Group I Metabotropic Glutamate Receptors

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

2015-01-01

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...

NMDA-induced potentiation of mGluR5 is mediated by activation of protein phosphatase 2B/calcineurin

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Alagarsamy, Sudar; Saugstad, Julie; Warren, Lee; Mansuy, Isabelle M.; Gereau, Robert W.; Conn, P. Jeffrey

2010-01-01

Previous reports have shown that activation of N-methyl-D-aspartate (NMDA) receptors potentiates responses to activation of the group I metabotropic glutamate receptor mGluR5 by reversing PKC-mediated desensitization of this receptor. NMDA-induced reversal of mGluR5 desensitization is dependent on activation of protein phosphatases. However, the specific protein phosphatase involved and the precise mechanism by which NMDA receptor activation reduces mGluR desensitization are not known. We have performed a series of molecular, biochemical, and genetic studies to show that NMDA-induced regulation of mGluR5 is dependent on activation of calcium-dependent protein phosphatase 2B/calcineurin (PP2B/CaN). Furthermore, we report that purified calcineurin directly dephosphorylates the C-terminal tail of mGluR5 at sites that are phosphorylated by PKC. Finally, immunoprecipitation and GST fusion protein pull-down experiments reveal that calcineurin interacts with mGluR5, suggesting that these proteins could be colocalized in a signaling complex. Taken together with previous studies, these data suggest that activation of NMDA receptors leads to activation of calcineurin and that calcineurin modulates mGluR5 function by directly dephosphorylating mGluR5 at PKC sites that are involved in desensitization of this receptor. 2005 Elsevier Ltd. All rights reserved. PMID:16005030

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

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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.

Fear extinction induces mGluR5-mediated synaptic and intrinsic plasticity in infralimbic neurons.

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Sepulveda-Orengo, Marian T; Lopez, Ana V; Soler-Cedeño, Omar; Porter, James T

2013-04-24

Studies suggest that plasticity in the infralimbic prefrontal cortex (IL) in rodents and its homolog in humans is necessary for inhibition of fear during the recall of fear extinction. The recall of extinction is impaired by locally blocking metabotropic glutamate receptor type 5 (mGluR5) activation in IL during extinction training. This finding suggests that mGluR5 stimulation may lead to IL plasticity needed for fear extinction. To test this hypothesis, we recorded AMPA and NMDA currents, AMPA receptor (AMPAR) rectification, and intrinsic excitability in IL pyramidal neurons in slices from trained rats using whole-cell patch-clamp recording. We observed that fear extinction increases the AMPA/NMDA ratio, consistent with insertion of AMPARs into IL synapses. In addition, extinction training increased inward rectification, suggesting that extinction induces the insertion of calcium-permeable (GluA2-lacking) AMPARs into IL synapses. Consistent with this, selectively blocking calcium-permeable AMPARs with Naspm reduced the AMPA EPSCs in IL neurons to a larger degree after extinction. Extinction-induced changes in AMPA/NMDA ratio, rectification, and intrinsic excitability were blocked with an mGluR5 antagonist. These findings suggest that mGluR5 activation leads to consolidation of fear extinction by regulating the intrinsic excitability of IL neurons and modifying the composition of AMPARs in IL synapses. Therefore, impaired mGluR5 activity in IL synapses could be one factor that causes inappropriate modulation of fear expression leading to anxiety disorders.

In Vitro Functional Characterization of GET73 as Possible Negative Allosteric Modulator of Metabotropic Glutamate Receptor 5.

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Beggiato, Sarah; Borelli, Andrea C; Tomasini, Maria C; Castelli, M Paola; Pintori, Nicholas; Cacciaglia, Roberto; Loche, Antonella; Ferraro, Luca

2018-01-01

The present study was aimed to further characterize the pharmacological profile of N-[4-(trifluoromethyl) benzyl]-4-methoxybutyramide (GET73), a putative negative allosteric modulator (NAM) of metabotropic glutamate subtype 5 receptor (mGluR5) under development as a novel medication for the treatment of alcohol dependence. This aim has been accomplished by means of a series of in vitro functional assays. These assays include the measure of several down-stream signaling [intracellular Ca ++ levels, inositol phosphate (IP) formation and CREB phosphorylation (pCREB)] which are generally affected by mGluR5 ligands. In particular, GET73 (0.1 nM-10 μM) was explored for its ability to displace the concentration-response curve of some mGluR5 agonists/probes (glutamate, L-quisqualate, CHPG) in different native preparations. GET73 produced a rightward shift of concentration-response curves of glutamate- and CHPG-induced intracellular Ca ++ levels in primary cultures of rat cortical astrocytes. The compound also induced a rightward shift of concentration response curve of glutamate- and L-quisqualate-induced increase in IP turnover in rat hippocampus slices, along with a reduction of CHPG (10 mM)-induced increase in IP formation. Moreover, GET73 produced a rightward shift of concentration-response curve of glutamate-, CHPG- and L-quisqualate-induced pCREB levels in rat cerebral cortex neurons. Although the engagement of other targets cannot be definitively ruled out, these data support the view that GET73 acts as an mGluR5 NAM and support the significance of further investigating the possible mechanism of action of the compound.

Gender-specific desensitization of group I metabotropic glutamate receptors after maternal l-glutamate intake during lactation.

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López-Zapata, Antonio; León-Navarro, David Agustín; Crespo, María; Martín, Mairena

2018-04-22

In the present work we have studied the effect of maternal intake of l-Glutamate (l-Glu) (1 g/L) during lactation on group I mGluR transduction pathway in brain plasma membrane from 15 days-old neonates. Results obtained have shown that maternal l-glutamate intake did not significantly affect neither weights of pups nor negative geotaxis reflex, an index of neurobehavioral development, but increased l-Glu plasma level in both male and female neonates. In male neonates, maternal l-Glu intake evoked a loss of mGluR 1 whereas no variation on mGluR 5 was observed as revealed by Western-blotting assay. The loss of mGlu 1 R was accompanied by a decrease on l-Glu-stimulated phospholipase C activity suggesting, therefore, a loss of group I mGluR functionality. Concerning female neonates, no variations were detected neither mGluR 1 nor mGluR 5 and group I mGluR functionality was also preserved. Copyright © 2018 ISDN. Published by Elsevier Ltd. All rights reserved.

mGluR5 Positive Allosteric Modulation Enhances Extinction Learning Following Cocaine Self-Administration

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Cleva, Richard M.; Hicks, Megan P.; Gass, Justin T.; Wischerath, Kelly C.; Plasters, Elizabeth T.; Widholm, John J.; Olive, M. Foster

2011-01-01

Extinction of classically and instrumentally conditioned behaviors, such as conditioned fear and drug-seeking behavior, is a process of active learning, and recent studies indicate that potentiation of glutamatergic transmission facilitates extinction learning. In this study we investigated the effects of the type 5 metabotropic glutamate receptors (mGluR5) positive allosteric modulator 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) on the extinction of cocaine-seeking behavior in ...

Inhibition of spontaneous recovery of fear by mGluR5 after prolonged extinction training.

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Sheng-Chun Mao

Full Text Available Fear behavior is vital for survival and involves learning contingent associations of non-threatening cues with aversive stimuli. In contrast, excessive levels of fear can be maladaptive and lead to anxiety disorders. Generally, extensive sessions of extinction training correlates with reduced spontaneous recovery. The molecular mechanisms underlying the long-term inhibition of fear recovery following repeated extinction training are not fully understood. Here we show that in rats, prolonged extinction training causes greater reduction in both fear-potentiated startle and spontaneous recovery. This effect was specifically blocked by metabotropic glutamate receptor 5 (mGluR5, but not by mGluR1 antagonists and by a protein synthesis inhibitor. Similar inhibition of memory recovery following prolonged extinction training was also observed in mice. In agreement with the instrumental role of mGluR5 in the prolonged inhibition of fear recovery, we found that FMR1-/- mice which exhibit enhanced mGluR5-mediated signaling exhibit lower spontaneous recovery of fear after extinction training than wild-type littermates. At the molecular level, we discovered that prolonged extinction training reversed the fear conditioning-induced increase in surface expression of GluR1, AMPA/NMDA ratio, postsynaptic density-95 (PSD-95 and synapse-associated protein-97 (SAP97. Accordingly, delivery of Tat-GluR2(3Y, a synthetic peptide that blocks AMPA receptor endocytosis, inhibited prolonged extinction training-induced inhibition of fear recovery. Together, our results demonstrate that prolonged extinction training results in the mGluR5-dependent long-term inhibition of fear recovery. This effect may involve the degradation of original memory and may explain the beneficial effects of prolonged exposure therapy for the treatment of phobias.

Inhibition of spontaneous recovery of fear by mGluR5 after prolonged extinction training.

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Mao, Sheng-Chun; Chang, Chih-Hua; Wu, Chia-Chen; Orejarena, M Juliana; Orejanera, Maria Juliana; Manzoni, Olivier J; Gean, Po-Wu

2013-01-01

Fear behavior is vital for survival and involves learning contingent associations of non-threatening cues with aversive stimuli. In contrast, excessive levels of fear can be maladaptive and lead to anxiety disorders. Generally, extensive sessions of extinction training correlates with reduced spontaneous recovery. The molecular mechanisms underlying the long-term inhibition of fear recovery following repeated extinction training are not fully understood. Here we show that in rats, prolonged extinction training causes greater reduction in both fear-potentiated startle and spontaneous recovery. This effect was specifically blocked by metabotropic glutamate receptor 5 (mGluR5), but not by mGluR1 antagonists and by a protein synthesis inhibitor. Similar inhibition of memory recovery following prolonged extinction training was also observed in mice. In agreement with the instrumental role of mGluR5 in the prolonged inhibition of fear recovery, we found that FMR1-/- mice which exhibit enhanced mGluR5-mediated signaling exhibit lower spontaneous recovery of fear after extinction training than wild-type littermates. At the molecular level, we discovered that prolonged extinction training reversed the fear conditioning-induced increase in surface expression of GluR1, AMPA/NMDA ratio, postsynaptic density-95 (PSD-95) and synapse-associated protein-97 (SAP97). Accordingly, delivery of Tat-GluR2(3Y), a synthetic peptide that blocks AMPA receptor endocytosis, inhibited prolonged extinction training-induced inhibition of fear recovery. Together, our results demonstrate that prolonged extinction training results in the mGluR5-dependent long-term inhibition of fear recovery. This effect may involve the degradation of original memory and may explain the beneficial effects of prolonged exposure therapy for the treatment of phobias.

Comprehensive behavioral study of mGluR3 knockout mice: implication in schizophrenia related endophenotypes

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2014-01-01

Background We previously performed systematic association studies of glutamate receptor gene family members with schizophrenia, and found positive associations of polymorphisms in the GRM3 (a gene of metabotropic glutamate receptor 3: mGluR3) with the disorder. Physiological roles of GRM3 in brain functions and its functional roles in the pathogenesis of schizophrenia remain to be resolved. Results We generated mGluR3 knockout (KO) mice and conducted comprehensive behavioral analyses. KO mice showed hyperactivity in the open field, light/dark transition, and 24-hour home cage monitoring tests, impaired reference memory for stressful events in the Porsolt forced swim test, impaired contextual memory in cued and contextual fear conditioning test, and impaired working memory in the T-Maze forced alternation task test. Hyperactivity and impaired working memory are known as endophenotypes of schizophrenia. We examined long-term synaptic plasticity by assessing long-term potentiation (LTP) in the CA1 region in the hippocampi of KO and wild-type (WT) mice. We observed no differences in the amplitude of LTP between the two genotypes, suggesting that mGluR3 is not essential for LTP in the CA1 region of the mouse hippocampus. As hyperactivity is typically associated with increased dopaminergic transmission, we performed in vivo microdialysis measurements of extracellular dopamine in the nucleus accumbens of KO and WT mice. We observed enhancements in the methamphetamine (MAP)-induced release of dopamine in KO mice. Conclusions These results demonstrate that a disturbance in the glutamate-dopamine interaction may be involved in the pathophysiology of schizophrenia-like behavior, such as hyperactivity in mGluR3 KO mice. PMID:24758191

Alterations in mGluR5 expression and signaling in Lewy body disease and in transgenic models of alpha-synucleinopathy--implications for excitotoxicity.

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Diana L Price

2010-11-01

Full Text Available Dementia with Lewy bodies (DLB and Parkinson's Disease (PD are neurodegenerative disorders of the aging population characterized by the abnormal accumulation of alpha-synuclein (alpha-syn. Previous studies have suggested that excitotoxicity may contribute to neurodegeneration in these disorders, however the underlying mechanisms and their relationship to alpha-syn remain unclear. For this study we proposed that accumulation of alpha-syn might result in alterations in metabotropic glutamate receptors (mGluR, particularly mGluR5 which has been linked to deficits in murine models of PD. In this context, levels of mGluR5 were analyzed in the brains of PD and DLB human cases and alpha-syn transgenic (tg mice and compared to age-matched, unimpaired controls, we report a 40% increase in the levels of mGluR5 and beta-arrestin immunoreactivity in the frontal cortex, hippocampus and putamen in DLB cases and in the putamen in PD cases. In the hippocampus, mGluR5 was more abundant in the CA3 region and co-localized with alpha-syn aggregates. Similarly, in the hippocampus and basal ganglia of alpha-syn tg mice, levels of mGluR5 were increased and mGluR5 and alpha-syn were co-localized and co-immunoprecipitated, suggesting that alpha-syn interferes with mGluR5 trafficking. The increased levels of mGluR5 were accompanied by a concomitant increase in the activation of downstream signaling components including ERK, Elk-1 and CREB. Consistent with the increased accumulation of alpha-syn and alterations in mGluR5 in cognitive- and motor-associated brain regions, these mice displayed impaired performance in the water maze and pole test, these behavioral alterations were reversed with the mGluR5 antagonist, MPEP. Taken together the results from study suggest that mGluR5 may directly interact with alpha-syn resulting in its over activation and that this over activation may contribute to excitotoxic cell death in select neuronal regions. These results highlight the

Metabotropic glutamate receptor 2 and corticotrophin-releasing factor receptor-1 gene expression is differently regulated by BDNF in rat primary cortical neurons

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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...... are particularly interested in the regulation of the 5-hydroxytryptamine receptor 2A (5-HT2A R). This receptor form a functional complex with the metabotropic glutamate receptor 2 (mGluR2) and is recruited to the cell membrane by the corticotrophin-releasing factor receptor 1 (CRF-R1). The effect of BDNF on gene...... expression for all these receptors, as well as a number of immediate-early genes, was pharmacologically characterized in primary neurons from rat frontal cortex. BDNF increased CRF-R1 mRNA levels up to fivefold, whereas mGluR2 mRNA levels were proportionally downregulated. No effect on 5-HT2A R mRNA was seen...

Pharmacological modulation of metabotropic glutamate receptor subtype 5 and 7 impairs extinction of social fear in a time-point-dependent manner.

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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.

Loss of dysbindin-1, a risk gene for schizophrenia, leads to impaired group 1 metabotropic glutamate receptor function in mice.

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Sanjeev K Bhardwaj

2015-03-01

Full Text Available The expression of dysbindin-1, a protein coded by the risk gene dtnbp1, is reduced in the brains of schizophrenia patients. Evidence indicates a role of dysbindin-1 in dopaminergic and glutamatergic transmission. Glutamatergic transmission and plasticity at excitatory synapses is critically regulated by G-protein coupled metabotropic glutamate receptor (mGluR family members, that have been implicated in schizophrenia. Here, we report a role of dysbindin-1 in hippocampal group 1 mGluR (mGluRI function in mice. In hippocampal synaptoneurosomal preparations from sandy (sdy mice, that have a loss of function mutation in dysbindin-1 gene, we observed a striking reduction in mGluRI agonist [(S-3,5-dihydroxyphenylglycine] (DHPG-induced phosphorylation of extracellular signal regulated kinase 1/2 (ERK1/2. This mGluR-ERK1/2 deficit occurred in the absence of significant changes in protein levels of the two members of the mGluRI family (i.e., mGluR1 and mGluR5 or in another mGluRI signaling pathway, i.e., protein kinase C (PKC. Aberrant mGluRI-ERK1/2 signaling affected hippocampal synaptic plasticity in the sdy mutants as DHPG-induced long-term depression (LTD at CA1 excitatory synapses was significantly reduced. Behavioral data suggest that the mGluRI hypofunction may underlie some of the cognitive abnormalities described in sdy mice as the administration of CDPPB (3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl benzamide, a positive allosteric modulator of mGluR5, rescued short-term object recognition and spatial learning and memory deficits in these mice. Taken together, our data suggest a novel role of dysbindin-1 in regulating mGluRI functions.

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

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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.

NAAG Peptidase Inhibitors Act via mGluR3: Animal Models of Memory, Alzheimer's, and Ethanol Intoxication.

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Olszewski, Rafal T; Janczura, Karolina J; Bzdega, Tomasz; Der, Elise K; Venzor, Faustino; O'Rourke, Brennen; Hark, Timothy J; Craddock, Kirsten E; Balasubramanian, Shankar; Moussa, Charbel; Neale, Joseph H

2017-09-01

Glutamate carboxypeptidase II (GCPII) inactivates the peptide neurotransmitter N-acetylaspartylglutamate (NAAG) following synaptic release. Inhibitors of GCPII increase extracellular NAAG levels and are efficacious in animal models of clinical disorders via NAAG activation of a group II metabotropic glutamate receptor. mGluR2 and mGluR3 knock-out (ko) mice were used to test the hypothesis that mGluR3 mediates the activity of GCPII inhibitors ZJ43 and 2-PMPA in animal models of memory and memory loss. Short- (1.5 h) and long- (24 h) term novel object recognition tests were used to assess memory. Treatment with ZJ43 or 2-PMPA prior to acquisition trials increased long-term memory in mGluR2, but not mGluR3, ko mice. Nine month-old triple transgenic Alzheimer's disease model mice exhibited impaired short-term novel object recognition memory that was rescued by treatment with a NAAG peptidase inhibitor. NAAG peptidase inhibitors and the group II mGluR agonist, LY354740, reversed the short-term memory deficit induced by acute ethanol administration in wild type mice. 2-PMPA also moderated the effect of ethanol on short-term memory in mGluR2 ko mice but failed to do so in mGluR3 ko mice. LY354740 and ZJ43 blocked ethanol-induced motor activation. Both GCPII inhibitors and LY354740 also significantly moderated the loss of motor coordination induced by 2.1 g/kg ethanol treatment. These data support the conclusion that inhibitors of glutamate carboxypeptidase II are efficacious in object recognition models of normal memory and memory deficits via an mGluR3 mediated process, actions that could have widespread clinical applications.

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

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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.

Different metabotropic glutamate receptors play opposite roles in synaptic plasticity of the rat medial vestibular nuclei.

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Grassi, Silvarosa; Frondaroli, Adele; Pettorossi, Vito Enrico

2002-09-15

In the medial vestibular nuclei (MVN) of rat brainstem slices, the role of group II and III metabotropic glutamate receptors (mGluRs) and of the subtypes of group I mGluRs: mGluR1, mGluR5, was investigated in basal synaptic transmission and in the induction and maintenance of long-term potentiation (LTP). We used selective antagonists and agonists for mGluRs and we analysed the field potentials evoked by vestibular afferent stimulation before and after high-frequency stimulation (HFS) to induce LTP. The group II and III mGluR antagonist, (R,S)-alpha-2-methyl-4sulphonophenylglycine (MSPG), induced LTP per se and caused a reduction of the paired-pulse facilitation (PPF) ratio indicating an enhancement of glutamate release. This suggests that group II and III mGluRs are activated under basal conditions to limit glutamate release. Both the group II and III mGluR selective antagonists, 2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3-(xanth-9-yl)propanoate (LY341495) and (R,S)-alpha-methylserine-O-phosphate (MSOP), induced LTP, and the selective agonists, (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate (APDC) and L(+)-2-amino-4-phosphonobutyric acid (L-AP4) depressed the field potentials and prevented HFS-LTP, with a prevailing contribution of group II mGluRs over that of group III mGluRs. The mGluR1 antagonist, 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) prevented the full development and maintenance of HFS-LTP. By contrast, the mGluR5 antagonist, 2-methyl-6-phenylethynylpyridine (MPEP) induced LTP per se, which was impeded by CPCCOEt, and it had no effect on LTP once induced by HFS. The PPF analysis showed an enhancement of glutamate release during MPEP potentiation. The group I mGluR agonist, (R,S)-3,5-dihydroxyphenylglycine (DHPG) induced LTP per se, which was blocked by CPCCOEt. By contrast the mGluR5 agonist, (R,S)-2-chloro-5-hydroxypheylglycine (CHPG) prevented LTP elicited by HFS and DHPG as well. In conclusion vestibular LTP is

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

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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.

Pharmacological modulation of mGluR7 with AMN082 and MMPIP exerts specific influences on alcohol consumption and preference in rats.

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Bahi, Amine; Fizia, Katharina; Dietz, Monika; Gasparini, Fabrizio; Flor, Peter J

2012-03-01

Growing evidence supports a role for the central nervous system (CNS) neurotransmitter L-glutamate and its metabotropic receptors (mGluRs) in drug addiction in general and alcohol-use disorders in particular. Alcohol dependence, for instance, has a genetic component, and the recent discovery that variations in the gene coding for mGluR7 modulate alcohol consumption further validates involvement of the L-glutamate system. Consequently, increasing interest emerges in developing L-glutamatergic therapies for the treatment of alcohol abuse and dependence. To this end, we performed a detailed behavioral pharmacology study to investigate the regulation of alcohol consumption and preference following administration of the mGluR7-selective drugs N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082) and 6-(4-Methoxyphenyl)-5-methyl-3-(4-pyridinyl)-isoxazolo[4,5-c]pyridin-4(5H)-one hydrochloride (MMPIP). Upon administration of the allosteric agonist AMN082 (10 mg/kg, i.p.) in rats, there was a significant decrease in ethanol consumption and preference, without affecting ethanol blood metabolism. In contrast, mGluR7 blockade with MMPIP (10 mg/kg, i.p.) showed an increase in alcohol intake and reversed AMN082's effect on ethanol consumption and preference. Both mGluR7-directed pharmacological tools had no effect on total fluid intake, taste preference, or on spontaneous locomotor activity. In conclusion, these findings support a specific regulatory role for mGluR7 on alcohol drinking and preference and provide evidence for the use of AMN082-type drugs as potential new treatments for alcohol-use disorders in man. © 2011 The Authors, Addiction Biology © 2011 Society for the Study of Addiction.

Activation of mGluR5 induces spike afterdepolarization and enhanced excitability in medium spiny neurons of the nucleus accumbens by modulating persistent Na+ currents

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D’Ascenzo, Marcello; Podda, Maria Vittoria; Fellin, Tommaso; Azzena, Gian Battista; Haydon, Philip; Grassi, Claudio

2009-01-01

The involvement of metabotropic glutamate receptors type 5 (mGluR5) in drug-induced behaviours is well-established but limited information is available on their functional roles in addiction-relevant brain areas like the nucleus accumbens (NAc). This study demonstrates that pharmacological and synaptic activation of mGluR5 increases the spike discharge of medium spiny neurons (MSNs) in the NAc. This effect was associated with the appearance of a slow afterdepolarization (ADP) which, in voltage-clamp experiments, was recorded as a slowly inactivating inward current. Pharmacological studies showed that ADP was elicited by mGluR5 stimulation via G-protein-dependent activation of phospholipase C and elevation of intracellular Ca2+ levels. Both ADP and spike aftercurrents were significantly inhibited by the Na+ channel-blocker, tetrodotoxin (TTX). Moreover, the selective blockade of persistent Na+ currents (INaP), achieved by NAc slice pre-incubation with 20 nm TTX or 10 μm riluzole, significantly reduced the ADP amplitude, indicating that this type of Na+ current is responsible for the mGluR5-dependent ADP. mGluR5 activation also produced significant increases in INaP, and the pharmacological blockade of this current prevented the mGluR5-induced enhancement of spike discharge. Collectively, these data suggest that mGluR5 activation upregulates INaP in MSNs of the NAc, thereby inducing an ADP that results in enhanced MSN excitability. Activation of mGluR5 will significantly alter spike firing in MSNs in vivo, and this effect could be an important mechanism by which these receptors mediate certain aspects of drug-induced behaviours. PMID:19433572

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

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Ying-Yu Huang

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

Positive allosteric modulation of mGluR5 accelerates extinction learning but not relearning following methamphetamine self-administration

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Peter R Kufahl

2012-11-01

Full Text Available Recent studies have implicated glutamate neurotransmission as an important substrate for the extinction of conditioned behaviors, including responding for drug reinforcement. Positive allosteric modulation of the type-5 metabotropic glutamate receptor (mGluR5 in particular has emerged as a treatment strategy for the enhancement of extinction of drug-motivated behaviors. Here, we investigated the effects of the mGluR5 positive allosteric modulator CDPPB, a compound known for its cognitive enhancing effects in rodents, on extinction learning in rats with different histories of methamphetamine (METH training. Rats were trained to self-administer METH under two conditions: 16 daily sessions of short access (90 min/day, ShA, or 8 daily sessions of short access followed by 8 sessions of long access (6 hr/day, LgA. Control rats self-administered sucrose pellets in daily 30 min sessions. Next, rats were administered vehicle or 30 mg/kg CDPPB prior to 7 consecutive daily extinction sessions, subjected to additional extinction sessions to re-establish a post-treatment baseline, and then tested for reinstatement of behavior in the presence of METH- or sucrose-paired cues. Rats were then subjected to a second series of extinction sessions, preceded by vehicle or 30 mg/kg CDPPB, and an additional test for cue-triggered reinstatement. CDPPB treatment resulted in a more rapid extinction of responding on the active lever, especially in the early sessions of the first extinction sequence. However, treatment effects were minimal during subsequent cue reinstatement tests and nonexistent during the second series of extinction sessions. Rats with histories of ShA, LgA and sucrose training expressed similar behavioral sensitivities to CDPPB, with LgA rats demonstrating a modestly higher treatment effect. Positive allosteric modulation of mGluR5 may therefore have some beneficial effects on efforts to facilitate extinction learning and reduce methamphetamine seeking.

mGluR5-antagonist mediated reversal of elevated stereotyped, repetitive behaviors in the VPA model of autism.

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Mili V Mehta

Full Text Available Autism spectrum disorders (ASD are highly disabling developmental disorders with a population prevalence of 1-3%. Despite a strong genetic etiology, there are no current therapeutic options that target the core symptoms of ASD. Emerging evidence suggests that dysfunction of glutamatergic signaling, in particular through metabotropic glutamate receptor 5 (mGluR5 receptors, may contribute to phenotypic deficits and may be appropriate targets for pharmacologic intervention. This study assessed the therapeutic potential of 2-methyl-6-phenylethyl-pyrididine (MPEP, an mGluR5-receptor antagonist, on repetitive and anxiety-like behaviors in the valproic acid (VPA mouse model of autism. Mice were exposed prenatally on day E13 to VPA and assessed for repetitive self-grooming and marble burying behaviors as adults. Anxiety-like behavior and locomotor activity were measured in an open-field. VPA-exposed mice displayed increased repetitive and anxiety-like behaviors, consistent with previously published results. Across both marble burying and self-grooming assays, MPEP significantly reduced repetitive behaviors in VPA-treated mice, but had no effect on locomotor activity. These results are consistent with emerging preclinical literature that mGluR5-antagonists may have therapeutic efficacy for core symptoms of autism.

Neurodevelopmental Expression Profile of Dimeric and Monomeric Group 1 mGluRs: Relevance to Schizophrenia Pathogenesis and Treatment.

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Lum, Jeremy S; Fernandez, Francesca; Matosin, Natalie; Andrews, Jessica L; Huang, Xu-Feng; Ooi, Lezanne; Newell, Kelly A

2016-10-10

Group 1 metabotropic glutamate receptors (mGluR1/mGluR5) play an integral role in neurodevelopment and are implicated in psychiatric disorders, such as schizophrenia. mGluR1 and mGluR5 are expressed as homodimers, which is important for their functionality and pharmacology. We examined the protein expression of dimeric and monomeric mGluR1α and mGluR5 in the prefrontal cortex (PFC) and hippocampus throughout development (juvenile/adolescence/adulthood) and in the perinatal phencyclidine (PCP) model of schizophrenia. Under control conditions, mGluR1α dimer expression increased between juvenile and adolescence (209-328%), while monomeric levels remained consistent. Dimeric mGluR5 was steadily expressed across all time points; monomeric mGluR5 was present in juveniles, dramatically declining at adolescence and adulthood (-97-99%). The mGluR regulators, Homer 1b/c and Norbin, significantly increased with age in the PFC and hippocampus. Perinatal PCP treatment significantly increased juvenile dimeric mGluR5 levels in the PFC and hippocampus (37-50%) but decreased hippocampal mGluR1α (-50-56%). Perinatal PCP treatment also reduced mGluR1α dimer levels in the PFC at adulthood (-31%). These results suggest that Group 1 mGluRs have distinct dimeric and monomeric neurodevelopmental patterns, which may impact their pharmacological profiles at specific ages. Perinatal PCP treatment disrupted the early expression of Group 1 mGluRs which may underlie neurodevelopmental alterations observed in this model.

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

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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

Localization of mGluR5, GABAB, GABAA, and cannabinoid receptors on the vago-vagal reflex pathway responsible for transient lower esophageal sphincter relaxation in humans: an immunohistochemical study

NARCIS (Netherlands)

Rohof, W. O.; Aronica, E.; Beaumont, H.; Troost, D.; Boeckxstaens, G. E.

2012-01-01

Background Transient lower esophageal sphincter relaxations (TLESRs) are the predominant mechanisms underlying gastro-esophageal reflux. TLESRs are mediated by a vago-vagal reflex, which can be blocked by interaction with metabotropic Glutamate Receptor 5 (mGluR5), ?-aminobutyric acid type B

Reduced juvenile long-term depression in tuberous sclerosis complex is mitigated in adults by compensatory recruitment of mGluR5 and Erk signaling.

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Wyatt B Potter

Full Text Available Tuberous sclerosis complex (TSC is a multisystem genetic disease that manifests with mental retardation, tumor formation, autism, and epilepsy. Heightened signaling through the mammalian target of rapamycin (mTOR pathway is involved in TSC pathology, however it remains unclear how other signaling pathways are perturbed and contribute to disease symptoms. Reduced long-term depression (LTD was recently reported in TSC mutant mice. We find that although reduced LTD is a feature of the juvenile mutant hippocampus, heightened expression of metabotropic glutamate receptor 5 and constitutively activated Erk signaling in the adult hippocampus drives wild-type levels of LTD. Increased mGluR5 and Erk results in a novel mTOR-independent LTD in CA1 hippocampus of adult mice, and contributes to the development of epileptiform bursting activity in the TSC2(+/- CA3 region of the hippocampus. Inhibition of mGluR5 or Erk signaling restores appropriate mTOR-dependence to LTD, and significantly reduces epileptiform bursting in TSC2(+/- hippocampal slices. We also report that adult TSC2(+/- mice exhibit a subtle perseverative behavioral phenotype that is eliminated by mGluR5 antagonism. These findings highlight the potential of modulating the mGluR5-Erk pathway in a developmental stage-specific manner to treat TSC.

Preparation of the metabotropic glutamate receptor 5 (mGluR5) PET tracer [18F]FPEB for human use: An automated radiosynthesis and a novel one-pot synthesis of its radiolabeling precursor

International Nuclear Information System (INIS)

Lim, Keunpoong; Labaree, David; Li, Songye; Huang, Yiyun

2014-01-01

The radiotracer 3-[ 18 F]fluoro-5-(2-pyridinylethynyl)benzonitrile, or [ 18 F]FPEB, is a promising PET imaging agent for the metabotropic glutamate subtype 5 receptor (mGluR5). In an effort to develop a routine production method of this radiotracer for use in clinical research we adapted its radiosynthesis to an automated chemistry module. In the meanwhile, we also developed a simplified “one-pot” method for the preparation of the nitrobenzonitrile radiolabeling precursor for [ 18 F]FPEB and its reference standard to replace the existing multi-step synthetic approach. - Highlights: • Radiosynthesis of [ 18 F]FPEB was performed in a Tracerlab FX-FN automated module. • The radiolabeling precursor was prepared from a “one-pot” Suzuki coupling method. • Total synthesis time from EOB to a final injectable dose was about 90 min. • The procedure was applied in the routine preparation of [ 18 F]FPEB for human use

Cyclic ADP ribose-dependent Ca2+ release by group I metabotropic glutamate receptors in acutely dissociated rat hippocampal neurons.

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Jong-Woo Sohn

Full Text Available Group I metabotropic glutamate receptors (group I mGluRs; mGluR1 and mGluR5 exert diverse effects on neuronal and synaptic functions, many of which are regulated by intracellular Ca(2+. In this study, we characterized the cellular mechanisms underlying Ca(2+ mobilization induced by (RS-3,5-dihydroxyphenylglycine (DHPG; a specific group I mGluR agonist in the somata of acutely dissociated rat hippocampal neurons using microfluorometry. We found that DHPG activates mGluR5 to mobilize intracellular Ca(2+ from ryanodine-sensitive stores via cyclic adenosine diphosphate ribose (cADPR, while the PLC/IP(3 signaling pathway was not involved in Ca(2+ mobilization. The application of glutamate, which depolarized the membrane potential by 28.5±4.9 mV (n = 4, led to transient Ca(2+ mobilization by mGluR5 and Ca(2+ influx through L-type Ca(2+ channels. We found no evidence that mGluR5-mediated Ca(2+ release and Ca(2+ influx through L-type Ca(2+ channels interact to generate supralinear Ca(2+ transients. Our study provides novel insights into the mechanisms of intracellular Ca(2+ mobilization by mGluR5 in the somata of hippocampal neurons.

Role of spinal metabotropic glutamate receptor 5 in pudendal inhibition of the nociceptive bladder reflex in cats.

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Reese, Jeremy N; Rogers, Marc J; Xiao, Zhiying; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-04-15

This study examined the role of spinal metabotropic glutamate receptor 5 (mGluR5) in the nociceptive C-fiber afferent-mediated spinal bladder reflex and in the inhibtion of this reflex by pudendal nerve stimulation (PNS). In α-chloralose-anesthetized cats after spinal cord transection at the T9/T10 level, intravesical infusion of 0.25% acetic acid irritated the bladder, activated nociceptive C-fiber afferents, and induced spinal reflex bladder contractions of low amplitude (reflexes were responsible for a major component of the contractions. This study shows that spinal mGluR5 plays an important role in the nociceptive C-fiber afferent-mediated spinal bladder reflex and in pudendal inhibition of this spinal reflex. Copyright © 2015 the American Physiological Society.

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

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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.

Glutamate: Tastant and Neuromodulator in Taste Buds.

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Vandenbeuch, Aurelie; Kinnamon, Sue C

2016-07-01

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

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

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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.

Effects of the mGluR2/3 agonist LY379268 on ketamine-evoked behaviours and neurochemical changes in the dentate gyrus of the rat

NARCIS (Netherlands)

Imre, Gabor; Salomons, Amber; Jongsma, Minke; Fokkema, Dirk S.; Den Boer, Johan A.; Ter Horst, Gert J.

One of the functions of group 11 metabotropic glutamate receptors (mGluR2/3) is to modulate glutamate release. Thus, targeting mGluR2/3s might be a novel treatment for several psychiatric disorders associated with inappropriate glutamatergic neurotransmission, such as schizophrenia. In an effort to

Altered expression patterns of group I and II metabotropic glutamate receptors in multiple sclerosis

NARCIS (Netherlands)

Geurts, J. J. G.; Wolswijk, G.; Bö, L.; van der Valk, P.; Polman, C. H.; Troost, D.; Aronica, E.

2003-01-01

Recent evidence supports a role for glutamate receptors in the pathophysiology of multiple sclerosis. In the present study, we have focused specifically on the expression of metabotropic glutamate receptors (mGluRs) in multiple sclerosis brain tissue. The expression of group I (mGluR1alpha and

Methoxyphenylethynyl, methoxypyridylethynyl and phenylethynyl derivatives of pyridine: synthesis, radiolabeling and evaluation of new PET ligands for metabotropic glutamate subtype 5 receptors

International Nuclear Information System (INIS)

Yu Meixiang; Tueckmantel, Werner; Wang, Xukui; Zhu Aijun; Kozikowski, Alan P.; Brownell, Anna-Liisa

2005-01-01

We have synthesized three different PET ligands to investigate the physiological function of metabotropic glutamate subtype 5 receptors (mGluR5) in vivo: 2-[ 11 C]methyl-6-(2-phenylethynyl)pyridine ([ 11 C]MPEP), 2-(2-(3-[ 11 C]methoxyphenyl)ethynyl)pyridine ([ 11 C]M-MPEP) and 2-(2-(5-[ 11 C]methoxypyridin-3-yl)ethynyl)pyridine ([ 11 C]M-PEPy). [ 11 C]Methyl iodide was used to label the compounds under basic conditions, and a Pd(0) catalyst was applied to label [ 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 [ 11 C]MPEP, [ 11 C]M-MPEP and [ 11 C]M-PEPy, a specific radioactivity of 700-1200 mCi/μmol 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 [ 11 C]MPEP binding, a 59.7% decrease in [ 11 C]M-MPEP binding and an 84.6% decrease in [ 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

Neuroprotective effects of metabotropic glutamate receptor group II and III activators against MPP(+)-induced cell death in human neuroblastoma SH-SY5Y cells: the impact of cell differentiation state.

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Jantas, D; Greda, A; Golda, S; Korostynski, M; Grygier, B; Roman, A; Pilc, A; Lason, W

2014-08-01

Recent studies have documented that metabotropic glutamate receptors from group II and III (mGluR II/III) are a potential target in the symptomatic treatment of Parkinson's disease (PD), however, the neuroprotective effects of particular mGluR II/III subtypes in relation to PD pathology are recognized only partially. In the present study, we investigated the effect of various mGluR II/III activators in the in vitro model of PD using human neuroblastoma SH-SY5Y cell line and mitochondrial neurotoxin MPP(+). We demonstrated that all tested mGluR ligands: mGluR II agonist - LY354740, mGluR III agonist - ACPT-I, mGluR4 PAM - VU0361737, mGluR8 agonist - (S)-3,4-DCPG, mGluR8 PAM - AZ12216052 and mGluR7 allosteric agonist - AMN082 were protective against MPP(+)-evoked cell damage in undifferentiated (UN-) SH-SY5Y cells with the highest neuroprotection mediated by mGluR8-specific agents. However, in retinoic acid- differentiated (RA-) SH-SY5Y cells we found protection mediated only by mGluR8 activators. We also demonstrated the cell proliferation stimulating effect for mGluR4 and mGluR8 PAMs. Next, we showed that the protection mediated by mGluR II/III activators in UN-SH-SY5Y was not accompanied by the modulation of caspase-3 activity, however, a decrease in the number of apoptotic nuclei was found. Finally, we showed that the inhibitor of necroptosis, necrostatin-1 blocked the mGluR III-mediated protection. Altogether our comparative in vitro data add a further proof to neuroprotective effects of mGluR agonists or PAMs and point to mGluR8 as a promising target for neuroprotective interventions in PD. The results also suggest the participation of necroptosis-related molecular pathways in neuroprotective effects of mGluR III activation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Inhibition of Group I Metabotropic Glutamate Receptors Reverses Autistic-Like Phenotypes Caused by Deficiency of the Translation Repressor eIF4E Binding Protein 2.

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Aguilar-Valles, Argel; Matta-Camacho, Edna; Khoutorsky, Arkady; Gkogkas, Christos; Nader, Karim; Lacaille, Jean-Claude; Sonenberg, Nahum

2015-08-05

Exacerbated mRNA translation during brain development has been linked to autism spectrum disorders (ASDs). Deletion of the eukaryotic initiation factor 4E (eIF4E)-binding protein 2 gene (Eif4ebp2), encoding the suppressor of mRNA translation initiation 4E-BP2, leads to an imbalance in excitatory-to-inhibitory neurotransmission and ASD-like behaviors. Inhibition of group I metabotropic glutamate receptors (mGluRs) mGluR1 and mGluR5 reverses the autistic phenotypes in several ASD mouse models. Importantly, these receptors control synaptic physiology via activation of mRNA translation. We investigated the potential reversal of autistic-like phenotypes in Eif4ebp2(-/-) mice by using antagonists of mGluR1 (JNJ16259685) or mGluR5 (fenobam). Augmented hippocampal mGluR-induced long-term depression (LTD; or chemically induced mGluR-LTD) in Eif4ebp2(-/-) mice was rescued by mGluR1 or mGluR5 antagonists. While rescue by mGluR5 inhibition occurs through the blockade of a protein synthesis-dependent component of LTD, normalization by mGluR1 antagonists requires the activation of protein synthesis. Synaptically induced LTD was deficient in Eif4ebp2(-/-) mice, and this deficit was not rescued by group I mGluR antagonists. Furthermore, a single dose of mGluR1 (0.3 mg/kg) or mGluR5 (3 mg/kg) antagonists in vivo reversed the deficits in social interaction and repetitive behaviors (marble burying) in Eif4ebp2(-/-) mice. Our results demonstrate that Eif4ebp2(-/-) mice serve as a relevant model to test potential therapies for ASD symptoms. In addition, we provide substantive evidence that the inhibition of mGluR1/mGluR5 is an effective treatment for physiological and behavioral alterations caused by exacerbated mRNA translation initiation. Exacerbated mRNA translation during brain development is associated with several autism spectrum disorders (ASDs). We recently demonstrated that the deletion of a negative regulator of mRNA translation initiation, the eukaryotic initiation factor 4E

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 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......)-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...

Intercellular signal communication among odontoblasts and trigeminal ganglion neurons via glutamate.

Science.gov (United States)

Nishiyama, A; Sato, M; Kimura, M; Katakura, A; Tazaki, M; Shibukawa, Y

2016-11-01

Various stimuli to the exposed surface of dentin induce changes in the hydrodynamic force inside the dentinal tubules resulting in dentinal pain. Recent evidences indicate that mechano-sensor channels, such as the transient receptor potential channels, in odontoblasts receive these hydrodynamic forces and trigger the release of ATP to the pulpal neurons, to generate dentinal pain. A recent study, however, has shown that odontoblasts also express glutamate receptors (GluRs). This implies that cells in the dental pulp tissue have the ability to release glutamate, which acts as a functional intercellular mediator to establish inter-odontoblast and odontoblast-trigeminal ganglion (TG) neuron signal communication. To investigate the intercellular signal communication, we applied mechanical stimulation to odontoblasts and measured the intracellular free Ca 2+ concentration ([Ca 2+ ] i ). During mechanical stimulation in the presence of extracellular Ca 2+ , we observed a transient [Ca 2+ ] i increase not only in single stimulated odontoblasts, but also in adjacent odontoblasts. We could not observe these responses in the absence of extracellular Ca 2+ . [Ca 2+ ] i increases in the neighboring odontoblasts during mechanical stimulation of single odontoblasts were inhibited by antagonists of metabotropic glutamate receptors (mGluRs) as well as glutamate-permeable anion channels. In the odontoblast-TG neuron coculture, we observed an increase in [Ca 2+ ] i in the stimulated odontoblasts and TG neurons, in response to direct mechanical stimulation of single odontoblasts. These [Ca 2+ ] i increases in the neighboring TG neurons were inhibited by antagonists for mGluRs. The [Ca 2+ ] i increases in the stimulated odontoblasts were also inhibited by mGluRs antagonists. We further confirmed that the odontoblasts express group I, II, and III mGluRs. However, we could not record any currents evoked from odontoblasts near the mechanically stimulated odontoblast, with or without

PICK1 uncoupling from mGluR7a causes absence-like seizures

OpenAIRE

Bertaso, Federica; Zhang, Chuansheng; Scheschonka, Astrid; de Bock, Frédéric; Fontanaud, Pierre; Marin, Philippe; Huganir, Richard L; Betz, Heinrich; Bockaert, Joël; Fagni, Laurent; Lerner-Natoli, Mireille

2008-01-01

Absence epilepsy is a neurological disorder that causes a recurrent loss of consciousness and generalized spike-and-wave discharges on an electroencephalogram (EEG). The role of metabotropic glutamate receptors (mGluRs) and associated scaffolding proteins in absence epilepsy has been unclear to date. We investigated a possible role for these proteins in absence epilepsy, focusing on the mGluR7a receptor and its PDZ-interacting protein, protein interacting with C kinase 1 (PICK1), in rats and ...

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

)-pyridine (MPEP) has facilitated the understanding of the roles of mGluR5s in the central nervous system. Both in vitro and in vivo studies have demonstrated that the activation of mGluR5s is necessary for some forms of long-term potentiation and long-term depression in different brain regions. Investigations...... 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...

Peri-adolescent drinking of ethanol and/or nicotine modulates astroglial glutamate transporters and metabotropic glutamate receptor-1 in female alcohol-preferring rats.

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Alasmari, Fawaz; Bell, Richard L; Rao, P S S; Hammad, Alaa M; Sari, Youssef

2018-07-01

Impairment in glutamate neurotransmission mediates the development of dependence upon nicotine (NIC) and ethanol (EtOH). Previous work indicates that continuous access to EtOH or phasic exposure to NIC reduces expression of the glutamate transporter-1 (GLT-1) and cystine/glutamate antiporter (xCT) but not the glutamate/aspartate transporter (GLAST). Additionally, metabotropic glutamate receptors (mGluRs) expression was affected following exposure to EtOH or NIC. However, little is known about the effects of EtOH and NIC co-consumption on GLT-1, xCT, GLAST, and mGluR1 expression. In this study, peri-adolescent female alcohol preferring (P) rats were given binge-like access to water, sucrose (SUC), SUC-NIC, EtOH, or EtOH-NIC for four weeks. The present study determined the effects of these reinforcers on GLT-1, xCT, GLAST, and mGluR1 expression in the nucleus accumbens (NAc), hippocampus (HIP) and prefrontal cortex (PFC). GLT-1 and xCT expression were decreased in the NAc following both SUC-NIC and EtOH-NIC. In addition, only xCT expression was downregulated in the HIP in both of these latter groups. Also, glutathione peroxidase (GPx) activity in the HIP was reduced following SUC, SUC-NIC, EtOH, and EtOH-NIC consumption. Similar to previous work, GLAST expression was not altered in any brain region by any of the reinforcers. However, mGluR1 expression was increased in the NAc in the SUC-NIC, EtOH, and EtOH-NIC groups. These results indicate that peri-adolescent binge-like drinking of EtOH or SUC with or without NIC may exert differential effects on astroglial glutamate transporters and receptors. Our data further parallel some of the previous findings observed in adult rats. Copyright © 2018. Published by Elsevier Inc.

Differential regulation of glutamate receptors in trigeminal ganglia following masseter inflammation

OpenAIRE

Lee, Jongseok; Ro, Jin Y.

2007-01-01

The present study examined whether N-methyl-D-aspartate receptor (NMDAR) and 5-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits and group I metabotropic glutamate receptors (mGluRs) are constitutively expressed in trigeminal ganglia (TG) using Western blot analysis in male Sprague Dawley rats. We then investigated whether experimental induction of masseter inflammation influences glutamate receptor expressions by comparing the protein levels from naïve rats to th...

In-vivo effects of knocking-down metabotropic glutamate receptor 5 in the SOD1G93A mouse model of amyotrophic lateral sclerosis.

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Bonifacino, Tiziana; Cattaneo, Luca; Gallia, Elena; Puliti, Aldamaria; Melone, Marcello; Provenzano, Francesca; Bossi, Simone; Musante, Ilaria; Usai, Cesare; Conti, Fiorenzo; Bonanno, Giambattista; Milanese, Marco

2017-09-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder due to loss of upper and lower motor neurons (MNs). The mechanisms of neuronal death are largely unknown, thus prejudicing the successful pharmacological treatment. One major cause for MN degeneration in ALS is represented by glutamate(Glu)-mediated excitotoxicity. We have previously reported that activation of Group I metabotropic Glu receptors (mGluR1 and mGluR5) at glutamatergic spinal cord nerve terminals produces abnormal Glu release in the widely studied SOD1 G93A mouse model of ALS. We also demonstrated that halving mGluR1 expression in the SOD1 G93A mouse had a positive impact on survival, disease onset, disease progression, and on a number of cellular and biochemical readouts of ALS. We generated here SOD1 G93A mice with reduced expression of mGluR5 (SOD1 G93A Grm5 -/+ ) by crossing the SOD1 G93A mutant mouse with the mGluR5 heterozigous Grm5 -/+ mouse. SOD1 G93A Grm5 -/+ mice showed prolonged survival probability and delayed pathology onset. These effects were associated to enhanced number of preserved MNs, decreased astrocyte and microglia activation, reduced cytosolic free Ca 2+ concentration, and regularization of abnormal Glu release in the spinal cord of SOD1 G93A Grm5 -/+ mice. Unexpectedly, only male SOD1 G93A Grm5 -/+ mice showed improved motor skills during disease progression vs. SOD1 G93A mice, while SOD1 G93A Grm5 -/+ females did not. These results demonstrate that a lower constitutive level of mGluR5 has a significant positive impact in mice with ALS and support the idea that blocking Group I mGluRs may represent a potentially effective pharmacological approach to the disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pharmacological interference with metabotropic glutamate receptor subtype 7 but not subtype 5 differentially affects within- and between-session extinction of Pavlovian conditioned fear.

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Toth, Iulia; Dietz, Monika; Peterlik, Daniel; Huber, Sabine E; Fendt, Markus; Neumann, Inga D; Flor, Peter J; Slattery, David A

2012-03-01

Fear extinction is defined as the attenuation of a conditioned-fear memory by re-exposing animals to the conditioned stimulus without the aversive stimulus. This process is known to be effectively enhanced via administration of D-cycloserine (DCS), a partial NMDA-receptor agonist. However, other glutamatergic mechanisms, such as interference with metabotropic glutamate receptor (mGluR) subtypes 5 and 7 in the extinction of aversive memories are insufficiently understood. Using the allosteric mGluR5 receptor antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP), the mGluR7 allosteric agonist N,N'-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082), and DCS for comparison, we aimed to study how pharmacological blockade of mGluR5 and activation of mGluR7 influenced within- and between-session conditioned-fear extinction training and extinction retention in rats. We show that when injected before extinction training, mGluR7 activation with AMN082 enhanced freezing and thereby attenuated within-session fear extinction, whereas both DCS and the mGluR5 receptor antagonist MPEP had no effect on this process. However, these differential drug effects were not long lasting, as no difference in extinction retention were observed 24 h later. Therefore, we assessed whether the compounds affect 24 h consolidation of extinction training following incomplete extinction training (between-session extinction). Similar to DCS, AMN082- but not MPEP-treated rats showed facilitated extinction retention, as exhibited by decreased freezing. Finally, using fluoxetine, we provide evidence that the effect of AMN082 on between-session extinction retention is most likely not via increasing 5-HT transmission. These findings demonstrate that mGluR7 activation differentially modulates conditioned-fear extinction, in dependence on the protocol employed, and suggests drugs with AMN082-like mechanisms as potential add-on drugs following exposure-based psychotherapy for fear-related human

Loss of object recognition memory produced by extended access to methamphetamine self-administration is reversed by positive allosteric modulation of metabotropic glutamate receptor 5.

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Reichel, Carmela M; Schwendt, Marek; McGinty, Jacqueline F; Olive, M Foster; See, Ronald E

2011-03-01

Chronic methamphetamine (meth) abuse can lead to persisting cognitive deficits. Here, we utilized a long-access meth self-administration (SA) protocol to assess recognition memory and metabotropic glutamate receptor (mGluR) expression, and the possible reversal of cognitive impairments with the mGluR5 allosteric modulator, 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) benzamide (CDPPB). Male, Long-Evans rats self-administered i.v. meth (0.02 mg/infusion) on an FR1 schedule of reinforcement or received yoked-saline infusions. After seven daily 1-h sessions, rats were switched to 6-h daily sessions for 14 days, and then underwent drug abstinence. Rats were tested for object recognition memory at 1 week after meth SA at 90 min and 24 h retention intervals. In a separate experiment, rats underwent the same protocol, but received either vehicle or CDPPB (30 mg/kg) after familiarization. Rats were killed on day 8 or 14 post-SA and brain tissue was obtained. Meth intake escalated over the extended access period. Additionally, meth-experienced rats showed deficits in both short- and long-term recognition memory, demonstrated by a lack of novel object exploration. The deficit at 90 min was reversed by CDPPB treatment. On day 8, meth intake during SA negatively correlated with mGluR expression in the perirhinal and prefrontal cortex, and mGluR5 receptor expression was decreased 14 days after discontinuation of meth. This effect was specific to mGluR5 levels in the perirhinal cortex, as no differences were identified in the hippocampus or in mGluR2/3 receptors. These results from a clinically-relevant animal model of addiction suggest that mGluR5 receptor modulation may be a potential treatment of cognitive dysfunction in meth addiction.

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....

Increased response to glutamate in small diameter dorsal root ganglion neurons after sciatic nerve injury.

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Kerui Gong

Full Text Available Glutamate in the peripheral nervous system is involved in neuropathic pain, yet we know little how nerve injury alters responses to this neurotransmitter in primary sensory neurons. We recorded neuronal responses from the ex-vivo preparations of the dorsal root ganglia (DRG one week following a chronic constriction injury (CCI of the sciatic nerve in adult rats. We found that small diameter DRG neurons (30 µm were unaffected. Puff application of either glutamate, or the selective ionotropic glutamate receptor agonists alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA and kainic acid (KA, or the group I metabotropic receptor (mGluR agonist (S-3,5-dihydroxyphenylglycine (DHPG, induced larger inward currents in CCI DRGs compared to those from uninjured rats. N-methyl-D-aspartate (NMDA-induced currents were unchanged. In addition to larger inward currents following CCI, a greater number of neurons responded to glutamate, AMPA, NMDA, and DHPG, but not to KA. Western blot analysis of the DRGs revealed that CCI resulted in a 35% increase in GluA1 and a 60% decrease in GluA2, the AMPA receptor subunits, compared to uninjured controls. mGluR1 receptor expression increased by 60% in the membrane fraction, whereas mGluR5 receptor subunit expression remained unchanged after CCI. These results show that following nerve injury, small diameter DRG neurons, many of which are nociceptive, have increased excitability and an increased response to glutamate that is associated with changes in receptor expression at the neuronal membrane. Our findings provide further evidence that glutamatergic transmission in the periphery plays a role in nociception.

Aberrant modulation of a delayed rectifier potassium channel by glutamate in Alzheimer's disease.

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Poulopoulou, Cornelia; Markakis, Ioannis; Davaki, Panagiota; Tsaltas, Eleftheria; Rombos, Antonis; Hatzimanolis, Alexandros; Vassilopoulos, Dimitrios

2010-02-01

In Alzheimer's disease (AD), potassium channel abnormalities have been reported in both neural and peripheral tissues. Herein, using whole-cell patch-clamp, we demonstrate an aberrant glutamate-dependent modulation of K(V)1.3 channels in T lymphocytes of AD patients. Although intrinsic K(V)1.3 properties in patients were similar to healthy individuals, glutamate (1-1000 microM) failed to yield the hyperpolarizing shift normally observed in K(V)1.3 steady-state inactivation (-4.4+/-2.7 mV in AD vs. -14.3+/-2.5 mV in controls, 10 microM glutamate), resulting in a 4-fold increase of resting channel activity. Specific agonist and antagonist data indicate that this abnormality is due to dysfunction of cognate group II mGluRs. Given that glutamate is present in plasma and that both mGluRs and K(V)1.3 channels regulate T-lymphocyte responsiveness, our finding may account for the presence of immune-associated alterations in AD. Furthermore, if this aberration reflects a corresponding one in neural tissue, it could provide a potential target in AD pathogenesis.

In vivo positron emission tomography imaging with [{sup 11}C]ABP688: binding variability and specificity for the metabotropic glutamate receptor subtype 5 in baboons

Energy Technology Data Exchange (ETDEWEB)

DeLorenzo, Christine; Brennan, Kathleen G. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); Milak, Matthew S.; Parsey, Ramin V. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); New York State Psychiatric Institute, New York, NY (United States); Kumar, J.S.D.; Mann, J.J. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); New York State Psychiatric Institute, New York, NY (United States); Columbia University College of Physicians and Surgeons, Department of Radiology, New York, NY (United States)

2011-06-15

Metabotropic glutamate receptor subtype 5 (mGluR5) dysfunction has been implicated in several disorders. [{sup 11}C]ABP688, a positron emission tomography (PET) ligand targeting mGluR5, could be a valuable tool in the development of novel therapeutics for these disorders by establishing in vivo drug occupancy. Due to safety concerns in humans, these studies may be performed in nonhuman primates. Therefore, in vivo characterization of [{sup 11}C]ABP688 in nonhuman primates is essential. Test-retest studies were performed in baboons (Papio anubis) to compare modeling approaches and determine the optimal reference region. The mGluR5-specific antagonist 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine (MTEP) was then used in test-block studies, in which ligand binding was measured before and after MTEP administration. Test/block data were analyzed both by calculating changes in binding and using a graphical approach, which allowed estimation of both MTEP occupancy and nonspecific binding. Test-retest results, which have not been previously reported for [{sup 11}C]ABP688, indicated that [{sup 11}C]ABP688 variability is low using an unconstrained two-tissue compartment model. The most appropriate, though not ideal, reference region was found to be the gray matter of the cerebellum. Using these optimal modeling techniques on the test/block data, about 90% occupancy was estimated by the graphical approach. These studies are the first to demonstrate the specificity of [{sup 11}C]ABP688 for mGluR5 with in vivo PET in nonhuman primates. The results indicate that, in baboons, occupancy of mGluR5 is detectable by in vivo PET, a useful finding for proceeding to human studies, or performing further baboon studies, quantifying the in vivo occupancy of novel therapeutics targeting mGluR5. (orig.)

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.

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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.

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

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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.

The change of metabotropic glutamate receptor 5 expression level in rats with late-stage traumatic brain injury and the therapeutic effect of taurine

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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

Species differences in mGluR5 binding sites in mammalian central nervous system determined using in vitro binding with [18F]F-PEB

International Nuclear Information System (INIS)

Patel, Shil; Hamill, Terence G.; Connolly, Brett; Jagoda, Elaine; Li Wenping; Gibson, Raymond E.

2007-01-01

Binding of [ 18 F]3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ([ 18 F]F-PEB) was evaluated in membranes and tissue sections prepared from rat, rhesus and human brain. Saturation equilibrium binding experiments with frozen brain cortex and caudate-putamen membranes of young adult rhesus and human and with cortex and striatum from rat yielded data indicative of specific high-affinity binding (K D =0.1-0.15 nM, n≥3) to a saturable site previously shown to be metabotropic glutamate receptor 5 (mGluR5; Patel S, Ndubizu O, Hamill T, Chaudhary A, Burns HD, Hargreaves RJ, Gibson RE. Screening cascade and development of potential positron emission tomography radiotracers for mGluR5: in vitro and in vivo characterization. Mol Imaging Biol 2005;7:314-323). High-affinity binding of [ 18 F]F-PEB was also detected in cerebellum membranes from rat, rhesus and human. The density of binding sites (B max ) measured using [ 18 F]F-PEB followed the rank order cortex∼caudate-putamen/striatum>cerebellum for all three species, with the cerebellum B max being significantly lower than that observed in the other regions. Receptor autoradiography studies in tissue sections confirmed that the regional distribution of [ 18 F]F-PEB in mammalian central nervous system is consistent with that of mGluR5 and that a small but specific mGluR5 signal is observed in rhesus and human cerebellum. A small and quantifiable specific signal could also be observed in rat cerebellum using this radiotracer. Immunohistochemical analysis in brain sections revealed a rank order of staining in rhesus and human brain of cortex∼caudate-putamen>cerebellum. Rat brain immunohistochemistry followed the same rank order, although the staining in the cerebellum was significantly lower. Using a 'no-wash' wipe assay, the development of a specific signal within 20 min of incubation of tissue brain sections (>60% in the cortex and striatum; 36-49% in the cerebellum) from all three species confirmed previous in vivo

Long-Lasting Impairment of mGluR5-Activated Intracellular Pathways in the Striatum After Withdrawal of Cocaine Self-Administration

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Hoffmann, Hanne Mette; Crouzin, Nadine; Moreno, Estefanía; Raivio, Noora; Fuentes, Silvia; McCormick, Peter J.; Vignes, Michel

2017-01-01

Abstract Background: Cocaine addiction continues to be a major heath concern, and despite public health intervention there is a lack of efficient pharmacological treatment options. A newly identified potential target are the group I metabotropic glutamate receptors, with allosteric modulators showing particular promise. Methods: We evaluated the capacity of group I metabotropic glutamate receptors to induce functional responses in ex vivo striatal slices from rats with (1) acute cocaine self-administration, (2) chronic cocaine self-administration, and (3) 60 days cocaine self-administration withdrawal by Western blot and extracellular recordings of synaptic transmission. Results: We found that striatal group I metabotropic glutamate receptors are the principal mediator of the mGluR1/5 agonist (RS)-3,5-dihydroxyphenylglycine-induced cAMP responsive-element binding protein phosphorylation. Both acute and chronic cocaine self-administration blunted group I metabotropic glutamate receptor effects on cAMP responsive-element binding protein phosphorylation in the striatum, which correlated with the capacity to induce long-term depression, an effect that was maintained 60 days after chronic cocaine self-administration withdrawal. In the nucleus accumbens, the principal brain region mediating the rewarding effects of drugs, chronic cocaine self-administration blunted group I metabotropic glutamate receptor stimulation of extracellular signal-regulated protein kinases 1/2 and cAMP responsive-element binding protein. Interestingly, the group I metabotropic glutamate receptor antagonist/inverse-agonist, 2-methyl-6-(phenylethynyl)pyridine hydrochloride, led to a specific increase in cAMP responsive-element binding protein phosphorylation after chronic cocaine self-administration, specifically in the nucleus accumbens, but not in the striatum. Conclusions: Prolonged cocaine self-administration, through withdrawal, leads to a blunting of group I metabotropic glutamate receptor

Therapeutic potential of mGluR5 targeting in Alzheimer's disease

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Anil eKumar

2015-06-01

Full Text Available Decades of research dedicated towards Alzheimer's disease (AD has culminated in much of the current understanding of the neurodegeneration associated with disease. However, delineating the pathophysiology and finding a possible cure for the disease is still wanting. This is in part due to the lack of knowledge pertaining to the connecting link between neurodegenerative and neuroinflammatory pathways. Consequently, the inefficacy and ill-effects of the drugs currently available for AD encourage the need for alternative and safe therapeutic intervention. In this review we highlight the potential of mGluR5, a metabotropic glutamatergic receptor, in understanding the mechanism underlying the neuronal death and neuroinflammation in AD. We also discuss the role of mGlu5 receptor in mediating the neuron-glia interaction in the disease. Finally, we discuss the potential of mGluR5 as target for treating AD.

Structure of metabotropic glutamate receptor C-terminal domains in contact with interacting proteins

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Ralf eEnz

2012-04-01

Full Text Available Metabotropic glutamate receptors (mGluRs regulate intracellular signal pathways that control several physiological tasks, including neuronal excitability, learning and memory. This is achieved by the formation of synaptic signal complexes, in which mGluRs assemble with functionally related proteins such as enzymes, scaffolds and cytoskeletal anchor proteins. Thus, mGluR associated proteins actively participate in the regulation of glutamatergic neurotransmission. Importantly, dysfunction of mGluRs and interacting proteins may lead to impaired signal transduction and finally result in neurological disorders, e.g. night blindness, addiction, epilepsy, schizophrenia, autism spectrum disorders and Parkinson´s disease. In contrast to solved crystal structures of extracellular N-terminal domains of some mGluR types, only a few studies analyzed the conformation of intracellular receptor domains. Intracellular C-termini of most mGluR types are subject to alternative splicing and can be further modified by phosphorylation and SUMOylation. In this way, diverse interaction sites for intracellular proteins that bind to and regulate the glutamate receptors are generated. Indeed, most of the known mGluR binding partners interact with the receptors´ C-terminal domains. Within the last years, different laboratories analyzed the structure of these domains and described the geometry of the contact surface between mGluR C-termini and interacting proteins. Here, I will review recent progress in the structure characterization of mGluR C-termini and provide an up-to-date summary of the geometry of these domains in contact with binding partners.

Effects of the mGluR5 antagonist MPEP on ethanol withdrawal induced anxiety-like syndrome in rats.

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Kumar, Jaya; Hapidin, Hermizi; Bee, Yvonne-Tee Get; Ismail, Zalina

2013-11-26

Abstinence from chronic ethanol consumption leads to the manifestation of a variety of symptoms attributed to central nervous system hyperexcitability, such as increased irritability, anxiety, and restlessness. Recent studies have demonstrated the importance of metabotropic glutamate receptor 5 (mGluR5) in addictive behaviours. This study investigates the effects of the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) on ethanol withdrawal induced anxiety using two behavioural paradigms. Male Wistar rats were fed a Modified Liquid Diet (MLD) containing low fat cow milk, sucrose, and maltodextrin with a gradual introduction of 2.4%, 4.8% and 7.2% ethanol for 20 days. Six hours into ethanol withdrawal, the rats were intraperitoneally injected with normal saline and MPEP (2.5, 5.0, 10, 20, 30 mg/kg) and were assessed for ethanol withdrawal induced anxiety-like syndrome using an automated elevated plus maze and an open field. MPEP at 10 mg/kg significantly attenuated ethanol withdrawal induced anxiety without any compromising effects on locomotor activities. Despite reversing several indices of ethanol withdrawal induced anxiety in both the elevated plus maze and the open field, low doses of MPEP (2.5, 5 mg/kg) significantly compromised the locomotor activities of ethanol withdrawn rats. High doses of MPEP (20 and 30 mg/kg) significantly attenuated withdrawal anxiety when tested in the elevated plus maze but not in the open field. Administration of MPEP (2.5, 5, 10, 20, 30 mg/kg) has no significant compromising effect on the locomotor activities of ethanol naïve rats. Despite significantly reducing withdrawal anxiety in both behavioural paradigms at 10 mg/kg, the compromising effects of low and high doses of MPEP must be further explored along with the therapeutic efficiency of this drug for relieving withdrawal induced anxiety.

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

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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.

Selectivity and Evolutionary Divergence of Metabotropic Glutamate Receptors for Endogenous Ligands and G Proteins Coupled to Phospholipase C or TRP Channels*

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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

Adenosine A2A Receptor in the Monkey Basal Ganglia: Ultrastructural Localization and Colocalization With the Metabotropic Glutamate Receptor 5 in the Striatum

OpenAIRE

Bogenpohl, James W.; Ritter, Stefanie L.; Hall, Randy A.; Smith, Yoland

2012-01-01

The adenosine A2A receptor (A2AR) is a potential drug target for the treatment of Parkinson’s disease and other neurological disorders. In rodents, the therapeutic efficacy of A2AR modulation is improved by concomitant modulation of the metabotropic glutamate receptor 5 (mGluR5). To elucidate the anatomical substrate(s) through which these therapeutic benefits could be mediated, pre-embedding electron microscopy immunohistochemistry was used to conduct a detailed, quantitative ultrastructural...

Hippocampal mGluR5 predicts an occurrence of helplessness behavior after repetitive exposure to uncontrollable stress.

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Yim, Yeong Shin; Lee, Jinu; Kim, Gun-Tae; Song, Teresa; Kim, Chul Hoon; Kim, Dong Goo

2012-06-21

An individual's behavior is generally based on genetic blueprint and previous experiences. A coping strategy, affected by personal interpretation of past events, can be determined by behavioral controllability of stress. In this study, we examined the relationship between the hippocampal mGluR5 expression and coping strategies to stress. Rats were exposed to stress via inescapable and unpredictable footshocks on PNDs 14 and 90. Coping strategies to stress were also measured. Hippocampal mGluR5 was found to be linked to the behavioral coping strategy, as it increased in rats that showed helplessness behavior (HL (+) group) and decreased in those that did not (HL (-) group). Also, the HL (+) group showed a lack of adaptation in a novel environment but the HL (-) group did not. The results suggest that mGluR5 has a pivotal role in the controllability-based coping strategy. Hippocampal mGluR5 could be a target molecule in the manipulation of neuropsychiatric conditions for which maladaptation is a part of behavioral consequences. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Localization of metabotropic glutamate receptors in the outer plexiform layer of the goldfish retina

NARCIS (Netherlands)

Joselevitch, Christina; Klooster, Jan; Kamermans, Maarten

2007-01-01

We studied the localization of metabotropic glutamate receptors (mGluRs) in the goldfish outer plexiform layer by light-and electron-microscopical immunohistochemistry. The mGluR1alpha antibody labeled putative ON-type bipolar cell dendrites and horizontal cell processes in both rod spherules and

Prenatal chronic mild stress induces depression-like behavior and sex-specific changes in regional glutamate receptor expression patterns in adult rats.

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Wang, Y; Ma, Y; Hu, J; Cheng, W; Jiang, H; Zhang, X; Li, M; Ren, J; Li, X

2015-08-20

Chronic stress during critical periods of human fetal brain development is associated with cognitive, behavioral, and mood disorders in later life. Altered glutamate receptor (GluR) expression has been implicated in the pathogenesis of stress-dependent disorders. To test whether prenatal chronic mild stress (PCMS) enhances offspring's vulnerability to stress-induced behavioral and neurobiological abnormalities and if this enhanced vulnerability is sex-dependent, we measured depression-like behavior in the forced swimming test (FST) and regional changes in GluR subunit expression in PCMS-exposed adult male and female rats. Both male and female PCMS-exposed rats exhibited stronger depression-like behavior than controls. Males and females exhibited unique regional changes in GluR expression in response to PCMS alone, FST alone (CON-FST), and PCMS with FST (PCMS-FST). In females, PCMS alone did not alter N-methyl-d-aspartate receptor (NMDAR) or metabotropic glutamate receptor (mGluR) expression, while in PCMS males, higher mGluR2/3, mGluR5, and NR1 expression levels were observed in the prefrontal cortex. In addition, PCMS altered the change in GluR expression induced by acute stress (the FST test), and this too was sex-specific. Male PCMS-FST rats expressed significantly lower mGluR5 levels in the hippocampus, lower mGluR5, NR1, postsynaptic density protein (PSD)95, and higher mGluR2/3 in the prefrontal cortex, and higher mGluR5 and PSD95 in the amygdala than male CON-FST rats. Female PCMS-FST rats expressed lower NR1 in the hippocampus, lower NR2B and PSD95 in the prefrontal cortex, lower mGluR2/3 in the amygdala, and higher PSD95 in the amygdala than female CON-FST rats. PCMS may increase the offspring's vulnerability to depression by altering sex-specific stress-induced changes in glutamatergic signaling. Copyright © 2015. Published by Elsevier Ltd.

Species differences in mGluR5 binding sites in mammalian central nervous system determined using in vitro binding with [{sup 18}F]F-PEB

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Patel, Shil [Department of Research Imaging, Merck Research Laboratories, West Point, PA 19486 (United States)], E-mail: shailendra_patel@merck.com; Hamill, Terence G.; Connolly, Brett; Jagoda, Elaine; Li Wenping; Gibson, Raymond E. [Department of Research Imaging, Merck Research Laboratories, West Point, PA 19486 (United States)

2007-11-15

Binding of [{sup 18}F]3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ([{sup 18}F]F-PEB) was evaluated in membranes and tissue sections prepared from rat, rhesus and human brain. Saturation equilibrium binding experiments with frozen brain cortex and caudate-putamen membranes of young adult rhesus and human and with cortex and striatum from rat yielded data indicative of specific high-affinity binding (K{sub D}=0.1-0.15 nM, n{>=}3) to a saturable site previously shown to be metabotropic glutamate receptor 5 (mGluR5; Patel S, Ndubizu O, Hamill T, Chaudhary A, Burns HD, Hargreaves RJ, Gibson RE. Screening cascade and development of potential positron emission tomography radiotracers for mGluR5: in vitro and in vivo characterization. Mol Imaging Biol 2005;7:314-323). High-affinity binding of [{sup 18}F]F-PEB was also detected in cerebellum membranes from rat, rhesus and human. The density of binding sites (B{sub max}) measured using [{sup 18}F]F-PEB followed the rank order cortex{approx}caudate-putamen/striatum>cerebellum for all three species, with the cerebellum B{sub max} being significantly lower than that observed in the other regions. Receptor autoradiography studies in tissue sections confirmed that the regional distribution of [{sup 18}F]F-PEB in mammalian central nervous system is consistent with that of mGluR5 and that a small but specific mGluR5 signal is observed in rhesus and human cerebellum. A small and quantifiable specific signal could also be observed in rat cerebellum using this radiotracer. Immunohistochemical analysis in brain sections revealed a rank order of staining in rhesus and human brain of cortex{approx}caudate-putamen>cerebellum. Rat brain immunohistochemistry followed the same rank order, although the staining in the cerebellum was significantly lower. Using a 'no-wash' wipe assay, the development of a specific signal within 20 min of incubation of tissue brain sections (>60% in the cortex and striatum; 36-49% in the cerebellum

Metabotropic glutamate receptor type 1 autoimmunity

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Lopez-Chiriboga, A. Sebastian; Komorowski, Lars; Kümpfel, Tania; Probst, Christian; Hinson, Shannon R.; Pittock, Sean J.

2016-01-01

Objective: To describe retrospectively the clinical associations of immunoglobulin G (IgG) targeting metabotropic glutamate receptor 1 (mGluR1-IgG). Methods: Specimens of 9 patients evaluated on a service basis in the Mayo Clinic Neuroimmunology Laboratory by tissue-based immunofluorescence assay (IFA) yielded a robust, synaptic immunostaining pattern consistent with mGluR1-IgG (serum, 9; CSF, 2 available). Transfected HEK293 cell-based assay (CBA) confirmed mGluR1 specificity in all 11 specimens. A further 2 patients were detected in Germany primarily by CBA. Results: The median symptom onset age for the 11 patients was 58 years (range 33–81 years); 6 were male. All 9 Mayo Clinic patients had subacute onset of cerebellar ataxia, 4 had dysgeusia, 1 had psychiatric symptoms, and 1 had cognitive impairment. All were evaluated for malignancy, but only 1 was affected (cutaneous T-cell lymphoma). One developed ataxia post–herpes zoster infection. Head MRIs were generally atrophic or normal-appearing, and CSF was inflammatory in just 1 of 5 tested, though mGluR1-IgG was detected in both specimens submitted. Five patients improved (attributable to immunotherapy in 4, spontaneously in 1), 3 stabilized (attributable to immunotherapy in 2, cancer therapy in 1), and 1 progressively declined (untreated). The 2 German patients had ataxia, but fulfilled multiple sclerosis diagnostic criteria (1 relapsing-remitting, 1 progressive). However, both had histories of hematologic malignancy (acute lymphocytic leukemia and mantle cell lymphoma), and had mGluR1-IgG detected in serum by CBA (weakly positive on tissue-based IFA). Conclusions: mGluR1 autoimmunity represents a treatable form of cerebellar ataxia. Dysgeusia may be a diagnostic clue. Paraneoplastic, parainfectious, or idiopathic causes may occur. PMID:26888994

Evaluation in vitro and in animals of a new 11C-labeled PET radioligand for metabotropic glutamate receptors 1 in brain

International Nuclear Information System (INIS)

Zanotti-Fregonara, Paolo; Liow, Jeih-San; Zoghbi, Sami S.; Clark, David T.; Morse, Cheryl; Pike, Victor W.; 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; Innis, Robert B.

2013-01-01

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 50 8.9 nM) and partial mGluR5 antagonist (IC 50 118 nM), and LSN2606428, a full mGluR1 and mGluR5 antagonist (IC 50 35.3 nM and 10.2 nM, respectively) were successfully labeled with 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. 11 C-LY2428703 showed promising characteristics, including: (1) high potency for binding to human mGluR1 (IC 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. 11 C-LY2428703, a new PET radioligand for mGluR1 quantification, displayed promising characteristics both in vitro and in vivo in rodents. (orig.)

Evaluation in vitro and in animals of a new {sup 11}C-labeled PET radioligand for metabotropic glutamate receptors 1 in brain

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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.)

Activity of Metabotropic Glutamate Receptor 4 Suppresses Proliferation and Promotes Apoptosis With Inhibition of Gli-1 in Human Glioblastoma Cells

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Zhichao Zhang

2018-05-01

Full Text Available Glioblastoma multiforme (GBM is the most lethal glioma variant in the adult brain and among the deadliest of human cancers. Increasing evidence has shown that metabotropic glutamate receptor subtype 4 (mGluR4 expression may play roles in regulating the growth of neural stem cells as well as several cancer cell lines. Here, we investigated the effects of mGluR4 on the growth and apoptosis of the LN229 GBM cell line. Involvement of Gli-1, one of the key transcription factors in the sonic Hedgehog (SHH signaling pathway, was further explored. In this study, mGluR4 was activated using selective agonist VU0155041; and gene-targeted siRNAs were used to generate loss of function of mGluR4 and Gli-1 in LN229 cells. The results demonstrated that LN229 cells expressed mGluR4 and the agonist VU0155041 decreased cell viability in a dose- and time-dependent manner. Activation of mGluR4 inhibited cyclin D1 expression, activated pro-caspase-8/9/3, and disrupted the balance of Bcl-2/Bax expression, which indicated cell cycle arrest and apoptosis of LN229 cells, respectively. Furthermore, Gli-1 expression was reduced by mGluR4 activation in LN229 cells, and downregulation of Gli-1 expression by gene-targeted siRNA resulted in both inhibition of cell proliferation and promotion of apoptosis. Moreover, VU0155041 treatment substantially blocked SHH-induced cyclin D1 expression and cell proliferation, while increasing TUNEL-positive cells and the activation of apoptosis-related proteins. We concluded that activation of mGluR4 expressed in LN229 cells could inhibit GBM cell growth by decreasing cell proliferation and promoting apoptosis. Further suppression of intracellular Gli-1 expression might be involved in the action of mGluR4 on cancer cells. Our study suggested a novel role of mGluR4, which might serve as a potential drug target for control of GBM cell growth.

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

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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.

Metabotropic glutamate receptor subtype 7 ablation causes dysregulation of the HPA axis and increases hippocampal BDNF protein levels: implications for stress-related psychiatric disorders.

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Mitsukawa, Kayo; Mombereau, Cedric; Lötscher, Erika; Uzunov, Doncho P; van der Putten, Herman; Flor, Peter J; Cryan, John F

2006-06-01

Regulation of neurotransmission via group-III metabotropic glutamate receptors (mGluR4, -6, -7, and -8) has recently been implicated in the pathophysiology of affective disorders, such as major depression and anxiety. For instance, mice with a targeted deletion of the gene for mGluR7 (mGluR7-/-) showed antidepressant and anxiolytic-like effects in a variety of stress-related paradigms, including the forced swim stress and the stress-induced hyperthermia tests. Deletion of mGluR7 reduces also amygdala- and hippocampus-dependent conditioned fear and aversion responses. Since the hypothalamic-pituitary-adrenal (HPA) axis regulates the stress response we investigate whether parameters of the HPA axis at the levels of selected mRNA transcripts and endocrine hormones are altered in mGluR7-deficient mice. Over all, mGluR7-/- mice showed only moderately lower serum levels of corticosterone and ACTH compared with mGluR7+/+ mice. More strikingly however, we found strong evidence for upregulated glucocorticoid receptor (GR)-dependent feedback suppression of the HPA axis in mice with mGluR7 deficiency: (i) mRNA transcripts of GR were significantly upregulated in the hippocampus of mGluR7-/- animals, (ii) similar increases were seen with 5-HT1A receptor transcripts, which are thought to be directly controlled by the transcription factor GR and finally (iii) mGluR7-/- mice showed elevated sensitivity to dexamethasone-induced suppression of serum corticosterone when compared with mGluR7+/+ animals. These results indicate that mGluR7 deficiency causes dysregulation of HPA axis parameters, which may account, at least in part, for the phenotype of mGluR7-/- mice in animal models for anxiety and depression. In addition, we present evidence that protein levels of brain-derived neurotrophic factor are also elevated in the hippocampus of mGluR7-/- mice, which we discuss in the context of the antidepressant-like phenotype found in those animals. We conclude that genetic ablation of mGluR

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

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Meldrum, B S

2000-04-01

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

Developmental shift from long-term depression to long-term potentiation in the rat medial vestibular nuclei: role of group I metabotropic glutamate receptors.

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Puyal, Julien; Grassi, Silvarosa; Dieni, Cristina; Frondaroli, Adele; Demêmes, Danielle; Raymond, Jaqueline; Pettorossi, Vito Enrico

2003-12-01

The effects of high frequency stimulation (HFS) of the primary vestibular afferents on synaptic transmission in the ventral part of the medial vestibular nuclei (vMVN) were studied during postnatal development and compared with the changes in the expression of the group I metabotropic glutamate receptor (mGluR) subtypes, mGluR1 and mGluR5. During the first stages of development, HFS always induced a mGluR5- and GABAA-dependent long-term depression (LTD) which did not require NMDA receptor and mGluR1 activation. The probability of inducing LTD decreased progressively throughout the development and it was zero at about the end of the second postnatal week. Conversely, long-term potentiation (LTP) appeared at the beginning of the second week and its occurrence increased to reach the adult value at the end of the third week. Of interest, the sudden change in the LTP frequency occurred at the time of eye opening, about the end of the second postnatal week. LTP depended on NMDA receptor and mGluR1 activation. In parallel with the modifications in synaptic plasticity, we observed that the expression patterns and localizations of mGluR5 and mGluR1 in the medial vestibular nuclei (MVN) changed during postnatal development. At the earlier stages the mGluR1 expression was minimal, then increased progressively. In contrast, mGluR5 expression was initially high, then decreased. While mGluR1 was exclusively localized in neuronal compartments and concentrated at the postsynaptic sites at all stages observed, mGluR5 was found mainly in neuronal compartments at immature stages, then preferentially in glial compartments at mature stages. These results provide the first evidence for a progressive change from LTD to LTP accompanied by a distinct maturation expression of mGluR1 and mGluR5 during the development of the MVN.

Pain-related increase of excitatory transmission and decrease of inhibitory transmission in the central nucleus of the amygdala are mediated by mGluR1

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Neugebauer Volker

2010-12-01

Full Text Available Abstract Neuroplasticity in the central nucleus of the amygdala (CeA, particularly its latero-capsular division (CeLC, is an important contributor to the emotional-affective aspects of pain. Previous studies showed synaptic plasticity of excitatory transmission to the CeLC in different pain models, but pain-related changes of inhibitory transmission remain to be determined. The CeLC receives convergent excitatory inputs from the parabrachial nucleus in the brainstem and from the basolateral amygdala (BLA. In addition, feedforward inhibition of CeA neurons is driven by glutamatergic projections from the BLA area to a cluster of GABAergic neurons in the intercalated cell masses (ITC. Using patch-clamp in rat brain slices we measured monosynaptic excitatory postsynaptic currents (EPSCs and polysynaptic inhibitory currents (IPSCs that were evoked by electrical stimulation in the BLA. In brain slices from arthritic rats, input-output functions of excitatory synaptic transmission were enhanced whereas inhibitory synaptic transmission was decreased compared to control slices from normal untreated rats. A non-NMDA receptor antagonist (NBQX blocked the EPSCs and reduced the IPSCs, suggesting that non-NMDA receptors mediate excitatory transmission and also contribute to glutamate-driven feed-forward inhibition of CeLC neurons. IPSCs were blocked by a GABAA receptor antagonist (bicuculline. Bicuculline increased EPSCs under normal conditions but not in slices from arthritic rats, which indicates a loss of GABAergic control of excitatory transmission. A metabotropic glutamate receptor subtype 1 (mGluR1 antagonist (LY367385 reversed both the increase of excitatory transmission and the decrease of inhibitory transmission in the arthritis pain model but had no effect on basal synaptic transmission in control slices from normal rats. The inhibitory effect of LY367385 on excitatory transmission was blocked by bicuculline suggesting the involvement of a GABAergic

mGluR5 positive allosteric modulation and its effects on MK-801 induced set-shifting impairments in a rat operant delayed matching/non-matching-to-sample task

Science.gov (United States)

LaCrosse, Amber L.; Burrows, Brian T.; Angulo, Rachel M.; Conrad, Phoebe R.; Himes, Sarah M.; Mathews, Nordia; Wegner, Scott A.; Taylor, Sara B.; Olive, M. Foster

2014-01-01

Rationale Positive allosteric modulators (PAMs) of type 5 metabotropic glutamate receptors (mGluR5) exert pro-cognitive effects in animal models of various neuropsychiatric diseases. However, few studies to date have examined ability of mGluR5 PAMs to reverse cognitive deficits in operant delayed matching/non-matching-to-sample (DMS/DNMS) tasks. Objectives To determine the ability of the mGluR5 PAM 3-cyano-N-1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) to reverse set-shifting deficits induced by the NMDA receptor antagonist MK-801. Methods Male Sprague-Dawley rats were initially trained to lever press for sucrose reinforcement under either DMS or DNMS conditions. Following successful acquisition of the task, reinforcement conditions were reversed (DNMS→DMS or DMS→DNMS). In Experiment 1, rats were treated daily prior to each session with either vehicle/vehicle, vehicle/MK-801 (0.06 mg/kg) simultaneously, CDPPB (20 mg/kg)/MK-801 simultaneously, or CDPPB 30 min prior to MK-801. In Experiment 2, rats were treated with either vehicle/vehicle, vehicle/MK-801, or CDPPB 30 min prior to MK-801 only prior to sessions that followed task reversal. Results In Experiment 1, no group differences in initial task acquisition were observed. Rats treated with vehicle+MK−801 showed significant set-shifting impairments following task reversal, which were partially attenuated by simultaneous administration of CDPPB/MK-801, and completely precluded by administration of CDPPB 30 min prior to MK-801. In Experiment 2, MK-801 did not impair reversal learning and no other group differences were observed. Conclusions MK-801 induced deficits in operant set-shifting ability were prevented by pretreatment with CDPPB. MK-801 did not produce deficits in initial task learning or when treatment was initiated following task reversal. PMID:24973895

Group I mGluR antagonist rescues the deficit of D1-induced LTP in a mouse model of fragile X syndrome

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Xu Zhao-Hui

2012-05-01

Full Text Available Abstract Background Fragile X syndrome (FXS is caused by the absence of the mRNA-binding protein Fragile X mental retardation protein (FMRP, encoded by the Fmr1 gene. Overactive signaling by group 1 metabotropic glutamate receptor (Grp1 mGluR could contribute to slowed synaptic development and other symptoms of FXS. Our previous study has identified that facilitation of synaptic long-term potentiation (LTP by D1 receptor is impaired in Fmr1 knockout (KO mice. However, the contribution of Grp1 mGluR to the facilitation of synaptic plasticity by D1 receptor stimulation in the prefrontal cortex has been less extensively studied. Results Here we demonstrated that DL-AP3, a Grp1 mGluR antagonist, rescued LTP facilitation by D1 receptor agonist SKF81297 in Fmr1KO mice. Grp1 mGluR inhibition restored the GluR1-subtype AMPA receptors surface insertion by D1 activation in the cultured Fmr1KO neurons. Simultaneous treatment of Grp1 mGluR antagonist with D1 agonist recovered the D1 receptor signaling by reversing the subcellular redistribution of G protein-coupled receptor kinase 2 (GRK2 in the Fmr1KO neurons. Treatment of SKF81297 alone failed to increase the phosphorylation of NR2B-containing N-methyl D-aspartate receptors (NMDARs at Tyr-1472 (p-NR2B-Tyr1472 in the cultures from KO mice. However, simultaneous treatment of DL-AP3 could rescue the level of p-NR2B-Tyr1472 by SKF81297 in the cultures from KO mice. Furthermore, behavioral tests indicated that simultaneous treatment of Grp1 mGluR antagonist with D1 agonist inhibited hyperactivity and improved the learning ability in the Fmr1KO mice. Conclusion The findings demonstrate that mGluR1 inhibition is a useful strategy to recover D1 receptor signaling in the Fmr1KO mice, and combination of Grp1 mGluR antagonist and D1 agonist is a potential drug therapy for the FXS.

Microscopic visualization of metabotropic glutamate receptors on the surface of living cells using bifunctional magnetic resonance imaging probes.

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Mishra, Anurag; Mishra, Ritu; Gottschalk, Sven; Pal, Robert; Sim, Neil; Engelmann, Joern; Goldberg, Martin; Parker, David

2014-02-19

A series of bimodal metabotropic glutamate-receptor targeted MRI contrast agents has been developed and evaluated, based on established competitive metabotropic Glu receptor subtype 5 (mGluR5) antagonists. In order to directly visualize mGluR5 binding of these agents on the surface of live astrocytes, variations in the core structure were made. A set of gadolinium conjugates containing either a cyanine dye or a fluorescein moiety was accordingly prepared, to allow visualization by optical microscopy in cellulo. In each case, surface receptor binding was compromised and cell internalization observed. Another approach, examining the location of a terbium analogue via sensitized emission, also exhibited nonspecific cell uptake in neuronal cell line models. Finally, biotin derivatives of two lead compounds were prepared, and the specificity of binding to the mGluR5 cell surface receptors was demonstrated with the aid of their fluorescently labeled avidin conjugates, using both total internal reflection fluorescence (TIRF) and confocal microscopy.

NMDA and mGluR1 receptor subtypes as major players affecting depotentiation in the hippocampal CA1-region

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Amira Latif-Hernandez

2014-03-01

Full Text Available Neurons have the ability to modify their structure and function which ultimately serves for learning (Abraham and Bear, 1996. Dendritic events provide a major contribution to such modifications. For example, natural and artificial patterns of afferent activation have been shown to induce persistent forms of synaptic plasticity, such as long-term potentiation (LTP and long-term depression (LTD at distinct dendritic synapses. LTP and LTD are both assumed to occur during the physiological processes of learning and memory formation and to sustain the latter (Abraham, 2008. In recent years, there has been a burgeoning interest in the understanding of metaplasticity, which refers to the plasticity of synaptic plasticity (Abraham and Bear, 1996. In particular, depotentiation (DP is the mechanism by which synapses that have recently undergone LTP can reverse their synaptic strengthening in response to low frequency stimulation (LFS; Abraham, 2008. Typically, DP is thought to prevent the saturation of synaptic potentiation by resetting synapses into a more efficient state to store new information. The detailed mechanisms that underlie DP still remain unclear. Bortolotto et al. (1994 first identified metabotropic glutamate receptors (mGluRs as being involved in DP. Experimental evidence indicates that both subtypes of group I mGluRs (mGluR1 and mGluR5 have distinct functions in synaptic plasticity in the hippocampal CA1 region (Gladding et al., 2008. However, their role in DP was not addressed yet in detail and appear to be distinct from those involved in NMDAR-dependent DP (Zho et al., 2002. Therefore, we investigated the precise mechanisms responsible for NMDAR and mGluR-dependent DP by combining electrophysiological recordings in vitro and pharmacological approach. Transverse hippocampal slices (400 µm thick were prepared from the right hippocampus with a tissue chopper and placed into a submerged-type chamber, where they were continuously perfused

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

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

2001-01-01

a molecular model of the ATD of mGluR1 based on a weak amino acid sequence similarity with a bacterial periplasmic binding protein. The ATD consists of two globular lobes, which are speculated to contract from an "open" to a "closed" conformation following agonist binding. In the present study, we have...... 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...

Metabotropic glutamate receptor 5 contributes to inflammatory tongue pain via extracellular signal-regulated kinase signaling in the trigeminal spinal subnucleus caudalis and upper cervical spinal cord

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Liu Ming-Gang

2012-11-01

Full Text Available Abstract Background In the orofacial region, limited information is available concerning pathological tongue pain, such as inflammatory pain or neuropathic pain occurring in the tongue. Here, we tried for the first time to establish a novel animal model of inflammatory tongue pain in rats and to investigate the roles of metabotropic glutamate receptor 5 (mGluR5-extracellular signal-regulated kinase (ERK signaling in this process. Methods Complete Freund’s adjuvant (CFA was submucosally injected into the tongue to induce the inflammatory pain phenotype that was confirmed by behavioral testing. Expression of phosphorylated ERK (pERK and mGluR5 in the trigeminal subnucleus caudalis (Vc and upper cervical spinal cord (C1-C2 were detected with immunohistochemical staining and Western blotting. pERK inhibitor, a selective mGluR5 antagonist or agonist was continuously administered for 7 days via an intrathecal (i.t. route. Local inflammatory responses were verified by tongue histology. Results Submucosal injection of CFA into the tongue produced a long-lasting mechanical allodynia and heat hyperalgesia at the inflamed site, concomitant with an increase in the pERK immunoreactivity in the Vc and C1-C2. The distribution of pERK-IR cells was laminar specific, ipsilaterally dominant, somatotopically relevant, and rostrocaudally restricted. Western blot analysis also showed an enhanced activation of ERK in the Vc and C1-C2 following CFA injection. Continuous i.t. administration of the pERK inhibitor and a selective mGluR5 antagonist significantly depressed the mechanical allodynia and heat hyperalgesia in the CFA-injected tongue. In addition, the number of pERK-IR cells in ipsilateral Vc and C1-C2 was also decreased by both drugs. Moreover, continuous i.t. administration of a selective mGluR5 agonist induced mechanical allodynia in naive rats. Conclusions The present study constructed a new animal model of inflammatory tongue pain in rodents, and

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

A Temporally Distinct Role for Group I and Group II Metabotropic Glutamate Receptors in Object Recognition Memory

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Brown, Malcolm Watson; Warburton, Elizabeth Clea; Barker, Gareth Robert Isaac; Bashir, Zafar Iqbal

2006-01-01

Recognition memory, involving the ability to discriminate between a novel and familiar object, depends on the integrity of the perirhinal cortex (PRH). Glutamate, the main excitatory neurotransmitter in the cortex, is essential for many types of memory processes. Of the subtypes of glutamate receptor, metabotropic receptors (mGluRs) have received…

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

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Dindler, Anne; Blaabjerg, Morten; Kamand, Morad

2018-01-01

of pharmacological activation and inhibition of mGluR2/3 on proliferation, differentiation and viability of a human neural stem cell line. Immunofluorescence staining revealed the presence of mGluR2/3 receptors on both proliferating and differentiating stem cells, including cells differentiated into β-tubulin III....... Western blot analysis revealed that the active, dimeric form of mGluR2/3 was mainly present on the proliferating cells, which may explain our findings. The present study emphasises the importance of glutamate and mGluRs on regulation of human neural stem cells and suggests a significant role of mGluR2....../3 during cell proliferation. This article is protected by copyright. All rights reserved....

Viral-mediated knockdown of mGluR7 in the nucleus accumbens mediates excessive alcohol drinking and increased ethanol-elicited conditioned place preference in rats.

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Bahi, Amine

2013-10-01

Whether metabotropic glutamate 7 (mGluR7) -activation enhances or diminishes the reinforcing properties of psychostimulants remains unclear. We have previously shown that systemic mGluR7 activation reduced alcohol consumption and preference as well as locomotor-stimulating and rewarding properties of ethanol. In this study, we further examined the contribution of mGluR7 on the effect of ethanol within the nucleus accumbens (NAcc), a neural target for many drugs of abuse. Using short hairpin RNA (shRNA)-expressing lentiviral vectors (LV) to alter locally the activity of mGluR7 in male rats, we have shown that blocking mGluR7 expression increased ethanol consumption and preference in a two-bottle choice drinking paradigm with no effect either on saccharin or on quinine used for taste discrimination. In addition, mGluR7 knockdown increases preference for environments previously paired with low doses of ethanol in the conditioned place preference (CPP) test, as it shifted the dose-response curve for ethanol CPP to the left, indicating alterations in the rewarding effects of alcohol. More importantly, mGluR7 blockade in the dorsal striatum (DS) neither affected ethanol consumption nor ethanol-elicited CPP. These results show that levels of mGluR7 in the NAcc regulate responsiveness to alcohol. Taken together, these findings clearly demonstrate that mGluR7 signaling within the NAcc is a key modulator of functional responses to ethanol and offer an important target for regulating the addictive effects of alcohol.

Metabotropic glutamate receptor type 1 autoimmunity: Clinical features and treatment outcomes.

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Lopez-Chiriboga, A Sebastian; Komorowski, Lars; Kümpfel, Tania; Probst, Christian; Hinson, Shannon R; Pittock, Sean J; McKeon, Andrew

2016-03-15

To describe retrospectively the clinical associations of immunoglobulin G (IgG) targeting metabotropic glutamate receptor 1 (mGluR1-IgG). Specimens of 9 patients evaluated on a service basis in the Mayo Clinic Neuroimmunology Laboratory by tissue-based immunofluorescence assay (IFA) yielded a robust, synaptic immunostaining pattern consistent with mGluR1-IgG (serum, 9; CSF, 2 available). Transfected HEK293 cell-based assay (CBA) confirmed mGluR1 specificity in all 11 specimens. A further 2 patients were detected in Germany primarily by CBA. The median symptom onset age for the 11 patients was 58 years (range 33-81 years); 6 were male. All 9 Mayo Clinic patients had subacute onset of cerebellar ataxia, 4 had dysgeusia, 1 had psychiatric symptoms, and 1 had cognitive impairment. All were evaluated for malignancy, but only 1 was affected (cutaneous T-cell lymphoma). One developed ataxia post-herpes zoster infection. Head MRIs were generally atrophic or normal-appearing, and CSF was inflammatory in just 1 of 5 tested, though mGluR1-IgG was detected in both specimens submitted. Five patients improved (attributable to immunotherapy in 4, spontaneously in 1), 3 stabilized (attributable to immunotherapy in 2, cancer therapy in 1), and 1 progressively declined (untreated). The 2 German patients had ataxia, but fulfilled multiple sclerosis diagnostic criteria (1 relapsing-remitting, 1 progressive). However, both had histories of hematologic malignancy (acute lymphocytic leukemia and mantle cell lymphoma), and had mGluR1-IgG detected in serum by CBA (weakly positive on tissue-based IFA). mGluR1 autoimmunity represents a treatable form of cerebellar ataxia. Dysgeusia may be a diagnostic clue. Paraneoplastic, parainfectious, or idiopathic causes may occur. © 2016 American Academy of Neurology.

Astrocytes Control Neuronal Excitability in the Nucleus Accumbens

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Tommaso Fellin

2007-01-01

Full Text Available Though accumulating evidence shows that the metabotropic glutamate receptor 5 (mGluR5 mediates some of the actions of extracellular glutamate after cocaine use, the cellular events underlying this action are poorly understood. In this review, we will discuss recent results showing that mGluR5 receptors are key regulators of astrocyte activity. Synaptic release of glutamate activates mGluR5 expressed in perisynaptic astrocytes and generates intense Ca2+ signaling in these cells. Ca2+ oscillations, in turn, trigger the release from astrocytes of the gliotransmitter glutamate, which modulates neuronal excitability by activating NMDA receptors. By integrating these results with the most recent evidence demonstrating the importance of astrocytes in the regulation of neuronal excitability, we propose that astrocytes are involved in mediating some of the mGluR5-dependent drug-induced behaviors.

Selective and interactive effects of D2 receptor antagonism and positive allosteric mGluR4 modulation on waiting impulsivity.

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Isherwood, Sarah N; Robbins, Trevor W; Nicholson, Janet R; Dalley, Jeffrey W; Pekcec, Anton

2017-09-01

Metabotropic glutamate receptor 4 (mGluR4) and dopamine D 2 receptors are specifically expressed within the indirect pathway neurons of the striato-pallidal-subthalamic pathway. This unique expression profile suggests that mGluR4 and D 2 receptors may play a cooperative role in the regulation and inhibitory control of behaviour. We investigated this possibility by testing the effects of a functionally-characterised positive allosteric mGluR4 modulator, 4-((E)-styryl)-pyrimidin-2-ylamine (Cpd11), both alone and in combination with the D 2 receptor antagonist eticlopride, on two distinct forms of impulsivity. Rats were trained on the five-choice serial reaction time task (5-CSRTT) of sustained visual attention and segregated according to low, mid, and high levels of motor impulsivity (LI, MI and HI, respectively), with unscreened rats used as an additional control group. A separate group of rats was trained on a delay discounting task (DDT) to assess choice impulsivity. Systemic administration of Cpd11 dose-dependently increased motor impulsivity and impaired attentional accuracy on the 5-CSRTT in all groups tested. Eticlopride selectively attenuated the increase in impulsivity induced by Cpd11, but not the accompanying attentional impairment, at doses that had no significant effect on behavioural performance when administered alone. Cpd11 also decreased choice impulsivity on the DDT (i.e. increased preference for the large, delayed reward) and decreased locomotor activity. These findings demonstrate that mGluR4s, in conjunction with D 2 receptors, affect motor- and choice-based measures of impulsivity, and therefore may be novel targets to modulate impulsive behaviour associated with a number of neuropsychiatric syndromes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

In Silico Analysis of the Association Relationship between Neuroprotection and Flavors of Traditional Chinese Medicine Based on the mGluRs

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Qiao, Liansheng; Chen, Yankun; Zhao, Bowen; Gu, Yu; Huo, Xiaoqian; Zhang, Yanling; Li, Gongyu

2018-01-01

The metabotropic glutamate receptors (mGluRs) are known as both synaptic receptors and taste receptors. This feature is highly similar to the Property and Flavor theory of Traditional Chinese medicine (TCM), which has the pharmacological effect and flavor. In this study, six ligand based pharmacophore (LBP) models, seven homology modeling models, and fourteen molecular docking models of mGluRs were built based on orthosteric and allosteric sites to screening potential compounds from Traditional Chinese Medicine Database (TCMD). Based on the Pharmacopoeia of the People’s Republic of China, TCMs of compounds and their flavors were traced and listed. According to the tracing result, we found that the TCMs of the compounds which bound to orthosteric sites of mGluRs are highly correlated to a sweet flavor, while the allosteric site corresponds to a bitter flavor. Meanwhile, the pharmacological effects of TCMs with highly frequent flavors were further analyzed. We found that those TCMs play a neuroprotective role through the efficiencies of detumescence, promoting blood circulation, analgesic effect, and so on. This study provides a guide for developing new neuroprotective drugs from TCMs which target mGluRs. Moreover, it is the first study to present a novel approach to discuss the association relationship between flavor and the neuroprotective mechanism of TCM based on mGluRs. PMID:29320397

Metabotropic Glutamate Receptor 7 Modulates the Rewarding Effects of Cocaine in Rats: Involvement of a Ventral Pallidal GABAergic Mechanism

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Li, Xia; Li, Jie; Peng, Xiao-Qing; Spiller, Krista; Gardner, Eliot L; Xi, Zheng-Xiong

2013-01-01

The metabotropic glutamate receptor 7 (mGluR7) has received much attention as a potential target for the treatment of epilepsy, major depression, and anxiety. In this study, we investigated the possible involvement of mGluR7 in cocaine reward in animal models of drug addiction. Pretreatment with the selective mGluR7 allosteric agonist N,N’-dibenzyhydryl-ethane-1,2-diamine dihydrochloride (AMN082; 1-20 mg/kg, i.p.) dose-dependently inhibited cocaine-induced enhancement of electrical brain-stimulation reward and intravenous cocaine self-administration under both fixed-ratio and progressive-ratio reinforcement conditions, but failed to alter either basal or cocaine-enhanced locomotion or oral sucrose self-administration, suggesting a specific inhibition of cocaine reward. Microinjections of AMN082 (1–5 μg/μl per side) into the nucleus accumbens (NAc) or ventral pallidum (VP), but not dorsal striatum, also inhibited cocaine self-administration in a dose-dependent manner. Intra-NAc or intra-VP co-administration of 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP, 5 μg/μl per side), a selective mGluR7 allosteric antagonist, significantly blocked AMN082’s action, suggesting an effect mediated by mGluR7 in these brain regions. In vivo microdialysis demonstrated that cocaine (10 mg/kg, i.p.) priming significantly elevated extracellular DA in the NAc or VP, while decreasing extracellular GABA in VP (but not in NAc). AMN082 pretreatment selectively blocked cocaine-induced changes in extracellular GABA, but not in DA, in both naive rats and cocaine self-administration rats. These data suggest: (1) mGluR7 is critically involved in cocaine’s acute reinforcement; (2) GABA-, but not DA-, dependent mechanisms in the ventral striatopallidal pathway appear to underlie AMN082’s actions; and (3) AMN082 or other mGluR7-selective agonists may be useful in the treatment of cocaine addiction. PMID:19158667

Modulation of seizure activity in mice by metabotropic glutamate receptor ligands

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Dalby, Nils Ole; Thomsen, C

1996-01-01

The anticonvulsant properties of ligands at metabotropic glutamate receptors (mGluRs) were examined in different seizure models by use of intracerebroventricular infusion. The mGluR1a antagonist/mGluR2 agonist, (S)-4-carboxy-3-hydroxyphenylglycine [(S)-4C3HPG] dose-dependently antagonized...... pentylenetetrazol- and methyl-6,7-dimethoxy-4-ethyl-beta-carboline-2-carboxylate (DMCM)-induced clonic convulsions in mice with ED50 values of 400 and 180 nmol/mice, respectively. A modest increase in electrical seizure threshold was observed in mice injected with (S)-4C3HPG. No effect on seizures induced...... by systemic administration of N-methyl-D-aspartate was observed by prior intracerebroventricular infusion of (S)-4C3HPG. The more selective (but less potent) mGluR1a antagonist, (S)-4-carboxyphenylglycine, was a weak anticonvulsant in similar seizure models with the exception of convulsions induced...

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

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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...

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.

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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.

Protection but maintained dysfunction of nigral dopaminergic nerve cell bodies and striatal dopaminergic terminals in MPTP-lesioned mice after acute treatment with the mGluR5 antagonist MPEP.

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Aguirre, Jose A; Kehr, Jan; Yoshitake, Takashi; Liu, Fang-Ling; Rivera, Alicia; Fernandez-Espinola, Sergio; Andbjer, Beth; Leo, Giuseppina; Medhurst, Andrew D; Agnati, Luigi F; Fuxe, Kjell

2005-02-08

The mGluR5 antagonist MPEP was used to study the role of mGluR5 in MPTP-induced injury of the nigrostriatal DA neurons. The findings indicate that acute blockade of mGluR5 may result in neuroprotective actions against MPTP neurotoxicity on nigral DA cell bodies and striatal DA terminals using stereological analysis of TH immunoreactivity and microdensitometry. Biochemical analysis showed no restoration of DA levels and metabolism indicating a maintained reduction of DA transmission.

Night blindness and abnormal cone electroretinogram ON responses in patients with mutations in the GRM6 gene encoding mGluR6

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Dryja, Thaddeus P.; McGee, Terri L.; Berson, Eliot L.; Fishman, Gerald A.; Sandberg, Michael A.; Alexander, Kenneth R.; Derlacki, Deborah J.; Rajagopalan, Aruna S.

2005-01-01

We report three unrelated patients with mutations in the GRM6 gene that normally encodes the glutamate receptor mGluR6. This neurotransmitter receptor has been shown previously to be present only in the synapses of the ON bipolar cell dendrites, and it mediates synaptic transmission from rod and cone photoreceptors to this type of second-order neuron. Despite the synaptic defect, best visual acuities were normal or only moderately reduced (20/15 to 20/40). The patients were night blind from an early age, and when maximally dark-adapted, they could perceive lights only with an intensity equal to or slightly dimmer than that normally detected by the cone system (i.e., 2-3 log units above normal). Electroretinograms (ERGs) in response to single brief flashes of light had clearly detectable a-waves, which are derived from photoreceptors, and greatly reduced b-waves, which are derived from the second-order inner retinal neurons. ERGs in response to sawtooth flickering light indicated a markedly reduced ON response and a nearly normal OFF response. There was no subjective delay in the perception of suddenly appearing white vs. black objects on a gray background. These patients exemplify a previously unrecognized, autosomal recessive form of congenital night blindness associated with a negative ERG waveform. PMID:15781871

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

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Yamasaki, Tomoteru; Fujinaga, Masayuki; Maeda, Jun; Kawamura, Kazunori; Yui, Joji; Hatori, Akiko; Yoshida, Yuichiro; Nagai, Yuji; Tokunaga, Masaki; Higuchi, Makoto; Suhara, Tetsuya; Fukumura, Toshimitsu; Zhang, Ming-Rong

2012-04-01

In this study, we evaluate the utility of 4-[(18)F]fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide ([(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 [(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(T)) was detected in the cerebellum (V(T) = 11.5). [(18)F]FITM has an excellent profile as a PET ligand for mGluR1 imaging. PET with [(18)F]FITM may prove useful for determining the regional distribution and density of mGluR1 and the mGluR1 occupancy of drugs in human brains.

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...

Risk-Conferring Glutamatergic Genes and Brain Glutamate Plus Glutamine in Schizophrenia

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Juan R. Bustillo

2017-06-01

Full Text Available BackgroundThe proton magnetic resonance spectroscopy (1H-MRS signals from glutamate (or the combined glutamate and glutamine signal—Glx have been found to be greater in various brain regions in people with schizophrenia. Recently, the Psychiatric Genetics Consortium reported that several common single-nucleotide polymorphisms (SNPs in glutamate-related genes confer increased risk of schizophrenia. Here, we examined the relationship between presence of these risk polymorphisms and brain Glx levels in schizophrenia.Methods1H-MRS imaging data from an axial, supraventricular tissue slab were acquired in 56 schizophrenia patients and 67 healthy subjects. Glx was measured in gray matter (GM and white matter (WM regions. The genetic data included six polymorphisms genotyped across an Illumina 5M SNP array. Only three of six glutamate as well as calcium-related SNPs were available for examination. These included three glutamate-related polymorphisms (rs10520163 in CLCN3, rs12704290 in GRM3, and rs12325245 in SLC38A7, and three calcium signaling polymorphisms (rs1339227 in RIMS1, rs7893279 in CACNB2, and rs2007044 in CACNA1C. Summary risk scores for the three glutamate and the three calcium polymorphisms were calculated.ResultsGlx levels in GM positively correlated with glutamate-related genetic risk score but only in younger (≤36 years schizophrenia patients (p = 0.01. Glx levels did not correlate with calcium risk scores. Glx was higher in the schizophrenia group compared to levels in controls in GM and WM regardless of age (p < 0.001.ConclusionElevations in brain Glx are in part, related to common allelic variants of glutamate-related genes known to increase the risk for schizophrenia. Since the glutamate risk scores did not differ between groups, some other genetic or environmental factors likely interact with the variability in glutamate-related risk SNPs to contribute to an increase in brain Glx early in the illness.

Glutamic acid promotes monacolin K production and monacolin K biosynthetic gene cluster expression in Monascus.

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Zhang, Chan; Liang, Jian; Yang, Le; Chai, Shiyuan; Zhang, Chenxi; Sun, Baoguo; Wang, Chengtao

2017-12-01

This study investigated the effects of glutamic acid on production of monacolin K and expression of the monacolin K biosynthetic gene cluster. When Monascus M1 was grown in glutamic medium instead of in the original medium, monacolin K production increased from 48.4 to 215.4 mg l -1 , monacolin K production increased by 3.5 times. Glutamic acid enhanced monacolin K production by upregulating the expression of mokB-mokI; on day 8, the expression level of mokA tended to decrease by Reverse Transcription-polymerase Chain Reaction. Our findings demonstrated that mokA was not a key gene responsible for the quantity of monacolin K production in the presence of glutamic acid. Observation of Monascus mycelium morphology using Scanning Electron Microscope showed glutamic acid significantly increased the content of Monascus mycelium, altered the permeability of Monascus mycelium, enhanced secretion of monacolin K from the cell, and reduced the monacolin K content in Monascus mycelium, thereby enhancing monacolin K production.

The selective metabotropic glutamate receptor 5 antagonist mavoglurant (AFQ056) reduces the incidence of reflux episodes in dogs and patients with moderate to severe gastroesophageal reflux disease.

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Rouzade-Dominguez, M-L; Pezous, N; David, O J; Tutuian, R; Bruley des Varannes, S; Tack, J; Malfertheiner, P; Allescher, H-D; Ufer, M; Rühl, A

2017-08-01

Transient lower esophageal sphincter relaxations (TLESRs) induced by gastric distension are modulated by the metabotropic glutamate receptor 5 (mGluR5) that influences the vagal reflex loop. We therefore aimed to examine the effects of the selective mGluR5 antagonist mavoglurant (AFQ056) on the number of TLESRs in dogs and reflux episodes in patients with gastroesophageal reflux disease (GERD). In a dog model, the number of meal-induced TLESRs was determined after intravenous (0.03, 0.1, 0.3, and 1 mg kg -1 ) and oral (1, 3, and 10 mg kg -1 ) doses of mavoglurant with reference to vehicle. In a multicenter, randomized, double-blind, placebo-controlled, three-period crossover study, the incidence of meal-induced reflux episodes was assessed by esophageal impedance monitoring after single, oral doses of mavoglurant (50 and 400 mg) or baclofen (40 mg) in 30 patients with moderate to severe GERD. In dogs, mavoglurant reduced the number of TLESRs after intravenous and oral administration. In patients with GERD, the incidence of postprandial reflux episodes was significantly lower at a dose of 400 mg mavoglurant (-37.5% ; 90% confidence interval [CI]: -57.8, -17.2), whereas there was no significant difference at 50 mg of mavoglurant compared to placebo. A significantly lower incidence of reflux episodes was also noted with the active comparator baclofen (-50.3%; 90% CI: -66.2, -34.3), thereby validating this study. These data suggest a potential clinical benefit of mGluR5 antagonists such as mavoglurant in patients with GERD, particularly in those with persisting symptoms despite treatment with proton pump inhibitors. © 2017 John Wiley & Sons Ltd.

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

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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

Characterization of age/sex and the regional distribution of mGluR5 availability in the healthy human brain measured by high-resolution [11C]ABP688 PET

International Nuclear Information System (INIS)

DuBois, Jonathan M.; Porras-Betancourt, Manuel; Massarweh, Gassan; Soucy, Jean-Paul; Kobayashi, Eliane; Rousset, Olivier G.; Rowley, Jared; Reader, Andrew J.; Labbe, Aurelie; Rosa-Neto, Pedro

2016-01-01

Metabotropic glutamate receptor type 5 (mGluR5) is a G protein-coupled receptor that has been implicated in several psychiatric and neurological diseases. The radiopharmaceutical [ 11 C]ABP688 allows for in vivo quantification of mGluR5 availability using positron emission tomography (PET). In this study, we aimed to detail the regional distribution of [ 11 C]ABP688 binding potential (BP ND ) and the existence of age/sex effects in healthy individuals. Thirty-one healthy individuals aged 20 to 77 years (men, n = 18, 45.3 ± 18.2 years; females, n = 13, 41.5 ± 19.6 years) underwent imaging with [ 11 C]ABP688 using the high-resolution research tomograph (HRRT). We developed an advanced partial volume correction (PVC) method using surface-based analysis in order to accurately estimate the regional variation of radioactivity. BP ND was calculated using the simplified reference tissue model, with the cerebellum as the reference region. Surface-based and volume-based analyses were performed for 39 cortical and subcortical regions of interest per hemisphere. We found the highest [ 11 C]ABP688 BP ND in the lateral prefrontal and anterior cingulate cortices. The lowest [ 11 C]ABP688 BP ND was observed in the pre- and post-central gyri as well as the occipital lobes and the thalami. No sex effect was observed. Associations between age and [ 11 C]ABP688 BP ND without PVC were observed in the right amygdala and left putamen, but were not significant after multiple comparisons correction. The present results highlight complexities underlying brain adaptations during the aging process, and support the notion that certain aspects of neurotransmission remain stable during the adult life span. (orig.)

Altered expression of genes involved in GABAergic transmission and neuromodulation of granule cell activity in the cerebellum of schizophrenia patients.

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Bullock, W Michael; Cardon, Karen; Bustillo, Juan; Roberts, Rosalinda C; Perrone-Bizzozero, Nora I

2008-12-01

Deficits in gamma-aminobutyric acid (GABA) signaling have been described in the prefrontal cortex, limbic system, and cerebellum in individuals with schizophrenia. The purpose of the present study was to further investigate cerebellar gene expression alterations as they relate to decreases in GABAergic transmission by examining the expression of GABAergic markers, N-methyl-d-aspartic-acid (NMDA) receptor subunits, and cerebellum neuromodulators in individuals with schizophrenia. Subjects were postmortem men with a diagnosis of schizophrenia (N=13) and a postmortem interval-matched non-psychiatric male comparison group (N=13). The authors utilized real-time-quantitative polymerase chain reaction (PCR) to measure mRNA levels of the following GABAergic markers: glutamic acid decarboxylase (GAD) 65 and 67; GABA plasma membrane transporter-1 (GAT-1); GABA type A (GABA(A)) receptor subunits alpha(6), beta(3), and delta; and parvalbumin. In addition, real-time-quantitative PCR was utilized to assess mRNA levels of the NMDA receptor (NR) subunits NR1, NR2-A, NR2-B, NR2-C, and NR2-D as well as the cerebellar neuromodulators glutamate receptor (GluR)-6, kainate-preferring glutamate receptor subunit-2 (KA2), metabotropic glutamate receptor (mGluR)-2 and mGluR3, and neuronal nitric oxide synthase. Measurements for mRNA levels were determined using lateral cerebellar hemisphere tissue from both schizophrenia and comparison subjects. Schizophrenia subjects showed significant decreases in mRNA levels of GAD(67), GAD(65), GAT-1, mGluR2, and neuronal nitric oxide synthase. Increases in GABA(A)-alpha(6 )and GABA(A)-delta as well as GluR6 and KA2 were also observed. Medication effects on the expression of the same genes were examined in rats treated with either haloperidol (Sprague-Dawley rats [N=16]) or clozapine (Long-Evans rats [N=20]). Both haloperidol and clozapine increased the levels of GAD(67) in the cerebellum and altered the expression of other cerebellar mRNAs. These

Characterization of age/sex and the regional distribution of mGluR5 availability in the healthy human brain measured by high-resolution [{sup 11}C]ABP688 PET

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DuBois, Jonathan M.; Porras-Betancourt, Manuel; Massarweh, Gassan; Soucy, Jean-Paul; Kobayashi, Eliane [McGill University, Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec (Canada); Rousset, Olivier G. [Johns Hopkins University, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Rowley, Jared [McGill University, Translational Neuroimaging Laboratory, McGill Center for Studies in Aging, Douglas Mental Health University Institute, Montreal (Canada); Reader, Andrew J. [McGill University, PET Unit, McConnell Brain Imaging Center, Montreal Neurological Institute, Montreal (Canada); King' s College London, St. Thomas' Hospital, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Labbe, Aurelie [McGill University, Department of Epidemiology, Biostatistics and Occupational health, Montreal (Canada); Douglas Mental Health University Institute / Douglas Institut Universitaire en Sante Mentale, Department of Psychiatry, Montreal (Canada); Rosa-Neto, Pedro [McGill University, Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec (Canada); McGill University, Translational Neuroimaging Laboratory, McGill Center for Studies in Aging, Douglas Mental Health University Institute, Montreal (Canada)

2016-01-15

Metabotropic glutamate receptor type 5 (mGluR5) is a G protein-coupled receptor that has been implicated in several psychiatric and neurological diseases. The radiopharmaceutical [{sup 11}C]ABP688 allows for in vivo quantification of mGluR5 availability using positron emission tomography (PET). In this study, we aimed to detail the regional distribution of [{sup 11}C]ABP688 binding potential (BP{sub ND}) and the existence of age/sex effects in healthy individuals. Thirty-one healthy individuals aged 20 to 77 years (men, n = 18, 45.3 ± 18.2 years; females, n = 13, 41.5 ± 19.6 years) underwent imaging with [{sup 11}C]ABP688 using the high-resolution research tomograph (HRRT). We developed an advanced partial volume correction (PVC) method using surface-based analysis in order to accurately estimate the regional variation of radioactivity. BP{sub ND} was calculated using the simplified reference tissue model, with the cerebellum as the reference region. Surface-based and volume-based analyses were performed for 39 cortical and subcortical regions of interest per hemisphere. We found the highest [{sup 11}C]ABP688 BP{sub ND} in the lateral prefrontal and anterior cingulate cortices. The lowest [{sup 11}C]ABP688 BP{sub ND} was observed in the pre- and post-central gyri as well as the occipital lobes and the thalami. No sex effect was observed. Associations between age and [{sup 11}C]ABP688 BP{sub ND} without PVC were observed in the right amygdala and left putamen, but were not significant after multiple comparisons correction. The present results highlight complexities underlying brain adaptations during the aging process, and support the notion that certain aspects of neurotransmission remain stable during the adult life span. (orig.)

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

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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

Exercise induced upregulation of glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modifier subunit gene expression in Thoroughbred horses

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Jeong-Woong Park

2017-05-01

Full Text Available Objective This study was performed to reveal the molecular structure and expression patterns of horse glutamate-cysteine ligase catalytic subunit (GCLC and glutamate-cysteine ligase modifier subunit (GCLM genes whose products form glutamate cysteine ligase, which were identified as differentially expressed genes in the previous study. Methods We performed bioinformatics analyses, and gene expression assay with quantitative polymerase chain reaction (qPCR for horse GCLC and GCLM genes in muscle and blood leukocytes of Thoroughbred horses Results Expression of GCLC showed the same pattern in both blood and muscle tissues after exercise. Expression of GCLC increased in the muscle and blood of Thoroughbreds, suggesting a tissue-specific regulatory mechanism for the expression of GCLC. In addition, expression of the GCLM gene increased after exercise in both the blood and muscle of Thoroughbreds. Conclusion We established the expression patterns of GCLC and GCLM in the skeletal muscle and blood of Thoroughbred horses in response to exercise. Further study is now warranted to uncover the functional importance of these genes in exercise and recovery in racehorses.

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

DEFF Research Database (Denmark)

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

2005-01-01

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

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

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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.

Δ(1-pyrroline-5-carboxylate/glutamate biogenesis is required for fungal virulence and sporulation.

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Ziting Yao

Full Text Available Proline dehydrogenase (Prodh and Δ(1-pyrroline-5-carboxylate dehydrogenase (P5Cdh are two key enzymes in the cellular biogenesis of glutamate. Recombinant Prodh and P5Cdh proteins of the chestnut blight fungus Cryphonectria parasitica were investigated and showed activity in in vitro assays. Additionally, the C. parasitica Prodh and P5Cdh genes were able to complement the Saccharomyces cerevisiae put1 and put2 null mutants, respectively, to allow these proline auxotrophic yeast mutants to grow on media with proline as the sole source of nitrogen. Deletion of the Prodh gene in C. parasitica resulted in hypovirulence and a lower level of sporulation, whereas deletion of P5Cdh resulted in hypovirulence though no effect on sporulation; both Δprodh and Δp5cdh mutants were unable to grow on minimal medium with proline as the sole nitrogen source. In a wild-type strain, the intracellular level of proline and the activity of Prodh and P5Cdh increased after supplementation of exogenous proline, though the intracellular Δ(1-pyrroline-5-carboxylate (P5C content remained unchanged. Prodh and P5Cdh were both transcriptionally down-regulated in cells infected with hypovirus. The disruption of other genes with products involved in the conversion of arginine to ornithine, ornithine and glutamate to P5C, and P5C to proline in the cytosol did not appear to affect virulence; however, asexual sporulation was reduced in the Δpro1 and Δpro2 mutants. Taken together, our results showed that Prodh, P5Cdh and related mitochondrial functions are essential for virulence and that proline/glutamate pathway components may represent down-stream targets of hypovirus regulation in C. parasitica.

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.

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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

A missense mutation in Grm6 reduces but does not eliminate mGluR6 expression or rod depolarizing bipolar cell function.

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Peachey, Neal S; Hasan, Nazarul; FitzMaurice, Bernard; Burrill, Samantha; Pangeni, Gobinda; Karst, Son Yong; Reinholdt, Laura; Berry, Melissa L; Strobel, Marge; Gregg, Ronald G; McCall, Maureen A; Chang, Bo

2017-08-01

GRM6 encodes the metabotropic glutamate receptor 6 (mGluR6) used by retinal depolarizing bipolar cells (DBCs). Mutations in GRM6 lead to DBC dysfunction and underlie the human condition autosomal recessive complete congenital stationary night blindness. Mouse mutants for Grm6 are important models for this condition. Here we report a new Grm6 mutant, identified in an electroretinogram (ERG) screen of mice maintained at The Jackson Laboratory. The Grm6 nob8 mouse has a reduced-amplitude b-wave component of the ERG, which reflects light-evoked DBC activity. Sequencing identified a missense mutation that converts a highly conserved methionine within the ligand binding domain to leucine (p.Met66Leu). Consistent with prior studies of Grm6 mutant mice, the laminar size and structure in the Grm6 nob8 retina were comparable to control. The Grm6 nob8 phenotype is distinguished from other Grm6 mutants that carry a null allele by a reduced but not absent ERG b-wave, decreased but present expression of mGluR6 at DBC dendritic tips, and mislocalization of mGluR6 to DBC somas. Consistent with a reduced but not absent b-wave, there were a subset of retinal ganglion cells whose responses to light onset have times to peak within the range of those in control retinas. These data indicate that the p.Met66Leu mutant mGluR6 is trafficked less than control. However, the mGluR6 that is localized to the DBC dendritic tips is able to initiate DBC signal transduction. The Grm6 nob8 mouse extends the Grm6 allelic series and will be useful for elucidating the role of mGluR6 in DBC signal transduction and in human disease. NEW & NOTEWORTHY This article describes a mouse model of the human disease complete congenital stationary night blindness in which the mutation reduces but does not eliminate GRM6 expression and bipolar cell function, a distinct phenotype from that seen in other Grm6 mouse models.

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.

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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.

Peripheral Glutamate Receptors Are Required for Hyperalgesia Induced by Capsaicin

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You-Hong Jin

2012-01-01

Full Text Available Transient receptor potential vanilloid1 (TRPV1 and glutamate receptors (GluRs are located in small diameter primary afferent neurons (nociceptors, and it was speculated that glutamate released in the peripheral tissue in response to activation of TRPV1 might activate nociceptors retrogradely. But, it was not clear which types of GluRs are functioning in the nociceptive sensory transmission. In the present study, we examined the c-Fos expression in spinal cord dorsal horn following injection of drugs associated with glutamate receptors with/without capsaicin into the hindpaw. The subcutaneous injection of capsaicin or glutamate remarkably evoked c-Fos expression in ipsilateral sides of spinal cord dorsal horn. This capsaicin evoked increase of c-Fos expression was significantly prevented by concomitant administration of MK801, CNQX, and CPCCOEt. On the other hand, there were not any significant changes in coinjection of capsaicin and MCCG or MSOP. These results reveal that the activation of iGluRs and group I mGluR in peripheral afferent nerves play an important role in mechanisms whereby capsaicin evokes/maintains nociceptive responses.

Interactions between estrogen receptors and metabotropic glutamate receptors and their impact on drug addiction in females.

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Tonn Eisinger, Katherine R; Gross, Kellie S; Head, Brian P; Mermelstein, Paul G

2018-03-10

Estrogen receptors α and β (ERα and ERβ) have a unique relationship with metabotropic glutamate receptors (mGluRs) in the female rodent brain such that estradiol is able to recruit intracellular G-protein signaling cascades to influence neuronal physiology, structure, and ultimately behavior. While this association between ERs and mGluRs exists in many cell types and brain regions, its effects are perhaps most striking in the nucleus accumbens (NAc). This review will discuss the original characterization of ER/mGluR signaling and how estradiol activity in the NAc confers increased sensitivity to drugs of abuse in females through this mechanism. Copyright © 2018 Elsevier Inc. All rights reserved.

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

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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.

Sequence and expression pattern of a novel human orphan G-protein-coupled receptor, GPRC5B, a family C receptor with a short amino-terminal domain

DEFF Research Database (Denmark)

Bräuner-Osborne, Hans; Krogsgaard-Larsen, P

2000-01-01

Query of GenBank with the amino acid sequence of human metabotropic glutamate receptor subtype 2 (mGluR2) identified a predicted gene product of unknown function on BAC clone CIT987SK-A-69G12 (located on chromosome band 16p12) as a homologous protein. The transcript, entitled GPRC5B, was cloned f...... from an expressed sequence tag clone that contained the entire open reading frame of the transcript encoding a protein of 395 amino acids. Analysis of the protein sequence reveal that GPRC5B contains a signal peptide and seven transmembrane alpha-helices, which is a hallmark of G...

Knocking down metabotropic glutamate receptor 1 improves survival and disease progression in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

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Milanese, Marco; Giribaldi, Francesco; Melone, Marcello; Bonifacino, Tiziana; Musante, Ilaria; Carminati, Enrico; Rossi, Pia I A; Vergani, Laura; Voci, Adriana; Conti, Fiorenzo; Puliti, Aldamaria; Bonanno, Giambattista

2014-04-01

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease reflecting degeneration of upper and lower motoneurons (MNs). The cause of ALS and the mechanisms of neuronal death are still largely obscure, thus impairing the establishment of efficacious therapies. Glutamate (Glu)-mediated excitotoxicity plays a major role in MN degeneration in ALS. We recently demonstrated that the activation of Group I metabotropic Glu autoreceptors, belonging to both type 1 and type 5 receptors (mGluR1 and mGluR5), at glutamatergic spinal cord nerve terminals, produces excessive Glu release in mice over-expressing human superoxide-dismutase carrying the G93A point mutation (SOD1(G93A)), a widely used animal model of human ALS. To establish whether these receptors are implicated in ALS, we generated mice expressing half dosage of mGluR1 in the SOD1(G93A) background (SOD1(G93A)Grm1(crv4/+)), by crossing the SOD1(G93A) mutant mouse with the Grm1(crv4/+) mouse, lacking mGluR1 because of a spontaneous recessive mutation. SOD1(G93A)Grm1(crv4/+) mice showed prolonged survival probability, delayed pathology onset, slower disease progression and improved motor performances compared to SOD1(G93A) mice. These effects were associated to reduction of mGluR5 expression, enhanced number of MNs, decreased astrocyte and microglia activation, normalization of metallothionein and catalase mRNA expression, reduced mitochondrial damage, and decrease of abnormal Glu release in spinal cord of SOD1(G93A)Grm1(crv4/+)compared to SOD1(G93A) mice. These results demonstrate that a lower constitutive level of mGluR1 has a significant positive impact on mice with experimental ALS, thus providing the rationale for future pharmacological approaches to ALS by selectively blocking Group I metabotropic Glu receptors. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical lesioning and glutamate administration reveal a major role for the nucleus tractus solitarius in the cardiac-somatic reflex in rats.

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Liu, X-H; Sun, N; Du, J-Q; Tang, J-S; Han, M; Zhu, J-X; Huo, F-Q

2012-04-05

Many patients suffer from secondary muscle hyperalgesia after experiencing angina pectoris. In this study, we examined the role of the nucleus tractus solitarius (NTS) and glutamate receptors in modulating cardiac-evoked muscle hyperalgesia induced by pericardial capsaicin, which was monitored by recording electromyogram (EMG) activity from the spinotrapezius muscle in the anesthetized rat. Unilateral chemical lesioning of the commissural NTS with the neurotoxin ibotenic acid significantly depressed the cardiac-somatic reflex; the EMG responses decreased to 56.4 ± 6.9% of that of the controls (5 of 5). Microinjection of the excitatory amino acid glutamate, at 10, 20, and 50 nmol, into the commissural NTS increased the EMG response, in a dose-dependent manner, to 116.9 ± 4.9%, 143.9 ± 10.2%, and 214.2 ± 15.8% (n=8), respectively, of that of the controls. In contrast, microinjection of the N-methyl-D-aspartate (NMDA) receptor antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo [a, d]-cyclohepten-5,10-imine maleate (MK-801) at 4 and 6 nmol, decreased the EMG response to 45.2 ± 10.6% and 36.8 ± 14.3%, respectively, of that of the controls (n=8 for each dose). Similarly, the metabotropic glutamate receptor (mGluR) antagonist (RS)-a-methyl-4-carboxyphenylglycine (MCPG), at 2.5 and 5 nmol, decreased the EMG response to 65.2 ± 16.3% and 57.0 ± 4.2%, respectively, of that of the controls. When a combination of MK-801 and MCPG was administrated, the EMG response further decreased to 22.5 ± 13.2% (n=6) of that of the controls. However, administration of a non-NMDA receptor antagonist 6, 7-dinitroquinoxaline-2, 3-dione (DNQX), at 2 and 5 nmol, had no effect on the EMG response. These results suggest that the NTS is involved in the facilitation of the cardiac-somatic reflex, and that the NMDA receptor and mGluRs play an important role in mediating this effect. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

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

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Ana ePalomino

2014-03-01

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

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

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Santokh Gill

2010-05-01

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

Anti-Cancer Effect of Metabotropic Glutamate Receptor 1 Inhibition in Human Glioma U87 Cells: Involvement of PI3K/Akt/mTOR Pathway

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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.

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

International Nuclear Information System (INIS)

Park, Eunkyung; Sullivan, Jenna M.; Planeta, Beata; Gallezot, Jean-Dominique; Lim, Keunpoong; Lin, Shu-Fei; Ropchan, Jim; Huang, Yiyun; Carson, Richard E.; McCarthy, Timothy J.; Ding, Yu-Shin; Morris, Evan D.; Williams, Wendol A.

2015-01-01

[ 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 [ 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 [ 18 F]FPEB. Four methods were used to estimate volume of distribution (V T ): equilibrium analysis (EQ) using arterial (EQ A ) or venous input data (EQ V ), MA1, and a two-tissue compartment model (2 T). Binding potential (BP 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 T and BP ND were calculated for each method. Venous blood measurements (C V ) were compared with arterial input (C A ) to examine their usability in EQ analysis. Regional V T estimated by the four methods displayed a high degree of agreement (r 2 ranging from 0.83 to 0.99 among the methods), although EQ A and EQ V overestimated V T by a mean of 9 % and 7 %, respectively, compared to 2 T. Mean values of aTRV of V T were 11 % by EQ A , 12 % by EQ V , 14 % by MA1 and 14 % by 2 T. Regional BP ND also agreed well among the methods and mean aTRV of BP ND was 8 - 12 % (CWM) and 7 - 9 % (CGM). Venous and arterial blood concentrations of [ 18 F]FPEB were well matched during equilibrium (C V = 1.01 . C A , r 2 = 0.95). [ 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, [ 18 F]FPEB is an excellent PET imaging tracer for mGluR5 in humans. (orig.)

Control of Amygdala Circuits by 5-HT Neurons via 5-HT and Glutamate Cotransmission.

Science.gov (United States)

Sengupta, Ayesha; Bocchio, Marco; Bannerman, David M; Sharp, Trevor; Capogna, Marco

2017-02-15

The serotonin (5-HT) system and the amygdala are key regulators of emotional behavior. Several lines of evidence suggest that 5-HT transmission in the amygdala is implicated in the susceptibility and drug treatment of mood disorders. Therefore, elucidating the physiological mechanisms through which midbrain 5-HT neurons modulate amygdala circuits could be pivotal in understanding emotional regulation in health and disease. To shed light on these mechanisms, we performed patch-clamp recordings from basal amygdala (BA) neurons in brain slices from mice with channelrhodopsin genetically targeted to 5-HT neurons. Optical stimulation of 5-HT terminals at low frequencies (≤1 Hz) evoked a short-latency excitation of BA interneurons (INs) that was depressed at higher frequencies. Pharmacological analysis revealed that this effect was mediated by glutamate and not 5-HT because it was abolished by ionotropic glutamate receptor antagonists. Optical stimulation of 5-HT terminals at higher frequencies (10-20 Hz) evoked both slow excitation and slow inhibition of INs. These effects were mediated by 5-HT because they were blocked by antagonists of 5-HT 2A and 5-HT 1A receptors, respectively. These fast glutamate- and slow 5-HT-mediated responses often coexisted in the same neuron. Interestingly, fast-spiking and non-fast-spiking INs displayed differential modulation by glutamate and 5-HT. Furthermore, optical stimulation of 5-HT terminals did not evoke glutamate release onto BA principal neurons, but inhibited these cells directly via activation of 5-HT 1A receptors and indirectly via enhanced GABA release. Collectively, these findings suggest that 5-HT neurons exert a frequency-dependent, cell-type-specific control over BA circuitry via 5-HT and glutamate co-release to inhibit the BA output. SIGNIFICANCE STATEMENT The modulation of the amygdala by serotonin (5-HT) is important for emotional regulation and is implicated in the pathogenesis and treatment of affective disorders

Contribution of altered signal transduction associated to glutamate receptors in brain to the neurological alterations of hepatic encephalopathy

Institute of Scientific and Technical Information of China (English)

Vicente Felipo

2006-01-01

Patients with liver disease may present hepatic encephalopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations,including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death.The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE.These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced,which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE.However, it is necessary to previously assess the possible secondary effects.Patients with HE may present psychomotor slowing,hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and

Synthesis and characterization in monkey of [{sup 11}C]SP203 as a radioligand for imaging brain metabotropic glutamate 5 receptors

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Simeon, Fabrice G.; Liow, Jeih-San; Zhang, Yi; Hong, Jinsoo; Gladding, Robert L.; Zoghbi, Sami S.; Innis, Robert B.; Pike, Victor W. [National Institutes of Health, Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD (United States)

2012-12-15

[{sup 18}F]SP203 (3-fluoro-5-(2-(2-([{sup 18}F]fluoromethyl)-thiazol-4-yl)ethynyl)benzonitrile) is an effective high-affinity and selective radioligand for imaging metabotropic 5 receptors (mGluR5) in human brain with PET. To provide a radioligand that may be used for more than one scanning session in the same subject in a single day, we set out to label SP203 with shorter-lived {sup 11}C (t{sub 1/2} = 20.4 min) and to characterize its behavior as a radioligand with PET in the monkey. Iodo and bromo precursors were obtained by cross-coupling 2-fluoromethyl-4-((trimethylsilyl)ethynyl)-1,3-thiazole with 3,5-diiodofluorobenzene and 3,5-dibromofluorobenzene, respectively. Treatment of either precursor with [{sup 11}C]cyanide ion rapidly gave [{sup 11}C]SP203, which was purified with high-performance liquid chromatography. PET was used to measure the uptake of radioactivity in brain regions after injecting [{sup 11}C]SP203 intravenously into rhesus monkeys at baseline and under conditions in which mGluR5 were blocked with 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP). The emergence of radiometabolites in monkey blood in vitro and in vivo was assessed with radio-HPLC. The stability of [{sup 11}C]SP203 in human blood in vitro was also measured. The iodo precursor gave [{sup 11}C]SP203 in higher radiochemical yield (>98 %) than the bromo precursor (20-52 %). After intravenous administration of [{sup 11}C]SP203 into three rhesus monkeys, radioactivity peaked early in brain (average 12.5 min) with a regional distribution in rank order of expected mGluR5 density. Peak uptake was followed by a steady decline. No radioactivity accumulated in the skull. In monkeys pretreated with MTEP before [{sup 11}C]SP203 administration, radioactivity uptake in brain was again high but then declined more rapidly than in the baseline scan to a common low level. [{sup 11}C]SP203 was unstable in monkey blood in vitro and in vivo, and gave predominantly less lipophilic radiometabolites

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.

Identification of the glutaminase genes of Aspergillus sojae involved in glutamate production during soy sauce fermentation.

Science.gov (United States)

Ito, Kotaro; Koyama, Yasuji; Hanya, Yoshiki

2013-01-01

Glutaminase, an enzyme that catalyzes the conversion of L-glutamine to L-glutamate, enhances the umami taste in soy sauce. The Aspergillus sojae genome contains 10 glutaminase genes. In this study, we estimated that approximately 60% of the glutamate in soy sauce is produced through the glutaminase reaction. To determine which glutaminase is involved in soy sauce glutamate production, we prepared soy sauces using single and multiple glutaminase gene disruptants of A. sojae. The glutamate concentration in soy sauce prepared using the ΔgahA-ΔgahB-ΔggtA-Δgls disruptant was approximately 60% lower than that in the control strain, whereas it was decreased by approximately 20-30% in the ΔgahA-ΔgahB disruptant. However, the glutamate concentration was unchanged in the soy sauces prepared using the ΔgahA-ΔggtA-Δgls and ΔgahB-ΔggtA-Δgls disruptants. These results indicate that four glutaminases are involved in glutamate production in soy sauce, and that the peptidoglutaminase activities of GahA and GahB increase the glutamate concentration in soy sauce.

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

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

National Research Council Canada - National Science Library

Levey, Alan

2000-01-01

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

In vivo analysis of the role of metabotropic glutamate receptors in the afferent regulation of chick cochlear nucleus neurons.

Science.gov (United States)

Carzoli, Kathryn L; Hyson, Richard L

2011-02-01

Cochlea removal results in the death of approximately 20-30% of neurons in the chick nucleus magnocellularis (NM). One early event in NM neuronal degradation is the disruption of their ribosomes. This can be visualized in the first few hours following cochlea removal using Y10B, an antibody that recognizes ribosomal RNA. Previous studies using a brain slice preparation suggest that maintenance of ribosomal integrity in NM neurons requires metabotropic glutamate receptor (mGluR) activation. Isolating the brain slice in vitro, however, may eliminate other potential sources of trophic support and only allows for evaluation of the early changes that occur in NM neurons following deafferentation. Consequently, it is not known if mGluR activation is truly required for the maintenance of NM neurons in the intact system. The current experiments evaluated the importance of mGluRs in vivo. The effects of short-term receptor blockade were assessed through Y10B labeling and the effects of long-term blockade were assessed through stereological counting of NM neurons in Nissl-stained tissue. mGluR antagonists or vehicle were administered intracerebroventricularly following unilateral cochlea removal. Vehicle-treated subjects replicated the previously reported effects of cochlea removal, showing lighter Y10B labeling and fewer Nissl-stained NM neurons on the deafened side of the brain. Blockade of mGluRs prevented the rapid activity-dependent difference in Y10B labeling, and in some cases, had the reverse effect, yielding lighter labeling of NM neurons on the intact side of the brain. Similarly, mGluR blockade over longer survival periods resulted in a reduction in number of cells on both intact and deafferented sides of the brain, and in some cases, yielded a reverse effect of fewer neurons on the intact side versus deafened side. These data are consistent with in vitro findings and suggest that mGluR activation plays a vital role in the afferent maintenance of NM neurons

Impaired RNA splicing of 5'-regulatory sequences of the astroglial glutamate transporter EAAT2 in human astrocytoma

NARCIS (Netherlands)

Münch, C.; Penndorf, A.; Schwalenstöcker, B.; Troost, D.; Ludolph, A. C.; Ince, P.; Meyer, T.

2001-01-01

A loss of the glutamate transporter EAAT2 has been reported in the neoplastic transformation of astrocytic cells and astrocytoma. The RNA expression of EAAT2 and five 5'-regulatory splice variants was investigated to identify alterations of the post-transcriptional EAAT2 gene regulation in human

Genetic association studies of glutamate, GABA and related genes in schizophrenia and bipolar disorder: a decade of advance.

Science.gov (United States)

Cherlyn, Suat Ying Tan; Woon, Puay San; Liu, Jian Jun; Ong, Wei Yi; Tsai, Guo Chuan; Sim, Kang

2010-05-01

Schizophrenia (SZ) and bipolar disorder (BD) are debilitating neurobehavioural disorders likely influenced by genetic and non-genetic factors and which can be seen as complex disorders of synaptic neurotransmission. The glutamatergic and GABAergic neurotransmission systems have been implicated in both diseases and we have reviewed extensive literature over a decade for evidence to support the association of glutamate and GABA genes in SZ and BD. Candidate-gene based population and family association studies have implicated some ionotrophic glutamate receptor genes (GRIN1, GRIN2A, GRIN2B and GRIK3), metabotropic glutamate receptor genes (such as GRM3), the G72/G30 locus and GABAergic genes (e.g. GAD1 and GABRB2) in both illnesses to varying degrees, but further replication studies are needed to validate these results. There is at present no consensus on specific single nucleotide polymorphisms or haplotypes associated with the particular candidate gene loci in these illnesses. The genetic architecture of glutamate systems in bipolar disorder need to be better studied in view of recent data suggesting an overlap in the genetic aetiology of SZ and BD. There is a pressing need to integrate research platforms in genomics, epistatic models, proteomics, metabolomics, neuroimaging technology and translational studies in order to allow a more integrated understanding of glutamate and GABAergic signalling processes and aberrations in SZ and BD as well as their relationships with clinical presentations and treatment progress over time. (c) 2010 Elsevier Ltd. All rights reserved.

Synthesis, in vitro and in vivo evaluation of [11C]MMTP: a potential PET ligand for mGluR1 receptors

DEFF Research Database (Denmark)

Prabhakaran, Jaya; Majo, Vattoly J; Milak, Matthew S

2010-01-01

Synthesis, in vitro and in vivo evaluation of [O-methyl-(11)C]dimethylamino-3(4-methoxyphenyl)-3H-pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-4-one (1), a potential imaging agent for mGluR1 receptors using PET are described. Synthesis of the corresponding desmethyl precursor 2 was achieved...... selectively labeled mGluR1 receptors in slide-mounted sections of postmortem human brain containing cerebellum, hippocampus, prefrontal cortex and striatum as demonstrated by in vitro autoradiography using phosphor-imaging. PET studies in anesthetized baboon show that [(11)C]1 penetrates the BBB...... and accumulates in cerebellum, a region reported to have higher expression of mGluR1. These findings suggest [(11)C]1 is a promising PET radiotracer candidate for mGluR1....

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.

The Group 2 Metabotropic Glutamate Receptor Agonist LY379268 Rescues Neuronal, Neurochemical and Motor Abnormalities in R6/2 Huntington’s Disease Mice

Science.gov (United States)

Reiner, A.; Lafferty, D.C.; Wang, H.B.; Del Mar, N.; Deng, Y.P.

2012-01-01

Excitotoxic injury to striatum by dysfunctional cortical input or aberrant glutamate uptake may contribute to Huntington’s Disease (HD) pathogenesis. Since corticostriatal terminals possess mGluR2/3 autoreceptors, whose activation dampens glutamate release, we tested the ability of the mGluR2/3 agonist LY379268 to improve the phenotype in R6/2 HD mice with 120–125 CAG repeats. Daily subcutaneous injection of a maximum tolerated dose (MTD) of LY379268 (20mg/kg) had no evident adverse effects in WT mice, and diverse benefits in R6/2 mice, both in a cohort of mice tested behaviorally until the end of R6/2 lifespan and in a cohort sacrificed at 10 weeks of age for blinded histological analysis. MTD LY379268 yielded a significant 11% increase in R6/2 survival, an improvement on rotarod, normalization and/or improvement in locomotor parameters measured in open field (activity, speed, acceleration, endurance, and gait), a rescue of a 15–20% cortical and striatal neuron loss, normalization of SP striatal neuron neurochemistry, and to a lesser extent enkephalinergic striatal neuron neurochemistry. Deficits were greater in male than female R6/2 mice, and drug benefit tended to be greater in males. The improvements in SP striatal neurons, which facilitate movement, are consistent with the improved movement in LY379268-treated R6/2 mice. Our data indicate that mGluR2/3 agonists may be particularly useful for ameliorating the morphological, neurochemical and motor defects observed in HD. PMID:22472187

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.)

D-serine deficiency attenuates the behavioral and cellular effects induced by the hallucinogenic 5-HT(2A) receptor agonist DOI

DEFF Research Database (Denmark)

Santini, Martin A; Balu, Darrick T; Puhl, Matthew D

2014-01-01

Both the serotonin and glutamate systems have been implicated in the pathophysiology of schizophrenia, as well as in the mechanism of action of antipsychotic drugs. Psychedelic drugs act through the serotonin 2A receptor (5-HT2AR), and elicit a head-twitch response (HTR) in mice, which directly...... correlates to 5-HT2AR activation and is absent in 5-HT2AR knockout mice. The precise mechanism of this response remains unclear, but both an intrinsic cortico-cortical pathway and a thalamo-cortical pathway involving glutamate release have been proposed. Here, we used a genetic model of NMDAR hypofunction......RNA. These altered functional responses in SRKO mice were not associated with changes in cortical or hippocampal 5-HT levels or in 5-HT2AR and metabotropic glutamate-2 receptor (mGluR2) mRNA and protein expression. Together, these findings suggest that D-serine-dependent NMDAR activity is involved in mediating...

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.

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

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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.

Surface expression of metabotropic glutamate receptor variants mGluR1a and mGluR1b in transfected HEK293 cells

Czech Academy of Sciences Publication Activity Database

Kumpošt, Jiří; Syrová, Zdeňka; Kulihová, Lenka; Franková, Daniela; Bologna, J.C.; Hlaváčková, Veronika; Prezeau, L.; Králíková, Michaela; Hrušková, Bohdana; Pin, J. P.; Blahoš, Jaroslav

2008-01-01

Roč. 55, č. 4 (2008), s. 409-418 ISSN 0028-3908 R&D Projects: GA ČR GA303/08/1591; GA AV ČR IAA500390701; GA MŠk(CZ) LC06063 Grant - others:GA ČR(CZ) GA204/05/0920 Program:GA Institutional research plan: CEZ:AV0Z50520514 Keywords : G-proteins * glutamate * receptor Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.383, year: 2008

Adenylyl cyclase-5 in the dorsal striatum function as a molecular switch for the generation of behavioral preferences for cue-directed food choices.

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Kim, Hannah; Kim, Tae-Kyung; Kim, Ji-Eun; Park, Jin-Young; Lee, Yunjin; Kang, Minkyung; Kim, Kyoung-Shim; Han, Pyung-Lim

2014-11-07

Behavioral choices in habits and innate behaviors occur automatically in the absence of conscious selection. These behaviors are not easily modified by learning. Similar types of behaviors also occur in various mental illnesses including drug addiction, obsessive-compulsive disorder, schizophrenia, and autism. However, underlying mechanisms are not clearly understood. In the present study, we investigated the molecular mechanisms regulating unconditioned preferred behaviors in food-choices. Mice lacking adenylyl cyclase-5 (AC5 KO mice), which is preferentially expressed in the dorsal striatum, consumed food pellets nearly one after another in cages. AC5 KO mice showed aversive behaviors to bitter tasting quinine, but they compulsively chose quinine-containing AC5 KO-pellets over fresh pellets. The unusual food-choice behaviors in AC5 KO mice were due to the gain of behavioral preferences for food pellets containing an olfactory cue, which wild-type mice normally ignored. Such food-choice behaviors in AC5 KO mice disappeared when whiskers were trimmed. Conversely, whisker trimming in wildtype mice induced behavioral preferences for AC5 KO food pellets, indicating that preferred food-choices were not learned through prior experience. Both AC5 KO mice and wildtype mice with trimmed whiskers had increased glutamatergic input from the barrel cortex into the dorsal striatum, resulting in an increase in the mGluR1-dependent signaling cascade. The siRNA-mediated inhibition of mGluR1 in the dorsal striatum in AC5 KO mice and wildtype mice with trimmed whiskers abolished preferred choices for AC5 KO food pellets, whereas siRNA-mediated inhibition of mGluR3 glutamate receptors in the dorsal striatum in wildtype mice induced behavioral preferences for AC5 KO food pellets, thus mimicking AC5 KO phenotypes. Our results show that the gain and loss of behavioral preferences for a specific cue-directed option were regulated by specific cellular factors in the dorsal striatum, such

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

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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.

GABA receptor subunit distribution and FMRP-mGluR5 signaling abnormalities in the cerebellum of subjects with schizophrenia, mood disorders, and autism.

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Fatemi, S Hossein; Folsom, Timothy D

2015-09-01

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. GABAergic receptor abnormalities have been documented in several major psychiatric disorders including schizophrenia, mood disorders, and autism. Abnormal expression of mRNA and protein for multiple GABA receptors has also been observed in multiple brain regions leading to alterations in the balance between excitatory/inhibitory signaling in the brain with potential profound consequences for normal cognition and maintenance of mood and perception. Altered expression of GABAA receptor subunits has been documented in fragile X mental retardation 1 (FMR1) knockout mice, suggesting that loss of its protein product, fragile X mental retardation protein (FMRP), impacts GABAA subunit expression. Recent postmortem studies from our laboratory have shown reduced expression of FMRP in the brains of subjects with schizophrenia, bipolar disorder, major depression, and autism. FMRP acts as a translational repressor and, under normal conditions, inhibits metabotropic glutamate receptor 5 (mGluR5)-mediated signaling. In fragile X syndrome (FXS), the absence of FMRP is hypothesized to lead to unregulated mGluR5 signaling, ultimately resulting in the behavioral and intellectual impairments associated with this disorder. Our laboratory has identified changes in mGluR5 expression in autism, schizophrenia, and mood disorders. In the current review article, we discuss our postmortem data on GABA receptors, FMRP, and mGluR5 levels and compare our results with other laboratories. Finally, we discuss the interactions between these molecules and the potential for new therapeutic interventions that target these interconnected signaling systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Functional Comparison of the Two Bacillus anthracis Glutamate Racemases▿

OpenAIRE

Dodd, Dylan; Reese, Joseph G.; Louer, Craig R.; Ballard, Jimmy D.; Spies, M. Ashley; Blanke, Steven R.

2007-01-01

Glutamate racemase activity in Bacillus anthracis is of significant interest with respect to chemotherapeutic drug design, because l-glutamate stereoisomerization to d-glutamate is predicted to be closely associated with peptidoglycan and capsule biosynthesis, which are important for growth and virulence, respectively. In contrast to most bacteria, which harbor a single glutamate racemase gene, the genomic sequence of B. anthracis predicts two genes encoding glutamate racemases, racE1 and rac...

Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene

DEFF Research Database (Denmark)

Tosic, Mirjana; Ott, Jurg; Barral, Sandra

2006-01-01

Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCLM......) subunit, is strongly associated with schizophrenia in two case-control studies and in one family study. GCLM gene expression is decreased in patients' fibroblasts. Thus, GSH metabolism dysfunction is proposed as one of the vulnerability factors for schizophrenia....

Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene

DEFF Research Database (Denmark)

Tosic, Mirjana; Ott, Jurg; Barral, Sandra

2006-01-01

Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCL......) subunit, is strongly associated with schizophrenia in two case-control studies and in one family study. GCLM gene expression is decreased in patients' fibroblasts. Thus, GSH metabolism dysfunction is proposed as one of the vulnerability factors for schizophrenia....

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.

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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.

Evaluation of a bolus/infusion protocol for 11C-ABP688, a PET tracer for mGluR5

International Nuclear Information System (INIS)

Burger, Cyrill; Deschwanden, Alexandra; Ametamey, Simon; Johayem, Anass; Mancosu, Bruno; Wyss, Matthias; Hasler, Gregor; Buck, Alfred

2010-01-01

11 C-ABP-688 is a selective tracer for the mGluR5 receptor. Its kinetics is fast and thus favourable for an equilibrium approach to determine receptor-related parameters. The purpose of this study was to test the hypothesis that the pattern of the 11 C-ABP688 uptake using a bolus-plus-infusion (B/I) protocol at early time points corresponds to the perfusion and at a later time point to the total distribution volume. Methods: A bolus and a B/I study (1 h each) was performed in five healthy male volunteers. With the B/I protocol, early and late scans were normalized to gray matter, cerebellum and white matter. The same normalization was done on the maps of the total distribution volume (Vt) and K 1 which were calculated in the study with bolus only injection and the Logan method (Vt) and a two-tissue compartment model (K 1 ). Results: There was an excellent correlation close to the identity line between the pattern of the late uptake in the B/I study and Vt of the bolus-only study for all three normalizations. The pattern of the early uptake in the B/I study correlated well with the K 1 maps, but only when normalized to gray matter and cerebellum, not to white matter. Conclusion: It is demonstrated that with a B/I protocol the 11 C-ABP688 distribution in late scans reflects the pattern of the total distribution volume and is therefore a measure for the density pattern of mGluR5. The early scans following injection are related to blood flow, although not in a fully quantitative manner. The advantage of the B/I protocol is that no arterial blood sampling is required, which is advantageous in clinical studies.

Synthesis and evaluation of a glutamic acid-modified hPAMAM complex as a promising versatile gene carrier.

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Hemmati, Mohammad; Kazemi, Bahram; Najafi, Farhood; Zarebkohan, Amir; Shirkoohi, Reza

2016-01-01

Hyperbranched poly(amidoamine) (HPAMAM), structurally analogous to polyamidoamine dendrimer (PAMAM) dendrimers, has been suggested to be an effective carrier for gene delivery. In the present study, glutamic acid-modified hPAMAM was developed as a novel non-viral gene carrier for the first time. The hPAMAM was synthesized by using a modified one-pot method. DNA was found to be bound to hPAMAM at different weight ratios (WhPAMAM/WDNA). The resulting HPAMAM-Glu20 was able to efficiently protect the encapsulated-DNA against degradation for over 2 h. In addition to low cytotoxicity, the transfection efficiency of hPAMAM-Glu20 represented much higher (p glutamic amino acid (Glu)-based gene delivery is an economical, effective and biocompatible method.

In vitro and in vivo evaluation of [11C]MPEPy as a potential PET ligand for mGlu5 receptors

International Nuclear Information System (INIS)

Severance, Alin J.; Parsey, Ramin V.; Kumar, J.S. Dileep; Underwood, Mark D.; Arango, Victoria; Majo, Vattoly J.; Prabhakaran, Jaya; Simpson, Norman R.; Heertum, Ronald L. van; Mann, J. John

2006-01-01

Excessive activation via the metabotropic glutamate receptor subtype 5 (mGluR 5 ) has been implicated in depression, neuropathic pain and other psychiatric, neurological and neurodegenerative diseases. A mGluR 5 radioligand for in vivo quantification by positron emission tomography (PET) would facilitate studies of the role of this receptor in disease and treatment. 3-Methoxy-5-pyridin-2-ylethynylpyridine (MPEPy), a selective and high-affinity antagonist at the mGluR 5 receptor was selected as a candidate ligand; a recent publication by Yu et al. [Nucl Med Biol 32 (2005) 631-640] presented initial micro-PET results for [ 11 C]MPEPy with enthusiasm. Building on their efforts, we report as unique contributions (1) an improved chemical synthesis method, (2) the first data using human tissue, (3) phosphor images for rat brain preparations, (4) a novel comparison of anesthetic agents and (5) in vivo data in baboon. In vitro phosphor imaging studies of this ligand using human and rat brain tissue demonstrated high specific binding in the hippocampus, striatum and cortex with minimal specific binding in the cerebellum. In contrast, in vivo micro-PET studies in rats using urethane anesthesia, PET studies in baboons using isoflurane anesthesia and ex vivo micro-PET studies in unanesthetized rats each showed little specific binding in the brain. Despite the promising in vitro results, the low signal-to-noise ratio found in vivo does not justify the use of [ 11 C]MPEPy as a PET radiotracer in humans

Contribution of glutamate decarboxylase in Lactobacillus reuteri to acid resistance and persistence in sourdough fermentation.

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Su, Marcia S; Schlicht, Sabine; Gänzle, Michael G

2011-08-30

Acid stress impacts the persistence of lactobacilli in industrial sourdough fermentations, and in intestinal ecosystems. However, the contribution of glutamate to acid resistance in lactobacilli has not been demonstrated experimentally, and evidence for the contribution of acid resistance to the competitiveness of lactobacilli in sourdough is lacking. It was therefore the aim of this study to investigate the ecological role of glutamate decarboxylase in L. reuteri. A gene coding for a putative glutamate decarboxylase, gadB, was identified in the genome of L. reuteri 100-23. Different from the organization of genetic loci coding for glutamate decarboxylase in other lactic acid bacteria, gadB was located adjacent to a putative glutaminase gene, gls3. An isogenic deletion mutant, L. reuteri ∆gadB, was generated by a double crossover method. L. reuteri 100-23 but not L. reuteri ∆gadB converted glutamate to γ-aminobutyrate (GABA) in phosphate butter (pH 2.5). In sourdough, both strains converted glutamine to glutamate but only L. reuteri 100-23 accumulated GABA. Glutamate addition to phosphate buffer, pH 2.5, improved survival of L. reuteri 100-23 100-fold. However, survival of L. reuteri ∆gadB remained essentially unchanged. The disruption of gadB did not affect growth of L. reuteri in mMRS or in sourdough. However, the wild type strain L. reuteri 100-23 displaced L. reuteri ∆gadB after 5 cycles of fermentation in back-slopped sourdough fermentations. The conversion of glutamate to GABA by L. reuteri 100-23 contributes to acid resistance and to competitiveness in industrial sourdough fermentations. The organization of the gene cluster for glutamate conversion, and the availability of amino acids in cereals imply that glutamine rather than glutamate functions as the substrate for GABA formation. The exceptional coupling of glutamine deamidation to glutamate decarboxylation in L. reuteri likely reflects adaptation to cereal substrates.

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

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Gareeva, A E; Khusnutdinova, E K

2014-01-01

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

Dietary supplementation with arginine and glutamic acid enhances key lipogenic gene expression in growing pigs.

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Hu, C J; Jiang, Q Y; Zhang, T; Yin, Y L; Li, F N; Su, J Y; Wu, G Y; Kong, X F

2017-12-01

Our previous study showed dietary supplementation with Arg and Glu increased intramuscular fat deposition and decreased back fat thickness in pigs, suggesting that the genes involved in lipid metabolism might be regulated differently in muscle and s.c. adipose (SA) tissues. Sixty Duroc × Large White × Landrace pigs with an average initial BW of 77.1 ± 1.3 kg were randomly assigned to 1 of 5 treatment groups (castrated male to female ratio = 1:1). Pigs in the control group were fed a basic diet, and those in experimental groups were fed the basic diet supplemented with 2.05% alanine (isonitrogenous group), 1.00% arginine (Arg group), 1.00% glutamic acid + 1.44% alanine (Glu group), or 1.00% arginine + 1.00% glutamic acid (Arg+Glu group). Fatty acid percentages and mRNA expression levels of the genes involved in lipid metabolism in muscle and SA tissues were examined. The percentages of C14:0 and C16:0 in the SA tissue of Glu group pigs and C14:0 in the longissimus dorsi (LD) muscle of Glu and Arg+Glu groups decreased ( acid synthase in the Arg+Glu group was more upregulated ( < 0.05) than that of the Arg group. An increase in the mRNA level of in the biceps femoris muscle was also observed in the Arg+Glu group ( < 0.05) compared with the basic diet and isonitrogenous groups. Collectively, these findings suggest that dietary supplementation with Arg and Glu upregulates the expression of genes involved in adipogenesis in muscle tissues and lipolysis in SA tissues.

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...

Effect of biotin on transcription levels of key enzymes and glutamate efflux in glutamate fermentation by Corynebacterium glutamicum.

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Cao, Yan; Duan, Zuoying; Shi, Zhongping

2014-02-01

Biotin is an important factor affecting the performance of glutamate fermentation by biotin auxotrophic Corynebacterium glutamicum and glutamate is over-produced only when initial biotin content is controlled at suitable levels or initial biotin is excessive but with Tween 40 addition during fermentation. The transcription levels of key enzymes at pyruvate, isocitrate and α-ketoglutarate metabolic nodes, as well as transport protein (TP) of glutamate were investigated under the conditions of varied biotin contents and Tween 40 supplementation. When biotin was insufficient, the genes encoding key enzymes and TP were down-regulated in the early production phase, in particular, the transcription level of isocitrate dehydrogenase (ICDH) which was only 2% of that of control. Although the cells' morphology transformation and TP level were not affected, low transcription level of ICDH led to lower final glutamate concentration (64 g/L). When biotin was excessive, the transcription levels of key enzymes were at comparable levels as those of control with ICDH as an exception, which was only 3-22% of control level throughout production phase. In this case, little intracellular glutamate accumulation (1.5 mg/g DCW) and impermeable membrane resulted in non glutamate secretion into broth, even though the quantity of TP was more than 10-folds of control level. Addition of Tween 40 when biotin was excessive stimulated the expression of all key enzymes and TP, intracellular glutamate content was much higher (10-12 mg/g DCW), and final glutamate concentration reached control level (75-80 g/L). Hence, the membrane alteration and TP were indispensable in glutamate secretion. Biotin and Tween 40 influenced the expression level of ICDH and glutamate efflux, thereby influencing glutamate production.

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

Effects of the group I metabotropic glutamate receptor agonist, DHPG, and injection stress on striatal cell signaling in food-restricted and ad libitum fed rats

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Carr Kenneth D

2004-12-01

Full Text Available Abstract Background Chronic food restriction augments the rewarding effect of centrally administered psychostimulant drugs and this effect may involve a previously documented upregulation of D-1 dopamine receptor-mediated MAP kinase signaling in nucleus accumbens (NAc and caudate-putamen (CPu. Psychostimulants are known to induce striatal glutamate release, and group I metabotropic glutamate receptors (mGluR have been implicated in the cellular and behavioral responses to amphetamine. The purpose of the present study was to evaluate whether chronic food restriction increases striatal MAP kinase signaling in response to the group I mGluR agonist, DHPG. Results Western immunoblotting was used to demonstrate that intracerebroventricular (i.c.v. injection of DHPG (500 nmol produces greater activation of ERK1/2 and CREB in CPu and NAc of food-restricted as compared to ad libitum fed rats. Fos-immunostaining induced by DHPG was also stronger in CPu and NAc core of food-restricted relative to ad libitum fed rats. However, i.c.v. injection of saline-vehicle produced greater activation of ERK1/2 and CREB in CPu and NAc of food-restricted relative to ad libitum fed rats, and this difference was not seen when subjects received no i.c.v. injection prior to sacrifice. In addition, although DHPG activated Akt, there was no difference in Akt activation between feeding groups. To probe whether the augmented ERK1/2 and CREB activation in vehicle-injected food-restricted rats are mediated by one or more GluR types, effects of an NMDA antagonist (MK-801, 100 nmol, AMPA antagonist (DNQX, 10 nmol, and group I mGluR antagonist (AIDA, 100 nmol were compared to saline-vehicle. Antagonist injections did not diminish activation of ERK1/2 or CREB. Conclusions These results indicate that a group I mGluR agonist induces phosphorylation of Akt, ERK1/2 and CREB in both CPu and NAc. However, group I mGluR-mediated signaling may not be upregulated in food-restricted rats

N-Acetylcysteine Reverses Cocaine Induced Metaplasticity

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Moussawi, Khaled; Pacchioni, Alejandra; Moran, Megan; Olive, M. Foster; Gass, Justin T.; Lavin, Antonieta; Kalivas, Peter W

2009-01-01

Cocaine addiction is characterized by an impaired ability to develop adaptive behaviors that can compete with cocaine seeking, implying a deficit in the ability to induce plasticity in cortico-accumbens circuitry critical for regulating motivated behavior. RWe found that rats withdrawn from cocaine self-administration had a marked in vivo deficit in the ability to develop long-term potentation (LTP) and depression (LTD) in the nucleus accumbens core subregion following stimulation of prefrontal cortex. N-acetylcysteine treatment prevents relapse in animal models and craving in humans by activating cystine-glutamate exchange and thereby stimulating extrasynaptic metabotropic glutamate receptors (mGluR). N-acetylcysteine treatment restored the ability to induce LTP and LTD by indirectly stimulating mGluR2/3 and mGluR5, respectively. Cocaine self-administration induces metaplasticity that inhibits the further induction of synaptic plasticity, and this impairment can be reversed by N-acetylcysteine, a drug that also prevents relapse. PMID:19136971

N-Acetylcysteine reverses cocaine-induced metaplasticity.

Science.gov (United States)

Moussawi, Khaled; Pacchioni, Alejandra; Moran, Megan; Olive, M Foster; Gass, Justin T; Lavin, Antonieta; Kalivas, Peter W

2009-02-01

Cocaine addiction is characterized by an impaired ability to develop adaptive behaviors that can compete with cocaine seeking, implying a deficit in the ability to induce plasticity in cortico-accumbens circuitry crucial for regulating motivated behavior. We found that rats withdrawn from cocaine self-administration had a marked in vivo deficit in the ability to develop long-term potentiation (LTP) and long-term depression (LTD) in the nucleus accumbens core subregion after stimulation of the prefrontal cortex. N-acetylcysteine (NAC) treatment prevents relapse in animal models and craving in humans by activating cystine-glutamate exchange and thereby stimulating extrasynaptic metabotropic glutamate receptors (mGluR). NAC treatment of rats restored the ability to induce LTP and LTD by indirectly stimulating mGluR2/3 and mGluR5, respectively. Our findings show that cocaine self-administration induces metaplasticity that inhibits further induction of synaptic plasticity, and this impairment can be reversed by NAC, a drug that also prevents relapse.

Evolution of glutamate dehydrogenase genes: evidence for lateral gene transfer within and between prokaryotes and eukaryotes

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Roger Andrew J

2003-06-01

Full Text Available Abstract Background Lateral gene transfer can introduce genes with novel functions into genomes or replace genes with functionally similar orthologs or paralogs. Here we present a study of the occurrence of the latter gene replacement phenomenon in the four gene families encoding different classes of glutamate dehydrogenase (GDH, to evaluate and compare the patterns and rates of lateral gene transfer (LGT in prokaryotes and eukaryotes. Results We extend the taxon sampling of gdh genes with nine new eukaryotic sequences and examine the phylogenetic distribution pattern of the various GDH classes in combination with maximum likelihood phylogenetic analyses. The distribution pattern analyses indicate that LGT has played a significant role in the evolution of the four gdh gene families. Indeed, a number of gene transfer events are identified by phylogenetic analyses, including numerous prokaryotic intra-domain transfers, some prokaryotic inter-domain transfers and several inter-domain transfers between prokaryotes and microbial eukaryotes (protists. Conclusion LGT has apparently affected eukaryotes and prokaryotes to a similar extent within the gdh gene families. In the absence of indications that the evolution of the gdh gene families is radically different from other families, these results suggest that gene transfer might be an important evolutionary mechanism in microbial eukaryote genome evolution.

A Phase I randomized clinical trial testing the safety, tolerability and preliminary pharmacokinetics of the mGluR5 negative allosteric modulator GET 73 following single and repeated doses in healthy volunteers.

Science.gov (United States)

Haass-Koffler, Carolina L; Goodyear, Kimberly; Long, Victoria M; Tran, Harrison H; Loche, Antonella; Cacciaglia, Roberto; Swift, Robert M; Leggio, Lorenzo

2017-11-15

Preclinical work suggests that the metabotropic glutamate receptor subtype 5 (mGlu5) may represent a novel target to treat neuropsychiatric disorders, including alcohol use disorder and obesity. The goal of this first-in-man study was to evaluate the safety, tolerability and pharmacokinetics (PK) of GET 73 (PubChem SID: 329974174), a novel mGluR5 negative allosteric modulator. This was a double-blind, placebo-controlled, ascending dose, Phase I study conducted in healthy male volunteers in two experiments. GET 73 was administered as single ascending doses (N=48; Experiment 1; 10, 30, 100, 300, 450, 600-mg) or multiple ascending doses (N=32; Experiment 2; 100, 300, 450, 450-mg twice a day). Primary endpoints were the incidence of adverse events (AEs) among drug conditions and drug tolerability. The secondary endpoints were the PK parameters of GET 73 and its metabolite MET 2. Single GET 73 doses of up to 600-mg and repeated ascending doses of up to 450-mg twice/day were safe and well-tolerated. There were no serious or severe AEs. All AEs were mild or moderate in severity. Total GET 73 exposure increased with each increased GET 73 dose. A dose-related increase in mean maximum plasma drug concentration was observed after repeated dosing. Maximum plasma drug concentrations occurred between 0.5 and 2.05h after administration in all groups for both single and repeated doses. This first-in-human study indicates that GET 73, as single or multiple ascending doses, is safe and well-tolerated when administered to healthy male volunteers. Copyright © 2017 Elsevier B.V. All rights reserved.

Poly-γ-glutamic Acid Synthesis, Gene Regulation, Phylogenetic Relationships, and Role in Fermentation.

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Hsueh, Yi-Huang; Huang, Kai-Yao; Kunene, Sikhumbuzo Charles; Lee, Tzong-Yi

2017-12-07

Poly-γ-glutamic acid (γ-PGA) is a biodegradable biopolymer produced by several bacteria, including Bacillus subtilis and other Bacillus species; it has good biocompatibility, is non-toxic, and has various potential biological applications in the food, pharmaceutical, cosmetic, and other industries. In this review, we have described the mechanisms of γ-PGA synthesis and gene regulation, its role in fermentation, and the phylogenetic relationships among various pgsBCAE , a biosynthesis gene cluster of γ-PGA, and pgdS , a degradation gene of γ-PGA. We also discuss potential applications of γ-PGA and highlight the established genetic recombinant bacterial strains that produce high levels of γ-PGA, which can be useful for large-scale γ-PGA production.

Effects of mGluR5 and mGluR1 antagonists on anxiety-like behavior and learning in developing rats

Czech Academy of Sciences Publication Activity Database

Mikulecká, Anna; Mareš, Pavel

2009-01-01

Roč. 204, č. 1 (2009), s. 133-139 ISSN 0166-4328 R&D Projects: GA ČR(CZ) GA305/06/1188 Institutional research plan: CEZ:AV0Z50110509 Keywords : metabotropic glutamate receptors * anxiety * learning Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.220, year: 2009

Essential roles of aspartate aminotransferase 1 and vesicular glutamate transporters in β-cell glutamate signaling for incretin-induced insulin secretion.

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Naoya Murao

Full Text Available Incretins (GLP-1 and GIP potentiate insulin secretion through cAMP signaling in pancreatic β-cells in a glucose-dependent manner. We recently proposed a mechanistic model of incretin-induced insulin secretion (IIIS that requires two critical processes: 1 generation of cytosolic glutamate through the malate-aspartate (MA shuttle in glucose metabolism and 2 glutamate transport into insulin granules by cAMP signaling to promote insulin granule exocytosis. To directly prove the model, we have established and characterized CRISPR/Cas9-engineered clonal mouse β-cell lines deficient for the genes critical in these two processes: aspartate aminotransferase 1 (AST1, gene symbol Got1, a key enzyme in the MA shuttle, which generates cytosolic glutamate, and the vesicular glutamate transporters (VGLUT1, VGLUT2, and VGLUT3, gene symbol Slc17a7, Slc17a6, and Slc17a8, respectively, which participate in glutamate transport into secretory vesicles. Got1 knockout (KO β-cell lines were defective in cytosolic glutamate production from glucose and showed impaired IIIS. Unexpectedly, different from the previous finding that global Slc17a7 KO mice exhibited impaired IIIS from pancreatic islets, β-cell specific Slc17a7 KO mice showed no significant impairment in IIIS, as assessed by pancreas perfusion experiment. Single Slc17a7 KO β-cell lines also retained IIIS, probably due to compensatory upregulation of Slc17a6. Interestingly, triple KO of Slc17a7, Slc17a6, and Slc17a8 diminished IIIS, which was rescued by exogenously introduced wild-type Slc17a7 or Slc17a6 genes. The present study provides direct evidence for the essential roles of AST1 and VGLUTs in β-cell glutamate signaling for IIIS and also shows the usefulness of the CRISPR/Cas9 system for studying β-cells by simultaneous disruption of multiple genes.

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.

Poly-γ-glutamic Acid Synthesis, Gene Regulation, Phylogenetic Relationships, and Role in Fermentation

Science.gov (United States)

Hsueh, Yi-Huang; Huang, Kai-Yao; Kunene, Sikhumbuzo Charles; Lee, Tzong-Yi

2017-01-01

Poly-γ-glutamic acid (γ-PGA) is a biodegradable biopolymer produced by several bacteria, including Bacillus subtilis and other Bacillus species; it has good biocompatibility, is non-toxic, and has various potential biological applications in the food, pharmaceutical, cosmetic, and other industries. In this review, we have described the mechanisms of γ-PGA synthesis and gene regulation, its role in fermentation, and the phylogenetic relationships among various pgsBCAE, a biosynthesis gene cluster of γ-PGA, and pgdS, a degradation gene of γ-PGA. We also discuss potential applications of γ-PGA and highlight the established genetic recombinant bacterial strains that produce high levels of γ-PGA, which can be useful for large-scale γ-PGA production. PMID:29215550

Poly-γ-glutamic Acid Synthesis, Gene Regulation, Phylogenetic Relationships, and Role in Fermentation

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Yi-Huang Hsueh

2017-12-01

Full Text Available Poly-γ-glutamic acid (γ-PGA is a biodegradable biopolymer produced by several bacteria, including Bacillus subtilis and other Bacillus species; it has good biocompatibility, is non-toxic, and has various potential biological applications in the food, pharmaceutical, cosmetic, and other industries. In this review, we have described the mechanisms of γ-PGA synthesis and gene regulation, its role in fermentation, and the phylogenetic relationships among various pgsBCAE, a biosynthesis gene cluster of γ-PGA, and pgdS, a degradation gene of γ-PGA. We also discuss potential applications of γ-PGA and highlight the established genetic recombinant bacterial strains that produce high levels of γ-PGA, which can be useful for large-scale γ-PGA production.

Systematic study of association of four GABAergic genes: glutamic acid decarboxylase 1 gene, glutamic acid decarboxylase 2 gene, GABA(B) receptor 1 gene and GABA(A) receptor subunit beta2 gene, with schizophrenia using a universal DNA microarray.

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Zhao, Xu; Qin, Shengying; Shi, Yongyong; Zhang, Aiping; Zhang, Jing; Bian, Li; Wan, Chunling; Feng, Guoyin; Gu, Niufan; Zhang, Guangqi; He, Guang; He, Lin

2007-07-01

Several studies have suggested the dysfunction of the GABAergic system as a risk factor in the pathogenesis of schizophrenia. In the present study, case-control association analysis was conducted in four GABAergic genes: two glutamic acid decarboxylase genes (GAD1 and GAD2), a GABA(A) receptor subunit beta2 gene (GABRB2) and a GABA(B) receptor 1 gene (GABBR1). Using a universal DNA microarray procedure we genotyped a total of 20 SNPs on the above four genes in a study involving 292 patients and 286 controls of Chinese descent. Statistically significant differences were observed in the allelic frequencies of the rs187269C/T polymorphism in the GABRB2 gene (P=0.0450, chi(2)=12.40, OR=1.65) and the -292A/C polymorphism in the GAD1 gene (P=0.0450, chi(2)=14.64 OR=1.77). In addition, using an electrophoretic mobility shift assay (EMSA), we discovered differences in the U251 nuclear protein binding to oligonucleotides representing the -292 SNP on the GAD1 gene, which suggests that the -292C allele has reduced transcription factor binding efficiency compared with the 292A allele. Using the multifactor-dimensionality reduction method (MDR), we found that the interactions among the rs187269C/T polymorphism in the GABRB2 gene, the -243A/G polymorphism in the GAD2 gene and the 27379C/T and 661C/T polymorphisms in the GAD1 gene revealed a significant association with schizophrenia (Pschizophrenia in the Chinese population.

Hierarchical mutational events compensate for glutamate auxotrophy of a Bacillus subtilis gltC mutant.

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Dormeyer, Miriam; Lübke, Anastasia L; Müller, Peter; Lentes, Sabine; Reuß, Daniel R; Thürmer, Andrea; Stülke, Jörg; Daniel, Rolf; Brantl, Sabine; Commichau, Fabian M

2017-06-01

Glutamate is the major donor of nitrogen for anabolic reactions. The Gram-positive soil bacterium Bacillus subtilis either utilizes exogenously provided glutamate or synthesizes it using the gltAB-encoded glutamate synthase (GOGAT). In the absence of glutamate, the transcription factor GltC activates expression of the GOGAT genes for glutamate production. Consequently, a gltC mutant strain is auxotrophic for glutamate. Using a genetic selection and screening system, we could isolate and differentiate between gltC suppressor mutants in one step. All mutants had acquired the ability to synthesize glutamate, independent of GltC. We identified (i) gain-of-function mutations in the gltR gene, encoding the transcription factor GltR, (ii) mutations in the promoter of the gltAB operon and (iii) massive amplification of the genomic locus containing the gltAB operon. The mutants belonging to the first two classes constitutively expressed the gltAB genes and produced sufficient glutamate for growth. By contrast, mutants that belong to the third class appeared most frequently and solved glutamate limitation by increasing the copy number of the poorly expressed gltAB genes. Thus, glutamate auxotrophy of a B. subtilis gltC mutant can be relieved in multiple ways. Moreover, recombination-dependent amplification of the gltAB genes is the predominant mutational event indicating a hierarchy of mutations. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

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...

mGluR1 receptors contribute to non-purinergic slow excitatory transmission to submucosal VIP neurons of guinea-pig ileum

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Jaime Pei Pei Foong

2009-05-01

Full Text Available Vasoactive intestinal peptide (VIP immunoreactive secretomotor neurons in the submucous plexus are involved in mediating bacterial toxin-induced hypersecretion leading to diarrhoea. VIP neurons become hyperexcitable after the mucosa is exposed to cholera toxin, which suggests that the manipulation of the excitability of these neurons may be therapeutic. This study used standard intracellular recording methods to systematically characterize slow excitatory postsynaptic potentials (EPSPs evoked in submucosal VIP neurons by different stimulus regimes (1, 3 and 15 pulse 30 Hz stimulation, together with their associated input resistances and pharmacology. All slow EPSPs were associated with a significant increase in input resistance compared to baseline values. Slow EPSPs evoked by a single stimulus were confirmed to be purinergic, however, slow EPSPs evoked by 15 pulse trains were non-purinergic and those evoked by 3 pulse trains were mixed. NK1 or NK3 receptor antagonists did not affect slow EPSPs. The group I mGluR receptor antagonist, PHCCC reduced the amplitude of purinergic and non-purinergic slow EPSPs. Blocking mGluR1 receptors depressed the overall response to 3 and 15 pulse trains, but this effect was inconsistent, while blockade of mGluR5 receptors had no effect on the non-purinergic slow EPSPs. Thus, although other receptors are almost certainly involved, our data indicate that there are at least two pharmacologically distinct types of slow EPSPs in the VIP secretomotor neurons: one mediated by P2Y receptors and the other in part by mGluR1 receptors.

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

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

2015-03-15

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

Signal Transduction Mechanisms Underlying Group I mGluR-mediated Increase in Frequency and Amplitude of Spontaneous EPSCs in the Spinal Trigeminal Subnucleus Oralis of the Rat

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Ahn Dong-Kuk

2009-09-01

Full Text Available Abstract Group I mGluRs (mGluR1 and 5 pre- and/or postsynaptically regulate synaptic transmission at glutamatergic synapses. By recording spontaneous EPSCs (sEPSCs in the spinal trigeminal subnucleus oralis (Vo, we here investigated the regulation of glutamatergic transmission through the activation of group I mGluRs. Bath-applied DHPG (10 μM/5 min, activating the group I mGluRs, increased sEPSCs both in frequency and amplitude; particularly, the increased amplitude was long-lasting. The DHPG-induced increases of sEPSC frequency and amplitude were not NMDA receptor-dependent. The DHPG-induced increase in the frequency of sEPSCs, the presynaptic effect being further confirmed by the DHPG effect on paired-pulse ratio of trigeminal tract-evoked EPSCs, an index of presynaptic modulation, was significantly but partially reduced by blockades of voltage-dependent sodium channel, mGluR1 or mGluR5. Interestingly, PKC inhibition markedly enhanced the DHPG-induced increase of sEPSC frequency, which was mainly accomplished through mGluR1, indicating an inhibitory role of PKC. In contrast, the DHPG-induced increase of sEPSC amplitude was not affected by mGluR1 or mGluR5 antagonists although the long-lasting property of the increase was disappeared; however, the increase was completely inhibited by blocking both mGluR1 and mGluR5. Further study of signal transduction mechanisms revealed that PLC and CaMKII mediated the increases of sEPSC in both frequency and amplitude by DHPG, while IP3 receptor, NO and ERK only that of amplitude during DHPG application. Altogether, these results indicate that the activation of group I mGluRs and their signal transduction pathways differentially regulate glutamate release and synaptic responses in Vo, thereby contributing to the processing of somatosensory signals from orofacial region.

Insulin-induced inhibition of gluconeogenesis genes, including glutamic pyruvic transaminase 2, is associated with reduced histone acetylation in a human liver cell line.

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Honma, Kazue; Kamikubo, Michiko; Mochizuki, Kazuki; Goda, Toshinao

2017-06-01

Hepatic glutamic pyruvic transaminase (GPT; also known as alanine aminotransferase) is a gluconeogenesis enzyme that catalyzes conversions between alanine and pyruvic acid. It is also used as a blood biomarker for hepatic damage. In this study, we investigated whether insulin regulates GPT expression, as it does for other gluconeogenesis genes, and if this involves the epigenetic modification of histone acetylation. Human liver-derived HepG2 cells were cultured with 0.5-100nM insulin for 8h, and the mRNA expression of GPT, glutamic-oxaloacetic transaminase (GOT), γ-glutamyltransferase (GGT), PCK1, G6PC and FBP1 was measured. We also investigated the extent of histone acetylation around these genes. Insulin suppressed the mRNA expression of gluconeogenesis genes (GPT2, GOT1, GOT2, GGT1, GGT2, G6PC, and PCK1) in HepG2 cells in a dose-dependent manner. mRNA levels of GPT2, but not GPT1, were decreased by insulin. Histone acetylation was also reduced around GPT2, G6PC, and PCK1 in response to insulin. The expression of GPT2 and other gluconeogenesis genes such as G6PC and PCK1 was suppressed by insulin, in association with decreases in histone H3 and H4 acetylation surrounding these genes. Copyright © 2017 Elsevier Inc. All rights reserved.

Pharmacological Enhancement of mGluR5 Facilitates Contextual Fear Memory Extinction

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Sethna, Ferzin; Wang, Hongbing

2014-01-01

Behavioral exposure therapy, which involves extinction of the previously acquired fear, has been used to treat anxiety-related symptoms such as post-traumatic stress disorder. It has been hypothesized that proextinction pharmacotherapeutics may enhance the efficacy of exposure therapy. Systemic administration of the metabotropic glutamate receptor…

Elevated CaMKIIα and Hyperphosphorylation of Homer Mediate Circuit Dysfunction in a Fragile X Syndrome Mouse Model

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Weirui Guo

2015-12-01

Full Text Available Abnormal metabotropic glutamate receptor 5 (mGluR5 function, as a result of disrupted scaffolding with its binding partner Homer, contributes to the pathophysiology of fragile X syndrome, a common inherited form of intellectual disability and autism caused by mutations in Fmr1. How loss of Fmr1 disrupts mGluR5-Homer scaffolds is unknown, and little is known about the dynamic regulation of mGluR5-Homer scaffolds in wild-type neurons. Here, we demonstrate that brief (minutes-long elevations in neural activity cause CaMKIIα-mediated phosphorylation of long Homer proteins and dissociation from mGluR5 at synapses. In Fmr1 knockout (KO cortex, Homers are hyperphosphorylated as a result of elevated CaMKIIα protein. Genetic or pharmacological inhibition of CaMKIIα or replacement of Homers with dephosphomimetics restores mGluR5-Homer scaffolds and multiple Fmr1 KO phenotypes, including circuit hyperexcitability and/or seizures. This work links translational control of an FMRP target mRNA, CaMKIIα, to the molecular-, cellular-, and circuit-level brain dysfunction in a complex neurodevelopmental disorder.

Towards trans-diagnostic mechanisms in psychiatry: neurobehavioral profile of rats with a loss-of-function point mutation in the dopamine transporter gene

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Valentina Vengeliene

2017-04-01

Full Text Available The research domain criteria (RDoC matrix has been developed to reorient psychiatric research towards measurable behavioral dimensions and underlying mechanisms. Here, we used a new genetic rat model with a loss-of-function point mutation in the dopamine transporter (DAT gene (Slc6a3_N157K to systematically study the RDoC matrix. First, we examined the impact of the Slc6a3_N157K mutation on monoaminergic signaling. We then performed behavioral tests representing each of the five RDoC domains: negative and positive valence systems, cognitive, social and arousal/regulatory systems. The use of RDoC may be particularly helpful for drug development. We studied the effects of a novel pharmacological approach metabotropic glutamate receptor mGluR2/3 antagonism, in DAT mutants in a comparative way with standard medications. Loss of DAT functionality in mutant rats not only elevated subcortical extracellular dopamine concentration but also altered the balance of monoaminergic transmission. DAT mutant rats showed deficits in all five RDoC domains. Thus, mutant rats failed to show conditioned fear responses, were anhedonic, were unable to learn stimulus-reward associations, showed impaired cognition and social behavior, and were hyperactive. Hyperactivity in mutant rats was reduced by amphetamine and atomoxetine, which are well-established medications to reduce hyperactivity in humans. The mGluR2/3 antagonist LY341495 also normalized hyperactivity in DAT mutant rats without affecting extracellular dopamine levels. We systematically characterized an altered dopamine system within the context of the RDoC matrix and studied mGluR2/3 antagonism as a new pharmacological strategy to treat mental disorders with underlying subcortical dopaminergic hyperactivity.

Glutamate prevents intestinal atrophy via luminal nutrient sensing in a mouse model of total parenteral nutrition

DEFF Research Database (Denmark)

Xiao, Weidong; Feng, Yongjia; Holst, Jens Juul

2014-01-01

significantly changed the amount of T1Rs, GLM receptors, and transporters, and GLM prevented these changes. GLM significantly prevented TPN-associated intestinal atrophy (2.5-fold increase in IEC proliferation) and was dependent on up-regulation of the protein kinase pAkt, but independent of T1R3 and mGluR5...... signaling. GLM led to a loss of EBF with TPN (60% increase in FITC-dextran permeability, 40% decline in transepithelial resistance); via T1R3, it protected EBF, whereas mGluR5 was associated with EBF loss. GLM led to a decline in circulating glucagon-like peptide 2 (GLP-2) during TPN. The decline...

Reversal of alcohol dependence-induced deficits in cue-guided behavior via mGluR2/3 signaling in mice.

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Barker, Jacqueline M; Lench, Daniel H; Chandler, L Judson

2016-01-01

Alcohol use disorders are associated with deficits in adaptive behavior. While some behavioral impairments that are associated with alcohol use disorders may predate exposure to drugs of abuse, others may result directly from exposure to drugs of abuse, including alcohol. Identifying a causal role for how alcohol exposure leads to these impairments will enable further investigation of the neurobiological mechanisms by which it acts to dysregulate adaptive behavior. In the present study, we examined the effects of chronic intermittent ethanol exposure (CIE) on the use of reward-paired cues to guide consummatory behaviors in a mouse model, and further, how manipulations of mGluR2/3 signaling-known to be dysregulated after chronic alcohol exposure-may alter the expression of this behavior. Adult male C57B/6J mice were trained to self-administer 10 % ethanol and exposed to CIE via vapor inhalation. After CIE exposure, mice were trained in a Pavlovian task wherein a cue (tone) was paired with the delivery of a 10 % sucrose unconditioned stimulus. The use of the reward-paired cue to guide licking behavior was determined across training. The effect of systemic mGluR2/3 manipulation on discrimination between cue-on and cue-off intervals was assessed by administration of the mGluR2/3 agonist LY379268 or the antagonist LY341495 prior to a testing session. Exposure to CIE resulted in reductions in discrimination between cue-on and cue-off intervals, with CIE-exposed mice exhibiting significantly lower consummatory behavior during reward-paired cues than air controls. In addition, systemic administration of an mGluR2/3 agonist restored the use of reward-paired cues in CIE-exposed animals without impacting behavior in air controls. Conversely, administration of an mGluR2/3 antagonist mimicked the effects of CIE on cue-guided licking behavior, indicating that mGluR2/3 signaling can bidirectionally regulate the ability to use reward-paired cues to guide behavior. Together

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....

Glutamate and Brain Glutaminases in Drug Addiction.

Science.gov (United States)

Márquez, Javier; Campos-Sandoval, José A; Peñalver, Ana; Matés, José M; Segura, Juan A; Blanco, Eduardo; Alonso, Francisco J; de Fonseca, Fernando Rodríguez

2017-03-01

Glutamate is the principal excitatory neurotransmitter in the central nervous system and its actions are related to the behavioral effects of psychostimulant drugs. In the last two decades, basic neuroscience research and preclinical studies with animal models are suggesting a critical role for glutamate transmission in drug reward, reinforcement, and relapse. Although most of the interest has been centered in post-synaptic glutamate receptors, the presynaptic synthesis of glutamate through brain glutaminases may also contribute to imbalances in glutamate homeostasis, a key feature of the glutamatergic hypothesis of addiction. Glutaminases are the main glutamate-producing enzymes in brain and dysregulation of their function have been associated with neurodegenerative diseases and neurological disorders; however, the possible implication of these enzymes in drug addiction remains largely unknown. This mini-review focuses on brain glutaminase isozymes and their alterations by in vivo exposure to drugs of abuse, which are discussed in the context of the glutamate homeostasis theory of addiction. Recent findings from mouse models have shown that drugs induce changes in the expression profiles of key glutamatergic transmission genes, although the molecular mechanisms that regulate drug-induced neuronal sensitization and behavioral plasticity are not clear.

Hyperactivity and Hypermotivation Associated With Increased Striatal mGluR1 Signaling in a Shank2 Rat Model of Autism

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Meera E. Modi

2018-06-01

Full Text Available Mutations in the SHANK family of genes have been consistently identified in genetic and genomic screens of autism spectrum disorder (ASD. The functional overlap of SHANK with several other ASD-associated genes suggests synaptic dysfunction as a convergent mechanism of pathophysiology in ASD. Although many ASD-related mutations result in alterations to synaptic function, the nature of those dysfunctions and the consequential behavioral manifestations are highly variable when expressed in genetic mouse models. To investigate the phylogenetic conservation of phenotypes resultant of Shank2 loss-of-function in a translationally relevant animal model, we generated and characterized a novel transgenic rat with a targeted mutation of the Shank2 gene, enabling an evaluation of gene-associated phenotypes, the elucidation of complex behavioral phenotypes, and the characterization of potential translational biomarkers. The Shank2 loss-of-function mutation resulted in a notable phenotype of hyperactivity encompassing hypermotivation, increased locomotion, and repetitive behaviors. Mutant rats also expressed deficits in social behavior throughout development and in the acquisition of operant tasks. The hyperactive phenotype was associated with an upregulation of mGluR1 expression, increased dendritic branching, and enhanced long-term depression (LTD in the striatum but opposing morphological and cellular alterations in the hippocampus (HP. Administration of the mGluR1 antagonist JNJ16259685 selectively normalized the expression of striatally mediated repetitive behaviors and physiology but had no effect on social deficits. Finally, Shank2 mutant animals also exhibited alterations in electroencephalography (EEG spectral power and event-related potentials, which may serve as translatable EEG biomarkers of synaptopathic alterations. Our results show a novel hypermotivation phenotype that is unique to the rat model of Shank2 dysfunction, in addition to the

Anti-neuronal anti-bodies in patients with early psychosis.

Science.gov (United States)

Mantere, O; Saarela, M; Kieseppä, T; Raij, T; Mäntylä, T; Lindgren, M; Rikandi, E; Stoecker, W; Teegen, B; Suvisaari, J

2018-02-01

It may be challenging to distinguish autoimmune encephalitis associated with anti-neuronal autoantibodies from primary psychiatric disorders. Here, serum was drawn from patients with a first-episode psychosis (n=70) or a clinical high-risk for psychosis (n=6) and controls (n=34). We investigated the serum prevalence of 24 anti-neuronal autoantibodies: IgG antibodies for anti-N-methyl-d-aspartate-type glutamate receptor (anti-NMDAR), glutamate and γ-aminobutyric acid alpha and beta receptors (GABA-a, GABA-b), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA), glycine receptor (GlyR), metabotropic glutamate receptor 1 and 5 (mGluR1, mGluR5), anti-Tr/Delta/notch-like epidermal growth factor-related receptor (DNER), contactin-associated protein-like 2 (CASPR2), myelin oligodendrocyte glycoprotein (MOG), glutamic acid decarboxylase-65 (GAD65), collapsin response mediator protein 5/crossveinless-2 (CV2), aquaporin-4 (AQP4), anti-dipeptidyl-peptidase-like protein-6 (DPPX), type 1 anti-neuronal nuclear antibody (ANNA-1, Hu), Ri, Yo, IgLON5, Ma2, zinc finger protein 4 (ZIC4), Rho GTPase-activating protein 26, amphiphysin, and recoverin, as well as IgA and IgM for dopamine-2-receptor (DRD2). Anti-NMDA IgG antibodies were positive with serum titer 1:320 in one patient with a clinical high risk for psychosis. He did not receive a diagnosis of encephalitis after comprehensive neurological evaluation. All other antineuronal autoantibodies were negative and there were no additional findings with immunohistochemistry of brain issues. Copyright © 2017 Elsevier B.V. All rights reserved.

Anticonvulsive effect of paeoniflorin on experimental febrile seizures in immature rats: possible application for febrile seizures in children.

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Hitomi Hino

Full Text Available Febrile seizures (FS is the most common convulsive disorder in children, but there have been no clinical and experimental studies of the possible treatment of FS with herbal medicines, which are widely used in Asian countries. Paeoniflorin (PF is a major bioactive component of Radix Paeoniae alba, and PF-containing herbal medicines have been used for neuromuscular, neuropsychiatric, and neurodegenerative disorders. In this study, we analyzed the anticonvulsive effect of PF and Keishikashakuyaku-to (KS; a PF-containing herbal medicine for hyperthermia-induced seizures in immature rats as a model of human FS. When immature (P5 male rats were administered PF or KS for 10 days, hyperthermia-induced seizures were significantly suppressed compared to control rats. In cultured hippocampal neurons, PF suppressed glutamate-induced elevation of intracellular Ca(2+ ([Ca(2+](i, glutamate receptor-mediated membrane depolarization, and glutamate-induced neuronal death. In addition, PF partially suppressed the elevation in [Ca(2+](i induced by activation of the metabotropic glutamate receptor 5 (mGluR5, but not that mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid (AMPA or N-methyl-D-aspartate (NMDA receptors. However, PF did not affect production or release of γ-aminobutyric acid (GABA in hippocampal neurons. These results suggest that PF or PF-containing herbal medicines exert anticonvulsive effects at least in part by preventing mGluR5-dependent [Ca(2+](i elevations. Thus, it could be a possible candidate for the treatment of FS in children.

A Novel Corynebacterium glutamicum l-Glutamate Exporter.

Science.gov (United States)

Wang, Yu; Cao, Guoqiang; Xu, Deyu; Fan, Liwen; Wu, Xinyang; Ni, Xiaomeng; Zhao, Shuxin; Zheng, Ping; Sun, Jibin; Ma, Yanhe

2018-03-15

Besides metabolic pathways and regulatory networks, transport systems are also pivotal for cellular metabolism and hyperproduction of biochemicals using microbial cell factories. The identification and characterization of transporters are therefore of great significance for the understanding and engineering of transport reactions. Herein, a novel l-glutamate exporter, MscCG2, which exists extensively in Corynebacterium glutamicum strains but is distinct from the only known l-glutamate exporter, MscCG, was discovered in an industrial l-glutamate-producing C. glutamicum strain. MscCG2 was predicted to possess three transmembrane helices in the N-terminal region and located in the cytoplasmic membrane, which are typical structural characteristics of the mechanosensitive channel of small conductance. MscCG2 has a low amino acid sequence identity (23%) to MscCG and evolved separately from MscCG with four transmembrane helices. Despite the considerable differences between MscCG2 and MscCG in sequence and structure, gene deletion and complementation confirmed that MscCG2 also functioned as an l-glutamate exporter and an osmotic safety valve in C. glutamicum Besides, transcriptional analysis showed that MscCG2 and MscCG genes were transcribed in similar patterns and not induced by l-glutamate-producing conditions. It was also demonstrated that MscCG2-mediated l-glutamate excretion was activated by biotin limitation or penicillin treatment and that constitutive l-glutamate excretion was triggered by a gain-of-function mutation of MscCG2 (A151V). Discovery of MscCG2 will enrich the understanding of bacterial amino acid transport and provide additional targets for exporter engineering. IMPORTANCE The exchange of matter, energy, and information with surroundings is fundamental for cellular metabolism. Therefore, studying transport systems that are essential for these processes is of great significance. Besides, transport systems of bacterial cells are usually related to

Towards trans-diagnostic mechanisms in psychiatry: neurobehavioral profile of rats with a loss-of-function point mutation in the dopamine transporter gene.

Science.gov (United States)

Vengeliene, Valentina; Bespalov, Anton; Roßmanith, Martin; Horschitz, Sandra; Berger, Stefan; Relo, Ana L; Noori, Hamid R; Schneider, Peggy; Enkel, Thomas; Bartsch, Dusan; Schneider, Miriam; Behl, Berthold; Hansson, Anita C; Schloss, Patrick; Spanagel, Rainer

2017-04-01

The research domain criteria (RDoC) matrix has been developed to reorient psychiatric research towards measurable behavioral dimensions and underlying mechanisms. Here, we used a new genetic rat model with a loss-of-function point mutation in the dopamine transporter (DAT) gene ( Slc6a3 _N157K) to systematically study the RDoC matrix. First, we examined the impact of the Slc6a3 _N157K mutation on monoaminergic signaling. We then performed behavioral tests representing each of the five RDoC domains: negative and positive valence systems, cognitive, social and arousal/regulatory systems. The use of RDoC may be particularly helpful for drug development. We studied the effects of a novel pharmacological approach metabotropic glutamate receptor mGluR2/3 antagonism, in DAT mutants in a comparative way with standard medications. Loss of DAT functionality in mutant rats not only elevated subcortical extracellular dopamine concentration but also altered the balance of monoaminergic transmission. DAT mutant rats showed deficits in all five RDoC domains. Thus, mutant rats failed to show conditioned fear responses, were anhedonic, were unable to learn stimulus-reward associations, showed impaired cognition and social behavior, and were hyperactive. Hyperactivity in mutant rats was reduced by amphetamine and atomoxetine, which are well-established medications to reduce hyperactivity in humans. The mGluR2/3 antagonist LY341495 also normalized hyperactivity in DAT mutant rats without affecting extracellular dopamine levels. We systematically characterized an altered dopamine system within the context of the RDoC matrix and studied mGluR2/3 antagonism as a new pharmacological strategy to treat mental disorders with underlying subcortical dopaminergic hyperactivity. © 2017. Published by The Company of Biologists Ltd.

The Role of a Novel TRMT1 Gene Mutation and Rare GRM1 Gene Defect in Intellectual Disability in Two Azeri Families.

Science.gov (United States)

Davarniya, Behzad; Hu, Hao; Kahrizi, Kimia; Musante, Luciana; Fattahi, Zohreh; Hosseini, Masoumeh; Maqsoud, Fariba; Farajollahi, Reza; Wienker, Thomas F; Ropers, H Hilger; Najmabadi, Hossein

2015-01-01

Cognitive impairment or intellectual disability (ID) is a widespread neurodevelopmental disorder characterized by low IQ (below 70). ID is genetically heterogeneous and is estimated to affect 1-3% of the world's population. In affected children from consanguineous families, autosomal recessive inheritance is common, and identifying the underlying genetic cause is an important issue in clinical genetics. In the framework of a larger project, aimed at identifying candidate genes for autosomal recessive intellectual disorder (ARID), we recently carried out single nucleotide polymorphism-based genome-wide linkage analysis in several families from Ardabil province in Iran. The identification of homozygosity-by-descent loci in these families, in combination with whole exome sequencing, led us to identify possible causative homozygous changes in two families. In the first family, a missense variant was found in GRM1 gene, while in the second family, a frameshift alteration was identified in TRMT1, both of which were found to co-segregate with the disease. GRM1, a known causal gene for autosomal recessive spinocerebellar ataxia (SCAR13, MIM#614831), encodes the metabotropic glutamate receptor1 (mGluR1). This gene plays an important role in synaptic plasticity and cerebellar development. Conversely, the TRMT1 gene encodes a tRNA methyltransferase that dimethylates a single guanine residue at position 26 of most tRNAs using S-adenosyl methionine as the methyl group donor. We recently presented TRMT1 as a candidate gene for ARID in a consanguineous Iranian family (Najmabadi et al., 2011). We believe that this second Iranian family with a biallelic loss-of-function mutation in TRMT1 gene supports the idea that this gene likely has function in development of the disorder.

Time-resolved transcriptome analysis of Bacillus subtilis responding to valine, glutamate, and glutamine.

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Bang-Ce Ye

Full Text Available Microorganisms can restructure their transcriptional output to adapt to environmental conditions by sensing endogenous metabolite pools. In this paper, an Agilent customized microarray representing 4,106 genes was used to study temporal transcript profiles of Bacillus subtilis in response to valine, glutamate and glutamine pulses over 24 h. A total of 673, 835, and 1135 amino-acid-regulated genes were identified having significantly changed expression at one or more time points in response to valine, glutamate, and glutamine, respectively, including genes involved in cell wall, cellular import, metabolism of amino-acids and nucleotides, transcriptional regulation, flagellar motility, chemotaxis, phage proteins, sporulation, and many genes of unknown function. Different amino acid treatments were compared in terms of both the global temporal profiles and the 5-minute quick regulations, and between-experiment differential genes were identified. The highlighted genes were analyzed based on diverse sources of gene functions using a variety of computational tools, including T-profiler analysis, and hierarchical clustering. The results revealed the common and distinct modes of action of these three amino acids, and should help to elucidate the specific signaling mechanism of each amino acid as an effector.

Genome-wide gene-environment study identifies glutamate receptor gene GRIN2A as a Parkinson's disease modifier gene via interaction with coffee.

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Taye H Hamza

2011-08-01

Full Text Available Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD. We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC, and we performed a genome-wide association and interaction study (GWAIS, testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P(2df = 10(-6, GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10(-7 but not in light coffee-drinkers. The a priori Replication hypothesis that "Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers" was confirmed: OR(Replication = 0.59, P(Replication = 10(-3; OR(Pooled = 0.51, P(Pooled = 7×10(-8. Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10(-3, whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10(-13. Imputation revealed a block of SNPs that achieved P(2df<5×10(-8 in GWAIS, and OR = 0.41, P = 3×10(-8 in heavy coffee-drinkers. This study is proof of

Mitochondrial glutamate carriers from Drosophila melanogaster: biochemical, evolutionary and modeling studies.

Science.gov (United States)

Lunetti, Paola; Cappello, Anna Rita; Marsano, René Massimiliano; Pierri, Ciro Leonardo; Carrisi, Chiara; Martello, Emanuela; Caggese, Corrado; Dolce, Vincenza; Capobianco, Loredana

2013-10-01

The mitochondrial carriers are members of a family of transport proteins that mediate solute transport across the inner mitochondrial membrane. Two isoforms of the glutamate carriers, GC1 and GC2 (encoded by the SLC25A22 and SLC25A18 genes, respectively), have been identified in humans. Two independent mutations in SLC25A22 are associated with severe epileptic encephalopathy. In the present study we show that two genes (CG18347 and CG12201) phylogenetically related to the human GC encoding genes are present in the D. melanogaster genome. We have functionally characterized the proteins encoded by CG18347 and CG12201, designated as DmGC1p and DmGC2p respectively, by overexpression in Escherichia coli and reconstitution into liposomes. Their transport properties demonstrate that DmGC1p and DmGC2p both catalyze the transport of glutamate across the inner mitochondrial membrane. Computational approaches have been used in order to highlight residues of DmGC1p and DmGC2p involved in substrate binding. Furthermore, gene expression analysis during development and in various adult tissues reveals that CG18347 is ubiquitously expressed in all examined D. melanogaster tissues, while the expression of CG12201 is strongly testis-biased. Finally, we identified mitochondrial glutamate carrier orthologs in 49 eukaryotic species in order to attempt the reconstruction of the evolutionary history of the glutamate carrier function. Comparison of the exon/intron structure and other key features of the analyzed orthologs suggests that eukaryotic glutamate carrier genes descend from an intron-rich ancestral gene already present in the common ancestor of lineages that diverged as early as bilateria and radiata. © 2013.

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)-glutamic...... demonstrate that incorporation of an additional carbon atom into the backbone of (S)-glutamic acid and its analogues, to give the corresponding homologues, and replacement of the terminal carboxyl groups by isosteric acidic groups have profound effects on the pharmacological profiles at mGlu receptor subtypes...... acid (mGlu) receptors expressed in Chinese hamster ovary cells. 2 (S)-Quisqualic acid was a potent mGlu1/mGlu5 agonist (EC50 values of 1.1 microM and 0.055 microM, respectively) showing no activity at mGlu2 and weak agonism at mGlu4 (EC50 approximately 1000 microM). 3 (S)-Homoquisqualic acid displayed...

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

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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.

Mice lacking glutamate carboxypeptidase II develop normally, but are less susceptible to traumatic brain injury.

Science.gov (United States)

Gao, Yang; Xu, Siyi; Cui, Zhenwen; Zhang, Mingkun; Lin, Yingying; Cai, Lei; Wang, Zhugang; Luo, Xingguang; Zheng, Yan; Wang, Yong; Luo, Qizhong; Jiang, Jiyao; Neale, Joseph H; Zhong, Chunlong

2015-07-01

Glutamate carboxypeptidase II (GCPII) is a transmembrane zinc metallopeptidase found mainly in the nervous system, prostate and small intestine. In the nervous system, glia-bound GCPII mediates the hydrolysis of the neurotransmitter N-acetylaspartylglutamate (NAAG) into glutamate and N-acetylaspartate. Inhibition of GCPII has been shown to attenuate excitotoxicity associated with enhanced glutamate transmission under pathological conditions. However, different strains of mice lacking the GCPII gene are reported to exhibit striking phenotypic differences. In this study, a GCPII gene knockout (KO) strategy involved removing exons 3-5 of GCPII. This generated a new GCPII KO mice line with no overt differences in standard neurological behavior compared to their wild-type (WT) littermates. However, GCPII KO mice were significantly less susceptible to moderate traumatic brain injury (TBI). GCPII gene KO significantly lessened neuronal degeneration and astrocyte damage in the CA2 and CA3 regions of the hippocampus 24 h after moderate TBI. In addition, GCPII gene KO reduced TBI-induced deficits in long-term spatial learning/memory tested in the Morris water maze and motor balance tested via beam walking. Knockout of the GCPII gene is not embryonic lethal and affords histopathological protection with improved long-term behavioral outcomes after TBI, a result that further validates GCPII as a target for drug development consistent with results from studies using GCPII peptidase inhibitors. © 2015 International Society for Neurochemistry.

Cloning and Expression Vector Construction of Glutamate Decarboxylase Gene from Lactobacillus Plantarum

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B Arabpour

2016-06-01

Full Text Available BACKGROUND AND OBJECTIVE: Gamma-aminobutyric acid (GABA is a four-carbon non-protein amino acid used in the treatment of hypertension, diabetes, inflammation, and depression. GABA is synthesized by glutamic acid decarboxylase (GAD enzyme in many organisms, including bacteria. Therefore, cloning of this enzyme is essential to the optimization of GABA production. This study aimed to clone and construct the expression vector of GAD gene from Lactobacillus plantarum PTCC 1058 bacterium. METHODS: In this experimental study, we investigated the morphological, biochemical, genetic and 16s rDNA sequencing of L. plantarum PTCC 1058 strain. Genomic DNA of the bacterium was isolated and amplified using the GAD gene via polymerase chain reaction (PCR. Afterwards, the gene was inserted into the pJET1.2/blunt cloning vector and subcloned in vector pET32a. Plasmid pET32a-gad expression vector was transformed in Escherichia coli BL21 strain, and protein expression was assessed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE. FINDINGS: Morphological, biochemical and genetic analyses of 16s rDNA sequencing indicated that the studied substrain was of the L. plantarum strain. In addition, results of nucleotide sequencing of the fragmented segment via PCR showed the presence of GAD gene. Results of colony PCR and SDS-PAGE analysis confirmed the accuracy of the cloning and gene expression of the recombinant Escherichia coli BL21 strain. CONCLUSION: According to the results of this study, cloning of GAD gene from L. plantarum PTCC 1058 was successful. These cloned genes could grow rapidly in prokaryotic and eukaryotic systems and be used in cost-effective culture media and even non-recyclable waste.

Molecular cloning, expression, and sequence analysis of GPRC6A, a novel family C G-protein-coupled receptor

DEFF Research Database (Denmark)

Wellendorph, Petrine; Bräuner-Osborne, Hans

2004-01-01

with a significant homology to the human calcium-sensing receptor (CaR, 34% aa sequence identity), the taste receptor 1 (T1R1, 28%), and the metabotropic glutamate receptor 1 (mGluR1, 24%), places GPRC6A in family C of the GPCRs. Interestingly, GPRC6A bears the highest resemblance with an odorant goldfish 5...

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

Rescue of Synaptic Phenotypes and Spatial Memory in Young Fragile X Mice.

Science.gov (United States)

Sun, Miao-Kun; Hongpaisan, Jarin; Alkon, Daniel L

2016-05-01

Fragile X syndrome (FXS) is characterized by synaptic immaturity, cognitive impairment, and behavioral changes. The disorder is caused by transcriptional shutdown in neurons of thefragile X mental retardation 1gene product, fragile X mental retardation protein. Fragile X mental retardation protein is a repressor of dendritic mRNA translation and its silencing leads to dysregulation of synaptically driven protein synthesis and impairments of intellect, cognition, and behavior, and FXS is a disorder that currently has no effective therapeutics. Here, young fragile X mice were treated with chronic bryostatin-1, a relatively selective protein kinase Cεactivator, which induces synaptogenesis and synaptic maturation/repair. Chronic treatment with bryostatin-1 rescues young fragile X mice from the disorder phenotypes, including normalization of most FXS abnormalities in 1) hippocampal brain-derived neurotrophic factor expression, 2) postsynaptic density-95 levels, 3) transformation of immature dendritic spines to mature synapses, 4) densities of the presynaptic and postsynaptic membranes, and 5) spatial learning and memory. The therapeutic effects were achieved without downregulation of metabotropic glutamate receptor (mGluR) 5 in the hippocampus and are more dramatic than those of a late-onset treatment in adult fragile X mice. mGluR5 expression was in fact lower in fragile X mice and its expression was restored with the bryostatin-1 treatment. Our results show that synaptic and cognitive function of young FXS mice can be normalized through pharmacological treatment without downregulation of mGluR5 and that bryostatin-1-like agents may represent a novel class of drugs to treat fragile X mental retardation at a young age and in adults. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

The Role of a Novel TRMT1 Gene Mutation and Rare GRM1 Gene Defect in Intellectual Disability in Two Azeri Families.

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Behzad Davarniya

Full Text Available Cognitive impairment or intellectual disability (ID is a widespread neurodevelopmental disorder characterized by low IQ (below 70. ID is genetically heterogeneous and is estimated to affect 1-3% of the world's population. In affected children from consanguineous families, autosomal recessive inheritance is common, and identifying the underlying genetic cause is an important issue in clinical genetics. In the framework of a larger project, aimed at identifying candidate genes for autosomal recessive intellectual disorder (ARID, we recently carried out single nucleotide polymorphism-based genome-wide linkage analysis in several families from Ardabil province in Iran. The identification of homozygosity-by-descent loci in these families, in combination with whole exome sequencing, led us to identify possible causative homozygous changes in two families. In the first family, a missense variant was found in GRM1 gene, while in the second family, a frameshift alteration was identified in TRMT1, both of which were found to co-segregate with the disease. GRM1, a known causal gene for autosomal recessive spinocerebellar ataxia (SCAR13, MIM#614831, encodes the metabotropic glutamate receptor1 (mGluR1. This gene plays an important role in synaptic plasticity and cerebellar development. Conversely, the TRMT1 gene encodes a tRNA methyltransferase that dimethylates a single guanine residue at position 26 of most tRNAs using S-adenosyl methionine as the methyl group donor. We recently presented TRMT1 as a candidate gene for ARID in a consanguineous Iranian family (Najmabadi et al., 2011. We believe that this second Iranian family with a biallelic loss-of-function mutation in TRMT1 gene supports the idea that this gene likely has function in development of the disorder.

The Role of a Novel TRMT1 Gene Mutation and Rare GRM1 Gene Defect in Intellectual Disability in Two Azeri Families

Science.gov (United States)

Kahrizi, Kimia; Musante, Luciana; Fattahi, Zohreh; Hosseini, Masoumeh; Maqsoud, Fariba; Farajollahi, Reza; Wienker, Thomas F.; Ropers, H. Hilger; Najmabadi, Hossein

2015-01-01

Cognitive impairment or intellectual disability (ID) is a widespread neurodevelopmental disorder characterized by low IQ (below 70). ID is genetically heterogeneous and is estimated to affect 1–3% of the world’s population. In affected children from consanguineous families, autosomal recessive inheritance is common, and identifying the underlying genetic cause is an important issue in clinical genetics. In the framework of a larger project, aimed at identifying candidate genes for autosomal recessive intellectual disorder (ARID), we recently carried out single nucleotide polymorphism-based genome-wide linkage analysis in several families from Ardabil province in Iran. The identification of homozygosity-by-descent loci in these families, in combination with whole exome sequencing, led us to identify possible causative homozygous changes in two families. In the first family, a missense variant was found in GRM1 gene, while in the second family, a frameshift alteration was identified in TRMT1, both of which were found to co-segregate with the disease. GRM1, a known causal gene for autosomal recessive spinocerebellar ataxia (SCAR13, MIM#614831), encodes the metabotropic glutamate receptor1 (mGluR1). This gene plays an important role in synaptic plasticity and cerebellar development. Conversely, the TRMT1 gene encodes a tRNA methyltransferase that dimethylates a single guanine residue at position 26 of most tRNAs using S-adenosyl methionine as the methyl group donor. We recently presented TRMT1 as a candidate gene for ARID in a consanguineous Iranian family (Najmabadi et al., 2011). We believe that this second Iranian family with a biallelic loss-of-function mutation in TRMT1 gene supports the idea that this gene likely has function in development of the disorder. PMID:26308914

Integrated Analysis of the Transcriptome and Metabolome of Corynebacterium glutamicum during Penicillin-Induced Glutamic Acid Production.

Science.gov (United States)

Hirasawa, Takashi; Saito, Masaki; Yoshikawa, Katsunori; Furusawa, Chikara; Shmizu, Hiroshi

2018-05-01

Corynebacterium glutamicum is known for its ability to produce glutamic acid and has been utilized for the fermentative production of various amino acids. Glutamic acid production in C. glutamicum is induced by penicillin. In this study, the transcriptome and metabolome of C. glutamicum is analyzed to understand the mechanism of penicillin-induced glutamic acid production. Transcriptomic analysis with DNA microarray revealed that expression of some glycolysis- and TCA cycle-related genes, which include those encoding the enzymes involved in conversion of glucose to 2-oxoglutaric acid, is upregulated after penicillin addition. Meanwhile, expression of some TCA cycle-related genes, encoding the enzymes for conversion of 2-oxoglutaric acid to oxaloacetic acid, and the anaplerotic reactions decreased. In addition, expression of NCgl1221 and odhI, encoding proteins involved in glutamic acid excretion and inhibition of the 2-oxoglutarate dehydrogenase, respectively, is upregulated. Functional category enrichment analysis of genes upregulated and downregulated after penicillin addition revealed that genes for signal transduction systems are enriched among upregulated genes, whereas those for energy production and carbohydrate and amino acid metabolisms are enriched among the downregulated genes. As for the metabolomic analysis using capillary electrophoresis time-of-flight mass spectrometry, the intracellular content of most metabolites of the glycolysis and the TCA cycle decreased dramatically after penicillin addition. Overall, these results indicate that the cellular metabolism and glutamic acid excretion are mainly optimized at the transcription level during penicillin-induced glutamic acid production by C. glutamicum. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancement of γ-aminobutyric acid production in recombinant Corynebacterium glutamicum by co-expressing two glutamate decarboxylase genes from Lactobacillus brevis.

Science.gov (United States)

Shi, Feng; Jiang, Junjun; Li, Yongfu; Li, Youxin; Xie, Yilong

2013-11-01

γ-Aminobutyric acid (GABA), a non-protein amino acid, is a bioactive component in the food, feed and pharmaceutical fields. To establish an effective single-step production system for GABA, a recombinant Corynebacterium glutamicum strain co-expressing two glutamate decarboxylase (GAD) genes (gadB1 and gadB2) derived from Lactobacillus brevis Lb85 was constructed. Compared with the GABA production of the gadB1 or gadB2 single-expressing strains, GABA production by the gadB1-gadB2 co-expressing strain increased more than twofold. By optimising urea supplementation, the total production of L-glutamate and GABA increased from 22.57 ± 1.24 to 30.18 ± 1.33 g L⁻¹, and GABA production increased from 4.02 ± 0.95 to 18.66 ± 2.11 g L⁻¹ after 84-h cultivation. Under optimal urea supplementation, L-glutamate continued to be consumed, GABA continued to accumulate after 36 h of fermentation, and the pH level fluctuated. GABA production increased to a maximum level of 27.13 ± 0.54 g L⁻¹ after 120-h flask cultivation and 26.32 g L⁻¹ after 60-h fed-batch fermentation. The conversion ratio of L-glutamate to GABA reached 0.60-0.74 mol mol⁻¹. By co-expressing gadB1 and gadB2 and optimising the urea addition method, C. glutamicum was genetically improved for de novo biosynthesis of GABA from its own accumulated L-glutamate.

Radiometric microassay for glutamic acid decarboxylase

Energy Technology Data Exchange (ETDEWEB)

Maderdrut, J L [North Carolina Dept. of Mental Health, Raleigh (USA); North Carolina Univ., Chapel Hill (USA). School of Medicine)

1979-01-01

A simple method for purifying L-(/sup 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 ..gamma..-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 ..mu..g. The cation-exchange method is compared with the anion-exchange and CO/sub 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.

Enhanced production of poly glutamic acid by Bacillus sp. SW1-2 ...

African Journals Online (AJOL)

Bacillus sp. SW1-2 producing poly glutamic acid (PGA), locally isolated from Eastern province in Saudi Arabia, was characterized and identified based on 16S rRNA gene sequencing. Phylogenetic analysis revealed its closeness to Bacillus megaterium. The homopolymer consists mainly of glutamic as indicated in the ...

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...

The Pathophysiology of Fragile X (and What It Teaches Us about Synapses)

Science.gov (United States)

Bhakar, Asha L.; Dölen, Gül; Bear, Mark F.

2014-01-01

Fragile X is the most common known inherited cause of intellectual disability and autism, and it typically results from transcriptional silencing of FMR1 and loss of the encoded protein, FMRP (fragile X mental retardation protein). FMRP is an mRNA-binding protein that functions at many synapses to inhibit local translation stimulated by metabotropic glutamate receptors (mGluRs) 1 and 5. Recent studies on the biology of FMRP and the signaling pathways downstream of mGluR1/5 have yielded deeper insight into how synaptic protein synthesis and plasticity are regulated by experience. This new knowledge has also suggested ways that altered signaling and synaptic function can be corrected in fragile X, and human clinical trials based on this information are under way. PMID:22483044

Complex formation between glutamic acid and molybdenum (VI)

International Nuclear Information System (INIS)

Gharib, Farrokh; Khorrami, S.A.; Sharifi, Sasan

1997-01-01

Equilibria of the reaction of molybdenum (VI) with L-glutamic acid have been studied in aqueous solution in the pH range 2.5 to 9.5, using spectrophotometric and optical rotation methods at constant ionic strength (0.15 mol dm -3 sodium perchlorate) and temperature 25 ± 0.1 degC. Our studies have shown that glutamic acid forms a mononuclear complex with Mo(VI) of the type MoO 3 L 2- at pH 5.5. The stability constant of this complexation and the dissociation constants of L-glutamic acid have been determined. (author). 17 refs., 2 figs., 4 tabs

2-Methyl-6-(phenylethynyl pyridine (MPEP reverses maze learning and PSD-95 deficits in Fmr1 knock-out mice.

Directory of Open Access Journals (Sweden)

Réno Michelle Gandhi

2014-03-01

Full Text Available Fragile X syndrome (FXS is caused by the lack of expression of the fragile X mental retardation protein (FMRP, which results in intellectual disability and other debilitating symptoms including impairment of visual-spatial functioning. FXS is the only single-gene disorder that is highly co-morbid with autism spectrum disorder and can therefore provide insight into its pathophysiology. Lack of FMRP results in altered group I metabotropic glutamate receptor (mGluR signalling, which is a target for putative treatments. The Hebb-Williams (H-W mazes are a set of increasingly complex spatial navigation problems that depend on intact hippocampal and thus mGluR-5 functioning. In the present investigation, we examined whether an antagonist of mGluR-5 would reverse previously described behavioural deficits in Fmr1 KO mice. Mice were trained on a subset of the H-W mazes and then treated with either 20 mg/kg of an mGluR-5 antagonist, 2-Methyl-6-(phenylethynyl pyridine (MPEP; n = 11 or an equivalent dose of saline (n = 11 prior to running test mazes. Latency and errors were dependent variables recorded during the test phase. Immediately after completing each test, marble-burying behavior was assessed which confirmed that the drug treatment was pharmacologically active during maze learning. Although latency was not statistically different between the groups, MPEP treated Fmr1 KO mice made significantly fewer errors on mazes deemed more difficult suggesting a reversal of the behavioural deficit. MPEP treated mice were also less perseverative and impulsive when navigating mazes. Furthermore, MPEP treatment reversed PSD-95 protein deficits in Fmr1 KO treated mice, whereas levels of a control protein (β-tubulin remained unchanged. These data further validate MPEP as a potentially beneficial treatment for FXS. Our findings also suggest that adapted H-W mazes may be a useful tool to document alterations in behavioural functioning following pharmacological

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

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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.

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

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Twum eAnsah

2011-06-01

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

AMPK Activation Affects Glutamate Metabolism in Astrocytes

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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...... on glutamate metabolism in astrocytes was studied using primary cultures of these cells from mouse cerebral cortex during incubation in media containing 2.5 mM glucose and 100 µM [U-(13)C]glutamate. The metabolism of glutamate including a detailed analysis of its metabolic pathways involving the tricarboxylic...... 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...

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

Mutual diffusion coefficients of L-glutamic acid and monosodium L-glutamate in aqueous solutions at T = 298.15 K

International Nuclear Information System (INIS)

Ribeiro, Ana C.F.; Rodrigo, M.M.; Barros, Marisa C.F.; Verissimo, Luis M.P.; Romero, Carmen; Valente, Artur J.M.; Esteso, Miguel A.

2014-01-01

Highlights: • Interdiffusion coefficients of L-glutamic acid and sodium L-glutamate were measured. • The L-glutamic acid behaves as a monoprotic weak acid. • The sodium L-glutamate shows a symmetrical 1:1 non-associated behaviour. • Limiting diffusion coefficients and ionic conductivities were estimated. • Diffusion coefficients were discussed on the basis of the Onsager–Fuoss equations. - Abstract: Mutual diffusion coefficient values for binary aqueous solutions of both L-glutamic acid (H 2 Glu) and sodium L-glutamate (NaHGlu) were measured with the Taylor dispersion technique, at T = 298.15 K, and concentrations ranging from (0.001 to 0.100) mol · dm −3 . The results were discussed on the basis of the Onsager–Fuoss and the Nernst theoretical equations, by considering the H 2 Glu as a weak acid (monoprotic acid, with K 2 = 5.62 · 10 −5 ). The smaller values found for the acid with respect to those of the salt, confirm this association hypothesis. From the diffusion coefficient values at infinitesimal concentration, limiting ionic conductivities as well as the hydrodynamic radius of the hydrogen glutamate ion (HGlu − ) were derived and analyzed in terms of the chain methylene groups. The effect of different phenomena, such as association or complexation, were also taken into consideration and discussed. Values for the dissociation degree for H 2 Glu were also estimated

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...

Genome-Wide Gene-Environment Study Identifies Glutamate Receptor Gene GRIN2A as a Parkinson's Disease Modifier Gene via Interaction with Coffee

Science.gov (United States)

Hamza, Taye H.; Chen, Honglei; Hill-Burns, Erin M.; Rhodes, Shannon L.; Montimurro, Jennifer; Kay, Denise M.; Tenesa, Albert; Kusel, Victoria I.; Sheehan, Patricia; Eaaswarkhanth, Muthukrishnan; Yearout, Dora; Samii, Ali; Roberts, John W.; Agarwal, Pinky; Bordelon, Yvette; Park, Yikyung; Wang, Liyong; Gao, Jianjun; Vance, Jeffery M.; Kendler, Kenneth S.; Bacanu, Silviu-Alin; Scott, William K.; Ritz, Beate; Nutt, John; Factor, Stewart A.; Zabetian, Cyrus P.; Payami, Haydeh

2011-01-01

Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD). We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC), and we performed a genome-wide association and interaction study (GWAIS), testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS) in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication) were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P2df = 10−6, GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10−7) but not in light coffee-drinkers. The a priori Replication hypothesis that “Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers” was confirmed: ORReplication = 0.59, PReplication = 10−3; ORPooled = 0.51, PPooled = 7×10−8. Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10−3), whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10−13). Imputation revealed a block of SNPs that achieved P2dfcoffee-drinkers. This study is proof of concept that inclusion of environmental factors can help identify genes that

Genome-wide gene-environment study identifies glutamate receptor gene GRIN2A as a Parkinson's disease modifier gene via interaction with coffee.

Science.gov (United States)

Hamza, Taye H; Chen, Honglei; Hill-Burns, Erin M; Rhodes, Shannon L; Montimurro, Jennifer; Kay, Denise M; Tenesa, Albert; Kusel, Victoria I; Sheehan, Patricia; Eaaswarkhanth, Muthukrishnan; Yearout, Dora; Samii, Ali; Roberts, John W; Agarwal, Pinky; Bordelon, Yvette; Park, Yikyung; Wang, Liyong; Gao, Jianjun; Vance, Jeffery M; Kendler, Kenneth S; Bacanu, Silviu-Alin; Scott, William K; Ritz, Beate; Nutt, John; Factor, Stewart A; Zabetian, Cyrus P; Payami, Haydeh

2011-08-01

Our aim was to identify genes that influence the inverse association of coffee with the risk of developing Parkinson's disease (PD). We used genome-wide genotype data and lifetime caffeinated-coffee-consumption data on 1,458 persons with PD and 931 without PD from the NeuroGenetics Research Consortium (NGRC), and we performed a genome-wide association and interaction study (GWAIS), testing each SNP's main-effect plus its interaction with coffee, adjusting for sex, age, and two principal components. We then stratified subjects as heavy or light coffee-drinkers and performed genome-wide association study (GWAS) in each group. We replicated the most significant SNP. Finally, we imputed the NGRC dataset, increasing genomic coverage to examine the region of interest in detail. The primary analyses (GWAIS, GWAS, Replication) were performed using genotyped data. In GWAIS, the most significant signal came from rs4998386 and the neighboring SNPs in GRIN2A. GRIN2A encodes an NMDA-glutamate-receptor subunit and regulates excitatory neurotransmission in the brain. Achieving P(2df) = 10(-6), GRIN2A surpassed all known PD susceptibility genes in significance in the GWAIS. In stratified GWAS, the GRIN2A signal was present in heavy coffee-drinkers (OR = 0.43; P = 6×10(-7)) but not in light coffee-drinkers. The a priori Replication hypothesis that "Among heavy coffee-drinkers, rs4998386_T carriers have lower PD risk than rs4998386_CC carriers" was confirmed: OR(Replication) = 0.59, P(Replication) = 10(-3); OR(Pooled) = 0.51, P(Pooled) = 7×10(-8). Compared to light coffee-drinkers with rs4998386_CC genotype, heavy coffee-drinkers with rs4998386_CC genotype had 18% lower risk (P = 3×10(-3)), whereas heavy coffee-drinkers with rs4998386_TC genotype had 59% lower risk (P = 6×10(-13)). Imputation revealed a block of SNPs that achieved P(2df)coffee-drinkers. This study is proof of concept that inclusion of environmental factors can help identify

Genomic analysis of Bacillus subtilis lytic bacteriophage ϕNIT1 capable of obstructing natto fermentation carrying genes for the capsule-lytic soluble enzymes poly-γ-glutamate hydrolase and levanase.

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Ozaki, Tatsuro; Abe, Naoki; Kimura, Keitarou; Suzuki, Atsuto; Kaneko, Jun

2017-01-01

Bacillus subtilis strains including the fermented soybean (natto) starter produce capsular polymers consisting of poly-γ-glutamate and levan. Capsular polymers may protect the cells from phage infection. However, bacteriophage ϕNIT1 carries a γ-PGA hydrolase gene (pghP) that help it to counteract the host cell's protection strategy. ϕNIT had a linear double stranded DNA genome of 155,631-bp with a terminal redundancy of 5,103-bp, containing a gene encoding an active levan hydrolase. These capsule-lytic enzyme genes were located in the possible foreign gene cluster regions between central core and terminal redundant regions, and were expressed at the late phase of the phage lytic cycle. All tested natto origin Spounavirinae phages carried both genes for capsule degrading enzymes similar to ϕNIT1. A comparative genomic analysis revealed the diversity among ϕNIT1 and Bacillus phages carrying pghP-like and levan-hydrolase genes, and provides novel understanding on the acquisition mechanism of these enzymatic genes.

Distinct roles of two anaplerotic pathways in glutamate production induced by biotin limitation in Corynebacterium glutamicum.

Science.gov (United States)

Sato, Hiroki; Orishimo, Keita; Shirai, Tomokazu; Hirasawa, Takashi; Nagahisa, Keisuke; Shimizu, Hiroshi; Wachi, Masaaki

2008-07-01

Corynebacterium glutamicum is a biotin auxotrophic bacterium in which glutamate production is induced under biotin-limited conditions. During glutamate production, anaplerotic reactions catalyzed by phosphoenolpyruvate carboxylase (PEPC) and a biotin-containing enzyme pyruvate carboxylase (PC) are believed to play an important role in supplying oxaloacetate in the tricarboxylic acid cycle. To understand the distinct roles of PEPC and PC on glutamate production by C. glutamicum, we observed glutamate production induced under biotin-limited conditions in the disruptants of the genes encoding PEPC (ppc) and PC (pyc), respectively. The pyc disruptant retained the ability to produce high amounts of glutamate, and lactate was simultaneously produced probably due to the increased intracellular pyruvate levels. On the other hand, the ppc knockout mutant could not produce glutamate. Additionally, glutamate production in the pyc disruptant was enhanced by overexpression of ppc rather than disruption of the lactate dehydrogenase gene (ldh), which is involved in lactate production. Metabolic flux analysis based on the 13C-labeling experiment and measurement of 13C-enrichment in glutamate using nuclear magnetic resonance spectroscopy revealed that the flux for anaplerotic reactions in the pyc disruptant was lower than that in the wild type, concomitantly increasing the flux for lactate formation. Moreover, overexpression of ppc increased this flux in both the pyc disruptant and the wild type. Our results suggest that the PEPC-catalyzed anaplerotic reaction is necessary for glutamate production induced under biotin-limited conditions, because PC is not active during glutamate production, and overexpression of ppc effectively enhances glutamate production under biotin-limited conditions.

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)

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

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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

The phosphorylation status and cytoskeletal remodeling of striatal astrocytes treated with quinolinic acid

International Nuclear Information System (INIS)

Pierozan, Paula; Ferreira, Fernanda; Ortiz de Lima, Bárbara; Gonçalves Fernandes, Carolina; Totarelli Monteforte, Priscila; Castro Medaglia, Natalia de; Bincoletto, Claudia; Soubhi Smaili, Soraya; Pessoa-Pureur, Regina

2014-01-01

Quinolinic acid (QUIN) is a glutamate agonist which markedly enhances the vulnerability of neural cells to excitotoxicity. QUIN is produced from the amino acid tryptophan through the kynurenine pathway (KP). Dysregulation of this pathway is associated with neurodegenerative conditions. In this study we treated striatal astrocytes in culture with QUIN and assayed the endogenous phosphorylating system associated with glial fibrillary acidic protein (GFAP) and vimentin as well as cytoskeletal remodeling. After 24 h incubation with 100 µM QUIN, cells were exposed to 32 P-orthophosphate and/or protein kinase A (PKA), protein kinase dependent of Ca 2+ /calmodulin II (PKCaMII) or protein kinase C (PKC) inhibitors, H89 (20 μM), KN93 (10 μM) and staurosporin (10 nM), respectively. Results showed that hyperphosphorylation was abrogated by PKA and PKC inhibitors but not by the PKCaMII inhibitor. The specific antagonists to ionotropic NMDA and non-NMDA (50 µM DL-AP5 and CNQX, respectively) glutamate receptors as well as to metabotropic glutamate receptor (mGLUR; 50 µM MCPG), mGLUR1 (100 µM MPEP) and mGLUR5 (10 µM 4C3HPG) prevented the hyperphosphorylation provoked by QUIN. Also, intra and extracellular Ca 2+ quelators (1 mM EGTA; 10 µM BAPTA-AM, respectively) prevented QUIN-mediated effect, while Ca 2+ influx through voltage-dependent Ca 2+ channel type L (L-VDCC) (blocker: 10 µM verapamil) is not implicated in this effect. Morphological analysis showed dramatically altered actin cytoskeleton with concomitant change of morphology to fusiform and/or flattened cells with retracted cytoplasm and disruption of the GFAP meshwork, supporting misregulation of actin cytoskeleton. Both hyperphosphorylation and cytoskeletal remodeling were reversed 24 h after QUIN removal. Astrocytes are highly plastic cells and the vulnerability of astrocyte cytoskeleton may have important implications for understanding the neurotoxicity of QUIN in neurodegenerative disorders. - Highlights: �

CCL5–Glutamate Cross-Talk in Astrocyte-Neuron Communication in Multiple Sclerosis

Directory of Open Access Journals (Sweden)

Anna Pittaluga

2017-09-01

Full Text Available The immune system (IS and the central nervous system (CNS are functionally coupled, and a large number of endogenous molecules (i.e., the chemokines for the IS and the classic neurotransmitters for the CNS are shared in common between the two systems. These interactions are key elements for the elucidation of the pathogenesis of central inflammatory diseases. In recent years, evidence has been provided supporting the role of chemokines as modulators of central neurotransmission. It is the case of the chemokines CCL2 and CXCL12 that control pre- and/or post-synaptically the chemical transmission. This article aims to review the functional cross-talk linking another endogenous pro-inflammatory factor released by glial cells, i.e., the chemokine Regulated upon Activation Normal T-cell Expressed and Secreted (CCL5 and the principal neurotransmitter in CNS (i.e., glutamate in physiological and pathological conditions. In particular, the review discusses preclinical data concerning the role of CCL5 as a modulator of central glutamatergic transmission in healthy and demyelinating disorders. The CCL5-mediated control of glutamate release at chemical synapses could be relevant either to the onset of psychiatric symptoms that often accompany the development of multiple sclerosis (MS, but also it might indirectly give a rationale for the progression of inflammation and demyelination. The impact of disease-modifying therapies for the cure of MS on the endogenous availability of CCL5 in CNS will be also summarized. We apologize in advance for omission in our coverage of the existing literature.

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.

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

2005-04-01

The present study has examined the anticonvulsant and neuroprotective effect of group II metabotropic glutamate receptor (mGluR) agonist (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC) in the model of seizures induced in immature 12-day-old rats by bilateral intracerebroventricular infusion of dl-homocysteic acid (DL-HCA, 600 nmol/side). For biochemical analyses, rat pups were sacrificed during generalized clonic-tonic seizures, approximately 45-50 min after infusion. Comparable time intervals were used for sacrificing the pups which had received 2R,4R-APDC. Low doses of 2R,4R-APDC (0.05 nmol/side) provided a pronounced anticonvulsant effect which was abolished by pretreatment with a selective group II mGluR antagonist LY341495. Generalized clonic-tonic seizures were completely suppressed and cortical energy metabolite changes which normally accompany these seizures were either normalized (decrease of glucose and glycogen) or markedly reduced (an accumulation of lactate). EEG recordings support the marked anticonvulsant effect of 2R,4R-APDC, nevertheless, this was only partial. In spite of the absence of obvious motor phenomena, isolated spikes or even short periods of partial ictal activity could be observed. Isolated spikes could also be seen in some animals after application of 2R,4R-APDC alone, reflecting most likely subclinical proconvulsant activity of this agonist. The neuroprotective effect of 2R,4R-APDC was evaluated after 24 h and 6 days of survival following DL-HCA-induced seizures. Massive neuronal degeneration, as revealed by Fluoro-Jade B staining, was observed in a number of brain regions following infusion of DL-HCA alone (seizure group), whereas 2R,4R-APDC pretreatment provided substantial neuroprotection. The present findings support the possibility that group II mGluRs are a promising target for a novel approach to treating epilepsy.

Central N-acetyl aspartylglutamate deficit: a possible pathogenesis of schizophrenia.

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Tsai, Shih-Jen

2005-09-01

The "glutamate hypothesis" of schizophrenia has emerged from the finding that phencyclidine (PCP) induces psychotic-like behaviors in rodents, possibly by blocking the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor, thereby causing increased glutamate release. N-acetyl aspartylglutamate (NAAG), an endogenous peptide abundant in mammalian nervous systems, is localized in certain brain cells, including cortical and hippocampal pyramidal neurons. NAAG is synthesized from N-acetylaspartate (NAA) and glutamate, and NAA availability may limit the rate of NAAG synthesis. Although NAAG is known to have some neurotransmitter-like functions, NAA does not. NAAG is a highly selective agonist of the type 3 metabotropic glutamate receptor (mGluR3, a presynaptic autoreceptor) and can inhibit glutamate release. In addition, at low levels, NAAG is an NMDA receptor antagonist, and blocking of NMDA receptors may increase glutamate release. Taken together, low central NAAG levels may antagonize the effect of glutamate at NMDA receptors and decrease its agonistic effect on presynaptic mGluR3; both activities could increase glutamate release, similar to the increase demonstrated in the PCP model of schizophrenia. In this report, it is suggested that the central NAAG deficit, possibly through decreased synthesis or increased degradation of NAAG, may play a role in the pathogenesis of schizophrenia. Evidence is presented and discussed from magnetic resonance, postmortem, animal model, schizophrenia treatment, and genetic studies. The central NAAG deficit model of schizophrenia could explain the disease process, from the perspectives of both neurodevelopment and neurodegeneration, and may point to potential treatments for schizophrenia.

The effect of pH and ADP on ammonia affinity for human glutamate dehydrogenases

DEFF Research Database (Denmark)

Zaganas, Ioannis; Pajecka, Kamilla; Nielsen, Camilla Wendel

2013-01-01

Glutamate dehydrogenase (GDH) uses ammonia to reversibly convert α-ketoglutarate to glutamate using NADP(H) and NAD(H) as cofactors. While GDH in most mammals is encoded by a single GLUD1 gene, humans and other primates have acquired a GLUD2 gene with distinct tissue expression profile. The two...... human isoenzymes (hGDH1 and hGDH2), though highly homologous, differ markedly in their regulatory properties. Here we obtained hGDH1 and hGDH2 in recombinant form and studied their Km for ammonia in the presence of 1.0 mM ADP. The analyses showed that lowering the pH of the buffer (from 8.0 to 7.......0) increased the Km for ammonia substantially (hGDH1: from 12.8 ± 1.4 mM to 57.5 ± 1.6 mM; hGDH2: from 14.7 ± 1.6 mM to 62.2 ± 1.7 mM), thus essentially precluding reductive amination. Moreover, lowering the ADP concentration to 0.1 mM not only increased the K0.5 [NH4 (+)] of hGDH2, but also introduced...

Subtype selective kainic acid receptor agonists

DEFF Research Database (Denmark)

Bunch, Lennart; Krogsgaard-Larsen, Povl

2009-01-01

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

Association of a missense mutation in the positional candidate gene glutamate receptor-interacting protein 1 with backfat thickness traits in pigs

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Jae-Bong Lee

2017-08-01

Full Text Available Objective Previously, we reported quantitative trait loci (QTLs affecting backfat thickness (BFT traits on pig chromosome 5 (SW1482–SW963 in an F2 intercross population between Landrace and Korean native pigs. The aim of this study was to evaluate glutamate receptor-interacting protein 1 (GRIP1 as a positional candidate gene underlying the QTL affecting BFT traits. Methods Genotype and phenotype analyses were performed using the 1,105 F2 progeny. A mixed-effect linear model was used to access association between these single nucleotide polymorphism (SNP markers and the BFT traits in the F2 intercross population. Results Highly significant associations of two informative SNPs (c.2442 T>C, c.3316 C>G [R1106G] in GRIP1 with BFT traits were detected. In addition, the two SNPs were used to construct haplotypes that were also highly associated with the BFT traits. Conclusion The SNPs and haplotypes of the GRIP1 gene determined in this study can contribute to understand the genetic structure of BFT traits in pigs.

Development of GPCR modulation of GABAergic transmission in chicken nucleus laminaris neurons.

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Zheng-Quan Tang

Full Text Available Neurons in the nucleus laminaris (NL of birds act as coincidence detectors and encode interaural time difference to localize the sound source in the azimuth plane. GABAergic transmission in a number of CNS nuclei including the NL is subject to a dual modulation by presynaptic GABA(B receptors (GABA(BRs and metabotropic glutamate receptors (mGluRs. Here, using in vitro whole-cell patch clamp recordings from acute brain slices of the chick, we characterized the following important but unknown properties pertaining to such a dual modulation: (1 emergence of functional GABA synapses in NL neurons; (2 the temporal onset of neuromodulation mediated by GABA(BRs and mGluRs; and (3 the physiological conditions under which GABA(BRs and mGluRs are activated by endogenous transmitters. We found that (1 GABA(AR-mediated synaptic responses were observed in about half of the neurons at embryonic day 11 (E11; (2 GABA(BR-mediated modulation of the GABAergic transmission was detectable at E11, whereas the modulation by mGluRs did not emerge until E15; and (3 endogenous activity of GABA(BRs was induced by both low- (5 or 10 Hz and high-frequency (200 Hz stimulation of the GABAergic pathway, whereas endogenous activity of mGluRs was induced by high- (200 Hz but not low-frequency (5 or 10 Hz stimulation of the glutamatergic pathway. Furthermore, the endogenous activity of mGluRs was mediated by group II but not group III members. Therefore, autoreceptor-mediated modulation of GABAergic transmission emerges at the same time when the GABA synapses become functional. Heteroreceptor-mediated modulation appears at a later time and is receptor type dependent in vitro.

Mammalian folylpoly-γ-glutamate synthetase. 2. Substrate specificity and kinetic properties

International Nuclear Information System (INIS)

Cichowicz, D.J.; Shane, B.

1987-01-01

The specificity of hog liver folylpolyglutamate synthetase for folate substrates and for nucleotide and L-[ 14 C]glutamate substrates and analogues has been investigated. The kinetic mechanism, determined by using aminopterin as the folate substrate, is ordered Ter-Ter with MgATP binding first, folate second, and glutamate last. This mechanism precludes the sequential addition of glutamate moieties to enzyme-bound folate. Folate, dihydrofolate, and tetrahydrofolate possess the optimal configurations for catalysis while 5- and 10-position substitutions of the folate molecule impair catalysis. k/sub cat/ values decrease with increasing glutamate chain length, and the rate of decrease varies depending on the state of reduction and substitution of the folate molecule. Folate binding, as assessed by on rates, is slow. Dihydrofolate exhibits the fastest rate, and the rates are slightly reduced for tetrahydrofolate and 10-formyltetrahydrofolate and greatly reduced for 5-methyltetrahydrofolate and folic acid. Tetrahydrofolate polyglutamates are the only long glutamate chain length folates with detectable substrate activity. The specificity of the L-glutamate binding site is very narrow. L-Homocysteate and 4-threo-fluoroglutamate are alternate substrates and act as chain termination inhibitors in that their addition to the folate molecule prevents or severely retards the further addition of glutamate moieties. The K/sub m/ for glutamate is dependent on the folate substrate used. MgATP is the preferred nucleotide substrate, and β,γ-methylene-ATP, β,γ-imido-ATP, adenosine 5'-O-(3-thiotriphosphate), P 1 ,P 5 -di(adenosine-5') pentaphosphate, and free ATP 4- are potent inhibitors of the reaction

Synaptically evoked glutamate transporter currents in Spinal Dorsal Horn Astrocytes

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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.

Direct and indirect effects of RNA interference against pyridoxal kinase and pyridoxine 5'-phosphate oxidase genes in Bombyx mori.

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Huang, ShuoHao; Yao, LiLi; Zhang, JianYun; Huang, LongQuan

2016-08-01

Vitamin B6 comprises six interconvertible pyridine compounds (vitamers), among which pyridoxal 5'-phosphate is a coenzyme involved in a high diversity of biochemical reactions. Humans and animals obtain B6 vitamers from diet, and synthesize pyridoxal 5'-phosphate by pyridoxal kinase and pyridoxine 5'-phosphate oxidase. Currently, little is known on how pyridoxal 5'-phosphate biosynthesis is regulated, and pyridoxal 5'-phosphate is supplied to meet their requirement in terms of cofactor. Bombyx mori is a large silk-secreting insect, in which protein metabolism is most active, and the vitamin B6 demand is high. In this study, we successfully down-regulated the gene expression of pyridoxal kinase and pyridoxine 5'-phosphate oxidase by body cavity injection of synthesized double-stranded small interfering RNA to 5th instar larvae of Bombyx mori, and analyzed the gene transcription levels of pyridoxal 5'-phosphate dependent enzymes, phosphoserine aminotransferase and glutamic-oxaloacetic transaminase. Results show that the gene expression of pyridoxal kinase and pyridoxine 5'-phosphate oxidase has a greater impact on the gene transcription of enzymes using pyridoxal 5'-phosphate as a cofactor in Bombyx mori. Our study suggests that pyridoxal 5'-phosphate biosynthesis and dynamic balance may be regulated by genetic networks. Copyright © 2016 Elsevier B.V. All rights reserved.

Blood Glutamate Scavenging: Insight into Neuroprotection

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Alexander Zlotnik

2012-08-01

Full Text Available 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 brain interstitial fluids by making use of the naturally occurring brain-to-blood glutamate efflux has been shown to be effective in various animal studies. This is facilitated by gradient driven transport across brain capillary endothelial glutamate transporters. Blood glutamate scavengers enhance this naturally occurring mechanism by reducing the blood glutamate concentration, thus increasing the rate at which excess glutamate is cleared. Blood glutamate scavenging is achieved by several mechanisms including: catalyzation of the enzymatic process involved in glutamate metabolism, redistribution of glutamate into tissue, and acute stress response. Regardless of the mechanism involved, decreased blood glutamate concentration is associated with improved neurological outcome. This review focuses on the physiological, mechanistic and clinical roles of blood glutamate scavenging, particularly in the context of acute and chronic CNS injury. We discuss the details of brain-to-blood glutamate efflux, auto-regulation mechanisms of blood glutamate, natural and exogenous blood glutamate scavenging systems, and redistribution of glutamate. We then propose different applied methodologies to reduce blood and brain glutamate concentrations and discuss the neuroprotective role of blood glutamate scavenging.

Effects of phosphoenolpyruvate carboxylase desensitization on glutamic acid production in Corynebacterium glutamicum ATCC 13032.

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Wada, Masaru; Sawada, Kazunori; Ogura, Kotaro; Shimono, Yuta; Hagiwara, Takuya; Sugimoto, Masakazu; Onuki, Akiko; Yokota, Atsushi

2016-02-01

Phosphoenolpyruvate carboxylase (PEPC) in Corynebacterium glutamicum ATCC13032, a glutamic-acid producing actinobacterium, is subject to feedback inhibition by metabolic intermediates such as aspartic acid and 2-oxoglutaric acid, which implies the importance of PEPC in replenishing oxaloacetic acid into the TCA cycle. Here, we investigated the effects of feedback-insensitive PEPC on glutamic acid production. A single amino-acid substitution in PEPC, D299N, was found to relieve the feedback control by aspartic acid, but not by 2-oxoglutaric acid. A simple mutant, strain R1, having the D299N substitution in PEPC was constructed from ATCC 13032 using the double-crossover chromosome replacement technique. Strain R1 produced glutamic acid at a concentration of 31.0 g/L from 100 g/L glucose in a jar fermentor culture under biotin-limited conditions, which was significantly higher than that of the parent, 26.0 g/L (1.19-fold), indicative of the positive effect of desensitized PEPC on glutamic acid production. Another mutant, strain DR1, having both desensitized PEPC and PYK-gene deleted mutations, was constructed in a similar manner using strain D1 with a PYK-gene deleted mutation as the parent. This mutation had been shown to enhance glutamic acid production in our previous study. Although marginal, strain D1 produced higher glutamic acid, 28.8 g/L, than ATCC13032 (1.11-fold). In contrast, glutamic acid production by strain DR-1 was elevated up to 36.9 g/L, which was 1.42-fold higher than ATCC13032 and significantly higher than the other three strains. The results showed a synergistic effect of these two mutations on glutamic acid production in C. glutamicum. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Functional identification of glutamate cysteine ligase and glutathione synthetase in the marine yeast Rhodosporidium diobovatum

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Kong, Min; Wang, Fengjuan; Tian, Liuying; Tang, Hui; Zhang, Liping

2018-02-01

Glutathione (GSH) fulfills a variety of metabolic functions, participates in oxidative stress response, and defends against toxic actions of heavy metals and xenobiotics. In this study, GSH was detected in Rhodosporidium diobovatum by high-performance liquid chromatography (HPLC). Then, two novel enzymes from R. diobovatum were characterized that convert glutamate, cysteine, and glycine into GSH. Based on reverse transcription PCR, we obtained the glutathione synthetase gene ( GSH2), 1866 bp, coding for a 56.6-kDa protein, and the glutamate cysteine ligase gene ( GSH1), 2469 bp, coding for a 90.5-kDa protein. The role of GSH1 and GSH2 for the biosynthesis of GSH in the marine yeast R. diobovatum was determined by deletions using the CRISPR-Cas9 nuclease system and enzymatic activity. These results also showed that GSH1 and GSH2 were involved in the production of GSH and are thus being potentially useful to engineer GSH pathways. Alternatively, pET- GSH constructed using vitro recombination could be used to detect the function of genes related to GSH biosynthesis. Finally, the fermentation parameters determined in the present study provide a reference for industrial GSH production in R. diobovatum.

Mutations of the Corynebacterium glutamicum NCgl1221 Gene, Encoding a Mechanosensitive Channel Homolog, Induce l-Glutamic Acid Production▿

OpenAIRE

Nakamura, Jun; Hirano, Seiko; Ito, Hisao; Wachi, Masaaki

2007-01-01

Corynebacterium glutamicum is a biotin auxotroph that secretes l-glutamic acid in response to biotin limitation; this process is employed in industrial l-glutamic acid production. Fatty acid ester surfactants and penicillin also induce l-glutamic acid secretion, even in the presence of biotin. However, the mechanism of l-glutamic acid secretion remains unclear. It was recently reported that disruption of odhA, encoding a subunit of the 2-oxoglutarate dehydrogenase complex, resulted in l-gluta...

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

-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...

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.

GRP1 PH Domain, Like AKT1 PH Domain, Possesses a Sentry Glutamate Residue Essential for Specific Targeting to Plasma Membrane PI(3,4,5)P3

Science.gov (United States)

Pilling, Carissa; Landgraf, Kyle E.; Falke, Joseph J.

2011-01-01

During the appearance of the signaling lipid PI(3,4,5)P3, an important subset of pleckstrin homology (PH) domains target signaling proteins to the plasma membrane. To ensure proper pathway regulation, such PI(3,4,5)P3-specific PH domains must exclude the more prevalant, constitutive plasma membrane lipid PI(4,5)P2 and bind the rare PI(3,4,5)P3 target lipid with sufficiently high affinity. Our previous study of the E17K mutant of protein kinase B (AKT1) PH domain, together with evidence from Carpten et al (1), revealed that the native AKT1 E17 residue serves as a sentry glutamate that excludes PI(4,5)P2, thereby playing an essential role in specific PI(3,4,5)P3 targeting (2). The sentry glutamate hypothesis proposes that an analogous sentry glutamate residue is a widespread feature of PI(3,4,5)P3-specific PH domains, and that charge reversal mutation at the sentry glutamate position will yield both increased PI(4,5)P2 affinity and constitutive plasma membrane targeting. To test this hypothesis the present study investigates the E345 residue, a putative sentry glutamate, of General Receptor for Phosphoinositides 1 (GRP1) PH domain. The results show that incorporation of the E345K charge reversal mutation into GRP1 PH domain enhances PI(4,5)P2 affinity 8-fold and yields constitutive plasma membrane targeting in cells, reminiscent of the effects of the E17K mutation in AKT1 PH domain. Hydrolysis of plasma membrane PI(4,5)P2 releases E345K GRP1 PH domain into the cytoplasm and the efficiency of this release increases when target Arf6 binding is disrupted. Overall, the findings provide strong support for the sentry glutamate hypothesis and suggest that the GRP1 E345K mutation will be linked to changes in cell physiology and human pathologies, as demonstrated for AKT1 E17K (1, 3). Analysis of available PH domain structures suggests that a lone glutamate residue (or, in some cases an aspartate) is a common, perhaps ubiquitous, feature of PI(3,4,5)P3-specific binding

Neuromodulatory Effect of Thymoquinone in Attenuating Glutamate-Mediated Neurotoxicity Targeting the Amyloidogenic and Apoptotic Pathways

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Ibram Amin Fouad

2018-04-01

Full Text Available Overexposure of the glutamatergic N-methyl-d-aspartate (NMDA receptor to the excitatory neurotransmitter l-glutamic acid leads to neuronal cell death by excitotoxicity as a result of increased intracellular Ca2+, mitochondrial dysfunction, and apoptosis. Moreover, it was previously reported that prolonged activation of the NMDA receptor increased beta-amyloid (Aβ levels in the brain. Thymoquinone (TQ, the active constituent of Nigella sativa seeds, has been shown to have potent antioxidant and antiapoptotic effects. The aim of the present study was to explore the neuromodulatory effects of different doses of TQ (2.5 and 10 mg/kg against apoptotic cell death and Aβ formation resulting from glutamate administration in rats using vitamin E as a positive control. Behavioral changes were assessed using Y-maze and Morris water maze tests for evaluating spatial memory and cognitive functions. Caspase-3, Lactate dehydrogenase, Aβ-42, and cytochrome c gene expression were determined. TQ-treated groups showed significant decreases in the levels of all tested biochemical and behavioral parameters compared with the glutamate-treated group. These findings demonstrated that TQ has a promising neuroprotective activity against glutamate-induced neurotoxicity and this effect is mediated through its anti-amyloidogenic, antioxidant, and antiapoptotic activities.

The glutamate/GABA-glutamine cycle

DEFF Research Database (Denmark)

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

2006-01-01

Neurons are metabolically handicapped in the sense that they are not able to perform de novo synthesis of neurotransmitter glutamate and gamma-aminobutyric acid (GABA) from glucose. A metabolite shuttle known as the glutamate/GABA-glutamine cycle describes the release of neurotransmitter glutamate...... 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...

Overrepresentation of glutamate signaling in Alzheimer's disease: network-based pathway enrichment using meta-analysis of genome-wide association studies.

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Eduardo Pérez-Palma

Full Text Available Genome-wide association studies (GWAS have successfully identified several risk loci for Alzheimer's disease (AD. Nonetheless, these loci do not explain the entire susceptibility of the disease, suggesting that other genetic contributions remain to be identified. Here, we performed a meta-analysis combining data of 4,569 individuals (2,540 cases and 2,029 healthy controls derived from three publicly available GWAS in AD and replicated a broad genomic region (>248,000 bp associated with the disease near the APOE/TOMM40 locus in chromosome 19. To detect minor effect size contributions that could help to explain the remaining genetic risk, we conducted network-based pathway analyses either by extracting gene-wise p-values (GW, defined as the single strongest association signal within a gene, or calculated a more stringent gene-based association p-value using the extended Simes (GATES procedure. Comparison of these strategies revealed that ontological sub-networks (SNs involved in glutamate signaling were significantly overrepresented in AD (p<2.7×10(-11, p<1.9×10(-11; GW and GATES, respectively. Notably, glutamate signaling SNs were also found to be significantly overrepresented (p<5.1×10(-8 in the Alzheimer's disease Neuroimaging Initiative (ADNI study, which was used as a targeted replication sample. Interestingly, components of the glutamate signaling SNs are coordinately expressed in disease-related tissues, which are tightly related to known pathological hallmarks of AD. Our findings suggest that genetic variation within glutamate signaling contributes to the remaining genetic risk of AD and support the notion that functional biological networks should be targeted in future therapies aimed to prevent or treat this devastating neurological disorder.

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

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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.

Regulation of glutamate transporter 1 (GLT-1) gene expression by cocaine self-administration and withdrawal.

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Kim, Ronald; Sepulveda-Orengo, Marian T; Healey, Kati L; Williams, Emily A; Reissner, Kathryn J

2018-01-01

Downregulation of the astroglial glutamate transporter GLT-1 is observed in the nucleus accumbens (NAc) following administration of multiple drugs of abuse. The decrease in GLT-1 protein expression following cocaine self-administration is dependent on both the amount of cocaine self-administered and the length of withdrawal, with longer access to cocaine and longer withdrawal periods leading to greater decreases in GLT-1 protein. However, the mechanism(s) by which cocaine downregulates GLT-1 protein remains unknown. We used qRT-PCR to examine gene expression of GLT-1 splice isoforms (GLT-1A, GLT-1B) in the NAc, prelimbic cortex (PL) and basolateral amygdala (BLA) of rats, following two widely used models of cocaine self-administration: short-access (ShA) self-administration, and the long-access (LgA) self-administration/incubation model. While downregulation of GLT-1 protein is observed following ShA cocaine self-administration and extinction, this model did not lead to a change in GLT-1A or GLT-1B gene expression in any brain region examined. Forced abstinence following ShA cocaine self-administration also was without effect. In contrast, LgA cocaine self-administration and prolonged abstinence significantly decreased GLT-1A gene expression in the NAc and BLA, and significantly decreased GLT-1B gene expression in the PL. No change was observed in NAc GLT-1A gene expression one day after LgA cocaine self-administration, indicating withdrawal-induced decreases in GLT-1A mRNA. In addition, LgA cocaine self-administration and withdrawal induced hypermethylation of the GLT-1 gene in the NAc. These results indicate that a decrease in NAc GLT-1 mRNA is only observed after extended access to cocaine combined with protracted abstinence, and that epigenetic mechanisms likely contribute to this effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glutamine and glutamate: Nonessential or essential amino acids?

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Malcolm Watford

2015-09-01

Full Text Available Glutamine and glutamate are not considered essential amino acids but they play important roles in maintaining growth and health in both neonates and adults. Although glutamine and glutamate are highly abundant in most feedstuffs there is increasing evidence that they may be limiting during pregnancy, lactation and neonatal growth, particularly when relatively low protein diets are fed. Supplementation of diets with glutamine, glutamate or both at 0.5 to 1.0% to both suckling and recently weaned piglets improves intestinal and immune function and results in better growth. In addition such supplementation to the sow prevents some of the loss of lean body mass during lactation, and increases milk glutamine content. However, a number of important questions related to physiological condition, species under study and the form and amount of the supplements need to be addressed before the full benefits of glutamine and glutamate supplementation in domestic animal production can be realized. Keywords: Amino acid, Glutamate, Glutamine, Lactation, Pregnancy, Growth

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

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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

50 Hz hippocampal stimulation in refractory epilepsy: Higher level of basal glutamate predicts greater release of glutamate.

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Cavus, Idil; Widi, Gabriel A; Duckrow, Robert B; Zaveri, Hitten; Kennard, Jeremy T; Krystal, John; Spencer, Dennis D

2016-02-01

The effect of electrical stimulation on brain glutamate release in humans is unknown. Glutamate is elevated at baseline in the epileptogenic hippocampus of patients with refractory epilepsy, and increases during spontaneous seizures. We examined the effect of 50 Hz stimulation on glutamate release and its relationship to interictal levels in the hippocampus of patients with epilepsy. In addition, we measured basal and stimulated glutamate levels in a subset of these patients where stimulation elicited a seizure. Subjects (n = 10) were patients with medically refractory epilepsy who were undergoing intracranial electroencephalography (EEG) evaluation in an epilepsy monitoring unit. Electrical stimulation (50 Hz) was delivered through implanted hippocampal electrodes (n = 11), and microdialysate samples were collected every 2 min. Basal glutamate, changes in glutamate efflux with stimulation, and the relationships between peak stimulation-associated glutamate concentrations, basal zero-flow levels, and stimulated seizures were examined. Stimulation of epileptic hippocampi in patients with refractory epilepsy caused increases in glutamate efflux (p = 0.005, n = 10), and 4 of ten patients experienced brief stimulated seizures. Stimulation-induced increases in glutamate were not observed during the evoked seizures, but rather were related to the elevation in interictal basal glutamate (R(2) = 0.81, p = 0.001). The evoked-seizure group had lower basal glutamate levels than the no-seizure group (p = 0.04), with no stimulation-induced change in glutamate efflux (p = 0.47, n = 4). Conversely, increased glutamate was observed following stimulation in the no-seizure group (p = 0.005, n = 7). Subjects with an atrophic hippocampus had higher basal glutamate levels (p = 0.03, n = 7) and higher stimulation-induced glutamate efflux. Electrical stimulation of the epileptic hippocampus either increased extracellular glutamate efflux or induced seizures. The magnitude of stimulated

Psychosis and relapse in bipolar disorder are related to GRM3 ...

African Journals Online (AJOL)

; mGluR3; G72 protein; HumanDysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, ...

Bioconversion of sugar cane molasses into glutamic acid by gamma irradiated corynebacterium glutamicum

International Nuclear Information System (INIS)

El-Batal, A.I.

1996-01-01

Corynebacterium glutamicum (ATCC 13058) was used for glutamic acid production from sugar cane molasses which contain sufficient. The addition of 5 units ml 4 of penicillin G was superior in glutamic acid production (11.5 g L 4 ). Tweens and their saturated fatty acids were effective on the accumulation of glutamic acid in the culture medium and the maximum yield (16.6 g L 4 ) was the addition of 5 mg ml 4 Tween 40. Gamma irradiation prior to Tween-40 treatment of bacterial cells resulted in an obvious increase in glutamic acid production and it was maximum (23.72 g L 4 ) at 0.1 k Gy exposure dose of inocula. 5 tabs

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.

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

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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.

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

Science.gov (United States)

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

2012-01-01

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

The Drosophila DmGluRA is required for social interaction and memory

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Brian P. Schoenfeld

2013-05-01

Full Text Available Metabotropic glutamate receptors (mGluRs have well established roles in cognition andsocial behavior in mammals. Whether or not these roles have been conserved throughoutevolution from invertebrate species is less clear. Mammals have 8 mGluRs whereasDrosophila have a single DmGluRA, which has both Gi and Gq coupled signalingactivity. We have utilized Drosophila to examine the role of DmGluRA in social behaviorand various phases of memory. We have found that flies that are homozygous orheterozygous for loss of function mutations of DmGluRA have impaired social behaviorin male Drosophila. Futhermore, flies that are homozygous or heterozygous for loss offunction mutations of DmGluRA have impaired learning during training, immediate recallmemory, short-term memory and long-term memory as young adults. This workdemonstrates a role for metabotropic glutamate receptor activity in both social behaviorand memory in Drosophila.

The phosphorylation status and cytoskeletal remodeling of striatal astrocytes treated with quinolinic acid

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Pierozan, Paula; Ferreira, Fernanda; Ortiz de Lima, Bárbara; Gonçalves Fernandes, Carolina [Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035-003 (Brazil); Totarelli Monteforte, Priscila; Castro Medaglia, Natalia de; Bincoletto, Claudia; Soubhi Smaili, Soraya [Departamento de Farmacologia, Universidade Federal de São Paulo (UNIFESP/EPM), São Paulo, SP (Brazil); Pessoa-Pureur, Regina, E-mail: rpureur@ufrgs.br [Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035-003 (Brazil)

2014-04-01

Quinolinic acid (QUIN) is a glutamate agonist which markedly enhances the vulnerability of neural cells to excitotoxicity. QUIN is produced from the amino acid tryptophan through the kynurenine pathway (KP). Dysregulation of this pathway is associated with neurodegenerative conditions. In this study we treated striatal astrocytes in culture with QUIN and assayed the endogenous phosphorylating system associated with glial fibrillary acidic protein (GFAP) and vimentin as well as cytoskeletal remodeling. After 24 h incubation with 100 µM QUIN, cells were exposed to {sup 32}P-orthophosphate and/or protein kinase A (PKA), protein kinase dependent of Ca{sup 2+}/calmodulin II (PKCaMII) or protein kinase C (PKC) inhibitors, H89 (20 μM), KN93 (10 μM) and staurosporin (10 nM), respectively. Results showed that hyperphosphorylation was abrogated by PKA and PKC inhibitors but not by the PKCaMII inhibitor. The specific antagonists to ionotropic NMDA and non-NMDA (50 µM DL-AP5 and CNQX, respectively) glutamate receptors as well as to metabotropic glutamate receptor (mGLUR; 50 µM MCPG), mGLUR1 (100 µM MPEP) and mGLUR5 (10 µM 4C3HPG) prevented the hyperphosphorylation provoked by QUIN. Also, intra and extracellular Ca{sup 2+} quelators (1 mM EGTA; 10 µM BAPTA-AM, respectively) prevented QUIN-mediated effect, while Ca{sup 2+} influx through voltage-dependent Ca{sup 2+} channel type L (L-VDCC) (blocker: 10 µM verapamil) is not implicated in this effect. Morphological analysis showed dramatically altered actin cytoskeleton with concomitant change of morphology to fusiform and/or flattened cells with retracted cytoplasm and disruption of the GFAP meshwork, supporting misregulation of actin cytoskeleton. Both hyperphosphorylation and cytoskeletal remodeling were reversed 24 h after QUIN removal. Astrocytes are highly plastic cells and the vulnerability of astrocyte cytoskeleton may have important implications for understanding the neurotoxicity of QUIN in neurodegenerative

Improvement in antioxidant activity, angiotensin-converting enzyme inhibitory activity and in vitro cellular properties of fermented pepino milk by Lactobacillus strains containing the glutamate decarboxylase gene.

Science.gov (United States)

Chiu, Tsai-Hsin; Tsai, Shwu-Jene; Wu, Tsung-Yen; Fu, Szu-Chieh; Hwang, Yi-Ting

2013-03-15

The purpose of this study was to evaluate the functional potential of fermented pepino extract (PE) milk by Lactobacillus strains containing the glutamate decarboxylase (GAD) gene. Three Lactobacillus strains were selected, including L. brevis BCRC 12310, L. casei BCRC 14082 and L. salivarius subsp. salivarius BCRC 14759. The contents of free amino acids, total phenolics content, total carotenoids and the associated functional and antioxidant abilities were analyzed, including angiotensin-converting enzyme (ACE) inhibition activity, 1,1-diphenyl-2-picylhydrazyl (DPPH) radical-scavenging ability and oxygen radical absorbance capacity (ORAC). Cell proliferation of fermented PE milk was also evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Compared to the unfermented PE, fermented PE milk from Lactobacillus strains with the GAD gene showed higher levels of total phenolics, γ-aminobutyric acid, ACE inhibitory activity, DPPH, and ORAC. The viability of human promyelocytic leukemia cells (HL-60) determined by the MTT method decreased significantly when the cells were incubated with the PE and the fermented PE milk extracts. The consumption of fermented PE milk from Lactobacillus strains with the GAD gene is expected to benefit health. Further application as a health food is worthy of investigation. © 2012 Society of Chemical Industry. © 2012 Society of Chemical Industry.

Purification and characterization of gamma poly glutamic acid from newly Bacillus licheniformis NRC20.

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Tork, Sanaa E; Aly, Magda M; Alakilli, Saleha Y; Al-Seeni, Madeha N

2015-03-01

γ-poly glutamic acid (γ-PGA) has received considerable attention for pharmaceutical and biomedical applications. γ-PGA from the newly isolate Bacillus licheniformis NRC20 was purified and characterized using diffusion distance agar plate, mass spectrometry and thin layer chromatography. All analysis indicated that γ-PGA is a homopolymer composed of glutamic acid. Its molecular weight was determined to be 1266 kDa. It was composed of L- and D-glutamic acid residues. An amplicon of 3050 represents the γ-PGA-coding genes was obtained, sequenced and submitted in genbank database. Its amino acid sequence showed high similarity with that obtained from B. licheniformis strains. The bacterium NRC 20 was independent of L-glutamic acid but the polymer production enhanced when cultivated in medium containing L-glutamic acid as the sole nitrogen source. Finally we can conclude that γ-PGA production from B. licheniformis NRC20 has many promised applications in medicine, industry and nanotechnology. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of Jerusalem artichoke resource for efficient one-step fermentation of poly-(γ-glutamic acid) using a novel strain Bacillus amyloliquefaciens NX-2S.

Science.gov (United States)

Qiu, Yibin; Sha, Yuanyuan; Zhang, Yatao; Xu, Zongqi; Li, Sha; Lei, Peng; Xu, Zheng; Feng, Xiaohai; Xu, Hong

2017-09-01

This study aimed to develop non-food fermentation for the cost-effective production of poly-(γ-glutamic acid) (γ-PGA) using a novel strain of Bacillus amyloliquefaciens NX-2S. The new isolate assimilated inulin more efficiently than other carbohydrates from Jerusalem artichoke, without hydrolytic treatment. To investigate the effect of inulin on γ-PGA production, the transcript levels of γ-PGA synthetase genes (pgsB, pgsC, pgsA), regulatory genes (comA, degQ, degS), and the glutamic acid biosynthesis gene (glnA) were analyzed; inulin addition upregulated these key genes. Without exogenous glutamate, strain NX-2S could produce 6.85±0.22g/L of γ-PGA during fermentation. Exogenous glutamate greatly enhances the γ-PGA yield (39.4±0.38g/L) and productivity (0.43±0.05g/L/h) in batch fermentation. Our study revealed a potential method of non-food fermentation to produce high-value products. Copyright © 2017. Published by Elsevier Ltd.

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...

Neuroprotective effects of the novel glutamate transporter inhibitor (-)-3-hydroxy-4,5,6,6a-tetrahydro-3aH-pyrrolo[3,4-d]-isoxazole-4-carboxylic acid, which preferentially inhibits reverse transport (glutamate release) compared with glutamate reuptake

DEFF Research Database (Denmark)

Colleoni, Simona; Jensen, Anders Asbjørn; Landucci, Elisa

2008-01-01

on the three hEAAT subtypes. (-)-HIP-A maintained the remarkable property, previously reported with the racemates, of inhibiting synaptosomal glutamate-induced [3H]D-aspartate release (reverse transport) at concentrations significantly lower than those inhibiting [3H]L-glutamate uptake. New data suggest...

Glutamate and Neurodegenerative Disease

Science.gov (United States)

Schaeffer, Eric; Duplantier, Allen

As the main excitatory neurotransmitter in the mammalian central nervous system, glutamate is critically involved in most aspects of CNS function. Given this critical role, it is not surprising that glutamatergic dysfunction is associated with many CNS disorders. In this chapter, we review the literature that links aberrant glutamate neurotransmission with CNS pathology, with a focus on neurodegenerative diseases. The biology and pharmacology of the various glutamate receptor families are discussed, along with data which links these receptors with neurodegenerative conditions. In addition, we review progress that has been made in developing small molecule modulators of glutamate receptors and transporters, and describe how these compounds have helped us understand the complex pharmacology of glutamate in normal CNS function, as well as their potential for the treatment of neurodegenerative diseases.

Enriched environment influences hormonal status and hippocampal brain derived neurotrophic factor in a sex dependent manner.

Science.gov (United States)

Bakos, J; Hlavacova, N; Rajman, M; Ondicova, K; Koros, C; Kitraki, E; Steinbusch, H W M; Jezova, D

2009-12-01

The present study is aimed at testing the hypothesis that an enriched environment (EE) induces sex-dependent changes in stress hormone release and in markers of increased brain plasticity. The focus was on hypothalamic-pituitary-adrenocortical (HPA) axis activity, plasma levels of stress hormones, gene expression of glutamate receptor subunits and concentrations of brain-derived neurotrophic factor (BDNF) in selected brain regions. Rats exposed to EE were housed in groups of 12 in large cages with various objects, which were frequently changed, for 6 weeks. Control animals were housed four per cage under standard conditions. In females the EE-induced rise in hippocampal BDNF, a neurotrophic factor associated with increased neural plasticity, was more pronounced than in males. Similar sex-specific changes were observed in BDNF concentrations in the hypothalamus. EE also significantly attenuated oxytocin and aldosterone levels only in female but not male rats. Plasma testosterone positively correlated with hippocampal BDNF in female but not male rats housed in EE. In male rats housing in EE led to enhanced levels of testosterone and adrenocorticotropic hormone (ACTH), this was not seen in females. Hippocampal glucocorticoid but not mineralocorticoid receptor levels decreased in rats housed in EE irrespective of sex. Housing conditions failed to modify mRNA levels of glutamate receptor type 1 (Glur1) and metabotropic glutamate receptor subtype 5 (mGlur5) subunits of glutamate receptors in the forebrain. Moreover, a negative association between corticosterone and BDNF was observed in both sexes. The results demonstrate that the association between hormones and changes in brain plasticity is sex related. In particular, testosterone seems to be involved in the regulatory processes related to neuroplasticity in females.

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.

[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.

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 ...

GMP reverses the facilitatory effect of glutamate on inhibitory avoidance task in rats.

Science.gov (United States)

Rubin, M A; Jurach, A; da Costa Júnior, E M; Lima, T T; Jiménez-Bernal, R E; Begnini, J; Souza, D O; de Mello, C F

1996-09-02

Previous studies have demonstrated that post-training intrahippocampal glutamate administration improves inhibitory avoidance task performance in rats. Antagonism of the agonist actions of glutamate by guanine nucleotides has been shown at the molecular and behavioural level. In the present investigation we demonstrate that intrahippocampal co-administration of GMP (guanosine 5'-monophosphate) reverses the facilitatory effect of glutamate on the inhibitory avoidance learning paradigm and inhibits [3H]glutamate binding in hippocampal synaptic plasma membranes. These results suggest that guanine nucleotides may modulate glutamate actions.

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.

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

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

International Nuclear Information System (INIS)

Mennini, T.; Miari, A.

1991-01-01

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

Influence of the glutamic acid content of the diet on the catabolisc rate of labelled glutamic acid in rats. 1

International Nuclear Information System (INIS)

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

1984-01-01

Male rats received in 8 groups of 10 animals each for a period of 7 days 7 synthetic diets and one semisynthetic diet on maintenance requirement level. A L-amino acid mixture corresponding to the pattern of egg protein without glutamic acid was the protein source of the synthetic diets. Glutamic acid was supplemented successively from 0 to 58 mol-% of the total amino acid content. The crude protein source of diet 8 was whole-egg powder. On the 8th day of experiment 5 animals per group were labelled by intragastric infusion with 14 C-glutamic acid. During the following 24 hours the excretion of CO 2 and 14 CO 2 was measured. Throughout the experimental feeding body weight was relative constant, however, when the synthetic diets were fed it was necessary to increase the daily amount of energy from 460 to 480 kJ/kg/sup 0.67/. The relative 14 CO 2 excretion within 24 hours was 68-75 % of the dose. However, the main part of the amount of radioactivity excreted during 24 hours was already found after 4 to 6 hours. Exponential functions calculated from the data of cumulative 14 CO 2 excretion suggest the existence of a fast process of 14 CO 2 formation directly from 14 C-glutamic acid, reaching a plateau within 2 hours and a slow process of oxidation of intermediates of glutamic acid metabolism, causing a continued 14 CO 2 formation even after 24 hours. The oxidation of 14 C-glutamic acid to CO 2 decreased 2 to 14 hours after labelling if the glutamic acid content of the diet increased. The same was found for the specific radioactivity of 14 CO 2 . A storage of intermediates of glutamic acid before degradation was assumed. (author)

Independent and additive effects of glutamic acid and methionine on yeast longevity.

Science.gov (United States)

Wu, Ziyun; Song, Lixia; Liu, Shao Quan; Huang, Dejian

2013-01-01

It is established that glucose restriction extends yeast chronological and replicative lifespan, but little is known about the influence of amino acids on yeast lifespan, although some amino acids were reported to delay aging in rodents. Here we show that amino acid composition greatly alters yeast chronological lifespan. We found that non-essential amino acids (to yeast) methionine and glutamic acid had the most significant impact on yeast chronological lifespan extension, restriction of methionine and/or increase of glutamic acid led to longevity that was not the result of low acetic acid production and acidification in aging media. Remarkably, low methionine, high glutamic acid and glucose restriction additively and independently extended yeast lifespan, which could not be further extended by buffering the medium (pH 6.0). Our preliminary findings using yeasts with gene deletion demonstrate that glutamic acid addition, methionine and glucose restriction prompt yeast longevity through distinct mechanisms. This study may help to fill a gap in yeast model for the fast developing view that nutrient balance is a critical factor to extend lifespan.

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.

The GRP1 PH domain, like the AKT1 PH domain, possesses a sentry glutamate residue essential for specific targeting to plasma membrane PI(3,4,5)P(3).

Science.gov (United States)

Pilling, Carissa; Landgraf, Kyle E; Falke, Joseph J

2011-11-15

During the appearance of the signaling lipid PI(3,4,5)P(3), an important subset of pleckstrin homology (PH) domains target signaling proteins to the plasma membrane. To ensure proper pathway regulation, such PI(3,4,5)P(3)-specific PH domains must exclude the more prevalant, constitutive plasma membrane lipid PI(4,5)P(2) and bind the rare PI(3,4,5)P(3) target lipid with sufficiently high affinity. Our previous study of the E17K mutant of the protein kinase B (AKT1) PH domain, together with evidence from Carpten et al. [Carpten, J. D., et al. (2007) Nature 448, 439-444], revealed that the native AKT1 E17 residue serves as a sentry glutamate that excludes PI(4,5)P(2), thereby playing an essential role in specific PI(3,4,5)P(3) targeting [Landgraf, K. E., et al. (2008) Biochemistry 47, 12260-12269]. The sentry glutamate hypothesis proposes that an analogous sentry glutamate residue is a widespread feature of PI(3,4,5)P(3)-specific PH domains, and that charge reversal mutation at the sentry glutamate position will yield both increased PI(4,5)P(2) affinity and constitutive plasma membrane targeting. To test this hypothesis, we investigated the E345 residue, a putative sentry glutamate, of the general receptor for phosphoinositides 1 (GRP1) PH domain. The results show that incorporation of the E345K charge reversal mutation into the GRP1 PH domain enhances PI(4,5)P(2) affinity 8-fold and yields constitutive plasma membrane targeting in cells, reminiscent of the effects of the E17K mutation in the AKT1 PH domain. Hydrolysis of plasma membrane PI(4,5)P(2) releases the E345K GRP1 PH domain into the cytoplasm, and the efficiency of this release increases when Arf6 binding is disrupted. Overall, the findings provide strong support for the sentry glutamate hypothesis and suggest that the GRP1 E345K mutation will be linked to changes in cell physiology and human pathologies, as demonstrated for AKT1 E17K [Carpten, J. D., et al. (2007) Nature 448, 439-444; Lindhurst, M. J., et al

Neurogranin in the nucleus accumbens regulates NMDA receptor tolerance and motivation for ethanol seeking.

Science.gov (United States)

Reker, Ashlie N; Oliveros, Alfredo; Sullivan, John M; Nahar, Lailun; Hinton, David J; Kim, Taehyun; Bruner, Robert C; Choi, Doo-Sup; Goeders, Nicholas E; Nam, Hyung W

2018-03-15

Dysfunction of N-methyl-d-aspartate receptor (NMDAR) signaling in the nucleus accumbens (NAc) has been implicated in the pathophysiology of alcohol use disorders (AUD). Neurogranin (Ng), a calmodulin-binding protein, is exclusively expressed in the post-synapse, and mediates NMDAR driven synaptic plasticity by regulating the calcium-calmodulin (Ca 2+ -CaM) pathway. To study the functional role of Ng in AUD, we administrated behavior tests including Pavlovian instrument transfer (PIT), operant conditioning, and rotarod test using Ng null mice (Ng -/- mice). We used adeno-associated virus (AAV)-mediated Ng expression and pharmacological manipulation to validate behavioral responses in Ng -/- mice. The results from our multidisciplinary approaches demonstrated that deficit of Ng increases tolerance to NMDAR inhibition and elicit faster cue reactivity during PIT without changes in ethanol reward. Operant conditioning results demonstrated that Ng -/- mice self-administered significantly more ethanol and displayed reduced sensitivity to aversive motivation. We identified that ethanol exposure decreases mGluR5 (metabotropic glutamate receptor 5) expression in the NAc of Ng -/- mice and pharmacological inhibition of mGluR5 reverses NMDAR desensitization in Ng -/- mice. Together these findings specifically suggest that accumbal Ng plays an essential role in the counterbalance between NMDAR and mGluR5 signaling; which alters NMDAR resistance, and thereby altering aversive motivation for ethanol and may ultimately contribute to susceptibility for alcohol addiction. Copyright © 2017 Elsevier Ltd. All rights reserved.

The accessibility in the external part of the TM5 of the glutamate transporter EAAT1 is conformationally sensitive during the transport cycle.

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Xiuping Zhang

Full Text Available BACKGROUND: Excitatory amino acid transporter 1 (EAAT1 is a glutamate transporter which is a key element in the termination of the synaptic actions of glutamate. It serves to keep the extracellular glutamate concentration below neurotoxic level. However the functional significance and the change of accessibility of residues in transmembrane domain (TM 5 of the EAAT1 are not clear yet. METHODOLOGY/PRINCIPAL FINDINGS: We used cysteine mutagenesis with treatments with membrane-impermeable sulfhydryl reagent MTSET [(2-trimethylammonium methanethiosulfonate] to investigate the change of accessibility of TM5. Cysteine mutants were introduced from position 291 to 300 of the cysteine-less version of EAAT1. We checked the activity and kinetic parameters of the mutants before and after treatments with MTSET, furthermore we analyzed the effect of the substrate and blocker on the inhibition of the cysteine mutants by MTSET. Inhibition of transport by MTSET was observed in the mutants L296C, I297C and G299C, while the activity of K300C got higher after exposure to MTSET. V(max of L296C and G299C got lower while that of K300C got higher after treated by MTSET. The L296C, G299C, K300C single cysteine mutants showed a conformationally sensitive reactivity pattern. The sensitivity of L296C to MTSET was potentiated by glutamate and TBOA,but the sensitivity of G299C to MTSET was potentiated only by TBOA. CONCLUSIONS/SIGNIFICANCE: All these facts suggest that the accessibility of some positions of the external part of the TM5 is conformationally sensitive during the transport cycle. Our results indicate that some residues of TM5 take part in the transport pathway during the transport cycle.

Oral glutamate intake reduces acute and chronic effects of ethanol in ...

African Journals Online (AJOL)

treatment, male Wistar rats were trained to consume ethanol-sucrose solution during a 2-h period daily, ... Oral treatment with 2.5 g/kg of glutamate reversed the acute motor effects of ethanol. ..... glutamate release in the prefrontal cortex-NAc.

Circadian Regulation of Glutamate Transporters

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Donají Chi-Castañeda

2018-06-01

Full Text Available L-glutamate is the major excitatory amino acid in the mammalian central nervous system (CNS. This neurotransmitter is essential for higher brain functions such as learning, cognition and memory. A tight regulation of extra-synaptic glutamate levels is needed to prevent a neurotoxic insult. Glutamate removal from the synaptic cleft is carried out by a family of sodium-dependent high-affinity transporters, collectively known as excitatory amino acid transporters. Dysfunction of glutamate transporters is generally involved in acute neuronal injury and neurodegenerative diseases, so characterizing and understanding the mechanisms that lead to the development of these disorders is an important goal in the design of novel treatments for the neurodegenerative diseases. Increasing evidence indicates glutamate transporters are controlled by the circadian system in direct and indirect manners, so in this contribution we focus on the mechanisms of circadian regulation (transcriptional, translational, post-translational and post-transcriptional regulation of glutamate transport in neuronal and glial cells, and their consequence in brain function.

Agmatine Prevents Adaptation of the Hippocampal Glutamate System in Chronic Morphine-Treated Rats.

Science.gov (United States)

Wang, Xiao-Fei; Zhao, Tai-Yun; Su, Rui-Bin; Wu, Ning; Li, Jin

2016-12-01

Chronic exposure to opioids induces adaptation of glutamate neurotransmission, which plays a crucial role in addiction. Our previous studies revealed that agmatine attenuates opioid addiction and prevents the adaptation of glutamate neurotransmission in the nucleus accumbens of chronic morphine-treated rats. The hippocampus is important for drug addiction; however, whether adaptation of glutamate neurotransmission is modulated by agmatine in the hippocampus remains unknown. Here, we found that continuous pretreatment of rats with ascending doses of morphine for 5 days resulted in an increase in the hippocampal extracellular glutamate level induced by naloxone (2 mg/kg, i.p.) precipitation. Agmatine (20 mg/kg, s.c.) administered concurrently with morphine for 5 days attenuated the elevation of extracellular glutamate levels induced by naloxone precipitation. Furthermore, in the hippocampal synaptosome model, agmatine decreased the release and increased the uptake of glutamate in synaptosomes from chronic morphine-treated rats, which might contribute to the reduced elevation of glutamate levels induced by agmatine. We also found that expression of the hippocampal NR2B subunit, rather than the NR1 subunit, of N-methyl-D-aspartate receptors (NMDARs) was down-regulated after chronic morphine treatment, and agmatine inhibited this reduction. Taken together, agmatine prevented the adaptation of the hippocampal glutamate system caused by chronic exposure to morphine, including modulating extracellular glutamate concentration and NMDAR expression, which might be one of the mechanisms underlying the attenuation of opioid addiction by agmatine.

Analysis of L-glutamic acid fermentation by using a dynamic metabolic simulation model of Escherichia coli.

Science.gov (United States)

Nishio, Yousuke; Ogishima, Soichi; Ichikawa, Masao; Yamada, Yohei; Usuda, Yoshihiro; Masuda, Tadashi; Tanaka, Hiroshi

2013-09-22

Understanding the process of amino acid fermentation as a comprehensive system is a challenging task. Previously, we developed a literature-based dynamic simulation model, which included transcriptional regulation, transcription, translation, and enzymatic reactions related to glycolysis, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and the anaplerotic pathway of Escherichia coli. During simulation, cell growth was defined such as to reproduce the experimental cell growth profile of fed-batch cultivation in jar fermenters. However, to confirm the biological appropriateness of our model, sensitivity analysis and experimental validation were required. We constructed an L-glutamic acid fermentation simulation model by removing sucAB, a gene encoding α-ketoglutarate dehydrogenase. We then performed systematic sensitivity analysis for L-glutamic acid production; the results of this process corresponded with previous experimental data regarding L-glutamic acid fermentation. Furthermore, it allowed us to predicted the possibility that accumulation of 3-phosphoglycerate in the cell would regulate the carbon flux into the TCA cycle and lead to an increase in the yield of L-glutamic acid via fermentation. We validated this hypothesis through a fermentation experiment involving a model L-glutamic acid-production strain, E. coli MG1655 ΔsucA in which the phosphoglycerate kinase gene had been amplified to cause accumulation of 3-phosphoglycerate. The observed increase in L-glutamic acid production verified the biologically meaningful predictive power of our dynamic metabolic simulation model. In this study, dynamic simulation using a literature-based model was shown to be useful for elucidating the precise mechanisms involved in fermentation processes inside the cell. Further exhaustive sensitivity analysis will facilitate identification of novel factors involved in the metabolic regulation of amino acid fermentation.

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...

The effects of DL-AP5 and glutamate on ghrelin-induced feeding behavior in 3-h food-deprived broiler cockerels

NARCIS (Netherlands)

Taati, Majid; Nayebzadeh, Hassan; Zendehdel, Morteza

This study was designed to examine the effects of intracerebroventricular injection of DL-AP5 (N-methyl-D-aspartate (NMDA) receptor antagonist) and glutamate on ghrelin-induced feeding behavior in 3-h food-deprived (FD3) broiler cockerels. At first, guide cannula was surgically implanted in the

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.

Analysis of L-serine-O-phosphate in cerebrospinal spinal fluid by derivatization-liquid chromatography/mass spectrometry.

Science.gov (United States)

McNaney, Colleen A; Benitex, Yulia; Luchetti, David; Labasi, Jeffrey M; Olah, Timothy V; Morgan, Daniel G; Drexler, Dieter M

2014-05-01

L-serine-O-phosphate (L-SOP), the precursor of L-serine, is a potent agonist against the group III metabotropic glutamate receptors (mGluRs) and, thus, is of interest as a potential biomarker for monitoring modulation of neurotransmitter release. So far, no reports are available on the analysis of L-SOP in cerebrospinal fluid (CSF). Here a novel method is presented to determine L-SOP levels in CSF employing precolumn derivatization with (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP) coupled to liquid chromatography/mass spectrometry (derivatization-LC/MS, d-LC/MS). Copyright © 2014 Elsevier Inc. All rights reserved.

Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's expression, impair glutamate-induced signaling and function, activate blood brain barrier endothelial cells, kill neurons, damage the brain, induce behavioral/psychiatric/cognitive abnormalities and ataxia in animal models, and can be removed or silenced in some patients by immunotherapy.

Science.gov (United States)

Levite, Mia

2014-08-01

antibodies into the brain of mice, the mice became ataxic. Anti-mGluR1 antibodies derived from patients with Ataxia also caused disturbance of eye movements in animal models. Immunotherapy can be very effective for some Cerebellar Ataxia patients that have anti-mGluR1 antibodies. (5) Anti-mGluR5 antibodies were found thus far in the serum and CSF of very few patients with Hodgkin lymphoma and Limbic Encephalopathy (Ophelia syndrome). The sera of these patients that contained anti-GluR5 antibodies reacted with the neuropil of the hippocampus and cell surface of live rat hippocampal neurons, and immunoprecipitation from cultured neurons and mass spectrometry demonstrated that the antigen was indeed mGluR5. Taken together, all these evidences show that anti-glutamate receptor antibodies are much more frequent among various neurological diseases than ever realized before, and that they are very detrimental to the nervous system. As such, they call for diagnosis, therapeutic removal or silencing and future studies. What we have learned by now about the broad family of anti-glutamate receptor antibodies is so exciting, novel, unique and important, that it makes all future efforts worthy and essential.

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

DEFF Research Database (Denmark)

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

2009-01-01

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

Two siblings with early infantile myoclonic encephalopathy due to mutation in the gene encoding mitochondrial glutamate/H+ symporter SLC25A22.

Science.gov (United States)

Cohen, Rony; Basel-Vanagaite, Lina; Goldberg-Stern, Hadassah; Halevy, Ayelet; Shuper, Avinoam; Feingold-Zadok, Michal; Behar, Doron M; Straussberg, Rachel

2014-11-01

To characterize a new subset of early myoclonic encephalopathy usually associated with metabolic etiologies with a new genetic entity. We describe two siblings with early myoclonic encephalopathy born to consanguineous parents of Arab Muslim origin from Israel. We used homozygosity mapping and candidate gene sequencing to reveal the genetic basis of the myoclonic syndrome. We found a rare missense mutation in the gene encoding one of the two mitochondrial glutamate/H symporters, SLC25A22. The phenotype of early myoclonic encephalopathy was first linked to the same mutation in 2005 in patients of the same ethnicity as our family. Owing to the devastating nature of this encephalopathy, we focus attention on its clinical history, epileptic semiology, distinct electroencephalography features, and genetic basis. We provide the evidence that an integrated diagnostic strategy combining homozygosity mapping with candidate gene sequencing is efficient in consanguineous families with highly heterogeneous autosomal recessive diseases. Copyright © 2014 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Association of the −243A>G, +61450C>A Polymorphisms of the Glutamate Decarboxylase 2 (GAD2) Gene with Obesity and Insu¬lin Level in North Indian Population

OpenAIRE

Jai PRAKASH; Balraj MITTAL; Shally AWASTHI; Neena SRIVASTAVA

2016-01-01

Background: Obesity associated with type 2 diabetes, and hypertension increased mortality and morbidity. Glutamate decarboxylase 2 (GAD2) gene is associated with obesity and it regulate food intake and insulin level. We investigated the association of GAD-2gene −243A>G (rs2236418) and +61450C>A (rs992990) polymorphisms with obesity and related phenotypes.Methods: Insulin, glucose and lipid levels were estimated using standard protocols. All subjects were genotyped (PCR-RFLP) method.Resu...

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

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......, and different techniques have been developed to this end. This review presents and discusses these techniques, especially the recent progress in the field of glutamate biosensors, as well as the great potential of nanotechnology in glutamate sensing. Microdialysis coupled to analytical detection techniques...... neurobiological research. Another interesting group of biosensors for glutamate are fluorescence-based glutamate biosensors, which have unsurpassed spatio-temporal resolution and are therefore important tools for investigating glutamate dynamics during signaling. Adding to this list are biosensors based on nano...

Glutamate Efflux at the Blood-Brain Barrier

DEFF Research Database (Denmark)

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

2014-01-01

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, metabolism of L-glutamate and transport of metabolites or a combination of the two. However, both in vitro and in vivo studies have demonstrated blood-to-brain transport of L-glutamate, at least during pathological events. This review summarizes the current knowledge on the brain-to-blood L-glutamate efflux...

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)

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.

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...

Introduction to the Glutamate-Glutamine Cycle

DEFF Research Database (Denmark)

Sonnewald, Ursula; Schousboe, Arne

2016-01-01

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......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...

Characterization and expression of glutamate dehydrogenase in response to acute salinity stress in the Chinese mitten crab, Eriocheir sinensis.

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Yueru Wang

Full Text Available Glutamate dehydrogenase (GDH is a key enzyme for the synthesis and catabolism of glutamic acid, proline and alanine, which are important osmolytes in aquatic animals. However, the response of GDH gene expression to salinity alterations has not yet been determined in macro-crustacean species.GDH cDNA was isolated from Eriocheir sinensis. Then, GDH gene expression was analyzed in different tissues from normal crabs and the muscle of crabs following transfer from freshwater (control directly to water with salinities of 16‰ and 30‰, respectively. Full-length GDH cDNA is 2,349 bp, consisting of a 76 bp 5'- untranslated region, a 1,695 bp open reading frame encoding 564 amino acids and a 578 bp 3'- untranslated region. E. sinensis GDH showed 64-90% identity with protein sequences of mammalian and crustacean species. Muscle was the dominant expression source among all tissues tested. Compared with the control, GDH expression significantly increased at 6 h in crabs transferred to 16‰ and 30‰ salinity, and GDH expression peaked at 48 h and 12 h, respectively, with levels approximately 7.9 and 8.5 fold higher than the control. The free amino acid (FAA changes in muscle, under acute salinity stress (16‰ and 30‰ salinities, correlated with GDH expression levels. Total FAA content in the muscle, which was based on specific changes in arginine, proline, glycine, alanine, taurine, serine and glutamic acid, tended to increase in crabs following transfer to salt water. Among these, arginine, proline and alanine increased significantly during salinity acclimation and accounted for the highest proportion of total FAA.E. sinensis GDH is a conserved protein that serves important functions in controlling osmoregulation. We observed that higher GDH expression after ambient salinity increase led to higher FAA metabolism, especially the synthesis of glutamic acid, which increased the synthesis of proline and alanine to meet the demand of osmoregulation at

Analysis of l-glutamic acid fermentation by using a dynamic metabolic simulation model of Escherichia coli

Science.gov (United States)

2013-01-01

Background Understanding the process of amino acid fermentation as a comprehensive system is a challenging task. Previously, we developed a literature-based dynamic simulation model, which included transcriptional regulation, transcription, translation, and enzymatic reactions related to glycolysis, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and the anaplerotic pathway of Escherichia coli. During simulation, cell growth was defined such as to reproduce the experimental cell growth profile of fed-batch cultivation in jar fermenters. However, to confirm the biological appropriateness of our model, sensitivity analysis and experimental validation were required. Results We constructed an l-glutamic acid fermentation simulation model by removing sucAB, a gene encoding α-ketoglutarate dehydrogenase. We then performed systematic sensitivity analysis for l-glutamic acid production; the results of this process corresponded with previous experimental data regarding l-glutamic acid fermentation. Furthermore, it allowed us to predicted the possibility that accumulation of 3-phosphoglycerate in the cell would regulate the carbon flux into the TCA cycle and lead to an increase in the yield of l-glutamic acid via fermentation. We validated this hypothesis through a fermentation experiment involving a model l-glutamic acid-production strain, E. coli MG1655 ΔsucA in which the phosphoglycerate kinase gene had been amplified to cause accumulation of 3-phosphoglycerate. The observed increase in l-glutamic acid production verified the biologically meaningful predictive power of our dynamic metabolic simulation model. Conclusions In this study, dynamic simulation using a literature-based model was shown to be useful for elucidating the precise mechanisms involved in fermentation processes inside the cell. Further exhaustive sensitivity analysis will facilitate identification of novel factors involved in the metabolic regulation of amino acid fermentation. PMID

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...... between the anti-GLURP489-1271 and anti-(EENV)6 antibody responses. The data provide indirect evidence for a protective role of antibodies reacting with recombinant GLURP489-1271 as well as with the synthetic peptide (EENV)6 from the Pf155/RESA....

A Stable Glutamate Biosensor Based on MnO2 Bulk-modified ...

African Journals Online (AJOL)

An amperometric glutamate biosensor was developed using screen-printed carbon electrodes bulk-modified with MnO2 (5%, m:m) onto which glutamate oxidase was immobilized via Nafion(R) film entrapment. The analytical performance of the biosensor was assessed in a flow injection mode and peak heights of the ...

Glutamate Transporters in the Blood-Brain Barrier

DEFF Research Database (Denmark)

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

2017-01-01

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...... cells. The mechanisms underlying transendothelial L-glutamate transport are however still not well understood. The present chapter summarizes the current knowledge on blood-brain barrier L-glutamate transporters and the suggested pathways for the brain-to-blood L-glutamate efflux......., regulates the exchange of nutrients, gases, and metabolic waste products between plasma and brain interstitial fluid. It has been suggested that brain capillary endothelial cells could play an important role in L-glutamate homeostasis by mediating brain-to-blood L-glutamate efflux. Both in vitro and in vivo...

Label Free Detection of L-Glutamate Using Microfluidic Based Thermal Biosensor

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Varun Lingaiah Kopparthy

2015-01-01

Full Text Available A thermoelectric biosensor for the detection of L-glutamate concentration was developed. The thermoelectric sensor is integrated into a micro-calorimeter which measures the heat produced by biochemical reactions. The device contains a single flow channel that is 120 µm high and 10 mm wide with two fluid inlets and one fluid outlet. An antimony-bismuth (Sb-Bi thermopile with high common mode rejection ratio is attached to the lower channel wall and measures the dynamic changes in the temperature when L-glutamate undergoes oxidative deamination in the presence of glutamate oxidase (GLOD. The thermopile has a Seebeck coefficient of ~7 µV·(m·K−1. The device geometry, together with hydrodynamic focusing, eliminates the need of extensive temperature control. Layer-by-layer assembly is used to immobilize GLOD on the surface of glass coverslips by alternate electrostatic adsorption of polyelectrolyte and GLOD. The impulse injection mode using a 6-port injection valve minimizes sample volume to 5 µL. The sensitivity of the sensor for glutamate is 17.9 nVs·mM−1 in the linear range of 0–54 mM with an R2 value of 0.9873. The lowest detection limit of the sensor for glutamate is 5.3 mM.

NMDAR NR2A and NR2B specific PKC-dependent regulation of mGluR is defective in the Fragile X Syndrome mouse model

DEFF Research Database (Denmark)

Banke, Tue G.; Toft, Anna Karina; Lundbye, Camilla Johanne

The Fragile X Syndrome (FXS) animal model, the Fmr1 knock-out (KO) mouse, has demonstrated an increased mGluR5-mediated long-term depression (LTD). However, surprisingly little information exists about other ion channels/receptors and their effects on FXS, including NMDA receptors (NMDAR). Here we....... Furthermore, in this model it appears that NR2B activation stimulates PKC, while NR2A activation halts or reverses this effect. In addition, in the KO mice, the coupling between specific NMDAR subunits and mGluR-LTD activity through PKC seems defective in an age-dependent manner. These findings suggest strong...

Intramuscular temperature modulates glutamate-evoked masseter muscle pain intensity in humans.

Science.gov (United States)

Sato, Hitoshi; Castrillon, Eduardo E; Cairns, Brian E; Bendixen, Karina H; Wang, Kelun; Nakagawa, Taneaki; Wajima, Koichi; Svensson, Peter

2015-01-01

To determine whether glutamate-evoked jaw muscle pain is altered by the temperature of the solution injected. Sixteen healthy volunteers participated and received injections of hot (48°C), neutral (36°C), or cold (3°C) solutions (0.5 mL) of glutamate or isotonic saline into the masseter muscle. Pain intensity was assessed with an electronic visual analog scale (eVAS). Numeric rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, and pressure pain thresholds (PPTs) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). Two-way or three-way repeated measures ANOVA were used for data analyses. Injection of hot glutamate and cold glutamate solutions significantly increased and decreased, respectively, the peak pain intensity compared with injection of neutral glutamate solution. The duration of glutamate-evoked pain was significantly longer when hot glutamate was injected than when cold glutamate was injected. No significant effect of temperature on pain intensity was observed when isotonic saline was injected. No effect of solution temperature was detected on unpleasantness, heat perception, cold perception, area of pain drawings, or PPTs. There was a significantly greater use of the "numb" term in the MPQ to describe the injection of cold solutions compared to the injection of both neutral and hot solutions. Glutamate-evoked jaw muscle pain was significantly altered by the temperature of the injection solution. Although temperature perception in the jaw muscle is poor, pain intensity is increased when the muscle tissue temperature is elevated.

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

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

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Leif eHertz

2015-02-01

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

Evidence that glutamate mediates axon-to-Schwann cell signaling in the squid.

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Lieberman, E M; Abbott, N J; Hassan, S

1989-01-01

High-frequency stimulation (100 Hz) of isolated giant axons of the small squid Alloteuthis subulata and the large squid Loligo forbesi caused the periaxonal Schwann cell resting potential (Em = -40 mV) to hyperpolarize up to 11 mV in direct proportion to train duration and action potential amplitude. In both species, the Schwann cell also hyperpolarized up to 17 mV with the application of L-glutamate (10(-9) to 10(-6) M), in a dose-dependent manner. By contrast, in the presence of 10(-8) M d-tubocurarine (d-TC) to block the cholinergic component of the Schwann cell response, Schwann cells depolarized 8-9 mV during electrical stimulation of the axon or application of L-glutamate. In the presence of 10(-5) M 2-amino-4-phosphonobutyrate (2-APB), the hyperpolarization to glutamate and to axon stimulation was blocked, whereas the cholinergic (carbachol-induced) hyperpolarization was unaffected. In experiments with Alloteuthis, L-aspartate (10(-7) M) also caused a Schwann cell hyperpolarization, but this was not blocked by 2-APB. In tests with glutamate receptor agonists and antagonists, quisqualate (10(-5) M) produced a hyperpolarization blocked by 10(-4) M L-glutamic acid diethylester (GDEE), which also blocked the response to axonal stimulation. Kainic acid (10(-4) M) also caused a hyperpolarization, but n-methyl-D-aspartate (NMDA; 10(-4) M), ibotenate (10(-5) M), alpha-amino-3-hydroxy-5-methyl-isoxazole proprionate (AMPA; (10(-4) M), and isethionate (10(-5) M) had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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...

Excretion and intestinal absorption of tritiated glutamic acid by carp, Cyprinus Carpio

International Nuclear Information System (INIS)

Watabe, Terushia; Kistner, G.

1986-01-01

Excretion and intestinal absorption of tritiated glutamic acid by carp was investigated. Approximately 80% of orally administered tritium was excreted at a half life value of 1.4 h and an observed slower excretion of 7 days for the remainder. Tritium incorporated in glutamic acid was efficiently retained at the site of absorption, i.e. intestine, liver, gill, kidney, blood and muscle. A dual marking experiment using tritiated glutamic acid and 14 C-market glutamic acid showed higher excretion of tritium by factors 2.0 to 4.9 than that of 14 C. Tritiated glutamic acid is considered to be mainly incorporated in the citric acid cycle soon after administration and the release of tritium in tritiated water through the cycle is assumed as causing the initial rapid excretion of tritium in carp. The intestinal absorption of glutamic acid was likely to depend on its concentration in the administered solution. The maximum level of absorption is estimated to be 0.1 m mol/0.5 h for one year old carp. The results obtained here would make it possible to estimate the tritium contamination of fish due to tritiated glutamic acid entering the food chain. (orig.)

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

International Nuclear Information System (INIS)

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

1989-01-01

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

Interactions of MK-801 with glutamate-, glutamine- and methamphetamine-evoked release of [3H]dopamine from striatal slices

International Nuclear Information System (INIS)

Bowyer, J.F.; Scallet, A.C.; Holson, R.R.; Lipe, G.W.; Slikker, W. Jr.; Ali, S.F.

1991-01-01

The interactions of MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-imine], glutamate and glutamine with methamphetamine (METH)-evoked release of [ 3 H]dopamine were assessed in vitro to determine whether MK-801 inhibition of METH neurotoxicity might be mediated presynaptically, and to evaluate the effects of glutamatergic stimulation on METH-evoked dopamine release. MK-801 inhibition of glutamate- or METH-evoked dopamine release might reduce synaptic dopamine levels during METH exposure and decrease the formation of 6-hydroxydopamine or other related neurotoxins. Without Mg 2+ present, 40 microM and 1 mM glutamate evoked a N-methyl-D-aspartate receptor-mediated [ 3 H]dopamine and [ 3 H]metabolite (tritium) release of 3 to 6 and 12 to 16% of total tritium stores, respectively, from striatal slices. With 1.50 mM Mg 2+ present, 10 mM glutamate alone or in combination with the dopamine uptake blocker nomifensine released only 2.1 or 4.2%, respectively, of total tritium stores, and release was only partially dependent on N-methyl-D-aspartate-type glutamate receptors. With or without 1.50 mM Mg 2+ present, 0.5 or 5 microM METH evoked a substantial release of tritium (5-8 or 12-21% of total stores, respectively). METH-evoked dopamine release was not affected by 5 microM MK-801 but METH-evoked release was additive with glutamate-evoked release. Without Mg 2+ present, 1 mM glutamine increased glutamate release and induced the release of [ 3 H]dopamine and metabolites. Both 0.5 and 5 microM METH also increased tritium release with 1 mM glutamine present. When striatal slices were exposed to 5 microM METH this glutamine-evoked release of glutamate was increased more than 50%

Efficient Production of γ-GABA Using Recombinant E. coli Expressing Glutamate Decarboxylase (GAD) Derived from Eukaryote Saccharomyces cerevisiae.

Science.gov (United States)

Xiong, Qiang; Xu, Zheng; Xu, Lu; Yao, Zhong; Li, Sha; Xu, Hong

2017-12-01

γ-Aminobutyric acid (γ-GABA) is a non-proteinogenic amino acid, which acts as a major regulator in the central nervous system. Glutamate decarboxylase (namely GAD, EC 4.1.1.15) is known to be an ideal enzyme for γ-GABA production using L-glutamic acid as substrate. In this study, we cloned and expressed GAD gene from eukaryote Saccharomyces cerevisiae (ScGAD) in E. coli BL21(DE3). This enzyme was further purified and its optimal reaction temperature and pH were 37 °C and pH 4.2, respectively. The cofactor of ScGAD was verified to be either pyridoxal 5'-phosphate (PLP) or pyridoxal hydrochloride. The optimal concentration of either cofactor was 50 mg/L. The optimal medium for E. coli-ScGAD cultivation and expression were 10 g/L lactose, 5 g/L glycerol, 20 g/L yeast extract, and 10 g/L sodium chloride, resulting in an activity of 55 U/mL medium, three times higher than that of using Luria-Bertani (LB) medium. The maximal concentration of γ-GABA was 245 g/L whereas L-glutamic acid was near completely converted. These findings provided us a good example for bio-production of γ-GABA using recombinant E. coli expressing a GAD enzyme derived from eukaryote.

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...

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

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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.

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

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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

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.

The kinesin-3 family motor KLP-4 regulates anterograde trafficking of GLR-1 glutamate receptors in the ventral nerve cord of Caenorhabditis elegans.

Science.gov (United States)

Monteiro, Michael I; Ahlawat, Shikha; Kowalski, Jennifer R; Malkin, Emily; Koushika, Sandhya P; Juo, Peter

2012-09-01

The transport of glutamate receptors from the cell body to synapses is essential during neuronal development and may contribute to the regulation of synaptic strength in the mature nervous system. We previously showed that cyclin-dependent kinase-5 (CDK-5) positively regulates the abundance of GLR-1 glutamate receptors at synapses in the ventral nerve cord (VNC) of Caenorhabditis elegans. Here we identify a kinesin-3 family motor klp-4/KIF13 in a cdk-5 suppressor screen for genes that regulate GLR-1 trafficking. klp-4 mutants have decreased abundance of GLR-1 in the VNC. Genetic analysis of klp-4 and the clathrin adaptin unc-11/AP180 suggests that klp-4 functions before endocytosis in the ventral cord. Time-lapse microscopy indicates that klp-4 mutants exhibit decreased anterograde flux of GLR-1. Genetic analysis of cdk-5 and klp-4 suggests that they function in the same pathway to regulate GLR-1 in the VNC. Interestingly, GLR-1 accumulates in cell bodies of cdk-5 but not klp-4 mutants. However, GLR-1 does accumulate in klp-4-mutant cell bodies if receptor degradation in the multivesicular body/lysosome pathway is blocked. This study identifies kinesin KLP-4 as a novel regulator of anterograde glutamate receptor trafficking and reveals a cellular control mechanism by which receptor cargo is targeted for degradation in the absence of its motor.

Effect of Flunarizine on Serum Glutamate Levels and its Correlation with Headache Intensity in Chronic Tension-Type Headache Patients.

Science.gov (United States)

Surbakti, Khairul Putra; Sjahrir, Hasan; Juwita-Sembiring, Rosita; Mutiara, Erna

2017-10-15

Some of the excitatory neurotransmitters including glutamate have been suggested to be involved in headache pathophysiology. To our knowledge, there is a lack of publication about flunarizine efficacy in chronic tension-type headache (CTTH) treatments and the roles of glutamate in CTTH pathophysiology. This study aimed to investigate the flunarizine effect on serum levels of glutamate and its correlation with headache intensity based on the Numeric Rating Scale for pain (NRS) scores in CTTH patients. In a prospective randomised, double-blind study with pre and post-test design, seventy-three CTTH patients were randomly allocated with flunarizine 5 mg, flunarizine 10 mg and amitriptyline 12.5 mg groups. The serum levels of glutamate and NRS scores were measured before and after 15-day treatment. Flunarizine 5 mg was more effective than flunarizine 10 mg and amitriptyline 12.5 mg in reducing serum glutamate levels, whereas amitriptyline 12.5 mg was the most effective in reducing headache intensity. There was found nonsignificant, but very weak negative correlation between headache intensity and serum glutamate levels after flunarizine 5 mg administration (r = -0.062; P = 0.385), nonsignificant very weak negative correlation after flunarizine 10 mg administration (r = -0.007; P = 0.488) and there was found a significant moderate positive correlation (r = 0.508; P = 0.007) between headache intensity and serum glutamate levels after amitriptyline 12.5 mg administration. Since there was no significant correlation found between serum glutamate and headache intensity after treatment with flunarizine, it is suggested that decreasing of headache intensity after flunarizine treatment occurred not through glutamate pathways in CTTH patients.

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

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Sanderson Thomas M

2011-07-01

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

NADPH-dependent glutamate dehydrogenase in Penicillium chrysogenum is involved in regulation of beta-lactam production

DEFF Research Database (Denmark)

Thykær, Jette; Kildegaard, Kanchana Rueksomtawin; Noorman, H.

2008-01-01

was detected in either of the Delta gdhA strains. Supplementation with glutamate restored growth but no beta-lactam production was detected for the constructed strains. Cultures with high ammonium concentrations (repressing conditions) and with proline as nitrogen source (de-repressed conditions) showed......The interactions between the ammonium assimilatory pathways and beta-lactam production were investigated by disruption of the NADPH-dependent glutamate dehydrogenase gene (gdhA) in two industrial beta-lactam-producing strains of Penicillium chrysogenum. The strains used were an adipoyl-7-ADCA...... continued beta-lactam production for the reference strains whereas the Delta gdhA strains remained non-productive under all conditions. By overexpressing the NAD-dependent glutamate dehydrogenase, the specific growth rate could be restored, but still no beta-lactam production was detected. The results...

Real-time monitoring of extracellular l-glutamate levels released by high-frequency stimulation at region CA1 of hippocampal slices with a glass capillary-based l-glutamate sensor

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Yuki Ikegami

2014-12-01

Full Text Available Real-time monitoring of l-glutamate released by high-frequency stimulation in region CA1 of mouse hippocampal slices was performed with a glass capillary-based sensor, in combination with the recoding of excitatory postsynaptic potentials (fEPSPs. A method for extracting l-glutamate currents from the recorded ones was described and applied for determining the level of extracellular l-glutamate released by 100 Hz stimulation. Recording of an l-glutamate current with a current sampling interval of 1 Hz was found to be useful for acquiring a Faradaic current that reflects l-glutamate level released by the high-frequency stimulation of 7 trains, each 20 stimuli at 100 Hz and inter-train interval of 3 s. The l-glutamate level was obtained as 15 ± 6 μM (n = 8 for the persistent enhancement of fEPSPs, i.e., the induction of long-term potentiation (LTP, and 3 ± 1 μM (n = 5 for the case of no LTP induction. Based on these observations, the level of the extracellular l-glutamate was shown to play a crucial role in the induction of LTP.

Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

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Signorá Peres Konrad

2012-10-01

Full Text Available OBJECTIVES: The aim of this study was to evaluate cardiovascular autonomic function in a rodent obesity model induced by monosodium glutamate injections during the first seven days of life. METHOD: The animals were assigned to control (control, n = 10 and monosodium glutamate (monosodium glutamate, n = 13 groups. Thirty-three weeks after birth, arterial and venous catheters were implanted for arterial pressure measurements, drug administration, and blood sampling. Baroreflex sensitivity was evaluated according to the tachycardic and bradycardic responses induced by sodium nitroprusside and phenylephrine infusion, respectively. Sympathetic and vagal effects were determined by administering methylatropine and propranolol. RESULTS: Body weight, Lee index, and epididymal white adipose tissue values were higher in the monosodium glutamate group in comparison to the control group. The monosodium glutamate-treated rats displayed insulin resistance, as shown by a reduced glucose/insulin index (-62.5%, an increased area under the curve of total insulin secretion during glucose overload (39.3%, and basal hyperinsulinemia. The mean arterial pressure values were higher in the monosodium glutamate rats, whereas heart rate variability (>7 times, bradycardic responses (>4 times, and vagal (~38% and sympathetic effects (~36% were reduced as compared to the control group. CONCLUSION: Our results suggest that obesity induced by neonatal monosodium glutamate treatment impairs cardiac autonomic function and most likely contributes to increased arterial pressure and insulin resistance.

Paraventricular Stimulation with Glutamate Elicits Bradycardia and Pituitary Responses

Science.gov (United States)

Darlington, Daniel N.; Miyamoto, Michael; Keil, Lanny C.; Dallman, Mary F.

1989-01-01

The excitatory neurotransmitter, L-glutamate (0.5 M, pH 7.4), or the organic acid, acetate (0.5 M, pH 7.4), was microinjected (50 nl over 2 min) directly into the paraventricular nuclei (PVN) of pentobarbital sodium-anesthetized rats while arterial blood pressure and heart rate and plasma adrenocorticotropic hormone (ACTH), vasopressin, and oxytocin were measured. Activation of PVN neurons with L-glutamate led to increases in plasma ACTH, vasopressin, and oxytocin and a profound bradycardia (-80 beats/min) with little change in arterial blood pressure. Microinjection of acetate had no effect on the above variables. The decrease in heart rate was shown to be dependent on the concentration of glutamate injected and the volume of injectate. The bradycardia was mediated through the autonomic nervous system because ganglionic blockade (pentolinium tartrate) eliminated the response; atropine and propranolol severely attenuated the bradycardia. The bradycardia was greatest when L-glutamate was microinjected into the caudal PVN. Injections into the rostral PVN or into nuclei surrounding the PVN led to small or nonsignificant decreases in heart rate. Focal electric stimulation (2-50 pA) of the PVN also led to decreases in heart rate and arterial blood pressure. These data suggest that activation of PVN neurons leads to the release of ACTH, vasopressin, and oxytocin from the pituitary and a bradycardia that is mediated by the autonomic nervous system.

Glutamate mediated astrocytic filtering of neuronal activity.

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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.

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

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 �

Islet-selectivity of G-protein coupled receptor ligands evaluated for PET imaging of pancreatic {beta}-cell mass

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Cline, Gary W., E-mail: gary.cline@yale.edu [Yale University School of Medicine (United States); Zhao, Xiaojian [Yale University School of Medicine (United States); Jakowski, Amy B.; Soeller, Walter C.; Treadway, Judith L. [Pfizer Global Research and Development, Pfizer Inc., Groton CT (United States)

2011-09-02

Highlights: {yields} We screened G-protein coupled receptors for imaging pancreatic. {yields} Database mining and immunohistochemistry identified GPCRs enriched in {beta}-cells. {yields} In vitro and in vivo assays were used to determine exocrine vs endocrine specificity. {yields} GPCR candidates for imaging of {beta}-cell mass are Prokineticin-1R, mGluR5, and GLP-1R. -- Abstract: A critical unmet need exists for methods to quantitatively measure endogenous pancreatic {beta}-cell mass (BCM) for the clinical evaluation of therapies to prevent or reverse loss of BCM and diabetes progression. Our objective was to identify G-protein coupled receptors (GPCRs) that are expressed with a high degree of specificity to islet {beta}-cells for receptor-targeted imaging of BCM. GPCRs enriched in pancreatic islets relative to pancreas acinar and hepatic tissue were identified using a database screen. Islet-specific expression was confirmed by human pancreas immunohistochemistry (IHC). In vitro selectivity assessment was determined from the binding and uptake of radiolabeled ligands to the rat insulinoma INS-1 832/13 cell line and isolated rat islets relative to the exocrine pancreas cell-type, PANC-1. Tail-vein injections of radioligands into rats were used to determine favorable image criteria of in vivo biodistribution to the pancreas relative to other internal organs (i.e., liver, spleen, stomach, and lungs). Database and IHC screening identified four candidate receptors for further in vitro and in vivo evaluation for PET imaging of BCM: prokineticin-1 receptor (PK-1R), metabotropic glutamate receptor type-5 (mGluR5), neuropeptide Y-2 receptor (NPY-2R), and glucagon-like peptide 1 receptor (GLP-1R). In vitro specificity ratios gave the following receptor rank order: PK-1R > GLP-1R > NPY-2R > mGluR5. The biodistribution rank order of selectivity to the pancreas was found to be PK-1R > VMAT2 {approx} GLP-1R > mGluR5. Favorable islet selectivity and biodistribution

Islet-selectivity of G-protein coupled receptor ligands evaluated for PET imaging of pancreatic β-cell mass

International Nuclear Information System (INIS)

Cline, Gary W.; Zhao, Xiaojian; Jakowski, Amy B.; Soeller, Walter C.; Treadway, Judith L.

2011-01-01

Highlights: → We screened G-protein coupled receptors for imaging pancreatic. → Database mining and immunohistochemistry identified GPCRs enriched in β-cells. → In vitro and in vivo assays were used to determine exocrine vs endocrine specificity. → GPCR candidates for imaging of β-cell mass are Prokineticin-1R, mGluR5, and GLP-1R. -- Abstract: A critical unmet need exists for methods to quantitatively measure endogenous pancreatic β-cell mass (BCM) for the clinical evaluation of therapies to prevent or reverse loss of BCM and diabetes progression. Our objective was to identify G-protein coupled receptors (GPCRs) that are expressed with a high degree of specificity to islet β-cells for receptor-targeted imaging of BCM. GPCRs enriched in pancreatic islets relative to pancreas acinar and hepatic tissue were identified using a database screen. Islet-specific expression was confirmed by human pancreas immunohistochemistry (IHC). In vitro selectivity assessment was determined from the binding and uptake of radiolabeled ligands to the rat insulinoma INS-1 832/13 cell line and isolated rat islets relative to the exocrine pancreas cell-type, PANC-1. Tail-vein injections of radioligands into rats were used to determine favorable image criteria of in vivo biodistribution to the pancreas relative to other internal organs (i.e., liver, spleen, stomach, and lungs). Database and IHC screening identified four candidate receptors for further in vitro and in vivo evaluation for PET imaging of BCM: prokineticin-1 receptor (PK-1R), metabotropic glutamate receptor type-5 (mGluR5), neuropeptide Y-2 receptor (NPY-2R), and glucagon-like peptide 1 receptor (GLP-1R). In vitro specificity ratios gave the following receptor rank order: PK-1R > GLP-1R > NPY-2R > mGluR5. The biodistribution rank order of selectivity to the pancreas was found to be PK-1R > VMAT2 ∼ GLP-1R > mGluR5. Favorable islet selectivity and biodistribution characteristics suggest several GPCRs as potential

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

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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

Creatine affords protection against glutamate-induced nitrosative and oxidative stress.

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Cunha, Mauricio P; Lieberknecht, Vicente; Ramos-Hryb, Ana Belén; Olescowicz, Gislaine; Ludka, Fabiana K; Tasca, Carla I; Gabilan, Nelson H; Rodrigues, Ana Lúcia S

2016-05-01

Creatine has been reported to exert beneficial effects in several neurodegenerative diseases in which glutamatergic excitotoxicity and oxidative stress play an etiological role. The purpose of this study was to investigate the protective effects of creatine, as compared to the N-Methyl-d-Aspartate (NMDA) receptor antagonist dizocilpine (MK-801), against glutamate or hydrogen peroxide (H2O2)-induced injury in human neuroblastoma SH-SY5Y cells. Exposure of cells to glutamate (60-80 mM) or H2O2 (200-300 μM) for 24 h decreased cellular viability and increased dichlorofluorescein (DCF) fluorescence (indicative of increased reactive oxygen species, ROS) and nitric oxide (NO) production (assessed by mono-nitrogen oxides, NOx, levels). Creatine (1-10 mM) or MK-801 (0.1-10 μM) reduced glutamate- and H2O2-induced toxicity. The protective effect of creatine against glutamate-induced toxicity involves its antioxidant effect, since creatine, similar to MK-801, prevented the increase on DCF fluorescence induced by glutamate or H2O2. Furthermore, creatine or MK-801 blocked glutamate- and H2O2-induced increases in NOx levels. In another set of experiments, the repeated, but not acute, administration of creatine (300 mg/kg, po) in mice prevented the decreases on cellular viability and mitochondrial membrane potential (assessed by tetramethylrhodamine ethyl ester, TMRE, probe) of hippocampal slices incubated with glutamate (10 mM). Creatine concentration-dependent decreased the amount of nitrite formed in the reaction of oxygen with NO produced from sodium nitroprusside solution, suggesting that its protective effect against glutamate or H2O2-induced toxicity might be due to its scavenger activity. Overall, the results suggest that creatine may be useful as adjuvant therapy for neurodegenerative disease treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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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.

GluD1 is a common altered player in neuronal differentiation from both MECP2-mutated and CDKL5-mutated iPS cells.

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Livide, Gabriella; Patriarchi, Tommaso; Amenduni, Mariangela; Amabile, Sonia; Yasui, Dag; Calcagno, Eleonora; Lo Rizzo, Caterina; De Falco, Giulia; Ulivieri, Cristina; Ariani, Francesca; Mari, Francesca; Mencarelli, Maria Antonietta; Hell, Johannes Wilhelm; Renieri, Alessandra; Meloni, Ilaria

2015-02-01

Rett syndrome is a monogenic disease due to de novo mutations in either MECP2 or CDKL5 genes. In spite of their involvement in the same disease, a functional interaction between the two genes has not been proven. MeCP2 is a transcriptional regulator; CDKL5 encodes for a kinase protein that might be involved in the regulation of gene expression. Therefore, we hypothesized that mutations affecting the two genes may lead to similar phenotypes by dysregulating the expression of common genes. To test this hypothesis we used induced pluripotent stem (iPS) cells derived from fibroblasts of one Rett patient with a MECP2 mutation (p.Arg306Cys) and two patients with mutations in CDKL5 (p.Gln347Ter and p.Thr288Ile). Expression profiling was performed in CDKL5-mutated cells and genes of interest were confirmed by real-time RT-PCR in both CDKL5- and MECP2-mutated cells. The only major change in gene expression common to MECP2- and CDKL5-mutated cells was for GRID1, encoding for glutamate D1 receptor (GluD1), a member of the δ-family of ionotropic glutamate receptors. GluD1 does not form AMPA or NMDA glutamate receptors. It acts like an adhesion molecule by linking the postsynaptic and presynaptic compartments, preferentially inducing the inhibitory presynaptic differentiation of cortical neurons. Our results demonstrate that GRID1 expression is downregulated in both MECP2- and CDKL5-mutated iPS cells and upregulated in neuronal precursors and mature neurons. These data provide novel insights into disease pathophysiology and identify possible new targets for therapeutic treatment of Rett syndrome.

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 GDH...... was questioned here by generation of CNS-specific GDH-null mice (CnsGlud1(-/-)); which were viable, fertile and without apparent behavioral problems. GDH immunoreactivity as well as enzymatic activity were absent in Cns-Glud1(-/-) brains. Immunohistochemical analyses on brain sections revealed that the pyramidal...... oxidative catabolism of glutamate in astrocytes, showing that GDH is required for Krebs cycle pathway. As revealed by NMR studies, brain glutamate levels remained unchanged, whereas glutamine levels were increased. This pattern was favored by up-regulation of astrocyte-type glutamate and glutamine...

Pharmacological characterization and modeling of the binding sites of novel 1,3-bis(pyridinylethynyl)benzenes as metabotropic glutamate receptor 5-selective negative allosteric modulators

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Mølck, Christina; Harpsøe, Kasper; Gloriam, David E

2012-01-01

)pyridine (MPEP)-derived negative allosteric modulators, 2-, 3-, and 4-BisPEB, have been characterized. 2-, 3-, and 4-BisPEB are 1,3-bis(pyridinylethynyl)-benzenes and differ only by the position of the nitrogen atoms in the pyridine rings. Despite their high structural similarity, 2-BisPEB [1,3-bis(pyridin-2......-ylethynyl)-benzene, nitrogen atoms in ortho positions], with an IC(50) value in the nanomolar range, is significantly more potent than the 3- and 4-pyridyl analogs. Mutational analysis, directed by a previously published mGluR5 homology model, was used to determine key residues for the ligand...... that the higher potency of 2-BisPEB is due to hydrogen bonding to Ser809 because the S809A mutation made 2-BisPEB equipotent to 3- and 4-BisPEB (IC(50), 1-2.5 µM). The potency of MPEP was also greatly affected by S809A (52-fold), suggesting that a Ser809-mediated hydrogen bond is also a key interaction between...

Fluorescence imaging of glutamate release in neurons

International Nuclear Information System (INIS)

Wang, Ziqiang; Yeung, Edward S.

1999-01-01

A noninvasive detection scheme based on glutamate dehydrogenase (GDH) enzymatic assay combined with microscopy was developed to measure the glutamate release in cultured cells from the central nervous system (CNS). The enzyme reaction is very specific and sensitive. The detection limit with charge-coupled device (CCD) imaging is down to μM levels of glutamate with reasonable response time (∼30 s). The standard glutamate test shows a linear response over 3 orders of magnitude, from μM to 0.1 mM range. The in vitro monitoring of glutamate release from cultured neuron cells demonstrated excellent spatial and temporal resolution. (c) 1999 Society for Applied Spectroscopy

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

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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.

Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway

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Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng; Greig, Nigel H. [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States); Mattson, Mark P. [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States); Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Camandola, Simonetta, E-mail: camandolasi@mail.nih.gov [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States)

2013-04-19

Highlights: •Naphthazarin activates the Nrf2/ARE pathway. •Naphthazarin induces Nrf2-driven genes in neurons and astrocytes. •Naphthazarin protects neurons against excitotoxicity. -- Abstract: Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity.

Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway

International Nuclear Information System (INIS)

Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng; Greig, Nigel H.; Mattson, Mark P.; Camandola, Simonetta

2013-01-01

Highlights: •Naphthazarin activates the Nrf2/ARE pathway. •Naphthazarin induces Nrf2-driven genes in neurons and astrocytes. •Naphthazarin protects neurons against excitotoxicity. -- Abstract: Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity

Glutamate uptake is important for osmoregulation and survival in the rice pathogen Burkholderia glumae.

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Yongsung Kang

Full Text Available Bacteria exhibit an optimal growth rate in culture media with sufficient nutrients at an optimal temperature and pH. In addition, the concentration of solutes plays a critical role in bacterial growth and survival. Glutamate is known to be a major anionic solute involved in osmoregulation and the bacterial cell's response to changes in solute concentration. To determine how glutamate uptake is involved in osmoregulation in the rice bacterial pathogen Burkholderia glumae BGR1, we mutated the gltI gene encoding a periplasmic substrate binding protein of a glutamate transport system to abolish glutamate uptake, and monitored the growth of the gltI null mutant in Luria-Bertani medium. We found that the gltI null mutant showed a slower growth rate than the wild-type strain and experienced hyperosmotic stress resulting in water loss from the cytoplasm in stationary phase. When the incubation time was extended, the mutant population collapsed due to the hyperosmotic stress. The gltI null mutant exhibited loss of adaptability under both hypoosmotic and hyperosmotic stresses. The growth rate of the gltI null mutant was restored to the level of wild-type growth by exogenous addition of glycine betaine to the culture medium, indicating that glycine betaine is a compatible solute in B. glumae. These results indicate that glutamate uptake from the environment plays a key role in osmoregulation in B. glumae.

A novel stereospecific synthesis of 14C labeled 1-glutamic acid

International Nuclear Information System (INIS)

Wurz, R.E.; Kepner, R.E.; Webb, A.D.

1989-01-01

A stereospecific synthesis of 4- 14 C-1-glutamic acid was completed in five steps from sodium 2- 14 C-acetate. The morpholine derived enamine of ethyl pyruvate was reacted with ethyl 2- 14 C-bromoacetate to give after hydrolysis diethyl 4- 14 C-2-oxoglutarate. The 2-oxoglutarate was reacted with hydroxylamine hydrochloride to give diethyl 4-14C-2-hydroxyiminoglutarate which was then reduced with a LiAlH4, (-)-N-methylephedrine and 3,5-dimethylphenol mixture to give 4- 14 C-1-glutamic acid. The 4- 14 C-1-glutamic acid was used in investigations into the biosynthesis of gamma-lactones in sherries

GLT-1 Transport Stoichiometry Is Constant at Low and High Glutamate Concentrations when Chloride Is Substituted by Gluconate.

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Anatoli Y Kabakov

Full Text Available Glutamate is the major excitatory neurotransmitter, but prolonged exposure even at micromolar concentrations causes neuronal death. Extracellular glutamate is maintained at nanomolar level by glutamate transporters, which, however, may reverse transport and release glutamate. If and when the reverse occurs depends on glutamate transport stoichiometry (GTS. Previously we found that in the presence of chloride, the coupled GLT-1 glutamate transporter current and its relationship to radiolabeled glutamate flux significantly decreased when extracellular glutamate concentration increased above 0.2 mM, which implies a change in GTS. Such high concentrations are feasible near GLT-1 expressed close to synaptic release site during excitatory neurotransmission. The aim of this study was to determine GLT-1 GTS at both low (19-75 μM and high (300-1200 μM glutamate concentration ranges. GTS experiments were conducted in the absence of chloride to avoid contributions by the GLT-1 uncoupled chloride conductance. Mathematical analysis of the transporter thermodynamic equilibrium allowed us to derive equations revealing the number of a particular type of ion transported per elementary charge based on the measurements of the transporter reversal potential. We found that GLT-1a expressed in COS-7 cells co-transports 1.5 Na+, 0.5 Glu-, 0.5 H+ and counter-transports 0.6 K+ per elementary charge in both glutamate concentration ranges, and at both 37°C and 26°C temperatures. The thermodynamic parameter Q10 = 2.4 for GLT-1 turnover rate of 19 s-1 (37°C, -50 mV remained constant in the 10 μM-10 mM glutamate concentration range. Importantly, the previously reported decrease in the current/flux ratio at high glutamate concentration was not seen in the absence of chloride in both COS-7 cells and cultured rat neurons. Therefore, only in the absence of chloride, GLT-1 GTS remains constant at all glutamate concentrations. Possible explanations for why apparent GTS might

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

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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)

The odyssey of a young gene: structure-function studies in human glutamate dehydrogenases reveal evolutionary-acquired complex allosteric regulation mechanisms.

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Zaganas, Ioannis V; Kanavouras, Konstantinos; Borompokas, Nikolas; Arianoglou, Giovanna; Dimovasili, Christina; Latsoudis, Helen; Vlassi, Metaxia; Mastorodemos, Vasileios

2014-01-01

Mammalian glutamate dehydrogenase (GDH) catalyzes the reversible inter-conversion of glutamate to α-ketoglutarate and ammonia, interconnecting carbon skeleton and nitrogen metabolism. In addition, it functions as an energy switch by its ability to fuel the Krebs cycle depending on the energy status of the cell. As GDH lies at the intersection of several metabolic pathways, its activity is tightly regulated by several allosteric compounds that are metabolic intermediates. In contrast to other mammals that have a single GDH-encoding gene, humans and great apes possess two isoforms of GDH (hGDH1 and hGDH2, encoded by the GLUD1 and GLUD2 genes, respectively) with distinct regulation pattern, but remarkable sequence similarity (they differ, in their mature form, in only 15 of their 505 amino-acids). The GLUD2 gene is considered a very young gene, emerging from the GLUD1 gene through retro-position only recently (<23 million years ago). The new hGDH2 iso-enzyme, through random mutations and natural selection, is thought to have conferred an evolutionary advantage that helped its persistence through primate evolution. The properties of the two highly homologous human GDHs have been studied using purified recombinant hGDH1 and hGDH2 proteins obtained by expression of the corresponding cDNAs in Sf21 cells. According to these studies, in contrast to hGDH1 that maintains basal activity at 35-40 % of its maximal, hGDH2 displays low basal activity that is highly responsive to activation by rising levels of ADP and/or L-leucine which can also act synergistically. While hGDH1 is inhibited potently by GTP, hGDH2 shows remarkable GTP resistance. Furthermore, the two iso-enzymes are differentially inhibited by estrogens, polyamines and neuroleptics, and also differ in heat-lability. To elucidate the molecular mechanisms that underlie these different regulation patterns of the two iso-enzymes (and consequently the evolutionary adaptation of hGDH2 to a new functional role), we have

Sexual attraction enhances glutamate transmission in mammalian anterior cingulate cortex

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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.

21 CFR 182.1047 - Glutamic acid hydrochloride.

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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...

Neurochemical and behavioral characterization of neuronal glutamate transporter EAAT3 heterozygous mice

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Luis F. González

2017-10-01

Full Text Available Abstract Background Obsessive–compulsive disorder (OCD is a severe neuropsychiatric condition affecting 1–3% of the worldwide population. OCD has a strong genetic component, and the SLC1A1 gene that encodes neuronal glutamate transporter EAAT3 is a strong candidate for this disorder. To evaluate the impact of reduced EAAT3 expression in vivo, we studied male EAAT3 heterozygous and wild-type littermate mice using a battery of behavioral paradigms relevant to anxiety (open field test, elevated plus maze and compulsivity (marble burying, as well as locomotor activity induced by amphetamine. Using high-performance liquid chromatography, we also determined tissue neurotransmitter levels in cortex, striatum and thalamus—brain areas that are relevant to OCD. Results Compared to wild-type littermates, EAAT3 heterozygous male mice have unaltered baseline anxiety-like, compulsive-like behavior and locomotor activity. Administration of acute amphetamine (5 mg/kg intraperitoneally increased locomotion with no differences across genotypes. Tissue levels of glutamate, GABA, dopamine and serotonin did not vary between EAAT3 heterozygous and wild-type mice. Conclusions Our results indicate that reduced EAAT3 expression does not impact neurotransmitter content in the corticostriatal circuit nor alter anxiety or compulsive-like behaviors.

Mechanical, thermal and morphological properties of glutaraldehyde crosslinked bovine pericardium followed by glutamic acid treatment

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Gilberto Goissis

2009-03-01

Full Text Available Major problems with valve bioprostheses are associated with progressive structural deterioration and calcification, directly associated with the use of glutaraldehyde (GA. This work describes the effects of GA processing and borate/glutamic acid buffer treatment on the mechanical, thermal and morphological properties of 0.5% GA crosslinked bovine pericardium (BP. The results showed that while the treatment of 0.5% GA crosslinked BP with borate/glutamic acid significantly improves the mechanical properties, it had no visible effect on surface morphology. Better surface preservation was only achieved for BP pre-treated with a lower GA concentration followed by the conventional treatment (0.5% GA. Improvements in mechanical properties probably arises from structural changes probably involving the depolymerization of polymeric GA crosslinks and an increase electrostatic interaction due to covalent binding of glutamic acid to free carbonyl groups (Schiff base.The results indicate that the treatment GA crosslinked BP with borate/glutamic acid buffer may be an attractive procedure for the manufacture of heart valve bioprostheses.

Evidence for presynaptically silent synapses in the immature hippocampus

International Nuclear Information System (INIS)

Yoon, Jae Young; Choi, Sukwoo

2017-01-01

Silent synapses show NMDA receptor (NMDAR)-mediated synaptic responses, but not AMPAR-mediated synaptic responses. A prevailing hypothesis states that silent synapses contain NMDARs, but not AMPARs. However, alternative presynaptic hypotheses, according to which AMPARs are present at silent synapses, have been proposed; silent synapses show slow glutamate release via a fusion pore, and glutamate spillover from the neighboring synaptic terminals. Consistent with these presynaptic hypotheses, the peak glutamate concentrations at silent synapses have been estimated to be ≪170 μM, much lower than those seen at functional synapses. Glutamate transients predicted based on the two presynaptic mechanisms have been shown to activate only high-affinity NMDARs, but not low-affinity AMPARs. Interestingly, a previous study has developed a new approach to distinguish between the two presynaptic mechanisms using dextran, an inert macromolecule that reduces the diffusivity of released glutamate: postsynaptic responses through the fusion pore mechanism, but not through the spillover mechanism, are potentiated by reduced glutamate diffusivity. Therefore, we reasoned that if the fusion pore mechanism underlies silent synapses, dextran application would reveal AMPAR-mediated synaptic responses at silent synapses. In the present study, we recorded AMPAR-mediated synaptic responses at the CA3-CA1 synapses in neonatal rats in the presence of blockers for NMDARs and GABAARs. Bath application of dextran revealed synaptic responses at silent synapses. GYKI53655, a selective AMPAR-antagonist, completely inhibited the unsilenced synaptic responses, indicating that the unsilenced synaptic responses are mediated by AMPARs. The dextran-mediated reduction in glutamate diffusivity would also lead to the activation of metabotropic glutamate receptors (mGluRs), which might induce unsilencing via the activation of unknown intracellular signaling. Hence, we determined whether mGluR-blockers alter

Screening key candidate genes and pathways involved in insulinoma by microarray analysis.

Science.gov (United States)

Zhou, Wuhua; Gong, Li; Li, Xuefeng; Wan, Yunyan; Wang, Xiangfei; Li, Huili; Jiang, Bin

2018-06-01

Insulinoma is a rare type tumor and its genetic features remain largely unknown. This study aimed to search for potential key genes and relevant enriched pathways of insulinoma.The gene expression data from GSE73338 were downloaded from Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified between insulinoma tissues and normal pancreas tissues, followed by pathway enrichment analysis, protein-protein interaction (PPI) network construction, and module analysis. The expressions of candidate key genes were validated by quantitative real-time polymerase chain reaction (RT-PCR) in insulinoma tissues.A total of 1632 DEGs were obtained, including 1117 upregulated genes and 514 downregulated genes. Pathway enrichment results showed that upregulated DEGs were significantly implicated in insulin secretion, and downregulated DEGs were mainly enriched in pancreatic secretion. PPI network analysis revealed 7 hub genes with degrees more than 10, including GCG (glucagon), GCGR (glucagon receptor), PLCB1 (phospholipase C, beta 1), CASR (calcium sensing receptor), F2R (coagulation factor II thrombin receptor), GRM1 (glutamate metabotropic receptor 1), and GRM5 (glutamate metabotropic receptor 5). DEGs involved in the significant modules were enriched in calcium signaling pathway, protein ubiquitination, and platelet degranulation. Quantitative RT-PCR data confirmed that the expression trends of these hub genes were similar to the results of bioinformatic analysis.The present study demonstrated that candidate DEGs and enriched pathways were the potential critical molecule events involved in the development of insulinoma, and these findings were useful for better understanding of insulinoma genesis.

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

Introduction to the Glutamate-Glutamine Cycle.

Science.gov (United States)

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 but more recent research has seriously questioned this.This volume of Advances in Neurobiology is intended to provide a detailed discussion of recent developments in research aimed at delineating the functional roles of the cycle taking into account that in order for this system to work there must be a tight coupling between metabolism of glutamate in astrocytes, transfer of glutamine to neurons and de novo synthesis of glutamine in astrocytes. To understand this, knowledge about the activity and regulation of the enzymes and transporters involved in these processes is required and as can be seen from the table of contents these issues will be dealt with in detail in the individual chapters of the book.

The role of glutamate and its receptors in autism and the use of glutamate receptor antagonists in treatment

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Rojas, Donald C.

2014-01-01

Glutamate is the major excitatory neurotransmitter in the brain and may be a key neurotransmitter involved in autism. Literature pertaining to glutamate and autism or related disorders (e.g., Fragile X syndrome) is reviewed in this article. Interest in glutamatergic dysfunction in autism is high due to increasing convergent evidence implicating the system in the disorder from peripheral biomarkers, neuroimaging, protein expression, genetics and animal models. Currently, there are no pharmaceutical interventions approved for autism that address glutamate deficits in the disorder. New treatments related to glutamatergic neurotransmission, however, are emerging. In addition, older glutamate-modulating medications with approved indications for use in other disorders are being investigated for re-tasking as treatments for autism. This review presents evidence in support of glutamate abnormalities in autism and the potential for translation into new treatments for the disorder. PMID:24752754

Influence of the glutamic acid content of the diet on the catabolic rate of labelled glutamic acid in rats. 2

International Nuclear Information System (INIS)

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

1984-01-01

40 rats with a body weight of 100 g received 7 semisynthetic diets with different contents of glutamic acid and one diet contained whole-egg. A L-amino acid mixture corresponding to the pattern of egg protein was the protein source of the semisynthetic diets. Glutamic acid was supplemented succesively from 0 to 58 mol-% of the total amino acid content. On the 8th day of the experimental feeding the animals were labelled by subcutaneous injection of 14 C-glutamic acid. Subsequently the CO 2 and the 14 CO 2 excretion were measured for 24 hours. In this period 64 to 68 % of the injected radioactivity were recovered as 14 CO 2 . The curve pattern of 14 CO 2 excretion indicates two different processes of 14 CO 2 formation. One characterizing the direct degradation of glutamic acid to CO 2 with a high rate constant and a second one with a lower rate constant characterizing the 14 CO 2 formation via metabolites of glutamic acid. 77 % of the total 14 CO 2 excretion in 24 hours resulted from the direct oxidation of glutamic acid and 23 % from the oxidation of intermediates. When 14 CO 2 formation was measured 10 to 24 hours after injection of 14 C-glutamic acid a positive correlation to the content of glutamic acid in the diet was observed. The intestinal tissue contributes considerably to the catabolization of glutamic acid, however, there seems to exist an upper limit for this capacity. (author)

Properties of glutamate-gated ion channels in horizontal cells of the perch retina.

Science.gov (United States)

Schmidt, K F

1997-08-01

The effect of two different concentrations of L-glutamate and kainate on the gating kinetics of amino acid-sensitive non-NMDA channels were studied in cultured teleost retinal horizontal cells by single-channel recording and by noise analysis of whole-cell currents. When the glutamate agonist kainate was applied clearly parabolic mean-variance relations of whole-cell membrane currents (up to 3000 pA) indicated that this agonist was acting on one type of channels with a conductance of 5-10 pS. The cells were less sensitive when L-glutamate was used as the agonist and in most cases whole-cell currents amounted to less than 200 pA. The mean-variance relation of glutamate induced currents was complex, indicating that more than one type of channel opening could be involved. Power spectra of whole-cell currents were fitted with two Lorentzians with time constants of approx. 1 and 5-20 msec. Effects on amplitudes and time constants of agonist concentrations are demonstrated. Two categories of unitary events with mean open times of approx. 1 and 7 msec and conductances of approx. 7 and 12 pS, respectively, were obtained in single-channel recordings from cell-attached patches at different concentrations of glutamate in the pipette.

A novel reagentless glutamate microband biosensor for real-time cell toxicity monitoring

Energy Technology Data Exchange (ETDEWEB)

Hughes, G.; Pemberton, R.M. [Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Bristol, Coldharbour Lane, Bristol, BS16 1QY (United Kingdom); Fielden, P.R. [Department of Chemistry, Lancaster University, Bailrigg, Lancaster, LA1 4YB (United Kingdom); Hart, J.P., E-mail: john.hart@uwe.ac.uk [Centre for Research in Biosciences, Faculty of Health and Applied Sciences, University of the West of England, Bristol, Coldharbour Lane, Bristol, BS16 1QY (United Kingdom)

2016-08-24

A reagentless glutamate biosensor was applied to the determination of glutamate released from liver hepatocellular carcinoma cells (HepG2) in response to toxic challenge from various concentrations of paracetamol. A screen printed carbon electrode (SPCE) containing the electrocatalyst Meldola's Blue (MB-SPCE) served as the electron mediator for the oxidation of NADH. A mixture of the enzyme glutamate dehydrogenase (GLDH), cofactor nicotinamide adenine dinucleotide (NAD{sup +}) and the biopolymer chitosan (CHIT) were drop-coated onto the surface of the transducer (MB-SPCE) in a simple one step fabrication process. The reagentless biosensor was used with amperometry in stirred solution at an applied potential of +0.1 V (vs. Ag/AgCl). All experiments were carried out at the following conditions: pH 7, temperature 37 °C, atmosphere 5% CO{sub 2}. The linear range of the device was found to be 25–125 μM in phosphate buffer (75 mM, containing 0.05 M NaCl) and 25–150 μM in cell culture medium. The limits of detection (LOD) were found to be 1.2 μM and 4.2 μM based on three times signal to noise, using PBS and culture medium respectively. The sensitivity was calculated to be 106 nA μM{sup −1} cm{sup −2} and 210 nA μM{sup −1} cm{sup −2} in PBS and cell medium respectively. The response time was ∼60 s in an agitated solution. HepG2 cells were exposed to various concentrations of paracetamol (1 mM, 5 mM and 10 mM) in order to investigate the drug-induced release of glutamate into the culture medium in real time. Two toxicity studies were investigated using different methods of exposure and analysis. The first method consisted of a single measurement of the glutamate concentration, using the method of standard addition, after 24 h incubation. The concentrations of glutamate were found to be 52 μM, 93 μM and 177 μM, released on exposure to 1 mM, 5 mM and 10 mM paracetamol respectively. The second method involved the

A novel reagentless glutamate microband biosensor for real-time cell toxicity monitoring

International Nuclear Information System (INIS)

Hughes, G.; Pemberton, R.M.; Fielden, P.R.; Hart, J.P.

2016-01-01

A reagentless glutamate biosensor was applied to the determination of glutamate released from liver hepatocellular carcinoma cells (HepG2) in response to toxic challenge from various concentrations of paracetamol. A screen printed carbon electrode (SPCE) containing the electrocatalyst Meldola's Blue (MB-SPCE) served as the electron mediator for the oxidation of NADH. A mixture of the enzyme glutamate dehydrogenase (GLDH), cofactor nicotinamide adenine dinucleotide (NAD"+) and the biopolymer chitosan (CHIT) were drop-coated onto the surface of the transducer (MB-SPCE) in a simple one step fabrication process. The reagentless biosensor was used with amperometry in stirred solution at an applied potential of +0.1 V (vs. Ag/AgCl). All experiments were carried out at the following conditions: pH 7, temperature 37 °C, atmosphere 5% CO_2. The linear range of the device was found to be 25–125 μM in phosphate buffer (75 mM, containing 0.05 M NaCl) and 25–150 μM in cell culture medium. The limits of detection (LOD) were found to be 1.2 μM and 4.2 μM based on three times signal to noise, using PBS and culture medium respectively. The sensitivity was calculated to be 106 nA μM"−"1 cm"−"2 and 210 nA μM"−"1 cm"−"2 in PBS and cell medium respectively. The response time was ∼60 s in an agitated solution. HepG2 cells were exposed to various concentrations of paracetamol (1 mM, 5 mM and 10 mM) in order to investigate the drug-induced release of glutamate into the culture medium in real time. Two toxicity studies were investigated using different methods of exposure and analysis. The first method consisted of a single measurement of the glutamate concentration, using the method of standard addition, after 24 h incubation. The concentrations of glutamate were found to be 52 μM, 93 μM and 177 μM, released on exposure to 1 mM, 5 mM and 10 mM paracetamol respectively. The second method involved the continuous monitoring of glutamate

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.

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.

Quantitative autoradiographic distribution of L-[3H]glutamate-binding sites in rat central nervous system

International Nuclear Information System (INIS)

Greenamyre, J.T.; Young, A.B.; Penney, J.B.

1984-01-01

Quantitative autoradiography was used to determine the distribution of L-[3H]glutamate-binding sites in the rat central nervous system. Autoradiography was carried out in the presence of Cl- and Ca2+ ions. Scatchard plots and Hill coefficients of glutamate binding suggested that glutamate was interacting with a single population of sites having a K-D of about 300 nM and a capacity of 14.5 pmol/mg of protein. In displacement studies, ibotenate also appeared to bind to a single class of non-interacting sites with a KI of 28 microM. However, quisqualate displacement of [3H]glutamate binding revealed two well-resolved sites with KIS of 12 nM and 114 microM in striatum. These sites were unevenly distributed, representing different proportions of specific glutamate binding in different brain regions. The distribution of glutamate-binding sites correlated very well with the projection areas of putative glutamatergic pathways. This technique provides an extremely sensitive assay which can be used to gather detailed pharmacological and anatomical information about L-[3H]glutamate binding in the central nervous system

Amino acid transamination is crucial for ischaemic cardioprotection in normal and preconditioned isolated rat hearts--focus on L-glutamate

DEFF Research Database (Denmark)

Løfgren, Bo; Povlsen, Jonas Agerlund; Rasmussen, Lars Ege

2010-01-01

We have found that cardioprotection by l-glutamate mimics protection by classical ischaemic preconditioning (IPC). We investigated whether the effect of IPC involves amino acid transamination and whether IPC modulates myocardial glutamate metabolism. In a glucose-perfused, isolated rat heart model...... subjected to 40 min global no-flow ischaemia and 120 min reperfusion, the effects of IPC (2 cycles of 5 min ischaemia and 5 min reperfusion) and continuous glutamate (20 mm) administration during reperfusion on infarct size and haemodynamic recovery were studied. The effect of inhibiting amino acid...... transamination was evaluated by adding the amino acid transaminase inhibitor amino-oxyacetate (AOA; 0.025 mm) during reperfusion. Changes in coronary effluent, interstitial (microdialysis) and intracellular glutamate ([GLUT](i)) concentrations were measured. Ischaemic preconditioning and postischaemic glutamate...

Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway.

Science.gov (United States)

Son, Tae Gen; Kawamoto, Elisa M; Yu, Qian-Sheng; Greig, Nigel H; Mattson, Mark P; Camandola, Simonetta

2013-04-19

Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity. Published by Elsevier Inc.

A novel dendrimer based on poly (L-glutamic acid) derivatives as an efficient and biocompatible gene delivery vector

International Nuclear Information System (INIS)

Zeng Xin; Pan Shirong; Wang Chi; Wen Yuting; Wu Hongmei; Wang Cuifeng; Wu Chuanbin; Feng Min; Li Jie

2011-01-01

Non-viral gene delivery systems based on cationic polymers have faced limitations related to their relative low gene transfer efficiency, cytotoxicity and system instability in vivo. In this paper, a flexible and pompon-like dendrimer composed of poly (amidoamine) (PAMAM) G4.0 as the inner core and poly (L-glutamic acid) grafted low-molecular-weight polyethylenimine (PLGE) as the surrounding multiple arms was synthesized (MGI dendrimer). The novel MGI dendrimer was designed to combine the merits of size-controlled PAMAM G4.0 and the low toxicity and flexible chains of PLGE. In phosphate-buffered saline dispersions the well-defined DNA/MGI complex above a N/P ratio of 30 showed good stability with particle sizes of approximately 200 nm and a comparatively low polydispersity index. However, the particle size of the DNA/25 kDa polyethylenimine (DNA/PEI 25K) complex was larger than 700 nm under the same salt conditions. The shielding of the compact amino groups at the periphery of flexible PAMAM and biocompatible PLGE chains in MGI resulted in a dramatic decrease of the cytotoxicity compared to native PAMAM G4.0 dendrimer. The in vitro transfection efficiency of DNA/MGI dendrimer complex was higher than that of PAMAM G4.0 dendrimer. Importantly, in serum-containing medium, DNA/MGI complexes at their optimal N/P ratio maintained the same high levels of transfection efficiency as in serum-free medium, while the transfection efficiency of native PAMAM G4.0, PEI 25K and Lipofectamine 2000 were sharply decreased. In vivo gene delivery of pVEGF165/MGI complex into balloon-injured rabbit carotid arteries resulted in significant inhibition of restenosis by increasing VEGF165 expression in local vessels. Therefore, the pompon-like MGI dendrimer may be a promising vector candidate for efficient gene delivery in vivo.

Transcriptomic responses in mouse brain exposed to chronic excess of the neurotransmitter glutamate

Directory of Open Access Journals (Sweden)

Pal Ranu