression of GluN1 in Aldh2-KO mice compared with WT mice, both in the WCL and fraction 5, but GluA1 levels were unchanged as measured by WB. Our novel findings provide the first evidence for the role of ALDH2 in glutamate release and GluN1 protein expression in the frontal cortex. The observed strain differences in glutamate levels and GluN1 expression may suggest that enhanced glutamatergic function facilitates improved spatial memory in Aldh2-KO mice and such observation deserves further investigation. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. 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

  8. Methoxyphenylethynyl, methoxypyridylethynyl and phenylethynyl derivatives of pyridine: synthesis, radiolabeling and evaluation of new PET ligands for metabotropic glutamate subtype 5 receptors

    Energy Technology Data Exchange (ETDEWEB)

    Yu Meixiang [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States)]. E-mail: myu@utmck.edu; Tueckmantel, Werner [Acenta Discovery Inc., Tucson, AZ 85747 (United States); Wang, Xukui [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States); Zhu Aijun [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States); Kozikowski, Alan P. [Acenta Discovery Inc., Tucson, AZ 85747 (United States); [Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60612 (United States); Brownell, Anna-Liisa [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States)]. E-mail: abrownell@partners.org

    2005-08-01

    We have synthesized three different PET ligands to investigate the physiological function of metabotropic glutamate subtype 5 receptors (mGluR5) in vivo: 2-[{sup 11}C]methyl-6-(2-phenylethynyl)pyridine ([{sup 11}C]MPEP), 2-(2-(3-[{sup 11}C]methoxyphenyl)ethynyl)pyridine ([{sup 11}C]M-MPEP) and 2-(2-(5-[{sup 11}C]methoxypyridin-3-yl)ethynyl)pyridine ([{sup 11}C]M-PEPy). [{sup 11}C]Methyl iodide was used to label the compounds under basic conditions, and a Pd(0) catalyst was applied to label [{sup 11}C]MPEP in a Stille coupling reaction. In vivo microPET imaging studies of the functional accumulation of radiolabeled ligands were conducted in 35 rats (Sprague-Dawley, 8 weeks old male, weight of 300 g). Specific binding was tested using pre-administration of unlabeled mGluR5 antagonist 2-methyl-6-(2-phenylethynyl)pyridine (MPEP) (10 mg/kg iv 5 min before radioactivity injection). In the radiolabeling of [{sup 11}C]MPEP, [{sup 11}C]M-MPEP and [{sup 11}C]M-PEPy, a specific radioactivity of 700-1200 mCi/{mu}mol and over 97% radiochemical purity were obtained. The microPET studies showed these three radiolabeled mGluR5 antagonists having the highest binding in the olfactory bulb followed by striatum, hippocampus and cortex. Pre-administration of the mGluR5 antagonist MPEP induced a 45.1% decrease in [{sup 11}C]MPEP binding, a 59.7% decrease in [{sup 11}C]M-MPEP binding and an 84.6% decrease in [{sup 11}C]M-PEPy binding in the olfactory bulb at 5 min. The feasibility of synthesizing high-affinity and high-selectivity ligands for mGluR5 receptors and their suitability as PET imaging ligands for mGluR5 receptors in vivo are demonstrated.

  9. Evaluation in vitro and in animals of a new {sup 11}C-labeled PET radioligand for metabotropic glutamate receptors 1 in brain

    Energy Technology Data Exchange (ETDEWEB)

    Zanotti-Fregonara, Paolo; Liow, Jeih-San; Zoghbi, Sami S.; Clark, David T.; Morse, Cheryl; Pike, Victor W. [National Institute of Mental Health, National Institutes of Health, Molecular Imaging Branch, Bethesda, MD (United States); Barth, Vanessa N.; Rhoads, Emily; Siuda, Edward; Heinz, Beverly A.; Nisenbaum, Eric; Dressman, Bruce; Joshi, Elizabeth; Luffer-Atlas, Debra; Fisher, Matthew J.; Masters, John J.; Goebl, Nancy; Kuklish, Steven L.; Tauscher, Johannes [Eli Lilly and Co., Indianapolis, IN (United States); Innis, Robert B. [National Institute of Mental Health, National Institutes of Health, Molecular Imaging Branch, Bethesda, MD (United States); National Institute of Mental Health, Molecular Imaging Branch, Bethesda, MD (United States)

    2013-02-15

    Two allosteric modulators of the group I metabotropic glutamate receptors (mGluR1 and mGluR5) were evaluated as positron emission tomography (PET) radioligands for mGluR1. LY2428703, a full mGluR1 antagonist (IC{sub 50} 8.9 nM) and partial mGluR5 antagonist (IC{sub 50} 118 nM), and LSN2606428, a full mGluR1 and mGluR5 antagonist (IC{sub 50} 35.3 nM and 10.2 nM, respectively) were successfully labeled with {sup 11}C and evaluated as radioligands for mGluR1. The pharmacology of LY2428703 was comprehensively assessed in vitro and in vivo, and its biodistribution was investigated by liquid chromatography-mass spectrometry/mass spectrometry, and by PET imaging in the rat. In contrast, LSN2606428 was only evaluated in vitro; further evaluation was stopped due to its unfavorable pharmacological properties and binding affinity. {sup 11}C-LY2428703 showed promising characteristics, including: (1) high potency for binding to human mGluR1 (IC{sub 50} 8.9 nM) with no significant affinity for other human mGlu receptors (mGluR2 through mGluR8); (2) binding to brain displaceable by administration of an mGluR1 antagonist; (3) only one major radiometabolite in both plasma and brain, with a negligible brain concentration (with 3.5 % of the total radioactivity in cerebellum) and no receptor affinity; (4) a large specific and displaceable signal in the mGluR1-rich cerebellum with no significant in vivo affinity for mGluR5, as shown by PET studies in rats; and (5) lack of substrate behavior for efflux transporters at the blood-brain barrier, as shown by PET studies conducted in wild-type and knockout mice. {sup 11}C-LY2428703, a new PET radioligand for mGluR1 quantification, displayed promising characteristics both in vitro and in vivo in rodents. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, M. [Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (United States); Bizon, J.L. [Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, NC (United States); Nicolle, M.M. [Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (United States)

    1996-08-02

    Using in vitro autoradiography, we investigated [{sup 3}H]{alpha}-amino-3-hydroxy-5-methyl-4-isoxazolepropionate, [{sup 3}H]kainate and [{sup 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, [{sup 3}H]{alpha}-amino-3-hydroxy-5-methyl-4-isoxazolepropionate binding in CA1 and [{sup 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 [{sup 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, [{sup 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 [{sup 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

  11. Detection of a gravitropism phenotype in glutamate receptor-like 3.3 mutants of Arabidopsis thaliana using machine vision and computation.

    Science.gov (United States)

    Miller, Nathan D; Durham Brooks, Tessa L; Assadi, Amir H; Spalding, Edgar P

    2010-10-01

    Gene disruption frequently produces no phenotype in the model plant Arabidopsis thaliana, complicating studies of gene function. Functional redundancy between gene family members is one common explanation but inadequate detection methods could also be responsible. Here, newly developed methods for automated capture and processing of time series of images, followed by computational analysis employing modified linear discriminant analysis (LDA) and wavelet-based differentiation, were employed in a study of mutants lacking the Glutamate Receptor-Like 3.3 gene. Root gravitropism was selected as the process to study with high spatiotemporal resolution because the ligand-gated Ca(2+)-permeable channel encoded by GLR3.3 may contribute to the ion fluxes associated with gravity signal transduction in roots. Time series of root tip angles were collected from wild type and two different glr3.3 mutants across a grid of seed-size and seedling-age conditions previously found to be important to gravitropism. Statistical tests of average responses detected no significant difference between populations, but LDA separated both mutant alleles from the wild type. After projecting the data onto LDA solution vectors, glr3.3 mutants displayed greater population variance than the wild type in all four conditions. In three conditions the projection means also differed significantly between mutant and wild type. Wavelet analysis of the raw response curves showed that the LDA-detected phenotypes related to an early deceleration and subsequent slower-bending phase in glr3.3 mutants. These statistically significant, heritable, computation-based phenotypes generated insight into functions of GLR3.3 in gravitropism. The methods could be generally applicable to the study of phenotypes and therefore gene function.

  12. The Role of Aldehyde Oxidase and Xanthine Oxidase in the Biotransformation of a Novel Negative Allosteric Modulator of Metabotropic Glutamate Receptor Subtype 5

    Science.gov (United States)

    Morrison, Ryan D.; Blobaum, Anna L.; Byers, Frank W.; Santomango, Tammy S.; Bridges, Thomas M.; Stec, Donald; Brewer, Katrina A.; Sanchez-Ponce, Raymundo; Corlew, Melany M.; Rush, Roger; Felts, Andrew S.; Manka, Jason; Bates, Brittney S.; Venable, Daryl F.; Rodriguez, Alice L.; Jones, Carrie K.; Niswender, Colleen M.; Conn, P. Jeffrey; Lindsley, Craig W.; Emmitte, Kyle A.

    2012-01-01

    Negative allosteric modulation (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5) represents a therapeutic strategy for the treatment of childhood developmental disorders, such as fragile X syndrome and autism. VU0409106 emerged as a lead compound within a biaryl ether series, displaying potent and selective inhibition of mGlu5. Despite its high clearance and short half-life, VU0409106 demonstrated efficacy in rodent models of anxiety after extravascular administration. However, lack of a consistent correlation in rat between in vitro hepatic clearance and in vivo plasma clearance for the biaryl ether series prompted an investigation into the biotransformation of VU0409106 using hepatic subcellular fractions. An in vitro appraisal in rat, monkey, and human liver S9 fractions indicated that the principal pathway was NADPH-independent oxidation to metabolite M1 (+16 Da). Both raloxifene (aldehyde oxidase inhibitor) and allopurinol (xanthine oxidase inhibitor) attenuated the formation of M1, thus implicating the contribution of both molybdenum hydroxylases in the biotransformation of VU0409106. The use of 18O-labeled water in the S9 experiments confirmed the hydroxylase mechanism proposed, because 18O was incorporated into M1 (+18 Da) as well as in a secondary metabolite (M2; +36 Da), the formation of which was exclusively xanthine oxidase-mediated. This unusual dual and sequential hydroxylase metabolism was confirmed in liver S9 and hepatocytes of multiple species and correlated with in vivo data because M1 and M2 were the principal metabolites detected in rats administered VU0409106. An in vitro-in vivo correlation of predicted hepatic and plasma clearance was subsequently established for VU0409106 in rats and nonhuman primates. PMID:22711749

  13. Oxytocin receptors are expressed on dopamine and glutamate neurons in the mouse ventral tegmental area that project to nucleus accumbens and other mesolimbic targets.

    Science.gov (United States)

    Peris, Joanna; MacFadyen, Kaley; Smith, Justin A; de Kloet, Annette D; Wang, Lei; Krause, Eric G

    2017-04-01

    The mesolimbic dopamine (DA) circuitry determines which behaviors are positively reinforcing and therefore should be encoded in the memory to become a part of the behavioral repertoire. Natural reinforcers, like food and sex, activate this pathway, thereby increasing the likelihood of further consummatory, social, and sexual behaviors. Oxytocin (OT) has been implicated in mediating natural reward and OT-synthesizing neurons project to the ventral tegmental area (VTA) and nucleus accumbens (NAc); however, direct neuroanatomical evidence of OT regulation of DA neurons within the VTA is sparse. To phenotype OT-receptor (OTR) expressing neurons originating within the VTA, we delivered Cre-inducible adeno-associated virus that drives the expression of fluorescent marker into the VTA of male mice that had Cre-recombinase driven by OTR gene expression. OTR-expressing VTA neurons project to NAc, prefrontal cortex, the extended amygdala, and other forebrain regions but less than 10% of these OTR-expressing neurons were identified as DA neurons (defined by tyrosine hydroxylase colocalization). Instead, almost 50% of OTR-expressing cells in the VTA were glutamate (GLU) neurons, as indicated by expression of mRNA for the vesicular GLU transporter (vGluT). About one-third of OTR-expressing VTA neurons did not colocalize with either DA or GLU phenotypic markers. Thus, OTR expression by VTA neurons implicates that OT regulation of reward circuitry is more complex than a direct action on DA neurotransmission. J. Comp. Neurol. 525:1094-1108, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  14. The endocrine disrupting potential of monosodium glutamate (MSG) on secretion of the glucagon-like peptide-1 (GLP-1) gut hormone and GLP-1 receptor interaction.

    Science.gov (United States)

    Shannon, Maeve; Green, Brian; Willars, Gary; Wilson, Jodie; Matthews, Natalie; Lamb, Joanna; Gillespie, Anna; Connolly, Lisa

    2017-01-04

    Monosodium glutamate (MSG) is a suspected obesogen with epidemiological evidence positively correlating consumption to increased body mass index and higher prevalence of metabolic syndrome. ELISA and high content analysis (HCA) were employed to examine the disruptive effects of MSG on the secretion of enteroendocrine hormone glucagon-like peptide-1 (GLP-1) and GLP-1 receptor (GLP-1R), respectively. Following 3h MSG exposure of the enteroendocrine pGIP/neo: STC-1 cell line model (500μg/ml) significantly increased GLP-1 secretion (1.8 fold; P≤0.001), however, 72h exposure (500μg/ml) caused a 1.8 fold decline (P≤0.05). Also, 3h MSG exposure (0.5-500μg/ml) did not induce any cytotoxicity (including multiple pre-lethal markers) but 72h exposure at 250-500μg/ml, decreased cell number (11.8-26.7%; P≤0.05), increased nuclear area (23.9-29.8%; P≤0.001) and decreased mitochondrial membrane potential (13-21.6%; P≤0.05). At 500μg/ml, MSG increased mitochondrial mass by 16.3% (P≤0.01). MSG did not agonise or antagonise internalisation of the GLP-1R expressed recombinantly in U2OS cells, following GLP-1 stimulation. In conclusion, 72h exposure of an enteroendocrine cell line at dietary levels of MSG, results in pre-lethal cytotoxicity and decline in GLP-1 secretion. These adverse events may play a role in the pathogenesis of obesity as outlined in the obesogen hypothesis by impairing GLP-1 secretion, related satiety responses and glucose-stimulated insulin release. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Peripheral CB1 Receptor Neutral Antagonist, AM6545, Ameliorates Hypometabolic Obesity and Improves Adipokine Secretion in Monosodium Glutamate Induced Obese Mice

    Directory of Open Access Journals (Sweden)

    Haiming Ma

    2018-03-01

    Full Text Available Effect of peripheral cannabinoid receptor 1 (CB1R blockade by AM6545 in the monosodium glutamate (MSG-induced hypometabolic and hypothalamic obesity was observed, and the impact on intraperitoneal adipose tissue and adipokines was investigated. The MSG mice is characterized by excessive abdominal obesity, and combined with dyslipidemia and insulin resistance. 3-Week AM6545 treatment dose-dependently decreased the body weight, intraperitoneal fat mass, and rectified the accompanied dyslipidemia include elevated serum triglyceride, total cholesterol, free fatty acids, and lowered LDLc level. Glucose intolerance and hyperinsulinemia were also alleviated. But AM6545 didn’t affect the food-intake consistently through the experiment. In line with the reduction on fat mass, the size of adipocyte was reduced markedly. Most interestingly, AM6545 showed significant improvement on levels of circulating adipokines including lowering leptin, asprosin and TNFα, and increasing HMW adiponectin. Correspondingly, dysregulated gene expression of lipogenesis, lipolysis, and adipokines in the adipose tissue were nearly recovered to normal level after AM6545 treatment. Additionally, western blot analysis revealed that AM6545 corrected the elevated CB1R and PPARγ protein expression, while increased the key energy uncoupling protein UCP1 expression in adipose tissue. Taken together, the current study indicates that AM6545 induced a comprehensive metabolic improvement in the MSG mice including counteracting the hypometabolic and hypothalamic obesity, and improving the accompanied dyslipidemia and insulin resistance. One key underlying mechanism is related to ameliorate on the metabolic deregulation of adipose tissue, the synthesis and secretion of adipokines were thus rectified, and finally the catabolism was increased and the anabolism was reduced in intraperitoneal adipose tissue. Findings from this study will provide the valuable information about peripheral CB1R

  16. Glutamate-induced sensitization of rat masseter muscle fibers.

    NARCIS (Netherlands)

    Cairns, B.E.; Gambarota, G.; Svensson, P.; Arendt-Nielsen, L.; Berde, C.B.

    2002-01-01

    In rats, intradermal or intraarticular injection of glutamate or selective excitatory amino acid receptor agonists acting at peripheral excitatory amino acid receptors can decrease the intensity of mechanical stimulation required to evoke nocifensive behaviors, an indication of hyperalgesia. Since

  17. A novel assay of Gi/o-linked G protein-coupled receptor coupling to potassium channels provides new insights into the pharmacology of the group III metabotropic glutamate receptors.

    Science.gov (United States)

    Niswender, Colleen M; Johnson, Kari A; Luo, Qingwei; Ayala, Jennifer E; Kim, Caroline; Conn, P Jeffrey; Weaver, C David

    2008-04-01

    The group III metabotropic glutamate receptors (mGluRs) represent a family of presynaptically expressed G-protein-coupled receptors (GPCRs) with enormous therapeutic potential; however, robust cellular assays to study their function have been difficult to develop. We present here a new assay, compatible with traditional high-throughput screening platforms, to detect activity of pharmacological ligands interacting with G(i/o)-coupled GPCRs, including the group III mGluRs 4, 7, and 8. The assay takes advantage of the ability of the Gbetagamma subunits of G(i) and G(o) heterotrimers to interact with G-protein regulated inwardly rectifying potassium channels (GIRKs), and we show here that we are able to detect the activity of multiple types of pharmacophores including agonists, antagonists, and allosteric modulators of several distinct GPCRs. Using GIRK-mediated thallium flux, we perform a side-by-side comparison of the activity of a number of commercially available compounds, some of which have not been extensively evaluated because of the previous lack of robust assays at each of the three major group III mGluRs. It is noteworthy that several compounds previously considered to be general group III mGluR antagonists have very weak activity using this assay, suggesting the possibility that these compounds may not effectively inhibit these receptors in native systems. We anticipate that the GIRK-mediated thallium flux strategy will provide a novel tool to advance the study of G(i/o)-coupled GPCR biology and promote ligand discovery and characterization.

  18. Experimental Malaria in Pregnancy Induces Neurocognitive Injury in Uninfected Offspring via a C5a-C5a Receptor Dependent Pathway.

    Directory of Open Access Journals (Sweden)

    Chloë R McDonald

    2015-09-01

    Full Text Available The in utero environment profoundly impacts childhood neurodevelopment and behaviour. A substantial proportion of pregnancies in Africa are at risk of malaria in pregnancy (MIP however the impact of in utero exposure to MIP on fetal neurodevelopment is unknown. Complement activation, in particular C5a, may contribute to neuropathology and adverse outcomes during MIP. We used an experimental model of MIP and standardized neurocognitive testing, MRI, micro-CT and HPLC analysis of neurotransmitter levels, to test the hypothesis that in utero exposure to malaria alters neurodevelopment through a C5a-C5aR dependent pathway. We show that malaria-exposed offspring have persistent neurocognitive deficits in memory and affective-like behaviour compared to unexposed controls. These deficits were associated with reduced regional brain levels of major biogenic amines and BDNF that were rescued by disruption of C5a-C5aR signaling using genetic and functional approaches. Our results demonstrate that experimental MIP induces neurocognitive deficits in offspring and suggest novel targets for intervention.

  19. Nectin-4 co-stimulates the prolactin receptor by interacting with SOCS1 and inhibiting its activity on the JAK2-STAT5a signaling pathway.

    Science.gov (United States)

    Maruoka, Masahiro; Kedashiro, Shin; Ueda, Yuki; Mizutani, Kiyohito; Takai, Yoshimi

    2017-04-28

    Cell-surface cytokine receptors are regulated by their cis -interacting stimulatory and inhibitory co-receptors. We previously showed that the Ig-like cell-adhesion molecule nectin-4 cis -interacts with the prolactin receptor through the extracellular region and stimulates prolactin-induced prolactin receptor activation and signaling, resulting in alveolar development in the mouse mammary gland. However, it remains unknown how this interaction stimulates these effects. We show here that the cis -interaction of the extracellular region of nectin-4 with the prolactin receptor was not sufficient for eliciting these effects and that the cytoplasmic region of nectin-4 was also required for this interaction. The cytoplasmic region of nectin-4 directly interacted with suppressor of cytokine signaling 1 (SOCS1), but not SOCS3, JAK2, or STAT5a, and inhibited the interaction of SOCS1 with JAK2, eventually resulting in the increased phosphorylation of STAT5a. The juxtamembrane region of nectin-4 interacted with the Src homology 2 domain of SOCS1. Both the interaction of nectin-4 with the extracellular region of the prolactin receptor and the interaction of SOCS1 with the cytoplasmic region of nectin-4 were required for the stimulatory effect of nectin-4 on the prolactin-induced prolactin receptor activation. The third Ig-like domain of nectin-4 and the second fibronectin type III domain of the prolactin receptor were involved in this cis -interaction, and both the extracellular and transmembrane regions of nectin-4 and the prolactin receptor were required for this direct interaction. These results indicate that nectin-4 serves as a stimulatory co-receptor for the prolactin receptor by regulating the feedback inhibition of SOCS1 in the JAK2-STAT5a signaling pathway. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Preclinical and the first clinical studies on [11C]ITMM for mapping metabotropic glutamate receptor subtype 1 by positron emission tomography

    International Nuclear Information System (INIS)

    Toyohara, Jun; Sakata, Muneyuki; Fujinaga, Masayuki; Yamasaki, Tomoteru; Oda, Keiichi; Ishii, Kenji; Zhang, Ming Rong; Moriguchi Jeckel, Cristina Maria; Ishiwata, Kiichi

    2013-01-01

    Introduction: Preclinical studies and first positron emission tomography (PET) imaging studies were performed using N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-4-[ 11 C] methoxy-N-methylbenzamide ([ 11 C]ITMM) to map metabotropic glutamate receptor type 1 (mGluR1) in the human brain. Methods: [ 11 C]ITMM was synthesized by O-methylation of the desmethyl precursor with [ 11 C]methyl triflate in the presence of NaOH at room temperature. In vitro selectivity and brain distributions of [ 11 C]ITMM in mice were characterized. Radiation absorbed-dose by [ 11 C]ITMM in humans was calculated from mouse distribution data. Acute toxicity of ITMM at 4.72 mg/kg body weight (> 74,000-fold clinical equivalent dose of [ 11 C]ITMM) was evaluated. Mutagenicity of ITMM was studied by the Ames test. Clinical PET imaging of mGluR1 with [ 11 C] ITMM was performed in a healthy volunteer. Results: ITMM had low activity for a 28-standard receptor binding profile. Regional brain uptake of [ 11 C]ITMM in mice was heterogeneous and consistent with known mGluR1 distributions. The radiation absorbed-dose by [ 11 C]ITMM in humans was sufficiently low for clinical use, and no acute toxicity or mutagenicity of ITMM occurred. A 90-min dynamic PET scan with [ 11 C]ITMM in a healthy volunteer showed a gradual increase of radioactivity in the cerebellum. Total distribution volume of [ 11 C]ITMM was highest in the cerebellum, followed by thalamus, cerebral cortex, and striatum; regional differences in brain radioactivity corresponded to the mGluR1 distribution in the brain. Peripherally, [ 11 C]ITMM was stable in humans: 60% of the plasma radioactivity remained in the unchanged form for 60 min. Conclusions: [ 11 C] ITMM is a suitable radioligand for imaging mGluR1 in the human brain providing acceptable dosimetry and pharmacological safety at the dose required for PET

  1. Anti-Cancer Effect of Metabotropic Glutamate Receptor 1 Inhibition in Human Glioma U87 Cells: Involvement of PI3K/Akt/mTOR Pathway

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    2015-01-01

    Full Text Available Background: Metabotropic glutamate receptors (mGluRs are G-protein-coupled receptors that mediate neuronal excitability and synaptic plasticity in the central nervous system, and emerging evidence suggests a role of mGluRs in the biology of cancer. Previous studies showed that mGluR1 was a potential therapeutic target for the treatment of breast cancer and melanoma, but its role in human glioma has not been determined. Methods: In the present study, we investigated the effects of mGluR1 inhibition in human glioma U87 cells using specific targeted small interfering RNA (siRNA or selective antagonists Riluzole and BAY36-7620. The anti-cancer effects of mGluR1 inhibition were measured by cell viability, lactate dehydrogenase (LDH release, TUNEL staining, cell cycle assay, cell invasion and migration assays in vitro, and also examined in a U87 xenograft model in vivo. Results: Inhibition of mGluR1 significantly decreased the cell viability but increased the LDH release in a dose-dependent fashion in U87 cells. These effects were accompanied with the induction of caspase-dependent apoptosis and G0/G1 cell cycle arrest. In addition, the results of Matrigel invasion and cell tracking assays showed that inhibition of mGluR1 apparently attenuated cell invasion and migration in U87 cells. All these anti-cancer effects were ablated by the mGluR1 agonist L-quisqualic acid. The results of western blot analysis showed that mGluR1 inhibition overtly decreased the phosphorylation of PI3K, Akt, mTOR and P70S6K, indicating the mitigated activation of PI3K/Akt/mTOR pathway. Moreover, the anti-tumor activity of mGluR1 inhibition in vivo was also demonstrated in a U87 xenograft glioma model in athymic nude mice. Conclusion: The remarkable efficiency of mGluR1 inhibition to induce cell death in U87 cells may find therapeutic application for the treatment of glioma patients.

  2. AMN082, a metabotropic glutamate receptor 7 allosteric agonist, attenuates locomotor sensitization and cross-sensitization induced by cocaine and morphine in mice.

    Science.gov (United States)

    Jenda, M; Gawel, K; Marszalek, M; Komsta, L; Kotlinska, J H

    2015-03-03

    Previous studies have indicated that metabotropic glutamate receptors 7 (mGluR7s) are involved in drug addiction. However, the role of these receptors in drug-induced behavioral sensitization is unknown. The aim of the present study was to determine whether systemic injection of AMN082, a selective mGluR7 allosteric agonist, reduces the cocaine- and morphine-induced hyperactivity and the development and expression of locomotor sensitization, and also affects the reciprocal cross-sensitization to the stimulant effect of cocaine and morphine in mice. AMN082 (1.25-10.0 mg/kg, i.p.) did not have an impact on locomotion of naive mice and did not affect the acute cocaine- or morphine-induced hyperactivity, except the dose of 10 mg/kg that suppressed the locomotor effect of both drugs. Repeated exposure to cocaine or morphine (10 mg/kg, 5× every 3 days) gradually increased locomotion during induction of sensitization and after 4 (cocaine) or 7 day (morphine) withdrawal phase when challenged with cocaine (10 mg/kg, i.p.) or morphine (10 mg/kg, i.p.) on day 17 or 20, respectively. Pretreatment of animals with the lower doses of AMN082 (1.25-5.0 mg/kg, i.p.), 30 min before every cocaine or morphine injection during repeated drug administration or before cocaine or morphine challenge, dose-dependently attenuated the development, as well as the expression of cocaine or morphine locomotor sensitization. AMN082 also inhibited the reciprocal cross-sensitization between these drugs. Prior to administration of MMPIP (10 mg/kg, i.p.), a selective mGluR7 antagonist reversed the inhibitory effect of AMN082 on the development or expression of cocaine or morphine sensitization. These data indicate that AMN082 attenuated the development and expression of cocaine and morphine sensitization, and the reciprocal cross-sensitization via a mechanism that involves mGluR7s. Thus, AMN082 might have therapeutic implications not only in the treatment of cocaine or opioid addiction but also in the

  3. [Glutamate signaling and neural plasticity].

    Science.gov (United States)

    Watanabe, Masahiko

    2013-07-01

    Proper functioning of the nervous system relies on the precise formation of neural circuits during development. At birth, neurons have redundant synaptic connections not only to their proper targets but also to other neighboring cells. Then, functional neural circuits are formed during early postnatal development by the selective strengthening of necessary synapses and weakening of surplus connections. Synaptic connections are also modified so that projection fields of active afferents expand at the expense of lesser ones. We have studied the molecular mechanisms underlying these activity-dependent prunings and the plasticity of synaptic circuitry using gene-engineered mice defective in the glutamatergic signaling system. NMDA-type glutamate receptors are critically involved in the establishment of the somatosensory pathway ascending from the brainstem trigeminal nucleus to the somatosensory cortex. Without NMDA receptors, whisker-related patterning fails to develop, whereas lesion-induced plasticity occurs normally during the critical period. In contrast, mice lacking the glutamate transporters GLAST or GLT1 are selectively impaired in the lesion-induced critical plasticity of cortical barrels, although whisker-related patterning itself develops normally. In the developing cerebellum, multiple climbing fibers initially innervating given Purkinje cells are eliminated one by one until mono-innervation is achieved. In this pruning process, P/Q-type Ca2+ channels expressed on Purkinje cells are critically involved by the selective strengthening of single main climbing fibers against other lesser afferents. Therefore, the activation of glutamate receptors that leads to an activity-dependent increase in the intracellular Ca2+ concentration plays a key role in the pruning of immature synaptic circuits into functional circuits. On the other hand, glutamate transporters appear to control activity-dependent plasticity among afferent fields, presumably through adjusting

  4. Astrocyte-neuron interaction in the substantia gelatinosa of the spinal cord dorsal horn via P2X7 receptor-mediated release of glutamate and reactive oxygen species.

    Science.gov (United States)

    Ficker, Christoph; Rozmer, Katalin; Kató, Erzsébet; Andó, Rómeó D; Schumann, Luisa; Krügel, Ute; Franke, Heike; Sperlágh, Beáta; Riedel, Thomas; Illes, Peter

    2014-10-01

    The substantia gelatinosa (SG) of the spinal cord processes incoming painful information to ascending projection neurons. Whole-cell patch clamp recordings from SG spinal cord slices documented that in a low Ca(2+) /no Mg(2+) (low X(2+) ) external medium adenosine triphosphate (ATP)/dibenzoyl-ATP, Bz-ATP) caused inward current responses, much larger in amplitude than those recorded in a normal X(2+) -containing bath medium. The effect of Bz-ATP was antagonized by the selective P2X7 receptor antagonist A-438079. Neuronal, but not astrocytic Bz-ATP currents were strongly inhibited by a combination of the ionotropic glutamate receptor antagonists AP-5 and CNQX. In fact, all neurons and some astrocytes responded to NMDA, AMPA, and muscimol with inward current, demonstrating the presence of the respective receptors. The reactive oxygen species H2 O2 potentiated the effect of Bz-ATP at neurons but not at astrocytes. Hippocampal CA1 neurons exhibited a behavior similar to, but not identical with SG neurons. Although a combination of AP-5 and CNQX almost abolished the effect of Bz-ATP, H2 O2 was inactive. A Bz-ATP-dependent and A-438079-antagonizable reactive oxygen species production in SG slices was proven by a microelectrode biosensor. Immunohistochemical investigations showed the colocalization of P2X7-immunoreactivity with microglial (Iba1), but not astrocytic (GFAP, S100β) or neuronal (MAP2) markers in the SG. It is concluded that SG astrocytes possess P2X7 receptors; their activation leads to the release of glutamate, which via NMDA- and AMPA receptor stimulation induces cationic current in the neighboring neurons. P2X7 receptors have a very low density under resting conditions but become functionally upregulated under pathological conditions. © 2014 Wiley Periodicals, Inc.

  5. An Examination of the Role of L-Glutamate and Inosine 5'-Monophosphate in Hedonic Taste-Guided Behavior by Mice Lacking the T1R1 + T1R3 Receptor.

    Science.gov (United States)

    Blonde, Ginger D; Spector, Alan C

    2017-06-01

    The heterodimeric T1R1 + T1R3 receptor is considered critical for normal signaling of L-glutamate and 5'-ribonucleotides in the oral cavity. However, some taste-guided responsiveness remains in mice lacking one subunit of the receptor, suggesting that other receptors are sufficient to support some behaviors. Here, mice lacking both receptor subunits (KO) and wild-type (WT, both n = 13) mice were tested in a battery of behavioral tests. Mice were trained and tested in gustometers with a concentration series of Maltrin-580, a maltodextrin, in a brief-access test (10-s trials) as a positive control. Similar tests followed with monosodium glutamate (MSG) with and without the ribonucleotide inosine 5'-monophosphate (IMP), but always in the presence of the epithelial sodium channel blocker amiloride (A). Brief-access tests were repeated following short-term (30-min) and long-term (48-h) exposures to MSG + A + IMP and were also conducted with sodium gluconate replacing MSG. Finally, progressive ratio tests were conducted with Maltrin-580 or MSG + A + IMP, to assess appetitive behavior while minimizing satiation. Overall, MSG generated little concentration-dependent responding in either food-restricted WT or KO mice, even in combination with IMP. However, KO mice licked less to the amino acid stimuli, a measure of consummatory behavior in the brief-access tests. In contrast, both groups initiated a similar number of trials and had a similar breakpoint in the progressive ratio task, both measures of appetitive (approach) behavior. Collectively, these results suggest that while the T1R1 + T1R3 receptor is necessary for consummatory responding to MSG (+IMP), other receptors are sufficient to maintain appetitive responding to this "umami" stimulus complex in food-restricted mice. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. A Novel Role for the Receptor of the Complement Cleavage Fragment C5a, C5aR1, in CCR5-Mediated Entry of HIV into Macrophages.

    Science.gov (United States)

    Moreno-Fernandez, Maria E; Aliberti, Julio; Groeneweg, Sander; Köhl, Jörg; Chougnet, Claire A

    2016-04-01

    The complement system is an ancient pattern recognition system that becomes activated during all stages of HIV infection. Previous studies have shown that C5a can enhance the infection of monocyte-derived macrophages and T cells indirectly through the production of interleukin (IL)-6 and tumor necrosis factor (TNF)-α and the attraction of dendritic cells. C5a exerts its multiple biologic functions mainly through activation of C5a receptor 1 (C5aR1). Here, we assessed the role of C5aR1 as an enhancer of CCR5-mediated HIV infection. We determined CCR5 and C5aR1 heterodimer formation in myeloid cells and the impact of C5aR1 blockade on HIV entry and genomic integration. C5aR1/CCR5 heterodimer formation was identified by immunoprecipitation and western blotting. THP-1 cells and monocyte-derived macrophages (MDM) were infected by R5 laboratory strains or HIV pseudotyped for the vesicular stomatitis virus (VSV) envelope. Levels of integrated HIV were measured by quantitative PCR after targeting of C5aR1 by a C5aR antagonist, neutralizing C5aR1 monoclonal antibody (mAb) or hC5a. C5aR1 was also silenced by specific siRNA prior to viral entry. We found that C5aR1 forms heterodimers with the HIV coreceptor CCR5 in myeloid cells. Targeting C5aR1 significantly decreased integration by R5 viruses but not by VSV-pseudotyped viruses, suggesting that C5aR1 is critical for viral entry. The level of inhibition achieved with C5aR1-blocking reagents was comparable to that of CCR5 antagonists. Mechanistically, C5aR1 targeting decreased CCR5 expression. MDM from CCR5Δ32 homozygous subjects expressed levels of C5aR1 similar to CCR5 WT individuals, suggesting that mere C5aR1 expression is not sufficient for HIV infection. HIV appeared to preferentially enter THP-1 cells expressing high levels of both C5aR1 and CCR5. Targeted reduction of C5aR1 expression in such cells reduced HIV infection by ~50%. Our data thus suggest that C5aR1 acts as an enhancer of CCR5-mediated HIV entry into

  7. Long-term, repeated dose in vitro neurotoxicity of the glutamate receptor antagonist L-AP3, demonstrated in rat hippocampal slice cultures by using continuous propidium iodide incubation

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Blaabjerg, Morten; Noraberg, Jens

    2007-01-01

    Most in vitro models are only used to assess short-term effects of test compounds. However, as demonstrated here, hippocampal slice cultures can be used for long-term studies. The test compound used was the metabotropic glutamate receptor antagonist, L(+)-2-amino-3-phosphonopropionic acid (L-AP3......), which is known to be toxic in vivo after subchronic, but not acute, administration. Degenerative effects were monitored by measuring the cellular uptake of propidium iodide (PI; continuously present in the medium) and lactate dehydrogenase (LDH) leakage, and by using a panel of histological stains...

  8. 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...

  9. Role of spinal cord glutamate transporter during normal sensory transmission and pathological pain states

    Directory of Open Access Journals (Sweden)

    Stephens Robert L

    2005-10-01

    Full Text Available Abstract Glutamate is a neurotransmitter critical for spinal excitatory synaptic transmission and for generation and maintenance of spinal states of pain hypersensitivity via activation of glutamate receptors. Understanding the regulation of synaptically and non-synaptically released glutamate associated with pathological pain is important in exploring novel molecular mechanisms and developing therapeutic strategies of pathological pain. The glutamate transporter system is the primary mechanism for the inactivation of synaptically released glutamate and the maintenance of glutamate homeostasis. Recent studies demonstrated that spinal glutamate transporter inhibition relieved pathological pain, suggesting that the spinal glutamate transporter might serve as a therapeutic target for treatment of pathological pain. However, the exact function of glutamate transporter in pathological pain is not completely understood. This report will review the evidence for the role of the spinal glutamate transporter during normal sensory transmission and pathological pain conditions and discuss potential mechanisms by which spinal glutamate transporter is involved in pathological pain.

  10. Above and beyond C5a Receptor Targeting by Staphylococcal Leucotoxins: Retrograde Transport of Panton-Valentine Leucocidin and γ-Hemolysin.

    Science.gov (United States)

    Zimmermann-Meisse, Gaëlle; Prévost, Gilles; Jover, Emmanuel

    2017-01-20

    Various membrane receptors associated with the innate immune response have recently been identified as mediators of the cellular action of Staphylococcus aureus leucotoxins. Two of these, the Panton-Valentine leucotoxin LukS-PV/LukF-PV and the γ-hemolysin HlgC/HlgB, bind the C5a complement-derived peptide receptor. These leucotoxins utilize the receptor to induce intracellular Ca 2+ release from internal stores, other than those activated by C5a. The two leucotoxins are internalized with the phosphorylated receptor, but it is unknown whether they divert retrograde transport of the receptor or follow another pathway. Immunolabeling and confocal microscopic techniques were used to analyze the presence of leucotoxins in endosomes, lysosomes, endoplasmic reticulum, and Golgi. The two leucotoxins apparently followed retrograde transport similar to that of the C5a peptide-activated receptor. However, HlgC/HlgB reached the Golgi network very early, whereas LukS-PV/LukF-PV followed slower kinetics. The HlgC/HlgB leucotoxin remained in neutrophils 6 h after a 10-min incubation of the cells in the presence of the toxin with no signs of apoptosis, whereas apoptosis was observed 3 h after neutrophils were incubated with LukS-PV/LukF-PV. Such retrograde transport of leucotoxins provides a novel understanding of the cellular effects initiated by sublytic concentrations of these toxins.

  11. Above and beyond C5a Receptor Targeting by Staphylococcal Leucotoxins: Retrograde Transport of Panton–Valentine Leucocidin and γ-Hemolysin

    Directory of Open Access Journals (Sweden)

    Gaëlle Zimmermann-Meisse

    2017-01-01

    Full Text Available Various membrane receptors associated with the innate immune response have recently been identified as mediators of the cellular action of Staphylococcus aureus leucotoxins. Two of these, the Panton–Valentine leucotoxin LukS-PV/LukF-PV and the γ-hemolysin HlgC/HlgB, bind the C5a complement-derived peptide receptor. These leucotoxins utilize the receptor to induce intracellular Ca2+ release from internal stores, other than those activated by C5a. The two leucotoxins are internalized with the phosphorylated receptor, but it is unknown whether they divert retrograde transport of the receptor or follow another pathway. Immunolabeling and confocal microscopic techniques were used to analyze the presence of leucotoxins in endosomes, lysosomes, endoplasmic reticulum, and Golgi. The two leucotoxins apparently followed retrograde transport similar to that of the C5a peptide-activated receptor. However, HlgC/HlgB reached the Golgi network very early, whereas LukS-PV/LukF-PV followed slower kinetics. The HlgC/HlgB leucotoxin remained in neutrophils 6 h after a 10-min incubation of the cells in the presence of the toxin with no signs of apoptosis, whereas apoptosis was observed 3 h after neutrophils were incubated with LukS-PV/LukF-PV. Such retrograde transport of leucotoxins provides a novel understanding of the cellular effects initiated by sublytic concentrations of these toxins.

  12. A first-in-man PET study of [18F]PSS232, a fluorinated ABP688 derivative for imaging metabotropic glutamate receptor subtype 5.

    Science.gov (United States)

    Warnock, Geoffrey; Sommerauer, Michael; Mu, Linjing; Pla Gonzalez, Gloria; Geistlich, Susanne; Treyer, Valerie; Schibli, Roger; Buck, Alfred; Krämer, Stefanie D; Ametamey, Simon M

    2018-06-01

    Non-invasive imaging of metabotropic glutamate receptor 5 (mGlu 5 ) in the brain using PET is of interest in e.g., anxiety, depression, and Parkinson's disease. Widespread application of the most widely used mGlu 5 tracer, [ 11 C]ABP688, is limited by the short physical half-life of carbon-11. [ 18 F]PSS232 is a fluorinated analog with promising preclinical properties and high selectivity and specificity for mGlu 5 . In this first-in-man study, we evaluated the brain uptake pattern and kinetics of [ 18 F]PSS232 in healthy volunteers. [ 18 F]PSS232 PET was performed with ten healthy male volunteers aged 20-40 years. Seven of the subjects received a bolus injection and the remainder a bolus/infusion protocol. Cerebral blood flow was determined in seven subjects using [ 15 O]water PET. Arterial blood activity was measured using an online blood counter. Tracer kinetics were evaluated by compartment modeling and parametric maps were generated for both tracers. At 90 min post-injection, 59.2 ± 11.1% of total radioactivity in plasma corresponded to intact tracer. The regional first pass extraction fraction of [ 18 F]PSS232 ranged from 0.41 ± 0.06 to 0.55 ± 0.03 and brain distribution pattern matched that of [ 11 C]ABP688. Uptake kinetics followed a simple two-tissue compartment model. The volume of distribution of total tracer (V T , ml/cm 3 ) ranged from 1.18 ± 0.20 for white matter to 2.91 ± 0.51 for putamen. The respective mean distribution volume ratios (DVR) with cerebellum as the reference tissue were 0.88 ± 0.06 and 2.12 ± 0.10, respectively. The tissue/cerebellum ratios of a bolus/infusion protocol (30/70 dose ratio) were close to the DVR values. Brain uptake of [ 18 F]PSS232 matched the distribution of mGlu 5 and followed a two-tissue compartment model. The well-defined kinetics and the possibility to use reference tissue models, obviating the need for arterial blood sampling, make [ 18 F]PSS232 a promising fluorine-18 labeled

  13. The change of metabotropic glutamate receptor 5 expression level in rats with late-stage traumatic brain injury and the therapeutic effect of taurine

    Directory of Open Access Journals (Sweden)

    Ying CAI

    2016-08-01

    Full Text Available Objective To investigate the change of metabotropic glutamate receptor 5 (mGluR5 expression level in rats with late-stage (the 7th day traumatic brain injury (TBI and the role of taurine. Methods The left cerebral TBI rat models were made by using lateral fluid percussion method. A total of 30 specific pathogen free (SPF male Sprague-Dawley (SD rats were randomly divided into 3 groups: sham operation group (control group, TBI model group (TBI group and taurine treatment group (taurine group. Wet and dry weight method was used to measure the brain water content. Real-time fluorescent quantitative polymerase chain reaction (PCR and Western blotting were used to detect the change of mRNA and protein expression of aquaporin 4 (AQP4 and mGluR5 in each group.  Results Compared with control group, the brain water content (t = 4.893, P = 0.002, AQP4 mRNA (t = 6.523, P = 0.000 and protein (t = 4.366, P = 0.008 expression were upregulated, while mGluR5 mRNA (t = 5.776, P = 0.001 and protein (t = 3.945, P = 0.014 expression were downregulated in TBI group. After taurine treatment, the brain water content (t = 2.151, P = 0.140, AQP4 mRNA (t = 1.144,P = 0.432 and protein (t = 0.367, P = 0.804 decreased to normal, while mGluR5 mRNA (t = 1.824, P = 0.216 and protein (t = 1.185, P = 0.414 increased to normal. Correlation analysis showed brain water content was negatively correlated with mGluR5 mRNA (r = -0.617, P = 0.014 and mGluR5 protein (r = -0.665, P = 0.007, while it was positively correlated with AQP4 protein (r = 0.658, P = 0.008.  Conclusions Taurine can significantly increase the mGluR5 expression level of brain issue in the late-stage (the 7th day of TBI and decline brain edema and brain water content. It may be a potential protective agent as an inhibitory neurotransmitter. DOI: 10.3969/j.issn.1672-6731.2016.08.008

  14. Frequency-dependent depression of excitatory synaptic transmission is independent of activation of MCPG-sensitive presynaptic metabotropic glutamate receptors in cultured hippocampal neurons.

    Science.gov (United States)

    Maki, R; Cummings, D D; Dichter, M A

    1995-10-01

    1. A paired-pulse paradigm, and a high-frequency train followed by a test pulse, were used to investigate the possible role of presynaptic metabotropic glutamate receptors (mGluRs) in frequency-dependent modulation of the amplitude of excitatory post-synaptic currents (EPSCs). Paired whole cell patch-clamp recordings from monosynaptically connected hippocampal neurons maintained in very low-density cultures were performed, using the mGluR antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG, 500 microM) and the mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD, 100 microM]. 2. Paired-pulse depression (PPD) was observed in all the excitatory pairs recorded. The average PPD ratio (amplitude of the 2nd EPSC divided by the amplitude of the 1st EPSC) was 0.80 +/- 0.1 (SD) (n = 8). Application of the mGluR antagonist MCPG had no effect on the amplitude of the EPSCs and did not affect the ratio of the two EPSCs (PPD ratio 0.79 +/- 0.2). 3. The amplitudes of 10 successive EPSCs stimulated at a high frequency (20 Hz) decremented on average in both 4 mM extracellular Ca2+ (n = 5) and in 1 mM extracellular Ca2+ (n = 6). In all pairs tested, posttetanic depression (PTD) was observed (PTD ratio 0.7 +/- 0.2). Bath application of MCPG (500 microM) did not affect the amplitudes of the EPSCs during the train; MCPG also did not affect PTD. 4. The mGluR agonist (1S,3R)-ACPD depressed the amplitudes of the EPSCs in both the paired-pulse (1st EPSC, 35 +/- 9%; 2nd EPSC, 36 +/- 10%) and posttetanic pulse (1 and 4 mM extracellular Ca2+) paradigms. The amount of depression observed, both PPD and PTD, remained unaffected by application of (1S,3R)-ACPD. Coapplication of the antagonist MCPG (500 microM) blocked the effects of (1S,3R)-ACPD (100 microM). 5. We conclude that frequency-dependent depression of EPSC amplitudes occurs independent of endogenous activation of MCPG-sensitive mGluRs in cultured hippocampal neurons. Moreover, we demonstrate that exogenous

  15. Preclinical evaluation and test-retest studies of [{sup 18}F]PSS232, a novel radioligand for targeting metabotropic glutamate receptor 5 (mGlu{sub 5})

    Energy Technology Data Exchange (ETDEWEB)

    Milicevic Sephton, Selena; Mueller Herde, Adrienne; Keller, Claudia; Ruedisuehli, Sonja; Schibli, Roger; Kraemer, Stefanie D.; Ametamey, Simon M. [Center for Radiopharmaceutical Sciences of ETH, PSI and USZ, Zurich (Switzerland); Mu, Linjing [University Hospital Zuerich, Department of Nuclear Medicine, Zuerich (Switzerland); Auberson, Yves [Novartis Institutes for Biomedical Research, Novartis Pharma AG, Basel (Switzerland)

    2015-01-15

    A novel, {sup 18}F-labelled metabotropic glutamate receptor subtype 5 (mGlu{sub 5}) derivative of [{sup 11}C]ABP688 ([{sup 11}C]1), [{sup 18}F]PSS232 ([{sup 18}F]5), was evaluated in vitro and in vivo for its potential as a PET agent and was used in test-retest reliability studies The radiosynthesis of [{sup 18}F]5 was accomplished via a one-step reaction using a mesylate precursor. In vitro stability was determined in PBS and plasma, and with liver microsomal enzymes. Metabolite studies were performed using rat brain extracts, blood and urine. In vitro autoradiography was performed on horizontal slices of rat brain using 1 and 8, antagonists for mGlu{sub 5} and mGlu{sub 1}, respectively. Small-animal PET, biodistribution, and test-retest studies were performed in Wistar rats. In vivo, dose-dependent displacement studies were performed using 6 and blocking studies with 7. [{sup 18}F]5 was obtained in decay-corrected maximal radiochemical yield of 37 % with a specific activity of 80 - 400 GBq/μmol. Treatment with rat and human microsomal enzymes in vitro for 60 min resulted in 20 % and 4 % of hydrophilic radiometabolites, respectively. No hydrophilic decomposition products or radiometabolites were found in PBS or plasma. In vitro autoradiography on rat brain slices showed a heterogeneous distribution consistent with the known distribution of mGlu{sub 5} with high binding to hippocampal and cortical regions, and negligible radioactivity in the cerebellum. Similar distribution of radioactivity was found in PET images. Under displacement conditions with 6, reduced [{sup 18}F]5 binding was found in all brain regions except the cerebellum. 7 reduced binding in the striatum by 84 % on average. Test-retest studies were reproducible with a variability ranging from 6.8 % to 8.2 %. An extended single-dose toxicity study in Wistar rats showed no compound-related adverse effects. The new mGlu{sub 5} radiotracer, [{sup 18}F]5, showed specific and selective in vitro and in vivo

  16. Role of Site-Specific N-Glycans Expressed on GluA2 in the Regulation of Cell Surface Expression of AMPA-Type Glutamate Receptors.

    Directory of Open Access Journals (Sweden)

    Yusuke Takeuchi

    Full Text Available The AMPA-type glutamate receptor (AMPAR, which is a tetrameric complex composed of four subunits (GluA1-4 with several combinations, mediates the majority of rapid excitatory synaptic transmissions in the nervous system. Cell surface expression levels of AMPAR modulate synaptic plasticity, which is considered one of the molecular bases for learning and memory formation. To date, a unique trisaccharide (HSO3-3GlcAβ1-3Galβ1-4GlcNAc, human natural killer-1 (HNK-1 carbohydrate, was found expressed specifically on N-linked glycans of GluA2 and regulated the cell surface expression of AMPAR and the spine maturation process. However, evidence that the HNK-1 epitope on N-glycans of GluA2 directly affects these phenomena is lacking. Moreover, it is thought that other N-glycans on GluA2 also have potential roles in the regulation of AMPAR functions. In the present study, using a series of mutants lacking potential N-glycosylation sites (N256, N370, N406, and N413 within GluA2, we demonstrated that the mutant lacking the N-glycan at N370 strongly suppressed the intracellular trafficking of GluA2 from the endoplasmic reticulum (ER in HEK293 cells. Cell surface expression of GluA1, which is a major subunit of AMPAR in neurons, was also suppressed by co-expression of the GluA2 N370S mutant. The N370S mutant and wild-type GluA2 were co-immunoprecipitated with GluA1, suggesting that N370S was properly associated with GluA1. Moreover, we found that N413 was the main potential site of the HNK-1 epitope that promoted the interaction of GluA2 with N-cadherin, resulting in enhanced cell surface expression of GluA2. The HNK-1 epitope on N-glycan at the N413 of GluA2 was also involved in the cell surface expression of GluA1. Thus, our data suggested that site-specific N-glycans on GluA2 regulate the intracellular trafficking and cell surface expression of AMPAR.

  17. Distribution of N-methyl D-aspartate (NMDA) receptor mRNAs in the rat suprachiasmatic nucleus

    DEFF Research Database (Denmark)

    Mikkelsen, J.D.; Larsen, Philip J.; Ebling, Francis J.P.

    1993-01-01

    Anatomi, neurobiologi, glutamate receptor, circadian rhythms, suprachiasmatic nucleus, in situ hybridization, rat......Anatomi, neurobiologi, glutamate receptor, circadian rhythms, suprachiasmatic nucleus, in situ hybridization, rat...

  18. Glutamate Receptor Aptamers and ALS

    National Research Council Canada - National Science Library

    Niu, Li

    2008-01-01

    .... An aptamer is a single-stranded nucleic acid that directly inhibits a protein's function by folding into a specific tertiary structure that dictates high-affinity binding to the target protein...

  19. Serotonin-1A receptor stimulation mediates effects of a metabotropic glutamate 2/3 receptor antagonist, 2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl)propanoic acid (LY341495), and an N-methyl-D-aspartate receptor antagonist, ketamine, in the novelty-suppressed feeding test.

    Science.gov (United States)

    Fukumoto, Kenichi; Iijima, Michihiko; Chaki, Shigeyuki

    2014-06-01

    α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor stimulation has been proposed to be a common neural mechanism of metabotropic glutamate 2/3 (mGlu2/3) receptor antagonists and an N-methyl-D-aspartate receptor antagonist, ketamine, exerting antidepressant effects in animal models. AMPA receptor stimulation has also been shown to mediate an increase in the extracellular level of serotonin (5-HT) in the medial prefrontal cortex by an mGlu2/3 receptor antagonist in rats. However, involvement of the serotonergic system in the actions of mGlu2/3 receptor antagonists and ketamine is not well understood. We investigated involvement of the serotonergic system in the effects of an mGlu2/3 receptor antagonist, 2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl)propanoic acid (LY341495), and ketamine in a novelty-suppressed feeding (NSF) test in mice. The intraperitoneal administration of LY341495 or ketamine at 30 min prior to the test significantly shortened latency to feed, which was attenuated by an AMPA receptor antagonist, 2,3-dioxo-6-nitro-1,2,3,4-tetrahydr-obenzo[f]quinoxaline-7-sulfonamide (NBQX). The effects of LY341495 and ketamine were no longer observed in mice pretreated with a tryptophan hydroxylase inhibitor, para-chlorophenylalanine (PCPA). Moreover, the effects of LY341495 and ketamine were blocked by a 5-HT1A receptor antagonist, N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridynyl) cyclohexane-carboxamide (WAY100635), but not by a 5-HT2A/2C receptor antagonist, ritanserin. Likewise, an AMPA receptor potentiator, 2,3-dihydro-1,4-benzodioxin-7-yl-(1-piperidyl)methanone (CX546), shortened latency to feed in the NSF test, which was prevented by depletion of 5-HT and blockade of 5-HT1A receptor. These results suggest that AMPA receptor-dependent 5-HT release and subsequent 5-HT1A receptor stimulation may be involved in the actions of an mGlu2/3 receptor antagonist and ketamine in the NSF test.

  20. 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.

  1. The Influence of Glutamate on Axonal Compound Action Potential In Vitro.

    Science.gov (United States)

    Abouelela, Ahmed; Wieraszko, Andrzej

    2016-01-01

    Background  Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives  The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods  Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results  The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion  The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.

  2. Memory Trace Reactivation and Behavioral Response during Retrieval Are Differentially Modulated by Amygdalar Glutamate Receptors Activity: Interaction between Amygdala and Insular Cortex

    Science.gov (United States)

    Osorio-Gómez, Daniel; Guzmán-Ramos, Kioko; Bermúdez-Rattoni, Federico

    2017-01-01

    The insular cortex (IC) is required for conditioned taste aversion (CTA) retrieval. However, it remains unknown which cortical neurotransmitters levels are modified upon CTA retrieval. Using in vivo microdialysis, we observed that there were clear elevations in extracellular glutamate, norepinephrine, and dopamine in and around the center of the…

  3. Transcriptional profiling of striatal neurons in response to single or concurrent activation of dopamine D2, adenosine A(2A) and metabotropic glutamate type 5 receptors: focus on beta-synuclein expression.

    Science.gov (United States)

    Canela, Laia; Selga, Elisabet; García-Martínez, Juan Manuel; Amaral, Olavo B; Fernández-Dueñas, Víctor; Alberch, Jordi; Canela, Enric I; Franco, Rafael; Noé, Véronique; Lluís, Carme; Ciudad, Carlos J; Ciruela, Francisco

    2012-10-25

    G protein-coupled receptor oligomerization is a concept which is changing the understanding of classical pharmacology. Both, oligomerization and functional interaction between adenosine A(2A,) dopamine D(2) and metabotropic glutamate type 5 receptors have been demonstrated in the striatum. However, the transcriptional consequences of receptors co-activation are still unexplored. We aim here to determine the changes in gene expression of striatal primary cultured neurons upon isolated or simultaneous receptor activation. Interestingly, we found that 95 genes of the total analyzed (15,866 transcripts and variants) changed their expression in response to simultaneous stimulation of all three receptors. Among these genes, we focused on the β-synuclein (β-Syn) gene (SCNB). Quantitative PCR verified the magnitude and direction of change in expression of SCNB. Since β-Syn belongs to the homologous synuclein family and may be considered a natural regulator of α-synuclein (α-Syn), it has been proposed that β-Syn might act protectively against α-Syn neuropathology. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Expression of complement C5a receptor and the viability of 4T1 tumor cells following agonist–antagonist treatment

    Directory of Open Access Journals (Sweden)

    Nurneqman Nashreq Kosni

    2016-01-01

    Conclusion: This experiment shows the presence of C5a receptor on 4T1 cell line. We believe that the antagonist peptide is eligible to be used widely in cancer immunotherapy field; but in vivo studies need to be carried out first in the future, as it will determine how these drugs affect the tumor cell growth.

  5. Dengue Virus Infection Is through a Cooperative Interaction between a Mannose Receptor and CLEC5A on Macrophage as a Multivalent Hetero-Complex

    Science.gov (United States)

    Lyu, Jia-Huei; Hsiao, Michael; Hsu, Tsui-Ling; Wong, Chi-Huey

    2016-01-01

    Dengue fever is a mosquito-borne viral pandemic disease that is widespread in the tropical and subtropical areas. Dengue virus uses human mannose-binding receptor (MR) and DC-SIGN on macrophages as primary receptors, and CLEC5A as signaling receptor to sense the dengue virus invasion and then to signal and stimulate macrophages to secrete cytokines. But the interplay between MR/DC-SIGN and CLEC5A is unknown. Here we demonstrate a plausible mechanism for the interaction, i.e. MR/DC-SIGN first attracts the virus with high avidity, and the virus concurrently interacts with CLEC5A in close proximity to form a multivalent hetero-complex and facilitate CLEC5A-mediated signal transduction. Our study suggests that the cooperation between a high-avidity lectin-virus interaction and a nearby low-avidity signaling receptor provides a necessary connection between binding and signaling. Understanding this mechanism may lead to the development of a new antiviral strategy. PMID:27832191

  6. Differential Interaction of the Staphylococcal Toxins Panton-Valentine Leukocidin and γ-Hemolysin CB with Human C5a Receptors.

    Science.gov (United States)

    Spaan, András N; Schiepers, Ariën; de Haas, Carla J C; van Hooijdonk, Davy D J J; Badiou, Cédric; Contamin, Hugues; Vandenesch, François; Lina, Gérard; Gerard, Norma P; Gerard, Craig; van Kessel, Kok P M; Henry, Thomas; van Strijp, Jos A G

    2015-08-01

    Staphylococcus aureus is well adapted to the human host. Evasion of the host phagocyte response is critical for successful infection. The staphylococcal bicomponent pore-forming toxins Panton-Valentine leukocidin LukSF-PV (PVL) and γ-hemolysin CB (HlgCB) target human phagocytes through interaction with the complement receptors C5aR1 and C5aR2. Currently, the apparent redundancy of both toxins cannot be adequately addressed in experimental models of infection because mice are resistant to PVL and HlgCB. The molecular basis for species specificity of the two toxins in animal models is not completely understood. We show that PVL and HlgCB feature distinct activity toward neutrophils of different mammalian species, where activity of PVL is found to be restricted to fewer species than that of HlgCB. Overexpression of various mammalian C5a receptors in HEK cells confirms that cytotoxicity toward neutrophils is driven by species-specific interactions of the toxins with C5aR1. By taking advantage of the species-specific engagement of the toxins with their receptors, we demonstrate that PVL and HlgCB differentially interact with human C5aR1 and C5aR2. In addition, binding studies illustrate that different parts of the receptor are involved in the initial binding of the toxin and the subsequent formation of lytic pores. These findings allow a better understanding of the molecular mechanism of pore formation. Finally, we show that the toxicity of PVL, but not of HlgCB, is neutralized by various C5aR1 antagonists. This study offers directions for the development of improved preclinical models for infection, as well as for the design of drugs antagonizing leukocidin toxicity. Copyright © 2015 by The American Association of Immunologists, Inc.

  7. Rat odontoblasts may use glutamate to signal dentin injury.

    Science.gov (United States)

    Cho, Yi Sul; Ryu, Chang Hyun; Won, Jong Hwa; Vang, Hue; Oh, Seog Bae; Ro, Jin Young; Bae, Yong Chul

    2016-10-29

    Accumulating evidence indicates that odontoblasts act as sensor cells, capable of triggering action potentials in adjacent pulpal nociceptive axons, suggesting a paracrine signaling via a currently unknown mediator. Since glutamate can mediate signaling by non-neuronal cells, and peripheral axons may express glutamate receptors (GluR), we hypothesized that the expression of high levels of glutamate, and of sensory receptors in odontoblasts, combined with an expression of GluR in adjacent pulpal axons, is the morphological basis for odontoblastic sensory signaling. To test this hypothesis, we investigated the expression of glutamate, the thermo- and mechanosensitive ion channels transient receptor potential vanilloid 1 (TRPV1), transient receptor potential ankyrin 1 (TRPA1), and TWIK-1-related K+channel (TREK-1), and the glutamate receptor mGluR5, in a normal rat dental pulp, and following dentin injury. We also examined the glutamate release from odontoblast in cell culture. Odontoblasts were enriched with glutamate, at the level as high as in adjacent pulpal axons, and showed immunoreactivity for TRPV1, TRPA1, and TREK-1. Pulpal sensory axons adjacent to odontoblasts expressed mGluR5. Both the levels of glutamate in odontoblasts, and the expression of mGluR5 in nearby axons, were upregulated following dentin injury. The extracellular glutamate concentration was increased significantly after treating of odontoblast cell line with calcium permeable ionophore, suggesting glutamate release from odontoblasts. These findings lend morphological support to the hypothesis that odontoblasts contain glutamate as a potential neuroactive substance that may activate adjacent pulpal axons, and thus contribute to dental pain and hypersensitivity. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Perinatal exposure to low-dose of bisphenol A causes anxiety-like alteration in adrenal axis regulation and behaviors of rat offspring: a potential role for metabotropic glutamate 2/3 receptors.

    Science.gov (United States)

    Zhou, Rong; Chen, Fang; Feng, Xuejiao; Zhou, Libin; Li, Yingchun; Chen, Ling

    2015-05-01

    The present study focuses on detecting anxiety-like behavior and associated neurochemical alterations in adolescent rats exposed perinatally to bisphenol A (BPA), an estrogen-mimicking endocrine disrupter and investigating the possible involvement of metabotropic glutamate 2/3 receptors (mGlu2/3 receptors) in BPA-induced anxiogenic effects. When female breeders were administered orally with BPA (40 μg/kg/d) during pregnancy and lactation, their pups (here named 'BPA-exposed offspring') developed an anxiety-like phenotype, characterized by the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, impaired glucocorticoid receptor (GR)-mediated negative feedback regulation of the HPA axis, altered hippocampal synaptic plasticity and increased anxiety-like behaviors. BPA-exposed offspring also showed a reduced expression of mGlu2/3 receptors in the hippocampus. BPA-exposed offspring further subjected to systemic administration of mGlu2/3 receptor agonist (LY379268, 0.5 mg/kg, i.p.) or antagonist (LY341495, 1.5 mg/kg, i.p.) twice per day for 6 days. The results indicated that chronic LY379268 treatment corrected the anxiety-like behaviors and associated neurochemical and endocrinological alterations in BPA-exposed offspring. Our data demonstrate for the first time that the perinatal BPA exposure induces an anxiety-like phenotype in behaviors and -related neuroendocrinology, and suggest that the changes in mGlu2/3 receptor might lie at the core of the pathological reprogramming triggered by early-life adversity. mGlu2/3 receptor may serve as a novel biomarker and potential therapeutic target for anxiety disorders associated with adverse early-life agents including perinatal BPA exposure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Discovery of VU6005649, a CNS Penetrant mGlu7/8 Receptor PAM Derived from a Series of Pyrazolo[1,5-a]pyrimidines.

    Science.gov (United States)

    Abe, Masahito; Seto, Mabel; Gogliotti, Rocco G; Loch, Matthew T; Bollinger, Katrina A; Chang, Sichen; Engelberg, Eileen M; Luscombe, Vincent B; Harp, Joel M; Bubser, Michael; Engers, Darren W; Jones, Carrie K; Rodriguez, Alice L; Blobaum, Anna L; Conn, P Jeffrey; Niswender, Colleen M; Lindsley, Craig W

    2017-10-12

    Herein, we report the structure-activity relationships within a series of mGlu 7 PAMs based on a pyrazolo[1,5- a ]pyrimidine core with excellent CNS penetration ( K p s > 1 and K p,uu s > 1). Analogues in this series proved to display a range of Group III mGlu receptor selectivity, but VU6005649 emerged as the first dual mGlu 7/8 PAM, filling a void in the Group III mGlu receptor PAM toolbox and demonstrating in vivo efficacy in a mouse contextual fear conditioning model.

  10. Increased prevalence of diverse N-methyl-D-aspartate glutamate receptor antibodies in patients with an initial diagnosis of schizophrenia: specific relevance of IgG NR1a antibodies for distinction from N-methyl-D-aspartate glutamate receptor encephalitis.

    Science.gov (United States)

    Steiner, Johann; Walter, Martin; Glanz, Wenzel; Sarnyai, Zoltán; Bernstein, Hans-Gert; Vielhaber, Stefan; Kästner, Andrea; Skalej, Martin; Jordan, Wolfgang; Schiltz, Kolja; Klingbeil, Christine; Wandinger, Klaus-Peter; Bogerts, Bernhard; Stoecker, Winfried

    2013-03-01

    Evidence for symptomatic convergence of schizophrenia and N-methyl-D-aspartate glutamate receptor (NMDA-R) encephalitis highlights the need for an assessment of antibody prevalence and specificity for distinct disease mechanisms in patients with a diagnosis of schizophrenia among glutamatergic pathophysiologic abnormalities in psychiatric disorders. To compare the specificity and prevalence of NMDA-R antibodies in schizophrenia (DSM-IV criteria) with those of other psychiatric diagnoses and to determine whether antibody subtypes characterize overlap with and distinction from those in NMDA-R encephalitis. Serum from 459 patients admitted with acute schizophrenia, major depression (MD), and borderline personality disorder (BLPD) or individuals serving as matched controls was obtained from our scientific blood bank. To explore epitope specificity and antibody subtype, IgA/IgG/IgM NMDA-R (NR1a or NR1a/NR2b) and α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPA-R) (GluR1/GluR2) serum antibodies were determined. Two hundred thirty matched healthy controls were compared with patients (unmedicated for at least 6 weeks) with schizophrenia (n = 121), MD (n = 70), or BLPD (n = 38). The primary outcome was the overall number of seropositive cases for NMDA-R and AMPA-R antibodies; the secondary outcome was disease specificity of IgA/IgG/IgM antibodies and epitope specificity for clinical subgroups. Diverse NMDA-R antibodies were identified in 15 subjects, primarily those with an initial schizophrenia diagnosis (9.9%), opposed to MD (2.8%), BLPD (0), and controls (0.4%). Retrospectively, 2 patients initially classified as having catatonic or disorganized schizophrenia were reclassified as having misdiagnosed NMDA-R encephalitis (presence of specific serum and cerebrospinal fluid IgG NR1a antibodies). In all other seropositive cases, the antibodies consisted of classes IgA and/or IgM or were directed against NR1a/NR2b (not against NR1a alone). None of the

  11. Microinjection of NMDA-type glutamate receptor agonist NMDA and antagonist D-AP-5 into the central nucleus of the amygdale alters water intake rather than food intake.

    Science.gov (United States)

    Yan, Junbao; Yan, Jianqun; Li, Jinrong; Chen, Ke; Sun, Huiling; Zhang, Yuan; Zhao, Xiaolin; Sun, Bo; Zhao, Shiru; Song, Lin; Wei, Xiaojing

    2012-05-01

    To investigate the role of N-Methyl-D-aspartic acid (NMDA)-type glutamate receptors in the central nucleus of the amygdale (CeA) in food and water intake. Male Sprague-Dawley rats with stainless steel cannulae implanted unilaterally into the CeA were used. The prototypic NMDA receptor agonist NMDA, or the selective NMDA receptor antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-AP-5) was microinjected into the CeA of satiated and euhydrated rats. Intra-CeA injection of 8.50, 17.00, or 34.00 nmol NMDA did not alter food intake but significantly increased water intake 0-1 h after the injection (F(3,32)=3.191, P=0.037) independent of food intake. Without affecting the food intake, injection of 6.34, 12.70, or 25.40 nmol D-AP-5 into the CeA significantly decreased water intake 0-1 h after the injection (F(3,28)=3.118, P=0.042) independent of food intake. NMDA receptors in the CeA may participate in the control of water intake rather than food intake.

  12. Novel reciprocal regulation of cAMP signaling and apoptosis by orphan G-protein-coupled receptor GPRC5A gene expression

    International Nuclear Information System (INIS)

    Hirano, Minoru; Zang, Liqing; Oka, Takehiko; Ito, Yoshiyuki; Shimada, Yasuhito; Nishimura, Yuhei; Tanaka, Toshio

    2006-01-01

    GPRC5A is a member of G-protein-coupled receptors, which was originally identified as an all-trans-retinoic acid-induced gene. Although recent studies reported that this gene was highly expressed in the cancer cell lines and that GPRC5A might positively regulate cell proliferation, its mechanism remains unknown. We investigated the upstream and downstream signaling of GPRC5A and its biological function, and found that cAMP signaling is the novel GPRC5A induction pathway. When GPRC5A gene was overexpressed, intracellular cAMP concentration was decreased, and Gsα gene expression was downregulated. On the other hand, RNA interference of GPRC5A increased mRNA levels of Gsα and intracellular cAMP, reduced cell number, and induced apoptosis. Conversely, cell number was increased by GPRC5A overexpression. We first report the novel negative feedback model of cAMP signaling through GPRC5A gene expression. This evidence explains one of the mechanisms of the GPRC5A-regulated cell growth in some cancer cell lines

  13. Crystallization and X-ray diffraction analysis of human CLEC5A (MDL-1), a dengue virus receptor

    International Nuclear Information System (INIS)

    Watson, Aleksandra A.; O’Callaghan, Christopher A.

    2009-01-01

    Recombinant human CLEC5A was crystallized in the trigonal space group P3 1 and X-ray diffraction data were collected to 1.56 Å resolution. The human C-type lectin-like protein CLEC5A (also known as MDL-1) is expressed on the surface of myeloid cells and plays a critical role in dengue-virus-induced disease by signalling through the transmembrane adaptor protein DAP12. The C-type lectin-like domain of CLEC5A was expressed in Escherichia coli, refolded and purified. Recombinant CLEC5A crystals were grown by sitting-drop vapour diffusion using polyethylene glycol 6000 as a precipitant. After optimization, crystals were grown which diffracted to 1.56 Å using synchrotron radiation. The results presented in this paper suggest that crystals producing diffraction of this quality will be suitable for structural determination of human CLEC5A

  14. Nonstructural 5A Protein of Hepatitis C Virus Interferes with Toll-Like Receptor Signaling and Suppresses the Interferon Response in Mouse Liver.

    Directory of Open Access Journals (Sweden)

    Takeya Tsutsumi

    Full Text Available The hepatitis C virus nonstructural protein NS5A is involved in resistance to the host immune response, as well as the viral lifecycle such as replication and maturation. Here, we established transgenic mice expressing NS5A protein in the liver and examined innate immune responses against lipopolysaccharide (LPS in vivo. Intrahepatic gene expression levels of cytokines such as interleukin-6, tumor necrosis factor-α, and interferon-γ were significantly suppressed after LPS injection in the transgenic mouse liver. Induction of the C-C motif chemokine ligand 2, 4, and 5 was also suppressed. Phosphorylation of the signal transducer and activator of transcription 3, which is activated by cytokines, was also reduced, and expression levels of interferon-stimulated genes, 2'-5' oligoadenylate synthase, interferon-inducible double-stranded RNA-activated protein kinase, and myxovirus resistance 1 were similarly suppressed. Since LPS binds to toll-like receptor 4 and stimulates the downstream pathway leading to induction of these genes, we examined the extracellular signal-regulated kinase and IκB-α. The phosphorylation levels of these molecules were reduced in transgenic mouse liver, indicating that the pathway upstream of the molecules was disrupted by NS5A. Further analyses revealed that the interaction between interleukin-1 receptor-associated kinase-1 and tumor necrosis factor receptor associated factor-6 was dispersed in transgenic mice, suggesting that NS5A may interfere with this interaction via myeloid differentiation primary response gene 88, which was shown to interact with NS5A. Since the gut microbiota, a source of LPS, is known to be associated with pathological conditions in liver diseases, our results suggest the involvement of NS5A in the pathogenesis of HCV infected-liver via the suppression of innate immunity.

  15. TRPM5, a taste-signaling transient receptor potential ion-channel, is a ubiquitous signaling component in chemosensory cells

    Directory of Open Access Journals (Sweden)

    Hofmann Thomas

    2007-07-01

    Full Text Available Abstract Background A growing number of TRP channels have been identified as key players in the sensation of smell, temperature, mechanical forces and taste. TRPM5 is known to be abundantly expressed in taste receptor cells where it participates in sweet, amino acid and bitter perception. A role of TRPM5 in other sensory systems, however, has not been studied so far. Results Here, we systematically investigated the expression of TRPM5 in rat and mouse tissues. Apart from taste buds, where we found TRPM5 to be predominantly localized on the basolateral surface of taste receptor cells, TRPM5 immunoreactivity was seen in other chemosensory organs – the main olfactory epithelium and the vomeronasal organ. Most strikingly, we found solitary TRPM5-enriched epithelial cells in all parts of the respiratory and gastrointestinal tract. Based on their tissue distribution, the low cell density, morphological features and co-immunostaining with different epithelial markers, we identified these cells as brush cells (also known as tuft, fibrillovesicular, multivesicular or caveolated cells. In terms of morphological characteristics, brush cells resemble taste receptor cells, while their origin and biological role are still under intensive debate. Conclusion We consider TRPM5 to be an intrinsic signaling component of mammalian chemosensory organs, and provide evidence for brush cells being an important cellular correlate in the periphery.

  16. TRPM5, a taste-signaling transient receptor potential ion-channel, is a ubiquitous signaling component in chemosensory cells.

    Science.gov (United States)

    Kaske, Silke; Krasteva, Gabriele; König, Peter; Kummer, Wolfgang; Hofmann, Thomas; Gudermann, Thomas; Chubanov, Vladimir

    2007-07-04

    A growing number of TRP channels have been identified as key players in the sensation of smell, temperature, mechanical forces and taste. TRPM5 is known to be abundantly expressed in taste receptor cells where it participates in sweet, amino acid and bitter perception. A role of TRPM5 in other sensory systems, however, has not been studied so far. Here, we systematically investigated the expression of TRPM5 in rat and mouse tissues. Apart from taste buds, where we found TRPM5 to be predominantly localized on the basolateral surface of taste receptor cells, TRPM5 immunoreactivity was seen in other chemosensory organs - the main olfactory epithelium and the vomeronasal organ. Most strikingly, we found solitary TRPM5-enriched epithelial cells in all parts of the respiratory and gastrointestinal tract. Based on their tissue distribution, the low cell density, morphological features and co-immunostaining with different epithelial markers, we identified these cells as brush cells (also known as tuft, fibrillovesicular, multivesicular or caveolated cells). In terms of morphological characteristics, brush cells resemble taste receptor cells, while their origin and biological role are still under intensive debate. We consider TRPM5 to be an intrinsic signaling component of mammalian chemosensory organs, and provide evidence for brush cells being an important cellular correlate in the periphery.

  17. Bidirectional regulation of thermotaxis by glutamate transmissions in Caenorhabditis elegans.

    Science.gov (United States)

    Ohnishi, Noriyuki; Kuhara, Atsushi; Nakamura, Fumiya; Okochi, Yoshifumi; Mori, Ikue

    2011-04-06

    In complex neural circuits of the brain, massive information is processed with neuronal communication through synaptic transmissions. It is thus fundamental to delineate information flows encoded by various kinds of transmissions. Here, we show that glutamate signals from two distinct sensory neurons bidirectionally affect the same postsynaptic interneuron, thereby producing the opposite behaviours. EAT-4/VGLUT (vesicular glutamate transporter)-dependent glutamate signals from AFD thermosensory neurons inhibit the postsynaptic AIY interneurons through activation of GLC-3/GluCl inhibitory glutamate receptor and behaviourally drive migration towards colder temperature. By contrast, EAT-4-dependent glutamate signals from AWC thermosensory neurons stimulate the AIY neurons to induce migration towards warmer temperature. Alteration of the strength of AFD and AWC signals led to significant changes of AIY activity, resulting in drastic modulation of behaviour. We thus provide an important insight on information processing, in which two glutamate transmissions encoding opposite information flows regulate neural activities to produce a large spectrum of behavioural outputs.

  18. Selective agonists at group II metabotropic glutamate receptors: synthesis, stereochemistry, and molecular pharmacology of (S)- and (R)-2-amino-4-(4-hydroxy[1,2,5]thiadiazol-3-yl)butyric acid

    DEFF Research Database (Denmark)

    Clausen, Rasmus P; Bräuner-Osborne, Hans; Greenwood, Jeremy R

    2002-01-01

    )-form of the 1,2,5-thiadiazol-3-ol Glu analogue, 2-amino-3-(4-hydroxy[1,2,5]thiadiazol-3-yl)propionic acid (TDPA, 6), is an 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, which in addition stereospecifically activates group I mGluRs. We have now synthesized the (S)- and (R......Homologation of analogues of the central excitatory neurotransmitter glutamic acid (Glu), in which the distal carboxy group has been bioisosterically replaced by acidic heterocyclic units, has previously provided subtype selective ligands for metabotropic Glu receptors (mGluRs). The (S......)-forms of 2-amino-4-(4-hydroxy[1,2,5]thiadiazol-3-yl)butyric acid (homo-TDPA, 7) and shown that whereas neither enantiomer interacts with AMPA receptors, (S)- and (R)-7 appear to be selective and equipotent agonists at group II mGluRs as represented by the mGluR2 subtype. The activities of (S)- and (R)-7...

  19. Glutamate and Neurotrophic Factors in Neuronal Plasticity and Disease

    Science.gov (United States)

    Mattson, Mark P.

    2008-01-01

    Glutamate’s role as a neurotransmitter at synapses has been known for 40 years, but glutamate has since been shown to regulate neurogenesis, neurite outgrowth, synaptogenesis and neuron survival in the developing and adult mammalian nervous system. Cell surface glutamate receptors are coupled to Ca2+ influx and release from endoplasmic reticulum stores which causes rapid (kinase- and protease-mediated) and delayed (transcription-dependent) responses that change the structure and function of neurons. Neurotrophic factors and glutamate interact to regulate developmental and adult neuroplasticity. For example, glutamate stimulates the production of brain-derived neurotrophic factor (BDNF) which, in turn, modifies neuronal glutamate sensitivity, Ca2+ homeostasis and plasticity. Neurotrophic factors may modify glutamate signalling directly, by changing the expression of glutamate receptor subunits and Ca2+-regulating proteins, and also indirectly by inducing the production of antioxidant enzymes, energy-regulating proteins and anti-apoptotic Bcl2 family members. Excessive activation of glutamate receptors, under conditions of oxidative and metabolic stress, may contribute to neuronal dysfunction and degeneration in diseases ranging from stroke and Alzheimer’s disease to psychiatric disorders. By enhancing neurotrophic factor signalling, environmental factors such as exercise and dietary energy restriction, and chemicals such as antidepressants may optimize glutamatergic signalling and protect against neurological disorders. PMID:19076369

  20. Early continuous white noise exposure alters l-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor subunit glutamate receptor 2 and gamma-aminobutyric acid type a receptor subunit beta3 protein expression in rat auditory cortex.

    Science.gov (United States)

    Xu, Jinghong; Yu, Liping; Zhang, Jiping; Cai, Rui; Sun, Xinde

    2010-02-15

    Auditory experience during the postnatal critical period is essential for the normal maturation of auditory function. Previous studies have shown that rearing infant rat pups under conditions of continuous moderate-level noise delayed the emergence of adult-like topographic representational order and the refinement of response selectivity in the primary auditory cortex (A1) beyond normal developmental benchmarks and indefinitely blocked the closure of a brief, critical-period window. To gain insight into the molecular mechanisms of these physiological changes after noise rearing, we studied expression of the AMPA receptor subunit GluR2 and GABA(A) receptor subunit beta3 in the auditory cortex after noise rearing. Our results show that continuous moderate-level noise rearing during the early stages of development decreases the expression levels of GluR2 and GABA(A)beta3. Furthermore, noise rearing also induced a significant decrease in the level of GABA(A) receptors relative to AMPA receptors. However, in adult rats, noise rearing did not have significant effects on GluR2 and GABA(A)beta3 expression or the ratio between the two units. These changes could have a role in the cellular mechanisms involved in the delayed maturation of auditory receptive field structure and topographic organization of A1 after noise rearing. Copyright 2009 Wiley-Liss, Inc.

  1. Differential contribution of complement receptor C5aR in myeloid and non-myeloid cells in chronic ethanol-induced liver injury in mice.

    Science.gov (United States)

    McCullough, Rebecca L; McMullen, Megan R; Das, Dola; Roychowdhury, Sanjoy; Strainic, Michael G; Medof, M Edward; Nagy, Laura E

    2016-07-01

    Complement is implicated in the development of alcoholic liver disease. C3 and C5 contribute to ethanol-induced liver injury; however, the role of C5a receptor (C5aR) on myeloid and non-myeloid cells to progression of injury is not known. C57BL/6 (WT), global C5aR-/-, myeloid-specific C5aR-/-, and non-myeloid-specific C5aR-/- mice were fed a Lieber-DeCarli diet (32%kcal EtOH) for 25 days. Cultured hepatocytes were challenged with ethanol, TNFα, and C5a. Chronic ethanol feeding increased expression of pro-inflammatory mediators in livers of WT mice; this response was completely blunted in C5aR-/- mice. However, C5aR-/- mice were not protected from other measures of hepatocellular damage, including ethanol-induced increases in hepatic triglycerides, plasma alanine aminotransferase and hepatocyte apoptosis. CYP2E1 and 4-hydroxynonenal protein adducts were induced in WT and C5aR-/- mice. Myeloid-specific C5aR-/- mice were protected from ethanol-induced increases in hepatic TNFα, whereas non-myeloid-specific C5aR-/- displayed increased hepatocyte apoptosis and inflammation after chronic ethanol feeding. In cultured hepatocytes, cytotoxicity induced by challenge with ethanol and TNFα was completely eliminated by treatment with C5a in cells from WT, but not C5aR-/- mice. Further, treatment with C5a enhanced activation of pro-survival signal AKT in hepatocytes challenged with ethanol and TNFα. Taken together, these data reveal a differential role for C5aR during ethanol-induced liver inflammation and injury, with C5aR on myeloid cells contributing to ethanol-induced inflammatory cytokine expression, while non-myeloid C5aR protects hepatocytes from death after chronic ethanol feeding. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Curcumin-Protected PC12 Cells Against Glutamate-Induced Oxidative Toxicity

    OpenAIRE

    Chang, Chi-Huang; Chen, Hua-Xin; Yü, George; Peng, Chiung-Chi; Peng, Robert Y.

    2014-01-01

    Glutamate is a major excitatory neurotransmitter present in the central nervous system. The glutamate/cystine antiporter system xc– connects the antioxidant defense with neurotransmission and behaviour. Overactivation of ionotropic glutamate receptors induces neuronal death, a pathway called excitotoxicity. Glutamate-induced oxidative stress is a major contributor to neurodegenerative diseases including cerebral ischemia, Alzheimer’s and Huntington’s disease. Curcuma has a wide spectrum of bi...

  3. 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.

  4. Clearance of glutamate inside the synapse and beyond.

    Science.gov (United States)

    Bergles, D E; Diamond, J S; Jahr, C E

    1999-06-01

    The heated debate over the level of postsynaptic receptor occupancy by transmitter has not been extinguished - indeed, new evidence is fanning the flames. Recent experiments using two-photon microscopy suggest that the concentration of glutamate in the synaptic cleft does not attain levels previously suggested. In contrast, recordings from glial cells and studies of extrasynaptic receptor activation indicate that significant quantities of glutamate escape from the cleft following exocytosis. Determining the amount of glutamate efflux from the synaptic cleft and the distance it diffuses is critical to issues of synaptic specificity and the induction of synaptic plasticity.

  5. Systemic administration of monosodium glutamate elevates intramuscular glutamate levels and sensitizes rat masseter muscle afferent fibers.

    Science.gov (United States)

    Cairns, Brian E; Dong, Xudong; Mann, Mandeep K; Svensson, Peter; Sessle, Barry J; Arendt-Nielsen, Lars; McErlane, Keith M

    2007-11-01

    There is evidence that elevated tissue concentrations of glutamate may contribute to pain and sensitivity in certain musculoskeletal pain conditions. In the present study, the food additive monosodium glutamate (MSG) was injected intravenously into rats to determine whether it could significantly elevate interstitial concentrations of glutamate in the masseter muscle and whether MSG administration could excite and/or sensitize slowly conducting masseter afferent fibers through N-methyl-D-aspartate (NMDA) receptor activation. The interstitial concentration of glutamate after systemic injection of isotonic phosphate-buffered saline (control) or MSG (10 and 50mg/kg) was measured with a glutamate-selective biosensor. The pre-injection baseline interstitial concentration of glutamate in the rat masseter muscle was 24+/-11 microM. Peak interstitial concentration after injection of 50mg/kg MSG was 63+/-18 microM and remained elevated above baseline for approximately 18 min. In vivo single unit recording experiments were undertaken to assess the effect of MSG (50mg/kg) on masseter afferent fibers. Injection of MSG evoked a brief discharge in one afferent fiber, and significantly decreased ( approximately 25%) the average afferent mechanical threshold (n=10) during the first 5 min after injection of MSG. Intravenous injection of ketamine (1mg/kg), 5 min prior to MSG, prevented the MSG-induced decreases in the mechanical threshold of masseter afferent fibers. The present results indicate that a 2- to 3-fold elevation in interstitial glutamate levels in the masseter muscle is sufficient to excite and induce afferent mechanical sensitization through NMDA receptor activation. These findings suggest that modest elevations of interstitial glutamate concentration could alter musculoskeletal pain sensitivity in humans.

  6. Glutamate-mediated protection of crayfish glial cells from PDT-induced apoptosis

    Science.gov (United States)

    Rudkovskii, M. V.; Romanenko, N. P.; Berezhnaya, E. V.; Kovaleva, V. D.; Uzdensky, A. B.

    2011-03-01

    Photodynamic treatment that causes intense oxidative stress and kills cells is currently used in neurooncology. However, along with tumor it damages surrounding healthy neurons and glial cells. In order to study the possible role of glutamate-related signaling pathways in photodynamic injury of neurons and glia, we investigated photodynamic effect of alumophthalocyanine Photosens on isolated crayfish stretch receptor that consists of a single neuron surrounded by glial cells. The laser diode (670 nm, 0.4 W/cm2) was used for dye photoexcitation. Application of glutamate increased photodynamically induced necrosis of neurons and glial cells but significantly decreased glial apoptosis. The natural neuroglial mediator N-acetylaspartylglutamate, which releases glutamate after cleavage in the extracellular space by glutamate carboxypeptidase II, also inhibited photoinduced apoptosis. Inhibition of glutamate carboxypeptidase II, oppositely, enhanced apoptosis of glial cells. These data confirm the anti-apoptotic activity of glutamate. Application of NMDA or inhibition of NMDA receptors by MK801 did not influence photodynamic death of neurons and glial cells that indicated nonparticipation of NMDA receptors in these processes. Inhibition of metabotropic glutamate receptors by AP-3 decreased PDT-induced apoptosis. One can suggest that crayfish neurons naturally secrete NAAG, which being cleaved by GCOP produces glutamate. Glutamate prevents photoinduced apoptosis of glial cells possibly through metabotropic but not ionotropic glutamate receptors.

  7. MPA-capped CdTe quantum dots exposure causes neurotoxic effects in nematode Caenorhabditis elegans by affecting the transporters and receptors of glutamate, serotonin and dopamine at the genetic level, or by increasing ROS, or both

    Science.gov (United States)

    Wu, Tianshu; He, Keyu; Zhan, Qinglin; Ang, Shengjun; Ying, Jiali; Zhang, Shihan; Zhang, Ting; Xue, Yuying; Tang, Meng

    2015-12-01

    As quantum dots (QDs) are widely used in biomedical applications, the number of studies focusing on their biological properties is increasing. While several studies have attempted to evaluate the toxicity of QDs towards neural cells, the in vivo toxic effects on the nervous system and the molecular mechanisms are unclear. The aim of the present study was to investigate the neurotoxic effects and the underlying mechanisms of water-soluble cadmium telluride (CdTe) QDs capped with 3-mercaptopropionic acid (MPA) in Caenorhabditis elegans (C. elegans). Our results showed that exposure to MPA-capped CdTe QDs induced behavioral defects, including alterations to body bending, head thrashing, pharyngeal pumping and defecation intervals, as well as impaired learning and memory behavior plasticity, based on chemotaxis or thermotaxis, in a dose-, time- and size-dependent manner. Further investigations suggested that MPA-capped CdTe QDs exposure inhibited the transporters and receptors of glutamate, serotonin and dopamine in C. elegans at the genetic level within 24 h, while opposite results were observed after 72 h. Additionally, excessive reactive oxygen species (ROS) generation was observed in the CdTe QD-treated worms, which confirmed the common nanotoxicity mechanism of oxidative stress damage, and might overcome the increased gene expression of neurotransmitter transporters and receptors in C. elegans induced by long-term QD exposure, resulting in more severe behavioral impairments.

  8. 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.

  9. 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.

    Science.gov (United States)

    Tateishi, Akito; Coleman, Sarah K; Migita, Satoshi; Keinänen, Kari; Haruyama, Tetsuya

    2012-01-01

    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 Ca(2+) 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.

  10. A review of glutamate's role in traumatic brain injury mechanisms

    Science.gov (United States)

    Good, Cameron H.

    2013-05-01

    Glutamate is the primary excitatory neurotransmitter used by the central nervous system (CNS) for synaptic communication, and its extracellular concentration is tightly regulated by glutamate transporters located on nearby astrocytes. Both animal models and human clinical studies have demonstrated elevated glutamate levels immediately following a traumatic brain event, with the duration and severity of the rise corresponding to prognosis. This rise in extracellular glutamate likely results from a combination of excessive neurotransmitter release from damaged neurons and down regulation of uptake mechanisms in local astrocytes. The immediate results of a traumatic event can lead to necrotic tissue in severely injured regions, while prolonged increases in excitatory transmission can cause secondary excitotoxic injury through activation of delayed apoptotic pathways. Initial TBI animal studies utilized a variety of broad glutamate receptor antagonists to successfully combat secondary injury mechanisms, but unfortunately this same strategy has proven inconclusive in subsequent human trials due to deleterious side effects and heterogeneity of injuries. More recent treatment strategies have utilized specific glutamate receptor subunit antagonists in an effort to minimize side effects and have shown promising results. Future challenges will be detecting the concentration and kinetics of the glutamate rise following injury, determining which patient populations could benefit from antagonist treatment based on their extracellular glutamate concentrations and when drugs should be administered to maximize efficacy.

  11. Identification of single nucleotide polymorphisms of the human metabotropic glutamate receptor 1 gene and pharmacological characterization of a P993S variant

    OpenAIRE

    2009-01-01

    Abstract mGluR1 receptors are believed to play major roles in the pathophysiology of diseases such as anxiety and chronic pain and are being actively investigated as targets for drug development. Sequence polymorphisms can potentially influence the efficacy of drugs in patient populations and are therefore an important consideration in the drug development process. To identify DNA sequence variants of the mGluR1 receptor, comparative DNA sequencing was performed on DNA samples (n=1...

  12. Glutamate receptor antagonist infusions into the basolateral and medial amygdala reveal differential contributions to olfactory vs. context fear conditioning and expression

    OpenAIRE

    Walker, David L.; Paschall, Gayla Y.; Davis, Michael

    2005-01-01

    The basolateral amygdala's involvement in fear acquisition and expression to visual and auditory stimuli is well known. The involvement of the basolateral and other amygdala areas in fear acquisition and expression to stimuli of other modalities is less certain. We evaluated the contribution of the basolateral and medial amygdala to olfactory and to context fear and fear conditioning by infusing into these areas the NMDA receptor antagonist AP5, the AMPA/kainate receptor antagonist NBQX, or v...

  13. Deletion of the complement C5a receptor alleviates the severity of acute pneumococcal otitis media following influenza A virus infection in mice.

    Directory of Open Access Journals (Sweden)

    Hua Hua Tong

    Full Text Available There is considerable evidence that influenza A virus (IAV promotes adherence, colonization, and superinfection by S. pneumoniae (Spn and contributes to the pathogenesis of otitis media (OM. The complement system is a critical innate immune defense against both pathogens. To assess the role of the complement system in the host defense and the pathogenesis of acute pneumococcal OM following IAV infection, we employed a well-established transtympanically-induced mouse model of acute pneumococcal OM. We found that antecedent IAV infection enhanced the severity of acute pneumococcal OM. Mice deficient in complement C1qa (C1qa-/- or factor B (Bf -/- exhibited delayed viral and bacterial clearance from the middle ear and developed significant mucosal damage in the eustachian tube and middle ear. This indicates that both the classical and alternative complement pathways are critical for the oto-immune defense against acute pneumococcal OM following influenza infection. We also found that Spn increased complement activation following IAV infection. This was characterized by sustained increased levels of anaphylatoxins C3a and C5a in serum and middle ear lavage samples. In contrast, mice deficient in the complement C5a receptor (C5aR demonstrated enhanced bacterial clearance and reduced severity of OM. Our data support the concept that C5a-C5aR interactions play a significant role in the pathogenesis of acute pneumococcal OM following IAV infection. It is possible that targeting the C5a-C5aR axis might prove useful in attenuating acute pneumococcal OM in patients with influenza infection.

  14. Hepatitis C virus nonstructural protein 5A modulates the toll-like receptor-MyD88-dependent signaling pathway in macrophage cell lines.

    Science.gov (United States)

    Abe, Takayuki; Kaname, Yuuki; Hamamoto, Itsuki; Tsuda, Yoshimi; Wen, Xiaoyu; Taguwa, Shuhei; Moriishi, Kohji; Takeuchi, Osamu; Kawai, Taro; Kanto, Tatsuya; Hayashi, Norio; Akira, Shizuo; Matsuura, Yoshiharu

    2007-09-01

    Hepatitis C virus (HCV) infection induces a wide range of chronic liver injuries; however, the mechanism through which HCV evades the immune surveillance system remains obscure. Blood dendritic cells (DCs) play a pivotal role in the recognition of viral infection and the induction of innate and adaptive immune responses. Several reports suggest that HCV infection induces the dysfunction of DCs in patients with chronic hepatitis C. Toll-like receptor (TLR) has been shown to play various roles in many viral infections; however, the involvement of HCV proteins in the TLR signaling pathway has not yet been precisely elucidated. In this study, we established mouse macrophage cell lines stably expressing HCV proteins and determined the effect of HCV proteins on the TLR signaling pathways. Immune cells expressing NS3, NS3/4A, NS4B, or NS5A were found to inhibit the activation of the TLR2, TLR4, TLR7, and TLR9 signaling pathways. Various genotypes of NS5A bound to MyD88, a major adaptor molecule in TLR, inhibited the recruitment of interleukin-1 receptor-associated kinase 1 to MyD88, and impaired cytokine production in response to TLR ligands. Amino acid residues 240 to 280, previously identified as the interferon sensitivity-determining region (ISDR) in NS5A, interacted with the death domain of MyD88, and the expression of a mutant NS5A lacking the ISDR partially restored cytokine production. These results suggest that the expression of HCV proteins modulates the TLR signaling pathway in immune cells.

  15. Glutamate Transport: A New Bench to Bedside Mechanism for Treating Drug Abuse.

    Science.gov (United States)

    Spencer, Sade; Kalivas, Peter W

    2017-10-01

    Drug addiction has often been described as a "hijacking" of the brain circuits involved in learning and memory. Glutamate is the principal excitatory neurotransmitter in the brain, and its contribution to synaptic plasticity and learning processes is well established in animal models. Likewise, over the past 20 years the addiction field has ascribed a critical role for glutamatergic transmission in the development of addiction. Chronic drug use produces enduring neuroadaptations in corticostriatal projections that are believed to contribute to a maladaptive deficit in inhibitory control over behavior. Much of this research focuses on the role played by ionotropic glutamate receptors directly involved in long-term potentiation and depression or metabotropic receptors indirectly modulating synaptic plasticity. Importantly, the balance between glutamate release and clearance tightly regulates the patterned activation of these glutamate receptors, emphasizing an important role for glutamate transporters in maintaining extracellular glutamate levels. Five excitatory amino acid transporters participate in active glutamate reuptake. Recent evidence suggests that these glutamate transporters can be modulated by chronic drug use at a variety of levels. In this review, we synopsize the evidence and mechanisms associated with drug-induced dysregulation of glutamate transport. We then summarize the preclinical and clinical data suggesting that glutamate transporters offer an effective target for the treatment of drug addiction. In particular, we focus on the role that altered glutamate transporters have in causing drug cues and contexts to develop an intrusive quality that guides maladaptive drug seeking behaviors. © The Author 2017. Published by Oxford University Press on behalf of CINP.

  16. Glutamate release from platelets: exocytosis versus glutamate transporter reversal.

    Science.gov (United States)

    Kasatkina, Ludmila A; Borisova, Tatiana A

    2013-11-01

    Platelets express neuronal and glial glutamate transporters EAAT 1-3 in the plasma membrane and vesicular glutamate transporters VGLUT 1,2 in the membrane of secretory granules. This study is focused on the assessment of non-exocytotic glutamate release, that is, the unstimulated release, heteroexchange and glutamate transporter reversal in platelets. Using the glutamate dehydrogenase assay, the absence of unstimulated release of endogenous glutamate from platelets was demonstrated, even after inhibition of glutamate transporters and cytoplasmic enzyme glutamine synthetase by dl-threo-β-benzyloxyaspartate and methionine sulfoximine, respectively. Depolarization of the plasma membrane by exposure to elevated [K(+)] did not induce the release of glutamate from platelets that was shown using the glutamate dehydrogenase assay and radiolabeled l-[(14)C]glutamate. Glutamate efflux by means of heteroexchange with transportable inhibitor of glutamate transporters dl-threo-β-hydroxyaspartate (dl-THA) was not observed. Furthermore, the protonophore cyanide-p-trifluoromethoxyphenyl-hydrazon (FCCP) and inhibitor of V-type H(+)-ATPase bafilomycin A1 also failed to stimulate the release of glutamate from platelets. However, exocytotic release of glutamate from secretory granules in response to thrombin stimulation was not prevented by elevated [K(+)], dl-THA, FCCP and bafilomycin A1. In contrast to nerve terminals, platelets cannot release glutamate in a non-exocytotic manner. Heteroexchange, transporter-mediated and unstimulated release of glutamate are not inherent to platelets. Therefore, platelets may be used as a peripheral marker/model for the analysis of glutamate uptake by brain nerve terminals only (direct function of transporters), whereas the mechanisms of glutamate release are different in platelets and nerve terminals. Glutamate is released by platelets exclusively by means of exocytosis. Also, reverse function of vesicular glutamate transporters of platelets is

  17. Probing the Metabotropic Glutamate Receptor 5 (mGlu5) Positive Allosteric Modulator (PAM) Binding Pocket: Discovery of Point Mutations That Engender a “Molecular Switch” in PAM Pharmacology

    Science.gov (United States)

    Gregory, Karen J.; Nguyen, Elizabeth D.; Reiff, Sean D.; Squire, Emma F.; Stauffer, Shaun R.; Lindsley, Craig W.; Meiler, Jens

    2013-01-01

    Positive allosteric modulation of metabotropic glutamate receptor subtype 5 (mGlu5) is a promising novel approach for the treatment of schizophrenia and cognitive disorders. Allosteric binding sites are topographically distinct from the endogenous ligand (orthosteric) binding site, allowing for co-occupation of a single receptor with the endogenous ligand and an allosteric modulator. Negative allosteric modulators (NAMs) inhibit and positive allosteric modulators (PAMs) enhance the affinity and/or efficacy of the orthosteric agonist. The molecular determinants that govern mGlu5 modulator affinity versus cooperativity are not well understood. Focusing on the modulators based on the acetylene scaffold, we sought to determine the molecular interactions that contribute to PAM versus NAM pharmacology. Generation of a comparative model of the transmembrane-spanning region of mGlu5 served as a tool to predict and interpret the impact of mutations in this region. Application of an operational model of allosterism allowed for determination of PAM and NAM affinity estimates at receptor constructs that possessed no detectable radioligand binding as well as delineation of effects on affinity versus cooperativity. Novel mutations within the transmembrane domain (TM) regions were identified that had differential effects on acetylene PAMs versus 2-methyl-6-(phenylethynyl)-pyridine, a prototypical NAM. Three conserved amino acids (Y658, T780, and S808) and two nonconserved residues (P654 and A809) were identified as key determinants of PAM activity. Interestingly, we identified two point mutations in TMs 6 and 7 that, when mutated, engender a mode switch in the pharmacology of certain PAMs. PMID:23444015

  18. 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.

  19. The alpha/beta-adrenergic receptor blocker arotinolol activates the thermogenesis of brown adipose tissue in monosodium-L-glutamate-induced obese mice.

    Science.gov (United States)

    Yoshida, T; Sakane, N; Wakabayashi, Y; Yoshioka, K; Umekawa, T; Kondo, M

    1994-05-01

    We have found previously that arotinolol, an alpha/beta-adrenergic blocker, increases blood flow in brown adipose tissue (BAT) in a similar extent as BRL 26830A, a beta 3-adrenoceptor agonist. We tested the hypothesis that arotinolol activates thermogenesis in BAT, leading to weight loss in monosodium-L-glutamate-induced (MSG-induced) obese mice and saline-treated controls. Six weeks of standard animal feed (CE-2) containing arotinolol hydrochloride (350 mg/kg CE-2), which reduced mean blood pressure in MSG-treated mice, significantly increased the mitochondrial protein content in BAT, and activated the specific and total binding of guanosine-5'-diphosphate (GDP) in BAT mitochondria, leading to a reduction of obesity in both MSG- and saline-treated mice vs. the control groups fed with CE-2 diet alone. However, six weeks of CE-2 diet containing propranolol hydrochloride (525 mg/kg CE-2) a non-selective beta-blocker, markedly reduced the specific and total binding of GDP in BAT mitochondria, leading to weight gain in both MSG- and saline-treated mice. These findings support the hypothesis, that arotinolol activates BAT thermogenesis, leading to weight loss.

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