WorldWideScience

Sample records for metabotropic glutamate subtype-5

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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...

  9. 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

  10. 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.

  11. 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...

  12. 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

  13. 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.

  14. 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

  15. 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...

  16. 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 ...

  17. 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

  18. 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

  19. 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...

  20. 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

  1. 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...

  2. 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

  3. 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

  4. 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.

  5. 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...

  6. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. 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

  11. 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

  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. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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.)

  20. 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...

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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...

  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. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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....

  6. 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

  7. 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.

  8. [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.

  9. 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.

  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. 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

  12. 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...

  13. 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

  14. 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

  15. 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...

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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...

  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. 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.

  6. 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.

  7. 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.)

  8. 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...

  9. 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.

  10. 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...

  11. 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

  12. 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...

  13. (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)....

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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.

  4. 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

  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. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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...

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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).

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  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. 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

  19. 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

  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. 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.)

  4. 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.)

  5. 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

  6. 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

  7. 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

  8. 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.

  9. Relative contributions of presystemic and systemic peptidases to oral exposure of a novel metabotropic glutamate 2/3 receptor agonist (LY404039) after oral administration of prodrug pomaglumetad methionil (LY2140023).

    Science.gov (United States)

    Annes, William F; Long, Amanda; Witcher, Jennifer W; Ayan-Oshodi, Mosun A; Knadler, Mary Pat; Zhang, Wei; Mitchell, Malcolm I; Cornelissen, Karen; Hall, Stephen D

    2015-01-01

    Pomaglumetad methionil (LY2140023) is the prodrug of a novel metabotropic glutamate 2/3 receptor agonist (LY404039) being investigated for the treatment of schizophrenia. Using accelerator mass spectrometry (AMS) and an intravenous (i.v.) radiolabeled tracer approach, the absolute bioavailability of the prodrug and the extent of its conversion to active moiety (LY404039) were estimated at presystemic (intestinal/first pass) and systemic sites after simultaneous oral and i.v. dosing in healthy subjects. The mean absolute bioavailability of prodrug (80 mg oral) was 0.68. On the basis of these data and a previous radiolabeled mass balance study in which no prodrug was recovered in feces, we concluded that 0.32 of the dose is converted to active drug in the intestinal tract. The fraction of prodrug converted to active moiety was approximately 1, indicating complete conversion of the prodrug that reaches the systemic circulation to the active moiety. Prodrug (80 mg oral and 100 μg i.v.) and active moiety (100 μg i.v.) were well tolerated in healthy subjects. Thus, the absolute bioavailability of prodrug LY2140023 and the fraction converted presystemically and systemically to active moiety LY404039 were estimated simultaneously using radiolabeled tracer microdosing and AMS. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  10. 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...

  11. Positive or negative allosteric modulation of metabotropic glutamate receptor 5 (mGluR5 does not alter expression of behavioral sensitization to methamphetamine [v1; ref status: indexed, http://f1000r.es/o0

    Directory of Open Access Journals (Sweden)

    Peter R Kufahl

    2013-03-01

    Full Text Available We investigated the role of metabotropic glutamate receptor type 5 (mGluR5 in methamphetamine-induced behavioral sensitization. The mGluR5 positive allosteric modulator (3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl benzamide (CDPPB and negative allosteric modulator fenobam were tested in separate experiments. Sprague-Dawley rats were repeatedly injected with 1 mg/kg methamphetamine or saline, and then given a locomotor challenge test using a dose of 0.5 mg/kg methamphetamine. Prior to the challenge test session, rats were injected with CDPPB, fenobam, or a vehicle.  Doses from previous studies showed reduced drug-conditioned behavior; however in this study neither CDPPB nor fenobam pretreatment resulted in an altered expression of behavioral sensitization, indicating a lack of mGluR5 involvement in sensitized methamphetamine-induced locomotion. Additionally, the high dose (30 mg/kg of fenobam resulted in decreased methamphetamine-induced locomotion in rats regardless of drug exposure history, which suggests evidence of nonspecific behavioral inhibition.

  12. Metabotropic glutamate receptor-5 and protein kinase C-epsilon increase in dorsal root ganglion neurons and spinal glial activation in an adolescent rat model of painful neck injury.

    Science.gov (United States)

    Weisshaar, Christine L; Dong, Ling; Bowman, Alex S; Perez, Federico M; Guarino, Benjamin B; Sweitzer, Sarah M; Winkelstein, Beth A

    2010-12-01

    There is growing evidence that neck pain is common in adolescence and is a risk factor for the development of chronic neck pain in adulthood. The cervical facet joint and its capsular ligament is a common source of pain in the neck in adults, but its role in adolescent pain remains unknown. The aim of this study was to define the biomechanics, behavioral sensitivity, and indicators of neuronal and glial activation in an adolescent model of mechanical facet joint injury. A bilateral C6-C7 facet joint distraction was imposed in an adolescent rat and biomechanical metrics were measured during injury. Following injury, forepaw mechanical hyperalgesia was measured, and protein kinase C-epsilon (PKCɛ) and metabotropic glutamate receptor-5 (mGluR5) expression in the dorsal root ganglion and markers of spinal glial activation were assessed. Joint distraction induced significant mechanical hyperalgesia during the 7 days post-injury (p capsule during injury were 32.8 ± 12.9%, which were consistent with the strains associated with comparable degrees of hypersensitivity in the adult rat. These results suggest that adolescents may have a lower tissue tolerance to induce pain and associated nociceptive response than do adults.

  13. Reduced excitatory amino acid transporter 1 and metabotropic glutamate receptor 5 expression in the cerebellum of fragile X mental retardation gene 1 premutation carriers with fragile X-associated tremor/ataxia syndrome.

    Science.gov (United States)

    Pretto, Dalyir I; Kumar, Madhur; Cao, Zhengyu; Cunningham, Christopher L; Durbin-Johnson, Blythe; Qi, Lihong; Berman, Robert; Noctor, Stephen C; Hagerman, Randi J; Pessah, Isaac N; Tassone, Flora

    2014-05-01

    A premutation (PM) expansion (55-200 CGG) in the fragile X mental retardation gene 1 causes elevated messenger RNA and reduced fragile X mental retardation gene 1 protein. Young PM carriers can develop characteristic physical features and mild cognitive disabilities. In addition, individuals with PM, particularly male carriers, are at high risk to develop fragile X-associated tremor/ataxia syndrome (FXTAS) with aging. Human postmortem FXTAS brains show extensive white matter disease in the cerebellum and the presence of intranuclear inclusions throughout the brain, although their etiologic significance is unknown. In the current work, expression levels of the metabotropic glutamate (Glu) receptor 5 and the Glu transporter excitatory amino acid transporter 1, examined by reverse transcription polymerase chain reaction and western blot analyses, were found to be reduced in the postmortem cerebellum of PM carriers with FXTAS compared with age matched controls, with higher CGG repeat number having greater reductions in both proteins. These data suggests a dysregulation of Glu signaling in PM carriers, which would likely contribute to the development and severity of FXTAS. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Learning and memory deficits consequent to reduction of the fragile X mental retardation protein result from metabotropic glutamate receptor-mediated inhibition of cAMP signaling in Drosophila.

    Science.gov (United States)

    Kanellopoulos, Alexandros K; Semelidou, Ourania; Kotini, Andriana G; Anezaki, Maria; Skoulakis, Efthimios M C

    2012-09-19

    Loss of the RNA-binding fragile X protein [fragile X mental retardation protein (FMRP)] results in a spectrum of cognitive deficits, the fragile X syndrome (FXS), while aging individuals with decreased protein levels present with a subset of these symptoms and tremor. The broad range of behavioral deficits likely reflects the ubiquitous distribution and multiple functions of the protein. FMRP loss is expected to affect multiple neuronal proteins and intracellular signaling pathways, whose identity and interactions are essential in understanding and ameliorating FXS symptoms. We used heterozygous mutants and targeted RNA interference-mediated abrogation in Drosophila to uncover molecular pathways affected by FMRP reduction. We present evidence that FMRP loss results in excess metabotropic glutamate receptor (mGluR) activity, attributable at least in part to elevation of the protein in affected neurons. Using high-resolution behavioral, genetic, and biochemical analyses, we present evidence that excess mGluR upon FMRP attenuation is linked to the cAMP decrement reported in patients and models, and underlies olfactory associative learning and memory deficits. Furthermore, our data indicate positive transcriptional regulation of the fly fmr1 gene by cAMP, via protein kinase A, likely through the transcription factor CREB. Because the human Fmr1 gene also contains CREB binding sites, the interaction of mGluR excess and cAMP signaling defects we present suggests novel combinatorial pharmaceutical approaches to symptom amelioration upon FMRP attenuation.

  15. Pharmacology of (S)-homoquisqualic acid and (S)-2-amino-5-phosphonopentanoic acid [(S)-AP5] at cloned metabotropic glutamate receptors

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Krogsgaard-Larsen, P

    1998-01-01

    1 In this study we have determined the pharmacological profile of (S)-quisqualic acid, (S)-2-amino-4-phosphonobutyric acid ((S)-AP4) and their higher homologues (S)-homoquisqualic acid, (S)-2-amino-5-phosphonopentanoic acid ((S)-AP5), respectively, and (R)-AP5 at subtypes of metabotropic (S...... competitive antagonism at mGlu1 (KB = 184 microM) and full agonism at mGlu5 (EC50 = 36 microM) and mGlu2 (EC50 = 23 microM), but was inactive at mGlu4. 4 (S)-AP4 was a potent and selective mGlu4 agonist (EC50 = 0.91 microM) being inactive at mGlu1, mGlu2 and mGlu5 both as agonist and antagonist. 5 (S)-AP5...... displayed very weak agonist activity at mGlu4. At the mGlu2 receptor subtype (S)-AP5 acted as a competitive antagonist (KB = 205 microM), whereas the compound was inactive at mGlu, and mGlu5. (R)-AP5 was inactive at all mGlu receptor subtypes tested both as agonist and antagonist. 6 These studies...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. The Metabotropic Glutamate 2/3 Receptor Agonist LY379268 Blocked Nicotine-Induced Increases in Nucleus Accumbens Shell Dopamine only in the Presence of a Nicotine-Associated Context in Rats

    Science.gov (United States)

    D'Souza, Manoranjan S; Liechti, Matthias E; Ramirez-Niño, Ana M; Kuczenski, Ronald; Markou, Athina

    2011-01-01

    The metabotropic glutamate 2/3 (mGlu2/3) receptor agonist LY379268 ([−]-2-oxa-4-aminobicyclo [3.1.0] hexane-4,6-dicarboxylate) attenuates both nicotine self-administration and cue-induced nicotine seeking in rats. In this study, the effects of LY379268 (1 mg/kg) or saline pretreatment on nicotine-induced increases in nucleus accumbens (NAcc) shell dopamine were evaluated using in vivo microdialysis under different experimental conditions: (i) nicotine (0.4 mg/kg, base) was experimenter-administered subcutaneously to nicotine-naïve rats; (ii) nicotine was experimenter-administered either subcutaneously (0.4 mg/kg) or by a single experimenter-administered infusion (0.06 mg/kg, base) in rats with a history of nicotine self-administration (nicotine experienced) in the absence of a nicotine-associated context (ie, context and cues associated with nicotine self-administration); (iii) nicotine (0.06 mg/kg) was self-administered or experimenter-administered in nicotine-experienced rats in the presence of a nicotine-associated context. In saline-pretreated nicotine-naïve and nicotine-experienced rats, nicotine increased NAcc shell dopamine regardless of the context used for testing. Interestingly, LY379268 pretreatment blocked nicotine-induced increases in NAcc shell dopamine in nicotine-experienced rats only when tested in the presence of a nicotine-associated context. LY379268 did not block nicotine-induced increases in NAcc shell dopamine in nicotine-naïve or -experienced rats tested in the absence of a nicotine-associated context. These intriguing findings suggest that activation of mGlu2/3 receptors negatively modulates the combined effects of nicotine and nicotine-associated contexts/cues on NAcc dopamine. Thus, these data highlight a critical role for mGlu2/3 receptors in context/cue-induced drug-seeking behavior and suggest a neurochemical mechanism by which mGlu2/3 receptor agonists may promote smoking cessation by preventing relapse induced by the

  1. Chronic, systemic treatment with a metabotropic glutamate receptor 5 antagonist produces anxiolytic-like effects and reverses abnormal firing activity of projection neurons in the basolateral nucleus of the amygdala in rats with bilateral 6-OHDA lesions.

    Science.gov (United States)

    Chen, Li; Liu, Jian; Ali, Umar; Gui, Zhen Hua; Hou, Chen; Fan, Ling Ling; Wang, Yong; Wang, Tao

    2011-02-28

    Although 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective metabotropic glutamate receptor 5 antagonist, improves the motor symptoms of Parkinson's disease (PD), the effects of MPEP on the psychiatric symptom of PD and the mechanism involved are still unclear. In the present study, we examined the effects of MPEP in anxiolytic-like behavior and firing activity of projection neurons in the basolateral nucleus of the amygdala (BLA) in rats with 6-hydroxydopamine (6-OHDA) injected bilaterally into dorsal striatum. Rats were divided into three groups, sham-operated group, 6-OHDA lesion with vehicle treatment group and 6-OHDA lesion with MPEP treatment group. Injection of 6-OHDA (10.5 μg) into the dorsal striatum produced 31.5% loss of tyrosine hydroxylase immunoreactive (TH-ir) neurons in the SNpc. The 6-OHDA-lesioned rats showed anxiety behavior and the firing rate of BLA projection neurons decreased significantly compared with sham-operated rats, and no difference was found in the firing pattern of these neurons. Whereas chronic, systemic treatment of MPEP (3 mg/kg/day, i.p.; 14 days) attenuated loss of TH-ir neurons, produced anxiolytic-like effect and normalized the abnormal firing rate of projection neurons of the BLA in rats with the bilateral lesions. Systemic administration of cumulative apomorphine (10-160 μg/kg, i.v.) inhibited the firing rate of BLA projection neurons in sham-operated, 6-OHDA lesion with vehicle-treated and MPEP-treated rats, but the 6-OHDA lesion decreased the response of BLA projection neurons to apomorphine stimulation, while MPEP reversed the reactivity of these neurons. These data demonstrate that the partial lesion of the nigrostriatal pathway causes anxiety symptom and decreases firing rate of BLA projection neurons in the rat. Furthermore, chronic, systemic MPEP treatment has the neuroprotective and anxiolytic-like effects, and reverses the abnormal firing rate of BLA projection neurons, suggesting that MPEP has important

  2. 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.

  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. CNS syndromes associated with antibodies against metabotropic receptors.

    Science.gov (United States)

    Lancaster, Eric

    2017-06-01

    Autoantibodies to Central nervous system (CNS) metabotropic receptors are associated with a growing family of autoimmune brain diseases, including encephalitis, basal ganglia encephalitis, Ophelia syndrome, and cerebellitis. The purpose of this review is to summarize the state of knowledge regarding the target receptors, the neurological autoimmune disorders, and the pathogenic mechanisms. Antibodies to the γ-aminobutyric acid B receptor are associate with limbic encephalitis and severe seizures, often with small cell lung cancers. Metabotropic glutamate receptor 5 (mGluR5) antibodies associate with Ophelia syndrome, a relatively mild form of encephalitis linked to Hodgkin lymphoma. mGluR1 antibodies associate with a form of cerebellar degeneration, and also Hodgkin lymphoma. Antibodies to Homer 3, a protein associated with mGluR1, have also been reported in two patients with cerebellar syndromes. Dopamine-2 receptor antibodies have been reported by one group in children with basal ganglia encephalitis and other disorders. CNS metabotropic receptor antibodies may exert direct inhibitory effects on their target receptors, but the evidence is more limited than with autoantibodies to ionotropic glutamate receptors. In the future, improved recognition of these patients may lead to better outcomes. Understanding the molecular mechanisms of the diseases may uncover novel treatment strategies.

  5. Glutamate affects the production of epoxyeicosanoids within the brain: The up-regulation of brain CYP2J through the MAPK-CREB signaling pathway.

    Science.gov (United States)

    Liu, Mingzhou; Zhu, Quanfei; Wu, Jinhua; Yu, Xuming; Hu, Mingbai; Xie, Xianfei; Yang, Zheqiong; Yang, Jing; Feng, Yu-Qi; Yue, Jiang

    2017-04-15

    Glutamate is the major excitatory neurotransmitter in the brain, and chronic glutamate excitotoxicity has been thought to be involved in numerous neurodegenerative diseases. We investigated the effects of glutamate at concentrations lower than the usual extrasynaptic concentrations on the production of epoxyeicosanoids mediated by brain CYP2J. Glutamate increased CYP2J2 mRNA levels in astrocytes in a dose-dependent manner, while an antagonist of the metabotropic glutamate receptor subtype 5 (mGlu5 receptor) attenuated the glutamate-induced increases in CYP2J2 levels by glutamate. Glutamate increased the binding of cAMP response element-binding protein (CREB) with the CYP2J2 promoter, and the inhibition of the MAPK signaling pathway (ERK1/2, p38, and JNK) decreased the binding of CREB with the CYP2J2 promoter following the glutamate treatment. CREB activated the CYP2J2 promoter located at -1522 to -1317bp, and CREB overexpression significantly increased CYP2J2 mRNA levels. The CYP2J2 and mGlu5 mRNA levels were higher in the frontal cortex, hippocampus, cerebellum, and brainstem in adult rats that received a subcutaneous injection of monosodium l-glutamate at 1, 3, 5, and 7days of age. The data from the partial least-squares-discriminant analysis showed the epoxyeicosanoid profile of the hippocampus from the cerebellum, brain stem, and frontal cortex. The sum of the epoxyeicosatrienoic acids (EETs) and dihydroxyeicosatrienoic acids (DHETs) was increased by 1.16-fold, 1.18-fold, and 1.19-fold in the frontal cortex, cerebellum, and brain stem, respectively, in rats treated with monosodium l-glutamate compared with the control group. The results suggest that brain CYP2J levels and CYP2J-mediated epoxyeicosanoid production can be regulated by extrasynaptic glutamate. The glutamate receptors expressed in astrocytes may mediate the regulation of drug-metabolizing enzymes and the metabolome of endogenous substances by glutamate. Copyright © 2017 Elsevier B.V. All rights

  6. 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

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. Inhibitory mechanism of l-glutamic acid on spawning of the starfish Patiria (Asterina) pectinifera.

    Science.gov (United States)

    Mita, Masatoshi

    2017-03-01

    l-Glutamic acid was previously identified as an inhibitor of spawning in the starfish Patiria (Asterina) pectinifera; this study examined how l-glutamic acid works. Oocyte release from ovaries of P. pectinifera occurred after germinal vesicle breakdown (GVBD) and follicular envelope breakdown (FEBD) when gonads were incubated ex vivo with either relaxin-like gonad-stimulating peptide (RGP) or 1-methyladenine (1-MeAde). l-Glutamic acid blocked this spawning phenotype, causing the mature oocytes to remain within the ovaries. Neither RGP-induced 1-MeAde production in ovarian follicle cells nor 1-MeAde-induced GVBD and FEBD was affected by l-glutamic acid. l-Glutamic acid may act through metabotropic receptors in the ovaries to inhibit spawning, as l-(+)-2-amino-4-phosphonobutyric acid, an agonist for metabotropic glutamate receptors, also inhibited spawning induced by 1-MeAde. Application of acetylcholine (ACH) to ovaries under inhibitory conditions with l-glutamic acid, however, brought about spawning, possibly by inducing contraction of the ovarian wall to discharge mature oocytes from the ovaries concurrently with GVBD and FEBD. Thus, l-glutamic acid may inhibit ACH secretion from gonadal nerve cells in the ovary. Mol. Reprod. Dev. 84: 246-256, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

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

  14. Protective effect of naringenin on glutamate-induced neurotoxicity in cultured hippocampal cells

    Directory of Open Access Journals (Sweden)

    Xu Xiao-Hui

    2015-01-01

    Full Text Available Monosodium glutamate induces excitotoxicity in the central nervous system through hyperactivation of both ionotropic and metabotropic glutamate receptors, which leads to neuronal cell death. In this study, we investigated the neuroprotective effects of naringenin on excitotoxicity induced by glutamate in primary hippocampal neurons of neonatal mice. The expression levels of apoptosis-inducing proteins and as well as ischemic factors were observed by Western blot analysis. Immunocytochemistry and morphometric analysis of hippocampal cells with or without glutamate and naringenin treatment were performed. We observed that naringenin regulated Erk1/2 and Akt phosphorylation and reduced the demise of dendrites due to glutamate exposure in cultured hippocampal neurons. Furthermore, naringenin induced the brain-derived neurotrophic factor and other neuroprotective cytokines, and markedly improved the survival rates of the neurons 24 h following glutamate exposure. The observed results suggest that the naturally occurring bioflavonoid (naringenin exerts neuroprotective effects via highly specific molecular targets in neurons.

  15. Glutamate neurotransmission is affected in prenatally stressed offspring

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  16. Glutamate mediated astrocytic filtering of neuronal activity.

    Directory of Open Access Journals (Sweden)

    Gilad Wallach

    2014-12-01

    Full Text Available Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity.

  17. Glutamate Mediated Astrocytic Filtering of Neuronal Activity

    Science.gov (United States)

    Herzog, Nitzan; De Pittà, Maurizio; Jacob, Eshel Ben; Berry, Hugues; Hanein, Yael

    2014-01-01

    Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity. PMID:25521344

  18. 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...

  19. 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.

  20. The involvement of glutamate in the pathophysiology of depression.

    Science.gov (United States)

    Palucha, A; Pilc, A

    2005-05-01

    In spite of more than 40 years of thorough studies, conventional antidepressants still have many limitations that hinder the effective treatment of depression. It seems that a breakthrough in the therapy of depression will require going beyond a monoamine-based theory of depression. Converging lines of evidence indicate that the glutamatergic system might be a promising target for a novel antidepressant therapy. Both ionotropic glutamate receptor ligands (functional NMDA receptor antagonists and AMPA receptor potentiators) and compounds acting at metabotropic glutamate receptors (mGluRs; group I mGluR antagonists, group II antagonists and group III agonists) produce antidepressant-like activity in several preclinical and some clinical studies. In this review, current knowledge and crucial hypotheses concerning the role of glutamate in the pathophysiology of depression are discussed. 2005 Prous Science. All rights reserved

  1. 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.

  2. Glutamate released spontaneously from astrocytes sets the threshold for synaptic plasticity.

    Science.gov (United States)

    Bonansco, Christian; Couve, Alejandro; Perea, Gertrudis; Ferradas, Carla Á; Roncagliolo, Manuel; Fuenzalida, Marco

    2011-04-01

    Astrocytes exhibit spontaneous calcium oscillations that could induce the release of glutamate as gliotransmitter in rat hippocampal slices. However, it is unknown whether this spontaneous release of astrocytic glutamate may contribute to determining the basal neurotransmitter release probability in central synapses. Using whole-cell recordings and Ca(2+) imaging, we investigated the effects of the spontaneous astrocytic activity on neurotransmission and synaptic plasticity at CA3-CA1 hippocampal synapses. We show here that the metabolic gliotoxin fluorocitrate (FC) reduces the amplitude of evoked excitatory postsynaptic currents and increases the paired-pulse facilitation, mainly due to the reduction of the neurotransmitter release probability and the synaptic potency. FC also decreased intracellular Ca(2+) signalling and Ca(2+) -dependent glutamate release from astrocytes. The addition of glutamine rescued the effects of FC over the synaptic potency; however, the probability of neurotransmitter release remained diminished. The blockage of group I metabotropic glutamate receptors mimicked the effects of FC on the frequency of miniature synaptic responses. In the presence of FC, the Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N ',N '-tetra-acetate or group I metabotropic glutamate receptor antagonists, the excitatory postsynaptic current potentiation induced by the spike-timing-dependent plasticity protocol was blocked, and it was rescued by delivering a stronger spike-timing-dependent plasticity protocol. Taken together, these results suggest that spontaneous glutamate release from astrocytes contributes to setting the basal probability of neurotransmitter release via metabotropic glutamate receptor activation, which could be operating as a gain control mechanism that regulates the threshold of long-term potentiation. Therefore, endogenous astrocyte activity provides a novel non-neuronal mechanism that could be critical for transferring information in

  3. 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...

  4. 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....

  5. Regional regulation of glutamate signaling during cuprizone-induced demyelination in the brain.

    Science.gov (United States)

    Azami Tameh, Abolfazl; Clarner, Tim; Beyer, Cordian; Atlasi, Mohammad Ali; Hassanzadeh, Gholamreza; Naderian, Homayoun

    2013-10-01

    Glutamate excitotoxicity is associated with a wide range of neurodegenerative disorders and also seems to be involved in the pathology of demyelinating disorders such as multiple sclerosis (MS). Cuprizone-induced toxic demyelination shows clear characteristics of MS such as demyelination and axonal damage without the involvement of the innate immune system. In this study, we have evaluated glutamate signaling during cuprizone-induced demyelination in the white and gray matter of mouse brain by studying the expression of ionotropic and metabotropic glutamate-receptors and -transporters by Affymetrix gene array analysis, followed by real-time PCR and western blot analysis. Cellular localization of glutamate transporters was investigated by fluorescence double-labeling experiments. Comparing white and gray matter areas, the expression of glutamate receptors was region-specific. Among NMDA receptor subunits, NR2A was up-regulated in the demyelinated corpus callosum (CC), whereas the metabotropic glutamate receptor mGluR2 was down-regulated in demyelinated gray matter. Glutamate-aspartate transporter (GLAST) co-localizing with GFAP(+) astrocytes was increased in both demyelinated CC and telencephalic cortex, whereas Slc1a4 transporter was up-regulated only in CC. Our data indicate that cuprizone treatment affects glutamate-receptors and -transporters differently in gray and white matter brain areas revealing particularly regulation of GLAST and Slc1a4 compared with other genes. This might have an important influence on brain-region selective sensitivity to neurotoxic compounds and the progression of demyelination as has been reported for MS and other demyelinating neurological diseases. Copyright © 2013 Elsevier GmbH. All rights reserved.

  6. Inflammation, Glutamate, and Glia: A Trio of Trouble in Mood Disorders.

    Science.gov (United States)

    Haroon, Ebrahim; Miller, Andrew H; Sanacora, Gerard

    2017-01-01

    Increasing data indicate that inflammation and alterations in glutamate neurotransmission are two novel pathways to pathophysiology in mood disorders. The primary goal of this review is to illustrate how these two pathways may converge at the level of the glia to contribute to neuropsychiatric disease. We propose that a combination of failed clearance and exaggerated release of glutamate by glial cells during immune activation leads to glutamate increases and promotes aberrant extrasynaptic signaling through ionotropic and metabotropic glutamate receptors, ultimately resulting in synaptic dysfunction and loss. Furthermore, glutamate diffusion outside the synapse can lead to the loss of synaptic fidelity and specificity of neurotransmission, contributing to circuit dysfunction and behavioral pathology. This review examines the fundamental role of glia in the regulation of glutamate, followed by a description of the impact of inflammation on glial glutamate regulation at the cellular, molecular, and metabolic level. In addition, the role of these effects of inflammation on glia and glutamate in mood disorders will be discussed along with their translational implications.

  7. Inflammation, Glutamate, and Glia: A Trio of Trouble in Mood Disorders

    Science.gov (United States)

    Haroon, Ebrahim; Miller, Andrew H; Sanacora, Gerard

    2017-01-01

    Increasing data indicate that inflammation and alterations in glutamate neurotransmission are two novel pathways to pathophysiology in mood disorders. The primary goal of this review is to illustrate how these two pathways may converge at the level of the glia to contribute to neuropsychiatric disease. We propose that a combination of failed clearance and exaggerated release of glutamate by glial cells during immune activation leads to glutamate increases and promotes aberrant extrasynaptic signaling through ionotropic and metabotropic glutamate receptors, ultimately resulting in synaptic dysfunction and loss. Furthermore, glutamate diffusion outside the synapse can lead to the loss of synaptic fidelity and specificity of neurotransmission, contributing to circuit dysfunction and behavioral pathology. This review examines the fundamental role of glia in the regulation of glutamate, followed by a description of the impact of inflammation on glial glutamate regulation at the cellular, molecular, and metabolic level. In addition, the role of these effects of inflammation on glia and glutamate in mood disorders will be discussed along with their translational implications. PMID:27629368

  8. 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....

  9. Asymetric functioning of dimeric metabotropic glutamate receptors disclosed by positive allosteric modulators

    Czech Academy of Sciences Publication Activity Database

    Goudet, C.; Kniazeff, J.; Hlaváčková, Veronika; Malhaire, F.; Maurel, D.; Acher, F.; Blahoš, Jaroslav; Prézeau, L.; Pin, J.-P.

    2005-01-01

    Roč. 280, č. 26 (2005), s. 24380-24385 ISSN 0021-9258 R&D Projects: GA ČR GA301/03/1183; GA AV ČR KJB5039402; GA ČR(CZ) GD309/03/H095 Institutional research plan: CEZ:AV0Z50390512 Keywords : GPCR dimer Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 5.854, year: 2005

  10. The Role of Metabotropic Glutamate Receptor 5 in Learning and Memory Processes

    DEFF Research Database (Denmark)

    Simonyi, Agnes; Schachtman, Todd; Christoffersen, Gert Rene Juul

    2005-01-01

    signaling mechanisms have also been revealed. MGluR5s are mainly localized postsynaptically on the periphery of synap-ses. MGluR5s have been implicated in synaptic plasticity and learning and memory. The development of the highly potent and selective mGluR5 antagonist 2-methyl-6-(phenylethynyl...... and radial arm maze performance as well as in contextual fear conditioning, but not in cue conditioning. This review summarizes recent advances reported on mGluR5 function in synaptic plasticity, learning and memory. The current development of positive and negative allosteric modulators of mGluR5...... of the effects of MPEP in various behavioral paradigms have concluded that mGluR5s play a critical role in aversive learning tasks and in hippocampal-dependent spatial learning. However, MPEP has proved ineffective in certain other learning tasks. MGluR5 knockout mice have shown impairments in water maze...

  11. Metabotropic glutamate receptor 5 as drug target for Fragile X syndrome.

    Science.gov (United States)

    Scharf, Sebastian H; Jaeschke, Georg; Wettstein, Joseph G; Lindemann, Lothar

    2015-02-01

    Fragile X syndrome (FXS) is the most common monogenic form of inherited mental retardation caused by a trinucleotid repeat expansion and transcriptional shutdown of the FMR1 gene. FXS patients present a complex and often severe neuropsychiatric phenotype yet have mild somatic symptoms, normal life expectancies, and no indications of neurodegeneration. The therapeutic potential of mGlu5 inhibitors was proposed in the 'mGluR theory of FXS' based on early insights into the molecular pathophysiology of FXS. Studies in Fragile X mental retardation 1 (Fmr1) knock-out mice, a widely used disease model, demonstrated that mGlu5 inhibitors can correct a broad range of disease-related phenotypes. Recent clinical trials, however, with two different mGlu5 inhibitors (basimglurant and mavoglurant) showed no therapeutic benefit in FXS patients for reasons as yet unclear. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. 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

  13. 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...

  14. Role of transient receptor potential melastatin-like subtype 5 channel in insulin secretion from rat β-cells.

    Science.gov (United States)

    Krishnan, Kalaiselvan; Ma, Zuheng; Björklund, Anneli; Islam, Md Shahidul

    2014-05-01

    Several studies have reported that the transient receptor potential melastatin-like subtype 5 (TRPM5) channel, a Ca(2+)-activated monovalent cation channel, is involved in the stimulus-secretion coupling in the mouse pancreatic β-cells. We have studied the role of the TRPM5 channel in regulating insulin secretion and cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) in the rat β-cells by using triphenylphosphine oxide, a selective inhibitor of the channel. Insulin secretion from islets from Sprague-Dawley rats was measured in batch incubations. Cytoplasmic free Ca(2+) concentration was measured from single β-cells by fura-2-based microfluorometry. Triphenylphosphine oxide did not alter insulin secretion and [Ca(2+)](i) response triggered by KCl or fructose. It inhibited insulin secretion in response to glucose, L-arginine, and glucagon-like peptide 1. It also inhibited glucose-induced insulin secretion by mechanisms that are independent of the adenosine triphosphate-sensitive potassium channels and [Ca(2+)](i) increase. Our results suggest that in the rat islets, TRPM5 is involved in mediating insulin secretion by glucose and l-arginine and in potentiating the glucose-induced insulin secretion by glucagon-like peptide 1.

  15. Glutamic Acid as Enhancer of Protein Synthesis Kinetics in Hepatocytes from Old Rats.

    Science.gov (United States)

    Brodsky, V Y; Malchenko, L A; Butorina, N N; Lazarev Konchenko, D S; Zvezdina, N D; Dubovaya, T K

    2017-08-01

    Dense cultures of hepatocytes from old rats (~2 years old, body weight 530-610 g) are different from similar cultures of hepatocytes from young rats by the low amplitude of protein synthesis rhythm. Addition of glutamic acid (0.2, 0.4, or 0.6 mg/ml) into the culture medium with hepatocytes of old rats resulted in increase in the oscillation amplitudes of the protein synthesis rhythm to the level of young rats. A similar action of glutamic acid on the protein synthesis kinetics was observed in vivo after feeding old rats with glutamic acid. Inhibition of metabotropic receptors of glutamic acid with α-methyl-4-carboxyphenylglycine (0.01 mg/ml) abolished the effect of glutamic acid. The amplitude of oscillation of the protein synthesis rhythm in a cell population characterizes synchronization of individual oscillations caused by direct cell-cell communications. Hence, glutamic acid, acting as a receptor-dependent transmitter, enhanced direct cell-cell communications of hepatocytes that were decreased with aging. As differentiated from other known membrane signaling factors (gangliosides, norepinephrine, serotonin, dopamine), glutamic acid can penetrate into the brain and thus influence the communications and protein synthesis kinetics that are disturbed with aging not only in hepatocytes, but also in neurons.

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

    Science.gov (United States)

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

    2003-01-01

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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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...

  2. [Preparation of leucine-methyl glutamate-glutamic acid copolymers].

    Science.gov (United States)

    Pan, S; Shi, F; Huang, L; Zhou, Q; Lin, Z; Yi, W

    1997-06-01

    The method for preparing leucine-methyl glutamate-glutamic acid copolymer was studied. In the first place benzyl glutamate and methyl glutamate were synthesized respectively. Then N-carboxy anhydrides (NCA) of leucine, benzyl glutamate or methyl glutamate were prepared in a closed container by phosgene-toluene solution method. After copolymerization the copolymers were debenzylated and demethylated by anhydrous hydrogen bromide. The free carboxyl group mole content in side chains of the copolymer was controlled by various standing periods following bubbling HBr. Analysis of infrared spectrogram and ultraviolet asorbance of copolymers indicated that this procedure resulted in the loss of almost all benzyl groups and some methyl groups.

  3. The glutamate aspartate transporter (GLAST) mediates L-glutamate-stimulated ascorbate-release via swelling-activated anion channels in cultured neonatal rodent astrocytes.

    Science.gov (United States)

    Lane, Darius J R; Lawen, Alfons

    2013-03-01

    Vitamin C (ascorbate) plays important neuroprotective and neuromodulatory roles in the mammalian brain. Astrocytes are crucially involved in brain ascorbate homeostasis and may assist in regenerating extracellular ascorbate from its oxidised forms. Ascorbate accumulated by astrocytes can be released rapidly by a process that is stimulated by the excitatory amino acid, L-glutamate. This process is thought to be neuroprotective against excitotoxicity. Although of potential clinical interest, the mechanism of this stimulated ascorbate-release remains unknown. Here, we report that primary cultures of mouse and rat astrocytes release ascorbate following initial uptake of dehydroascorbate and accumulation of intracellular ascorbate. Ascorbate-release was not due to cellular lysis, as assessed by cellular release of the cytosolic enzyme lactate dehydrogenase, and was stimulated by L-glutamate and L-aspartate, but not the non-excitatory amino acid L-glutamine. This stimulation was due to glutamate-induced cellular swelling, as it was both attenuated by hypertonic and emulated by hypotonic media. Glutamate-stimulated ascorbate-release was also sensitive to inhibitors of volume-sensitive anion channels, suggesting that the latter may provide the conduit for ascorbate efflux. Glutamate-stimulated ascorbate-release was not recapitulated by selective agonists of either ionotropic or group I metabotropic glutamate receptors, but was completely blocked by either of two compounds, TFB-TBOA and UCPH-101, which non-selectively and selectively inhibit the glial Na(+)-dependent excitatory amino acid transporter, GLAST, respectively. These results suggest that an impairment of astrocytic ascorbate-release may exacerbate neuronal dysfunction in neurodegenerative disorders and acute brain injury in which excitotoxicity and/or GLAST deregulation have been implicated.

  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. 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.

  6. Glutamate oxidation in astrocytes: Roles of glutamate dehydrogenase and aminotransferases.

    Science.gov (United States)

    McKenna, Mary C; Stridh, Malin H; McNair, Laura F; Sonnewald, Ursula; Waagepetersen, Helle S; Schousboe, Arne

    2016-12-01

    The cellular distribution of transporters and enzymes related to glutamate metabolism led to the concept of the glutamate-glutamine cycle. Glutamate is released as a neurotransmitter and taken up primarily by astrocytes ensheathing the synapses. The glutamate carbon skeleton is transferred back to the presynaptic neurons as the nonexcitatory amino acid glutamine. The cycle was initially thought to function with a 1:1 ratio between glutamate released and glutamine taken up by neurons. However, studies of glutamate metabolism in astrocytes have shown that a considerable proportion of glutamate undergoes oxidative degradation; thus, quantitative formation of glutamine from the glutamate taken up is not possible. Oxidation of glutamate is initiated by transamination catalyzed by an aminotransferase, or oxidative deamination catalyzed by glutamate dehydrogenase (GDH). We discuss methods available to elucidate the enzymes that mediate this conversion. Methods include pharmacological tools such as the transaminase inhibitor aminooxyacetic acid, studies using GDH knockout mice, and siRNA-mediated knockdown of GDH in astrocytes. Studies in brain slices incubated with [ 15 N]glutamate demonstrated activity of GDH in astrocytes in situ. These results, in conjunction with reports in the literature, support the conclusion that GDH is active in astrocytes both in culture and in vivo and that this enzyme plays a significant role in glutamate oxidation. Oxidative metabolism of glutamate, primarily mediated by GDH, but also by transamination by aspartate aminotransferase, provides considerably more energy than is required to maintain the activity of the high-affinity glutamate transporters needed for efficient removal of glutamate from the synaptic cleft. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. 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

  8. Pharmacological treatments inhibiting levodopa-induced dyskinesias in MPTP-lesioned monkeys: brain glutamate biochemical correlates

    Directory of Open Access Journals (Sweden)

    Nicolas eMorin

    2014-08-01

    Full Text Available Antiglutamatergic drugs can relieve Parkinson’s disease (PD symptoms and decrease L-3,4-dihydroxyphenylalanine (L-DOPA-induced dyskinesias (LID. This review reports relevant studies investigating glutamate receptor subtypes in relation to motor complications in PD patients and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP-lesioned monkeys. Antagonists of the ionotropic glutamate receptors, such as NMDA and AMPA receptors, display antidyskinetic activity in PD patients and animal models such as the MPTP monkey. Metabotropic glutamate 5 (mGlu5 receptor antagonists were shown to reduce the severity of LID in PD patients as well as in already dyskinetic non-human primates and to prevent the development of LID in de novo treatments in non-human primates. An increase in striatal post-synaptic NMDA, AMPA and mGlu5 receptors is documented in PD patients and MPTP monkeys with LID. This increase can be prevented in MPTP monkeys with the addition of a specific glutamate receptor antagonist to the L-DOPA treatment and also with drugs of various pharmacological specificities suggesting multiple receptor interactions. This is yet to be well documented for presynaptic mGlu4 and mGlu2/3 and offers additional new promising avenues.

  9. Glutamate oxidation in astrocytes: Roles of glutamate dehydrogenase and aminotransferases

    DEFF Research Database (Denmark)

    McKenna, Mary C; Stridh, Malin H; McNair, Laura Frendrup

    2016-01-01

    to the presynaptic neurons as the nonexcitatory amino acid glutamine. The cycle was initially thought to function with a 1:1 ratio between glutamate released and glutamine taken up by neurons. However, studies of glutamate metabolism in astrocytes have shown that a considerable proportion of glutamate undergoes...... the enzymes that mediate this conversion. Methods include pharmacological tools such as the transaminase inhibitor aminooxyacetic acid, studies using GDH knockout mice, and siRNA-mediated knockdown of GDH in astrocytes. Studies in brain slices incubated with [15N]glutamate demonstrated activity of GDH......The cellular distribution of transporters and enzymes related to glutamate metabolism led to the concept of the glutamate–glutamine cycle. Glutamate is released as a neurotransmitter and taken up primarily by astrocytes ensheathing the synapses. The glutamate carbon skeleton is transferred back...

  10. 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.

  11. Glutamic Acid - Amino Acid, Neurotransmitter, and Drug - Is Responsible for Protein Synthesis Rhythm in Hepatocyte Populations in vitro and in vivo.

    Science.gov (United States)

    Brodsky, V Y; Malchenko, L A; Konchenko, D S; Zvezdina, N D; Dubovaya, T K

    2016-08-01

    Primary cultures of rat hepatocytes were studied in serum-free media. Ultradian protein synthesis rhythm was used as a marker of cell synchronization in the population. Addition of glutamic acid (0.2 mg/ml) to the medium of nonsynchronous sparse cultures resulted in detection of a common protein synthesis rhythm, hence in synchronization of the cells. The antagonist of glutamic acid metabotropic receptors MCPG (0.01 mg/ml) added together with glutamic acid abolished the synchronization effect; in sparse cultures, no rhythm was detected. Feeding rats with glutamic acid (30 mg with food) resulted in protein synthesis rhythm in sparse cultures obtained from the rats. After feeding without glutamic acid, linear kinetics of protein synthesis was revealed. Thus, glutamic acid, a component of blood as a non-neural transmitter, can synchronize the activity of hepatocytes and can form common rhythm of protein synthesis in vitro and in vivo. This effect is realized via receptors. Mechanisms of cell-cell communication are discussed on analyzing effects of non-neural functions of neurotransmitters. Glutamic acid is used clinically in humans. Hence, a previously unknown function of this drug is revealed.

  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. De-coupling of blood flow and metabolism in the rat brain induced by glutamate

    International Nuclear Information System (INIS)

    Hirose, Shinichiro; Momosaki, Sotaro; Sasaki, Kazunari; Hosoi, Rie; Abe, Kohji; Inoue, Osamu; Gee, A.

    2009-01-01

    Glutamate plays an essential role in neuronal cell death in many neurological disorders. In this study, we examined both glucose metabolism and cerebral blood flow in the same rat following infusion of glutamate or ibotenic acid using the dual-tracer technique. The effects of MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, and 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX), an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-kainate receptor antagonist, on the changes in the glucose metabolism and cerebral blood flow induced by glutamate were also examined. The rats were microinjected with glutamate (1 μmol/μl, 2 μl) or ibotenic acid (10 μg/μl, 1 μl) into the right striatum, and dual-tracer autoradiograms of [ 18 F]fluorodeoxyglucose (FDG) and [ 14 C]iofetamine (IMP) were obtained. MK-801 and NBQX were injected intravenously about 45 and 30 min, respectively, after the infusion of glutamate. De-coupling of blood flow and metabolism was noted in the glutamate-infused hemisphere (as assessed by no alteration of [ 18 F]FDG uptake and significant decrease of [ 14 C]IMP uptake). Pretreatments with MK-801, NBQX, or combined use of MK-801 and NBQX did not affect the de-coupling of the blood flow and metabolism induced by glutamate. A histochemical study revealed that about 20% neuronal cell death had occurred in the striatum at 105 min after the infusion of glutamate. In addition, a significant increase of the [ 18 F]FDG uptake and decrease of [ 14 C]IMP uptake were also seen in the rat brain infused with ibotenic acid. These results indicate that glutamate and ibotenic acid caused a significant de-coupling of blood flow and glucose metabolism in the intact rat brain during the early phase of neurodegeneration. It is necessary to evaluate the relation between metabotropic glutamate receptors and de-coupling of blood flow and metabolism. (author)

  14. Glucose replaces glutamate as energy substrate to fuel glutamate uptake in glutamate dehydrogenase-deficient astrocytes.

    Science.gov (United States)

    Pajęcka, Kamilla; Nissen, Jakob D; Stridh, Malin H; Skytt, Dorte M; Schousboe, Arne; Waagepetersen, Helle S

    2015-07-01

    Cultured astrocytes treated with siRNA to knock down glutamate dehydrogenase (GDH) were used to investigate whether this enzyme is important for the utilization of glutamate as an energy substrate. By incubation of these cells in media containing different concentrations of glutamate (range 100-500 µM) in the presence or in the absence of glucose, the metabolism of these substrates was studied by using tritiated glutamate or 2-deoxyglucose as tracers. In addition, the cellular contents of glutamate and ATP were determined. The astrocytes were able to maintain physiological levels of ATP regardless of the expression level of GDH and the incubation condition, indicating a high degree of flexibility with regard to regulatory mechanisms involved in maintaining an adequate energy level in the cells. Glutamate uptake was found to be increased in these cells when exposed to increasing levels of extracellular glutamate independently of the GDH expression level. Moreover, increased intracellular glutamate content was observed in the GDH-deficient cells after a 2-hr incubation in the presence of 100 µM glutamate. It is significant that GDH-deficient cells exhibited an increased utilization of glucose in the presence of 250 and 500 µM glutamate, monitored as an increase in the accumulation of tritiated 2-deoxyglucose-6-phosphate. These findings underscore the importance of the expression level of GDH for the ability to utilize glutamate as an energy source fueling its own energy-requiring uptake. © 2015 Wiley Periodicals, Inc.

  15. Evidence for synergistic control of glutamate biosynthesis by glutamate dehydrogenases and glutamate in Bacillus subtilis.

    Science.gov (United States)

    Stannek, Lorena; Thiele, Martin J; Ischebeck, Till; Gunka, Katrin; Hammer, Elke; Völker, Uwe; Commichau, Fabian M

    2015-09-01

    In the Gram-positive bacterium, Bacillus subtilis glutamate is synthesized by the glutamine synthetase and the glutamate synthase (GOGAT). During growth with carbon sources that exert carbon catabolite repression, the rocG glutamate dehydrogenase (GDH) gene is repressed and the transcription factor GltC activates the expression of the GOGAT encoding gltAB genes. In the presence of amino acids of the glutamate family, the GDH RocG is synthesized and the enzyme prevents GltC from binding to DNA. The dual control of glutamate biosynthesis allows the efficient utilization of the available nutrients. Here we provide genetic and biochemical evidence that, like RocG, also the paralogous GDH GudB can inhibit the transcription factor GltC, thereby controlling glutamate biosynthesis. Contradictory previous observations show that high level of GDH activity does not result in permanent inhibition of GltC. By controlling the intracellular levels of glutamate through feeding with exogenous arginine, we observed that the GDH-dependent control of GltC and thus expression of the gltAB genes inversely correlates with the glutamate pool. These results suggest that the B. subtilis GDHs RocG and GudB in fact act as glutamate sensors. In conclusion, the GDH-mediated control of glutamate biosynthesis seems to depend on the intracellular glutamate concentration. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. Positive allosteric modulation of the human metabotropic glutamate receptor 4 (hmGluR4) by SIB-1893 and MPEP

    DEFF Research Database (Denmark)

    Mathiesen, Jesper Mosolff; Svendsen, Nannette; Bräuner-Osborne, Hans

    2003-01-01

    We have identified 2-methyl-6-(2-phenylethenyl)pyridine (SIB-1893) and 2-methyl-6-phenylethynyl pyridine hydrochloride (MPEP) as positive allosteric modulators for the hmGluR4. SIB-1893 and MPEP enhanced the potency and efficacy of L-2-amino-4-phophonobutyrate (L-AP4) in guanosine 5'-O-(3-[(35)S...

  17. Group II metabotropic glutamate receptor agonist may reduce behavioural deficit induced by early status epilepticus in adult rats

    Czech Academy of Sciences Publication Activity Database

    Alaverdashvili, Mariam; Kaminskij, Julij; Haugvicová, Renata; Folbergrová, Jaroslava

    2005-01-01

    Roč. 46, č. S6 (2005), s. 203-203 ISSN 0013-9580. [International Epilepsy Congress /26./. 28.08.2005-01.09.2005, Paris] R&D Projects: GA ČR(CZ) GA309/02/1238 Institutional research plan: CEZ:AV0Z50110509 Keywords : APDC * memory * cognitive functions Subject RIV: ED - Physiology

  18. Allelic association, DNA resequencing and copy number variation at the metabotropic glutamate receptor GRM7 gene locus in bipolar disorder.

    Science.gov (United States)

    Kandaswamy, Radhika; McQuillin, Andrew; Curtis, David; Gurling, Hugh

    2014-06-01

    Genetic markers at the GRM7 gene have shown allelic association with bipolar disorder (BP) in several case-control samples including our own sample. In this report, we present results of resequencing the GRM7 gene in 32 bipolar samples and 32 random controls selected from 553 bipolar cases and 547 control samples (UCL1). Novel and potential etiological base pair changes discovered by resequencing were genotyped in the entire UCL case-control sample. We also report on the association between GRM7 and BP in a second sample of 593 patients and 642 controls (UCL2). The three most significantly associated SNPs in the original UCL1 BP GWAS sample were genotyped in the UCL2 sample, of which none were associated. After combining the genotype data for the two samples only two (rs1508724 and rs6769814) of the original three SNP markers remained significantly associated with BP. DNA sequencing revealed mutations in three cases which were absent in control subjects. A 3'-UTR SNP rs56173829 was found to be significantly associated with BP in the whole UCL sample (P = 0.035; OR = 0.482), the rare allele being less common in cases compared to controls. Bioinformatic analyses predicted a change in the centroid secondary structure of RNA and alterations in the miRNA binding sites for the mutated base of rs56173829. We also validated two deletions and a duplication within GRM7 using quantitative-PCR which provides further support for the pre-existing evidence that copy number variants at GRM7 may have a role in the etiology of BP. © 2014 The Authors. American Journal of Medical Genetics Part B: Neuropsychiatric Published by Wiley Periodicals, Inc.

  19. Cocaine activates Homer1 immediate early gene transcription in the mesocorticolimbic circuit: differential regulation by dopamine and glutamate signaling.

    Science.gov (United States)

    Ghasemzadeh, M Behnam; Windham, Lindsay K; Lake, Russell W; Acker, Christopher J; Kalivas, Peter W

    2009-01-01

    Homer proteins are intracellular scaffolding proteins that, among glutamate receptors, selectively bind to group1 metabotropic glutamate receptors and regulate their trafficking and intracellular signaling. Homer proteins have been implicated in synaptic and behavioral plasticity, including drug-seeking behavior after cocaine treatment. Homer1 gene activation leads to transcription of a variant mRNA (Homer1a), which functions as an immediate early gene. Homer1a competes with the constitutive Homer proteins (Homer1b/c/d, Homer2a/b, Homer3) for binding to group1 metabotropic glutamate and IP3 receptors. Binding of Homer1a to these proteins disrupts their association with the intracellular signaling scaffold and modulates receptor function. In this study, using RT-PCR, activation of Homer1a mRNA transcription in response to acute and repeated administration of cocaine was characterized in prefrontal cortex, nucleus accumbens, and ventral tegmental area, three mesocorticolimbic nuclei of the rat brain. Moreover, the dopaminergic and glutamatergic regulation of Homer1 gene activation by cocaine was investigated. Acute cocaine rapidly and transiently activated transcription of Homer1a mRNA in all three nuclei. However, repeated administration of cocaine was not effective in inducing the Homer1a mRNA transcription after various withdrawal times ranging from 2 h to 3 weeks. The acute cocaine-mediated activation of Homer1 gene was regulated by D1 but not D2 dopamine receptors. The blockade of AMPA or NMDA glutamate receptors did not prevent cocaine-mediated activation of Homer1 gene in the three mesocorticolimbic nuclei. These data indicate that acute administration of cocaine transiently activates Homer1 gene producing the immediate early gene Homer1a mRNA in the three mesocorticolimbic nuclei of the rat brain. Activation of Homer1 gene may contribute to the cocaine-mediated synaptic and behavioral plasticity.

  20. Glucose replaces glutamate as energy substrate to fuel glutamate uptake in glutamate dehydrogenase-deficient astrocytes

    DEFF Research Database (Denmark)

    Pajęcka, Kamilla; Nissen, Jakob D; Stridh, Malin H

    2015-01-01

    Cultured astrocytes treated with siRNA to knock down glutamate dehydrogenase (GDH) were used to investigate whether this enzyme is important for the utilization of glutamate as an energy substrate. By incubation of these cells in media containing different concentrations of glutamate (range 100......-500 µM) in the presence or in the absence of glucose, the metabolism of these substrates was studied by using tritiated glutamate or 2-deoxyglucose as tracers. In addition, the cellular contents of glutamate and ATP were determined. The astrocytes were able to maintain physiological levels of ATP...... regardless of the expression level of GDH and the incubation condition, indicating a high degree of flexibility with regard to regulatory mechanisms involved in maintaining an adequate energy level in the cells. Glutamate uptake was found to be increased in these cells when exposed to increasing levels...

  1. L-( sup 3 H) glutamate binding to a membrane preparation from the optic lobe of the giant freshwater prawn Macrobrachium rosenbergii de Man

    Energy Technology Data Exchange (ETDEWEB)

    Pratumtan, P.; Govitrapong, P.; Withyachumnarnkul, B.; Poolsanguan, B. (Mahidol Univ., Bangkok (Thailand) Mahidol Univ., Nakorn Pathom (Thailand))

    1991-01-01

    Membrane preparation from the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man, was examined for the presence of specific L-({sup 3}H) glutamate binding. The optic lobes were isolated from live animals. The tissue was homogenized and the membrane fraction isolated by differential centrifugation. The membrane suspension was incubated with 10-1,000 nM of L-({sup 3}H) glutamate at 37{degree}C for 60 min. Nonspecific binding was determined by incubating the mixture with 100 {mu}M L-glutamate. L-({sup 3}H) glutamate specifically bound to the membrane fraction with a dissociation equilibrium constant (Kd) of 205 nM and maximum number of binding sites (Bmax) of 2.04 n mol/mg protein. By using LIGAND computerized program, the saturation isotherm binding pattern indicates a single type of binding. To determine the type of glutamate receptors, competitive inhibition and IC{sub 50} of several glutamate agonists and antagonists were determined. The study reveals a metabotropic type of binding site.

  2. Dances with black widow spiders: dysregulation of glutamate signalling enters centre stage in ADHD.

    Science.gov (United States)

    Lesch, K P; Merker, S; Reif, A; Novak, M

    2013-06-01

    Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with impairments across the lifespan. The persistence of ADHD is associated with considerable liability to neuropsychiatric co-morbidity such as depression, anxiety and substance use disorder. The substantial heritability of ADHD is well documented and recent genome-wide analyses for risk genes revealed synaptic adhesion molecules (e.g. latrophilin-3, LPHN3; fibronectin leucine-rich repeat transmembrane protein-3, FLRT3), glutamate receptors (e.g. metabotropic glutamate receptor-5, GRM5) and mediators of intracellular signalling pathways (e.g. nitric oxide synthase-1, NOS1). These genes encode principal components of the molecular machinery that connects pre- and postsynaptic neurons, facilitates glutamatergic transmission, controls synaptic plasticity and empowers intersecting neural circuits to process and refine information. Thus, identification of genetic variation affecting molecules essential for the formation, specification and function of excitatory synapses is refocusing research efforts on ADHD pathogenesis to include the long-neglected glutamate system. Copyright © 2012 Elsevier B.V. and ECNP. All rights reserved.

  3. Glutamate-dependent neuroglial calcium signaling differs between young and adult brain.

    Science.gov (United States)

    Sun, Wei; McConnell, Evan; Pare, Jean-Francois; Xu, Qiwu; Chen, Michael; Peng, Weiguo; Lovatt, Ditte; Han, Xiaoning; Smith, Yoland; Nedergaard, Maiken

    2013-01-11

    An extensive literature shows that astrocytes exhibit metabotropic glutamate receptor 5 (mGluR5)-dependent increases in cytosolic calcium ions (Ca(2+)) in response to glutamatergic transmission and, in turn, modulate neuronal activity by their Ca(2+)-dependent release of gliotransmitters. These findings, based on studies of young rodents, have led to the concept of the tripartite synapse, in which astrocytes actively participate in neurotransmission. Using genomic analysis, immunoelectron microscopy, and two-photon microscopy of astrocytic Ca(2+) signaling in vivo, we found that astrocytic expression of mGluR5 is developmentally regulated and is undetectable after postnatal week 3. In contrast, mGluR3, whose activation inhibits adenylate cyclase but not calcium signaling, was expressed in astrocytes at all developmental stages. Neuroglial signaling in the adult brain may therefore occur in a manner fundamentally distinct from that exhibited during development.

  4. Glutamic acid as anticancer agent: An overview

    OpenAIRE

    Dutta, Satyajit; Ray, Supratim; Nagarajan, K.

    2013-01-01

    The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. I...

  5. Glutamate mechanisms underlying opiate memories

    NARCIS (Netherlands)

    Peters, J.; de Vries, T.J.

    2012-01-01

    As the major excitatory neurotransmitter in the brain, glutamate plays an undisputable integral role in opiate addiction. This relates, in part, to the fact that addiction is a disorder of learning and memory, and glutamate is required for most types of memory formation. As opiate addiction

  6. Substrate and Cation Binding Mechanism of Glutamate Transporter Homologs

    NARCIS (Netherlands)

    Jensen, Sonja

    2017-01-01

    Glutamate transporters and their homologs are membrane proteins that transport glutamate and aspartate together with sodium ions and/or protons. Human glutamate transporters remove the neurotransmitter glutamate after signal transmission. Therefore, glutamate transporters play a great role in

  7. Glutamate plasticity woven through the progression to alcohol use disorder: a multi-circuit perspective [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Lara Hwa

    2017-03-01

    Full Text Available Glutamate signaling in the brain is one of the most studied targets in the alcohol research field. Here, we report the current understanding of how the excitatory neurotransmitter glutamate, its receptors, and its transporters are involved in low, episodic, and heavy alcohol use. Specific animal behavior protocols can be used to assess these different drinking levels, including two-bottle choice, operant self-administration, drinking in the dark, the alcohol deprivation effect, intermittent access to alcohol, and chronic intermittent ethanol vapor inhalation. Importantly, these methods are not limited to a specific category, since they can be interchanged to assess different states in the development from low to heavy drinking. We encourage a circuit-based perspective beyond the classic mesolimbic-centric view, as multiple structures are dynamically engaged during the transition from positive- to negative-related reinforcement to drive alcohol drinking. During this shift from lower-level alcohol drinking to heavy alcohol use, there appears to be a shift from metabotropic glutamate receptor-dependent behaviors to N-methyl-D-aspartate receptor-related processes. Despite high efficacy of the glutamate-related pharmaceutical acamprosate in animal models of drinking, it is ineffective as treatment in the clinic. Therefore, research needs to focus on other promising glutamatergic compounds to reduce heavy drinking or mediate withdrawal symptoms or both.

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

    DEFF Research Database (Denmark)

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

    1996-01-01

    , however, shown to be a specific and rather potent agonist at mGlu6, approximately 4 times weaker than the nonselective excitatory amino acid receptor agonist (S)-glutamic acid. 2-Aminoadipic acid (3), which shows a complex excitatory amino acid synaptic pharmacology, was an agonist at mGlu6 as well as m......The homologous series of acidic amino acids, ranging from aspartic acid (1) to 2-aminosuberic acid (5), and the corresponding series of 3-isoxazolol bioisosteres of these amino acids, ranging from (RS)-2-amino-2-(3-hydroxy-5-methylisoxazol-4-yl)acetic acid (AMAA, 6) to (RS)-2-amino-6-(3-hydroxy-5......-methylisoxazol-4-yl)hexanoic acid (10), were tested as ligands for metabotropic excitatory amino acid receptors (mGlu1 alpha, mGlu2, mGlu4a, and mGlu6). Whereas AMAA (6) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propinoic acid (AMPA, 7) are potent and highly selective agonists at N...

  9. 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

  10. Selective Interactions of Valeriana officinalis Extracts and Valerenic Acid with [3H]Glutamate Binding to Rat Synaptic Membranes

    Science.gov (United States)

    Del Valle-Mojica, Lisa M.; Ayala-Marín, Yoshira M.; Ortiz-Sanchez, Carmen M.; Torres-Hernández, Bianca A.; Abdalla-Mukhaimer, Safa; Ortiz, José G.

    2011-01-01

    Although GABA neurotransmission has been suggested as a mechanism for Valeriana officinalis effects, CNS depression can also be evoked by inhibition of ionotropic (iGluR) and metabotropic glutamate receptors (mGluR). In this study, we examined if aqueous valerian extract interacted with glutamatergic receptors. Freshly prepared aqueous valerian extract was incubated with rat cortical synaptic membranes in presence of 20 nM [3H]Glutamate. Aqueous valerian extract increased [3H]Glutamate binding from 1 × 10−7 to 1 × 10−3 mg/mL. In the presence of (2S,1′S,2′S)-2-(Carboxycyclopropyl)glycine (LCCG-I) and (2S,2′R,3′R)-2-(2′,3′-Dicarboxycyclopropyl)glycine (DCG-IV), Group II mGluR agents, valerian extract markedly decreased [3H]Glutamate binding, while (2S)-2-amino-3-(3,5-dioxo-1,2,4-oxadiazolidin-2-yl) propanoic acid) (quisqualic acid, QA), Group I mGluR agonist, increased [3H]Glutamate binding. At 0.05 mg/mL aqueous valerian extract specifically interacted with kainic acid NMDA and AMPA receptors. Valerenic acid, a marker compound for Valeriana officinalis, increased the [3H]Glutamate binding after 1.6 × 10−2 mg/mL, and at 0.008 mg/mL it interacted only with QA (Group I mGluR). The selective interactions of valerian extract and valerenic acid with Group I and Group II mGluR may represent an alternative explanation for the anxiolytic properties of this plant. PMID:21584239

  11. Glutamic acid as anticancer agent: An overview.

    Science.gov (United States)

    Dutta, Satyajit; Ray, Supratim; Nagarajan, K

    2013-10-01

    The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents. Besides these emphases are given especially for two endogenous derivatives of glutamic acid such as glutamine and glutamate. Glutamine is a derivative of glutamic acid and is formed in the body from glutamic acid and ammonia in an energy requiring reaction catalyzed by glutamine synthase. It also possesses anticancer activity. So the transportation and metabolism of glutamine are also discussed for better understanding the role of glutamic acid. Glutamates are the carboxylate anions and salts of glutamic acid. Here the roles of various enzymes required for the metabolism of glutamates are also discussed.

  12. 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...

  13. 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...

  14. Regulation of glutamate dehydrogenase in Bacillus subtilis.

    OpenAIRE

    Kane, J F; Wakim, J; Fischer, R S

    1981-01-01

    The activity of the nicotinamide adenine dinucleotide-dependent glutamate dehydrogenase in Bacillus subtilis was influenced by the carbon source, but not the nitrogen source, in the growth medium. The highest specific activity for this enzyme was found when B. subtilis was grown in a minimal or rich medium that contained glutamate as the carbon source. It is proposed that glutamate dehydrogenase serves a catabolic function in the metabolism of glutamate, is induced by glutamate, and is subjec...

  15. Regulation of glutamate dehydrogenase in Bacillus subtilis.

    Science.gov (United States)

    Kane, J F; Wakim, J; Fischer, R S

    1981-01-01

    The activity of the nicotinamide adenine dinucleotide-dependent glutamate dehydrogenase in Bacillus subtilis was influenced by the carbon source, but not the nitrogen source, in the growth medium. The highest specific activity for this enzyme was found when B. subtilis was grown in a minimal or rich medium that contained glutamate as the carbon source. It is proposed that glutamate dehydrogenase serves a catabolic function in the metabolism of glutamate, is induced by glutamate, and is subject to catabolite repression. PMID:6118356

  16. 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.

  17. 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...

  18. Genotoxicity of monosodium glutamate.

    Science.gov (United States)

    Ataseven, Nazmiye; Yüzbaşıoğlu, Deniz; Keskin, Ayten Çelebi; Ünal, Fatma

    2016-05-01

    Monosodium glutamate (MSG) is one of the most widely used flavor enhancers throughout the world. The aim of this study is to investigate the genotoxic potential of MSG by using chromosome aberrations (CAs), sister-chromatid exchanges (SCEs), cytokinesis-blocked micronucleus (CBMN), and random amplified polymorphic DNA-polimerase chain reaction (RAPD-PCR) in cultured human lymphocytes and alkaline comet assays in isolated human lymphocytes, which were incubated with six concentrations (250, 500, 1000, 2000, 4000 and 8000 μg/mL) of MSG. The result of this study indicated that MSG significantly and dose dependently increased the frequencies of CAs, SCE and MN in all treatments and times, compared with control. However, the replication (RI) and nuclear division indices (NDI) were not affected. In this paper, in vitro genotoxic effects of the MSG was also investigated on human peripheral lymphocytes by analysing the RAPD-PCR with arbitrary 10-mer primers. The changes occurring in RAPD profiles after MSG treatment include increase or decrease in band intensity and gain or loss of bands. In the comet assay, this additive caused DNA damage at all concentrations in isolated human lymphocytes after 1-h in vitro exposure. Our results demonstrate that MSG is genotoxic to the human peripheral blood lymphocytes in vitro. Copyright © 2016. Published by Elsevier Ltd.

  19. 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...

  20. 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...

  1. DNA nanopore translocation in glutamate solutions

    NARCIS (Netherlands)

    Plesa, C.; Van Loo, N.; Dekker, C.

    2015-01-01

    Nanopore experiments have traditionally been carried out with chloride-based solutions. Here we introduce silver/silver-glutamate-based electrochemistry as an alternative, and study the viscosity, conductivity, and nanopore translocation characteristics of potassium-, sodium-, and lithium-glutamate

  2. 21 CFR 582.1516 - Monopotassium glutamate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Monopotassium glutamate. 582.1516 Section 582.1516 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1516 Monopotassium glutamate. (a) Product. Monopotassium glutamate. (b) Conditions of use...

  3. 21 CFR 182.1516 - Monopotassium glutamate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Monopotassium glutamate. 182.1516 Section 182.1516 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Substances § 182.1516 Monopotassium glutamate. (a) Product. Monopotassium glutamate. (b) Conditions of use...

  4. 21 CFR 182.1500 - Monoammonium glutamate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Monoammonium glutamate. 182.1500 Section 182.1500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Substances § 182.1500 Monoammonium glutamate. (a) Product. Monoammonium glutamate. (b) Conditions of use...

  5. 21 CFR 582.1500 - Monoammonium glutamate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Monoammonium glutamate. 582.1500 Section 582.1500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1500 Monoammonium glutamate. (a) Product. Monoammonium glutamate. (b) Conditions of use...

  6. Glutamate esters as agents for cholescintigraphy

    International Nuclear Information System (INIS)

    Colombetti, L.

    1976-01-01

    Several sup(99m)Tc-labelled aldehyde glutamate complexes having similar pharmacological properties as sup(99m)Tc-pyridoxylidene glutamate have been prepared. The dynamic behaviour of these compounds in dogs and rabbits was studied using a digital computer and scintillation camera. The aldehyde-glutamate complex promises to be a useful agent for the dynamic study of hepatic and biliary function

  7. Ciprofloxacin triggered glutamate production by Corynebacterium glutamicum.

    Science.gov (United States)

    Lubitz, Dorit; Wendisch, Volker F

    2016-10-07

    Corynebacterium glutamicum is a well-studied bacterium which naturally overproduces glutamate when induced by an elicitor. Glutamate production is accompanied by decreased 2-oxoglutatate dehydrogenase activity. Elicitors of glutamate production by C. glutamicum analyzed to molecular detail target the cell envelope. Ciprofloxacin, an inhibitor of bacterial DNA gyrase and topoisomerase IV, was shown to inhibit growth of C. glutamicum wild type with concomitant excretion of glutamate. Enzyme assays showed that 2-oxoglutarate dehydrogenase activity was decreased due to ciprofloxacin addition. Transcriptome analysis revealed that this inhibitor of DNA gyrase increased RNA levels of genes involved in DNA synthesis, repair and modification. Glutamate production triggered by ciprofloxacin led to glutamate titers of up to 37 ± 1 mM and a substrate specific glutamate yield of 0.13 g/g. Even in the absence of the putative glutamate exporter gene yggB, ciprofloxacin effectively triggered glutamate production. When C. glutamicum wild type was cultivated under nitrogen-limiting conditions, 2-oxoglutarate rather than glutamate was produced as consequence of exposure to ciprofloxacin. Recombinant C. glutamicum strains overproducing lysine, arginine, ornithine, and putrescine, respectively, secreted glutamate instead of the desired amino acid when exposed to ciprofloxacin. Ciprofloxacin induced DNA synthesis and repair genes, reduced 2-oxoglutarate dehydrogenase activity and elicited glutamate production by C. glutamicum. Production of 2-oxoglutarate could be triggered by ciprofloxacin under nitrogen-limiting conditions.

  8. 21 CFR 182.1045 - Glutamic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glutamic acid. 182.1045 Section 182.1045 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1045 Glutamic acid. (a) Product. Glutamic acid. (b) [Reserved] (c) Limitations, restrictions, or...

  9. Curcumin Protects against Monosodium Glutamate Neurotoxicity and Decreasing NMDA2B and mGluR5 Expression in Rat Hippocampus

    Directory of Open Access Journals (Sweden)

    Rania M. Khalil

    2016-08-01

    Full Text Available Background: Monosodium glutamate (MSG is a flavor enhancer used in food industries. MSG is well documented to induce neurotoxicity. Curcumin (CUR reportedly possesses beneficial effects against various neurotoxic insults. Hence, this present study has been designed to evaluate the neuroprotective effect of curcumin on MSG-induced neurotoxicity in rats. Methods: Thirty-two male Wister rats were divided into four groups (n=8: Control group, MSG group, CUR group and MSG + CUR group. CUR (Curcumin 150 mg/kg, orally was given day after day for four weeks along with MSG (4 mg/kg, orally. After 4 weeks, rats were sacrificed and brain hippocampus was isolated immediately on ice. Inflammatory marker TNFα and acetylcholinesterase (AChE activity (marker for cholinergic function were estimated. Gene expressions of metabotropic glutamate receptor 5 (mGluR5 and N-methyl-D-aspartate receptor 2B (NMDA2B along with glutamate concentration were assessed. Results: Treatment with CUR significantly attenuated AChE activity and TNFα in MSG-treated animals. The anti-inflammatory properties of CUR may be responsible for this observed neuroprotective action. A possible role of CUR to attenuate both glutamate level and gene expression of NMDA2B and mGLUR5 in brain hippocampus was established when compared to MSG group. Conclusion: We concluded that CUR as flavor enhancer protects against MSG-induced neurotoxicity in rats.

  10. [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.

  11. A Metabotropic-Like Flux-Independent NMDA Receptor Regulates Ca2+ Exit from Endoplasmic Reticulum and Mitochondrial Membrane Potential in Cultured Astrocytes.

    Science.gov (United States)

    Montes de Oca Balderas, Pavel; Aguilera, Penélope

    2015-01-01

    Astrocytes were long thought to be only structural cells in the CNS; however, their functional properties support their role in information processing and cognition. The ionotropic glutamate N-methyl D-aspartate (NMDA) receptor (NMDAR) is critical for CNS functions, but its expression and function in astrocytes is still a matter of research and debate. Here, we report immunofluorescence (IF) labeling in rat cultured cortical astrocytes (rCCA) of all NMDAR subunits, with phenotypes suggesting their intracellular transport, and their mRNA were detected by qRT-PCR. IF and Western Blot revealed GluN1 full-length synthesis, subunit critical for NMDAR assembly and transport, and its plasma membrane localization. Functionally, we found an iCa2+ rise after NMDA treatment in Fluo-4-AM labeled rCCA, an effect blocked by the NMDAR competitive inhibitors D(-)-2-amino-5-phosphonopentanoic acid (APV) and Kynurenic acid (KYNA) and dependent upon GluN1 expression as evidenced by siRNA knock down. Surprisingly, the iCa2+ rise was not blocked by MK-801, an NMDAR channel blocker, or by extracellular Ca2+ depletion, indicating flux-independent NMDAR function. In contrast, the IP3 receptor (IP3R) inhibitor XestosponginC did block this response, whereas a Ryanodine Receptor inhibitor did so only partially. Furthermore, tyrosine kinase inhibition with genistein enhanced the NMDA elicited iCa2+ rise to levels comparable to those reached by the gliotransmitter ATP, but with different population dynamics. Finally, NMDA depleted the rCCA mitochondrial membrane potential (mΔψ) measured with JC-1. Our results demonstrate that rCCA express NMDAR subunits which assemble into functional receptors that mediate a metabotropic-like, non-canonical, flux-independent iCa2+ increase.

  12. [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

  13. Taurine activates delayed rectifier KV channels via a metabotropic pathway in retinal neurons

    Science.gov (United States)

    Bulley, Simon; Liu, Yufei; Ripps, Harris; Shen, Wen

    2013-01-01

    Taurine is one of the most abundant amino acids in the retina, throughout the CNS, and in heart and muscle cells. In keeping with its broad tissue distribution, taurine serves as a modulator of numerous basic processes, such as enzyme activity, cell development, myocardial function and cytoprotection. Despite this multitude of functional roles, the precise mechanism underlying taurine's actions has not yet been identified. In this study we report findings that indicate a novel role for taurine in the regulation of voltage-gated delayed rectifier potassium (KV) channels in retinal neurons by means of a metabotropic receptor pathway. The metabotropic taurine response was insensitive to the Cl− channel blockers, picrotoxin and strychnine, but it was inhibited by a specific serotonin 5-HT2A receptor antagonist, MDL11939. Moreover, we found that taurine enhanced KV channels via intracellular protein kinase C-mediated pathways. When 5-HT2A receptors were expressed in human embryonic kidney cells, taurine and AL34662, a non-specific 5-HT2 receptor activator, produced a similar regulation of KIR channels. In sum, this study provides new evidence that taurine activates a serotonin system, apparently via 5-HT2A receptors and related intracellular pathways. PMID:23045337

  14. The glutamate/GABA-glutamine cycle

    DEFF Research Database (Denmark)

    Bak, Lasse K; Schousboe, Arne; Waagepetersen, Helle S

    2006-01-01

    or GABA from neurons and subsequent uptake into astrocytes. In return, astrocytes release glutamine to be taken up into neurons for use as neurotransmitter precursor. In this review, the basic properties of the glutamate/GABA-glutamine cycle will be discussed, including aspects of transport and metabolism...... of intercellular transfer of ammonia produced in neurons (when glutamine is deamidated to glutamate) and utilized in astrocytes (for amidation of glutamate) when the glutamate/GABA-glutamine cycle is operating. A main objective of this review is to endorse the view that the glutamate/GABA-glutamine cycle must...

  15. 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

  16. Fate of glutamate carbon and nitrogen in isolated guinea-pig kidney-cortex tubules. Evidence for involvement of glutamate dehydrogenase in glutamine sythesis from glutamate.

    OpenAIRE

    Baverel, G; Genoux, C; Forissier, M; Pellet, M

    1980-01-01

    1. The pathways and the fate of glutamate carbon and nitrogen were investigated in isolated guinea-pig kidney-cortex tubules. 2. At low glutamate concentration (1 mM), the glutamate carbon skeleton was either completely oxidized or converted into glutamine. At high glutamate concentration (5 mM), glucose, lactate and alanine were additional products of glutamate metabolism. 3. At neither concentration of glutamate was there accumulation of ammonia. 4. Nitrogen-balance calculations and the rel...

  17. Introduction to the Glutamate-Glutamine Cycle

    DEFF Research Database (Denmark)

    Sonnewald, Ursula; Schousboe, Arne

    2016-01-01

    The term 'glutamate-glutamine cycle' was coined several decades ago based on the observation that using certain (14)C-labeled precursors for studies of brain metabolism the specific radioactivity of glutamine generated from glutamate was higher than that of glutamate, its immediate precursor....... This is metabolically impossible unless it is assumed that at least two distinct pools of these amino acids exist. This combined with the finding that the enzyme synthesizing glutamine from glutamate was expressed in astrocytes but not in neurons formed the basis of the notion that a cycle must exist in which glutamate...... released from neurons is transported into astrocytes, converted to glutamine which is subsequently returned to neurons and converted to glutamate by an enzyme the activity of which is much higher in neurons than in astrocytes. Originally this cycle was supposed to function in a stoichiometric fashion...

  18. Introduction to the Glutamate-Glutamine Cycle

    DEFF Research Database (Denmark)

    Sonnewald, Ursula; Schousboe, Arne

    2016-01-01

    . This is metabolically impossible unless it is assumed that at least two distinct pools of these amino acids exist. This combined with the finding that the enzyme synthesizing glutamine from glutamate was expressed in astrocytes but not in neurons formed the basis of the notion that a cycle must exist in which glutamate......The term 'glutamate-glutamine cycle' was coined several decades ago based on the observation that using certain (14)C-labeled precursors for studies of brain metabolism the specific radioactivity of glutamine generated from glutamate was higher than that of glutamate, its immediate precursor...... released from neurons is transported into astrocytes, converted to glutamine which is subsequently returned to neurons and converted to glutamate by an enzyme the activity of which is much higher in neurons than in astrocytes. Originally this cycle was supposed to function in a stoichiometric fashion...

  19. Metabotropic GABAB receptors mediate GABA inhibition of acetylcholine release in the rat neuromuscular junction.

    Science.gov (United States)

    Malomouzh, Artem I; Petrov, Konstantin A; Nurullin, Leniz F; Nikolsky, Evgeny E

    2015-12-01

    Gamma-aminobutyric acid (GABA) is an amino acid which acts as a neurotransmitter in the central nervous system. Here, we studied the effects of GABA on non-quantal, spontaneous, and evoked quantal acetylcholine (ACh) release from motor nerve endings. We found that while the application of 10 μM of GABA had no effect on spontaneous quantal ACh release, as detected by the frequency of miniature endplate potentials, GABA reduced the non-quantal ACh release by 57%, as determined by the H-effect value. Finally, the evoked quantal ACh release, estimated by calculating the quantal content of full-sized endplate potentials (EPPs), was reduced by 34%. GABA's inhibitory effect remained unchanged after pre-incubation with picrotoxin, an ionotropic GABAA receptor blocker, but was attenuated following application of the GABAB receptor blocker CGP 55845, which itself had no effect on ACh release. An inhibitor of phospholipase C, U73122, completely prevented the GABA-induced decrease in ACh release. Immunofluorescence demonstrated the presence of both subunits of the GABAB receptor (GABAB R1 and GABAB R2) in the neuromuscular junction. These findings suggest that metabotropic GABAB receptors are expressed in the mammalian neuromuscular synapse and their activation results in a phospholipase C-mediated reduction in the intensity of non-quantal and evoked quantal ACh release. We investigated the effect of gamma-aminobutyric acid (GABA) on neuromuscular transmission. GABA reduced the non-quantal and evoked quantal release of acetylcholine. These effects are mediated by GABAB receptors and are implemented via phospholipase C (PLC) activation. Our findings suggest that in the mammalian neuromuscular synapse, metabotropic GABAB receptors are expressed and their activation results in a reduction in the intensity of acetylcholine release. © 2015 International Society for Neurochemistry.

  20. Extensive neuroadaptive changes in cortical gene-transcript expressions of the glutamate system in response to repeated intermittent MDMA administration in adolescent rats

    Directory of Open Access Journals (Sweden)

    Malki Rana

    2008-04-01

    Full Text Available Abstract Background Many studies have focused on the implication of the serotonin and dopamine systems in neuroadaptive responses to the recreational drug 3,4-methylenedioxy-metamphetamine (MDMA. Less attention has been given to the major excitatory neurotransmitter glutamate known to be implicated in schizophrenia and drug addiction. The aim of the present study was to investigate the effect of repeated intermittent MDMA administration upon gene-transcript expression of the glutamate transporters (EAAT1, EAAT2-1, EAAT2-2, the glutamate receptor subunits of AMPA (GluR1, GluR2, GluR3, the glutamate receptor subunits of NMDA (NR1, NR2A and NR2B, as well as metabotropic glutamate receptors (mGluR1, mGluR2, mGluR3, mGluR5 in six different brain regions. Adolescent male Sprague Dawley rats received MDMA at the doses of 3 × 1 and 3 × 5 mg/kg/day, or 3× vehicle 3 hours apart, every 7th day for 4 weeks. The gene-transcript levels were assessed using real-time PCR validated with a range of housekeeping genes. Results The findings showed pronounced enhancements in gene-transcript expression of GluR2, mGluR1, mGluR5, NR1, NR2A, NR2B, EAAT1, and EAAT2-2 in the cortex at bregma +1.6. In the caudate putamen, mRNA levels of GluR3, NR2A, and NR2B receptor subunits were significantly increased. In contrast, the gene-transcript expression of GluR1 was reduced in the hippocampus. In the hypothalamus, there was a significant increase of GluR1, GluR3, mGluR1, and mGluR3 gene-transcript expressions. Conclusion Repeated intermittent MDMA administration induces neuroadaptive changes in gene-transcript expressions of glutamatergic NMDA and AMPA receptor subunits, metabotropic receptors and transporters in regions of the brain regulating reward-related associative learning, cognition, and memory and neuro-endocrine functions.

  1. Prefrontal changes in the glutamate-glutamine cycle and neuronal/glial glutamate transporters in depression with and without suicide

    NARCIS (Netherlands)

    Zhao, J.; Verwer, R.W.H.; van Wamelen, D.J.; Qi, X.R.; Gao, S.F.; Lucassen, P.J.; Swaab, D.F.

    2016-01-01

    There are indications for changes in glutamate metabolism in relation to depression or suicide. The glutamate-glutamine cycle and neuronal/glial glutamate transporters mediate the uptake of the glutamate and glutamine. The expression of various components of the glutamate-glutamine cycle and the

  2. 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...

  3. Potential of Glutamate-Based Drug Discovery for Next Generation Antidepressants

    Directory of Open Access Journals (Sweden)

    Shigeyuki Chaki

    2015-09-01

    Full Text Available Recently, ketamine has been demonstrated to exert rapid-acting antidepressant effects in patients with depression, including those with treatment-resistant depression, and this discovery has been regarded as the most significant advance in drug development for the treatment of depression in over 50 years. To overcome unwanted side effects of ketamine, numerous approaches targeting glutamatergic systems have been vigorously investigated. For example, among agents targeting the NMDA receptor, the efficacies of selective GluN2B receptor antagonists and a low-trapping antagonist, as well as glycine site modulators such as GLYX-13 and sarcosine have been demonstrated clinically. Moreover, agents acting on metabotropic glutamate receptors, such as mGlu2/3 and mGlu5 receptors, have been proposed as useful approaches to mimicking the antidepressant effects of ketamine. Neural and synaptic mechanisms mediated through the antidepressant effects of ketamine have been being delineated, most of which indicate that ketamine improves abnormalities in synaptic transmission and connectivity observed in depressive states via the AMPA receptor and brain-derived neurotrophic factor-dependent mechanisms. Interestingly, some of the above agents may share some neural and synaptic mechanisms with ketamine. These studies should provide important insights for the development of superior pharmacotherapies for depression with more potent and faster onsets of actions.

  4. Glutamate synthase: An archaeal horizontal gene transfer?

    Indian Academy of Sciences (India)

    (GOGAT) which is a key enzyme in ammonia assimilation in bacteria, algae and plants. It catalyzes the reductive transamidation of amido nitrogen from glutamine to 2-oxoglutarate to form two molecules of glutamate (Temple et al 1998). Glutamate synthases differ according to their molecular weights, subunit compositions, ...

  5. Modeling of glutamate-induced dynamical patterns

    DEFF Research Database (Denmark)

    Faurby-Bentzen, Christian Krefeld; Zhabotinsky, A.M.; Laugesen, Jakob Lund

    2009-01-01

    Based on established physiological mechanisms, the paper presents a detailed computer model, which supports the hypothesis that temporal lobe epilepsy may be caused by failure of glutamate reuptake from the extracellular space. The elevated glutamate concentration causes an increased activation o...

  6. Glutamate Fermentation-2: Mechanism of L-Glutamate Overproduction in Corynebacterium glutamicum.

    Science.gov (United States)

    Hirasawa, Takashi; Wachi, Masaaki

    The nonpathogenic coryneform bacterium, Corynebacterium glutamicum, was isolated as an L-glutamate-overproducing microorganism by Japanese researchers and is currently utilized in various amino acid fermentation processes. L-Glutamate production by C. glutamicum is induced by limitation of biotin and addition of fatty acid ester surfactants and β-lactam antibiotics. These treatments affect the cell surface structures of C. glutamicum. After the discovery of C. glutamicum, many researchers have investigated the underlying mechanism of L-glutamate overproduction with respect to the cell surface structures of this organism. Furthermore, metabolic regulation during L-glutamate overproduction by C. glutamicum, particularly, the relationship between central carbon metabolism and L-glutamate biosynthesis, has been investigated. Recently, the role of a mechanosensitive channel protein in L-glutamate overproduction has been reported. In this chapter, mechanisms of L-glutamate overproduction by C. glutamicum have been reviewed.

  7. Competitive inhibition of glutamate dehydrogenase reaction.

    Science.gov (United States)

    Choudhury, Rajarshi; Punekar, Narayan S

    2007-06-12

    Irrespective of their pyridine nucleotide specificity, all glutamate dehydrogenases share a common chemical mechanism that involves an enzyme bound 'iminoglutarate' intermediate. Three compounds, structurally related to this intermediate, were tested for the inhibition of purified NADP-glutamate dehydrogenases from two Aspergilli, as also the bovine liver NAD(P)-glutamate dehydrogenase. 2-Methyleneglutarate, closely resembling iminoglutarate, was a potent competitive inhibitor of the glutamate dehydrogenase reaction. This is the first report of a non-aromatic structure with a better glutamate dehydrogenase inhibitory potency than aryl carboxylic acids such as isophthalate. A suitably located 2-methylene group to mimic the iminium ion could be exploited to design inhibitors of other amino acid dehydrogenases.

  8. The eIF2a Kinase PERK Limits the Expression of Hippocampal Metabotropic Glutamate Receptor-Dependent Long-Term Depression

    Science.gov (United States)

    Trinh, Mimi A.; Ma, Tao; Kaphzan, Hanoch; Bhattacharya, Aditi; Antion, Marcia D.; Cavener, Douglas R.; Hoeffer, Charles A.; Klann, Eric

    2014-01-01

    The proper regulation of translation is required for the expression of long-lasting synaptic plasticity. A major site of translational control involves the phosphorylation of eukaryotic initiation factor 2 a (eIF2a) by PKR-like endoplasmic reticulum (ER) kinase (PERK). To determine the role of PERK in hippocampal synaptic plasticity, we used the…

  9. Posttreatment with group II metabotropic glutamate receptor agonist 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate is only weakly effective on seizures in immature rats

    Czech Academy of Sciences Publication Activity Database

    Folbergrová, Jaroslava; Druga, Rastislav; Tsenov, Grygoriy; Haugvicová, Renata; Otáhal, Jakub

    2009-01-01

    Roč. 1273, - (2009), s. 144-154 ISSN 0006-8993 R&D Projects: GA ČR(CZ) GA309/05/2015; GA ČR GA309/08/0292; GA ČR(CZ) GA304/07/1137 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z50200510 Keywords : DL-homocysteic acid-induced seizures * posttreatment with 2R * 4R-APDC * partial protection Subject RIV: FH - Neuro logy Impact factor: 2.463, year: 2009

  10. 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...

  11. 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...

  12. Activation of Group II Metabotropic Glutamate Receptors Increases Proliferation but does not Influence Neuronal Differentiation of a Human Neural Stem Cell Line

    DEFF Research Database (Denmark)

    Dindler, Anne; Blaabjerg, Morten; Kamand, Morad

    2018-01-01

    -positive immature neurons and glial fibrillary acidic protein-positive astrocytes. Stimulation of mGluR2/3 receptors during cell propagation using the agonist (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl) glycine (DCG-IV) increased total cell numbers significantly (60% compared to untreated controls). This effect...

  13. Seizures induced by homocysteic acid in immature rats are prevented by group III metabotropic glutamate receptoragonist (R,S)-4-phosphonophenylglycine

    Czech Academy of Sciences Publication Activity Database

    Folbergrová, Jaroslava; Haugvicová, Renata; Mareš, Pavel

    2003-01-01

    Roč. 180, č. 1 (2003), s. 46-54 ISSN 0014-4886 R&D Projects: GA ČR GA309/02/1238 Institutional research plan: CEZ:AV0Z5011922 Keywords : immature rats * seizures * energy metabolites Subject RIV: FH - Neurology Impact factor: 3.676, year: 2003

  14. A radiometric microassay for glutamic acid decarboxylase

    International Nuclear Information System (INIS)

    Maderdrut, J.L.; North Carolina Univ., Chapel Hill

    1979-01-01

    A simple method for purifying L-[ 3 H] glutamic acid and incubation conditions suitable for estimating L-glutamic acid decarboxylase activity are described. Routine and recycled cation-exchange procedure for separating γ-aminobutyric acid from L-glutamate are outlined and compared. Recycling increases the sensitivity of the cation-exchange method by 6-7 fold. L-Glutamate decarboxylase activity can be measured reliably in samples of embryonic neural tissue having wet-weights of approximately 1 μg. The cation-exchange method is compared with the anion-exchange and CO 2 -trapping methods. L-Glutamate decarboxylase activity has been detected in the lumbar spinal cord of the chick embryo at Day 21/4 (stage 14) using the cation-exchange method. This is 5-6 days earlier than L-glutamate decarboxylase activity has been detected in embryonic neural tissue by previous investigators. L-Glutamate decarboxylase is present in the lumbar spinal cord at least as early as the birth of the first lumbar spinal cord neurons and at least 1-2 days before the initiation of synaptogenesis. (author)

  15. AMPK Activation Affects Glutamate Metabolism in Astrocytes

    DEFF Research Database (Denmark)

    Voss, Caroline Marie; Pajęcka, Kamilla; Stridh, Malin H

    2015-01-01

    acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon...... skeleton into the TCA cycle was reduced. On the other hand, glutamate uptake into the astrocytes as well as its conversion to glutamine catalyzed by glutamine synthetase was not affected by AMPK activation. Interestingly, synthesis and release of citrate, which are hallmarks of astrocytic function, were...

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

    Directory of Open Access Journals (Sweden)

    Haruka Aoki

    2014-01-01

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

  17. Glutamate transporters combine transporter- and channel-like features

    NARCIS (Netherlands)

    Slotboom, DJ; Konings, WN; Lolkema, JS

    2001-01-01

    Glutamate transporters in the mammalian central nervous system have a unique position among secondary transport proteins as they exhibit glutamate-gated chloride-channel activity in addition to glutamate-transport activity. In this article, the available data on the structure of the glutamate

  18. Metabolic fate and function of dietary glutamate in the gut

    Science.gov (United States)

    Glutamate is a major constituent of dietary protein and is also consumed in many prepared foods as an additive in the form of monosodium glutamate. Evidence from human and animal studies indicates that glutamate is a major oxidative fuel for the gut and that dietary glutamate is extensively metabol...

  19. Emerging aspects of dietary glutamate metabolism in the developing gut

    Science.gov (United States)

    Glutamate is a major constituent of dietary protein and is also consumed in many prepared foods as a flavour additive in the form of monosodium glutamate (MSG). Evidence from human and animal studies indicates that glutamate is the major oxidative fuel for the gut and that dietary glutamate is exten...

  20. Control of the phosphorylation of the astrocyte marker glial fibrillary acidic protein (GFAP in the immature rat hippocampus by glutamate and calcium ions: possible key factor in astrocytic plasticity

    Directory of Open Access Journals (Sweden)

    Rodnight R.

    1997-01-01

    Full Text Available The present review describes recent research on the regulation by glutamate and Ca2+ of the phosphorylation state of the intermediate filament protein of the astrocytic cytoskeleton, glial fibrillary acidic protein (GFAP, in immature hippocampal slices. The results of this research are discussed against a background of modern knowledge of the functional importance of astrocytes in the brain and of the structure and dynamic properties of intermediate filament proteins. Astrocytes are now recognized as partners with neurons in many aspects of brain function with important roles in neural plasticity. Site-specific phosphorylation of intermediate filament proteins, including GFAP, has been shown to regulate the dynamic equilibrium between the polymerized and depolymerized state of the filaments and to play a fundamental role in mitosis. Glutamate was found to increase the phosphorylation state of GFAP in hippocampal slices from rats in the post-natal age range of 12-16 days in a reaction that was dependent on external Ca2+. The lack of external Ca2+ in the absence of glutamate also increased GFAP phosphorylation to the same extent. These effects of glutamate and Ca2+ were absent in adult hippocampal slices, where the phosphorylation of GFAP was completely Ca2+-dependent. Studies using specific agonists of glutamate receptors showed that the glutamate response was mediated by a G protein-linked group II metabotropic glutamate receptor (mGluR. Since group II mGluRs do not act by liberating Ca2+ from internal stores, it is proposed that activation of the receptor by glutamate inhibits Ca2+ entry into the astrocytes and consequently down-regulates a Ca2+-dependent dephosphorylation cascade regulating the phosphorylation state of GFAP. The functional significance of these results may be related to the narrow developmental window when the glutamate response is present. In the rat brain this window corresponds to the period of massive synaptogenesis during

  1. Construction of a potentiometric glutamate biosensor for determination of glutamate in some real samples.

    Science.gov (United States)

    Y Lmaz, Demet; Karaku, Emine

    2011-12-01

    The potentiometric glutamate biosensor based on ammonium-selective poly(vinylchloride) (PVC) membrane electrode was constructed by chemically immobilizing glutamate oxidase. Ammonium ions produced after an enzymatic reaction were determined potentiometrically. We determined the optimum working conditions of the biosensor such as buffer concentration, buffer pH, lifetime, response time, linear working range, kinetic constants (K(m) and V(max)) of glutamate oxidase enzyme used for biosensor construction values, and other response characteristics. Additionally, glutamate assay in some real samples such as chicken bullion, healthy human serum, and commercial multipower amino acid mixture were also successfully carried out. The results showed good agreement with previously reported values.

  2. 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

  3. Biobased synthesis of acrylonitrile from glutamic acid

    NARCIS (Netherlands)

    Notre, le J.E.L.; Scott, E.L.; Franssen, M.C.R.; Sanders, J.P.M.

    2011-01-01

    Glutamic acid was transformed into acrylonitrile in a two step procedure involving an oxidative decarboxylation in water to 3-cyanopropanoic acid followed by a decarbonylation-elimination reaction using a palladium catalyst

  4. Temperature-sensitive glutamate dehydrogenase mutants of Salmonella typhimurium.

    OpenAIRE

    Dendinger, S M; Brenchley, J E

    1980-01-01

    Mutants of Salmonella typhimurium defective in glutamate dehydrogenase activity were isolated in parent strains lacking glutamate synthase activity by localizcd mutagenesis or by a general mutagenesis combined with a cycloserine enrichment for glutamate auxotrophs. Two mutants with temperature-sensitive phenotypes had glutamate dehydrogenase activities that were more thermolabile than that of an isogenic control strain. Eight other mutants had less than 10% of the wild-type glutamate dehydrog...

  5. Intracellular synthesis of glutamic acid in Bacillus methylotrophicus SK19.001, a glutamate-independent poly(γ-glutamic acid)-producing strain.

    Science.gov (United States)

    Peng, Yingyun; Zhang, Tao; Mu, Wanmeng; Miao, Ming; Jiang, Bo

    2016-01-15

    Bacillus methylotrophicus SK19.001 is a glutamate-independent strain that produces poly(γ-glutamic acid) (γ-PGA), a polymer of D- and L-glutamic acids that possesses applications in food, the environment, agriculture, etc. This study was undertaken to explore the synthetic pathway of intracellular L- and D-glutamic acid in SK19.001 by investigating the effects of tricarboxylic acid cycle intermediates and different amino acids as metabolic precursors on the production of γ-PGA and analyzing the activities of the enzymes involved in the synthesis of L- and D-glutamate. Tricarboxylic acid cycle intermediates and amino acids could participate in the synthesis of γ-PGA via independent pathways in SK19.001. L-Aspartate aminotransferase, L-glutaminase and L-glutamate synthase were the enzymatic sources of L-glutamate. Glutamate racemase was responsible for the formation of D-glutamate for the synthesis of γ-PGA, and the synthetase had stereoselectivity for glutamate substrate. The enzymatic sources of L-glutamate were investigated for the first time in the glutamate-independent γ-PGA-producing strain, and multiple enzymatic sources of L-glutamate were verified in SK19.001, which will benefit efforts to improve production of γ-PGA with metabolic engineering strategies. © 2015 Society of Chemical Industry.

  6. The application of glutamic acid alpha-decarboxylase for the valorization of glutamic acid

    NARCIS (Netherlands)

    Lammens, T.M.; Biase, De Daniela; Franssen, M.C.R.; Scott, E.L.; Sanders, J.P.M.

    2009-01-01

    Glutamic acid is an important constituent of waste streams from biofuels production. It is an interesting starting material for the synthesis of nitrogen containing bulk chemicals, thereby decreasing the dependency on fossil fuels. On the pathway from glutamic acid to a range of molecules, the

  7. The Degradation of 14C-Glutamic Acid by L-Glutamic Acid Decarboxylase.

    Science.gov (United States)

    Dougherty, Charles M; Dayan, Jean

    1982-01-01

    Describes procedures and semi-micro reaction apparatus (carbon dioxide trap) to demonstrate how a particular enzyme (L-Glutamic acid decarboxylase) may be used to determine the site or sites of labeling in its substrate (carbon-14 labeled glutamic acid). Includes calculations, solutions, and reagents used. (Author/SK)

  8. A Novel Amperometric Glutamate Biosensor Based on Glutamate Oxidase Adsorbed on Silicalite

    Science.gov (United States)

    Soldatkina, O. V.; Soldatkin, O. O.; Kasap, B. Ozansoy; Kucherenko, D. Yu.; Kucherenko, I. S.; Kurc, B. Akata; Dzyadevych, S. V.

    2017-04-01

    In this work, we developed a new amperometric biosensor for glutamate detection using a typical method of glutamate oxidase (GlOx) immobilization via adsorption on silicalite particles. The disc platinum electrode ( d = 0.4 mm) was used as the amperometric sensor. The procedure of biosensor preparation was optimized. The main parameters of modifying amperometric transducers with a silicalite layer were determined along with the procedure of GlOx adsorption on this layer. The biosensors based on GlOx adsorbed on silicalite demonstrated high sensitivity to glutamate. The linear range of detection was from 2.5 to 450 μM, and the limit of glutamate detection was 1 μM. It was shown that the proposed biosensors were characterized by good response reproducibility during hours of continuous work and operational stability for several days. The developed biosensors could be applied for determination of glutamate in real samples.

  9. Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally “frozen” analogues of L-glutamic acid

    Directory of Open Access Journals (Sweden)

    Beatrice Bechi

    2014-05-01

    Full Text Available Several strategies aimed to “freeze” natural amino acids into more constrained analogues have been developed with the aim of enhancing in vitro potency/selectivity and, more in general, drugability properties. The case of L-glutamic acid (L-Glu, 1 is of particular importance since it is the primary excitatory neurotransmitter in the mammalian central nervous system (CNS and plays a critical role in a wide range of disorders like schizophrenia, depression, neurodegenerative diseases such as Parkinson’s and Alzheimer’s and in the identification of new potent and selective ligands of ionotropic and metabotropic glutamate receptors (GluRs. To this aim, bicycle compound Ib was designed and synthesised from D-serine as novel [2.3]-spiro analogue of L-Glu. This frozen amino acid derivative was designed to further limit the rotation around the C3–C4 bond present in the azetidine derivative Ia by incorporating an appropriate spiro moiety. The cyclopropyl moiety was introduced by a diastereoselective rhodium catalyzed cyclopropanation reaction.

  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. Vitamin D is associated with metabotropic but not neurotrophic effects of exercise in ovariectomized rats

    Directory of Open Access Journals (Sweden)

    Parvin Babaei

    2017-11-01

    Full Text Available Abstract Purpose Here, we studied the beneficial effects of aerobic exercise on metabolic syndrome components, cognitive performance, brain derived neurotrophic factor (BDNF and irisin in ovariectomized rats with different serum vitamin D (Vit D status. Methods Eighty female wistar rats were divided into 2 groups of sham operated (sham, n = 8, and ovariectomized (OVX, n = 72. Then OVX were divided into 9 groups of receiving combination of exercise protocol with low dose of Vit D (OVX + EXE + LD, high dose of Vit D (OVX + EXE + HD, Vit D deficiency (OVX + EXE − D, and (OVX + EXE + Veh. Also non exercised groups of OVX receiving high dose of Vit D (OVX + HD, low dose of Vit D (OVX + LD, Vit D deficiency (OVX − D, and Veh (OVX + Veh were included. After 2 months of related interventions, spatial memory was assessed using Morris water maze (MWM, and then metabolic syndrome components were measured. Results High dose of Vit D supplementation showed significant reduction in weight (p = 0.001, lipid profiles (p = 0.001, visceral fat (p = 0.001 and waist circumference (p = 0.001 regardless of exercising or not, with no change in cognitiive function. Serum BDNF level was significantly higher in Vit D deficient group (p = 0.001, and was decreased in the OVX + HD. In contrary, irisin did not show any significant relationship with serum concentration of Vit D, while it was significantly elevated in the exercised groups compared with non-exercised counterparts. Conclusion Vit D insufficiency deteriorates metabolic syndrome components, and elevates serum BDNF as a compensatory metabotropic factor, and further supplementation significantly attenuates these components parallel with reduction in BDNF. In addition, aerobic exercise successfully induces various metabolic benefits, provided optimum serum level of Vit D.

  12. Monosodium glutamate for simple photometric iron analysis

    Science.gov (United States)

    Prasetyo, E.

    2018-01-01

    Simple photometric method for iron analysis using monosodium glutamate (MSG) was proposed. The method could be used as an alternative method, which was technically simple, economic, quantitative, readily available, scientifically sound and environmental friendly. Rapid reaction of iron (III) with glutamate in sodium chloride-hydrochloric acid buffer (pH 2) to form red-brown complex was served as a basis in the photometric determination, which obeyed the range of iron (III) concentration 1.6 – 80 µg/ml. This method could be applied to determine iron concentration in soil with satisfactory results (accuracy and precision) compared to other photometric and atomic absorption spectrometry results.

  13. The structure of glutamate transporters shows channel-like features

    NARCIS (Netherlands)

    Slotboom, DJ; Konings, WN; Lolkema, JS

    2001-01-01

    Neuronal and glial glutamate transporters remove the excitatory neurotransmitter glutamate from the synaptic cleft and thus prevent neurotoxicity, The proteins belong to a large family of secondary transporters, which includes transporters from a variety of bacterial, archaeal and eukaryotic

  14. 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...

  15. 21 CFR 182.1047 - Glutamic acid hydrochloride.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glutamic acid hydrochloride. 182.1047 Section 182.1047 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1047 Glutamic acid hydrochloride. (a) Product. Glutamic acid hydrochloride. (b...

  16. Influence of Glutamic Acid on the Properties of Poly(xylitol glutamate sebacate Bioelastomer

    Directory of Open Access Journals (Sweden)

    Weifu Dong

    2013-11-01

    Full Text Available In order to further improve the biocompatibility of xylitol based poly(xylitol sebacate (PXS bioelastomer, a novel kind of amino acid based poly(xylitol glutamate sebacate (PXGS has been successfully prepared in this work by melt polycondensation of xylitol, N-Boc glutamic acid and sebacic acid. Differential scanning calorimetry (DSC results indicated the glass-transition temperatures could be decreased by feeding N-Boc glutamic acid. In comparison to PXS, PXGS exhibited comparable tensile strength and much higher elongation at break at the same ratio of acid/xylitol. The introduction of glutamic acid increased the hydrophilicity and in vitro degradation rate of the bioelastomer. It was found that PXGS exhibited excellent properties, such as tensile properties, biodegradability and hydrophilicity, which could be easily tuned by altering the feeding monomer ratios. The amino groups in the PXGS polyester side chains are readily functionalized, thus the biomelastomers can be considered as potential biomaterials for biomedical application.

  17. the effect of monosodium glutamate (msg)

    African Journals Online (AJOL)

    Uwaifoh

    2012-03-30

    Mar 30, 2012 ... Neuronal vulnerability in mouse models of Huntington's disease: Membrane channel protein changes. J Neurosci Res; 80: 634 - 645. Ashaolu, J.O., Ukwenya, V.O., Okonoboh, A.B., Ghazal, O.K. and Jimoh A.A.G. (2011). Effect of monosodium glutamate on hematological parameters in Wistar rats.

  18. 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.

  19. Monosodium glutamate: Potentials at inducing prostate pathologies ...

    African Journals Online (AJOL)

    The health implication of the alteration could be compounded by the opposing response elicited by increasing the concentration of either MSG or DW. Key words: Monosodium glutamate, total acid phosphatase, prostatic acid phosphatase, prostate cancer, prostatitis, benign prostate hyperplasia, infertility. African Journal of ...

  20. Amperometric L-glutamate biosensor based on bacterial cell-surface displayed glutamate dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Bo [Laboratory for Biosensing, Key Laboratory of Biofuels, and Shandong Provinicial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy & Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049 (China); Zhang, Shu [Laboratory for Biosensing, Key Laboratory of Biofuels, and Shandong Provinicial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy & Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Key Laboratory of Marine Chemistry Theory and Technology of Ministry of Education, Ocean University of China, 238 Songling Road, Qingdao 266100 (China); Lang, Qiaolin [Laboratory for Biosensing, Key Laboratory of Biofuels, and Shandong Provinicial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy & Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Song, Jianxia; Han, Lihui [Key Laboratory of Marine Chemistry Theory and Technology of Ministry of Education, Ocean University of China, 238 Songling Road, Qingdao 266100 (China); Liu, Aihua, E-mail: liuah@qibebt.ac.cn [Laboratory for Biosensing, Key Laboratory of Biofuels, and Shandong Provinicial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy & Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049 (China)

    2015-07-16

    Highlights: • E. coli surface-dispalyed Gldh exhibiting excellent enzyme activity and stability. • Sensitive amperometric biosensor for glutamate using Gldh-bacteria and MWNTs. • The glutamate biosensor exhibited high specificity and stability. - Abstract: A novel L-glutamate biosensor was fabricated using bacteria surface-displayed glutamate dehydrogenase (Gldh-bacteria). Here the cofactor NADP{sup +}-specific dependent Gldh was expressed on the surface of Escherichia coli using N-terminal region of ice nucleation protein (INP) as the anchoring motif. The cell fractionation assay and SDS-PAGE analysis indicated that the majority of INP-Gldh fusion proteins were located on the surface of cells. The biosensor was fabricated by successively casting polyethyleneimine (PEI)-dispersed multi-walled carbon nanotubes (MWNTs), Gldh-bacteria and Nafion onto the glassy carbon electrode (Nafion/Gldh-bacteria/PEI-MWNTs/GCE). The MWNTs could not only significantly lower the oxidation overpotential towards NAPDH, which was the product of NADP{sup +} involving in the oxidation of glutamate by Gldh, but also enhanced the current response. Under the optimized experimental conditions, the current–time curve of the Nafion/Gldh-bacteria/PEI-MWNTs/GCE was performed at +0.52 V (vs. SCE) by amperometry varying glutamate concentration. The current response was linear with glutamate concentration in two ranges (10 μM–1 mM and 2–10 mM). The low limit of detection was estimated to be 2 μM glutamate (S/N = 3). Moreover, the proposed biosensor is stable, specific, reproducible and simple, which can be applied to real samples detection.

  1. Strontium D-Glutamate Hexahydrate and Strontium Di(hydrogen L-glutamate) Pentahydrate

    DEFF Research Database (Denmark)

    Christgau, Stephan; Odderhede, Jette; Stahl, Kenny

    2005-01-01

    Sr(C5H7NO4)] center dot 6H(2)O, ( I), and [Sr(C5H8NO4)(2)] center dot 5H(2)O, (II), both crystallize with similar strontium - glutamate - water layers. In ( I), the neutral layers are connected through hydrogen bonds by water molecules, while in ( II), the positively charged layers are connected...... through hydrogen bonds and electrostatic interactions by interleaving layers of hydrogen glutamate anions and water molecules....

  2. ¹³C-metabolic enrichment of glutamate in glutamate dehydrogenase mutants of Saccharomyces cerevisiae.

    Science.gov (United States)

    Tang, Yijin; Sieg, Alex; Trotter, Pamela J

    2011-10-20

    Glutamate dehydrogenases (GDH) interconvert α-ketoglutarate and glutamate. In yeast, NADP-dependent enzymes, encoded by GDH1 and GDH3, are reported to synthesize glutamate from α-ketoglutarate, while an NAD-dependent enzyme, encoded by GDH2, catalyzes the reverse. Cells were grown in acetate/raffinose (YNAceRaf) to examine the role(s) of these enzymes during aerobic metabolism. In YNAceRaf the doubling time of wild type, gdh2Δ, and gdh3Δ cells was comparable at ∼4 h. NADP-dependent GDH activity (Gdh1p+Gdh3p) in wild type, gdh2Δ, and gdh3Δ was decreased ∼80% and NAD-dependent activity (Gdh2p) in wild type and gdh3Δ was increased ∼20-fold in YNAceRaf as compared to glucose. Cells carrying the gdh1Δ allele did not divide in YNAceRaf, yet both the NADP-dependent (Gdh3p) and NAD-dependent (Gdh2p) GDH activity was ∼3-fold higher than in glucose. Metabolism of [1,2-(13)C]-acetate and analysis of carbon NMR spectra were used to examine glutamate metabolism. Incorporation of (13)C into glutamate was nearly undetectable in gdh1Δ cells, reflecting a GDH activity at glutamate carbons indicates a decreased rate of glutamate biosynthesis from acetate in gdh2Δ and gdh3Δ strains as compared to wild type. Further, the relative complexity of (13)C-isotopomers at early time points was noticeably greater in gdh3Δ as compared to wild type and gdh2Δ cells. These in vivo data show that Gdh1p is the primary GDH enzyme and Gdh2p and Gdh3p play evident roles during aerobic glutamate metabolism. Copyright © 2010 Elsevier GmbH. All rights reserved.

  3. 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.

  4. Deletion of glutamate dehydrogenase 1 (Glud1) in the central nervous system affects glutamate handling without altering synaptic transmission

    DEFF Research Database (Denmark)

    Frigerio, Francesca; Karaca, Melis; De Roo, Mathias

    2012-01-01

    Glutamate dehydrogenase (GDH), encoded by GLUD1, participates in the breakdown and synthesis of glutamate, the main excitatory neurotransmitter. In the CNS, besides its primary signaling function, glutamate is also at the crossroad of metabolic and neurotransmitter pathways. Importance of brain G...

  5. Amperometric L-glutamate biosensor based on bacterial cell-surface displayed glutamate dehydrogenase.

    Science.gov (United States)

    Liang, Bo; Zhang, Shu; Lang, Qiaolin; Song, Jianxia; Han, Lihui; Liu, Aihua

    2015-07-16

    A novel L-glutamate biosensor was fabricated using bacteria surface-displayed glutamate dehydrogenase (Gldh-bacteria). Here the cofactor NADP(+)-specific dependent Gldh was expressed on the surface of Escherichia coli using N-terminal region of ice nucleation protein (INP) as the anchoring motif. The cell fractionation assay and SDS-PAGE analysis indicated that the majority of INP-Gldh fusion proteins were located on the surface of cells. The biosensor was fabricated by successively casting polyethyleneimine (PEI)-dispersed multi-walled carbon nanotubes (MWNTs), Gldh-bacteria and Nafion onto the glassy carbon electrode (Nafion/Gldh-bacteria/PEI-MWNTs/GCE). The MWNTs could not only significantly lower the oxidation overpotential towards NAPDH, which was the product of NADP(+) involving in the oxidation of glutamate by Gldh, but also enhanced the current response. Under the optimized experimental conditions, the current-time curve of the Nafion/Gldh-bacteria/PEI-MWNTs/GCE was performed at +0.52 V (vs. SCE) by amperometry varying glutamate concentration. The current response was linear with glutamate concentration in two ranges (10 μM-1 mM and 2-10 mM). The low limit of detection was estimated to be 2 μM glutamate (S/N=3). Moreover, the proposed biosensor is stable, specific, reproducible and simple, which can be applied to real samples detection. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Microbial production of poly-γ-glutamic acid.

    Science.gov (United States)

    Sirisansaneeyakul, Sarote; Cao, Mingfeng; Kongklom, Nuttawut; Chuensangjun, Chaniga; Shi, Zhongping; Chisti, Yusuf

    2017-09-05

    Poly-γ-glutamic acid (γ-PGA) is a natural, biodegradable and water-soluble biopolymer of glutamic acid. This review is focused on nonrecombinant microbial production of γ-PGA via fermentation processes. In view of its commercial importance, the emphasis is on L-glutamic acid independent producers (i.e. microorganisms that do not require feeding with the relatively expensive amino acid L-glutamic acid to produce γ-PGA), but glutamic acid dependent production is discussed for comparison. Strategies for improving production, reducing costs and using renewable feedstocks are discussed.

  7. Inhibitors of glutamate dehydrogenase block sodium-dependent glutamate uptake in rat brain membranes

    Directory of Open Access Journals (Sweden)

    Brendan S Whitelaw

    2013-09-01

    Full Text Available We recently found evidence for anatomic and physical linkages between the astroglial Na+-dependent glutamate transporters (GLT-1/EAAT2 and GLAST/EAAT1 and mitochondria. In these same studies, we found that the glutamate dehydrogenase (GDH inhibitor, epigallocatechin-monogallate (EGCG, inhibits both glutamate oxidation and Na+-dependent glutamate uptake in astrocytes. In the present study, we extend this finding by exploring the effects of EGCG on Na+-dependent L-[3H]-glutamate (Glu uptake in crude membranes (P2 prepared from rat brain cortex. In this preparation, uptake is almost exclusively mediated by GLT-1. EGCG inhibited L-[3H]-Glu uptake in cortical membranes with an IC50 value of 230 µM. We also studied the effects of two additional inhibitors of GDH, hexachlorophene (HCP and bithionol (BTH. Both of these compounds also caused concentration-dependent inhibition of glutamate uptake in cortical membranes. Pre-incubating with HCP for up to 15 min had no greater effect than that observed with no pre-incubation, showing that the effects occur rapidly. HCP decreased the Vmax for glutamate uptake without changing the Km, consistent with a non-competitive mechanism of action. EGCG, HCP, and BTH also inhibited Na+-dependent transport of D-[3H]-aspartate (Asp, a non-metabolizable substrate, and [3H]-γ-aminobutyric acid (GABA. In contrast to the forebrain, glutamate uptake in crude cerebellar membranes (P2 is likely mediated by GLAST (EAAT1. Therefore, the effects of these compounds were examined in cerebellar membranes. In this region, none of these compounds had any effect on uptake of either L-[3H]-Glu or D-[3H]-Asp, but they all inhibited [3H]-GABA uptake. Together these studies suggest that GDH is preferentially required for glutamate uptake in forebrain as compared to cerebellum, and GDH may be required for GABA uptake as well. They also provide further evidence for a functional linkage between glutamate transport and mitochondria.

  8. Microsensors for in vivo Measurement of Glutamate in Brain Tissue

    Directory of Open Access Journals (Sweden)

    Miranda van der Zeyden

    2008-11-01

    Full Text Available Several immobilized enzyme-based electrochemical biosensors for glutamate detection have been developed over the last decade. In this review, we compare first and second generation sensors. Structures, working mechanisms, interference prevention, in vitro detection characteristics and in vivo performance are summarized here for those sensors that have successfully detected brain glutamate in vivo. In brief, first generation sensors have a simpler structure and are faster in glutamate detection. They also show a better sensitivity to glutamate during calibration in vitro. For second generation sensors, besides their less precise detection, their fabrication is difficult to reproduce, even with a semi-automatic dip-coater. Both generations of sensors can detect glutamate levels in vivo, but the reported basal levels are different. In general, second generation sensors detect higher basal levels of glutamate compared with the results obtained from first generation sensors. However, whether the detected glutamate is indeed from synaptic sources is an issue that needs further attention.

  9. Glutamate Efflux at the Blood-Brain Barrier

    DEFF Research Database (Denmark)

    Cederberg-Helms, Hans Christian; Uhd-Nielsen, Carsten; Brodin, Birger

    2014-01-01

    L-Glutamate is considered the most important excitatory amino acid in the mammalian brain. Strict control of its concentration in the brain interstitial fluid is important to maintain neurotransmission and avoid excitotoxicity. The role of astrocytes in handling L-glutamate transport and metabolism...... is well known, however endothelial cells may also play an important role through mediating brain-to-blood L-glutamate efflux. Expression of excitatory amino acid transporters has been demonstrated in brain endothelial cells of bovine, human, murine, rat and porcine origin. These can account for high...... affinity concentrative uptake of L-glutamate from the brain interstitial fluid into the capillary endothelial cells. The mechanisms in between L-glutamate uptake in the endothelial cells and L-glutamate appearing in the blood are still unclear and may involve a luminal transporter for L-glutamate...

  10. Glutamate alteration of glutamic acid decarboxylase (GAD) in GABAergic neurons: the role of cysteine proteases.

    Science.gov (United States)

    Monnerie, Hubert; Le Roux, Peter D

    2008-09-01

    Brain cell vulnerability to neurologic insults varies greatly, depending on their neuronal subpopulation. Among cells that survive a pathological insult such as ischemia or brain trauma, some may undergo morphological and/or biochemical changes that could compromise brain function. We previously reported that surviving cortical GABAergic neurons exposed to glutamate in vitro displayed an NMDA receptor (NMDAR)-mediated alteration in the levels of the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67) [Monnerie, H., Le Roux, P., 2007. Reduced dendrite growth and altered glutamic acid decarboxylase (GAD) 65- and 67-kDa isoform protein expression from mouse cortical GABAergic neurons following excitotoxic injury in vitro. Exp. Neurol. 205, 367-382]. In this study, we examined the mechanisms by which glutamate excitotoxicity caused a change in cortical GABAergic neurons' GAD protein levels. Removing extracellular calcium prevented the NMDAR-mediated decrease in GAD protein levels, measured using Western blot techniques, whereas inhibiting calcium entry through voltage-gated calcium channels had no effect. Glutamate's effect on GAD protein isoforms was significantly attenuated by preincubation with the cysteine protease inhibitor N-Acetyl-L-Leucyl-L-Leucyl-L-norleucinal (ALLN). Using class-specific protease inhibitors, we observed that ALLN's effect resulted from the blockade of calpain and cathepsin protease activities. Cell-free proteolysis assay confirmed that both proteases were involved in glutamate-induced alteration in GAD protein levels. Together these results suggest that glutamate-induced excitotoxic stimulation of NMDAR in cultured cortical neurons leads to altered GAD protein levels from GABAergic neurons through intracellular calcium increase and protease activation including calpain and cathepsin. Biochemical alterations in surviving cortical GABAergic neurons in various disease states may contribute to the altered balance between excitation

  11. Neuronal Activity and Glutamate Uptake Decrease Mitochondrial Mobility in Astrocytes and Position Mitochondria Near Glutamate Transporters

    Science.gov (United States)

    Jackson, Joshua G.; O'Donnell, John C.; Takano, Hajime; Coulter, Douglas A.

    2014-01-01

    Within neurons, mitochondria are nonuniformly distributed and are retained at sites of high activity and metabolic demand. Glutamate transport and the concomitant activation of the Na+/K+-ATPase represent a substantial energetic demand on astrocytes. We hypothesized that mitochondrial mobility within astrocytic processes might be regulated by neuronal activity and glutamate transport. We imaged organotypic hippocampal slice cultures of rat, in which astrocytes maintain their highly branched morphologies and express glutamate transporters. Using time-lapse confocal microscopy, the mobility of mitochondria within individual astrocytic processes and neuronal dendrites was tracked. Within neurons, a greater percentage of mitochondria were mobile than in astrocytes. Furthermore, they moved faster and farther than in astrocytes. Inhibiting neuronal activity with tetrodotoxin (TTX) increased the percentage of mobile mitochondria in astrocytes. Mitochondrial movement in astrocytes was inhibited by vinblastine and cytochalasin D, demonstrating that this mobility depends on both the microtubule and actin cytoskeletons. Inhibition of glutamate transport tripled the percentage of mobile mitochondria in astrocytes. Conversely, application of the transporter substrate d-aspartate reversed the TTX-induced increase in the percentage of mobile mitochondria. Inhibition of reversed Na+/Ca2+ exchange also increased the percentage of mitochondria that were mobile. Last, we demonstrated that neuronal activity increases the probability that mitochondria appose GLT-1 particles within astrocyte processes, without changing the proximity of GLT-1 particles to VGLUT1. These results imply that neuronal activity and the resulting clearance of glutamate by astrocytes regulate the movement of astrocytic mitochondria and suggest a mechanism by which glutamate transporters might retain mitochondria at sites of glutamate uptake. PMID:24478345

  12. Developmental expression of glutamate transporters and glutamate dehydrogenase in astrocytes of the postnatal rat hippocampus.

    Science.gov (United States)

    Kugler, Peter; Schleyer, Verena

    2004-01-01

    Glutamate is the major excitatory transmitter in the CNS and plays distinct roles in a number of developmental events. Its extracellular concentration, which mediates these activities, is regulated by glutamate transporters in glial cells and neurons. In the present study, we have used nonradioactive in situ hybridization, immunocytochemistry, and immunoblotting to show the cellular and regional expression of the high-affinity glutamate transporters GLAST (EAAT1) and generic GLT1 (EAAT2; glial form of GLT1) in the rat hippocampus during postnatal development (P1-60). The results of transporter expression were compared with the localization and activity pattern of glutamate dehydrogenase (GDH), an important glutamate-metabolizing enzyme. The study showed that both transporters and GDH were demonstrable at P1 (day of birth). The expression of GLAST (detected by in situ hybridization and immunocytochemistry) in the early postnatal development was higher than GLT1. Thereafter, the expression of both transporters increased, showing adult levels at between P20 and P30 (detected by in situ hybridization and immunoblotting). At these time points, the expression of GLT1 appeared to be significantly higher than the GLAST expression. GLT1 and GLAST proteins were demonstrable only in astrocytes. The increase of GDH activities (steepest increase from P5-P8), which were localized preferentially in astrocytes, was in agreement with the increase of transporter expression, preferentially with that of GLT1. These observations suggest that the extent of glutamate transporter expression and of glutamate-metabolizing GDH activity in astrocytes is intimately correlated with the formation of glutamatergic synapses in the developing hippocampus. 2004 Wiley-Liss, Inc.

  13. The Glutamine-Glutamate/GABA Cycle

    DEFF Research Database (Denmark)

    Walls, Anne B; Waagepetersen, Helle S; Bak, Lasse Kristoffer

    2015-01-01

    The operation of a glutamine-glutamate/GABA cycle in the brain consisting of the transfer of glutamine from astrocytes to neurons and neurotransmitter glutamate or GABA from neurons to astrocytes is a well-known concept. In neurons, glutamine is not only used for energy production and protein...... synthesis, as in other cells, but is also an essential precursor for biosynthesis of amino acid neurotransmitters. An excellent tool for the study of glutamine transfer from astrocytes to neurons is [(14)C]acetate or [(13)C]acetate and the glial specific enzyme inhibitors, i.e. the glutamine synthetase...... inhibitor methionine sulfoximine and the tricarboxylic acid cycle (aconitase) inhibitors fluoro-acetate and -citrate. Acetate is metabolized exclusively by glial cells, and [(13)C]acetate is thus capable when used in combination with magnetic resonance spectroscopy or mass spectrometry, to provide...

  14. Binding thermodynamics of a glutamate transporter homologue

    Science.gov (United States)

    Reyes, Nicolas; Oh, SeCheol; Boudker, Olga

    2013-01-01

    Glutamate transporters catalyze concentrative uptake of the neurotransmitter into glial cells and neurons. Their transport cycle involves binding and release of the substrate on the extra- and intracellular sides of the plasma membranes, and translocation of the substrate-binding site across the lipid bilayers. The energy of the ionic gradients, mainly sodium, fuels the cycle. Here, we used a cross-linking approach to trap a glutamate transporter homologue from Pyrococcus horikoshii in key conformational states with substrate-binding site facing either the extracellular or intracellular sides of the membrane to study their binding thermodynamics. We show that the chemical potential of sodium ions in solution is exclusively coupled to substrate binding and release, and not to substrate translocation. Despite the structural symmetry, the binding mechanisms are distinct on the opposite sides of the membrane and more complex than the current models suggest. PMID:23563139

  15. Glutamate dehydrogenase (RocG) in Bacillus licheniformis WX-02: Enzymatic properties and specific functions in glutamic acid synthesis for poly-γ-glutamic acid production.

    Science.gov (United States)

    Tian, Guangming; Wang, Qin; Wei, Xuetuan; Ma, Xin; Chen, Shouwen

    2017-04-01

    Poly-γ-glutamic acid (γ-PGA), a natural biopolymer, is widely used in cosmetics, medicine, food, water treatment, and agriculture owing to its features of moisture sequestration, cation chelation, non-toxicity and biodegradability. Intracellular glutamic acid, the substrate of γ-PGA, is a limiting factor for high yield in γ-PGA production. Bacillus subtilis and Bacillus licheniformis are both important γ-PGA producing strains, and B. subtilis synthesizes glutamic acid in vivo using the unique GOGAT/GS pathway. However, little is known about the glutamate synthesis pathway in B. licheniformis. The aim of this work was to characterize the glutamate dehydrogenase (RocG) in glutamic acid synthesis from B. licheniformis with both in vivo and in vitro experiments. By re-directing the carbon flux distribution, the rocG gene deletion mutant WX-02ΔrocG produced intracellular glutamic acid with a concentration of 90ng/log(CFU), which was only 23.7% that of the wild-type WX-02 (380ng/log(CFU)). Furthermore, the γ-PGA yield of mutant WX-02ΔrocG was 5.37g/L, a decrease of 45.3% compared to the wild type (9.82g/L). In vitro enzymatic assays of RocG showed that RocG has higher affinity for 2-oxoglutarate than glutamate, and the glutamate synthesis rate was far above degradation. This is probably the first study to reveal the glutamic acid synthesis pathway and the specific functions of RocG in B. licheniformis. The results indicate that γ-PGA production can be enhanced through improving intracellular glutamic acid synthesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Synaptically evoked glutamate transporter currents in Spinal Dorsal Horn Astrocytes

    Directory of Open Access Journals (Sweden)

    Dougherty Patrick M

    2009-07-01

    Full Text Available Abstract Background Removing and sequestering synaptically released glutamate from the extracellular space is carried out by specific plasma membrane transporters that are primarily located in astrocytes. Glial glutamate transporter function can be monitored by recording the currents that are produced by co-transportation of Na+ ions with the uptake of glutamate. The goal of this study was to characterize glutamate transporter function in astrocytes of the spinal cord dorsal horn in real time by recording synaptically evoked glutamate transporter currents. Results Whole-cell patch clamp recordings were obtained from astrocytes in the spinal substantia gelatinosa (SG area in spinal slices of young adult rats. Glutamate transporter currents were evoked in these cells by electrical stimulation at the spinal dorsal root entry zone in the presence of bicuculline, strychnine, DNQX and D-AP5. Transporter currents were abolished when synaptic transmission was blocked by TTX or Cd2+. Pharmacological studies identified two subtypes of glutamate transporters in spinal astrocytes, GLAST and GLT-1. Glutamate transporter currents were graded with stimulus intensity, reaching peak responses at 4 to 5 times activation threshold, but were reduced following low-frequency (0.1 – 1 Hz repetitive stimulation. Conclusion These results suggest that glutamate transporters of spinal astrocytes could be activated by synaptic activation, and recording glutamate transporter currents may provide a means of examining the real time physiological responses of glial cells in spinal sensory processing, sensitization, hyperalgesia and chronic pain.

  17. Glutamine and glutamate as vital metabolites

    Directory of Open Access Journals (Sweden)

    Newsholme P.

    2003-01-01

    Full Text Available Glucose is widely accepted as the primary nutrient for the maintenance and promotion of cell function. This metabolite leads to production of ATP, NADPH and precursors for the synthesis of macromolecules such as nucleic acids and phospholipids. We propose that, in addition to glucose, the 5-carbon amino acids glutamine and glutamate should be considered to be equally important for maintenance and promotion of cell function. The functions of glutamine/glutamate are many, i.e., they are substrates for protein synthesis, anabolic precursors for muscle growth, they regulate acid-base balance in the kidney, they are substrates for ureagenesis in the liver and for hepatic and renal gluconeogenesis, they act as an oxidative fuel for the intestine and cells of the immune system, provide inter-organ nitrogen transport, and act as precursors of neurotransmitter synthesis, of nucleotide and nucleic acid synthesis and of glutathione production. Many of these functions are interrelated with glucose metabolism. The specialized aspects of glutamine/glutamate metabolism of different glutamine-utilizing cells are discussed in the context of glucose requirements and cell function.

  18. Glutamate production from ammonia via glutamate dehydrogenase 2 activity supports cancer cell proliferation under glutamine depletion.

    Science.gov (United States)

    Takeuchi, Yukiko; Nakayama, Yasumune; Fukusaki, Eiichiro; Irino, Yasuhiro

    2018-01-01

    Cancer cells rapidly consume glutamine as a carbon and nitrogen source to support proliferation, but the cell number continues to increase exponentially after glutamine is nearly depleted from the medium. In contrast, cell proliferation rates are strongly depressed when cells are cultured in glutamine-free medium. How cancer cells survive in response to nutrient limitation and cellular stress remains poorly understood. In addition, rapid glutamine catabolism yields ammonia, which is a potentially toxic metabolite that is secreted into the extracellular space. Here, we show that ammonia can be utilized for glutamate production, leading to cell proliferation under glutamine-depleted conditions. This proliferation requires glutamate dehydrogenase 2, which synthesizes glutamate from ammonia and α-ketoglutarate and is expressed in MCF7 and T47D cells. Our findings provide insight into how cancer cells survive under glutamine deprivation conditions and thus contribute to elucidating the mechanisms of tumor growth. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. A novel glutamate transport system in poly(γ-glutamic acid)-producing strain Bacillus subtilis CGMCC 0833.

    Science.gov (United States)

    Wu, Qun; Xu, Hong; Zhang, Dan; Ouyang, Pingkai

    2011-08-01

    Bacillus subtilis CGMCC 0833 is a poly(γ-glutamic acid) (γ-PGA)-producing strain. It has the capacity to tolerate high concentration of extracellular glutamate and to utilize glutamate actively. Such a high uptake capacity was owing to an active transport system for glutamate. Therefore, a specific transport system for L-glutamate has been observed in this strain. It was a novel transport process in which glutamate was symported with at least two protons, and an inward-directed sodium gradient had no stimulatory effect on it. K(m) and V(m) for glutamate transport were estimated to be 67 μM and 152 nmol⁻¹ min⁻¹ mg⁻¹ of protein, respectively. The transport system showed structural specificity and stereospecificity and was strongly dependent on extracellular pH. Moreover, it could be stimulated by Mg²⁺, NH₄⁺, and Ca²⁺. In addition, the glutamate transporter in this strain was studied at the molecular level. As there was no important mutation of the transporter protein, it appeared that the differences of glutamate transporter properties between this strain and other B. subtilis strains were not due to the differences of the amino acid sequence and the structure of transporter protein. This is the first extensive report on the properties of glutamate transport system in γ-PGA-producing strain.

  20. siRNA knock down of glutamate dehydrogenase in astrocytes affects glutamate metabolism leading to extensive accumulation of the neuroactive amino acids glutamate and aspartate.

    Science.gov (United States)

    Skytt, Dorte M; Klawonn, Anna M; Stridh, Malin H; Pajęcka, Kamilla; Patruss, Yasar; Quintana-Cabrera, Ruben; Bolaños, Juan P; Schousboe, Arne; Waagepetersen, Helle S

    2012-09-01

    Glutamate is the most abundant excitatory neurotransmitter in the brain and astrocytes are key players in sustaining glutamate homeostasis. Astrocytes take up the predominant part of glutamate after neurotransmission and metabolism of glutamate is necessary for a continuous efficient removal of glutamate from the synaptic area. Glutamate may either be amidated by glutamine synthetase or oxidatively metabolized in the mitochondria, the latter being at least to some extent initiated by oxidative deamination by glutamate dehydrogenase (GDH). To explore the particular importance of GDH for astrocyte metabolism we have knocked down GDH in cultured cortical astrocytes employing small interfering RNA (siRNA) achieving a reduction of the enzyme activity by approximately 44%. The astrocytes were incubated for 2h in medium containing either 1.0mM [(15)NH(4)(+)] or 100 μM [(15)N]glutamate. For those exposed to [(15)N]glutamate an additional 100 μM was added after 1h. Metabolic mapping was performed from isotope incorporation measured by mass spectrometry into relevant amino acids of cell extracts and media. The contents of the amino acids were measured by HPLC. The (15)N incorporation from [(15)NH(4)(+)] into glutamate, aspartate and alanine was decreased in astrocytes exhibiting reduced GDH activity. However, the reduced GDH activity had no effect on the cellular contents of these amino acids. This supports existing in vivo and in vitro studies that GDH is predominantly working in the direction of oxidative deamination and not reductive amination. In contrast, when exposing the astrocytes to [(15)N]glutamate, the reduced GDH activity led to an increased (15)N incorporation into glutamate, aspartate and alanine and a large increase in the content of glutamate and aspartate. Surprisingly, this accumulation of glutamate and net-synthesis of aspartate were not reflected in any alterations in either the glutamine content or labeling, but a slight increase in mono labeling of

  1. From the Cover: Glutamate antagonists limit tumor growth

    Science.gov (United States)

    Rzeski, Wojciech; Turski, Lechoslaw; Ikonomidou, Chrysanthy

    2001-05-01

    Neuronal progenitors and tumor cells possess propensity to proliferate and to migrate. Glutamate regulates proliferation and migration of neurons during development, but it is not known whether it influences proliferation and migration of tumor cells. We demonstrate that glutamate antagonists inhibit proliferation of human tumor cells. Colon adenocarcinoma, astrocytoma, and breast and lung carcinoma cells were most sensitive to the antiproliferative effect of the N-methyl-D-aspartate antagonist dizocilpine, whereas breast and lung carcinoma, colon adenocarcinoma, and neuroblastoma cells responded most favorably to the -amino-3-hydroxy-5-methyl-4-isoxazole-propionate antagonist GYKI52466. The antiproliferative effect of glutamate antagonists was Ca2+ dependent and resulted from decreased cell division and increased cell death. Morphological alterations induced by glutamate antagonists in tumor cells consisted of reduced membrane ruffling and pseudopodial protrusions. Furthermore, glutamate antagonists decreased motility and invasive growth of tumor cells. These findings suggest anticancer potential of glutamate antagonists.

  2. Glutamate Transporters in the Blood-Brain Barrier

    DEFF Research Database (Denmark)

    Helms, Hans Christian Cederberg; Nielsen, Carsten Uhd; Waagepetersen, Helle Sønderby

    2017-01-01

    The amino acid L-glutamate serves a number of roles in the central nervous system, being an excitatory neurotransmitter, metabolite, and building block in protein synthesis. During pathophysiological events, where L-glutamate homeostasis cannot be maintained, the increased brain interstitial fluid...... studies have demonstrated blood-to-brain transport of L-glutamate, at least during pathological events. A number of studies have shown that brain endothelial cells express excitatory amino acid transporters, which may account for abluminal concentrative uptake of L-glutamate into the capillary endothelial...... concentration of L-glutamate causes excitotoxicity. A tight control of the brain interstitial fluid L-glutamate levels is therefore imperative, in order to maintain optimal neurotransmission and to avoid such excitotoxicity. The blood-brain barrier, i.e., the endothelial lining of the brain capillaries...

  3. [Determination of glutamic acid in biological material by capillary electrophoresis].

    Science.gov (United States)

    Narezhnaya, E; Krukier, I; Avrutskaya, V; Degtyareva, A; Igumnova, E A

    2015-01-01

    The conditions for the identification and determination of Glutamic acid by capillary zone electrophoresis without their preliminary derivatization have been optimized. The effect of concentration of buffer electrolyte and pH on determination of Glutamic acid has been investigated. It is shown that the 5 Mm borate buffer concentration and a pH 9.15 are optimal. Quantitative determination of glutamic acid has been carried out using a linear dependence between the concentration of the analyte and the area of the peak. The accuracy and reproducibility of the determination are confirmed by the method "introduced - found". Glutamic acid has been determined in the placenta homogenate. The duration of analysis doesn't exceed 30 minutes. The results showed a decrease in the level of glutamic acid in cases of pregnancy complicated by placental insufficiency compared with the physiological, and this fact allows to consider the level of glutamic acid as a possible marker of complicated pregnancy.

  4. 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.

  5. Relationship between Increase in Astrocytic GLT-1 Glutamate Transport and Late-LTP

    Science.gov (United States)

    Pita-Almenar, Juan D.; Zou, Shengwei; Colbert, Costa M.; Eskin, Arnold

    2012-01-01

    Na[superscript +]-dependent high-affinity glutamate transporters have important roles in the maintenance of basal levels of glutamate and clearance of glutamate during synaptic transmission. Interestingly, several studies have shown that basal glutamate transport displays plasticity. Glutamate uptake increases in hippocampal slices during early…

  6. Bidirectional regulation of thermotaxis by glutamate transmissions in Caenorhabditis elegans

    OpenAIRE

    Ohnishi, Noriyuki; Kuhara, Atsushi; Nakamura, Fumiya; Okochi, Yoshifumi; Mori, Ikue

    2011-01-01

    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 thermosenso...

  7. Pharmacological Treatment of Glutamate Excitotoxicity Following Traumatic Brain Injury

    Science.gov (United States)

    2009-01-14

    In 1969, Olney found that subcutaneous injection of monosodium glutamate resulted in necrotic brain lesions in the hypothalamus of newborn mice...Thesis: "Pharmacological Treatment of Glutamate Excitotoxicity Following Traumatic Brain Injury" Name of Candidate: Michael Doh Molecular & Cell...TYPE 3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Pharmacological Treatment Of Glutamate Excitotoxicity Following Traumatic

  8. Glutamate monitoring in vitro and in vivo: recent progress in the field of glutamate biosensors

    DEFF Research Database (Denmark)

    Rieben, Nathalie Ines; Rose, Nadia Cherouati; Martinez, Karen Laurence

    2009-01-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. It is involved in numerous important brain functions such as learning, memory and cognition, as well as the development and plasticity of the central nervous system. In order to ensure efficient signal...... transmission, glutamate is highly compartmentalized. Prolonged elevated extracellular levels of glutamate have been shown to be excitotoxic with the result of neuronal cell death ultimately. Furthermore, alterations in glutamate levels have been shown to be linked to several neurodegenerative disorders...... such as Alzheimer's, Parkinson's and Huntington's diseases, as well as ischemic stroke and amyotrophic lateral sclerosis. Accurate measurement of glutamate levels in vitro and in vivo for a better understanding of the physiological and pathological role of glutamate in neurotransmission has remained challenging...

  9. In situ measurement of glutamate concentrations in the periportal, intermediate, and pericentral zones of rat liver

    NARCIS (Netherlands)

    Geerts, W. J.; Jonker, A.; Boon, L.; Meijer, A. J.; Charles, R.; van Noorden, C. J.; Lamers, W. H.

    1997-01-01

    We developed a quantitative histochemical assay for measurement of local glutamate concentrations in cryostat sections of rat liver. Deamination of glutamate by glutamate dehydrogenase (GDH) was coupled to the production of formazan and formazan precipitation was used for colorimetric visualization.

  10. Identification and characterization of a bacterial glutamic peptidase.

    Science.gov (United States)

    Jensen, Kenneth; Østergaard, Peter R; Wilting, Reinhard; Lassen, Søren F

    2010-12-01

    Glutamic peptidases, from the MEROPS family G1, are a distinct group of peptidases characterized by a catalytic dyad consisting of a glutamate and a glutamine residue, optimal activity at acidic pH and insensitivity towards the microbial derived protease inhibitor, pepstatin. Previously, only glutamic peptidases derived from filamentous fungi have been characterized. We report the first characterization of a bacterial glutamic peptidase (pepG1), derived from the thermoacidophilic bacteria Alicyclobacillus sp. DSM 15716. The amino acid sequence identity between pepG1 and known fungal glutamic peptidases is only 24-30% but homology modeling, the presence of the glutamate/glutamine catalytic dyad and a number of highly conserved motifs strongly support the inclusion of pepG1 as a glutamic peptidase. Phylogenetic analysis places pepG1 and other putative bacterial and archaeal glutamic peptidases in a cluster separate from the fungal glutamic peptidases, indicating a divergent and independent evolution of bacterial and fungal glutamic peptidases. Purification of pepG1, heterologously expressed in Bacillus subtilis, was performed using hydrophobic interaction chromatography and ion exchange chromatography. The purified peptidase was characterized with respect to its physical properties. Temperature and pH optimums were found to be 60°C and pH 3-4, in agreement with the values observed for the fungal members of family G1. In addition, pepG1 was found to be pepstatin-insensitive, a characteristic signature of glutamic peptidases. Based on the obtained results, we suggest that pepG1 can be added to the MEROPS family G1 as the first characterized bacterial member.

  11. Identification and characterization of a bacterial glutamic peptidase

    Directory of Open Access Journals (Sweden)

    Jensen Kenneth

    2010-12-01

    Full Text Available Abstract Background Glutamic peptidases, from the MEROPS family G1, are a distinct group of peptidases characterized by a catalytic dyad consisting of a glutamate and a glutamine residue, optimal activity at acidic pH and insensitivity towards the microbial derived protease inhibitor, pepstatin. Previously, only glutamic peptidases derived from filamentous fungi have been characterized. Results We report the first characterization of a bacterial glutamic peptidase (pepG1, derived from the thermoacidophilic bacteria Alicyclobacillus sp. DSM 15716. The amino acid sequence identity between pepG1 and known fungal glutamic peptidases is only 24-30% but homology modeling, the presence of the glutamate/glutamine catalytic dyad and a number of highly conserved motifs strongly support the inclusion of pepG1 as a glutamic peptidase. Phylogenetic analysis places pepG1 and other putative bacterial and archaeal glutamic peptidases in a cluster separate from the fungal glutamic peptidases, indicating a divergent and independent evolution of bacterial and fungal glutamic peptidases. Purification of pepG1, heterologously expressed in Bacillus subtilis, was performed using hydrophobic interaction chromatography and ion exchange chromatography. The purified peptidase was characterized with respect to its physical properties. Temperature and pH optimums were found to be 60°C and pH 3-4, in agreement with the values observed for the fungal members of family G1. In addition, pepG1 was found to be pepstatin-insensitive, a characteristic signature of glutamic peptidases. Conclusions Based on the obtained results, we suggest that pepG1 can be added to the MEROPS family G1 as the first characterized bacterial member.

  12. 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.

  13. Novel Inhibitors Complexed with Glutamate Dehydrogenase

    Science.gov (United States)

    Li, Ming; Smith, Christopher J.; Walker, Matthew T.; Smith, Thomas J.

    2009-01-01

    Mammalian glutamate dehydrogenase (GDH) is a homohexameric enzyme that catalyzes the reversible oxidative deamination of l-glutamate to 2-oxoglutarate using NAD(P)+ as coenzyme. Unlike its counterparts from other animal kingdoms, mammalian GDH is regulated by a host of ligands. The recently discovered hyperinsulinism/hyperammonemia disorder showed that the loss of allosteric inhibition of GDH by GTP causes excessive secretion of insulin. Subsequent studies demonstrated that wild-type and hyperinsulinemia/hyperammonemia forms of GDH are inhibited by the green tea polyphenols, epigallocatechin gallate and epicatechin gallate. This was followed by high throughput studies that identified more stable inhibitors, including hexachlorophene, GW5074, and bithionol. Shown here are the structures of GDH complexed with these three compounds. Hexachlorophene forms a ring around the internal cavity in GDH through aromatic stacking interactions between the drug and GDH as well as between the drug molecules themselves. In contrast, GW5074 and bithionol both bind as pairs of stacked compounds at hexameric 2-fold axes between the dimers of subunits. The internal core of GDH contracts when the catalytic cleft closes during enzymatic turnover. None of the drugs cause conformational changes in the contact residues, but all bind to key interfaces involved in this contraction process. Therefore, it seems likely that the drugs inhibit enzymatic turnover by inhibiting this transition. Indeed, this expansion/contraction process may play a major role in the inter-subunit communication and allosteric regulation observed in GDH. PMID:19531491

  14. 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.

  15. Influence of the glutamic acid content of the diet on the catabolic rate of labelled glutamic acid in rats. 3

    International Nuclear Information System (INIS)

    Simon, O.; Wilke, A.; Bergner, H.

    1984-01-01

    Mal rats received during a 8 days experimental feeding period diets with different contents in glutamic acid. The daily feed intake was restricted to the energy maintenance level of 460 kJ/kg/sup 0.75/. The diet contained a mixture of L-amino acids corresponding to the pattern of egg protein except glutamic acid. Glutamic acid was added successively at 10 levels (0 to 14.8 % of dry matter) and the resulting diets were fed to groups of 4 animals each. At the end of the experimental feeding period 14 C- and 15 N-labelled glutamic acid were applied by intragastric infusion. CO 2 and 14 CO 2 excretion was measured during the following 4 hours and the urinary N and 15 N excretion during the following 24 hours. The CO 2 excretion decreased from 53 to 44 mmol CO 2 /100g body weight with increasing levels of dietary glutamic acid. This change seems to result from the increasing proportion of amino acids as an energetic fuel. While the amount of oxidized glutamic acid increased with increasing supplements of glutamic acid the relative 14 CO 2 excretion decreased from 57 to 48 % of the applied radioactivity. The urinary 15 N excretion during 24 hours was 31 % of the given amount of 15 N if no glutamic acid was included in the diet. This proportion increased successively up to 52 % in the case of the highest supply of glutamic acid. Because the total N excretion increased at the same extent as the 15 N excretion a complete mixing of the NH 2 groups resulting from glutamic acid due to desamination with the ammonia pool was assumed. No correlation between glutamic acid content of the diet and specific radioactivity of CO 2 or atom-% 15 N excess of urinary N was observed. (author)

  16. Application of a glutamate microsensor to brain tissue

    NARCIS (Netherlands)

    Oldenziel, Weite Hendrik

    2006-01-01

    The amino acid l-glutamate is one of the most important neurotransmitters in the central nervous system (CNS). It is involved in many physiological processes and consequently in the pathophysiology of several psychiatric, neurological and neurodegenerative disorders. Therefore, glutamate is an

  17. Histochemical Studies of the Effects of Monosodium Glutamate on ...

    African Journals Online (AJOL)

    Background: Monosodium glutamate (MSG) is a commonly used food additive and there is growing concern that excitotoxins such as MSG play a critical role in the development of several hepatic disorders. Objectives: The histochemical effect of monosodium glutamate was investigated on the liver of adult Wistar rats.

  18. probing the cob(ii)alamin conductor hypothesis with glutamate ...

    African Journals Online (AJOL)

    dell

    Glutamate mutase activity was also demonstrated upon incubation of GlmS and E with 3',5'- ... overproduced in E.coli (Huhta et al. 2001,. Huhta et ..... Biochemistry. 37: 9704-9715. Buckel W 2001 Unusual enzymes involved in five pathways of glutamate fermentation. Appl. Microbiol. Biotechnol. 57: 263-273. Buckel W and ...

  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. 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.

  1. Microscopic picture of the aqueous solvation of glutamic acid

    NARCIS (Netherlands)

    Leenders, E.J.M.; Bolhuis, P.G.; Meijer, E.J.

    2008-01-01

    We present molecular dynamics simulations of glutamic acid and glutamate solvated in water, using both density functional theory (DFT) and the Gromos96 force field. We focus on the microscopic aspects of the solvation−particularly on the hydrogen bond structures and dynamics−and investigate the

  2. Some Properties of Glutamate Dehydrogenase from the Marine Red ...

    African Journals Online (AJOL)

    Keywords: ammonia assimilation, glutamate dehydrogenase, GDH, Gracilaria sordida, red alga, enzyme activity. Glutamate dehydrogenases (GDH, EC ... Anabolic functions could be assimilation of ammonia released during photorespiration and synthesis of N-rich transport compounds. Western Indian Ocean Journal of ...

  3. Surface grafting of poly(L-glutamates). 3. Block copolymerization

    NARCIS (Netherlands)

    Wieringa, RH; Siesling, EA; Werkman, PJ; Vorenkamp, EJ; Schouten, AJ

    2001-01-01

    This paper describes for the first time the synthesis of surface-grafted AB-block copolypeptides, consisting of poly(gamma -benzyl L-glutamate) (PBLG) as the A-block and poly(gamma -methyl L-glutamate) (PMLG) as the B-block. Immobilized primary amine groups of (,gamma -aminopropyl)triethoxysilane

  4. 21 CFR 522.1125 - Hemoglobin glutamer-200 (bovine).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hemoglobin glutamer-200 (bovine). 522.1125 Section... (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS § 522.1125 Hemoglobin glutamer-200 (bovine). (a) Specifications. Each 125 milliliter bag contains 13...

  5. Electrochemical Synthesis of Polypyrrole Layers Doped with Glutamic Ions

    NARCIS (Netherlands)

    Meteleva-Fischer, Yulia V.; Von Hauff, Elizabeth; Parisi, Juergen

    2009-01-01

    Electrochemically synthesized polypyrrole thin films doped with glutamic ions were investigated as interesting materials for potential use as molecularly selective surfaces. Pyrrole and glutamate interact in aqueous solution, resulting in the formation of a prominent band at 240 nm in the absorption

  6. Dietary glutamate will not affect pain in fibromyalgia

    NARCIS (Netherlands)

    Geenen, R.; Janssens, E.L.; Jacobs, J.W.G.; Staveren, van W.A.

    2004-01-01

    Injection of glutamate into the masseter muscle has been suggested-to evoke an increase in intensity of and sensitivity to pain. A case study showed that a diet low in monosodium glutamate (MSG) might accomplish pain relief in fibromyalgia (FM). To clarify the possible pain-modulating effect of

  7. Histological Studies of the Effects of Monosodium Glutamate on the ...

    African Journals Online (AJOL)

    Background: Monosodium glutamate (MSG) is a commonly used food additive and there is growing concern that this may play a critical role in the aethiopathogenesis of anovulatory infertility. Objectives: The effect of monosodium glutamate (MSG) used as food additive on the ovaries of adult Wistar rat was investigated.

  8. Astrocytes revisited: concise historic outlook on glutamate homeostasis and signaling

    Science.gov (United States)

    Parpura, Vladimir; Verkhratsky, Alexei

    2012-01-01

    Astroglia is a main type of brain neuroglia, which includes many cell sub-types that differ in their morphology and physiological properties and yet are united by the main function, which is the maintenance of brain homeostasis. Astrocytes employ a variety of mechanisms for communicating with neuronal networks. The communication mediated by neurotransmitter glutamate has received a particular attention. Glutamate is de novo synthesized exclusively in astrocytes; astroglia-derived glutamine is the source of glutamate for neurons. Glutamate is released from both neurons and astroglia through exocytosis, although various other mechanisms may also play a role. Glutamate-activated specific receptors trigger excitatory responses in neurons and astroglia. Here we overview main properties of glutamatergic transmission in neuronal-glial networks and identify some future challenges facing the field. PMID:23275317

  9. 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

  10. Production of poly-γ-glutamic acid by a thermotolerant glutamate-independent strain and comparative analysis of the glutamate dependent difference.

    Science.gov (United States)

    Zeng, Wei; Chen, Guiguang; Guo, Ye; Zhang, Bin; Dong, Mengna; Wu, Yange; Wang, Jun; Che, Zhiqun; Liang, Zhiqun

    2017-11-25

    Poly-γ-glutamic acid (γ-PGA) is a promising microbial polymer with wide applications in industry, agriculture and medicine. In this study, a novel glutamate-independent γ-PGA producing strain with thermotolerant characteristics was isolated and identified as Bacillus subtilis GXG-5, then its product was also characterized. The fermentation process was optimized by single-factor tests, and results showed that high temperature (50 °C) was especially suitable for the γ-PGA production by GXG-5. The γ-PGA yield reached 19.50 ± 0.75 g/L with substrate conversion efficiency of 78% at 50 °C in 10 L fermentor. Comparison of GXG-5 and GXA-28 (glutamate-dependent strain) under respective optimal fermentation conditions, the γ-PGA yield of GXG-5 was 19.0% higher than that of GXA-28, and GXG-5 was also superior to GXA-28 in the availability of carbon sources and substrates. Furthermore, the glutamate dependent difference between GXA-28 and GXG-5 was analyzed by genomic sequencing, results indicated that genes related to the glutamate dependent difference mainly involved in carbohydrate transport and metabolism and amino acid metabolism, and 13 genes related to γ-PGA synthesis were mutated in GXG-5. This study provided a potential glutamate-independent strain to replace glutamate-dependent strain for γ-PGA production, and shared novel information for understanding the glutamate dependent difference at the genomic level.

  11. 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.

  12. Glutamate-induced glutamate release: A proposed mechanism for calcium bursting in astrocytes

    Science.gov (United States)

    Larter, Raima; Craig, Melissa Glendening

    2005-12-01

    Here we present a new model for the generation of complex calcium-bursting patterns in astrocytes, a type of brain cell recently implicated in a variety of neural functions including memory formation. The model involves two positive feedback processes, in which the key feedback species are calcium ion and glutamate. The latter is the most abundant excitatory neurotransmitter in the brain and has been shown to be involved in bidirectional communication between astrocytes and nearby neurons. The glutamate feedback process considered here is shown to be critical for the generation of complex bursting oscillations in the astrocytes and to, perhaps, code for information which may be passed from neuron to neuron via the astrocyte. These processes may be involved in memory storage and formation as well as in mechanisms which lead to dynamical diseases such as epilepsy.

  13. Calcium regulates glutamate dehydrogenase and poly-γ-glutamic acid synthesis in Bacillus natto.

    Science.gov (United States)

    Meng, Yonghong; Dong, Guiru; Zhang, Chen; Ren, Yuanyuan; Qu, Yuling; Chen, Weifeng

    2016-04-01

    To study the effect of Ca(2+) on glutamate dehydrogenase (GDH) and its role in poly-γ-glutamic acid (γ-PGA) synthesis in Bacillus natto HSF 1410. When the concentration of Ca(2+) varied from 0 to 0.1 g/l in the growth medium of B. natto HSF 1410, γ-PGA production increased from 6.8 to 9.7 g/l, while GDH specific activity and NH4Cl consumption improved from 183 to 295 U/mg and from 0.65 to 0.77 g/l, respectively. GDH with α-ketoglutarate as substrate primarily used NADPH as coenzyme with a K m of 0.08 mM. GDH was responsible for the synthesis of endogenous glutamate. The specific activity of GDH remained essentially unchanged in the presence of CaCl2 (0.05-0.2 g/l) in vitro. However, the specific activity of GDH and its expression was significantly increased by CaCl2 in vivo. Therefore, the regulation of GDH and PGA synthesis by Ca(2+) is an intracellular process. Calcium regulation may be an effective approach for producing γ-PGA on an industrial scale.

  14. Glutamate and GABA in appetite regulation

    Directory of Open Access Journals (Sweden)

    Teresa Cardoso Delgado

    2013-08-01

    Full Text Available Appetite is regulated by a coordinated interplay between gut, adipose tissue and brain. A primary site for the regulation of appetite is the hypothalamus where interaction between orexigenic neurons, expressing Neuropeptide Y/Agouti-related protein, and anorexigenic neurons, expressing Pro-opiomelanocortin cocaine/Amphetamine-related transcript, controls energy homeostasis. Within the hypothalamus, several peripheral signals have been shown to modulate the activity of these neurons, including the orexigenic peptide ghrelin and the anorexigenic hormones insulin and leptin. In addition to the accumulated knowledge on neuropeptide signaling, presence and function of amino acid neurotransmitters in key hypothalamic neurons brought a new light into appetite regulation. Therefore, the principal aim of this review will be to describe the current knowledge of the role of amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation and the associated neuronal-astrocytic metabolic coupling mechanisms.Glutamate and GABA dominate synaptic transmission in the hypothalamus and administration of their receptors agonists into hypothalamic nuclei stimulates feeding. By using 13C High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy based analysis, the Cerdán group has shown that increased neuronal firing in mice hypothalamus, as triggered by appetite during the feeding-fasting paradigm, may stimulate the use of lactate as neuronal fuel leading to increased astrocytic glucose consumption and glycolysis. Moreover, fasted mice showed increased hypothalamic [2-13C]GABA content, which may be explained by the existence of GABAergic neurons in key appetite regulation hypothalamic nuclei. Interestingly, increased [2-13C]GABA concentration in the hypothalamus of fasted animals appears to result mainly from reduction in GABA metabolizing pathways, rather than increased GABA synthesis by augmented activity of the

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

    International Nuclear Information System (INIS)

    O'Shea, R.D.

    2001-01-01

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

  16. Evidence for glutamate as a neuroglial transmitter within sensory ganglia.

    Science.gov (United States)

    Kung, Ling-Hsuan; Gong, Kerui; Adedoyin, Mary; Ng, Johnson; Bhargava, Aditi; Ohara, Peter T; Jasmin, Luc

    2013-01-01

    This study examines key elements of glutamatergic transmission within sensory ganglia of the rat. We show that the soma of primary sensory neurons release glutamate when depolarized. Using acute dissociated mixed neuronal/glia cultures of dorsal root ganglia (DRG) or trigeminal ganglia and a colorimetric assay, we show that when glutamate uptake by satellite glial cells (SGCs) is inhibited, KCl stimulation leads to simultaneous increase of glutamate in the culture medium. With calcium imaging we see that the soma of primary sensory neurons and SGCs respond to AMPA, NMDA, kainate and mGluR agonists, and selective antagonists block this response. Using whole cell patch-clamp technique, inward currents were recorded from small diameter (ganglion preparation) in response to local application of the above glutamate receptor agonists. Following a chronic constriction injury (CCI) of either the inferior orbital nerve or the sciatic nerve, glutamate expression increases in the trigeminal ganglia and DRG respectively. This increase occurs in neurons of all diameters and is present in the somata of neurons with injured axons as well as in somata of neighboring uninjured neurons. These data provides additional evidence that glutamate can be released within the sensory ganglion, and that the somata of primary sensory neurons as well as SGCs express functional glutamate receptors at their surface. These findings, together with our previous gene knockdown data, suggest that glutamatergic transmission within the ganglion could impact nociceptive threshold.

  17. Role of aminotransferases in glutamate metabolism of human erythrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Ellinger, James J. [University of Wisconsin-Madison, Department of Biochemistry (United States); Lewis, Ian A. [Princeton University, Lewis-Sigler Institute for Integrative Genomics (United States); Markley, John L., E-mail: markley@nmrfam.wisc.edu [University of Wisconsin-Madison, Department of Biochemistry (United States)

    2011-04-15

    Human erythrocytes require a continual supply of glutamate to support glutathione synthesis, but are unable to transport this amino acid across their cell membrane. Consequently, erythrocytes rely on de novo glutamate biosynthesis from {alpha}-ketoglutarate and glutamine to maintain intracellular levels of glutamate. Erythrocytic glutamate biosynthesis is catalyzed by three enzymes, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and glutamine aminohydrolase (GA). Although the presence of these enzymes in RBCs has been well documented, the relative contributions of each pathway have not been established. Understanding the relative contributions of each biosynthetic pathway is critical for designing effective therapies for sickle cell disease, hemolytic anemia, pulmonary hypertension, and other glutathione-related disorders. In this study, we use multidimensional {sup 1}H-{sup 13}C nuclear magnetic resonance (NMR) spectroscopy and multiple reaction mode mass spectrometry (MRM-MS) to measure the kinetics of de novo glutamate biosynthesis via AST, ALT, and GA in intact cells and RBC lysates. We show that up to 89% of the erythrocyte glutamate pool can be derived from ALT and that ALT-derived glutamate is subsequently used for glutathione synthesis.

  18. Dysfunctional TCA-Cycle Metabolism in Glutamate Dehydrogenase Deficient Astrocytes.

    Science.gov (United States)

    Nissen, Jakob D; Pajęcka, Kamilla; Stridh, Malin H; Skytt, Dorte M; Waagepetersen, Helle S

    2015-12-01

    Astrocytes take up glutamate in the synaptic area subsequent to glutamatergic transmission by the aid of high affinity glutamate transporters. Glutamate is converted to glutamine or metabolized to support intermediary metabolism and energy production. Glutamate dehydrogenase (GDH) and aspartate aminotransferase (AAT) catalyze the reversible reaction between glutamate and α-ketoglutarate, which is the initial step for glutamate to enter TCA cycle metabolism. In contrast to GDH, AAT requires a concomitant interconversion of oxaloacetate and aspartate. We have investigated the role of GDH in astrocyte glutamate and glucose metabolism employing siRNA mediated knock down (KD) of GDH in cultured astrocytes using stable and radioactive isotopes for metabolic mapping. An increased level of aspartate was observed upon exposure to [U-(13) C]glutamate in astrocytes exhibiting reduced GDH activity. (13) C Labeling of aspartate and TCA cycle intermediates confirmed that the increased amount of aspartate is associated with elevated TCA cycle flux from α-ketoglutarate to oxaloacetate, i.e. truncated TCA cycle. (13) C Glucose metabolism was elevated in GDH deficient astrocytes as observed by increased de novo synthesis of aspartate via pyruvate carboxylation. In the absence of glucose, lactate production from glutamate via malic enzyme was lower in GDH deficient astrocytes. In conclusions, our studies reveal that metabolism via GDH serves an important anaplerotic role by adding net carbon to the TCA cycle. A reduction in GDH activity seems to cause the astrocytes to up-regulate activity in pathways involved in maintaining the amount of TCA cycle intermediates such as pyruvate carboxylation as well as utilization of alternate substrates such as branched chain amino acids. © 2015 Wiley Periodicals, Inc.

  19. In vitro evidence for the brain glutamate efflux hypothesis

    DEFF Research Database (Denmark)

    Helms, Hans Christian; Madelung, Rasmus; Waagepetersen, Helle Sønderby

    2012-01-01

    -glutamate homeostasis. Transendothelial transport- and accumulation studies of (3) H-L-glutamate, (3) H-L-aspartate, and (3) H-D-aspartate in an electrically tight bovine endothelial/rat astrocyte blood-brain barrier coculture model were performed. After 6 days in culture, the endothelium displayed transendothelial......The concentration of the excitotoxic amino acid, L-glutamate, in brain interstitial fluid is tightly regulated by uptake transporters and metabolism in astrocytes and neurons. The aim of this study was to investigate the possible role of the blood-brain barrier endothelium in brain L...

  20. 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.

  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. Fabrication of Implantable, Enzyme-Immobilized Glutamate Sensors for the Monitoring of Glutamate Concentration Changes in Vitro and in Vivo

    Directory of Open Access Journals (Sweden)

    Tina T.-C. Tseng

    2014-06-01

    Full Text Available Glutamate sensors based on the immobilization of glutamate oxidase (GlutOx were prepared by adsorption on electrodeposited chitosan (Method 1 and by crosslinking with glutaraldehyde (Method 2 on micromachined platinum microelectrodes. It was observed that glutamate sensors prepared by Method 1 have faster response time (<2 s and lower detection limit (2.5 ± 1.1 μM compared to that prepared by Method 2 (response time: <5 sec and detection limit: 6.5 ± 1.7 μM; glutamate sensors prepared by Method 2 have a larger linear detection range (20–352 μM and higher sensitivity (86.8 ± 8.8 nA·μM−1·cm−2, N = 12 compared to those prepared by Method 1 (linear detection range: 20–217 μM and sensitivity: 34.9 ± 4.8 nA·μM−1·cm−2, N = 8. The applicability of the glutamate sensors in vivo was also demonstrated. The glutamate sensors were implanted into the rat brain to monitor the stress-induced extracellular glutamate release in the hypothalamus of the awake, freely moving rat.

  3. Inhibition of the Mitochondrial Glutamate Carrier SLC25A22 in Astrocytes Leads to Intracellular Glutamate Accumulation

    Directory of Open Access Journals (Sweden)

    Emmanuelle Goubert

    2017-05-01

    Full Text Available The solute carrier family 25 (SLC25 drives the import of a large diversity of metabolites into mitochondria, a key cellular structure involved in many metabolic functions. Mutations of the mitochondrial glutamate carrier SLC25A22 (also named GC1 have been identified in early epileptic encephalopathy (EEE and migrating partial seizures in infancy (MPSI but the pathophysiological mechanism of GC1 deficiency is still unknown, hampered by the absence of an in vivo model. This carrier is mainly expressed in astrocytes and is the principal gate for glutamate entry into mitochondria. A sufficient supply of energy is essential for the proper function of the brain and mitochondria have a pivotal role in maintaining energy homeostasis. In this work, we wanted to study the consequences of GC1 absence in an in vitro model in order to understand if glutamate catabolism and/or mitochondrial function could be affected. First, short hairpin RNA (shRNA designed to specifically silence GC1 were validated in rat C6 glioma cells. Silencing GC1 in C6 resulted in a reduction of the GC1 mRNA combined with a decrease of the mitochondrial glutamate carrier activity. Then, primary astrocyte cultures were prepared and transfected with shRNA-GC1 or mismatch-RNA (mmRNA constructs using the Neon® Transfection System in order to target a high number of primary astrocytes, more than 64%. Silencing GC1 in primary astrocytes resulted in a reduced nicotinamide adenine dinucleotide (Phosphate (NAD(PH formation upon glutamate stimulation. We also observed that the mitochondrial respiratory chain (MRC was functional after glucose stimulation but not activated by glutamate, resulting in a lower level of cellular adenosine triphosphate (ATP in silenced astrocytes compared to control cells. Moreover, GC1 inactivation resulted in an intracellular glutamate accumulation. Our results show that mitochondrial glutamate transport via GC1 is important in sustaining glutamate homeostasis in

  4. 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

  5. Production of L-glutamic acid by a Bacillus sp.

    Science.gov (United States)

    Chattopadhyay, S P; Banerjee, A K

    1978-01-01

    A strain of Bacillus cereus var. mycoides isolated from Burdwan soil produces L-glutamate in the medium. The strain is able to grow and produce in a synthetic medium but supplementation with casamino acid or yeast extract improves the yield. Maintenance of pH of the fermentation medium near neutrality prolongs the active growth period and improves the yield. Glucose and ammonium nitrate were found to be most suitable carbon and nitrogen sources, respectively. Cane sugar molasses (as a substitute for glucose) significantly stimulated the growth but glutamate production was less. Various B vitamins stimulate the growth and glutamate yield. The yield of glutamate under optimal condition is 5.2 g/l.

  6. Microsensors for in vivo Measurement of Glutamate in Brain Tissue

    NARCIS (Netherlands)

    Qin, Si; van der Zeyden, Miranda; Oldenziel, Weite H.; Cremers, Thomas I. F. H.; Westerink, Ben H. C.

    2008-01-01

    Several immobilized enzyme-based electrochemical biosensors for glutamate detection have been developed over the last decade. In this review, we compare first and second generation sensors. Structures, working mechanisms, interference prevention, in vitro detection characteristics and in vivo

  7. Response of regional brain glutamate transaminases of rat to aluminum in protein malnutrition

    OpenAIRE

    Chatterjee Ajay K; Nayak Prasunpriya

    2002-01-01

    Abstract Background The mechanism of aluminum-induced neurotoxicity is not clear. The involvement of glutamate in the aluminium-induced neurocomplications has been suggested. Brain glutamate levels also found to be altered in protein malnutrition. Alterations in glutamate levels as well as glutamate-α-decarboxylase in different regions of rat brain has been reported in response to aluminum exposure. Thus the study of glutamate metabolising enzymes in different brain regions of rats maintained...

  8. Catalytic activity of bovine glutamate dehydrogenase requires a hexamer structure.

    OpenAIRE

    Bell, E T; Bell, J E

    1984-01-01

    Previous workers have shown that the hexamers of glutamate dehydrogenase are dissociated first into trimers and subsequently into monomers by increasing guanidinium chloride concentrations. In renaturation experiments it is shown that trimers of glutamate dehydrogenase can be reassociated to give the hexamer form of the enzyme, with full regain of activity. Monomeric subunits produced at high guanidinium chloride concentrations cannot be renatured. The trimer form of the enzyme is shown to ha...

  9. Detection and quantitation of glutamate carboxypeptidase II in human blood

    Czech Academy of Sciences Publication Activity Database

    Knedlík, Tomáš; Navrátil, Václav; Vik, V.; Pacík, D.; Šácha, Pavel; Konvalinka, Jan

    2014-01-01

    Roč. 74, č. 7 (2014), s. 768-780 ISSN 0270-4137 R&D Projects: GA ČR GAP304/12/0847 Grant - others:OPPC(CZ) CZ.2.16/3.1.00/24016 Institutional support: RVO:61388963 Keywords : serum marker * glutamate carboxypeptidase II * plasma glutamate carboxypeptidase * prostate cancer * prostate -specific membrane antigen Subject RIV: CE - Biochemistry Impact factor: 3.565, year: 2014

  10. Immunochemical characterization of the brain glutamate binding protein

    International Nuclear Information System (INIS)

    Roy, S.

    1986-01-01

    A glutamate binding protein (GBP) was purified from bovine and rat brain to near homogeneity. Polyclonal antibodies were raised against this protein. An enzyme-linked-immunosorbent-assay was used to quantify and determine the specificity of the antibody response. The antibodies were shown to strongly react with bovine brain GBP and the analogous protein from rat brain. The antibodies did not show any crossreactivity with the glutamate metabolizing enzymes, glutamate dehydrogenase, glutamine synthetase and glutamyl transpeptidase, however it crossreacted moderately with glutamate decarboxylase. The antibodies were also used to define the possible physiologic activity of GBP in synaptic membranes. The antibodies were shown: (i) to inhibit the excitatory amino-acid stimulation of thiocyanate (SCN)flux, (ii) had no effect on transport of L-Glutamic acid across the synaptic membrane, and (iii) had no effect on the depolarization-induced release of L-glutamate. When the anti-GBP antibodies were used to localize and quantify the GBP distribution in various subcellular fractions and in brain tissue samples, it was found that the hippocampus had the highest immunoreactivity followed by the cerebral cortex, cerebellar cortex and caudate-putamen. The distribution of immunoreactivity in the subcellular fraction were as follows: synaptic membranes > crude mitochondrial fraction > homogenate > myelin. In conclusion these studies suggest that: (a) the rat brain GBP and the bovine brain GBP are immunologically homologous protein, (b) there are no structural similarities between the GBP and the glutamate metabolizing enzymes with the exception of glutamate decarboxylase and (c) the subcellular and regional distribution of the GBP immunoreactivity followed a similar pattern as observed for L-[ 3 H]-binding

  11. Glutamic Acid Selective Chemical Cleavage of Peptide Bonds.

    Science.gov (United States)

    Nalbone, Joseph M; Lahankar, Neelam; Buissereth, Lyssa; Raj, Monika

    2016-03-04

    Site-specific hydrolysis of peptide bonds at glutamic acid under neutral aqueous conditions is reported. The method relies on the activation of the backbone amide chain at glutamic acid by the formation of a pyroglutamyl (pGlu) imide moiety. This activation increases the susceptibility of a peptide bond toward hydrolysis. The method is highly specific and demonstrates broad substrate scope including cleavage of various bioactive peptides with unnatural amino acid residues, which are unsuitable substrates for enzymatic hydrolysis.

  12. Update on food safety of monosodium l-glutamate (MSG).

    Science.gov (United States)

    Henry-Unaeze, Helen Nonye

    2017-12-01

    This evidence-based safety review of the flavor enhancer monosodium l-glutamate (MSG) was triggered by its global use and recent studies expressing some safety concerns. This article obtained information through search of evidence-based scientific databases, especially the US National Library of Medicine NIH. (A) MSG is a water-soluble salt of glutamate, a non-essential amino acid, normally synthesized in the body and prevalent in protein foods. (B) MSG is utilized world-wide for its "umami" taste and flavor enhancement qualities, (C) the human body does not discriminate between glutamate present in food and that added as seasoning, (D) glutamate metabolism is compartmentalized in the human body without reported ethnic differences, (E) glutamate does not passively cross biological membranes, (F) food glutamate is completely metabolized by gut cells as energy source and serves as key substrate for other important metabolites in the liver, (G) normal food use of MSG is dose-dependent and self-limiting without elevation in plasma glutamate, (H) the recent EFSA acceptable daily intake (30mg/kg body weight/day) is not attainable when MSG is consumed at normal dietary level, (I) scientists have not been able to consistently elicit reactions in double-blind studies with 'sensitive' individuals using MSG or placebo in food. Based on the above observations (A-I), high quality MSG is safe for all life-cycle stages without respect to ethnic origin or culinary background. MSG researchers are advised to employ appropriate scientific methodologies, consider glutamate metabolism and its normal food use before extrapolating pharmacological rodent studies to humans. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Monosodium glutamate is not likely to be genotoxic.

    Science.gov (United States)

    Rogers, Michael D

    2016-08-01

    The International Glutamate Technical Committee (IGTC) wishes to comment on a recent publication in the Journal entitled "Genotoxicity of monosodium glutamate" (authored by Ataseven N, Yüzbaşıoğlu D, Keskin AÇ and Ünal F) (Ataseven et al. 2016). In particular, we wish to highlight that, in our considered view, the results of this study were inappropriately discussed and that references were selectively used. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Glutamate synapses in human cognitive disorders.

    Science.gov (United States)

    Volk, Lenora; Chiu, Shu-Ling; Sharma, Kamal; Huganir, Richard L

    2015-07-08

    Accumulating data, including those from large genetic association studies, indicate that alterations in glutamatergic synapse structure and function represent a common underlying pathology in many symptomatically distinct cognitive disorders. In this review, we discuss evidence from human genetic studies and data from animal models supporting a role for aberrant glutamatergic synapse function in the etiology of intellectual disability (ID), autism spectrum disorder (ASD), and schizophrenia (SCZ), neurodevelopmental disorders that comprise a significant proportion of human cognitive disease and exact a substantial financial and social burden. The varied manifestations of impaired perceptual processing, executive function, social interaction, communication, and/or intellectual ability in ID, ASD, and SCZ appear to emerge from altered neural microstructure, function, and/or wiring rather than gross changes in neuron number or morphology. Here, we review evidence that these disorders may share a common underlying neuropathy: altered excitatory synapse function. We focus on the most promising candidate genes affecting glutamatergic synapse function, highlighting the likely disease-relevant functional consequences of each. We first present a brief overview of glutamatergic synapses and then explore the genetic and phenotypic evidence for altered glutamate signaling in ID, ASD, and SCZ.

  15. Comparative evaluation of glutamate-sensitive radiopharmaceuticals: Technetium-99m-glutamic acid and technetium-99m-diethylenetriaminepentaacetic acid-bis(glutamate) conjugate for tumor imaging.

    Science.gov (United States)

    Kakkar, Dipti; Tiwari, Anjani K; Chuttani, Krishna; Kaul, Ankur; Singh, Harpal; Mishra, Anil K

    2010-12-01

    Single-photon emission computed tomography has become a significant imaging modality with huge potential to visualize and provide information of anatomic dysfunctions that are predictive of future diseases. This imaging tool is complimented by radiopharmaceuticals/radiosubstrates that help in imaging specific physiological aspects of the human body. The present study was undertaken to explore the utility of technetium-99m (⁹⁹(m)Tc)-labeled glutamate conjugates for tumor scintigraphy. As part of our efforts to further utilize the application of chelating agents, glutamic acid was conjugated with a multidentate ligand, diethylenetriaminepentaacetic acid (DTPA). The DTPA-glutamate conjugate [DTPA-bis(Glu)] was well characterized by IR, NMR, and mass spectroscopy. The biological activity of glutamic acid was compared with its DTPA conjugate by radiocomplexation with ⁹⁹(m)Tc (labeling efficiency ≥98%). In vivo studies of both the radiolabeled complexes ⁹⁹(m)Tc-Glu and ⁹⁹(m)Tc-DTPA-bis(Glu) were then carried out, followed by gamma scintigraphy in New Zealand albino rabbits. Improved serum stability of ⁹⁹(m)Tc-labeled DTPA conjugate indicated that ⁹⁹(m)Tc remained bound to the conjugate up to 24 hours. Blood clearance showed a relatively slow washout of the DTPA conjugate when compared with the labeled glutamate. Biodistribution characteristics of the conjugate in Balb/c mice revealed that DTPA conjugation of glutamic acid favors less accumulation in the liver and bone and rapid renal clearance. Tumor scintigraphy in mice showed increasing tumor accumulation, stable up to 4 hours. These preliminary studies show that ⁹⁹(m)Tc-DTPA-bis(Glu) can be a useful radiopharmaceutical for diagnostic applications in single-photon emission computed tomography imaging.

  16. Enhancing poly-γ-glutamic acid production in Bacillus amyloliquefaciens by introducing the glutamate synthesis features from Corynebacterium glutamicum.

    Science.gov (United States)

    Feng, Jun; Quan, Yufen; Gu, Yanyan; Liu, Fenghong; Huang, Xiaozhong; Shen, Haosheng; Dang, Yulei; Cao, Mingfeng; Gao, Weixia; Lu, Xiaoyun; Wang, Yi; Song, Cunjiang; Wang, Shufang

    2017-05-22

    Poly-γ-glutamic acid (γ-PGA) is a valuable polymer with glutamate as its sole precursor. Enhancement of the intracellular glutamate synthesis is a very important strategy for the improvement of γ-PGA production, especially for those glutamate-independent γ-PGA producing strains. Corynebacterium glutamicum has long been used for industrial glutamate production and it exhibits some unique features for glutamate synthesis; therefore introduction of these metabolic characters into the γ-PGA producing strain might lead to increased intracellular glutamate availability, and thus ultimate γ-PGA production. In this study, the unique glutamate synthesis features from C. glutamicum was introduced into the glutamate-independent γ-PGA producing Bacillus amyloliquefaciens NK-1 strain. After introducing the energy-saving NADPH-dependent glutamate dehydrogenase (NADPH-GDH) pathway, the NK-1 (pHT315-gdh) strain showed slightly increase (by 9.1%) in γ-PGA production. Moreover, an optimized metabolic toggle switch for controlling the expression of ɑ-oxoglutarate dehydrogenase complex (ODHC) was introduced into the NK-1 strain, because it was previously shown that the ODHC in C. glutamicum was completely inhibited when glutamate was actively produced. The obtained NK-PO1 (pHT01-xylR) strain showed 66.2% higher γ-PGA production than the NK-1 strain. However, the further combination of these two strategies (introducing both NADPH-GDH pathway and the metabolic toggle switch) did not lead to further increase of γ-PGA production but rather the resultant γ-PGA production was even lower than that in the NK-1 strain. We proposed new metabolic engineering strategies to improve the γ-PGA production in B. amyloliquefaciens. The NK-1 (pHT315-gdh) strain with the introduction of NADPH-GDH pathway showed 9.1% improvement in γ-PGA production. The NK-PO1 (pHT01-xylR) strain with the introduction of a metabolic toggle switch for controlling the expression of ODHC showed 66.2% higher

  17. Delineation of glutamate pathways and secretory responses in pancreatic islets with β-cell-specific abrogation of the glutamate dehydrogenase.

    Science.gov (United States)

    Vetterli, Laurène; Carobbio, Stefania; Pournourmohammadi, Shirin; Martin-Del-Rio, Rafael; Skytt, Dorte M; Waagepetersen, Helle S; Tamarit-Rodriguez, Jorge; Maechler, Pierre

    2012-10-01

    In pancreatic β-cells, glutamate dehydrogenase (GDH) modulates insulin secretion, although its function regarding specific secretagogues is unclear. This study investigated the role of GDH using a β-cell-specific GDH knockout mouse model, called βGlud1(-/-). The absence of GDH in islets isolated from βGlud1(-/-) mice resulted in abrogation of insulin release evoked by glutamine combined with 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid or l-leucine. Reintroduction of GDH in βGlud1(-/-) islets fully restored the secretory response. Regarding glucose stimulation, insulin secretion in islets isolated from βGlud1(-/-) mice exhibited half of the response measured in control islets. The amplifying pathway, tested at stimulatory glucose concentrations in the presence of KCl and diazoxide, was markedly inhibited in βGlud1(-/-) islets. On glucose stimulation, net synthesis of glutamate from α-ketoglutarate was impaired in GDH-deficient islets. Accordingly, glucose-induced elevation of glutamate levels observed in control islets was absent in βGlud1(-/-) islets. Parallel biochemical pathways, namely alanine and aspartate aminotransferases, could not compensate for the lack of GDH. However, the secretory response to glucose was fully restored by the provision of cellular glutamate when βGlud1(-/-) islets were exposed to dimethyl glutamate. This shows that permissive levels of glutamate are required for the full development of glucose-stimulated insulin secretion and that GDH plays an indispensable role in this process.

  18. Bacterial cell-surface displaying of thermo-tolerant glutamate dehydrogenase and its application in L-glutamate assay.

    Science.gov (United States)

    Song, Jianxia; Liang, Bo; Han, Dongfei; Tang, Xiangjiang; Lang, Qiaolin; Feng, Ruirui; Han, Lihui; Liu, Aihua

    2015-03-01

    In this paper, glutamate dehydrogenase (Gldh) is reported to efficiently display on Escherichia coli cell surface by using N-terminal region of ice the nucleation protein as an anchoring motif. The presence of Gldh was confirmed by SDS-PAGE and enzyme activity assay. Gldh was detected mainly in the outer membrane fraction, suggesting that the Gldh was displayed on the bacterial cell surface. The optimal temperature and pH for the bacteria cell-surface displayed Gldh (bacteria-Gldh) were 70°C and 9.0, respectively. Additionally, the fusion protein retained almost 100% of its initial enzymatic activity after 1 month incubation at 4°C. Transition metal ions could inhibit the enzyme activity to different extents, while common anions had little adverse effect on enzyme activity. Importantly, the displayed Gldh is most specific to l-glutamate reported so far. The bacterial Gldh was enabled to catalyze oxidization of l-glutamate with NADP(+) as cofactor, and the resultant NADPH can be detected spectrometrically at 340nm. The bacterial-Gldh based l-glutamate assay was established, where the absorbance at 340nm increased linearly with the increasing l-glutamate concentration within the range of 10-400μM. Further, the proposed approach was successfully applied to measure l-glutamate in real samples. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Neonatal monosodium glutamate treatment modifies glutamic acid decarboxylase activity during rat brain postnatal development.

    Science.gov (United States)

    Ureña-Guerrero, Mónica Elisa; López-Pérez, Silvia Josefina; Beas-Zárate, Carlos

    2003-03-01

    Monosodium glutamate (MSG) produces neurodegeneration in several brain regions when it is administered to neonatal rats. From an early embryonic age to adulthood, GABA neurons appear to have functional glutamatergic receptors, which could convert them in an important target for excitotoxic neurodegeneration. Changes in the activity of the GABA synthesizing enzyme, glutamic acid decarboxylase (GAD), have been shown after different neuronal insults. Therefore, this work evaluates the effect of neonatal MSG treatment on GAD activity and kinetics in the cerebral cortex, striatum, hippocampus and cerebellum of the rat brain during postnatal development. Neonatal MSG treatment decreased GAD activity in the cerebral cortex at 21 and 60 postnatal days (PD), mainly due to a reduction in the enzyme affinity (K(m)). In striatum, the GAD activity and the enzyme maximum velocity (V(max)) were increased at PD 60 after neonatal MSG treatment. Finally, in the hippocampus and cerebellum, the GAD activity and V(max) were increased, but the K(m) was found to be lower in the experimental group. The results could be related to compensatory mechanisms from the surviving GABAergic neurons, and suggest a putative adjustment in the GAD isoform expression throughout the development of the postnatal brain, since this enzyme is regulated by the synaptic activity under physiological and/or pathophysiological conditions.

  20. Mediator-less highly sensitive voltammetric detection of glutamate using glutamate dehydrogenase/vertically aligned CNTs grown on silicon substrate.

    Science.gov (United States)

    Gholizadeh, Azam; Shahrokhian, Saeed; zad, Azam Iraji; Mohajerzadeh, Shamsoddin; Vosoughi, Manouchehr; Darbari, Sara; Sanaee, Zeinab

    2012-01-15

    A sensitive glutamate biosensor is prepared based on glutamate dehydrogenase/vertically aligned carbon nanotubes (GLDH, VACNTs). Vertically aligned carbon nanotubes were grown on a silicon substrate by direct current plasma enhanced chemical vapor deposition (DC-PECVD) method. The electrochemical behavior of the synthesized VACNTs was investigated by cyclic voltammetry and electrochemical impedance spectroscopic methods. Glutamate dehydrogenase covalently attached on tip of VACNTs. The electrochemical performance of the electrode for detection of glutamate was investigated by cyclic and differential pulse voltammetry. Differential pulse voltammetric determinations of glutamate are performed in mediator-less condition and also, in the presence of 1 and 5 μM thionine as electron mediator. The linear calibration curve of the concentration of glutamate versus peak current is investigated in a wide range of 0.1-500 μM. The mediator-less biosensor has a low detection limit of 57 nM and two linear ranges of 0.1-20 μM with a sensitivity of 0.976 mA mM(-1) cm(-2) and 20-300 μM with a sensitivity of 0.182 mA mM(-1) cm(-2). In the presence of 1 μM thionine as an electron mediator, the prepared biosensor shows a low detection limit of 68 nM and two linear ranges of 0.1-20 with a calibration sensitivity of 1.17 mA mM(-1) cm(-2) and 20-500 μM with a sensitivity of 0.153 mA mM(-1) cm(-2). The effects of the other biological compounds on the voltammetric behavior of the prepared biosensor and its response stability are investigated. The results are demonstrated that the GLDH/VACNTs electrode even without electron mediator is a suitable basic electrode for detection of glutamate. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Differential effects of repetitive oral administration of monosodium glutamate on interstitial glutamate concentration and muscle pain sensitivity.

    Science.gov (United States)

    Shimada, Akiko; Baad-Hansen, Lene; Castrillon, Eduardo; Ghafouri, Bijar; Stensson, Niclas; Gerdle, Björn; Ernberg, Malin; Cairns, Brian; Svensson, Peter; Svensson Odont, Peter

    2015-02-01

    The aim of this study was to determine the relationship of high daily monosodium glutamate (MSG) consumption with glutamate concentrations in jaw muscle, saliva, and serum, and muscle pain sensitivity in healthy participants. A randomized, double-blinded, placebo-controlled study was conducted to investigate the effect of repetitive consumption of high-dose MSG on glutamate concentration in the masseter muscles measured by microdialysis and muscle pain sensitivity. In five contiguous experimental daily sessions, 32 healthy participants drank MSG (150 mg/kg) or NaCl (24 mg/kg) diluted with a 400 mL soda. The concentrations of glutamate before and after the ingestion were assessed in dialysate and plasma samples on the first and last days. Saliva glutamate concentration was assessed every day. Pressure pain threshold, pressure pain tolerance, autonomic parameters (heart rate, systolic and diastolic blood pressures) and reported side effects also were assessed. No significant change was noted in the baseline concentration of glutamate in the masseter muscle, blood, or saliva, but the peak concentration in the masseter muscle increased significantly between day 1 and 5. A statistically significant increase in systolic and diastolic blood pressures after MSG administration was observed, as well as a significantly higher frequency of reports of nausea and headache in the MSG group. No robust effect of MSG on muscle sensitivity was found. Interstitial glutamate concentration in the masseter muscle is not highly disturbed by excessive repetitive intake of MSG in healthy man. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients.

    Science.gov (United States)

    Shimada, A; Castrillon, E E; Baad-Hansen, L; Ghafouri, B; Gerdle, B; Wåhlén, K; Ernberg, M; Cairns, B E; Svensson, P

    2016-10-01

    A randomized, double-blinded, placebo-controlled study was conducted to investigate if single monosodium glutamate (MSG) administration would elevate muscle/serum glutamate concentrations and affect muscle pain sensitivity in myofascial temporomandibular disorders (TMD) patients more than in healthy individuals. Twelve myofascial TMD patients and 12 sex- and age-matched healthy controls participated in two sessions. Participants drank MSG (150 mg/kg) or NaCl (24 mg/kg; control) diluted in 400 mL of soda. The concentration of glutamate in the masseter muscle, blood plasma and saliva was determined before and after the ingestion of MSG or control. At baseline and every 15 min after the ingestion, pain intensity was scored on a 0-10 numeric rating scale. Pressure pain threshold, pressure pain tolerance (PPTol) and autonomic parameters were measured. All participants were asked to report adverse effects after the ingestion. In TMD, interstitial glutamate concentration was significantly greater after the MSG ingestion when compared with healthy controls. TMD reported a mean pain intensity of 2.8/10 at baseline, which significantly increased by 40% 30 min post MSG ingestion. At baseline, TMD showed lower PPTols in the masseter and trapezius, and higher diastolic blood pressure and heart rate than healthy controls. The MSG ingestion resulted in reports of headache by half of the TMD and healthy controls, respectively. These findings suggest that myofascial TMD patients may be particularly sensitive to the effects of ingested MSG. WHAT DOES THIS STUDY ADD?': Elevation of interstitial glutamate concentration in the masseter muscle caused by monosodium glutamate (MSG) ingestion was significantly greater in myofascial myofascial temporomandibular disorders (TMD) patients than healthy individuals. This elevation of interstitial glutamate concentration in the masseter muscle significantly increased the intensity of spontaneous pain in myofascial TMD patients. © 2016

  3. Seizures induced in immature rats by homocysteic acid and the associated brain damage are prevented by group II metabotropic glutamate receptor agonist (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate

    Czech Academy of Sciences Publication Activity Database

    Folbergrová, Jaroslava; Druga, Rastislav; Otáhal, Jakub; Haugvicová, Renata; Mareš, Pavel; Kubová, Hana

    2005-01-01

    Roč. 192, č. 2 (2005), s. 420-436 ISSN 0014-4886 R&D Projects: GA ČR(CZ) GA309/02/1238 Institutional research plan: CEZ:AV0Z5011922 Keywords : immature rats * neuronal degeneration * energy metabolites Subject RIV: FH - Neurology Impact factor: 3.767, year: 2005

  4. Glutamate abnormalities in obsessive compulsive disorder: neurobiology, pathophysiology, and treatment.

    Science.gov (United States)

    Pittenger, Christopher; Bloch, Michael H; Williams, Kyle

    2011-12-01

    Obsessive compulsive disorder is prevalent, disabling, incompletely understood, and often resistant to current therapies. Established treatments consist of specialized cognitive-behavioral psychotherapy and pharmacotherapy with medications targeting serotonergic and dopaminergic neurotransmission. However, remission is rare, and more than a quarter of OCD sufferers receive little or no benefit from these approaches, even when they are optimally delivered. New insights into the disorder, and new treatment strategies, are urgently needed. Recent evidence suggests that the ubiquitous excitatory neurotransmitter glutamate is dysregulated in OCD, and that this dysregulation may contribute to the pathophysiology of the disorder. Here we review the current state of this evidence, including neuroimaging studies, genetics, neurochemical investigations, and insights from animal models. Finally, we review recent findings from small clinical trials of glutamate-modulating medications in treatment-refractory OCD. The precise role of glutamate dysregulation in OCD remains unclear, and we lack blinded, well-controlled studies demonstrating therapeutic benefit from glutamate-modulating agents. Nevertheless, the evidence supporting some important perturbation of glutamate in the disorder is increasingly strong. This new perspective on the pathophysiology of OCD, which complements the older focus on monoaminergic neurotransmission, constitutes an important focus of current research and a promising area for the ongoing development of new therapeutics. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Distribution of vesicular glutamate transporters in the human brain

    Directory of Open Access Journals (Sweden)

    Erika eVigneault

    2015-03-01

    Full Text Available Glutamate is the major excitatory transmitter in the brain. Vesicular glutamate transporters (VGLUT1-3 are responsible for uploading glutamate into synaptic vesicles. VGLUT1 and VGLUT2 are considered as specific markers of canonical glutamatergic neurons, while VGLUT3 is found in neurons previously shown to use other neurotransmitters than glutamate. Although there exists a rich literature on the localization of these glutamatergic markers in the rodent brain, little is currently known about the distribution of VGLUT1-3 in the human brain. In the present study, using subtype specific probes and antisera, we examined the localization of the three vesicular glutamate transporters in the human brain by in situ hybridization, immunoautoradiography and immunohistochemistry. We found that the VGLUT1 transcript was highly expressed in the cerebral cortex, hippocampus and cerebellum, whereas VGLUT2 mRNA was mainly found in the thalamus and brainstem. VGLUT3 mRNA was localized in scarce neurons within the cerebral cortex, hippocampus, striatum and raphe nuclei. Following immunoautoradiographic labeling, intense VGLUT1- and VGLUT2-immunoreactivities were observed in all regions investigated (cerebral cortex, hippocampus, caudate-putamen, cerebellum, thalamus, amygdala, substantia nigra, raphe while VGLUT3 was absent from the thalamus and cerebellum. This extensive mapping of VGLUT1-3 in human brain reveals distributions that correspond for the most part to those previously described in rodent brains.

  6. Influence of glutamic acid enantiomers on C-mineralization.

    Science.gov (United States)

    Formánek, Pavel; Vranová, Valerie; Lojková, Lea

    2015-02-01

    Seasonal dynamics in the mineralization of glutamic acid enantiomers in soils from selected ecosystems was determined and subjected to a range of treatments: ambient x elevated CO2 level and meadow x dense x thinned forest environment. Mineralization of glutamic acid was determined by incubation of the soil with 2 mg L- or D-glutamic acid g(-1) of dry soil to induce the maximum respiration rate. Mineralization of glutamic acid enantiomers in soils fluctuates over the course of a vegetation season, following a similar trend across a range of ecosystems. Mineralization is affected by environmental changes and management practices, including elevated CO2 level and thinning intensity. L-glutamic acid metabolism is more dependent on soil type as compared to metabolism of its D-enantiomer. The results support the hypothesis that the slower rate of D- compared to L- amino acid mineralization is due to different roles in anabolism and catabolism of the soil microbial community. © 2014 Wiley Periodicals, Inc.

  7. Methylphenidate Increases Glutamate Uptake in Bergmann Glial Cells.

    Science.gov (United States)

    Guillem, Alain M; Martínez-Lozada, Zila; Hernández-Kelly, Luisa C; López-Bayghen, Esther; López-Bayghen, Bruno; Calleros, Oscar A; Campuzano, Marco R; Ortega, Arturo

    2015-11-01

    Glutamate, the main excitatory transmitter in the vertebrate brain, exerts its actions through the activation of specific membrane receptors present in neurons and glial cells. Over-stimulation of glutamate receptors results in neuronal death, phenomena known as excitotoxicity. A family of glutamate uptake systems, mainly expressed in glial cells, removes the amino acid from the synaptic cleft preventing an excessive glutamatergic stimulation and thus neuronal damage. Autism spectrum disorders comprise a group of syndromes characterized by impaired social interactions and anxiety. One or the most common drugs prescribed to treat these disorders is Methylphenidate, known to increase dopamine extracellular levels, although it is not clear if its sedative effects are related to a plausible regulation of the glutamatergic tone via the regulation of the glial glutamate uptake systems. To gain insight into this possibility, we used the well-established model system of cultured chick cerebellum Bergmann glia cells. A time and dose-dependent increase in the activity and protein levels of glutamate transporters was detected upon Methylphenidate exposure. Interestingly, this increase is the result of an augmentation of both the synthesis as well as the insertion of these protein complexes in the plasma membrane. These results favour the notion that glial cells are Methylphenidate targets, and that by these means could regulate dopamine turnover.

  8. Binding and release of glutamate from overoxidized polypyrrole via an applied potential for application as a molecular switch

    NARCIS (Netherlands)

    von Hauff, Elizabeth; Meteleva-Fischer, Yulia; Parisi, Jueirgen; Weiler, Reto

    2008-01-01

    The controlled binding and release of glutamate from overoxidized polypyrrole (PPy) films via a variable potential was investigated. Glutamate-doped PPy films were electrochemically deposited from aqueous sodium glutamate electrolytes containing the pyrrole monomer. The resulting polymer films were

  9. Dysfunctional TCA-Cycle Metabolism in Glutamate Dehydrogenase Deficient Astrocytes

    DEFF Research Database (Denmark)

    Nissen, Jakob D; Pajęcka, Kamilla; Stridh, Malin H

    2015-01-01

    aminotransferase (AAT) catalyze the reversible reaction between glutamate and α-ketoglutarate, which is the initial step for glutamate to enter TCA cycle metabolism. In contrast to GDH, AAT requires a concomitant interconversion of oxaloacetate and aspartate. We have investigated the role of GDH in astrocyte...... Labeling of aspartate and TCA cycle intermediates confirmed that the increased amount of aspartate is associated with elevated TCA cycle flux from α-ketoglutarate to oxaloacetate, i.e. truncated TCA cycle. (13) C Glucose metabolism was elevated in GDH deficient astrocytes as observed by increased de novo...... synthesis of aspartate via pyruvate carboxylation. In the absence of glucose, lactate production from glutamate via malic enzyme was lower in GDH deficient astrocytes. In conclusions, our studies reveal that metabolism via GDH serves an important anaplerotic role by adding net carbon to the TCA cycle...

  10. Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci

    Directory of Open Access Journals (Sweden)

    Guillermo Hugo Peralta

    Full Text Available ABSTRACT Aminotransferases and glutamate dehydrogenase are two main types of enzymes involved in the initial steps of amino acid catabolism, which plays a key role in the cheese flavor development. In the present work, glutamate dehydrogenase and aminotransferase activities were screened in twenty one strains of lactic acid bacteria of dairy interest, either cheese-isolated or commercial starters, including fifteen mesophilic lactobacilli, four thermophilic lactobacilli, and two streptococci. The strains of Streptococcus thermophilus showed the highest glutamate dehydrogenase activity, which was significantly elevated compared with the lactobacilli. Aspartate aminotransferase prevailed in most strains tested, while the levels and specificity of other aminotransferases were highly strain- and species-dependent. The knowledge of enzymatic profiles of these starter and cheese-isolated cultures is helpful in proposing appropriate combinations of strains for improved or increased cheese flavor.

  11. Zinc and glutamate dehydrogenase in putative glutamatergic brain structures.

    Science.gov (United States)

    Wolf, G; Schmidt, W

    1983-01-01

    A certain topographic parallelism between the distribution of histochemically (TIMM staining) identified zinc and putative glutamatergic structures in the rat brain was demonstrated. Glutamate dehydrogenase as a zinc containing protein is in consideration to be an enzyme synthesizing transmitter glutamate. In a low concentration range externally added zinc ions (10(-9) to 10(-7) M) induced an increase in the activity of glutamate dehydrogenase (GDH) originating from rat hippocampal formation, neocortex, and cerebellum up to 142.4%. With rising molarity of Zn(II) in the incubation medium, the enzyme of hippocampal formation and cerebellum showed a biphasic course of activation. Zinc ions of a concentration higher than 10(-6) M caused a strong inhibition of GDH. The effect of Zn(II) on GDH originating from spinal ganglia and liver led only to a decrease of enzyme activity. These results are discussed in connection with a functional correlation between zinc and putatively glutamatergic system.

  12. Foreign body granuloma caused by monosodium glutamate after BCG vaccination.

    Science.gov (United States)

    Chiu, Yao-Kun; Huang, Chao-Cheng; Jeng, Jingyueh; Shiea, Jentaie; Chen, Wei-Jen

    2006-08-01

    We describe a 7-month-old male infant with a foreign body granuloma caused by monosodium glutamate (MSG) after a Bacille Calmette-Guérin (BCG) immunization. A ridged, erythematous, indurated plaque developed over a BCG injection site on his left upper arm 1 month after the first BCG immunization. Biopsy showed multiple noncaseating foreign body granulomas without detectable mycobacteria by both Ziehl-Neelsen stain and polymerase chain reaction assay. Birefringent crystals were identified in the foreign body giant cells with polarized light microscopy. The crystals were further determined to be glutamic acid by the method of fast atom bombardment. Hence, MSG, the only composite of BCG vaccine except the bacillus, was believed to be responsible for the granulomatous foreign body reaction. On review of the literature, we could find no previous report of an adverse reaction of BCG immunization attributable to MSG (glutamic acid).

  13. Enzymatic production of α-ketoglutaric acid from l-glutamic acid via l-glutamate oxidase.

    Science.gov (United States)

    Niu, Panqing; Dong, Xiaoxiang; Wang, Yuancai; Liu, Liming

    2014-06-10

    In this study, a novel strategy for α-ketoglutaric acid (α-KG) production from l-glutamic acid using recombinant l-glutamate oxidase (LGOX) was developed. First, by analyzing the molecular structure characteristics of l-glutamic acid and α-KG, LGOX was found to be the best catalyst for oxidizing the amino group of l-glutamic acid to a ketonic group without the need for exogenous cofactor. Then the LGOX gene was expressed in Escherichia coli BL21 (DE3) in a soluble and active form, and the recombinant LGOX activity reached to a maximum value of 0.59U/mL at pH 6.5, 30°C. Finally, the maximum α-KG concentration reached 104.7g/L from 110g/L l-glutamic acid in 24h, under the following optimum conditions: 1.5U/mL LGOX, 250U/mL catalase, 3mM MnCl2, 30°C, and pH 6.5. Copyright © 2014. Published by Elsevier B.V.

  14. Therapeutic effects of glutamic acid in piglets challenged with deoxynivalenol.

    Science.gov (United States)

    Wu, Miaomiao; Xiao, Hao; Ren, Wenkai; Yin, Jie; Tan, Bie; Liu, Gang; Li, Lili; Nyachoti, Charles Martin; Xiong, Xia; Wu, Guoyao

    2014-01-01

    The mycotoxin deoxynivalenol (DON), one of the most common food contaminants, primarily targets the gastrointestinal tract to affect animal and human health. This study was conducted to examine the protective function of glutamic acid on intestinal injury and oxidative stress caused by DON in piglets. Twenty-eight piglets were assigned randomly into 4 dietary treatments (7 pigs/treatment): 1) uncontaminated control diet (NC), 2) NC+DON at 4 mg/kg (DON), 3) NC+2% glutamic acid (GLU), and 4) NC+2% glutamic acid + DON at 4 mg/kg (DG). At day 15, 30 and 37, blood samples were collected to determine serum concentrations of CAT (catalase), T-AOC (total antioxidant capacity), H2O2 (hydrogen peroxide), NO (nitric oxide), MDA (maleic dialdehyde), DAO (diamine oxidase) and D-lactate. Intestinal morphology, and the activation of Akt/mTOR/4EBP1 signal pathway, as well as the concentrations of H2O2, MDA, and DAO in kidney, liver and small intestine, were analyzed at day 37. Results showed that DON significantly (Pglutamic acid supplementation according to the change of oxidative parameters in blood and tissues. Meanwhile, DON caused obvious intestinal injury from microscopic observations and permeability indicators, which was alleviated by glutamic acid supplementation. Moreover, the inhibition of DON on Akt/mTOR/4EBP1 signal pathway was reduced by glutamic acid supplementation. Collectively, these data suggest that glutamic acid may be a useful nutritional regulator for DON-induced damage manifested as oxidative stress, intestinal injury and signaling inhibition.

  15. Synthesis of edatrexate (2-13C-glutamate)

    International Nuclear Information System (INIS)

    DeGraw, J.I.; Colwell, W.T.; Jue, Thomas

    1997-01-01

    The experimental antitumor drug Edatrexate, labeled with 99% 13 C at the 2-position of the glutamate acid group was required for 13 C-magnetic resonance spectroscopy studies in biological media. Coupling of 2,4-diamino-4-deoxy-10-ethyl-10-deazapteroic acid with diethyl L-2- 13 C-glutamate as promoted by BOP reagent afforded Edatrexate (2- 13 C-glu) diethyl ester in 60% yield following purification by column chromatography. Saponification by aqueous NaOH in 2-methoxyethanol gave the target molecule in 44% yield or 26% overall. (author)

  16. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...

  17. Lack of cardioprotection from metabolic support with glutamine or glutamate in a porcine coronary occlusion model

    DEFF Research Database (Denmark)

    Kristensen, Jens; Mæng, Michael; Mortensen, Ulrik

    2005-01-01

    vascular resistance, while glutamate preserved cardiac output during infusion. CONCLUSION: Substrate supplementation with the anaplerotic precursors glutamine and glutamate is ineffective as adjunctive therapy for severe myocardial ischemia. Beneficial effects documented in less complex experimental...

  18. Increased glutamate levels in the vitreous of patients with retinal detachment

    NARCIS (Netherlands)

    Diederen, R.; Heij, La E.C.; Deutz, N.E.P.; Kijlstra, A.; Kessels, A.G.H.; Eijk, van H.M.; Liem, A.T.A.; Dieudonne, S.; Hendrikse, F.

    2006-01-01

    Experimental models have implicated glutamate in the irreversible damage to retinal cells following retinal detachment. In this retrospective study we investigated a possible role for glutamate and other amino acid neurotransmitters during clinical rhegmatogenous retinal detachment (RRD). Undiluted

  19. Microdialysis as a tool for in vivo investigation of glutamate transport capacity in rat brain

    DEFF Research Database (Denmark)

    Bruhn, T; Christensen, Thomas; Diemer, Nils Henrik

    1995-01-01

    The role of glutamate as a possible mediator of neurodegeneration is well described, and the homeostasis of extracellular glutamate is considered of major importance when addressing the pathogenesis of excitatory neurodegeneration. Applying the 'indicator diffusion' method to the microdialysis te...

  20. [Enzymatic production of α-ketoglutaric acid by L-glutamate oxidase from L-glutamic acid].

    Science.gov (United States)

    Niu, Panqing; Zhang, Zhenyu; Liu, Liming

    2014-08-01

    We produced α-ketoglutaric acid (α-KG) from L-glutamic acid, using enzymatic transformation approach with L-glutamate oxidase (LGOX). First, wild strain Streptomyces sp. FMME066 was mutated with NTG, a genetically stable mutant Streptomyces sp. FMME067 was obtained. Under the optimal nutrition conditions with fructose 10 g/L, peptone 7.5 g/L, KH2PO4 1 g/L and CaCl2 0.05 g/L, the maximum LGOX activity reached 0.14 U/mL. The LGOX was stable to pH and temperature, and Mn2+ had a stimulating effect. Finally, after 24 h enzymatic conversion under the optimal conditions, the maximum titer of α-KG reached 38.1 g/L from 47 g/L L-glutamic acid. Enzymatic transformation by LGOX is a potential approach for α-KG production.

  1. 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...

  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. Conformational Studies on γ - Benzyl- L- Glutamate and L- Valine Containing Block Copolypeptides

    OpenAIRE

    Kumar, Ajay

    2010-01-01

    Conformational studies on γ - benzyl-L- glutamate and L- valine containing block copolypeptides are reported using IR and CD spectra. The block copolypeptides contain valine block in the center and on both sides of the valine are γ - benzyl- L- glutamate blocks. The changes in conformation with increase in chain length of γ - benzyl- L- glutamate blocks are observed. When the chain length of γ - benzyl-L- glutamate block is 13, the block copolypeptide crystallized into beta conformation. With...

  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. Coupled ion binding and structural transitions along the transport cycle of glutamate transporters

    OpenAIRE

    Verdon, Grégory; Oh, SeCheol; Serio, Ryan N; Boudker, Olga

    2014-01-01

    eLife digest Molecules of glutamate can carry messages between cells in the brain, and these signals are essential for thought and memory. Glutamate molecules can also act as signals to build new connections between brain cells and to prune away unnecessary ones. However, too much glutamate outside of the cells kills the brain tissue and can lead to devastating brain diseases. In a healthy brain, special pumps called glutamate transporters move these molecules back into the brain cells, where...

  6. CHARACTERIZATION OF A BINDING PROTEIN-DEPENDENT GLUTAMATE TRANSPORT-SYSTEM OF RHODOBACTER-SPHAEROIDES

    NARCIS (Netherlands)

    Jacobs, M.H J; Driessen, A.J.M.; Konings, W.N

    The mechanism of L-glutamate uptake was studied in Rhodobacter sphaeroides. Uptake of L-glutamate is mediated by a high-affinity (K-t of 1.2 mu M), shock-sensitive transport system that is inhibited by vanadate and dependent on the internal pH. From the shock fluid, an L-glutamate-binding protein

  7. Characterization of a Binding Protein-Dependent Glutamate Transport System of Rhodobacter sphaeroides

    NARCIS (Netherlands)

    Jacobs, Mariken H.J.; Driessen, Arnold J.M.; Konings, Wil N.

    1995-01-01

    The mechanism of L-glutamate uptake was studied in Rhodobacter sphaeroides. Uptake of L-glutamate is mediated by a high-affinity (Kt of 1.2 µM), shock-sensitive transport system that is inhibited by vanadate and dependent on the internal pH. From the shock fluid, an L-glutamate-binding protein was

  8. Bicarbonate and the pathway of glutamate oxidation in isolated rat-liver mitochondria

    NARCIS (Netherlands)

    Wanders, R. J.; Meijer, A. J.; Groen, A. K.; Tager, J. M.

    1983-01-01

    1. The factors affecting the pathway of glutamate oxidation were studied in isolated rat-liver mitochondria in incubations of 2-3 min. 2. It was found that bicarbonate at a physiological concentration has a profound effect on the pathway of glutamate oxidation. Ammonia formation via glutamate

  9. 40 CFR 721.3820 - L-Glutamic acid, N-(1-oxododecyl)-, disodium salt.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false L-Glutamic acid, N-(1-oxododecyl... Specific Chemical Substances § 721.3820 L-Glutamic acid, N-(1-oxododecyl)-, disodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as L-Glutamic...

  10. 21 CFR 573.500 - Condensed, extracted glutamic acid fermentation product.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Condensed, extracted glutamic acid fermentation... AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.500 Condensed, extracted glutamic acid fermentation product. Condensed, extracted glutamic acid fermentation product may be safely used in animal feed...

  11. 40 CFR 721.3821 - L-Glutamic acid, N-(1-oxododecyl)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false L-Glutamic acid, N-(1-oxododecyl... Substances § 721.3821 L-Glutamic acid, N-(1-oxododecyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as L-Glutamic acid, N-(1-oxododecyl)- (PMN P...

  12. 40 CFR 180.1187 - L-glutamic acid; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false L-glutamic acid; exemption from the... Exemptions From Tolerances § 180.1187 L-glutamic acid; exemption from the requirement of a tolerance. L-glutamic acid is exempt from the requirement of a tolerance on all food commodities when used in accordance...

  13. 78 FR 65269 - Monosodium Glutamate From the People's Republic of China and the Republic of Indonesia...

    Science.gov (United States)

    2013-10-31

    ...) petitions concerning imports of monosodium glutamate (MSG) from Indonesia and the PRC filed in proper form... September 26, 2013.\\3\\ \\1\\ See Countervailing Duty Petitions on Monosodium Glutamate from the PRC and... Duties and Countervailing Duties on Imports of Monosodium Glutamate from the People's Republic of China...

  14. Evolution and expression analysis of the soybean glutamate ...

    Indian Academy of Sciences (India)

    Evolution and expression analysis of the soybean glutamate decarboxylase gene family. TAE KYUNG HYUN, SEUNG HEE EOM, XIAO HAN and JU-SUNG KIM http://www.ias.ac.in/jbiosci. J. Biosci. 39(5), December 2014, 899–907, © Indian Academy of Sciences. Supplementary material. Supplementary figure 1.

  15. Anaplerosis for Glutamate Synthesis in the Neonate and in Adulthood

    DEFF Research Database (Denmark)

    Brekke, Eva; Morken, Tora Sund; Walls, Anne B

    2016-01-01

    A central task of the tricarboxylic acid (TCA, Krebs, citric acid) cycle in brain is to provide precursors for biosynthesis of glutamate, GABA, aspartate and glutamine. Three of these amino acids are the partners in the intricate interaction between astrocytes and neurons and form the so...

  16. Assay of partially purified glutamate dehydrogenase isolated from ...

    African Journals Online (AJOL)

    Glutamate dehydrogenase (E C 1.4.1.1) isolated from the seeds of asparagus beans was partially purified to a factor of 22 by dialysis after fractional precipitation with solid ammonium sulphate at 40 and 60% saturation. A specific activity of 11.78μmol min-1 mg-1 protein was calculated for the partially purified enzyme when ...

  17. Histological studies of the effects of monosodium glutamate on the ...

    African Journals Online (AJOL)

    Background: The effect of monosodium glutamate used as food additive on the fallopian tubes of adult Wistar rat was investigated. Material and Methods: Adult female Wistar rats (n=24) of average weight of 230g were randomly assigned into three groups A, B and C of (n=8) in each group. The treatment groups (A and B) ...

  18. Does formate reduce alpha-ketoglutarate and ammonia to glutamate?

    Science.gov (United States)

    Maughan, Q.; Miller, S. L.; Bada, J. L. (Principal Investigator)

    1999-01-01

    The reported reduction of alpha-ketoglutarate and ammonia by formate is much slower than described (Morowitz et al., 1995). The formate reduction if any is small under these conditions. Glutamate is produced from a reduction by a second molecule of alpha-ketoglutarate involving an oxidative decarboxylation.

  19. Effect of monosodium glutamate and aspartame on behavioral and ...

    African Journals Online (AJOL)

    The present study aimed to investigate the individual and combined effect of mono-sodium glutamate (MSG) and aspartame (ASM) on biochemical, blood parameters and neuro-behavioral aspects of mice. The results indicated that exposure induced many changes in fear and anxiety behavior. The non-social and social ...

  20. Effects Of Monosodium Glutamate (MSG) On The Histological ...

    African Journals Online (AJOL)

    An investigation was carried out on the effects of monosodium glutamate (MSG), a commonly ues food additive, on the spinal cord of adult Wistar rats. Twenty-four adult Wistar rats weighing between 180-250g were divided into four groups of six rats per group. Graduated doses of 6mg, 12mg and 18mg per kilogram body ...

  1. The effects of Groundnut, Spices, Monosodium Glutamate and Salt ...

    African Journals Online (AJOL)

    This study was intended to determine the effect of salt, groundnut, monosodium glutamate and spices, especially in combinations as used in Yaji, on the histology of the brain. The rats were divided into nine (9) groups (A – I) of eight rats (8) each. Groups A, B, C, D, E, F, G, H, constituted the test groups whereas group I ...

  2. probing the cob(ii)alamin conductor hypothesis with glutamate ...

    African Journals Online (AJOL)

    dell

    effect to weak interactions of O3' of the riboise moiety with either C19-H of the corrin ring or with the glutamate residue 330 of component E (Glu330). The catalytic inactivity of 2',5'- dideoxyadenosylcobalamin and peptidoadenylcobalamin reveals critical interactions of the 2'-OH moiety (O2') during the catalytic cycle.

  3. 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...

  4. Behavioral deficits in adult rats treated neonatally with glutamate

    Czech Academy of Sciences Publication Activity Database

    Hliňák, Zdeněk; Gandalovičová, D.; Krejčí, I.

    2005-01-01

    Roč. 27, č. 3 (2005), s. 465-473 ISSN 0892-0362 R&D Projects: GA MZd(CZ) NF6474 Institutional research plan: CEZ:AV0Z5011922 Keywords : neonatal treatment * monosodium glutamate * long-term effect Subject RIV: ED - Physiology Impact factor: 1.940, year: 2005

  5. Substrate Specificity via Ternary Complex Formation with Glutamate Dehydrogenase

    NARCIS (Netherlands)

    Koekoek, Henk; Robillard, George T.

    1977-01-01

    Very little discrimination is observed in the binary binding of dicarboxylic acid substrate analogues to glutamate dehydrogenase as monitored by proton nuclear magnetic resonance. Variation in length, charge, bulkiness and conformational rigidity resulted in only a factor of five variation in KD and

  6. Isolation and characterization of the rat gene encoding glutamate dehydrogenase

    NARCIS (Netherlands)

    Das, A. T.; Arnberg, A. C.; Malingré, H.; Moerer, P.; Charles, R.; Moorman, A. F.; Lamers, W. H.

    1993-01-01

    The concentration of glutamate dehydrogenase (GDH) varies strongly between different organs and between different regions within organs. To permit further studies on the regulation of GDH expression, we isolated and characterized the rat gene encoding the GDH protein. This gene contains 13 exons and

  7. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain two...

  8. Blood and Brain Glutamate Levels in Children with Autistic Disorder

    Science.gov (United States)

    Hassan, Tamer H.; Abdelrahman, Hadeel M.; Fattah, Nelly R. Abdel; El-Masry, Nagda M.; Hashim, Haitham M.; El-Gerby, Khaled M.; Fattah, Nermin R. Abdel

    2013-01-01

    Despite of the great efforts that move forward to clarify the pathophysiologic mechanisms in autism, the cause of this disorder, however, remains largely unknown. There is an increasing body of literature concerning neurochemical contributions to the pathophysiology of autism. We aimed to determine blood and brain levels of glutamate in children…

  9. 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)

  10. Effects of glycine and glutamic acid supplementation to low protein ...

    African Journals Online (AJOL)

    Reduction in CP below 190 g/kg led to a decline in body weight and feed intake and an increase in fat deposition in body, as would be expected. Plasma T4 concentration decreased significantly in the birds on the 170 g CP/kg diet and supplementation of glycine and glutamic acid had no effect on hormonal levels of the ...

  11. 78 FR 76321 - Monosodium Glutamate From China and Indonesia

    Science.gov (United States)

    2013-12-17

    ... United States at less than fair value (LTFV) and subsidized by the Governments of China and Indonesia. \\1... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-503-504 and 731-TA-1229-1230 (Preliminary)] Monosodium Glutamate From China and Indonesia Determinations On the basis of the record \\1...

  12. Examining the role of glutamic acid 183 in chloroperoxidase catalysis

    NARCIS (Netherlands)

    Yi, X.; Conesa, A.; Punt, P.J.; Hager, L.P.

    2003-01-01

    Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in

  13. Synthesis of Biobased Succinonitrile from Glutamic Acid and Glutamine

    NARCIS (Netherlands)

    Lammens, T.M.; Nôtre, Le J.; Franssen, M.C.R.; Scott, E.L.; Sanders, J.P.M.

    2011-01-01

    Succinonitrile is the precursor of 1,4-diaminobutane, which is used for the industrial production of polyamides. This paper describes the synthesis of biobased succinonitrile from glutamic acid and glutamine, amino acids that are abundantly present in many plant proteins. Synthesis of the

  14. Effect of dexamethasone on fetal hepatic glutamine-glutamate exchange

    NARCIS (Netherlands)

    M. Timmerman (Michelle); C. Teng; R.B. Wilkening; P.V. Fennessey (Paul); F.C. Battaglia (Frederick); G. Meschia

    2000-01-01

    textabstractIntravenous infusion of dexamethasone (Dex) in the fetal lamb causes a two- to threefold increase in plasma glutamine and other glucogenic amino acids and a decrease of plasma glutamate to approximately one-third of normal. To explore the underlying

  15. Glutamate metabolism in the brain focusing on astrocytes

    DEFF Research Database (Denmark)

    Schousboe, Arne; Scafidi, Susanna; Bak, Lasse Kristoffer

    2014-01-01

    Metabolism of glutamate, the main excitatory neurotransmitter and precursor of GABA, is exceedingly complex and highly compartmentalized in brain. Maintenance of these neurotransmitter pools is strictly dependent on the de novo synthesis of glutamine in astrocytes which requires both the anaplero......Metabolism of glutamate, the main excitatory neurotransmitter and precursor of GABA, is exceedingly complex and highly compartmentalized in brain. Maintenance of these neurotransmitter pools is strictly dependent on the de novo synthesis of glutamine in astrocytes which requires both...... the anaplerotic enzyme pyruvate carboxylase and glutamine synthetase. Glutamate is formed directly from glutamine by deamidation via phosphate activated glutaminase a reaction that also yields ammonia. Glutamate plays key roles linking carbohydrate and amino acid metabolism via the tricarboxylic acid (TCA) cycle......, as well as in nitrogen trafficking and ammonia homeostasis in brain. The anatomical specialization of astrocytic endfeet enables these cells to rapidly and efficiently remove neurotransmitters from the synaptic cleft to maintain homeostasis, and to provide glutamine to replenish neurotransmitter pools...

  16. Monosodium glutamate toxicity: Sida acuta leaf extract ameliorated ...

    African Journals Online (AJOL)

    The brain is reportedly sensitive to monosodium glutamate (MSG) toxicity via oxidative stress. Sida acuta leaf ethanolic extract (SALEE) possesses antioxidant activity which can mitigate this neurotoxicity. The present study investigated the possible protective effect of SALEE on MSG-induced toxicity in rats. Twenty-six ...

  17. Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

    1992-01-01

    A Plasmodium falciparum antigen gene coding for a 220-kD glutamate-rich protein (GLURP) has been cloned, and the 783 C-terminal amino acids of this protein (GLURP489-1271) have been expressed as a beta-galactosidase fusion protein in Escherichia coli. The encoded 783 amino acid residues contain t...

  18. Reduction of sodium content in spicy soups using monosodium glutamate

    DEFF Research Database (Denmark)

    Jinap, Selamat; Hajeb, Parvaneh; Karim, Roslina

    2016-01-01

    Background: Excessive dietary sodium intake causes several diseases, such as hypertension, cardiovascular and renal disease, etc. Hence, reducing sodium intake has been highly recommended. In this study the effect of monosodium glutamate (MSG), as an umami substance, on saltiness and sodium...

  19. Muscle pain sensitivity after glutamate injection is not modified by systemic administration of monosodium glutamate.

    Science.gov (United States)

    Shimada, Akiko; Castrillon, Eduardo; Baad-Hansen, Lene; Ghafouri, Bijar; Gerdle, Björn; Ernberg, Malin; Cairns, Brian; Svensson, Peter

    2015-01-01

    Monosodium glutamate (MSG) is often thought to be associated with headache and craniofacial pains like temporomandibular disorders. This randomized, double-blinded, placebo-controlled study was performed to investigate how ingestion of MSG affects muscle pain sensitivity before and after experimentally induced muscle pain. Sixteen healthy adult subjects participated in 2 sessions with at least 1-week interval between sessions. In each session, two injections of glutamate (Glu, 0.5 M, 0.2 ml) and two injections of saline (0.9%, 0.2 ml) into the masseter and temporalis muscles, respectively, were undertaken, with a 15 min interval between each injection. Injections of saline were made contralateral to Glu injections and done in a randomized order. Participants drank 400 mL of soda mixed with either MSG (150 mg/kg) or NaCl (24 mg/kg, placebo) 30 min before the intramuscular injections. Pressure pain thresholds (PPT), autonomic parameters and pain intensity were assessed prior to (baseline) and 30 min after ingestion of soda, as well as 5 min and 10 min after the intramuscular injections and at the end of the session. Whole saliva samples were collected prior to and 30, 45, 60, and 75 min after the ingestion of soda. MSG administration resulted in a significantly higher Glu level in saliva than administration of NaCl and was associated with a significant increase in systolic blood pressure. Injections of Glu were significantly more painful than injections of NaCl. However, ingestion of MSG did not change the intensity of Glu-evoked pain. Glu injections also significantly increased systolic and diastolic blood pressure, but without an additional effect of MSG ingestion. Glu injections into the masseter muscle significantly reduced the PPT. However, pre-injection MSG ingestion did not significantly alter this effect. Interestingly, PPT was significantly increased in the trapezius after MSG ingestion and intramuscular injection of Glu in the jaw muscles. The main finding

  20. On the potential role of glutamate transport in mental fatigue

    Directory of Open Access Journals (Sweden)

    Hansson Elisabeth

    2004-11-01

    Full Text Available Abstract Mental fatigue, with decreased concentration capacity, is common in neuroinflammatory and neurodegenerative diseases, often appearing prior to other major mental or physical neurological symptoms. Mental fatigue also makes rehabilitation more difficult after a stroke, brain trauma, meningitis or encephalitis. As increased levels of proinflammatory cytokines are reported in these disorders, we wanted to explore whether or not proinflammatory cytokines could induce mental fatigue, and if so, by what mechanisms. It is well known that proinflammatory cytokines are increased in major depression, "sickness behavior" and sleep deprivation, which are all disorders associated with mental fatigue. Furthermore, an influence by specific proinflammatory cytokines, such as interleukin (IL-1, on learning and memory capacities has been observed in several experimental systems. As glutamate signaling is crucial for information intake and processing within the brain, and due to the pivotal role for glutamate in brain metabolism, dynamic alterations in glutamate transmission could be of pathophysiological importance in mental fatigue. Based on this literature and observations from our own laboratory and others on the role of astroglial cells in the fine-tuning of glutamate neurotransmission we present the hypothesis that the proinflammatory cytokines tumor necrosis factor-α, IL-1β and IL-6 could be involved in the pathophysiology of mental fatigue through their ability to attenuate the astroglial clearance of extracellular glutamate, their disintegration of the blood brain barrier, and effects on astroglial metabolism and metabolic supply for the neurons, thereby attenuating glutamate transmission. To test whether our hypothesis is valid or not, brain imaging techniques should be applied with the ability to register, over time and with increasing cognitive loading, the extracellular concentrations of glutamate and potassium (K+ in humans suffering from

  1. On the potential role of glutamate transport in mental fatigue.

    Science.gov (United States)

    Rönnbäck, Lars; Hansson, Elisabeth

    2004-11-04

    Mental fatigue, with decreased concentration capacity, is common in neuroinflammatory and neurodegenerative diseases, often appearing prior to other major mental or physical neurological symptoms. Mental fatigue also makes rehabilitation more difficult after a stroke, brain trauma, meningitis or encephalitis. As increased levels of proinflammatory cytokines are reported in these disorders, we wanted to explore whether or not proinflammatory cytokines could induce mental fatigue, and if so, by what mechanisms.It is well known that proinflammatory cytokines are increased in major depression, "sickness behavior" and sleep deprivation, which are all disorders associated with mental fatigue. Furthermore, an influence by specific proinflammatory cytokines, such as interleukin (IL)-1, on learning and memory capacities has been observed in several experimental systems. As glutamate signaling is crucial for information intake and processing within the brain, and due to the pivotal role for glutamate in brain metabolism, dynamic alterations in glutamate transmission could be of pathophysiological importance in mental fatigue. Based on this literature and observations from our own laboratory and others on the role of astroglial cells in the fine-tuning of glutamate neurotransmission we present the hypothesis that the proinflammatory cytokines tumor necrosis factor-alpha, IL-1beta and IL-6 could be involved in the pathophysiology of mental fatigue through their ability to attenuate the astroglial clearance of extracellular glutamate, their disintegration of the blood brain barrier, and effects on astroglial metabolism and metabolic supply for the neurons, thereby attenuating glutamate transmission. To test whether our hypothesis is valid or not, brain imaging techniques should be applied with the ability to register, over time and with increasing cognitive loading, the extracellular concentrations of glutamate and potassium (K+) in humans suffering from mental fatigue. At

  2. Effects of added glutamate on liking for novel food flavors.

    Science.gov (United States)

    Prescott, John

    2004-04-01

    Adding glutamate to foods increases their umami quality, their acceptability and their consumption. The functional significance of this palatability is unclear. Other highly palatable substances, e.g. sugar and fats, also increase liking for novel flavors with which they are repeatedly paired, especially when ingested. This is thought to reflect the rewarding effects of sugar and fat energy, post-ingestion. To determine if a liking for novel flavors can also be conditioned using glutamate, 44 subjects rated 10 ml samples of three novel soups for liking and familiarity, both before and after seven daily exposures to each of two soup flavors-one with added monosodium l-glutamate (MSG) (0.5% w/w; MSG+) and one without (MSG-). During exposure, subjects received either a 250 ml bowl of soup (Consume group) or a 10 ml sample (Taste group). There were no significant differences as a function of samples or groups, despite some trends for changes in liking to be higher in the consumed MSG+ condition. In a second experiment, 69 subjects were divided into three groups (Consume MSG+; Consume MSG-; Taste MSG+) in which they received nine exposures to one novel soup flavor. The Consume MSG+ group showed a significantly greater increase in liking than either the Consume MSG- or the Taste MSG+ groups, which did not differ. Changes in familiarity ratings reflected amount consumed, not MSG content. Pairing glutamate with a novel flavor can condition liking for that flavor. While post-ingestive effects of glutamate may be rewarding, flavor conditioning cannot be ruled out.

  3. Glutamate and GABA in vestibulo-sympathetic pathway neurons

    Directory of Open Access Journals (Sweden)

    Gay R Holstein

    2016-02-01

    Full Text Available The vestibulo-sympathetic reflex actively modulates blood pressure during changes in posture. This reflex allows humans to stand up and quadrupeds to rear or climb without a precipitous decline in cerebral perfusion. The vestibulo-sympathetic reflex pathway conveys signals from the vestibular end organs to the caudal vestibular nuclei. These cells, in turn, project to pre-sympathetic neurons in the rostral and caudal ventrolateral medulla (RVLM and CVLM, respectively. The present study assessed glutamate- and GABA-related immunofluorescence associated with central vestibular neurons of the vestibulo-sympathetic reflex pathway in rats. Retrograde FluoroGold tract tracing was used to label vestibular neurons with projections to RVLM or CVLM, and sinusoidal galvanic vestibular stimulation was employed to activate these pathways. Central vestibular neurons of the vestibulo-sympathetic reflex were identified by co-localization of FluoroGold and cFos protein, which accumulates in some vestibular neurons following galvanic stimulation. Triple-label immunofluorescence was used to co-localize glutamate- or GABA- labeling in the identified vestibulo-sympathetic reflex pathway neurons. Most activated projection neurons displayed intense glutamate immunofluorescence, suggestive of glutamatergic neurotransmission. To support this, anterograde tracer was injected into the caudal vestibular nuclei. Vestibular axons and terminals in RVLM and CVLM co-localized the anterograde tracer and vesicular glutamate transporter-2 signals. Other retrogradely-labeled cFos-positive neurons displayed intense GABA immunofluorescence. Vestibulo-sympathetic reflex pathway neurons of both phenotypes were present in the caudal medial and spinal vestibular nuclei, and projected to both RVLM and CVLM. As a group, however, triple-labeled vestibular cells with intense glutamate immunofluorescence were located more rostrally in the vestibular nuclei than the GABAergic neurons. Only the

  4. Laser-scanning astrocyte mapping reveals increased glutamate-responsive domain size and disrupted maturation of glutamate uptake following neonatal cortical freeze-lesion

    Directory of Open Access Journals (Sweden)

    Mortiz eArmbruster

    2014-09-01

    Full Text Available Astrocytic uptake of glutamate shapes extracellular neurotransmitter dynamics, receptor activation, and synaptogenesis. During development, glutamate transport becomes more robust. How neonatal brain insult affects the functional maturation of glutamate transport remains unanswered. Neonatal brain insult can lead to developmental delays, cognitive losses, and epilepsy; the disruption of glutamate transport is known to cause changes in synaptogenesis, receptor activation, and seizure. Using the neonatal freeze-lesion (FL model, we have investigated how insult affects the maturation of astrocytic glutamate transport. As lesioning occurs on the day of birth, a time when astrocytes are still functionally immature, this model is ideal for identifying changes in astrocyte maturation following insult. Reactive astrocytosis, astrocyte proliferation, and in vitro hyperexcitability are known to occur in this model. To probe astrocyte glutamate transport with better spatial precision we have developed a novel technique, Laser Scanning Astrocyte Mapping (LSAM, which combines glutamate transport current (TC recording from astrocytes with laser scanning glutamate photolysis. LSAM allows us to identify the area from which a single astrocyte can transport glutamate and to quantify spatial heterogeneity in the rate of glutamate clearance kinetics within that domain. Using LSAM, we report that cortical astrocytes have an increased glutamate-responsive area following FL and that TCs have faster decay times in distal, as compared to proximal processes. Furthermore, the developmental shift from GLAST- to GLT-1-dominated clearance is disrupted following FL. These findings introduce a novel method to probe astrocyte glutamate uptake and show that neonatal cortical FL disrupts the functional maturation of cortical astrocytes.

  5. 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.

  6. Differential contribution of the proline and glutamine pathways to glutamate biosynthesis and nitrogen assimilation in yeast lacking glutamate dehydrogenase.

    Science.gov (United States)

    Sieg, Alex G; Trotter, Pamela J

    2014-01-01

    In Saccharomyces cerevisiae, the glutamate dehydrogenase (GDH) enzymes play a pivotal role in glutamate biosynthesis and nitrogen assimilation. It has been proposed that, in GDH-deficient yeast, either the proline utilization (PUT) or the glutamine synthetase-glutamate synthase (GS/GOGAT) pathway serves as the alternative pathway for glutamate production and nitrogen assimilation to the exclusion of the other. Using a gdh-null mutant (gdh1Δ2Δ3Δ), this ambiguity was addressed using a combination of growth studies and pathway-specific enzyme assays on a variety of nitrogen sources (ammonia, glutamine, proline and urea). The GDH-null mutant was viable on all nitrogen sources tested, confirming that alternate pathways for nitrogen assimilation exist in the gdh-null strain. Enzyme assays point to GS/GOGAT as the primary alternative pathway on the preferred nitrogen sources ammonia and glutamine, whereas growth on proline required both the PUT and GS/GOGAT pathways. In contrast, growth on glucose-urea media elicited a decrease in GOGAT activity along with an increase in activity of the PUT pathway specific enzyme Δ(1)-pyrroline-5-carboxylate dehydrogenase (P5CDH). Together, these results suggest the alternative pathway for nitrogen assimilation in strains lacking the preferred GDH-dependent route is nitrogen source dependent and that neither GS/GOGAT nor PUT serves as the sole compensatory pathway. Copyright © 2014 Elsevier GmbH. All rights reserved.

  7. Deletion of genes involved in glutamate metabolism to improve poly-gamma-glutamic acid production in B. amyloliquefaciens LL3.

    Science.gov (United States)

    Zhang, Wei; He, Yulian; Gao, Weixia; Feng, Jun; Cao, Mingfeng; Yang, Chao; Song, Cunjiang; Wang, Shufang

    2015-02-01

    Here, we attempted to elevate poly-gamma-glutamic acid (γ-PGA) production by modifying genes involved in glutamate metabolism in Bacillus amyloliquefaciens LL3. Products of rocR, rocG and gudB facilitate the conversion from glutamate to 2-oxoglutarate in Bacillus subtillis. The gene odhA is responsible for the synthesis of a component of the 2-oxoglutarate dehydrogenase complex that catalyzes the oxidative decarboxylation of 2-oxoglutarate to succinyl coenzyme A. In-frame deletions of these four genes were performed. In shake flask experiments the gudB/rocG double mutant presented enhanced production of γ-PGA, a 38 % increase compared with wild type. When fermented in a 5-L fermenter with pH control, the γ-PGA yield of the rocR mutant was increased to 5.83 g/L from 4.55 g/L for shake flask experiments. The gudB/rocG double mutant produced 5.68 g/L γ-PGA compared with that of 4.03 g/L for the wild type, a 40 % increase. Those results indicated the possibility of improving γ-PGA production by modifying glutamate metabolism, and identified potential genetic targets to improve γ-PGA production.

  8. Expression of the human isoform of glutamate dehydrogenase, hGDH2, augments TCA cycle capacity and oxidative metabolism of glutamate during glucose deprivation in astrocytes

    DEFF Research Database (Denmark)

    Nissen, Jakob D; Lykke, Kasper; Bryk, Jaroslaw

    2017-01-01

    A key enzyme in brain glutamate homeostasis is glutamate dehydrogenase (GDH) which links carbohydrate and amino acid metabolism mediating glutamate degradation to CO2 and expanding tricarboxylic acid (TCA) cycle capacity with intermediates, i.e. anaplerosis. Humans express two GDH isoforms, GDH1...... and supports the TCA cycle during energy-demanding processes such as high intensity glutamatergic signaling. However, little is known about how expression of hGDH2 affects the handling of glutamate and TCA cycle metabolism in astrocytes. Therefore, we cultured astrocytes from cerebral cortical tissue of hGDH2...

  9. Glutamate monitoring in vitro and in vivo: recent progress in the field of glutamate biosensors

    DEFF Research Database (Denmark)

    Rieben, Nathalie Ines; Rose, Nadia Cherouati; Martinez, Karen Laurence

    2009-01-01

    such as Alzheimer's, Parkinson's and Huntington's diseases, as well as ischemic stroke and amyotrophic lateral sclerosis. Accurate measurement of glutamate levels in vitro and in vivo for a better understanding of the physiological and pathological role of glutamate in neurotransmission has remained challenging...... is currently the most common method for in vivo glutamate sampling. However, the recent development and improvement of enzyme-based amperometric glutamate biosensors makes them a promising alternative to microdialysis for in vivo applications, as well as valuable devices for in vitro applications in basic...

  10. MDMA decreases glutamic acid decarboxylase (GAD) 67-immunoreactive neurons in the hippocampus and increases seizure susceptibility: Role for glutamate.

    Science.gov (United States)

    Huff, Courtney L; Morano, Rachel L; Herman, James P; Yamamoto, Bryan K; Gudelsky, Gary A

    2016-12-01

    3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37-58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Glutamate release from satellite glial cells of the murine trigeminal ganglion.

    Science.gov (United States)

    Wagner, Lysann; Warwick, Rebekah A; Pannicke, Thomas; Reichenbach, Andreas; Grosche, Antje; Hanani, Menachem

    2014-08-22

    It has been proposed that glutamate serves as a mediator between neurons and satellite glial cells (SGCs) in sensory ganglia and that SGCs release glutamate. Using a novel method, we studied glutamate release from SGCs from murine trigeminal ganglia. Sensory neurons with adhering SGCs were enzymatically isolated from wild type and transgenic mice in which vesicular exocytosis was suppressed in glial cells. Extracellular glutamate was detected by microfluorimetry. After loading the cells with a photolabile Ca(2+) chelator, the intracellular Ca(2+) concentration was raised in SGCs by a UV pulse, which resulted in glutamate release. The amount of released glutamate was decreased in cells with suppressed exocytosis and after pharmacological block of hemichannels. The data demonstrate that SGCs of the trigeminal ganglion release glutamate in a Ca(2+)-dependent manner. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. GDH-Dependent Glutamate Oxidation in the Brain Dictates Peripheral Energy Substrate Distribution

    DEFF Research Database (Denmark)

    Karaca, Melis; Frigerio, Francesca; Migrenne, Stephanie

    2015-01-01

    glutamate dehydrogenase (GDH) activity. Here, we investigated the significance of glutamate as energy substrate for the brain. Upon glutamate exposure, astrocytes generated ATP in a GDH-dependent way. The observed lack of glutamate oxidation in brain-specific GDH null CnsGlud1(-/-) mice resulted......Glucose, the main energy substrate used in the CNS, is continuously supplied by the periphery. Glutamate, the major excitatory neurotransmitter, is foreseen as a complementary energy contributor in the brain. In particular, astrocytes actively take up glutamate and may use it through oxidative....... Our data reveal the importance of glutamate as necessary energy substrate for the brain and the role of central GDH in the regulation of whole-body energy homeostasis....

  13. Effect of insulin on the compartmentation of glutamate for protein synthesis

    International Nuclear Information System (INIS)

    Brown, A.B.; Mohan, C.; Bessman, S.P.

    1986-01-01

    The effect of insulin on the formation of CO 2 and incorporation of 1- 14 C glutamine and U- 14 C acetate into protein was studied in isolated rat hepatocytes. Insulin caused an 18% increase in 14 CO 2 production from U- 14 C acetate in comparison to a 10% increase from 1- 14 C glutamate. Insulin caused a greater increase in the incorporation of tracer acetate carbons into hepatocyte protein. Hydrolysis of labeled protein and subsequent determination of glutamate specific activity revealed that incorporation of acetate carbons into protein as glutamate was about 52% greater in the presence of insulin. These results demonstrate the existence of two compartments of glutamate for protein synthesis: (i) glutamate generated in the Krebs cycle through transamination of a-ketoglutarate; (ii) cytosolic glutamate. Insulin had a greater stimulatory effect on the incorporation of glutamate generated in the Krebs cycle

  14. Glutamic acid and its derivatives: candidates for rational design of anticancer drugs.

    Science.gov (United States)

    Ali, Imran; Wani, Waseem A; Haque, Ashanul; Saleem, Kishwar

    2013-05-01

    Throughout the history of human civilizations, cancer has been a major health problem. Its treatment has been interesting but challenging to scientists. Glutamic acid and its derivative glutamine are known to play interesting roles in cancer genesis, hence, it was realized that structurally variant glutamic acid derivatives may be designed and developed and, might be having antagonistic effects on cancer. The present article describes the state-of-art of glutamic acid and its derivatives as anticancer agents. Attempts have been made to explore the effectivity of drug-delivery systems based on glutamic acid for the delivery of anticancer drugs. Moreover, efforts have also been made to discuss the mechanism of action of glutamic acid derivatives as anticancer agents, clinical applications of glutamic acid derivatives, as well as recent developments and future perspectives of glutamic acid drug development have also been discussed.

  15. Glutamate Metabolism in Brain Structures in Experimental Hemorrhagic Shock

    Directory of Open Access Journals (Sweden)

    V. N. Jakovlev

    2017-01-01

    Full Text Available Purpose. To study glutamate metabolism characteristics in phylogenetically different parts of the mammalian brain in experimentally induced hemorrhagic shock (HS in cats.Material and methods. Experiments were performed on 76 cats. HS was induced by intermittent bloodletting from femoral artery at a rate of 10ml/kg•10 minutes, with the average volume of 24±0.8 ml/kg. The bloodletting was discontinued after arterial pressure (BP drop to 60.0±1.5 mmHg. We studied ammonia, glutamate (Gt, and α-ketoglutarate (α-KG levels and glutaminase (GS and glutamate dehydrogenase (GDG activity in specimens harvested from phylogenetically different parts of the brain (cortex, limbic system, diencephalon, and medulla oblongata.Results. In intact animals, the peak GDG activity was found in the medulla oblongata (phylogenetically the oldest part of the brain and the peak GS activity was registered in the sensorimotor cortex (phylogenetically the youngest part of the brain; the glutaminase activity did not depend on the phylogenetic age of brain structures.In the case of HS, Gt metabolism changes began in the sensorimotor cortex manifested by decreased GS activity, which progresses by the 70th minute of the post%hemorrhagic period (PHP accompanied by delayed increase in the GDG and glutaminase activity, as well as Gt accumulation. In the limbic system and diencephalon the Gt metabolism was changing (impaired glutamine synthesis, stimuled Gt synthesis with glutamine desamidization and α%KG amination when developed by the 70th minute of the PHP. Similarly to sensorimotor cortex, changes were associated with Gt accumulation. During the agony, α%KG deficiency developed in all parts of the brain as a result of its increased contribution to Gt synthesis. At the same period of time, in the sensorimotor cortex, limbic system and diencephalon the Gt synthesis from glutamine was stimulated, however, the Gt contribution tothe formation of glutamine was decreased. The

  16. Identification of a Novel Activator of Mammalian Glutamate Dehydrogenase.

    Science.gov (United States)

    Smith, Hong Q; Smith, Thomas J

    2016-11-29

    Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of l-glutamate and in animals is highly regulated. GDH in hyperinsulinism/hyperammonemia syndrome patients lacks GTP inhibition, resulting in hypersecretion of insulin upon protein consumption. This suggests insulin secretion could be stimulated with GDH activators. A high-throughput screen yielded one potent activator, N1-[4-(2-aminopyrimidin-4-yl)phenyl]-3-(trifluoromethyl)benzene-1-sulfonamide (75-E10). 75-E10 is ∼1000-fold more efficacious than the synthetic activator, BCH, and is at least as effective as ADP. 75-E10 compound is highly effective at alleviating GTP inhibition and may be binding to the ADP site. Unlike ADP, 75-E10 is activated over a broad range of conditions.

  17. Conformation of poly(γ-glutamic acid) in aqueous solution.

    Science.gov (United States)

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε acidic media. © 2015 Wiley Periodicals, Inc.

  18. [Synthesis and pharmacologic study of diethyl N-palmitoyl glutamate].

    Science.gov (United States)

    Vamvakides, A; Kolocouris, N

    1989-01-01

    The diethyl N-palmitoyl glutamate (DEEPGt) was synthesized by the mixed anhydrides method and pharmacologically studied; hypothermy, sedation, myorelaxation and antagonism of the pentetrazole (PTZ) convulsions were obtained in mice. The haloperidol catalepsy's potentiation coming with oral dyskinesias were observed on rats. It seems, in the light of this pharmacological exploration, that DEEPGt penetrates easily in the brain and develops an anti-glutamatergic activity. It is probably the slow liberation of N-palmitoyl glutamic acid (PGt) from the DEEPGt which amplifies its anti-PTZ activity and could be interesting against the memory impairing action of all the glutamatergic antagonists which are actually considered as the possible next generation of antiepileptic and neuroprotecting drugs.

  19. Sexual attraction enhances glutamate transmission in mammalian anterior cingulate cortex

    Directory of Open Access Journals (Sweden)

    Wu Long-Jun

    2009-05-01

    Full Text Available Abstract Functional human brain imaging studies have indicated the essential role of cortical regions, such as the anterior cingulate cortex (ACC, in romantic love and sex. However, the neurobiological basis of how the ACC neurons are activated and engaged in sexual attraction remains unknown. Using transgenic mice in which the expression of green fluorescent protein (GFP is controlled by the promoter of the activity-dependent gene c-fos, we found that ACC pyramidal neurons are activated by sexual attraction. The presynaptic glutamate release to the activated neurons is increased and pharmacological inhibition of neuronal activities in the ACC reduced the interest of male mice to female mice. Our results present direct evidence of the critical role of the ACC in sexual attraction, and long-term increases in glutamate mediated excitatory transmission may contribute to sexual attraction between male and female mice.

  20. The role of histidine residues in glutamate dehydrogenase

    Science.gov (United States)

    Tudball, N.; Bailey-Wood, R.; Thomas, P.

    1972-01-01

    1. Glutamate dehydrogenase was subject to rapid inactivation when irradiated in the presence of Rose Bengal or incubated in the presence of ethoxyformic anhydride. 2. Inactivation in the presence of Rose Bengal led to the photo-oxidation of four histidine residues. Oxidation of three histidine residues had little effect on enzyme activity, but oxidation of the fourth residue led to the almost total loss of activity. 3. Acylation of glutamate dehydrogenase with ethoxyformic anhydride at pH6.1 led to the modification of three histidine residues with a corresponding loss of half the original activity. Acylation at pH7.5 led to the modification of two histidine residues and a total loss of enzyme activity. 4. One of the histidine residues undergoing reaction at pH6.1 also undergoes reaction at pH7.5. 5. The presence of either glutamate or NAD+ in the reaction mixtures at pH6.1 had no appreciable effect. At pH7.5 glutamate caused a marked decrease in both the degree of alkylation and degree of inactivation. NAD+ had no effect on the degree of inactivation at pH7.5 but did modify the extent of acylation. 6. The normal response of the enzyme towards ADP was unaffected by acylation at pH6.1 or 7.5. 7. The normal response of the enzyme towards GTP was altered by treatment at both pH6.1 and 7.5. PMID:4345275

  1. Pharmacology of Glutamate Transport in the CNS: Substrates and Inhibitors of Excitatory Amino Acid Transporters (EAATs) and the Glutamate/Cystine Exchanger System x c -

    Science.gov (United States)

    Bridges, Richard J.; Patel, Sarjubhai A.

    As the primary excitatory neurotransmitter in the mammalian CNS, l-glutamate participates not only in standard fast synaptic communication, but also contributes to higher order signal processing, as well as neuropathology. Given this variety of functional roles, interest has been growing as to how the extracellular concentrations of l-glutamate surrounding neurons are regulated by cellular transporter proteins. This review focuses on two prominent systems, each of which appears capable of influencing both the signaling and pathological actions of l-glutamate within the CNS: the sodium-dependent excitatory amino acid transporters (EAATs) and the glutamate/cystine exchanger, system x c - (Sx c -). While the family of EAAT subtypes limit access to glutamate receptors by rapidly and efficiently sequestering l-glutamate in neurons and glia, Sxc - provides a route for the export of glutamate from cells into the extracellular environment. The primary intent of this work is to provide an overview of the inhibitors and substrates that have been developed to delineate the pharmacological specificity of these transport systems, as well as be exploited as probes with which to selectively investigate function. Particular attention is paid to the development of small molecule templates that mimic the structural properties of the endogenous substrates, l-glutamate, l-aspartate and l-cystine and how strategic control of functional group position and/or the introduction of lipophilic R-groups can impact multiple aspects of the transport process, including: subtype selectivity, inhibitory potency, and substrate activity.

  2. Complete Genome Sequence of Bacillus amyloliquefaciens LL3, Which Exhibits Glutamic Acid-Independent Production of Poly-γ-Glutamic Acid▿

    OpenAIRE

    Geng, Weitao; Cao, Mingfeng; Song, Cunjiang; Xie, Hui; Liu, Li; Yang, Chao; Feng, Jun; Zhang, Wei; Jin, Yinghong; Du, Yang; Wang, Shufang

    2011-01-01

    Bacillus amyloliquefaciens is one of most prevalent Gram-positive aerobic spore-forming bacteria with the ability to synthesize polysaccharides and polypeptides. Here, we report the complete genome sequence of B. amyloliquefaciens LL3, which was isolated from fermented food and presents the glutamic acid-independent production of poly-γ-glutamic acid.

  3. A Glutamic Acid-Producing Lactic Acid Bacteria Isolated from Malaysian Fermented Foods

    Directory of Open Access Journals (Sweden)

    Bita Forghani

    2012-05-01

    Full Text Available L-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218 were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA as a bioactive compound.

  4. 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.

  5. A Glutamic Acid-Producing Lactic Acid Bacteria Isolated from Malaysian Fermented Foods

    Science.gov (United States)

    Zareian, Mohsen; Ebrahimpour, Afshin; Bakar, Fatimah Abu; Mohamed, Abdul Karim Sabo; Forghani, Bita; Ab-Kadir, Mohd Safuan B.; Saari, Nazamid

    2012-01-01

    l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound. PMID:22754309

  6. Morphine Protects Spinal Cord Astrocytes from Glutamate-Induced Apoptosis via Reducing Endoplasmic Reticulum Stress

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2016-10-01

    Full Text Available Glutamate is not only a neurotransmitter but also an important neurotoxin in central nervous system (CNS. Chronic elevation of glutamate induces both neuronal and glial cell apoptosis. However, its effect on astrocytes is complex and still remains unclear. In this study, we investigated whether morphine, a common opioid ligand, could affect glutamate-induced apoptosis in astrocytes. Primary cultured astrocytes were incubated with glutamate in the presence/absence of morphine. It was found that morphine could reduce glutamate-induced apoptosis of astrocytes. Furthermore, glutamate activated Ca2+ release, thereby inducing endoplasmic reticulum (ER stress in astrocytes, while morphine attenuated this deleterious effect. Using siRNA to reduce the expression of κ-opioid receptor, morphine could not effectively inhibit glutamate-stimulated Ca2+ release in astrocytes, the protective effect of morphine on glutamate-injured astrocytes was also suppressed. These results suggested that morphine could protect astrocytes from glutamate-induced apoptosis via reducing Ca2+ overload and ER stress pathways. In conclusion, this study indicated that excitotoxicity participated in the glutamate mediated apoptosis in astrocytes, while morphine attenuated this deleterious effect via regulating Ca2+ release and ER stress.

  7. Crystal structure of a chimaeric bacterial glutamate dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Tânia; Sharkey, Michael A.; Engel, Paul C.; Khan, Amir R.

    2016-05-23

    Glutamate dehydrogenases (EC 1.4.1.2–4) catalyse the oxidative deamination of L-glutamate to α-ketoglutarate using NAD(P)+as a cofactor. The bacterial enzymes are hexameric, arranged with 32 symmetry, and each polypeptide consists of an N-terminal substrate-binding segment (domain I) followed by a C-terminal cofactor-binding segment (domain II). The catalytic reaction takes place in the cleft formed at the junction of the two domains. Distinct signature sequences in the nucleotide-binding domain have been linked to the binding of NAD+versusNADP+, but they are not unambiguous predictors of cofactor preference. In the absence of substrate, the two domains move apart as rigid bodies, as shown by the apo structure of glutamate dehydrogenase fromClostridium symbiosum. Here, the crystal structure of a chimaeric clostridial/Escherichia colienzyme has been determined in the apo state. The enzyme is fully functional and reveals possible determinants of interdomain flexibility at a hinge region following the pivot helix. The enzyme retains the preference for NADP+cofactor from the parentE. colidomain II, although there are subtle differences in catalytic activity.

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

    Directory of Open Access Journals (Sweden)

    Nicholas P Vyleta

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

  9. Computational design of glutamate dehydrogenase in Bacillus subtilis natto.

    Science.gov (United States)

    Chen, Li-Li; Wang, Jia-Le; Hu, Yu; Qian, Bing-Jun; Yao, Xiao-Min; Wang, Jing-Fang; Zhang, Jian-Hua

    2013-04-01

    Bacillus subtilis natto is widely used in industry to produce natto, a traditional and popular Japanese soybean food. However, during its secondary fermentation, high amounts of ammonia are released to give a negative influence on the flavor of natto. Glutamate dehydrogenase (GDH) is a key enzyme for the ammonia produced and released, because it catalyzes the oxidative deamination of glutamate to alpha-ketoglutarate using NAD(+) or NADP(+) as co-factor during carbon and nitrogen metabolism processes. To solve this problem, we employed multiple computational methods model and re-design GDH from Bacillus subtilis natto. Firstly, a structure model of GDH with cofactor NADP(+) was constructed by threading and ab initio modeling. Then the substrate glutamate were flexibly docked into the structure model to form the substrate-binding mode. According to the structural analysis of the substrate-binding mode, Lys80, Lys116, Arg196, Thr200, and Ser351 in the active site were found could form a significant hydrogen bonding network with the substrate, which was thought to play a crucial role in the substrate recognition and position. Thus, these residues were then mutated into other amino acids, and the substrate binding affinities for each mutant were calculated. Finally, three single mutants (K80A, K116Q, and S351A) were found to have significant decrease in the substrate binding affinities, which was further supported by our biochemical experiments.

  10. Intertissue differences for the role of glutamate dehydrogenase in metabolism.

    Science.gov (United States)

    Treberg, Jason R; Banh, Sheena; Pandey, Umesh; Weihrauch, Dirk

    2014-01-01

    The enzyme glutamate dehydrogenase (GDH) plays an important role in integrating mitochondrial metabolism of amino acids and ammonia. Glutamate may function as a respiratory substrate in the oxidative deamination direction of GDH, which also yields α-ketoglutarate. In the reductive amination direction GDH produces glutamate, which can then be used for other cellular needs such as amino acid synthesis via transamination. The production or removal of ammonia by GDH is also an important consequence of flux through this enzyme. However, the abundance and role of GDH in cellular metabolism varies by tissue. Here we discuss the different roles the house-keeping form of GDH has in major organs of the body and how GDH may be important to regulating aspects of intermediary metabolism. The near-equilibrium poise of GDH in liver and controversy over cofactor specificity and regulation is discussed, as well as, the role of GDH in regulation of renal ammoniagenesis, and the possible importance of GDH activity in the release of nitrogen carriers by the small intestine.

  11. Isocitrate Dehydrogenase and Glutamate Synthesis in Acetobacter suboxydans1

    Science.gov (United States)

    Greenfield, Seymour; Claus, G. W.

    1969-01-01

    Acetobacter suboxydans is an obligate aerobe for which an operative tricarboxylic acid cycle has not been demonstrated. Glutamate synthesis has been reported to occur by mechanisms other than those utilizing isocitrate dehydrogenase, a tricarboxylic acid cycle enzyme not previously detected in this organism. We have recovered α-ketoglutarate and glutamate from a system containing citrate, nicotinamide adenine dinucleotide (NAD), a divalent cation, pyridoxal phosphate, an amino donor, and dialyzed, cell-free extract. Aconitase activity was readily detected in these extracts, but isocitrate dehydrogenase activity, measured by NAD reduction, was masked by a cyanide-resistant, particulate, reduced NAD oxidase. Isocitrate dehydrogenase activity could be demonstrated after centrifuging the extracts at 150,000 × g for 3 hr and treating the supernatant fluid with 2-heptyl-4-hydroxyquinoline N-oxide. It is concluded that A. suboxydans can utilize the conventional tricarboxylic acid cycle enzymes to convert citrate to α-ketoglutarate which can then undergo a transamination to glutamate. Images PMID:5361215

  12. Crystal structure of a chimaeric bacterial glutamate dehydrogenase.

    Science.gov (United States)

    Oliveira, Tânia; Sharkey, Michael A; Engel, Paul C; Khan, Amir R

    2016-06-01

    Glutamate dehydrogenases (EC 1.4.1.2-4) catalyse the oxidative deamination of L-glutamate to α-ketoglutarate using NAD(P)(+) as a cofactor. The bacterial enzymes are hexameric, arranged with 32 symmetry, and each polypeptide consists of an N-terminal substrate-binding segment (domain I) followed by a C-terminal cofactor-binding segment (domain II). The catalytic reaction takes place in the cleft formed at the junction of the two domains. Distinct signature sequences in the nucleotide-binding domain have been linked to the binding of NAD(+) versus NADP(+), but they are not unambiguous predictors of cofactor preference. In the absence of substrate, the two domains move apart as rigid bodies, as shown by the apo structure of glutamate dehydrogenase from Clostridium symbiosum. Here, the crystal structure of a chimaeric clostridial/Escherichia coli enzyme has been determined in the apo state. The enzyme is fully functional and reveals possible determinants of interdomain flexibility at a hinge region following the pivot helix. The enzyme retains the preference for NADP(+) cofactor from the parent E. coli domain II, although there are subtle differences in catalytic activity.

  13. Glutamate and GABA-metabolizing enzymes in post-mortem cerebellum in Alzheimer's disease: phosphate-activated glutaminase and glutamic acid decarboxylase.

    Science.gov (United States)

    Burbaeva, G Sh; Boksha, I S; Tereshkina, E B; Savushkina, O K; Prokhorova, T A; Vorobyeva, E A

    2014-10-01

    Enzymes of glutamate and GABA metabolism in postmortem cerebellum from patients with Alzheimer's disease (AD) have not been comprehensively studied. The present work reports results of original comparative study on levels of phosphate-activated glutaminase (PAG) and glutamic acid decarboxylase isoenzymes (GAD65/67) in autopsied cerebellum samples from AD patients and matched controls (13 cases in each group) as well as summarizes published evidence for altered levels of PAG and GAD65/67 in AD brain. Altered (decreased) levels of these enzymes and changes in links between amounts of these enzymes and other glutamate-metabolizing enzymes (such as glutamate dehydrogenase and glutamine synthetase-like protein) in AD cerebella suggest significantly impaired glutamate and GABA metabolism in this brain region, which was previously regarded as not substantially involved in AD pathogenesis.

  14. 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...

  15. Delineation of glutamate pathways and secretory responses in pancreatic islets with β-cell-specific abrogation of the glutamate dehydrogenase

    DEFF Research Database (Denmark)

    Vetterli, Laurène; Carobbio, Stefania; Pournourmohammadi, Shirin

    2012-01-01

    In pancreatic β-cells, glutamate dehydrogenase (GDH) modulates insulin secretion, although its function regarding specific secretagogues is unclear. This study investigated the role of GDH using a β-cell-specific GDH knockout mouse model, called βGlud1(-/-). The absence of GDH in islets isolated...... from βGlud1(-/-) mice resulted in abrogation of insulin release evoked by glutamine combined with 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid or l-leucine. Reintroduction of GDH in βGlud1(-/-) islets fully restored the secretory response. Regarding glucose stimulation, insulin secretion in islets...... isolated from βGlud1(-/-) mice exhibited half of the response measured in control islets. The amplifying pathway, tested at stimulatory glucose concentrations in the presence of KCl and diazoxide, was markedly inhibited in βGlud1(-/-) islets. On glucose stimulation, net synthesis of glutamate from α...

  16. Reduced expression of glutamate transporter EAAT2 and impaired glutamate transport in human primary astrocytes exposed to HIV-1 or gp120

    International Nuclear Information System (INIS)

    Wang Zhuying; Pekarskaya, Olga; Bencheikh, Meryem; Chao Wei; Gelbard, Harris A.; Ghorpade, Anuja; Rothstein, Jeffrey D.; Volsky, David J.

    2003-01-01

    L-Glutamate is the major excitatory neurotransmitter in the brain. Astrocytes maintain low levels of synaptic glutamate by high-affinity uptake and defects in this function may lead to neuronal cell death by excitotoxicity. We tested the effects of HIV-1 and its envelope glycoprotein gp120 upon glutamate uptake and expression of glutamate transporters EAAT1 and EAAT2 in fetal human astrocytes in vitro. Astrocytes isolated from fetal tissues between 16 and 19 weeks of gestation expressed EAAT1 and EAAT2 RNA and proteins as detected by Northern blot analysis and immunoblotting, respectively, and the cells were capable of specific glutamate uptake. Exposure of astrocytes to HIV-1 or gp120 significantly impaired glutamate uptake by the cells, with maximum inhibition within 6 h, followed by gradual decline during 3 days of observation. HIV-1-infected cells showed a 59% reduction in V max for glutamate transport, indicating a reduction in the number of active transporter sites on the cell surface. Impaired glutamate transport after HIV-1 infection or gp120 exposure correlated with a 40-70% decline in steady-state levels of EAAT2 RNA and protein. EAAT1 RNA and protein levels were less affected. Treatment of astrocytes with tumor necrosis factor-α (TNF-α) decreased the expression of both EAAT1 and EAAT2, but neither HIV-1 nor gp120 were found to induce TNF-α production by astrocytes. These findings demonstrate that HIV-1 and gp120 induce transcriptional downmodulation of the EAAT2 transporter gene in human astrocytes and coordinately attenuate glutamate transport by the cells. Reduction of the ability of HIV-1-infected astrocytes to take up glutamate may contribute to the development of neurological disease

  17. 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...

  18. Limited energy supply in Müller cells alters glutamate uptake

    DEFF Research Database (Denmark)

    Toft-Kehler, Anne Katrine; Skytt, Dorte Marie; Poulsen, Kristian Arild

    2014-01-01

    evaluates if glucose-deprivation of Müller cells interferes with their ability to remove glutamate from the extracellular space. The human Müller glial cell line, Moorfields/Institute of Ophthalmology-Müller 1, was used to study changes in glutamate uptake. Excitatory amino acid transporter (EAAT) proteins...... were up-regulated in glucose-deprived Müller cells and glutamate uptake was significantly increased in the absence of glucose. The present findings revealed an up-regulation of EAAT1 and EAAT2 in glucose-deprived Müller cells as well as an increased ability to take up glutamate. Hence, glucose...... deprivation may result in an increased ability to protect RGCs from glutamate-induced excitotoxicity, whereas malfunction of glutamate uptake in Müller cells may contribute to retinal neurodegeneration....

  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. Development of a novel ultrasensitive enzyme immunoassay for human glutamic acid decarboxylase 65 antibody.

    Science.gov (United States)

    Numata, Satoshi; Katakami, Hideki; Inoue, Shinobu; Sawada, Hirotake; Hashida, Seiichi

    2016-07-01

    We developed a novel, ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for determination of glutamic acid decarboxylase autoantibody concentrations in serum samples from patients with type 2 diabetes. We developed an immune complex transfer enzyme immunoassay for glutamic acid decarboxylase autoantibody and measured glutamic acid decarboxylase autoantibody from 22 patients with type 1 diabetes, 29 patients with type 2 diabetes, and 32 healthy controls. A conventional ELISA kit identified 10 patients with type 1 diabetes and one patient with type 2 diabetes as glutamic acid decarboxylase autoantibody positive, whereas 15 patients with type 1 diabetes and six patients with type 2 diabetes were identified as glutamic acid decarboxylase autoantibody positive using immune complex transfer enzyme immunoassay. Immune complex transfer enzyme immunoassay is a highly sensitive and specific assay for glutamic acid decarboxylase autoantibody and might be clinically useful for diabetic onset prediction and early diagnosis. © The Author(s) 2016.

  1. The SLC1 high-affinity glutamate and neutral amino acid transporter family.

    Science.gov (United States)

    Kanai, Yoshikatsu; Clémençon, Benjamin; Simonin, Alexandre; Leuenberger, Michele; Lochner, Martin; Weisstanner, Martin; Hediger, Matthias A

    2013-01-01

    Glutamate transporters play important roles in the termination of excitatory neurotransmission and in providing cells throughout the body with glutamate for metabolic purposes. The high-affinity glutamate transporters EAAC1 (SLC1A1), GLT1 (SLC1A2), GLAST (SLC1A3), EAAT4 (SLC1A6), and EAAT5 (SLC1A7) mediate the cellular uptake of glutamate by the co-transport of three sodium ions (Na(+)) and one proton (H(+)), with the counter-transport of one potassium ion (K(+)). Thereby, they protect the CNS from glutamate-induced neurotoxicity. Loss of function of glutamate transporters has been implicated in the pathogenesis of several diseases, including amyotrophic lateral sclerosis and Alzheimer's disease. In addition, glutamate transporters play a role in glutamate excitotoxicity following an ischemic stroke, due to reversed glutamate transport. Besides glutamate transporters, the SLC1 family encompasses two transporters of neutral amino acids, ASCT1 (SLC1A4) and ASCT2 (SLC1A5). Both transporters facilitate electroneutral exchange of amino acids in neurons and/or cells of the peripheral tissues. Some years ago, a high resolution structure of an archaeal homologue of the SLC1 family was determined, followed by the elucidation of its structure in the presence of the substrate aspartate and the inhibitor d,l-threo-benzyloxy aspartate (d,l-TBOA). Historically, the first few known inhibitors of SLC1 transporters were based on constrained glutamate analogs which were active in the high micromolar range but often also showed off-target activity at glutamate receptors. Further development led to the discovery of l-threo-β-hydroxyaspartate derivatives, some of which effectively inhibited SLC1 transporters at nanomolar concentrations. More recently, small molecule inhibitors have been identified whose structures are not based on amino acids. Activators of SLC1 family members have also been discovered but there are only a few examples known. Copyright © 2013 Elsevier Ltd. All rights

  2. Effects of Bee Venom on Glutamate-Induced Toxicity in Neuronal and Glial Cells

    OpenAIRE

    Lee, Sang Min; Yang, Eun Jin; Choi, Sun-Mi; Kim, Seon Hwy; Baek, Myung Gi; Jiang, Jing Hua

    2012-01-01

    Bee venom (BV), which is extracted from honeybees, is used in traditional Korean medical therapy. Several groups have demonstrated the anti-inflammatory effects of BV in osteoarthritis both in vivo and in vitro. Glutamate is the predominant excitatory neurotransmitter in the central nervous system (CNS). Changes in glutamate release and uptake due to alterations in the activity of glutamate transporters have been reported in many neurodegenerative diseases, including Parkinson's disease, Alzh...

  3. 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...

  4. Glutamate and GABA uptake by cerebellar granule and glial cell enriched populations

    International Nuclear Information System (INIS)

    Campbell, G.L.; Shank, R.P.

    1978-01-01

    The results of a study on the uptake of glutamate and GABA by the granule and glial cell enriched populations are reported. They demonstrate that the granule cells vigorously accumulate glutamate but not GABA, whereas the glial cell enriched fraction takes up both amino acids quite rapidly. An unexpected and significant finding is that both cell populations take up glutamate by two distinct high-affinity transport systems as well as a low-affinity system. (Auth.)

  5. Poly-gamma-glutamic acid a substitute of salivary protein statherin

    International Nuclear Information System (INIS)

    Qamar, Z.; Rahim, Z.B.H.A.; Fatima, T.

    2016-01-01

    The modus operandi of salivary proteins in reducing the kinetics of enamel dissolution during simulated caries challenges is thought to be associated with interaction of glutamic acid residues with human teeth surfaces. Japanese traditional food stuff natto is rich with chain of repeating glutamic acid residues linked by gamma-peptide bond and hence, named poly-gamma-glutamic acid (PGGA). It is a naturally occurring polypeptide and may therefore perform similar caries inhibitory functions as statherin. (author)

  6. In Vivo Glutamate Measured with MR Spectroscopy: Behavioral Correlates in Aging

    OpenAIRE

    Zahr, Natalie M.; Mayer, Dirk; Rohlfing, Torsten; Chanraud, Sandra; Gu, Meng; Sullivan, Edith V.; Pfefferbaum, Adolf

    2012-01-01

    Altered availability of the brain biochemical glutamate may contribute to the neural mechanisms underlying age-related changes in cognitive and motor functions. To investigate the contribution of regional glutamate levels to behavior in the aging brain, we used an in vivo Magnetic Resonance Spectroscopy (MRS) protocol optimized for glutamate detection in 3 brain regions targeted by cortical glutamatergic efferents—striatum, cerebellum, and pons. Data from 61 healthy men and women ranging in a...

  7. Ceftriaxone modulates uptake activity of glial glutamate transporter-1 against global brain ischemia in rats.

    Science.gov (United States)

    Hu, Yu-Yan; Xu, Jing; Zhang, Min; Wang, Dan; Li, Li; Li, Wen-Bin

    2015-01-01

    Ceftriaxone(Cef) selectively increases the expression of glial glutamate transporter-1 (GLT-1), which was thought to be neuroprotective in some circumstances. However, the effect of Cef on glutamate uptake of GLT-1 was mostly assayed using in vitro studies such as primary neuron/astrocyte cultures or brain slices. In addition, the effect of Cef on neurons in different ischemic models was still discrepant. Therefore, this study was undertaken to observe the effect of Cef on neurons in global brain ischemia in rats, and especially to provide direct evidence of the up-regulation of GLT-1 uptake for glutamate contributing to the neuronal protection of Cef against brain ischemia. Neuropathological evaluation indicated that administration of Cef, especially pre-treatment protocols, significantly prevented delayed neuronal death in hippocampal CA1 subregion normally induced by global brain ischemia. Simultaneously, pre-administration of Cef significantly up-regulated the expression of GLT-1. Particularly, GLT-1 uptake assay with (3) H-glutamate in living cells from adult rats showed that up-regulation in glutamate uptake accompanied up-regulated GLT-1 expression. Inhibition of GLT-1 by antisense oligodeoxynucleotides or dihydrokainate significantly inhibited the Cef-induced up-regulation in GLT-1 uptake and the neuroprotective effect against global ischemia. Thus, we may conclude that Cef protects neurons against global brain ischemia via up-regulation of the expression and glutamate uptake of GLT-1. Glutamate uptake by glial glutamate transporter-1 (GLT-1) is the principal way to regulate extracellular glutamate homeostasis in central nervous system. Over-accumulation of glutamate results in excitotoxicity and injures neurons after cerebral ischemia. Ceftriaxone up-regulates GLT-1 expression and uptake of glutamate, diminishes the excitotoxicity of glutamate and then protects neurons against global brain ischemia. © 2014 International Society for Neurochemistry.

  8. Antioxidant effect of phycocyanin on oxidative stress induced with monosodium glutamate in rats

    OpenAIRE

    Bertolin, Telma Elita; Farias, Daniele; Guarienti, Cíntia; Petry, Fernanda Tais Souza; Colla, Luciane Maria; Costa, Jorge Alberto Vieira

    2011-01-01

    The objective of this work was to study the antioxidant effect of phycocyanin on the oxidative stress induced by monosodium glutamate in the rats. The tests were performed with 32 rats of Wistar breed, divided into four groups, which were administered saline solution of phycocyanin, monosodium glutamate and monosodium glutamate plus phycocyanin. Sulfhydryl groups and the secondary substances derived from lipid oxidation were determined through the level of TBA. The evaluation of these values ...

  9. Monosodium glutamate-induced oxidative kidney damage and possible mechanisms: a mini-review.

    Science.gov (United States)

    Sharma, Amod

    2015-10-22

    Animal studies suggest that chronic monosodium glutamate (MSG) intake induces kidney damage by oxidative stress. However, the underlying mechanisms are still unclear, despite the growing evidence and consensus that α-ketoglutarate dehydrogenase, glutamate receptors and cystine-glutamate antiporter play an important role in up-regulation of oxidative stress in MSG-induced renal toxicity. This review summaries evidence from studies into MSG-induced renal oxidative damage, possible mechanisms and their importance from a toxicological viewpoint.

  10. GABA and glutamate uptake and metabolism in retinal glial (Müller cells

    Directory of Open Access Journals (Sweden)

    Andreas eBringmann

    2013-04-01

    Full Text Available Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and -aminobutyric acid (GABA. Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the shaping and termination of the synaptic activity, particularly in the inner retina. Reactive Müller cells are neuroprotective, e.g., by the clearance of excess extracellular glutamate, but may also contribute to neuronal degeneration by a malfunctioning or even reversal of glial glutamate transporters, or by a downregulation of the key enzyme, glutamine synthetase. This review summarizes the present knowledge about the role of Müller cells in the clearance and metabolization of extracellular glutamate and GABA. Some major pathways of GABA and glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism.

  11. Glutamate and ATP at the Interface Between Signaling and Metabolism in Astroglia

    DEFF Research Database (Denmark)

    Parpura, Vladimir; Fisher, Elizabeth S; Lechleiter, James D

    2017-01-01

    Glutamate is the main excitatory transmitter in the brain, while ATP represents the most important energy currency in any living cell. Yet, these chemicals play an important role in both processes, enabling them with dual-acting functions in metabolic and intercellular signaling pathways. Glutamate...... can fuel ATP production, while ATP can act as a transmitter in intercellular signaling. We discuss the interface between glutamate and ATP in signaling and metabolism of astrocytes. Not only do glutamate and ATP cross each other's paths in physiology of the brain, but they also do so in its pathology...

  12. Glutamate metabolism is down-regulated in astrocytes during experimental allergic encephalomyelitis

    DEFF Research Database (Denmark)

    Hardin-Pouzet, H; Krakowski, M; Bourbonnière, L

    1997-01-01

    dehydrogenase (GDH) expression were dramatically reduced. These two astrocytic enzymes are responsible for degradation of glutamate, the most abundant excitatory neurotransmitter in the brain. Since elevated levels of glutamate may be neurotoxic, we propose that the decreased capacity of astrocytes...... in the spinal cord of mice, which had developed a complete paralysis of hind- and fore-limbs and tail (grade 4 EAE), thus establishing that reactive gliosis occurred under these experimental conditions. Within the same samples and using similar techniques, we found that glutamine synthetase (GS) and glutamate...... to metabolize glutamate may contribute to EAE pathology....

  13. Coupling of glutamate and glucose uptake in cultured Bergmann glial cells.

    Science.gov (United States)

    Mendez-Flores, Orquidia G; Hernández-Kelly, Luisa C; Suárez-Pozos, Edna; Najimi, Mustapha; Ortega, Arturo

    2016-09-01

    Glutamate, the main excitatory neurotransmitter in the vertebrate brain, exerts its actions through specific membrane receptors present in neurons and glial cells. Over-stimulation of glutamate receptors results in neuronal death, phenomena known as excitotoxicity. A family of sodium-dependent, glutamate uptake transporters mainly expressed in glial cells, removes the amino acid from the synaptic cleft preventing neuronal death. The sustained sodium influx associated to glutamate removal in glial cells, activates the sodium/potassium ATPase restoring the ionic balance, additionally, glutamate entrance activates glutamine synthetase, both events are energy demanding, therefore glia cells increase their ATP expenditure favouring glucose uptake, and triggering several signal transduction pathways linked to proper neuronal glutamate availability, via the glutamate/glutamine shuttle. To further characterize these complex transporters interactions, we used the well-established model system of cultured chick cerebellum Bergmann glia cells. A time and dose-dependent increase in the activity, plasma membrane localization and protein levels of glucose transporters was detected upon d-aspartate exposure. Interestingly, this increase is the result of a protein kinase C-dependent signaling cascade. Furthermore, a glutamate-dependent glucose and glutamate transporters co-immunoprecipitation was detected. These results favour the notion that glial cells are involved in glutamatergic neuronal physiology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Effective Mechanism for Synthesis of Neurotransmitter Glutamate and its Loading into Synaptic Vesicles.

    Science.gov (United States)

    Takeda, Kouji; Ueda, Tetsufumi

    2017-01-01

    Glutamate accumulation into synaptic vesicles is a pivotal step in glutamate transmission. This process is achieved by a vesicular glutamate transporter (VGLUT) coupled to v-type proton ATPase. Normal synaptic transmission, in particular during intensive neuronal firing, would demand rapid transmitter re-filling of emptied synaptic vesicles. We have previously shown that isolated synaptic vesicles are capable of synthesizing glutamate from α-ketoglutarate (not from glutamine) by vesicle-bound aspartate aminotransferase for immediate uptake, in addition to ATP required for uptake by vesicle-bound glycolytic enzymes. This suggests that local synthesis of these substances, essential for glutamate transmission, could occur at the synaptic vesicle. Here we provide evidence that synaptosomes (pinched-off nerve terminals) also accumulate α-ketoglutarate-derived glutamate into synaptic vesicles within, at the expense of ATP generated through glycolysis. Glutamine-derived glutamate is also accumulated into synaptic vesicles in synaptosomes. The underlying mechanism is discussed. It is suggested that local synthesis of both glutamate and ATP at the presynaptic synaptic vesicle would represent an efficient mechanism for swift glutamate loading into synaptic vesicles, supporting maintenance of normal synaptic transmission.

  15. Molecular basis for convergent evolution of glutamate recognition by pentameric ligand-gated ion channels

    DEFF Research Database (Denmark)

    Lynagh, Timothy; Beech, Robin N.; Lalande, Maryline J.

    2015-01-01

    that glutamate recognition requires an arginine residue in the base of the binding site, which originated at least three distinct times according to phylogenetic analysis. Most remarkably, the arginine emerged on the principal face of the binding site in the Lophotrochozoan lineage, but 65 amino acids upstream......Glutamate is an indispensable neurotransmitter, triggering postsynaptic signals upon recognition by postsynaptic receptors. We questioned the phylogenetic position and the molecular details of when and where glutamate recognition arose in the glutamate-gated chloride channels. Experiments revealed......, on the complementary face, in the Ecdysozoan lineage. This combined experimental and computational approach throws new light on the evolution of synaptic signalling....

  16. Peripheral nerve injury increases glutamate-evoked calcium mobilization in adult spinal cord neurons

    Directory of Open Access Journals (Sweden)

    Doolen Suzanne

    2012-07-01

    Full Text Available Abstract Background Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of peripheral neuropathic pain. Results Bath-applied glutamate robustly increased [Ca2+]i in 14.4 ± 2.6 cells per dorsal horn within a 440 x 330 um field-of-view, with an average time-to-peak of 27 s and decay of 112 s. Repeated application produced sequential responses of similar magnitude, indicating the absence of sensitization, desensitization or tachyphylaxis. Ca2+ transients were glutamate concentration-dependent with a Kd = 0.64 mM. Ca2+ responses predominantly occurred on neurons since: 1 Over 95% of glutamate-responsive cells did not label with the astrocyte marker, SR-101; 2 62% of fura-2 AM loaded cells exhibited spontaneous action potentials; 3 75% of cells that responded to locally-applied glutamate with a rise in [Ca2+]i also showed a significant increase in AP frequency upon a subsequent glutamate exposure; 4 In experiments using simultaneous on-cell recordings and Ca2+ imaging, glutamate elicited a Ca2+ response and an increase in AP frequency. AMPA/kainate (CNQX- and AMPA (GYKI 52466-selective receptor antagonists significantly attenuated glutamate-evoked increases in [Ca2+]i, while NMDA (AP-5, kainate (UBP-301 and class I mGluRs (AIDA did not. Compared to sham controls, peripheral nerve injury

  17. Peripheral nerve injury increases glutamate-evoked calcium mobilization in adult spinal cord neurons.

    Science.gov (United States)

    Doolen, Suzanne; Blake, Camille B; Smith, Bret N; Taylor, Bradley K

    2012-07-28

    Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of peripheral neuropathic pain. Bath-applied glutamate robustly increased [Ca2+]i in 14.4 ± 2.6 cells per dorsal horn within a 440 x 330 um field-of-view, with an average time-to-peak of 27 s and decay of 112 s. Repeated application produced sequential responses of similar magnitude, indicating the absence of sensitization, desensitization or tachyphylaxis. Ca2+ transients were glutamate concentration-dependent with a Kd = 0.64 mM. Ca2+ responses predominantly occurred on neurons since: 1) Over 95% of glutamate-responsive cells did not label with the astrocyte marker, SR-101; 2) 62% of fura-2 AM loaded cells exhibited spontaneous action potentials; 3) 75% of cells that responded to locally-applied glutamate with a rise in [Ca2+]i also showed a significant increase in AP frequency upon a subsequent glutamate exposure; 4) In experiments using simultaneous on-cell recordings and Ca2+ imaging, glutamate elicited a Ca2+ response and an increase in AP frequency. AMPA/kainate (CNQX)- and AMPA (GYKI 52466)-selective receptor antagonists significantly attenuated glutamate-evoked increases in [Ca2+]i, while NMDA (AP-5), kainate (UBP-301) and class I mGluRs (AIDA) did not. Compared to sham controls, peripheral nerve injury significantly decreased mechanical paw

  18. Interaction between the glutamate transporter GLT1b and the synaptic PDZ domain protein PICK1

    DEFF Research Database (Denmark)

    Bassan, Merav; Liu, Hongguang; Madsen, Kenneth L

    2008-01-01

    Synaptic plasticity is implemented by the interaction of glutamate receptors with PDZ domain proteins. Glutamate transporters provide the only known mechanism of clearance of glutamate from excitatory synapses, and GLT1 is the major glutamate transporter. We show here that GLT1 interacts...... expressing PICK1 and GLT1b. In addition, expression of GLT1b in COS7 cells changed the distribution of PICK1, bringing it to the surface. GLT1b and PICK1 co-localized with each other and with synaptic markers in hippocampal neurons in culture. Phorbol ester, an activator of protein kinase C (PKC), a known...

  19. Antioxidant effect of phycocyanin on oxidative stress induced with monosodium glutamate in rats

    Directory of Open Access Journals (Sweden)

    Telma Elita Bertolin

    2011-08-01

    Full Text Available The objective of this work was to study the antioxidant effect of phycocyanin on the oxidative stress induced by monosodium glutamate in the rats. The tests were performed with 32 rats of Wistar breed, divided into four groups, which were administered saline solution of phycocyanin, monosodium glutamate and monosodium glutamate plus phycocyanin. Sulfhydryl groups and the secondary substances derived from lipid oxidation were determined through the level of TBA. The evaluation of these values and the level of sulfhydryl showed that the administration of phycocyanin presented significant antioxidant effect (p < 0.05 reducing the oxidative stress induced by the monosodium glutamate in vivo.

  20. 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