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Sample records for metabotropic glutamate receptor-dependent

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

    Directory of Open Access Journals (Sweden)

    Atsushi Tamura

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

  2. Therapeutic Promise and Principles: Metabotropic Glutamate Receptors

    Directory of Open Access Journals (Sweden)

    Kenneth Maiese

    2008-01-01

    Full Text Available For a number of disease entities, oxidative stress becomes a significant factor in the etiology and progression of cell dysfunction and injury. Therapeutic strategies that can identify novel signal transduction pathways to ameliorate the toxic effects of oxidative stress may lead to new avenues of treatment for a spectrum of disorders that include diabetes, Alzheimer's disease, Parkinson's disease and immune system dysfunction. In this respect, metabotropic glutamate receptors (mGluRs may offer exciting prospects for several disorders since these receptors can limit or prevent apoptotic cell injury as well as impact upon cellular development and function. Yet the role of mGluRs is complex in nature and may require specific mGluR modulation for a particular disease entity to maximize clinical efficacy and limit potential disability. Here we discuss the potential clinical translation of mGluRs and highlight the role of novel signal transduction pathways in the metabotropic glutamate system that may be vital for the clinical utility of mGluRs.

  3. Therapeutic promise and principles: metabotropic glutamate receptors.

    Science.gov (United States)

    Maiese, Kenneth; Chong, Zhao Zhong; Shang, Yan Chen; Hou, Jinling

    2008-01-01

    For a number of disease entities, oxidative stress becomes a significant factor in the etiology and progression of cell dysfunction and injury. Therapeutic strategies that can identify novel signal transduction pathways to ameliorate the toxic effects of oxidative stress may lead to new avenues of treatment for a spectrum of disorders that include diabetes, Alzheimer's disease, Parkinson's disease and immune system dysfunction. In this respect, metabotropic glutamate receptors (mGluRs) may offer exciting prospects for several disorders since these receptors can limit or prevent apoptotic cell injury as well as impact upon cellular development and function. Yet the role of mGluRs is complex in nature and may require specific mGluR modulation for a particular disease entity to maximize clinical efficacy and limit potential disability. Here we discuss the potential clinical translation of mGluRs and highlight the role of novel signal transduction pathways in the metabotropic glutamate system that may be vital for the clinical utility of mGluRs.

  4. Metabotropic glutamate receptors: From the workbench to the bedside

    OpenAIRE

    Nicoletti, F.; Bockaert, J; Collingridge, G L; Conn, P. J.; Ferraguti, F.; Schoepp, D. D.; Wroblewski, J T; Pin, J P

    2010-01-01

    Metabotropic glutamate (mGlu) receptors were discovered in the mid 1980s and originally described as glutamate receptors coupled to polyphosphoinositide hydrolysis. Almost 6500 articles have been published since then, and subtype-selective mGlu receptor ligands are now under clinical development for the treatment of a variety of disorders such as Fragile-X syndrome, schizophrenia, Parkinson’s disease and L-DOPA-induced dyskinesias, generalized anxiety disorder, chronic pain, and gastroesophag...

  5. [Metabotropic glutamate receptors as targets for new drug development].

    Science.gov (United States)

    Arkhipov, V I; Kapralova, M V

    2011-01-01

    The review is devoted to experimental investigations of metabotropic glutamate receptors and the properties of drugs (ligands) belonging to agonists, antagonists, and modulators of the activity of these receptors. Possibilities of the treatment of neurodegenerative disorders, cognitive disturbances in schizophrenia patients, and narcotic dependency by using drugs of this class are considered.

  6. The Role of Metabotropic Glutamate Receptor Genes in Schizophrenia.

    Science.gov (United States)

    Maj, Carlo; Minelli, Alessandra; Giacopuzzi, Edoardo; Sacchetti, Emilio; Gennarelli, Massimo

    2016-01-01

    Genomic studies revealed two main components in the genetic architecture of schizophrenia, one constituted by common variants determining a distributed polygenic effect and one represented by a large number of heterogeneous rare and highly disruptive mutations. These gene modifications often affect neural transmission and different studies proved an involvement of metabotropic glutamate receptors in schizophrenia phenotype. Through the combination of literature information with genomic data from public repositories, we analyzed the current knowledge on the involvement of genetic variations of the human metabotropic glutamate receptors in schizophrenia and related endophenotypes. Despite the analysis did not reveal a definitive connection, different suggestive associations have been identified and in particular a relevant role has emerged for GRM3 in affecting specific schizophrenia endophenotypes. This supports the hypothesis that these receptors are directly involved in schizophrenia disorder.

  7. Metabotropic Glutamate Receptors and Interacting Proteins in Epileptogenesis.

    Science.gov (United States)

    Qian, Feng; Tang, Feng-Ru

    2016-01-01

    Neurotransmitter and receptor systems are involved in different neurological and neuropsychological disorders such as Parkinson's disease, depression, Alzheimer's disease and epilepsy. Recent advances in studies of signal transduction pathways or interacting proteins of neurotransmitter receptor systems suggest that different receptor systems may share the common signal transduction pathways or interacting proteins which may be better therapeutic targets for development of drugs to effectively control brain diseases. In this paper, we reviewed metabotropic glutamate receptors (mGluRs) and their related signal transduction pathways or interacting proteins in status epilepticus and temporal lobe epilepsy, and proposed some novel therapeutical drug targets for controlling epilepsy and epileptogenesis.

  8. Metabotropic glutamate receptors: From the workbench to the bedside

    Science.gov (United States)

    Nicoletti, F.; Bockaert, J.; Collingridge, G.L.; Conn, P.J.; Ferraguti, F.; Schoepp, D.D.; Wroblewski, J.T.; Pin, J.P.

    2013-01-01

    Metabotropic glutamate (mGlu) receptors were discovered in the mid 1980s and originally described as glutamate receptors coupled to polyphosphoinositide hydrolysis. Almost 6500 articles have been published since then, and subtype-selective mGlu receptor ligands are now under clinical development for the treatment of a variety of disorders such as Fragile-X syndrome, schizophrenia, Parkinson’s disease and L-DOPA-induced dyskinesias, generalized anxiety disorder, chronic pain, and gastroesophageal reflux disorder. Prof. Erminio Costa was linked to the early times of the mGlu receptor history, when a few research groups challenged the general belief that glutamate could only activate ionotropic receptors and all metabolic responses to glutamate were secondary to calcium entry. This review moves from those nostalgic times to the most recent advances in the physiology and pharmacology of mGlu receptors, and highlights the role of individual mGlu receptor subtypes in the pathophysiology of human disorders. This article is part of a Special Issue entitled ‘Trends in Neuropharmacology: In Memory of Erminio Costa’. PMID:21036182

  9. Metabotropic glutamate receptor 5 upregulates surface NMDA receptor expression in striatal neurons via CaMKII

    OpenAIRE

    Jin, Dao-Zhong; Xue, Bing; Mao, Li-Min; Wang, John Q

    2015-01-01

    Metabotropic and ionotropic glutamate receptors are closely clustered in postsynaptic membranes and are believed to interact actively with each other to control excitatory synaptic transmission. Metabotropic glutamate receptor 5 (mGluR5), for example, has been well documented to potentiate ionotropic NMDA receptor activity, although underlying mechanisms are poorly understood. In this study, we investigated the role of mGluR5 in regulating trafficking and subcellular distribution of NMDA rece...

  10. Metabotropic glutamate receptor blockade in nucleus accumbens shell shifts affective valence toward fear and displeasure

    OpenAIRE

    Richard, Jocelyn M.; Berridge, Kent C

    2010-01-01

    Glutamatergic inputs to the nucleus accumbens (NAc) modulate both appetitive and fearful motivation. Pathological disturbances of glutamate signaling in NAc have been suggested to contribute to motivation disorders, ranging from excessive desire in drug addiction to paranoia in schizophrenia. Metabotropic glutamate receptors are of special interest, as metabotropic Group II receptor (mglu2/3) agonists have been proposed as potential treatments for both addiction and schizophrenia. Here we tes...

  11. Glutamate-induced swelling of cultured astrocytes is mediated by metabotropic glutamate receptor

    Institute of Scientific and Technical Information of China (English)

    袁芳; 王天佑

    1996-01-01

    The effects of glutamate and its agonists and antagonists on the swelling of cultured astrocytes were studied. Swelling of astrocytes was measured by [3H]-O-methyl-D-glucose uptake. Glutamate at 0.5, 1 and 10mmol/L and irons-l-aminocyclopentane-1,3-dicarboxylic acid (trans-ACPD), a metabotropic glutamate receptor (mGluR) agonist, at 1 mmol/L caused a significant increase in astrocytic volume, whereas alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) was not effective. L-2-amino-3-phosphonopropionic acid (L-AP3), an antagonist of mGluR, blocked the astrocytic swelling induced by trans-ACPD or glutamate. In Ca2+-free condition, glutamate was no longer effective. Swelling of astrocytes induced by glutamate was not blocked by CdCl2 at 20 μmol/L, but significantly reduced by CdCl2 at 300 μmol/L and dantrolene at 30 μmol/L. These findings indicate that mGluR activation results in astrocytic swelling and both extracellular calcium and internal calcium stores play important roles in the genes

  12. Metabotropic glutamate receptors and interacting proteins: evolving drug targets.

    Science.gov (United States)

    Enz, Ralf

    2012-01-01

    The correct targeting, localization, regulation and signaling of metabotropic glutamate receptors (mGluRs) represent major mechanisms underlying the complex function of neuronal networks. These tasks are accomplished by the formation of synaptic signal complexes that integrate functionally related proteins such as neurotransmitter receptors, enzymes and scaffold proteins. By these means, proteins interacting with mGluRs are important regulators of glutamatergic neurotransmission. Most described mGluR interaction partners bind to the intracellular C-termini of the receptors. These domains are extensively spliced and phosphorylated, resulting in a high variability of binding surfaces offered to interacting proteins. Malfunction of mGluRs and associated proteins are linked to neurodegenerative and neuropsychiatric disorders including addiction, depression, epilepsy, schizophrenia, Alzheimer's, Huntington's and Parkinson's disease. MGluR associated signal complexes are dynamic structures that assemble and disassemble in response to the neuronal fate. This, in principle, allows therapeutic intervention, defining mGluRs and interacting proteins as promising drug targets. In the last years, several studies elucidated the geometry of mGluRs in contact with regulatory proteins, providing a solid fundament for the development of new therapeutic strategies. Here, I will give an overview of human disorders directly associated with mGluR malfunction, provide an up-to-date summary of mGluR interacting proteins and highlight recently described structures of mGluR domains in contact with binding partners.

  13. The preclinical properties of a novel group II metabotropic glutamate receptor agonist LY379268

    NARCIS (Netherlands)

    Imre, Gabor

    2007-01-01

    Activation of group II metabotropic glutamate (mGlu2/3) receptors reduces excessive glutamate release that is often associated with neurodegenerative and psychiatric disorders. This finding encouraged the search for potent and selective agonists as potential therapeutic agents. The search led to the

  14. Metabotropic glutamate receptor-mediated signaling dampens the HPA axis response to restraint stress.

    Science.gov (United States)

    Evanson, Nathan K; Herman, James P

    2015-10-15

    Glutamate is an important neurotransmitter in the regulation of the neural portion of hypothalamus-pituitary-adrenal (HPA) axis activity, and signals through ionotropic and metabotropic receptors. In the current studies we investigated the role of hypothalamic paraventricular group I metabotropic glutamate receptors in the regulation of the HPA axis response to restraint stress in rats. Direct injection of the group I metabotropic glutamate receptor agonist 3,5-dihydroxyphenylglycine (DHPG) into the PVN prior to restraint leads to blunting of the HPA axis response in awake animals. Consistent with this result, infusion of the group I receptor antagonist hexyl-homoibotenic acid (HIBO) potentiates the HPA axis response to restraint. The excitatory effect of blocking paraventricular group I metabotropic glutamate signaling is blocked by co-administration of dexamethasone into the PVN. However, the inhibitory effect of DHPG is not affected by co-administration of the cannabinoid CB1 receptor antagonist AM-251 into the PVN. Together, these results suggest that paraventricular group I metabotropic glutamate receptor signaling acts to dampen HPA axis reactivity. This effect appears to be similar to the rapid inhibitory effect of glucocorticoids at the PVN, but is not mediated by endocannabinoid signaling.

  15. Group I Metabotropic Glutamate Receptor Interacting Proteins: Fine-Tuning Receptor Functions in Health and Disease.

    Science.gov (United States)

    Kalinowska, Magdalena; Francesconi, Anna

    2016-01-01

    Group I metabotropic glutamate receptors mediate slow excitatory neurotransmission in the central nervous system and are critical to activity-dependent synaptic plasticity, a cellular substrate of learning and memory. Dysregulated receptor signaling is implicated in neuropsychiatric conditions ranging from neurodevelopmental to neurodegenerative disorders. Importantly, group I metabotropic glutamate receptor signaling functions can be modulated by interacting proteins that mediate receptor trafficking, expression and coupling efficiency to signaling effectors. These interactions afford cell- or pathway-specific modulation to fine-tune receptor function, thus representing a potential target for pharmacological interventions in pathological conditions.

  16. Group I metabotropic glutamate receptors in the medial prefrontal cortex: role in mesocorticolimbic glutamate release in cocaine sensitization.

    Science.gov (United States)

    Timmer, Kristin M; Steketee, Jeffery D

    2013-12-01

    Cocaine sensitization is associated with increased excitability of pyramidal projection neurons in the medial prefrontal cortex. Such hyperexcitability is presumed to increase glutamatergic input to the nucleus accumbens and ventral tegmental area. This study examined the effects of medial prefrontal cortex Group I metabotropic glutamate receptor activation on glutamate levels in the medial prefrontal cortex, nucleus accumbens, and ventral tegmental area in sensitized and control animals. Male Sprague-Dawley rats received four daily injections of cocaine (15 mg/kg, i.p.) or saline (1 mL/kg i.p.). One, 7, or 21 days from the fourth injection, dual-probe microdialysis experiments were performed wherein Group I metabotropic glutamate receptor agonist DHPG was infused into the medial prefrontal cortex and glutamate levels in this region as well as the nucleus accumbens or ventral tegmental area were examined. Intra-mPFC DHPG infusion increased glutamate levels in the medial prefrontal cortex at 1 and 7 days withdrawal, and in the nucleus accumbens at 21 days withdrawal in sensitized rats. These results suggest Group I metabotropic glutamate receptor activation may contribute to the increased excitability of medial prefrontal cortex pyramidal neurons in sensitized animals.

  17. Metabotropic glutamate receptors are required for the induction of long-term potentiation

    Science.gov (United States)

    Zheng, F.; Gallagher, J. P.

    1992-01-01

    Recent observations have led to the suggestion that the metabotropic glutamate receptor may play a role in the induction or maintenance of long-term potentiation (LTP). However, experimental evidence supporting a role for this receptor in the induction of LTP is still inconclusive and controversial. Here we report that, in rat dorsolateral septal nucleus (DLSN) neurons, which have the highest density of metabotropic receptors and show functional responses, the induction of LTP is not blocked by the NMDA receptor antagonist 2-amino-5-phosphonovalerate, but is blocked by two putative metabotropic glutamate receptor antagonists, L-2-amino-3-phosphonopropionic acid and L-2-amino-4-phosphonobutyrate. Furthermore, superfusion of (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid, a selective metabotropic glutamate agonist, resulted in a long-lasting potentiation of synaptic transmission similar to that induced by tetanic stimuli. Our results demonstrated that activation of postsynaptic metabotropic receptors is both necessary and sufficient for the induction of LTP in the DLSN, and we suggest that such a mechanism may be important at other CNS synapses.

  18. Activation of astroglial group Ⅱ and Ⅲ metabotropic glutamate receptors protects midbrain neurons against LPS or MPP+ -induced neurotoxicity

    Institute of Scientific and Technical Information of China (English)

    Hong-HongYao; FangWang; FangZhou; Li-FangHu; TaoSun; Jian-HuaDing; GangHu

    2004-01-01

    AIM: Activation of glial metabotropic glutamate receptors (mGluRs) may be proved to play a critical role for neuroprotection in neurodegenerative diseases. Excess glutamate induced-excitoxicity is implicated in the initiation or progression of the neurodegenerative process. Glutamate accumulation in the central nervous system mediated by inhibiting glutamate

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

    DEFF Research Database (Denmark)

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

    1998-01-01

    We have studied the effects of the enantiomers of 2-amino-3-(3-hydroxyisoxazol-5-yl)propionic acid (homoibotenic acid, HIBO) and analogues substituted with a methyl, bromo or butyl group in the four position of the ring at cloned metabotropic glutamate (mGlu) receptors expressed in Chinese hamste...

  20. Metabotropic glutamate receptors in the thalamocortical network: strategic targets for the treatment of absence epilepsy

    NARCIS (Netherlands)

    Ngomba, R.T.; Santolini, I.; Salt, T.E.; Ferraguti, F.; Battaglia, G.; Luijtelaar, E.L.J.M. van

    2011-01-01

    Metabotropic glutamate (mGlu) receptors are positioned at synapses of the thalamocortical network that underlie the development of spike-and-wave discharges (SWDs) associated with absence epilepsy. The modulatory role of individual mGlu receptor subtypes on excitatory and inhibitory synaptic

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    modulators. In this analysis, we make the first comprehensive structural comparison of all metabotropic glutamate receptors, placing selective negative allosteric modulators and critical mutants into the detailed context of the receptor binding sites. A better understanding of how the different m...

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  3. The Role of Metabotropic Glutamate Receptors and Cortical Adaptation in Habituation of Odor-Guided Behavior

    Science.gov (United States)

    Yadon, Carly A.; Wilson, Donald A.

    2005-01-01

    Decreases in behavioral investigation of novel stimuli over time may be mediated by a variety of factors including changes in attention, internal state, and motivation. Sensory cortical adaptation, a decrease in sensory cortical responsiveness over prolonged stimulation, may also play a role. In olfaction, metabotropic glutamate receptors on…

  4. Metabotropic glutamate receptors in the thalamocortical network: strategic targets for the treatment of absence epilepsy

    NARCIS (Netherlands)

    Ngomba, R.T.; Santolini, I.; Salt, T.E.; Ferraguti, F.; Battaglia, G.; Luijtelaar, E.L.J.M. van

    2011-01-01

    Metabotropic glutamate (mGlu) receptors are positioned at synapses of the thalamocortical network that underlie the development of spike-and-wave discharges (SWDs) associated with absence epilepsy. The modulatory role of individual mGlu receptor subtypes on excitatory and inhibitory synaptic transmi

  5. LIGAND-BINDING PROFILE OF THE RAT METABOTROPIC GLUTAMATE-RECEPTOR MGLUR3 EXPRESSED IN A TRANSFECTED CELL-LINE

    NARCIS (Netherlands)

    LAURIE, DJ; DANZEISEN, M; BODDEKE, HWGM; SOMMER, B

    1995-01-01

    A cDNA clone encoding the rat metabotropic glutamate receptor mGluR3 was stably transfected into human embryonic kidney 293 cells. Receptor-expressing cell lines were characterized by centrifugation binding assays using [H-3]glutamate as radioligand. The rank order of affinity was L-glutamate>(1S,3R

  6. Metabotropic and ionotropic glutamate receptors as potential targets for the treatment of alcohol use disorder.

    Science.gov (United States)

    Goodwani, Sunil; Saternos, Hannah; Alasmari, Fawaz; Sari, Youssef

    2017-02-24

    Emerging evidence indicates that dysfunctional glutamate neurotransmission is critical in the initiation and development of alcohol and drug dependence. Alcohol consumption induced downregulation of glutamate transporter 1 (GLT-1) as reported in previous studies from our laboratory. Glutamate is the major excitatory neurotransmitter in the brain, which acts via interactions with several glutamate receptors. Alcohol consumption interferes with the glutamatergic signal transmission by altering the functions of these receptors. Among the glutamate receptors involved in alcohol-drinking behavior are the metabotropic receptors such as mGluR1/5, mGluR2/3, and mGluR7, as well as the ionotropic receptors, NMDA and AMPA. Preclinical studies using agonists and antagonists implicate these glutamatergic receptors in the development of alcohol use disorder (AUD). Therefore, the purpose of this review is to discuss the neurocircuitry involving glutamate transmission in animals exposed to alcohol and further outline the role of metabotropic and ionotropic receptors in the regulation of alcohol-drinking behavior. This review provides ample information about the potential therapeutic role of glutamatergic receptors for the treatment of AUD.

  7. Driving Cellular Plasticity and Survival Through the Signal Transduction Pathways of Metabotropic Glutamate Receptors

    OpenAIRE

    2005-01-01

    Metabotropic glutamate receptors (mGluRs) share a common molecular morphology with other G protein–linked receptors, but there expression throughout the mammalian nervous system places these receptors as essential mediators not only for the initial development of an organism, but also for the vital determination of a cell’s fate during many disorders in the nervous system that include amyotrophic lateral sclerosis, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, Multiple Scler...

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

    OpenAIRE

    Enz, Ralf

    2012-01-01

    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 o...

  9. The Metabotropic Glutamate 5 Receptor Modulates Extinction and Reinstatement of Methamphetamine-Seeking in Mice

    OpenAIRE

    Rose Chesworth; Brown, Robyn M.; Jee Hyun Kim; Lawrence, Andrew J.

    2013-01-01

    Methamphetamine (METH) is a highly addictive psychostimulant with no therapeutics registered to assist addicts in discontinuing use. Glutamatergic dysfunction has been implicated in the development and maintenance of addiction. We sought to assess the involvement of the metabotropic glutamate 5 receptor (mGlu5) in behaviours relevant to METH addiction because this receptor has been implicated in the actions of other drugs of abuse, including alcohol, cocaine and opiates. mGlu5 knockout (KO) m...

  10. Inhibition of a slow synaptic response by a metabotropic glutamate receptor antagonist in hippocampal CA3 pyramidal cells.

    Science.gov (United States)

    Gerber, U; Lüthi, A; Gähwiler, B H

    1993-11-22

    The effects of a novel antagonist of metabotropic glutamate receptors were investigated in CA3 pyramidal cells in hippocampal slice cultures of the rat. Earlier experiments showed that selective activation of metabotropic glutamate receptors with low concentrations of an agonist, 1S, 3R-1-amino-cyclopentane-1,3-dicarboxylic acid (ACPD), induced an inward current associated with a decrease in membrane conductance and inhibition of the slow calcium-dependent potassium current. These responses were strongly and reversibly reduced by the antagonist, (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG, 0.5-1 mM). In the presence of antagonists of ionotropic glutamate receptors, stimulation of the afferent mossy fibres evoked postsynaptic responses in CA3 pyramidal cells which paralleled those observed with exogenously applied metabotropic glutamate receptor agonists, i.e. a slow inward current and a reduction of calcium-dependent potassium current. Both responses were greatly reduced by bath-applied MCPG (1 mM). These results show that MCPG acts as an effective antagonist at metabotropic glutamate receptors coupled to potassium conductances in the hippocampus. Furthermore, they confirm that glutamate release from presynaptic terminals can modulate postsynaptic properties by activation of metabotropic glutamate receptors.

  11. Mechanisms Associated with Activation of Intracellular Metabotropic Glutamate Receptor, mGluR5.

    Science.gov (United States)

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

    2017-01-01

    The group 1 metabotropic glutamate receptor, mGluR5, is found on the cell surface as well as on intracellular membranes where it can mediate both overlapping and unique signaling effects. Previously we have shown that glutamate activates intracellular mGluR5 by entry through sodium-dependent transporters and/or cystine glutamate exchangers. Calibrated antibody labelling suggests that the glutamate concentration within neurons is quite high (~10 mM) raising the question as to whether intracellular mGluR5 is maximally activated at all times or whether a different ligand might be responsible for receptor activation. To address this issue, we used cellular, optical and molecular techniques to show that intracellular glutamate is largely sequestered in mitochondria; that the glutamate concentration necessary to activate intracellular mGluR5 is about ten-fold higher than what is necessary to activate cell surface mGluR5; and uncaging caged glutamate within neurons can directly activate the receptor. Thus these studies further the concept that glutamate itself serves as the ligand for intracellular mGluR5.

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

    Science.gov (United States)

    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…

  13. Excitatory amino acids acting on metabotropic glutamate receptors broaden the action potential in hippocampal neurons.

    Science.gov (United States)

    Hu, G Y; Storm, J F

    1991-12-24

    Activation of metabotropic glutamate receptors (mGluRs, QP or ACPD receptors) has recently been shown to cause depolarization, blockade of the slow after-hyperpolarization and depression of calcium currents in hippocampal pyramidal cells. Here, we report evidence for a new mGluR-mediated effect: slowing of the spike repolarization in CA1 cells in rat hippocampal slices. During blockade of the ionotropic glutamate receptors, the mGluR agonists trans-1-amino-cyclopentyl-1,3-dicarboxylate (t-ACPD), quisqualate or L-glutamate caused spike broadening. In contrast, the ionotropic receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) was ineffective. The spike broadening may act in concert with the other mGluR effects, e.g. by further increasing the influx of Ca2+ ions which, in turn, may contribute to synaptic modulation.

  14. 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...

  15. PCP and MK-801 Induced Behaviors Reduced by NAAG Peptidase Inhibition via Metabotropic Glutamate Receptors

    Science.gov (United States)

    Olszewski, Rafal T.; Wegorzewska, Marta M.; Monteiro, Ana C.; Krolikowski, Kristyn A.; Zhou, Jia; Kozikowski, Alan P.; Long, Katrice; Mastropaolo, John; Deutsch, Stephen I.; Neale, Joseph H.

    2007-01-01

    Background NMDA receptor open channel blockers phencyclidine (PCP) and dizocilpine (MK-801) elicit schizophrenia-like symptoms in humans and in animal models. Group II metabotropic glutamate receptor agonists reverse the behavioral effects of PCP and MK-801 in animal models. N-Acetylaspartylglutamate (NAAG), third most prevalent neurotransmitter in the mammalian nervous system, is a selective group II metabotropic glutamate receptor agonist. We previously reported that ZJ43, a potent inhibitor of the enzymes that inactivate synaptically released NAAG, reduced motor and stereotypic effects of PCP in the rat. Methods To confirm the efficacy of NAAG peptidase inhibition in decreasing motor behaviors induced by PCP and MK-801, ZJ43 was tested in additional schizophrenia models. Results ZJ43 reduced MK-801-induced motor activation in a mouse model that has been used to characterize the efficacy of a wide range of pharmacotherapies for this human disorder. In a second mouse strain, the peptidase inhibitor reduced PCP-induced stereotypic movements. ZJ43 also reduced PCP-induced negative symptoms in a resident-intruder assay. The group II metabotropic glutamate receptor antagonist, LY341495, blocked the effect of NAAG peptidase inhibition in these mouse models of positive and negative PCP- and MK-801-induced behaviors. Additionally, LY341495 alone increased some PCP-induced behaviors suggesting that normal levels of NAAG act to moderate the effect of PCP via a group II mGluR. Conclusion These data support the proposal that NAAG peptidase inhibition and elevation of synaptic NAAG levels represent a new therapeutic approach to treating the positive and negative symptoms of schizophrenia that are modeled by open channel NMDA receptor antagonists. PMID:17597589

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

    DEFF Research Database (Denmark)

    Baskys, Andrius; Bayazitov, Ildar; Fang, Liwei

    2005-01-01

    Group I metabotropic glutamate receptor (mGluR) agonist DHPG reduced nerve cell death caused by their exposure to NMDA ("neuroprotective effect") and attenuated NMDA receptor-mediated currents [Blaabjerg, M., Baskys, A., Zimmer, J., Vawter, M. P., 2003b. Changes in hippocampal gene expression aft......GluRs reduces nerve cell susceptibility to excitotoxic injury in a PLC-dependent manner; (2) this reduction is associated with a PLC-dependent depression of excitatory synaptic transmission; and (3) mGluR1 activation may facilitate neurogenesis....

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ying-Yu Huang

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

  19. 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...

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

    NARCIS (Netherlands)

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

    2005-01-01

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

  1. 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...

  2. Metabotropic glutamate receptor expression in olfactory receptor neurons from the channel catfish, Ictalurus punctatus.

    Science.gov (United States)

    Medler, K F; Tran, H N; Parker, J M; Caprio, J; Bruch, R C

    1998-04-01

    Metabotropic glutamate receptors (mGluRs) were identified in olfactory receptor neurons of the channel catfish, Ictalurus punctatus, by polymerase chain reaction. DNA sequence analysis confirmed the presence of two subtypes, mGluR1 and mGluR3, that were coexpressed with each other and with the putative odorant receptors within single olfactory receptor neurons. Immunocytochemical data showed that both mGluR subtypes were expressed in the apical dendrites and some cilia of olfactory neurons. Pharmacological analysis showed that antagonists to each mGluR subtype significantly decreased the electrophysiological response to odorant amino acids. alpha-Methyl-L-CCG1/(2S,3S,4S)-2-methyl-2-(carboxycyclopropyl++ +)glycine (MCCG), a known antagonist to mGluR3, and (S)-4-carboxyphenylglycine (S-4CPG), a specific antagonist to mGluR1, each significantly reduced olfactory receptor responses to L-glutamate. S-4CPG and MCCG reduced the glutamate response to 54% and 56% of control, respectively, which was significantly greater than their effect on a neutral amino acid odorant, methionine. These significant reductions of odorant response by the antagonists, taken with the expression of these receptors throughout the dendritic and ciliated portions of some olfactory receptor neurons, suggest that these mGluRs may be involved in olfactory reception and signal transduction.

  3. Illuminating Phenylazopyridines To Photoswitch Metabotropic Glutamate Receptors: From the Flask to the Animals.

    Science.gov (United States)

    Gómez-Santacana, Xavier; Pittolo, Silvia; Rovira, Xavier; Lopez, Marc; Zussy, Charleine; Dalton, James A R; Faucherre, Adèle; Jopling, Chris; Pin, Jean-Philippe; Ciruela, Francisco; Goudet, Cyril; Giraldo, Jesús; Gorostiza, Pau; Llebaria, Amadeu

    2017-01-25

    Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice. The combination of light and some specific phenylazopyridine ligands displays atypical pharmacological profiles, including light-dependent receptor overactivation, which can be observed both in vitro and in vivo. Remarkably, the localized administration of light and a photoswitchable compound in the peripheral tissues of rodents or in the brain amygdalae results in an illumination-dependent analgesic effect. The results reveal a robust translation of the phenylazopyridine photoisomerization to a precise photoregulation of biological activity.

  4. Metabotropic glutamate receptor agonists potentiate a slow afterdepolarization in CNS neurons

    Science.gov (United States)

    Zheng, F.; Gallagher, J. P.

    1992-01-01

    We have previously reported that, in the rat dorsolateral septal nucleus (DLSN), metabotropic glutamate receptor (met-GluR) agonists evoked a slow depolarization accompanied by an increase in membrane conductance and burst firing. We have speculated that the burst firing elicited by met-GluR agonists may be due to activation or enhancement of a non-specific cation current, which exists in some DLSN neurons. Now we report that a slow afterdepolarization (sADP) mediated by a non-specific cation current was potentiated by both 1S,3R-ACPD and quisqualate. In addition, met-GluR agonists unmask a sADP in DLSN neurons which did not show a sADP under control conditions. Our data suggest that a non-specific cation current can be potentiated by activation of the met-GluR.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-15

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

  6. Metabotropic glutamate receptor-1 as a novel target for the antiangiogenic treatment of breast cancer.

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    Cecilia L Speyer

    Full Text Available Metabotropic glutamate receptors (mGluRs are normally expressed in the central nervous system, where they mediate neuronal excitability and neurotransmitter release. Certain cancers, including melanoma and gliomas, express various mGluR subtypes that have been implicated as playing a role in disease progression. Recently, we detected metabotropic glutamate receptor-1 (gene: GRM1; protein: mGluR1 in breast cancer and found that it plays a role in the regulation of cell proliferation and tumor growth. In addition to cancer cells, brain endothelial cells express mGluR1. In light of these studies, and because angiogenesis is both a prognostic indicator in cancer correlating with a poorer prognosis and a potential therapeutic target, we explored a potential role for mGluR1 in mediating endothelial cell (EC proliferation and tumor-induced angiogenesis. GRM1 and mGluR1 were detected in various types of human ECs and, using mGluR1-specific inhibitors or shRNA silencing, we demonstrated that EC growth and Matrigel tube formation are dependent on mGluR1 signaling. In addition, loss of mGluR1 activity leads to reduced angiogenesis in a murine Matrigel sponge implant model as well as a murine tumor model. These results suggest a role for mGluR1 in breast cancer as a pro-angiogenic factor as well as a mediator of tumor progression. They also suggest mGluR1 as a potential new molecular target for the anti-angiogenic therapy of breast cancer.

  7. Regulated release of BDNF by cortical oligodendrocytes is mediated through metabotropic glutamate receptors and the PLC pathway

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    Issa P Bagayogo

    2009-04-01

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

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

    Science.gov (United States)

    Owen, Dafydd R

    2011-08-17

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

  9. Enhancement of CA3 hippocampal network activity by activation of group II metabotropic glutamate receptors.

    Science.gov (United States)

    Ster, Jeanne; Mateos, José María; Grewe, Benjamin Friedrich; Coiret, Guyllaume; Corti, Corrado; Corsi, Mauro; Helmchen, Fritjof; Gerber, Urs

    2011-06-14

    Impaired function or expression of group II metabotropic glutamate receptors (mGluRIIs) is observed in brain disorders such as schizophrenia. This class of receptor is thought to modulate activity of neuronal circuits primarily by inhibiting neurotransmitter release. Here, we characterize a postsynaptic excitatory response mediated by somato-dendritic mGluRIIs in hippocampal CA3 pyramidal cells and in stratum oriens interneurons. The specific mGluRII agonists DCG-IV or LCCG-1 induced an inward current blocked by the mGluRII antagonist LY341495. Experiments with transgenic mice revealed a significant reduction of the inward current in mGluR3(-/-) but not in mGluR2(-/-) mice. The excitatory response was associated with periods of synchronized activity at theta frequency. Furthermore, cholinergically induced network oscillations exhibited decreased frequency when mGluRIIs were blocked. Thus, our data indicate that hippocampal responses are modulated not only by presynaptic mGluRIIs that reduce glutamate release but also by postsynaptic mGluRIIs that depolarize neurons and enhance CA3 network activity.

  10. Homodimerization enhances both sensitivity and dynamic range of the ligand-binding domain of type 1 metabotropic glutamate receptor.

    Science.gov (United States)

    Serebryany, Eugene; Folta-Stogniew, Ewa; Liu, Jian; Yan, Elsa C Y

    2016-12-01

    Cooperativity in ligand binding is a key emergent property of protein oligomers. Positive cooperativity (higher affinity for subsequent binding events than for initial binding) is frequent. However, the symmetrically homodimeric ligand-binding domain (LBD) of metabotropic glutamate receptor type 1 exhibits negative cooperativity. To investigate its origin and functional significance, we measured the response to glutamate in vitro of wild-type and C140S LBD as a function of the extent of dimerization. Our results indicate that homodimerization enhances the affinity of the first, but not the second, binding site, relative to the monomer, giving the dimeric receptor both greater sensitivity and a broader dynamic range.

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

    Science.gov (United States)

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

    2012-08-01

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

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

    Science.gov (United States)

    Enz, Ralf

    2012-01-01

    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.

  13. Pharmacological and molecular characterization of the positive allosteric modulators of metabotropic glutamate receptor 2.

    Science.gov (United States)

    Lundström, L; Bissantz, C; Beck, J; Dellenbach, M; Woltering, T J; Wichmann, J; Gatti, S

    2017-02-16

    The metabotropic glutamate receptor 2 (mGlu2) plays an important role in the presynaptic control of glutamate release and several mGlu2 positive allosteric modulators (PAMs) have been under assessment for their potential as antipsychotics. The binding mode of mGlu2 PAMs is better characterized in functional terms while few data are available on the relationship between allosteric and orthosteric binding sites. Pharmacological studies characterizing binding and effects of two different chemical series of mGlu2 PAMs are therefore carried out here using the radiolabeled mGlu2 agonist (3)[H]-LY354740 and mGlu2 PAM (3)[H]-2,2,2-TEMPS. A multidimensional approach to the PAM mechanism of action shows that mGlu2 PAMs increase the affinity of (3)[H]-LY354740 for the orthosteric site of mGlu2 as well as the number of (3)[H]-LY354740 binding sites. (3)[H]-2,2,2-TEMPS binding is also enhanced by the presence of LY354740. New residues in the allosteric rat mGlu2 binding pocket are identified to be crucial for the PAMs ligand binding, among these Tyr(3.40) and Asn(5.46). Also of remark, in the described experimental conditions S731A (Ser(5.42)) residue is important only for the mGlu2 PAM LY487379 and not for the compound PAM-1: an example of the structural differences among these mGlu2 PAMs. This study provides a summary of the information generated in the past decade on mGlu2 PAMs adding a detailed molecular investigation of PAM binding mode. Differences among mGlu2 PAM compounds are discussed as well as the mGlu2 regions interacting with mGlu2 PAM and NAM agents and residues driving mGlu2 PAM selectivity.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Metabotropic glutamate receptor type 5 in levodopa-induced motor complications.

    Science.gov (United States)

    Ouattara, Bazoumana; Grégoire, Laurent; Morissette, Marc; Gasparini, Fabrizio; Vranesic, Ivo; Bilbe, Graeme; Johns, Donald R; Rajput, Alex; Hornykiewicz, Oleh; Rajput, Ali H; Gomez-Mancilla, Baltazar; Di Paolo, Thérèse

    2011-07-01

    Metabotropic glutamate receptors type 5 (mGluR5) are implicated in regulation of synaptic plasticity and learning, and were the focus of our investigation in human Parkinson's disease (PD) patients with dyskinesias and wearing-off, and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) monkeys with dyskinesias. Using the selective mGluR5 ligand [(3)H]ABP688 autoradiography, we measured mGluR5 in brain slices from 11 normal and 14 PD patients and from MPTP monkeys, in relation to motor complications (dyskinesias and wearing-off) associated with treatment with l-dopa. In 16 monkeys with a bilateral MPTP lesion and four controls, [(3)H]ABP688 specific binding was elevated in the striatum of dyskinetic l-dopa-treated MPTP monkeys but not in MPTP monkeys without dyskinesias compared to controls. PD patients with motor complications (either dyskinesias or wearing-off) had higher [(3)H]ABP688 specific binding compared to those without motor complications and controls in putamen, external and internal globus pallidus. Elevated glutamatergic transmission as measured with increased mGluR5 specific binding was associated with motor complications and its antagonism could be targeted for their treatment.

  16. Place field stability requires the metabotropic glutamate receptor, mGlu5

    Science.gov (United States)

    Zhang, Sijie; Manahan-Vaughan, Denise

    2014-01-01

    The metabotropic glutamate (mGlu) receptors are critically involved in enabling the persistency of forms of synaptic plasticity that are believed to underlie hippocampus-dependent memory. These receptors and in particular, mGlu5, are also required for hippocampus-dependent learning and memory. In the hippocampus, synaptic plasticity is one of the mechanisms by which spatial information may be represented. Another mechanism involves increased firing of place cells. Place cells increase their firing activity when an animal is in a specific spatial location. Inhibition of factors that are essential for synaptic plasticity, such as N-methyl-d-aspartate receptors or protein synthesis, also impair place cell activity. This raises the question as to whether mGlu receptors, that are so important for synaptic plasticity and spatial memory, are also important for place cell encoding. We examined location-dependent place cell firing i.e. place fields. We observed that antagonism of mGlu5, using 2-methyl-6-(phenylethynyl) pyridine (MPEP) had no effect on place field profiles in a familiar environment. However, in a novel environment mGlu5-antagonism affected long-term place field stability, reduced place cell firing and spatial information. These data strongly suggest a role for mGlu5 in the mechanisms underlying informational content and long-term stability of place fields, and add to evidence supporting the importance of these receptors for hippocampal function. PMID:24910241

  17. Blockade of metabotropic glutamate receptor 5 activation inhibits mechanical hypersensitivity following abdominal surgery.

    Science.gov (United States)

    Dolan, Sharron; Nolan, Andrea Mary

    2007-08-01

    This study used the metabotropic glutamate 5 (mGlu5) receptor subtype-selective antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) to characterise the contribution of mGlu5 receptor activity to pain and hypersensitivity in an animal model of post-surgical pain. Adult female Wistar rats (200-250g) were anaesthetised with isoflurane (2%) and underwent a midline laparotomy with gentle manipulation of the viscera, and the effects of pre- (30min) or post- (5h) operative treatment with MPEP (1, 3 or 10mgkg(-1); i.p.) or drug-vehicle on hindpaw withdrawal latency (in seconds) to thermal stimulation (Hargreave's Test) and response threshold (in grams) to mechanical stimulation (using a dynamic plantar aesthesiometer) were measured. Animals that underwent surgery displayed significant hypersensitivity to mechanical stimulation of the hindpaws. Hypersensitivity was maximum at 6h post-surgery (44.5+/-2.4% decrease; p<0.01 vs. anaesthesia only controls) and persisted for 48h. Surgery had no effect on thermal withdrawal latency. Both pre-operative and post-operative administration of 10mgkg(-1)MPEP blocked mechanical hypersensitivity induced by surgery (p<0.01 vs. vehicle treatment). MPEP had no effect on acute nociceptive thresholds in naïve animals. These data suggest that activity at mGlu5 receptors contributes to development of pain and hypersensitivity following surgery.

  18. Reduction of group II metabotropic glutamate receptors during development of benzodiazepine dependence.

    Science.gov (United States)

    Okamoto, Ritsuko; Itoh, Yoshinori; Murata, Yusuke; Kobayashi, Daisuke; Hosoi, Masako; Mine, Kazunori

    2013-01-01

    Prolonged use of benzodiazepines often leads to dependence and withdrawal syndrome. However, the cellular mechanisms underlying benzodiazepine dependence have not been fully clarified. Several investigators have shown an involvement of metabotropic glutamate receptors (mGluRs) in the pathophysiology of dependence or withdrawal. This study was performed to elucidate the role of mGluRs in benzodiazepine dependence. Withdrawal signs were precipitated in mice by flumazenil injection (25 mg/kg) after continuous subcutaneous infusion of benzodiazepines for 7 days, and the effects of several Gi-coupled receptor ligands on forskolin-stimulated cyclic AMP accumulation were examined in the cerebral cortex of mice. The mRNA expression for mGluRs was determined by RT-PCR. A single injection of flumazenil precipitated typical withdrawal signs such as tail elevation and tremor in mice treated with diazepam or alprazolam, but not quazepam. The inhibitory effect of nonselective mGluR ligands on adenylate cyclase activity was diminished in mice that showed signs of benzodiazepine withdrawal. The mRNA expression levels of mGluR2 and mGluR3 were lowered in the cerebral cortex of mice pretreated with diazepam or alprazolam. Our findings suggest that the reduction in the expression of group II mGluRs subunits may be involved in the development of benzodiazepine dependence.

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

    Directory of Open Access Journals (Sweden)

    Rose Chesworth

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

  20. Protective role for type 4 metabotropic glutamate receptors against ischemic brain damage.

    Science.gov (United States)

    Moyanova, Slavianka G; Mastroiacovo, Federica; Kortenska, Lidia V; Mitreva, Rumiana G; Fardone, Erminia; Santolini, Ines; Sobrado, Mónica; Battaglia, Giuseppe; Bruno, Valeria; Nicoletti, Ferdinando; Ngomba, Richard T

    2011-04-01

    We examined the influence of type 4 metabotropic glutamate (mGlu4) receptors on ischemic brain damage using the permanent middle cerebral artery occlusion (MCAO) model in mice and the endothelin-1 (Et-1) model of transient focal ischemia in rats. Mice lacking mGlu4 receptors showed a 25% to 30% increase in infarct volume after MCAO as compared with wild-type littermates. In normal mice, systemic injection of the selective mGlu4 receptor enhancer, N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-caboxamide (PHCCC; 10  mg/kg, subcutaneous, administered once 30  minutes before MCAO), reduced the extent of ischemic brain damage by 35% to 45%. The drug was inactive in mGlu4 receptor knockout mice. In the Et-1 model, PHCCC administered only once 20  minutes after ischemia reduced the infarct volume to a larger extent in the caudate/putamen than in the cerebral cortex. Ischemic rats treated with PHCCC showed a faster recovery of neuronal function, as shown by electrocorticographic recording and by a battery of specific tests, which assess sensorimotor deficits. These data indicate that activation of mGlu4 receptors limit the development of brain damage after permanent or transient focal ischemia. These findings are promising because selective mGlu4 receptor enhancers are under clinical development for the treatment of Parkinson's disease and other central nervous system disorders.

  1. Metabotropic glutamate receptor 5 (mGluR5 regulates bladder nociception

    Directory of Open Access Journals (Sweden)

    Crock Lara W

    2012-03-01

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

  2. Metabotropic glutamate receptor-mediated long-term depression: molecular mechanisms.

    Science.gov (United States)

    Gladding, Clare M; Fitzjohn, Stephen M; Molnár, Elek

    2009-12-01

    The ability to modify synaptic transmission between neurons is a fundamental process of the nervous system that is involved in development, learning, and disease. Thus, synaptic plasticity is the ability to bidirectionally modify transmission, where long-term potentiation and long-term depression (LTD) represent the best characterized forms of plasticity. In the hippocampus, two main forms of LTD coexist that are mediated by activation of either N-methyl-d-aspartic acid receptors (NMDARs) or metabotropic glutamate receptors (mGluRs). Compared with NMDAR-LTD, mGluR-LTD is less well understood, but recent advances have started to delineate the underlying mechanisms. mGluR-LTD at CA3:CA1 synapses in the hippocampus can be induced either by synaptic stimulation or by bath application of the group I selective agonist (R,S)-3,5-dihydroxyphenylglycine. Multiple signaling mechanisms have been implicated in mGluR-LTD, illustrating the complexity of this form of plasticity. This review provides an overview of recent studies investigating the molecular mechanisms underlying hippocampal mGluR-LTD. It highlights the role of key molecular components and signaling pathways that are involved in the induction and expression of mGluR-LTD and considers how the different signaling pathways may work together to elicit a persistent reduction in synaptic transmission.

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

    Science.gov (United States)

    Chesworth, Rose; Brown, Robyn M; Kim, Jee Hyun; Lawrence, Andrew J

    2013-01-01

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

  4. Metabotropic glutamate subtype 5 receptors modulate fear-conditioning induced enhancement of prepulse inhibition in rats.

    Science.gov (United States)

    Zou, Dan; Huang, Juan; Wu, Xihong; Li, Liang

    2007-02-01

    Non-startling acoustic events presented shortly before an intense startling sound can inhibit the acoustic startle reflex. This phenomenon is called prepulse inhibition (PPI), and is widely used as a model of sensorimotor gating. The present study investigated whether PPI can be modulated by fear conditioning, whose acquisition can be blocked by the specific antagonist of metabotropic glutamate receptors subtype 5 (mGluR5), 2-methyl-6-(phenylethynyl)-pyridine (MPEP). The results show that a gap embedded in otherwise continuous noise sounds, which were delivered by two spatially separated loudspeakers, could inhibit the startle reflex induced by an intense sound that was presented 50 ms after the gap. The inhibitory effect depended on the duration of the gap, and was enhanced by fear conditioning that was introduced by temporally pairing the gap with footshock. Intraperitoneal injection of MPEP (0.5 or 5mg/kg) 30 min before fear conditioning blocked the enhancing effect of fear conditioning on PPI, but did not affect either the baseline startle magnitude or PPI if no fear conditioning was introduced. These results indicate that PPI is enhanced when the prepulse signifies an aversive event after fear conditioning. Also, mGlu5Rs play a role in preserving the fear-conditioning-induced enhancement of PPI.

  5. Phosphorylation of group I metabotropic glutamate receptors in drug addiction and translational research.

    Science.gov (United States)

    Mao, Li-Min; Wang, Qiang

    2016-09-01

    Protein phosphorylation is an important posttranslational modification of group I metabotropic glutamate receptors (mGluR1 and mGluR5 subtypes) which are widely distributed throughout the mammalian brain. Several common protein kinases are involved in this type of modification, including protein kinase A, protein kinase C, and extracellular signal-regulated kinase. Through constitutive and activity-dependent phosphorylation of mGluR1/5 at specific residues, protein kinases regulate trafficking, subcellular/subsynaptic distribution, and function of modified receptors. Increasing evidence demonstrates that mGluR1/5 phosphorylation in the mesolimbic reward circuitry is sensitive to chronic psychostimulant exposure and undergoes adaptive changes in its abundance and activity. These changes contribute to long-term excitatory synaptic plasticity related to the addictive property of drugs of abuse. The rapid progress in uncovering the neurochemical basis of addiction has fostered bench-to-bed translational research by targeting mGluR1/5 for developing effective pharmacotherapies for treating addiction in humans. This review summarizes recent data from the studies analyzing mGluR1/5 phosphorylation. Phosphorylation-dependent mechanisms in stimulant-induced mGluR1/5 and behavioral plasticity are also discussed in association with increasing interest in mGluR1/5 in translational medicine.

  6. Mitochondria and NMDA receptor-dependent toxicity of berberine sensitizes neurons to glutamate and rotenone injury.

    Directory of Open Access Journals (Sweden)

    Kai Kysenius

    Full Text Available The global incidence of metabolic and age-related diseases, including type 2 diabetes and Alzheimer's disease, is on the rise. In addition to traditional pharmacotherapy, drug candidates from complementary and alternative medicine are actively being pursued for further drug development. Berberine, a nutraceutical traditionally used as an antibiotic, has recently been proposed to act as a multi-target protective agent against type 2 diabetes, dyslipidemias, ischemic brain injury and neurodegenerative diseases, such as Parkinson's and Alzheimer's disease. However, the safety profile of berberine remains controversial, as isolated reports suggest risks with acute toxicity, bradycardia and exacerbation of neurodegeneration. We report that low micromolar berberine causes rapid mitochondria-dependent toxicity in primary neurons characterized by mitochondrial swelling, increased oxidative stress, decreased mitochondrial membrane potential and depletion of ATP content. Berberine does not induce caspase-3 activation and the resulting neurotoxicity remains unaffected by pan-caspase inhibitor treatment. Interestingly, inhibition of NMDA receptors by memantine and MK-801 completely blocked berberine-induced neurotoxicity. Additionally, subtoxic nanomolar concentrations of berberine were sufficient to sensitize neurons to glutamate excitotoxicity and rotenone injury. Our study highlights the need for further safety assessment of berberine, especially due to its tendency to accumulate in the CNS and the risk of potential neurotoxicity as a consequence of increasing bioavailability of berberine.

  7. Functional Impact of Allosteric Agonist Activity of Selective Positive Allosteric Modulators of Metabotropic Glutamate Receptor Subtype 5 in Regulating Central Nervous System Function

    OpenAIRE

    Noetzel, Meredith J.; Rook, Jerri M.; Vinson, Paige N.; Cho, Hyekyung P.; Days, Emily; Zhou, Y.; Rodriguez, Alice L.; Lavreysen, Hilde; Stauffer, Shaun R.; Niswender, Colleen M.; Xiang, Zixiu; Daniels, J. Scott; Jones, Carrie K.; Lindsley, Craig W.; Weaver, C. David

    2012-01-01

    Positive allosteric modulators (PAMs) of metabotropic glutamate receptor subtype 5 (mGlu5) have emerged as an exciting new approach for the treatment of schizophrenia and other central nervous system (CNS) disorders. Of interest, some mGlu5 PAMs act as pure PAMs, only potentiating mGlu5 responses to glutamate whereas others [allosteric agonists coupled with PAM activity (ago-PAMs)] potentiate responses to glutamate and have intrinsic allosteric agonist activity in mGlu5-expressing cell lines....

  8. Metabotropic glutamate receptor agonists modify the pyloric output of the crustacean stomatogastric ganglion.

    Science.gov (United States)

    Pérez-Acevedo, Nivia L; Krenz, Wulf D

    2005-11-16

    We have studied the effects of groups I, II, and III metabotropic glutamate receptor (mGluR) agonists and antagonists on pyloric activity in the stomatogastric ganglion (STG) of the Caribbean spiny lobster Panulirus argus. We have found that agonists for all three groups of mGluRs modify the pyloric output. The group I agonist, l-quisqualic acid (l-QA), activated the pyloric central pattern generator (CPG). When the pyloric rhythm was partially suppressed by sucrose-block of input fibers in the stomatogastric nerve (stn), l-QA accelerated the rhythmic activity. In addition, the number of spike discharges was increased in pyloric motoneurons: pyloric (PY), and lateral pyloric (LP). In completely blocked preparations, a slow pyloric rhythm was initiated by l-QA. Groups II and III agonists exerted an inhibitory effect on pyloric activity. The group II agonist, (2S,1'S,2'S)-2-(Carboxycyclopropyl)glycine (L-CCG-I), decreased both the frequency of the pyloric rhythm and the number of spike discharges in the motoneurons: ventricular dilator (VD), PY, and LP. The effects of L-CCG-I were dose-dependent. The group III agonist, l-(+)-2-Amino-4-phosphonobutyric acid (l-AP4), slightly decreased the frequency of the pyloric rhythm and suppressed spike discharges in the VD neuron. All effects of mGluR agonists were reversible. The effect of l-QA was blocked by the broad spectrum mGluR antagonist (S)-Methyl-4-carboxyphenylglycine (MCPG). The inhibitory effect of L-CCG-I was prevented by MCPG and by the group II/III mGluR antagonist (RS)-alpha-Methyl-4-phosphonophenylglycine (MPPG), and was partially blocked by the group II mGluR antagonist (RS)-1-amino-5-phosphonoindan-1-carboxylic acid (APICA). The inhibitory effect of l-AP4 was blocked by MPPG and partially blocked by APICA.

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

    Science.gov (United States)

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

    2017-01-01

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

  10. Amyloid-beta neurotoxicity and clearance are both regulated by glial group II metabotropic glutamate receptors.

    Science.gov (United States)

    Durand, Daniela; Carniglia, Lila; Turati, Juan; Ramírez, Delia; Saba, Julieta; Caruso, Carla; Lasaga, Mercedes

    2017-09-01

    Astrocytes are now fully endorsed as key players in CNS functionality and plasticity. We recently showed that metabotropic glutamate receptor 3 (mGlu3R) activation by LY379268 promotes non-amyloidogenic cleavage of amyloid precursor protein (APP) in cultured astrocytes, leading to increased release of neuroprotective sAPPα. Furthermore, mGlu3R expression is reduced in hippocampal astrocytes from PDAPP-J20 mice, suggesting a role for these receptors in Alzheimer's disease. The present study enquires into the role of astroglial-derived neurotrophins induced by mGlu3R activation in neurotoxicity triggered by amyloid β (Aβ). Conditioned medium from LY379268-treated astrocytes protected hippocampal neurons from Aβ-induced cell death. Immunodepletion of sAPPα from the conditioned medium prevented its protective effect. LY379268 induced brain-derived neurotrophic factor (BDNF) expression in astrocytes, and neutralizing BDNF from conditioned medium also prevented its neuroprotective effect on Aβ neurotoxicity. LY379268 was also able to decrease Aβ-induced neuron death by acting directly on neuronal mGlu3R. On the other hand, LY379268 increased Aβ uptake in astrocytes and microglia. Indeed, and more importantly, a reduction in Aβ-induced neuron death was observed when co-cultured with LY379268-pretreated astrocytes, suggesting a link between neuroprotection and increased glial phagocytic activity. Altogether, these results indicate a double function for glial mGlu3R activation against Aβ neurotoxicity: (i) it increases the release of protective neurotrophins such as sAPPα and BDNF, and (ii) it induces amyloid removal from extracellular space by glia-mediated phagocytosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2015-07-01

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

  12. Phosphorylation of group I metabotropic glutamate receptors in drug addiction and translational research

    Institute of Scientific and Technical Information of China (English)

    Limin Mao; John Q Wang∗

    2016-01-01

    Protein phosphorylation is an impor-tant posttranslational modification of group I metabo-tropic glutamate receptors ( mGluR1 and mGluR5 subtypes, mGluR1/5 ) which are widely distributed throughout the mammalian brain. Several common protein kinases are involved in this type of modifica-tion, including protein kinase A, protein kinase C, and extracellular signal-regulated kinase. Through con-stitutive and activity-dependent phosphorylation of mGluR1/5 at specific residues, protein kinases regu-late trafficking, subcellular/subsynaptic distribution, and function of modified receptors. Increasing evi-dence demonstrates that mGluR1/5 phosphorylation in the mesolimbic reward circuitry is sensitive to chro-nic psychostimulant exposure and undergoes adaptive changes in its abundance and activity. These changes contribute to long-term excitatory synaptic plasticity related to the addictive property of drugs of abuse. The rapid progress in uncovering the neurochemical basis of addiction has fostered bench-to-bed translation-al research by targeting mGluR1/5 for developing ef-fective pharmacotherapies for treating addiction in hu-mans. This review summarizes recent data from the studies analyzing mGluR1/5 phosphorylation. Phos-phorylation-dependent mechanisms in stimulant-in-duced mGluR1/5 and behavioral plasticity are also dis-cussed in association with increasing interest in mGluR1/5 in translational medicine.

  13. Differential expression of group I metabotropic glutamate receptors in functionally distinct hippocampal interneurons.

    Science.gov (United States)

    van Hooft, J A; Giuffrida, R; Blatow, M; Monyer, H

    2000-05-15

    Metabotropic glutamate receptors (mGluRs) have been proposed to be involved in oscillatory rhythmic activity in the hippocampus. However, the subtypes of mGluRs involved and their precise distribution in different populations of interneurons is unclear. In this study, we combined functional analysis of mGluR-mediated inward currents in CA1 oriens-alveus interneurons with anatomical and immunocytochemical identification of these interneurons and expression analysis of group I mGluR using single-cell reverse transcription-PCR (RT-PCR). Four major interneuron subtypes could be distinguished based on the mGluR-mediated inward current induced by the application of 100 microm trans-(1S,3R)-1-aminocyclopentane-1, 3-dicarboxylic acid (ACPD) under voltage-clamp conditions and the action potential firing pattern under current-clamp conditions. Type I interneurons responded with a large inward current of approximately 224 pA, were positive for somatostatin, and the majority expressed both mGluR1 and mGluR5. Type II interneurons responded with an inward current of approximately 80 pA, contained calbindin, and expressed mainly mGluR1. Type III interneurons responded with an inward current of approximately 60 pA. These interneurons were fast-spiking, contained parvalbumin, and expressed mainly mGluR5. Type IV interneurons did not respond with an inward current upon application of ACPD, yet they expressed group I mGluRs. Activation of group I mGluRs under current-clamp conditions increased spike frequency and resulted in rhythmic firing activity in type I and II, but not in type III and IV, interneurons. RT-PCR results suggest that activation of mGluR1 in the subsets of GABAergic interneurons, classified here as type I and II, may play an important role in mediating synchronous activity.

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

    Directory of Open Access Journals (Sweden)

    Malathi Banda

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

  15. Autoradiographic visualization of group III metabotropic glutamate receptors using [3H]-L-2-amino-4-phosphonobutyrate

    OpenAIRE

    Hudtloff, Camilla; Thomsen, Christian

    1998-01-01

    In vitro receptor autoradiography using [3H]-L-2-amino-4-phosphonobutyrate ([3H]-L-AP4) binding to sections of rat brain has been characterized and shown to most likely represent labelling of group III metabotropic glutamate receptors.Specific [3H]-L-AP4 binding to rat brain sections was observed at high densities in the molecular layer of the cerebellar cortex and the outer layer of the superior colliculus. Moderate levels were observed throughout the cerebral cortex, in the molecular layer ...

  16. [3H]-L-2-amino-4-phosphonobutyrate labels a metabotropic glutamate receptor, mGluR4a.

    OpenAIRE

    Eriksen, L; Thomsen, C.

    1995-01-01

    1. The ligand binding site of subtype mGluR4a of the metabotropic glutamate receptor family was characterized by using [3H]-L-2-amino-4-phosphonobutyrate ([3H]-L-AP4) binding. 2. Specific [3H]-L-AP4 binding to membranes prepared from baby hamster kidney (BHK) cells transfected with a vector encoding mGluR4a accounted for 60-70% of the total binding whereas no specific binding of [3H]-L-AP4 was observed to membranes prepared from BHK cells expressing the vector only. 3. Specific binding of [3H...

  17. Altered expression of metabotropic glutamate receptor 1 alpha after acute diffuse brain injury Effect of the competitive antagonist 1-aminoindan-1, 5-dicarboxylic acid

    Institute of Scientific and Technical Information of China (English)

    Fei Cao; Mantao Chen; Gu Li; Ke Ye; Xin Huang; Xiujue Zheng

    2012-01-01

    The diffuse brain injury model was conducted in Sprague-Dawley rats, according to Marmarou's free-fall attack. The water content in brain tissue, expression of metabotropic glutamate receptor 1α mRNA and protein were significantly increased after injury, reached a peak at 24 hours, and then gradually decreased. After treatment with the competitive antagonist of metabotropic glutamate receptor 1α, (RS)-1-aminoindan-1, 5-dicarboxylic acid, the water content of brain tissues decreased between 12-72 hours after injury, and neurological behaviors improved at 2 weeks. These experimental findings suggest that the 1-aminoindan-1, 5-dicarboxylic acid may result in marked neuroprotection against diffuse brain injury.

  18. The role of Arg(78) in the metabotropic glutamate receptor mGlu(1) for agonist binding and selectivity

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Sheppard, P O; O'Hara, P J

    2000-01-01

    likely, through the formation of an ionic bond between its positively charged side chain and the distal acid group of the agonists. Furthermore, the different impact of the two mutations on (S)-glutamic acid and (S)-quisqualic acid potencies strongly indicates that while Arg(78) appears to be a common......The metabotropic glutamate receptors belong to family C of the G-protein coupled receptor superfamily. These receptors all possess large extracellular amino terminal domains, where agonist binding takes place. We have previously constructed a molecular model of the amino terminal domain of the m......Glu(1) receptor based on a weak amino acid sequence similarity with a family of bacterial periplasmic binding proteins (PBPs). The residues Ser(165) and Thr(188) were demonstrated to be involved in agonist binding to the receptor. Here, we report that mutation of Arg(78) in the mGlu(1b) receptor...

  19. Metabotropic glutamate and GABA receptors modulate cellular excitability and glutamatergic transmission in chicken cochlear nucleus angularis neurons.

    Science.gov (United States)

    Shi, Wei; Lu, Yong

    2017-03-01

    Neurons in the avian cochlear nucleus angularis (NA) receive glutamatergic input from the auditory nerve, and GABAergic input from the superior olivary nucleus. Physiologically heterogeneous, NA neurons perform multiple functions including encoding sound intensity information. Using in vitro whole-cell patch recordings from acute brain slices and immunohistochemistry staining, we investigated neuromodulation mediated by metabotropic glutamate and GABA receptors (mGluRs and GABABRs) in NA neurons. Based on their intrinsic firing patterns in response to somatic current injections, NA neurons were classified into onset, damped, and tonic cells. Pharmacological activation of group II mGluRs, group III mGluRs, and GABABRs, by their respective agonists, suppressed the cellular excitability of non-onset firing NA neurons. Each of these agonists inhibited the glutamatergic transmission in NA neurons, in a cell type-independent manner. The frequency but not the amplitude of spontaneous release of glutamate was reduced by each of these agonists, suggesting that the modulation of the glutamatergic transmission was via presynaptic actions. Interestingly, activation of group I mGluRs increased cellular excitability and suppressed glutamatergic transmission in non-onset neurons. These results elaborate that auditory processing in NA neurons is subject to neuromodulation mediated by metabotropic receptors activated by native neurotransmitters released at NA.

  20. Involvement of group III metabotropic glutamate receptors in the modulation of spinal nociceptive signals

    Institute of Scientific and Technical Information of China (English)

    Xiaorong Yang; Yu Zhang; Xin Zhao; Naihong Liu; Jiantian Qiao; Ce Zhang

    2009-01-01

    BACKGROUND:Previous morphological studies have demonstrated that group III metabotropic glutamate receptors (mGluRs) are commonly found in nociceptive pathways,particularly in the terminals of primary afferent fibers in the spinal dorsal horn.OBJECTIVE:To investigate the role of group III mGluRs in a rat model of spinal nociception by intrathecal administration of a selective agonist,L-Serine-O-phosphate (L-SOP).DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment.The study was performed at the Department of Physiology and Neurobiology,Shanxi Medical University,between March 2007 and May 2008.MATERIALS:L-SOP of group III mGluRs (Tocris Cookson Ltd,UK),formalin (Sigma,USA),rabbit anti-c-Fos polyclonal antibody and biotin-labeled goat anti-rabbit IgG (Cell Signaling Technology,USA) were used in this study.METHODS:A total of 26 healthy Wistar rats,aged 1 month and weighing 100-120 g,were subjected to intrathecal catheter implantation.After 5-8 days,10 rats were selected according to experimental requirements.L-SOP 250 nmol in 10 μL,or the equivalent volume of normal saline,was administered by intrathecal injection into the L3-5 region of the spinal cord in the experimental and control groups,respectively.After 15 minutes,formalin (5%,50 μL) was subcutaneously injected into the plantar of the left hindpaw of each rat to establish formalin-induced pain models.MAIN OUTCOME MEASURES:Nociceptive behavioral responses and immunohistochemical examination of Fos expression.RESULTS:Intrathecal injection of L-SOP significantly attenuated the second phase nociceptive response compared with the control group (P<0.05),and Fos expression in the spinal dorsal horn was significantly decreased along with the number of Fos-like immunoreactive neurons (P<0.05).CONCLUSION:Group III mGluRs are involved in the modulation of nociceptive signals,and their activation suppresses the transmission of nociceptive signals.

  1. Developmental distribution pattern of metabotropic glutamate receptor 5 in prenatal human hippocampus

    Institute of Scientific and Technical Information of China (English)

    Pengbo Yang; Yong Liu; Junfeng Zhang; Lingyu Zhao; Qian Jiao; Hui Jin; Xinli Xiao; Haixia Zhang; Ming Hu; Haixia Lu

    2012-01-01

    Objective Metabotropic glutamate receptor 5 (mGluR5) is concentrated in zones of active neurogenesis in the prenatal and postnatal rodent brain and plays an important role in the regulation of neurogenesis.However,little is known about mGluR5 in the prenatal human brain.Here,we aimed to explore the expression pattern and cellular distribution of mGluR5 in human fetal hippocampus.Methods Thirty-four human fetuses were divided into four groups according to gestational age:9-11,14-16,22-24 and 32-36 weeks.The hippocampus was dissected out and prepared.The protein and mRNA expression of mGluR5 were evaluated by Western blot and immunohistochemistry or real-time PCR.The cellular distribution of mGluR5 was observed with double-labeling immunofluorescence.Results Both mGluR5 mRNA and protein were detected in the prenatal human hippocampus by real-time PCR and immunoblotting,and the expression levels increased gradually over time.The immunohistochemistry results were consistent with immunoblotting and showed that mGluR5 immunoreactivity was mainly present in the inner marginal zone (IMZ),hippocampal plate (HP) and ventricular zone (VZ).The double-labeling immunofluorescence showed that mGluR5 was present in neural stem cells (nestin-positive),neuroblasts (DCX-positive) and mature neurons (NeuN-positive),but not in typical astrocytes (GFAP-positive).The cells co-expressing mGluR5 and nestin were mainly located in the IMZ,HP and subplate at 11 weeks,all layers at 16 weeks,and CA1 at 24 weeks.As development proceeded,the number of mGluR5/nestin double-positive cells decreased gradually so that there were only a handful of double-labeled cells at 32 weeks.However,mGluR5/DCX double-positive cells were only found in the HP,IZ and IMZ at 11 weeks.Conclusion The pattem of mGluR5 expression by neural stem/progenitor cells,neuroblasts and neurons provides important anatomical evidence for the role of mGluR5 in the regulation of human hippocampal development.

  2. Protective role for type-1 metabotropic glutamate receptors against spike and wave discharges in the WAG/Rij rat model of absence epilepsy

    NARCIS (Netherlands)

    Ngomba, R.T.; Santolini, I.; Biagioni, F.; Molinaro, G.; Simonyi, A.; Rijn, C.M. van; D'Amore, V.; Mastroiacovo, F.; Olivieri, G.; Gradini, R.; Luijtelaar, E.L.J.M. van; Nicoletti, F.

    2011-01-01

    Eight-month old WAG/Rij rats, which developed spontaneous occurring absence seizures, showed a reduced function of mGlu1 metabotropic glutamate receptors in the thalamus, as assessed by in vivo measurements of DHPG-stimulated polyphosphoinositide hydrolysis, in the presence of the mGlu5 antagonist M

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

    Science.gov (United States)

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

    2009-01-01

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

  4. Activation of group II metabotropic glutamate receptors inhibits glutamatergic transmission in the rat entorhinal cortex via reduction of glutamate release probability.

    Science.gov (United States)

    Wang, Shouping; Chen, Xiaotong; Kurada, Lalitha; Huang, Zitong; Lei, Saobo

    2012-03-01

    Glutamate interacts with ionotropic and metabotropic glutamate receptors (mGluRs). Whereas the entorhinal cortex (EC) is a principal structure involved in learning and memory, the roles of mGluRs in synaptic transmission in the EC have not been completely determined. Here, we show that activation of group II mGluRs (mGluR II) induced robust depression of glutamatergic transmission in the EC. The mGluR II-induced depression was due to a selective reduction of presynaptic release probability without alterations of the quantal size and the number of release sites. The mechanisms underlying mGluR II-mediated suppression of glutamate release included the inhibition of presynaptic release machinery and the depression of presynaptic P/Q-type Ca(2+) channels. Whereas mGluR II-induced depression required the function of Gα(i/o) proteins, protein kinase A (PKA) pathway was only involved in mGluR II-mediated inhibition of release machinery and thereby partially required for mGluR II-induced inhibition of glutamate release. Presynaptic stimulation at 5 Hz for 10 min also induced depression of glutamatergic transmission via activation of presynaptic mGluR II suggesting an endogenous role for mGluR II in modulating glutamatergic transmission.

  5. Association between genetic variants of the metabotropic glutamate receptor 3 (GRM3) and cognitive set shifting in healthy individuals.

    Science.gov (United States)

    Baune, B T; Suslow, T; Beśte, C; Birosova, E; Domschke, K; Sehlmeyer, C; Konrad, C

    2010-07-01

    Set-shifting and maintenance are complex cognitive processes, which are often impaired in schizophrenia. The genetic basis of these processes is poorly understood. We aimed to investigate the association between genetic variants of the metabotropic glutamate receptor 3 (GRM3) and cognitive set-shifting in healthy individuals. The relationship between 14 selected single nucleotide polymorphisms (SNPs) of the GRM3 gene and cognitive set-shifting as measured by perseverative errors using the modified card sorting test (MCST) was analysed in a sample of N = 98 young healthy individuals (mean age in years: 22.7 +/- 0.19). Results show that SNP rs17676277 is related to the performance on the MCST. Subjects with the TT genotype showed significantly less perseverative errors as compared with the AA (P = 0.025) and AT (P = 0.0005) and combined AA/AT genotypes (P = 0.0005). Haplotype analyses suggest the involvement of various SNPs of the GRM3 gene in perseverative error processing in a dominant model of inheritance. The findings strongly suggest that the genetic variation (rs17676277 and three haplotypes) in the metabotropic GRM3 is related to cognitive set-shifting in healthy individuals independent of working memory. However, because of a relatively small sample size for a genetic association study, the present results are tentative and require replication.

  6. Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 5 (mGluR5) attenuate microglial activation.

    Science.gov (United States)

    Xue, Fengtian; Stoica, Bogdan A; Hanscom, Marie; Kabadi, Shruti V; Faden, Alan I

    2014-01-01

    Traumatic brain injury causes progressive neurodegeneration associated with chronic microglial activation. Recent studies show that neurodegeneration and neuroinflammation after traumatic brain injury can be inhibited as late as one month in animals by the activation of the metabotropic glutamate receptor 5 in microglia using (RS)-2-chloro-5- hydroxy-phenylglycine. However, the therapeutic potential of this agonist is limited due to its relatively weak potency and brain permeability. To address such concerns, we evaluated the anti-inflammatory activities of several positive allosteric modulators using various in vitro assays, and found that 3,3'-difluorobenzaldazine, 3-cyano-N-(1,3-diphenyl-1H-pyrazol- 5-yl)benzamide and 4-nitro-N-(1-(2-fluorophenyl)-3-phenyl-1H-pyrazol-5-yl)benzamide showed significantly improved potency which makes them potential lead compounds for further development of positive allosteric modulators for the treatment of traumatic brain injury.

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

    DEFF Research Database (Denmark)

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

    2001-01-01

    and the loops connecting these. The findings offer valuable insight into the mechanism of ATD closure and family C receptor activation. Furthermore, the findings demonstrate that ATD regions other than those participating in agonist binding could be potential targets for new generations of ligands......The metabotropic glutamate receptors (mGluRs) belong to family C of the G-protein-coupled receptor (GPCR) superfamily. The receptors are characterized by having unusually long amino-terminal domains (ATDs), to which agonist binding has been shown to take place. Previously, we have constructed...... of a "closed" conformation, and thus stabilizing a more or less inactive "open" form of the ATD. This study presents the first metal ion site constructed in a family C GPCR. Furthermore, it is the first time a metal ion site has been created in a region outside of the seven transmembrane regions of a GPCR...

  8. Actions of Xanthurenic acid, a putative endogenous Group II metabotropic glutamate receptor agonist, on sensory transmission in the thalamus.

    Science.gov (United States)

    Copeland, C S; Neale, S A; Salt, T E

    2013-03-01

    Xanthurenic acid (XA), a molecule arising from tryptophan metabolism by transamination of 3-hydroxykynurenine, has recently been identified as an endogenous Group II (mGlu2 and mGlu3) metabotropic glutamate (mGlu) receptor ligand in vitro. Impairments in Group II mGlu receptor expression and function have been implicated in the pathophysiology of schizophrenia, as have multiple steps in the kynurenine metabolism pathway. Therefore, we examined XA in vivo to further investigate its potential as a Group II mGlu receptor ligand using a preparation that has been previously demonstrated to efficiently reveal the action of other Group II mGlu receptor ligands in vivo. Extracellular single-neurone recordings were made in the rat ventrobasal thalamus (VB) in conjunction with iontophoresis of agonists, an antagonist and a positive allosteric modulator and/or intravenous (i.v.) injection of XA. We found the XA effect on sensory inhibition, when applied iontophoretically and i.v., was similar to that of other Group II mGlu receptor agonists in reducing inhibition evoked in the VB from the thalamic reticular nucleus upon physiological sensory stimulation. Furthermore, we postulate that XA may be the first potential endogenous allosteric agonist (termed 'endocoid') for the mGlu receptors. As the Group II receptors and kynurenine metabolism pathway have both been heavily implicated in the pathophysiology of schizophrenia, XA could play a pivotal role in antipsychotic research as this potential endocoid represents both a convergence within these two biological parameters and a novel class of Group II mGlu receptor ligand. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.

  9. Changes in mRNA for metabotropic glutamate receptors after transient cerebral ischaemia

    DEFF Research Database (Denmark)

    Rosdahl, D; Seitzberg, D A; Christensen, Thomas;

    1994-01-01

    Using a rat 4-vessel occlusion model of cerebral ischaemia we studied the changes in the mRNA level for the metabotropic receptor subtypes mGluR1 alpha, mGluR1 beta, mGluR2, mGluR3, mGluR4, and mGluR5 by means of in situ hybridization with oligonucleotides. After 24 hours of reperfusion the mRNA ...

  10. Metabotropic glutamate receptor 6 signaling enhances TRPM1 calcium channel function and increases melanin content in human melanocytes.

    Science.gov (United States)

    Devi, Sulochana; Markandeya, Yogananda; Maddodi, Nityanand; Dhingra, Anuradha; Vardi, Noga; Balijepalli, Ravi C; Setaluri, Vijayasaradhi

    2013-05-01

    Mutations in TRPM1, a calcium channel expressed in retinal bipolar cells and epidermal melanocytes, cause complete congenital stationary night blindness with no discernible skin phenotype. In the retina, TRPM1 activity is negatively coupled to metabotropic glutamate receptor 6 (mGluR6) signaling through Gαo and TRPM1 mutations result in the loss of responsiveness of TRPM1 to mGluR6 signaling. Here, we show that human melanocytes express mGluR6, and treatment of melanocytes with L-AP4, a type III mGluR-selective agonist, enhances Ca(2+) uptake. Knockdown of TRPM1 or mGluR6 by shRNA abolished L-AP4-induced Ca(2+) influx and TRPM1 currents, showing that TRPM1 activity in melanocytes is positively coupled to mGluR6 signaling. Gαo protein is absent in melanocytes. However, forced expression of Gαo restored negative coupling of TRPM1 to mGluR6 signaling, but treatment with pertussis toxin, an inhibitor of Gi /Go proteins, did not affect basal or mGluR6-induced Ca(2+) uptake. Additionally, chronic stimulation of mGluR6 altered melanocyte morphology and increased melanin content. These data suggest differences in coupling of TRPM1 function to mGluR6 signaling explain different cellular responses to glutamate in the retina and the skin.

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

    Directory of Open Access Journals (Sweden)

    Xia Yan

    2012-08-01

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

  12. Xanthurenic Acid Activates mGlu2/3 Metabotropic Glutamate Receptors and is a Potential Trait Marker for Schizophrenia.

    Science.gov (United States)

    Fazio, Francesco; Lionetto, Luana; Curto, Martina; Iacovelli, Luisa; Cavallari, Michele; Zappulla, Cristina; Ulivieri, Martina; Napoletano, Flavia; Capi, Matilde; Corigliano, Valentina; Scaccianoce, Sergio; Caruso, Alessandra; Miele, Jessica; De Fusco, Antonio; Di Menna, Luisa; Comparelli, Anna; De Carolis, Antonella; Gradini, Roberto; Nisticò, Robert; De Blasi, Antonio; Girardi, Paolo; Bruno, Valeria; Battaglia, Giuseppe; Nicoletti, Ferdinando; Simmaco, Maurizio

    2015-12-08

    The kynurenine pathway of tryptophan metabolism has been implicated in the pathophysiology of psychiatric disorders, including schizophrenia. We report here that the kynurenine metabolite, xanturenic acid (XA), interacts with, and activates mGlu2 and mGlu3 metabotropic glutamate receptors in heterologous expression systems. However, the molecular nature of this interaction is unknown, and our data cannot exclude that XA acts primarily on other targets, such as the vesicular glutamate transporter, in the CNS. Systemic administration of XA in mice produced antipsychotic-like effects in the MK-801-induced model of hyperactivity. This effect required the presence of mGlu2 receptors and was abrogated by the preferential mGlu2/3 receptor antagonist, LY341495. Because the mGlu2 receptor is a potential drug target in the treatment of schizophrenia, we decided to measure serum levels of XA and other kynurenine metabolites in patients affected by schizophrenia. Serum XA levels were largely reduced in a large cohort of patients affected by schizophrenia, and, in patients with first-episode schizophrenia, levels remained low after 12 months of antipsychotic medication. As opposed to other kynurenine metabolites, XA levels were also significantly reduced in first-degree relatives of patients affected by schizophrenia. We suggest that lowered serum XA levels might represent a novel trait marker for schizophrenia.

  13. Persistent current oscillations produced by activation of metabotropic glutamate receptors in immature rat CA3 hippocampal neurons.

    Science.gov (United States)

    Aniksztejn, L; Sciancalepore, M; Ben Ari, Y; Cherubini, E

    1995-04-01

    1. The single-electrode voltage-clamp technique was used to study the effects of the metabotropic glutamate receptors (mGluRs) agonist 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD, ACPD, 3-10 microM) on CA3 hippocampal neurons during the 1st 10 days of postnatal (P) life and in adulthood. 2. Repeated applications of 1S,3R-ACPD, in the presence of tetrodotoxin (TTX, 1 microM), tetraethylammonium chloride (TEACl 10 mM), and CsCl (2 mM), induced in immature but not in adult neurons periodic inward currents (PICs) that persisted for several hours after the last application of the agonist. 3. PICs, which were generated by nonspecific cationic currents, reversed polarity at 2.8 +/- 3 (SD) mV. They were reversibly blocked by kynurenic acid (1 mM), suggesting that they were mediated by glutamate acting on ionotropic receptors. They were also abolished in a nominally Ca(2+)-free medium. 4. PICs were irreversibly abolished by thapsigargin (10 microM) but were unaffected by ryanodine (10-40 microM). Caffeine (2 mM) also reversibly blocked PICs; this effect was independent from adenosine 3',5'-cyclic monophosphate (cAMP) accumulation, inhibition of voltage-dependent Ca2+ current, or blockade of adenosine receptors. 5. We suggest that, in neonatal slices, mGluRs-induced PICs are triggered by elevation of [Ca2+]i, after mobilization of Ca2+ from inositol 1,4,5-trisphosphate (InsP3)-sensitive stores. This will lead to a persistent, pulsatile release of glutamate from presynaptic nerve terminals, a phenomenon that is probably maintained via a calcium-induced-calcium release process.

  14. Rab8 modulates metabotropic glutamate receptor subtype 1 intracellular trafficking and signaling in a protein kinase C-dependent manner.

    Science.gov (United States)

    Esseltine, Jessica L; Ribeiro, Fabiola M; Ferguson, Stephen S G

    2012-11-21

    Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors (GPCRs) that are activated by glutamate, the primary excitatory neurotransmitter in the CNS. Alterations in glutamate receptor signaling are implicated in neuropathologies such as Alzheimer's disease, ischemia, and Huntington's disease among others. Group 1 mGluRs (mGluR1 and mGluR5) are primarily coupled to Gα(q/11) leading to the activation of phospholipase C and the formation of diacylglycerol and inositol 1,4,5-trisphosphate, which results in the release of intracellular calcium stores and protein kinase C (PKC) activation. Desensitization, endocytosis, and recycling are major mechanisms of GPCR regulation, and the intracellular trafficking of GPCRs is linked to the Rab family of small G proteins. Rab8 is a small GTPase that is specifically involved in the regulation of secretory/recycling vesicles, modulation of the actin cytoskeleton, and cell polarity. Rab8 has been shown to regulate the synaptic delivery of AMPA receptors during long-term potentiation and during constitutive receptor recycling. We show here that Rab8 interacts with the C-terminal tail of mGluR1a in an agonist-dependent manner and plays a role in regulating of mGluR1a signaling and intracellular trafficking in human embryonic kidney 293 cells. Specifically, Rab8 expression attenuates mGluR1a-mediated inositol phosphate formation and calcium release from mouse neurons in a PKC-dependent manner, while increasing cell surface mGluR1a expression via decreased receptor endocytosis. These experiments provide us with an understanding of the role Rabs play in coordinated regulation of mGluR1a and how this impacts mGluR1a signaling.

  15. Reduction of glutamatergic neurotransmission by prolonged exposure to dieldrin involves NMDA receptor internalization and metabotropic glutamate receptor 5 downregulation.

    Science.gov (United States)

    Briz, Victor; Galofré, Mireia; Suñol, Cristina

    2010-01-01

    Dieldrin was previously used as a pesticide. Although its use has been discontinued, humans are still exposed to it due to its high environmental persistence and because it accumulates in the adipose tissue of animals. Acute exposure to dieldrin provokes convulsions due to its antagonism on the gamma-aminobutyric acid-A (GABA(A)) receptor. However, little is known about the effects of low chronic exposure to this pollutant. In the present work, we use primary cultures of cortical neurons to study the mechanisms involved in the toxic action of dieldrin. We found that 2 and 6 days in vitro (DIV) exposure to a subcytotoxic concentration (60nM) of dieldrin reduced the increase in intracellular calcium concentration ([Ca(2+)](i)) and the excitotoxicity caused by glutamate. Exposure to dieldrin for 6 DIV induced N-methyl-D-aspartate receptor (NMDAR) internalization and reduced metabotropic glutamate receptor 5 (mGLUR5) levels. Double immunostaining for NMDAR and mGLUR5 showed that these receptors lose colocalization on the cell membrane in neurons treated with dieldrin. No changes were observed in receptor functionalities or receptor levels after 2 DIV of exposure to dieldrin. However, the increase in [Ca(2+)](i) induced by coactivation of NMDAR and mGLUR5 was significantly reduced. Thus, a functional interaction between the two receptors seems to play an important role in glutamate-induced excitotoxicity. We confirm that permanent blockade of the GABA(A) receptor by this persistent pesticide triggers adaptive neuronal changes consisting of a reduction of glutamatergic neurotransmission. This might explain the cognitive and learning deficits observed in animals after chronic treatment with dieldrin.

  16. Induction of Anti-Hebbian LTP in CA1 Stratum Oriens Interneurons: Interactions between Group I Metabotropic Glutamate Receptors and M1 Muscarinic Receptors

    OpenAIRE

    Le Duigou, C.; Savary, E.; Kullmann, D M.; Miles, R.

    2015-01-01

    An anti-Hebbian form of LTP is observed at excitatory synapses made with some hippocampal interneurons. LTP induction is facilitated when postsynaptic interneurons are hyperpolarized, presumably because Ca(2+) entry through Ca(2+)-permeable glutamate receptors is enhanced. The contribution of modulatory transmitters to anti-Hebbian LTP induction remains to be established. Activation of group I metabotropic receptors (mGluRs) is required for anti-Hebbian LTP induction in interneurons with cell...

  17. Computer-aided design of negative allosteric modulators of metabotropic glutamate receptor 5 (mGluR5): Comparative molecular field analysis of aryl ether derivatives.

    Science.gov (United States)

    Selvam, Chelliah; Thilagavathi, Ramasamy; Narasimhan, Balasubramanian; Kumar, Pradeep; Jordan, Brian C; Ranganna, Kasturi

    2016-02-15

    The metabotropic glutamate receptors (mGlu receptors) have emerged as attractive targets for number of neurological and psychiatric disorders. Recently, mGluR5 negative allosteric modulators (NAMs) have gained considerable attention in pharmacological research. Comparative molecular field analysis (CoMFA) was performed on 73 analogs of aryl ether which were reported as mGluR5 NAMs. The study produced a statistically significant model with high correlation coefficient and good predictive abilities.

  18. Involvement of metabotropic glutamate receptor 5 in the inhibition of methamphetamine-associated contextual memory after prolonged extinction training.

    Science.gov (United States)

    Huang, Chien-Hsuan; Yu, Yang-Jung; Chang, Chih-Hua; Gean, Po-Wu

    2016-04-01

    Addiction is thought to be a memory process between perception and environmental cues and addicted patients often relapse when they come into contact with the drug-related context once again. Here, we used a conditioned place preference protocol to seek a more effective extinction methodology of methamphetamine (METH) memory and delineate its underlying mechanism. Conditioning METH for 3 days in mice markedly increased the time spent in the METH-paired compartment. Then the mice were conditioned with saline for 6 days, from day 6 to day 11, a procedure termed extinction training. However, METH memory returned after a priming injection of METH. We prolonged extinction duration from 6 to 10 days and found that this extensive extinction (EE) training prevented priming effect. At the molecular level, we discovered that prolonged extinction training reversed the METH-conditioned place preference-induced increase in surface expression of GluA2 and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/NMDA ratio in the basolateral amygdala. In addition, we found that extinction with metabotropic glutamate receptor 5 (mGluR5) activation had similar results to EE: reduced relapse after extinction, decreased synaptic AMPA receptors AMPARs and the AMPA/NMDA ratio. On the contrary, EE with mGluR5 inhibition suppressed the results of EE. These data indicate that EE training-elicited inhibition of METH-primed reinstatement is mediated by the mGluR5. Conditioning mice with methamphetamine place preference (METH CPP) increases surface expression of AMPA receptors (AMPARs) in the basolateral amygdala. We found prolongation of extinction duration from 6 to 10 days prevented priming effect. At the molecular level, we discovered that extensive extinction (EE) reversed the METH CPP-induced increase in surface expression of GluA2 and AMPA/NMDA ratio. In addition, we found that extinction with the metabotropic glutamate receptor 5 (mGluR5) activation had similar results to EE

  19. Estrogen Receptor β Activation Rapidly Modulates Male Sexual Motivation through the Transactivation of Metabotropic Glutamate Receptor 1a.

    Science.gov (United States)

    Seredynski, Aurore L; Balthazart, Jacques; Ball, Gregory F; Cornil, Charlotte A

    2015-09-23

    In addition to the transcriptional activity of their liganded nuclear receptors, estrogens, such as estradiol (E2), modulate cell functions, and consequently physiology and behavior, within minutes through membrane-initiated events. The membrane-associated receptors (mERs) underlying the acute effects of estrogens on behavior have mostly been documented in females where active estrogens are thought to be of ovarian origin. We determined here, by acute intracerebroventricular injections of specific agonists and antagonists, the type(s) of mERs that modulate rapid effects of brain-derived estrogens on sexual motivation in male Japanese quail. Brain aromatase blockade acutely inhibited sexual motivation. Diarylpropionitrile (DPN), an estrogen receptor β (ERβ)-specific agonist, and to a lesser extent 17α-estradiol, possibly acting through ER-X, prevented this effect. In contrast, drugs targeting ERα (PPT and MPP), GPR30 (G1 and G15), and the Gq-mER (STX) did not affect sexual motivation. The mGluR1a antagonist LY367385 significantly inhibited sexual motivation but mGluR2/3 and mGluR5 antagonists were ineffective. LY367385 also blocked the behavioral restoration induced by E2 or DPN, providing functional evidence that ERβ interacts with metabotropic glutamate receptor 1a (mGluR1a) signaling to acutely regulate male sexual motivation. Together these results show that ERβ plays a key role in sexual behavior regulation and the recently uncovered cooperation between mERs and mGluRs is functional in males where it mediates the acute effects of estrogens produced centrally in response to social stimuli. The presence of an ER-mGluR interaction in birds suggests that this mechanism emerged relatively early in vertebrate history and is well conserved. Significance statement: The membrane-associated receptors underlying the acute effects of estrogens on behavior have mostly been documented in females, where active estrogens are thought to be of ovarian origin. Using acute

  20. Neurophysiologic and antipsychotic profiles of TASP0433864, a novel positive allosteric modulator of metabotropic glutamate 2 receptor.

    Science.gov (United States)

    Hiyoshi, Tetsuaki; Marumo, Toshiyuki; Hikichi, Hirohiko; Tomishima, Yasumitsu; Urabe, Hiroki; Tamita, Tomoko; Iida, Izumi; Yasuhara, Akito; Karasawa, Jun-ichi; Chaki, Shigeyuki

    2014-12-01

    Excess glutamatergic neurotransmission has been implicated in the pathophysiology of schizophrenia, and the activation of metabotropic glutamate 2 (mGlu2) receptor may exert antipsychotic effects by normalizing glutamate transmission. In the present study, we investigated the neurophysiologic and antipsychotic profiles of TASP0433864 [(2S)-2-[(4-tert-butylphenoxy)methyl]-5-methyl-2,3-dihydroimidazo[2,1-b][1,3]oxazole-6-carboxamide], a newly synthesized positive allosteric modulator (PAM) of mGlu2 receptor. TASP0433864 exhibited PAM activity at human and rat mGlu2 receptors with EC50 values of 199 and 206 nM, respectively, without exerting agonist activity at rat mGlu2 receptor. TASP0433864 produced a leftward and upward shift in the concentration-response curve of glutamate-increased guanosine 5'-O-(3-[(35)S]thio)triphosphate binding to mGlu2 receptor. In contrast, TASP0433864 had negligible activities for other mGlu receptors, including mGlu3 receptor, and did not have any affinity for other receptors or transporters. In hippocampal slices, TASP0433864 potentiated an inhibitory effect of DCG-IV [(2S,2'R,3'R)-2-(2',3'-dicarboxylcyclopropyl)glycine], a mGlu2/3 receptor agonist, on the field excitatory postsynaptic potentials in the dentate gyrus, indicating that TASP0433864 potentiates the mGlu2 receptor-mediated presynaptic inhibition of glutamate release. Moreover, TASP0433864 inhibited both MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate]- and ketamine-increased cortical γ band oscillation in the rat cortical electroencephalogram, which have been considered to reflect the excess activation of cortical pyramidal neurons. The inhibitory effect of TASP0433864 on cortical activation was also observed in the mouse 2-deoxy-glucose uptake study. In a behavioral study, TASP0433864 significantly inhibited both ketamine- and methamphetamine-increased locomotor activities in mice and rats, respectively. Collectively, these

  1. Metabotropic glutamate2/3 receptor agonism facilitates autonomic recovery after pharmacological panic challenge in healthy humans.

    Science.gov (United States)

    Agorastos, Agorastos; Demiralay, Cüneyt; Stiedl, Oliver; Muhtz, Christoph; Wiedemann, Klaus; Kellner, Michael

    2016-05-01

    Group II metabotropic glutamate receptors (mGluR2/3) are suggested to modulate anxiety, arousal, and stress including autonomic control. However, no study has investigated mGluR2/3-related effects on baseline autonomic activity and reactivity to emotional challenge in humans as yet. Using a double-blind, randomized placebo-controlled, cross-over study design, we investigated the influence of a 1-week treatment with the mGluR2/3 agonist LY544344, prodrug of LY354740, on autonomic reactivity to a cholecystokinin tetrapeptide (CCK-4) panic challenge in eight healthy young men. The main outcome measures were time and frequency domain heart rate variability parameters during baseline, CCK-4 challenge, and recovery. There was no evidence for LY544344-mediated effects on baseline and CCK-4 challenge vagal activity, but a significantly lower recovery low frequency (%) and low frequency/high frequency ratio in the LY544344 group, suggesting enhanced autonomic recovery. This pilot study provides first human data indicating that mGluR2/3 agonism is involved in autonomic responsiveness, suggesting an important role of mGluR2/3 in central autonomic regulation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-15

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

  3. Temporal and spatial distribution of metabotropic glutamate receptor 5 during development in the rat cortex and hippocampus

    Institute of Scientific and Technical Information of China (English)

    Xinli Xiao; Ming Hu; Pengbo Yang; Lin Zhang; Xinlin Chen; Yong Liu

    2011-01-01

    Metabotropic glutamate receptor 5 (mGluR5) is expressed by neurons in zones of active neurogenesis and is involved in the development of neural stem cells in vivo and in vitro. We examined the expression of mGluR5 in the cortex and hippocampus of rats during various prenatal and postnatal periods using immunohistochemistry. During prenatal development, mGluR5 was primarily localized to neuronal somas in the forebrain. During early postnatal periods, the receptor was mainly present on somas in the cortex. mGluR5 immunostaining was visible in apical dendrites and in the neuropil of neurons and persisted throughout postnatal development. During this period, pyramidal neurons were strongly labeled for the receptor. In the hippocampal CA1 region, mGluR5 immunoreactivity was more intense in the stratum oriens, stratum radiatum, and lacunosum moleculare at P0, P5 and P10 relative to P60. mGluR5 expression increased significantly in the molecular layer and decreased significantly in the granule cell layer of the dentate gyrus at P5, P10 and P60 in comparison with P0. Furthermore, some mGluR5-positive cells were also bromodeoxyuridine- or NeuroD-positive in the dentate gyrus at P14. These results demonstrate that mGluR5 has a differential expression pattern in the cortex and hippocampus during early growth, suggesting a role for this receptor in the control of domain specific brain developmental events.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-02-01

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

  5. Investigation of allosteric modulation mechanism of metabotropic glutamate receptor 1 by molecular dynamics simulations, free energy and weak interaction analysis

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    Bai, Qifeng; Yao, Xiaojun

    2016-02-01

    Metabotropic glutamate receptor 1 (mGlu1), which belongs to class C G protein-coupled receptors (GPCRs), can be coupled with G protein to transfer extracellular signal by dimerization and allosteric regulation. Unraveling the dimer packing and allosteric mechanism can be of great help for understanding specific regulatory mechanism and designing more potential negative allosteric modulator (NAM). Here, we report molecular dynamics simulation studies of the modulation mechanism of FITM on the wild type, T815M and Y805A mutants of mGlu1 through weak interaction analysis and free energy calculation. The weak interaction analysis demonstrates that van der Waals (vdW) and hydrogen bonding play an important role on the dimer packing between six cholesterol molecules and mGlu1 as well as the interaction between allosteric sites T815, Y805 and FITM in wild type, T815M and Y805A mutants of mGlu1. Besides, the results of free energy calculations indicate that secondary binding pocket is mainly formed by the residues Thr748, Cys746, Lys811 and Ser735 except for FITM-bound pocket in crystal structure. Our results can not only reveal the dimer packing and allosteric regulation mechanism, but also can supply useful information for the design of potential NAM of mGlu1.

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

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    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.

  7. 代谢型谷氨酸受体与吗啡耐受和依赖%Involvement of metabotropic glutamate receptor in morphine tolerance and dependence

    Institute of Scientific and Technical Information of China (English)

    刘金变; 江伟

    2009-01-01

    Glutamate mediates its effects via both ionotropie and metabotropic receptors. Metabotropic glutamate receptors (mGluRs) include eight subtypes and are classified into three major groups. G protein-coupled mGluRs modulate function of ion channel, neurotransmitter releasing, synapse transmission and plasticity through pre-and post-synaptic sites. Recent evidence supports the involvement of mGluRs in the development of morphine tolerance and dependence. This article reviewed the progress in differential role of mGluRs subtypes in morphine tolerance and dependence.%谷氨酸通过离子型和代谢型谷氨酸受体(metabotropic Slutmate receptors,mGluRs)发挥作用,其中mGluRs是G蛋白耦联受体,分为3组共8个亚型,通过突触前和突触后作用参与离子通道活动调节、神经递质释放、突触传递和突触町塑性等生理病理过程.研究表明mGluRs与吗啡耐受和依赖密切有关.现就近年来各种类型的mGluRs参与吗啡耐受和依赖的研究进展作一综述.

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

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    Shostak Y

    2014-09-01

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

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

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    Bernabucci Matteo

    2012-10-01

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

  10. Could MDMA Promote Stemness Characteristics in Mouse Embryonic Stem Cells via mGlu5 Metabotropic Glutamate Receptors?

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    Rokhsareh Meamar

    2012-01-01

    Full Text Available Objective: Ecstasy, or 3, 4 (± methylenedioxymethamphetamine (MDMA, is a potent neurotoxic drug. One of the mechanisms for its toxicity is the secondary release of glutamate. Mouse embryonic stem cells (mESCs express only one glutamate receptor, the metabotropic glutamate receptor 5 (mGlu5, which is involved in the maintenance and self-renewal of mESCs. This study aims to investigate whether MDMA could influence self-renewal via the mGlu5 receptor in mESCs.Materials and Methods: In this expremental study, we used immunocytochemistry and reverse transcription-polymerase chain reaction (RT-PCR to determine the presence of the mGlu5 receptor in mESCs. The expression of mGlu5 was evaluated after MDMA was added to mESCs throughout neural precursor cell formation as group 1 and during neural precursor cell differentiation as group 2. The stemness characteristic in treated mESCs by immunofluorescence and flow cytometry was studied. Finally, caspase activity was evaluated by fluorescence staining in the treated group. One-way ANOVA or repeated measure of ANOVA according to the experimental design was used for statistical analyses.Results: In this study mGlu5 expression was shown in mESCs. In terms of neuronal differentiation, MDMA affected mGlu5 expression during neural precursor cell formation (group 1 and not during neural precursor differentiation (group 2. MDMA (450 μM induced a significant increment in self-renewal properties in mESCs but did not reverse 2-methyl-6(phenylethynyl pyridine (MPEP, 1 μM, a non-competitive selective mGlu5 antagonist. Fluorescence staining with anti-caspase 3 showed a significant increase in the number of apoptotic cells in the MDMA group.Conclusion: We observed a dual role for MDMA on mESCs: reduced proliferation and maintenance of self-renewal. The lack of decreasing stemness characteristic in presence of MPEP suggests that MDMA mediates its role through a different mechanism that requires further investigation. In

  11. The impact of corticothalamic feedback on the output dynamics of a thalamocortical neurone model: the role of synapse location and metabotropic glutamate receptors.

    Science.gov (United States)

    Emri, Z; Antal, K; Crunelli, V

    2003-01-01

    The spatio-temporal integration of cortical excitatory postsynaptic potentials was investigated in a multi-compartment model of a thalamocortical neurone. Consistent with experimental data, cortical excitatory postsynaptic potentials contained a metabotropic glutamate receptor-mediated component and were generated by synapses located on distal dendrites. Within this framework, three synaptic distributions (each with equal maximal synaptic conductances) were compared: symmetric, with synapses distributed equally between all dendritic trees, single-dendrite, where synapses were allocated on all distal segments of one dendrite, and single-segment, which comprised one synapse on a single dendritic compartment. We addressed three main issues: (1) the propagation of cortical excitatory postsynaptic potentials to the soma, (2) the interaction of cortical excitatory postsynaptic potentials with proximally generated retinal excitatory postsynaptic potentials, and (3) the effectiveness of cortical excitatory postsynaptic potentials in entraining and perturbing the delta oscillation. The somatic and dendritic amplitudes of the cortical excitatory postsynaptic potentials depended on the distribution of the synapses, being largest and smallest, respectively, for the symmetric distribution, and smallest and largest, respectively, for the single-segment distribution. When a retinal excitatory postsynaptic potential followed a subthreshold cortical excitatory postsynaptic potential with a short (2-200 ms) delay, its ability to evoke action potentials was increased, with single-segment cortical excitatory postsynaptic potentials having the longest-lasting facilitatory effect. When a retinal excitatory postsynaptic potential arrived with a longer delay (210-400 ms), the effect of the cortical excitatory postsynaptic potential was to decrease the number of retinally evoked action potentials. These facilitatory and depressant effects of the cortical excitatory postsynaptic potentials

  12. Dynamic modulation of inflammatory pain-related affective and sensory symptoms by optical control of amygdala metabotropic glutamate receptor 4.

    Science.gov (United States)

    Zussy, C; Gómez-Santacana, X; Rovira, X; De Bundel, D; Ferrazzo, S; Bosch, D; Asede, D; Malhaire, F; Acher, F; Giraldo, J; Valjent, E; Ehrlich, I; Ferraguti, F; Pin, J-P; Llebaria, A; Goudet, C

    2016-12-20

    Contrary to acute pain, chronic pain does not serve as a warning signal and must be considered as a disease per se. This pathology presents a sensory and psychological dimension at the origin of affective and cognitive disorders. Being largely refractory to current pharmacotherapies, identification of endogenous systems involved in persistent and chronic pain is crucial. The amygdala is a key brain region linking pain sensation with negative emotions. Here, we show that activation of a specific intrinsic neuromodulatory system within the amygdala associated with type 4 metabotropic glutamate receptors (mGlu4) abolishes sensory and affective symptoms of persistent pain such as hypersensitivity to pain, anxiety- and depression-related behaviors, and fear extinction impairment. Interestingly, neuroanatomical and synaptic analysis of the amygdala circuitry suggests that the effects of mGlu4 activation occur outside the central nucleus via modulation of multisensory thalamic inputs to lateral amygdala principal neurons and dorso-medial intercalated cells. Furthermore, we developed optogluram, a small diffusible photoswitchable positive allosteric modulator of mGlu4. This ligand allows the control of endogenous mGlu4 activity with light. Using this photopharmacological approach, we rapidly and reversibly inhibited behavioral symptoms associated with persistent pain through optical control of optogluram in the amygdala of freely behaving animals. Altogether, our data identify amygdala mGlu4 signaling as a mechanism that bypasses central sensitization processes to dynamically modulate persistent pain symptoms. Our findings help to define novel and more precise therapeutic interventions for chronic pain, and exemplify the potential of optopharmacology to study the dynamic activity of endogenous neuromodulatory mechanisms in vivo.Molecular Psychiatry advance online publication, 20 December 2016; doi:10.1038/mp.2016.223.

  13. ADX71743, a potent and selective negative allosteric modulator of metabotropic glutamate receptor 7: in vitro and in vivo characterization.

    Science.gov (United States)

    Kalinichev, Mikhail; Rouillier, Mélanie; Girard, Francoise; Royer-Urios, Isabelle; Bournique, Bruno; Finn, Terry; Charvin, Delphine; Campo, Brice; Le Poul, Emmanuel; Mutel, Vincent; Poli, Sonia; Neale, Stuart A; Salt, Thomas E; Lütjens, Robert

    2013-03-01

    Metabotropic glutamate receptor 7 (mGlu(7)) has been suggested to be a promising novel target for treatment of a range of disorders, including anxiety, post-traumatic stress disorder, depression, drug abuse, and schizophrenia. Here we characterized a potent and selective mGlu(7) negative allosteric modulator (NAM) (+)-6-(2,4-dimethylphenyl)-2-ethyl-6,7-dihydrobenzo[d]oxazol-4(5H)-one (ADX71743). In vitro, Schild plot analysis and reversibility tests at the target confirmed the NAM properties of the compound and attenuation of L-(+)-2-amino-4-phosphonobutyric acid-induced synaptic depression confirmed activity at the native receptor. The pharmacokinetic analysis of ADX71743 in mice and rats revealed that it is bioavailable after s.c. administration and is brain penetrant (cerebrospinal fluid concentration/total plasma concentration ratio at C(max) = 5.3%). In vivo, ADX71743 (50, 100, 150 mg/kg, s.c.) caused no impairment of locomotor activity in rats and mice or activity on rotarod in mice. ADX71743 had an anxiolytic-like profile in the marble burying and elevated plus maze tests, dose-dependently reducing the number of buried marbles and increasing open arm exploration, respectively. Whereas ADX71743 caused a small reduction in amphetamine-induced hyperactivity in mice, it was inactive in the mouse 2,5-dimethoxy-4-iodoamphetamine-induced head twitch and the rat conditioned avoidance response tests. In addition, the compound was inactive in the mouse forced swim test. These data suggest that ADX71743 is a suitable compound to help unravel the physiologic role of mGlu(7) and to better understand its implication in central nervous system diseases. Our in vivo tests using ADX71743, reported here, suggest that pharmacological inhibition of mGlu(7) is a valid approach for developing novel pharmacotherapies to treat anxiety disorders, but may not be suitable for treatment of depression or psychosis.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. 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.

  16. Modulation of intracellular calcium mobilization and GABAergic currents through subtype-specific metabotropic glutamate receptors in neonatal rat hippocampus.

    Science.gov (United States)

    Taketo, M; Matsuda, H

    2010-01-15

    Group I metabotropic glutamate receptors (mGluRs) are coupled to phosphoinositide hydrolysis, and are thought to modulate neuronal excitability, by mobilizing intracellular Ca(2+). Difference in Ca(2+) mobilization among subclasses of the receptors has been reported, and regarded as a possible cause of variant neuronal modifications. In hippocampal interneurons, several subclasses of mGluRs including mGluR1 and mGluR5 have been immunohistochemically identified. The subclass-specific physiological effects of mGluRs on neuronal transmission in hippocampus, however, have not been fully elucidated. In the present study, effects of group I mGluR agonist, (S)-3,5-dihydroxyphenylglycine (DHPG) on intracellular calcium concentration were examined in hippocampal interneurons. Application of DHPG increased fluorescence ratio in neonatal CA3 stratum oriens/alveus interneurons. The DHPG-induced calcium mobilization was markedly inhibited by mGluR1-specific antagonist, cyclopropan[b]chromen-1a-carboxylate (CPCCOEt). Inhibition of the calcium elevation by mGluR5-specific antagonist, 6-methyl-2-(phenylazo)-3-pyrindol (MPEP), was weaker than that of CPCCOEt. The fluorescence ratio was not significantly changed by application of mGluR5-specific agonist, (RS)-2-chloro-5-hydroxyphenylglycine (CHPG). DHPG induced calcium responses in CA1 interneurons as in CA3, and the responses were partially inhibited by MPEP treatment. Effects of group I mGluR agonist and antagonist were also investigated, on GABA(A) receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in CA3 pyramidal neurons. The GABAergic sIPSCs were facilitated by DHPG perfusion, and the potentiation was reduced by CPCCOEt, and less distinctly by MPEP. The sIPSCs were not significantly potentiated by CHPG application. These results indicate that mGluR1 is functional in hippocampal interneurons, and DHPG exerts its effect mainly through this receptor at early developmental period.

  17. Contribution of opioid and metabotropic glutamate receptor mechanisms to inhibition of bladder overactivity by tibial nerve stimulation.

    Science.gov (United States)

    Matsuta, Yosuke; Mally, Abhijith D; Zhang, Fan; Shen, Bing; Wang, Jicheng; Roppolo, James R; de Groat, William C; Tai, Changfeng

    2013-07-15

    The contribution of metabotropic glutamate receptors (mGluR) and opioid receptors to inhibition of bladder overactivity by tibial nerve stimulation (TNS) was investigated in cats under α-chloralose anesthesia using LY341495 (a group II mGluR antagonist) and naloxone (an opioid receptor antagonist). Slow infusion cystometry was used to measure the volume threshold (i.e., bladder capacity) for inducing a large bladder contraction. After measuring the bladder capacity during saline infusion, 0.25% acetic acid (AA) was infused to irritate the bladder, activate the nociceptive C-fiber bladder afferents, and induce bladder overactivity. AA significantly (P < 0.0001) reduced bladder capacity to 26.6 ± 4.7% of saline control capacity. TNS (5 Hz, 0.2 ms) at 2 and 4 times the threshold (T) intensity for inducing an observable toe movement significantly increased bladder capacity to 62.2 ± 8.3% at 2T (P < 0.01) and 80.8 ± 9.2% at 4T (P = 0.0001) of saline control capacity. LY341495 (0.1-5 mg/kg iv) did not change bladder overactivity, but completely suppressed the inhibition induced by TNS at a low stimulus intensity (2T) and partially suppressed the inhibition at high intensity (4T). Following administration of LY341495, naloxone (0.01 mg/kg iv) completely eliminated the high-intensity TNS-induced inhibition. However, without LY341495 treatment a 10 times higher dose (0.1 mg/kg) of naloxone was required to completely block TNS inhibition. These results indicate that interactions between group II mGluR and opioid receptor mechanisms contribute to TNS inhibition of AA-induced bladder overactivity. Understanding neurotransmitter mechanisms underlying TNS inhibition of bladder overactivity is important for the development of new treatments for bladder disorders.

  18. Metabotropic Glutamate Receptor Subtype 7 in the Bed Nucleus of the Stria Terminalis is Essential for Intermale Aggression.

    Science.gov (United States)

    Masugi-Tokita, Miwako; Flor, Peter J; Kawata, Mitsuhiro

    2016-02-01

    Metabotropic glutamate receptor subtype 7 (mGluR7) is a member of group III mGluRs, which localize to the presynaptic active zones of the mammalian central nervous system. Although histological, genetic, and electrophysiological studies ensure the importance of mGluR7, its roles in behavior and physiology remain largely unknown. Using a resident-intruder paradigm, we found a severe reduction in intermale aggressive behavior in mGluR7 knockout (KO) mice. We also found alterations in other social behaviors in male mGluR7 KO mice, including sexual behavior toward male intruders. Because olfaction is critical for rodent social behavior, including aggression, we performed an olfaction test, finding that mGluR7 KO mice failed to show interest in the smell of male urine. To clarify the olfactory deficit, we then exposed mice to urine and analyzed c-Fos-immunoreactivity, discovering a remarkable reduction in neural activity in the bed nucleus of the stria terminalis (BNST) of mGluR7 KO mice. Finally, intra-BNST administration of the mGluR7-selective antagonist 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP) also reproduced the phenotype of mGluR7 KO mice, including reduced aggression and altered social interaction. Thus mGluR7 may work as an 'enhancer of neural activity' in the BNST and is important for intermale aggression. Our findings demonstrate that mGluR7 is essential for social behavior and innate behavior. Our study on mGluR7 in the BNST will shed light on future therapies for emotional disorders in humans.

  19. N-Methyl-d-aspartate Modulation of Nucleus Accumbens Dopamine Release by Metabotropic Glutamate Receptors: Fast Cyclic Voltammetry Studies in Rat Brain Slices in Vitro.

    Science.gov (United States)

    Yavas, Ersin; Young, Andrew M J

    2017-02-15

    The N-methyl-d-aspartate (NMDA) receptor antagonist, phencyclidine, induces behavioral changes in rodents mimicking symptoms of schizophrenia, possibly mediated through dysregulation of glutamatergic control of mesolimbic dopamine release. We tested the hypothesis that NMDA receptor activation modulates accumbens dopamine release, and that phencyclidine pretreatment altered this modulation. NMDA caused a receptor-specific, dose-dependent decrease in electrically stimulated dopamine release in nucleus accumbens brain slices. This decrease was unaffected by picrotoxin, making it unlikely to be mediated through GABAergic neurones, but was decreased by the metabotropic glutamate receptor antagonist, (RS)-α-methyl-4-sulfonophenylglycine, indicating that NMDA activates mechanisms controlled by these receptors to decrease stimulated dopamine release. The effect of NMDA was unchanged by in vivo pretreatment with phencyclidine (twice daily for 5 days), with a washout period of at least 7 days before experimentation, which supports the hypothesis that there is no enduring direct effect of PCP at NMDA receptors after this pretreatment procedure. We propose that NMDA depression of accumbal dopamine release is mediated by metabotropic glutamate receptors located pre- or perisynaptically, and suggest that NMDA evoked increased extrasynaptic spillover of glutamate is sufficient to activate these receptors that, in turn, inhibit dopamine release. Furthermore, we suggest that enduring functional changes brought about by subchronic phencyclidine pretreatment, modeling deficits in schizophrenia, are downstream effects consequent on chronic blockade of NMDA receptors, rather than direct effects on NMDA receptors themselves.

  20. Metabotropic glutamate receptors are involved in the detection of IMP and L-amino acids by mouse taste sensory cells.

    Science.gov (United States)

    Pal Choudhuri, S; Delay, R J; Delay, E R

    2016-03-01

    G-protein-coupled receptors are thought to be involved in the detection of umami and L-amino acid taste. These include the heterodimer taste receptor type 1 member 1 (T1r1)+taste receptor type 1 member 3 (T1r3), taste and brain variants of mGluR4 and mGluR1, and calcium sensors. While several studies suggest T1r1+T1r3 is a broadly tuned lLamino acid receptor, little is known about the function of metabotropic glutamate receptors (mGluRs) in L-amino acid taste transduction. Calcium imaging of isolated taste sensory cells (TSCs) of T1r3-GFP and T1r3 knock-out (T1r3 KO) mice was performed using the ratiometric dye Fura 2 AM to investigate the role of different mGluRs in detecting various L-amino acids and inosine 5' monophosphate (IMP). Using agonists selective for various mGluRs such as (RS)-3,5-dihydroxyphenylglycine (DHPG) (an mGluR1 agonist) and L-(+)-2-amino-4-phosphonobutyric acid (l-AP4) (an mGluR4 agonist), we evaluated TSCs to determine if they might respond to these agonists, IMP, and three L-amino acids (monopotassium L-glutamate, L-serine and L-arginine). Additionally, we used selective antagonists against different mGluRs such as (RS)-L-aminoindan-1,5-dicarboxylic acid (AIDA) (an mGluR1 antagonist), and (RS)-α-methylserine-O-phosphate (MSOP) (an mGluR4 antagonist) to determine if they can block responses elicited by these L-amino acids and IMP. We found that L-amino acid- and IMP-responsive cells also responded to each agonist. Antagonists for mGluR4 and mGluR1 significantly blocked the responses elicited by IMP and each of the L-amino acids. Collectively, these data provide evidence for the involvement of taste and brain variants of mGluR1 and mGluR4 in L-amino acid and IMP taste responses in mice, and support the concept that multiple receptors contribute to IMP and L-amino acid taste.

  1. Metabotropic glutamate receptors involved in nociception and their signaling transductions%参与伤害性反应的代谢型谷氨酸受体及信号转导机制

    Institute of Scientific and Technical Information of China (English)

    王云; 岳云; 吴安石

    2009-01-01

    代谢型谷氨酸受体(metabotropic glutamate receptors,mGluRs)是一类与G蛋白耦联的谷氨酸受体,在外周和脊髓参与伤害性信号的处理,并通过不同的细胞内信号转导机制,调节各种激酶、受体和离子通道的磷酸化以及转录因子的激活,是治疗疼痛的重要靶位.%Metabotropic glutamate receptors represent a family of G protein-coupled receptors.They are involved in the nociceptive process at the peripheral and central levels and tigger different signaling transduction pathways,which may further activate a variety of kinases,receptors,ion channels and transcription factors.As such,metabotropic glutamate receptors arepotential drug targets for pain relief.

  2. Metabotropic glutamate mGlu2 receptor is necessary for the pharmacological and behavioral effects induced by hallucinogenic 5-HT2A receptor agonists

    OpenAIRE

    Moreno, José L.; Holloway, Terrell; Albizu, Laura; Sealfon, Stuart C.; González-Maeso, Javier

    2011-01-01

    Hallucinogenic drugs, including mescaline, psilocybin and lysergic acid diethylamide (LSD), act at serotonin 5-HT2A receptors (5-HT2ARs). Metabotropic glutamate receptor 2/3 (mGluR2/3) ligands show efficacy in modulating the responses induced by activation of 5-HT2ARs. The formation of a 5-HT2AR-mGluR2 complex suggests a functional interaction that affects the hallucinogen-regulated cellular signaling pathways. Here, we tested the cellular and behavioral effects of hallucinogenic 5-HT2AR agon...

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

    Directory of Open Access Journals (Sweden)

    Sylvia eTerbeck

    2015-03-01

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

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

    Science.gov (United States)

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

    2012-07-01

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

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

    DEFF Research Database (Denmark)

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

    2001-01-01

    The potential toxic effects of the metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) and its interactions with the N-methyl-D-aspartate (NMDA) receptor were studied in hippocampal brain slice cultures, using densitometric measurements of the cellular....... The neurodegeneration induced by 2 mM ACPD was completely abolished by addition of 10 microM of the NMDA receptor antagonist (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), while 20 microM of the 2-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)/kainic acid receptor antagonist...... of metabotropic glutamate receptors with ACPD at concentrations of 2 mM or higher induces a distinct subfield-related and time and concentration dependent pattern of hippocampal degeneration, and that ACPD at subtoxic concentrations modulates NMDA-induced excitotoxicity through the mGluR5 receptor in a time...

  6. Translational Pharmacology of the Metabotropic Glutamate 2 Receptor-Preferring Agonist LY2812223 in the Animal and Human Brain.

    Science.gov (United States)

    Felder, Christian C; Schober, Douglas A; Tu, Yuan; Quets, Anne; Xiao, Hongling; Watt, Marla; Siuda, Ed; Nisenbaum, Eric; Xiang, Chuanxi; Heinz, Beverly; Prieto, Lourdes; McKinzie, David L; Monn, James A

    2017-04-01

    LY2812223 [(1R,2S,4R,5R,6R)-2-amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic acid] was identified via structure-activity studies arising from the potent metabotropic glutamate mGlu2/3 receptor agonist LY354740 [(+)-2-aminobicyclo[3.1.0] hexane-2,6-dicarboxylic acid] as an mGlu2-preferring agonist. This pharmacology was determined using stably transfected cells containing either the human mGlu2 or mGlu3 receptor. We extended the pharmacological evaluation of LY2812223 to native brain tissues derived from relevant species used for preclinical drug development as well as human postmortem brain tissue. This analysis was conducted to ensure pharmacological translation from animals to human subjects in subsequent clinical studies. A guanosine 5'-O-(3-[(35)S]thio)triphosphate (GTPγS) functional binding assay, a method for measuring Gi-coupled signaling that is inherent to the group 2 mGlu receptors, was used to evaluate LY2812223 pharmacology of native mGlu receptors in mouse, rat, nonhuman primate, and human cortical brain tissue samples. In native tissue membranes, LY2812223 unexpectedly acted as a partial agonist across all species tested. Activity of LY2812223 was lost in cortical membranes collected from mGlu2 knockout mice, but not those from mGlu3 knockout mice, providing additional support for mGlu2-preferring activity. Other signal transduction assays were used for comparison with the GTP binding assay (cAMP, calcium mobilization, and dynamic mass redistribution). In ectopic cell line-based assays, LY2812223 displayed near maximal agonist responses at the mGlu2 receptor across all assay formats, while it showed no functional agonist activity at the mGlu3 receptor except in the cAMP assay. In native brain slices or membranes that express both mGlu2 and mGlu3 receptors, LY2812223 displayed unexpected partial agonist activity, which may suggest a functional interplay between these receptor subtypes in the brain. Copyright © 2017 by

  7. Metabotropic glutamate receptor 7 modulates the rewarding effects of cocaine in rats: involvement of a ventral pallidal GABAergic mechanism.

    Science.gov (United States)

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

    2009-06-01

    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 microg/microl 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 microg/microl 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.

  8. In vitro binding of a radio-labeled positive allosteric modulator for metabotropic glutamate receptor subtype 5.

    Science.gov (United States)

    Zysk, John R; Spear, Nathan; Fieles, William; Stein, Mark M; Sygowski, Linda S; King, Megan M; Hoesch, Valerie; Hastings, Richard; Brockel, Becky; Do, Mylinh; Ström, Peter; Gadient, Reto; Chhajlani, Vijay; Elmore, Charles S; Maier, Donna L

    2013-03-01

    The positive allosteric modulator (PAM) binding site for metabotropic glutamate receptor subtype 5 (mGlu(5)) lacks a readily available radio-labeled tracer fordetailed structure-activity studies. This communication describes a selective mGlu(5) compound, 7-methyl-2-(4-(pyridin-2-yloxy)benzyl)-5-(pyridin-3-yl)isoindolin-1-one (PBPyl) that binds with high affinity to human mGlu(5) and exhibits functional PAM activity. Analysis of PBPyl by FLIPR revealed an EC(50) of 87 nM with an 89% effect in transfected HEK293 cells and an EC(50) of 81 nM with a 42% effect in rat primary neurons. PBPyl exhibited 5-fold higher functional selectivity for mGlu(5) in a full mGlu receptor panel. Unlabeled PBPyl was tested for specific binding using a liquid chromatography mass spectrometry (LC/MS/MS)-based filtration binding assay and exhibited 40% specific binding in recombinant membranes, a value higher than any candidate compound tested. In competition binding studies with [(3)H]MPEP, the mGlu(5) receptor negative allosteric modulator (NAM), PBPyl exhibited a k(i) value of 34 nM. PBPyl also displaced [(3)H]ABP688, a mGluR(5) receptor NAM, in tissue sections from mouse and rat brain using autoradiography. Areas of specific binding included the frontal cortex, striatum and nucleus accumbens. PBPyl was radiolabeled to a specific activity of 15 Ci/mmol and tested for specific binding in a filter plate format. In recombinant mGlu(5b) membranes, [(3)H] PBPyl exhibited saturable binding with a K(d) value of 18.6 nM. In competition binding experiments, [(3)H] PBPyl was displaced by high affinity mGlu(5) positive and negative modulators. Further tests showed that PBPyl displays less than optimal characteristics as an in vivo tool, including a high volume of distribution and ClogP, making it more suitable as an in vitro compound. However, as a first report of direct binding of an mGlu(5) receptor PAM, this study offers value toward the development of novel PET imaging agents for this important

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

    Directory of Open Access Journals (Sweden)

    Wei Jia

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

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

    Directory of Open Access Journals (Sweden)

    Takayoshi eMasuoka

    2016-03-01

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

  11. Groups II and III metabotropic glutamate receptors differentially modulate brief and prolonged nociception in primate STT cells.

    Science.gov (United States)

    Neugebauer, V; Chen, P S; Willis, W D

    2000-12-01

    The heterogeneous family of G-protein-coupled metabotropic glutamate receptors (mGluRs) provides excitatory and inhibitory controls of synaptic transmission and neuronal excitability in the nervous system. Eight mGluR subtypes have been cloned and are classified in three subgroups. Group I mGluRs can stimulate phosphoinositide hydrolysis and activate protein kinase C whereas group II (mGluR2 and 3) and group III (mGluR4, 6, 7, and 8) mGluRs share the ability to inhibit cAMP formation. The present study examined the roles of groups II and III mGluRs in the processing of brief nociceptive information and capsaicin-induced central sensitization of primate spinothalamic tract (STT) cells in vivo. In 11 anesthetized male monkeys (Macaca fascicularis), extracellular recordings were made from 21 STT cells in the lumbar dorsal horn. Responses to brief (15 s) cutaneous stimuli of innocuous (brush), marginally and distinctly noxious (press and pinch, respectively) intensity were recorded before, during, and after the infusion of group II and group III mGluR agonists into the dorsal horn by microdialysis. Different concentrations were applied for at least 20 min each (at 5 microliter/min) to obtain cumulative concentration-response relationships. Values in this paper refer to the drug concentrations in the microdialysis fibers; actual concentrations in the tissue are about three orders of magnitude lower. The agonists were also applied at 10-25 min after intradermal capsaicin injection. The group II agonists (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine (LCCG1, 1 microM-10 mM, n = 6) and (-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4, 6-dicarboxylate (LY379268; 1 microM-10 mM, n = 6) had no significant effects on the responses to brief cutaneous mechanical stimuli (brush, press, pinch) or on ongoing background activity. In contrast, the group III agonist L(+)-2-amino-4-phosphonobutyric acid (LAP4, 0. 1 microM-10 mM, n = 6) inhibited the responses to cutaneous mechanical stimuli in a

  12. Extinction of a cocaine-taking context that protects against drug-primed reinstatement is dependent on the metabotropic glutamate 5 receptor.

    Science.gov (United States)

    Kim, Jee Hyun; Perry, Christina; Luikinga, Sophia; Zbukvic, Isabel; Brown, Robyn M; Lawrence, Andrew J

    2015-05-01

    We investigated the effects of extinguishing action-reward versus context-reward associations on drug-primed reinstatement, and the potential role of the metabotropic glutamate 5 receptor (mGlu5) in these different types of extinction in rats that self-administer cocaine. We observed that daily context extinction (non-reinforced exposures to the cocaine-taking context with retracted levers) was just as effective as daily lever extinction in reducing cocaine-primed reinstatement compared with passive abstinence. Additionally, systemic injections of the mGlu5 negative allosteric modulator MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine) following each extinction session significantly impaired the ability of context extinction to reduce cocaine-primed reinstatement, without affecting reinstatement after lever extinction or passive abstinence.

  13. Discovery and biological evaluation of tetrahydrothieno[2,3-c]pyridine derivatives as selective metabotropic glutamate receptor 1 antagonists for the potential treatment of neuropathic pain.

    Science.gov (United States)

    Nam, Mina; Kim, TaeHun; Kwak, Jinsook; Seo, Seon Hee; Ko, Min Kyung; Lim, Eun Jeong; Min, Sun-Joon; Cho, Yong Seo; Keum, Gyochang; Baek, Du-Jong; Lee, Jiyoun; Pae, Ae Nim

    2015-06-05

    Metabotropic glutamate receptor 1 (mGluR1) has been a prime target for drug discovery due to its heavy involvement in various brain disorders. Recent studies suggested that mGluR1 is associated with chronic pain and can serve as a promising target for the treatment of neuropathic pain. In an effort to develop a novel mGluR1 antagonist, we designed and synthesized a library of compounds with tetrahydrothieno[2,3-c]pyridine scaffold. Among these compounds, compound 9b and 10b showed excellent antagonistic activity in vitro and demonstrated pain-suppressing activity in animal models of pain. Both compounds were orally active, and compound 9b exhibited a favorable pharmacokinetic profile in rats. We believe that these compounds can provide a promising lead compound that is suitable for the potential treatment of neuropathic pain.

  14. Prenatal valproate treatment produces autistic-like behavior and increases metabotropic glutamate receptor 1A-immunoreactivity in the hippocampus of juvenile rats.

    Science.gov (United States)

    Peralta, Francisco; Fuentealba, Constanza; Fiedler, Jenny; Aliaga, Esteban

    2016-09-01

    Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by deficits in social communication and social interaction, and repetitive and stereotypical patterns of behavior. Previously, a common physiopathological pathway, involving the control of synaptic protein synthesis, was proposed as a convergence point in ASD. In particular, a role for local mRNA translation activated by class I metabotropic glutamate receptor type 5 (mGluR5) was suggested in genetic syndromes with autistic signs and in the prenatal exposition to the valproate model of autism. However, the role of the other members of class I metabotropic glutamate receptors, including mGluR1, has been poorly studied. The present study analyzed the immunoreactivity for mGluR1a in the hippocampus of rats prenatally treated with valproate. Pregnant dams (embryonic day 12.5) were injected with valproate (450 mg/kg) and subsequently, the behavior and mGluR1a were evaluated at postnatal day 30. Experimental rats exhibited social deficit, repetitive conduct and anxious behaviors compared with that of the control animals. Additionally, the present study observed an increased level of mGluR1a-immunoreactivity in the hilus of dentate gyrus and in the CA1 alveus region of the hippocampus. These results suggested an over‑functioning of mGluR1a signaling in the hippocampus, induced in the valproate model of autism, which may serve a role in cognitive and behavioral signs of ASD.

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

    Science.gov (United States)

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

    2014-01-01

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

  16. Intrinsic plasticity induced by group II metabotropic glutamate receptors via enhancement of high-threshold KV currents in sound localizing neurons.

    Science.gov (United States)

    Hamlet, W R; Lu, Y

    2016-06-01

    Intrinsic plasticity has emerged as an important mechanism regulating neuronal excitability and output under physiological and pathological conditions. Here, we report a novel form of intrinsic plasticity. Using perforated patch clamp recordings, we examined the modulatory effects of group II metabotropic glutamate receptors (mGluR II) on voltage-gated potassium (KV) currents and the firing properties of neurons in the chicken nucleus laminaris (NL), the first central auditory station where interaural time cues are analyzed for sound localization. We found that activation of mGluR II by synthetic agonists resulted in a selective increase of the high-threshold KV currents. More importantly, synaptically released glutamate (with reuptake blocked) also enhanced the high-threshold KV currents. The enhancement was frequency-coding region dependent, being more pronounced in low-frequency neurons compared to middle- and high-frequency neurons. The intracellular mechanism involved the Gβγ signaling pathway associated with phospholipase C and protein kinase C. The modulation strengthened membrane outward rectification, sharpened action potentials, and improved the ability of NL neurons to follow high-frequency inputs. These data suggest that mGluR II provides a feedforward modulatory mechanism that may regulate temporal processing under the condition of heightened synaptic inputs.

  17. The metabotropic glutamate receptor subtype 7 rs3792452 polymorphism is associated with the response to methylphenidate in children with attention-deficit/hyperactivity disorder.

    Science.gov (United States)

    Park, Subin; Kim, Bung-Nyun; Cho, Soo-Churl; Kim, Jae-Won; Kim, Johanna Inhyang; Shin, Min-Sup; Yoo, Hee-Jeong; Han, Doug Hyun; Cheong, Jae Hoon

    2014-05-01

    The purpose of this study was to investigate the association between the metabotropic glutamate receptor subtype 7 (mGluR7) gene (GRM7) polymorphism and treatment response to methylphenidate in Korean children with attention-deficit/hyperactivity disorder (ADHD). We enrolled 175 medication-naïve children with ADHD in an open-label 8 week trial of methylphenidate. The participants were genotyped and evaluated using the Clinical Global Impressions (CGI) Scale and the parent version of the ADHD Rating Scale-IV (ADHD-RS) before and after treatment. After the 8 week course of methylphenidate, children with the GRM7 rs37952452 polymorphism G/A genotype had a more pronounced response rate to the treatment than did children with the G/G genotype according to the ADHD-RS scores (72.2% vs. 55.4%, respectively; p=0.011) and the more stringent standard of combined ADHD-RS and CGI-Improvement (CGI-I) scores (50.0% vs. 35.3%, respectively; p=0.044). The present study suggests that the GRM7 rs37952452 polymorphism may play a role in the treatment response to methylphenidate in children with ADHD. Further studies to evaluate the association between glutamate genes and treatment response to methylphenidate in children with ADHD, including a replication of our findings using a control or comparative group in a larger sample, are warranted.

  18. Effects of a metabotropic glutamate receptor subtype 7 negative allosteric modulator in the periaqueductal grey on pain responses and rostral ventromedial medulla cell activity in rat.

    Science.gov (United States)

    Palazzo, Enza; Marabese, Ida; Luongo, Livio; Boccella, Serena; Bellini, Giulia; Giordano, Maria Elvira; Rossi, Francesca; Scafuro, Mariantonietta; Novellis, Vito de; Maione, Sabatino

    2013-09-03

    The metabotropic glutamate receptor 7 (mGluR7) negative allosteric modulator, 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP), was locally microinjected into the ventrolateral periaqueductal gray (VL PAG) and the effect on pain responses in formalin and spare nerve injury (SNI) -induced neuropathic pain models was monitored in the rat. The activity of rostral ventromedial medulla (RVM) "pronociceptive" ON and "antinociceptive" OFF cells was also evaluated. Intra-VL PAG MMPIP blocked the first and second phase of nocifensive behaviour in the formalin pain model. MMPIP increased the tail flick latency and simultaneously increased the activity of the OFF cells while inhibiting that of ON cells in rats with SNI of the sciatic nerve. MMPIP failed to modify nociceptive responses and associated RVM ON and OFF cell activity in sham rats. An increase in mGluR7 gene, protein and staining, the latter being associated with vesicular glutamate transporter-positive profiles, has been found in the VL PAG in SNI rats. Blockade of mGluR7 within the VL PAG has an antinociceptive effect in formalin and neuropathic pain models. VL PAG mGluR7 blockade offers a target for dis-inhibiting the VL PAG-RVM pathway and silencing pain in inflammatory and neuropathic pain models.

  19. Functional impact of allosteric agonist activity of selective positive allosteric modulators of metabotropic glutamate receptor subtype 5 in regulating central nervous system function.

    Science.gov (United States)

    Noetzel, Meredith J; Rook, Jerri M; Vinson, Paige N; Cho, Hyekyung P; Days, Emily; Zhou, Y; Rodriguez, Alice L; Lavreysen, Hilde; Stauffer, Shaun R; Niswender, Colleen M; Xiang, Zixiu; Daniels, J Scott; Jones, Carrie K; Lindsley, Craig W; Weaver, C David; Conn, P Jeffrey

    2012-02-01

    Positive allosteric modulators (PAMs) of metabotropic glutamate receptor subtype 5 (mGlu(5)) have emerged as an exciting new approach for the treatment of schizophrenia and other central nervous system (CNS) disorders. Of interest, some mGlu(5) PAMs act as pure PAMs, only potentiating mGlu(5) responses to glutamate whereas others [allosteric agonists coupled with PAM activity (ago-PAMs)] potentiate responses to glutamate and have intrinsic allosteric agonist activity in mGlu(5)-expressing cell lines. All mGlu(5) PAMs previously shown to have efficacy in animal models act as ago-PAMs in cell lines, raising the possibility that allosteric agonist activity is critical for in vivo efficacy. We have now optimized novel mGlu(5) pure PAMs that are devoid of detectable agonist activity and structurally related mGlu(5) ago-PAMs that activate mGlu(5) alone in cell lines. Studies of mGlu(5) PAMs in cell lines revealed that ago-PAM activity is dependent on levels of mGlu(5) receptor expression in human embryonic kidney 293 cells, whereas PAM potency is relatively unaffected by levels of receptor expression. Furthermore, ago-PAMs have no agonist activity in the native systems tested, including cortical astrocytes and subthalamic nucleus neurons and in measures of long-term depression at the hippocampal Schaffer collateral-CA1 synapse. Finally, studies with pure PAMs and ago-PAMs chemically optimized to provide comparable CNS exposure revealed that both classes of mGlu(5) PAMs have similar efficacy in a rodent model predictive of antipsychotic activity. These data suggest that the level of receptor expression influences the ability of mGlu(5) PAMs to act as allosteric agonists in vitro and that ago-PAM activity observed in cell-based assays may not be important for in vivo efficacy.

  20. Modulation of glutamatergic transmission by metabotropic glutamate receptor activation in second-order neurons of the guinea pig nucleus tractus solitarius.

    Science.gov (United States)

    Ohi, Yoshiaki; Kimura, Satoko; Haji, Akira

    2014-09-18

    Activity of second-order relay neurons in the nucleus tractus solitarius (NTS) is regulated by peripheral and intrinsic synaptic inputs, and modulation of those inputs by metabotropic glutamate receptors (mGluRs) has been proposed. This study investigated effects of mGluR activation on glutamatergic transmission in the NTS second-order neurons of guinea pigs. Whole-cell patch-clamp recordings from the brainstem slices revealed that activation of mGluRs exerted its effects on the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) but not on the amplitude. The sEPSC frequency was increased by an agonist of group I mGluRs, and it was decreased by an mGluR1 antagonist but not by an mGluR5 antagonist. The agonists of group II and III mGluRs decreased the sEPSC frequency, while their antagonists alone had no effect. Perfusion of cystine or TBOA, either of which elevates extracellular glutamate concentration, resulted in an increase in the sEPSC frequency, leaving the amplitude unchanged. The increased frequency of sEPSCs was returned to control by an mGluR1 antagonist. The tractus solitarius-evoked EPSCs were not altered by an agonist of group I mGluRs, whereas they were decreased along with an increase in paired-pulse ratio by agonists of group II and III mGluRs. These results suggest that mGluRs are present at the presynaptic sites in the NTS second-order neurons in guinea pigs. The mGluR1s function to facilitate the release of glutamate from axon terminals of intrinsic interneurons and the group II and III mGluRs play an inhibitory role in glutamatergic transmission.

  1. Metabotropic glutamate 2/3 receptor antagonists improve behavioral and prefrontal dopaminergic alterations in the chronic corticosterone-induced depression model in mice.

    Science.gov (United States)

    Ago, Yukio; Yano, Koji; Araki, Ryota; Hiramatsu, Naoki; Kita, Yuki; Kawasaki, Toshiyuki; Onoe, Hirotaka; Chaki, Shigeyuki; Nakazato, Atsuro; Hashimoto, Hitoshi; Baba, Akemichi; Takuma, Kazuhiro; Matsuda, Toshio

    2013-02-01

    Metabotropic glutamate 2/3 (mGlu2/3) receptor antagonists have an antidepressant-like effect, but the exact mechanism still remains unclear. This study examined the effects of mGlu2/3 receptor antagonists in chronic corticosterone-treated mice which could be used as an animal model of depression. In the forced swim test, the mGlu2/3 receptor antagonists MGS0039 (1.0 mg/kg, i.p.) and LY341495 (0.3 mg/kg, i.p) significantly reduced the increased immobility time of mice pretreated with corticosterone (20 mg/kg, s.c.) for 21 days, while desipramine (30 mg/kg, i.p.) and fluoxetine (30 mg/kg, i.p.) did not. The antidepressant-like effect of LY341495 was not blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonist NBQX (10 mg/kg, i.p.). Systemic administration of LY341495 did not affect basal release of glutamate, dopamine or serotonin in the prefrontal cortex of the control or chronic corticosterone-treated mice. Chronic corticosterone markedly enhanced high K(+)-induced release of dopamine, but not serotonin or glutamate, in the prefrontal cortex. This neurochemical change was blocked by systemic administration of MGS0039 and LY341495, but not desipramine or fluoxetine. These results suggest that chronic corticosterone-treated mice could be used as an animal model of treatment-resistant depression. This study also suggests that the prefrontal dopaminergic system is involved in the antidepressant-like effect of mGlu2/3 receptor antagonists in the chronic corticosterone-induced depression model.

  2. Expression of metabotropic glutamate receptor 1a in a rat cortical neuronal model of in vitro mechanical injury and the effects of its competitive antagonist (RS)-1-aminoindan-1, 5-dicarboxylic acid

    Institute of Scientific and Technical Information of China (English)

    Fei Cao; Mantao Chen; Xiujue Zheng; Gu Li; Liang Wen; Xiaofeng Yang

    2011-01-01

    The present study established a rat cortical neuronal model of in vitro mechanical injury. At 30 min-utes after injury, the survival rate of the injured cortical neurons was decreased compared with normal neurons, and was gradually decreased with aggravated degree of injury. Reverse transcrip-tion-polymerase chain reaction results showed that at 1 hour after injury, there was increased ex-pression of metabotropic glutamate receptor 1a in cortical neurons. Immunohistochemical staining results showed that at 30 minutes after injury, the number of metabotropic glutamate receptor 1a-positive cells increased compared with normal neurons. At 12 hours after injury, lactate dehy-drogenase activity in the (RS)-1-aminoindan-1, 5-dicarboxylic acid (AIDA)-treated injury neurons was significantly decreased than that in the pure injury group. At 1 hour after injury, intracellular free Ca2+ concentration was markedly decreased in the AIDA-treated injury neurons than that in the pure injury neurons. These findings suggest that after mechanical injury to cortical neurons, metabotropic glutamate receptor 1a expression increased. The resulting increase in intracellular free Ca2+ con-centration was blocked by AIDA, indicating that AIDA exhibits neuroprotective effects after me-chanical injury.

  3. Pharmacological activation of group-II metabotropic glutamate receptors corrects a schizophrenia-like phenotype induced by prenatal stress in mice.

    Science.gov (United States)

    Matrisciano, Francesco; Tueting, Patricia; Maccari, Stefania; Nicoletti, Ferdinando; Guidotti, Alessandro

    2012-03-01

    Prenatal exposure to restraint stress causes long-lasting changes in neuroplasticity that likely reflect pathological modifications triggered by early-life stress. We found that the offspring of dams exposed to repeated episodes of restraint stress during pregnancy (here named 'prenatal restraint stress mice' or 'PRS mice') developed a schizophrenia-like phenotype, characterized by a decreased expression of brain-derived neurotrophic factor and glutamic acid decarboxylase 67, an increased expression of type-1 DNA methyl transferase (DNMT1) in the frontal cortex, and a deficit in social interaction, locomotor activity, and prepulse inhibition. PRS mice also showed a marked decrease in metabotropic glutamate 2 (mGlu2) and mGlu3 receptor mRNA and protein levels in the frontal cortex, which was manifested at birth and persisted in adult life. This decrease was associated with an increased binding of DNMT1 to CpG-rich regions of mGlu2 and mGlu3 receptor promoters and an increased binding of MeCP2 to the mGlu2 receptor promoter. Systemic treatment with the selective mGlu2/3 receptor agonist LY379268 (0.5 mg/kg, i.p., twice daily for 5 days), corrected all the biochemical and behavioral abnormalities shown in PRS mice. Our data show for the first time that PRS induces a schizophrenia-like phenotype in mice, and suggest that epigenetic changes in mGlu2 and mGlu3 receptors lie at the core of the pathological programming induced by early-life stress.

  4. Genomic structure of metabotropic glutamate receptor 7 and comparison of genomic structures of extracellular domains of mGluR family

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Metabotropic glutamate receptor 7, coupled with a chemical neurotransmitter L-glutamate, plays an important role in the development of many psychiatric and neurological disorders. To study the biological and genetic mechanism of the mGluR7-related diseases, a physical map covering the full-length mGluR7 genomic sequence has been constructed through seed clone screening and fingerprinting database searching. These BAC clones in the physical map have been sequenced with shotgun strategy and assembled by Phred-Phrap-Consed software; the error rate of the final genomic sequence is less than 0.01%. mGluR7 spans 880 kb genomic region, the GC content and repeat content of mGluR7 genomic sequence are 38% and 37.5% respectively. mGluR7 has a typical "house-keeping" promoter and consists of 11 exons, with introns ranging from 6 kb to 285 kb. mGluR7a and mGluR7b are two known alternatively splicing variants. Comparing the genomic structures of extracellular domains of mGluR family, their genomic structures can be subdivided into three groups, which are consistent with that of proteins. Although the genomic organization of mGluR7's group is conserved, the majority of introns in the extracellular segments vary dramatically. It is an obvious trend of the increasing intron size inverse proportion to phylogenetic time. Variation of genomic structure is higher than that of protein, which is attributed to the species characteristic regulation of gene expression.

  5. Metabotropic glutamate receptor 1 mediates the electrophysiological and toxic actions of the cycad derivative beta-N-Methylamino-L-alanine on substantia nigra pars compacta DAergic neurons.

    Science.gov (United States)

    Cucchiaroni, Maria Letizia; Viscomi, Maria Teresa; Bernardi, Giorgio; Molinari, Marco; Guatteo, Ezia; Mercuri, Nicola B

    2010-04-14

    Amyotrophic lateral sclerosis-Parkinson dementia complex (ALS-PDC) is a neurodegenerative disease with ALS, parkinsonism, and Alzheimer's symptoms that is prevalent in the Guam population. beta-N-Methylamino alanine (BMAA) has been proposed as the toxic agent damaging several neuronal types in ALS-PDC, including substantia nigra pars compacta dopaminergic (SNpc DAergic) neurons. BMAA is a mixed glutamate receptor agonist, but the specific pathways activated in DAergic neurons are not yet known. We combined electrophysiology, microfluorometry, and confocal microscopy analysis to monitor membrane potential/current, cytosolic calcium concentration ([Ca(2+)](i)) changes, cytochrome-c (cyt-c) immunoreactivity, and reactive oxygen species (ROS) production induced by BMAA. Rapid toxin applications caused reversible membrane depolarization/inward current and increase of firing rate and [Ca(2+)](i) in DAergic neurons. The inward current (I(BMAA)) was mainly mediated by activation of metabotropic glutamate receptor 1 (mGluR1), coupled to transient receptor potential (TRP) channels, and to a lesser extent, AMPA receptors. Indeed, mGluR1 (CPCCOEt) and TRP channels (SKF 96365; Ruthenium Red) antagonists reduced I(BMAA), and a small component of I(BMAA) was reduced by the AMPA receptor antagonist CNQX. Calcium accumulation was mediated by mGluR1 but not by AMPA receptors. Application of a low concentration of NMDA potentiated the BMAA-mediated calcium increase. Prolonged exposure to BMAA caused significant modifications of membrane properties, calcium overload, cell shrinkage, massive cyt-c release into the cytosol and ROS production. In SNpc GABAergic neurons, BMAA activated only AMPA receptors. Our study identifies the mGluR1-activated mechanism induced by BMAA that may cause the neuronal degeneration and parkinsonian symptoms seen in ALS-PDC. Moreover, environmental exposure to BMAA might possibly also contribute to idiopathic PD.

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

    Directory of Open Access Journals (Sweden)

    Richard M. Cleva

    2011-03-01

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

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

    DEFF Research Database (Denmark)

    Jørgensen, Christinna V; Klein, Anders B; El-Sayed, Mona;

    2013-01-01

    Brain-derived neurotrophic factor (BDNF) is important for neuronal survival and plasticity. Incorporation of matured receptor proteins is an integral part of synapse formation. However, whether BDNF increases synthesis and integration of receptors in functional synapses directly is unclear. We...... 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...

  8. β-Arrestin2 Couples Metabotropic Glutamate Receptor 5 to Neuronal Protein Synthesis and Is a Potential Target to Treat Fragile X

    Directory of Open Access Journals (Sweden)

    Laura J. Stoppel

    2017-03-01

    Full Text Available Synaptic protein synthesis is essential for modification of the brain by experience and is aberrant in several genetically defined disorders, notably fragile X (FX, a heritable cause of autism and intellectual disability. Neural activity directs local protein synthesis via activation of metabotropic glutamate receptor 5 (mGlu5, yet how mGlu5 couples to the intracellular signaling pathways that regulate mRNA translation is poorly understood. Here, we provide evidence that β-arrestin2 mediates mGlu5-stimulated protein synthesis in the hippocampus and show that genetic reduction of β-arrestin2 corrects aberrant synaptic plasticity and cognition in the Fmr1−/y mouse model of FX. Importantly, reducing β-arrestin2 does not induce psychotomimetic activity associated with full mGlu5 inhibitors and does not affect Gq signaling. Thus, in addition to identifying a key requirement for mGlu5-stimulated protein synthesis, these data suggest that β-arrestin2-biased negative modulators of mGlu5 offer significant advantages over first-generation inhibitors for the treatment of FX and related disorders.

  9. Insights into the interaction of negative allosteric modulators with the metabotropic glutamate receptor 5: discovery and computational modeling of a new series of ligands with nanomolar affinity.

    Science.gov (United States)

    Anighoro, Andrew; Graziani, Davide; Bettinelli, Ilaria; Cilia, Antonio; De Toma, Carlo; Longhi, Matteo; Mangiarotti, Fabio; Menegon, Sergio; Pirona, Lorenza; Poggesi, Elena; Riva, Carlo; Rastelli, Giulio

    2015-07-01

    Metabotropic glutamate receptor 5 (mGlu5) is a biological target implicated in major neurological and psychiatric disorders. In the present study, we have investigated structural determinants of the interaction of negative allosteric modulators (NAMs) with the seven-transmembrane (7TM) domain of mGlu5. A homology model of the 7TM receptor domain built on the crystal structure of the mGlu1 template was obtained, and the binding modes of known NAMs, namely MPEP and fenobam, were investigated by docking and molecular dynamics simulations. The results were validated by comparison with mutagenesis data available in the literature for these two ligands, and subsequently corroborated by the recently described mGlu5 crystal structure. Moreover, a new series of NAMs was synthesized and tested, providing compounds with nanomolar affinity. Several structural modifications were sequentially introduced with the aim of identifying structural features important for receptor binding. The synthesized NAMs were docked in the validated homology model and binding modes were used to interpret and discuss structure-activity relationships within this new series of compounds. Finally, the models of the interaction of NAMs with mGlu5 were extended to include important non-aryl alkyne mGlu5 NAMs taken from the literature. Overall, the results provide useful insights into the molecular interaction of negative allosteric modulators with mGlu5 and may facilitate the design of new modulators for this class of receptors.

  10. The group I metabotropic glutamate receptor mGluR5 is required for fear memory formation and long-term potentiation in the lateral amygdala.

    Science.gov (United States)

    Rodrigues, Sarina M; Bauer, Elizabeth P; Farb, Claudia R; Schafe, Glenn E; LeDoux, Joseph E

    2002-06-15

    The group I metabotropic glutamate receptor subtype mGluR5 has been shown to play a key role in the modulation of synaptic plasticity. The present experiments examined the function of mGluR5 in the circuitry underlying Pavlovian fear conditioning using neuroanatomical, electrophysiological, and behavioral techniques. First, we show using immunocytochemical and tract-tracing methods that mGluR5 is localized to dendritic shafts and spines in the lateral nucleus of the amygdala (LA) and is postsynaptic to auditory thalamic inputs. In electrophysiological experiments, we show that long-term potentiation at thalamic input synapses to the LA is impaired by bath application of a specific mGluR5 antagonist, 2-methyl-6-(phenyle-thynyl)-pyridine (MPEP), in vitro. Finally, we show that intra-amygdala administration of MPEP dose-dependently impairs the acquisition, but not expression or consolidation, of auditory and contextual fear conditioning. Collectively, the results of this study indicate that mGluR5 in the LA plays a crucial role in fear conditioning and in plasticity at synapses involved in fear conditioning.

  11. Activation of metabotropic glutamate 5 and NMDA receptors underlies the induction of persistent bursting and associated long-lasting changes in CA3 recurrent connections.

    Science.gov (United States)

    Stoop, Ron; Conquet, François; Zuber, Benoit; Voronin, Leon L; Pralong, Etienne

    2003-07-02

    The aim of this study was to describe the induction and expression mechanisms of a persistent bursting activity in a horizontal slice preparation of the rat limbic system that includes the ventral part of the hippocampus and the entorhinal cortex. Disinhibition of this preparation by bicuculline led to interictal-like bursts in the CA3 region that triggered synchronous activity in the entorhinal cortex. Washout of bicuculline after a 1 hr application resulted in a maintained production of hippocampal bursts that continued to spread to the entorhinal cortex. Separation of CA3 from the entorhinal cortex caused the activity in the latter to become asynchronous with CA3 activity in the presence of bicuculline and disappear after washout; however, in CA3, neither the induction of bursting nor its persistence were affected. Associated with the CA3 persistent bursting, a strengthening of recurrent collateral excitatory input to CA3 pyramidal cells and a decreased input to CA3 interneurons was found. Both the induction of the persistent bursting and the changes in synaptic strength were prevented by antagonists of metabotropic glutamate 5 (mGlu5) or NMDA receptors or protein synthesis inhibitors and did not occur in slices from mGlu5 receptor knock-out mice. The above findings suggest potential synaptic mechanisms by which the hippocampus switches to a persistent interictal bursting mode that may support a spread of interictal-like bursting to surrounding temporal lobe regions.

  12. Biodistribution and radiation dosimetry of a positron emission tomographic ligand, {sup 18}F-SP203, to image metabotropic glutamate subtype 5 receptors in humans

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Yasuyuki; Simeon, Fabrice G.; Pike, Victor W.; Innis, Robert B.; Fujita, Masahiro [National Institute of Mental Health, Molecular Imaging Branch, Bethesda, MD (United States); Hatazawa, Jun [Osaka University Graduate School of Medicine, Department of Nuclear Medicine and Tracer Kinetics, Suita, Osaka (Japan); Mozley, P.D. [Merck Research Laboratories, West Point, PA (United States)

    2010-10-15

    A new PET ligand, 3-fluoro-5-(2-(2-{sup 18}F-(fluoromethyl)-thiazol-4-yl)ethynyl)benzonitrile ({sup 18}F-SP203), is a positron emission tomographic radioligand selective for metabotropic glutamate subtype 5 receptors. The purposes of this study were to estimate the radiation-absorbed doses of {sup 18}F-SP203 in humans and to determine from the distribution of radioactivity in bone structures with various proportions of bone and red marrow whether {sup 18}F-SP203 undergoes defluorination. Whole-body images were acquired for 5 h after injecting {sup 18}F-SP203 in seven healthy humans. Urine was collected at various time points. Radiation-absorbed doses were estimated by the Medical Internal Radiation Dose scheme. After injecting {sup 18}F-SP203, the two organs with highest radiation exposure were urinary bladder wall and gallbladder wall, consistent with both urinary and fecal excretion. In the skeleton, most of the radioactivity was in bone structures that contain red marrow and not in those without red marrow. Although the dose to red marrow (30.9 {mu}Sv/MBq) was unusually high, the effective dose (17.8 {mu}Sv/MBq) of {sup 18}F-SP203 was typical of that of other {sup 18}F radiotracers. {sup 18}F-SP203 causes an effective dose in humans typical of several other {sup 18}F radioligands and undergoes little defluorination. (orig.)

  13. Differential regulation of voltage-gated Ca2+ currents and metabotropic glutamate receptor activity by measles virus infection in rat cortical neurons.

    Science.gov (United States)

    Günther, Christine; Laube, Mandy; Liebert, Uwe-Gerd; Kraft, Robert

    2012-01-06

    Measles virus (MV) infection may lead to severe chronic CNS disease processes, including MV-induced encephalitis. Because the intracellular Ca(2+) concentration ([Ca(2+)](i)) is a major determinant of the (patho-)physiological state in all cells we asked whether important Ca(2+) conducting pathways are affected by MV infection in cultured cortical rat neurons. Patch-clamp measurements revealed a decrease in voltage-gated Ca(2+) currents during MV-infection, while voltage-gated K(+) currents and NMDA-evoked currents were unaffected. Calcium-imaging experiments using 50mM extracellular KCl showed reduced [Ca(2+)](i) increases in MV-infected neurons, confirming a decreased activity of voltage-gated Ca(2+) channels. In contrast, the group-I metabotropic glutamate receptor (mGluR) agonist DHPG evoked changes in [Ca(2+)](i) that were increased in MV-infected cells. Our results show that MV infection conversely regulates Ca(2+) signals induced by group-I mGluRs and by voltage-gated Ca(2+) channels, suggesting that these physiological impairments may contribute to an altered function of cortical neurons during MV-induced encephalitis.

  14. Deletion of Metabotropic Glutamate Receptors 2 and 3 (mGlu2 & mGlu3 in Mice Disrupts Sleep and Wheel-Running Activity, and Increases the Sensitivity of the Circadian System to Light.

    Directory of Open Access Journals (Sweden)

    David Pritchett

    Full Text Available Sleep and/or circadian rhythm disruption (SCRD is seen in up to 80% of schizophrenia patients. The co-morbidity of schizophrenia and SCRD may in part stem from dysfunction in common brain mechanisms, which include the glutamate system, and in particular, the group II metabotropic glutamate receptors mGlu2 and mGlu3 (encoded by the genes Grm2 and Grm3. These receptors are relevant to the pathophysiology and potential treatment of schizophrenia, and have also been implicated in sleep and circadian function. In the present study, we characterised the sleep and circadian rhythms of Grm2/3 double knockout (Grm2/3-/- mice, to provide further evidence for the involvement of group II metabotropic glutamate receptors in the regulation of sleep and circadian rhythms. We report several novel findings. Firstly, Grm2/3-/- mice demonstrated a decrease in immobility-determined sleep time and an increase in immobility-determined sleep fragmentation. Secondly, Grm2/3-/- mice showed heightened sensitivity to the circadian effects of light, manifested as increased period lengthening in constant light, and greater phase delays in response to nocturnal light pulses. Greater light-induced phase delays were also exhibited by wildtype C57Bl/6J mice following administration of the mGlu2/3 negative allosteric modulator RO4432717. These results confirm the involvement of group II metabotropic glutamate receptors in photic entrainment and sleep regulation pathways. Finally, the diurnal wheel-running rhythms of Grm2/3-/- mice were perturbed under a standard light/dark cycle, but their diurnal rest-activity rhythms were unaltered in cages lacking running wheels, as determined with passive infrared motion detectors. Hence, when assessing the diurnal rest-activity rhythms of mice, the choice of assay can have a major bearing on the results obtained.

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

    DEFF Research Database (Denmark)

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

    1997-01-01

    chiral HPLC. The configurational assignments of 6 and 7 were based on 1H NMR spectroscopic studies on 12 and 11, respectively, and circular dichroism studies on 6 and 7. Values of optical rotations using different solvents and the chiral HPLC elution order of 6 and 7 supported the results...... of the spectroscopic configurational assignments. The activities of 6 and 7 at ionotropic EAA (iGlu) receptors and at mGlu1-7 were studied. (S)-Homo-AMPA (6) was shown to be a specific agonist at mGlu6 (EC50 = 58 +/- 11 microM) comparable in potency with the endogenous mGlu agonist (S)-glutamic acid (EC50 = 20 +/- 3...

  16. The metabotropic glutamate receptor, mGlu5, is required for extinction learning that occurs in the absence of a context change.

    Science.gov (United States)

    André, Marion Agnes Emma; Güntürkün, Onur; Manahan-Vaughan, Denise

    2015-02-01

    The metabotropic glutamate (mGlu) receptors and, in particular, mGlu5 are crucially involved in multiple forms of synaptic plasticity that are believed to underlie explicit memory. MGlu5 is also required for information transfer through neuronal oscillations and for spatial memory. Furthermore, mGlu5 is involved in extinction of implicit forms of learning. This places this receptor in a unique position with regard to information encoding. Here, we explored the role of this receptor in context-dependent extinction learning under constant, or changed, contextual conditions. Animals were trained over 3 days to take a left turn under 25% reward probability in a T-maze with a distinct floor pattern (Context A). On Day 4, they experienced either a floor pattern change (Context B) or the same floor pattern (Context A) in the absence of reward. After acquisition of the task, the animals were returned to the maze once more on Day 5 (Context A, no reward). Treatment with the mGlu5 antagonist, 2-methyl-6-(phenylethynyl) pyridine, before maze exposure on Day 4 completely inhibited extinction learning in the AAA paradigm but had no effect in the ABA paradigm. A subsequent return to the original context (A, on Day 5) revealed successful extinction in the AAA paradigm, but impairment of extinction in the ABA paradigm. These data support that although extinction learning in a new context is unaffected by mGlu5 antagonism, extinction of the consolidated context is impaired. This suggests that mGlu5 is intrinsically involved in enabling learning that once-relevant information is no longer valid.

  17. The Metabotropic Glutamate Receptor, mGlu5, Is Required for Extinction Learning That Occurs in the Absence of a Context Change

    Science.gov (United States)

    André, Marion Agnes Emma; Güntürkün, Onur; Manahan-Vaughan, Denise

    2015-01-01

    The metabotropic glutamate (mGlu) receptors and, in particular, mGlu5 are crucially involved in multiple forms of synaptic plasticity that are believed to underlie explicit memory. MGlu5 is also required for information transfer through neuronal oscillations and for spatial memory. Furthermore, mGlu5 is involved in extinction of implicit forms of learning. This places this receptor in a unique position with regard to information encoding. Here, we explored the role of this receptor in context-dependent extinction learning under constant, or changed, contextual conditions. Animals were trained over 3 days to take a left turn under 25% reward probability in a T-maze with a distinct floor pattern (Context A). On Day 4, they experienced either a floor pattern change (Context B) or the same floor pattern (Context A) in the absence of reward. After acquisition of the task, the animals were returned to the maze once more on Day 5 (Context A, no reward). Treatment with the mGlu5 antagonist, 2-methyl-6-(phenylethynyl) pyridine, before maze exposure on Day 4 completely inhibited extinction learning in the AAA paradigm but had no effect in the ABA paradigm. A subsequent return to the original context (A, on Day 5) revealed successful extinction in the AAA paradigm, but impairment of extinction in the ABA paradigm. These data support that although extinction learning in a new context is unaffected by mGlu5 antagonism, extinction of the consolidated context is impaired. This suggests that mGlu5 is intrinsically involved in enabling learning that once-relevant information is no longer valid. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc. PMID:25160592

  18. Pretreatment with group I metabotropic glutamate receptors antagonists attenuates lethality induced by acute cocaine overdose and expression of sensitization to hyperlocomotor effect of cocaine in mice.

    Science.gov (United States)

    Kotlinska, Jolanta; Bochenski, Marcin

    2011-01-01

    Cocaine abuse and dependence is a worldwide health problem. However, there are no currently approved medications to reduce cocaine abuse/relapse and toxicity. The aim of the present study was to test, whether group I metabotropic glutamate receptors (mGluRs) antagonists (mGluR1 and mGluR5) differentially regulate toxic versus behavioral effects of cocaine, both phenomena relevant to the psychopathology of cocaine addiction in humans. In the present study, we assessed the impact of mGluR1 antagonist-EMQMCM and mGluR5 antagonist-MTEP on the cocaine-induced lethality and the expression of sensitization to hyperlocomotor effect of cocaine in mice. Our study indicated that EMQMCM and MTEP, both substances at the doses of 5 and 10 mg/kg (but not 2.5 mg/kg), decreased cocaine-induced lethality produced by 75 mg/kg of cocaine, which was given acutely. The effect of EMQMCM was dose-dependent, and this compound at the dose of 10 mg/kg almost completely abolished the lethality induced by cocaine. MTEP reduced this cocaine effect at the doses of 5 and 10 mg/kg, equally. Furthermore, EMQMCM (1.25-5 mg/kg) at the doses of 2.5 and 5.0 mg/kg, and MTEP (2.5-10 mg/kg) only at the highest dose of 10 mg/kg, significantly reduced the expression of cocaine-induced (10 mg/kg) behavioral sensitization. Our results suggest that stimulation of mGluR1 and mGluR5 is involved in lethal effect of cocaine overdose and cocaine seeking behavior evaluated in behavioral sensitization test. However, the participation of mGluR1 in these cocaine effects seems to be dominant. Therefore, antagonists showing preferences towards mGluR1 might be useful in therapy of cocaine toxicity and abuse.

  19. Blocking metabotropic glutamate receptor subtype 7 (mGlu7) via the Venus flytrap domain (VFTD) inhibits amygdala plasticity, stress, and anxiety-related behavior.

    Science.gov (United States)

    Gee, Christine E; Peterlik, Daniel; Neuhäuser, Christoph; Bouhelal, Rochdi; Kaupmann, Klemens; Laue, Grit; Uschold-Schmidt, Nicole; Feuerbach, Dominik; Zimmermann, Kaspar; Ofner, Silvio; Cryan, John F; van der Putten, Herman; Fendt, Markus; Vranesic, Ivo; Glatthar, Ralf; Flor, Peter J

    2014-04-18

    The metabotropic glutamate receptor subtype 7 (mGlu7) is an important presynaptic regulator of neurotransmission in the mammalian CNS. mGlu7 function has been linked to autism, drug abuse, anxiety, and depression. Despite this, it has been difficult to develop specific blockers of native mGlu7 signaling in relevant brain areas such as amygdala and limbic cortex. Here, we present the mGlu7-selective antagonist 7-hydroxy-3-(4-iodophenoxy)-4H-chromen-4-one (XAP044), which inhibits lateral amygdala long term potentiation (LTP) in brain slices from wild type mice with a half-maximal blockade at 88 nm. There was no effect of XAP044 on LTP of mGlu7-deficient mice, indicating that this pharmacological effect is mGlu7-dependent. Unexpectedly and in contrast to all previous mGlu7-selective drugs, XAP044 does not act via the seven-transmembrane region but rather via a binding pocket localized in mGlu7's extracellular Venus flytrap domain, a region generally known for orthosteric agonist binding. This was shown by chimeric receptor studies in recombinant cell line assays. XAP044 demonstrates good brain exposure and wide spectrum anti-stress and antidepressant- and anxiolytic-like efficacy in rodent behavioral paradigms. XAP044 reduces freezing during acquisition of Pavlovian fear and reduces innate anxiety, which is consistent with the phenotypes of mGlu7-deficient mice, the results of mGlu7 siRNA knockdown studies, and the inhibition of amygdala LTP by XAP044. Thus, we present an mGlu7 antagonist with a novel molecular mode of pharmacological action, providing significant application potential in psychiatry. Modeling the selective interaction between XAP044 and mGlu7's Venus flytrap domain, whose three-dimensional structure is already known, will facilitate future drug development supported by computer-assisted drug design.

  20. Metabotropic glutamate receptor I (mGluR1) antagonism impairs cocaine-induced conditioned place preference via inhibition of protein synthesis.

    Science.gov (United States)

    Yu, Fei; Zhong, Peng; Liu, Xiaojie; Sun, Dalong; Gao, Hai-Qing; Liu, Qing-Song

    2013-06-01

    Antagonism of group I metabotropic glutamate receptors (mGluR1 and mGluR5) reduces behavioral effects of drugs of abuse, including cocaine. However, the underlying mechanisms remain poorly understood. Activation of mGluR5 increases protein synthesis at synapses. Although mGluR5-induced excessive protein synthesis has been implicated in the pathology of fragile X syndrome, it remains unknown whether group I mGluR-mediated protein synthesis is involved in any behavioral effects of drugs of abuse. We report that group I mGluR agonist DHPG induced more pronounced initial depression of inhibitory postsynaptic currents (IPSCs) followed by modest long-term depression (I-LTD) in dopamine neurons of rat ventral tegmental area (VTA) through the activation of mGluR1. The early component of DHPG-induced depression of IPSCs was mediated by the cannabinoid CB1 receptors, while DHPG-induced I-LTD was dependent on protein synthesis. Western blotting analysis indicates that mGluR1 was coupled to extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR) signaling pathways to increase translation. We also show that cocaine conditioning activated translation machinery in the VTA via an mGluR1-dependent mechanism. Furthermore, intra-VTA microinjections of mGluR1 antagonist JNJ16259685 and protein synthesis inhibitor cycloheximide significantly attenuated or blocked the acquisition of cocaine-induced conditioned place preference (CPP) and activation of translation elongation factors. Taken together, these results suggest that mGluR1 antagonism inhibits de novo protein synthesis; this effect may block the formation of cocaine-cue associations and thus provide a mechanism for the reduction in CPP to cocaine.

  1. Changes of metabotropic glutamate receptor subtype 1a in diffuse brain injury with secondary brain insults and the effects of 2-methyl-4-carboxyphenylglycine

    Institute of Scientific and Technical Information of China (English)

    FEI Zhou 费舟; ZHANG Xiang 章翔; LIU En-yu 刘恩渝

    2003-01-01

    Objective: To observe the changes of metabotropic glutamate receptor 1a in rat brain in a rodent model of diffuse head injury with secondary insults and the effects of 2-methyl-4-carboxyphenylglycine (MCPG).Methods: Based on Marmarous rodent model of diffuse brain injury (DBI), hypotension was made by blood withdrawal as secondary brain insults (SBI).105 male SD rats were randomized into A and B groups.The changes of mGluR1a in cerebral cortex were studied by immunohistochemistry and the effect of MCPG by HE.Each group was divided into different subgroups at different time after injury.Results: Compared with that of sham group, the number of mGluR1a positive neuron increased by 12.9±3.2 (P<0.05) 1 day after injury in the injured cerebral cortex in DBI group.However, in DBI and SBI group there was a more significant increase in the number of mGluR1a positive neuron at 4 hours after injury (15.6±3.0, P<0.05)and then the number of mGluR1a positive neuron gradually decreased.Administration of MCPG reduced total cortical necrotic neurons counts on the 7th day after injury (5.21±2.52, P<0.05).Conclusions: Brain injury can increase the gene expression of mGluR1a and the role of mGluR1a may be a key factor in the aggravation of head injury with SBI, and that MCPG may have therapeutic potential in head injury.

  2. Automated cGMP-compliant radiosynthesis of [(18) F]-(E)-PSS232 for brain PET imaging of metabotropic glutamate receptor subtype 5.

    Science.gov (United States)

    Park, Jun Young; Son, Jeongmin; Yun, Mijin; Ametamey, Simon M; Chun, Joong-Hyun

    2017-09-25

    (E)-3-(Pyridin-2-yl ethynyl)cyclohex-2-enone O-(3-(2-[(18) F]-fluoroethoxy)propyl) oxime ([(18) F]-(E)-PSS232, [(18) F]2a) is a recently developed radiotracer that can be used to visualize metabotropic glutamate receptor subtype 5 (mGlu5 ) in vivo. The mGlu5 has become an attractive therapeutic and diagnostic target owing to its role in many neuropsychiatric disorders. Several carbon-11- and fluorine-18-labelled radiotracers have been developed to measure mGlu5 receptor occupancy in the human brain. The radiotracer [(18) F]2a, which is used as an analogue for [(11) C]ABP688 ([(11) C]1) and has a longer physical half-life, is a selective radiotracer that exhibits high binding affinity for mGlu5 . Herein, we report the fully automated radiosynthesis of [(18) F]2a using a commercial GE TRACERlab(TM) FX-FN synthesizer for routine production and distribution to nearby satellite clinics. Nucleophilic substitution of the corresponding mesylate precursor with cyclotron-produced [(18) F]fluoride ion at 100 °C in dimethyl sulfoxide (DMSO), followed by high-performance liquid chromatography (HPLC) purification and formulation, readily provided [(18) F]2a with a radiochemical yield of 40 ± 2% (decay corrected, n = 5) at the end of synthesis. Radiochemical purity for the [(18) F]-(E)-conformer was greater than 95%. Molar activity was determined to be 63.6 ± 9.6 GBq/μmol (n = 5), and the overall synthesis time was 70 min. This article is protected by copyright. All rights reserved.

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

    Science.gov (United States)

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

    2017-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zanotti-Fregonara, Paolo; Liow, Jeih-San; Zoghbi, Sami S.; Clark, David T.; Morse, Cheryl; Pike, Victor W. [National Institute of Mental Health, National Institutes of Health, Molecular Imaging Branch, Bethesda, MD (United States); Barth, Vanessa N.; Rhoads, Emily; Siuda, Edward; Heinz, Beverly A.; Nisenbaum, Eric; Dressman, Bruce; Joshi, Elizabeth; Luffer-Atlas, Debra; Fisher, Matthew J.; Masters, John J.; Goebl, Nancy; Kuklish, Steven L.; Tauscher, Johannes [Eli Lilly and Co., Indianapolis, IN (United States); Innis, Robert B. [National Institute of Mental Health, National Institutes of Health, Molecular Imaging Branch, Bethesda, MD (United States); National Institute of Mental Health, Molecular Imaging Branch, Bethesda, MD (United States)

    2013-02-15

    Two allosteric modulators of the group I metabotropic glutamate receptors (mGluR1 and mGluR5) were evaluated as positron emission tomography (PET) radioligands for mGluR1. LY2428703, a full mGluR1 antagonist (IC{sub 50} 8.9 nM) and partial mGluR5 antagonist (IC{sub 50} 118 nM), and LSN2606428, a full mGluR1 and mGluR5 antagonist (IC{sub 50} 35.3 nM and 10.2 nM, respectively) were successfully labeled with {sup 11}C and evaluated as radioligands for mGluR1. The pharmacology of LY2428703 was comprehensively assessed in vitro and in vivo, and its biodistribution was investigated by liquid chromatography-mass spectrometry/mass spectrometry, and by PET imaging in the rat. In contrast, LSN2606428 was only evaluated in vitro; further evaluation was stopped due to its unfavorable pharmacological properties and binding affinity. {sup 11}C-LY2428703 showed promising characteristics, including: (1) high potency for binding to human mGluR1 (IC{sub 50} 8.9 nM) with no significant affinity for other human mGlu receptors (mGluR2 through mGluR8); (2) binding to brain displaceable by administration of an mGluR1 antagonist; (3) only one major radiometabolite in both plasma and brain, with a negligible brain concentration (with 3.5 % of the total radioactivity in cerebellum) and no receptor affinity; (4) a large specific and displaceable signal in the mGluR1-rich cerebellum with no significant in vivo affinity for mGluR5, as shown by PET studies in rats; and (5) lack of substrate behavior for efflux transporters at the blood-brain barrier, as shown by PET studies conducted in wild-type and knockout mice. {sup 11}C-LY2428703, a new PET radioligand for mGluR1 quantification, displayed promising characteristics both in vitro and in vivo in rodents. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Chi Zhang

    2015-01-01

    Full Text Available Background: Metabotropic glutamate receptors (mGluRs are G-protein-coupled receptors that mediate neuronal excitability and synaptic plasticity in the central nervous system, and emerging evidence suggests a role of mGluRs in the biology of cancer. Previous studies showed that mGluR1 was a potential therapeutic target for the treatment of breast cancer and melanoma, but its role in human glioma has not been determined. Methods: In the present study, we investigated the effects of mGluR1 inhibition in human glioma U87 cells using specific targeted small interfering RNA (siRNA or selective antagonists Riluzole and BAY36-7620. The anti-cancer effects of mGluR1 inhibition were measured by cell viability, lactate dehydrogenase (LDH release, TUNEL staining, cell cycle assay, cell invasion and migration assays in vitro, and also examined in a U87 xenograft model in vivo. Results: Inhibition of mGluR1 significantly decreased the cell viability but increased the LDH release in a dose-dependent fashion in U87 cells. These effects were accompanied with the induction of caspase-dependent apoptosis and G0/G1 cell cycle arrest. In addition, the results of Matrigel invasion and cell tracking assays showed that inhibition of mGluR1 apparently attenuated cell invasion and migration in U87 cells. All these anti-cancer effects were ablated by the mGluR1 agonist L-quisqualic acid. The results of western blot analysis showed that mGluR1 inhibition overtly decreased the phosphorylation of PI3K, Akt, mTOR and P70S6K, indicating the mitigated activation of PI3K/Akt/mTOR pathway. Moreover, the anti-tumor activity of mGluR1 inhibition in vivo was also demonstrated in a U87 xenograft glioma model in athymic nude mice. Conclusion: The remarkable efficiency of mGluR1 inhibition to induce cell death in U87 cells may find therapeutic application for the treatment of glioma patients.

  6. Radiosynthesis and evaluation of [{sup 11}C]YM-202074 as a PET ligand for imaging the metabotropic glutamate receptor type 1

    Energy Technology Data Exchange (ETDEWEB)

    Yanamoto, Kazuhiko; Konno, Fujiko; Odawara, Chika; Yamasaki, Tomoteru; Kawamura, Kazunori; Hatori, Akiko; Yui, Joji; Wakizaka, Hidekatsu [Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555 (Japan); Nengaki, Nobuki [Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555 (Japan); SHI Accelerator Service Co., Ltd., Shinagawa-ku, Tokyo 141-8686 (Japan); Takei, Makoto [Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555 (Japan); Tokyo Nuclear Service Co., Ltd., Taito-ku, Tokyo 110-0005 (Japan); Zhang Mingrong, E-mail: zhang@nirs.go.j [Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555 (Japan)

    2010-07-15

    Introduction: Developing positron emission tomography (PET) ligands for imaging metabotropic glutamate receptor type 1 (mGluR1) is important for studying its role in the central nervous system. N-cyclohexyl-6-{l_brace}[N-(2-methoxyethyl)-N-methylamino]methyl{r_brace} -N-methylthiazolo[3,2-a]benzimidazole-2-carboxamide (YM-202074) exhibited high binding affinity for mGluR1 (K{sub i}=4.8 nM), and selectivity over other mGluRs in vitro. The purpose of this study was to label YM-202074 with carbon-11 and to evaluate in vitro and in vivo characteristics of [{sup 11}C]YM-202074 as a PET ligand for mGluR1 in rodents. Methods: [{sup 11}C]YM-202074 was synthesized by N-[{sup 11}C]methylation of its desmethyl precursor with [{sup 11}C]methyl iodide. The in vitro and in vivo brain regional distributions were determined in rats using autoradiography and PET, respectively. Results: [{sup 11}C]YM-202074 (262-630 MBq, n=5) was obtained with radiochemical purity of >98% and specific activity of 27-52 GBq/{mu}mol at the end of synthesis, starting from [{sup 11}C]CO{sub 2} of 19.3-21.5 GBq. In vitro autoradiographic results showed that the high specific binding of [{sup 11}C]YM-202074 for mGluR1 was presented in the cerebellum, thalamus and hippocampus, which are known as mGluR1-rich regions. In ex vivo autoradiography and PET studies, the radioligand was specifically distributed in the cerebellum, although the uptake was low. Furthermore, the regional distribution was fairly uniform in the whole brain by pretreatment with JNJ16259685 (a mGluR1 antagonist). However, radiometabolite(s) was detected in the brain. Conclusions: From these results, especially considering the low brain uptake and the influx of radiometabolite(s) into brain, [{sup 11}C]YM-202074 may not be a useful PET ligand for in vivo imaging of mGluR1 in the brain.

  7. Synthesis, radiolabeling, in vitro and in vivo evaluation of [{sup 18}F]-FPECMO as a positron emission tomography radioligand for imaging the metabotropic glutamate receptor subtype 5

    Energy Technology Data Exchange (ETDEWEB)

    Lucatelli, Christophe; Honer, Michael; Salazar, Jean-Frederic; Ross, Tobias L.; Schubiger, P. August [Center for Radiopharmaceutical Science of ETH, PSI and USZ, 8093 Zurich (Switzerland); Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich (Switzerland); Ametamey, Simon M. [Center for Radiopharmaceutical Science of ETH, PSI and USZ, 8093 Zurich (Switzerland); Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich (Switzerland)], E-mail: simon.ametamey@pharma.ethz.ch

    2009-08-15

    Introduction: [{sup 18}F]-(E)-3-((6-Fluoropyridin-2-yl)ethynyl)cyclohex-2-enone O-methyl oxime ([{sup 18}F]-FPECMO) is a novel derivative of [{sup 11}C]-ABP688. [{sup 18}F]-FPECMO was characterized as a PET imaging agent for the metabotropic glutamate receptor subtype 5 (mGluR5). Methods: [{sup 18}F]-FPECMO was synthesized in a one-step reaction sequence by reacting [{sup 18}F]-KF-K{sub 222} complex with (E)-3-((6-bromopyridin-2-yl)ethynyl)cyclohex-2-enone O-methyl oxime in dry DMSO. The in vitro affinity of FPECMO was determined by displacement assays using rat whole brain homogenates (without cerebellum) and the mGluR5-specific radioligand [{sup 3}H]-M-MPEP. Further in vitro characterization involved metabolite studies, lipophilicity determination and autoradiographical analyses of brain slices. In vivo evaluation was performed by postmortem biodistribution studies and PET experiments using Sprague-Dawley rats. Results: The radiochemical yield after semipreparative HPLC was 35{+-}7% and specific activity was >240 GBq/{mu}mol. [{sup 18}F]-FPECMO exhibited optimal lipophilicity (logD=2.1) and high metabolic stability in vitro. Displacement studies revealed a K{sub i} value of 3.6{+-}0.7 nM for FPECMO. Biodistribution studies and ex vivo autoradiography showed highest radioactivity accumulation in mGluR5-rich brain regions such as the striatum and hippocampus. Co-injection of [{sup 18}F]-FPECMO and ABP688 (1 mg/kg body weight), an mGluR5 antagonist, showed 40% specific binding in the striatum, hippocampus and cortex, regions known to contain high densities of the mGluR5. PET imaging, however, did not allow the visualization of mGluR5-rich brain regions in the rat brain due to a fast washout of [{sup 18}F]-FPECMO from mGluR5-expressing tissues and rapid defluorination. Conclusions: [{sup 18}F]-FPECMO showed significant potential for the detection of mGluR5 in vitro; however, its in vivo characteristics are not optimal for a clear-cut visualization of the mGluR5 in

  8. Enhancement of social novelty discrimination by positive allosteric modulators at metabotropic glutamate 5 receptors: adolescent administration prevents adult-onset deficits induced by neonatal treatment with phencyclidine.

    Science.gov (United States)

    Clifton, Nicholas E; Morisot, Nadège; Girardon, Sylvie; Millan, Mark J; Loiseau, Florence

    2013-02-01

    Metabotropic glutamate-5 receptors (mGluR5), which physically and functionally interact with N-methyl-D-Aspartate (NMDA) receptors, likewise control cognitive processes and have been proposed as targets for novel classes of antipsychotic agent. Since social cognition is impaired in schizophrenia and disrupted by NMDA receptor antagonists like dizocilpine, we evaluated its potential modulation by mGluR5. Acute administration (0.63-40 mg/kg) of the mGluR5 positive allosteric modulators (PAMs), 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) and ADX47273, reversed a delay-induced impairment in social novelty discrimination (SND) in adult rats. The action of CDPPB was blocked by the mGluR5 antagonist, 2-methyl-6-(phenylethynyl)-pyridine (2.5-10 mg/kg), and was also expressed upon microinjection into frontal cortex (0.63-10 μg/side), but not striatum. Supporting an interrelationship between mGluR5 and NMDA receptors, enhancement of SND by CDPPB was blocked by dizocilpine (0.08 mg/kg) while, reciprocally, dizocilpine-induced impairment in SND was attenuated by CDPPB (10 mg/kg). The SND deficit elicited by post-natal administration of phencyclidine (10 mg/kg, days 7-11) was reversed by CDPPB or ADX47273 in adults at week 8. This phencyclidine-induced impairment in cognition emerged in adult rats from week 7 on, and chronic, pre-symptomatic treatment of adolescent rats with CDPPB over weeks 5-6 (10 mg/kg per day) prevented the appearance of SND deficits in adults until at least week 13. In conclusion, as evaluated by a SND procedure, mGluR5 PAMs promote social cognition via actions expressed in interaction with NMDA receptors and exerted in frontal cortex. MGluR5 PAMs not only reverse but also (when given during adolescence) prevent the emergence of cognitive impairment associated with a developmental model of schizophrenia.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yu Meixiang [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States)]. E-mail: myu@utmck.edu; Tueckmantel, Werner [Acenta Discovery Inc., Tucson, AZ 85747 (United States); Wang, Xukui [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States); Zhu Aijun [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States); Kozikowski, Alan P. [Acenta Discovery Inc., Tucson, AZ 85747 (United States); [Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60612 (United States); Brownell, Anna-Liisa [Experimental PET Laboratory, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 (United States)]. E-mail: abrownell@partners.org

    2005-08-01

    We have synthesized three different PET ligands to investigate the physiological function of metabotropic glutamate subtype 5 receptors (mGluR5) in vivo: 2-[{sup 11}C]methyl-6-(2-phenylethynyl)pyridine ([{sup 11}C]MPEP), 2-(2-(3-[{sup 11}C]methoxyphenyl)ethynyl)pyridine ([{sup 11}C]M-MPEP) and 2-(2-(5-[{sup 11}C]methoxypyridin-3-yl)ethynyl)pyridine ([{sup 11}C]M-PEPy). [{sup 11}C]Methyl iodide was used to label the compounds under basic conditions, and a Pd(0) catalyst was applied to label [{sup 11}C]MPEP in a Stille coupling reaction. In vivo microPET imaging studies of the functional accumulation of radiolabeled ligands were conducted in 35 rats (Sprague-Dawley, 8 weeks old male, weight of 300 g). Specific binding was tested using pre-administration of unlabeled mGluR5 antagonist 2-methyl-6-(2-phenylethynyl)pyridine (MPEP) (10 mg/kg iv 5 min before radioactivity injection). In the radiolabeling of [{sup 11}C]MPEP, [{sup 11}C]M-MPEP and [{sup 11}C]M-PEPy, a specific radioactivity of 700-1200 mCi/{mu}mol and over 97% radiochemical purity were obtained. The microPET studies showed these three radiolabeled mGluR5 antagonists having the highest binding in the olfactory bulb followed by striatum, hippocampus and cortex. Pre-administration of the mGluR5 antagonist MPEP induced a 45.1% decrease in [{sup 11}C]MPEP binding, a 59.7% decrease in [{sup 11}C]M-MPEP binding and an 84.6% decrease in [{sup 11}C]M-PEPy binding in the olfactory bulb at 5 min. The feasibility of synthesizing high-affinity and high-selectivity ligands for mGluR5 receptors and their suitability as PET imaging ligands for mGluR5 receptors in vivo are demonstrated.

  10. AMN082, a metabotropic glutamate receptor 7 allosteric agonist, attenuates locomotor sensitization and cross-sensitization induced by cocaine and morphine in mice.

    Science.gov (United States)

    Jenda, M; Gawel, K; Marszalek, M; Komsta, L; Kotlinska, J H

    2015-03-03

    Previous studies have indicated that metabotropic glutamate receptors 7 (mGluR7s) are involved in drug addiction. However, the role of these receptors in drug-induced behavioral sensitization is unknown. The aim of the present study was to determine whether systemic injection of AMN082, a selective mGluR7 allosteric agonist, reduces the cocaine- and morphine-induced hyperactivity and the development and expression of locomotor sensitization, and also affects the reciprocal cross-sensitization to the stimulant effect of cocaine and morphine in mice. AMN082 (1.25-10.0 mg/kg, i.p.) did not have an impact on locomotion of naive mice and did not affect the acute cocaine- or morphine-induced hyperactivity, except the dose of 10 mg/kg that suppressed the locomotor effect of both drugs. Repeated exposure to cocaine or morphine (10 mg/kg, 5× every 3 days) gradually increased locomotion during induction of sensitization and after 4 (cocaine) or 7 day (morphine) withdrawal phase when challenged with cocaine (10 mg/kg, i.p.) or morphine (10 mg/kg, i.p.) on day 17 or 20, respectively. Pretreatment of animals with the lower doses of AMN082 (1.25-5.0 mg/kg, i.p.), 30 min before every cocaine or morphine injection during repeated drug administration or before cocaine or morphine challenge, dose-dependently attenuated the development, as well as the expression of cocaine or morphine locomotor sensitization. AMN082 also inhibited the reciprocal cross-sensitization between these drugs. Prior to administration of MMPIP (10 mg/kg, i.p.), a selective mGluR7 antagonist reversed the inhibitory effect of AMN082 on the development or expression of cocaine or morphine sensitization. These data indicate that AMN082 attenuated the development and expression of cocaine and morphine sensitization, and the reciprocal cross-sensitization via a mechanism that involves mGluR7s. Thus, AMN082 might have therapeutic implications not only in the treatment of cocaine or opioid addiction but also in the

  11. Evidence for a fragile X mental retardation protein-mediated translational switch in metabotropic glutamate receptor-triggered Arc translation and long-term depression.

    Science.gov (United States)

    Niere, Farr; Wilkerson, Julia R; Huber, Kimberly M

    2012-04-25

    Group 1 metabotropic glutamate receptor (mGluR)-stimulated protein synthesis and long-term synaptic depression (mGluR-LTD) are altered in the mouse model of fragile X syndrome, Fmr1 knock-out (KO) mice. Fmr1 encodes fragile X mental retardation protein (FMRP), a dendritic RNA binding protein that functions, in part, as a translational suppressor. It is unknown whether and how FMRP acutely regulates LTD and/or the rapid synthesis of new proteins required for LTD, such as the activity-regulated cytoskeletal-associated protein (Arc). The protein phosphatase PP2A dephosphorylates FMRP, which contributes to translational activation of some target mRNAs. Here, we report that PP2A and dephosphorylation of FMRP at S500 are required for an mGluR-induced, rapid (5 min) increase in dendritic Arc protein and LTD in rat and mouse hippocampal neurons. In Fmr1 KO neurons, basal, dendritic Arc protein levels and mGluR-LTD are enhanced, but mGluR-triggered Arc synthesis is absent. Lentiviral-mediated expression of wild-type FMRP in Fmr1 KO neurons suppresses basal dendritic Arc levels and mGluR-LTD, and restores rapid mGluR-triggered Arc synthesis. A phosphomimic of FMRP (S500D) suppresses steady-state dendritic Arc levels but does not rescue mGluR-induced Arc synthesis. A dephosphomimic of FMRP (S500A) neither suppresses dendritic Arc nor supports mGluR-induced Arc synthesis. Accordingly, S500D-FMRP expression in Fmr1 KO neurons suppresses mGluR-LTD, whereas S500A-FMRP has no effect. These data support a model in which phosphorylated FMRP functions to suppress steady-state translation of Arc and LTD. Upon mGluR activation of PP2A, FMRP is rapidly dephosphorylated, which contributes to rapid new synthesis of Arc and mGluR-LTD.

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

    Directory of Open Access Journals (Sweden)

    Ying CAI

    2016-08-01

    Full Text Available Objective To investigate the change of metabotropic glutamate receptor 5 (mGluR5 expression level in rats with late-stage (the 7th day traumatic brain injury (TBI and the role of taurine. Methods The left cerebral TBI rat models were made by using lateral fluid percussion method. A total of 30 specific pathogen free (SPF male Sprague-Dawley (SD rats were randomly divided into 3 groups: sham operation group (control group, TBI model group (TBI group and taurine treatment group (taurine group. Wet and dry weight method was used to measure the brain water content. Real-time fluorescent quantitative polymerase chain reaction (PCR and Western blotting were used to detect the change of mRNA and protein expression of aquaporin 4 (AQP4 and mGluR5 in each group.  Results Compared with control group, the brain water content (t = 4.893, P = 0.002, AQP4 mRNA (t = 6.523, P = 0.000 and protein (t = 4.366, P = 0.008 expression were upregulated, while mGluR5 mRNA (t = 5.776, P = 0.001 and protein (t = 3.945, P = 0.014 expression were downregulated in TBI group. After taurine treatment, the brain water content (t = 2.151, P = 0.140, AQP4 mRNA (t = 1.144,P = 0.432 and protein (t = 0.367, P = 0.804 decreased to normal, while mGluR5 mRNA (t = 1.824, P = 0.216 and protein (t = 1.185, P = 0.414 increased to normal. Correlation analysis showed brain water content was negatively correlated with mGluR5 mRNA (r = -0.617, P = 0.014 and mGluR5 protein (r = -0.665, P = 0.007, while it was positively correlated with AQP4 protein (r = 0.658, P = 0.008.  Conclusions Taurine can significantly increase the mGluR5 expression level of brain issue in the late-stage (the 7th day of TBI and decline brain edema and brain water content. It may be a potential protective agent as an inhibitory neurotransmitter. DOI: 10.3969/j.issn.1672-6731.2016.08.008

  13. Preclinical evaluation and test-retest studies of [{sup 18}F]PSS232, a novel radioligand for targeting metabotropic glutamate receptor 5 (mGlu{sub 5})

    Energy Technology Data Exchange (ETDEWEB)

    Milicevic Sephton, Selena; Mueller Herde, Adrienne; Keller, Claudia; Ruedisuehli, Sonja; Schibli, Roger; Kraemer, Stefanie D.; Ametamey, Simon M. [Center for Radiopharmaceutical Sciences of ETH, PSI and USZ, Zurich (Switzerland); Mu, Linjing [University Hospital Zuerich, Department of Nuclear Medicine, Zuerich (Switzerland); Auberson, Yves [Novartis Institutes for Biomedical Research, Novartis Pharma AG, Basel (Switzerland)

    2015-01-15

    A novel, {sup 18}F-labelled metabotropic glutamate receptor subtype 5 (mGlu{sub 5}) derivative of [{sup 11}C]ABP688 ([{sup 11}C]1), [{sup 18}F]PSS232 ([{sup 18}F]5), was evaluated in vitro and in vivo for its potential as a PET agent and was used in test-retest reliability studies The radiosynthesis of [{sup 18}F]5 was accomplished via a one-step reaction using a mesylate precursor. In vitro stability was determined in PBS and plasma, and with liver microsomal enzymes. Metabolite studies were performed using rat brain extracts, blood and urine. In vitro autoradiography was performed on horizontal slices of rat brain using 1 and 8, antagonists for mGlu{sub 5} and mGlu{sub 1}, respectively. Small-animal PET, biodistribution, and test-retest studies were performed in Wistar rats. In vivo, dose-dependent displacement studies were performed using 6 and blocking studies with 7. [{sup 18}F]5 was obtained in decay-corrected maximal radiochemical yield of 37 % with a specific activity of 80 - 400 GBq/μmol. Treatment with rat and human microsomal enzymes in vitro for 60 min resulted in 20 % and 4 % of hydrophilic radiometabolites, respectively. No hydrophilic decomposition products or radiometabolites were found in PBS or plasma. In vitro autoradiography on rat brain slices showed a heterogeneous distribution consistent with the known distribution of mGlu{sub 5} with high binding to hippocampal and cortical regions, and negligible radioactivity in the cerebellum. Similar distribution of radioactivity was found in PET images. Under displacement conditions with 6, reduced [{sup 18}F]5 binding was found in all brain regions except the cerebellum. 7 reduced binding in the striatum by 84 % on average. Test-retest studies were reproducible with a variability ranging from 6.8 % to 8.2 %. An extended single-dose toxicity study in Wistar rats showed no compound-related adverse effects. The new mGlu{sub 5} radiotracer, [{sup 18}F]5, showed specific and selective in vitro and in vivo

  14. Non-competitive metabotropic glutamate 1 receptor antagonists block activity of slowly adapting type I mechanoreceptor units in the rat sinus hair follicle.

    Science.gov (United States)

    Cahusac, P M B; Mavulati, S C

    2009-10-20

    Previous studies suggested that Group I metabotropic glutamate (mGlu) receptors play a role in mechanotransduction processes of slowly adapting type I mechanoreceptors. Using an isolated rat sinus hair follicle preparation we tested a range of compounds. Surprisingly, only non-competitive mGlu1 receptor antagonists produced profound and long-lasting depression of mechanically evoked firing. 6-Amino-N-cyclohexyl-N,3-dimethylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (YM-298198) had an IC(50) of 8.7 muM (95% CI 5.7 to 13.2 microM), representing the most potent known blocker of type I mechanoreceptors. The derivative 6-amino-N-cyclohexyl-3-methylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (desmethyl YM-298198) had a comparable potency. Another compound 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) had a similar depressant effect, although it was less potent with an approximate IC(50) of 100 microM. Between three and seven times the concentration of CPCCOEt and YM-298198 respectively was required to produce similar depressions in slowly adapting type II units. No depression, and some weak excitatory effects, were observed using the following ligands: the competitive mGlu1 receptor antagonist alpha-amino-5-carboxy-3-methyl-2-thiopheneacetic acid (3-MATIDA) (300 microM), the phosphoserine phosphatase inhibitor dl-2-amino-3-phosphonopropionic acid (dl-AP3) (2 mM), non-competitive mGlu5 receptor antagonists 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine; (S)-3,5-DHPG, (S)-3,5-dihydroxyphenylglycine (MTEP) (10 microM) and 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) (100 microM), the mGlu1 receptor agonist (S)-3,5-dihydroxyphenylglycine ((S)-3,5-DHPG) (500 microM), and the mGlu5 receptor agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) (1 mM). The results suggest that the non-competitive mGlu1 receptor antagonists are not acting at conventional mGlu1 receptors but at other binding sites, possibly

  15. 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.)

  16. Group I Metabotropic Glutamate Receptors

    DEFF Research Database (Denmark)

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

    2015-01-01

    Human neural stem cells (NSCs) from the developing embryo or the subventricular zone of the adult brain can potentially elicit brain repair after injury or disease, either via endogenous cell proliferation or by cell transplantation. Profound knowledge of the diverse signals affecting these cells...

  17. Role of metabotropic glutamate receptor subtype mGluR1 in brief nociception and central sensitization of primate STT cells.

    Science.gov (United States)

    Neugebauer, V; Chen, P S; Willis, W D

    1999-07-01

    G-protein coupled metabotropic glutamate receptors (mGluRs) are important modulators of synaptic transmission in the mammalian CNS and have been implicated in various forms of neuroplasticity and nervous system disorders. Increasing evidence also suggests an involvement of mGluRs in nociception and pain behavior although the contribution of individual mGluR subtypes is not yet clear. Subtypes mGluR1 and mGluR5 are classified as group I mGluRs and share the ability to stimulate phosphoinositide hydrolysis and activate protein kinase C. The present study examined the role of group I mGluRs in nociceptive processing and capsaicin-induced central sensitization of primate spinothalamic tract (STT) cells in vivo. In 10 anesthetized male monkeys (Macaca fascicularis) extracellular recordings were made from 20 STT cells in the lumbar dorsal horn. Responses to brief (15 s) cutaneous stimuli of innocuous (BRUSH) and barely and substantially noxious (PRESS and PINCH, respectively) intensity were recorded before, during, and after the infusion of group I mGluR agonists and antagonists into the dorsal horn by microdialysis. Cumulative concentration-response relationships were obtained by applying different concentrations for at least 20 min each (at 5 microl/min). The actual concentrations reached in the tissue are 2-3 orders of magnitude lower than those in the microdialysis fibers (values in this paper refer to the latter). The group I antagonists were also applied at 10-25 min after capsaicin injection. S-DHPG, a group I agonist at both mGluR1 and mGluR5, potentiated the responses to innocuous and noxious stimuli (BRUSH > PRESS > PINCH) at low concentrations (10-100 microM; n = 5) but had inhibitory effects at higher concentrations (1-10 mM; n = 5). The mGluR5 agonist CHPG (1 microM-100 mM; n = 5) did not potentiate but inhibited all responses (10-100 mM; n = 5). AIDA (1 microM-100 mM), a mGluR1-selective antagonist, dose-dependently depressed the responses to PINCH and

  18. 代谢型谷氨酸受体参与对MAPK的调节%Regulation of the Ras-MAPK pathway in neurons by metabotropic glutamate receptors

    Institute of Scientific and Technical Information of China (English)

    毛利民; 杨鲁; Anish; Arora; Nikhil; K.; Parelkar; 张国弛; 刘贤宇; Eun; Sang; Choe; 陈海; 王强

    2005-01-01

    Mitogen-activated protein kinases (MAPKs) are expressed in postmitotic neuronal cells of adult mammalian brain and are involved in the regulation of various cellular activities, including inducible gene expression. Recent data from this laboratory show that selective stimulation of metabotropic glutamate receptor 5 (mGluR5) activates a major subclass of MAPKs, extracellular signal-regulated protein kinase ( ERK), in striatal neurons. The activation of ERK was mediated partially through the mGluR5-associated signaling pathway, i. e., inositol-1,4,5-triphosphate (IP3 )-mediated Ca2+ release. More importantly, the member of Homer family, Homer1b/c, forms a central signaling pathway linking mGluR5 to ERK in a Ca2+ -independent manner. In addition, a major serine/threonine phosphatase, protein phosphatase 2A (PP2A), is also involved in the mGluR5 regulation of ERK phosphorylation. As an information superhighway between the surface membrane and the nucleus, ERK when co-activated by both IP3/Ca2+- and Homer1 b/c-dependent pathways showed the ability to phosphorylate two transcription factors, Elk-1 and cAMP response element-binding protein (CREB),and thereby facilitated c-Fos expression. Together, available data obtained from this laboratory and others indicate that mGluR5 possesses the ability to activate the ERK pathway in striatal neurons. A sophisticated signaling apparatus involving coordinated interactions between protein kinases and protein phosphatases mediates the mGluR5-ERK coupling imperative for the transcriptional regulation.%Mitogen-activated protein kinase(MAPK)在成体脑细胞高度表达并参与了多种细胞功能活动的调节.近年来,本实验室的实验结果表明五型代谢型谷氨酸受体(mGluR5)可以激活纹状体培养神经元内MAPK的主要亚型ERK,ERK的激活经由两条独立的胞内信号通路介导,传统的IP3/Ca2+通路介导了一部分的ERK激活,而mGluR5的C-端结合蛋白Homer则以Ca2+-非依赖方式介导了

  19. Synthesis and structure-activity relationships of 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine analogues as potent, noncompetitive metabotropic glutamate receptor subtype 5 antagonists; search for cocaine medications.

    Science.gov (United States)

    Iso, Yasuyoshi; Grajkowska, Ewa; Wroblewski, Jarda T; Davis, Jared; Goeders, Nicholas E; Johnson, Kenneth M; Sanker, Subramaniam; Roth, Bryan L; Tueckmantel, Werner; Kozikowski, Alan P

    2006-02-09

    Recent genetic and pharmacological studies have suggested that the metabotropic glutamate receptor subtype 5 (mGluR5) may represent a druggable target in identifying new therapeutics for the treatment of various central nervous system disorders including drug abuse. In particular, considerable attention in the mGluR5 field has been devoted to identifying ligands that bind to the allosteric modulatory site, distinct from the site for the primary agonist glutamate. Both 2-methyl-6-(phenylethynyl)pyridine (MPEP) and its analogue 3-[(2-methyl-4-thiazolyl)ethynyl]pyridine (MTEP) have been shown to be selective and potent noncompetitive antagonists of mGluR5. Because of results presented in this study showing that MTEP prevents the reinstatement of cocaine self-administration caused by the presentation of environmental cues previously associated with cocaine availability, we have prepared a series of analogues of MTEP with the aim of gaining a better understanding of the structural features relevant to its antagonist potency and with the ultimate aim of investigating the effects of such compounds in blunting the self-administration of cocaine. These efforts have led to the identification of compounds showing higher potency as mGluR5 antagonists than either MPEP or MTEP. Two compounds 19 and 59 exhibited functional activity as mGluR5 antagonists that are 490 and 230 times, respectively, better than that of MTEP.

  20. The metabotropic glutamate 2/3 receptor agonist LY379268 counteracted ketamine-and apomorphine-induced performance deficits in the object recognition task, but not object location task, in rats.

    Science.gov (United States)

    Pitsikas, Nikolaos; Markou, Athina

    2014-10-01

    Experimental evidence indicates that the non competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine and the mixed dopamine (DA) D1/D2 receptor agonist apomorphine induce schizophrenia-like symptoms in rodents, including cognitive deficits. Activation of Group II metabotropic glutamate 2/3 (mGlu2/3) receptors reduces the excessive glutamate release that is hypothesized to be associated with psychiatric disorders. Thus, mGlu2/3 receptor agonists may reverse deficits induced by excessive glutamate or DA release induced by administration of NMDA receptor antagonists and DA receptor agonists, respectively, and potentially those seen in schizophrenia. LY379268 is a selective mGlu2/3 receptor agonist that has shown to be effective in several animal models of stroke, epilepsy, and drug abuse. The present study investigated whether LY379268 antagonizes non-spatial and spatial recognition memory deficits induced by ketamine and apomorphine administration in rats. To assess the effects of the compounds on non-spatial and spatial recognition memory, the object recognition task and object location task were used. Post-training administration of LY379268 (1-3 mg/kg, i.p.) counteracted ketamine (3 mg/kg, i.p.) and apomorphine (1 mg/kg, i.p.)-induced performance deficits in the object recognition task. In contrast, LY379268 (1-3 mg/kg, i.p.) did not attenuate spatial recognition memory deficits produced by ketamine (3 mg/kg, i.p.) or apomorphine (1 mg/kg, i.p.) in the object location task. The present data show that the mGlu2/3 receptor agonist LY379268 reversed non-spatial, but not spatial, recognition memory deficits induced by NMDA receptor blockade or DA receptor agonism in rodents. Thus, such mGlu2/3 receptor agonists may be efficacious in reversing some memory deficits seen in schizophrenia patients.

  1. Relevance of the metabotropic glutamate receptor (mGluR5) in the regulation of NREM-REM sleep cycle and homeostasis: evidence from mGluR5 (-/-) mice.

    Science.gov (United States)

    Ahnaou, A; Raeymaekers, L; Steckler, T; Drinkenbrug, W H I M

    2015-04-01

    Sleep is a homeostatically regulated behavior and sleep loss evokes a proportional increase in sleep time and delta slow wave activity. Glutamate and pharmacological modulation of the metabotropic glutamate receptors (mGluR) signaling have been implicated in the organization of vigilance states. Here, the role of the mGluR5 on homeostatic regulation of sleep-wake cycle and electroencephalographic (EEG) activity was examined in mGluR5 (-/-) mice. We first characterized the sleep-wake EEG phenotype in mGluR5 (-/-) and wild-type (WT) littermates mice by continuous recording for 72h of EEG, body temperature (BT) and locomotor activity (LMA). Next, we investigated the influence of sleep deprivation on the recovery sleep and EEG slow wave activity (1-4Hz) during NREM sleep to assess whether mGluR5 deletion affects the sleep homeostasis process. Like the control animals, mGluR5 (-/-) mice exhibited a clear-cut circadian sleep-wake architecture, however they showed reduced REM sleep time during the light phase with shorter REM sleep bouts and reduced state transitions in the NREM sleep-REM sleep cycle during the first and last 24h of the spontaneous 72h recording period. In addition, mGluR5 (-/-) mice had decreased slow EEG delta power during NREM sleep and enhanced LMA associated with elevated BT during the dark phase. Moreover, mGluR5 (-/-) mice exhibited reduced slow wave activity and sleep drive after sleep deprivation, indicating altered sleep homeostatic processes. The findings strongly indicate that mGluR5 is involved in shaping the stability of NREM sleep-REM sleep state transitions, NREM slow wave activity and homeostatic response to sleep loss.

  2. Design and synthesis of systemically active metabotropic glutamate subtype-2 and -3 (mGlu2/3) receptor positive allosteric modulators (PAMs): pharmacological characterization and assessment in a rat model of cocaine dependence.

    Science.gov (United States)

    Dhanya, Raveendra-Panickar; Sheffler, Douglas J; Dahl, Russell; Davis, Melinda; Lee, Pooi San; Yang, Li; Nickols, Hilary Highfield; Cho, Hyekyung P; Smith, Layton H; D'Souza, Manoranjan S; Conn, P Jeffrey; Der-Avakian, Andre; Markou, Athina; Cosford, Nicholas D P

    2014-05-22

    As part of our ongoing small-molecule metabotropic glutamate (mGlu) receptor positive allosteric modulator (PAM) research, we performed structure-activity relationship (SAR) studies around a series of group II mGlu PAMs. Initial analogues exhibited weak activity as mGlu2 receptor PAMs and no activity at mGlu3. Compound optimization led to the identification of potent mGlu2/3 selective PAMs with no in vitro activity at mGlu1,4-8 or 45 other CNS receptors. In vitro pharmacological characterization of representative compound 44 indicated agonist-PAM activity toward mGlu2 and PAM activity at mGlu3. The most potent mGlu2/3 PAMs were characterized in assays predictive of ADME/T and pharmacokinetic (PK) properties, allowing the discovery of systemically active mGlu2/3 PAMs. On the basis of its overall profile, compound 74 was selected for behavioral studies and was shown to dose-dependently decrease cocaine self-administration in rats after intraperitoneal administration. These mGlu2/3 receptor PAMs have significant potential as small molecule tools for investigating group II mGlu pharmacology.

  3. Metabotropic glutamate receptor 5 negative allosteric modulators: discovery of 2-chloro-4-[1-(4-fluorophenyl)-2,5-dimethyl-1H-imidazol-4-ylethynyl]pyridine (basimglurant, RO4917523), a promising novel medicine for psychiatric diseases.

    Science.gov (United States)

    Jaeschke, Georg; Kolczewski, Sabine; Spooren, Will; Vieira, Eric; Bitter-Stoll, Nadia; Boissin, Patrick; Borroni, Edilio; Büttelmann, Bernd; Ceccarelli, Simona; Clemann, Nicole; David, Beatrice; Funk, Christoph; Guba, Wolfgang; Harrison, Anthony; Hartung, Thomas; Honer, Michael; Huwyler, Jörg; Kuratli, Martin; Niederhauser, Urs; Pähler, Axel; Peters, Jens-Uwe; Petersen, Ann; Prinssen, Eric; Ricci, Antonio; Rueher, Daniel; Rueher, Marianne; Schneider, Manfred; Spurr, Paul; Stoll, Theodor; Tännler, Daniel; Wichmann, Jürgen; Porter, Richard H; Wettstein, Joseph G; Lindemann, Lothar

    2015-02-12

    Negative allosteric modulators (NAMs) of metabotropic glutamate receptor 5 (mGlu5) have potential for the treatment of psychiatric diseases including depression, fragile X syndrome (FXS), anxiety, obsessive-compulsive disorders, and levodopa induced dyskinesia in Parkinson's disease. Herein we report the optimization of a weakly active screening hit 1 to the potent and selective compounds chloro-4-[1-(4-fluorophenyl)-2,5-dimethyl-1H-imidazol-4-ylethynyl]pyridine (basimglurant, 2) and 2-chloro-4-((2,5-dimethyl-1-(4-(trifluoromethoxy)phenyl)-1H-imidazol-4-yl)ethynyl)pyridine (CTEP, 3). Compound 2 is active in a broad range of anxiety tests reaching the same efficacy but at a 10- to 100-fold lower dose compared to diazepam and is characterized by favorable DMPK properties in rat and monkey as well as an excellent preclinical safety profile and is currently in phase II clinical studies for the treatment of depression and fragile X syndrome. Analogue 3 is the first reported mGlu5 NAM with a long half-life in rodents and is therefore an ideal tool compound for chronic studies in mice and rats.

  4. Metabotropic Glutamate Receptor Type 5 (mGluR5) Cortical Abnormalities in Focal Cortical Dysplasia Identified In Vivo With [11C]ABP688 Positron-Emission Tomography (PET) Imaging

    Science.gov (United States)

    DuBois, Jonathan M.; Rousset, Olivier G.; Guiot, Marie-Christine; Hall, Jeffery A.; Reader, Andrew J.; Soucy, Jean-Paul; Rosa-Neto, Pedro; Kobayashi, Eliane

    2016-01-01

    Metabotropic glutamate receptor type 5 (mGluR5) abnormalities have been described in tissue resected from epilepsy patients with focal cortical dysplasia (FCD). To determine if these abnormalities could be identified in vivo, we investigated mGluR5 availability in 10 patients with focal epilepsy and an MRI diagnosis of FCD using positron-emission tomography (PET) and the radioligand [11C]ABP688. Partial volume corrected [11C]ABP688 binding potentials (BPND) were computed using the cerebellum as a reference region. Each patient was compared to homotopic cortical regions in 33 healthy controls using region-of-interest (ROI) and vertex-wise analyses. Reduced [11C]ABP688 BPND in the FCD was seen in 7/10 patients with combined ROI and vertex-wise analyses. Reduced FCD BPND was found in 4/5 operated patients (mean follow-up: 63 months; Engel I), of whom surgical specimens revealed FCD type IIb or IIa, with most balloon cells showing negative or weak mGluR5 immunoreactivity as compared to their respective neuropil and normal neurons at the border of resections. [11C]ABP688 PET shows for the first time in vivo evidence of reduced mGluR5 availability in FCD, indicating focal glutamatergic alterations in malformations of cortical development, which cannot be otherwise clearly demonstrated through resected tissue analyses. PMID:27578494

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

    Science.gov (United States)

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

    2012-09-19

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

  6. 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...

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

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Krogsgaard-Larsen, P

    1998-01-01

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

  8. Biotransformation of a novel positive allosteric modulator of metabotropic glutamate receptor subtype 5 contributes to seizure-like adverse events in rats involving a receptor agonism-dependent mechanism.

    Science.gov (United States)

    Bridges, Thomas M; Rook, Jerri M; Noetzel, Meredith J; Morrison, Ryan D; Zhou, Ya; Gogliotti, Rocco D; Vinson, Paige N; Xiang, Zixiu; Jones, Carrie K; Niswender, Colleen M; Lindsley, Craig W; Stauffer, Shaun R; Conn, P Jeffrey; Daniels, J Scott

    2013-09-01

    Activation of metabotropic glutamate receptor subtype 5 (mGlu5) represents a novel strategy for therapeutic intervention into multiple central nervous system disorders, including schizophrenia. Recently, a number of positive allosteric modulators (PAMs) of mGlu5 were discovered to exhibit in vivo efficacy in rodent models of psychosis, including PAMs possessing varying degrees of agonist activity (ago-PAMs), as well as PAMs devoid of agonist activity. However, previous studies revealed that ago-PAMs can induce seizure activity and behavioral convulsions, whereas pure mGlu5 PAMs do not induce these adverse effects. We recently identified a potent and selective mGlu5 PAM, VU0403602, that was efficacious in reversing amphetamine-induced hyperlocomotion in rats. The compound also induced time-dependent seizure activity that was blocked by coadministration of the mGlu5 antagonist, 2-methyl-6-(phenylethynyl) pyridine. Consistent with potential adverse effects induced by ago-PAMs, we found that VU0403602 had significant allosteric agonist activity. Interestingly, inhibition of VU0403602 metabolism in vivo by a pan cytochrome P450 (P450) inactivator completely protected rats from induction of seizures. P450-mediated biotransformation of VU0403602 was discovered to produce another potent ago-PAM metabolite-ligand (M1) of mGlu5. Electrophysiological studies in rat hippocampal slices confirmed agonist activity of both M1 and VU0403602 and revealed that M1 can induce epileptiform activity in a manner consistent with its proconvulsant behavioral effects. Furthermore, unbound brain exposure of M1 was similar to that of the parent compound, VU0403602. These findings indicate that biotransformation of mGlu5 PAMs to active metabolite-ligands may contribute to the epileptogenesis observed after in vivo administration of this class of allosteric receptor modulators.

  9. Intrathecal administration of roscovitine prevents remifentanil-induced postoperative hyperalgesia and decreases the phosphorylation of N-methyl-D-aspartate receptor and metabotropic glutamate receptor 5 in spinal cord.

    Science.gov (United States)

    Liu, Xiaojie; Liu, Yue; Zhang, Juan; Zhang, Wei; Sun, Yu-E; Gu, Xiaoping; Ma, Zhengliang

    2014-07-01

    N-methyl-D-aspartate receptor (NMDAR) and metabotropic glutamate receptor 5 (mGluR5) play an important role in nociceptive processing and central sensitization. Our previous study showed that tyrosine phosphorylation of NMDAR subunit 2B (NR2B) at Tyr1472 in spinal dorsal horn contributes to the postoperative hyperalgesia induced by remifentanil. Cyclin-dependent kinase 5 (Cdk5) has been implicated in synaptic plasticity, learning, memory and pain signaling via regulating the phosphorylation of NMDAR and mGluR5. In the present study, a rat model of postoperative pain was used to investigate the role of Cdk5 in spinal dorsal horn in remifentanil-induced hyperalgesia and the intervention of pretreatment with Cdk5 inhibitor roscovitine. Intraoperative infusion of remifentanil (0.04 mg/kg, subcutaneous) significantly enhanced mechanical allodynia and thermal hyperalgesia induced by plantar incision during the postoperative period (each lasting between 2 h and 48 h), which were attenuated by pretreatment with roscovitine. Correlated with the pain behavior changes, Western blotting revealed that there was a significant increase in the expression of Cdk5 and its activator p35/p25, and further the kinase activity of Cdk5 in spinal dorsal horn after intraoperative infusion of remifentanil. The phosphorylation of NR2A at Ser1232, the phosphorylation of NR2B at Tyr1472 and the phosphorylation of mGluR5 at Ser1167 were also significantly up-regulated. Furthermore, these increases were attenuated by pretreatment with roscovitine. These results suggested that Cdk5 may contribute to remifentanil-induced postoperative hyperalgesia via regulating the phosphorylation of NMDAR and mGluR5 in spinal dorsal horn. These findings provide experimental evidence for the further application of Cdk5 inhibitor in preventing remifentanil-induced hyperalgesia. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Amygdalar activation of group I metabotropic glutamate receptors produces anti- and pro-conflict effects depending upon animal sex in a sexually dimorphic conditioned conflict-based anxiety model

    Science.gov (United States)

    De Jesús-Burgos, María I.; González-García, Stephanie; Cruz-Santa, Yanira; Pérez-Acevedo, Nivia L.

    2016-01-01

    Women are more susceptible than men to develop anxiety disorders, however, the mechanisms involved are still unclear. In this study, we investigated the role of group I metabotropic glutamate receptors (mGluRs), a target for anxiety disorders, and whether estradiol may modulate conflict-based anxiety in female rats by using the Vogel Conflict Test (VCT). We used ovariectomized female rats with high (OVX + EB) and low (OVX) estradiol levels and intact male rats to evaluate sex differences. Infusion of (S)-3,5-Dihydroxyphenylglycine (DHPG), a group I mGluR agonist, into the basolateral amygdala, a region involved in anxiety-responses, statistically increased the number of shocks in OVX, but not OVX + EB female rats at 0.1, nor at 1.0 μM. In contrast, DHPG statistically decreased the number of shocks in male rats at 1.0 μM only. DHPG (0.1 μM) increased the number of recoveries in OVX, but not OVX + EB or male rats. Sex differences were detected for the number of shocks, recoveries and punished licks, where female rats displayed more conflict than male rats. Western blot analyses showed that protein expression of mGluR1, but not mGluR5 was higher in OVX + EB > OVX > male rats in the amygdala, whereas no significant differences were detected in the hippocampus, olfactory bulb and/or the periaqueductal gray. Therefore, DHPG produced paradoxical effects that are sex dependent; producing anxiolytic-like effects in female rats, while anxiogenic-like effects in male rats according to the VCT. These results highlight the importance of including female experimental models to underpin the neural circuitry of anxiety according to sex and for the screening of novel anxiolytic compounds. PMID:26777900

  11. Amygdalar activation of group I metabotropic glutamate receptors produces anti- and pro-conflict effects depending upon animal sex in a sexually dimorphic conditioned conflict-based anxiety model.

    Science.gov (United States)

    De Jesús-Burgos, María I; González-García, Stephanie; Cruz-Santa, Yanira; Pérez-Acevedo, Nivia L

    2016-04-01

    Women are more susceptible than men to develop anxiety disorders, however, the mechanisms involved are still unclear. In this study, we investigated the role of group I metabotropic glutamate receptors (mGluRs), a target for anxiety disorders, and whether estradiol may modulate conflict-based anxiety in female rats by using the Vogel Conflict Test (VCT). We used ovariectomized female rats with high (OVX+EB) and low (OVX) estradiol levels and intact male rats to evaluate sex differences. Infusion of (S)-3,5-Dihydroxyphenylglycine (DHPG), a group I mGluR agonist, into the basolateral amygdala, a region involved in anxiety-responses, statistically increased the number of shocks in OVX, but not OVX+EB female rats at 0.1, nor at 1.0 μM. In contrast, DHPG statistically decreased the number of shocks in male rats at 1.0 μM only. DHPG (0.1 μM) increased the number of recoveries in OVX, but not OVX+EB or male rats. Sex differences were detected for the number of shocks, recoveries and punished licks, where female rats displayed more conflict than male rats. Western blot analyses showed that protein expression of mGluR1, but not mGluR5 was higher in OVX+EB>OVX>male rats in the amygdala, whereas no significant differences were detected in the hippocampus, olfactory bulb and/or the periaqueductal gray. Therefore, DHPG produced paradoxical effects that are sex dependent; producing anxiolytic-like effects in female rats, while anxiogenic-like effects in male rats according to the VCT. These results highlight the importance of including female experimental models to underpin the neural circuitry of anxiety according to sex and for the screening of novel anxiolytic compounds.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. Novel agonists for serotonin 5-HT7 receptors reverse metabotropic glutamate receptor-mediated long-term depression in the hippocampus of wild-type and Fmr1 KO mice, a model of Fragile X Syndrome

    Directory of Open Access Journals (Sweden)

    Lara eCosta

    2015-03-01

    Full Text Available Serotonin 5-HT7 receptors are expressed in the hippocampus and modulate the excitability of hippocampal neurons. We have previously shown that 5-HT7 receptors modulate glutamate-mediated hippocampal synaptic transmission and long-term synaptic plasticity. In particular, we have shown that activation of 5-HT7 receptors reversed metabotropic glutamate receptor-mediated long-term depression (mGluR-LTD in wild-type (wt and in Fmr1 KO mice, a mouse model of Fragile X syndrome in which mGluR-LTD is abnormally enhanced, suggesting that 5-HT7 receptor agonists might be envisaged as a novel therapeutic strategy for Fragile X syndrome. In this perspective, we have characterized the basic in vitro pharmacokinetic properties of novel molecules with high binding affinity and selectivity for 5-HT7 receptors and we have tested their effects on synaptic plasticity using patch clamp on acute hippocampal slices.Here we show that LP-211, a high affinity selective agonist of 5-HT7 receptors, reverses mGluR-LTD in wt and Fmr1 KO mice, correcting a synaptic malfunction in the mouse model of Fragile X syndrome. Among novel putative agonists of 5-HT7 receptors, the compound BA-10 displayed improved affinity and selectivity for 5-HT7 receptors and improved in vitro pharmacokinetic properties with respect to LP-211. BA-10 significantly reversed mGluR-LTD in the CA3-CA1 synapse in wt and Fmr1KO mice, indicating that BA-10 behaved as a highly effective agonist of 5-HT7 receptors and reduced exaggerated mGluR-LTD in a mouse model of Fragile X Syndrome. On the other side, the compounds RA-7 and PM-20, respectively arising from in vivo metabolism of LP-211 and BA-10, had no effect on mGluR-LTD thus did not behave as agonists of 5-HT7 receptors in our conditions.The present results provide information about the structure-activity relationship of novel 5-HT7 receptor agonists and indicate that LP-211 and BA-10 might be used as novel pharmacological tools for the therapy of

  14. Novel agonists for serotonin 5-HT7 receptors reverse metabotropic glutamate receptor-mediated long-term depression in the hippocampus of wild-type and Fmr1 KO mice, a model of Fragile X Syndrome.

    Science.gov (United States)

    Costa, Lara; Sardone, Lara M; Lacivita, Enza; Leopoldo, Marcello; Ciranna, Lucia

    2015-01-01

    Serotonin 5-HT7 receptors are expressed in the hippocampus and modulate the excitability of hippocampal neurons. We have previously shown that 5-HT7 receptors modulate glutamate-mediated hippocampal synaptic transmission and long-term synaptic plasticity. In particular, we have shown that activation of 5-HT7 receptors reversed metabotropic glutamate receptor-mediated long-term depression (mGluR-LTD) in wild-type (wt) and in Fmr1 KO mice, a mouse model of Fragile X Syndrome in which mGluR-LTD is abnormally enhanced, suggesting that 5-HT7 receptor agonists might be envisaged as a novel therapeutic strategy for Fragile X Syndrome. In this perspective, we have characterized the basic in vitro pharmacokinetic properties of novel molecules with high binding affinity and selectivity for 5-HT7 receptors and we have tested their effects on synaptic plasticity using patch clamp on acute hippocampal slices. Here we show that LP-211, a high affinity selective agonist of 5-HT7 receptors, reverses mGluR-LTD in wt and Fmr1 KO mice, correcting a synaptic malfunction in the mouse model of Fragile X Syndrome. Among novel putative agonists of 5-HT7 receptors, the compound BA-10 displayed improved affinity and selectivity for 5-HT7 receptors and improved in vitro pharmacokinetic properties with respect to LP-211. BA-10 significantly reversed mGluR-LTD in the CA3-CA1 synapse in wt and Fmr1KO mice, indicating that BA-10 behaved as a highly effective agonist of 5-HT7 receptors and reduced exaggerated mGluR-LTD in a mouse model of Fragile X Syndrome. On the other side, the compounds RA-7 and PM-20, respectively arising from in vivo metabolism of LP-211 and BA-10, had no effect on mGluR-LTD thus did not behave as agonists of 5-HT7 receptors in our conditions. The present results provide information about the structure-activity relationship of novel 5-HT7 receptor agonists and indicate that LP-211 and BA-10 might be used as novel pharmacological tools for the therapy of Fragile X Syndrome.

  15. Anxiolytic effects of a novel group II metabotropic glutamate receptor agonist (LY354740) in the fear-potentiated startle paradigm in humans.

    Science.gov (United States)

    Grillon, Christian; Cordova, Jeremy; Levine, Louise R; Morgan, Charles A

    2003-08-01

    LY354740, a structural analogue of glutamate that shows specificity at the mGluR2/3 receptor, has anxiolytic effects in animal models. This study investigated the anxiolytic effects of LY354740 in humans using the fear-potentiated startle reflex methodology. Subjects were given either placebo (n=16), 20 mg LY354740 (n=15), or 200 mg LY354740 (n=13). The fear-potentiated startle tests examined startle potentiation to shock anticipation and to darkness. Consistent with previous results, startle was increased by threat of shock and by darkness. LY354740 did not affect baseline startle. Correspondingly, subjects did not report LY354740 to be sedative. LY354740 significantly reduced the increase in startle magnitude during shock anticipation, but not during darkness. Subjective reports of state anxiety and negative affectivity during the fear-potentiated startle tests were also reduced in a dose-dependent manner by LY354740. These results suggest that LY354740 has an anxiolytic profile in humans without being sedative.

  16. THC (Δ9-Tetrahydrocannabinol) Exerts Neuroprotective Effect in Glutamate-affected Murine Primary Mesencephalic Cultures Through Restoring Mitochondrial Membrane Potential and Anti-apoptosis Involving CB1 Receptor-dependent Mechanism.

    Science.gov (United States)

    Nguyen, Chi Huu; Krewenka, Christopher; Radad, Khaled; Kranner, Barbara; Huber, Alexandra; Duvigneau, Johanna Catharina; Miller, Ingrid; Moldzio, Rudolf

    2016-12-01

    Aging-related neurodegenerative diseases, such as Parkinson's disease (PD) or related disorders, are an increasing societal and economic burden worldwide. Δ9-Tetrahydrocannabinol (THC) is discussed as a neuroprotective agent in several in vitro and in vivo models of brain injury. However, the mechanisms by which THC exhibits neuroprotective properties are not completely understood. In the present study, we investigated neuroprotective mechanisms of THC in glutamate-induced neurotoxicity in primary murine mesencephalic cultures, as a culture model for PD. Glutamate was administered for 48 h with or without concomitant THC treatment. Immunocytochemistry staining and resazurin assay were used to evaluate cell viability. Furthermore, superoxide levels, caspase-3 activity, and mitochondrial membrane potential were determined to explore the mode of action of this compound. THC protected dopaminergic neurons and other cell types of primary dissociated cultures from glutamate-induced neurotoxicity. Moreover, THC significantly counteracted the glutamate-induced mitochondrial membrane depolarization and apoptosis. SR141716A, a CB1 receptor antagonist, concentration-dependently blocked the protective effect of THC in primary mesencephalic cultures. In conclusion, THC exerts anti-apoptotic and restores mitochondrial membrane potential via a mechanism dependent on CB1 receptor. It strengthens the fact that THC has a benefit on degenerative cellular processes occurring, among others, in PD and other neurodegenerative diseases by slowing down the progression of neuronal cell death. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Transcriptional regulation of metabotropic glutamate receptor 2/3 expression by the NF-κB pathway in primary dorsal root ganglia neurons: a possible mechanism for the analgesic effect of L-acetylcarnitine

    Directory of Open Access Journals (Sweden)

    Nicoletti Ferdinando

    2006-06-01

    Full Text Available Abstract L-acetylcarnitine (LAC, a drug utilized for the treatment of neuropathic pain in humans, has been shown to induce analgesia in rodents by up-regulating the expression of metabotropic glutamate receptor 2 (mGlu2 in dorsal root ganglia (DRG. We now report that LAC-induced upregulation of mGlu2 expression in DRG cultures involves transcriptional activation mediated by nuclear factor-kappaB (NF-κB. A single application of LAC (250 μM to DRG cultures induced a transient increase in mGlu2 mRNA, which was observable after 1 hour and was no longer detectable after 1 to 4 days. In contrast, LAC treatment had no effect on mGlu3 mRNA expression. Pharmacological inhibition of NF-κB binding to DNA by caffeic acid phenethyl ester (CAPE (2.5 μg/ml for 30 minutes reduced the constitutive expression of mGlu2 and mGlu3 mRNA after 1–4 days and reduced the constitutive expression of mGlu2/3 protein at 4 days. This evidence combined with the expression of p65/RelA and c-Rel in DRG neurons indicated that expression of mGlu2 and mGlu3 is endogenously regulated by the NF-κB family of transcription factors. Consistent with this idea, the transient increase in mGlu2 mRNA induced by LAC after 1 hour was completely suppressed by CAPE. Furthermore, LAC induced an increase in the acetylation of p65/RelA, a process that enhances the transcriptional activity of p65/RelA. These results are consistent with the hypothesis that LAC selectively induces the expression of mGlu2 by acting as a donor of acetyl groups, thus enhancing the activity of the NF-κB family of transcription factors. Accordingly, we show that carnitine, which has no effect on pain thresholds, had no effect on p65/RelA acetylation and did not enhance mGlu2 expression. Taken together, these results demonstrate that expression of mGlu2 and mGlu3 mRNA is regulated by the NF-κB transcriptional machinery, and that agents that increase acetylation and activation of NF-κB transcription factors might

  18. Blockade of stress-induced increase of glutamate release in the rat prefrontal/frontal cortex by agomelatine involves synergy between melatonergic and 5-HT2C receptor-dependent pathways

    Directory of Open Access Journals (Sweden)

    Racagni Giorgio

    2010-06-01

    Full Text Available Abstract Background Agomelatine is a melatonergic receptor agonist and a 5HT2C receptor antagonist that has shown antidepressant efficacy. In order to analyze separately the effect of the two receptorial components, rats were chronically treated with agomelatine, melatonin (endogenous melatonergic agonist, or S32006 (5-HT2C antagonist, and then subjected to acute footshock-stress. Results Only chronic agomelatine, but not melatonin or S32006, completely prevented the stress-induced increase of glutamate release in the rat prefrontal/frontal cortex. Conclusions These results suggest a potential synergy between melatonergic and serotonergic pathways in the action of agomelatine.

  19. 大鼠纹状体I组代谢型谷氨酸受体激动引起动物向对侧旋转%Activation of group I metabotropic glutamate receptors in rat striatum induces contralateral rotation

    Institute of Scientific and Technical Information of China (English)

    袁芳; 王忠诚; 徐立新; 王天佑; 张亚卓

    2001-01-01

    AIM:To study the subtype of metabotropic glutamate receptors (mGluRs) which induce contralateral rotations of rats after mGluRs activation. METHODS:Turning movement was measured at 6 h after agonist or antagonist of mGluRs was microinjected into rat striatum. RESULTS:tACPD, an agonist of mGluRs, at 500 nmol and 1 000 nmol induced contralateral rotations of rats. L-AP3, MCPG and dantrolene attenuated the turning effect of tACPD. DHPG, a selective agonist of group I mGluRs, mimicked the effect of tACPD. The effect of DHPG was blocked by MCPG, LY367385 (antagonist of mGluR1) and MPEP (antagonist of mGluR5), and abolished by pretreatment with reserpine (5 mg/kg). CONCLUSION:These results indicated the activation of group I mGluRs in rat striatum induced turning effect, which may be associated with the mobilization of intracellular Ca2+ stores and dependant on the existence of dopamine.%目的:研究代谢型谷氨酸受体(mGluRs)激动剂引起大鼠向对侧旋转时介导的受体亚型。方法:大鼠纹状体内微量注射mGluRs激动剂或拮抗剂,观察大鼠的意识、行为变化,并于给药后6 h测定旋转活动。结果:mGluRs非亚型特异的激动剂tACPD (500、1 000 nmol)纹状体内注射引起大鼠向对侧旋转,mGluRs的非竞争性拮抗剂L-AP3、竞争性拮抗剂MCPG及抑制细胞内钙释放的胆罗啉均可减轻tACPD引起的旋转。I组mGluRs的特异性激动剂DHPG (500 nmol)纹状体内注射也引起大鼠向对侧旋转,MCPG及mGluR1的拮抗剂LY367385 及mGluR5的拮抗剂MPEP均可拮抗DHPG引起的旋转。预先腹腔注射利血平(5 mg/kg)可阻断DHPG的作用。结论:I组mGluRs激动引起大鼠向对侧旋转,此作用可能与细胞内钙释放有关及依赖于多巴胺的存在。

  20. Exploration of allosteric agonism structure-activity relationships within an acetylene series of metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulators (PAMs): discovery of 5-((3-fluorophenyl)ethynyl)-N-(3-methyloxetan-3-yl)picolinamide (ML254).

    Science.gov (United States)

    Turlington, Mark; Noetzel, Meredith J; Chun, Aspen; Zhou, Ya; Gogliotti, Rocco D; Nguyen, Elizabeth D; Gregory, Karen J; Vinson, Paige N; Rook, Jerri M; Gogi, Kiran K; Xiang, Zixiu; Bridges, Thomas M; Daniels, J Scott; Jones, Carrie; Niswender, Colleen M; Meiler, Jens; Conn, P Jeffrey; Lindsley, Craig W; Stauffer, Shaun R

    2013-10-24

    Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 5 (mGlu5) represent a promising therapeutic strategy for the treatment of schizophrenia. Both allosteric agonism and high glutamate fold-shift have been implicated in the neurotoxic profile of some mGlu5 PAMs; however, these hypotheses remain to be adequately addressed. To develop tool compounds to probe these hypotheses, the structure-activity relationship of allosteric agonism was examined within an acetylenic series of mGlu5 PAMs exhibiting allosteric agonism in addition to positive allosteric modulation (ago-PAMs). PAM 38t, a low glutamate fold-shift allosteric ligand (maximum fold-shift ~ 3.0), was selected as a potent PAM with no agonism in the in vitro system used for compound characterization and in two native electrophysiological systems using rat hippocampal slices. PAM 38t (ML254) will be useful to probe the relative contribution of cooperativity and allosteric agonism to the adverse effect liability and neurotoxicity associated with this class of mGlu5 PAMs.

  1. 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...

  2. P/Q-type and T-type calcium channels, but not type 3 transient receptor potential cation channels, are involved in inhibition of dendritic growth after chronic metabotropic glutamate receptor type 1 and protein kinase C activation in cerebellar Purkinje cells.

    Science.gov (United States)

    Gugger, Olivia S; Hartmann, Jana; Birnbaumer, Lutz; Kapfhammer, Josef P

    2012-01-01

    The development of a neuronal dendritic tree is modulated both by signals from afferent fibers and by an intrinsic program. We have previously shown that chronic activation of either type 1 metabotropic glutamate receptors (mGluR1s) or protein kinase C (PKC) in organotypic cerebellar slice cultures of mice and rats severely inhibits the growth and development of the Purkinje cell dendritic tree. The signaling events linking receptor activation to the regulation of dendritic growth remain largely unknown. We have studied whether channels allowing the entry of Ca(2+) into Purkinje cells, in particular the type 3 transient receptor potential cation channels (TRPC3s), P/Q-type Ca(2+) channels, and T-type Ca(2+) channels, might be involved in signaling after mGluR1 or PKC stimulation. We show that the inhibition of dendritic growth seen after mGluR1 or PKC stimulation is partially rescued by pharmacological blockade of P/Q-type and T-type Ca(2+) channels, indicating that activation of these channels mediating Ca(2+) influx contributes to the inhibition of dendritic growth. In contrast, the absence of Ca(2+) -permeable TRPC3s in TRPC3-deficient mice or pharmacological blockade had no effect on mGluR1-mediated and PKC-mediated inhibition of Purkinje cell dendritic growth. Similarly, blockade of Ca(2+) influx through glutamate receptor δ2 or R-type Ca(2+) channels or inhibition of release from intracellular stores did not influence mGluR1-mediated and PKC-mediated inhibition of Purkinje cell dendritic growth. These findings suggest that both T-type and P/Q-type Ca(2+) channels, but not TRPC3 or other Ca(2+) -permeable channels, are involved in mGluR1 and PKC signaling leading to the inhibition of dendritic growth in cerebellar Purkinje cells.

  3. Alcohol drinking increases the dopamine-stimulating effects of ethanol and reduces D2 auto-receptor and group II metabotropic glutamate receptor function within the posterior ventral tegmental area of alcohol preferring (P) rats.

    Science.gov (United States)

    Ding, Zheng-Ming; Ingraham, Cynthia M; Rodd, Zachary A; McBride, William J

    2016-10-01

    Repeated local administration of ethanol (EtOH) sensitized the posterior ventral tegmental area (pVTA) to the local dopamine (DA)-stimulating effects of EtOH. Chronic alcohol drinking increased nucleus accumbens (NAC) DA transmission and pVTA glutamate transmission in alcohol-preferring (P) rats. The objectives of the present study were to determine the effects of chronic alcohol drinking by P rats on the (a) sensitivity and response of the pVTA DA neurons to the DA-stimulating actions of EtOH, and (b) negative feedback control of DA (via D2 auto-receptors) and glutamate (via group II mGlu auto-receptors) release in the pVTA. EtOH (50 or 150 mg%) or the D2/3 receptor antagonist sulpiride (100 or 200 μM) was microinjected into the pVTA while DA was sampled with microdialysis in the NAC shell (NACsh). The mGluR2/3 antagonist LY341495 (1 or 10 μM) was perfused through the pVTA via reverse microdialysis and local extracellular glutamate and DA levels were measured. EtOH produced a more robust increase of NACsh DA in the 'EtOH' than 'Water' groups (e.g., 150 mg% EtOH: to ∼ 210 vs 150% of baseline). In contrast, sulpiride increased DA release in the NACsh more in the 'Water' than 'EtOH' groups (e.g., 200 μM sulpiride: to ∼ 190-240 vs 150-160% of baseline). LY341495 (at 10 μM) increased extracellular glutamate and DA levels in the 'Water' (to ∼ 150-180% and 180-230% of baseline, respectively) but not the 'EtOH' groups. These results indicate that alcohol drinking enhanced the DA-stimulating effects of EtOH, and attenuated the functional activities of D2 auto-receptors and group II mGluRs within the pVTA. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Acid-sensing ion channel 1a is required for mGlu receptor dependent long-term depression in the hippocampus.

    Science.gov (United States)

    Mango, D; Braksator, E; Battaglia, G; Marcelli, S; Mercuri, N B; Feligioni, M; Nicoletti, F; Bashir, Z I; Nisticò, R

    2017-01-27

    Acid-sensing ion channels (ASICs), members of the degenerin/epithelial Na(+) channel superfamily, are widely distributed in the mammalian nervous system. ASIC1a is highly permeable to Ca(2+) and are thought to be important in a variety of physiological processes, including synaptic plasticity, learning and memory. To further understand the role of ASIC1a in synaptic transmission and plasticity, we investigated metabotropic glutamate (mGlu) receptor-dependent long-term depression (LTD) in the hippocampus. We found that ASIC1a channels mediate a component of LTD in P30-40 animals, since the ASIC1a selective blocker psalmotoxin-1 (PcTx1) reduced the magnitude of LTD induced by application of the group I mGlu receptor agonist (S)-3,5-Dihydroxyphenylglycine (DHPG) or induced by paired-pulse low frequency stimulation (PP-LFS). Conversely, PcTx1 did not affect LTD in P13-18 animals. We also provide evidence that ASIC1a is involved in group I mGlu receptor-induced increase in action potential firing. However, blockade of ASIC1a did not affect DHPG-induced polyphosphoinositide hydrolysis, suggesting the involvement of some other molecular partners in the functional crosstalk between ASIC1a and group I mGlu receptors. Notably, PcTx1 was able to prevent the increase in GluA1 S845 phosphorylation at the post-synaptic membrane induced by group I mGlu receptor activation. These findings suggest a novel function of ASIC1a channels in the regulation of group I mGlu receptor synaptic plasticity and intrinsic excitability.

  5. N-(4-((2-(trifluoromethyl)-3-hydroxy-4-(isobutyryl)phenoxy)methyl)benzyl)-1-methyl-1H-imidazole-4-carboxamide (THIIC), a novel metabotropic glutamate 2 potentiator with potential anxiolytic/antidepressant properties: in vivo profiling suggests a link between behavioral and central nervous system neurochemical changes.

    Science.gov (United States)

    Fell, Matthew J; Witkin, Jeffrey M; Falcone, Julie F; Katner, Jason S; Perry, Kenneth W; Hart, John; Rorick-Kehn, Linda; Overshiner, Carl D; Rasmussen, Kurt; Chaney, Stephen F; Benvenga, Mark J; Li, Xia; Marlow, Deanna L; Thompson, Linda K; Luecke, Susan K; Wafford, Keith A; Seidel, Wesley F; Edgar, Dale M; Quets, Anne T; Felder, Christian C; Wang, XuShan; Heinz, Beverly A; Nikolayev, Alexander; Kuo, Ming-Shang; Mayhugh, Daniel; Khilevich, Albert; Zhang, Deyi; Ebert, Philip J; Eckstein, James A; Ackermann, Bradley L; Swanson, Steven P; Catlow, John T; Dean, Robert A; Jackson, Kimberley; Tauscher-Wisniewski, Sitra; Marek, Gerard J; Schkeryantz, Jeffrey M; Svensson, Kjell A

    2011-01-01

    The normalization of excessive glutamatergic neurotransmission through the activation of metabotropic glutamate 2 (mGlu2) receptors may have therapeutic potential in a variety of psychiatric disorders, including anxiety/depression and schizophrenia. Here, we characterize the pharmacological properties of N-(4-((2-(trifluoromethyl)-3-hydroxy-4-(isobutyryl)phenoxy)methyl)benzyl)-1-methyl-1H-imidazole-4-carboxamide (THIIC), a structurally novel, potent, and selective allosteric potentiator of human and rat mGlu2 receptors (EC(50) = 23 and 13 nM, respectively). THIIC produced anxiolytic-like efficacy in the rat stress-induced hyperthermia assay and the mouse stress-induced elevation of cerebellar cGMP and marble-burying assays. THIIC also produced robust activity in three assays that detect antidepressant-like activity, including the mouse forced-swim test, the rat differential reinforcement of low rate 72-s assay, and the rat dominant-submissive test, with a maximal response similar to that of imipramine. Effects of THIIC in the forced-swim test and marble burying were deleted in mGlu2 receptor null mice. Analysis of sleep electroencephalogram (EEG) showed that THIIC had a sleep-promoting profile with increased non-rapid eye movement (REM) and decreased REM sleep. THIIC also decreased the dark phase increase in extracellular histamine in the medial prefrontal cortex and decreased levels of the histamine metabolite tele-methylhistamine (t-MeHA) in rat cerebrospinal fluid. Collectively, these results indicate that the novel mGlu2-positive allosteric modulator THIIC has robust activity in models used to predict anxiolytic/antidepressant efficacy, substantiating, at least with this molecule, differentiation in the biological impact of mGlu2 potentiation versus mGlu2/3 orthosteric agonism. In addition, we provide evidence that sleep EEG and CSF t-MeHA might function as viable biomarker approaches to facilitate the translational development of THIIC and other mGlu2

  6. Comparative Effects of LY3020371, a Potent and Selective Metabotropic Glutamate (mGlu) 2/3 Receptor Antagonist, and Ketamine, a Noncompetitive N-Methyl-d-Aspartate Receptor Antagonist in Rodents: Evidence Supporting the Use of mGlu2/3 Antagonists, for the Treatment of Depression.

    Science.gov (United States)

    Witkin, J M; Mitchell, S N; Wafford, K A; Carter, G; Gilmour, G; Li, J; Eastwood, B J; Overshiner, C; Li, X; Rorick-Kehn, L; Rasmussen, K; Anderson, W H; Nikolayev, A; Tolstikov, V V; Kuo, M-S; Catlow, J T; Li, R; Smith, S C; Mitch, C H; Ornstein, P L; Swanson, S; Monn, J A

    2017-04-01

    The ability of the N-methyl-d-aspartate receptor antagonist ketamine to alleviate symptoms in patients suffering from treatment-resistant depression (TRD) is well documented. In this paper, we directly compare in vivo biologic responses in rodents elicited by a recently discovered metabotropic glutamate (mGlu) 2/3 receptor antagonist 2-amino-3-[(3,4-difluorophenyl)sulfanylmethyl]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY3020371) with those produced by ketamine. Both LY3020371 and ketamine increased the number of spontaneously active dopamine cells in the ventral tegmental area of anesthetized rats, increased O2 in the anterior cingulate cortex, promoted wakefulness, enhanced the efflux of biogenic amines in the prefrontal cortex, and produced antidepressant-related behavioral effects in rodent models. The ability of LY3020371 to produce antidepressant-like effects in the forced-swim assay in rats was associated with cerebrospinal fluid (CSF) drug levels that matched concentrations required for functional antagonist activity in native rat brain tissue preparations. Metabolomic pathway analyses from analytes recovered from rat CSF and hippocampus demonstrated that both LY3020371 and ketamine activated common pathways involving GRIA2 and ADORA1. A diester analog of LY3020371 [bis(((isopropoxycarbonyl)oxy)-methyl) (1S,2R,3S,4S,5R,6R)-2-amino-3-(((3,4-difluorophenyl)thio)methyl)-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylate (LY3027788)] was an effective oral prodrug; when given orally, it recapitulated effects of intravenous doses of LY3020371 in the forced-swim and wake-promotion assays, and augmented the antidepressant-like effects of fluoxetine or citalopram without altering plasma or brain levels of these compounds. The broad overlap of biologic responses produced by LY3020371 and ketamine supports the hypothesis that mGlu2/3 receptor blockade might be a novel therapeutic approach for the treatment of TRD patients. LY3020371 and LY3027788 represent

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

    Science.gov (United States)

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

    2014-06-01

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

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  9. Involvement of cAMP-PKA pathway in group Ⅱ metabotropic glutamate receptors-mediated regulation of respiratory rhythm from neonatal rat brainstem slice%cAMP-PKA通路参与Ⅱ组代谢性谷氨酸受体对新生鼠离体延髓脑片呼吸节律性放电的调节

    Institute of Scientific and Technical Information of China (English)

    郑奇辉; 李国才; 程静; 方芳; 吴中海

    2011-01-01

    本研究旨在探讨cAMP-PKA通路在Ⅱ组代谢性谷氨酸受体对离体延髓脑片呼吸节律性放电的影响中的作用.制作新生大鼠离体延髓脑片标本,主要包含延髓面神经后核内侧区(medial region of the nucleus retrofacialis,mNRF),并完整保留舌下神经根,以改良Kreb's液(modified Kreb's solution,MKS)恒温灌流脑片,用吸附电极记录舌下神经根呼吸节律性放电活动(respiratory rhythmical discharge activity,RRDA).待放电活动稳定后,第1组灌流Ⅱ组代谢性谷氨酸受体特异性拮抗剂(2S)-a-ethylglutamic acid(EGLU)10 min,第2组先给予cAMP-PKA通路激动剂Forskolin灌流10 min,而后MKS洗脱至正常,灌流cAMP-PKA通路抑制剂Rp-cyclic 3',5'-hydrogen phosphorothioate adenosine triethylammonium salt(Rp-cAMPS)10 min,第3组首先给予Rp-cAMPS 10 min,洗脱后联合Rp-cAMPS+EGLU持续灌流10 min,记录各组各时间点RRDA的变化.结果显示,给予Ⅱ组代谢性谷氨酸受体拮抗剂EGLU后,呼吸周期(respiratory cycle,RC)缩短,放电积分幅度(integral amplitude,IA)和吸气时程(inspiratory time,TI)没有变化;Forskolin兴奋呼吸,缩短RC,增加IA,延长TI;Rp-cAMPS则延长RC,降低IA,缩短TI;并且cAMP-PKA通路被阻断之后,EGLU缩短RC的效应也被抑制.这些结果提示在离体延髓水平上,cAMP-PKA通路参与了Ⅱ组代谢性谷氨酸受体对脑片呼吸节律性放电的调节.%The study aims to identify the role of cAMP-PKA pathway in the group II metabotropic glutamate receptors (mGluRs)-mediated regulation of respiratory rhythm from the brainstem slice. Neonatal (aged 0-3 d) Sprague-Dawley rats of either sex were used. The brainstem slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared, and the surgical procedure was performed in the modified Kreb's solution (MK.S) with continuous carbogen (95% O2 and 5% CO2) bubbling, and ended in 3 min. Respiratory rhythmical discharge activity

  10. Modulation of glutamate transport and receptor binding by glutamate receptor antagonists in EAE rat brain.

    Science.gov (United States)

    Sulkowski, Grzegorz; Dąbrowska-Bouta, Beata; Salińska, Elżbieta; Strużyńska, Lidia

    2014-01-01

    The etiology of multiple sclerosis (MS) is currently unknown. However, one potential mechanism involved in the disease may be excitotoxicity. The elevation of glutamate in cerebrospinal fluid, as well as changes in the expression of glutamate receptors (iGluRs and mGluRs) and excitatory amino acid transporters (EAATs), have been observed in the brains of MS patients and animals subjected to experimental autoimmune encephalomyelitis (EAE), which is the predominant animal model used to investigate the pathophysiology of MS. In the present paper, the effects of glutamatergic receptor antagonists, including amantadine, memantine, LY 367583, and MPEP, on glutamate transport, the expression of mRNA of glutamate transporters (EAATs), the kinetic parameters of ligand binding to N-methyl-D-aspartate (NMDA) receptors, and the morphology of nerve endings in EAE rat brains were investigated. The extracellular level of glutamate in the brain is primarily regulated by astrocytic glutamate transporter 1 (GLT-1) and glutamate-aspartate transporter (GLAST). Excess glutamate is taken up from the synaptic space and metabolized by astrocytes. Thus, the extracellular level of glutamate decreases, which protects neurons from excitotoxicity. Our investigations showed changes in the expression of EAAT mRNA, glutamate transport (uptake and release) by synaptosomal and glial plasmalemmal vesicle fractions, and ligand binding to NMDA receptors; these effects were partially reversed after the treatment of EAE rats with the NMDA antagonists amantadine and memantine. The antagonists of group I metabotropic glutamate receptors (mGluRs), including LY 367385 and MPEP, did not exert any effect on the examined parameters. These results suggest that disturbances in these mechanisms may play a role in the processes associated with glutamate excitotoxicity and the progressive brain damage in EAE.

  11. Glutamate-mediated protection of crayfish glial cells from PDT-induced apoptosis

    Science.gov (United States)

    Rudkovskii, M. V.; Romanenko, N. P.; Berezhnaya, E. V.; Kovaleva, V. D.; Uzdensky, A. B.

    2011-03-01

    Photodynamic treatment that causes intense oxidative stress and kills cells is currently used in neurooncology. However, along with tumor it damages surrounding healthy neurons and glial cells. In order to study the possible role of glutamate-related signaling pathways in photodynamic injury of neurons and glia, we investigated photodynamic effect of alumophthalocyanine Photosens on isolated crayfish stretch receptor that consists of a single neuron surrounded by glial cells. The laser diode (670 nm, 0.4 W/cm2) was used for dye photoexcitation. Application of glutamate increased photodynamically induced necrosis of neurons and glial cells but significantly decreased glial apoptosis. The natural neuroglial mediator N-acetylaspartylglutamate, which releases glutamate after cleavage in the extracellular space by glutamate carboxypeptidase II, also inhibited photoinduced apoptosis. Inhibition of glutamate carboxypeptidase II, oppositely, enhanced apoptosis of glial cells. These data confirm the anti-apoptotic activity of glutamate. Application of NMDA or inhibition of NMDA receptors by MK801 did not influence photodynamic death of neurons and glial cells that indicated nonparticipation of NMDA receptors in these processes. Inhibition of metabotropic glutamate receptors by AP-3 decreased PDT-induced apoptosis. One can suggest that crayfish neurons naturally secrete NAAG, which being cleaved by GCOP produces glutamate. Glutamate prevents photoinduced apoptosis of glial cells possibly through metabotropic but not ionotropic glutamate receptors.

  12. Glutamate receptor ligands

    DEFF Research Database (Denmark)

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

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA......-ray crystallographic analyses, chemical correlation, and CD spectral analyses. The effects of the individual stereoisomers at ionotropic and metabotropic (S)-Glu receptors (iGluRs and mGluRs) were characterized. Compounds with S-configuration at the alpha-carbon generally showed mGluR2 agonist activity of similar...... limited effect on pharmacology. Structure-activity relationships at iGluRs in the rat cortical wedge preparation showed a complex pattern, some compounds being NMDA receptor agonists [e.g., EC(50) =110 microM for (2S,5RS)-5-methyl-AA (6a,b)] and some compounds showing NMDA receptor antagonist effects [e...

  13. Neuregulin and BDNF induce a switch to NMDA receptor-dependent myelination by oligodendrocytes.

    Directory of Open Access Journals (Sweden)

    Iben Lundgaard

    2013-12-01

    Full Text Available Myelination is essential for rapid impulse conduction in the CNS, but what determines whether an individual axon becomes myelinated remains unknown. Here we show, using a myelinating coculture system, that there are two distinct modes of myelination, one that is independent of neuronal activity and glutamate release and another that depends on neuronal action potentials releasing glutamate to activate NMDA receptors on oligodendrocyte lineage cells. Neuregulin switches oligodendrocytes from the activity-independent to the activity-dependent mode of myelination by increasing NMDA receptor currents in oligodendrocyte lineage cells 6-fold. With neuregulin present myelination is accelerated and increased, and NMDA receptor block reduces myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. In vivo, we demonstrate that remyelination after white matter damage is NMDA receptor-dependent. These data resolve controversies over the signalling regulating myelination and suggest novel roles for neuregulin in schizophrenia and in remyelination after white matter damage.

  14. Kynurenines and Glutamate: Multiple Links and Therapeutic Implications.

    Science.gov (United States)

    Schwarcz, R

    2016-01-01

    Glutamate is firmly established as the major excitatory neurotransmitter in the mammalian brain and is actively involved in most aspects of neurophysiology. Moreover, glutamatergic impairments are associated with a wide variety of dysfunctional states, and both hypo- and hyperfunction of glutamate have been plausibly linked to the pathophysiology of neurological and psychiatric diseases. Metabolites of the kynurenine pathway (KP), the major catabolic route of the essential amino acid tryptophan, influence glutamatergic activity in several distinct ways. This includes direct effects of these "kynurenines" on ionotropic and metabotropic glutamate receptors or vesicular glutamate transport, and indirect effects, which are initiated by actions at various other recognition sites. In addition, some KP metabolites affect glutamatergic functions by generating or scavenging highly reactive free radicals. This review summarizes these phenomena and discusses implications for brain physiology and pathology.

  15. 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.

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

    Science.gov (United States)

    Mita, Masatoshi

    2016-12-22

    l-Glutamic acid was previously identified as an inhibitor of spawning in the starfish Patiria (Asterina) pectinifera; this study examined how l-glutamic acid works. Oocyte release from ovaries of P. pectinifera occurred after germinal vesicle breakdown (GVBD) and follicular envelope breakdown (FEBD) when gonads were incubated ex vivo with either relaxin-like gonad-stimulating peptide (RGP) or 1-methyladenine (1-MeAde). l-Glutamic acid blocked this spawning phenotype, causing the mature oocytes to remain within the ovaries. Neither RGP-induced 1-MeAde production in ovarian follicle cells nor 1-MeAde-induced GVBD and FEBD was affected by l-glutamic acid. l-Glutamic acid may act through metabotropic receptors in the ovaries to inhibit spawning, as l-(+)-2-amino-4-phosphonobutyric acid, an agonist for metabotropic glutamate receptors, also inhibited spawning induced by 1-MeAde. Application of acetylcholine (ACH) to ovaries under inhibitory conditions with l-glutamic acid, however, brought about spawning, possibly by inducing contraction of the ovarian wall to discharge mature oocytes from the ovaries concurrently with GVBD and FEBD. Thus, l-glutamic acid may inhibit ACH secretion from gonadal nerve cells in the ovary. Mol. Reprod. Dev. 2016. © 2016 Wiley Periodicals, Inc.

  17. Receptor-Dependent Coronavirus Infection of Dendritic Cells

    Science.gov (United States)

    Turner, Brian C.; Hemmila, Erin M.; Beauchemin, Nicole; Holmes, Kathryn V.

    2004-01-01

    In several mammalian species, including humans, coronavirus infection can modulate the host immune response. We show a potential role of dendritic cells (DC) in murine coronavirus-induced immune modulation and pathogenesis by demonstrating that the JAW SII DC line and primary DC from BALB/c mice and p/p mice with reduced expression of the murine coronavirus receptor, murine CEACAM1a, are susceptible to murine coronavirus infection by a receptor-dependent pathway. PMID:15113927

  18. Switching off LTP: mGlu and NMDA receptor-dependent novelty exploration-induced depotentiation in the rat hippocampus.

    Science.gov (United States)

    Qi, Yingjie; Hu, Neng-Wei; Rowan, Michael J

    2013-04-01

    Both electrically induced synaptic long-term potentiation (LTP) and long-term depression have been extensively studied as models of the cellular basis of learning and memory mechanisms. Recently, considerable interest has been generated by the possibility that the activity-dependent persistent reversal of previously established synaptic LTP (depotentiation) may play a role in the time- and state-dependent erasure of memory. Here, we examined the requirement for glutamate receptor activation in experience-induced reversal of previously established LTP in the CA1 area of the hippocampus of freely behaving rats. Continuous exploration of non-aversive novelty for ~30 min, which was associated with hippocampal activation as measured by increased theta power in the electroencephalogram, triggered a rapid and persistent reversal of high frequency stimulation-induced LTP both at apical and basal synapses. Blockade of metabotropic glutamate (mGlu) receptors with mGlu5 subtype-selective antagonists, or N-methyl-D-aspartate (NMDA) receptors with GluN2B subunit-selective antagonists, prevented novelty-induced depotentiation. These findings strongly indicate that activation of both mGlu5 receptors and GluN2B-containing NMDA receptors is required for experience-triggered induction of depotentiation at CA3-CA1 synapses. The mechanistic concordance of the present and previous studies of experience-induced and electrically induced synaptic depotentiation helps to integrate our understanding of the neurophysiological underpinnings of learning and memory.

  19. Activation of both Group I and Group II metabotropic glutamatergic receptors suppress retinogeniculate transmission.

    Science.gov (United States)

    Lam, Y-W; Sherman, S M

    2013-07-09

    Relay cells of dorsal lateral geniculate nucleus (LGN) receive a Class 1 glutamatergic input from the retina and a Class 2 input from cortical layer 6. Among the properties of Class 2 synapses is the ability to activate metabotropic glutamate receptors (mGluRs), and mGluR activation is known to affect thalamocortical transmission via regulating retinogeniculate and thalamocortical synapses. Using brain slices, we studied the effects of Group I (dihydroxyphenylglycine) and Group II ((2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine) mGluR agonists on retinogeniculate synapses. We showed that both agonists inhibit retinogeniculate excitatory postsynaptic currents (EPSCs) through presynaptic mechanisms, and their effects are additive and independent. We also found high-frequency stimulation of the layer 6 corticothalamic input produced a similar suppression of retinogeniculate EPSCs, suggesting layer 6 projection to LGN as a plausible source of activating these presynaptic mGluRs.

  20. Posttranslational Modification Biology of Glutamate Receptors and Drug Addiction

    Directory of Open Access Journals (Sweden)

    Li-Min eMao

    2011-03-01

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

  1. Activation of group Ⅰ metabotropic glutamate receptors modulates descending activation of spinal cord motoneurons%Ⅰ组代谢型谷氨酸受体激活调制脊髓运动神经元的下行激活

    Institute of Scientific and Technical Information of China (English)

    郑勇; 汪萌芽

    2011-01-01

    AIM: To evaluate the modulatory action of group I metabotropic glutaraate receptors (mGluRs) on descending activation of spinal cord motoneurons (MNs) in vitro. METHODS; The intracellular recordings were made in MNs of spinal cord slices isolated from neonatal rats (7-14 days old) , and excitatory postsynap-tic potential (EPSP) was evoked by ipsilateral ventrolateral funiculus (iVLF) stimulation, I. e. iVLF-EPSP. By superfusion of (S)-3, 5-di-hydroxyphenylglycine hydrate (DHPG) , an agonist of group I mGluRs, the modulatory action was observed on the MN membrane electrical properties, as well as on the iVLF-EPSP. RESULTS: Application of DHPG (5 pmol/L) significantly depolarized the motoneuron membrane(n = 7, P<0. 01), reduced time constant (n = 7, P<0. 05), and extended the half-width of the spike potential (n = 5, P

  2. 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...

  3. 背根神经节内代谢型谷氨酸受体2与酸敏感性离子通道3和辣椒素受体1的共存研究%Co-localization of metabotropic glutamate receptor 2 with ASIC3 or TRPV1 in the dorsal root

    Institute of Scientific and Technical Information of China (English)

    张婷; 王旭翾; 张靖; 史娟; 李会莉; 李云庆

    2008-01-01

    Metabotropie glutamate receptor (mGluR) 2/3 plays an important role on the nociceptive transmission from periphery to spinal cord.The previous studies demonstrated that mGluR2 can contribute to mechanical hypersensitivity and thermal hypersensitivity in rat.Therefore,in the present study,by using the immunofluorescenee histochemical technique,we try to explore that whether mGluR2 is colocalized with acid-sensing ion channel 3 (ASIC3),a muhi-modulator of mechanosensation,or transient receptor potential/vanilloid receptor subtype-1 (TRPV1),which responses for thermosensation in dorsal root ganglion (DRG).Morphological observations showed that mGluR2-immunoreactivity was mainly distributed in cellular plasma of neurons in DRG.The counting number results indicated that 35.84% of DRG neurons were mGluR2-immunoreactive (ir).On the other hand,82.61% of mGluR2-ir cells were the small-diameter neurons (diameter:<30 μm),5.79% of which were the medium-diameter neurons (diameter:30-50μm) and 11.59% of which was the large-diameter neurons (diameter:>50 tun).Furthermore,42.45% and 79.78% of mGiuR2-ir cells was individually co-localized with ASIC3-or TRPVI-ir in small-diameter neurons in the double-labeled immunofluorescence sections.The present results suggest that mGhiR2 mainly exists in small neurons of the DRG,which are regarded as nociceptors consisting of AS-and C-fibers.While mGluR2 is highly co-localized with ASIC3 and TRPV1,implying their potential relationship in DRG may be involved in mechanical hypersensitivity and thermal hypersensitivity.%代谢型谷氨酸受体(mGluR)2/3在伤害性信息从外周向脊髓传递的过程中发挥着重要作用.以往研究证明在大鼠中mGluR2参与了机械性超敏和热超敏的形成,因此本研究拟采用免疫荧光组织化学染色技术揭示背根节(DRG)中mGluR2和酸敏感性离子通道3(ASIC3),一个多觉机械性感受器,或者和热伤害性感受器辣椒素受体(TRPV1)的共存情

  4. L-Glutamate supplementation improves small intestinal architecture and enhances the expressions of jejunal mucosa amino acid receptors and transporters in weaning piglets.

    Directory of Open Access Journals (Sweden)

    Meng Lin

    Full Text Available L-Glutamate is a major oxidative fuel for the small intestine. However, few studies have demonstrated the effect of L-glutamate on the intestinal architecture and signaling of amino acids in the small intestine. The aim of this study was to investigate the effects of dietary L-glutamate supplementation on the intestinal architecture and expressions of jejunal mucosa amino acid receptors and transporters in weaning piglets. A total of 120 weaning piglets aged 35 ± 1 days with an average body weight at 8.91 ± 0.45 kg were randomly allocated to two treatments with six replicates of ten piglets each, fed with diets containing 1.21% alanine, or 2% L-glutamate. L-Glutamate supplementation increased the activity of glutamate oxaloacetate transaminase (GOT in the jejunal mucosa. Also, the mRNA expression level of jejunal mucosa glutamine synthetase (GS was increased by L-glutamate supplementation. The height of villi in duodenal and jejunal segments, and the relative mRNA expression of occludin and zonula occludens protein-1 (ZO-1 in jejunal mucosa were increased by dietary L-glutamate supplementation. L-Glutamate supplementation increased plasma concentrations of glutamate, arginine, histidine, isoleucine, leucine, methionine, phenylalanine and threonine. L-Glutamate supplementation also increased the relative mRNA expression of the jejunal mucosa Ca(2+-sensing receptor (CaR, metabotropic glutamate receptor 1 (mGluR1 and metabotropic glutamate receptor 4 (mGluR4, and neutral amino acid transporter B(0-like (SLC1A5 in the jejunal mucosa. These findings suggest that dietary addition of 2% L-glutamate improves the intestinal integrity and influences the expression of amino acid receptors and transporters in the jejunum of weaning, which is beneficial for the improvement of jejunal nutrients for digestion and absorption.

  5. Intracellular calcium level is an important factor influencing ion channel modulations by PLC-coupled metabotropic receptors in hippocampal neurons.

    Science.gov (United States)

    Sugawara, Yuto; Echigo, Ryousuke; Kashima, Kousuke; Minami, Hanae; Watanabe, Megumi; Nishikawa, Yuiko; Muranishi, Miho; Yoneda, Mitsugu; Ohno-Shosaku, Takako

    2013-05-28

    Signaling pathways involving phospholipase C (PLC) are involved in various neural functions. Understanding how these pathways are regulated will lead to a better understanding of their roles in neural functions. Previous studies demonstrated that receptor-driven PLCβ activation depends on intracellular Ca(2+) concentration ([Ca(2+)]i), suggesting the possibility that PLCβ-dependent cellular responses are basically Ca(2+) dependent. To test this possibility, we examined whether modulations of ion channels driven by PLC-coupled metabotropic receptors are sensitive to [Ca(2+)]i using cultured hippocampal neurons. Muscarinic activation triggered an inward current at -100 mV (the equilibrium potential for K(+)) in a subpopulation of neurons. This current response was suppressed by pirenzepine (an M1-preferring antagonist), PLC inhibitor, non-selective cation channel blocker, and lowering [Ca(2+)]i. Using the neurons showing no response at -100 mV, effects of muscarinic activation on K(+) channels were examined at -40 mV. Muscarinic activation induced a transient decrease of the holding outward current. This current response was mimicked and occluded by XE991, an M-current K(+) channel blocker, suppressed by pirenzepine, PLC inhibitor and lowering [Ca(2+)]i, and enhanced by elevating [Ca(2+)]i. Similar results were obtained when group I metabotropic glutamate receptors were activated instead of muscarinic receptors. These results clearly show that ion channel modulations driven by PLC-coupled metabotropic receptors are dependent on [Ca(2+)]i, supporting the hypothesis that cellular responses induced by receptor-driven PLCβ activation are basically Ca(2+) dependent.

  6. Simulation of postsynaptic glutamate receptors reveals critical features of glutamatergic transmission.

    Directory of Open Access Journals (Sweden)

    Renaud Greget

    Full Text Available Activation of several subtypes of glutamate receptors contributes to changes in postsynaptic calcium concentration at hippocampal synapses, resulting in various types of changes in synaptic strength. Thus, while activation of NMDA receptors has been shown to be critical for long-term potentiation (LTP and long term depression (LTD of synaptic transmission, activation of metabotropic glutamate receptors (mGluRs has been linked to either LTP or LTD. While it is generally admitted that dynamic changes in postsynaptic calcium concentration represent the critical elements to determine the direction and amplitude of the changes in synaptic strength, it has been difficult to quantitatively estimate the relative contribution of the different types of glutamate receptors to these changes under different experimental conditions. Here we present a detailed model of a postsynaptic glutamatergic synapse that incorporates ionotropic and mGluR type I receptors, and we use this model to determine the role of the different receptors to the dynamics of postsynaptic calcium with different patterns of presynaptic activation. Our modeling framework includes glutamate vesicular release and diffusion in the cleft and a glutamate transporter that modulates extracellular glutamate concentration. Our results indicate that the contribution of mGluRs to changes in postsynaptic calcium concentration is minimal under basal stimulation conditions and becomes apparent only at high frequency of stimulation. Furthermore, the location of mGluRs in the postsynaptic membrane is also a critical factor, as activation of distant receptors contributes significantly less to calcium dynamics than more centrally located ones. These results confirm the important role of glutamate transporters and of the localization of mGluRs in postsynaptic sites in their signaling properties, and further strengthen the notion that mGluR activation significantly contributes to postsynaptic calcium

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

    Directory of Open Access Journals (Sweden)

    Xinglong Gu

    2016-01-01

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

  8. Glycine Potentiates AMPA Receptor Function through Metabotropic Activation of GluN2A-containing NMDA Receptors

    Directory of Open Access Journals (Sweden)

    Li-Jun Li

    2016-10-01

    Full Text Available NMDA receptors are Ca2+-permeable ion channels. The activation of NMDA receptors requires agonist glutamate and co-agonist glycine. Recent evidence indicates that NMDA receptor also has metabotropic function. Here we report that in cultured mouse hippocampal neurons, glycine increases AMPA receptor-mediated currents independent of the channel activity of NMDA receptors and the activation of glycine receptors. The potentiation of AMPA receptor function by glycine is antagonized by the inhibition of ERK1/2. In the hippocampal neurons and in the HEK293 cells transfected with different combinations of NMDA receptors, glycine preferentially acts on GluN2A-containing NMDA receptors (GluN2ARs, but not GluN2B-containing NMDA receptors (GluN2BRs, to enhance ERK1/2 phosphorylation independent of the channel activity of GluN2ARs. Without requiring the channel activity of GluN2ARs, glycine increases AMPA receptor-mediated currents through GluN2ARs. Thus, these results reveal a metabotropic function of GluN2ARs in mediating glycine-induced potentiation of AMPA receptor function via ERK1/2 activation.

  9. Glycine Potentiates AMPA Receptor Function through Metabotropic Activation of GluN2A-Containing NMDA Receptors

    Science.gov (United States)

    Li, Li-Jun; Hu, Rong; Lujan, Brendan; Chen, Juan; Zhang, Jian-Jian; Nakano, Yasuko; Cui, Tian-Yuan; Liao, Ming-Xia; Chen, Jin-Cao; Man, Heng-Ye; Feng, Hua; Wan, Qi

    2016-01-01

    NMDA receptors are Ca2+-permeable ion channels. The activation of NMDA receptors requires agonist glutamate and co-agonist glycine. Recent evidence indicates that NMDA receptor also has metabotropic function. Here we report that in cultured mouse hippocampal neurons, glycine increases AMPA receptor-mediated currents independent of the channel activity of NMDA receptors and the activation of glycine receptors. The potentiation of AMPA receptor function by glycine is antagonized by the inhibition of ERK1/2. In the hippocampal neurons and in the HEK293 cells transfected with different combinations of NMDA receptors, glycine preferentially acts on GluN2A-containing NMDA receptors (GluN2ARs), but not GluN2B-containing NMDA receptors (GluN2BRs), to enhance ERK1/2 phosphorylation independent of the channel activity of GluN2ARs. Without requiring the channel activity of GluN2ARs, glycine increases AMPA receptor-mediated currents through GluN2ARs. Thus, these results reveal a metabotropic function of GluN2ARs in mediating glycine-induced potentiation of AMPA receptor function via ERK1/2 activation.

  10. Downregulation of postsynaptic density-95-interacting regulator of spine morphogenesis reduces glutamate-induced excitotoxicity by differentially regulating glutamate receptors in rat cortical neurons.

    Science.gov (United States)

    Luo, Peng; Yang, Yuefan; Liu, Wei; Rao, Wei; Bian, Huan; Li, Xin; Chen, Tao; Liu, Mengdong; Zhao, Yongbo; Dai, Shuhui; Yan, Xu; Fei, Zhou

    2013-12-01

    Glutamate-induced excitotoxicity is involved in many neurological diseases. Preso, a novel postsynaptic scaffold protein, mediates excitatory synaptic transmission and various synaptic functions. In this study, we investigated the role of Preso in the regulation of glutamate-induced excitotoxicity in rat cortical neurons. Knockdown of Preso with small interfering RNA improved neuronal viability and attenuated the elevation of lactate dehydrogenase (LDH) release after glutamate treatment. Downregulation of Preso also inhibited an increase in the BAX/Bcl-2 ratio and cleavage of caspase-9 and caspase-3. Although the expression and distribution of metabotropic glutamate receptor (mGluR) 1/5, NR1, NR2A and NR2B were not changed by knockdown of Preso, downregulation of Preso protected neurons from glutamate-induced excitotoxicity by inhibiting mGluR and N-methyl-D-aspartate receptor function. However, downregulation of Preso neither affected the expression of GluR1 and GluR2 nor influenced the function of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor after glutamate treatment. Furthermore, intracellular Ca(2+) was an important downstream effector of Preso in the regulation of excitotoxicity. These results suggest that expression of Preso promotes the induction of excitotoxicity by facilitating different glutamate receptor signaling pathways. Therefore, Preso might be a potential pharmacological target for preventing and treating neurological diseases.

  11. Discovery and characterization of non-competitive antagonists of group I metabotropic glutamate receptors.

    Science.gov (United States)

    Gasparini, F; Floersheim, P; Flor, P J; Heinrich, M; Inderbitzin, W; Ott, D; Pagano, A; Stierlin, C; Stoehr, N; Vranesic, I; Kuhn, R

    2001-01-01

    We have investigated the mechanism of inhibition of the new group I mGluR antagonists CPCCOEt and MPEP and determined that both compounds have a non-competitive mode of inhibition. Furthermore using chimeric/mutated receptors constructs we have found that these antagonists act at a novel pharmacological site located in the trans-membrane (TM). Specific non-conserved amino acid residues in the TM domain have been identified which are necessary for the inhibition by CPCCOEt and MPEP of the mGlul and mGlu5 receptors, respectively. Using molecular modeling a model of the TM domain was built for both mGlu1 and mGlu5 receptor subtypes. Docking of CPCCOEt and MPEP into their respective model allowed the modelisation of the novel binding site.

  12. Fear extinction in 17 day old rats is dependent on metabotropic glutamate receptor 5 signaling.

    Science.gov (United States)

    Ganella, Despina E; Thangaraju, Pushbalela; Lawrence, Andrew J; Kim, Jee Hyun

    2016-02-01

    We used pharmacological modulation of the mGlu5 receptor to investigate its role in the extinction of conditioned fear throughout development. In postnatal day (P) 17 rats, the positive allosteric modulator CDPPB facilitated, while the negative allosteric modulator MTEP impaired extinction. These drugs had no such effects on P24 or adult rats. These results establish a changing importance of mGlu5 in extinction of conditioned fear at distinct stages of development.

  13. Group II metabotropic glutamate receptors depress synaptic transmission onto subicular burst firing neurons

    NARCIS (Netherlands)

    Kintscher, M.; Breustedt, J.; Miceli, S.M.; Schmitz, D.; Wozny, C.

    2012-01-01

    The subiculum (SUB) is a pivotal structure positioned between the hippocampus proper and various cortical and subcortical areas. Despite the growing body of anatomical and intrinsic electrophysiological data of subicular neurons, modulation of synaptic transmission in the SUB is not well understood.

  14. Metabotropic Glutamate Receptor-Mediated Long-Term Depression: Molecular Mechanisms

    OpenAIRE

    Gladding, Clare M.; Fitzjohn, Stephen M; Molnár, Elek

    2009-01-01

    The ability to modify synaptic transmission between neurons is a fundamental process of the nervous system that is involved in development, learning, and disease. Thus, synaptic plasticity is the ability to bidirectionally modify transmission, where long-term potentiation and long-term depression (LTD) represent the best characterized forms of plasticity. In the hippocampus, two main forms of LTD coexist that are mediated by activation of either N-methyl-d-aspartic acid receptors (NMDARs) or ...

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    signaling mechanisms have also been revealed. MGluR5s are mainly localized postsynaptically on the periphery of synap-ses. MGluR5s have been implicated in synaptic plasticity and learning and memory. The development of the highly potent and selective mGluR5 antagonist 2-methyl-6-(phenylethynyl...... of the effects of MPEP in various behavioral paradigms have concluded that mGluR5s play a critical role in aversive learning tasks and in hippocampal-dependent spatial learning. However, MPEP has proved ineffective in certain other learning tasks. MGluR5 knockout mice have shown impairments in water maze...... 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...

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    signaling mechanisms have also been revealed. MGluR5s are mainly localized postsynaptically on the periphery of synap-ses. MGluR5s have been implicated in synaptic plasticity and learning and memory. The development of the highly potent and selective mGluR5 antagonist 2-methyl-6-(phenylethynyl...... and radial arm maze performance as well as in contextual fear conditioning, but not in cue conditioning. This review summarizes recent advances reported on mGluR5 function in synaptic plasticity, learning and memory. The current development of positive and negative allosteric modulators of mGluR5...... will provide new pharmacological tools to enhance our knowledge of these receptors in physiological and pathophysiological processes and will further facilitate new investigations on mGluR5 as a therapeutic target for a range of neurological and psychological disorders....

  17. Developmental regulation of hippocampal excitatory synaptic transmission by metabotropic glutamate receptors

    National Research Council Canada - National Science Library

    Ross, F M; Cassidy, J; Wilson, M; Davies, S N

    2000-01-01

    ... postsynaptic potentials L ‐AP4 L‐(+)‐2‐amino‐4‐phosphonobutyric acid LTD long term depression MAP4 ( S )‐2‐amino‐2‐methyl‐4‐phosphonobutanoic acid MCCG (2 S ,3 S ,4 S )‐2...

  18. Modulation of seizure activity in mice by metabotropic glutamate receptor ligands

    DEFF Research Database (Denmark)

    Dalby, Nils Ole; Thomsen, C

    1996-01-01

    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...... against sound-induced convulsions in DBA/2 mice and DMCM-induced seizures in mice but were inactive against seizures induced by administration of pentylenetetrazol or by electrical stimulation. These data suggest that mGluR ligands modulate seizure activity in mice and this effect may be mediated via...

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

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  20. Control of cortical neuronal migration by glutamate and GABA

    Directory of Open Access Journals (Sweden)

    Heiko J Luhmann

    2015-01-01

    Full Text Available Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP, respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca2+ transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e. neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g. anti-epileptics, anesthetics, alcohol may disturb the normal migration pattern when present during early corticogenesis.

  1. Glutamate signalling in bone.

    Directory of Open Access Journals (Sweden)

    Karen eBrakspear

    2012-08-01

    Full Text Available Mechanical loading plays a key role in the physiology of bone, allowing bone to functionally adapt to its environment, however characterisation of the signalling events linking load to bone formation is incomplete. A screen for genes associated with mechanical load-induced bone formation identified the glutamate transporter GLAST, implicating the excitatory amino acid, glutamate, in the mechanoresponse. When an osteogenic load (10N, 10Hz was externally applied to the rat ulna, GLAST (EAAT1 mRNA, was significantly down-regulated in osteocytes in the loaded limb. Functional components from each stage of the glutamate signalling pathway have since been identified within bone, including proteins necessary for calcium-mediated glutamate exocytosis, receptors, transporters and signal propagation. Activation of ionotropic glutamate receptors has been shown to regulate the phenotype of osteoblasts and osteoclasts in vitro and bone mass in vivo. Furthermore, glutamatergic nerves have been identified in the vicinity of bone cells expressing glutamate receptors in vivo. However, it is not yet known how a glutamate signalling event is initiated in bone or its physiological significance. This review will examine the role of the glutamate signalling pathway in bone, with emphasis on the functions of glutamate transporters in osteoblasts.

  2. 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.

  3. Role of Paraventricular Nucleus Glutamate Signaling in Regulation of HPA Axis Stress Responses.

    Science.gov (United States)

    Evanson, Nathan K; Herman, James P

    The hypothalamus-pituitary-adrenal (HPA) axis is the main neuroendocrine arm of the stress response, activation of which leads to the production of glucocorticoid hormones. Glucocorticoids are steroid hormones that are secreted from the adrenal cortex, and have a variety of effects on the body, including modulation of the immune system, suppression of reproductive hormones maintenance of blood glucose levels, and maintenance of blood pressure. Glutamate plays an important role in coordination of HPA axis output. There is strong evidence that glutamate drives HPA axis stress responses through excitatory signaling via ionotropic glutamate receptor signaling. However, glutamate signaling via kainate receptors and group I metabotropic receptors inhibit HPA drive, probably via presynaptic inhibitory mechanisms. Notably, kainate receptors are also localized in the median eminence, and appear to play an excitatory role in control of CRH release at the nerve terminals. Finally, glutamate innervation of the PVN undergoes neuroplastic changes under conditions of chronic stress, and may be involved in sensitization of HPA axis responses. Altogether, the data suggest that glutamate plays a complex role in excitation of CRH neurons, acting at multiple levels to both drive HPA axis responses and limit over-activation.

  4. II. Glutamine and glutamate.

    Science.gov (United States)

    Tapiero, H; Mathé, G; Couvreur, P; Tew, K D

    2002-11-01

    Glutamine and glutamate with proline, histidine, arginine and ornithine, comprise 25% of the dietary amino acid intake and constitute the "glutamate family" of amino acids, which are disposed of through conversion to glutamate. Although glutamine has been classified as a nonessential amino acid, in major trauma, major surgery, sepsis, bone marrow transplantation, intense chemotherapy and radiotherapy, when its consumption exceeds its synthesis, it becomes a conditionally essential amino acid. In mammals the physiological levels of glutamine is 650 micromol/l and it is one of the most important substrate for ammoniagenesis in the gut and in the kidney due to its important role in the regulation of acid-base homeostasis. In cells, glutamine is a key link between carbon metabolism of carbohydrates and proteins and plays an important role in the growth of fibroblasts, lymphocytes and enterocytes. It improves nitrogen balance and preserves the concentration of glutamine in skeletal muscle. Deamidation of glutamine via glutaminase produces glutamate a precursor of gamma-amino butyric acid, a neurotransmission inhibitor. L-Glutamic acid is a ubiquitous amino acid present in many foods either in free form or in peptides and proteins. Animal protein may contain from 11 to 22% and plants protein as much as 40% glutamate by weight. The sodium salt of glutamic acid is added to several foods to enhance flavor. L-Glutamate is the most abundant free amino acid in brain and it is the major excitatory neurotransmitter of the vertebrate central nervous system. Most free L-glutamic acid in brain is derived from local synthesis from L-glutamine and Kreb's cycle intermediates. It clearly plays an important role in neuronal differentiation, migration and survival in the developing brain via facilitated Ca++ transport. Glutamate also plays a critical role in synaptic maintenance and plasticity. It contributes to learning and memory through use-dependent changes in synaptic efficacy and

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

    Science.gov (United States)

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

    2012-06-15

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

  6. Modulation of Pineal Melatonin Synthesis by Glutamate Involves Paracrine Interactions between Pinealocytes and Astrocytes through NF-κB Activation

    Directory of Open Access Journals (Sweden)

    Darine Villela

    2013-01-01

    Full Text Available The glutamatergic modulation of melatonin synthesis is well known, along with the importance of astrocytes in mediating glutamatergic signaling in the central nervous system. Pinealocytes and astrocytes are the main cell types in the pineal gland. The objective of this work was to investigate the interactions between astrocytes and pinealocytes as a part of the glutamate inhibitory effect on melatonin synthesis. Rat pinealocytes isolated or in coculture with astrocytes were incubated with glutamate in the presence of norepinephrine, and the melatonin content, was quantified. The expression of glutamate receptors, the intracellular calcium content and the NF-κB activation were analyzed in astrocytes and pinealocytes. TNF-α's possible mediation of the effect of glutamate was also investigated. The results showed that glutamate's inhibitory effect on melatonin synthesis involves interactions between astrocytes and pinealocytes, possibly through the release of TNF-α. Moreover, the activation of the astrocytic NF-κB seems to be a necessary step. In astrocytes and pinealocytes, AMPA, NMDA, and group I metabotropic glutamate receptors were observed, as well as the intracellular calcium elevation. In conclusion, there is evidence that the modulation of melatonin synthesis by glutamate involves paracrine interactions between pinealocytes and astrocytes through the activation of the astrocytic NF-κB transcription factor and possibly by subsequent TNF-α release.

  7. Evidence for glutamate, GABA and NO in coordinating behaviour in the sponge, Ephydatia muelleri (Demospongiae, Spongillidae).

    Science.gov (United States)

    Elliott, Glen R D; Leys, Sally P

    2010-07-01

    The view that sponges lack tissue level organisation, epithelia, sensory cells and coordinated behaviour is challenged by recent molecular studies showing the existence in Porifera of molecules and proteins that define cell signalling systems in higher order metazoans. Demonstration that freshwater sponges can contract their canals in an organised manner in response to both external and endogenous stimuli prompted us to examine the physiology of the contraction behaviour. Using a combination of digital time-lapse microscopy, high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, immunocytochemistry and pharmacological manipulations, we tested the role of the diffusible amino acids glutamate and gamma-aminobutyric acid (GABA) and a short-lived diffusible gas, nitric oxide (NO), in triggering or modulating contractions in Ephydatia muelleri. We identified pools of glutamate, glutamine and GABA used to maintain a metabotropic glutamate and GABA receptor signalling system. Glutamate induced contractions and propagation of a stereotypical behaviour inflating and deflating the canal system, acting in a dose-dependent manner. Glutamate-triggered contractions were blocked by the metabatropic glutamate receptor inhibitor AP3 and by incubation of the sponge in an allosteric competitive inhibitor of glutamate, Kynurenic acid. Incubation in GABA inhibited glutamate-triggered contractions of the sponge. Nitric oxide synthase, involved in the formation of the diffusible gas NO, was localised using NADPH-diaphorase to mesenchyme cells in the osculum and pinacoderm. A cGMP assay showed the same cells were labelled suggesting that the NO system is functional. Our findings suggest sponges coordinate behaviour using chemical messenger systems common to other animals.

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

    OpenAIRE

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

    2011-01-01

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

  9. Glutamate decreases the secretion of IL-10 by peripheral blood lymphocytes in persons with autoimmune thyroiditis.

    Science.gov (United States)

    Kvaratskhelia, E; Dabrundashvili, N; Gagua, M; Maisuradze, E; Mikeladze, D

    2008-11-01

    Human T lymphocytes expose ionotropic and metabotropic glutamate receptors, which control immune responses, cell activation, maturation, and death. Several cytokines release during inflammation which identification may have important physiological and clinical implications. Main biological function of IL-10 is limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells. Various inflammatory molecules regulated the secretion of IL-8 and IL-10, but the action of glutamate on the biosynthesis of cytokines is unknown. We have found that in peripheral blood lymphocytes glutamate at the concentrations within normal plasma levels (1 x 10(-5) M), as well as at lower concentration (0.3 x 10(-6) M) changes the secretion of immunosuppressive cytokine IL-10, whereas synthesis of proinflammatory chemokine, IL-8 did not changed significantly. Moreover, our results have shown that peripheral blood lymphocytes from patients with autoimmune thyroiditis release less IL-10 at both concentration of glutamate than peripheral blood lymphocytes from healthy persons. These data suggest that glutamate decrease the secretion of IL-10 by peripheral blood lymphocytes, especially in patients with autoimmune thyroiditis that may be responsible for prolongation of inflammation.

  10. Glutamate enhances the expression of vascular endothelial growth factor in cultured SD rat astrocytes

    Institute of Scientific and Technical Information of China (English)

    Chong-xiao Liu; Yong Liu; Wei Shi; Xin-lin Chen; Xin-li Xiao; Ling-yu Zhao; Yu-mei Tian; Jun-feng Zhang

    2009-01-01

    Objective To study the effect of glutamate on the expression of vascular endothelial growth factor (VEGF) mRNA and protein in cultured rat astrocytes. Methods Cultured rat astrocytes were randomly divided into 6 groups: control group (C), glutamate group (G), QA group (Q), DCG-IV group (D), L-AP4 group (L) and glutanmte-FMCPG gronp (G+M). Cells were cultured under nomoxic condition (95% air, 5% CO2). RT-PCR and ELISA methods were used to detect the expression of VEGF mRNA and protein in cultured astrocytes, respectively. G+ M group was preincubated with lmM MCPG for 30 min prior to the stimulation with glutamate. There were 7 time points at 0,4,8,12,16,24 and 48 h in each group except G+M group. Results The expression of VEGF mRNA and protein did not differ significantly among D group, L group and C group. Different from that in C group, the expression of VEGF mRNA and protein could be enhanced both in a dose-dependent and time-dependent manner in G group and Q group. Meanwhile, the enhanced expression of VEGF mRNA and protein in G group was completely suppressed by MCPG after 24 h. Conclusion Glutamate can increase the expression of VEGF mRNA and protein in cultured astrocytes, which may be due to the activation of group I metabotropic glutamate receptors in astrocytes.

  11. Des souris knock-out pour le récepteur métabotrope au glutamate mGluR7 révèlent son rôle dans la cognition et les émotions

    OpenAIRE

    Sansig, Gilles

    2016-01-01

    Metabotropic glutamate receptors (mGluRs) consist of eight different subtypes and exert their effects on second messengers and ion channels via G-proteins. The function of individual mGluR subtypes in the CNS, however, largely remains to be clarified. To study the role of mGluR7 receptors, we used homologous recombination to generate mice lacking this metabotropic receptor subtype (mGluR7). Immunohistochemical and immunoelectron-microscopic analyses showed that mGluR7 is highly expressed in a...

  12. The BDNF Val66Met polymorphism impairs NMDA receptor-dependent synaptic plasticity in the hippocampus.

    Science.gov (United States)

    Ninan, Ipe; Bath, Kevin G; Dagar, Karishma; Perez-Castro, Rosalia; Plummer, Mark R; Lee, Francis S; Chao, Moses V

    2010-06-30

    The Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) gene results in a defect in regulated release of BDNF and affects episodic memory and affective behaviors. However, the precise role of the BDNF Val66Met polymorphism in hippocampal synaptic transmission and plasticity has not yet been studied. Therefore, we examined synaptic properties in the hippocampal CA3-CA1 synapses of BDNF(Met/Met) mice and matched wild-type mice. Although basal glutamatergic neurotransmission was normal, both young and adult mice showed a significant reduction in NMDA receptor-dependent long-term potentiation. We also found that NMDA receptor-dependent long-term depression was decreased in BDNF(Met/Met) mice. However, mGluR-dependent long-term depression was not affected by the BDNF Val66Met polymorphism. Consistent with the NMDA receptor-dependent synaptic plasticity impairment, we observed a significant decrease in NMDA receptor neurotransmission in the CA1 pyramidal neurons of BDNF(Met/Met) mice. Thus, these results show that the BDNF Val66Met polymorphism has a direct effect on NMDA receptor transmission, which may account for changes in synaptic plasticity in the hippocampus.

  13. 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

    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...... oxidative degradation; thus, quantitative formation of glutamine from the glutamate taken up is not possible. Oxidation of glutamate is initiated by transamination catalyzed by an aminotransferase, or oxidative deamination catalyzed by glutamate dehydrogenase (GDH). We discuss methods available to elucidate...... the enzymes that mediate this conversion. Methods include pharmacological tools such as the transaminase inhibitor aminooxyacetic acid, studies using GDH knockout mice, and siRNA-mediated knockdown of GDH in astrocytes. Studies in brain slices incubated with [15N]glutamate demonstrated activity of GDH...

  14. Ascorbate prevents cell death from prolonged exposure to glutamate in an in vitro model of human dopaminergic neurons.

    Science.gov (United States)

    Ballaz, Santiago; Morales, Ingrid; Rodríguez, Manuel; Obeso, José A

    2013-12-01

    Ascorbate (vitamin C) is a nonenzymatic antioxidant highly concentrated in the brain. In addition to mediating redox balance, ascorbate is linked to glutamate neurotransmission in the striatum, where it renders neuroprotection against excessive glutamate stimulation. Oxidative stress and glutamatergic overactivity are key biochemical features accompanying the loss of dopaminergic neurons in the substantia nigra that characterizes Parkinson's disease (PD). At present, it is not clear whether antiglutamate agents and ascorbate might be neuroprotective agents for PD. Thus, we tested whether ascorbate can prevent cell death from prolonged exposure to glutamate using dopaminergic neurons of human origin. To this purpose, dopamine-like neurons were obtained by differentiation of SH-SY5Y cells and then cultured for 4 days without antioxidant (antiaging) protection to evaluate glutamate toxicity and ascorbate protection as a model system of potential factors contributing to dopaminergic neuron death in PD. Glutamate dose dependently induced toxicity in dopaminergic cells largely by the stimulation of AMPA and metabotropic receptors and to a lesser extent by N-methyl-D-aspartate and kainate receptors. At relatively physiological levels of extracellular concentration, ascorbate protected cells against glutamate excitotoxicity. This neuroprotection apparently relies on the inhibition of oxidative stress, because ascorbate prevented the pro-oxidant action of the scavenging molecule quercetin, which occurred over the course of prolonged exposure, as is also seen with glutamate. Our findings show the relevance of ascorbate as a neuroprotective agent and emphasize an often underappreciated role of oxidative stress in glutamate excitotoxicity. Occurrence of a glutamate-ascorbate link in dopaminergic neurons may explain previous contradictions regarding their putative role in PD.

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

    Directory of Open Access Journals (Sweden)

    Nicolas eMorin

    2014-08-01

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

  16. Glutamate signals through mGluR2 to control Schwann cell differentiation and proliferation

    Science.gov (United States)

    Saitoh, Fuminori; Wakatsuki, Shuji; Tokunaga, Shinji; Fujieda, Hiroki; Araki, Toshiyuki

    2016-01-01

    Rapid saltatory nerve conduction is facilitated by myelin structure, which is produced by Schwann cells (SC) in the peripheral nervous system (PNS). Proper development and degeneration/regeneration after injury requires regulated phenotypic changes of SC. We have previously shown that glutamate can induce SC proliferation in culture. Here we show that glutamate signals through metabotropic glutamate receptor 2 (mGluR2) to induce Erk phosphorylation in SC. mGluR2-elicited Erk phosphorylation requires ErbB2/3 receptor tyrosine kinase phosphorylation to limit the signaling cascade that promotes phosphorylation of Erk, but not Akt. We found that Gβγ and Src are involved in subcellular signaling downstream of mGluR2. We also found that glutamate can transform myelinating SC to proliferating SC, while inhibition of mGluR2 signaling can inhibit demyelination of injured nerves in vivo. These data suggest pathophysiological significance of mGluR2 signaling in PNS and its possible therapeutic importance to combat demyelinating disorders including Charcot-Marie-Tooth disease. PMID:27432639

  17. Ethanol produces corticotropin releasing factor receptor-dependent enhancement of spontaneous glutamatergic transmission in the mouse central amygdala

    Science.gov (United States)

    Silberman, Yuval; Fetterly, Tracy L.; Awad, Elias K.; Milano, Elana J.; Usdin, Ted B.; Winder, Danny G.

    2015-01-01

    Background Ethanol modulation of Central Amygdala (CeA) neurocircuitry plays a key role in the development of alcoholism via activation of the corticotropin releasing factor (CRF) receptor system. Previous work has predominantly focused on ethanol/CRF interactions on the CeA GABA circuitry; however our lab recently showed that CRF enhances CeA glutamatergic transmission. Therefore, this study sought to determine if ethanol modulates CeA glutamate transmission via activation of CRF signaling. Methods The effects of ethanol on spontaneous excitatory postsynaptic currents (sEPSCs) and basal resting membrane potentials were examined via standard electrophysiology methods in adult male C57BL/6J mice. Local ablation of CeA CRF neurons (CRFCeAhDTR) was achieved by targeting the human diphtheria toxin receptor (hDTR) to CeA CRF neurons with an adeno-associated virus. Ablation was quantified post-hoc with confocal microscopy. Genetic targeting of the diphtheria toxin active subunit to CRF neurons (CRFDTA mice) ablated CRF neurons throughout the CNS, as assessed by qRT-PCR quantification of CRF mRNA. Results Acute bath application of ethanol significantly increased sEPSC frequency in a concentration dependent manner in CeA neurons, and this effect was blocked by pretreatment of co-applied CRF receptor 1 and CRF receptor 2 antagonists. In experiments utilizing a CRF-tomato reporter mouse, ethanol did not significantly alter the basal membrane potential of CeA CRF neurons. The ability of ethanol to enhance CeA sEPSC frequency was not altered in CRFCeAhDTR mice despite a ~78% reduction in CeA CRF cell counts. The ability of ethanol to enhance CeA sEPSC frequency was also not altered in the CRFDTA mice despite a three-fold reduction in CRF mRNA levels. Conclusion These findings demonstrate that ethanol enhances spontaneous glutamatergic transmission in the CeA via a CRF receptor dependent mechanism. Surprisingly, our data suggest that this action may not require endogenous CRF

  18. Reverse Induced Fit-Driven MAS-Downstream Transduction: Looking for Metabotropic Agonists.

    Science.gov (United States)

    Pernomian, Larissa; Gomes, Mayara Santos; de Paula da Silva, Carlos Henrique Tomich; Campos, Joaquin

    2017-09-11

    The protective effects assigned to MAS receptors activation have spurred a great interest in the development of MAS agonists for clinical purposes. However, the current bases that drive the design of these ligands preclude important concepts recently addressed for MAS activation. Emerging data confirmed that physiological concentrations of peptide MAS agonists induce an atypical signaling that does not reach the metabotropic efficacy of constitutive MAS activation. The canonical activation of MAS-coupled G proteins is only achieved by supraphysiological concentrations of peptide MAS agonists or physiological concentrations of chemically modified analogues. These pleiotropic differences are because of two overlapped but non-identical ligand binding domains (LBD): one non-metabotropic site that recognizes peptide agonists and one metabotropic domain that recognizes modified analogues. Accordingly, it is feasible that supraphysiological concentrations of peptide MAS agonists undergo to chemical modifications that make them suitable for binding to the metabotropic LBD. Recent advances on Receptor Theory confirmed that G protein-coupled receptor (GPCR) oligomerization enhances pharmacological parameters coupled to metabotropic signaling from GPCR ligands, including MAS agonists. For instance, the formation of GPCR-signalosome complex (higher order heteroligomers of GPCR involved in signaling crosstalk) makes the transduction of agonists a more adaptive signal. Considering the recent identification of MAS-signalosome, we postulate the reverse induced fit hypothesis in which MAS-signalosome would trigger chemical modifications required for agonists bind to the metabotropic MAS/LBD. In view of this hypothesis, we cover rational perspectives that consider this information for the development of novel metabotropic MAS agonists provided with constitutive efficacy at physiological concentrations. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  19. Role of principal ionotropic and metabotropic receptors in visceral pain.

    Science.gov (United States)

    Kannampalli, Pradeep; Sengupta, Jyoti N

    2015-03-30

    Visceral pain is the most common form of pain caused by varied diseases and a major reason for patients to seek medical consultation. It also leads to a significant economic burden due to workdays lost and reduced productivity. Further, long-term use of non-specific medications is also associated with side effects affecting the quality of life. Despite years of extensive re-search and the availability of several therapeutic options, management of patients with chronic visceral pain is often in-adequate, resulting in frustration for both patients and physicians. This is, most likely, because the mechanisms associated with chronic visceral pain are different from those of acute pain. Accumulating evidence from years of research implicates several receptors and ion channels in the induction and maintenance of central and peripheral sensitization during chronic pain states. Understanding the specific role of these receptors will facilitate to capitalize on their unique properties to augment the ther-apeutic efficacy while at the same time minimizing unwanted side effects. The aim of this review is to provide a concise review of the recent literature that reports on the role of principal ionotropic receptors and metabotropic receptors in the modulation visceral pain. We also include an overview of the possibility of these receptors as potential new targets for the treatment of chronic visceral pain conditions.

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

    Science.gov (United States)

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

    2016-08-01

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

  1. Blood Glutamate Scavenging: Insight into Neuroprotection

    Directory of Open Access Journals (Sweden)

    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.

  2. Kalirin-7 is necessary for normal NMDA receptor-dependent synaptic plasticity

    KAUST Repository

    Lemtiri-Chlieh, Fouad

    2011-12-19

    Background: Dendritic spines represent the postsynaptic component of the vast majority of excitatory synapses present in the mammalian forebrain. The ability of spines to rapidly alter their shape, size, number and receptor content in response to stimulation is considered to be of paramount importance during the development of synaptic plasticity. Indeed, long-term potentiation (LTP), widely believed to be a cellular correlate of learning and memory, has been repeatedly shown to induce both spine enlargement and the formation of new dendritic spines. In our studies, we focus on Kalirin-7 (Kal7), a Rho GDP/GTP exchange factor (Rho-GEF) localized to the postsynaptic density that plays a crucial role in the development and maintenance of dendritic spines both in vitro and in vivo. Previous studies have shown that mice lacking Kal7 (Kal7 KO) have decreased dendritic spine density in the hippocampus as well as focal hippocampal-dependent learning impairments.Results: We have performed a detailed electrophysiological characterization of the role of Kal7 in hippocampal synaptic plasticity. We show that loss of Kal7 results in impaired NMDA receptor-dependent LTP and long-term depression, whereas a NMDA receptor-independent form of LTP is shown to be normal in the absence of Kal7.Conclusions: These results indicate that Kal7 is an essential and selective modulator of NMDA receptor-dependent synaptic plasticity in the hippocampus. 2011 Lemtiri-Chlieh et al; licensee BioMed Central Ltd.

  3. Kalirin-7 is necessary for normal NMDA receptor-dependent synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Lemtiri-Chlieh Fouad

    2011-12-01

    Full Text Available Abstract Background Dendritic spines represent the postsynaptic component of the vast majority of excitatory synapses present in the mammalian forebrain. The ability of spines to rapidly alter their shape, size, number and receptor content in response to stimulation is considered to be of paramount importance during the development of synaptic plasticity. Indeed, long-term potentiation (LTP, widely believed to be a cellular correlate of learning and memory, has been repeatedly shown to induce both spine enlargement and the formation of new dendritic spines. In our studies, we focus on Kalirin-7 (Kal7, a Rho GDP/GTP exchange factor (Rho-GEF localized to the postsynaptic density that plays a crucial role in the development and maintenance of dendritic spines both in vitro and in vivo. Previous studies have shown that mice lacking Kal7 (Kal7KO have decreased dendritic spine density in the hippocampus as well as focal hippocampal-dependent learning impairments. Results We have performed a detailed electrophysiological characterization of the role of Kal7 in hippocampal synaptic plasticity. We show that loss of Kal7 results in impaired NMDA receptor-dependent LTP and long-term depression, whereas a NMDA receptor-independent form of LTP is shown to be normal in the absence of Kal7. Conclusions These results indicate that Kal7 is an essential and selective modulator of NMDA receptor-dependent synaptic plasticity in the hippocampus.

  4. 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.

  5. Intrathecal injection of glutamate receptor antagonists/agonist selectively attenuated rat pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch.

    Science.gov (United States)

    Liu, Tong; Pang, Xue-Yan; Bai, Zhan-Tao; Chai, Zhi-Fang; Jiang, Feng; Ji, Yong-Hua

    2007-12-15

    The present study investigated the involvement of spinal glutamate receptors in the induction and maintenance of the pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch (BmK). (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5-10-imine hydrogen maleate (MK-801; 40nmol; a non-competitive NMDA receptor antagonist), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 40nmol; a non-NMDA receptor antagonist), dl-amino-3-phosphonopropionic acid (dl-AP3; 100nmol; a group I metabotropic glutamate receptor antagonist) and 4-aminopyrrolidine-2,4-dicarboxylate (APDC; 100nmol; a group II metabotropic glutamate receptor agonist) were employed. On intrathecal injection of glutamate receptor antagonists/agonist before BmK venom administration by 10min, BmK venom-induced spontaneous nociceptive responses could be suppressed by all tested agents. Primary thermal hyperalgesia could be inhibited by MK-801 and dl-AP3, while bilateral mechanical hyperalgesia could be inhibited by CNQX and dl-AP3 and contralateral mechanical hyperalgesia could be inhibited by APDC. On intrathecal injection of glutamate receptor antagonists/agonist after BmK venom injection by 4.5h, primary thermal hyperalgesia could be partially reversed by all tested agents, while bilateral mechanical hyperalgesia could only be inhibited by APDC. The results suggest that the role of spinal glutamate receptors may be different on the various manifestations of BmK venom-induced pain-related behaviors.

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

    DEFF Research Database (Denmark)

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

    2003-01-01

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

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

    OpenAIRE

    Mathiesen, Jesper Mosolff; Svendsen, Nannette; Bräuner-Osborne, Hans; Thomsen, Christian; Ramirez, M Teresa

    2003-01-01

    We have identified 2-methyl-6-(2-phenylethenyl)pyridine (SIB-1893) and 2-methyl-6-phenylethynyl pyridine hydrochloride (MPEP) as positive allosteric modulators for the hmGluR4. SIB-1893 and MPEP enhanced the potency and efficacy of L-2-amino-4-phophonobutyrate (L-AP4) in guanosine 5′-O-(3-[35S]thiotriphosphate ([35S]GTPγS) binding and efficacy in cAMP studies. These effects were fully blocked by the mGluR4 competitive antagonist (RS)-α-cyclopropyl-4-phosphonophenylglycine (CPPG), indicating a...

  8. Loss of Metabotropic Glutamate Receptor 5 Function on Peripheral Benzodiazepine Receptor in Mice Prenatally Exposed to LPS.

    Directory of Open Access Journals (Sweden)

    Dany Arsenault

    Full Text Available Parental microglial induced neuroinflammation, triggered by bacterial- or viral infections, can induce neuropsychiatric disorders like schizophrenia and autism to offspring in animal models. Recent investigations suggest that microglia, the resident immune cells of the brain, provides a link between neurotransmission, immune cell activation, brain inflammation and neuronal dysfunction seen with the offspring. Relatively little is known about how reduction of brain inflammation and restoration of glial function are associated with diminution of brain degeneration and behavioral deficits in offspring. Increased mGluR5 expression and the long-lasting excitotoxic effects of the neurotoxin during brain development are associated with the glial dysfunctions. We investigated the relationship of mGluR5 and PBR and how they regulate glial function and inflammatory processes in mice prenatally exposed to LPS (120μg/kg, between gestational days 15 and 17, an inflammatory model of a psychiatric disorder. Using PET imaging, we showed that pharmacological activation of mGluR5 during 5 weeks reduced expression of classic inflammation marker PBR in many brain areas and that this molecular association was not present in LPS-exposed offspring. The post-mortem analysis revealed that the down regulation of PBR was mediated through activation of mGluR5 in astrocytes. In addition, we demonstrated that this interaction is defective in a mouse model of the psychiatric deficit offering a novel insight of mGluR5 involvement to brain related disorders and PBR related imaging studies. In conclusion, mGluR5 driven glutamatergic activity regulates astrocytic functions associated with PBR (cholesterol transport, neurosteroidogenesis, glial phenotype during maturation and could be associated with neuropsychiatric disorders in offspring.

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

    NARCIS (Netherlands)

    Elia, J.; Glessner, J.T.; Wang, K.; Takahashi, N.; Shtir, C.J.; Hadley, D.; Sleiman, P.M.; Zhang, H.; Kim, C.E.; Robison, R.; Lyon, G.J.; Flory, J.H.; Bradfield, J.P.; Imielinski, M.; Hou, C.; Frackelton, E.C.; Chiavacci, R.M.; Sakurai, T.; Rabin, C.; Middleton, F.A.; Thomas, K.A.; Garris, M.; Mentch, F.; Freitag, C.M.; Steinhausen, H.C.; Todorov, A.A.; Reif, A.; Rothenberger, A.; Franke, B.; Mick, E.O.; Roeyers, H.; Buitelaar, J.K.; Lesch, K.P.; Banaschewski, T.; Ebstein, R.P.; Mulas, F.; Oades, R.D.; Sergeant, J.A.; Sonuga-Barke, E.J.S.; Renner, T.J.; Romanos, M.; Romanos, J.; Warnke, A.; Walitza, S.; Meyer, J.; Palmason, H.; Seitz, C.; Loo, S.K.; Smalley, S.L.; Biederman, J.; Kent, L.; Asherson, P.; Anney, R.J.; Gaynor, J.W.; Shaw, P.; Devoto, M.; White, P.S.; Grant, S.F.; Buxbaum, J.D.; Rapoport, J.L.; Williams, N.M.; Nelson, S.F.; Faraone, S.V.; Hakonarson, H.

    2011-01-01

    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

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

    DEFF Research Database (Denmark)

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

    2001-01-01

    to originate in (S)-11 (EC(50) = 395 microM, K(b) = 86 and 90 microM, respectively). Compound 9, administered icv, but not sc, was shown to protect mice against convulsions induced by N-methyl-D-aspartic acid (NMDA). Compounds 9 and 11 were resolved using chiral HPLC, and the configurational assignments...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  12. Downregulation of metabotropic glutamate receptors mGluR5 and glutamate transporter EAAC1 in the myenteric plexus of the diabetic rat ileum

    Institute of Scientific and Technical Information of China (English)

    Yanhua Bai; Jun Zhang; Hongyang Shi; Fei Dai

    2008-01-01

    Objective: To study the morphologic abnormalities of the myenteric plexus in diabetic rats and to explore the mechanism of their effect on gastrointestinal motility. Methods: Forty rats were randomly divided into a diabetic group and a control group, Gastric emptying and small intestine transit rates were measured and histologic and molecular changes in glutamatergic nerves in the ileal myenteric plexus were observed, mGluR5 receptor and EAAC1 transporter changes in the diabetic rats were studied using fluorescence immunohistochemistry and RT-PCR. Results:Eighteen weeks after the establishment of the diabetic rats model, gastric emptying and small intestine transit rates were found to be significantly delayed in the diabetic group when compared with the control group. The density of glutamatergic ganglia and neurons in the ileal myenterie plexus were significantly decreased in the diabetic group when compared with control group(P<0.05) and the mGluR5 receptors and EAAC1 transporters were downregulated in the diabetic rats(P<0.05). Conclusion: Decreased glutamatergic enteric ganglia and neurons and decreased mGluR5 receptors and EAAC1 transporters in the intestinal myenteric plexus is one of the mechanisms of diabetic gastroenteropathy in rats.

  13. Effect of Calpain inhibitor I on glucocorticoid receptor-dependent degradation and its transactivation ability

    Institute of Scientific and Technical Information of China (English)

    程晓刚; 粟永萍; 罗成基; 刘晓宏

    2004-01-01

    Objective: To investigate the effect of Calpain inhibitor I on glucocorticoid receptor-dependent proteasomal degradation and its transcriptional activity. Methods: After Raw-264.7 cells were treated with Calpain inhibitor I, dexamethasone, or both for about 12 h, the change of glucocorticoid receptor was detected by western blot analysis. COS-7 cells were transfected with PRsh-GRα expression vector and glucocorticoid-responsive receptor pMAMneo-CAT, then the effect of Calpain inhibitor I on glucocorticoid receptor transcriptional activation ability was determined by CAT activity. Results: The glucocorticoid receptor levels decreased after RAW-264.7 cells were treated with dexamethasone for 12 hours, which effect can be inhibited by Calpain inhibitor I to some extent. CAT activity assay showed that Calpain inhibitor I enhance glucocorticoid receptor transcriptional activity. Conclusion: Calpain inhibitor I can inhibit the down-regulation of dexamethasone on glucocoaicoid receptor, and enhances glucocorticoid receptor transactivation ability.

  14. Two-photon brightness of azobenzene photoswitches designed for glutamate receptor optogenetics.

    Science.gov (United States)

    Carroll, Elizabeth C; Berlin, Shai; Levitz, Joshua; Kienzler, Michael A; Yuan, Zhe; Madsen, Dorte; Larsen, Delmar S; Isacoff, Ehud Y

    2015-02-17

    Mammalian neurotransmitter-gated receptors can be conjugated to photoswitchable tethered ligands (PTLs) to enable photoactivation, or photoantagonism, while preserving normal function at neuronal synapses. "MAG" PTLs for ionotropic and metabotropic glutamate receptors (GluRs) are based on an azobenzene photoswitch that is optimally switched into the liganding state by blue or near-UV light, wavelengths that penetrate poorly into the brain. To facilitate deep-tissue photoactivation with near-infrared light, we measured the efficacy of two-photon (2P) excitation for two MAG molecules using nonlinear spectroscopy. Based on quantitative characterization, we find a recently designed second generation PTL, L-MAG0460, to have a favorable 2P absorbance peak at 850 nm, enabling efficient 2P activation of the GluK2 kainate receptor, LiGluR. We also achieve 2P photoactivation of a metabotropic receptor, LimGluR3, with a new mGluR-specific PTL, D-MAG0460. 2P photoswitching is efficiently achieved using digital holography to shape illumination over single somata of cultured neurons. Simultaneous Ca(2+)-imaging reports on 2P photoswitching in multiple cells with high temporal resolution. The combination of electrophysiology or Ca(2+) imaging with 2P activation by optical wavefront shaping should make second generation PTL-controlled receptors suitable for studies of intact neural circuits.

  15. Inflammation and the glutamate system in schizophrenia: implications for therapeutic targets and drug development.

    Science.gov (United States)

    Müller, Norbert

    2008-12-01

    Despite the progress in antipsychotic therapy for schizophrenia, the effects are still not satisfactory. There is a high percentage of therapy-resistant patients and the overall course of the disease is unfavourable in many affected individuals. Therefore, other therapeutic targets than dopaminergic and serotonergic neurotransmitters are being considered. Glutamatergic hypofunction, mediated mainly by NMDA receptor blockade, is suggested to be indirectly responsible for dopaminergic dysfunction in schizophrenia. Increased levels of kynurenic acid (KYN-A), an endogenous NMDA receptor antagonist, resulting from disturbed tryptophan/kynurenine metabolism can explain psychotic symptoms and cognitive deterioration. The role of the immune system in the production of KYN-A and therapeutic targets in the immune and glutamate systems are outlined. Therapeutic consequences are discussed. Glutamate modulators that particularly influence the NMDA co-transmitters glycine and serine, including inhibitors of glycine transporters, are described and initial clinical evidence is discussed. Another target of the glutamate system is the metabotropic mGlu2/3 receptor; Preliminary clinical results of a study with a mGlu2/3 receptor agonist in schizophrenia are mentioned.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Target-Dependent Compartmentalization of the Corelease of Glutamate and GABA from the Mossy Fibers.

    Science.gov (United States)

    Galván, Emilio J; Gutiérrez, Rafael

    2017-01-18

    The mossy fibers (MFs) corelease glutamate and GABA onto pyramidal cells of CA3 during development, until the end of the third postnatal week. However, the major target cells of the MF are the interneurons of CA3. Therefore, it has been shown that the interneurons of the hilus and stratum lucidum receive this dual monosynaptic input on MF stimulation. Because the plasticity of glutamatergic transmission from the different terminals of the MF is target specific, we here asked whether the corelease of glutamate and GABA was also subjected to a target-dependent compartmentalization. We analyzed the occurrence and plasticity of MF simultaneous glutamatergic-GABAergic signaling onto interneurons of the different strata of CA3 in rats during the third postnatal week. We show the coexistence of time-locked, glutamate receptor and GABA receptor-mediated mono synaptic responses evoked by MF stimulation in interneurons from stratum lucidum and stratum radiatum, but not in interneurons from stratum lacunosum-moleculare. As expected from the transmission of MF origin, MF GABAergic responses were depressed by the activation of metabotropic glutamate receptors. Strikingly, while MF glutamatergic responses underwent LTD, the simultaneous MF GABAergic responses of stratum lucidum interneurons, but not of stratum radiatum interneurons, displayed a Hebbian form of LTP that was mimicked by PKC activation. PKA activation potentiated MF glutamatergic responses of stratum radiatum interneurons, whereas in stratum lucidum interneurons only GABAergic responses were potentiated. We here disclose that the corelease of glutamate and GABA, as well as their plasticity are compartmentalized in a target-dependent manner, showing counterbalanced compensatory plasticity of two neurotransmitters released by different terminals of the same pathway.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-01-01

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

  19. Main path and byways: non-vesicular glutamate release by system xc(-) as an important modifier of glutamatergic neurotransmission.

    Science.gov (United States)

    Massie, Ann; Boillée, Séverine; Hewett, Sandra; Knackstedt, Lori; Lewerenz, Jan

    2015-12-01

    System xc(-) is a cystine/glutamate antiporter that exchanges extracellular cystine for intracellular glutamate. Cystine is intracellularly reduced to cysteine, a building block of GSH. As such, system xc(-) can regulate the antioxidant capacity of cells. Moreover, in several brain regions, system xc(-) is the major source of extracellular glutamate. As such this antiporter is able to fulfill key physiological functions in the CNS, while evidence indicates it also plays a role in certain brain pathologies. Since the transcription of xCT, the specific subunit of system xc(-), is enhanced by the presence of reactive oxygen species and inflammatory cytokines, system xc(-) could be involved in toxic extracellular glutamate release in neurological disorders that are associated with increased oxidative stress and neuroinflammation. System xc(-) has also been reported to contribute to the invasiveness of brain tumors and, as a source of extracellular glutamate, could participate in the induction of peritumoral seizures. Two independent reviews (Pharmacol. Rev. 64, 2012, 780; Antioxid. Redox Signal. 18, 2013, 522), approached from a different perspective, have recently been published on the functions of system xc(-) in the CNS. In this review, we highlight novel achievements and insights covering the regulation of system xc(-) as well as its involvement in emotional behavior, cognition, addiction, neurological disorders and glioblastomas, acquired in the past few years. System xc(-) constitutes an important source of extrasynaptic glutamate in the brain. By modulating the tone of extrasynaptic metabotropic or ionotropic glutamate receptors, it affects excitatory neurotransmission, the threshold for overexcitation and excitotoxicity and, as a consequence, behavior. This review describes the current knowledge of how system xc(-) is regulated and involved in physiological as well as pathophysiological brain functioning.

  20. Pivotal Enzyme in Glutamate Metabolism of Poly-γ-Glutamate-Producing Microbes

    OpenAIRE

    Tohru Kamei; Takashi Yamamoto; Makoto Ashiuchi

    2013-01-01

    The extremely halophilic archaeon Natrialba aegyptiaca secretes the L-homo type of poly-g-glutamate (PGA) as an extremolyte. We examined the enzymes involved in glutamate metabolism and verified the presence of L-glutamate dehydrogenases, L-aspartate aminotransferase, and L-glutamate synthase. However, neither glutamate racemase nor D-amino acid aminotransferase activity was detected, suggesting the absence of sources of D-glutamate. In contrast, D-glutamate-rich PGA producers mostly possess ...

  1. Nitric oxide modulates the temporal properties of the glutamate response in type 4 OFF bipolar cells.

    Directory of Open Access Journals (Sweden)

    Alex H Vielma

    Full Text Available Nitric oxide (NO is involved in retinal signal processing, but its cellular actions are only partly understood. An established source of retinal NO are NOACs, a group of nNOS-expressing amacrine cells which signal onto bipolar, other amacrine and ganglion cells in the inner plexiform layer. Here, we report that NO regulates glutamate responses in morphologically and electrophysiologically identified type 4 OFF cone bipolar cells through activation of the soluble guanylyl cyclase-cGMP-PKG pathway. The glutamate response of these cells consists of two components, a fast phasic current sensitive to kainate receptor agonists, and a secondary component with slow kinetics, inhibited by AMPA receptor antagonists. NO shortened the duration of the AMPA receptor-dependent component of the glutamate response, while the kainate receptor-dependent component remained unchanged. Application of 8-Br-cGMP mimicked this effect, while inhibition of soluble guanylate cyclase or protein kinase G prevented it, supporting a mechanism involving a cGMP signaling pathway. Notably, perfusion with a NOS-inhibitor prolonged the duration of the glutamate response, while the NO precursor L-arginine shortened it, in agreement with a modulation by endogenous NO. Furthermore, NO accelerated the response recovery during repeated stimulation of type 4 cone bipolar cells, suggesting that the temporal response properties of this OFF bipolar cell type are regulated by NO. These results reveal a novel cellular mechanism of NO signaling in the retina, and represent the first functional evidence of NO modulating OFF cone bipolar cells.

  2. Pharmacology of glutamate receptor antagonists in the kindling model of epilepsy.

    Science.gov (United States)

    Löscher, W

    1998-04-01

    It is widely accepted that excitatory amino acid transmitters such as glutamate are involved in the initiation of seizures and their propagation. Most attention has been directed to synapses using NMDA receptors, but more recent evidence indicates potential roles for ionotropic non-NMDA (AMPA/kainate) and metabotropic glutamate receptors as well. Based on the role of glutamate in the development and expression of seizures, antagonism of glutamate receptors has long been thought to provide a rational strategy in the search for new, effective anticonvulsant drugs. Furthermore, because glutamate receptor antagonists, particularly those acting on NMDA receptors, protect effectively in the induction of kindling, it was suggested that they may have utility in epilepsy prophylaxis, for example, after head trauma. However, first clinical trials with competitive and uncompetitive NMDA receptor antagonists in patients with partial (focal) seizures, showed that these drugs lack convincing anticonvulsant activity but induce severe neurotoxic adverse effects in doses which were well tolerated in healthy volunteers. Interestingly, the only animal model which predicted the unfavorable clinical activity of competitive NMDA antagonists in patients with chronic epilepsy was the kindling model of temporal lobe epilepsy, indicating that this model should be used in the search for more effective and less toxic glutamate receptor antagonists. In this review, results from a large series of experiments on different categories of glutamate receptor antagonists in fully kindled rats are summarized and discussed. NMDA antagonists, irrespective whether they are competitive, high- or low-affinity uncompetitive, glycine site or polyamine site antagonists, do not counteract focal seizure activity and only weakly, if at all, attenuate propagation to secondarily generalized seizures in this model, indicating that once kindling is established, NMDA receptors are not critical for the expression of

  3. A genome wide association study links glutamate receptor pathway to sporadic Creutzfeldt-Jakob disease risk.

    Science.gov (United States)

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

    2014-01-01

    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.

  4. A genome wide association study links glutamate receptor pathway to sporadic Creutzfeldt-Jakob disease risk.

    Directory of Open Access Journals (Sweden)

    Pascual Sanchez-Juan

    Full Text Available 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.

  5. Synaptic plasticity in the medial vestibular nuclei: role of glutamate receptors and retrograde messengers in rat brainstem slices.

    Science.gov (United States)

    Grassi, S; Pettorossi, V E

    2001-08-01

    The analysis of cellular-molecular events mediating synaptic plasticity within vestibular nuclei is an attempt to explain the mechanisms underlying vestibular plasticity phenomena. The present review is meant to illustrate the main results, obtained in vitro, on the mechanisms underlying long-term changes in synaptic strength within the medial vestibular nuclei. The synaptic plasticity phenomena taking place at the level of vestibular nuclei could be useful for adapting and consolidating the efficacy of vestibular neuron responsiveness to environmental requirements, as during visuo-vestibular recalibration and vestibular compensation. Following a general introduction on the most salient features of vestibular compensation and visuo-vestibular adaptation, which are two plastic events involving neuronal circuitry within the medial vestibular nuclei, the second and third sections describe the results from rat brainstem slice studies, demonstrating the possibility to induce long-term potentiation and depression in the medial vestibular nuclei, following high frequency stimulation of the primary vestibular afferents. In particular the mechanisms sustaining the induction and expression of vestibular long-term potentiation and depression, such as the role of various glutamate receptors and retrograde messengers have been described. The relevant role of the interaction between the platelet-activating factor, acting as a retrograde messenger, and the presynaptic metabotropic glutamate receptors, in determining the full expression of vestibular long-term potentiation is also underlined. In addition, the mechanisms involved in vestibular long-term potentiation have been compared with those leading to long-term potentiation in the hippocampus to emphasize the most significant differences emerging from vestibular studies. The fourth part, describes recent results demonstrating the essential role of nitric oxide, another retrograde messenger, in the induction of vestibular

  6. 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.

  7. A sweet taste receptor-dependent mechanism of glucosensing in hypothalamic tanycytes.

    Science.gov (United States)

    Benford, Heather; Bolborea, Matei; Pollatzek, Eric; Lossow, Kristina; Hermans-Borgmeyer, Irm; Liu, Beihui; Meyerhof, Wolfgang; Kasparov, Sergey; Dale, Nicholas

    2017-05-01

    Hypothalamic tanycytes are glial-like glucosensitive cells that contact the cerebrospinal fluid of the third ventricle, and send processes into the hypothalamic nuclei that control food intake and body weight. The mechanism of tanycyte glucosensing remains undetermined. While tanycytes express the components associated with the glucosensing of the pancreatic β cell, they respond to nonmetabolisable glucose analogues via an ATP receptor-dependent mechanism. Here, we show that tanycytes in rodents respond to non-nutritive sweeteners known to be ligands of the sweet taste (Tas1r2/Tas1r3) receptor. The initial sweet tastant-evoked response, which requires the presence of extracellular Ca(2+) , leads to release of ATP and a larger propagating Ca(2+) response mediated by P2Y1 receptors. In Tas1r2 null mice the proportion of glucose nonresponsive tanycytes was greatly increased in these mice, but a subset of tanycytes retained an undiminished sensitivity to glucose. Our data demonstrate that the sweet taste receptor mediates glucosensing in about 60% of glucosensitive tanycytes while the remaining 40% of glucosensitive tanycytes use some other, as yet unknown mechanism. © 2017 The Authors GLIA Published by Wiley Periodicals, Inc.

  8. Computational Studies of Glutamate Transporters

    Directory of Open Access Journals (Sweden)

    Jeffry Setiadi

    2015-11-01

    Full Text Available Glutamate is the major excitatory neurotransmitter in the human brain whose binding to receptors on neurons excites them while excess glutamate are removed from synapses via transporter proteins. Determination of the crystal structures of bacterial aspartate transporters has paved the way for computational investigation of their function and dynamics at the molecular level. Here, we review molecular dynamics and free energy calculation methods used in these computational studies and discuss the recent applications to glutamate transporters. The focus of the review is on the insights gained on the transport mechanism through computational methods, which otherwise is not directly accessible by experimental probes. Recent efforts to model the mammalian glutamate and other amino acid transporters, whose crystal structures have not been solved yet, are included in the review.

  9. Glutamate antagonists limit tumor growth

    OpenAIRE

    2001-01-01

    Neuronal progenitors and tumor cells possess propensity to proliferate and to migrate. Glutamate regulates proliferation and migration of neurons during development, but it is not known whether it influences proliferation and migration of tumor cells. We demonstrate that glutamate antagonists inhibit proliferation of human tumor cells. Colon adenocarcinoma, astrocytoma, and breast and lung carcinoma cells were most sensitive to the antiproliferative effect of the N...

  10. Glutamate Receptor Aptamers and ALS

    Science.gov (United States)

    2008-01-01

    too bright and too im. This was the same practice used qualitatively in choos - ng green cells for whole-cell recording. The corresponding ange of the...nitrobenzyl)glutamate (Molecular Probes, Inc., Eugene , OR) (22) was dissolved in the external bath buffer and applied to a cell using a cell-flow device (see...9). In brief, caged glutamate (Molecular Probes, Eugene , OR) was dissolved in the external bath buffer and applied to a cell in the whole-cell mode

  11. Blood Glutamate Scavenging: Insight into Neuroprotection

    OpenAIRE

    Alexander Zlotnik; Yoram Shapira; Matthew Boyko; Akiva Leibowitz

    2012-01-01

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

  12. Prefrontal cortex glutamate and extraversion.

    Science.gov (United States)

    Grimm, Simone; Schubert, Florian; Jaedke, Maren; Gallinat, Jürgen; Bajbouj, Malek

    2012-10-01

    Extraversion is considered one of the core traits of personality. Low extraversion has been associated with increased vulnerability to affective and anxiety disorders. Brain imaging studies have linked extraversion, approach behaviour and the production of positive emotional states to the dorsolateral prefrontal cortex (DLPFC) and glutamatergic neurotransmission. However, the relationship between extraversion and glutamate in the DLPFC has not been investigated so far. In order to address this issue, absolute glutamate concentrations in the DLPFC and the visual cortex as a control region were measured by 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) in 29 subjects with high and low extraversion. We found increased glutamate levels in the DLPFC of introverts as compared with extraverts. The increased glutamate concentration was specific for the DLPFC and negatively associated with state anxiety. Although preliminary, results indicate altered top-down control of DLPFC due to reduced glutamate concentration as a function of extraversion. Glutamate measurement with 1H-MRS may facilitate the understanding of biological underpinnings of personality traits and psychiatric diseases associated with dysfunctions in approach behaviour and the production of positive emotional states.

  13. Bicyclic glutamic acid derivatives.

    Science.gov (United States)

    Meyer, Udo; Bisel, Philippe; Weckert, Edgar; Frahm, August Wilhelm

    2006-05-15

    For the second-generation asymmetric synthesis of the trans-tris(homoglutamic) acids via Strecker reaction of chiral ketimines, the cyanide addition as the key stereodifferentiating step produces mixtures of diastereomeric alpha-amino nitrile esters the composition of which is independent of the reaction temperature and the type of the solvent, respectively. The subsequent hydrolysis is exclusively achieved with concentrated H(2)SO(4) yielding diastereomeric mixtures of three secondary alpha-amino alpha-carbamoyl-gamma-esters and two diastereomeric cis-fused angular alpha-carbamoyl gamma-lactams as bicyclic glutamic acid derivatives, gained from in situ stereomer differentiating cyclisation of the secondary cis-alpha-amino alpha-carbamoyl-gamma-esters. Separation was achieved by CC. The pure secondary trans-alpha-amino alpha-carbamoyl-gamma-esters cyclise on heating and treatment with concentrated H(2)SO(4), respectively, to diastereomeric cis-fused angular secondary alpha-amino imides. Their hydrogenolysis led to the enantiomeric cis-fused angular primary alpha-amino imides. The configuration of all compounds was completely established by NMR methods, CD-spectra, and by X-ray analyses of the (alphaR,1R,5R)-1-carbamoyl-2-(1-phenylethyl)-2-azabicyclo[3.3.0]octan-3-one and of the trans-alphaS,1S,2R-2-ethoxycarbonylmethyl-1-(1-phenylethylamino)cyclopentanecarboxamide.

  14. Effect of Interleukin-1β on the Variation of Adenylyl Cyclase Expression in Rats with Seizures Induced by L-Glutamate

    Institute of Scientific and Technical Information of China (English)

    王珍; 刘庆莹; 朱长庚

    2004-01-01

    To explore the mechanism of interleukin-1beta (IL-1β) in the onset of seizure and the effect of IL-1β on the expression of adenylyl cyclase (AC) in rats with seizure induced by L-glutamate. Experimental rats were first injected with IL-1β and then L-glutamate (a dose under the threshold) was injected into the right lateral ventricle. The rats were sacrificed 4 h after the onset of epileptic activity and examined for changes in behavior, immunohistochemistry and compared with those with seizure induced by L-glutamate alone. It was found that the expression of AC in hippocampal and neocortex of rats with seizure induced by IL-1β and L-glutamate were stronger than that of control group (P<0.05), without significant difference found between the L-glutamate group and IL-1β plus L-glutamate group in the expression of AC, the latent period and the severity of seizure. When IL-ra were given (i. c. v. ) first, there was no epileptic activity and the expression of AC did not increase. There were no differences in the expression of AC of rats with IL-1ra and that of control rats. But when 2-methyl-2-(carboxycyclopropyl)glycine (MCCG) was given (i. c.v. ) first, the strongest expression of AC, the shortest latent period and the the most serious seizure activities were observed. The results indicated that IL-1β could facilitate the onset of epilepsy induced by L-glutamate through IL-1R, metabotropic glutamate receptors might work with IL-1R and the increased expression of AC might be involved in the process.

  15. Casein kinase 1-epsilon deletion increases mu opioid receptor-dependent behaviors and binge eating1.

    Science.gov (United States)

    Goldberg, L R; Kirkpatrick, S L; Yazdani, N; Luttik, K P; Lacki, O A; Keith Babbs, R; Jenkins, D F; Evan Johnson, W; Bryant, C D

    2017-09-01

    Genetic and pharmacological studies indicate that casein kinase 1 epsilon (Csnk1e) contributes to psychostimulant, opioid, and ethanol motivated behaviors. We previously used pharmacological inhibition to demonstrate that Csnk1e negatively regulates the locomotor stimulant properties of opioids and psychostimulants. Here, we tested the hypothesis that Csnk1e negatively regulates opioid and psychostimulant reward using genetic inhibition and the conditioned place preference assay in Csnk1e knockout mice. Similar to pharmacological inhibition, Csnk1e knockout mice showed enhanced opioid-induced locomotor activity with the mu opioid receptor agonist fentanyl (0.2 mg/kg i.p.) as well as enhanced sensitivity to low-dose fentanyl reward (0.05 mg/kg). Interestingly, female knockout mice also showed a markedly greater escalation in consumption of sweetened palatable food - a behavioral pattern consistent with binge eating that also depends on mu opioid receptor activation. No difference was observed in fentanyl analgesia in the 52.5°C hot plate assay (0-0.4 mg/kg), naloxone conditioned place aversion (4 mg/kg), or methamphetamine conditioned place preference (0-4 mg/kg). To identify molecular adaptations associated with increased drug and food behaviors in knockout mice, we completed transcriptome analysis via mRNA sequencing of the striatum. Enrichment analysis identified terms associated with myelination and axon guidance and pathway analysis identified a differentially expressed gene set predicted to be regulated by the Wnt signaling transcription factor, Tcf7l2. To summarize, Csnk1e deletion increased mu opioid receptor-dependent behaviors, supporting previous studies indicating an endogenous negative regulatory role of Csnk1e in opioid behavior. © 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  16. Abnormalities in Glutamate Metabolism and Excitotoxicity in the Retinal Diseases

    Directory of Open Access Journals (Sweden)

    Makoto Ishikawa

    2013-01-01

    Full Text Available In the physiological condition, glutamate acts as an excitatory neurotransmitter in the retina. However, excessive glutamate can be toxic to retinal neurons by overstimulation of the glutamate receptors. Glutamate excess is primarily attributed to perturbation in the homeostasis of the glutamate metabolism. Major pathway of glutamate metabolism consists of glutamate uptake by glutamate transporters followed by enzymatic conversion of glutamate to nontoxic glutamine by glutamine synthetase. Glutamate metabolism requires energy supply, and the energy loss inhibits the functions of both glutamate transporters and glutamine synthetase. In this review, we describe the present knowledge concerning the retinal glutamate metabolism under the physiological and pathological conditions.

  17. VGF (TLQP-62)-induced neurogenesis targets early phase neural progenitor cells in the adult hippocampus and requires glutamate and BDNF signaling.

    Science.gov (United States)

    Thakker-Varia, Smita; Behnke, Joseph; Doobin, David; Dalal, Vidhi; Thakkar, Keya; Khadim, Farah; Wilson, Elizabeth; Palmieri, Alicia; Antila, Hanna; Rantamaki, Tomi; Alder, Janet

    2014-05-01

    The neuropeptide VGF (non-acronymic), which has antidepressant-like effects, enhances adult hippocampal neurogenesis as well as synaptic activity and plasticity in the hippocampus, however the interaction between these processes and the mechanism underlying this regulation remain unclear. In this study, we demonstrate that VGF-derived peptide TLQP-62 specifically enhances the generation of early progenitor cells in nestin-GFP mice. Specifically, TLQP-62 significantly increases the number of Type 2a neural progenitor cells (NPCs) while reducing the number of more differentiated Type 3 cells. The effect of TLQP-62 on proliferation rather than differentiation was confirmed using NPCs in vitro; TLQP-62 but not scrambled peptide PEHN-62 increases proliferation in a cell line as well as in primary progenitors from adult hippocampus. Moreover, TLQP-62 but not scrambled peptide increases Cyclin D mRNA expression. The proliferation of NPCs induced by TLQP-62 requires synaptic activity, in particular through NMDA and metabotropic glutamate receptors. The activation of glutamate receptors by TLQP-62 activation induces phosphorylation of CaMKII through NMDA receptors and protein kinase D through metabotropic glutamate receptor 5 (mGluR5). Furthermore, pharmacological antagonists to CaMKII and PKD inhibit TLQP-62-induced proliferation of NPCs indicating that these signaling molecules downstream of glutamate receptors are essential for the actions of TLQP-62 on neurogenesis. We also show that TLQP-62 gradually activates Brain-Derived Neurotrophic Factor (BDNF)-receptor TrkB in vitro and that Trk signaling is required for TLQP-62-induced proliferation of NPCs. Understanding the precise molecular mechanism of how TLQP-62 influences neurogenesis may reveal mechanisms by which VGF-derived peptides act as antidepressant-like agents.

  18. Intrahepatic expression of genes related to metabotropic receptors in chronic hepatitis

    Institute of Scientific and Technical Information of China (English)

    Andrzej Cie(s)la,; Maciej Ku(s)mider,; Agata Faron-Górecka; Marta Dziedzicka-Wasylewska; Monika Bociaga-Jasik; Danuta Owczarek; Irena Cie(c)ko-Michalska

    2012-01-01

    AIM:To screen for genes related to metabotropic receptors that might be involved in the development of chronic hepatitis.METHODS:Assessment of 20 genes associated with metabotropic receptors was performed in liver specimens obtained by punch biopsy from 12 patients with autoimmune and chronic hepatitis type B and C.For this purpose,a microarray with low integrity grade and with oligonucleotide DNA probes complementary to target transcripts was used.Evaluation of gene expression was performed in relation to transcript level,correlation between samples and grouping of clinical parameters used in chronic hepatitis assessment.Clinical markers of chronic hepatitis included alanine and aspartate aminotransferase,γ-glutamyltranspeptidase,alkaline phosphatase and cholinesterase activity,levels of iron ions,total cholesterol,triglycerides,albumin,glucose,hemoglobin,platelets,histological analysis of inflammatory and necrotic status,fibrosis according to METAVIR score,steatosis,as well as anthropometric body mass index,waist/hip index,percentage of adipose tissue and liver size in ultrasound examination.Gender,age,concomitant diseases and drugs were also taken into account.Validation of oligonucleotide microarray gene expression results was done with the use of quantitative real-time polymerase chain reaction (qRT-PCR).RESULTS:The highest (0.002 < P < 0.046) expression among genes encoding main components of metabotropic receptor pathways,such as the a subunit of G-coupled protein,phosphoinositol-dependent protein kinase or arrestin was comparable to that of angiotensinogen synthesized in the liver.Carcinogenesis suppressor genes,such as chemokine ligand 4,transcription factor early growth response protein 1 and lysophosphatidic acid receptor,were characterized by the lowest expression (0.002 < P < 0.046),while the factor potentially triggering hepatic cancer,transcription factor JUN-B,had a 20-fold higher expression.The correlation between expression of genes of

  19. DNA nanopore translocation in glutamate solutions

    NARCIS (Netherlands)

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

    2015-01-01

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

  20. Glutamic acid as anticancer agent: An overview

    National Research Council Canada - National Science Library

    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...

  1. 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) (c) Limitations, restrictions, or explanation....

  2. 21 CFR 182.1500 - Monoammonium glutamate.

    Science.gov (United States)

    2010-04-01

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

  3. 21 CFR 582.1516 - Monopotassium glutamate.

    Science.gov (United States)

    2010-04-01

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

  4. 21 CFR 582.1500 - Monoammonium glutamate.

    Science.gov (United States)

    2010-04-01

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

  5. 21 CFR 182.1516 - Monopotassium glutamate.

    Science.gov (United States)

    2010-04-01

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

  6. Ciprofloxacin triggered glutamate production by Corynebacterium glutamicum.

    Science.gov (United States)

    Lubitz, Dorit; Wendisch, Volker F

    2016-10-07

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

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Marco Pedrazzi

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

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

    Science.gov (United States)

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

    2011-01-01

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

  10. AMPK Activation Affects Glutamate Metabolism in Astrocytes

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...... 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...... affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK...

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

    Science.gov (United States)

    Montes de Oca Balderas, Pavel; Aguilera, Penélope

    2015-01-01

    Astrocytes were long thought to be only structural cells in the CNS; however, their functional properties support their role in information processing and cognition. The ionotropic glutamate N-methyl D-aspartate (NMDA) receptor (NMDAR) is critical for CNS functions, but its expression and function in astrocytes is still a matter of research and debate. Here, we report immunofluorescence (IF) labeling in rat cultured cortical astrocytes (rCCA) of all NMDAR subunits, with phenotypes suggesting their intracellular transport, and their mRNA were detected by qRT-PCR. IF and Western Blot revealed GluN1 full-length synthesis, subunit critical for NMDAR assembly and transport, and its plasma membrane localization. Functionally, we found an iCa2+ rise after NMDA treatment in Fluo-4-AM labeled rCCA, an effect blocked by the NMDAR competitive inhibitors D(-)-2-amino-5-phosphonopentanoic acid (APV) and Kynurenic acid (KYNA) and dependent upon GluN1 expression as evidenced by siRNA knock down. Surprisingly, the iCa2+ rise was not blocked by MK-801, an NMDAR channel blocker, or by extracellular Ca2+ depletion, indicating flux-independent NMDAR function. In contrast, the IP3 receptor (IP3R) inhibitor XestosponginC did block this response, whereas a Ryanodine Receptor inhibitor did so only partially. Furthermore, tyrosine kinase inhibition with genistein enhanced the NMDA elicited iCa2+ rise to levels comparable to those reached by the gliotransmitter ATP, but with different population dynamics. Finally, NMDA depleted the rCCA mitochondrial membrane potential (mΔψ) measured with JC-1. Our results demonstrate that rCCA express NMDAR subunits which assemble into functional receptors that mediate a metabotropic-like, non-canonical, flux-independent iCa2+ increase. PMID:25954808

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

    Science.gov (United States)

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

    2013-01-01

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

  13. 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...

  14. 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.; Wamelen, D.J. van; 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 neu

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

    Directory of Open Access Journals (Sweden)

    Malki Rana

    2008-04-01

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

  16. Dopamine-dependent effects on basal and glutamate stimulated network dynamics in cultured hippocampal neurons.

    Science.gov (United States)

    Li, Yan; Chen, Xin; Dzakpasu, Rhonda; Conant, Katherine

    2017-02-01

    Oscillatory activity occurs in cortical and hippocampal networks with specific frequency ranges thought to be critical to working memory, attention, differentiation of neuronal precursors, and memory trace replay. Synchronized activity within relatively large neuronal populations is influenced by firing and bursting frequency within individual cells, and the latter is modulated by changes in intrinsic membrane excitability and synaptic transmission. Published work suggests that dopamine, a potent modulator of learning and memory, acts on dopamine receptor 1-like dopamine receptors to influence the phosphorylation and trafficking of glutamate receptor subunits, along with long-term potentiation of excitatory synaptic transmission in striatum and prefrontal cortex. Prior studies also suggest that dopamine can influence voltage gated ion channel function and membrane excitability in these regions. Fewer studies have examined dopamine's effect on related endpoints in hippocampus, or potential consequences in terms of network burst dynamics. In this study, we record action potential activity using a microelectrode array system to examine the ability of dopamine to modulate baseline and glutamate-stimulated bursting activity in an in vitro network of cultured murine hippocampal neurons. We show that dopamine stimulates a dopamine type-1 receptor-dependent increase in number of overall bursts within minutes of its application. Notably, however, at the concentration used herein, dopamine did not increase the overall synchrony of bursts between electrodes. Although the number of bursts normalizes by 40 min, bursting in response to a subsequent glutamate challenge is enhanced by dopamine pretreatment. Dopamine-dependent potentiation of glutamate-stimulated bursting was not observed when the two modulators were administered concurrently. In parallel, pretreatment of murine hippocampal cultures with dopamine stimulated lasting increases in the phosphorylation of the

  17. Evaluation of hydrogel-coated glutamate microsensors

    NARCIS (Netherlands)

    Oldenziel, Weite Hendrik; Dijkstra, G; Cremers, T.I.F.H.; Westerink, B.H.C.

    2006-01-01

    Glutamate microsensors form a promising analytical tool for monitoring neuronally derived glutamate directly in the brain. However, when a microsensor is implanted in brain tissue, many factors can diminish its performance. Consequently, a thorough characterization and evaluation of a microsensor is

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

    Science.gov (United States)

    Hirasawa, Takashi; Wachi, Masaaki

    2016-12-03

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

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

    Science.gov (United States)

    Xiao, Weidong; Feng, Yongjia; Holst, Jens J; Hartmann, Bolette; Yang, Hua; Teitelbaum, Daniel H

    2014-05-01

    Small intestine luminal nutrient sensing may be crucial for modulating physiological functions. However, its mechanism of action is incompletely understood. We used a model of enteral nutrient deprivation, or total parenteral nutrition (TPN), resulting in intestinal mucosal atrophy and decreased epithelial barrier function (EBF). We examined how a single amino acid, glutamate (GLM), modulates intestinal epithelial cell (IEC) growth and EBF. Controls were chow-fed mice, T1 receptor-3 (T1R3)-knockout (KO) mice, and treatment with the metabotropic glutamate receptor (mGluR)-5 antagonist MTEP. TPN 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 was regulated by T1R3 and mGluR5, suggesting a novel negative regulator pathway for IEC proliferation not previously described. Loss of luminal nutrients with TPN administration may widely affect intestinal taste sensing. GLM has previously unrecognized actions on IEC growth and EBF. Restoring luminal sensing via GLM could be a strategy for patients on TPN.

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

    Directory of Open Access Journals (Sweden)

    Shigeyuki Chaki

    2015-09-01

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

  1. Synthesis and pharmacology of glutamate receptor ligands: new isothiazole analogues of ibotenic acid.

    Science.gov (United States)

    Jørgensen, Charlotte G; Clausen, Rasmus P; Hansen, Kasper B; Bräuner-Osborne, Hans; Nielsen, Birgitte; Metzler, Bjørn; Metzler, Birgitte Bjørn; Kehler, Jan; Krogsgaard-Larsen, Povl; Madsen, Ulf

    2007-02-07

    The naturally occurring heterocyclic amino acid ibotenic acid (Ibo) and the synthetic analogue thioibotenic acid (Thio-Ibo) possess interesting but dissimilar pharmacological activity at ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs). Therefore, a series of Thio-Ibo analogues was synthesized. The synthesis included introduction of substituents by Suzuki and Grignard reactions on 4-halogenated 3-benzyloxyisothiazolols, reduction of the obtained alcohols, followed by introduction of the amino acid moiety by use of 2-(N-tert-butoxycarbonylimino)malonic acid diethyl ester. The obtained Thio-Ibo analogues (1, 2a-g) were characterized in functional assays on recombinant mGluRs and in receptor binding assays on native iGluRs. At mGluRs, the activity at Group II was retained for compounds with small substituents (2a-2d), whereas the Group I and Group III receptor activities for all new compounds were lost. Detection of NMDA receptor affinity prompted further characterization, and two-electrode voltage-clamp recordings at recombinant NMDA receptor subtypes NR1/NR2A-D expressed in Xenopus oocytes were carried out for compounds with small substituents (chloro, bromo, methyl or ethyl, compounds 2a-d). This series of Thio-Ibo analogues defines a structural threshold for NMDA receptor activation and reveals that the individual subtypes have different steric requirements for receptor activation. The compounds 2a and 2c are the first examples of agonists discriminating individual NMDA subtypes.

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

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  3. 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

    2016-12-23

    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.

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

    Slotboom, DJ; Konings, WN; Lolkema, JS

    2001-01-01

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

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

    Science.gov (United States)

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

  7. T cells induce extended class II MHC compartments in dendritic cells in a Toll-like receptor-dependent manner.

    Science.gov (United States)

    Boes, Marianne; Bertho, Nicolas; Cerny, Jan; Op den Brouw, Marjolein; Kirchhausen, Tomas; Ploegh, Hidde

    2003-10-15

    Interaction of Ag-loaded dendritic cells with Ag-specific CD4 T cells induces the formation of long tubular class II MHC-positive compartments that polarize toward the T cell. We show involvement of a Toll-like receptor-mediated signal in this unusual form of intracellular class II MHC trafficking. First, wild-type dendritic cells loaded with LPS-free Ag failed to show formation of class II-positive tubules upon Ag-specific T cell engagement, but did so upon supplementation of the Ag with low concentrations of LPS. Second, Ag-loaded myeloid differentiation factor 88 -deficient dendritic cells failed to form these tubules upon interaction with T cells, regardless of the presence of LPS. Finally, inclusion of a cell-permeable peptide that blocks TNFR-associated factor 6 function, downstream of myeloid differentiation factor 88, blocked T cell-dependent tubulation. A Toll-like receptor-dependent signal is thus required to allow Ag-loaded dendritic cells to respond to T cell contact by formation of extended endosomal compartments. This activation does not result in massive translocation of class II MHC molecules to the cell surface.

  8. Neuroprotective effects of the allosteric agonist of metabotropic glutamate receptor 7 AMN082 on oxygen-glucose deprivation- and kainate-induced neuronal cell death.

    Science.gov (United States)

    Domin, Helena; Jantas, Danuta; Śmiałowska, Maria

    2015-09-01

    Although numerous studies demonstrated a neuroprotective potency of unspecific group III mGluR agonists in in vitro and in vivo models of excitotoxicity, little is known about the protective role of group III mGlu receptor activation against neuronal cell injury evoked by ischemic conditions. The aim of the present study was to assess neuroprotective potential of the allosteric agonist of mGlu7 receptor, N,N'-Bis(diphenylmethyl)-1,2-ethanediamine dihydrochloride (AMN082) against oxygen-glucose deprivation (OGD)- and kainate (KA)-evoked neuronal cell damage in primary neuronal cultures, with special focus on its efficacy after delayed application. We demonstrated that in cortical neuronal cultures exposed to a 180 min OGD, AMN082 (0.01-1 µM) in a concentration- and time-dependent way attenuated the OGD-induced changes in the LDH release and MTT reduction assays. AMN082 (0.5 and 1 µM) produced also neuroprotective effects against KA-evoked neurotoxicity both in cortical and hippocampal cultures. Of particular importance was the finding that AMN082 attenuated excitotoxic neuronal injury after delayed application (30 min after OGD, or 30 min-1 h after KA). In both models of neurotoxicity, namely OGD- and KA-induced injury, the neuroprotective effects of AMN082 (1 µM) were reversed by the selective mGlu7 antagonist, 6-(4-Methoxyphenyl)-5-methyl-3-(4-pyridinyl)-isoxazolo[4,5-c]pyridin-4(5H)-one hydrochloride (MMPIP, 1 µM), suggesting the mGlu7-dependent mechanism of neuroprotective effects of AMN082. Next, we showed that AMN082 (0.5 and 1 µM) attenuated the OGD-induced increase in the number of necrotic nuclei as well inhibited the OGD-evoked calpain activation, suggesting the participation of these processes in the mechanism of AMN082-mediated protection. Additionally, we showed that protection evoked by AMN082 (1 µM) in KA model was connected with the inhibition of toxin-induced caspase-3 activity, and this effect was abolished by the mGlu7 receptor antagonist. The obtained results indicated that the activation of mGlu7 receptors may be a promising target for neuroprotection against ischemic and excitotoxic insults.

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

    DEFF Research Database (Denmark)

    Kjaerby, Celia; Bundgaard, Christoffer; Fejgin, Kim;

    2013-01-01

    treatment, pyramidal neurons displayed a reduced mIPSC frequency and up-regulation of extrasynaptic THIP-induced current. ADX47273 treatment restored this up-regulation of THIP-induced current. Reduced receptor function seems to be the underlying cause of the reported changes, since repeated treatment...

  10. Discovery of dual positive allosteric modulators (PAMs) of the metabotropic glutamate 2 receptor and CysLT1 antagonists for treating migraine headache.

    Science.gov (United States)

    Blanco, Maria-Jesus; Benesh, Dana R; Knobelsdorf, James A; Khilevich, Albert; Cortez, Guillermo S; Mokube, Fese; Aicher, Thomas D; Groendyke, Todd M; Marmsater, Fredrik P; Tang, Tony P; Johnson, Kirk W; Clemens-Smith, Amy; Muhlhauser, Mark A; Swanson, Steven; Catlow, John; Emkey, Renee; Johnson, Michael P; Schkeryantz, Jeffrey M

    2017-01-15

    Pyridylmethylsulfonamide series were the first reported example of positive allosteric modulators (PAM) of the mGlu2 receptor. The hydroxyacetophenone scaffold is a second series of mGlu2 PAMs we have identified. This series of molecules are potent mGlu2 potentiators and possess significant CysLT1 (cysteinyl leukotriene receptor 1) antagonist activity, showing in vivo efficacy in a dural plasma protein extravasation (PPE) model of migraine. In this paper, we describe the dual SAR, pharmacokinetics and preclinical in vivo efficacy data for a tetrazole containing hydroxyacetophenone scaffold.

  11. Synthesis and evaluation of a series of heterobiarylamides that are centrally penetrant metabotropic glutamate receptor 4 (mGluR4) positive allosteric modulators (PAMs).

    Science.gov (United States)

    Engers, Darren W; Niswender, Colleen M; Weaver, C David; Jadhav, Satyawan; Menon, Usha N; Zamorano, Rocio; Conn, P Jeffrey; Lindsley, Craig W; Hopkins, Corey R

    2009-07-23

    We report the synthesis and evaluation of a series of heterobiaryl amides as positive allosteric modulators of mGluR4. Compounds 9b and 9c showed submicromolar potency at both human and rat mGluR4. In addition, both 9b and 9c were shown to be centrally penetrant in rats using nontoxic vehicles, a major advance for the mGluR4 field.

  12. Changes in metabotropic glutamate receptor 4 expression and the effects of L-2-amino-4-phosphonobutyrate in a rodent model of diffuse brain injury

    Institute of Scientific and Technical Information of China (English)

    白红民; 王伟民; 李天栋; 费舟

    2004-01-01

    Objective: To examine the changes in the expression of mGluR4 after diffuse brain injury (DBI) and to determine the role of its specific agonist L-2-amino-4phosphonobutyrate (L-AP4) in vivo. Methods: A total of 161 male SD rats were randomized into the following groups. Group A included normal control, sham-operated control and DBI group. DBI was produced according to Marmarou's diffuse head injury model. mRNA expression of mGluR4 was detected by hybridization in situ. Group B included DBI alone, DBI treated with normal saline and DBI treated with L-AP4. All DBI rats were trained in a series of performance tests, following which they were subjected to DBI. At 1 and 12 hours, animals were injected intraventricularly with L-AP4 (100 mmol/L, 10 μl) or normal saline. Motor and cognitive performances were tested at 1,3, 7, 14 days after injury and the damaged neurons were also detected. Results: There was no significant difference between normal control group and sham-operated group in the expression of mGluR4 (P > 0.05 ). The animals exposed to DBI showed significantly increased expression of mRNA of mGluR4 compared with the sham-operated animals 1 h after injury (P < 0.05 ). At 6 hours, the evolution of neuronal expression of mGluR4 in the trauma alone group was relatively static. Compared with saline-treated control animals, rats treated with L-AP4 showed an effective result of decreased number of damaged neurons and better motor and cognitive performances. Conclusions: Increased expression of mGluR4 is important in the pathophysiological process of DBI and its specific agonist L -AP4 can provide remarkable neuroprotection against DBI not only at the histopathological level but also in the motor and cognitive performance.

  13. Metabotropic glutamate antagonists alone and in combination with morphine: comparison across two models of acute pain and a model of persistent, inflammatory pain.

    Science.gov (United States)

    Picker, Mitchell J; Daugherty, Dana; Henry, Fredrick E; Miller, Laurence L; Dykstra, Linda A

    2011-12-01

    The present study examined the effects of the mGluR1 antagonist JNJ16259685 (JNJ) and the mGluR5 antagonist 2-methyl-6-phenylethynylpyridine (MPEP) alone and in combination with morphine in two acute pain models (hotplate, warm water tail-withdrawal), and a persistent, inflammatory pain model (capsaicin). In the hotplate and warm water tail-withdrawal procedures, JNJ and MPEP were ineffective when administered alone. In both procedures, JNJ potentiated morphine antinociception. In the hotplate procedure, MPEP potentiated morphine antinociception at the highest dose examined, whereas in the warm water tail-withdrawal procedure MPEP attenuated morphine antinociception at a moderate dose and potentiated morphine antinociception at a high dose. For both JNJ and MPEP, the magnitude of this morphine potentiation was considerably greater in the hotplate procedure. In the capsaicin procedure, the highest dose of MPEP produced intermediate levels of antihyperalgesia and also attenuated the effects of a dose of morphine that produced intermediate levels of antihyperalgesia. In contrast, JNJ had no effect when administered alone in the capsaicin procedure and did not alter morphine-induced antihyperalgesia. The present findings suggest that the effects produced by mGluR1 and mGluR5 antagonists alone and in combination with morphine can be differentiated in models of both acute and persistent pain.

  14. Modulation of Long-Term Potentiation and Epileptiform Activity in the Rat Dentate Gyrus by the Group II Metabotropic Glutamate Receptor Subtype mGluR3

    Science.gov (United States)

    2006-05-31

    200 µM) blocked LTP of extracellular excitatory post-synaptic potentials ( EPSPs ) after high-frequency stimulation (100Hz; 2s) of the medial perforant...affect EPSPs recorded in a paired-pulse paradigm which argues against a presynaptic effect. These data are the first to indicate competitive effects...acetylaspartylglutamate (NAAG; 50 and 200 µM) blocked LTP of extracellular excitatory post-synaptic potentials ( EPSPs ) after high-frequency stimulation

  15. Mutation-induced quisqualic acid and ibotenic acid affinity at the metabotropic glutamate receptor subtype 4: ligand selectivity results from a synergy of several amino acid residues

    DEFF Research Database (Denmark)

    Hermit, Mette B; Greenwood, Jeremy R; Bräuner-Osborne, Hans

    2004-01-01

    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...... that mimicked mGluR1 residues. Based on ligand docking to homology models, the non-conserved residues, Lys-74, Glu-287, Ser-313, and Lys-317, were chosen for the mutational studies and all of the mutations proved capable of partially or completely restoring the affinities of the ligands. In particular......, the mutations K74Y and K317R induced dramatic triple-order-of-magnitude increases in the affinity of ibotenic acid at mGluR4, making the affinity equivalent to that of mGluR1. Furthermore, the affinity of quisqualic acid at mGluR4 was increased to the same level as mGluR1 by the two double mutations, K74Y/K317R...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    -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...

  17. Activation of metabotropic glutamate 5 and NMDA receptors underlies the induction of persistent bursting and associated long-lasting changes in CA3 recurrent connections.

    OpenAIRE

    Stoop, Ron; Conquet, François; Zuber, Benoît; Voronin, Leon L.; Pralong, Etienne

    2003-01-01

    The aim of this study was to describe the induction and expression mechanisms of a persistent bursting activity in a horizontal slice preparation of the rat limbic system that includes the ventral part of the hippocampus and the entorhinal cortex. Disinhibition of this preparation by bicuculline led to interictal-like bursts in the CA3 region that triggered synchronous activity in the entorhinal cortex. Washout of bicuculline after a 1 hr application resulted in a maintained production of hip...

  18. Metabotropic glutamate receptor 1 recycles to the cell surface in protein phosphatase 2A‐dependent manner in non‐neuronal and neuronal cell lines

    National Research Council Canada - National Science Library

    Pandey, Saurabh; Mahato, Prabhat Kumar; Bhattacharyya, Samarjit

    2014-01-01

    ...‐neuronal cells like hepatocytes, skin cells, etc. Although it has been reported that mG luR1 gets endocytosed on ligand application, the events after the internalization of the receptor has not been studied...

  19. Biobased synthesis of acrylonitrile from glutamic acid

    NARCIS (Netherlands)

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

    2011-01-01

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

  20. Genetics Home Reference: glutamate formiminotransferase deficiency

    Science.gov (United States)

    ... glutamate formiminotransferase deficiency is also characterized by megaloblastic anemia. Megaloblastic anemia occurs when a person has a low number ... named? Additional Information & Resources MedlinePlus (4 ... Encyclopedia: Megaloblastic Anemia (image) Health Topic: Amino Acid Metabolism Disorders Health ...

  1. Biobased synthesis of acrylonitrile from glutamic acid

    NARCIS (Netherlands)

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

    2011-01-01

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

  2. Mechanism for the activation of glutamate receptors

    Science.gov (United States)

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

  3. DNA nanopore translocation in glutamate solutions

    Science.gov (United States)

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

    2015-08-01

    Nanopore experiments have traditionally been carried out with chloride-based solutions. Here we introduce silver/silver-glutamate-based electrochemistry as an alternative, and study the viscosity, conductivity, and nanopore translocation characteristics of potassium-, sodium-, and lithium-glutamate solutions. We show that it has a linear response at typical voltages and can be used to detect DNA translocations through a nanopore. The glutamate anion also acts as a redox-capable thickening agent, with high-viscosity solutions capable of slowing down the DNA translocation process by up to 11 times, with a corresponding 7 time reduction in signal. These results demonstrate that glutamate can replace chloride as the primary anion in nanopore resistive pulse sensing.

  4. Differential expression of glutamate receptors in avian neural pathways for learned vocalization.

    Science.gov (United States)

    Wada, Kazuhiro; Sakaguchi, Hironobu; Jarvis, Erich D; Hagiwara, Masatoshi

    2004-08-01

    Learned vocalization, the substrate for human language, is a rare trait. It is found in three distantly related groups of birds-parrots, hummingbirds, and songbirds. These three groups contain cerebral vocal nuclei for learned vocalization not found in their more closely related vocal nonlearning relatives. Here, we cloned 21 receptor subunits/subtypes of all four glutamate receptor families (AMPA, kainate, NMDA, and metabotropic) and examined their expression in vocal nuclei of songbirds. We also examined expression of a subset of these receptors in vocal nuclei of hummingbirds and parrots, as well as in the brains of dove species as examples of close vocal nonlearning relatives. Among the 21 subunits/subtypes, 19 showed higher and/or lower prominent differential expression in songbird vocal nuclei relative to the surrounding brain subdivisions in which the vocal nuclei are located. This included relatively lower levels of all four AMPA subunits in lMAN, strikingly higher levels of the kainite subunit GluR5 in the robust nucleus of the arcopallium (RA), higher and lower levels respectively of the NMDA subunits NR2A and NR2B in most vocal nuclei and lower levels of the metabotropic group I subtypes (mGluR1 and -5) in most vocal nuclei and the group II subtype (mGluR2), showing a unique expression pattern of very low levels in RA and very high levels in HVC. The splice variants of AMPA subunits showed further differential expression in vocal nuclei. Some of the receptor subunits/subtypes also showed differential expression in hummingbird and parrot vocal nuclei. The magnitude of differential expression in vocal nuclei of all three vocal learners was unique compared with the smaller magnitude of differences found for nonvocal areas of vocal learners and vocal nonlearners. Our results suggest that evolution of vocal learning was accompanied by differential expression of a conserved gene family for synaptic transmission and plasticity in vocal nuclei. They also suggest

  5. Modeling of glutamate-induced dynamical patterns

    DEFF Research Database (Denmark)

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

    2009-01-01

    Based on established physiological mechanisms, the paper presents a detailed computer model, which supports the hypothesis that temporal lobe epilepsy may be caused by failure of glutamate reuptake from the extracellular space. The elevated glutamate concentration causes an increased activation o...... of NMDA receptors in pyramidal neurons, which in turn leads to neuronal dynamics that is qualitatively identical to epileptiform activity. We identify by chaos analysis a surprising possibility that muscarinergic receptors can help the system out of a chaotic regime....

  6. [Glutamate neurotransmission, stress and hormone secretion].

    Science.gov (United States)

    Jezová, D; Juránková, E; Vigas, M

    1995-11-01

    Glutamate neurotransmission has been investigated in relation to several physiological processes (learning, memory) as well as to neurodegenerative and other disorders. Little attention has been paid to its involvement in neuroendocrine response during stress. Penetration of excitatory amino acids from blood to the brain is limited by the blood-brain barrier. As a consequence, several toxic effects but also bioavailability for therapeutic purposes are reduced. A free access to circulating glutamate is possible only in brain structures lacking the blood-brain barrier or under conditions of its increased permeability. Excitatory amino acids were shown to stimulate the pituitary hormone release, though the mechanism of their action is still not fully understood. Stress exposure in experimental animals induced specific changes in mRNA levels coding the glutamate receptor subunits in the hippocampus and hypothalamus. The results obtained with the use of glutamate receptor antagonists indicate that a number of specific receptor subtypes contribute to the stimulation of ACTH release during stress. The authors provided also data on the role of NMDA receptors in the control of catecholamine release, particularly in stress-induced secretion of epinephrine. These results were the first piece of evidence on the involvement of endogenous excitatory amino acids in neuroendocrine activation during stress. Neurotoxic effects of glutamate in animals are well described, especially after its administration in the neonatal period. In men, glutamate toxicity and its use as a food additive are a continuous subject of discussions. The authors found an increase in plasma cortisol and norepinephrine, but not epinephrine and prolactin, in response to the administration of a high dose of glutamate. It cannot be excluded that these effects might be induced even by lower doses in situations with increased vulnerability to glutamate action (age, individual variability). (Tab. 1, Fig. 6, Ref. 44.).

  7. : Glutamate receptor 6 gene and autism

    OpenAIRE

    Jamain, Stéphane; Betancur, Catalina; Quach, Hélène; Philippe, Anne; Fellous, Marc; Giros, Bruno; Gillberg, Christopher; Leboyer, Marion; Bourgeron, Thomas

    2002-01-01

    International audience; A genome scan was previously performed and pointed to chromosome 6q21 as a candidate region for autism. This region contains the glutamate receptor 6 (GluR6 or GRIK2) gene, a functional candidate for the syndrome. Glutamate is the principal excitatory neurotransmitter in the brain and is directly involved in cognitive functions such as memory and learning. We used two different approaches, the affected sib-pair (ASP) method and the transmission disequilibrium test (TDT...

  8. Ionotropic glutamate receptors & CNS disorders.

    Science.gov (United States)

    Bowie, Derek

    2008-04-01

    Disorders of the central nervous system (CNS) are complex disease states that represent a major challenge for modern medicine. Although aetilogy is often unknown, it is established that multiple factors such as defects in genetics and/or epigenetics, the environment as well as imbalance in neurotransmitter receptor systems are all at play in determining an individual's susceptibility to disease. Gene therapy is currently not available and therefore, most conditions are treated with pharmacological agents that modify neurotransmitter receptor signaling. Here, I provide a review of ionotropic glutamate receptors (iGluRs) and the roles they fulfill in numerous CNS disorders. Specifically, I argue that our understanding of iGluRs has reached a critical turning point to permit, for the first time, a comprehensive re-evaluation of their role in the cause of disease. I illustrate this by highlighting how defects in AMPA receptor (AMPAR) trafficking are important to fragile X mental retardation and ectopic expression of kainate receptor (KAR) synapses contributes to the pathology of temporal lobe epilepsy. Finally, I discuss how parallel advances in studies of other neurotransmitter systems may allow pharmacologists to work towards a cure for many CNS disorders rather than developing drugs to treat their symptoms.

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

    Science.gov (United States)

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

    2016-01-15

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

  10. Differential NMDA receptor-dependent calcium loading and mitochondrial dysfunction in CA1 vs. CA3 hippocampal neurons.

    Science.gov (United States)

    Stanika, Ruslan I; Winters, Christine A; Pivovarova, Natalia B; Andrews, S Brian

    2010-02-01

    Hippocampal CA1 pyramidal neurons are selectively vulnerable to ischemia, while adjacent CA3 neurons are relatively resistant. Although glutamate receptor-mediated mitochondrial Ca(2+) overload and dysfunction is a major component of ischemia-induced neuronal death, no direct relationship between selective neuronal vulnerability and mitochondrial dysfunction has been demonstrated in intact brain preparations. Here, we show that in organotypic slice cultures NMDA induces much larger Ca(2+) elevations in vulnerable CA1 neurons than in resistant CA3. Consequently, CA1 mitochondria exhibit stronger calcium accumulation, more extensive swelling and damage, stronger depolarization of their membrane potential, and a significant increase in ROS generation. NMDA-induced Ca(2+) and ROS elevations were abolished in Ca(2+)-free medium or by NMDAR antagonists, but not by zinc chelation. We conclude that Ca(2)(+) overload-dependent mitochondrial dysfunction is a determining factor in the selective vulnerability of CA1 neurons.

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

    Directory of Open Access Journals (Sweden)

    Haruka Aoki

    2014-01-01

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

  12. 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)

  13. 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 decar

  14. 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 decar

  15. Activation of Pedunculopontine Glutamate Neurons Is Reinforcing.

    Science.gov (United States)

    Yoo, Ji Hoon; Zell, Vivien; Wu, Johnathan; Punta, Cindy; Ramajayam, Nivedita; Shen, Xinyi; Faget, Lauren; Lilascharoen, Varoth; Lim, Byung Kook; Hnasko, Thomas S

    2017-01-04

    Dopamine transmission from midbrain ventral tegmental area (VTA) neurons underlies behavioral processes related to motivation and drug addiction. The pedunculopontine tegmental nucleus (PPTg) is a brainstem nucleus containing glutamate-, acetylcholine-, and GABA-releasing neurons with connections to basal ganglia and limbic brain regions. Here we investigated the role of PPTg glutamate neurons in reinforcement, with an emphasis on their projections to VTA dopamine neurons. We used cell-type-specific anterograde tracing and optogenetic methods to selectively label and manipulate glutamate projections from PPTg neurons in mice. We used anatomical, electrophysiological, and behavioral assays to determine their patterns of connectivity and ascribe functional roles in reinforcement. We found that photoactivation of PPTg glutamate cell bodies could serve as a direct positive reinforcer on intracranial self-photostimulation assays. Further, PPTg glutamate neurons directly innervate VTA; photostimulation of this pathway preferentially excites VTA dopamine neurons and is sufficient to induce behavioral reinforcement. These results demonstrate that ascending PPTg glutamate projections can drive motivated behavior, and PPTg to VTA synapses may represent an important target relevant to drug addiction and other mental health disorders. Uncovering brain circuits underlying reward-seeking is an important step toward understanding the circuit bases of drug addiction and other psychiatric disorders. The dopaminergic system emanating from the ventral tegmental area (VTA) plays a key role in regulating reward-seeking behaviors. We used optogenetics to demonstrate that the pedunculopontine tegmental nucleus sends glutamatergic projections to VTA dopamine neurons, and that stimulation of this circuit promotes behavioral reinforcement. The findings support a critical role for pedunculopontine tegmental nucleus glutamate neurotransmission in modulating VTA dopamine neuron activity and

  16. Methamphetamine induces dopamine D1 receptor-dependent endoplasmic reticulum stress-related molecular events in the rat striatum.

    Directory of Open Access Journals (Sweden)

    Subramaniam Jayanthi

    Full Text Available Methamphetamine (METH is an illicit toxic psychostimulant which is widely abused. Its toxic effects depend on the release of excessive levels of dopamine (DA that activates striatal DA receptors. Inhibition of DA-mediated neurotransmission by the DA D1 receptor antagonist, SCH23390, protects against METH-induced neuronal apoptosis. The initial purpose of the present study was to investigate, using microarray analyses, the influence of SCH23390 on transcriptional responses in the rat striatum caused by a single METH injection at 2 and 4 hours after drug administration. We identified 545 out of a total of 22,227 genes as METH-responsive. These include genes which are involved in apoptotic pathways, endoplasmic reticulum (ER stress, and in transcription regulation, among others. Of these, a total of 172 genes showed SCH23390-induced inhibition of METH-mediated changes. Among these SCH23390-responsive genes were several genes that are regulated during ER stress, namely ATF3, HSP27, Hmox1, HSP40, and CHOP/Gadd153. The secondary goal of the study was to investigate the role of DA D1 receptor stimulation on the expression of genes that participate in ER stress-mediated molecular events. We thus used quantitative PCR to confirm changes in the METH-responsive ER genes identified by the microarray analyses. We also measured the expression of these genes and of ATF4, ATF6, BiP/GRP78, and of GADD34 over a more extended time course. SCH23390 attenuated or blocked METH-induced increases in the expression of the majority of these genes. Western blot analysis revealed METH-induced increases in the expression of the antioxidant protein, Hmox1, which lasted for about 24 hours after the METH injection. Additionally, METH caused DA D1 receptor-dependent transit of the Hmox1 regulator protein, Nrf2, from cytosolic into nuclear fractions where the protein exerts its regulatory functions. When taken together, these findings indicate that SCH23390 can provide

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

    Directory of Open Access Journals (Sweden)

    Beatrice Bechi

    2014-05-01

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

  18. GLT-1: The elusive presynaptic glutamate transporter.

    Science.gov (United States)

    Rimmele, Theresa S; Rosenberg, Paul A

    2016-09-01

    Historically, glutamate uptake in the CNS was mainly attributed to glial cells for three reasons: 1) none of the glutamate transporters were found to be located in presynaptic terminals of excitatory synapses; 2) the putative glial transporters, GLT-1 and GLAST are expressed at high levels in astrocytes; 3) studies of the constitutive GLT-1 knockout as well as pharmacological studies demonstrated that >90% of glutamate uptake into forebrain synaptosomes is mediated by the operation of GLT-1. Here we summarize the history leading up to the recognition of GLT-1a as a presynaptic glutamate transporter. A major issue now is understanding the physiological and pathophysiological significance of the expression of GLT-1 in presynaptic terminals. To elucidate the cell-type specific functions of GLT-1, a conditional knockout was generated with which to inactivate the GLT-1 gene in different cell types using Cre/lox technology. Astrocytic knockout led to an 80% reduction of GLT-1 expression, resulting in intractable seizures and early mortality as seen also in the constitutive knockout. Neuronal knockout was associated with no obvious phenotype. Surprisingly, synaptosomal uptake capacity (Vmax) was found to be significantly reduced, by 40%, in the neuronal knockout, indicating that the contribution of neuronal GLT-1 to synaptosomal uptake is disproportionate to its protein expression (5-10%). Conversely, the contribution of astrocytic GLT-1 to synaptosomal uptake was much lower than expected. In contrast, the loss of uptake into liposomes prepared from brain protein from astrocyte and neuronal knockouts was proportionate with the loss of GLT-1 protein, suggesting that a large portion of GLT-1 in astrocytic membranes in synaptosomal preparations is not functional, possibly because of a failure to reseal. These results suggest the need to reinterpret many previous studies using synaptosomal uptake to investigate glutamate transport itself as well as changes in glutamate

  19. 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

  20. 13C–Metabolic enrichment of glutamate in glutamate dehydrogenase mutants of Saccharomyces cerevisiae

    OpenAIRE

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

    2011-01-01

    Glutamate dehydrogenases (GDH) interconvert α-ketoglutarate and glutamate. In yeast, NADP-dependent enzymes, encoded by GDH1 and GDH3, are reported to synthesize glutamate from α-ketoglutarate, while an NAD-dependent enzyme, encoded by GDH2, catalyzes the reverse. Cells were grown in acetate/raffinose (YNAceRaf) to examine the role(s) of these enzymes during aerobic metabolism. In YNAceRaf the doubling time of wild type, gdh2Δ, and gdh3Δ cells was comparable at ~ 4 hours. NADP-dependent GDH a...

  1. Molecular physiology of vesicular glutamate transporters in the digestive system

    Institute of Scientific and Technical Information of China (English)

    Tao Li; Fayez K. Ghishan; Liqun Bai

    2005-01-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS). Packaging and storage of glutamate into glutamatergic neuronal vesicles require ATP-dependent vesicular glutamate uptake systems, which utilize the electrochemical proton gradient as a driving force. Three vesicular glutamate transporters (VGLUT1-3) have been recently identified from neuronal tissue where they play a key role to maintain the vesicular glutamate level. Recently, it has been demonstrated that glutamate signaling is also functional in peripheral neuronal and non-neuronal tissues, and occurs in sites of pituitary, adrenal, pineal glands, bone, GI tract, pancreas,skin, and testis. The glutamate receptors and VGLUTs in digestivesystem have been found in both neuronal and endocrinal cells. The glutamate signaling in the digestive system may have significant relevance to diabetes and GI tract motility disorders. This review will focus on the most recent update of molecular physiology of digestive VGLUTs.

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

    African Journals Online (AJOL)

    Uche

    Background: Monosodium glutamate (MSG) is a commonly used food ... The rats were given water ad libitum. ... that monosodium glutamate consumption may have some deleterious effects on ..... (MSG); obese rat as a model for the study of.

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

    NARCIS (Netherlands)

    Slotboom, DJ; Konings, WN; Lolkema, JS

    2001-01-01

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

  4. Activation of mGluR7s inhibits cocaine-induced reinstatement of drug-seeking behavior by a nucleus accumbens glutamate-mGluR2/3 mechanism in rats.

    Science.gov (United States)

    Li, Xia; Li, Jie; Gardner, Eliot L; Xi, Zheng-Xiong

    2010-09-01

    The metabotropic glutamate receptor 7 (mGluR7) has been reported to be involved in cocaine and alcohol self-administration. However, the role of mGluR7 in relapse to drug seeking is unknown. Using a rat relapse model, we found that systemic administration of AMN082, a selective mGluR7 allosteric agonist, dose-dependently inhibits cocaine-induced reinstatement of drug-seeking behavior. Intracranial microinjections of AMN082 into the nucleus accumbens (NAc) or ventral pallidum, but not the dorsal striatum, also inhibited cocaine-primed reinstatement, an effect that was blocked by local co-administration of MMPIP, a selective mGluR7 antagonist. In vivo microdialysis demonstrated that cocaine priming significantly increased extracellular dopamine in the NAc, ventral pallidum and dorsal striatum, while increasing extracellular glutamate in the NAc only. AMN082 alone failed to alter extracellular dopamine, but produced a slow-onset long-lasting increase in extracellular glutamate in the NAc only. Pre-treatment with AMN082 dose-dependently blocked both cocaine-enhanced NAc glutamate and cocaine-induced reinstatement, an effect that was blocked by MMPIP or LY341497 (a selective mGluR2/3 antagonist). These data suggest that mGluR7 activation inhibits cocaine-induced reinstatement of drug-seeking behavior by a glutamate-mGluR2/3 mechanism in the NAc. The present findings support the potential use of mGluR7 agonists for the treatment of cocaine addiction.

  5. Regulation of Synaptic Transmission by Ambient Extracellular Glutamate

    OpenAIRE

    Featherstone, David E.; Scott A. Shippy

    2007-01-01

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

  6. Pharmacological Treatment of Glutamate Excitotoxicity Following Traumatic Brain Injury

    Science.gov (United States)

    2009-01-14

    Cannabinoid receptor agonists inhibit glutamatergic synaptic transmission in rat hippocampal cultures. J Neurosci. 1996 Jul 15;16(14):4322-34...19 Glutamate Receptor Antagonists...Glutamate excitotoxicity, another form of secondary injury, is defined as cell damage resulting from the overactivation of glutamate receptors . It

  7. 21 CFR 182.1047 - Glutamic acid hydrochloride.

    Science.gov (United States)

    2010-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Weifu Dong

    2013-11-01

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

  9. Evaluation of hydrogel-coated glutamate microsensors.

    Science.gov (United States)

    Oldenziel, Weite H; Dijkstra, Gerrit; Cremers, Thomas I F H; Westerink, Ben H C

    2006-05-15

    Glutamate microsensors form a promising analytical tool for monitoring neuronally derived glutamate directly in the brain. However, when a microsensor is implanted in brain tissue, many factors can diminish its performance. Consequently, a thorough characterization and evaluation of a microsensor is required concerning all factors that may possibly be encountered in vivo. The present report deals with the validation of a hydrogel-coated glutamate microsensor. This microsensor is constructed by coating a carbon fiber electrode (10-microm diameter; 300-500 microm long) with a five-component redox hydrogel, in which L-glutamate oxidase, horseradish peroxidase, and ascorbate oxidase are wired via poly(ethylene glycol) diglycidyl ether to an osmium-containing redox polymer. A thin Nafion coating completes the construction. Although this microsensor was previously used in vivo, information concerning its validation is limited. In the present study, attention was given to its selectivity, specificity, calibration, oxygen dependency, biofouling, operating potential dependency, and linear range. In addition, successful microsensor experiments in microdialysate, in vitro (in organotypic hippocampal slice cultures), and in vivo (in anesthesized rats) are shown.

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

    Science.gov (United States)

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

    2011-10-20

    Glutamate dehydrogenases (GDH) interconvert α-ketoglutarate and glutamate. In yeast, NADP-dependent enzymes, encoded by GDH1 and GDH3, are reported to synthesize glutamate from α-ketoglutarate, while an NAD-dependent enzyme, encoded by GDH2, catalyzes the reverse. Cells were grown in acetate/raffinose (YNAceRaf) to examine the role(s) of these enzymes during aerobic metabolism. In YNAceRaf the doubling time of wild type, gdh2Δ, and gdh3Δ cells was comparable at ∼4 h. NADP-dependent GDH activity (Gdh1p+Gdh3p) in wild type, gdh2Δ, and gdh3Δ was decreased ∼80% and NAD-dependent activity (Gdh2p) in wild type and gdh3Δ was increased ∼20-fold in YNAceRaf as compared to glucose. Cells carrying the gdh1Δ allele did not divide in YNAceRaf, yet both the NADP-dependent (Gdh3p) and NAD-dependent (Gdh2p) GDH activity was ∼3-fold higher than in glucose. Metabolism of [1,2-(13)C]-acetate and analysis of carbon NMR spectra were used to examine glutamate metabolism. Incorporation of (13)C into glutamate was nearly undetectable in gdh1Δ cells, reflecting a GDH activity at <15% of wild type. Analysis of (13)C-enrichment of glutamate carbons indicates a decreased rate of glutamate biosynthesis from acetate in gdh2Δ and gdh3Δ strains as compared to wild type. Further, the relative complexity of (13)C-isotopomers at early time points was noticeably greater in gdh3Δ as compared to wild type and gdh2Δ cells. These in vivo data show that Gdh1p is the primary GDH enzyme and Gdh2p and Gdh3p play evident roles during aerobic glutamate metabolism.

  11. 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.

  12. 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

    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...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    Astrocytes take up glutamate in the synaptic area subsequent to glutamatergic transmission by the aid of high affinity glutamate transporters. Glutamate is converted to glutamine or metabolized to support intermediary metabolism and energy production. Glutamate dehydrogenase (GDH) and aspartate...... synthesis of aspartate via pyruvate carboxylation. In the absence of glucose, lactate production from glutamate via malic enzyme was lower in GDH deficient astrocytes. In conclusions, our studies reveal that metabolism via GDH serves an important anaplerotic role by adding net carbon to the TCA cycle...

  14. Scientific Opinion on the safety of the change in the production method of L-glutamic acid (E620, monosodium L-glutamate (E621, monopotassium L-glutamate (E622, calcium di-L-glutamate (E623, monoammonium L-glutamate (E624 and magnesium di-L-glutamate (E625

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to food (ANS

    2015-01-01

    Full Text Available The Panel on Food Additives and Nutrient Sources added to Food (ANS was asked to deliver a scientific opinion evaluating   the safety of the change in the production method for the production of L-glutamic acid (E620, monosodium - L-glutamate (E621, monopotassium L-glutamate (E622, calcium di-L-glutamate (E623, monoammonium L-glutamate (E624 and magnesium di-L-glutamate (E625. The L-glutamic acid is produced by the genetically modified Corynebacterium glutamicum EA-12 strain. The recipient strain Corynebacterium glutamicum  strain2256  has been recommended for Qualified Presumption of Safety (QPS status. No antibiotic resistance genes were left in the genome and neither the production strain nor its recombinant DNA were detected in the final product. The Panel considered there were no safety concerns for consumers from the genetic modification. The proposed uses or use levels of L-glutamic acid and its salt derivatives produced with the current strain and the new genetically modified microorganism (GMM strain will be identical and thus the Panel considered that the exposure to the food additive will remain unaffected. Provided that the L-glutamic acid and its salts both produced with the current strain and with the GMM strain are equal in the specifications and physicochemical characteristics, the biological and toxicological data for the L-glutamic acid and its salts produced with the current strain are considered by the Panel to support the safety of the food additives produced with the GMM strain. The Panel concluded that there are no safety concerns from the  change in the production method of the food additives L-glutamic acid (E620, monosodium L-glutamate (E621, monopotassium L-glutamate (E622, calcium di-L-glutamate (E623, monoammonium L-glutamate (E624 and magnesium di-L-glutamate (E625 meeting their existing specifications.

  15. Glutamate carboxypeptidase II (GCPII) inhibitor 2-PMPA reduces rewarding effects of the synthetic cathinone MDPV in rats: a role for N-acetylaspartylglutamate (NAAG).

    Science.gov (United States)

    Hicks, Callum; Gregg, Ryan A; Nayak, Sunil U; Cannella, Lee Anne; Schena, Giana J; Tallarida, Christopher S; Reitz, Allen B; Smith, Garry R; Rawls, Scott M

    2017-06-01

    Metabotropic glutamate 2 and 3 (mGluR2/3) receptors are implicated in drug addiction as they limit excessive glutamate release during relapse. N-acetylaspartylglutamate (NAAG) is an endogenous mGluR2/3 agonist that is inactivated by the glutamate carboxypeptidase II (GCPII) enzyme. GCPII inhibitors, and NAAG itself, attenuate cocaine-seeking behaviors. However, their effects on the synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV) have not been examined. We determined whether withdrawal following repeated MDPV administration alters GCPII expression in corticolimbic regions. We also examined whether a GCPII inhibitor (2-(phosphonomethyl)-pentanedioic acid (2-PMPA)), and NAAG, reduce the rewarding and locomotor-stimulant effects of MDPV in rats. GCPII was assessed following repeated MDPV exposure (7 days). The effects of 2-PMPA and NAAG on acute MDPV-induced hyperactivity were determined using a locomotor test. We also examined the inhibitory effects of 2-PMPA and NAAG on MDPV-induced place preference, and whether the mGluR2/3 antagonist LY341495 could prevent these effects. MDPV withdrawal reduced GCPII expression in the prefrontal cortex. Systemic injection of 2-PMPA (100 mg/kg) did not affect the hyperactivity produced by MDPV (0.5-3 mg/kg). However, nasal administration of NAAG did reduce MDPV-induced ambulation, but only at the highest dose (500 μg/10 μl). We also showed that 2-PMPA (10-30 mg/kg) and NAAG (10-500 μg/10 μl) dose-dependently attenuated MDPV place preference, and that the effect of NAAG was blocked by LY341495 (3 mg/kg). These findings demonstrate that MDPV withdrawal produces dysregulation in the endogenous NAAG-GCPII signaling pathway in corticolimbic circuitry. Systemic administration of the GCPII inhibitor 2-PMPA, or NAAG, attenuates MDPV reward.

  16. 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.

  17. Identification of glutamate transporters and receptors in mouse testis

    Institute of Scientific and Technical Information of China (English)

    Jia-hua HU; Na YANG; Ying-hua MA; Jie JIANG; Jin-fu ZHANG; Jian FEI; Li-he GUO

    2004-01-01

    AIM: To investigate the presence of glutamate transporters and receptors in mouse testis. METHODS: Glutamate uptake analysis was performed to study the function of glutamate transporters in mouse testis. Comparative RT-PCR technique and sequencing analysis were used to study the expression of glutamate receptors and transporters in mouse testis. RESULTS: Mouse testis possessed glutamate uptake capacity with sodium-dependence. Vmax value of glutamate uptake was (1.60 ± 0.21) pmol/min per mg protein and Km value of glutamate uptake was (11.0±1.6) μmol/L in mouse testis according to saturation analysis. Furthermore, the uptake activity could be inhibited by DHK (GLT1 selective inhibitor) and THA (glutamate uptake inhibitor). In addition, RT-PCR results revealed that glutamate transporters (GLT1 and EAAC1) and ionotropic glutamate receptors (NR1, NR2B, GluR6 and KA2) were expressed in mouse testis. CONCLUSION: Glutamate transporters and receptors do exist in mouse testis.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Monnerie, Hubert; Le Roux, Peter D

    2008-09-01

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

  20. The Glutamine-Glutamate/GABA Cycle

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  1. Sertraline reduces glutamate uptake in human platelets.

    Science.gov (United States)

    Rodrigues, Débora Olmedo; Bristot, Ivi Juliana; Klamt, Fábio; Frizzo, Marcos Emílio

    2015-12-01

    Mitochondrial damage and declines in ATP levels have been recently attributed to sertraline. The effects of sertraline on different parameters were investigated in washed platelets from 18 healthy male volunteers, after 24h of drug exposure. Sertraline toxicity was observed only at the highest concentrations, 30 and 100 μM, which significantly reduced platelet viability to 76 ± 3% and 20 ± 2%, respectively. The same concentrations significantly decreased total ATP to 73 ± 3% and 13 ± 2%, respectively. Basal values of glycogen were not significantly affected by sertraline treatment. Glutamate uptake was significantly reduced after treatment with 3, 30 and 100 μM, by 28 ± 6%, 32 ± 5% and 54 ± 4%, respectively. Our data showed that sertraline at therapeutic concentrations does not compromise platelet viability and ATP levels, but they suggest that in a situation where extracellular glutamate levels are potentially increased, sertraline might aggravate an excitotoxic condition.

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

    Directory of Open Access Journals (Sweden)

    Dickenson Anthony H

    2009-02-01

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

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

    Science.gov (United States)

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

    2017-04-01

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

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    Dougherty Patrick M

    2009-07-01

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

  6. Pharmacokinetics of glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase and their blood glutamate-lowering activity in naïve rats.

    Science.gov (United States)

    Boyko, Matthew; Stepensky, David; Gruenbaum, Benjamin F; Gruenbaum, Shaun E; Melamed, Israel; Ohayon, Sharon; Glazer, Michael; Shapira, Yoram; Zlotnik, Alexander

    2012-10-01

    Traumatic brain injury (TBI) and stroke lead to elevated levels of glutamate in the brain that negatively affect the neurological outcomes in both animals and humans. Intravenous administration of glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) enzymes can be used to lower the blood glutamate levels and to improve the neurological outcome following TBI and stroke. The objective of this study was to analyze the pharmacokinetics and to determine the glutamate-lowering effects of GOT and GPT enzymes in naïve rats. We determined the time course of serum GOT, GPT, and glutamate levels following a single intravenous administration of two different doses of each one of the studied enzymes. Forty-six male rats were randomly assigned into one of 5 treatment groups: saline (control), human GOT at dose 0.03 and 0.06 mg/kg and porcine GPT at dose 0.6 and 1.2 mg/kg. Blood samples were collected at baseline, 5 min, and 2, 4, 8, 12, and 24 h after the drug injection and GOT, GPT and glutamate levels were determined. The pharmacokinetics of both GOT and GPT followed one-compartment model, and both enzymes exhibited substantial glutamate-lowering effects following intravenous administration. Analysis of the pharmacokinetic data indicated that both enzymes were distributed predominantly in the blood (central circulation) and did not permeate to the peripheral organs and tissues. Several-hour delay was present between the time course of the enzyme levels and the glutamate-lowering effects (leading to clock-wise hysteresis on concentration-effect curves), apparently due to the time that is required to affect the pool of serum glutamate. We conclude that the interaction between the systemically-administered enzymes (GOT and GPT) and the glutamate takes place in the central circulation. Thus, glutamate-lowering effects of GOT and GPT apparently lead to redistribution of the excess glutamate from the brain's extracellular fluid into the blood and can

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

    Science.gov (United States)

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

    2011-08-01

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

  8. Topiramate antagonism of L-glutamate-induced paroxysms in planarians

    Science.gov (United States)

    Raffa, Robert B.; Finno, Kristin E.; Tallarida, Christopher S.; Rawls, Scott M.

    2010-01-01

    We recently reported that NMDA (N-Methyl-D-aspartate) and AMPA (α-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid) induce concentration-dependent paroxysms in planarians (Dugesia dorotocephala). Since the postulated mechanisms of action of the sulfamate-substituted monosaccharide antiepileptic drug topiramate include inhibition of glutamate-activated ion channels, we tested the hypothesis that topiramate would inhibit glutamate-induced paroxysms in our model. We demonstrate that: (1) L-glutamate (1–10 mM), but not D-glutamate, induced dose-related paroxysms, and that (2) topiramate dose-relatedly (0.3–3 mM) inhibited L-glutamate-induced paroxysms. These results provide further evidence of a topiramate-sensitive glutamate receptor-mediated activity in this model. PMID:20863783

  9. From the Cover: Glutamate antagonists limit tumor growth

    Science.gov (United States)

    Rzeski, Wojciech; Turski, Lechoslaw; Ikonomidou, Chrysanthy

    2001-05-01

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

  10. [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.

  11. Glutamate neurotransmission is affected in prenatally stressed offspring

    DEFF Research Database (Denmark)

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

    2015-01-01

    with synaptic loss. Since metabolism of glutamate is dependent on interactions between neurons and surrounding astroglia, our results suggest that glutamate neurotransmitter pathways might be impaired in the brain of prenatally stressed rats. To study the effect of prenatal stress on the metabolism...... and neurotransmitter function of glutamate, pregnant rats were subjected to restrain stress during the last week of gestation. Brains of the adult offspring were used to assess glutamate metabolism, uptake and release as well as expression of glutamate receptors and transporters. While glutamate metabolism...... was not affected it was found that prenatal stress (PS) changed the expression of the transporters, thus, producing a higher level of vesicular vGluT-1 in the frontal cortex (FCx) and elevated levels of GLT1 protein and messenger RNA in the hippocampus (HPC) of adult male PS offspring. We also observed increased...

  12. [Autoantibodies to glutamate and GABA in opiate addiction].

    Science.gov (United States)

    Vetrile, L A; Fomina, V G; Nevidimova, T I; Vetlugina, T P; Batukhtina, E I; Savochkina, D N; Zakharova, I A; Davydova, T V

    2015-01-01

    Blood serum from 129 patients with opium addiction at different stages of the disease and 63 donors (control group) was examined for the presence of autoantibodies to the exciting and inhibitory amino acids glutamate and GABA. It was shown enhanced production of autoantibodies to glutamate and GABA. Dependence of the level and frequency of detec- tion of autoantibodies to glutamate and GABA on the stage of the disease was revealed.

  13. Increased expression of cystine/glutamate antiporter in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Villoslada Pablo

    2011-06-01

    Full Text Available Abstract Background Glutamate excitotoxicity contributes to oligodendrocyte and tissue damage in multiple sclerosis (MS. Intriguingly, glutamate level in plasma and cerebrospinal fluid of MS patients is elevated, a feature which may be related to the pathophysiology of this disease. In addition to glutamate transporters, levels of extracellular glutamate are controlled by cystine/glutamate antiporter xc-, an exchanger that provides intracellular cystine for production of glutathione, the major cellular antioxidant. The objective of this study was to analyze the role of the system xc- in glutamate homeostasis alterations in MS pathology. Methods Primary cultures of human monocytes and the cell line U-937 were used to investigate the mechanism of glutamate release. Expression of cystine glutamate exchanger (xCT was quantified by quantitative PCR, Western blot, flow cytometry and immunohistochemistry in monocytes in vitro, in animals with experimental autoimmune encephalomyelitis (EAE, the animal model of MS, and in samples of MS patients. Results and discussion We show here that human activated monocytes release glutamate through cystine/glutamate antiporter xc- and that the expression of the catalytic subunit xCT is upregulated as a consequence of monocyte activation. In addition, xCT expression is also increased in EAE and in the disease proper. In the later, high expression of xCT occurs both in the central nervous system (CNS and in peripheral blood cells. In particular, cells from monocyte-macrophage-microglia lineage have higher xCT expression in MS and in EAE, indicating that immune activation upregulates xCT levels, which may result in higher glutamate release and contribution to excitotoxic damage to oligodendrocytes. Conclusions Together, these results reveal that increased expression of the cystine/glutamate antiporter system xc- in MS provides a link between inflammation and excitotoxicity in demyelinating diseases.

  14. Exercise increases mitochondrial glutamate oxidation in the mouse cerebral cortex.

    Science.gov (United States)

    Herbst, Eric A F; Holloway, Graham P

    2016-07-01

    The present study investigated the impact of acute exercise on stimulating mitochondrial respiratory function in mouse cerebral cortex. Where pyruvate-stimulated respiration was not affected by acute exercise, glutamate respiration was enhanced following the exercise bout. Additional assessment revealed that this affect was dependent on the presence of malate and did not occur when substituting glutamine for glutamate. As such, our results suggest that glutamate oxidation is enhanced with acute exercise through activation of the malate-aspartate shuttle.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  17. How Glutamate Is Managed by the Blood–Brain Barrier

    Science.gov (United States)

    Hawkins, Richard A.; Viña, Juan R.

    2016-01-01

    A facilitative transport system exists on the blood–brain barrier (BBB) that has been tacitly assumed to be a path for glutamate entry to the brain. However, glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter the brain in appreciable quantities except in those small regions with fenestrated capillaries (circumventricular organs). The situation became understandable when luminal (blood facing) and abluminal (brain facing) membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exists only on the luminal membranes, whereas Na+-dependent transport systems for glutamate, glutamine, and some other amino acids are present only on the abluminal membrane. The Na+-dependent cotransporters of the abluminal membrane are in a position to actively transport amino acids from the extracellular fluid (ECF) into the endothelial cells of the BBB. These powerful secondary active transporters couple with the energy of the Na+-gradient to move glutamate and glutamine into endothelial cells, whereupon glutamate can exit to the blood on the luminal facilitative glutamate transporter. Glutamine may also exit the brain via separate facilitative transport system that exists on the luminal membranes, or glutamine can be hydrolyzed to glutamate within the BBB, thereby releasing ammonia that is freely diffusible. The γ-glutamyl cycle participates indirectly by producing oxoproline (pyroglutamate), which stimulates almost all secondary active transporters yet discovered in the abluminal membranes of the BBB. PMID:27740595

  18. How Glutamate Is Managed by the Blood–Brain Barrier

    Directory of Open Access Journals (Sweden)

    Richard A. Hawkins

    2016-10-01

    Full Text Available A facilitative transport system exists on the blood–brain barrier (BBB that has been tacitly assumed to be a path for glutamate entry to the brain. However, glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter the brain in appreciable quantities except in those small regions with fenestrated capillaries (circumventricular organs. The situation became understandable when luminal (blood facing and abluminal (brain facing membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exists only on the luminal membranes, whereas Na+-dependent transport systems for glutamate, glutamine, and some other amino acids are present only on the abluminal membrane. The Na+-dependent cotransporters of the abluminal membrane are in a position to actively transport amino acids from the extracellular fluid (ECF into the endothelial cells of the BBB. These powerful secondary active transporters couple with the energy of the Na+-gradient to move glutamate and glutamine into endothelial cells, whereupon glutamate can exit to the blood on the luminal facilitative glutamate transporter. Glutamine may also exit the brain via separate facilitative transport system that exists on the luminal membranes, or glutamine can be hydrolyzed to glutamate within the BBB, thereby releasing ammonia that is freely diffusible. The γ-glutamyl cycle participates indirectly by producing oxoproline (pyroglutamate, which stimulates almost all secondary active transporters yet discovered in the abluminal membranes of the BBB.

  19. CONTROL OF GLUTAMATE OXIDATION IN BRAIN AND LIVER MITOCHONDRIAL SYSTEMS.

    Science.gov (United States)

    BALAZS, R

    1965-05-01

    1. Glutamate oxidation in brain and liver mitochondrial systems proceeds mainly through transamination with oxaloacetate followed by oxidation of the alpha-oxoglutarate formed. Both in the presence and absence of dinitrophenol in liver mitochondria this pathway accounted for almost 80% of the uptake of glutamate. In brain preparations the transamination pathway accounted for about 90% of the glutamate uptake. 2. The oxidation of [1-(14)C]- and [5-(14)C]-glutamate in brain preparations is compatible with utilization through the tricarboxylic acid cycle, either after the formation of alpha-oxoglutarate or after decarboxylation to form gamma-aminobutyrate. There is no indication of gamma-decarboxylation of glutamate. 3. The high respiratory control ratio obtained with glutamate as substrate in brain mitochondrial preparations is due to the low respiration rate in the absence of ADP: this results from the low rate of formation of oxaloacetate under these conditions. When oxaloacetate is made available by the addition of malate or of NAD(+), the respiration rate is increased to the level obtained with other substrates. 4. When the transamination pathway of glutamate oxidation was blocked with malonate, the uptake of glutamate was inhibited in the presence of ADP or ADP plus dinitrophenol by about 70 and 80% respectively in brain mitochondrial systems, whereas the inhibition was only about 50% in dinitrophenol-stimulated liver preparations. In unstimulated liver mitochondria in the presence of malonate there was a sixfold increase in the oxidation of glutamate by the glutamate-dehydrogenase pathway. Thus the operating activity of glutamate dehydrogenase is much less than the ;free' (non-latent) activity. 5. The following explanation is put forward for the control of glutamate metabolism in liver and brain mitochondrial preparations. The oxidation of glutamate by either pathway yields alpha-oxoglutarate, which is further metabolized. Since aspartate aminotransferase is

  20. GDH3 encodes a glutamate dehydrogenase isozyme, a previously unrecognized route for glutamate biosynthesis in Saccharomyces cerevisiae.

    OpenAIRE

    Avendaño, A; DeLuna, A.; Olivera, H; Valenzuela, L.; A. Gonzalez

    1997-01-01

    It has been considered that the yeast Saccharomyces cerevisiae, like many other microorganisms, synthesizes glutamate through the action of NADP+-glutamate dehydrogenase (NADP+-GDH), encoded by GDH1, or through the combined action of glutamine synthetase and glutamate synthase (GOGAT), encoded by GLN1 and GLT1, respectively. A double mutant of S. cerevisiae lacking NADP+-GDH and GOGAT activities was constructed. This strain was able to grow on ammonium as the sole nitrogen source and thus to ...

  1. Repeated Cycles of Chronic Intermittent Ethanol Exposure Increases Basal Glutamate in the Nucleus Accumbens of Mice without affecting glutamate transport

    Directory of Open Access Journals (Sweden)

    William C. Griffin

    2015-02-01

    Full Text Available Repeated cycles of chronic intermittent ethanol (CIE exposure increase voluntary consumption of ethanol in mice. Previous work has shown that extracellular glutamate in the nucleus accumbens (NAc is significantly elevated in ethanol dependent mice and that pharmacologically manipulating glutamate concentrations in the NAc will alter ethanol drinking, indicating that glutamate homeostasis plays a crucial role in ethanol drinking in this model. The present studies were designed to measure extracellular glutamate at a time point in which mice would ordinarily be allowed voluntary access to ethanol in the CIE model and, additionally, to measure glutamate transport capacity in the NAc at the same time point. Extracellular glutamate was measured using quantitative microdialysis procedures. Glutamate transport capacity was measured under Na+ dependent and Na+ independent conditions to determine whether the function of excitatory amino acid transporters (EAATs; also known as system XAG or of system Xc- (Glial cysteine-glutamate exchanger was influenced by CIE exposure. The results of the quantitative microdialysis experiment confirm increased extracellular glutamate (~2 –fold in the NAc of CIE exposed mice (i.e. ethanol-dependent compared to non-dependent mice in the NAc, consistent with earlier work. However, the increase in extracellular glutamate was not due to altered transporter function in the NAc of ethanol-dependent mice, because neither Na+ dependent nor Na+ independent glutamate transport was significantly altered by CIE exposure. These findings point to the possibility that hyperexcitability of cortical-striatal pathways underlies the increases in extracellular glutamate found in the nucleus accumbens of ethanol-dependent mice.

  2. PGE2 released by primary sensory neurons modulates Toll-like receptor 4 activities through an EP4 receptor-dependent process.

    Science.gov (United States)

    Tse, Kai-Hei; Chow, Kevin B S; Wise, Helen

    2016-04-15

    Exogenous prostaglandin E2 (PGE2) displays mixed regulatory properties with regard to inflammatory gene expression in dorsal root ganglion (DRG) cells. We show here that endogenously-produced nanomolar concentrations of PGE2, such as that generated in response to Toll-like receptor 4 (TLR4) stimulation, inhibits both cyclooxygenase-2 (COX-2) and tumour necrosis factor alpha (TNFα) mRNA expression in DRG cells in an EP4 receptor-dependent manner. DRG neurons appear to be the major source of PGE2 in the DRG and likely serve as both an autocrine and paracrine system for limiting over-activation of both DRG neurons and glial cells in response to TLR4 stimulation. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. 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...... 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...

  4. Identification and characterization of a bacterial glutamic peptidase

    Directory of Open Access Journals (Sweden)

    Jensen Kenneth

    2010-12-01

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

  5. Linking tricyclic antidepressants to ionotropic glutamate receptors.

    Science.gov (United States)

    Stoll, Laura; Gentile, Lisa

    2005-07-29

    Although tricyclic antidepressants have been in existence since the 1940s when they were discovered upon screening iminodibenzyl derivatives for other potential therapeutic uses, their mechanism of action has remained unclear [A. Goodman Gilman, T.W. Rall, A.S. Nies, P. Taylor, Goodman and Gilman's The Pharmacological Basis of Therapeutics, eighth ed., Pergamon Press, New York, 1990]. In addition to their ability to hinder the reuptake of biogenic amines, there is mounting evidence that the tricyclic antidepressants inhibit glutamate transmission. Here, intrinsic tryptophan fluorescence spectroscopy is used to document the binding of desipramine, a member of the tricyclic antidepressant family, to a well-defined extracellular glutamate binding domain (S1S2) of the GluR2 subunit of the amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. The binding is distinct from those of other known effectors of the receptor, including the endogenous sulfated neurosteroids pregnenolone sulfate and 3alpha-hydroxy-5beta-pregnan-20-one sulfate, and is consistent with a conformational change upon binding that is allosterically transmitted to the channel region of the receptor.

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

    Science.gov (United States)

    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.

  7. In vitro evidence for the brain glutamate efflux hypothesis

    DEFF Research Database (Denmark)

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

    2012-01-01

    The concentration of the excitotoxic amino acid, L-glutamate, in brain interstitial fluid is tightly regulated by uptake transporters and metabolism in astrocytes and neurons. The aim of this study was to investigate the possible role of the blood-brain barrier endothelium in brain L-glutamate ho...

  8. Glutamate Efflux at the Blood-Brain Barrier

    DEFF Research Database (Denmark)

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

    2014-01-01

    L-Glutamate is considered the most important excitatory amino acid in the mammalian brain. Strict control of its concentration in the brain interstitial fluid is important to maintain neurotransmission and avoid excitotoxicity. The role of astrocytes in handling L-glutamate transport and metaboli...

  9. 21 CFR 522.1125 - Hemoglobin glutamer-200 (bovine).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hemoglobin glutamer-200 (bovine). 522.1125 Section... § 522.1125 Hemoglobin glutamer-200 (bovine). (a) Specifications. Each 125 milliliter bag contains 13 grams per deciliter of polymerized hemoglobin of bovine origin in modified Lactated Ringer's...

  10. Brain microdialysis of GABA and glutamate : What does it signify?

    NARCIS (Netherlands)

    Timmerman, W; Westerink, BHC

    1997-01-01

    Microdialysis has become a frequently used method to study extracellular levels of GABA and glutamate in the central nervous system. However, the fact that the major part of GABA and glutamate as measured by microdialysis does not fulfill the classical criteria for exocytotic release questions the v

  11. Application of a glutamate microsensor to brain tissue

    NARCIS (Netherlands)

    Oldenziel, Weite Hendrik

    2006-01-01

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

  12. Dietary glutamate will not affect pain in fibromyalgia

    NARCIS (Netherlands)

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

    2004-01-01

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

  13. 78 FR 76321 - Monosodium Glutamate From China and Indonesia

    Science.gov (United States)

    2013-12-17

    ... COMMISSION Monosodium Glutamate From China and Indonesia Determinations On the basis of the record \\1... injured by reason of imports from China and Indonesia of monosodium glutamate, provided for in subheading... United States at less than fair value (LTFV) and subsidized by the Governments of China and Indonesia. \\1...

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

    Science.gov (United States)

    Formánek, Pavel; Vranová, Valerie; Lojková, Lea

    2015-02-01

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

  15. A novel glutamate dehydrogenase from bovine brain: purification and characterization.

    Science.gov (United States)

    Lee, J; Kim, S W; Cho, S W

    1995-08-01

    A soluble form of novel glutamate dehydrogenase has been purified from bovine brain. The preparation was homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and composed of six identical subunits having a subunit size of 57,500 Da. The biochemical properties of glutamate dehydrogenase such as N-terminal amino acids sequences, kinetic parameters, amino acids analysis, and optimum pH were examined in both reductive amination of alpha-ketoglutarate and oxidative deamination of glutamate. N-terminal amino acid sequences of the bovine brain enzyme showed the significant differences in the first 5 amino acids compared to other glutamate dehydrogenases from various sources. These results indicate that glutamate dehydrogenase isolated from bovine brain is a novel polypeptide.

  16. The effects of prenatal H1N1 infection at E16 on FMRP, glutamate, GABA, and reelin signaling systems in developing murine cerebellum.

    Science.gov (United States)

    Fatemi, S Hossein; Folsom, Timothy D; Liesch, Stephanie B; Kneeland, Rachel E; Karkhane Yousefi, Mahtab; Thuras, Paul D

    2017-05-01

    Prenatal viral infection has been identified as a potential risk factor for the development of neurodevelopmental disorders such as schizophrenia and autism. Additionally, dysfunction in gamma-aminobutyric acid, Reelin, and fragile X mental retardation protein (FMRP)-metabotropic glutamate receptor 5 signaling systems has also been demonstrated in these two disorders. In the current report, we have characterized the developmental profiles of selected markers for these systems in cerebella of mice born to pregnant mice infected with human influenza (H1N1) virus on embryonic day 16 or sham-infected controls using SDS-PAGE and Western blotting techniques and evaluated the presence of abnormalities in the above-mentioned markers during brain development. The cerebellum was selected in light of emerging evidence that it plays roles in learning, memory, and emotional processing-all of which are disrupted in autism and schizophrenia. We identified unique patterns of gene and protein expression at birth (postnatal day 0 [P0]), childhood (P14), adolescence (P35), and young adulthood (P56) in both exposed and control mouse progeny. We also identified significant differences in protein expression for FMRP, very-low-density lipoprotein receptor, and glutamic acid decarboxylase 65 and 67 kDa proteins at specific postnatal time points in cerebella of the offspring of exposed mice. Our results provide evidence of disrupted FMRP, glutamatergic, and Reelin signaling in the exposed mouse offspring that explains the multiple brain abnormalities observed in this animal model. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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

    Science.gov (United States)

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

    2016-11-01

    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 neuronal/glial glutamate transporters was determined by qPCR in postmortem prefrontal cortex. The anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC) were selected from young MDD patients who had committed suicide (MDD-S; n = 17), from MDD patients who died of non-suicide related causes (MDD-NS; n = 7) and from matched control subjects (n = 12). We also compared elderly depressed patients who had not committed suicide (n = 14) with matched control subjects (n = 22). We found that neuronal located components (EAAT3, EAAT4, ASCT1, SNAT1, SNAT2) of the glutamate-glutamine cycle were increased in the ACC while the astroglia located components (EAAT1, EAAT2, GLUL) were decreased in the DLPFC of MDD-S patients. In contrast, most of the components in the cycle were increased in the DLPFC of MDD-NS patients. In conclusion, the glutamate-glutamine cycle - and thus glutamine transmission - is differentially affected in depressed suicide patients and depressed non-suicide patients in an area specific way. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. 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

    , 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...

  19. Untangling the glutamate dehydrogenase allosteric nightmare.

    Science.gov (United States)

    Smith, Thomas J; Stanley, Charles A

    2008-11-01

    Glutamate dehydrogenase (GDH) is found in all living organisms, but only animal GDH is regulated by a large repertoire of metabolites. More than 50 years of research to better understand the mechanism and role of this allosteric network has been frustrated by its sheer complexity. However, recent studies have begun to tease out how and why this complex behavior evolved. Much of GDH regulation probably occurs by controlling a complex ballet of motion necessary for catalytic turnover and has evolved concomitantly with a long antenna-like feature of the structure of the enzyme. Ciliates, the 'missing link' in GDH evolution, might have created the antenna to accommodate changing organelle functions and was refined in humans to, at least in part, link amino acid catabolism with insulin secretion.

  20. NCBI nr-aa BLAST: CBRC-XTRO-01-1995 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-XTRO-01-1995 sp|O00222|MGR8_HUMAN Metabotropic glutamate receptor 8 precursor ...(mGluR8) gb|AAH93725.1| Glutamate receptor, metabotropic 8, precursor [Homo sapiens] gb|AAI01676.1| Glutamate receptor, metabotropic... 8 [Homo sapiens] gb|EAW83621.1| glutamate receptor, metabotropic 8, isoform CRA_a [Homo sapiens] O00222 0.0 82% ...

  1. NCBI nr-aa BLAST: CBRC-OGAR-01-0953 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-OGAR-01-0953 ref|NP_000829.1| glutamate receptor, metabotropic 1 [Homo sapiens...] sp|Q13255|MGR1_HUMAN Metabotropic glutamate receptor 1 precursor (mGluR1) gb|AAB05337.1| metabotropic glut...amate receptor 1 alpha gb|EAW47835.1| glutamate receptor, metabotropic 1, isoform CRA_b [Homo sapiens] NP_000829.1 0.0 92% ...

  2. NCBI nr-aa BLAST: CBRC-RMAC-03-0050 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-RMAC-03-0050 sp|O00222|MGR8_HUMAN Metabotropic glutamate receptor 8 precursor ...(mGluR8) gb|AAH93725.1| Glutamate receptor, metabotropic 8, precursor [Homo sapiens] gb|AAI01676.1| Glutamate receptor, metabotropic... 8 [Homo sapiens] gb|EAW83621.1| glutamate receptor, metabotropic 8, isoform CRA_a [Homo sapiens] O00222 0.0 99% ...

  3. Glutamate and GABA in appetite regulation

    Directory of Open Access Journals (Sweden)

    Teresa Cardoso Delgado

    2013-08-01

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

  4. Glutamate and GABA in Appetite Regulation.

    Science.gov (United States)

    Delgado, Teresa C

    2013-01-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  6. Glutamate input to noradrenergic neurons plays an essential role in the development of morphine dependence and psychomotor sensitization.

    Science.gov (United States)

    Parkitna, Jan Rodriguez; Solecki, Wojciech; Gołembiowska, Krystyna; Tokarski, Krzysztof; Kubik, Jakub; Gołda, Sławomir; Novak, Martin; Parlato, Rosanna; Hess, Grzegorz; Sprengel, Rolf; Przewłocki, Ryszard

    2012-11-01

    The brain's noradrenergic system is involved in the development of behaviours induced by drugs of abuse, e.g. dependence and withdrawal, and also reward or psychomotor effects. To investigate how noradrenergic system activity is controlled in the context associated with drug-induced behaviours, we generated a Cre/loxP mouse model in which the essential glutamate NMDA receptor subunit NR1 is ablated in cells expressing dopamine β-hydroxylase (Dbh). As a result, the noradrenergic cells in NR1DbhCre mice lack the NMDA receptor-dependent component of excitatory post-synaptic currents. The mutant mice displayed no obvious behavioural alterations, had unchanged noradrenaline content and mild increase in dopamine levels in the nucleus accumbens. Interestingly, NR1DbhCre animals did not develop morphine-induced psychomotor sensitization. However, when the morphine injections were preceded by treatment with RX821002, an antagonist of α2-adrenergic receptors, the development of sensitization was restored. Conversely, pretreatment with clonidine, an agonist of α2-adrenergic receptors, blocked development of sensitization in wild-type mice. We also found that while the development of tolerance to morphine was normal in mutant mice, withdrawal symptoms were attenuated. These data reveal that NMDA receptors on noradrenergic neurons regulate development of opiate dependence and psychomotor sensitization, by controlling drug-induced noradrenaline signalling.

  7. Glutamine-Glutamate Cycle Flux Is Similar in Cultured Astrocytes and Brain and Both Glutamate Production and Oxidation Are Mainly Catalyzed by Aspartate Aminotransferase

    Directory of Open Access Journals (Sweden)

    Leif Hertz

    2017-02-01

    Full Text Available The glutamine-glutamate cycle provides neurons with astrocyte-generated glutamate/γ-aminobutyric acid (GABA and oxidizes glutamate in astrocytes, and it returns released transmitter glutamate/GABA to neurons after astrocytic uptake. This review deals primarily with the glutamate/GABA generation/oxidation, although it also shows similarity between metabolic rates in cultured astrocytes and intact brain. A key point is identification of the enzyme(s converting astrocytic α-ketoglutarate to glutamate and vice versa. Most experiments in cultured astrocytes, including those by one of us, suggest that glutamate formation is catalyzed by aspartate aminotransferase (AAT and its degradation by glutamate dehydrogenase (GDH. Strongly supported by results shown in Table 1 we now propose that both reactions are primarily catalyzed by AAT. This is possible because the formation occurs in the cytosol and the degradation in mitochondria and they are temporally separate. High glutamate/glutamine concentrations abolish the need for glutamate production from α-ketoglutarate and due to metabolic coupling between glutamate synthesis and oxidation these high concentrations render AAT-mediated glutamate oxidation impossible. This necessitates the use of GDH under these conditions, shown by insensitivity of the oxidation to the transamination inhibitor aminooxyacetic acid (AOAA. Experiments using lower glutamate/glutamine concentration show inhibition of glutamate oxidation by AOAA, consistent with the coupled transamination reactions described here.

  8. Role of aminotransferases in glutamate metabolism of human erythrocytes

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-15

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2017-02-03

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

  11. Hook-up of GluA2, GRIP and liprin-α for cholinergic muscarinic receptor-dependent LTD in the hippocampus

    Directory of Open Access Journals (Sweden)

    Wu Long-Jun

    2009-06-01

    Full Text Available Abstract The molecular mechanism underlying muscarinic acetylcholine receptor-dependent LTD (mAChR-LTD in the hippocampus is less studied. In a recent study, a novel mechanism is described. The induction of mAChR-LTD required the activation of protein tyrosine phosphatase (PTP, and the expression was mediated by AMPA receptor endocytosis via interactions between GluA2, GRIP and liprin-α. The hook-up of these proteins may result in the recruitment of leukocyte common antigen-related receptor (LAR, a PTP that is known to be involved in AMPA receptor trafficking. Interestingly, the similar molecular interaction cannot be applied to mGluR-LTD, despite the fact that the same G-protein involved in LTD is activated by both mAChR and mGluR. This discovery provides key molecular insights for cholinergic dependent cognitive function, and mAChR-LTD can serve as a useful cellular model for studying the roles of cholinergic mechanism in learning and memory.

  12. EGF Receptor-Dependent Mechanism May be Involved in the Tamm–Horsfall Glycoprotein-Enhanced PMN Phagocytosis via Activating Rho Family and MAPK Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Ko-Jen Li

    2014-01-01

    Full Text Available Our previous studies showed that urinary Tamm–Horsfall glycoprotein (THP potently enhanced polymorphonuclear neutrophil (PMN phagocytosis. However, the domain structure(s, signaling pathway and the intracellular events responsible for THP-enhanced PMN phagocytosis remain to be elucidated. THP was purified from normal human urine. The human promyelocytic leukemia cell line HL-60 was induced to differentiate into PMNs by all-trans retinoid acid. Pretreatment with different MAPK and PI3K inhibitors was used to delineate signaling pathways in THP-enhanced PMN phagocytosis. Phosphorylation of molecules responsible for PMN phagocytosis induced by bacterial lipopolysaccharide (LPS, THP, or human recombinant epidermal growth factor (EGF was evaluated by western blot. A p38 MAPK inhibitor, SB203580, effectively inhibited both spontaneous and LPS- and THP-induced PMN phagocytosis. Both THP and LPS enhanced the expression of the Rho family proteins Cdc42 and Rac that may lead to F-actin re-arrangement. Further studies suggested that THP and EGF enhance PMN and differentiated HL-60 cell phagocytosis in a similar pattern. Furthermore, the EGF receptor inhibitor GW2974 significantly suppressed THP- and EGF-enhanced PMN phagocytosis and p38 and ERK1/2 phosphorylation in differentiated HL-60 cells. We conclude that EGF receptor-dependent signaling may be involved in THP-enhanced PMN phagocytosis by activating Rho family and MAP kinase.

  13. Endothelin-1 induces proliferation of human lung fibroblasts and IL-11 secretion through an ET(A) receptor-dependent activation of MAP kinases.

    Science.gov (United States)

    Gallelli, Luca; Pelaia, Girolamo; D'Agostino, Bruno; Cuda, Giovanni; Vatrella, Alessandro; Fratto, Donatella; Gioffrè, Vincenza; Galderisi, Umberto; De Nardo, Marilisa; Mastruzzo, Claudio; Salinaro, Elisa Trovato; Maniscalco, Mauro; Sofia, Matteo; Crimi, Nunzio; Rossi, Francesco; Caputi, Mario; Costanzo, Francesco S; Maselli, Rosario; Marsico, Serafino A; Vancheri, Carlo

    2005-11-01

    Endothelin-1 (ET-1) is implicated in the fibrotic responses characterizing interstitial lung diseases, as well as in the airway remodeling process occurring in asthma. Within such a context, the aim of our study was to investigate, in primary cultures of normal human lung fibroblasts (NHLFs), the ET-1 receptor subtypes, and the intracellular signal transduction pathways involved in the proliferative effects of this peptide. Therefore, cells were exposed to ET-1 in the presence or absence of an overnight pre-treatment with either ET(A) or ET(B) selective receptor antagonists. After cell lysis, immunoblotting was performed using monoclonal antibodies against the phosphorylated, active forms of mitogen-activated protein kinases (MAPK). ET-1 induced a significant increase in MAPK phosphorylation pattern, and also stimulated fibroblast proliferation and IL-6/IL-11 release into cell culture supernatants. All these effects were inhibited by the selective ET(A) antagonist BQ-123, but not by the specific ET(B) antagonist BQ-788. The stimulatory influence of ET-1 on IL-11, but not on IL-6 secretion, was prevented by MAPK inhibitors. Therefore, such results suggest that in human lung fibroblasts ET-1 exerts a profibrogenic action via an ET(A) receptor-dependent, MAPK-mediated induction of IL-11 release and cell proliferation.

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

    Directory of Open Access Journals (Sweden)

    Tina T.-C. Tseng

    2014-06-01

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

  15. GDH3 encodes a glutamate dehydrogenase isozyme, a previously unrecognized route for glutamate biosynthesis in Saccharomyces cerevisiae.

    Science.gov (United States)

    Avendaño, A; Deluna, A; Olivera, H; Valenzuela, L; Gonzalez, A

    1997-09-01

    It has been considered that the yeast Saccharomyces cerevisiae, like many other microorganisms, synthesizes glutamate through the action of NADP+-glutamate dehydrogenase (NADP+-GDH), encoded by GDH1, or through the combined action of glutamine synthetase and glutamate synthase (GOGAT), encoded by GLN1 and GLT1, respectively. A double mutant of S. cerevisiae lacking NADP+-GDH and GOGAT activities was constructed. This strain was able to grow on ammonium as the sole nitrogen source and thus to synthesize glutamate through an alternative pathway. A computer search for similarities between the GDH1 nucleotide sequence and the complete yeast genome was carried out. In addition to identifying its cognate sequence at chromosome XIV, the search found that GDH1 showed high identity with a previously recognized open reading frame (GDH3) of chromosome I. Triple mutants impaired in GDH1, GLT1, and GDH3 were obtained. These were strict glutamate auxotrophs. Our results indicate that GDH3 plays a significant physiological role, providing glutamate when GDH1 and GLT1 are impaired. This is the first example of a microorganism possessing three pathways for glutamate biosynthesis.

  16. 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

  17. Neuroprotective Effects of Glutamate Antagonists and Extracellular Acidity

    Science.gov (United States)

    Kaku, David A.; Giffard, Rona G.; Choi, Dennis W.

    1993-06-01

    Glutamate antagonists protect neurons from hypoxic injury both in vivo and in vitro, but in vitro studies have not been done under the acidic conditions typical of hypoxia-ischemia in vivo. Consistent with glutamate receptor antagonism, extracellular acidity reduced neuronal death in murine cortical cultures that were deprived of oxygen and glucose. Under these acid conditions, N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isox-azolepropionate-kainate antagonists further reduced neuronal death, such that some neurons tolerated prolonged oxygen and glucose deprivation almost as well as did astrocytes. Neuroprotection induced by this combination exceeded that induced by glutamate antagonists alone, suggesting that extracellular acidity has beneficial effects beyond the attenuation of ionotropic glutamate receptor activation.

  18. GLUTAMATE DEHYDROGENASE 1 AND SIRT4 REGULATE GLIAL DEVELOPMENT

    OpenAIRE

    Komlos, Daniel; Mann, Kara D.; Zhuo, Yue; Ricupero, Christopher L.; Hart, Ronald P.; Liu, Alice Y.-C.; Firestein, Bonnie L.

    2012-01-01

    Congenital hyperinsulinism/hyperammonemia (HI/HA) syndrome is caused by an activation mutation of glutamate dehydrogenase 1 (GDH1), a mitochondrial enzyme responsible for the reversible interconversion between glutamate and α-ketoglutarate. The syndrome presents clinically with hyperammonemia, significant episodic hypoglycemia, seizures, and a frequent incidences of developmental and learning defects. Clinical research has implicated that although some of the developmental and neurological de...

  19. Glutamic Acid Selective Chemical Cleavage of Peptide Bonds.

    Science.gov (United States)

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

    2016-03-04

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

  20. [Glutamic acid as a universal extracellular signal].

    Science.gov (United States)

    Yoneda, Yukio

    2015-08-01

    The prevailing view is that both glutamic (Glu) and gamma-aminobutyric (GABA) acids play a role as an amino acid neurotransmitter released from neurons. However, little attention has been paid to the possible expression and functionality of signaling machineries required for amino acidergic neurotransmission in cells other than central neurons. In line with our first demonstration of the presence of Glu receptors outside the brain, in this review I will outline our recent findings accumulated since then on the physiological and pathological significance of neuronal amino acids as an extracellular signal essential for homeostasis in a variety of phenotypic cells. In undifferentiated neural progenitor cells, for instance, functional expression is seen with different signaling machineries used for glutamatergic and GABAergic neurotransmission in neurons. Moreover, Glu plays a role in mechanisms underlying suppression of proliferation for self-replication in undifferentiated mesenchymal stem cells. There is more accumulating evidence for neuronal amino acids playing a role as an extracellular autocrine or paracrine signal commonly used in different phenotypic cells. Evaluation of drugs currently used could be thus beneficial for the efficient prophylaxis and/or the therapy of a variety of diseases relevant to disturbance of amino acid signaling in diverse organs.

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

    Science.gov (United States)

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

    2010-12-01

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

  2. Ethanol withdrawal is required to produce persisting N-methyl-D-aspartate receptor-dependent hippocampal cytotoxicity during chronic intermittent ethanol exposure

    Science.gov (United States)

    Reynolds, Anna R.; Berry, B. Jennifer N.; Sharrett-Field, Lynda; Prendergast, Mark A.

    2015-01-01

    Chronic intermittent ethanol consumption is associated with neurodegeneration and cognitive deficits in preclinical laboratory animals and in the clinical population. While previous work suggests a role for neuroadaptations in the N-methyl-D-aspartate (NMDA) receptor in the development of ethanol dependence and manifestation of withdrawal, the relative roles of ethanol exposure and ethanol withdrawal in producing these effects have not been fully characterized. To examine underlying cytotoxic mechanisms associated with CIE exposure, organotypic hippocampal slices were exposed to 1–3 cycles of ethanol (50 mM) in cell culture medium for 5 days, followed by 24-hours of ethanol withdrawal in which a portion of slices were exposed to competitive NMDA receptor antagonist (2R)-amino-5-phosphonovaleric acid (APV; 40 µM). Cytotoxicity was assessed using immunohistochemical labeling of neuron specific nuclear protein (NeuN; Fox-3), a marker of mature neurons, and thionine (2%) staining of Nissl bodies. Multiple cycles of CIE produced neurotoxicity, as reflected in persisting losses of neuron NeuN immunoreactivity and thionine staining in each of the primary cell layers of the hippocampal formation. Hippocampi aged in vitro were significantly more sensitive to the toxic effects of multiple CIEs than were non-aged hippocampi. This effect was not demonstrated in slices exposed to continuous ethanol, in the absence of withdrawal, or to a single exposure/withdrawal regimen. Exposure to APV significantly attenuated the cytotoxicity observed in the primary cell layers of the hippocampus. The present findings suggest that ethanol withdrawal is required to produce NMDA receptor-dependent hippocampal cytotoxicity, particularly in the aging hippocampus in vitro. PMID:25746220

  3. Control of βAR- and N-methyl-D-aspartate (NMDA) Receptor-Dependent cAMP Dynamics in Hippocampal Neurons.

    Science.gov (United States)

    Chay, Andrew; Zamparo, Ilaria; Koschinski, Andreas; Zaccolo, Manuela; Blackwell, Kim T

    2016-02-01

    Norepinephrine, a neuromodulator that activates β-adrenergic receptors (βARs), facilitates learning and memory as well as the induction of synaptic plasticity in the hippocampus. Several forms of long-term potentiation (LTP) at the Schaffer collateral CA1 synapse require stimulation of both βARs and N-methyl-D-aspartate receptors (NMDARs). To understand the mechanisms mediating the interactions between βAR and NMDAR signaling pathways, we combined FRET imaging of cAMP in hippocampal neuron cultures with spatial mechanistic modeling of signaling pathways in the CA1 pyramidal neuron. Previous work implied that cAMP is synergistically produced in the presence of the βAR agonist isoproterenol and intracellular calcium. In contrast, we show that when application of isoproterenol precedes application of NMDA by several minutes, as is typical of βAR-facilitated LTP experiments, the average amplitude of the cAMP response to NMDA is attenuated compared with the response to NMDA alone. Models simulations suggest that, although the negative feedback loop formed by cAMP, cAMP-dependent protein kinase (PKA), and type 4 phosphodiesterase may be involved in attenuating the cAMP response to NMDA, it is insufficient to explain the range of experimental observations. Instead, attenuation of the cAMP response requires mechanisms upstream of adenylyl cyclase. Our model demonstrates that Gs-to-Gi switching due to PKA phosphorylation of βARs as well as Gi inhibition of type 1 adenylyl cyclase may underlie the experimental observations. This suggests that signaling by β-adrenergic receptors depends on temporal pattern of stimulation, and that switching may represent a novel mechanism for recruiting kinases involved in synaptic plasticity and memory.

  4. Control of βAR- and N-methyl-D-aspartate (NMDA Receptor-Dependent cAMP Dynamics in Hippocampal Neurons.

    Directory of Open Access Journals (Sweden)

    Andrew Chay

    2016-02-01

    Full Text Available Norepinephrine, a neuromodulator that activates β-adrenergic receptors (βARs, facilitates learning and memory as well as the induction of synaptic plasticity in the hippocampus. Several forms of long-term potentiation (LTP at the Schaffer collateral CA1 synapse require stimulation of both βARs and N-methyl-D-aspartate receptors (NMDARs. To understand the mechanisms mediating the interactions between βAR and NMDAR signaling pathways, we combined FRET imaging of cAMP in hippocampal neuron cultures with spatial mechanistic modeling of signaling pathways in the CA1 pyramidal neuron. Previous work implied that cAMP is synergistically produced in the presence of the βAR agonist isoproterenol and intracellular calcium. In contrast, we show that when application of isoproterenol precedes application of NMDA by several minutes, as is typical of βAR-facilitated LTP experiments, the average amplitude of the cAMP response to NMDA is attenuated compared with the response to NMDA alone. Models simulations suggest that, although the negative feedback loop formed by cAMP, cAMP-dependent protein kinase (PKA, and type 4 phosphodiesterase may be involved in attenuating the cAMP response to NMDA, it is insufficient to explain the range of experimental observations. Instead, attenuation of the cAMP response requires mechanisms upstream of adenylyl cyclase. Our model demonstrates that Gs-to-Gi switching due to PKA phosphorylation of βARs as well as Gi inhibition of type 1 adenylyl cyclase may underlie the experimental observations. This suggests that signaling by β-adrenergic receptors depends on temporal pattern of stimulation, and that switching may represent a novel mechanism for recruiting kinases involved in synaptic plasticity and memory.

  5. Latent inhibition of cued fear conditioning: an NMDA receptor-dependent process that can be established in the presence of anisomycin.

    Science.gov (United States)

    Lewis, Michael C; Gould, Thomas J

    2004-08-01

    Much of the research examining the biological basis for long-term memories has focused on mechanisms that support the formation of conditioned associations. Less information is available on biological mechanisms which underlie processes that modify the strength of conditioned associations. Latent inhibition is a phenomenon by which pre-exposure to a to-be-conditioned stimulus (CS) weakens subsequent conditioning of that CS to an unconditioned stimulus (US). Here we report that latent inhibition of cued fear conditioning is dependent on NMDA receptor activation. MK-801 (1 mg/kg), an NMDA receptor antagonist, abolished latent inhibition of cued fear conditioning. This dose of MK-801 administered before training did not disrupt cued fear conditioning. Conversely, anisomycin (150 mg/kg), a protein synthesis inhibitor, had no effect on latent inhibition of cued fear conditioning when administered 20 min before, immediately after, or 2, 4, 6, or 8 h after CS pre-exposure. Furthermore, continuous anisomycin administration (50 mg/kg, administered every 2 h for 6 h starting 20 min prior to pre-exposure) did not disrupt latent inhibition of cued fear conditioning. In addition, anisomycin had no effect on a long-lasting version of latent inhibition of cued fear conditioning that was maintained over a 7-day interval. Anisomycin administered before training, however, disrupted learning of the CS-US association. These findings suggest that latent inhibition of cued fear conditioning is a long-lasting NMDA receptor-dependent process that can develop during the inhibition of protein synthesis.

  6. Apolipoprotein E competitively inhibits receptor-dependent low density lipoprotein uptake by the liver but has no effect on cholesterol absorption or synthesis in the mouse.

    Science.gov (United States)

    Woollett, L A; Osono, Y; Herz, J; Dietschy, J M

    1995-01-01

    This study examines the question of whether apolipoprotein E (apoE) alters steady-state concentrations of plasma cholesterol carried in low density lipoproteins (LDL-C) by acting as a competitive inhibitor of hepatic LDL uptake or by altering the rate of net cholesterol delivery from the intestinal lumen to the liver. To differentiate between these two possibilities, rates of cholesterol absorption and synthesis and the kinetics of hepatic LDL-C transport were measured in vivo in mice with either normal (apoE+/+) or zero (apoE-/-) levels of circulating apoE. Rates of cholesterol absorption were essentially identical in both genotypes and equaled approximately 44% of the daily dietary load of cholesterol. This finding was consistent with the further observation that the rates of cholesterol synthesis in the liver (approximately 2,000 nmol/h) and extrahepatic tissues (approximately 3,000 nmol/h) were also essentially identical in the two groups of mice. However, the apparent Michaelis constant for receptor-dependent hepatic LDL-C uptake was markedly lower in the apoE-/- mice (44 +/- 4 mg/dl) than in the apoE+/+ animals (329 +/- 77 mg/dl) even though the maximal transport velocity for this uptake process was essentially the same (approximately 400 micrograms/h per g) in the two groups of mice. These studies, therefore, demonstrate that apoE-containing lipoproteins can act as potent competitive inhibitors of hepatic LDL-C transport and so can significantly increase steady-state plasma LDL-C levels. This apolipoprotein plays no role, however, in the regulation of cholesterol absorption, sterol biosynthesis, or hepatic LDL receptor number, at least in the mouse. PMID:8618929

  7. Pharmacological and structural characterization of conformationally restricted (S)-glutamate analogues at ionotropic glutamate receptors

    DEFF Research Database (Denmark)

    Juknaite, Lina; Venskutonyte, Raminta; Assaf, Zeinab

    2012-01-01

    A2 and the kainate receptor GluK3. These structures show that CBG-IV interacts with the binding pocket in the same way as (S)-glutamate. The binding affinities reveal that CBG-IV has high affinity at the AMPA and kainate receptor subtypes. Appreciable binding affinity of CBG-IV was not observed......Conformationally restricted glutamate analogues have been pharmacologically characterized at AMPA and kainate receptors and the crystal structures have been solved of the ligand (2S,1'R,2'S)-2-(2'-carboxycyclobutyl)glycine (CBG-IV) in complex with the ligand binding domains of the AMPA receptor Glu...... at NMDA receptors, where the introduction of the carbocyclic ring is expected to lead to a steric clash with binding site residues. CBG-IV was demonstrated to be an agonist at both GluA2 and the kainate receptor GluK1. CBG-IV showed high affinity binding to GluK1 compared to GluA2, GluK2 and GluK3, which...

  8. A NADP-glutamate dehydrogenase mutant of the petit-negative yeast Kluyveromyces lactis uses the glutamine synthetase-glutamate synthase pathway for glutamate biosynthesis.

    Science.gov (United States)

    Valenzuela, L; Guzmán-León, S; Coria, R; Ramírez, J; Aranda, C; González, A

    1995-10-01

    The activities of the enzymes involved in ammonium assimilation and glutamate biosynthesis were determined in wild-type and NADP-glutamate dehydrogenase (GDH) null mutant strains of Kluyveromyces lactis. The specific NADP-GDH activity from K. lactis was fivefold lower than that found in Saccharomyces cerevisiae. The glutamine synthetase (GS) and glutamate synthase (GOGAT) activities were similar to those reported in S. cerevisiae. The NADP-GDH null mutant was obtained by transforming the uraA strain MD2/1 with a linearized integrative yeast vector harbouring a 390 bp fragment of the NADP-GDH structural gene. This mutant grew as well as the parent strain on ammonium, but showed GS and GOGAT activities higher that those found in the wild-type strain, implying that the GS-GOGAT pathway could play a leading role in glutamate biosynthesis in K. lactis. Southern blotting analysis of K. lactis chromosomes separated by contour-clamped homogeneous electric field electrophoresis, indicated that the NADP-GDH structural gene is localized on chromosome VI.

  9. Single rodent mesohabenular axons release glutamate and GABA

    Science.gov (United States)

    Root, David H.; Mejias-Aponte, Carlos; Zhang, Shiliang; Wang, Huiling; Hoffman, Alexander F.; Lupica, Carl R.; Morales, Marisela

    2016-01-01

    The lateral habenula (LHb) is involved in reward, aversion, addiction, and depression, through descending interactions with several brain structures, including the ventral tegmental area (VTA). VTA provides reciprocal inputs to LHb, but their actions are unclear. Here we show that the majority of rat and mouse VTA neurons innervating LHb co-express markers for both glutamate-signaling (vesicular glutamate transporter 2, VGluT2) and GABA-signaling (glutamate decarboxylase, GAD; and vesicular GABA transporter, VGaT). A single axon from these mesohabenular neurons co-expresses VGluT2-protein and VGaT-protein, and surprisingly establishes symmetric and asymmetric synapses on LHb neurons. In LHb slices, light activation of mesohabenular fibers expressing channelrhodopsin-2 (ChR2) driven by VGluT2 or VGaT promoters elicits release of both glutamate and GABA onto single LHb neurons. In vivo light-activation of mesohabenular terminals inhibits or excites LHb neurons. Our findings reveal an unanticipated type of VTA neuron that co-transmits glutamate and GABA, and provides the majority of mesohabenular inputs. PMID:25242304

  10. Methylphenidate Increases Glutamate Uptake in Bergmann Glial Cells.

    Science.gov (United States)

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

    2015-11-01

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

  11. Distribution of vesicular glutamate transporters in the human brain

    Directory of Open Access Journals (Sweden)

    Erika eVigneault

    2015-03-01

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

  12. Monosodium glutamate induced histomorphometric changes in thyroid gland of adult

    Directory of Open Access Journals (Sweden)

    Pooja Rani1, Kamlesh Khatri2, Renu Chauhan1

    2013-08-01

    Full Text Available Monosodium Glutamate (MSG is widely used as a flavor enhanc-er throughout the world. MSG contains glutamic acid, sodium and water. Glutamic acid serves as a neurotransmitter vital to the transmission of nerve impulses in many parts of the central nerv-ous system, and in excess it may cause neurotoxicity leading to endocrinal disorders. The present study was conducted to eva-luate histomorphometrically the effects of monosodium glutamate on the thyroid gland of adult albino rats. The experimental group was given 4mg/g body weight of monosodium glutamate intra-peritoneally for seven days. Controls were maintained. After thirty days of the last dose, all the animals were sacrificed, their thyroid glands were dissected out, processed and sections stained with haematoxylin and eosin (H&E and Periodic Acid Schiff (PAS and examined for histomorphometry under Zeiss light microscope and Image Pro-Express Analyzer. The results of the present study showed a significant increase in the body weight of the MSG treated animals, although these animals consumed less food than the controls. A significant increase in the size of the follicles ac-companied by an increase in the mean height and area of the folli-cular cells and decreased colloid in some of the follicles was ob-served, pointing towards an increase in thyroid gland activity.

  13. Existence of an Endogenous Glutamate and Aspartate Transporter in Chinese Hamster Ovary Cells

    Institute of Scientific and Technical Information of China (English)

    Xunhe JI; Yuhua JIN; Yaoyue CHEN; Chongyong LI; Lihe GUO

    2007-01-01

    Chinese hamster ovary cells show endogenous high-affinity Na+-dependent glutamate transport activity. This transport activity is kinetically similar to a glutamate transporter family strategically expressed in the central nervous system and is pharmacologically unlike glutamate transporter-1 or excitatory amino acid carrier 1. The cDNA of a glutamate/aspartate transporter (GLAST)-like transporter was obtained and analyzed. The deduced amino acid sequence showed high similarity to human, mouse, and rat GLAST. We concluded that a GLAST-like glutamate transporter exists in Chinese hamster ovary cells that might confer the endogenous high-affinity Na+-dependent glutamate transport activity evident in these cells.

  14. A conserved aspartic acid is important for agonist (VUAA1 and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco.

    Directory of Open Access Journals (Sweden)

    Brijesh N Kumar

    Full Text Available Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco. An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.

  15. A Conserved Aspartic Acid Is Important for Agonist (VUAA1) and Odorant/Tuning Receptor-Dependent Activation of the Insect Odorant Co-Receptor (Orco)

    Science.gov (United States)

    Kumar, Brijesh N.; Taylor, Robert W.; Pask, Gregory M.; Zwiebel, Laurence J.; Newcomb, Richard D.; Christie, David L.

    2013-01-01

    Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco). An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ∼2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels. PMID:23894621

  16. A noncanonical release of GABA and glutamate modulates neuronal migration.

    Science.gov (United States)

    Manent, Jean-Bernard; Demarque, Michaël; Jorquera, Isabel; Pellegrino, Christophe; Ben-Ari, Yehezkel; Aniksztejn, Laurent; Represa, Alfonso

    2005-05-11

    Immature neurons express GABA and glutamate receptors before synapse formation, and both transmitters are released at an early developmental stage. We have now tested the hypothesis that the ongoing release of GABA and glutamate modulates neuronal migration. Using 5-bromo-2'-deoxyuridine labeling and cocultures of hippocampal slices obtained from naive and green fluorescent protein-transgenic mice, we report that migration is severely affected by GABA(A) or NMDA receptor antagonist treatments. These effects were also present in munc18-1 knock-out slices in which soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent vesicular secretion of transmitters has been deleted. GABA(A) antagonists were more efficient than NMDA antagonists to reduce cell migration, in keeping with the earlier maturation of GABAergic mechanisms. We conclude that GABA and, to a lesser degree, glutamate released in a SNARE-independent mechanism exert a paracrine action on neuronal migration.

  17. [PECULIARITIES OF THE CEREBROVASCULAR EFFECTS OF GLUTAMIC ACID].

    Science.gov (United States)

    Gan'shina, T S; Kurza, E V; Kurdyumov, I N; Maslennikov, D V; Mirzoyan, R S

    2016-01-01

    Experiments on nonlinear rats subjected to global transient cerebral ischemia revealed the ability of glutamic acid to improve cerebral circulation. Consequently, the excitatory amino acid can produce adverse (neurotoxic) and positive (anti-ischemic) effects in cerebral ischemia. The cerebrovascular effect of glutamic acid in cerebral ischemia is attenuated on the background action of the MNDA receptor blocker MK-801 (0.5 mg/kg intravenously) and eliminated by bicuculline. When glutamic acid is combined with the non-competitive MNDA receptor antagonist MK-801, neither one nor another drug shows its vasodilator effect. The results are indicative of the interaction between excitatory and inhibitory systems on the level of cerebral vessels and once again confirm our previous conclusion about the decisive role of GABA(A) receptors in brain vessels in the implementation of anti-ischemic activity of endogenous compounds (melatonin) and well-known pharmacological substances (mexidol, afobazole), and new chemical compounds based on GABA-containing lipid derivatives.

  18. Ubiquitin-dependent trafficking and turnover of ionotropic glutamate receptors

    Directory of Open Access Journals (Sweden)

    Marisa S Goo

    2015-10-01

    Full Text Available Changes in synaptic strength underlie the basis of learning and memory and are controlled, in part, by the insertion or removal of AMPA-type glutamate receptors at the postsynaptic membrane of excitatory synapses. Once internalized, these receptors may be recycled back to the plasma membrane by subunit-specific interactions with other proteins or by post-translational modifications such as phosphorylation. Alternatively, these receptors may be targeted for destruction by multiple degradation pathways in the cell. Ubiquitination, another post-translational modification, has recently emerged as a key signal that regulates the recycling and trafficking of glutamate receptors. In this review, we will discuss recent findings on the role of ubiquitination in the trafficking and turnover of ionotropic glutamate receptors and plasticity of excitatory synapses.

  19. Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci.

    Science.gov (United States)

    Peralta, Guillermo Hugo; Bergamini, Carina Viviana; Hynes, Erica Rut

    2016-01-01

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

  20. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  2. Brain glutamate metabolism during metabolic alkalosis and acidosis.

    Science.gov (United States)

    Ang, R C; Hoop, B; Kazemi, H

    1992-12-01

    Glutamate modifies ventilation by altering neural excitability centrally. Metabolic acid-base perturbations may also alter cerebral glutamate metabolism locally and thus affect ventilation. Therefore, the effect of metabolic acid-base perturbations on central nervous system glutamate metabolism was studied in pentobarbital-anesthetized dogs under normal acid-base conditions and during isocapnic metabolic alkalosis and acidosis. Cerebrospinal fluid transfer rates of radiotracer [13N]ammonia and of [13N]glutamine synthesized de novo via the reaction glutamate+NH3-->glutamine in brain glia were measured during normal acid-base conditions and after 90 min of acute isocapnic metabolic alkalosis and acidosis. Cerebrospinal fluid [13N]ammonia and [13N]glutamine transfer rates decreased in metabolic acidosis. Maximal glial glutamine efflux rate jm equals 85.6 +/- 9.5 (SE) mumol.l-1 x min-1 in all animals. No difference in jm was observed in metabolic alkalosis or acidosis. Mean cerebral cortical glutamate concentration was significantly lower in acidosis [7.01 +/- 0.45 (SE) mumol/g brain tissue] and tended to be larger in alkalosis, compared with 7.97 +/- 0.89 mumol/g in normal acid-base conditions. There was a similar change in cerebral cortical gamma-aminobutyric acid concentration. Within the limits of the present method and measurements, the results suggest that acute metabolic acidosis but not alkalosis reduces glial glutamine efflux, corresponding to changes in cerebral cortical glutamate metabolism. These results suggest that glutamatergic mechanisms may contribute to central respiratory control in metabolic acidosis.

  3. Glutamate-based magnetic resonance spectroscopy in neuroleptic malignant syndrome

    Directory of Open Access Journals (Sweden)

    Atri Chatterjee

    2014-01-01

    Full Text Available Glutamate neurotoxicity is implicated in a number of neurological diseases, including Neuroleptic Malignant syndrome. Therefore, functional magnetic resonance imaging can help in diagnosis and monitoring such conditions. However, reports of this application are scarce in the literature. In this manuscript, glutamate based imaging of the basal ganglia showed increased levels of the neurotransmitter bilaterally. In addition, a radon transform of the functional image was performed to look for any asymmetry in cerebral activation. Although no asymmetry was detected in this case, this novel analysis can be applied in physiological and pathological scenarios to visualize contribution of different brain structures.

  4. Complexity analysis of the glutamic acid ion-exchanged wastewater

    Institute of Scientific and Technical Information of China (English)

    林艳; 王瑞明; 徐国华; 王腾飞; 井瑞洁

    2008-01-01

    In this paper,the glutamic acid ion-exchanged wastewater has been studied.Kjeldahl determination method,Fehling reagent.muffle furnace method.and so on were used.It can be sure that the wastewater's COD is 50250 mg/L.and total solids is 13.76%.it contains:glutamic acid 0.3%:total reducing sugar 0.414%;fat 0.4274%;ammonium sulphate 10.0758%;microbial protein 0.8045%;ash 0.27%:others 1.4683%.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    A central task of the tricarboxylic acid (TCA, Krebs, citric acid) cycle in brain is to provide precursors for biosynthesis of glutamate, GABA, aspartate and glutamine. Three of these amino acids are the partners in the intricate interaction between astrocytes and neurons and form the so......-called glutamine-glutamate (GABA) cycle. The ketoacids α-ketoglutarate and oxaloacetate are removed from the cycle for this process. When something is removed from the TCA cycle it must be replaced to permit the continued function of this essential pathway, a process termed anaplerosis. This anaplerotic process...

  6. 代谢型谷氨酸受体5在吗啡耐受大鼠脊髓中的表达%Expression of metabotropic glutamate receptor 5 in spinal cord of morphine tolerant rats

    Institute of Scientific and Technical Information of China (English)

    刘金变; 江伟; 王爱忠

    2009-01-01

    目的 研究吗啡耐受大鼠脊髓代谢型谷氨酸受体5(mGluR5)的表达变化及mGluR5拮抗剂MPEP对其表达的影响.方法 雄性SD大鼠随机分为4组:对照组(NS),吗啡耐受组(Mor),吗啡加MPEP组(Mor+MPEP)和MPEP组.采用鞘内重复给药方式建立慢性吗啡耐受模型,鞘内注射吗啡10 μg,每日给药2次,连续7 d.通过甩尾实验,观察给药前和给药后30 min大鼠甩尾潜伏期并计算最大镇痛效应百分比[MPE%=(给药后阈值-基础阈值)/(最大阈值-基础阈值)×100%].采用免疫荧光和免疫印迹(Western blot)方法检测并比较各组L4~5脊髓组织mGluR5的表达.结果 鞘内重复注射吗啡后,吗啡组MPE%逐渐下降,到第7天与NS组比较,差异无统计学意义(P>0.05),吗啡加MPEP组第7天仍表现出较强的镇痛效应(P 0. 05). Morphine plus MPEP group had significant analgesic effect as compared with morphine group at Day 7 (P < 0. 05). The expression of mGluR5 was up-regulated in the dorsal horn of spinal cord in morphine tolerant rats. The protein level of mGluR5 in morphine plus MPEP group was lower than that in morphine group (P < 0. 05), but higher than control group (P < 0. 05). Conclusion The mGluR5 antagonist MPEP can prevent the development of morphine tolerance. The expression of mGluR5 protein increases in the spinal cord of morphine tolerant rats. MPEP plays its role in morphine tolerance by partly inhibiting the expression of mGluR5.

  7. Group 1 metabotropic glutamate receptors are involved in the activation of peripheral nociceptors%第一组代谢型谷氨酸受体在外周痛信号产生中的作用

    Institute of Scientific and Technical Information of China (English)

    王桢; 张宇; 张志华; 乔健天; 张策

    2003-01-01

    @@ 谷氨酸是脑内最重要的兴奋性递质,除参与快速的兴奋性突触传递外,还与突触前递质释放、突触传递的长时程增强和长时程抑制、学习和记忆过程、突触发育的可塑性等正常生理功能密切相关.谷氨酸过量时还具有神经毒作用,可导致神经元死亡.

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

    Science.gov (United States)

    Niu, Panqing; Zhang, Zhenyu; Liu, Liming

    2014-08-01

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

  9. Induction of glutamate dehydrogenase in the ovine fetal liver by dexamethasone infusion during late gestation

    NARCIS (Netherlands)

    M. Timmerman (Michelle); R.B. Wilkening; T.R. Regnault

    2003-01-01

    textabstractGlucocorticoids near term are known to upregulate many important enzyme systems prior to birth. Glutamate dehydrogenase (GDH) is a mitochondrial enzyme that catalyzes both the reversible conversion of ammonium nitrogen into organic nitrogen (glutamate production) and th

  10. Induction of glutamate dehydrogenase in the ovine fetal liver by dexamethasone infusion during late gestation

    NARCIS (Netherlands)

    M. Timmerman (Michelle); R.B. Wilkening; T.R. Regnault

    2003-01-01

    textabstractGlucocorticoids near term are known to upregulate many important enzyme systems prior to birth. Glutamate dehydrogenase (GDH) is a mitochondrial enzyme that catalyzes both the reversible conversion of ammonium nitrogen into organic nitrogen (glutamate production) and th

  11. Glutamate receptor ligands attenuate allodynia and hyperalgesia and potentiate morphine effects in a mouse model of neuropathic pain.

    Science.gov (United States)

    Osikowicz, Maria; Mika, Joanna; Makuch, Wioletta; Przewlocka, Barbara

    2008-09-30

    Recent studies have indicated that metabotropic glutamate receptors mGluR5, mGluR2/3 and mGluR7 are present in the regions of central nervous system important for nociceptive transmission, but their involvement in neuropathic pain has not been well established. We demonstrated that acute and chronic administration of MPEP (mGluR5 antagonist), LY379268 (mGluR2/3 agonist), and AMN082 (mGluR7 agonist) attenuated allodynia (von Frey test) and hyperalgesia (cold plate test) as measured in Swiss albino mice on day seven after chronic constriction injury (CCI) to the sciatic nerve. Moreover, single administration of MPEP (30 mg/kg; i.p.) or LY379268 (10mg/kg; i.p.) injected 30 min before morphine potentiated morphine's effects (20mg/kg; i.p.) in the mouse CCI model, as measured by both the tests mentioned above. However, a single administration of AMN082 (3mg/kg; i.p.) potentiated the effects of a single morphine injection (20mg/kg; i.p.) in the von Frey test only. Chronic administration (7 days) of low doses of MPEP, LY379268 or AMN082 (all drugs at 3mg/kg; i.p.) potentiated the effects of single doses of morphine (3, 10, and 20mg/kg; i.p.) administered on day seven; however, AMN082 only potentiated the effect in the cold plate test. Additionally, the same doses of MPEP and LY379268 (but not AMN082) chronically co-administered with morphine (40 mg/kg; i.p.) attenuated the development of morphine tolerance in CCI-exposed mice. Our data suggest that mGluR5, mGluR2/3, and mGluR7 are involved in injury-induced plastic changes in nociceptive pathways and that the mGluR5 and mGluR2/3 ligands enhanced morphine's effectiveness in neuropathy, which could have therapeutic implications.

  12. Cerebellar Ataxia and Glutamic Acid Decarboxylase Antibodies

    Science.gov (United States)

    Ariño, Helena; Gresa-Arribas, Nuria; Blanco, Yolanda; Martínez-Hernández, Eugenia; Sabater, Lidia; Petit-Pedrol, Mar; Rouco, Idoia; Bataller, Luis; Dalmau, Josep O.; Saiz, Albert; Graus, Francesc

    2016-01-01

    IMPORTANCE Current clinical and immunologic knowledge on cerebellar ataxia (CA) with glutamic acid decarboxylase 65 antibodies (GAD65-Abs) is based on case reports and small series with short-term follow-up data. OBJECTIVE To report the symptoms, additional antibodies, prognostic factors, and long-term outcomes in a cohort of patients with CA and GAD65-Abs. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study and laboratory investigations at a center for autoimmune neurologic disorders among 34 patients with CA and GAD65-Abs, including 25 with long-term follow-up data (median, 5.4 years; interquartile range, 3.1-10.3 years). MAIN OUTCOMES AND MEASURES Analysis of clinicoimmunologic features and predictors of response to immunotherapy. Immunochemistry on rat brain, cultured neurons, and human embryonic kidney cells expressing GAD65, GAD67, α1-subunit of the glycine receptor, and a repertoire of known cell surface autoantigens were used to identify additional antibodies. Twenty-eight patients with stiff person syndrome and GAD65-Abs served as controls. RESULTS The median age of patients was 58 years (range, 33-80 years); 28 of 34 patients (82%) were women. Nine patients (26%) reported episodes of brainstem and cerebellar dysfunction or persistent vertigo several months before developing CA. The clinical presentation was subacute during a period of weeks in 13 patients (38%). Nine patients (26%) had coexisting stiff person syndrome symptoms. Systemic organ-specific autoimmunities (type 1 diabetes mellitus and others) were present in 29 patients (85%). Twenty of 25 patients with long-term follow-up data received immunotherapy (intravenous immunoglobulin in 10 and corticosteroids and intravenous immunoglobulin or other immunosuppressors in 10), and 7 of them (35%) improved. Predictors of clinical response included subacute onset of CA (odds ratio [OR], 0.50; 95% CI, 0.25-0.99; P = .047) and prompt immunotherapy (OR, 0.98; 95% CI, 0.96-0.99; P = .01). Similar

  13. A conserved BDNF, glutamate- and GABA-enriched gene module related to human depression identified by coexpression meta-analysis and DNA variant genome-wide association studies.

    Directory of Open Access Journals (Sweden)

    Lun-Ching Chang

    Full Text Available Large scale gene expression (transcriptome analysis and genome-wide association studies (GWAS for single nucleotide polymorphisms have generated a considerable amount of gene- and disease-related information, but heterogeneity and various sources of noise have limited the discovery of disease mechanisms. As systematic dataset integration is becoming essential, we developed methods and performed meta-clustering of gene coexpression links in 11 transcriptome studies from postmortem brains of human subjects with major depressive disorder (MDD and non-psychiatric control subjects. We next sought enrichment in the top 50 meta-analyzed coexpression modules for genes otherwise identified by GWAS for various sets of disorders. One coexpression module of 88 genes was consistently and significantly associated with GWAS for MDD, other neuropsychiatric disorders and brain functions, and for medical illnesses with elevated clinical risk of depression, but not for other diseases. In support of the superior discriminative power of this novel approach, we observed no significant enrichment for GWAS-related genes in coexpression modules extracted from single studies or in meta-modules using gene expression data from non-psychiatric control subjects. Genes in the identified module encode proteins implicated in neuronal signaling and structure, including glutamate metabotropic receptors (GRM1, GRM7, GABA receptors (GABRA2, GABRA4, and neurotrophic and development-related proteins [BDNF, reelin (RELN, Ephrin receptors (EPHA3, EPHA5]. These results are consistent with the current understanding of molecular mechanisms of MDD and provide a set of putative interacting molecular partners, potentially reflecting components of a functional module across cells and biological pathways that are synchronously recruited in MDD, other brain disorders and MDD-related illnesses. Collectively, this study demonstrates the importance of integrating transcriptome data, gene

  14. A conserved BDNF, glutamate- and GABA-enriched gene module related to human depression identified by coexpression meta-analysis and DNA variant genome-wide association studies.

    Science.gov (United States)

    Chang, Lun-Ching; Jamain, Stephane; Lin, Chien-Wei; Rujescu, Dan; Tseng, George C; Sibille, Etienne

    2014-01-01

    Large scale gene expression (transcriptome) analysis and genome-wide association studies (GWAS) for single nucleotide polymorphisms have generated a considerable amount of gene- and disease-related information, but heterogeneity and various sources of noise have limited the discovery of disease mechanisms. As systematic dataset integration is becoming essential, we developed methods and performed meta-clustering of gene coexpression links in 11 transcriptome studies from postmortem brains of human subjects with major depressive disorder (MDD) and non-psychiatric control subjects. We next sought enrichment in the top 50 meta-analyzed coexpression modules for genes otherwise identified by GWAS for various sets of disorders. One coexpression module of 88 genes was consistently and significantly associated with GWAS for MDD, other neuropsychiatric disorders and brain functions, and for medical illnesses with elevated clinical risk of depression, but not for other diseases. In support of the superior discriminative power of this novel approach, we observed no significant enrichment for GWAS-related genes in coexpression modules extracted from single studies or in meta-modules using gene expression data from non-psychiatric control subjects. Genes in the identified module encode proteins implicated in neuronal signaling and structure, including glutamate metabotropic receptors (GRM1, GRM7), GABA receptors (GABRA2, GABRA4), and neurotrophic and development-related proteins [BDNF, reelin (RELN), Ephrin receptors (EPHA3, EPHA5)]. These results are consistent with the current understanding of molecular mechanisms of MDD and provide a set of putative interacting molecular partners, potentially reflecting components of a functional module across cells and biological pathways that are synchronously recruited in MDD, other brain disorders and MDD-related illnesses. Collectively, this study demonstrates the importance of integrating transcriptome data, gene coexpression modules

  15. The GLT-1 (EAAT2; slc1a2) glutamate transporter is essential for glutamate homeostasis in the neocortex of the mouse.

    Science.gov (United States)

    Bjørnsen, Lars Petter; Hadera, Mussie G; Zhou, Yun; Danbolt, Niels C; Sonnewald, Ursula

    2014-03-01

    Glutamate is the major excitatory neurotransmitter, and is inactivated by cellular uptake catalyzed mostly by the glutamate transporter subtypes GLT-1 (EAAT2) and GLAST (EAAT1). Astrocytes express both GLT-1 and GLAST, while axon terminals in the neocortex only express GLT-1. To evaluate the role of GLT-1 in glutamate homeostasis, we injected GLT-1 knockout (KO) mice and wild-type littermates with [1-(13)C]glucose and [1,2-(13)C]acetate 15 min before euthanization. Metabolite levels were analyzed in extracts from neocortex and cerebellum and (13)C labeling in neocortex. Whereas the cerebellum in GLT-1-deficient mice had normal levels of glutamate, glutamine, and (13)C labeling of metabolites, glutamate level was decreased but labeling from [1-(13)C] glucose was unchanged in the neocortex. The contribution from pyruvate carboxylation toward labeling of these metabolites was unchanged. Labeling from [1,2-(13)C] acetate, originating in astrocytes, was decreased in glutamate and glutamine in the neocortex indicating reduced mitochondrial metabolism in astrocytes. The decreased amount of glutamate in the cortex indicates that glutamine transport into neurons is not sufficient to replenish glutamate lost because of neurotransmission and that GLT-1 plays a role in glutamate homeostasis in the cortex. Glutamate is the major excitatory neurotransmitter, and is inactivated by uptake via GLT-1 (EAAT2) and GLAST (EAAT1) transporters, while axon terminals in the neocortex only express GLT-1. To evaluate the role of GLT-1 in glutamate homeostasis, we used [1-(13)C]glucose and [1,2-(13)C]acetate injection and NMR spectroscopy. The results indicate that glutamine transport into neurons is not sufficient to replenish glutamate lost because of neurotransmission and that GLT-1 plays a role in glutamate homeostasis in the neocortex.

  16. GABA and Glutamate Uptake and Metabolism in Retinal Glial (Müller) Cells

    OpenAIRE

    Bringmann, Andreas; Grosche, Antje; Pannicke, Thomas; Reichenbach, Andreas

    2013-01-01

    Müller cells, the principal glial cells of the retina, support the synaptic activity by the uptake and metabolization of extracellular neurotransmitters. Müller cells express uptake and exchange systems for various neurotransmitters including glutamate and γ-aminobutyric acid (GABA). Müller cells remove the bulk of extracellular glutamate in the inner retina and contribute to the glutamate clearance around photoreceptor terminals. By the uptake of glutamate, Müller cells are involved in the s...

  17. Glutamate carboxypeptidase II (GCPII) inhibitor displays anti-glutamate and anti-cocaine effects in an invertebrate assay.

    Science.gov (United States)

    Tallarida, Chris; Song, Kevin; Raffa, Robert B; Rawls, Scott M

    2012-06-01

    Glutamate carboxypeptidase II (GCPII) inhibitors are promising anti-glutamatergic and anti-addictive agents. We hypothesized that a GCPII inhibitor 2 (phosphonomethyl) pentanedioic acid (2-PMPA) would display anti-stereotypical activity in planarians. Experiments revealed that 2-PMPA displayed no overt behavioral activity by itself but attenuated stereotypical counts (C-shape hyperkinesias) elicited by four compounds (2-PMPA rank order potency: glutamate>NMDA>pilocarpine>cocaine). These data suggest GCPII inhibitors display broad-spectrum efficacy against behavioral activity produced by glutamatergic and non-glutamatergic compounds in an invertebrate assay.

  18. Cocaine-induced neuroadaptations in the dorsal striatum: glutamate dynamics and behavioral sensitization.

    Science.gov (United States)

    Parikh, Vinay; Naughton, Sean X; Shi, Xiangdang; Kelley, Leslie K; Yegla, Brittney; Tallarida, Christopher S; Rawls, Scott M; Unterwald, Ellen M

    2014-09-01

    Recent evidence suggests that diminished ability to control cocaine seeking arises from perturbations in glutamate homeostasis in the nucleus accumbens. However, the neurochemical substrates underlying cocaine-induced neuroadaptations in the dorsal striatum and how these mechanisms link to behavioral plasticity is not clear. We employed glutamate-sensitive microelectrodes and amperometry to study the impact of repeated cocaine administration on glutamate dynamics in the dorsolateral striatum of awake freely-moving rats. Depolarization-evoked glutamate release was robustly increased in cocaine-pretreated rats challenged with cocaine. Moreover, the clearance of glutamate signals elicited either by terminal depolarization or blockade of non-neuronal glutamate transporters slowed down dramatically in cocaine-sensitized rats. Repeated cocaine exposure also reduced the neuronal tone of striatal glutamate. Ceftriaxone, a β-lactam antibiotic that activates the astrocytic glutamate transporter, attenuated the effects of repeated cocaine exposure on synaptic glutamate release and glutamate clearance kinetics. Finally, the antagonism of AMPA glutamate receptors in the dorsolateral striatum blocked the development of behavioral sensitization to repeated cocaine administration. Collectively, these data suggest that repeated cocaine exposure disrupts presynaptic glutamate transmission and transporter-mediated clearance mechanisms in the dorsal striatum. Moreover, such alterations produce an over activation of AMPA receptors in this brain region leading to the sensitized behavioral response to repeated cocaine.

  19. 40 CFR 721.3821 - L-Glutamic acid, N-(1-oxododecyl)-.

    Science.gov (United States)

    2010-07-01

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

  20. [The comparative investigation of antihypoxia activity of glutamic and N-acetylglutamic acids].

    Science.gov (United States)

    Makarova, L M; Pogorelyĭ, V E

    2013-01-01

    Comparative study of antihypoxic activity of glutamic and N-acetylglutamic acid in doses of 1, 10, 50 and 100 mg/kg was realized. It was experimentally ascertained that the most apparent antihypoxic action of study objects occurs in conditions of hypobaric hypoxia of acetylated derivative of glutamic acid considerably exceeds glutamic acid.

  1. 40 CFR 180.1187 - L-glutamic acid; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

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

  2. Yokukansan, a Traditional Japanese Medicine, Adjusts Glutamate Signaling in Cultured Keratinocytes

    Directory of Open Access Journals (Sweden)

    Maki Wakabayashi

    2014-01-01

    Full Text Available Glutamate plays an important role in skin barrier signaling. In our previous study, Yokukansan (YKS affected glutamate receptors in NC/Nga mice and was ameliorated in atopic dermatitis lesions. The aim of this study was to assess the effect of YKS on skin and cultured human keratinocytes. Glutamate concentrations in skin of YKS-treated and nontreated NC/Nga mice were measured. Then, glutamate release from cultured keratinocytes was measured, and extracellular glutamate concentrations in YKS-stimulated cultured human keratinocytes were determined. The mRNA expression levels of NMDA receptor 2D (NMDAR2D and glutamate aspartate transporter (GLAST were also determined in YKS-stimulated cultured keratinocytes. The glutamate concentrations and dermatitis scores increased in conventional mice, whereas they decreased in YKS-treated mice. Glutamate concentrations in cell supernatants of cultured keratinocytes increased proportionally to the cell density. However, they decreased dose-dependently with YKS. YKS stimulation increased NMDAR2D in a concentration-dependent manner. Conversely, GLAST decreased in response to YKS. Our findings indicate that YKS affects peripheral glutamate signaling in keratinocytes. Glutamine is essential as a transmitter, and dermatitis lesions might produce and release excess glutamate. This study suggests that, in keratinocytes, YKS controls extracellular glutamate concentrations, suppresses N-methyl-D-aspartate (NMDA receptors, and activates glutamate transport.

  3. Feedback-induced glutamate spillover enhances negative feedback from horizontal cells to cones

    NARCIS (Netherlands)

    Vroman, Rozan; Kamermans, M.

    2015-01-01

    KEY POINTS: In the retina, horizontal cells feed back negatively to cone photoreceptors. Glutamate released from cones can spill over to neighbouring cones. Here we show that cone glutamate release induced by negative feedback can also spill over to neighbouring cones. This glutamate activates the g

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

    NARCIS (Netherlands)

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

    1995-01-01

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

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

    NARCIS (Netherlands)

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

    1995-01-01

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

  6. STUDY ON THE SEPARATION OF GLUTAMIC ACID BY ION—EXCHANGE

    Institute of Scientific and Technical Information of China (English)

    ShenJiyu; WangQinyu

    1995-01-01

    The feasibility of recovering glutamic acid by ion exchange method with macroporous resins was investigated.Their adsorption properties in stati state and the effective factors,such as pH,concentration of eeed and the ratio of ammonium ion to glutamic acid,were systematically explored.The best condition of separating glutamic acid from mother liquid were obtained.

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

    NARCIS (Netherlands)

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

    2000-01-01

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

  8. Role of astrocytic glutamate transporter in alcohol use disorder.

    Science.gov (United States)

    Ayers-Ringler, Jennifer R; Jia, Yun-Fang; Qiu, Yan-Yan; Choi, Doo-Sup

    2016-03-22

    Alcohol use disorder (AUD) is one of the most widespread neuropsychiatric conditions, having a significant health and socioeconomic impact. According to the 2014 World Health Organization global status report on alcohol and health, the harmful use of alcohol is responsible for 5.9% of all deaths worldwide. Additionally, 5.1% of the global burden of disease and injury is ascribed to alcohol (measured in disability adjusted life years, or disability adjusted life years). Although the neurobiological basis of AUD is highly complex, the corticostriatal circuit contributes significantly to the development of addictive behaviors. In-depth investigation into the changes of the neurotransmitters in this circuit, dopamine, gamma-aminobutyricacid, and glutamate, and their corresponding neuronal receptors in AUD and other addictions enable us to understand the molecular basis of AUD. However, these discoveries have also revealed a dearth of knowledge regarding contributions from non-neuronal sources. Astrocytes, though intimately involved in synaptic function, had until recently been noticeably overlooked in their potential role in AUD. One major function of the astrocyte is protecting neurons from excitotoxicity by removing glutamate from the synapse via excitatory amino acid transporter type 2. The importance of this key transporter in addiction, as well as ethanol withdrawal, has recently become evident, though its regulation is still under investigation. Historically, pharmacotherapy for AUD has been focused on altering the activity of neuronal glutamate receptors. However, recent clinical evidence has supported the animal-based findings, showing that regulating glutamate homeostasis contributes to successful management of recovery from AUD.

  9. 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-te