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Sample records for acute glutamate excitotoxicity

  1. EFFECT OF MELATONIN AGAINST GLUTAMATE-INDUCED EXCITOTOXICITY ON CULTURED CEREBRAL CORTICAL NEURONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To research the effect of melatonin against glutamate excitotoxicity. Methods The model of glutamate-induced excitotoxic damage was built up in rat cerebral cortical cell culture. The effect of mela- tonin against excitotoxic injury was observed by determining the leakage rate of lactate dehydrogenase(LDH) from neurons. Results The leakage rate of LDH wasn't decreased markedly when cultures were exposed to melatonin be- fore, during or 6 h after glutamate treatment. The leakage rate of LDH was decreased significantly when melatonin was administered 0 h, 2 h or 4 h after the cultures were exposed to glutamate. The inhibitory function of melatonin on LDH leakage was most effective at 2 h and 4 h. Conclusion Melatonin has protective effects on neurons damaged by glutamate in a certain time limit.

  2. Downregualtion of dynamin-related protein 1 attenuates glutamate-induced excitotoxicity via regulating mitochondrial function in a calcium dependent manner in HT22 cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chi; Yuan, Xian-rui; Li, Hao-yu; Zhao, Zi-jin; Liao, Yi-wei; Wang, Xiang-yu; Su, Jun; Sang, Shu-shan; Liu, Qing, E-mail: xiangyaliuqing@163.com

    2014-01-03

    Highlights: •Downregulation of Drp-1 attenuates glutamate-induced excitotoxicity. •Downregulation of Drp-1 inhibits glutamate-induced apoptosis. •Downregulation of Drp-1 reduces glutamate-induced mitochondrial dysfunction. •Downregulation of Drp-1 preserves intracellular calcium homeostasis. -- Abstract: Glutamate-mediated excitotoxicity is involved in many acute and chronic brain diseases. Dynamin related protein 1 (Drp-1), one of the GTPase family of proteins that regulate mitochondrial fission and fusion balance, is associated with apoptotic cell death in cancer and neurodegenerative diseases. Here we investigated the effect of downregulating Drp-1 on glutamate excitotoxicity-induced neuronal injury in HT22 cells. We found that downregulation of Drp-1 with specific small interfering RNA (siRNA) increased cell viability and inhibited lactate dehydrogenase (LDH) release after glutamate treatment. Downregulation of Drp-1 also inhibited an increase in the Bax/Bcl-2 ratio and cleavage of caspase-9 and caspase-3. Drp-1 siRNA transfection preserved the mitochondrial membrane potential (MMP), reduced cytochrome c release, enhanced ATP production, and partly prevented mitochondrial swelling. In addition, Drp-1 knockdown attenuated glutamate-induced increases of cytoplasmic and mitochondrial Ca{sup 2+}, and preserved the mitochondrial Ca{sup 2+} buffering capacity after excitotoxicity. Taken together, these results suggest that downregulation of Drp-1 protects HT22 cells against glutamate-induced excitatory damage, and this neuroprotection may be dependent at least in part on the preservation of mitochondrial function through regulating intracellular calcium homeostasis.

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

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    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.

  4. Mechanisms underlying the neurotoxicity induced by glyphosate-based herbicide in immature rat hippocampus: Involvement of glutamate excitotoxicity

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Roundup® induces Ca2+ influx through L-VDCC and NMDA receptor activation. • The mechanisms underlying Roundup® neurotoxicity involve glutamatergic excitotoxicity. • Kinase pathways participate in Roundup®-induced neural toxicity. • Roundup® alters glutamate uptake, release and metabolism in hippocampal cells. - Abstract: Previous studies demonstrate that glyphosate exposure is associated with oxidative damage and neurotoxicity. Therefore, the mechanism of glyphosate-induced neurotoxic effects needs to be determined. The aim of this study was to investigate whether Roundup® (a glyphosate-based herbicide) leads to neurotoxicity in hippocampus of immature rats following acute (30 min) and chronic (pregnancy and lactation) pesticide exposure. Maternal exposure to pesticide was undertaken by treating dams orally with 1% Roundup® (0.38% glyphosate) during pregnancy and lactation (till 15-day-old). Hippocampal slices from 15 day old rats were acutely exposed to Roundup® (0.00005–0.1%) during 30 min and experiments were carried out to determine whether glyphosate affects 45Ca2+ influx and cell viability. Moreover, we investigated the pesticide effects on oxidative stress parameters, 14C-α-methyl-amino-isobutyric acid (14C-MeAIB) accumulation, as well as glutamate uptake, release and metabolism. Results showed that acute exposure to Roundup® (30 min) increases 45Ca2+ influx by activating NMDA receptors and voltage-dependent Ca2+ channels, leading to oxidative stress and neural cell death. The mechanisms underlying Roundup®-induced neurotoxicity also involve the activation of CaMKII and ERK. Moreover, acute exposure to Roundup® increased 3H-glutamate released into the synaptic cleft, decreased GSH content and increased the lipoperoxidation, characterizing excitotoxicity and oxidative damage. We also observed that both acute and chronic exposure to Roundup® decreased 3H-glutamate uptake and metabolism, while induced 45

  5. System x(c)(-) regulates microglia and macrophage glutamate excitotoxicity in vivo.

    Science.gov (United States)

    Kigerl, Kristina A; Ankeny, Daniel P; Garg, Sanjay K; Wei, Ping; Guan, Zhen; Lai, Wenmin; McTigue, Dana M; Banerjee, Ruma; Popovich, Phillip G

    2012-01-01

    It is widely believed that microglia and monocyte-derived macrophages (collectively referred to as central nervous system (CNS) macrophages) cause excitotoxicity in the diseased or injured CNS. This view has evolved mostly from in vitro studies showing that neurotoxic concentrations of glutamate are released from CNS macrophages stimulated with lipopolysaccharide (LPS), a potent inflammogen. We hypothesized that excitotoxic killing by CNS macrophages is more rigorously controlled in vivo, requiring both the activation of the glutamate/cystine antiporter (system x(c)(-)) and an increase in extracellular cystine, the substrate that drives glutamate release. Here, we show that non-traumatic microinjection of low-dose LPS into spinal cord gray matter activates CNS macrophages but without causing overt neuropathology. In contrast, neurotoxic inflammation occurs when LPS and cystine are co-injected. Simultaneous injection of NBQX, an antagonist of AMPA glutamate receptors, reduces the neurotoxic effects of LPS+cystine, implicating glutamate as a mediator of neuronal cell death in this model. Surprisingly, neither LPS nor LPS+cystine adversely affects survival of oligodendrocytes or oligodendrocyte progenitor cells. Ex vivo analyses show that redox balance in microglia and macrophages is controlled by induction of system x(c)(-) and that high GSH:GSSG ratios predict the neurotoxic potential of these cells. Together, these data indicate that modulation of redox balance in CNS macrophages, perhaps through regulating system x(c)(-), could be a novel approach for attenuating injurious neuroinflammatory cascades.

  6. NSC-34 Motor Neuron-Like Cells Are Unsuitable as Experimental Model for Glutamate-Mediated Excitotoxicity

    Science.gov (United States)

    Madji Hounoum, Blandine; Vourc’h, Patrick; Felix, Romain; Corcia, Philippe; Patin, Franck; Guéguinou, Maxime; Potier-Cartereau, Marie; Vandier, Christophe; Raoul, Cédric; Andres, Christian R.; Mavel, Sylvie; Blasco, Hélène

    2016-01-01

    Glutamate-induced excitotoxicity is a major contributor to motor neuron degeneration in the pathogenesis of amyotrophic lateral sclerosis (ALS). The spinal cord × Neuroblastoma hybrid cell line (NSC-34) is often used as a bona fide cellular model to investigate the physiopathological mechanisms of ALS. However, the physiological response of NSC-34 to glutamate remains insufficiently described. In this study, we evaluated the relevance of differentiated NSC-34 (NSC-34D) as an in vitro model for glutamate excitotoxicity studies. NSC-34D showed morphological and physiological properties of motor neuron-like cells and expressed glutamate receptor subunits GluA1–4, GluN1 and GluN2A/D. Despite these diverse characteristics, no specific effect of glutamate was observed on cultured NSC-34D survival and morphology, in contrast to what has been described in primary culture of motor neurons (MN). Moreover, a small non sustained increase in the concentration of intracellular calcium was observed in NSC-34D after exposure to glutamate compared to primary MN. Our findings, together with the inability to obtain cultures containing only differentiated cells, suggest that the motor neuron-like NSC-34 cell line is not a suitable in vitro model to study glutamate-induced excitotoxicity. We suggest that the use of primary cultures of MN is more suitable than NSC-34 cell line to explore the pathogenesis of glutamate-mediated excitotoxicity at the cellular level in ALS and other motor neuron diseases. PMID:27242431

  7. A neuroprotective role for microRNA miR-1000 mediated by limiting glutamate excitotoxicity

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    Verma, Pushpa; Augustine, George J; Ammar, Mohamed-Raafet;

    2015-01-01

    Evidence has begun to emerge for microRNAs as regulators of synaptic signaling, specifically acting to control postsynaptic responsiveness during synaptic transmission. In this report, we provide evidence that Drosophila melanogaster miR-1000 acts presynaptically to regulate glutamate release...... at the synapse by controlling expression of the vesicular glutamate transporter (VGlut). Genetic deletion of miR-1000 led to elevated apoptosis in the brain as a result of glutamatergic excitotoxicity. The seed-similar miR-137 regulated VGluT2 expression in mouse neurons. These conserved miRNAs share...... a neuroprotective function in the brains of flies and mice. Drosophila miR-1000 showed activity-dependent expression, which might serve as a mechanism to allow neuronal activity to fine-tune the strength of excitatory synaptic transmission....

  8. Glutamate excitotoxicity and Ca(2+)-regulation of respiration: Role of the Ca(2+) activated mitochondrial transporters (CaMCs).

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    Rueda, Carlos B; Llorente-Folch, Irene; Traba, Javier; Amigo, Ignacio; Gonzalez-Sanchez, Paloma; Contreras, Laura; Juaristi, Inés; Martinez-Valero, Paula; Pardo, Beatriz; Del Arco, Araceli; Satrustegui, Jorgina

    2016-08-01

    Glutamate elicits Ca(2+) signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to physiological glutamate signals, cytosolic Ca(2+) activates respiration by stimulation of the NADH malate-aspartate shuttle through Ca(2+)-binding to the mitochondrial aspartate/glutamate carrier (Aralar/AGC1/Slc25a12), and by stimulation of adenine nucleotide uptake through Ca(2+) binding to the mitochondrial ATP-Mg/Pi carrier (SCaMC-3/Slc25a23). In addition, after Ca(2+) entry into the matrix through the mitochondrial Ca(2+) uniporter (MCU), it activates mitochondrial dehydrogenases. In response to pathological glutamate stimulation during excitotoxicity, Ca(2+) overload, reactive oxygen species (ROS), mitochondrial dysfunction and delayed Ca(2+) deregulation (DCD) lead to neuronal death. Glutamate-induced respiratory stimulation is rapidly inactivated through a mechanism involving Poly (ADP-ribose) Polymerase-1 (PARP-1) activation, consumption of cytosolic NAD(+), a decrease in matrix ATP and restricted substrate supply. Glutamate-induced Ca(2+)-activation of SCaMC-3 imports adenine nucleotides into mitochondria, counteracting the depletion of matrix ATP and the impaired respiration, while Aralar-dependent lactate metabolism prevents substrate exhaustion. A second mechanism induced by excitotoxic glutamate is permeability transition pore (PTP) opening, which critically depends on ROS production and matrix Ca(2+) entry through the MCU. By increasing matrix content of adenine nucleotides, SCaMC-3 activity protects against glutamate-induced PTP opening and lowers matrix free Ca(2+), resulting in protracted appearance of DCD and protection against excitotoxicity in vitro and in vivo, while the lack of lactate protection during in vivo excitotoxicity explains increased vulnerability to kainite-induced toxicity in Aralar

  9. Glutamate excitotoxicity and Ca2+-regulation of respiration: Role of the Ca2+ activated mitochondrial transporters (CaMCs).

    Science.gov (United States)

    Rueda, Carlos B; Llorente-Folch, Irene; Traba, Javier; Amigo, Ignacio; Gonzalez-Sanchez, Paloma; Contreras, Laura; Juaristi, Inés; Martinez-Valero, Paula; Pardo, Beatriz; Del Arco, Araceli; Satrustegui, Jorgina

    2016-08-01

    Glutamate elicits Ca(2+) signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to physiological glutamate signals, cytosolic Ca(2+) activates respiration by stimulation of the NADH malate-aspartate shuttle through Ca(2+)-binding to the mitochondrial aspartate/glutamate carrier (Aralar/AGC1/Slc25a12), and by stimulation of adenine nucleotide uptake through Ca(2+) binding to the mitochondrial ATP-Mg/Pi carrier (SCaMC-3/Slc25a23). In addition, after Ca(2+) entry into the matrix through the mitochondrial Ca(2+) uniporter (MCU), it activates mitochondrial dehydrogenases. In response to pathological glutamate stimulation during excitotoxicity, Ca(2+) overload, reactive oxygen species (ROS), mitochondrial dysfunction and delayed Ca(2+) deregulation (DCD) lead to neuronal death. Glutamate-induced respiratory stimulation is rapidly inactivated through a mechanism involving Poly (ADP-ribose) Polymerase-1 (PARP-1) activation, consumption of cytosolic NAD(+), a decrease in matrix ATP and restricted substrate supply. Glutamate-induced Ca(2+)-activation of SCaMC-3 imports adenine nucleotides into mitochondria, counteracting the depletion of matrix ATP and the impaired respiration, while Aralar-dependent lactate metabolism prevents substrate exhaustion. A second mechanism induced by excitotoxic glutamate is permeability transition pore (PTP) opening, which critically depends on ROS production and matrix Ca(2+) entry through the MCU. By increasing matrix content of adenine nucleotides, SCaMC-3 activity protects against glutamate-induced PTP opening and lowers matrix free Ca(2+), resulting in protracted appearance of DCD and protection against excitotoxicity in vitro and in vivo, while the lack of lactate protection during in vivo excitotoxicity explains increased vulnerability to kainite-induced toxicity in Aralar

  10. Green Tea Polyphenols Attenuated Glutamate Excitotoxicity via Antioxidative and Antiapoptotic Pathway in the Primary Cultured Cortical Neurons

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    Lin Cong

    2016-01-01

    Full Text Available Green tea polyphenols are a natural product which has antioxidative and antiapoptotic effects. It has been shown that glutamate excitotoxicity induced oxidative stress is linked to neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. In this study we explored the neuroprotective effect of green teen polyphenols against glutamate excitotoxicity in the primary cultured cortical neurons. We found that green tea polyphenols protected against glutamate induced neurotoxicity in the cortical neurons as measured by MTT and TUNEL assays. Green tea polyphenols were then showed to inhibit the glutamate induced ROS release and SOD activity reduction in the neurons. Furthermore, our results demonstrated that green tea polyphenols restored the dysfunction of mitochondrial pro- or antiapoptotic proteins Bax, Bcl-2, and caspase-3 caused by glutamate. Interestingly, the neuroprotective effect of green tea polyphenols was abrogated when the neurons were incubated with siBcl-2. Taken together, these results demonstrated that green tea polyphenols protected against glutamate excitotoxicity through antioxidative and antiapoptotic pathways.

  11. Computational Analysis of AMPK-Mediated Neuroprotection Suggests Acute Excitotoxic Bioenergetics and Glucose Dynamics Are Regulated by a Minimal Set of Critical Reactions.

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    Niamh M C Connolly

    Full Text Available Loss of ionic homeostasis during excitotoxic stress depletes ATP levels and activates the AMP-activated protein kinase (AMPK, re-establishing energy production by increased expression of glucose transporters on the plasma membrane. Here, we develop a computational model to test whether this AMPK-mediated glucose import can rapidly restore ATP levels following a transient excitotoxic insult. We demonstrate that a highly compact model, comprising a minimal set of critical reactions, can closely resemble the rapid dynamics and cell-to-cell heterogeneity of ATP levels and AMPK activity, as confirmed by single-cell fluorescence microscopy in rat primary cerebellar neurons exposed to glutamate excitotoxicity. The model further correctly predicted an excitotoxicity-induced elevation of intracellular glucose, and well resembled the delayed recovery and cell-to-cell heterogeneity of experimentally measured glucose dynamics. The model also predicted necrotic bioenergetic collapse and altered calcium dynamics following more severe excitotoxic insults. In conclusion, our data suggest that a minimal set of critical reactions may determine the acute bioenergetic response to transient excitotoxicity and that an AMPK-mediated increase in intracellular glucose may be sufficient to rapidly recover ATP levels following an excitotoxic insult.

  12. Topiramate protects against glutamate excitotoxicity via activating BDNF/TrkB-dependent ERK pathway in rodent hippocampal neurons.

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    Mao, Xiao-Yuan; Cao, Yong-Gang; Ji, Zhong; Zhou, Hong-Hao; Liu, Zhao-Qian; Sun, Hong-Li

    2015-07-01

    Topiramate (TPM) was previously found to have neuroprotection against neuronal injury in epileptic and ischemic models. However, whether TPM protects against glutamate-induced excitotoxicity in hippocampal neurons is elusive. Our present work aimed to evaluate the protective effect of TPM against glutamate toxicity in hippocampal neurons and further figure out the potential molecular mechanisms. The in vitro glutamate excitotoxic model was prepared with 125μM glutamate for 20min. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) analysis and Hoechst 33342 staining were conducted to detect neuronal survival. The protein expressions of brain-derived neurotrophic factor (BDNF), TrkB, mitogen-activated protein kinase (MAPK) cascade (including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK), cyclic AMP response element binding protein (CREB), Bcl-2, Bax and β-actin were detected via Western blot assay. Our results demonstrated that TPM protected hippocampal neurons from glutamate toxicity. Meanwhile, the pretreatment of TPM for 10min significantly prevented the down-regulation of BDNF and the phosphorylation of TrkB. Furthermore, the elevation of phosphorylated EKR expression was significantly inhibited after blockade of TrkB by TrkB IgG, while no alterations of phosphorylated JNK and p38 MAPK were found in the cultured hippocampal neurons. Besides, it was also found that the enhanced phosphorylation of CREB was evidently reversed under excitotoxic conditions after treating with U0126 (the selective inhibitor of ERK). The protein level of Bcl-2 was also observed to be remarkably increased after TPM treatment. In conclusion, these findings implicate that TPM exerts neuroprotective effects against glutamate excitotoxicity in hippocampal neurons and its protection may be modulated through BDNF/TrkB-dependent ERK pathway.

  13. Excitotoxic damage to white matter

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    Matute, Carlos; Alberdi, Elena; Domercq, María; Sánchez-Gómez, María-Victoria; Pérez-Samartín, Alberto; Rodríguez-Antigüedad, Alfredo; Pérez-Cerdá, Fernando

    2007-01-01

    Glutamate kills neurons by excitotoxicity, which is caused by sustained activation of glutamate receptors. In recent years, it has been shown that glutamate can also be toxic to white matter oligodendrocytes and to myelin by this mechanism. In particular, glutamate receptor-mediated injury to these cells can be triggered by activation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and N-methyl-d-aspartate glutamate receptor types. Thus, these receptor classes, and the intermediaries of the signal cascades they activate, are potential targets for drug development to treat white matter damage in acute and chronic diseases. In addition, alterations of glutamate homeostasis in white matter can determine glutamate injury to oligodendrocytes and myelin. Astrocytes are responsible for most glutamate uptake in synaptic and non-synaptic areas and consequently are the major regulators of glutamate homeostasis. Activated microglia in turn may secrete cytokines and generate radical oxygen species, which impair glutamate uptake and reduce the expression of glutamate transporters. Finally, oligodendrocytes also contribute to glutamate homeostasis. This review aims at summarizing the current knowledge about the mechanisms leading to oligodendrocyte cell death and demyelination as a consequence of alterations in glutamate signalling, and their clinical relevance to disease. In addition, we show evidence that oligodendrocytes can also be killed by ATP acting at P2X receptors. A thorough understanding of how oligodendrocytes and myelin are damaged by excitotoxicity will generate knowledge that can lead to improved therapeutic strategies to protect white matter. PMID:17504270

  14. Protection of taurine and granulocyte colony-stimulating factor against excitotoxicity induced by glutamate in primary cortical neurons

    OpenAIRE

    Pan, Chunliu; Gupta, Amit; Prentice, Howard; Wu, Jang-Yen

    2010-01-01

    Abstracts Background Both taurine, an inhibitory neurotransmitter and granulocyte colony-stimulating factor (G-CSF), a growth factor, possess neuroprotective and neurotrophic properties in vitro. However, the mechanisms of their underlying neuroprotective effects are not fully understood. Methods In the present study, we investigated the potential protective benefits of taurine, G-CSF and the combination of taurine and G-CSF against excitotoxicity induced by glutamate in primary cortical neur...

  15. Protection of cortical cells by equine estrogens against glutamate-induced excitotoxicity is mediated through a calcium independent mechanism

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    Perrella Joel

    2005-05-01

    Full Text Available Abstract Background High concentrations of glutamate can accumulate in the brain and may be involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease. This form of neurotoxicity involves changes in the regulation of cellular calcium (Ca2+ and generation of free radicals such as peroxynitrite (ONOO-. Estrogen may protect against glutamate-induced cell death by reducing the excitotoxic Ca2+ influx associated with glutamate excitotoxicity. In this study, the inhibition of N-methyl-D-aspartate (NMDA receptor and nitric oxide synthase (NOS along with the effect of 17β-estradiol (17β-E2 and a more potent antioxidant Δ8, 17β-estradiol (Δ8, 17β-E2 on cell viability and intracellular Ca2+ ([Ca2+]i, following treatment of rat cortical cells with glutamate, was investigated. Results Primary rat cortical cells were cultured for 7–12 days in Neurobasal medium containing B27 supplements. Addition of glutamate (200 μM decreased cell viability to 51.3 ± 0.7% compared to control. Treatment with the noncompetitive NMDAR antagonist, MK-801, and the NOS inhibitor, L-NAME, completely prevented cell death. Pretreatment (24 hrs with 17β-E2 and Δ8, 17β-E2 (0.01 to 10 μM significantly reduced cell death. 17β-E2 was more potent than Δ8, 17β-E2. Glutamate caused a rapid 2.5 fold increase in [Ca2+]i. Treatment with 0.001 to 10 μM MK-801 reduced the initial Ca2+ influx by 14–41% and increased cell viability significantly. Pretreatment with 17β-E2 and Δ8, 17β-E2 had no effect on Ca2+ influx but protected the cortical cells against glutamate-induced cell death. Conclusion Glutamate-induced cell death in cortical cultures can occur through NMDAR and NOS-linked mechanisms by increasing nitric oxide and ONOO-. Equine estrogens: 17β-E2 and Δ8, 17β-E2, significantly protected cortical cells against glutamate-induced excitotoxicity by a mechanism that appears to be independent of Ca2+ influx. To our knowledge, this is a first

  16. Magnolol reduces glutamate-induced neuronal excitotoxicity and protects against permanent focal cerebral ischemia up to 4 hours.

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    Wei-Ting Lee

    Full Text Available Neuroprotective efficacy of magnolol, 5,5'-dially-2,2'-dihydroxydiphenyl, was investigated in a model of stroke and cultured neurons exposed to glutamate-induced excitotoxicity. Rats were subjected to permanent middle cerebral artery occlusion (pMCAO. Magnolol or vehicle was administered intraperitoneally, at 1 hr pre-insult or 1-6 hrs post-insult. Brain infarction was measured upon sacrifice. Relative to controls, animals pre-treated with magnolol (50-200 mg/kg had significant infarct volume reductions by 30.9-37.8% and improved neurobehavioral outcomes (P<0.05, respectively. Delayed treatment with magnolol (100 mg/kg also protected against ischemic brain damage and improved neurobehavioral scores, even when administered up to 4 hrs post-insult (P<0.05, respectively. Additionally, magnolol (0.1 µM effectively attenuated the rises of intracellular Ca(2+ levels, [Ca(2+](i, in cultured neurons exposed to glutamate. Consequently, magnolol (0.1-1 µM significantly attenuated glutamate-induced cytotoxicity and cell swelling (P<0.05. Thus, magnolol offers neuroprotection against permanent focal cerebral ischemia with a therapeutic window of 4 hrs. This neuroprotection may be, partly, mediated by its ability to limit the glutamate-induced excitotoxicity.

  17. Low dose of L-glutamic acid attenuated the neurological dysfunctions and excitotoxicity in bilateral common carotid artery occluded mice.

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    Ramanathan, Muthiah; Abdul, Khadar K; Justin, Antony

    2016-10-01

    Glutamate, an excitatory neurotransmitter in the brain, produces excitotoxicity through its agonistic action on postsynaptic N-methyl-D-aspartate receptor, resulting in neurodegeneration. We hypothesized that the administration of low doses of glutamate in cerebral ischemia could attenuate the excitotoxicity in neurons through its autoreceptor regulatory mechanism, and thereby control neurodegeneration. To test the hypothesis, the effect of L-glutamic acid (L-GA) 400 μmol/l/kg was evaluated in a bilateral common carotid artery occlusion-induced global ischemic mouse model. Memantine was used as a positive control. Global ischemia in mice was induced by occlusion of both the common carotid artery (bilateral common carotid artery occlusion) for 20 min, followed by reperfusion injury. L-GA was infused slowly through the tail vein 30 min before the surgery and every 24 h thereafter until the end of the experiment. The time-dependent change in cerebral blood flow was monitored using a laser Doppler image analyzer. The neurotransmitters glutamate and γ-aminobutyric acid (GABA) and the neurobiochemicals ATP, glutathione, and nitric oxide were measured in the different regions of brain at 0, 24, 48, and 72 h after reperfusion injury. L-GA increased locomotor activity, muscle coordination, and cerebral blood flow in ischemic mice at 72 h after ischemic insult. L-GA reduced glutamate levels in the cortex, striatum, and hippocampus at 72 h, whereas GABA levels were elevated in all three brain regions studied. Further, L-GA elevated glutathione levels and attenuated nitric oxide levels, but failed to restore ATP levels 72 h after ischemia-reperfusion. We conclude that the gradual reduction of glutamate along with elevation of GABA in different brain regions could have contributed toward the neuroprotective effect of L-GA. Hence, a slow infusion of a low dose of L-GA could be beneficial in controlling excitotoxicity-induced neurodegeneration following ischemia

  18. Data of multiple regressions analysis between selected biomarkers related to glutamate excitotoxicity and oxidative stress in Saudi autistic patients.

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    El-Ansary, Afaf

    2016-06-01

    This work demonstrates data of multiple regression analysis between nine biomarkers related to glutamate excitotoxicity and impaired detoxification as two mechanisms recently recorded as autism phenotypes. The presented data was obtained by measuring a panel of markers in 20 autistic patients aged 3-15 years and 20 age and gender matching healthy controls. Levels of GSH, glutathione status (GSH/GSSG), glutathione reductase (GR), glutathione-s-transferase (GST), thioredoxin (Trx), thioredoxin reductase (TrxR) and peroxidoxins (Prxs I and III), glutamate, glutamine, glutamate/glutamine ratio glutamate dehydrogenase (GDH) in plasma and mercury (Hg) in red blood cells were determined in both groups. In Multiple regression analysis, R (2) values which describe the proportion or percentage of variance in the dependent variable attributed to the variance in the independent variables together were calculated. Moreover, β coefficients values which show the direction either positive or negative and the contribution of the independent variable relative to the other independent variables in explaining the variation of the dependent variable were determined. A panel of inter-related markers was recorded. This paper contains data related to and supporting research articles currently published entitled "Mechanism of nitrogen metabolism-related parameters and enzyme activities in the pathophysiology of autism" [1], "Novel metabolic biomarkers related to sulfur-dependent detoxification pathways in autistic patients of Saudi Arabia [2], and "A key role for an impaired detoxification mechanism in the etiology and severity of autism spectrum disorders" [3]. PMID:26933667

  19. Brain energy metabolism in glutamate-receptor activation and excitotoxicity: role for APC/C-Cdh1 in the balance glycolysis/pentose phosphate pathway.

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    Rodriguez-Rodriguez, Patricia; Almeida, Angeles; Bolaños, Juan P

    2013-04-01

    Recent advances in the field of brain energy metabolism strongly suggest that glutamate receptor-mediated neurotransmission is coupled with molecular signals that switch-on glucose utilization pathways to meet the high energetic requirements of neurons. Failure to adequately coordinate energy supply for neurotransmission ultimately results in a positive amplifying loop of receptor over-activation leading to neuronal death, a process known as excitotoxicity. In this review, we revisited current concepts in excitotoxic mechanisms, their involvement in energy substrate utilization, and the signaling pathways that coordinate both processes. In particular, we have focused on the novel role played by the E3 ubiquitin ligase, anaphase-promoting complex/cyclosome (APC/C)-Cdh1, in cell metabolism. Our laboratory identified 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) -a key glycolytic-promoting enzyme- as an APC/C-Cdh1 substrate. Interestingly, APC/C-Cdh1 activity is inhibited by over-activation of glutamate receptors through a Ca(2+)-mediated mechanism. Furthermore, by inhibiting APC/C-Cdh1 activity, glutamate-receptors activation promotes PFKFB3 stabilization, leading to increased glycolysis and decreased pentose-phosphate pathway activity. This causes a loss in neuronal ability to regenerate glutathione, triggering oxidative stress and delayed excitotoxicity. Further investigation is critical to identify novel molecules responsible for the coupling of energy metabolism with glutamatergic neurotransmission and excitotoxicity, as well as to help developing new therapeutic strategies against neurodegeneration.

  20. Oncostatin M promotes excitotoxicity by inhibiting glutamate uptake in astrocytes : implications in HIV-associated neurotoxicity

    NARCIS (Netherlands)

    Moidunny, Shamsudheen; Matos, Marco; Wesseling, Evelyn; Banerjee, Santanu; Volsky, David J; Cunha, Rodrigo A; Agostinho, Paula; Boddeke, Hendrikus W; Roy, Sabita

    2016-01-01

    BACKGROUND: Elevated levels of oncostatin M (OSM), an interleukin-6 cytokine family member, have been observed in HIV-1-associated neurocognitive disorders (HAND) and Alzheimer's disease. However, the function of OSM in these disease conditions is unclear. Since deficient glutamate uptake by astrocy

  1. Curcumin Protects Neurons from Glutamate-Induced Excitotoxicity by Membrane Anchored AKAP79-PKA Interaction Network

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    Kui Chen

    2015-01-01

    Full Text Available Now stimulation of AMPA receptor as well as its downstream pathways is considered as potential central mediators in antidepressant mechanisms. As a signal integrator which binds to AMPA receptor, A-kinase anchoring protein 79-(AKAP79- PKA complex is regarded as a potential drug target to exert neuroprotective effects. A well-tolerated and multitarget drug curcumin has been confirmed to exert antidepressant-like effects. To explore whether AKAP79-PKA complex is involved in curcumin-mediated antiexcitotoxicity, we detected calcium signaling, subcellular location of AKAP79-PKA complex, phosphorylation of glutamate receptor, and ERK and AKT cascades. In this study, we found that curcumin protected neurons from glutamate insult by reducing Ca2+ influx and blocking the translocation of AKAP79 from cytomembrane to cytoplasm. In parallel, curcumin enhanced the phosphorylation of AMPA receptor and its downstream pathways in PKA-dependent manner. If we pretreated cells with PKA anchoring inhibitor Ht31 to disassociate PKA from AKAP79, no neuroprotective effects were observed. In conclusion, our results show that AKAP79-anchored PKA facilitated the signal relay from AMPA receptor to AKT and ERK cascades, which may be crucial for curcumin-mediated antiexcitotoxicity.

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

    DEFF Research Database (Denmark)

    Baskys, Andrius; Bayazitov, Ildar; Fang, Liwei;

    2005-01-01

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

  3. Neuropathological characterization of spinal motor neuron degeneration processes induced by acute and chronic excitotoxic stimulus in vivo.

    Science.gov (United States)

    Ramírez-Jarquín, Uri Nimrod; Tapia, Ricardo

    2016-09-01

    Motor neuron (MN) diseases are characterized by progressive cell degeneration, and excitotoxicity has been postulated as a causal factor. Using two experimental procedures for inducing excitotoxic spinal MN degeneration in vivo, by acute and chronic overactivation of α-amino-3-hydroxy-5-methyl-4-isoxazoleacetic acid (AMPA) receptors, we characterized the time course of the neuropathological changes. Electron transmission microscopy showed that acute AMPA perfusion by microdialysis caused MN swelling 1.5h after surgery and lysis with membrane rupture as early as 3h; no cleaved caspase 3 was detected by immunochemistry. Chronic AMPA infusion by osmotic minipumps induced a slow degeneration process along 5days, characterized by progressive changes: endoplasmic reticulum swelling, vacuolization of cytoplasm, vacuole fusion and cell membrane rupture. Quantification of these ultrastructural alterations showed that the increase of vacuolated area was at the expense of the nuclear area. Caspase 3 cleavage was observed since the first day of AMPA infusion. We conclude that acute AMPA-induced excitotoxicity induces MN loss by necrosis, while the progress of degeneration induced by chronic infusion is slow, starting with an early apoptotic process followed by necrosis. In both the acute and chronic procedures a correlation could be established between the loss of MN by necrosis, but not by caspase 3-linked apoptosis, and severe motor deficits and hindlimb paralysis. Our findings are relevant for understanding the mechanisms of neuron death in degenerative diseases and thus for the design of pharmacological therapeutic strategies. PMID:27320208

  4. Potent protection of Danshensu(β-3,4-dihydroxyphenyl-lactic acid)against excitotoxic effects of maternal intragastric administration of monosodium glutamate at a late stage of pregnancy on developing mouse fetal brain

    Institute of Scientific and Technical Information of China (English)

    Jingen Shen; Lijian Yu; Rundi Ma; Yongping Zhang; Xiaoyu Zhang; Juanzhi Fang; Tingxi Yu

    2010-01-01

    Recent studies have demonstrated that ferulic acid[3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid]and sodium ferulate produce protective effects against glutamate-induced neurotoxicity in adult mice.Danshensu(β-3,4-dihydroxyphenyl-lactic acid)has a similar molecular structure and pharmacological action to caffeic acid.This study aimed to validate the protection conferred by Danshensu against excitotoxic effects of maternal intragastric administration of monosodium glutamate at late stages of pregnancy in the developing mouse fetal brain.Behavioral tests,as well as histopathological and immunohistochemical examination of hippocampi were performed in filial mice.Results revealed that maternal intragastric administration of excessive monosodium glutamate(1.0,2.0,4.0 g/kg body weight)at a late stage of pregnancy resulted in a series of behavioral disorders(hyperactivity,lesions of learning and memory,and disturbance in cooperation of movement ability under high-altitude stress),histopathological impairment(neuronal edema,degeneration,necrosis,and hyperplasia)and molecular cellular biological changes(upregulated expression of N-methyI-D-aspartate receptor type 1 and neuropeptide Y in the hippocampal region of the brain of the filial mice from mothers treated with monosodium glutamate).Simultaneous administration of sodium Danshensu partially reversed the effects of monosodium glutamate on the above mentioned phenomena.These findings indicate that sodium Danshensu exhibits obvious protective effects on the excitotoxicity of monosodium glutamate.

  5. Identification of Bax-interacting proteins in oligodendrocyte progenitors during glutamate excitotoxicity and perinatal hypoxia–ischemia

    Directory of Open Access Journals (Sweden)

    Sopio Simonishvili

    2013-12-01

    Full Text Available OPC (oligodendrocyte progenitor cell death contributes significantly to the pathology and functional deficits following hypoxic-ischemic injury in the immature brain and to deficits resulting from demyelinating diseases, trauma and degenerative disorders in the adult CNS. Glutamate toxicity is a major cause of oligodendroglial death in diverse CNS disorders, and previous studies have demonstrated that AMPA/kainate receptors require the pro-apoptotic protein Bax in OPCs undergoing apoptosis. The goal of the present study was to define the pro-apoptotic and anti-apoptotic effectors that regulate Bax in healthy OPCs and after exposure to excess glutamate in vitro and following H–I (hypoxia–ischemia in the immature rat brain. We show that Bax associates with a truncated form of Bid, a BH3-only domain protein, subsequent to glutamate treatment. Furthermore, glutamate exposure reduces Bax association with the anti-apoptotic Bcl family member, Bcl-xL. Cell fractionation studies demonstrated that both Bax and Bid translocate from the cytoplasm to mitochondria during the early stages of cell death consistent with a role for Bid as an activator, whereas Bcl-xL, which normally complexes with both Bax and Bid, disassociates from these complexes when OPCs are exposed to excess glutamate. Bax remained unactivated in the presence of insulin-like growth factor-1, and the Bcl-xL complexes were protected. Our data similarly demonstrate loss of Bcl-xL–Bax association in white matter following H–I and implicate active Bad in Bax-mediated OPC death. To identify other Bax-binding partners, we used proteomics and identified cofilin as a Bax-associated protein in OPCs. Cofilin and Bax associated in healthy OPCs, whereas the Bax–cofilin association was disrupted during glutamate-induced OPC apoptosis.

  6. Sepsis otopathy: experimental sepsis leads to significant hearing impairment due to apoptosis and glutamate excitotoxicity in murine cochlea

    Directory of Open Access Journals (Sweden)

    Joachim Schmutzhard

    2013-05-01

    Hearing loss is frequent in intensive care patients and can be due to several causes. However, sepsis has not been examined as a possible cause. The aim of this study is to assess the influence of experimental sepsis on hearing thresholds and to evaluate pathological changes in the cochlea. The cecal ligation puncture technique was used to induce sepsis in 18 mice. Results were compared with those from 13 sham-operated and 13 untreated control mice. The hearing thresholds of the animals were evaluated with auditory evoked brainstem responses prior to the induction of sepsis and again at the peak of the disease. Immediately after the second measurement, the mice were sacrificed and the inner ears harvested and prepared for further evaluation. The cochleae were examined with light microscopy, electron microscopy and immunohistochemistry for Bax, cleaved caspase-3 and Bcl-2. The mice with sepsis showed a significant hearing loss but not the control groups. Induction of apoptosis could be shown in the supporting cells of the organ of Corti. Furthermore, excitotoxicity could be shown at the basal pole of the inner hair cells. In this murine model, sepsis leads to significant hearing impairment. The physiological alteration could be linked to apoptosis in the supporting cells of the organ of Corti and to a disturbance of the synapses of the inner hair cells.

  7. Lentiviral-mediated delivery of Bcl-2 or GDNF protects against excitotoxicity in the rat hippocampus.

    Science.gov (United States)

    Wong, Liang-Fong; Ralph, G Scott; Walmsley, Lucy E; Bienemann, Alison S; Parham, Stephen; Kingsman, Susan M; Uney, James B; Mazarakis, Nicholas D

    2005-01-01

    Nutrient deprivation during ischemia leads to severe insult to neurons causing widespread excitotoxic damage in specific brain regions such as the hippocampus. One possible strategy for preventing neurodegeneration is to express therapeutic proteins in the brain to protect against excitotoxicity. We investigated the utility of equine infectious anemia virus (EIAV)-based vectors as genetic tools for delivery of therapeutic proteins in an in vivo excitotoxicity model. The efficacy of these vectors at preventing cellular loss in target brain areas following excitotoxic insult was also assessed. EIAV vectors generated to overexpress the human antiapoptotic Bcl-2 or growth factor glial-derived neurotrophic factor (GDNF) genes protected against glutamate-induced toxicity in cultured hippocampal neurons. In an in vivo excitotoxicity model, adult Wistar rats received a unilateral dose of the glutamate receptor agonist N-methyl-D-aspartate to the hippocampus that induced a large lesion in the CA1 region. Neuronal loss could not be protected by prior transduction of a control vector expressing beta-galactosidase. In contrast, EIAV-mediated expression of Bcl-2 and GDNF significantly reduced lesion size thus protecting the hippocampus from excitotoxic damage. These results demonstrate that EIAV vectors can be effectively used to deliver putative neuroprotective genes to target brain areas and prevent cellular loss in the event of a neurological insult. Therefore these lentiviral vectors provide potential therapeutic tools for use in cases of acute neurotrauma such as cerebral ischemia. PMID:15585409

  8. Disrupted glutamate-glutamine cycle in acute encephalopathy with biphasic seizures and late reduced diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Takanashi, Jun-ichi; Terai, Masaru [Tokyo Women' s Medical University Yachiyo Medical Center, Department of Pediatrics, Yachiyo-shi (Japan); Mizuguchi, Masashi [The University of Tokyo, Department of Developmental Medical Sciences, Graduate School of Medicine, Tokyo (Japan); Barkovich, A.J. [University of California San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

    2015-11-15

    Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype of infectious pediatric encephalopathy in Japan. It is sometimes difficult to make an early diagnosis of AESD; excitotoxicity is postulated to be the pathogenesis based on elevated glutamine (Gln) and glutamate (Glu) complex (Glx = Glu + Gln) observed on MR spectroscopy. It is uncertain whether Gln or Glu contributes to the elevated Glx, or whether MR spectroscopy is useful for an early diagnosis. Five Japanese patients with AESD (three boys and two girls, 1 year of age) were enrolled in this study. MR spectroscopy was acquired from the frontal white matter (repetition time (TR) of 5000 ms, echo time (TE) of 30 ms) with a 1.5- or 3.0-T scanner. MR spectroscopy was performed four times for two patients, three times for one patient, and two times for two patients. Quantification of Glu and Gln was performed using LCModel. Glu was elevated in three of four studies on days 1-4 and became normal or low afterward. Gln was normal in three studies on days 1-2, elevated in all seven studies on days 4-12, and became normal or low afterward. These findings suggest that MR spectroscopy may be useful for an early diagnosis. Acute Glu elevation changes to subacute Gln elevation, suggesting that a disrupted Glu-Gln cycle may play an important role. (orig.)

  9. [Do the glutamate excitotoxicity theory and potential free radicals implication in schizophrenia aetiopathogenesis provide a new enlightenment to links between: genome, environment and biology in the determinism of that disorder?].

    Science.gov (United States)

    Nguimfack Mbodie, P C

    2002-01-01

    The aetiopathogenesis of schizophrenia constitutes nowadays one of the major points of interest for researchers on this cosmopolitan disorder which involves about 1% of the world population and which significantly alters the social functioning of the individual. Numerous studies have focused on the role played by genome, environmental factors and biology in the development of symptoms. The neurodevelopmental theory is an illustration with the perinatal period considered as the main provider of environmental factors (hypertension, infections, bleedings during pregnancy, acute and chronic fetal distress.). Many authors found significant associations between such factors, the occurrence of brain lesions and finally schizophrenic symptoms. Although no convincing genetic model had been established to date for schizophrenia, nevertheless it appears that a predisposition not inheritable under the mendelian mode exists and authors showed that disease gets more and more severe over schizophrenic descendants. The risk to be schizophrenic being a first degree relative of the schizophrenic person is about ten time superior than in general population. Indeed, this risk is also about ten time superior in biological parents of schizophrenic adoptees than in biological parents of healthy adoptees. Studies done in monozygotic comparing to dizygotic twins are in favour of an important role played by genetic factors more than socioeducational or psychological factors. Concerning biology, the dopaminergic hypothesis remains shared by numerous authors although direct links with incriminated factors are not well established. Now is suspected the glutamate excitotoxicity with implication of free radicals in schizophrenia. These free radicals are products of various enzymatic activations led by overstimulation of post synaptic receptors (NMDA and AMPA) by the excess glutamate. Therefore, according to that concept, some amino acids as glutamate and derivatives could have through free

  10. Protective Effect of Calendula officinalis L. Flowers Against Monosodium Glutamate Induced Oxidative Stress and Excitotoxic Brain Damage in Rats.

    Science.gov (United States)

    Shivasharan, B D; Nagakannan, P; Thippeswamy, B S; Veerapur, V P

    2013-07-01

    Monosodium glutamate (MSG) is a popular flavour enhancer used in food industries; however, excess MSG is neurotoxic. Oxidative stress is well documented in MSG induced neurotoxicity. The compounds having antioxidant and anti-inflammatory properties reportedly possess beneficial effects against various neurotoxic insults. Calendula officinalis Linn. flower extract (COE) is known for its potent antioxidant and anti-inflammatory activities. Hence, this present study has been designed to evaluate the neuroprotective effect of COE on MSG-induced neurotoxicity in rats. Adult Wistar rats were administered systemically for 7 days with MSG and after one h of MSG injection, rats were treated with COE (100 and 200 mg/kg) orally. At the end the treatment period, animals were assessed for locomotor activity and were sacrificed; brains were isolated for estimation of LPO, GSH, CAT, TT, GST, Nitrite and histopathological studies. MSG caused a significant alteration in animal behavior, oxidative defense (raised levels of LPO, nitrite concentration, depletion of antioxidant levels) and hippocampal neuronal histology. Treatment with COE significantly attenuated behavioral alterations, oxidative stress, and hippocampal damage in MSG-treated animals. Hence, this study demonstrates that COE protects against MSG-induced neurotoxicity in rats. The antioxidant and anti-inflammatory properties of COE may be responsible for its observed neuroprotective action. PMID:24426226

  11. EFFECTS OF GLUTAMATE ON SODIUM CHANNEL IN ACUTELY DISSOCIATED HIPPOCAMPAL CA1 PYRAMIDAL NEURONS OF RATS

    Institute of Scientific and Technical Information of China (English)

    高宾丽; 伍国锋; 杨艳; 刘智飞; 曾晓荣

    2011-01-01

    Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibitio...

  12. Acute liver failure in rats activates glutamine-glutamate cycle but declines antioxidant enzymes to induce oxidative stress in cerebral cortex and cerebellum.

    Directory of Open Access Journals (Sweden)

    Santosh Singh

    Full Text Available BACKGROUND AND PURPOSE: Liver dysfunction led hyperammonemia (HA causes a nervous system disorder; hepatic encephalopathy (HE. In the brain, ammonia induced glutamate-excitotoxicity and oxidative stress are considered to play important roles in the pathogenesis of HE. The brain ammonia metabolism and antioxidant enzymes constitute the main components of this mechanism; however, need to be defined in a suitable animal model. This study was aimed to examine this aspect in the rats with acute liver failure (ALF. METHODS: ALF in the rats was induced by intraperitoneal administration of 300 mg thioacetamide/Kg. b.w up to 2 days. Glutamine synthetase (GS and glutaminase (GA, the two brain ammonia metabolizing enzymes vis a vis ammonia and glutamate levels and profiles of all the antioxidant enzymes vis a vis oxidative stress markers were measured in the cerebral cortex and cerebellum of the control and the ALF rats. RESULTS: The ALF rats showed significantly increased levels of ammonia in the blood (HA but little changes in the cortex and cerebellum. This was consistent with the activation of the GS-GA cycle and static levels of glutamate in these brain regions. However, significantly increased levels of lipid peroxidation and protein carbonyl contents were consistent with the reduced levels of all the antioxidant enzymes in both the brain regions of these ALF rats. CONCLUSION: ALF activates the GS-GA cycle to metabolize excess ammonia and thereby, maintains static levels of ammonia and glutamate in the cerebral cortex and cerebellum. Moreover, ALF induces oxidative stress by reducing the levels of all the antioxidant enzymes which is likely to play important role, independent of glutamate levels, in the pathogenesis of acute HE.

  13. Water extract from the leaves of Withania somnifera protect RA differentiated C6 and IMR-32 cells against glutamate-induced excitotoxicity.

    Directory of Open Access Journals (Sweden)

    Hardeep Kataria

    Full Text Available Glutamate neurotoxicity has been implicated in stroke, head trauma, multiple sclerosis and neurodegenerative disorders. Search for herbal remedies that may possibly act as therapeutic agents is an active area of research to combat these diseases. The present study was designed to investigate the neuroprotective role of Withania somnifera (Ashwagandha, also known as Indian ginseng, against glutamate induced toxicity in the retinoic acid differentiated rat glioma (C6 and human neuroblastoma (IMR-32 cells. The neuroprotective activity of the Ashwagandha leaves derived water extract (ASH-WEX was evaluated. Cell viability and the expression of glial and neuronal cell differentiation markers was examined in glutamate challenged differentiated cells with and without the presence of ASH-WEX. We demonstrate that RA-differentiated C6 and IMR-32 cells, when exposed to glutamate, undergo loss of neural network and cell death that was accompanied by increase in the stress protein HSP70. ASH-WEX pre-treatment inhibited glutamate-induced cell death and was able to revert glutamate-induced changes in HSP70 to a large extent. Furthermore, the analysis on the neuronal plasticity marker NCAM (Neural cell adhesion molecule and its polysialylated form, PSA-NCAM revealed that ASH-WEX has therapeutic potential for prevention of neurodegeneration associated with glutamate-induced excitotoxicty.

  14. 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.

  15. A beacon of hope in stroke therapy-Blockade of pathologically activated cellular events in excitotoxic neuronal death as potential neuroprotective strategies.

    Science.gov (United States)

    Hoque, Ashfaqul; Hossain, M Iqbal; Ameen, S Sadia; Ang, Ching-Seng; Williamson, Nicholas; Ng, Dominic C H; Chueh, Anderly C; Roulston, Carli; Cheng, Heung-Chin

    2016-04-01

    Excitotoxicity, a pathological process caused by over-stimulation of ionotropic glutamate receptors, is a major cause of neuronal loss in acute and chronic neurological conditions such as ischaemic stroke, Alzheimer's and Huntington's diseases. Effective neuroprotective drugs to reduce excitotoxic neuronal loss in patients suffering from these neurological conditions are urgently needed. One avenue to achieve this goal is to clearly define the intracellular events mediating the neurotoxic signals originating from the over-stimulated glutamate receptors in neurons. In this review, we first focus on the key cellular events directing neuronal death but not involved in normal physiological processes in the neurotoxic signalling pathways. These events, referred to as pathologically activated events, are potential targets for the development of neuroprotectant therapeutics. Inhibitors blocking some of the known pathologically activated cellular events have been proven to be effective in reducing stroke-induced brain damage in animal models. Notable examples are inhibitors suppressing the ion channel activity of neurotoxic glutamate receptors and those disrupting interactions of specific cellular proteins occurring only in neurons undergoing excitotoxic cell death. Among them, Tat-NR2B9c and memantine are clinically effective in reducing brain damage caused by some acute and chronic neurological conditions. Our second focus is evaluation of the suitability of the other inhibitors for use as neuroprotective therapeutics. We also discuss the experimental approaches suitable for bridging our knowledge gap in our current understanding of the excitotoxic signalling mechanism in neurons and discovery of new pathologically activated cellular events as potential targets for neuroprotection.

  16. 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...

  17. Relationship between plasma glutamate levels and post-stroke depression in patients with acute ischemic stroke

    Institute of Scientific and Technical Information of China (English)

    钱方媛

    2014-01-01

    Objective To test the association between the plasma glutamate levels during acute ischemic stroke andpost-stroke depression(PSD)initially.Methods Seventy-four ischemic stroke patients admitted to the hospital within the first day of stroke onset were evaluated at a follow-up of 2 weeks.The Beck Depression Inventory(BDI,21-item)and DSM-Ⅳcriteria was used to diagnose post-stroke depression(PSD)at 2 weeks after stroke.

  18. PEER REVIEW (L-Glutamate profile in Acute Ischemic Stroke after Intra Arterial Heparin Flushing )

    OpenAIRE

    Islam, Andi Asadul

    2016-01-01

    - PEER REVIEW Judul karya Ilmiah (artikel): L-Glutamate profile in Acute Ischemic Stroke after Intra Arterial Heparin Flushing 5 Orang Penulis Kelima a. Nama Jurnal : Bali Medical Journal b. Nomor ISSN : P: 2089-1180, E: 2302-2914 c. Volume,nomor, bulan, tahun : Volume 5, No. 3 Tahun 2016 d. Penerbit : Bali Med J e. DOI artikel (Jika ada) : f. Alamat web Jurnal : www.balimedicaljournal.org, www.ojs.unud.ac.id g. Terindeks di Scimagojr/

  19. A beacon of hope in stroke therapy-Blockade of pathologically activated cellular events in excitotoxic neuronal death as potential neuroprotective strategies.

    Science.gov (United States)

    Hoque, Ashfaqul; Hossain, M Iqbal; Ameen, S Sadia; Ang, Ching-Seng; Williamson, Nicholas; Ng, Dominic C H; Chueh, Anderly C; Roulston, Carli; Cheng, Heung-Chin

    2016-04-01

    Excitotoxicity, a pathological process caused by over-stimulation of ionotropic glutamate receptors, is a major cause of neuronal loss in acute and chronic neurological conditions such as ischaemic stroke, Alzheimer's and Huntington's diseases. Effective neuroprotective drugs to reduce excitotoxic neuronal loss in patients suffering from these neurological conditions are urgently needed. One avenue to achieve this goal is to clearly define the intracellular events mediating the neurotoxic signals originating from the over-stimulated glutamate receptors in neurons. In this review, we first focus on the key cellular events directing neuronal death but not involved in normal physiological processes in the neurotoxic signalling pathways. These events, referred to as pathologically activated events, are potential targets for the development of neuroprotectant therapeutics. Inhibitors blocking some of the known pathologically activated cellular events have been proven to be effective in reducing stroke-induced brain damage in animal models. Notable examples are inhibitors suppressing the ion channel activity of neurotoxic glutamate receptors and those disrupting interactions of specific cellular proteins occurring only in neurons undergoing excitotoxic cell death. Among them, Tat-NR2B9c and memantine are clinically effective in reducing brain damage caused by some acute and chronic neurological conditions. Our second focus is evaluation of the suitability of the other inhibitors for use as neuroprotective therapeutics. We also discuss the experimental approaches suitable for bridging our knowledge gap in our current understanding of the excitotoxic signalling mechanism in neurons and discovery of new pathologically activated cellular events as potential targets for neuroprotection. PMID:26899498

  20. Molecular mechanisms of excitotoxicity and their relevance to pathogenesis of neurodegenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Xiao-xia DONG; Yan WANG; Zheng-hong QIN

    2009-01-01

    A pivotal role for excitotoxicity in neurodegenerative diseases is gaining increasingly more acceptance, but the underlying mechanisms through which it participates in neurodegeneration still need further investigation. Excessive activation of glutamate receptors by excitatory amino acids leads to a number of deleterious consequences, including impairment of calcium buffering, generation of free radicals, activation of the mitochondrial permeability transition and secondary excitotoxicity. Recent studies implicate excitotoxicity in a variety of neuropathological conditions, suggesting that neurodegenerative diseases with distinct genetic etiologies may share excitotoxicity as a common pathogenic pathway. Thus, understanding the pathways involved in excitotoxicity is of critical importance for the future clinical treatment of many neurodegenerafive diseases. This review discusses the current understanding of excitotoxic mechanisms and how they are involved in the pathogenesis of neurodegenerative diseases.

  1. Pregabalin attenuates excitotoxicity in diabetes.

    Directory of Open Access Journals (Sweden)

    Chin-Wei Huang

    Full Text Available Diabetes can exacerbate seizures and worsen seizure-related brain damage. In the present study, we aimed to determine whether the standard antiepileptic drug pregabalin (PGB protects against pilocarpine-induced seizures and excitotoxicity in diabetes. Adult male Sprague-Dawley rats were divided into either a streptozotocin (STZ-induced diabetes group or a normal saline (NS group. Both groups were further divided into subgroups that were treated intravenously with either PGB (15 mg/kg or a vehicle; all groups were treated with subcutaneous pilocarpine (60 mg/kg to induce seizures. To evaluate spontaneous recurrent seizures (SRS, PGB-pretreated rats were fed rat chow containing oral PGB (450 mg for 28 consecutive days; vehicle-pretreated rats were fed regular chow. SRS frequency was monitored for 2 weeks from post-status epilepticus day 15. We evaluated both acute neuronal loss and chronic mossy fiber sprouting in the CA3 area. In addition, we performed patch clamp recordings to study evoked excitatory postsynaptic currents (eEPSCs in hippocampal CA1 neurons for both vehicle-treated rats with SRS. Finally, we used an RNA interference knockdown method for Kir6.2 in a hippocampal cell line to evaluate PGB's effects in the presence of high-dose ATP. We found that compared to vehicle-treated rats, PGB-treated rats showed less severe acute seizure activity, reduced acute neuronal loss, and chronic mossy fiber sprouting. In the vehicle-treated STZ rats, eEPSC amplitude was significantly lower after PGB administration, but glibenclamide reversed this effect. The RNA interference study confirmed that PGB could counteract the ATP-sensitive potassium channel (KATP-closing effect of high-dose ATP. By opening KATP, PGB protects against neuronal excitotoxicity, and is therefore a potential antiepileptogenic in diabetes. These findings might help develop a clinical algorithm for treating patients with epilepsy and comorbid metabolic disorders.

  2. Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants.

    Directory of Open Access Journals (Sweden)

    Laura Musazzi

    Full Text Available BACKGROUND: Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release. METHODOLOGY/FINDINGS: Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated, and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486. On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats. Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability. CONCLUSIONS/SIGNIFICANCE: Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes

  3. Repair Following Glutamate-induced Excitotoxic Neuronal Damage Mediated by Intracerebroventricular Injection of Cell-free Filtrate of Neural Stem Cell Lysates in Adult Mice%小鼠脑室内注射神经干细胞裂解液促进谷氨酸盐诱导的兴奋性神经元损伤的修复

    Institute of Scientific and Technical Information of China (English)

    于立坚; 马娟; 马润娣; 张永平; 房娟芝; 张霄瑜; 于廷曦

    2011-01-01

    Our previous study demonstrated that cell-free filtrate of sodium ferulate-induced and differen-tioned PC 12 cell lysates significantly attenuated chronic mild stress-induced depression-like behavioural disorders, up-regulated hippocampal and cerebral cortex expressions of nerve growth factor (NGF) and brain-derived neu-rotrophic factor (BDNF), and increased hippocampal number of neural stem cells (NSC)/neural progenitor cells in mice. The present study was undertaken to investigate the possibility of the repair following glutamate (monosodium glutamate, MSG)-induced excitotoxic brain injury mediated by intracerebroventricular injection of cell-free filtrate of neural stem cell lysates (FNSCL) in adult mice. Mouse NSCs were isolated from the brains of embryos at 15 day postcoitum (dpc). The expression of nestin, a special antigen for NSC, was detected by immunocytochemistry. Cell-free filtrate of NSCs was prepared from the NSC lysates. The animals in the MSG group received intragastric (ig) administration of MSG (2.0 g/(kgd) for 10 days), the animals in the MSG+NSCs group received intracerebroventricular transplantation of NSCs (approximately l.OxlO5 cells), and the animals in the MSG+FNSCL group received intracerebroventricular injection of 10 \\iL of FNSCL (approximately 1.0* 105 cells) separately on day 1 and day 10 after 10-d MSG exposure. The mice in control and MSG groups received intracerebroventricular injection of Dul-becco's modified Eagle's medium (DMEM) instead of NSCs or FNSCL. On 12 day after the last intracerebroventricular injection of FNSCL or transplantation of NSCs, Y-maze test was performed, and then the histopathology of animal brains was studied to analyze MSG-induced functional and morphological changes and the effects of intracerebroventricular injection of FNSCL and transplantation of NSCs on the repair of MSG-induced excitotoxic brain injury. The results showed that both intracerebroventricular injection of FNSCL and

  4. Glucose metabolism and glutamate analog acutely alkalinize pH of insulin secretory vesicles of pancreatic beta-cells.

    Science.gov (United States)

    Eto, Kazuhiro; Yamashita, Tokuyuki; Hirose, Kenzo; Tsubamoto, Yoshiharu; Ainscow, Edward K; Rutter, Guy A; Kimura, Satoshi; Noda, Mitsuhiko; Iino, Masamitsu; Kadowaki, Takashi

    2003-08-01

    We studied acute changes of secretory vesicle pH in pancreatic beta-cells with a fluorescent pH indicator, lysosensor green DND-189. Fluorescence was decreased by 0.66 +/- 0.10% at 149 +/- 16 s with 22.2 mM glucose stimulation, indicating that vesicular pH was alkalinized by approximately 0.016 unit. Glucose-responsive pH increase was observed when cytosolic Ca2+ influx was blocked but disappeared when an inhibitor of glycolysis or mitochondrial ATP synthase was present. Glutamate dimethyl ester (GME), a plasma membrane-permeable analog of glutamate, potentiated glucose-stimulated insulin secretion at 5 mM without changing cellular ATP content or cytosolic Ca2+ concentration ([Ca2+]). Application of GME at basal glucose concentration decreased DND-189 fluorescence by 0.83 +/- 0.19% at 38 +/- 2 s. These results indicated that the acutely alkalinizing effect of glucose on beta-cell secretory vesicle pH was dependent on glucose metabolism but independent of modulations of cytosolic [Ca2+]. Moreover, glutamate derived from glucose may be one of the mediators of this alkalinizing effect of glucose, which may have potential relevance to the alteration of secretory function by glutamate.

  5. Ionotropic glutamate receptor expression in human white matter.

    Science.gov (United States)

    Christensen, Pia Crone; Samadi-Bahrami, Zahra; Pavlov, Vlady; Stys, Peter K; Moore, G R Wayne

    2016-09-01

    Glutamate is the key excitatory neurotransmitter of the central nervous system (CNS). Its role in human grey matter transmission is well understood, but this is less clear in white matter (WM). Ionotropic glutamate receptors (iGluR) are found on both neuronal cell bodies and glia as well as on myelinated axons in rodents, and rodent WM tissue is capable of glutamate release. Thus, rodent WM expresses many of the components of the traditional grey matter neuron-to-neuron synapse, but to date this has not been shown for human WM. We demonstrate the presence of iGluRs in human WM by immunofluorescence employing high-resolution spectral confocal imaging. We found that the obligatory N-methyl-d-aspartic acid (NMDA) receptor subunit GluN1 and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA4 co-localized with myelin, oligodendroglial cell bodies and processes. Additionally, GluA4 colocalized with axons, often in distinct clusters. These findings may explain why human WM is vulnerable to excitotoxic events following acute insults such as stroke and traumatic brain injury and in more chronic inflammatory conditions such as multiple sclerosis (MS). Further exploration of human WM glutamate signalling could pave the way for developing future therapies modulating the glutamate-mediated damage in these and other CNS disorders. PMID:27443784

  6. Excitotoxic effects of non-NMDA receptor agonists in organotypic corticostriatal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, B W; Noraberg, J; Jakobsen, B;

    1999-01-01

    The excitotoxic effects of the glutamate receptor agonists kainic acid (KA) and 2-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and the corresponding neuroprotective effects of the AMPA/KA receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX) were examined...

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

    Science.gov (United States)

    Lane, Darius J R; Lawen, Alfons

    2013-03-01

    Vitamin C (ascorbate) plays important neuroprotective and neuromodulatory roles in the mammalian brain. Astrocytes are crucially involved in brain ascorbate homeostasis and may assist in regenerating extracellular ascorbate from its oxidised forms. Ascorbate accumulated by astrocytes can be released rapidly by a process that is stimulated by the excitatory amino acid, L-glutamate. This process is thought to be neuroprotective against excitotoxicity. Although of potential clinical interest, the mechanism of this stimulated ascorbate-release remains unknown. Here, we report that primary cultures of mouse and rat astrocytes release ascorbate following initial uptake of dehydroascorbate and accumulation of intracellular ascorbate. Ascorbate-release was not due to cellular lysis, as assessed by cellular release of the cytosolic enzyme lactate dehydrogenase, and was stimulated by L-glutamate and L-aspartate, but not the non-excitatory amino acid L-glutamine. This stimulation was due to glutamate-induced cellular swelling, as it was both attenuated by hypertonic and emulated by hypotonic media. Glutamate-stimulated ascorbate-release was also sensitive to inhibitors of volume-sensitive anion channels, suggesting that the latter may provide the conduit for ascorbate efflux. Glutamate-stimulated ascorbate-release was not recapitulated by selective agonists of either ionotropic or group I metabotropic glutamate receptors, but was completely blocked by either of two compounds, TFB-TBOA and UCPH-101, which non-selectively and selectively inhibit the glial Na(+)-dependent excitatory amino acid transporter, GLAST, respectively. These results suggest that an impairment of astrocytic ascorbate-release may exacerbate neuronal dysfunction in neurodegenerative disorders and acute brain injury in which excitotoxicity and/or GLAST deregulation have been implicated. PMID:22886112

  8. Bacterial cytolysin during meningitis disrupts the regulation of glutamate in the brain, leading to synaptic damage.

    Directory of Open Access Journals (Sweden)

    Carolin Wippel

    Full Text Available Streptococcus pneumoniae (pneumococcal meningitis is a common bacterial infection of the brain. The cholesterol-dependent cytolysin pneumolysin represents a key factor, determining the neuropathogenic potential of the pneumococci. Here, we demonstrate selective synaptic loss within the superficial layers of the frontal neocortex of post-mortem brain samples from individuals with pneumococcal meningitis. A similar effect was observed in mice with pneumococcal meningitis only when the bacteria expressed the pore-forming cholesterol-dependent cytolysin pneumolysin. Exposure of acute mouse brain slices to only pore-competent pneumolysin at disease-relevant, non-lytic concentrations caused permanent dendritic swelling, dendritic spine elimination and synaptic loss. The NMDA glutamate receptor antagonists MK801 and D-AP5 reduced this pathology. Pneumolysin increased glutamate levels within the mouse brain slices. In mouse astrocytes, pneumolysin initiated the release of glutamate in a calcium-dependent manner. We propose that pneumolysin plays a significant synapto- and dendritotoxic role in pneumococcal meningitis by initiating glutamate release from astrocytes, leading to subsequent glutamate-dependent synaptic damage. We outline for the first time the occurrence of synaptic pathology in pneumococcal meningitis and demonstrate that a bacterial cytolysin can dysregulate the control of glutamate in the brain, inducing excitotoxic damage.

  9. Kainic Acid-Induced Excitotoxicity Experimental Model: Protective Merits of Natural Products and Plant Extracts

    Directory of Open Access Journals (Sweden)

    Nur Shafika Mohd Sairazi

    2015-01-01

    Full Text Available Excitotoxicity is well recognized as a major pathological process of neuronal death in neurodegenerative diseases involving the central nervous system (CNS. In the animal models of neurodegeneration, excitotoxicity is commonly induced experimentally by chemical convulsants, particularly kainic acid (KA. KA-induced excitotoxicity in rodent models has been shown to result in seizures, behavioral changes, oxidative stress, glial activation, inflammatory mediator production, endoplasmic reticulum stress, mitochondrial dysfunction, and selective neurodegeneration in the brain upon KA administration. Recently, there is an emerging trend to search for natural sources to combat against excitotoxicity-associated neurodegenerative diseases. Natural products and plant extracts had attracted a considerable amount of attention because of their reported beneficial effects on the CNS, particularly their neuroprotective effect against excitotoxicity. They provide significant reduction and/or protection against the development and progression of acute and chronic neurodegeneration. This indicates that natural products and plants extracts may be useful in protecting against excitotoxicity-associated neurodegeneration. Thus, targeting of multiple pathways simultaneously may be the strategy to maximize the neuroprotection effect. This review summarizes the mechanisms involved in KA-induced excitotoxicity and attempts to collate the various researches related to the protective effect of natural products and plant extracts in the KA model of neurodegeneration.

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

    Directory of Open Access Journals (Sweden)

    Walailuk Kerdsan

    2009-01-01

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

  11. 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.

  12. The Role of Presenilin-1 in the Excitotoxicity of Ethanol Withdrawal.

    Science.gov (United States)

    Jung, Marianna E; Metzger, Daniel B; Das, Hriday K

    2016-09-01

    Presenilin-1 (PS1) is a core component of γ-secretase that is involved in neurodegeneration. We have previously shown that PS1 interacts with a mitogen-activated protein kinase [(MAPK) jun-NH2-terminal-kinase], and another MAPK (p38) is activated by ethanol withdrawal (EW), abrupt termination from chronic ethanol exposure. EW is excitotoxic in nature, induces glutamate upregulation, and provokes neuronal damage. Here, we explored a potential mechanistic pathway involving glutamate, p38 (p38α isozyme), and PS1 that may mediate EW-induced excitotoxic stress. We used the prefrontal cortex of male rats withdrawn from a chronic ethanol diet. Additionally, we used ethanol-withdrawn HT22 cells (mouse hippocampal) treated with the inhibitor of glutamate receptors [dizocilpine (MK-801)], p38α (SB203580; 4-[4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-1H-imidazol-5-yl]pyridine), or γ-secretase [N-[N- (3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT)] during EW. Separately, ethanol-free HT22 cells were exposed to glutamate with or without SB203580 or DAPT. Protein levels, mRNA levels, and cell viability were assessed using immunoblotting, qualitative polymerase chain reaction, and calcein assay, respectively. The prefrontal cortex of ethanol-withdrawn rats or HT22 cells showed an increase in PS1 and p38α, which was attenuated by MK-801 and SB203580, but mimicked by glutamate treatment to ethanol-free HT22 cells. DAPT attenuated the toxic effect of EW or glutamate on HT22 cells. These results suggest that PS1 expression is triggered by glutamate through p38α, contributing to the excitotoxic stimulus of EW. PMID:27278235

  13. The Role of Canonical Transient Receptor Potential Channels in Seizure and Excitotoxicity

    Directory of Open Access Journals (Sweden)

    Fang Zheng

    2014-04-01

    Full Text Available Canonical transient receptor potential (TRPC channels are a family of polymodal cation channels with some degree of Ca2+ permeability. Although initially thought to be channels mediating store-operated Ca2+ influx, TRPC channels can be activated by stimulation of Gq-coupled G-protein coupled receptors, or by an increase in intracellular free Ca2+ concentration. Thus, activation of TRPC channels could be a common downstream event of many signaling pathways that contribute to seizure and excitotoxicity, such as N-methyl-D-aspartate (NMDA receptor-mediated Ca2+ influx, or metabotropic glutamate receptor activation. Recent studies with genetic ablation of various TRPC family members have demonstrated that TRPC channels, in particular heteromeric TRPC1/4 channels and homomeric TRPC5 channels, play a critical role in both pilocarpine-induced acute seizures and neuronal cell death. However, exact underlying mechanisms remain to be fully elucidated, and selective TRPC modulators and antibodies with better specificity are urgently needed for future research.

  14. Blood Glutamate Scavenging: Insight into Neuroprotection

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    Alexander Zlotnik

    2012-08-01

    Full Text Available Brain insults are characterized by a multitude of complex processes, of which glutamate release plays a major role. Deleterious excess of glutamate in the brain’s extracellular fluids stimulates glutamate receptors, which in turn lead to cell swelling, apoptosis, and neuronal death. These exacerbate neurological outcome. Approaches aimed at antagonizing the astrocytic and glial glutamate receptors have failed to demonstrate clinical benefit. Alternatively, eliminating excess glutamate from brain interstitial fluids by making use of the naturally occurring brain-to-blood glutamate efflux has been shown to be effective in various animal studies. This is facilitated by gradient driven transport across brain capillary endothelial glutamate transporters. Blood glutamate scavengers enhance this naturally occurring mechanism by reducing the blood glutamate concentration, thus increasing the rate at which excess glutamate is cleared. Blood glutamate scavenging is achieved by several mechanisms including: catalyzation of the enzymatic process involved in glutamate metabolism, redistribution of glutamate into tissue, and acute stress response. Regardless of the mechanism involved, decreased blood glutamate concentration is associated with improved neurological outcome. This review focuses on the physiological, mechanistic and clinical roles of blood glutamate scavenging, particularly in the context of acute and chronic CNS injury. We discuss the details of brain-to-blood glutamate efflux, auto-regulation mechanisms of blood glutamate, natural and exogenous blood glutamate scavenging systems, and redistribution of glutamate. We then propose different applied methodologies to reduce blood and brain glutamate concentrations and discuss the neuroprotective role of blood glutamate scavenging.

  15. Are human neurodegenerative disorders linked to environmental chemicals with excitotoxic properties

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, P.S.; Ludolph, A.C.; Kisby, G.E. (Center for Research on Occupational and Environmental Toxicology, Oregon Health Sciences University, Portland (United States))

    1992-05-11

    At the present time, it seems unlikely that progressive neurodegenerative diseases, such as ALS, Parkinson's disease, and dementia of the Alzheimer type, are triggered by environmental agents with excitotoxic potential. These include excitotoxic agents that behave as glutamate agonists or disrupt energy metabolism: both types elicit permanent but self-limiting neuronal diseases with patterns of neuronal deficit that reflect selective chemical exposure (MPP+ and parkinsonism), differential susceptibility to energy dysmetabolism (NPA and dystonia), or the distribution of glutamate-receptors (domoic acid and memory loss). If environmental agents play an etiologic role in progressive neurodegenerative diseases, they are likely to target a critical, irreplaceable neuronal molecule that is required to maintain long-term neuronal integrity.41 references.

  16. Comparison of accuracy of sup(99m)Tc-pyridoxylidene glutamate scanning with oral cholecystography and ultrasonography in diagnosis of acute cholecystitis

    International Nuclear Information System (INIS)

    A prospective study of 116 patients admitted as emergencies with a clinical diagnosis of acute cholecystitis or biliary colic showed that the best investigation for confirming a diagnosis of acute cholecystitis was sup(99m)Tc-pyridoxylidene1 glutamate (PG) scanning. Its sensitivity was 99% and its specificity 86%, whereas those of oral cholecystography were 75% and 82% respectively, and those of ultrasonography were 54% and 62%, respectively. However, estimation of plasma liver enzymes was essential to exclude acute hepatitis before proceeding to early cholecystectomy. (author)

  17. Effect of glutamate on lysosomal membrane permeabilization in primary cultured cortical neurons

    OpenAIRE

    Yan, Min; Zhu, Wenbo; Zheng, Xiaoke; Li, Yuan; TANG, LIPENG; LU, BINGZHENG; Chen, WenLi; Qiu, Pengxin; Leng, Tiandong; Lin, Suizhen; Yan, Guangmei; Yin, Wei

    2016-01-01

    Glutamate is the principal neurotransmitter in the central nervous system. Glutamate-mediated excitotoxicity is the predominant cause of cerebral damage. Recent studies have shown that lysosomal membrane permeabilization (LMP) is involved in ischemia-associated neuronal death in non-human primates. This study was designed to investigate the effect of glutamate on lysosomal stability in primary cultured cortical neurons. Glutamate treatment for 30 min induced the permeabilization of lysosomal ...

  18. Effects of administered sodium ferulate on the repair of glutamate-induced excitotoxic neuronal impair meat in mouse fetal brain%阿魏酸钠对妊娠晚期母小鼠谷氨酸单钠灌胃诱导的仔鼠兴奋性毒性神经损伤的修复作用

    Institute of Scientific and Technical Information of China (English)

    张永平; 于立坚; 马润娣; 张霄瑜; 于廷曦

    2008-01-01

    Objective To investigate the effects of administered sodium ferulate (SF) on the repair of glutamate-induced excitotoxic neuronal impairment in mouse fetal brain.Methods Pregnant females were randomly divided into control,SF,MSG,and MSG + SF groups,n=10.The animals in MSG group received ig administration of monosodium glutamate (MSG,1.0,2.0,4.0g/kg,onee) at 17-day.The animals in MSG + SF and SF groups received ig administration of MSG (4.0g/kg,once) or normal saline at 17day,and ip administration of SF (40 mg/kg) starting at 18 dpo,once-daily for 2~3 d;the infant mice from the mothers treated with MSG +SF received ip administration of SF (40 mg/kg) after the birth,once-daily for 20 days.The animals in control and MSG groups received ig or ip administration of normal saline simultaneously,respectively.At the 31 st day after the birth the behavioural tests were performed,and the histopathology of the animal brains was studied.Results At the 31 st day after the birth,the number of MSG-treated mice which could crawl along a rope (5/13) was obviously less than that of control(12/14) (P<0.01) ;at the 52th day after the birth,correct responses of MSG-treated group in Ymaze test (17.1/20) were significantly less than that of control (19.4/20)(P<0.01).Examination of histopathology displayed MSG-induced hippocampal lesions were characterized by intracellular edema,degeneration and necrosis of neurons,and hyperplasia.However,the number of MSG+ SF-treated mice which could crawl along a rope (10/13) was close to that of control (12/14);at the 52th day after the birth,correct responses of Y-maze test in the MSG + SF group (19.1/20) were close those in the control (19.4/20).Examination of histopathology displayed that slight hippocampal lesions appeared in the MSG + SF-treated mice.Conclusion Long-term administration of SF may be feasible in repairing glutamate-induced exeitotoxic neuronal impairment in infant mice.%目的 研究阿魏酸钠(SF)腹腔注射对妊娠晚期母

  19. A comparative study of serum histaminase and serum glutamic oxaloacetic transaminase in acute myocardial infarction

    Directory of Open Access Journals (Sweden)

    Gupta S

    1979-01-01

    Full Text Available Serum histaminase and SGOT were estimated in 35 cases of acute myocardial infarction and 34 cases of ischaemic heart disease (Other than acute myocardial infarction and 30, age and sex match-ed, healthy subjects which served as controls, to evaluate the com-parison of time relation activity, diagnostic and prognostic value of histaminase and SGOT. The enzymes were estimated within 6 hours, then repeated -within 24 hours, 2nd day, 3rd day, 5th day, 10th day and 15th day, ascertained from the time o f pain in the chest. Raised histaminase levels were found in 97.14%; cases, while SGOT levels were found elevated in only 91.4% cases of acute myo-cardial infarction of which 30 were electrocardiographically proved and 5 had equivocal electrocardiographic evidence of acute infarc-tion like LBBB, complete heart block, ventricular tachycardia and old myocardial infarction. Furthermore elevation of histaminase was 6.2 times whereas of SGOT only 5.2 times above the mean normal value. Serum histaminase was found elevated in all the 6 cases who presented within 6 hours of infarction, while SGOT did not rise in any of these cases. Both histaminase and SGOT reached the peak levels on the 2nd day and persisted for whole of the first week. Higher levels of these enzymes were found associated with worse prognosis. Above observations show that the serum histaminase rises earlier than SGOT and can prove the diagnosis of myocardial infarction even when SGOT and ECG fail to reveal the diagnosis. It is a more sensitive index and has higher peak rise of levels than SGOT. How-ever its pattern of rise, fall and prognostic values are similar to that of SGOT.

  20. Glutamate Efflux at the Blood-Brain Barrier

    DEFF Research Database (Denmark)

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

    2014-01-01

    L-Glutamate is considered the most important excitatory amino acid in the mammalian brain. Strict control of its concentration in the brain interstitial fluid is important to maintain neurotransmission and avoid excitotoxicity. The role of astrocytes in handling L-glutamate transport and metabolism...... is well known, however endothelial cells may also play an important role through mediating brain-to-blood L-glutamate efflux. Expression of excitatory amino acid transporters has been demonstrated in brain endothelial cells of bovine, human, murine, rat and porcine origin. These can account for high......-glutamate, metabolism of L-glutamate and transport of metabolites or a combination of the two. However, both in vitro and in vivo studies have demonstrated blood-to-brain transport of L-glutamate, at least during pathological events. This review summarizes the current knowledge on the brain-to-blood L-glutamate efflux...

  1. Protective effect of parvalbumin on excitotoxic motor neuron death

    DEFF Research Database (Denmark)

    Van den Bosch, L.; Schwaller, B.; Vleminckx, V.;

    2002-01-01

    Amyotrophic lateral sclerosis, ALS, AMPA receptor, calcium-binding proteins, calcium buffering, excitotoxity, kainic acid, motor neuron, parvalbumin......Amyotrophic lateral sclerosis, ALS, AMPA receptor, calcium-binding proteins, calcium buffering, excitotoxity, kainic acid, motor neuron, parvalbumin...

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

    Directory of Open Access Journals (Sweden)

    Xu Xiao-Hui

    2015-01-01

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

  3. Magnesium sulfate protects against the bioenergetic consequences of chronic glutamate receptor stimulation.

    Directory of Open Access Journals (Sweden)

    Pascaline Clerc

    Full Text Available Extracellular glutamate is elevated following brain ischemia or trauma and contributes to neuronal injury. We tested the hypothesis that magnesium sulfate (MgSO4, 3 mM protects against metabolic failure caused by excitotoxic glutamate exposure. Rat cortical neuron preparations treated in medium already containing a physiological concentration of Mg(2+ (1 mM could be segregated based on their response to glutamate (100 µM. Type I preparations responded with a decrease or small transient increase in oxygen consumption rate (OCR. Type II neurons responded with >50% stimulation in OCR, indicating a robust response to increased energy demand without immediate toxicity. Pre-treatment with MgSO4 improved the initial bioenergetic response to glutamate and ameliorated subsequent loss of spare respiratory capacity, measured following addition of the uncoupler FCCP, in Type I but not Type II neurons. Spare respiratory capacity in Type I neurons was also improved by incubation with MgSO4 or NMDA receptor antagonist MK801 in the absence of glutamate treatment. This finding indicates that the major difference between Type I and Type II preparations is the amount of endogenous glutamate receptor activity. Incubation of Type II neurons with 5 µM glutamate prior to excitotoxic (100 µM glutamate exposure recapitulated a Type I phenotype. MgSO4 protected against an excitotoxic glutamate-induced drop in neuronal ATP both with and without prior 5 µM glutamate exposure. Results indicate that MgSO4 protects against chronic moderate glutamate receptor stimulation and preserves cellular ATP following treatment with excitotoxic glutamate.

  4. Magnesium Sulfate Protects Against the Bioenergetic Consequences of Chronic Glutamate Receptor Stimulation

    OpenAIRE

    Pascaline Clerc; Young, Christina A.; Evan A Bordt; Grigore, Alina M.; Gary Fiskum; Polster, Brian M.

    2013-01-01

    Extracellular glutamate is elevated following brain ischemia or trauma and contributes to neuronal injury. We tested the hypothesis that magnesium sulfate (MgSO4, 3 mM) protects against metabolic failure caused by excitotoxic glutamate exposure. Rat cortical neuron preparations treated in medium already containing a physiological concentration of Mg(2+) (1 mM) could be segregated based on their response to glutamate (100 µM). Type I preparations responded with a decrease or small transient in...

  5. Magnesium Sulfate Protects Against the Bioenergetic Consequences of Chronic Glutamate Receptor Stimulation

    Science.gov (United States)

    Clerc, Pascaline; Young, Christina A.; Bordt, Evan A.; Grigore, Alina M.; Fiskum, Gary; Polster, Brian M.

    2013-01-01

    Extracellular glutamate is elevated following brain ischemia or trauma and contributes to neuronal injury. We tested the hypothesis that magnesium sulfate (MgSO4, 3 mM) protects against metabolic failure caused by excitotoxic glutamate exposure. Rat cortical neuron preparations treated in medium already containing a physiological concentration of Mg2+ (1 mM) could be segregated based on their response to glutamate (100 µM). Type I preparations responded with a decrease or small transient increase in oxygen consumption rate (OCR). Type II neurons responded with >50% stimulation in OCR, indicating a robust response to increased energy demand without immediate toxicity. Pre-treatment with MgSO4 improved the initial bioenergetic response to glutamate and ameliorated subsequent loss of spare respiratory capacity, measured following addition of the uncoupler FCCP, in Type I but not Type II neurons. Spare respiratory capacity in Type I neurons was also improved by incubation with MgSO4 or NMDA receptor antagonist MK801 in the absence of glutamate treatment. This finding indicates that the major difference between Type I and Type II preparations is the amount of endogenous glutamate receptor activity. Incubation of Type II neurons with 5 µM glutamate prior to excitotoxic (100 µM) glutamate exposure recapitulated a Type I phenotype. MgSO4 protected against an excitotoxic glutamate-induced drop in neuronal ATP both with and without prior 5 µM glutamate exposure. Results indicate that MgSO4 protects against chronic moderate glutamate receptor stimulation and preserves cellular ATP following treatment with excitotoxic glutamate. PMID:24236167

  6. Force spectroscopy measurements show that cortical neurons exposed to excitotoxic agonists stiffen before showing evidence of bleb damage.

    Directory of Open Access Journals (Sweden)

    Shan Zou

    Full Text Available In ischemic and traumatic brain injury, hyperactivated glutamate (N-methyl-D-aspartic acid, NMDA and sodium (Nav channels trigger excitotoxic neuron death. Na(+, Ca(++ and H2O influx into affected neurons elicits swelling (increased cell volume and pathological blebbing (disassociation of the plasma membrane's bilayer from its spectrin-actomyosin matrix. Though usually conflated in injured tissue, cell swelling and blebbing are distinct processes. Around an injury core, salvageable neurons could be mildly swollen without yet having suffered the bleb-type membrane damage that, by rendering channels leaky and pumps dysfunctional, exacerbates the excitotoxic positive feedback spiral. Recognizing when neuronal inflation signifies non-lethal osmotic swelling versus blebbing should further efforts to salvage injury-penumbra neurons. To assess whether the mechanical properties of osmotically-swollen versus excitotoxically-blebbing neurons might be cytomechanically distinguishable, we measured cortical neuron elasticity (gauged via atomic force microscopy (AFM-based force spectroscopy upon brief exposure to hypotonicity or to excitotoxic agonists (glutamate and Nav channel activators, NMDA and veratridine. Though unperturbed by solution exchange per se, elasticity increased abruptly with hypotonicity, with NMDA and with veratridine. Neurons then invariably softened towards or below the pre-treatment level, sometimes starting before the washout. The initial channel-mediated stiffening bespeaks an abrupt elevation of hydrostatic pressure linked to NMDA or Nav channel-mediated ion/H2O fluxes, together with increased [Ca(++]int-mediated submembrane actomyosin contractility. The subsequent softening to below-control levels is consistent with the onset of a lethal level of bleb damage. These findings indicate that dissection/identification of molecular events during the excitotoxic transition from stiff/swollen to soft/blebbing is warranted and should be

  7. Force spectroscopy measurements show that cortical neurons exposed to excitotoxic agonists stiffen before showing evidence of bleb damage.

    Science.gov (United States)

    Zou, Shan; Chisholm, Roderick; Tauskela, Joseph S; Mealing, Geoff A; Johnston, Linda J; Morris, Catherine E

    2013-01-01

    In ischemic and traumatic brain injury, hyperactivated glutamate (N-methyl-D-aspartic acid, NMDA) and sodium (Nav) channels trigger excitotoxic neuron death. Na(+), Ca(++) and H2O influx into affected neurons elicits swelling (increased cell volume) and pathological blebbing (disassociation of the plasma membrane's bilayer from its spectrin-actomyosin matrix). Though usually conflated in injured tissue, cell swelling and blebbing are distinct processes. Around an injury core, salvageable neurons could be mildly swollen without yet having suffered the bleb-type membrane damage that, by rendering channels leaky and pumps dysfunctional, exacerbates the excitotoxic positive feedback spiral. Recognizing when neuronal inflation signifies non-lethal osmotic swelling versus blebbing should further efforts to salvage injury-penumbra neurons. To assess whether the mechanical properties of osmotically-swollen versus excitotoxically-blebbing neurons might be cytomechanically distinguishable, we measured cortical neuron elasticity (gauged via atomic force microscopy (AFM)-based force spectroscopy) upon brief exposure to hypotonicity or to excitotoxic agonists (glutamate and Nav channel activators, NMDA and veratridine). Though unperturbed by solution exchange per se, elasticity increased abruptly with hypotonicity, with NMDA and with veratridine. Neurons then invariably softened towards or below the pre-treatment level, sometimes starting before the washout. The initial channel-mediated stiffening bespeaks an abrupt elevation of hydrostatic pressure linked to NMDA or Nav channel-mediated ion/H2O fluxes, together with increased [Ca(++)]int-mediated submembrane actomyosin contractility. The subsequent softening to below-control levels is consistent with the onset of a lethal level of bleb damage. These findings indicate that dissection/identification of molecular events during the excitotoxic transition from stiff/swollen to soft/blebbing is warranted and should be feasible. PMID

  8. Novel application of stem cell-derived neurons to evaluate the time- and dose-dependent progression of excitotoxic injury.

    Directory of Open Access Journals (Sweden)

    Ian M Gut

    Full Text Available Glutamate receptor (GluR-mediated neurotoxicity is implicated in a variety of disorders ranging from ischemia to neural degeneration. Under conditions of elevated glutamate, the excessive activation of GluRs causes internalization of pathologic levels of Ca(2+, culminating in bioenergetic failure, organelle degradation, and cell death. Efforts to characterize cellular and molecular aspects of excitotoxicity and conduct therapeutic screening for pharmacologic inhibitors of excitogenic progression have been hindered by limitations associated with primary neuron culture. To address this, we evaluated glutamate-induced neurotoxicity in highly enriched glutamatergic neurons (ESNs derived from murine embryonic stem cells. As of 18 days in vitro (DIV 18, ESNs were synaptically coupled, exhibited spontaneous network activity with neurotypic mEPSCs and expressed NMDARs and AMPARs with physiological current:voltage behaviors. Addition of 0.78-200 μM glutamate evoked reproducible time- and dose-dependent metabolic failure in 6 h, with a calculated EC50 value of 0.44 μM at 24 h. Using a combination of cell viability assays and electrophysiology, we determined that glutamate-induced toxicity was specifically mediated by NMDARs and could be inhibited by addition of NMDAR antagonists, increased extracellular Mg(2+ or substitution of Ba(2+ for Ca(2+. Glutamate treatment evoked neurite fragmentation and focal swelling by both immunocytochemistry and scanning electron microscopy. Presentation of morphological markers of cell death was dose-dependent, with 0.78-200 μM glutamate resulting in apoptosis and 3000 μM glutamate generating a mixture of necrosis and apoptosis. Addition of neuroprotective small molecules reduced glutamate-induced neurotoxicity in a dose-dependent fashion. These data indicate that ESNs replicate many of the excitogenic mechanisms observed in primary neuron culture, offering a moderate-throughput model of excitotoxicity that combines the

  9. A study of cannabinoid-1 receptors during the early phase of excitotoxic damage to rat spinal locomotor networks in vitro.

    Science.gov (United States)

    Veeraraghavan, Priyadharishini; Dekanic, Ana; Nistri, Andrea

    2016-10-01

    Endocannabinoids acting on cannabinoid-1 receptors (CB1Rs) are proposed to protect brain and spinal neurons from excitotoxic damage. The ability to recover from spinal cord injury (SCI), in which excitotoxicity is a major player, is usually investigated at late times after modulation of CB1Rs whose role in the early phases of SCI remains unclear. Using the rat spinal cord in vitro as a model for studying SCI initial pathophysiology, we investigated if agonists or antagonists of CB1Rs might affect SCI induced by the excitotoxic agent kainate (KA) within 24h from a transient (1h) application of this glutamate agonist. The CB1 agonist anandamide (AEA or pharmacological block of its degradation) did not limit excitotoxic depolarization of spinal networks: cyclic adenosine monophosphate (cAMP) assay demonstrated that CB1Rs remained functional 24h later and similarly expressed among dead or survived cells. Locomotor-like network activity recorded from ventral roots could not recover with such treatments and was associated with persistent depression of synaptic transmission. Motoneurons, that are particularly vulnerable to KA, were not protected by AEA. Application of 2-arachidonoylglycerol also did not attenuate the electrophysiological and histological damage. The intensification of damage by the CB1 antagonist AM251 suggested that endocannabinoids were operative after excitotoxic stimulation, yet insufficient to contrast it efficiently. The present data indicate that the early phases of excitotoxic SCI could not be arrested by pharmacologically exploiting the endocannabinoid system, consistent with the notion that AEA and its derivatives are more useful to treat late SCI phases. PMID:27450568

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

    Science.gov (United States)

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

    2016-07-01

    Glutamate, the main excitatory amino acid in the vertebrate retina, is a well know activator of numerous signal transduction pathways, and has been critically involved in long-term synaptic changes acting through ionotropic and metabotropic glutamate receptors. However, recent findings underlining the importance of intensity and duration of glutamate stimuli for specific neuronal responses, including excitotoxicity, suggest a crucial role for Na(+)-dependent glutamate transporters, responsible for the removal of this neurotransmitter from the synaptic cleft, in the regulation of glutamate-induced signaling. Transporter proteins are expressed in neurons and glia cells, albeit most of glutamate uptake occurs in the glial compartment. Within the retina, Müller glia cells are in close proximity to glutamatergic synapses and participate in the recycling of glutamate through the glutamate/glutamine shuttle. In this context, we decided to investigate a plausible role of glutamate as a regulatory signal for its own transport in human retinal glia cells. To this end, we determined [(3)H]-D-aspartate uptake in cultures of spontaneously immortalized human Müller cells (MIO-M1) exposed to distinct glutamatergic ligands. A time and dose-dependent increase in the transporter activity was detected. This effect was dependent on the activation of the N-methyl D-aspartate subtype of glutamate receptors, due to a dual effect: an increase in affinity and an augmented expression of the transporter at the plasma membrane, as established via biotinylation experiments. Furthermore, a NMDA-dependent association of glutamate transporters with the cystoskeletal proteins ezrin and glial fibrillary acidic protein was also found. These results add a novel mediator of the glutamate transporter modulation and further strengthen the notion of the critical involvement of glia cells in synaptic function. PMID:27017513

  11. Pilocarpine-induced status epilepticus in rats involves ischemic and excitotoxic mechanisms.

    Directory of Open Access Journals (Sweden)

    Paolo Francesco Fabene

    Full Text Available The neuron loss characteristic of hippocampal sclerosis in temporal lobe epilepsy patients is thought to be the result of excitotoxic, rather than ischemic, injury. In this study, we assessed changes in vascular structure, gene expression, and the time course of neuronal degeneration in the cerebral cortex during the acute period after onset of pilocarpine-induced status epilepticus (SE. Immediately after 2 hr SE, the subgranular layers of somatosensory cortex exhibited a reduced vascular perfusion indicative of ischemia, whereas the immediately adjacent supragranular layers exhibited increased perfusion. Subgranular layers exhibited necrotic pathology, whereas the supergranular layers were characterized by a delayed (24 h after SE degeneration apparently via programmed cell death. These results indicate that both excitotoxic and ischemic injuries occur during pilocarpine-induced SE. Both of these degenerative pathways, as well as the widespread and severe brain damage observed, should be considered when animal model-based data are compared to human pathology.

  12. Pilocarpine-Induced Status Epilepticus in Rats Involves Ischemic and Excitotoxic Mechanisms

    Science.gov (United States)

    Fabene, Paolo Francesco; Merigo, Flavia; Galiè, Mirco; Benati, Donatella; Bernardi, Paolo; Farace, Paolo; Nicolato, Elena; Marzola, Pasquina; Sbarbati, Andrea

    2007-01-01

    The neuron loss characteristic of hippocampal sclerosis in temporal lobe epilepsy patients is thought to be the result of excitotoxic, rather than ischemic, injury. In this study, we assessed changes in vascular structure, gene expression, and the time course of neuronal degeneration in the cerebral cortex during the acute period after onset of pilocarpine-induced status epilepticus (SE). Immediately after 2 hr SE, the subgranular layers of somatosensory cortex exhibited a reduced vascular perfusion indicative of ischemia, whereas the immediately adjacent supragranular layers exhibited increased perfusion. Subgranular layers exhibited necrotic pathology, whereas the supergranular layers were characterized by a delayed (24 h after SE) degeneration apparently via programmed cell death. These results indicate that both excitotoxic and ischemic injuries occur during pilocarpine-induced SE. Both of these degenerative pathways, as well as the widespread and severe brain damage observed, should be considered when animal model-based data are compared to human pathology. PMID:17971868

  13. Glutamatergic Metabolites, Volume and Cortical Thickness in Antipsychotic-Naive Patients with First-Episode Psychosis: Implications for Excitotoxicity.

    Science.gov (United States)

    Plitman, Eric; Patel, Raihaan; Chung, Jun Ku; Pipitone, Jon; Chavez, Sofia; Reyes-Madrigal, Francisco; Gómez-Cruz, Gladys; León-Ortiz, Pablo; Chakravarty, M Mallar; de la Fuente-Sandoval, Camilo; Graff-Guerrero, Ariel

    2016-09-01

    Neuroimaging studies investigating patients with schizophrenia often report appreciable volumetric reductions and cortical thinning, yet the cause of these deficits is unknown. The association between subcortical and cortical structural alterations, and glutamatergic neurometabolites is of particular interest due to glutamate's capacity for neurotoxicity; elevated levels may be related to neuroanatomical compromise through an excitotoxic process. To this end, we explored the relationships between glutamatergic neurometabolites and structural measures in antipsychotic-naive patients experiencing their first non-affective episode of psychosis (FEP). Sixty antipsychotic-naive patients with FEP and 60 age- and sex-matched healthy controls underwent a magnetic resonance imaging session, which included a T1-weighted volumetric image and proton magnetic resonance spectroscopy in the precommissural dorsal caudate. Group differences in precommissural caudate volume (PCV) and cortical thickness (CT), and the relationships between glutamatergic neurometabolites (ie, glutamate+glutamine (Glx) and glutamate) and these structural measures, were examined. PCV was decreased in the FEP group (pschizophrenia. PMID:27272768

  14. The insulin/IGF signaling regulators cytohesin/GRP-1 and PIP5K/PPK-1 modulate susceptibility to excitotoxicity in C. elegans.

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    Nazila Tehrani

    Full Text Available During ischemic stroke, malfunction of excitatory amino acid transporters and reduced synaptic clearance causes accumulation of Glutamate (Glu and excessive stimulation of postsynaptic neurons, which can lead to their degeneration by excitotoxicity. The balance between cell death-promoting (neurotoxic and survival-promoting (neuroprotective signaling cascades determines the fate of neurons exposed to the excitotoxic insult. The evolutionary conserved Insulin/IGF Signaling (IIS cascade can participate in this balance, as it controls cell stress resistance in nematodes and mammals. Blocking the IIS cascade allows the transcription factor FoxO3/DAF-16 to accumulate in the nucleus and activate a transcriptional program that protects cells from a range of insults. We study the effect of IIS cascade on neurodegeneration in a C. elegans model of excitotoxicity, where a mutation in a central Glu transporter (glt-3 in a sensitizing background causes Glu-Receptor -dependent neuronal necrosis. We expand our studies on the role of the IIS cascade in determining susceptibility to excitotoxic necrosis by either blocking IIS at the level of PI3K/AGE-1 or stimulating it by removing the inhibitory effect of ZFP-1 on the expression of PDK-1. We further show that the components of the Cytohesin/GRP-1, Arf, and PIP5K/PPK-1 complex, known to regulate PIP2 production and the IIS cascade, modulate nematode excitotoxicity: mutations that are expected to reduce the complex's ability to produce PIP2 and inhibit the IIS cascade protect from excitotoxicity, while overstimulation of PIP2 production enhances neurodegeneration. Our observations therefore affirm the importance of the IIS cascade in determining the susceptibility to necrotic neurodegeneration in nematode excitotoxicity, and demonstrate the ability of Cytohesin/GRP-1, Arf, and PIP5K/PPK-1 complex to modulate neuroprotection.

  15. Glutamate in peripheral organs: Biology and pharmacology.

    Science.gov (United States)

    Du, Jie; Li, Xiao-Hui; Li, Yuan-Jian

    2016-08-01

    Glutamate is a versatile molecule existing in both the central nervous system and peripheral organs. Previous studies have mainly focussed on the biological effect of glutamate in the brain. Recently, abundant evidence has demonstrated that glutamate also participates in the regulation of physiopathological functions in peripheral tissues, including the lung, kidney, liver, heart, stomach and immune system, where the glutamate/glutamate receptor/glutamate transporter system plays an important role in the pathogenesis of certain diseases, such as myocardial ischaemia/reperfusion injury and acute gastric mucosa injury. All these findings provide new insight into the biology and pharmacology of glutamate and suggest a potential therapeutic role of glutamate in non-neurological diseases. PMID:27164423

  16. Distinct inhibition of acute cocaine-stimulated motor activity following microinjection of a group III metabotropic glutamate receptor agonist into the dorsal striatum of rats.

    Science.gov (United States)

    Mao, L; Wang, J Q

    2000-09-01

    Group III metabotropic glutamate receptors (mGluRs) are negatively coupled to adenylate cyclase through G-proteins. Activation of this group of mGluRs shows an inhibition of dopaminergic transmission in the forebrain. To define the role of striatal group III mGluRs in the regulation of basal and dopamine-stimulated motor behavior, the recently developed agonist and antagonist relatively selective for group III mGluRs were utilized to pharmacologically enhance and reduce group III mGluR glutamatergic tone in the dorsal striatum of chronically cannulated rats. Bilateral injections of a group III agonist, L-2-amino-4-phosphonobutyrate (L-AP4), did not alter basal levels of motor activity at three doses surveyed (1, 10, and 100 nmol). Neither did intracaudate injection of a group III antagonist, alpha-methyl-4-phosphonophenylglycine (MPPG), at 10, 30, and 100 nmol. However, pretreatment with L-AP4 (10 and 100 nmol) dose dependently blocked hyperlocomotion induced by acute injection of cocaine (20 mg/kg, i.p.), amphetamine (2.5 mg/kg, i.p.), or apomorphine (1 mg/kg, s.c.). The behavioral activity induced by cocaine was much more sensitive to L-AP4 than that induced by amphetamine and apomorphine. At 100 nmol, L-AP4 completely blocked cocaine effect whereas amphetamine- and apomorphine-stimulated behaviors were blocked only by 28% and 31%, respectively. The blocking effect of L-AP4 on cocaine action was reversed by pretreatment with MPPG. MPPG itself did not modify behavioral responses to cocaine, amphetamine, or apomorphine. These data indicate that the glutamatergic tone on the group III mGluRs is not active in the regulation of basal and acute dopamine-stimulated motor activity. However, enhanced group III mGluR glutamatergic transmission by an exogenous ligand is capable of suppressing behavioral responses to acute exposure of dopamine stimulants. PMID:11113488

  17. 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 homeostasis. Transendothelial transport- and accumulation studies of (3) H-L-glutamate, (3) H-L-aspartate, and (3) H-D-aspartate in an electrically tight bovine endothelial/rat astrocyte blood-brain barrier coculture model were performed. After 6 days in culture, the endothelium displayed transendothelial...... resistance values of 1014 ± 70 O cm(2) , and (14) C-D-mannitol permeability values of 0.88 ± 0.13 × 10(-6) cm s(-1) . Unidirectional flux studies showed that L-aspartate and L-glutamate, but not D-aspartate, displayed polarized transport in the brain-to-blood direction, however, all three amino acids...

  18. A Cytotoxic, Co-operative Interaction Between Energy Deprivation and Glutamate Release From System xc- Mediates Aglycemic Neuronal Cell Death.

    Science.gov (United States)

    Thorn, Trista L; He, Yan; Jackman, Nicole A; Lobner, Doug; Hewett, James A; Hewett, Sandra J

    2015-01-01

    The astrocyte cystine/glutamate antiporter (system xc(-)) contributes substantially to the excitotoxic neuronal cell death facilitated by glucose deprivation. The purpose of this study was to determine the mechanism by which this occurred. Using pure astrocyte cultures, as well as, mixed cortical cell cultures containing both neurons and astrocytes, we found that neither an enhancement in system xc(-) expression nor activity underlies the excitotoxic effects of aglycemia. In addition, using three separate bioassays, we demonstrate no change in the ability of glucose-deprived astrocytes--either cultured alone or with neurons--to remove glutamate from the extracellular space. Instead, we demonstrate that glucose-deprived cultures are 2 to 3 times more sensitive to the killing effects of glutamate or N-methyl-D-aspartate when compared with their glucose-containing controls. Hence, our results are consistent with the weak excitotoxic hypothesis such that a bioenergetic deficiency, which is measureable in our mixed but not astrocyte cultures, allows normally innocuous concentrations of glutamate to become excitotoxic. Adding to the burgeoning literature detailing the contribution of astrocytes to neuronal injury, we conclude that under our experimental paradigm, a cytotoxic, co-operative interaction between energy deprivation and glutamate release from astrocyte system xc(-) mediates aglycemic neuronal cell death.

  19. A Cytotoxic, Co-operative Interaction Between Energy Deprivation and Glutamate Release From System xc− Mediates Aglycemic Neuronal Cell Death

    Directory of Open Access Journals (Sweden)

    Trista L. Thorn

    2015-11-01

    Full Text Available The astrocyte cystine/glutamate antiporter (system xc− contributes substantially to the excitotoxic neuronal cell death facilitated by glucose deprivation. The purpose of this study was to determine the mechanism by which this occurred. Using pure astrocyte cultures, as well as, mixed cortical cell cultures containing both neurons and astrocytes, we found that neither an enhancement in system xc− expression nor activity underlies the excitotoxic effects of aglycemia. In addition, using three separate bioassays, we demonstrate no change in the ability of glucose-deprived astrocytes—either cultured alone or with neurons—to remove glutamate from the extracellular space. Instead, we demonstrate that glucose-deprived cultures are 2 to 3 times more sensitive to the killing effects of glutamate or N-methyl-D-aspartate when compared with their glucose-containing controls. Hence, our results are consistent with the weak excitotoxic hypothesis such that a bioenergetic deficiency, which is measureable in our mixed but not astrocyte cultures, allows normally innocuous concentrations of glutamate to become excitotoxic. Adding to the burgeoning literature detailing the contribution of astrocytes to neuronal injury, we conclude that under our experimental paradigm, a cytotoxic, co-operative interaction between energy deprivation and glutamate release from astrocyte system xc− mediates aglycemic neuronal cell death.

  20. Neuroprotection by GH against excitotoxic-induced cell death in retinal ganglion cells.

    Science.gov (United States)

    Martínez-Moreno, Carlos G; Ávila-Mendoza, José; Wu, Yilun; Arellanes-Licea, Elvira Del Carmen; Louie, Marcela; Luna, Maricela; Arámburo, Carlos; Harvey, Steve

    2016-08-01

    Retinal growth hormone (GH) has been shown to promote cell survival in retinal ganglion cells (RGCs) during developmental waves of apoptosis during chicken embryonic development. The possibility that it might also against excitotoxicity-induced cell death was therefore examined in the present study, which utilized quail-derived QNR/D cells as an in vitro RGC model. QNR/D cell death was induced by glutamate in the presence of BSO (buthionine sulfoxamide) (an enhancer of oxidative stress), but this was significantly reduced (PGH (rcGH). Similarly, QNR/D cells that had been prior transfected with a GH plasmid to overexpress secreted and non-secreted GH. This treatment reduced the number of TUNEL-labeled cells and blocked their release of lactate dehydrogenase (LDH). In a further experiment with dissected neuroretinal explants from ED (embryonic day) 10 embryos, rcGH treatment of the explants also reduced (PGH-overexpressing QNR/D cells. As rcGH treatment and GH-overexpression cells also increased the content of IGF-1 and IGF-1 mRNA this neuroprotective action of GH is likely to be mediated, at least partially, through an IGF-1 mechanism. This possibility is supported by the fact that the siRNA knockdown of GH or IGF-1 significantly reduced QNR/D cell viability, as did the immunoneutralization of IGF-1. GH is therefore neuroprotective against excitotoxicity-induced RGC cell death by anti-apoptotic actions involving IGF-1 stimulation. PMID:27129619

  1. 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. PMID:27184881

  2. Glutamate receptors

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  3. Astroglial glutamate transporters coordinate excitatory signaling and brain energetics.

    Science.gov (United States)

    Robinson, Michael B; Jackson, Joshua G

    2016-09-01

    In the mammalian brain, a family of sodium-dependent transporters maintains low extracellular glutamate and shapes excitatory signaling. The bulk of this activity is mediated by the astroglial glutamate transporters GLT-1 and GLAST (also called EAAT2 and EAAT1). In this review, we will discuss evidence that these transporters co-localize with, form physical (co-immunoprecipitable) interactions with, and functionally couple to various 'energy-generating' systems, including the Na(+)/K(+)-ATPase, the Na(+)/Ca(2+) exchanger, glycogen metabolizing enzymes, glycolytic enzymes, and mitochondria/mitochondrial proteins. This functional coupling is bi-directional with many of these systems both being regulated by glutamate transport and providing the 'fuel' to support glutamate uptake. Given the importance of glutamate uptake to maintaining synaptic signaling and preventing excitotoxicity, it should not be surprising that some of these systems appear to 'redundantly' support the energetic costs of glutamate uptake. Although the glutamate-glutamine cycle contributes to recycling of neurotransmitter pools of glutamate, this is an over-simplification. The ramifications of co-compartmentalization of glutamate transporters with mitochondria for glutamate metabolism are discussed. Energy consumption in the brain accounts for ∼20% of the basal metabolic rate and relies almost exclusively on glucose for the production of ATP. However, the brain does not possess substantial reserves of glucose or other fuels. To ensure adequate energetic supply, increases in neuronal activity are matched by increases in cerebral blood flow via a process known as 'neurovascular coupling'. While the mechanisms for this coupling are not completely resolved, it is generally agreed that astrocytes, with processes that extend to synapses and endfeet that surround blood vessels, mediate at least some of the signal that causes vasodilation. Several studies have shown that either genetic deletion or

  4. Change of glutamic acid decarboxylase antibody and protein tyrosine phosphatase antibody in Chinese patients with acute-onset type 1 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    CHAO Chen; HUANG Gan; LI Xia; YANG Lin; LIN Jian; JIN Ping; LUO Shuo-ming

    2013-01-01

    Background Glutamic acid decarboxylase antibody (GADA) and protein tyrosine phosphatase antibody (IA-2A) are two major autoantibodies,which exert important roles in the process of type 1 diabetes mellitus (T1D).Our study aimed to investigate the changes in positivity and titers of GADA and IA-2A during the course of Chinese acute-onset T1D patients and their relationships with clinical features.Methods Two hundreds and forty-seven Chinese newly diagnosed acute-onset T1D patients were consecutively recruited.GADA and IA-2A were detected at the time of diagnosis,one year later,3-5 years later after diagnosis during the follow-up; all the clinical data were recorded and analyzed as well.Results During the course of acute-onset T1D,the majority of patients remained stable for GADA or IA-2A,however,a few patients changed from positivity to negativity and fewer patients converted from negativity to positivity.The prevalence of GADA was 56.3% at diagnosis,decreasing to 50.5% one year later,and 43.3% 3-5 years later while the corresponding prevalence of IA-2A were 32.8%,31.0% and 23.3%,respectively.The median GADA titers were 0.0825 at diagnosis,declining to 0.0585 one year later and 0.0383 3-5 years later (P <0.001),while the corresponding median titers were 0.0016,0.0010,0.0014 for IA-2A,respectively.Fasting C-peptide (FCP) and postprandial C-peptide 2 hours (PCP2h)levels of GADA or IA-2A negativity persistence patients were higher than those of positivity persistence and negativity conversion patients (P <0.05) which indicated GADA or IA-2A negativity persistence T1D patients had a less loss of β cell function.Conclusion Our data suggest that repeated detection of GADA and IA-2A are necessary for differential diagnosis of autoimmune diabetes and the indirect prediction of the β cell function in Chinese patients.

  5. Protection of neurons in the retinal ganglion cell layer against excitotoxicity by the N-acylethanolamine, N-linoleoylethanolamine

    Directory of Open Access Journals (Sweden)

    Duncan RS

    2011-04-01

    Full Text Available R. Scott Duncan1,*, Hua Xin1,*, Daryl L Goad1, Kent D Chapman2,3, Peter Koulen1,31Vision Research Center and Departments of Ophthalmology and Basic Medical Science, School of Medicine, University of Missouri, Kansas City, MO, USA; 2Department of Biological Sciences, University of North Texas, Denton, TX, USA; 3Center for Plant Lipid Research, University of North Texas, Denton, TX, USA *Authors contributed equallyAbstract: Retinal ganglion cell (RGC death is a hallmark of neurodegenerative diseases and disease processes of the eye, including glaucoma. The protection of RGCs has been an important strategy for combating glaucoma, but little clinical success has been reported to date. One pathophysiological consequence of glaucoma is excessive extracellular glutamate subsequently leading to excitotoxicity in the retina. Endocannabinoids, such as the N-acylethanolamine (NAE, arachidonylethanolamine (NAE 20:4, exhibit neuroprotective properties in some models of neurodegenerative disease. The majority of NAEs, however, are not cannabinoids, and their physiological function is not clear. Here, we determined whether the noncannabinoid NAE, linoleoylethanolamine (NAE18:2, protects neurons in the RGC layer against glutamate excitotoxicity in ex-vivo retina cultures. Using a terminal deoxynucleotidyl transferase-mediated dUTP (2´-deoxyuridine 5´-triphosphate nick-end labeling (TUNEL assay, we determined that NAE18:2 reduces the number of apoptotic RGC layer neurons in response to glutamate and conclude that NAE18:2 is a neuroprotective compound with potential for treating glaucomatous retinopathy.Keywords: neuroprotection, glutamate, calcium signaling, immunocytochemistry, eye, vision, glaucoma.

  6. Role of brain glutamic acid metabolism changes in neurodegenerative pathologies

    OpenAIRE

    Nina Pavlovna Kanunnikova

    2012-01-01

    Glutamic acid is an essential participant of brain metabolism. It is known that the glutamate is a neurotransmitter in a numerous part of the brain synapses and acts through various ionotropic or metabotropic receptors. Multiple alterations of the brain glutamate system are observed in both acute and chronic brain injures. Glutamate metabolism changes take place in many neurodegenerative pathologies, such as brain ischemia, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, amyot...

  7. Glutamate release from astrocytic gliosomes under physiological and pathological conditions.

    Science.gov (United States)

    Milanese, Marco; Bonifacino, Tiziana; Zappettini, Simona; Usai, Cesare; Tacchetti, Carlo; Nobile, Mario; Bonanno, Giambattista

    2009-01-01

    Glial subcellular particles (gliosomes) have been purified from rat cerebral cortex or mouse spinal cord and investigated for their ability to release glutamate. Confocal microscopy showed that gliosomes are enriched with glia-specific proteins, such as GFAP and S-100 but not neuronal proteins, such as PSD-95, MAP-2, and beta-tubulin III. Furthermore, gliosomes exhibit labeling neither for integrin-alphaM nor for myelin basic protein, specific for microglia and oligodendrocytes, respectively. The gliosomal fraction contains proteins of the exocytotic machinery coexisting with GFAP. Consistent with ultrastructural analysis, several nonclustered vesicles are present in the gliosome cytoplasm. Finally, gliosomes represent functional organelles that actively export glutamate when subjected to releasing stimuli, such as ionomycin, high KCl, veratrine, 4-aminopyridine, AMPA, or ATP by mechanisms involving extracellular Ca2+, Ca2+ release from intracellular stores as well as reversal of glutamate transporters. In addition, gliosomes can release glutamate also by a mechanism involving heterologous transporter activation (heterotransporters) located on glutamate-releasing and glutamate transporter-expressing (homotransporters) gliosomes. This glutamate release involves reversal of glutamate transporters and anion channel opening, but not exocytosis. Both the exocytotic and the heterotransporter-mediated glutamate release were more abundant in gliosomes prepared from the spinal cord of transgenic mice, model of amyotrophic lateral sclerosis, than in controls; suggesting the involvement of astrocytic glutamate release in the excitotoxicity proposed as a cause of motor neuron degeneration. The results support the view that gliosomes may represent a viable preparation that allows to study mechanisms of astrocytic transmitter release and its regulation in healthy animals and in animal models of brain diseases. PMID:19607977

  8. Glutamate transporters and presynaptic metabotropic glutamate receptors protect neocortical Cajal-Retzius cells against over-excitation.

    Science.gov (United States)

    Dvorzhak, Anton; Unichenko, Petr; Kirischuk, Sergei

    2012-08-01

    Cajal-Retzius (CR) cells, early generated neurons in the marginal zone of developing neocortex, are reported to be highly vulnerable to excitotoxic damage. Because extracellular glutamate concentration in the central nervous system is mainly controlled by glutamate transporters (EAATs), we studied the effects of EAAT blockade on CR cells. DL: -TBOA, a specific EAAT antagonist, induced NMDA receptor-dependent bursting discharges in layer 2/3 pyramidal neurons, indicating that EAATs operate in the uptake mode and their blockade leads to elevation of extracellular glutamate concentration. In CR cells, however, DL: -TBOA failed to change either the membrane resistance or holding current, and moreover, it reduced the frequency of spontaneous GABAergic postsynaptic currents. DL: -TBOA decreased the mean amplitude and increased paired-pulse ratio of evoked GABAergic postsynaptic currents, indicating the presynaptic locus of its action. Indeed, LY379268, a specific agonist of group II metabotropic glutamate receptors (mGluR-II), mimicked the DL: -TBOA-mediated effects, and LY341495, an unspecific mGluR antagonist, eliminated the DL: -TBOA-induced effects. As dihydrokainic acid, a specific EAAT2 blocker, failed to affect evoked GABAergic postsynaptic currents, whereas TFB-TBOA, a selective blocker of EAAT1 and EAAT2, produced effects similar to that of DL: -TBOA, extracellular glutamate concentration in the marginal zone is mainly controlled by EAAT1 (GLAST). Thus, even though CR cells are highly vulnerable to excitotoxic damage, a number of mechanisms serve to protect them against excessive extracellular glutamate concentration including a lack of functional glutamatergic synapses, Mg(2+) blockade of NMDA receptors, and presynaptic mGluRs that inhibit transmission at GABAergic synapses. PMID:22665047

  9. Protective effects of Ginkgo biloba extract 761 against glutamate-induced neurotoxicity in cultured retinal neuron

    Institute of Scientific and Technical Information of China (English)

    WANG Yun-song; XU Liang; MA Ke; WANG Shuang; WANG Jin-jin

    2005-01-01

    @@ A large part of neuronal death is the result of episodes of anoxia and ischaemia in the retina and other eye diseases, such as anterior ischemic optic neuropathy, glaucoma. The neuronal death is due to the accumulation of glutamate in the extracellular space. Glutamate is the primary excitatory neurotransmitter in the retina. However, excessive overactivation of glutamate receptors leads to excitotoxic neuronal cell death. Glutamate induces cell death by increasing the levels of intracellular Ca2+ in neurons, thereby leading to generation of free radicals and activation proteases, as well as transcriptional activation of specific cell death programs. Glutamate excitoxicity can also cause neuronal mitochondrial membrane potential (MMP) loss, which is associated with changes in mitochondrial function leading to a neuronal dysfunction.

  10. Mechanisms of Neuronal Protection against Excitotoxicity, Endoplasmic Reticulum Stress, and Mitochondrial Dysfunction in Stroke and Neurodegenerative Diseases

    Directory of Open Access Journals (Sweden)

    Howard Prentice

    2015-01-01

    Full Text Available In stroke and neurodegenerative disease, neuronal excitotoxicity, caused by increased extracellular glutamate levels, is known to result in calcium overload and mitochondrial dysfunction. Mitochondrial deficits may involve a deficiency in energy supply as well as generation of high levels of oxidants which are key contributors to neuronal cell death through necrotic and apoptotic mechanisms. Excessive glutamate receptor stimulation also results in increased nitric oxide generation which can be detrimental to cells as nitric oxide interacts with superoxide to form the toxic molecule peroxynitrite. High level oxidant production elicits neuronal apoptosis through the actions of proapoptotic Bcl-2 family members resulting in mitochondrial permeability transition pore opening. In addition to apoptotic responses to severe stress, accumulation of misfolded proteins and high levels of oxidants can elicit endoplasmic reticulum (ER stress pathways which may also contribute to induction of apoptosis. Two categories of therapeutics are discussed that impact major pro-death events that include induction of oxidants, calcium overload, and ER stress. The first category of therapeutic agent includes the amino acid taurine which prevents calcium overload and is also capable of preventing ER stress by inhibiting specific ER stress pathways. The second category involves N-methyl-D-aspartate receptor (NMDA receptor partial antagonists illustrated by S-Methyl-N, N-diethyldithiocarbamate sulfoxide (DETC-MeSO, and memantine. DETC-MeSO is protective through preventing excitotoxicity and calcium overload and by blocking specific ER stress pathways. Another NMDA receptor partial antagonist is memantine which prevents excessive glutamate excitation but also remarkably allows maintenance of physiological neurotransmission. Targeting of these major sites of neuronal damage using pharmacological agents is discussed in terms of potential therapeutic approaches for

  11. Cyclooxygenase-2 expression in oligodendrocytes increases sensitivity to excitotoxic death

    Directory of Open Access Journals (Sweden)

    Rojas Monica A

    2010-04-01

    Full Text Available Abstract Background We previously found that cyclooxygenase 2 (COX-2 was expressed in dying oligodendrocytes at the onset of demyelination in the Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD model of multiple sclerosis (MS (Carlson et al. J.Neuroimmunology 2006, 149:40. This suggests that COX-2 may contribute to death of oligodendrocytes. Objective The goal of this study was to examine whether COX-2 contributes to excitotoxic death of oligodendrocytes and potentially contributes to demyelination. Methods The potential link between COX-2 and oligodendrocyte death was approached using histopathology of MS lesions to examine whether COX-2 was expressed in dying oligodendrocytes. COX-2 inhibitors were examined for their ability to limit demyelination in the TMEV-IDD model of MS and to limit excitotoxic death of oligodendrocytes in vitro. Genetic manipulation of COX-2 expression was used to determine whether COX-2 contributes to excitotoxic death of oligodendrocytes. A transgenic mouse line was generated that overexpressed COX-2 in oligodendrocytes. Oligodendrocyte cultures derived from these transgenic mice were used to examine whether increased expression of COX-2 enhanced the vulnerability of oligodendrocytes to excitotoxic death. Oligodendrocytes derived from COX-2 knockout mice were evaluated to determine if decreased COX-2 expression promotes a greater resistance to excitotoxic death. Results COX-2 was expressed in dying oligodendrocytes in MS lesions. COX-2 inhibitors limited demyelination in the TMEV-IDD model of MS and protected oligodendrocytes against excitotoxic death in vitro. COX-2 expression was increased in wild-type oligodendrocytes following treatment with Kainic acid (KA. Overexpression of COX-2 in oligodendrocytes increased the sensitivity of oligodendrocytes to KA-induced excitotoxic death eight-fold compared to wild-type. Conversely, oligodendrocytes prepared from COX-2 knockout mice showed a

  12. In vivo Electrochemical Biosensor for Brain Glutamate Detection: A Mini Review.

    Science.gov (United States)

    Hamdan, Siti Kartika; Mohd Zain, Ainiharyati

    2014-12-01

    Glutamate is one of the most prominent neurotransmitters in mammalian brains, which plays an important role in neuronal excitation. High levels of neurotransmitter cause numerous alterations, such as calcium overload and the dysfunction of mitochondrial and oxidative stress. These alterations may lead to excitotoxicity and may trigger multiple neuronal diseases, such as Alzheimer's disease, stroke, and epilepsy. Excitotoxicity is a pathological process that damages nerve cells and kills cells via excessive stimulation by neurotransmitters. Monitoring the concentration level of brain glutamate via an implantable microbiosensor is a promising alternative approach to closely investigate in the function of glutamate as a neurotransmitter. This review outlines glutamate microbiosensor designs to enhance the sensitivity of glutamate detection with less biofouling occurrence and minimal detection of interference species. There are many challenges in the development of a reproducible and stable implantable microbiosensor because many factors and limitations may affect the detection performance. However, the incorporation of multiple scales is needed to address the basic issues and combinations across the various disciplines needed to achieve the success of the system to overcome the challenges in the development of an implantable glutamate biosensor. PMID:25941459

  13. 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.

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

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    Chao Zhang

    2016-10-01

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

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

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  16. 谷氨酸转运体靶点药物的抗脑缺血作用研究进展%Drugs targeting glutamate transporters for prevention and treatment of cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    黄龙飞; 钱贻崧; 关腾; 黄梦昊; 李运曼

    2012-01-01

    兴奋性氨基酸毒性是脑缺血损伤的主要机制之一.缺血期间谷氨酸的大量累积会导致神经元细胞、星形胶质细胞等神经细胞发生兴奋性毒性损伤,因此对缺血期间谷氨酸水平的调控一直是脑缺血防治药物研究的重点.近年来研究表明,通过上调星形胶质细胞上谷氨酸转运体GLAST( EAATl)和GLT-1( EAAT2)的表达或活性,增加缺血时谷氨酸的摄取,维持突触间隙内谷氨酸的正常浓度,从而降低兴奋性毒性,减轻缺血性脑损伤.一些化合物如β-内酰胺类抗生素、尿酸、甲状腺激素、雌激素、山楂酸等已在体内或体外实验中被证实对谷氨酸转运体的调节作用,对抗谷氨酸毒性,发挥神经保护作用.研究和开发以星形胶质细胞谷氨酸转运体为作用靶点的药物,为缺血性脑损伤的预防和治疗提供了一条新的途径.%Glutamate is the most important excitatory neurotransmitter in the brain. However, it is a potent neurotoxin and is considered as the primary cause of neuron death during acute brain ischemia and in neurodegener-ative diseases. Thus, the effective treatment of excitotoxic injury requires modulation of glutamate release, glutamate receptor activation, ROS generation and glutamate transport. The astrocytic glutamate transporters GLAST/ EAAT1 and GLT-1/EAAT2 are crucial for removal of glutamate from the synaptic cleft, and are essential for maintaining a low concentration of extracellular glutamate in the brain. Enhanced transporter expression or activity is neuroprotective. Some compounds, such as (3-lactams, uric acid, thyroid hormone, estrogen and maslinic acid, have been indicated to reduce the neuron injury after cerebral ischemia by regulation of glutamate transporter function. Researches on astrocytic glutamate transporter-dependent neuroprotection provide a novel strategy for cerebral ischemia therapy and drug development.

  17. Increase of extracellular glutamate concentration increases its oxidation and diminishes glucose oxidation in isolated mouse hippocampus: reversible by TFB-TBOA.

    Science.gov (United States)

    Torres, Felipe Vasconcelos; Hansen, Fernanda; Locks-Coelho, Lucas Doridio

    2013-08-01

    Glutamate concentration at the synaptic level must be kept low in order to prevent excitotoxicity. Astrocytes play a key role in brain energetics, and also astrocytic glutamate transporters are responsible for the vast majority of glutamate uptake in CNS. Experiments with primary astrocytic cultures suggest that increased influx of glutamate cotransported with sodium at astrocytes favors its flux to the tricarboxylic acid cycle instead of the glutamate-glutamine cycle. Although metabolic coupling can be considered an emergent field of research with important recent discoveries, some basic aspects of glutamate metabolism still have not been characterized in brain tissue. Therefore, the aim of this study was to investigate whether the presence of extracellular glutamate is able to modulate the use of glutamate and glucose as energetic substrates. For this purpose, isolated hippocampi of mice were incubated with radiolabeled substrates, and CO2 radioactivity and extracellular lactate were measured. Our results point to a diminished oxidation of glucose with increasing extracellular glutamate concentration, glutamate presumably being the fuel, and might suggest that oxidation of glutamate could buffer excitotoxic conditions by high glutamate concentrations. In addition, these findings were reversed when glutamate uptake by astrocytes was impaired by the presence of (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-L-aspartic acid (TFB-TBOA). Taken together, our findings argue against the lactate shuttle theory, because glutamate did not cause any detectable increase in extracellular lactate content (or, presumably, in glycolysis), because the glutamate is being used as fuel instead of going to glutamine and back to neurons. PMID:23359514

  18. 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.

  19. Acacetin inhibits glutamate release and prevents kainic acid-induced neurotoxicity in rats.

    Directory of Open Access Journals (Sweden)

    Tzu-Yu Lin

    Full Text Available An excessive release of glutamate is considered to be a molecular mechanism associated with several neurological diseases that causes neuronal damage. Therefore, searching for compounds that reduce glutamate neurotoxicity is necessary. In this study, the possibility that the natural flavone acacetin derived from the traditional Chinese medicine Clerodendrum inerme (L. Gaertn is a neuroprotective agent was investigated. The effect of acacetin on endogenous glutamate release in rat hippocampal nerve terminals (synaptosomes was also investigated. The results indicated that acacetin inhibited depolarization-evoked glutamate release and cytosolic free Ca(2+ concentration ([Ca(2+]C in the hippocampal nerve terminals. However, acacetin did not alter synaptosomal membrane potential. Furthermore, the inhibitory effect of acacetin on evoked glutamate release was prevented by the Cav2.2 (N-type and Cav2.1 (P/Q-type channel blocker known as ω-conotoxin MVIIC. In a kainic acid (KA rat model, an animal model used for excitotoxic neurodegeneration experiments, acacetin (10 or 50 mg/kg was administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg intraperitoneal injection, and subsequently induced the attenuation of KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. The present study demonstrates that the natural compound, acacetin, inhibits glutamate release from hippocampal synaptosomes by attenuating voltage-dependent Ca(2+ entry and effectively prevents KA-induced in vivo excitotoxicity. Collectively, these data suggest that acacetin has the therapeutic potential for treating neurological diseases associated with excitotoxicity.

  20. NMDA receptor-dependent glutamate excitotoxicity in human embryonic stem cell-derived neurons

    OpenAIRE

    Gupta, K.; Hardingham, G. E.; Chandran, S

    2013-01-01

    Thanks to the development of efficient differentiation strategies, human pluripotent stem cells (HPSC) offer the opportunity for modelling neuronal injury and dysfunction in human neurons in vitro. Critically, the effective use of HPSC-derived neural cells in disease-modelling and potentially cell replacement therapies hinges on an understanding of the biology of these cells, specifically their development, subtype specification and responses to neurotoxic signalling mediators. Here, we gener...

  1. Aβ Induces Excitotoxicity Mediated by APC/C-Cdh1 Depletion That Can Be Prevented by Glutaminase Inhibition Promoting Neuronal Survival.

    Science.gov (United States)

    Fuchsberger, T; Martínez-Bellver, S; Giraldo, E; Teruel-Martí, V; Lloret, A; Viña, J

    2016-08-12

    The E3 ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C) is activated by the fizzy-related protein homolog/CDC20-like protein 1 (cdh1) in post-mitotic neurons. Growing evidence suggests that dysregulation of APC/C-Cdh1 is involved in neurodegenerative diseases. Here we show in neurons that oligomers of amyloid beta (Aβ), a peptide related to Alzheimer's disease, cause proteasome-dependent degradation of cdh1. This leads to a subsequent increase in glutaminase (a degradation target of APC/C-Cdh1), which causes an elevation of glutamate levels and further intraneuronal Ca(2+) dysregulation, resulting in neuronal apoptosis. Glutaminase inhibition prevents glutamate excitotoxicity and apoptosis in Aβ treated neurons. Furthermore, glutamate also decreases cdh1 and leads to accumulation of glutaminase, suggesting that there may be a positive feedback loop of cdh1 inactivation. We confirmed the main findings in vivo using microinjection of either Aβ or glutamate in the CA1 region of the rat hippocampus. We show here for the first time in vivo that both Aβ and glutamate cause nuclear exclusion of cdh1 and an increase in glutaminase. These results show that maintaining normal APC/C-Cdh1 activity may be a useful target in Alzheimer's disease treatment.

  2. L-Lactate protects neurons against excitotoxicity: implication of an ATP-mediated signaling cascade.

    Science.gov (United States)

    Jourdain, P; Allaman, I; Rothenfusser, K; Fiumelli, H; Marquet, P; Magistretti, P J

    2016-01-01

    Converging experimental data indicate a neuroprotective action of L-Lactate. Using Digital Holographic Microscopy, we observe that transient application of glutamate (100 μM; 2 min) elicits a NMDA-dependent death in 65% of mouse cortical neurons in culture. In the presence of L-Lactate (or Pyruvate), the percentage of neuronal death decreases to 32%. UK5099, a blocker of the Mitochondrial Pyruvate Carrier, fully prevents L-Lactate-mediated neuroprotection. In addition, L-Lactate-induced neuroprotection is not only inhibited by probenicid and carbenoxolone, two blockers of ATP channel pannexins, but also abolished by apyrase, an enzyme degrading ATP, suggesting that ATP produced by the Lactate/Pyruvate pathway is released to act on purinergic receptors in an autocrine/paracrine manner. Finally, pharmacological approaches support the involvement of the P2Y receptors associated to the PI3-kinase pathway, leading to activation of KATP channels. This set of results indicates that L-Lactate acts as a signalling molecule for neuroprotection against excitotoxicity through coordinated cellular pathways involving ATP production, release and activation of a P2Y/KATP cascade. PMID:26893204

  3. L-Lactate protects neurons against excitotoxicity: implication of an ATP-mediated signaling cascade

    KAUST Repository

    Jourdain, P.

    2016-02-19

    Converging experimental data indicate a neuroprotective action of L-Lactate. Using Digital Holographic Microscopy, we observe that transient application of glutamate (100 μM; 2 min) elicits a NMDA-dependent death in 65% of mouse cortical neurons in culture. In the presence of L-Lactate (or Pyruvate), the percentage of neuronal death decreases to 32%. UK5099, a blocker of the Mitochondrial Pyruvate Carrier, fully prevents L-Lactate-mediated neuroprotection. In addition, L-Lactate-induced neuroprotection is not only inhibited by probenicid and carbenoxolone, two blockers of ATP channel pannexins, but also abolished by apyrase, an enzyme degrading ATP, suggesting that ATP produced by the Lactate/Pyruvate pathway is released to act on purinergic receptors in an autocrine/paracrine manner. Finally, pharmacological approaches support the involvement of the P2Y receptors associated to the PI3-kinase pathway, leading to activation of KATP channels. This set of results indicates that L-Lactate acts as a signalling molecule for neuroprotection against excitotoxicity through coordinated cellular pathways involving ATP production, release and activation of a P2Y/KATP cascade.

  4. Hyperactive Somatostatin Interneurons Contribute to Excitotoxicity in Neurodegenerative Disorders

    Science.gov (United States)

    Liang, Bo; Schroeder, David; Zhang, Zhong-wei; Cox, Gregory A.; Li, Yun; Lin, Da-Ting

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are overlapping neurodegenerative disorders whose pathogenesis remains largely unknown. Here using TDP-43A315T mice, an ALS and FTD model with profound cortical pathology, we demonstrated that hyperactive somatostatin interneurons disinhibited layer 5 pyramidal neurons (L5-PN) and contributed to their excitotoxicity. Focal ablation of somatostatin interneurons efficiently restored normal excitability of L5-PN and alleviated neurodegeneration, suggesting a novel therapeutic target for ALS and FTD. PMID:26900927

  5. High-Throughput Assay Development for Cystine-Glutamate Antiporter (xc-) Highlights Faster Cystine Uptake than Glutamate Release in Glioma Cells.

    Science.gov (United States)

    Thomas, Ajit G; Sattler, Rita; Tendyke, Karen; Loiacono, Kara A; Hansen, Hans; Sahni, Vishal; Hashizume, Yutaka; Rojas, Camilo; Slusher, Barbara S

    2015-01-01

    The cystine-glutamate antiporter (system xc-) is a Na+-independent amino acid transporter that exchanges extracellular cystine for intracellular glutamate. It is thought to play a critical role in cellular redox processes through regulation of intracellular glutathione synthesis via cystine uptake. In gliomas, system xc- expression is universally up-regulated while that of glutamate transporters down-regulated, leading to a progressive accumulation of extracellular glutamate and excitotoxic cell death of the surrounding non-tumorous tissue. Additionally, up-regulation of system xc- in activated microglia has been implicated in the pathogenesis of several neurodegenerative disorders mediated by excess glutamate. Consequently, system xc- is a new drug target for brain cancer and neuroinflammatory diseases associated with excess extracellular glutamate. Unfortunately no potent and selective small molecule system xc- inhibitors exist and to our knowledge, no high throughput screening (HTS) assay has been developed to identify new scaffolds for inhibitor design. To develop such an assay, various neuronal and non-neuronal human cells were evaluated as sources of system xc-. Human glioma cells were chosen based on their high system xc- activity. Using these cells, [14C]-cystine uptake and cystine-induced glutamate release assays were characterized and optimized with respect to cystine and protein concentrations and time of incubation. A pilot screen of the LOPAC/NINDS libraries using glutamate release demonstrated that the logistics of the assay were in place but unfortunately, did not yield meaningful pharmacophores. A larger, HTS campaign using the 384-well cystine-induced glutamate release as primary assay and the 96-well 14C-cystine uptake as confirmatory assay is currently underway. Unexpectedly, we observed that the rate of cystine uptake was significantly faster than the rate of glutamate release in human glioma cells. This was in contrast to the same rates of

  6. Chronic desipramine prevents acute stress-induced reorganization of medial prefrontal cortex architecture by blocking glutamate vesicle accumulation and excitatory synapse increase

    DEFF Research Database (Denmark)

    Nava, Nicoletta; Treccani, Giulia; Liebenberg, Nico;

    2014-01-01

    While a clear negative influence of chronic exposure to stressful experiences has been repeatedly demonstrated, the outcome of acute stress on key brain regions has only just started to be elucidated. Although it has been proposed that acute stress may produce enhancement of brain plasticity...

  7. Reduced plasma membrane surface expression of GLAST mediates decreased glutamate regulation in the aged striatum.

    Science.gov (United States)

    Nickell, Justin; Salvatore, Michael F; Pomerleau, Francois; Apparsundaram, Subbu; Gerhardt, Greg A

    2007-11-01

    Extracellular L-glutamate poses a severe excitotoxic threat to neurons and glia when unregulated, therefore low synaptic levels of this neurotransmitter must be maintained via a rapid and robust transport system. A recent study from our laboratory showed a reduced glutamate uptake rate in the striatum of the aged Fischer 344 (F344) rat, yet the mechanism underlying this phenomenon is unknown. The current study utilized in vivo electrochemical recordings, immunoblotting and biotinylation in young (6 months), late-middle aged (18 months) and aged (24 months) F344 rats to elucidate the potential role that glutamate transporters (GLT-1, GLAST, and EAAC1) may play in this mechanism. Here we show that the time necessary to clear glutamate from the late-middle aged and aged striatum is significantly prolonged in comparison to the young striatum. In addition, an analysis of various sub-regions of the striatum revealed a marked dorsoventral gradient in terms of glutamate clearance times in the aged striatum, a phenomenon which was not present in the striatum of the animals of the remaining age groups. We also found that the decreased glutamate clearance time observed in the late-middle aged and aged rats is not due to a decrease in the production of total transporter protein among these three transporters. Rather, a significant reduction in the amount of GLAST expressed on the plasma membrane surface in the aged animals (approximately 55% when compared to young rats) may contribute to this phenomenon. These age-related alterations in extracellular l-glutamate regulation may be key contributors to the increased susceptibility of the aged brain to excitotoxic insults such as stroke and hypoxia.

  8. Ginkgolides protects cultured cortical neurons against excitotoxic and oxidative insults

    Institute of Scientific and Technical Information of China (English)

    ZHANGYu-Yang; YUQing-Hai; YOUSong; SHENGLi

    2004-01-01

    AIM: The neurotoxicity of glutamate is associated with neurological disorders including hypoxic-ischaemic brain injury. Studies using cultured cortical neurons have demonstrated that exposure to glutamate produced delayed degeneration of mature neurons. Oxygen free radicals generated during injury have been postulated to be a major cause of neuronal cell

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

    International Nuclear Information System (INIS)

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

  10. Real-time imaging of glutamate clearance reveals normal striatal uptake in Huntington disease mouse models.

    Science.gov (United States)

    Parsons, Matthew P; Vanni, Matthieu P; Woodard, Cameron L; Kang, Rujun; Murphy, Timothy H; Raymond, Lynn A

    2016-01-01

    It has become well accepted that Huntington disease (HD) is associated with impaired glutamate uptake, resulting in a prolonged time-course of extracellular glutamate that contributes to excitotoxicity. However, the data supporting this view come largely from work in synaptosomes, which may overrepresent nerve-terminal uptake over astrocytic uptake. Here, we quantify real-time glutamate dynamics in HD mouse models by high-speed imaging of an intensity-based glutamate-sensing fluorescent reporter (iGluSnFR) and electrophysiological recordings of synaptically activated transporter currents in astrocytes. These techniques reveal a disconnect between the results obtained in synaptosomes and those in situ. Exogenous glutamate uptake is impaired in synaptosomes, whereas real-time measures of glutamate clearance in the HD striatum are normal or even accelerated, particularly in the aggressive R6/2 model. Our results highlight the importance of quantifying glutamate dynamics under endogenous release conditions, and suggest that the widely cited uptake impairment in HD does not contribute to pathogenesis. PMID:27052848

  11. GSK-3 as a Target for Lithium-induced Neuroprotection against Excitotoxicity in Neuronal Cultures and Animal Models of Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    De-Maw eChuang

    2011-08-01

    Full Text Available The mood stabilizer lithium inhibits glycogen synthase kinase-3 (GSK-3 directly or indirectly by enhancing serine phosphorylation of both alpha and beta isoforms. Lithium robustly protected primary brain neurons from glutamate-induced excitotoxicity; these actions were mimicked by other GSK-3 inhibitors or silencing/inhibiting GSK-3alpha and/or beta isoforms. Lithium rapidly activated Akt to enhance GSK-3 serine phosphorylation and to block glutamate-induced Akt inactivation. Lithium also upregulated Bcl-2 and suppressed glutamate-induced p53 and Bax. Induction of BDNF was required for lithium’s neuroprotection to occur. BDNF promoter IV was activated by GSK-3 inhibition using lithium or other drugs, or through gene silencing/inactivation of either isoform. Further, lithium’s neuroprotective effects were associated with inhibition of NMDA receptor-mediated calcium influx and downstream signaling. In rodent ischemic models, post-insult treatment with lithium decreased infarct volume, ameliorated neurological deficits and improved functional recovery. Upregulation of heat shock protein 70 (HSP70 and Bcl-2 as well as downregulation of p53 likely contributed to lithium’s protective effects. Delayed treatment with lithium improved functional MRI responses, which was accompanied by enhanced angiogenesis. Two GSK-3-regulated pro-angiogenic factors, matrix metalloproteinase-9 (MMP-9 and vascular endothelial growth factor were induced by lithium. Finally, lithium promoted migration of mesenchymal stem cells (MSCs by upregulation of MMP-9 through GSK-3beta inhibition. Notably, transplantation of lithium-primed MSCs into ischemic rats enhanced MSC migration to the injured brain regions and improved the neurological performance. Several other GSK-3 inhibitors have also been reported to be beneficial in rodent ischemic models. Together, GSK-3 inhibition is a rational strategy to combat ischemic stroke and other excitotoxicity-related brain disorders.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-19

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

  13. High-level inhibition of mitochondrial complexes III and IV is required to increase glutamate release from the nerve terminal

    LENUS (Irish Health Repository)

    Kilbride, Sean M

    2011-07-26

    Abstract Background The activities of mitochondrial complex III (ubiquinol-cytochrome c reductase, EC 1.10.2.2) and complex IV (cytochrome c oxidase EC 1.9.3.1) are reduced by 30-70% in Huntington\\'s disease and Alzheimer\\'s disease, respectively, and are associated with excitotoxic cell death in these disorders. In this study, we investigated the control that complexes III and complex IV exert on glutamate release from the isolated nerve terminal. Results Inhibition of complex III activity by 60-90% was necessary for a major increase in the rate of Ca2+-independent glutamate release to occur from isolated nerve terminals (synaptosomes) depolarized with 4-aminopyridine or KCl. Similarly, an 85-90% inhibition of complex IV activity was required before a major increase in the rate of Ca2+-independent glutamate release from depolarized synaptosomes was observed. Inhibition of complex III and IV activities by ~ 60% and above was required before rates of glutamate efflux from polarized synaptosomes were increased. Conclusions These results suggest that nerve terminal mitochondria possess high reserves of complex III and IV activity and that high inhibition thresholds must be reached before excess glutamate is released from the nerve terminal. The implications of the results in the context of the relationship between electron transport chain enzyme deficiencies and excitotoxicity in neurodegenerative disorders are discussed.

  14. High-level inhibition of mitochondrial complexes III and IV is required to increase glutamate release from the nerve terminal

    Directory of Open Access Journals (Sweden)

    Kilbride Seán M

    2011-07-01

    Full Text Available Abstract Background The activities of mitochondrial complex III (ubiquinol-cytochrome c reductase, EC 1.10.2.2 and complex IV (cytochrome c oxidase EC 1.9.3.1 are reduced by 30-70% in Huntington's disease and Alzheimer's disease, respectively, and are associated with excitotoxic cell death in these disorders. In this study, we investigated the control that complexes III and complex IV exert on glutamate release from the isolated nerve terminal. Results Inhibition of complex III activity by 60-90% was necessary for a major increase in the rate of Ca2+-independent glutamate release to occur from isolated nerve terminals (synaptosomes depolarized with 4-aminopyridine or KCl. Similarly, an 85-90% inhibition of complex IV activity was required before a major increase in the rate of Ca2+-independent glutamate release from depolarized synaptosomes was observed. Inhibition of complex III and IV activities by ~ 60% and above was required before rates of glutamate efflux from polarized synaptosomes were increased. Conclusions These results suggest that nerve terminal mitochondria possess high reserves of complex III and IV activity and that high inhibition thresholds must be reached before excess glutamate is released from the nerve terminal. The implications of the results in the context of the relationship between electron transport chain enzyme deficiencies and excitotoxicity in neurodegenerative disorders are discussed.

  15. A New Transgenic Mouse Model for Studying the Neurotoxicity of Spermine Oxidase Dosage in the Response to Excitotoxic Injury.

    Directory of Open Access Journals (Sweden)

    Manuela Cervelli

    Full Text Available Spermine oxidase is a FAD-containing enzyme involved in polyamines catabolism, selectively oxidizing spermine to produce H2O2, spermidine, and 3-aminopropanal. Spermine oxidase is highly expressed in the mouse brain and plays a key role in regulating the levels of spermine, which is involved in protein synthesis, cell division and cell growth. Spermine is normally released by neurons at synaptic sites where it exerts a neuromodulatory function, by specifically interacting with different types of ion channels, and with ionotropic glutamate receptors. In order to get an insight into the neurobiological roles of spermine oxidase and spermine, we have deregulated spermine oxidase gene expression producing and characterizing the transgenic mouse model JoSMOrec, conditionally overexpressing the enzyme in the neocortex. We have investigated the effects of spermine oxidase overexpression in the mouse neocortex by transcript accumulation, immunohistochemical analysis, enzymatic assays and polyamine content in young and aged animals. Transgenic JoSMOrec mice showed in the neocortex a higher H2O2 production in respect to Wild-Type controls, indicating an increase of oxidative stress due to SMO overexpression. Moreover, the response of transgenic mice to excitotoxic brain injury, induced by kainic acid injection, was evaluated by analysing the behavioural phenotype, the immunodistribution of neural cell populations, and the ultrastructural features of neocortical neurons. Spermine oxidase overexpression and the consequently altered polyamine levels in the neocortex affects the cytoarchitecture in the adult and aging brain, as well as after neurotoxic insult. It resulted that the transgenic JoSMOrec mouse line is more sensitive to KA than Wild-Type mice, indicating an important role of spermine oxidase during excitotoxicity. These results provide novel evidences of the complex and critical functions carried out by spermine oxidase and spermine in the

  16. Hydroxysafflor Yellow A Protects Neurons From Excitotoxic Death through Inhibition of NMDARs

    Directory of Open Access Journals (Sweden)

    Xingtao Wang

    2016-04-01

    Full Text Available Excessive glutamate release causes overactivation of N-methyl d-aspartate receptors (NMDARs, leading to excitatory neuronal damage in cerebral ischemia. Hydroxysafflor yellow A (HSYA, a compound extracted from Carthamus tinctorius L., has been reported to exert a neuroprotective effect in many pathological conditions, including brain ischemia. However, the underlying mechanism of HSYA's effect on neurons remains elusive. In the present study, we conducted experiments using patch-clamp recording of mouse hippocampal slices. In addition, we performed Ca2+ imaging, Western blots, as well as mitochondrial-targeted circularly permuted yellow fluorescent protein transfection into cultured hippocampal neurons in order to decipher the physiological mechanism underlying HSYA's neuroprotective effect. Through the electrophysiology experiments, we found that HSYA inhibited NMDAR-mediated excitatory postsynaptic currents without affecting α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor and γ-aminobutyric acid A-type receptor-mediated currents. This inhibitory effect of HSYA on NMDARs was concentration dependent. HSYA did not show any preferential inhibition of either N-methyl d-aspartate receptor subtype 2A- or N-methyl d-aspartate receptor subtype 2B- subunit-containing NMDARs. Additionally, HSYA exhibits a facilitatory effect on paired NMDAR-mediated excitatory postsynaptic currents. Furthermore, HSYA reduced the magnitude of NMDAR-mediated membrane depolarization currents evoked by oxygen-glucose deprivation, and suppressed oxygen-glucose deprivation–induced and NMDAR-dependent ischemic long-term potentiation, which is believed to cause severe reperfusion damage after ischemia. Through the molecular biology experiments, we found that HSYA inhibited the NMDA-induced and NMDAR-mediated intracellular Ca2+ concentration increase in hippocampal cultures, reduced apoptotic and necrotic cell deaths, and prevented mitochondrial damage. Together

  17. 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.

  18. IL-1RAcPb signaling regulates adaptive mechanisms in neurons that promote their long-term survival following excitotoxic insults.

    Directory of Open Access Journals (Sweden)

    David eGosselin

    2013-02-01

    Full Text Available Excitotoxicity is a major component of neurodegenerative diseases and is typically accompanied by an inflammatory response. Cytokines IL-1alpha and IL-1beta are key regulators of this inflammatory response and modulate the activity of numerous cell types, including neurons. IL-1RAcPb is an isoform of IL-1RAcP expressed specifically in neurons and promotes their survival during acute inflammation. Here, we investigated in vivo whether IL-1RAcPb also promotes neuronal survival in a model of excitotoxicity. Intrastriatal injection of kainic acid in mice caused a strong induction of IL-1 cytokines mRNA in the brain. The stress response of cortical neurons at 12 hours post-injection, as measured by expression of Atf3, FoxO3a and Bdnf mRNAs, was similar in WT and AcPb-deficient mice. Importantly however, a delayed upregulation in the transcription calpastatin was significantly higher in WT than in AcPb-deficient mice. Finally, although absence of AcPb signaling had no effects on neuronal damage in the cortex at early time points, it significantly impaired their long-term survival. These data suggest that in a context of excitotoxicity, stimulation of IL-1RAcPb signaling may promote the activity of a key neuroprotective mechanism.

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

    Science.gov (United States)

    Levite, Mia

    2014-08-01

    Glutamate is the major excitatory neurotransmitter of the Central Nervous System (CNS), and it is crucially needed for numerous key neuronal functions. Yet, excess glutamate causes massive neuronal death and brain damage by excitotoxicity--detrimental over activation of glutamate receptors. Glutamate-mediated excitotoxicity is the main pathological process taking place in many types of acute and chronic CNS diseases and injuries. In recent years, it became clear that not only excess glutamate can cause massive brain damage, but that several types of anti-glutamate receptor antibodies, that are present in the serum and CSF of subpopulations of patients with a kaleidoscope of human neurological diseases, can undoubtedly do so too, by inducing several very potent pathological effects in the CNS. Collectively, the family of anti-glutamate receptor autoimmune antibodies seem to be the most widespread, potent, dangerous and interesting anti-brain autoimmune antibodies discovered up to now. This impression stems from taking together the presence of various types of anti-glutamate receptor antibodies in a kaleidoscope of human neurological and autoimmune diseases, their high levels in the CNS due to intrathecal production, their multiple pathological effects in the brain, and the unique and diverse mechanisms of action by which they can affect glutamate receptors, signaling and effects, and subsequently impair neuronal signaling and induce brain damage. The two main families of autoimmune anti-glutamate receptor antibodies that were already found in patients with neurological and/or autoimmune diseases, and that were already shown to be detrimental to the CNS, include the antibodies directed against ionotorpic glutamate receptors: the anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies and anti-NMDA-NR2 antibodies, and the antibodies directed against Metabotropic glutamate receptors: the anti-mGluR1 antibodies and the anti-mGluR5 antibodies. Each type of these anti-glutamate

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

    Science.gov (United States)

    Levite, Mia

    2014-08-01

    Glutamate is the major excitatory neurotransmitter of the Central Nervous System (CNS), and it is crucially needed for numerous key neuronal functions. Yet, excess glutamate causes massive neuronal death and brain damage by excitotoxicity--detrimental over activation of glutamate receptors. Glutamate-mediated excitotoxicity is the main pathological process taking place in many types of acute and chronic CNS diseases and injuries. In recent years, it became clear that not only excess glutamate can cause massive brain damage, but that several types of anti-glutamate receptor antibodies, that are present in the serum and CSF of subpopulations of patients with a kaleidoscope of human neurological diseases, can undoubtedly do so too, by inducing several very potent pathological effects in the CNS. Collectively, the family of anti-glutamate receptor autoimmune antibodies seem to be the most widespread, potent, dangerous and interesting anti-brain autoimmune antibodies discovered up to now. This impression stems from taking together the presence of various types of anti-glutamate receptor antibodies in a kaleidoscope of human neurological and autoimmune diseases, their high levels in the CNS due to intrathecal production, their multiple pathological effects in the brain, and the unique and diverse mechanisms of action by which they can affect glutamate receptors, signaling and effects, and subsequently impair neuronal signaling and induce brain damage. The two main families of autoimmune anti-glutamate receptor antibodies that were already found in patients with neurological and/or autoimmune diseases, and that were already shown to be detrimental to the CNS, include the antibodies directed against ionotorpic glutamate receptors: the anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies and anti-NMDA-NR2 antibodies, and the antibodies directed against Metabotropic glutamate receptors: the anti-mGluR1 antibodies and the anti-mGluR5 antibodies. Each type of these anti-glutamate

  1. BDNF heightens the sensitivity of motor neurons to excitotoxic insults through activation of TrkB

    Science.gov (United States)

    Hu, Peter; Kalb, Robert G.; Walton, K. D. (Principal Investigator)

    2003-01-01

    The survival promoting and neuroprotective actions of brain-derived neurotrophic factor (BDNF) are well known but under certain circumstances this growth factor can also exacerbate excitotoxic insults to neurons. Prior exploration of the receptor through which BDNF exerts this action on motor neurons deflects attention away from p75. Here we investigated the possibility that BDNF acts through the receptor tyrosine kinase, TrkB, to confer on motor neurons sensitivity to excitotoxic challenge. We blocked BDNF activation of TrkB using a dominant negative TrkB mutant or a TrkB function blocking antibody, and found that this protected motor neurons against excitotoxic insult in cultures of mixed spinal cord neurons. Addition of a function blocking antibody to BDNF to mixed spinal cord neuron cultures is also neuroprotective indicating that endogenously produced BDNF participates in vulnerability to excitotoxicity. We next examined the intracellular signaling cascades that are engaged upon TrkB activation. Previously we found that inhibition of the phosphatidylinositide-3'-kinase (PI3'K) pathway blocks BDNF-induced excitotoxic sensitivity. Here we show that expression of a constitutively active catalytic subunit of PI3'K, p110, confers excitotoxic sensitivity (ES) upon motor neurons not incubated with BDNF. Parallel studies with purified motor neurons confirm that these events are likely to be occuring specifically within motor neurons. The abrogation of BDNF's capacity to accentuate excitotoxic insults may make it a more attractive neuroprotective agent.

  2. 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

  3. Glutamate receptor agonists

    DEFF Research Database (Denmark)

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

    2011-01-01

    The neurotransmitter (S)-glutamate [(S)-Glu] is responsible for most of the excitatory neurotransmission in the central nervous system. The effect of (S)-Glu is mediated by both ionotropic and metabotropic receptors. Glutamate receptor agonists are generally a-amino acids with one or more...... stereogenic centers due to strict requirements in the agonist binding pocket of the activated state of the receptor. By contrast, there are many examples of achiral competitive antagonists. The present review addresses how stereochemistry affects the activity of glutamate receptor ligands. The review focuses...

  4. Cellular prion protein and NMDA receptor modulation: protecting against excitotoxicity

    Directory of Open Access Journals (Sweden)

    Stefanie A.G. Black

    2014-08-01

    Full Text Available Although it is well established that misfolding of the cellular prion protein (PrPC into the beta-sheet-rich, aggregated scrapie conformation (PrPSc causes a variety of transmissible spongiform encephalopathies (TSEs, the physiological roles of PrPC are still incompletely understood. There is accumulating evidence describing the roles of PrPC in neurodegeneration and neuroinflammation. Recently, we identified a functional regulation of NMDA receptors by PrPC that involves formation of a physical protein complex between these proteins. Excessive NMDA receptor activity during conditions such as ischemia mediates enhanced Ca2+ entry into cells and contributes to excitotoxic neuronal death. In addition, NMDA receptors and/or PrPC play critical roles in neuroinflammation and glial cell toxicity. Inhibition of NMDA receptor activity protects against PrPSc-induced neuronal death. Moreover, in mice lacking PrPC, infarct size is increased after focal cerebral ischemia, and absence of PrPC increases susceptibility of neurons to NMDA receptor-dependent death. Recently, PrPC was found to be a receptor for oligomeric beta-amyloid (Abeta peptides, suggesting a role for PrPC in Alzheimer’s disease. Our recent findings suggest that Abeta peptides enhance NMDA receptor current by perturbing the normal copper- and PrPC-dependent regulation of these receptors. Here, we review evidence highlighting a role for PrPC in preventing NMDA receptor-mediated excitotoxicity and inflammation. There is a need for more detailed molecular characterization of PrPC-mediated regulation of NMDA receptors, such as determining which NMDA receptor subunits mediate pathogenic effects upon loss of PrPC-mediated regulation and identifying PrPC binding site(s on the receptor. This knowledge will allow development of novel therapeutic interventions for not only TSEs, but also for Alzheimer’s disease and other neurodegenerative disorders involving dysfunction of PrPC.

  5. Glutamate Receptors in Plants

    OpenAIRE

    Davenport, Romola

    2002-01-01

    Ionotropic glutamate receptors function in animals as glutamate‐gated non‐selective cation channels. Numerous glutamate receptor‐like (GLR) genes have been identified in plant genomes, and plant GLRs are predicted, on the basis of sequence homology, to retain ligand‐binding and ion channel activity. Non‐selective cation channels are ubiquitous in plant membranes and may function in nutrient uptake, signalling and intra‐plant transport. However, there is little evidence for amino acid gating o...

  6. Glutamate Transmission in Addiction

    OpenAIRE

    Kalivas, Peter W.; LaLumiere, Ryan; Knackstedt, Lori; Shen, Haowei

    2008-01-01

    Cortico-striatal glutamate transmission has been implicated in both the initiation and expression of addiction related behaviors, such as locomotor sensitization and drug seeking. While glutamate transmission onto dopamine cells in the ventral tegmental area undergoes transient plasticity important for establishing addiction-related behaviors, glutamatergic plasticity in the nucleus accumbens is critical for the expression of these behaviors. This information points to the value of exploring ...

  7. Differentiation renders susceptibility to excitotoxicity in HT22 neurons

    Institute of Scientific and Technical Information of China (English)

    Minchao He; Jun Liu; Shaowu Cheng; Yigang Xing; William Z Suo

    2013-01-01

    HT22 is an immortalized mouse hippocampal neuronal cell line that does not express cholinergic and glutamate receptors like mature hippocampal neurons in vivo. This in part prevents its use as a model for mature hippocampal neurons in memory-related studies. We now report that HT22 cells were appropriately induced to differentiate and possess properties similar to those of mature hippocampal neurons in vivo, such as becoming more glutamate-receptive and excitatory. Results showed that sensitivity of HT22 cells to glutamate-induced toxicity changed dramatically when comparing undifferentiated with differentiated cells, with the half-effective concentration for differentiated cells reducing approximately two orders of magnitude. Moreover, glutamate-induced toxicity in differentiated cells, but not undifferentiated cells, was inhibited by the N-methyl-D- aspartate receptor antagonists MK-801 and memantine. Evidently, differentiated HT22 cells expressed N-methyl-D-aspartate receptors, while undifferentiated cells did not. Our experimental findings indicated that differentiation is important for immortalized cell lines to render post-mitotic neuronal properties, and that differentiated HT22 neurons represent a better model of hippocampal neurons than undifferentiated cells.

  8. Nerve growth factor protects cholinergic neurons against quinolinic acid-induced excitotoxicity in wistar rats

    OpenAIRE

    Vasiljević Ivana D.; Jovanović Marina D.; Čolić Miodrag J.; Mićić D.; Ninković Milica; Maličević Živorad

    2004-01-01

    The etiology of neuronal death in neurodegenerative diseases, including Huntington's disease (HD) is still unknown. There could be a complex interplay between altered energy metabolism, excitotoxicity and oxidative stress. Excitotoxic striatal lesions induced by quinolinic acid (QA), were used to test for the neuroprotective actions of nerve growth factor (NGF) on striatal cholinergic and GABAergic neurons. QA is an endogenous excitotoxin acting on N-methyl-D-aspartate (NMDA) rec...

  9. Mitochondrial calcium uniporter Mcu controls excitotoxicity and is transcriptionally repressed by neuroprotective nuclear calcium signals.

    Science.gov (United States)

    Qiu, Jing; Tan, Yan-Wei; Hagenston, Anna M; Martel, Marc-Andre; Kneisel, Niclas; Skehel, Paul A; Wyllie, David J A; Bading, Hilmar; Hardingham, Giles E

    2013-01-01

    The recent identification of the mitochondrial Ca(2+) uniporter gene (Mcu/Ccdc109a) has enabled us to address its role, and that of mitochondrial Ca(2+) uptake, in neuronal excitotoxicity. Here we show that exogenously expressed Mcu is mitochondrially localized and increases mitochondrial Ca(2+) levels following NMDA receptor activation, leading to increased mitochondrial membrane depolarization and excitotoxic cell death. Knockdown of endogenous Mcu expression reduces NMDA-induced increases in mitochondrial Ca(2+), resulting in lower levels of mitochondrial depolarization and resistance to excitotoxicity. Mcu is subject to dynamic regulation as part of an activity-dependent adaptive mechanism that limits mitochondrial Ca(2+) overload when cytoplasmic Ca(2+) levels are high. Specifically, synaptic activity transcriptionally represses Mcu, via a mechanism involving the nuclear Ca(2+) and CaM kinase-mediated induction of Npas4, resulting in the inhibition of NMDA receptor-induced mitochondrial Ca(2+) uptake and preventing excitotoxic death. This establishes Mcu and the pathways regulating its expression as important determinants of excitotoxicity, which may represent therapeutic targets for excitotoxic disorders.

  10. Cerebrovascular Acute Radiation Syndrome : Radiation Neurotoxins, Mechanisms of Toxicity, Neuroimmune Interactions.

    Science.gov (United States)

    Popov, Dmitri; Maliev, Slava

    . Radiation Toxins (SRD-1)had been isolated from Central Lymph of irradiated animals (cows, sheep, pigs). Experiments to study toxicity of Radiation Neurotoxins had been performed. Intravenous (IV) and intramuscular (IM) administration of RT SRD-1 to radiation naive animals had induced acute toxicity which referred to the harmful effects generated by high doses of radiation. In-jection of toxic doses of RT SRD-1 (Toxic doses: 0,1 mg/kg, 0,5mg/kg, 1 mg/kg, 10mg/kg,30 mg/kg, 50mg/kg,70 mg/kg,100 mg/kg, 110mg/kg)were compared to the similar effects caused by high doses of radiation. Results: Injection of SRD-1 ( Neurotoxin Cv ARS)of all ten tested toxic doses had caused a death of radiation naive animals within the first hours after admin-istration of toxins. For all animals in all experiments, a short period of extreme agitation was replaced by deep coma, and suppression of blood circulation and breathing. The results of postmortem section had showed characteristics of intra-cortical hemorrhage. Conclusions: Acute radiation injury induces a disorder of blood supply of the Central Nervous System (CNS). However, administration of SRD-1 Radiation Toxins to radiation naive animals produces crit-ically important inflammatory reactions with hemorrhagic stroke development. Neurotoxicity and Excitotoxicity are two stages of the pathological processes resulted in damaging and killing nerve cells thorough apoptotic necrosis. Excitotoxicity is well known as a pathological process that occurs when important excitatory neurotransmitters (glutamate, serotonin) over-activate the receptors -NMDA, AMPA, 5HT1, 5HT2, 5H3. Radiation Neurotoxins possibly act on the same receptors and activate the cell death mechanisms through direct or indirect excessive activation of same receptors.

  11. A comparison of some metabolic effects of N-methylaspartate stereoisomers, glutamate and depolarization: a multinuclear MRS study.

    Science.gov (United States)

    Thatcher, N M; Badar-Goffer, R S; Ben-Yoseph, O; McLean, M A; Morris, P G; Prior, M J W; Taylor, A; Bachelard, H S

    2002-02-01

    Exposure of guinea pig brain slices to low concentrations (10 microM) of NMDA caused decreases in PCr and ATP within 30 min, with a slower decrease in NAA and increase in lactate, both detectable after 1 h. Exposure to NMDA for over 1 h or at higher concentrations caused further increases in lactate and decreases in NAA, with no further change in PCr or ATP. The L-isomer, NMLA, and the racemic mixture, NMDLA, caused similar changes in lactate and NAA, but both produced greater decreases in the energy state than NMDA, similar to those caused by prolonged exposure to glutamate. MK-801 prevented the changes in the energy state caused by NMDA, but not those caused by NMLA or by glutamate. The results are compared to previous studies on depolarization and discussed in terms of the role of the NMDA sub-type of glutamate receptor in the excitotoxic hypothesis of neuronal degeneration.

  12. Effect of glutamate on inflammatory responses of intestine and brain after focal cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Lei Xu; Jie Sun; Ran Lu; Qing Ji; Jian-Guo Xu

    2005-01-01

    AIM: To study the modulation of glutamate on post-ischemic intestinal and cerebral inflammatory responses in a ischemic and excitotoxic rat model.METHODS: Adult male rats were subjected to bilateral carotid artery occlusion for 15 min and injection of monosodium glutamate intraperitoneally, to decapitate them at selected time points. Tumor necrosis factor alpha (TNF-α) level and nuclear factor kappa B (NF-κB) activity were determined by enzyme-linked immunosorbant assay (ELISA) and electrophoretic mobility shift assay (EMSA), respectively.Hemodynamic parameters were monitored continuously during the whole process of cerebral ischemia and reperfusion.RESULTS: Monosodium glutamate (MSG) treated rats displayed statistically significant high levels of TNF-α in cerebral and intestinal tissuess within the first 6 h of ischemia. The rats with cerebral ischemia showed a minor decrease of TNF-α production in cerebral and intestinal tissuess. The rats with cerebral ischemia and treated with MSG displayed statistically significant low levels of TNF-α in cerebral and intestinal tissues. These results correlated significantly with NF-κB production calculated at the same intervals. During experiment, the mean blood pressure and heart rates in all groups were stable.CONCLUSION: Glutamate is involved in the mechanism of intestinal and cerebral inflammation responses. The effects of glutamate on cerebral and intestinal inflammatory responses after ischemia are up-regulated at the transcriptional level,through the NF-κB signal transduction pathway.

  13. Glutamine synthetase activity and glutamate uptake in hippocampus and frontal cortex in portal hypertensive rats

    Institute of Scientific and Technical Information of China (English)

    Gabriela Beatriz Acosta; María Alejandra Fernández; Diego Martín Roselló; María Luján Tomaro; Karina Balestrasse; Abraham Lemberg

    2009-01-01

    AIM: To study glutamine synthetase (GS) activity and glutamate uptake in the hippocampus and frontal cortex (FC) from rats with prehepatic portal vein hypertension. METHODS: Male Wistar rats were divided into shamoperated group and a portal hypertension (PH) group with a regulated stricture of the portal vein. Animals were sacrificed by decapitation 14 d after portal vein stricture. GS activity was determined in the hippocampus and FC. Specific uptake of radiolabeled L-glutamate was studied using synaptosome-enriched fractions that were freshly prepared from both brain areas. RESULTS: We observed that the activity of GS increased in the hippocampus of PH rats, as compared to control animals, and decreased in the FC. A significant decrease in glutamate uptake was found in both brain areas, and was more marked in the hippocampus. The decrease in glutamate uptake might have been caused by a deficient transport function, significantly and persistent increase in this excitatory neurotransmitter activity. CONCLUSION: The presence of moderate ammonia blood levels may add to the toxicity of excitotoxic glutamate in the brain, which causes alterations in brain function. Portal vein stricture that causes portal hypertension modifies the normal function in some brain regions.

  14. Neuroprotective Activity of Pongamia pinnata in Monosodium Glutamate-induced Neurotoxicity in Rats.

    Science.gov (United States)

    Swamy, A H M Viswanatha; Patel, N L; Gadad, P C; Koti, B C; Patel, U M; Thippeswamy, A H M; Manjula, D V

    2013-11-01

    This study was designed to evaluate the neuroprotective activity of ethanol extract of Pongamia pinnata stem bark in monosodium glutamate-induced neurotoxicity in rats. Neurotoxicity was induced by intraperitoneal injection of monosodium glutamate 2 g per kg body weight daily for 7 days. Ethanol extract of Pongamia pinnata stem bark (200 and 400 mg/kg) was administered orally after 1 h of monosodium glutamate treatment. Dextromethorphan (30 mg/kg, p.o.) was used as standard drug for the comparison. The degree of protection was determined by various behavioural, locomotor, muscle grip activity, lipid peroxidation and measurement of antioxidant status of glutathione, catalase and superoxide dismutase. Estimation of calcium, sodium and potassium ions in brain tissue and gamma aminobutyric acid level in serum was carried out. The histopathological study of brain tissue was also carried out. Treatment with Pongamia pinnata significantly improved monosodium glutamate-induced alteration in behavioural and locomotor activity and muscle strength. Significant decrease in lipid peroxidation and increase in glutathione, superoxide dismutase and catalase was observed in Pongamia pinnata treated group. Further, Pongamia pinnata also significantly reduced the monosodium glutamate-induced excitotoxicity by decreasing the level of Ca(+2) and Na(+) with concomitant increase in the level of K(+). Serum gamma aminobutyric acid level was also increased in Pongamia pinnata treated animals. Further, the histopathological evidence supports the neuroprotective activity of Pongamia pinnata. In conclusion, the present study suggests that the ethanol extract of stem bark of Pongamia pinnata possesses significant neuroprotective activity in albino rats.

  15. Infant guinea pig retina model of glutamate toxicity and intervention of basic fibroblast growth factor

    Institute of Scientific and Technical Information of China (English)

    Yunzhi Shi; Lihua Wei; Mingshan Song; Min Chen; Changqing Du; Baoliang Sun

    2011-01-01

    Impaired vision with oligemic ophthalmopathy is a result of excitotoxicity caused by excitatory amino acids, resulting in pathological changes, such as loss of retinal neurons and in particular retinal ganglionic cells. The present study utilized infant guinea pigs, aged 45-50 days, to establish injury models via intrapedtoneal injection of fixed sodium glutamate doses. Results from hematoxylin- eosin staining revealed significantly reduced retinal ganglionic cell numbers and retinal damage at 10 days after 7 consecutive days of 3 g/kg sodium glutamate treatment; these animals sewed as the injury model group. In addition, models of moderate injury (glutamate 3 g/kg daily, for 7 consecutive days) were intrapedtoneally pretreated with basic fibroblast growth factor (800 U/kg daily). Immunohistochemistry results confirmed reduced anti-apoptotic gene bcl-2 expression in the ganglion cell layer of glutamate-injured guinea pigs. Expression of the pro-apoptotic gene caspase-3 was increased in the ganglion cell layer and inner plexiform layer. Somatostatin expression was primadly distributed in the ganglion cell layer and inner nuclear layer. Expression of the presynaptic element synaptophysin was weak. However, following basic fibroblast growth factor injection, expressions of the above-described bioactive molecules were reversed, which suggested that basic fibroblast growth factor exerted protective effects on sodium glutamate-induced retinal injury in infant guinea pigs by regulating expression of synaptophysin, somatostatin, Bcl-2, and caspase-3.

  16. Polysaccharides purified from Cordyceps cicadae protects PC12 cells against glutamate-induced oxidative damage.

    Science.gov (United States)

    Olatunji, Opeyemi J; Feng, Yan; Olatunji, Oyenike O; Tang, Jian; Wei, Yuan; Ouyang, Zhen; Su, Zhaoliang

    2016-11-20

    Two polysaccharides CPA-1 and CPB-2 were isolated purified from Cordyceps cicadae by hot water extraction, ethanol precipitation and purification using anion exchange and gel filtration chromatography. Preliminary structural characterization of CPA-1 and CPB-2 were performed. The protective effect of CPA-1 and CPB-2 against glutamate-induced oxidative toxicity in PC12 cells was analyzed. The results indicated that pretreatment of PC12 cells with CPA-1 and CPB-2 significantly increased cell survival, Ca(2+) overload and ROS generation. CPA-1 and CPB-2 also markedly up-regulated the antioxidant status of pretreated PC12 cells. Our results suggested that Cordyceps cicadae polysaccharides can protect PC12 cells against glutamate excitotoxicity and might serve as therapeutic agents for neuronal disorders. PMID:27561486

  17. Perspectives on neuroinflammation and excitotoxicity: a neurotoxic conspiracy?

    Science.gov (United States)

    Viviani, Barbara; Boraso, Mariaserena; Marchetti, Natalia; Marinovich, Marina

    2014-07-01

    Emerging evidences underline the ability of several environmental contaminants to induce an inflammatory response within the central nervous system, named neuroinflammation. This can occur as a consequence of a direct action of the neurotoxicant to the CNS and/or as a response secondary to the activation of the peripheral inflammatory response. In both cases, neuroinflammation is driven by the release of several soluble factors among which pro-inflammatory cytokines. IL-1β and TNF-α have been extensively studied for their effects within the CNS and emerged for their role in the modulation of the neuronal response, which allow the immune response to integrate with specific neuronal functions, as neurotransmission and synaptic plasticity. In particular, it has been evidenced a potential detrimental link between these cytokines and the glutamatergic system that seems to be part of increased brain excitability and excitotoxicity occurring in different pathological conditions. Aim of this mini-review will be to present experimental evidence on the way IL-1β and TNF-α impact neurons, focusing on the glutamatergic signalling, to provide a perspective on novel pathways possibly involved in environmental contaminants neurotoxicity. PMID:24662010

  18. Adenosine A2B receptor-mediated leukemia inhibitory factor release from astrocytes protects cortical neurons against excitotoxicity

    Directory of Open Access Journals (Sweden)

    Moidunny Shamsudheen

    2012-08-01

    Adenosine from glutamate-stressed neurons induces rapid LIF release in astrocytes. This rapid release of LIF promotes the survival of cortical neurons against excitotoxicity.

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

    Science.gov (United States)

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

    2016-08-15

    Traumatic spinal cord injury (SCI) leads to a cascade of secondary chemical insults, including oxidative stress and glutamate excitotoxicity, which damage host neurons and glia. Transplantation of exogenous neural stem/progenitor cells (NSPCs) has shown promise in enhancing regeneration after SCI, although survival of transplanted cells remains poor. Understanding the response of NSPCs to the chemical mediators of secondary injury is essential in finding therapies to enhance survival. We examined the in vitro effects of glutamate and glutamate receptor agonists on adult rat spinal cord-derived NSPCs. NSPCs isolated from the periventricular region of the adult rat spinal cord were exposed to various concentrations of glutamate for 96 h. We found that glutamate treatment (500 μM) for 96 h significantly increased live cell numbers, reduced cell death, and increased proliferation, but did not significantly alter cell phenotype. Concurrent glutamate treatment (500 μM) in the setting of H2O2 exposure (500 μM) for 10 h increased NSPC survival compared to H2O2 exposure alone. The effects of glutamate on NSPCs were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist GYKI-52466, but not by the N-methyl-D-aspartic acid receptor antagonist MK-801 or DL-AP5, or the mGluR3 antagonist LY-341495. Furthermore, treatment of NSPCs with AMPA, kainic acid, or the kainate receptor-specific agonist (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid mimicked the responses seen with glutamate both alone and in the setting of oxidative stress. These findings offer important insights into potential mechanisms to enhance NSPC survival and implicate a potential role for glutamate in promoting NSPC survival and proliferation after traumatic SCI. PMID:27316370

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    Cultured astrocytes treated with siRNA to knock down glutamate dehydrogenase (GDH) were used to investigate whether this enzyme is important for the utilization of glutamate as an energy substrate. By incubation of these cells in media containing different concentrations of glutamate (range 100......-500 µM) in the presence or in the absence of glucose, the metabolism of these substrates was studied by using tritiated glutamate or 2-deoxyglucose as tracers. In addition, the cellular contents of glutamate and ATP were determined. The astrocytes were able to maintain physiological levels of ATP...

  1. Distribution of radiolabeled L-glutamate and D-aspartate from blood into peripheral tissues in naive rats: Significance for brain neuroprotection

    Energy Technology Data Exchange (ETDEWEB)

    Klin, Yael [Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100 (Israel); Zlotnik, Alexander; Boyko, Matthew; Ohayon, Sharon; Shapira, Yoram [The Division of Anesthesiology, Soroka Medical Center and Ben Gurion University of the Negev, Beer-Sheva (Israel); Teichberg, Vivian I., E-mail: Vivian.teichberg@weizmann.ac.il [Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100 (Israel)

    2010-09-03

    Research highlights: {yields} Blood glutamate has a half-life time of 2-3 min. {yields} Blood glutamate is submitted to rapid decarboxylation. {yields} Blood glutamate and its metabolites are mainly absorbed in skeletal muscle and liver. {yields} The skeletal muscle and liver are now targets for potential drugs affording brain neuroprotection. -- Abstract: Excess L-glutamate (glutamate) levels in brain interstitial and cerebrospinal fluids (ISF and CSF, respectively) are the hallmark of several neurodegenerative conditions such as stroke, traumatic brain injury or amyotrophic lateral sclerosis. Its removal could prevent the glutamate excitotoxicity that causes long-lasting neurological deficits. As in previous studies, we have established the role of blood glutamate levels in brain neuroprotection, we have now investigated the contribution of the peripheral organs to the homeostasis of glutamate in blood. We have administered naive rats with intravenous injections of either L-[1-{sup 14}C] Glutamic acid (L-[1-{sup 14}C] Glu), L-[G-{sup 3}H] Glutamic acid (L-[G-{sup 3}H] Glu) or D-[2,3-{sup 3}H] Aspartic acid (D-[2,3-{sup 3}H] Asp), a non-metabolized analog of glutamate, and have followed their distribution into peripheral organs. We have observed that the decay of the radioactivity associated with L-[1-{sup 14}C] Glu and L-[G-{sup 3}H] Glu was faster than that associated with glutamate non-metabolized analog, D-[2,3-{sup 3}H] Asp. L-[1-{sup 14}C] Glu was subjected in blood to a rapid decarboxylation with the loss of {sup 14}CO{sub 2}. The three major sequestrating organs, serving as depots for the eliminated glutamate and/or its metabolites were skeletal muscle, liver and gut, contributing together 92% or 87% of total L-[U-{sup 14}C] Glu or D-[2,3-{sup 3}H] Asp radioactivity capture. L-[U-{sup 14}C] Glu and D-[2,3-{sup 3}H] Asp showed a different organ sequestration pattern. We conclude that glutamate is rapidly eliminated from the blood into peripheral tissues

  2. Neuroprotective effects of 20(S)-protopanaxadiol against glutamate-induced mitochondrial dysfunction in PC12 cells.

    Science.gov (United States)

    Bak, Dong-Ho; Kim, Hyung Don; Kim, Young Ock; Park, Chun Geun; Han, Seung-Yun; Kim, Jwa-Jin

    2016-02-01

    Ginseng (Panax ginseng C.A. Mey.) is commonly used in traditional oriental medicine for its wide spectrum of medicinal properties, including anti-inflammatory, antitumorigenic, adaptogenic and anti-aging properties. 20(S)-Protopanaxadiol (PPD), the main intestinal metabolite of ginsenosides, is one of the active ingredients in ginseng. In this study, we aimed to investigate the neuroprotective effects of PPD on PC12 cells; however, the underlying mechanisms remain elusive. We examined cell viability by MTT assay and the morphological changes of PC12 cells following glutamate‑induced cell damage and evaluated the anti‑apoptotic effects of PPD using Hoechst 33258 staining, western blot analysis and Muse™ Cell Analyzer and the antioxidant effects of PPD using FACS analysis and immunofluorescence. Furthermore, PPD exerted protective effects on PC12 cells via the inhibition of mitochondrial damage against glutamate-induced excitotoxicity using immunofluorescence, electron microscopy and FACS analysis. We demonstrate that treatment with PPD suppresses apoptosis, which contributes to the neuroprotective effects of PPD against glutamate‑induced excitotoxicity in PC12 cells. Treatment with PPD inhibited nuclear condensation and decreased the number of Annexin V-positive cells. In addition, PPD increased antioxidant activity and mitochondrial homeostasis in the glutamate-exposed cells. These antioxidant effects were responsible for the neuroprotection and enhanced mitochondrial function following treatment with PPD. Furthermore, PD inhibited the glutamate-induced morphological changes in the mitochondria and scavenged the mitochondrial and cytosolic reactive oxygen species (ROS) induced by glutamate. In addition, mitochondrial function was significantly improved in terms of mitochondrial membrane potential (MMP) and enhanced mitochondrial mass compared with the cells exposed to glutamate and not treated with PPD. Taken together, the findings of our study indicate

  3. Expressions of caspase-3, Tunel, and Hsp72 immunoreactivities in cultured spinal cord neurons of rat after exposure to glutamate, nitric oxide, or peroxynitrite.

    Science.gov (United States)

    Manabe, Y; Wang, J; Warita, H; Shiro, Y; Abe, K

    2001-07-01

    Although excitotoxic and oxidative stress play important roles in spinal neuron death, the exact mechanisms are not fully understood. We examined cell damage of primary culture of 11 day-old rat spinal cord by addition of glutamate, nitric oxice (NO) or peroxynitrite (PN) with detection of caspase-3, terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) or 72 kDa heat shock protein (HSP72). With addition of glutamate, NOC18 (a slow NO releaser) or PN, immunoreactivity for caspase-3 became stronger in the cytoplasm of large motor neurons in the ventral horn at 6 to 24 hr. TUNEL positive nuclei were found in spinal large motor neurons from 24 h and the positive cell proportion greatly increased at 48 h in contrast to the vehicle. On the other hand, the immunoreactivity of HSP72 in the ventral horn was already positive at 0 h, and gradually decreased in the course of time with glutamate, NOC18 or PN than vehicle treatment. In the dorsal horn, the proportion of caspase-3 positive small neurons greatly increased at 6 to 48 h after addition of glutamate. The present results suggest that both excitotoxic and oxidative stress play important roles in the apoptotic pathway in cultured spinal neurons. PMID:15111253

  4. No release of interstitial glutamate in experimental human model of muscle pain

    DEFF Research Database (Denmark)

    Ashina, M.; Jørgensen, M.; Stallknecht, Bente;

    2005-01-01

    Glutamate may be released from muscle nociceptors and thereby contribute to mechanisms underlying acute and chronic muscle pain. In vivo concentration of glutamate during muscle pain has not previously been studied in either animals or humans. In the present study, we aimed to study the in vivo...... flow increased significantly over time in response to infusion of chemical mixture and placebo (p = 0.001). However, we found no difference in changes in muscle blood flow between chemical mixture and placebo (p > 0.05). In conclusion, the present study demonstrates no signs of increased release...... of glutamate from myofascial nociceptors during and after acute experimentally induced muscle pain and tenderness....

  5. Comparison of excitotoxic profiles of ATPA, AMPA, KA and NMDA in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, J; Zimmer, J

    2001-01-01

    The excitotoxic profiles of (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propionic acid (ATPA), (RS)-2-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), kainic acid (KA) and N-methyl-D-aspartate (NMDA) were evaluated using cellular uptake of propidium iodide (PI) as a measure for...

  6. Icariin, a major constituent from Epimedium brevicornum, attenuates ibotenic acid-induced excitotoxicity in rat hippocampus.

    Science.gov (United States)

    Zong, Nan; Li, Fei; Deng, Yuanyuan; Shi, Jingshan; Jin, Feng; Gong, Qihai

    2016-10-15

    Excitotoxicity is one of the most extensively studied causes of neuronal death and plays an important role in Alzheimer's disease (AD). Icariin is a flavonoid component of a traditional Chinese medicine reported to possess a broad spectrum of pharmacological effects. The present study was designed to investigate the effects of icariin against learning and memory impairment induced by excitotoxicity. Here, we demonstrated that rats receiving intracerebroventricular injection of excitatory neurotoxin ibotenic acid exhibited impaired learning and memory. Oral administration of icariin at doses of 20 and 40mg/kg rescued behavioral performance and protected against neurotoxicity in rat hippocampus by suppressing ibotenic acid induced pro-apoptosis. Furthermore, Western blott of hippocampal specimens revealed that icariin up-regulated the expression of calbindin-D28k protein following ibotenic acid administration. Additionally, icariin inhibited mitogen-activated protein kinase (MAPK) family phosphorylation and nuclear factor kappa B (NF-κB) signaling, implicating the MAPK signaling and NF-κB signaling pathways were involved in the mechanism underlying icariin-mediated neuroprotection against ibotenic acid-induced excitotoxicity. These data suggested that icariin could be a potential agent for treatment of excitotoxicity-related diseases, including AD. PMID:27368415

  7. Involvement of mitogen-activated protein kinase pathways in N-methyl-D-aspartate-induced excitotoxicity

    Institute of Scientific and Technical Information of China (English)

    Xiaorong Yang; Ping Sun; Huaping Qin; Rui Wang; Ye Wang; Ruihong Shi; Xin Zhao; Ce Zhang

    2011-01-01

    Previous studies have shown that mitogen-activated protein kinase (MAPK) signaling pathways are involved in N-methyl-D-aspartate (NMDA)-mediated excitotoxicity. However, a systematic observation or analysis of the role of these various MAPK pathways in excitotoxicity processes does not exist. The present study further evaluated the role and contribution of three MAPK pathways extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAPK in an NMDA-mediated excitotoxicity model using MAPK-specific inhibitor. Results demonstrated that c-Jun N-terminal kinase inhibitor SP600125 and/or p38 MAPK inhibitor SB203580 inhibited NMDA-induced reduction in cell viability, as well as reduced NMDA-induced lactate dehydrogenase leakage and reactive oxygen species production. However, PD98059, an inhibitor of extracellular signal-regulated kinase, did not influence this model. Results demonstrated an involvement of c-Jun N-terminal kinase and p38 MAPK, but not extracellular signal-regulated kinase, in NMDA-mediated excitotoxicity in cortical neurons.

  8. EXPRESSION OF BAX AND BCL-2 IN MOUSE OFFSPRING BRAIN AFTER MATERNAL ORAL ADMINIS TRATION OF MONOSODIUM GLUTAMATE

    Institute of Scientific and Technical Information of China (English)

    徐磊; 赵晏; 展淑琴; 王会生; 史文春

    2002-01-01

    Objective To analyze the excitotoxicity of monoso dium glutamate (MSG) in the offspring cerebral cortex and hippocampal subregions after maternal oral administration of MSG. Methods Kunming mi ce were given per os MSG ( 4.0 g/kg ) at 17~21 days of pregnancy and their offs pring behaviors were studied at 10, 20 , 30 days postnatally. By using immunohis tochemical means, the involvement of Bcl-2 and Bax in the glutamate-induced c ell death in cortical and hippocampal neur ons were examined. Cell damage was assessed by direct cell counting. Res ults Administration of monosodium glutamate during the fetal period in mice resulted in a moderate increase in the expression of Bax in principal neuro ns in CA1, CA2, CA3, CA4 and in the cerebral cortex at postpartum 10, 20, 30 day s in the offspring mice, whereas Bcl-2 protein expressions were reduced signif icantly in the same regions as compared with those of controls. Conclusi on These findings suggest that glutamate toxicity results in cellular d eath via an apoptotic mechanism in which the Bcl-2/Bax-alpha molecular comple x may be involved. The glutamate-induced apoptosis appears to be related to the modulation of Bcl-2 family gene products such as Bcl-2 and Bax.

  9. EXPRESSION OF BAX AND BCL-2 IN MOUSE OFFSPRING BRAIN AFIER MATERNAL ORAL ADMINISTRATION OF MONOSODIUM GLUTAMATE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective:To analyze the excitotoxicity of monosodium glutamate(MSG)in the offspring crebral cortex and hippocampal subresions after maternal oral administration of MSG.Methods:Kunming mice were given per os MSG(4.0g/kg)at 17-21 days of pregnancy and their offspring behaviors were studied at 10,20,30days postnatally.By using inmunohistochemical means,the involvment of Bcl-2 and bax in the glutamate-induced cell death in cortical and hippocampal neurons were examined.Cell damage was assessed by direct cell counting.Results:administration of monosodium glutamate during the fetal period in mice resulted in a moderate increase in the expression of Bax in principal neurons in CA1,CA2,CA3,CA4 and in the cerebral cortex at postpartum 10,20,30 days in the offspring mice,whereas Bcl-2 protein expressions were reduced significantly in the same regions as compared with those of controls.Conclusion:These findings suggest that glutamate toxicity results in cellular death via an apoptotic mechanism in which the Bcl-2/Bax-alpha molecular complex may be involved.The glutamate-induced apoptosis appears to be related to the modulation of Bcl-2 family gene products such as Bcl-2 and Bax.

  10. Augmentation of normal and glutamate-impaired neuronal respiratory capacity by exogenous alternative biofuels.

    Science.gov (United States)

    Laird, Melissa D; Clerc, Pascaline; Polster, Brian M; Fiskum, Gary

    2013-12-01

    Mitochondrial respiratory capacity is critical for responding to changes in neuronal energy demand. One approach toward neuroprotection is the administration of alternative energy substrates ("biofuels") to overcome brain injury-induced inhibition of glucose-based aerobic energy metabolism. This study tested the hypothesis that exogenous pyruvate, lactate, β-hydroxybutyrate, and acetyl-L-carnitine each increase neuronal respiratory capacity in vitro either in the absence of or following transient excitotoxic glutamate receptor stimulation. Compared to the presence of 5 mM glucose alone, the addition of pyruvate, lactate, or β-hydroxybutyrate (1.0-10.0 mM) to either day in vitro (DIV) 14 or 7 rat cortical neurons resulted in significant, dose-dependent stimulation of respiratory capacity, measured by cell respirometry as the maximal O2 consumption rate in the presence of the respiratory uncoupler carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. A 30-min exposure to 100 μM glutamate impaired respiratory capacity for DIV 14, but not DIV 7, neurons. Glutamate reduced the respiratory capacity for DIV 14 neurons with glucose alone by 25 % and also reduced respiratory capacity with glucose plus pyruvate, lactate, or β-hydroxybutyrate. However, respiratory capacity in glutamate-exposed neurons following pyruvate or β-hydroxybutyrate addition was still, at least, as high as that obtained with glucose alone in the absence of glutamate exposure. These results support the interpretation that previously observed neuroprotection by exogenous pyruvate, lactate, or β-hydroxybutyrate is at least partially mediated by their preservation of neuronal respiratory capacity. PMID:24323418

  11. Neuroprotective activity of pongamia pinnata in monosodium glutamate-induced neurotoxicity in rats

    Directory of Open Access Journals (Sweden)

    A. H. M. Viswanatha Swamy

    2013-01-01

    Full Text Available This study was designed to evaluate the neuroprotective activity of ethanol extract of Pongamia pinnata stem bark in monosodium glutamate-induced neurotoxicity in rats. Neurotoxicity was induced by intraperitoneal injection of monosodium glutamate 2 g per kg body weight daily for 7 days. Ethanol extract of Pongamia pinnata stem bark (200 and 400 mg/kg was administered orally after 1 h of monosodium glutamate treatment. Dextromethorphan (30 mg/kg, p.o. was used as standard drug for the comparison. The degree of protection was determined by various behavioural, locomotor, muscle grip activity, lipid peroxidation and measurement of antioxidant status of glutathione, catalase and superoxide dismutase. Estimation of calcium, sodium and potassium ions in brain tissue and gamma aminobutyric acid level in serum was carried out. The histopathological study of brain tissue was also carried out. Treatment with Pongamia pinnata significantly improved monosodium glutamate-induced alteration in behavioural and locomotor activity and muscle strength. Significant decrease in lipid peroxidation and increase in glutathione, superoxide dismutase and catalase was observed in Pongamia pinnata treated group. Further, Pongamia pinnata also significantly reduced the monosodium glutamate-induced excitotoxicity by decreasing the level of Ca +2 and Na + with concomitant increase in the level of K + . Serum gamma aminobutyric acid level was also increased in Pongamia pinnata treated animals. Further, the histopathological evidence supports the neuroprotective activity of Pongamia pinnata. In conclusion, the present study suggests that the ethanol extract of stem bark of Pongamia pinnata possesses significant neuroprotective activity in albino rats.

  12. Augmentation of Normal and Glutamate-Impaired Neuronal Respiratory Capacity by Exogenous Alternative Biofuels

    Science.gov (United States)

    Laird, Melissa D.; Clerc, Pascaline; Polster, Brian M.; Fiskum, Gary

    2013-01-01

    Mitochondrial respiratory capacity is critical for responding to changes in neuronal energy demand. One approach toward neuroprotection is administration of alternative energy substrates (“biofuels”) to overcome brain injury-induced inhibition of glucose-based aerobic energy metabolism. This study tested the hypothesis that exogenous pyruvate, lactate, β-hydroxybutyrate, and acetyl-L-carnitine each increase neuronal respiratory capacity in vitro either in the absence of, or following transient excitotoxic glutamate receptor stimulation. Compared to the presence of 5 mM glucose alone, the addition of pyruvate, lactate, or β-hydroxybutyrate (1.0 – 10.0 mM) to either day in vitro (DIV) 14 or 7 rat cortical neurons resulted in significant, dose-dependent stimulation of respiratory capacity, measured by cell respirometry as the maximal O2 consumption rate in the presence of the respiratory uncoupler FCCP. A thirty minute exposure to 100 μM glutamate impaired respiratory capacity for DIV 14 but not DIV 7 neurons. Glutamate reduced the respiratory capacity for DIV 14 neurons with glucose alone by 25% and also reduced respiratory capacity with glucose plus pyruvate, lactate or β-hydroxybutyrate. However, respiratory capacity in glutamate-exposed neurons following pyruvate or β-hydroxybutyrate addition was still at least as high as that obtained with glucose alone in the absence of glutamate exposure. These results support the interpretation that previously observed neuroprotection by exogenous pyruvate, lactate, or β-hydroxybutyrate is at least partially mediated by their preservation of neuronal respiratory capacity. PMID:24323418

  13. 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.

  14. Neuropeptide Y expression in mouse hippocampus and its role in neuronal excitotoxicity

    Institute of Scientific and Technical Information of China (English)

    Yong-fei WU; Sheng-bin LI

    2005-01-01

    Aim: To investigate neuropeptide Y (NPY) expression in mouse hippocampus within early stages of kainic acid (KA) treatment and to understand its role in neuronal excitotoxicity. Methods: NPY expression in the hippocampus within early stages of KA intraperitoneal (ip) treatment was detected by immunohistochemistry (IHC) and in situ hybridization (ISH) methods. The role of NPY and Y5, Y2 receptors in excitotoxicity was analyzed by terminal deoxynucleotidyl transferase-mediated UTP nick end-labeling (TUNEL) assay. Results: Using IHC assay, in granule cell layer of the dentate gyrus (DG), NPY positive signals appeared 4 h after KA injection, reached the peak at 8 h and leveled off at 16 and 24 h. In CA3, no positive signal was found within the first 4 h after KA injection,but strong signal appeared at 16 and 24 h. No noticeable signal was detected in CA1 at all time points after KA injection. Using the ISH method, positive signals were detected at 4, 8, and 16 h in CA3, CA1, and hilus. In DG, much stronger ISH signals were detected at 4 h, but leveled off at 8 and 16 h. TUNEL analysis showed that intracerebroventricularly (icv) infusion of NPY and Y5, Y2 receptor agonists within 8 h after KA insult with proper dose could remarkably rescue pyramidal neurons in CA3 and CA1 from apoptosis. Conclusion: NPY is an important anti-epileptic agent. The preceding elevated expression of NPY in granule cell layer of DG after KA injection might partially explain its different excitotoxicity-induced apoptotic responses in comparison with the pyramidal neurons from CA3 and CA1 regions. NPY can not only reduce neuronal excitability but also prevent excitotoxicity-induced neuronal apoptosis in a time- and doserelated way by activation of Y5 and Y2 receptors.

  15. 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.

  16. Reduced calcium-dependent mitochondrial damage underlies the reduced vulnerability of excitotoxicity-tolerant hippocampal neurons.

    Science.gov (United States)

    Pivovarova, Natalia B; Stanika, Ruslan I; Watts, Charlotte A; Brantner, Christine A; Smith, Carolyn L; Andrews, S Brian

    2008-03-01

    In central neurons, over-stimulation of NMDA receptors leads to excessive mitochondrial calcium accumulation and damage, which is a critical step in excitotoxic death. This raises the possibility that low susceptibility to calcium overload-induced mitochondrial damage might characterize excitotoxicity-resistant neurons. In this study, we have exploited two complementary models of preconditioning-induced excitotoxicity resistance to demonstrate reduced calcium-dependent mitochondrial damage in NMDA-tolerant hippocampal neurons. We have further identified adaptations in mitochondrial calcium handling that account for enhanced mitochondrial integrity. In both models, enhanced tolerance was associated with improved preservation of mitochondrial membrane potential and structure. In the first model, which exhibited modest neuroprotection, mitochondria-dependent calcium deregulation was delayed, even though cytosolic and mitochondrial calcium loads were quantitatively unchanged, indicating that enhanced mitochondrial calcium capacity accounts for reduced injury. In contrast, the second model, which exhibited strong neuroprotection, displayed further delayed calcium deregulation and reduced mitochondrial damage because downregulation of NMDA receptor surface expression depressed calcium loading. Reducing calcium entry also modified the chemical composition of the calcium-buffering precipitates that form in calcium-loaded mitochondria. It thus appears that reduced mitochondrial calcium loading is a major factor underlying the robust neuroprotection seen in highly tolerant cells. PMID:18036152

  17. Glutamate Pays Its Own Way in Astrocytes

    OpenAIRE

    MaryC.McKenna

    2013-01-01

    In vitro and in vivo studies have shown that glutamate can be oxidized for energy by brain astrocytes. The ability to harvest the energy from glutamate provides astrocytes with a mechanism to offset the high ATP cost of the uptake of glutamate from the synaptic cleft. This brief review focuses on oxidative metabolism of glutamate by astrocytes, the specific pathways involved in the complete oxidation of glutamate and the energy provided by each reaction.

  18. Ethanol tachyphylaxis in spinal cord motorneurons: role of metabotropic glutamate receptors

    OpenAIRE

    Li, Hui-Fang; Wang, Meng-Ya; Knape, Jessica; Kendig, Joan J

    2003-01-01

    Ethanol (EtOH) tachyphylaxis (acute tolerance), a time-dependent decrease in apparent potency, is known in vivo and in some neuronal preparations. The present studies characterize EtOH tachyphylaxis in spinal motorneurons and test the hypothesis that metabotropic glutamate receptors (mGluRs) play a role.Patch clamp studies were carried out in motorneurons in rat spinal cord slices. Currents were evoked by pulses of glutamate, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) or ...

  19. Phenolic antioxidants attenuate hippocampal neuronal cell damage against kainic acid induced excitotoxicity

    Indian Academy of Sciences (India)

    M S Parihar; Taruna Hemnani

    2003-02-01

    Increasing evidence supports the role of excitotoxicity in neuronal cell injury. Thus, it is extremely important to explore methods to retard or reverse excitotoxic neuronal injury. In this regard, certain dietary compounds are begining to receive increased attention, in particular those involving phytochemicals found in medicinal plants in alleviating neuronal injury. In the present study, we examined whether medicinal plant extracts protect neurons against excitotoxic lesions induced by kainic acid (KA) in female Swiss albino mice. Mice were anesthetized with ketamine and xylazine (200 mg and 2 mg/kg body wt. respectively) and KA (0.25 g in a volume of 0.5 l) was administered to mice by intra hippocampal injections. The results showed an impairment of the hippocampus region of brain after KA injection. The lipid peroxidation and protein carbonyl content were significantly ( < 0.05) increased in comparison to controls. Glutathione peroxidase (GPx) activity (EC 1.11.1.9) and reduced glutathione (GSH) content declined after appearance of excitotoxic lesions. As GPx and GSH represent a major pathway in the cell for metabolizing hydrogen peroxide (H2O2), their depletion would be expected to allow H2O2 to accumulate to toxic levels. Dried ethanolic plant extracts of Withania somnifera (WS), Convolvulus pleuricauas (CP) and Aloe vera (AV) dissolved in distilled water were tested for their total antioxidant activity. The diet was prepared in terms of total antioxidant activity of plant extracts. The iron (Fe3+) reducing activity of plant extracts was also tested and it was found that WS and AV were potent reductants of Fe3+ at pH 5.5. CP had lower Fe3+ reducing activity in comparison to WS and AV. Plant extracts given singly and in combination 3 weeks prior to KA injections resulted in a decrease in neurotoxicity. Measures of lipid peroxidation and protein carbonyl declined. GPx activity and GSH content were elevated in hippocampus supplemented with WS and combination of

  20. Relationship between plasma glutamate levels and post-stroke depression in patients with acute ischemic stroke%缺血性卒中急性期血浆谷氨酸水平与卒中后抑郁相关性的初步研究

    Institute of Scientific and Technical Information of China (English)

    钱方媛; 张志珺; 钱俊枫

    2013-01-01

    Objective To test the association between the plasma glutamate levels during acute ischemic stroke and post-stroke depression (PSD) initially.Methods Seventy-four ischemic stroke patients admitted to the hospital within the first day of stroke onset were evaluated at a follow-up of 2 weeks.The Beck Depression Inventory (BDI,21-item) and DSM-Ⅳ criteria was used to diagnose post-stroke depression (PSD) at 2 weeks after stroke.The Hamilton Depression Rating Scale (HDRS,17-item) was used to assess the severity of major depressive symptoms.Plasma level of glutamate between PSD and non-PSD patients was measured by high performance liquid chromatography (HPLC) on day 2 and 2 weeks after stroke.Results (1) The glutamate levels on day 2 after stroke were significantly lower in PSD patients(Twenty-six patients) than non-PSD patients [(4.995 ±2.514) g/L vs.(6.558 ±2.835) g/L;t =2.140,P =0.036].(2) In post-stroke patients,a strong negative correlation was observed between glutamate levels on day 2 after stroke and severity of depression(r =-0.311,P =0.013).(3) In patients with PSD,the levels of glutamate at 2 weeks after stroke (6.312 ± 2.604) g/L significantly increased compared to the levels of glutamate on day 2 after stroke (t =-2.361,P =0.026).(4) Using a multivariate logistic regression,plasma glutamate on day 2 was associated with incident PSD at 2 weeks after stroke (OR =0.651,95% CI:0.459-0.922,P =0.016).Conclusion Plasma glutamate during the acute phase of stroke may be associated with PSD.%目的 初步探讨急性缺血性卒中患者血浆谷氨酸水平与卒中后抑郁(post-strokedepression,PSD)的关系.方法 于卒中后2周,采用Beck抑郁问卷(21项)及《美国精神障碍诊断与统计手册(第4版)》躯体疾病所致心境障碍诊断标准,对连续入组的74例急性缺血性卒中患者进行PSD诊断,以17项汉密尔顿抑郁量表(the 17-item Hamilton Depression Rating Scale,HDRS)评估抑郁症状严重程度,并采用高效液相

  1. Generation and characterization of transgenic mice expressing mitochondrial targeted red fluorescent protein selectively in neurons: modeling mitochondriopathy in excitotoxicity and amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Wang Yi

    2011-11-01

    Full Text Available Abstract Background Mitochondria have roles or appear to have roles in the pathogenesis of several chronic age-related and acute neurological disorders, including Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Parkinson's disease, and cerebral ischemia, and could be critical targets for development of rational mechanism-based, disease-modifying therapeutics for treating these disorders effectively. A deeper understanding of neural tissue mitochondria pathobiologies as definitive mediators of neural injury, disease, and cell death merits further study, and the development of additional tools to study neural mitochondria will help achieve this unmet need. Results We created transgenic mice that express the coral (Discosoma sp. red fluorescent protein DsRed2 specifically in mitochondria of neurons using a construct engineered with a Thy1 promoter, specific for neuron expression, to drive expression of a fusion protein of DsRed2 with a mitochondrial targeting sequence. The biochemical and histological characterization of these mice shows the expression of mitochondrial-targeted DsRed2 to be specific for mitochondria and concentrated in distinct CNS regions, including cerebral cortex, hippocampus, thalamus, brainstem, and spinal cord. Red fluorescent mitochondria were visualized in cerebral cortical and hippocampal pyramidal neurons, ventrobasal thalamic neurons, subthalamic neurons, and spinal motor neurons. For the purpose of proof of principle application, these mice were used in excitotoxicity paradigms and double transgenic mice were generated by crossing Thy1-mitoDsRed2 mice with transgenic mice expressing enhanced-GFP (eGFP under the control of the Hlxb9 promoter that drives eGFP expression specifically in motor neurons and by crossing Thy1-mitoDsRed2 mice to amyotrophic lateral sclerosis (ALS mice expressing human mutant superoxide dismutase-1. Conclusions These novel transgenic mice will be a useful tool for better understanding

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

    Directory of Open Access Journals (Sweden)

    Diana L Price

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

  3. Effects of recombinant human erythropoietin on glutamate expression in the retina with acute high intraocular pressure in a rabbit model%重组人促红细胞生成素对急性高眼压兔视网膜谷氨酸表达的影响

    Institute of Scientific and Technical Information of China (English)

    王建明; 熊蕾; 孙乃学; 赵世平

    2009-01-01

    Objective The neuroprotection provided by recombinant human erythropoietin(rhEPO)on the retina from ischemia-reperfusion injury has been confirmed but its mechanism is not fully understood.The present study aimed to investigate the effect of systemic administration of recombinant human erythropoietin(rhEPO)on the expression of glutamate in the retina after acute high intraocular pressure in vitro.MethodsThe acute high intraocular pressure models were established by the perfusion of physiological saline into anterior chamber of the lateral eye in forty-eight Japanese white rabbits.Other 6 Japanese white rabbits were as normal control group.The experimental rabbits were then equally divided into the model group and EPO group,and hypodermic injection of rhEPO was only performed in the EPO group.Glutamate expression in the retina in both groups was observed by immunohistochemistry on days 1,3,7,and 14 after retinal ischemia-reperfusion.Glutamate expression in another 6 rabbit retina without any treatment was determined as normal by the same method.The use of animal followed the Standard of Association for Research in Vision and Ophthalmology.ResultsNo positive expression of glutamate was observed in normal rabbit retina,but positive expression response of glutamate occurred in the rabbit retina of the model group.The number of positive expression cells in the EPO group was more than that in the model group at each time point(P<0.01).On day 14 after ischemia-reperfusion,the number of positive expression cells was 3.3±1.1 per high visual field in the retina of the model group but 0.3±0.2 in the retina of the EPO group,showing a significant decrease of positive expression cells in EPO group(P<0.01).ConclusionSystemic administration of rhEPO can down-regulate the expression of glutamate in the retina with acute high intraocular pressure.This process may be one of the mechanisms that rhEPO protects the retina from ischemia reperfusion injury.%目的 探讨全身应

  4. Effects of Zibu Piyin Recipe(滋补脾阴方药)on SNK-SPAR Pathway in Neuron Injury Induced by Glutamate

    Institute of Scientific and Technical Information of China (English)

    ZHAN Li-bin; SUI Hua; LU Xiao-guang; SUN Chang-kai; ZHANG Jian; MA Hui

    2008-01-01

    Objective:To investigate the relationship between the excitotoxicity and seruminducible kinase(SNK)and spine-associated Rap GTPase-activating protein(SPAR)pathway in primary hippocampal neuron injury induced by glutamate and furthermore,to explore the molecular between ZBPYR and the morphological regulation of dendritic spines.Methods:The serum containing ZBPYR was prepared by seropharmacology.Reverse transcription and polymerase chain reaction(RT-PCR)was used to detect the expression of mRNA for SNK,SPAR,postsynaptic density protein 95(PSD-95)and N-methyl-D-aspartate(NMDA)receptor subunits(NR1,NR2A and NR2B)in primary rat hippocampal neuron cultures after pretreatment with 10 μ mol/L glutamate and ZBPYR serum.Results:ZBPYR serum pretreatment resulted in a significant down-regulation of glutamate-induced SNK mRNA expression(P<0.05).Significant up-regulation was seen on the mRNA expression of SPAR and PSD-95 (P<0.05).All these changes were dose-dependent.The mRNA expression of NR1,NR2A and NR2B was down-regulated to different degrees(P<0.05).Conclusion:The mechanism of effect of ZBPYR on glutamate-induced excitotoxicity may be related to the regulation of SNK-SPAR signal pathway.ZBPYR may play a role in protecting and maintaining the normal morphology and structure of dendritic spines,which may be achieved by inhibiting the excessive activation of NMDA receptors.

  5. GDNF and neublastin protect against NMDA-induced excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Bonde, C; Kristensen, B W; Blaabjerg, M;

    2000-01-01

    The potential neuroprotective effects of glial cell line-derived neurotrophic factor (GDNF) and neublastin (NBN) against NMDA-induced excitotoxicity were examined in hippocampal brain slice cultures. Recombinant human GDNF (25-100 ng/ ml) or NBN, in medium conditioned by growth of transfected, NBN......-producing HiB5 cells, were added to slice cultures I h before exposure to 10 microM NMDA for 48h. Neuronal cell death was monitored, before and during the NMDA exposure, by densitometric measurements of propidium iodide (PI) uptake and loss of Nissl staining. Both the addition of rhGDNF and NBN...

  6. Excitatory and inhibitory pathways modulate kainate excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Rai, R;

    1993-01-01

    In organotypic hippocampal slice cultures, kainate (KA) specifically induces cell loss in the CA3 region while N-methyl-D-aspartate induces cell loss in the CA1 region. The sensitivity of slice cultures to KA toxicity appears only after 2 weeks in vitro which parallels the appearance of mossy fib...... fibers. KA toxicity is potentiated by co-application with the GABA-A antagonist, picrotoxin. These data suggest that the excitotoxicity of KA in slice cultures is modulated by both excitatory and inhibitory synapses....

  7. Maternal inflammation leads to impaired glutamate homeostasis and up-regulation of glutamate carboxypeptidase II in activated microglia in the fetal/newborn rabbit brain.

    Science.gov (United States)

    Zhang, Zhi; Bassam, Bassam; Thomas, Ajit G; Williams, Monica; Liu, Jinhuan; Nance, Elizabeth; Rojas, Camilo; Slusher, Barbara S; Kannan, Sujatha

    2016-10-01

    Astrocyte dysfunction and excessive activation of glutamatergic systems have been implicated in a number of neurologic disorders, including periventricular leukomalacia (PVL) and cerebral palsy (CP). However, the role of chorioamnionitis on glutamate homeostasis in the fetal and neonatal brains is not clearly understood. We have previously shown that intrauterine endotoxin administration results in intense microglial 'activation' and increased pro-inflammatory cytokines in the periventricular region (PVR) of the neonatal rabbit brain. In this study, we assessed the effect of maternal inflammation on key components of the glutamate pathway and its relationship to astrocyte and microglial activation in the fetal and neonatal New Zealand white rabbit brain. We found that intrauterine endotoxin exposure at gestational day 28 (G28) induced acute and prolonged glutamate elevation in the PVR of fetal (G29, 1day post-injury) and postnatal day 1 (PND1, 3days post-injury) brains along with prominent morphological changes in the astrocytes (soma hypertrophy and retracted processes) in the white matter tracts. There was a significant increase in glutaminase and N-Methyl-d-Aspartate receptor (NMDAR) NR2 subunit expression along with decreased glial L-glutamate transporter 1 (GLT-1) in the PVR at G29, that would promote acute dysregulation of glutamate homeostasis. This was accompanied with significantly decreased TGF-β1 at PND1 in CP kits indicating ongoing neuroinflammation. We also show for the first time that glutamate carboxypeptidase II (GCPII) was significantly increased in the activated microglia at the periventricular white matter area in both G29 and PND1 CP kits. This was confirmed by in vitro studies demonstrating that LPS activated primary microglia markedly upregulate GCPII enzymatic activity. These results suggest that maternal intrauterine endotoxin exposure results in early onset and long-lasting dysregulation of glutamate homeostasis, which may be mediated by

  8. Delayed translocation of NGFI-B/RXR in glutamate stimulated neurons allows late protection by 9-cis retinoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Mathisen, Gro H.; Fallgren, Asa B.; Strom, Bjorn O.; Boldingh Debernard, Karen A.; Mohebi, Beata U. [Department of Pharmaceutical Biosciences, University of Oslo, P.O. Box 1068, Blindern, N-0316 Oslo (Norway); Paulsen, Ragnhild E., E-mail: r.e.paulsen@farmasi.uio.no [Department of Pharmaceutical Biosciences, University of Oslo, P.O. Box 1068, Blindern, N-0316 Oslo (Norway)

    2011-10-14

    Highlights: {yields} NGFI-B and RXR translocate out of the nucleus after glutamate treatment. {yields} Arresting NGFI-B/RXR in the nucleus protects neurons from excitotoxicity. {yields} Late protection by 9-cis RA is possible due to a delayed translocation of NGFI-B/RXR. -- Abstract: Nuclear receptor and apoptosis inducer NGFI-B translocates out of the nucleus as a heterodimer with RXR in response to different apoptosis stimuli, and therefore represents a potential pharmacological target. We found that the cytosolic levels of NGFI-B and RXR{alpha} were increased in cultures of cerebellar granule neurons 2 h after treatment with glutamate (excitatory neurotransmitter in the brain, involved in stroke). To find a time-window for potential intervention the neurons were transfected with gfp-tagged expressor plasmids for NGFI-B and RXR. The default localization of NGFI-Bgfp and RXRgfp was nuclear, however, translocation out of the nucleus was observed 2-3 h after glutamate treatment. We therefore hypothesized that the time-window between treatment and translocation would allow late protection against neuronal death. The RXR ligand 9-cis retinoic acid was used to arrest NGFI-B and RXR in the nucleus. Addition of 9-cis retinoic acid 1 h after treatment with glutamate reduced the cytosolic translocation of NGFI-B and RXR{alpha}, the cytosolic translocation of NGFI-Bgfp observed in live neurons, as well as the neuronal death. However, the reduced translocation and the reduced cell death were not observed when 9-cis retinoic acid was added after 3 h. Thus, late protection from glutamate induced death by addition of 9-cis retinoic acid is possible in a time-window after apoptosis induction.

  9. Conditioned Medium Reconditions Hippocampal Neurons against Kainic Acid Induced Excitotoxicity: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar K. Bevinahal

    2014-01-01

    Full Text Available Stem cell therapy is gaining attention as a promising treatment option for neurodegenerative diseases. The functional efficacy of grafted cells is a matter of debate and the recent consensus is that the cellular and functional recoveries might be due to “by-stander” effects of grafted cells. In the present study, we investigated the neuroprotective effect of conditioned medium (CM derived from human embryonic kidney (HEK cells in a kainic acid (KA induced hippocampal degeneration model system in in vitro condition. Hippocampal cell line was exposed to KA (200 µM for 24 hrs (lesion group whereas, in the treatment group, hippocampal cell line was exposed to KA in combination with HEK-CM (KA + HEK-CM. We observed that KA exposure to cells resulted in significant neuronal loss. Interestingly, HEK-CM cotreatment completely attenuated the excitotoxic effects of KA. In HEK-CM cotreatment group, the cell viability was ~85–95% as opposed to 47% in KA alone group. Further investigation demonstrated that treatment with HEK-CM stimulated the endogenous cell survival factors like brain derived neurotrophic factors (BDNF and antiapoptotic factor Bcl-2, revealing the possible mechanism of neuroprotection. Our results suggest that HEK-CM protects hippocampal neurons against excitotoxicity by stimulating the host’s endogenous cell survival mechanisms.

  10. Glial response to 17β-estradiol in neonatal rats with excitotoxic brain injury.

    Science.gov (United States)

    Pansiot, Julien; Pham, Hoa; Dalous, Jeremie; Chevenne, Didier; Colella, Marina; Schwendimann, Leslie; Fafouri, Assia; Mairesse, Jérôme; Moretti, Raffaella; Schang, Anne-Laure; Charriaut-Marlangue, Christiane; Gressens, Pierre; Baud, Olivier

    2016-08-01

    White-matter injury is the most common cause of the adverse neurodevelopmental outcomes observed in preterm infants. Only few options exist to prevent perinatal brain injury associated to preterm delivery. 17β-estradiol (E2) is the predominant estrogen in circulation and has been shown to be neuroprotective in vitro and in vivo. However, while E2 has been found to modulate inflammation in adult models of brain damage, how estrogens influence glial cells response in the developing brain needs further investigations. Using a model of ibotenate-induced brain injury, we have refined the effects of E2 in the developing brain. E2 provides significant neuroprotection both in the cortical plate and the white matter in neonatal rats subjected to excitotoxic insult mimicking white matter and cortical damages frequently observed in very preterm infants. E2 promotes significant changes in microglial phenotypes balance in response to brain injury and the acceleration of oligodendrocyte maturation. Maturational effects of E2 on myelination process were observed both in vivo and in vitro. Altogether, these data demonstrate that response of glial cells to E2 could be responsible for its neuroprotective properties in neonatal excitotoxic brain injury. PMID:27222132

  11. Conditioned Medium Reconditions Hippocampal Neurons against Kainic Acid Induced Excitotoxicity: An In Vitro Study

    Science.gov (United States)

    Bevinahal, Pradeep Kumar K.; Venugopal, Chaitra; Yencharla, Harish Chandra Prasad S.; Chandanala, Shashank; Trichur, Raju R.; Talakad, Sathyaprabha N.; Bhonde, Ramesh R.; Dhanushkodi, Anandh

    2014-01-01

    Stem cell therapy is gaining attention as a promising treatment option for neurodegenerative diseases. The functional efficacy of grafted cells is a matter of debate and the recent consensus is that the cellular and functional recoveries might be due to “by-stander” effects of grafted cells. In the present study, we investigated the neuroprotective effect of conditioned medium (CM) derived from human embryonic kidney (HEK) cells in a kainic acid (KA) induced hippocampal degeneration model system in in vitro condition. Hippocampal cell line was exposed to KA (200 µM) for 24 hrs (lesion group) whereas, in the treatment group, hippocampal cell line was exposed to KA in combination with HEK-CM (KA + HEK-CM). We observed that KA exposure to cells resulted in significant neuronal loss. Interestingly, HEK-CM cotreatment completely attenuated the excitotoxic effects of KA. In HEK-CM cotreatment group, the cell viability was ~85–95% as opposed to 47% in KA alone group. Further investigation demonstrated that treatment with HEK-CM stimulated the endogenous cell survival factors like brain derived neurotrophic factors (BDNF) and antiapoptotic factor Bcl-2, revealing the possible mechanism of neuroprotection. Our results suggest that HEK-CM protects hippocampal neurons against excitotoxicity by stimulating the host's endogenous cell survival mechanisms. PMID:25505907

  12. The GluK4 kainate receptor subunit regulates memory, mood, and excitotoxic neurodegeneration.

    Science.gov (United States)

    Lowry, E R; Kruyer, A; Norris, E H; Cederroth, C R; Strickland, S

    2013-04-01

    Though the GluK4 kainate receptor subunit shows limited homology and a restricted expression pattern relative to other kainate receptor subunits, its ablation results in distinct behavioral and molecular phenotypes. GluK4 knockout mice demonstrated impairments in memory acquisition and recall in a Morris water maze test, suggesting a previously unreported role for kainate receptors in spatial memory. GluK4 knockout mice also showed marked hyperactivity and impaired pre-pulse inhibition, thereby mirroring two of the hallmark endophenotypes of patients with schizophrenia and bipolar disorder. Furthermore, we found that GluK4 is a key mediator of excitotoxic neurodegeneration: GluK4 knockout mice showed robust neuroprotection in the CA3 region of the hippocampus following intrahippocampal injection of kainate and widespread neuroprotection throughout the hippocampus following hypoxia-ischemia. Biochemical analysis of kainate- or sham-treated wild-type and GluK4 knockout hippocampal tissue suggests that GluK4 may act through the JNK pathway to regulate the molecular cascades that lead to excitotoxicity. Together, our findings suggest that GluK4 may be relevant to the understanding and treatment of human neuropsychiatric and neurodegenerative disorders.

  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....... Discussions of stoichiometry, the relative role of glutamate vs. GABA and pathological conditions affecting the glutamate/GABA-glutamine cycling are presented. Furthermore, a section is devoted to the accompanying ammonia homeostasis of the glutamate/GABA-glutamine cycle, examining the possible means...

  14. 3-Nitropropionic acid neurotoxicity in organotypic striatal and corticostriatal slice cultures is dependent on glucose and glutamate

    DEFF Research Database (Denmark)

    Storgaard, J; Kornblit, B T; Zimmer, J;

    2000-01-01

    Mitochondrial inhibition by 3-nitropropionic acid (3-NPA) causes striatal degeneration reminiscent of Huntington's disease. We studied 3-NPA neurotoxicity and possible indirect excitotoxicity in organotypic striatal and corticostriatal slice cultures. Neurotoxicity was quantified by assay...... of lactate dehydrogenase in the medium and glutamic acid decarboxylase in tissue homogenates. 3-NPA toxicity (25-100 microM in 5 mM glucose, 24-48 h) appeared to be highly dependent on culture medium glucose levels. 3-NPA treatment caused also a dose-dependent lactate increase, reaching a maximum...... striatum without cortex and tetrodotoxin, MK-801, and d-2-amino-5-phosphonopentanoic acid prevented or attenuated 3-NPA neurotoxicity, suggesting that membrane depolarization and/or neuronal activity of the glutamatergic corticostriatal pathway contributes to striatal pathology. The results indicate...

  15. System xc⁻ cystine/glutamate antiporter: an update on molecular pharmacology and roles within the CNS.

    Science.gov (United States)

    Bridges, Richard J; Natale, Nicholas R; Patel, Sarjubhai A

    2012-01-01

    System x(c)(-) is an amino acid antiporter that typically mediates the exchange of extracellular l-cystine and intracellular L-glutamate across the cellular plasma membrane. Studied in a variety of cell types, the import of L-cystine through this transporter is critical to glutathione production and oxidative protection. The exchange-mediated export of L-glutamate takes on added significance within the CNS, as it represents a non-vesicular route of release through which this excitatory neurotransmitter can participate in either neuronal signalling or excitotoxic pathology. When both the import of L-cystine and the export of L-glutamate are taken into consideration, system x(c)(-) has now been linked to a wide range of CNS functions, including oxidative protection, the operation of the blood-brain barrier, neurotransmitter release, synaptic organization, viral pathology, drug addiction, chemosensitivity and chemoresistance, and brain tumour growth. The ability to selectively manipulate system x(c)(-), delineate its function, probe its structure and evaluate it as a therapeutic target is closely linked to understanding its pharmacology and the subsequent development of selective inhibitors and substrates. Towards that goal, this review will examine the current status of our understanding of system x(c)(-) pharmacology and the structure-activity relationships that have guided the development of an initial pharmacophore model, including the presence of lipophilic domains adjacent to the substrate binding site. A special emphasis is placed on the roles of system x(c)(-) within the CNS, as it is these actions that are among the most exciting as potential long-range therapeutic targets.

  16. Exposure to enriched environment decreases neurobehavioral deficits induced by neonatal glutamate toxicity.

    Science.gov (United States)

    Horvath, Gabor; Reglodi, Dora; Vadasz, Gyongyver; Farkas, Jozsef; Kiss, Peter

    2013-01-01

    Environmental enrichment is a popular strategy to enhance motor and cognitive performance and to counteract the effects of various harmful stimuli. The protective effects of enriched environment have been shown in traumatic, ischemic and toxic nervous system lesions. Monosodium glutamate (MSG) is a commonly used taste enhancer causing excitotoxic effects when given in newborn animals. We have previously demonstrated that MSG leads to a delay in neurobehavioral development, as shown by the delayed appearance of neurological reflexes and maturation of motor coordination. In the present study we aimed at investigating whether environmental enrichment is able to decrease the neurobehavioral delay caused by neonatal MSG treatment. Newborn pups were treated with MSG subcutaneously on postnatal days 1, 5 and 9. For environmental enrichment, we placed rats in larger cages, supplemented with different toys that were altered daily. Normal control and enriched control rats received saline treatment only. Physical parameters such as weight, day of eye opening, incisor eruption and ear unfolding were recorded. Animals were observed for appearance of reflexes such as negative geotaxis, righting reflexes, fore- and hindlimb grasp, fore- and hindlimb placing, sensory reflexes and gait. In cases of negative geotaxis, surface righting and gait, the time to perform the reflex was also recorded daily. For examining motor coordination, we performed grid walking, footfault, rope suspension, rota-rod, inclined board and walk initiation tests. We found that enriched environment alone did not lead to marked alterations in the course of development. On the other hand, MSG treatment caused a slight delay in reflex development and a pronounced delay in weight gain and motor coordination maturation. This delay in most signs and tests could be reversed by enriched environment: MSG-treated pups kept under enriched conditions showed no weight retardation, no reflex delay in some signs and

  17. Exposure to Enriched Environment Decreases Neurobehavioral Deficits Induced by Neonatal Glutamate Toxicity

    Directory of Open Access Journals (Sweden)

    Peter Kiss

    2013-09-01

    Full Text Available Environmental enrichment is a popular strategy to enhance motor and cognitive performance and to counteract the effects of various harmful stimuli. The protective effects of enriched environment have been shown in traumatic, ischemic and toxic nervous system lesions. Monosodium glutamate (MSG is a commonly used taste enhancer causing excitotoxic effects when given in newborn animals. We have previously demonstrated that MSG leads to a delay in neurobehavioral development, as shown by the delayed appearance of neurological reflexes and maturation of motor coordination. In the present study we aimed at investigating whether environmental enrichment is able to decrease the neurobehavioral delay caused by neonatal MSG treatment. Newborn pups were treated with MSG subcutaneously on postnatal days 1, 5 and 9. For environmental enrichment, we placed rats in larger cages, supplemented with different toys that were altered daily. Normal control and enriched control rats received saline treatment only. Physical parameters such as weight, day of eye opening, incisor eruption and ear unfolding were recorded. Animals were observed for appearance of reflexes such as negative geotaxis, righting reflexes, fore- and hindlimb grasp, fore- and hindlimb placing, sensory reflexes and gait. In cases of negative geotaxis, surface righting and gait, the time to perform the reflex was also recorded daily. For examining motor coordination, we performed grid walking, footfault, rope suspension, rota-rod, inclined board and walk initiation tests. We found that enriched environment alone did not lead to marked alterations in the course of development. On the other hand, MSG treatment caused a slight delay in reflex development and a pronounced delay in weight gain and motor coordination maturation. This delay in most signs and tests could be reversed by enriched environment: MSG-treated pups kept under enriched conditions showed no weight retardation, no reflex delay in

  18. Ligands for Ionotropic Glutamate Receptors

    Science.gov (United States)

    Swanson, Geoffrey T.; Sakai, Ryuichi

    Marine-derived small molecules and peptides have played a central role in elaborating pharmacological specificities and neuronal functions of mammalian ionotropic glutamate receptors (iGluRs), the primary mediators of excitatory syn-aptic transmission in the central nervous system (CNS). As well, the pathological sequelae elicited by one class of compounds (the kainoids) constitute a widely-used animal model for human mesial temporal lobe epilepsy (mTLE). New and existing molecules could prove useful as lead compounds for the development of therapeutics for neuropathologies that have aberrant glutamatergic signaling as a central component. In this chapter we discuss natural source origins and pharmacological activities of those marine compounds that target ionotropic glutamate receptors.

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

    OpenAIRE

    Santokh Gill; Tracey Goldstein; Donna Situ; Zabka, Tanja S.; Gulland, Frances M. D.; Mueller, Rudi W.

    2010-01-01

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

  20. Blockade of cannabinoid CB receptor function protects against in vivo disseminating brain damage following NMDA-induced excitotoxicity

    DEFF Research Database (Denmark)

    Hansen, H.H.; Ramos, J.A.; Fernández-Ruiz, J.;

    2002-01-01

    The ability of cannabinoid CB, receptors to influence glutamatergic excitatory neurotransmission has fueled interest in how these receptors and their endogenous ligands may interact in conditions of excitotoxic insults. The present study characterized the impact of stimulated and inhibited CB rec...

  1. Neuroprotection of Persea major extract against oxygen and glucose deprivation in hippocampal slices involves increased glutamate uptake and modulation of A1 and A2A adenosine receptors

    Directory of Open Access Journals (Sweden)

    Marielli Letícia Fedalto

    2013-10-01

    Full Text Available Ischemic stroke is characterised by a lack of oxygen and glucose in the brain, leading to excessive glutamate release and neuronal cell death. Adenosine is produced in response to ATP depletion and acts as an endogenous neuromodulator that reduces excitotoxicity. Persea major (Meins. L.E. Kopp (Lauraceae is a medical plant that is indigenous to South Brazil, and the rural population has used it medicinally due to its anti-inflammatory properties. The aim of this study was to evaluate the neuroprotective effect of Persea major methanolic extract against oxygen and glucose deprivation and re-oxygenation as well as to determine its underlying mechanism of action in hippocampal brain slices. Persea major methanolic extract (0.5 mg/ml has a neuroprotective effect on hippocampal slices when added before or during 15 min of oxygen and glucose deprivation or 2 h of re-oxygenation. Hippocampal slices subjected to oxygen and glucose deprivation and re-oxygenation showed significantly reduced glutamate uptake, and the addition of Persea major methanolic extract in the re-oxygenation period counteracted the reduction of glutamate uptake. The presence of A1 or A2A, but not A2B or A3 receptor antagonists, abolished the neuroprotective effect of Persea major methanolic extract. In conclusion, the neuroprotective effect of Persea majormethanolic extract involves augmentation of glutamate uptake and modulation of A1 and A2B adenosine receptors.

  2. Glutamate and GABA imbalance following traumatic brain injury.

    Science.gov (United States)

    Guerriero, Réjean M; Giza, Christopher C; Rotenberg, Alexander

    2015-05-01

    Traumatic brain injury (TBI) leads to multiple short- and long-term changes in neuronal circuits that ultimately conclude with an imbalance of cortical excitation and inhibition. Changes in neurotransmitter concentrations, receptor populations, and specific cell survival are important contributing factors. Many of these changes occur gradually, which may explain the vulnerability of the brain to multiple mild impacts, alterations in neuroplasticity, and delays in the presentation of posttraumatic epilepsy. In this review, we provide an overview of normal glutamate and GABA homeostasis and describe acute, subacute, and chronic changes that follow injury. We conclude by highlighting opportunities for therapeutic interventions in this paradigm. PMID:25796572

  3. Altered mRNA editing and expression of ionotropic glutamate receptors after kainic acid exposure in cyclooxygenase-2 deficient mice.

    Directory of Open Access Journals (Sweden)

    Luca Caracciolo

    Full Text Available Kainic acid (KA binds to the AMPA/KA receptors and induces seizures that result in inflammation, oxidative damage and neuronal death. We previously showed that cyclooxygenase-2 deficient (COX-2(-/- mice are more vulnerable to KA-induced excitotoxicity. Here, we investigated whether the increased susceptibility of COX-2(-/- mice to KA is associated with altered mRNA expression and editing of glutamate receptors. The expression of AMPA GluR2, GluR3 and KA GluR6 was increased in vehicle-injected COX-2(-/- mice compared to wild type (WT mice in hippocampus and cortex, whereas gene expression of NMDA receptors was decreased. KA treatment decreased the expression of AMPA, KA and NMDA receptors in the hippocampus, with a significant effect in COX-2(-/- mice. Furthermore, we analyzed RNA editing levels and found that the level of GluR3 R/G editing site was selectively increased in the hippocampus and decreased in the cortex in COX-2(-/- compared with WT mice. After KA, GluR4 R/G editing site, flip form, was increased in the hippocampus of COX-2(-/- mice. Treatment of WT mice with the COX-2 inhibitor celecoxib for two weeks decreased the expression of AMPA/KA and NMDAR subunits after KA, as observed in COX-2(-/- mice. After KA exposure, COX-2(-/- mice showed increased mRNA expression of markers of inflammation and oxidative stress, such as cytokines (TNF-α, IL-1β and IL-6, inducible nitric oxide synthase (iNOS, microglia (CD11b and astrocyte (GFAP. Thus, COX-2 gene deletion can exacerbate the inflammatory response to KA. We suggest that COX-2 plays a role in attenuating glutamate excitotoxicity by modulating RNA editing of AMPA/KA and mRNA expression of all ionotropic glutamate receptor subunits and, in turn, neuronal excitability. These changes may contribute to the increased vulnerability of COX-2(-/- mice to KA. The overstimulation of glutamate receptors as a consequence of COX-2 gene deletion suggests a functional coupling between COX-2 and the

  4. Neuroprotection from NMDA excitotoxic lesion by Cu/Zn superoxide dismutase gene delivery to the postnatal rat brain by a modular protein vector

    Directory of Open Access Journals (Sweden)

    Castellano Bernardo

    2006-04-01

    Full Text Available Abstract Background Superoxide mediated oxidative stress is a key neuropathologic mechanism in acute central nervous system injuries. We have analyzed the neuroprotective efficacy of the transient overexpression of antioxidant enzyme Cu/Zn Superoxide dismutase (SOD after excitotoxic injury to the immature rat brain by using a recently constructed modular protein vector for non-viral gene delivery termed NLSCt. For this purpose, animals were injected with the NLSCt vector carrying the Cu/Zn SOD or the control GFP transgenes 2 hours after intracortical N-methyl-D-aspartate (NMDA administration, and daily functional evaluation was performed. Moreover, 3 days after, lesion volume, neuronal degeneration and nitrotyrosine immunoreactivity were evaluated. Results Overexpression of Cu/Zn SOD transgene after NMDA administration showed improved functional outcome and a reduced lesion volume at 3 days post lesion. In secondary degenerative areas, increased neuronal survival as well as decreased numbers of degenerating neurons and nitrotyrosine immunoreactivity was seen. Interestingly, injection of the NLSCt vector carrying the control GFP transgene also displayed a significant neuroprotective effect but less pronounced. Conclusion When the appropriate levels of Cu/Zn SOD are expressed transiently after injury using the non-viral modular protein vector NLSCt a neuroprotective effect is seen. Thus recombinant modular protein vectors may be suitable for in vivo gene therapy, and Cu/Zn SOD should be considered as an interesting therapeutic transgene.

  5. The effect of striatal dopamine depletion on striatal and cortical glutamate: A mini-review.

    Science.gov (United States)

    Caravaggio, Fernando; Nakajima, Shinichiro; Plitman, Eric; Gerretsen, Philip; Chung, Jun Ku; Iwata, Yusuke; Graff-Guerrero, Ariel

    2016-02-01

    Understanding the interplay between the neurotransmitters dopamine and glutamate in the striatum has become the highlight of several theories of neuropsychiatric illnesses, such as schizophrenia. Using in vivo brain imaging in humans, alterations in dopamine and glutamate concentrations have been observed in several neuropsychiatric disorders. However, it is unclear a priori how alterations in striatal dopamine should modulate glutamate concentrations in the basal ganglia. In this selective mini-review, we examine the consequence of reducing striatal dopamine functioning on glutamate concentrations in the striatum and cortex; regions of interest heavily examined in the human brain imaging studies. We examine the predictions of the classical model of the basal ganglia, and contrast it with findings in humans and animals. The review concludes that chronic dopamine depletion (>4months) produces decreases in striatal glutamate levels which are consistent with the classical model of the basal ganglia. However, acute alterations in striatal dopamine functioning, specifically at the D2 receptors, may produce opposite affects. This has important implications for models of the basal ganglia and theorizing about neurochemical alterations in neuropsychiatric diseases. Moreover, these findings may help guide a priori hypotheses for (1)H-MRS studies measuring glutamate changes given alterations in dopaminergic functioning in humans. PMID:26334687

  6. Glutamate joins the ranks of immunomodulators

    OpenAIRE

    Hansen, Anna M; Caspi, Rachel R.

    2010-01-01

    Elevated amounts of glutamate, which acts as a neurotransmitter but is also a neurotoxin, are a hallmark of the autoimmune neurological disease multiple sclerosis and may contribute to its pathology. The discovery that a receptor for glutamate can inhibit the development of autoimmunity and protect from neuroinflammation in a mouse model of multiple sclerosis suggests that glutamate may also have a protective role and that its receptor may represent a therapeutic target (pages 897–902).

  7. Neuroprotection Promoted by Guanosine Depends on Glutamine Synthetase and Glutamate Transporters Activity in Hippocampal Slices Subjected to Oxygen/Glucose Deprivation.

    Science.gov (United States)

    Dal-Cim, Tharine; Martins, Wagner C; Thomaz, Daniel T; Coelho, Victor; Poluceno, Gabriela Godoy; Lanznaster, Débora; Vandresen-Filho, Samuel; Tasca, Carla I

    2016-05-01

    Guanosine (GUO) has been shown to act as a neuroprotective agent against glutamatergic excitotoxicity by increasing glutamate uptake and decreasing its release. In this study, a putative effect of GUO action on glutamate transporters activity modulation was assessed in hippocampal slices subjected to oxygen and glucose deprivation (OGD), an in vitro model of brain ischemia. Slices subjected to OGD showed increased excitatory amino acids release (measured by D-[(3)H]aspartate release) that was prevented in the presence of GUO (100 µM). The glutamate transporter blockers, DL-TBOA (10 µM), DHK (100 µM, selective inhibitor of GLT-1), and sulfasalazine (SAS, 250 µM, Xc(-) system inhibitor) decreased OGD-induced D-aspartate release. Interestingly, DHK or DL-TBOA blocked the decrease in glutamate release induced by GUO, whereas SAS did not modify the GUO effect. GUO protected hippocampal slices from cellular damage by modulation of glutamate transporters, however selective blockade of GLT-1 or Xc- system only did not affect this protective action of GUO. OGD decreased hippocampal glutamine synthetase (GS) activity and GUO recovered GS activity to control levels without altering the kinetic parameters of GS activity, thus suggesting GUO does not directly interact with GS. Additionally, the pharmacological inhibition of GS activity with methionine sulfoximine abolished the effect of GUO in reducing D-aspartate release and cellular damage evoked by OGD. Altogether, results in hippocampal slices subjected to OGD show that GUO counteracts the release of excitatory amino acids, stimulates the activity of GS, and decreases the cellular damage by modulation of glutamate transporters activity.

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

    NARCIS (Netherlands)

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

    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

  9. Enhanced glutamate, IP3 and cAMP activity in the cerebral cortex of Unilateral 6-hydroxydopamine induced Parkinson's rats: Effect of 5-HT, GABA and bone marrow cell supplementation

    Directory of Open Access Journals (Sweden)

    Romeo Chinthu

    2011-01-01

    Full Text Available Abstract Parkinson's disease is characterized by progressive cell death in the substantia nigra pars compacta, which leads to dopamine depletion in the striatum and indirectly to cortical dysfunction. Increased glutamatergic transmission in the basal ganglia is implicated in the pathophysiology of Parkinson's disease and glutamate receptor mediated excitotoxicity has been suggested to be one of the possible causes of the neuronal degeneration. In the present study, the effects of serotonin, gamma-aminobutyric acid and bone marrow cells infused intranigrally to substantia nigra individually and in combination on unilateral 6-hydroxydopamine induced Parkinson's rat model was analyzed. Scatchard analysis of total glutamate and NMDA receptor binding parameters showed a significant increase in Bmax (P

  10. Novel neuroprotective mechanisms of pramipexole, an anti-Parkinson drug, against endogenous dopamine-mediated excitotoxicity.

    Science.gov (United States)

    Izumi, Yasuhiko; Sawada, Hideyuki; Yamamoto, Noriyuki; Kume, Toshiaki; Katsuki, Hiroshi; Shimohama, Shun; Akaike, Akinori

    2007-02-28

    Parkinson disease is characterized by selective degeneration of mesencephalic dopaminergic neurons, and endogenous dopamine may play a pivotal role in the degenerative processes. Using primary cultured mesencephalic neurons, we found that glutamate, an excitotoxin, caused selective dopaminergic neuronal death depending on endogenous dopamine content. Pramipexole, a dopamine D2/D3 receptor agonist used clinically in the treatment of Parkinson disease, did not affect glutamate-induced calcium influx but blocked dopaminergic neuronal death induced by glutamate. Pramipexole reduced dopamine content but did not change the levels of total or phosphorylated tyrosine hydroxylase, a rate-limiting enzyme in dopamine synthesis. The neuroprotective effect of pramipexole was independent of dopamine receptor stimulation because it was not abrogated by domperidone, a dopamine D2-type receptor antagonist. Moreover, both active S(-)- and inactive R(+)-enantiomers of pramipexole as a dopamine D2-like receptor agonist equally suppressed dopaminergic neuronal death. These results suggest that pramipexole protects dopaminergic neurons from glutamate neurotoxicity by the reduction of intracellular dopamine content, independently of dopamine D2-like receptor activation. PMID:17161393

  11. Metabotropic glutamate receptor ligands as potential therapeutics for addiction

    OpenAIRE

    Olive, M.F.

    2009-01-01

    There is now compelling evidence that the excitatory amino acid neurotransmitter glutamate plays a pivotal role in drug addiction and alcoholism. As a result, there has been increasing interest in developing glutamate-based therapies for the treatment of addictive disorders. Receptors for glutamate are primarily divided into two classes: ionotropic glutamate receptors (iGluRs) that mediate fast excitatory glutamate transmission, and metabotropic glutamate receptors (mGluRs), which are G-prote...

  12. Cu/Zn superoxide dismutase expression in the postnatal rat brain following an excitotoxic injury

    Directory of Open Access Journals (Sweden)

    Faiz Maryam

    2005-06-01

    Full Text Available Abstract Background In the nervous system, as in other organs, Cu/Zn superoxide dismutase (Cu/Zn SOD is a key antioxidant enzyme involved in superoxide detoxification in normal cellular metabolism and after cell injury. Although it has been suggested that immature brain has a different susceptibility to oxidative damage than adult brain, the distribution and cell-specific expression of this enzyme in immature brain and after postnatal brain damage has not been documented. Methods In this study, we used immunohistochemistry and western blot to analyze the expression of Cu/Zn SOD in intact immature rat brain and in immature rat brain after an NMDA-induced excitotoxic cortical injury performed at postnatal day 9. Double immunofluorescence labelling was used to identify Cu/Zn SOD-expressing cell populations. Results In intact immature brain, Cu/Zn SOD enzyme was widely expressed at high levels in neurons mainly located in cortical layers II, III and V, in the sub-plate, in the pyriform cortex, in the hippocampus, and in the hypothalamus. Glial fibrillary acidic protein-positive cells only showed Cu/Zn SOD expression in the glia limitans and in scattered cells of the ventricle walls. No expression was detected in interfascicular oligodendroglia, microglia or endothelial cells. Following excitotoxic damage, neuronal Cu/Zn SOD was rapidly downregulated (over 2–4 hours at the injection site before neurodegeneration signals and TUNEL staining were observed. Later, from 1 day post-lesion onward, an upregulation of Cu/Zn SOD was found due to increased expression in astroglia. A further increase was observed at 3, 5 and 7 days that corresponded to extensive induction of Cu/Zn SOD in highly reactive astrocytes and in the astroglial scar. Conclusion We show here that, in the intact immature brain, the expression of Cu/Zn SOD was mainly found in neurons. When damage occurs, a strong and very rapid downregulation of this enzyme precedes neuronal degeneration

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

    Science.gov (United States)

    Borbély, Sándor; Jócsák, Gergely; Moldován, Kinga; Sedlák, Éva; Preininger, Éva; Boldizsár, Imre; Tóth, Attila; Atlason, Palmi T; Molnár, Elek; Világi, Ildikó

    2016-07-01

    Lignans are biologically active phenolic compounds related to lignin, produced in different plants. Arctigenin, a dibenzylbutyrolactone-type lignan, has been used as a neuroprotective agent for the treatment of encephalitis. Previous studies of cultured rat cerebral cortical neurones raised the possibility that arctigenin inhibits kainate-induced excitotoxicity. The aims of the present study were: 1) to analyse the effect of arctigenin on normal synaptic activity in ex vivo brain slices, 2) to determine its receptor binding properties and test the effect of arctigenin on AMPA/kainate receptor activation and 3) to establish its effects on neuronal activity in vivo. Arctigenin inhibited glutamatergic transmission and reduced the evoked field responses. The inhibitory effect of arctigenin on the evoked field responses proved to be substantially dose dependent. Our results indicate that arctigenin exerts its effects under physiological conditions and not only on hyper-excited neurons. Furthermore, arctigenin can cross the blood-brain barrier and in the brain it interacts with kainate sensitive ionotropic glutamate receptors. These results indicate that arctigenin is a potentially useful new pharmacological tool for the inhibition of glutamate-evoked responses in the central nervous system in vivo. PMID:26972612

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

    Science.gov (United States)

    Borbély, Sándor; Jócsák, Gergely; Moldován, Kinga; Sedlák, Éva; Preininger, Éva; Boldizsár, Imre; Tóth, Attila; Atlason, Palmi T; Molnár, Elek; Világi, Ildikó

    2016-07-01

    Lignans are biologically active phenolic compounds related to lignin, produced in different plants. Arctigenin, a dibenzylbutyrolactone-type lignan, has been used as a neuroprotective agent for the treatment of encephalitis. Previous studies of cultured rat cerebral cortical neurones raised the possibility that arctigenin inhibits kainate-induced excitotoxicity. The aims of the present study were: 1) to analyse the effect of arctigenin on normal synaptic activity in ex vivo brain slices, 2) to determine its receptor binding properties and test the effect of arctigenin on AMPA/kainate receptor activation and 3) to establish its effects on neuronal activity in vivo. Arctigenin inhibited glutamatergic transmission and reduced the evoked field responses. The inhibitory effect of arctigenin on the evoked field responses proved to be substantially dose dependent. Our results indicate that arctigenin exerts its effects under physiological conditions and not only on hyper-excited neurons. Furthermore, arctigenin can cross the blood-brain barrier and in the brain it interacts with kainate sensitive ionotropic glutamate receptors. These results indicate that arctigenin is a potentially useful new pharmacological tool for the inhibition of glutamate-evoked responses in the central nervous system in vivo.

  15. Pharmacological activation/inhibition of the cannabinoid system affects alcohol withdrawal-induced neuronal hypersensitivity to excitotoxic insults.

    Directory of Open Access Journals (Sweden)

    Marina Rubio

    Full Text Available Cessation of chronic ethanol consumption can increase the sensitivity of the brain to excitotoxic damages. Cannabinoids have been proposed as neuroprotectants in different models of neuronal injury, but their effect have never been investigated in a context of excitotoxicity after alcohol cessation. Here we examined the effects of the pharmacological activation/inhibition of the endocannabinoid system in an in vitro model of chronic ethanol exposure and withdrawal followed by an excitotoxic challenge. Ethanol withdrawal increased N-methyl-D-aspartate (NMDA-evoked neuronal death, probably by altering the ratio between GluN2A and GluN2B NMDA receptor subunits. The stimulation of the endocannabinoid system with the cannabinoid agonist HU-210 decreased NMDA-induced neuronal death exclusively in ethanol-withdrawn neurons. This neuroprotection could be explained by a decrease in NMDA-stimulated calcium influx after the administration of HU-210, found exclusively in ethanol-withdrawn neurons. By contrast, the inhibition of the cannabinoid system with the CB1 receptor antagonist rimonabant (SR141716 during ethanol withdrawal increased death of ethanol-withdrawn neurons without any modification of NMDA-stimulated calcium influx. Moreover, chronic administration of rimonabant increased NMDA-stimulated toxicity not only in withdrawn neurons, but also in control neurons. In summary, we show for the first time that the stimulation of the endocannabinoid system is protective against the hyperexcitability developed during alcohol withdrawal. By contrast, the blockade of the endocannabinoid system is highly counterproductive during alcohol withdrawal.

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

    International Nuclear Information System (INIS)

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

  17. Impact of fumonisin B1 on glutamate toxicity and low magnesium-induced seizure activity in neuronal primary culture.

    Science.gov (United States)

    Domijan, A-M; Kovac, S; Abramov, A Y

    2012-01-27

    Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium spp. mould that contaminates maize world-wide. Although its neurodegenerative potential is well established, mechanisms and acute effects of FB(1) on neurons are still not completely understood. Our previous study on astrocytes and neuroblastoma cells demonstrated that acute FB(1) exposure inhibits mitochondrial complex I and leads to mitochondrial membrane potential depolarization and calcium deregulation. To further explore the mechanisms of FB(1) neurotoxicity, we here investigated the effects of acute FB(1) co-exposure with glutamate and in the low magnesium model of epilepsy on neuronal calcium level, mitochondrial membrane potential, and cell death in glio-neuronal cultures. FB(1) increased the glutamate-induced calcium signal in neurons and changed neuronal calcium signals to more sustained intracellular calcium rises in the low magnesium model of epilepsy that coincided with mitochondrial membrane potential depolarization. FB(1) co-exposure increased the percentage of dead neurons in low magnesium conditions dose dependently when compared with low magnesium exposure only, whereas in FB(1) and glutamate co-exposure neuronal death remained unchanged when compared with glutamate treatment only. Our results show that FB(1) makes neurons more vulnerable to glutamate-induced toxicity and epileptiform conditions, indicating that FB(1) can enhance the detrimental effect of these conditions on neurons. PMID:22178271

  18. Role of glutamate receptors and glial cells in the pathophysiology of treatment-resistant depression.

    Science.gov (United States)

    Kim, Yong-Ku; Na, Kyoung-Sae

    2016-10-01

    Treatment-resistant depression (TRD) causes substantial socioeconomic burden. Although a consensus on the definition of TRD has not yet been reached, it is certain that classic monoaminergic antidepressants are ineffective for TRD. One decade ago, many researchers found ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, to be an alternative to classic monoaminergic antidepressants. The major mechanisms of action of ketamine rapidly induce synaptogenesis in the brain-derived neurotrophic factor (BDNF) pathway. Although excessive glutamatergic neurotransmission and consequent excitotoxicity were considered a major cause of TRD, recent evidence suggests that the extrasynaptic glutamatergic receptor signal pathway mainly contributes to the detrimental effects of TRD. Glial cells such as microglia and astrocytes, early life adversity, and glucocorticoid receptor dysfunction participate in complex cross-talk. An appropriate reuptake of glutamate at the astrocyte is crucial for preventing 'spill-over' of synaptic glutamate and binding to the extrasynaptic NMDA receptor. Excessive microglial activation and the inflammatory process cause astrocyte glutamatergic dysfunction, which in turn activates microglial function. Early life adversity and glucocorticoid receptor dysfunction result in vulnerability to stress in adulthood. A maladaptive response to stress leads to increased glutamatergic release and pro-inflammatory cytokines, which then activate microglia. However, since the role of inflammatory mediators such as pro-inflammatory cytokines is not specific for depression, more disease-specific mechanisms should be identified. Last, although much research has focused on ketamine as an alternative antidepressant for TRD, its long-lasting effectiveness and adverse events have not been rigorously demonstrated. Additionally, evidence suggests that substantial brain abnormalities develop in ketamine abusers. Thus, more investigations for ketamine and other novel

  19. Different pools of glutamate receptors mediate sensitivity to ambient glutamate in the cochlear nucleus.

    Science.gov (United States)

    Yang, Yang; Xu-Friedman, Matthew A

    2015-06-01

    Ambient glutamate plays an important role in pathological conditions, such as stroke, but its role during normal activity is not clear. In addition, it is not clear how ambient glutamate acts on glutamate receptors with varying affinities or subcellular localizations. To address this, we studied "endbulb of Held" synapses, which are formed by auditory nerve fibers onto bushy cells (BCs) in the anteroventral cochlear nucleus. When ambient glutamate was increased by applying the glutamate reuptake inhibitor TFB-TBOA, BCs depolarized as a result of activation of N-methyl-D-aspartate receptors (NMDARs) and group I metabotropic glutamate receptors (mGluRs). Application of antagonists against NMDARs (in 0 Mg(2+)) or mGluRs caused hyperpolarization, indicating that these receptors were bound by a tonic source of glutamate. AMPA receptors did not show these effects, consistent with their lower glutamate affinity. We also evaluated the subcellular localization of the receptors activated by ambient glutamate. The mGluRs were not activated by synaptic stimulation and thus appear to be exclusively extrasynaptic. By contrast, NMDARs in both synaptic and extrasynaptic compartments were activated by ambient glutamate, as shown using the use-dependent antagonist MK-801. Levels of ambient glutamate appeared to be regulated in a spike-independent manner, and glia likely play a major role. These low levels of ambient glutamate likely have functional consequences, as even low concentrations of TBOA caused significant increases in BC spiking following synaptic stimulation. These results indicate that normal resting potential appears to be poised in the region of maximal sensitivity to small changes in ambient glutamate. PMID:25855696

  20. 谷氨酸转运体 EAAT2在抑郁症发病及治疗中的作用%Roles of glutamate transporter EAAT2 in occurrence and treatment of depression

    Institute of Scientific and Technical Information of China (English)

    陈建新; 姚丽华; 王惠玲; 刘忠纯; 王晓萍; 肖玲; 舒畅; 王高华

    2016-01-01

    谷氨酸转运体EAAT2(啮齿类动物命名为GLT-1:谷氨酸转运体1)是海马和前额叶星形胶质细胞上一种非常重要的谷氨酸转运体,其承担了细胞外大部分谷氨酸的摄取和转运,由于谷氨酸转运体EAAT2的作用在于降低突触间隙过高的谷氨酸水平,避免过高浓度的谷氨酸对神经元和神经胶质细胞的兴奋毒性作用,使之逐渐成为近年来抑郁症研究的热点。该文主要就谷氨酸转运体EAAT2在抑郁症中可能的病理生理作用,以及其可能作为新一代抗抑郁药作用的靶点进行综述。%The glutamate transporter EAAT 2 ( rodent nomencla-ture GLT-1:glutamate transporter 1), which is a predominantly astroglial glutamate transporter in the hippocampus and the pre-frontal cortex , is responsible for the majority of extracellular glu-tamate uptake .The glutamate transporter EAAT 2 can decrease the high levels of glutamate in the synaptic cleft , avoiding gluta-matergic excitotoxicity to damage the glial cells and neurons . Currently, the transporter EAAT2 has become a research hotspot of depression .This article aims to summarize roles of glutamate transporter EAAT2 in the occurrence and treatment of depres-sion.

  1. An Overview of Brain-Derived Neurotrophic Factor and Implications for Excitotoxic Vulnerability in the Hippocampus

    Directory of Open Access Journals (Sweden)

    Patrick S. Murray

    2011-01-01

    Full Text Available The present paper examines the nature and function of brain-derived neurotrophic factor (BDNF in the hippocampal formation and the consequences of changes in its expression. The paper focuses on literature describing the role of BDNF in hippocampal development and neuroplasticity. BDNF expression is highly sensitive to developmental and environmental factors, and increased BDNF signaling enhances neurogenesis, neurite sprouting, electrophysiological activity, and other processes reflective of a general enhancement of hippocampal function. Such increases in activity may mediate beneficial effects such as enhanced learning and memory. However, the increased activity also comes at a cost: BDNF plasticity renders the hippocampus more vulnerable to hyperexcitability and/or excitotoxic damage. Exercise dramatically increases hippocampal BDNF levels and produces behavioral effects consistent with this phenomenon. In analyzing the literature regarding exercise-induced regulation of BDNF, this paper provides a theoretical model for how the potentially deleterious consequences of BDNF plasticity may be modulated by other endogenous factors. The peptide galanin may play such a role by regulating hippocampal excitability.

  2. Basic fibroblast growth factor protects against excitotoxicity and chemical hypoxia in both neonatal and adult rats.

    Science.gov (United States)

    Kirschner, P B; Henshaw, R; Weise, J; Trubetskoy, V; Finklestein, S; Schulz, J B; Beal, M F

    1995-07-01

    Basic fibroblast growth factor (bFGF) is a polypeptide growth factor that promotes neuronal survival. We recently found that systemic administration of bFGF protects against both excitotoxicity and hypoxia-ischemia in neonatal animals. In the present study, we examined whether systemically administered bFGF could prevent neuronal death induced by intrastriatal injection of N-methyl-D-aspartate (NMDA) or chemical hypoxia induced by intrastriatal injection of malonate in adult rats and 1-methyl-4-phenylpyridinium (MPP+) in neonatal rats. Systemic administration of bFGF (100 micrograms/kg) for three doses both before and after intrastriatal injection of either NMDA or malonate in adult rats produced a significant neuroprotective effect. In neonatal rats, bFGF produced dose-dependent significant neuroprotective effects against MPP+ neurotoxicity, with a maximal protection of approximately 50% seen with either a single dose of bFGF of 300 micrograms/kg or three doses of 100 micrograms/kg. These results show that systemic administration of bFGF is effective in preventing neuronal injury under circumstances in which the blood-brain barrier may be compromised, raising the possibility that this strategy could be effective in stroke.

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

    Directory of Open Access Journals (Sweden)

    Clotilde Lauro

    2015-01-01

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

  4. Activation of group III metabotropic glutamate receptors is neuroprotective in cortical cultures.

    Science.gov (United States)

    Bruno, V; Copani, A; Bonanno, L; Knoepfel, T; Kuhn, R; Roberts, P J; Nicoletti, F

    1996-08-22

    (RS)-alpha-Methyl-4-phosphonophenylglycine (MPPG) and (S)-alpha-methyl-3-carboxyphenylalanine (M3CPA), two novel preferential antagonists of group III metabotropic glutamate (mGlu) receptors, antagonized the neuroprotective activity of L-2-amino-4-phosphono-butanoate (L-AP4) or L-serine-O-phosphate in mice cultured cortical cells exposed to a toxic pulse of N-methyl-D-aspartate. In contrast, MPPG did not influence the neuroprotective activity of the selective group II mGlu receptor agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxy-cyclopropyl) glycine (DCG-IV). These results indicate that activation of group III mGu receptors exerts neuroprotective activity against excitotoxic neuronal death. At least one of the two major group III mGlu receptor subtypes, i.e. mGlu4 receptor, is expressed by cultured cortical neurons, as shown by immunocytochemical analysis with specific polyclonal antibodies. PMID:8880068

  5. Potentiation of glutamate release caused by delta—methrin and the possible mechanism associated with carbon monoxide pathway and protein kinase C

    Institute of Scientific and Technical Information of China (English)

    AiBM; LiuYG

    2002-01-01

    The acute neurotoxicity of delta-methrin is thought to be associated with the release of grutamate from synaptosomes in brain.However,the mechanism how delta-methrin enhances the glutamate release has still not been elucidated.Here we report that both carbon monoxide(CO) and the activator of protein kinase C(PKC),similarly to delta-methrin,potentiate the Ca2+-dependent glutamate release from rat cerebral cortical synaptosomes,otherwise,the release of glutamate is inhibited by zinc proporphyrin-9(ZnPP-9) and inhibitors of PKC or of protein kinase G(PKG).In addition,the inhibitors of ZnPP-9 PKC and PKG seem to weaken the enhancement of glutamate releas caused by delta-methrin.So,we conclude that CO signal transduction pathway and PKC mediate the glutamate release from synptosomes by delta-methrin.

  6. 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

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

    OpenAIRE

    Weifu Dong; Ting Li; Shuangfei Xiang; Piming Ma; Mingqing Chen

    2013-01-01

    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 ten...

  8. Mechanism for the activation of glutamate receptors

    Science.gov (United States)

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

  9. Motor Alterations Induced by Chronic 4-Aminopyridine Infusion in the Spinal Cord In vivo: Role of Glutamate and GABA Receptors

    Science.gov (United States)

    Lazo-Gómez, Rafael; Tapia, Ricardo

    2016-01-01

    Motor neuron (MN) degeneration is the pathological hallmark of MN diseases, a group of neurodegenerative disorders clinically manifested as muscle fasciculations and hyperreflexia, followed by paralysis, respiratory failure, and death. Ample evidence supports a role of glutamate-mediated excitotoxicity in motor death. In previous work we showed that stimulation of glutamate release from nerve endings by perfusion of the K+-channel blocker 4-aminopyridine (4-AP) in the rat hippocampus induces seizures and neurodegeneration, and that AMPA infusion in the spinal cord produces paralysis and MN death. On these bases, in this work we have tested the effect of the chronic infusion of 4-AP in the spinal cord, using implanted osmotic minipumps, on motor activity and on MN survival, and the mechanisms underlying this effect. 4-AP produced muscle fasciculations and motor deficits assessed in two motor tests, which start 2–3 h after the implant, which ameliorated spontaneously within 6–7 days, but no neurodegeneration. These effects were prevented by both AMPA and NMDA receptors blockers. The role of GABAA receptors was also explored, and we found that chronic infusion of bicuculline induced moderate MN degeneration and enhanced the hyperexcitation produced by 4-AP. Unexpectedly, the GABAAR agonist muscimol also induced motor deficits and failed to prevent the MN death induced by AMPA. We conclude that motor alterations induced by chronic 4-AP infusion in the spinal cord in vivo is due to ionotropic glutamate receptor overactivation and that blockade of GABAergic neurotransmission induces MN death under chronic conditions. These results shed light on the role of glutamatergic and GABAergic neurotransmission in the regulation of MN excitability in the spinal cord. PMID:27242406

  10. Novel di-aryl-substituted isoxazoles act as noncompetitive inhibitors of the system Xc(-) cystine/glutamate exchanger.

    Science.gov (United States)

    Newell, J L; Keyari, C M; McDaniel, S W; Diaz, P J; Natale, N R; Patel, S A; Bridges, R J

    2014-07-01

    The system xc(-) antiporter is a plasma membrane transporter that mediates the exchange of extracellular l-cystine with intracellular l-glutamate. This exchange is significant within the context of the CNS because the import of l-cystine is required for the synthesis of the antioxidant glutathione, while the efflux of l-glutamate has the potential to contribute to either excitatory signaling or excitotoxic pathology. Changes in the activity of the transport system have been linked to the underlying pathological mechanisms of a variety of CNS disorders, one of the most prominent of which is its highly enriched expression in glial brain tumors. In an effort to produce more potent system xc(-) blockers, we have been using amino-3-carboxy-5-methylisoxazole propionic acid (ACPA) as a scaffold for inhibitor development. We previously demonstrated that the addition of lipophilic aryl groups to either the #4 or #5 position on the isoxazole ring markedly increased the inhibitory activity at system xc(-). In the present work a novel series of analogues has been prepared in which aryl groups have been introduced at both the #4 and #5 positions. In contrast to the competitive action of the mono-substituted analogues, kinetic analyses indicate that the di-substituted isoxazoles block system xc(-)-mediated uptake of (3)H-l-glutamate into SNB-19 cells by a noncompetitive mechanism. These new analogues appear to be the first noncompetitive inhibitors identified for this transport system, as well as being among the most potent blockers identified to date. These diaryl-isoxazoles should be of value in assessing the physiological roles and molecular pharmacology of system xc(-).

  11. 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...... 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....

  12. Functional Comparison of the Two Bacillus anthracis Glutamate Racemases▿

    OpenAIRE

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

    2007-01-01

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

  13. The stressed synapse: the impact of stress and glucocorticoids on glutamate transmission

    OpenAIRE

    Popoli, Maurizio; Yan, Zhen; McEwen, Bruce; Sanacora, Gerard

    2011-01-01

    Mounting evidence suggests that acute and chronic stress, especially the stress-induced release of glucocorticoids, induces changes in glutamate neurotransmission in the prefrontal cortex and the hippocampus, thereby influencing some aspects of cognitive processing. In addition, dysfunction of glutamatergic neurotransmission is increasingly considered to be a core feature of stress-related mental illnesses. Recent studies have shed light on the mechanisms by which stress and glucocorticoids a...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Glutamate dehydrogenase (GDH), encoded by GLUD1, participates in the breakdown and synthesis of glutamate, the main excitatory neurotransmitter. In the CNS, besides its primary signaling function, glutamate is also at the crossroad of metabolic and neurotransmitter pathways. Importance of brain GDH...... 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...... transporters and of glutamine synthetase. Present data show that the lack of GDH in the CNS modifies the metabolic handling of glutamate without altering synaptic transmission....

  15. The effect of excitotoxic hippocampal lesions on simple and conditional discrimination learning in the rat.

    Science.gov (United States)

    Murray, T K; Ridley, R M

    1999-02-15

    The effect of excitotoxic lesions of the hippocampus on acquisition and reversal of simple and conditional tasks was investigated using a Y-maze. Hippocampal-lesioned rats were severely impaired on acquisition and reversal of a conditional visuo-spatial task (where different pairs of visually distinctive choice arms indicated whether a left or right arm choice was correct on that trial) and were unable to acquire a visuo-visual conditional discrimination (where the appearance of the start arm indicated which of the visually distinctive choice arms was correct irrespective of their left/right position). They were not impaired on acquisition or reversal of a simple spatial left/right discrimination task (where all arms had the same visual appearance) nor on acquisition of a visual discrimination (where the correct, visually distinctive, choice arm varied in its left/right position). Hippocampal-lesioned rats were, however, impaired on reversal of this visual discrimination task and on acquisition and reversal of another visual discrimination task in which the visually distinctive choice arms were less different from each other than in the first version of this task. The degree of impairment in the lesioned rats was related to task difficulty for the sham-operated rats and was not specific to tasks requiring spatial choices, visual discrimination or conditional responding. The impairment on conditional tasks was greater than the impairment on those non-conditional tasks which happened to be matched for task difficulty for the sham-operated rats, suggesting that the conditional demand may target the function of the hippocampus rather closely. Statistically worse than chance performance by hippocampal-lesioned (and sham-operated) rats at the beginning of reversal testing, which was given 24 h after achieving criterion on acquisition of that task, indicated that hippocampal-lesioned rats simultaneously exhibited good memory but impaired learning for the type of

  16. Procedural Performance Benefits after Excitotoxic Hippocampal Lesions in the Rat Sequential Reaction Time Task.

    Science.gov (United States)

    Busse, Sebastian; Schwarting, Rainer K W

    2016-01-01

    It is widely agreed upon that hippocampal function is linked to episodic-like and spatial memory across various species, for example, rodents. However, the interplay between hippocampal function and other types of learning and memory, like procedural stimulus-response or sequential learning, is less clear. Recently (Eckart et al. in Hippocampus 22:1202-1214, 2012), we showed that excitotoxic hippocampal lesions, which mainly affected its dorsal part, led not only to the expected deficits in a spatial and episodic-like memory task, namely the object place recognition test, but also to substantial improvements in terms of speed and accuracy in a rat adaption of the human sequential reaction time task (SRTT). The design of that experiment, however, which included fixed test durations per training day, led to the fact that lesioned animals gained more instrumental experience, which may partly have accounted for their enhanced performance. In order to rule out such a potential confound, we performed the present experiment on rats with similar ibotenic lesions aiming at the dorsal hippocampus, but we now kept the amount of correct instrumental responses and reinforcements on the same level as in controls. Our data revealed that lesioned animals were still able to complete the SRTT in a substantially smaller amount of time, when compared to control and sham-operated animals, although no differences were observable in terms of speed or accuracy. Also, the animals with lesions showed impaired extinction in a subsequent test where rewards were omitted. The former effect can primarily be attributed to shorter post-reinforcement pauses in the lesioned animals, and the possible mechanisms of this and the extinction effect will be addressed in the discussion.

  17. Glutamate formation via the leucine-to-glutamate pathway of rat pancreas.

    Science.gov (United States)

    Schachter, David; Buteau, Jean

    2014-06-01

    The leucine-to-glutamate (Leu→Glu) pathway, which metabolizes the carbon atoms of l-leucine to form l-glutamate, was studied by incubation of rat tissue segments with l-[U-(14)C]leucine and estimation of the [(14)C]glutamate formed. Metabolism of the leucine carbon chain occurs in most rat tissues, but maximal activity of the Leu→Glu pathway for glutamate formation is limited to the thoracic aorta and pancreas. In rat aorta, the Leu→Glu pathway functions to relax the underlying smooth muscle; its functions in the pancreas are unknown. This report characterizes the Leu→Glu pathway of rat pancreas and develops methods to examine its functions. Pancreatic segments effect net formation of glutamate on incubation with l-leucine, l-glutamine, or a mix of 18 other plasma amino acids at their concentrations in normal rat plasma. Glutamate formed from leucine remains mainly in the tissue, whereas that from glutamine enters the medium. The pancreatic Leu→Glu pathway uses the leucine carbons for net glutamate formation; the α-amino group is not used; the stoichiometry is as follows: 1 mol of leucine yields 2 mol of glutamate (2 leucine carbons per glutamate) plus 2 mol of CO2. Comparison of the Leu→Glu pathway in preparations of whole pancreatic segments, isolated acini, and islets of Langerhans localizes it in the acini; relatively high activity is found in cultures of the AR42J cell line and very little in the INS-1 832/13 cell line. Pancreatic tissue glutamate concentration is homeostatically regulated in the range of ∼1-3 μmol/g wet wt. l-Valine and leucine ethyl, benzyl, and tert-butyl esters inhibit the Leu→Glu pathway without decreasing tissue total glutamate. PMID:24699330

  18. Cardiovascular responses to microinjection of L-glutamate into the NTS in AV3V-lesioned rats.

    Science.gov (United States)

    Vieira, Alexandre Antonio; Colombari, Eduardo; De Luca, Laurival A; de Almeida Colombari, Débora Simões; Menani, José V

    2004-10-29

    The excitatory amino acid L-glutamate injected into the nucleus of the solitary tract (NTS) in unanesthetized rats similar to peripheral chemoreceptor activation increases mean arterial pressure (MAP) and reduces heart rate. In this study, we investigated the effects of acute (1 day) and chronic (15 days) electrolytic lesions of the preoptic-periventricular tissue surrounding the anteroventral third ventricle (AV3V region) on the pressor and bradycardic responses induced by injections of L-glutamate into the NTS or peripheral chemoreceptor activation in unanesthetized rats. Male Holtzman rats with sham or electrolytic AV3V lesions and a stainless steel cannula implanted into the NTS were used. Differently from the pressor responses (28+/-3 mm Hg) produced by injections into the NTS of sham-lesioned rats, L-glutamate (5 nmol/100 nl) injected into the NTS reduced MAP (-26+/-8 mm Hg) or produced no effect (2+/-7 mm Hg) in acute and chronic AV3V-lesioned rats, respectively. The bradycardia to l-glutamate into the NTS and the cardiovascular responses to chemoreflex activation with intravenous potassium cyanide or to baroreflex activation with intravenous phenylephrine or sodium nitroprusside were not modified by AV3V lesions. The results show that the integrity of the AV3V region is essential for the pressor responses to L-glutamate into the NTS but not for the pressor responses to chemoreflex activation, suggesting dissociation between the central mechanisms involved in these responses.

  19. Effect of cannabis on glutamate signalling in the brain: A systematic review of human and animal evidence.

    Science.gov (United States)

    Colizzi, Marco; McGuire, Philip; Pertwee, Roger G; Bhattacharyya, Sagnik

    2016-05-01

    Use of cannabis or delta-9-tetrahydrocannabinol (Δ9-THC), its main psychoactive ingredient, is associated with psychotic symptoms or disorder. However, the neurochemical mechanism that may underlie this psychotomimetic effect is poorly understood. Although dopaminergic dysfunction is generally recognized as the final common pathway in psychosis, evidence of the effects of Δ9-THC or cannabis use on dopaminergic measures in the brain is equivocal. In fact, it is thought that cannabis or Δ9-THC may not act on dopamine firing directly but indirectly by altering glutamate neurotransmission. Here we systematically review all studies examining acute and chronic effects of cannabis or Δ9-THC on glutamate signalling in both animals and man. Limited research carried out in humans tends to support the evidence that chronic cannabis use reduces levels of glutamate-derived metabolites in both cortical and subcortical brain areas. Research in animals tends to consistently suggest that Δ9-THC depresses glutamate synaptic transmission via CB1 receptor activation, affecting glutamate release, inhibiting receptors and transporters function, reducing enzyme activity, and disrupting glutamate synaptic plasticity after prolonged exposure. PMID:26987641

  20. [Autoimmune mechanisms of modulation of the activity of glutamate receptors in children with epilepsy and craniocerebral injury].

    Science.gov (United States)

    Pinelis, V G; Sorokina, E G

    2008-01-01

    The role of glutamate receptors and their hyperstimulation in the development of autoimmune processes is discussed with reference to brain pathology associated with hypoxia and ischemia. Epilepsy, paroxismal condition, and craniocerebral injury (CCI) in children are shown to be accompanied by a rise in the levels of antibodies against AMPA and NMDA receptors of glutamate and nitric oxide markers (cGMP, nitrates + nitrites). Also enhanced in epilepsy and paroxismal condition are the levels of cGMP and antibodies against AMPA(GluR1) receptors of glutamate. Acute CCI period is characterized by a marked change in the levels of NO metabolites and antibodies to two subtypes of glutamate receptor, AMPA and NMDA. The levels of antibodies to NMDA(NR2A) receptors are significantly different within 1 day after CCI depending on its outcome. Unfavourable outcome of CCI is associated with the lowest level of antibodies and high NO metabolite content. Relationship between the levels of NO and antibodies against glutamate receptors is discussed with the use of experimental data. It is concluded that antibodies to glutamate receptors and receptor hyperstimulation play an important role in pathogenesis of hypoxia. PMID:19189459

  1. Functional and structural remodeling of glutamate synapses in prefrontal and frontal cortex induced by behavioral stress

    Directory of Open Access Journals (Sweden)

    Laura eMusazzi

    2015-04-01

    Full Text Available Increasing evidence has shown that the pathophysiology of neuropsychiatric disorders, including mood disorders, is associated with abnormal function and regulation of the glutamatergic system. Consistently, preclinical studies on stress-based animal models of pathology showed that glucocorticoids and stress exert crucial effects on neuronal excitability and function, especially in cortical and limbic areas. In prefrontal and frontal cortex, acute stress was shown to induce enhancement of glutamate release/transmission dependent on activation of corticosterone receptors. Although the mechanisms whereby stress affects glutamate transmission have not yet been fully understood, it was shown that synaptic, non-genomic action of corticosterone is required to increase the readily releasable pool of glutamate vesicles but is not sufficient to enhance transmission in prefrontal and frontal cortex. Slower, partly genomic mechanisms are probably necessary for the enhancement of glutamate transmission induced by stress.Combined evidence has suggested that the changes in glutamate release and transmission are responsible for the dendritic remodeling and morphological changes induced by stress and it has been argued that sustained alterations of glutamate transmission may play a key role in the long-term structural/functional changes associated with mood disorders in patients. Intriguingly, modifications of the glutamatergic system induced by stress in the prefrontal cortex seem to be biphasic. Indeed, while the fast response to stress suggests an enhancement in the number of excitatory synapses, synaptic transmission and working memory, long-term adaptive changes -including those consequent to chronic stress- induce opposite effects. Better knowledge of the cellular effectors involved in this biphasic effect of stress may be useful to understand the pathophysiology of stress-related disorders, and open new paths for the development of therapeutic approaches.

  2. Screening for glutamate-induced and dexamethasone-downregulated epilepsy-related genes in rats by mRNA differential display

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Background It is known that excessive release of glutamate can induce excitotoxicity in neurons and lead to seizure. Dexamethasone has anti-seizure function. The aim of this study was to investigate glutamate- dexamethasone interaction in the pathogenesis of epilepsy, identify differentially expressed genes in the hippocampus of glutamate-induced epileptic rats by mRNA differential display, and observe the effects of dexamethasone on these genes expression.Methods Seizure models were established by injecting 5 μl (250 μg/μl) monosodium glutamate (MSG) into the lateral cerebral ventricle in rats. Dexamethasone (5 mg/kg) was injected intraperitoneally at 30 minutes after MSG inducing convulsion. The rats' behavior and electroencephalogram (EEG) were then recorded for 1 hour. The effects of dexamethasone on gene expression were observed in MSG-induced epileptic rats at 1 hour and 6 hours after the onset of seizure by mRNA differential display. The differentially expressed genes were confirmed by Dot blot.Results EEG and behaviors showed that MSG did induce seizure, and dexamethasone could clearly alleviate the symptom. mRNA differential display showed that MSG increased the expression of some genes in epileptic rats and dexamethasone could downregulate their expression. From more than 10 differentially expressed cDNA fragments, we identified a 226 bp cDNA fragment that was expressed higher in the hippocampus of epileptic rats than that in the control group. Its expression was reduced after the administration of dexamethasone. Sequence analysis and protein alignment showed that the predicted amino acid sequence of this cDNA fragment kept 43% identity to agmatinase, a member of the ureohydrolase superfamily. Conclusions The results of the current study suggest that the product of the 226 bp cDNA has a function similar to agmatinase. Dexamethasone might relax alleviate seizure by inhibiting expression of the gene.

  3. Flavor Preferences Conditioned by Dietary Glutamate.

    Science.gov (United States)

    Ackroff, Karen; Sclafani, Anthony

    2016-07-01

    Our understanding of the molecular basis of umami taste and its appetitive qualities has been greatly aided by studies in laboratory rodents. This review describes methods for testing responses to the prototypical umami substance monosodium glutamate (MSG) in rodents. Two techniques, forced exposure to MSG and 2-bottle choice tests with ascending concentrations, were used to evaluate the responses to the taste of umami itself, and 2 other methods used oral or postoral MSG to modify the responses to other flavors. Intake and preference for MSG are enhanced in mice by experience with MSG and with other nutrients with positive postoral effects. In addition, flavor preferences are enhanced in mice and rats by gastric or intestinal MSG infusions via an associative learning process. Even mice with an impaired or absent ability to taste MSG can learn to prefer a flavor added to an MSG solution, supporting the notion that glutamate acts postorally. The more complex flavor of dashi seasoning, which includes umami substances (inosinate, glutamate), is attractive to rodents, but dashi does not condition flavor preferences. Details of the postoral glutamate detection process and the nature of the signal involved in learned preferences are still uncertain but probably involve gastric or intestinal sensors or both and vagal transmission. Some findings suggest that postoral glutamate effects may enhance food preferences in humans, but this requires further study. PMID:27422522

  4. Croton zehntneri Essential oil prevents acetaminophen-induced acute hepatotoxicity in mice

    OpenAIRE

    Maria Goretti R. Queiroz; José Henrique L. Cardoso; Adriana R. Tomé; Roberto C. P. Lima Jr.; Jamile M. Ferreira; Daniel F. Sousa; Felipe C. Lima; Campos, Adriana R.

    2008-01-01

    Hepatoprotective activity of Croton zehntneri Pax & Hoffman (Euphorbiaceae) leaf essential oil (EOCz) was evaluated against single dose of acetaminophen-induced (500 mg/kg, p.o.) acute hepatotoxicity in mice. EOCz significantly protected the hepatotoxicity as evident from the activities of serum glutamate pyruvate transaminase (GPT), serum glutamate oxaloacetate transaminase (GOT) activities, that were significantly (p

  5. Key Proteins of Activating Cell Death Can Be Predicted through a Kainic Acid-Induced Excitotoxic Stress

    Directory of Open Access Journals (Sweden)

    Hsiu-Ling Tsai

    2015-01-01

    Full Text Available Epilepsy is a major neurological disorder characterized by spontaneous seizures accompanied by neurophysiological changes. Repeated seizures can damage the brain as neuronal death occurs. A better understanding of the mechanisms of brain cell death could facilitate the discovery of novel treatments for neurological disorders such as epilepsy. In this study, a model of kainic acid- (KA- induced neuronal death was established to investigate the early protein markers associated with apoptotic cell death due to excitotoxic damage in the rat cortex. The results indicated that KA induces both apoptotic and necrotic cell death in the cortex. Incubation with high concentrations (5 and 500 μM, >75% and low concentrations (0.5 pM: 95% and 50 nM: 8% of KA for 180 min led to necrotic and apoptotic cell death, respectively. Moreover, proteomic analysis using two-dimensional gel electrophoresis and mass spectrometry demonstrated that antiapoptotic proteins, including heat shock protein 70, 3-mercaptopyruvate sulfurtransferase, tubulin-B-5, and pyruvate dehydrogenase E1 component subunit beta, were significantly higher in apoptosis than in necrosis induced by KA. Our findings provide direct evidence that several proteins are associated with apoptotic and necrotic cell death in excitotoxicity model. The results indicate that these proteins can be apoptotic biomarkers from the early stages of cell death.

  6. Role of HSP70 in motoneuron survival after excitotoxic stress in a rat spinal cord injury model in vitro.

    Science.gov (United States)

    Shabbir, Ayisha; Bianchetti, Elena; Cargonja, Renato; Petrovic, Antonela; Mladinic, Miranda; Pilipović, Kristina; Nistri, Andrea

    2015-12-01

    The outcome for gait recovery from paralysis due to spinal lesion remains uncertain even when damage is limited. One critical factor is the survival of motoneurons, which are very vulnerable cells. To clarify the early pathophysiological mechanisms of spinal damage, an in vitro injury model of the rat spinal cord caused by moderate excitotoxicity was used. With this preparation we investigated whether motoneuron survival was dependent on the expression of the neuroprotective protein HSP70. In the present study excitotoxicity evoked by kainate induced delayed (24 h) loss (35%) of motoneurons, which became pyknotic with translocation of the cell death biomarker apoptosis-inducing factor (AIF) to the nucleus. This process was concomitant with suppression of locomotor network electrical activity. Surviving cells showed strong expression of HSP70 without nuclear AIF. The HSP70 inhibitor VER155008 per se induced neurotoxicity similar to that of kainate, while the HSP90 inhibitor geldanamycin did not damage spinal tissue. Electrophysiological recording following kainate or VER155008 indicated depression of motoneuron field potentials, with decreased excitability and impaired synaptic transmission. When these two drugs were applied together, more intense neurotoxicity emerged. Our data indicate that HSP70 was one important contributor to motoneuron survival and suggest that enhancing HSP70 activity is a potential future strategy for neuroprotecting these cells. PMID:26490753

  7. Cooperation between BDNF and glutamate in the regulation of synaptic transmission and neuronal development.

    Science.gov (United States)

    Martin, Jean-Luc; Finsterwald, Charles

    2011-01-01

    Ample evidence supports a role of brain-derived neurotrophic factor (BDNF) in the survival and differentiation of selective populations of neurons in the peripheral and central nervous systems. In addition to its trophic actions, BDNF exerts acute effects on synaptic transmission and plasticity. In particular, BDNF enhances excitatory synaptic transmission through pre- and postsynaptic mechanisms. In this regard, BDNF enhances glutamate release, the frequency of miniature excitatory postsynaptic currents (mEPSCs), NMDA receptor activity and the phosphorylation of NMDA receptor subunits. Our recent studies revealed a novel cooperative interaction between BDNF and glutamate in the regulation of dendritic development. Indeed, we found that the effects of BDNF on dendritic growth of cortical neurons require both the stimulation of cAMP response element-binding protein (CREB) phosphorylation by BDNF and the activation of the CREB-regulated transcription coactivator 1 (CRTC1) by glutamate. Together, these studies highlight the importance of the cooperation between BDNF and glutamate in the regulation of synaptic transmission and neuronal development.

  8. 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

  9. Development and Genetics of Glutamate Taste Preferencea

    OpenAIRE

    Gary K Beauchamp; Bachmanov, Alexander; STEIN, LESLIE J

    1998-01-01

    The sodium salt of glutamic acid, monosodium glutamate (MSG), and certain other amino acids and ribonucleotides impart a unique taste sensation often called ‘umami.’ We have been studying preference for umami substances in two systems: inbred mice and human infants. In 48-hr tests, C57BL/6J (C57) mice exhibit a lower preference threshold for MSG than do 129/J mice. Moreover, C57 mice show a greater preference across a wide range of concentrations and, at high (e.g., 300–600 mM) concentrations...

  10. Binding of Glutamate to the Umami Receptor

    OpenAIRE

    Lopez Cacales, J.; Oliviera Costa, S.; de Groot, B.; Walters, D

    2010-01-01

    Abstract The umami taste receptor is a heterodimer composed of two members of the T1R taste receptor family: T1R1 and T1R3. It detects glutamate in humans, and is a more general amino acid detector in other species. We have constructed homology models of the ligand binding domains of the human umami receptor (based on crystallographic structures of the metabotropic glutamate receptor of the central nervous system). We have carried out molecular dynamics simulations of the ligand bi...

  11. 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

  12. 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.

  13. Biological Signatures of Brain Damage Associated with High Serum Ferritin Levels in Patients with Acute Ischemic Stroke and Thrombolytic Treatment

    Directory of Open Access Journals (Sweden)

    Mónica Millán

    2008-01-01

    Full Text Available Background and purpose: Increased body iron stores have been related to greater oxidative stress and brain injury in clinical and experimental cerebral ischemia and reperfusion. We aimed to investigate the biological signatures of excitotoxicity, inflammation and blood brain barrier disruption potentially associated with high serum ferritin levels-related damage in acute stroke patients treated with i.v. t-PA.

  14. Regulation of Glutamate Receptors by Their Auxiliary Subunits

    OpenAIRE

    Tomita, Susumu

    2010-01-01

    Glutamate receptors are major excitatory receptors in the brain. Recent findings have established auxiliary subunits of glutamate receptors as critical modulators of synaptic transmission, synaptic plasticity and neurological disorder. The elucidation of the molecular rules governing glutamate receptors and subunits will improve our understanding of synapses and of neural-circuit regulation in the brain.

  15. Combined calpain-induced downregulation of TrkB-FL and TrkB-T1 upregulation causes neuronal death in excitotoxicity and ischemia

    OpenAIRE

    Díaz-Guerra, Margarita; Vidaurre, Oscar G.; Gascón, Sergio

    2012-01-01

    Electronic response to "Excitotoxicity downregulates TrkB.FL signaling and upregulates the neuroprotective truncated TrkB receptors in cultured hippocampal and striatal neurons" Gomes, et al., 32(13): 4610-4622; doi: 10.1523/JNEUROSCI.0374-12.2012

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

    Directory of Open Access Journals (Sweden)

    Weifu Dong

    2013-11-01

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

  17. AMPK Activation Affects Glutamate Metabolism in Astrocytes

    DEFF Research Database (Denmark)

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

    2015-01-01

    skeleton into the TCA cycle was reduced. On the other hand, glutamate uptake into the astrocytes as well as its conversion to glutamine catalyzed by glutamine synthetase was not affected by AMPK activation. Interestingly, synthesis and release of citrate, which are hallmarks of astrocytic function, were...

  18. Targeting glia with N-Acetylcysteine modulates brain glutamate and behaviours relevant to neurodevelopmental disorders in C57BL/6J mice

    Directory of Open Access Journals (Sweden)

    Alice Marie Sybille Durieux

    2015-12-01

    Full Text Available An imbalance between excitatory (E glutamate and inhibitory (I GABA transmission may underlie neurodevelopmental conditions such as Autism Spectrum Disorder (ASD and schizophrenia. This may be direct, through alterations in synaptic genes, but there is increasing evidence for the importance of indirect modulation of E/I balance through glial mechanisms. Here we used C57BL/6J mice to test the hypothesis that striatal glutamate levels can be shifted by N-acetylcysteine (NAC, which acts at the cystine-glutamate antiporter of glial cells. Striatal glutamate was quantified in-vivo using proton magnetic resonance spectroscopy. The effect of NAC on behaviours relevant to ASD was examined in a separate cohort. NAC induced a time-dependent decrease in striatal glutamate, which recapitulated findings of lower striatal glutamate reported in ASD. NAC-treated animals were significantly less active and more anxious in the open field test; and NAC-treated females had significantly impaired prepulse inhibition of startle response. This at least partly mimics greater anxiety and impaired sensorimotor gating reported in neurodevelopmental disorders. Thus glial mechanisms regulate glutamate acutely and have functional consequences even in adulthood. Glial cells may be a potential drug target for the development of new therapies for neurodevelopmental disorders across the life-span.

  19. Glutamate Receptor Agonists and Glutamate Transporter Antagonists Regulate Differentiation of Osteoblast Lineage Cells.

    Science.gov (United States)

    Xie, Wenjie; Dolder, Silvia; Siegrist, Mark; Wetterwald, Antoinette; Hofstetter, Willy

    2016-08-01

    Development and function of osteoblast lineage cells are regulated by a complex microenvironment consisting of the bone extracellular matrix, cells, systemic hormones and cytokines, autocrine and paracrine factors, and mechanical load. Apart from receptors that transduce extracellular signals into the cell, molecular transporters play a crucial role in the cellular response to the microenvironment. Transporter molecules are responsible for cellular uptake of nutritional components, elimination of metabolites, ion transport, and cell-cell communication. In this report, the expression of molecular transporters in osteoblast lineage cells was investigated to assess their roles in cell development and activity. Low-density arrays, covering membrane and vesicular transport molecules, were used to assess gene expression in osteoblasts representing early and late differentiation states. Receptors and transporters for the amino acid glutamate were found to be differentially expressed during osteoblast development. Glutamate is a neurotransmitter in the central nervous system, and the mechanisms of its release, signal transduction, and cellular reabsorption in the synaptic cleft are well understood. Less clear, however, is the control of equivalent processes in peripheral tissues. In primary osteoblasts, inhibition of glutamate transporters with nonselective inhibitors leads to an increase in the concentration of extracellular glutamate. This change was accompanied by a decrease in osteoblast proliferation, stimulation of alkaline phosphatase, and the expression of transcripts encoding osteocalcin. Enzymatic removal of extracellular glutamate abolished these pro-differentiation effects, as did the inhibition of PKC- and Erk1/2-signaling pathways. These findings demonstrate that glutamate signaling promotes differentiation and activation of osteoblast lineage cells. Consequently, the glutamate system may represent a putative therapeutic target to induce an anabolic response

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-16

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

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

    International Nuclear Information System (INIS)

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

  2. Growth hormone reverses excitotoxic damage induced by kainic acid in the green iguana neuroretina.

    Science.gov (United States)

    Ávila-Mendoza, José; Mora, Janeth; Carranza, Martha; Luna, Maricela; Arámburo, Carlos

    2016-08-01

    It is known that growth hormone (GH) is expressed in extrapituitary tissues, including the nervous system and ocular tissues, where it is involved in autocrine/paracrine actions related to cell survival and anti-apoptosis in several vertebrates. Little is known, however, in reptiles, so we analyzed the expression and distribution of GH in the eye of green iguana and its potential neuroprotective role in retinas that were damaged by the intraocular administration of kainic acid (KA). It was found, by Western blotting, that GH-immunoreactivity (GH-IR) was expressed as two isoforms (15 and 26kDa, under reducing conditions) in cornea, vitreous, retina, crystalline, iris and sclera, in varying proportions. Also, two bands for the growth hormone receptor (GHR)-IR were observed (70 and 44kDa, respectively) in the same tissues. By immunofluorescence, GH-IR was found in neurons present in several layers of the neuroretina (inner nuclear [INL], outer nuclear [ONL] and ganglion cell [GCL] layers) as determined by its co-existence with NeuN, but not in glial cells. In addition, GH and GHR co-expression was found in the same cells, suggesting paracrine/autocrine interactions. KA administration induced retinal excitotoxic damage, as determined by a significant reduction of the cell density and an increase in the appearance of apoptotic cells in the INL and GCL. In response to KA injury, both endogenous GH and Insulin-like Growth Factor I (IGF-I) expression were increased by 70±1.8% and 33.3±16%, respectively. The addition of exogenous GH significantly prevented the retinal damage produced by the loss of cytoarchitecture and cell density in the GCL (from 4.9±0.79 in the control, to 1.45±0.2 with KA, to 6.35±0.49cell/mm(2) with KA+GH) and in the INL (19.12±1.6, 10.05±1.9, 21.0±0.8cell/mm(2), respectively) generated by the long-term effect of 1mM KA intraocular administration. The co-incubation with a specific anti-GH antibody, however, blocked the protective effect of GH

  3. Shifts in striatal responsivity evoked by chronic stimulation of dopamine and glutamate systems.

    Science.gov (United States)

    Canales, J J; Capper-Loup, C; Hu, D; Choe, E S; Upadhyay, U; Graybiel, A M

    2002-10-01

    Dopamine and glutamate are key neurotransmitters in cortico-basal ganglia loops affecting motor and cognitive function. To examine functional convergence of dopamine and glutamate neurotransmitter systems in the basal ganglia, we evaluated the long-term effects of chronic stimulation of each of these systems on striatal responses to stimulation of the other. First we exposed rats to chronic intermittent cocaine and used early-gene assays to test the responsivity of the striatum to subsequent acute motor cortex stimulation by application of the GABA(A) (gamma-aminobutyric acid alpha subunit) receptor antagonist, picrotoxin. Reciprocally, we studied the effects of chronic intermittent motor cortex stimulation on the capacity for subsequent acute dopaminergic treatments to induce early-gene activation in the striatum. Prior treatment with chronic intermittent cocaine induced motor sensitization and significantly potentiated the striatal expression of Fos-family early genes in response to stimulation of the motor cortex. Contrary to this, chronic intermittent stimulation of the motor cortex down-regulated cocaine-induced gene expression in the striatum, but enhanced striatal gene expression induced by a full D1 receptor agonist (SKF 81297) and did not change the early-gene response elicited by a D2 receptor antagonist (haloperidol). These findings suggests that repeated dopaminergic stimulation produces long-term enhancement of corticostriatal signalling from the motor cortex, amplifying cortically evoked modulation of the basal ganglia. By contrast, persistent stimulation of the motor cortex inhibits cocaine-stimulated signalling in the striatum, but not signalling mediated by individual dopamine receptor sites, suggesting that chronic cortical hyperexcitability produces long-term impairment of dopaminergic activity and compensation at the receptor level. These findings prompt a model of the basal ganglia function as being regulated by opposing homeostatic dopamine-glutamate

  4. 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.

  5. 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.

  6. The endocannabinoid N-arachidonoyldopamine (NADA) exerts neuroprotective effects after excitotoxic neuronal damage via cannabinoid receptor 1 (CB(1)).

    Science.gov (United States)

    Grabiec, Urszula; Koch, Marco; Kallendrusch, Sonja; Kraft, Robert; Hill, Kerstin; Merkwitz, Claudia; Ghadban, Chalid; Lutz, Beat; Straiker, Alex; Dehghani, Faramarz

    2012-03-01

    Endocannabinoids exert numerous effects in the CNS under physiological and pathological conditions. The aim of the present study was to examine whether the endocannabinoid N-arachidonoyldopamine (NADA) may protect neurons in excitotoxically lesioned organotypic hippocampal slice cultures (OHSC). OHSC were excitotoxically lesioned by application of N-methyl-d-aspartate (NMDA, 50 μM) for 4 h and subsequently treated with different NADA concentrations (0.1 pM-50 μM) alone or in combination with cannabinoid receptor antagonists. NADA protected dentate gyrus granule cells and caused a slight reduction in the number of microglial cells. The number of degenerated neurons significantly decreased between 100 pM and 10 μM NADA (p NADA mediated neuroprotection, we applied the cannabinoid (CB) receptor 1 (CB(1)) inverse agonist/antagonist AM251, CB(2) inverse agonist/antagonist AM630, abnormal-cannabidiol (abn-CBD)-sensitive receptor antagonist O-1918, transient receptor potential channel V1 (TRPV1) antagonist 6-iodonordihydrocapsaicin and A1 (TRPA1) antagonist HC-030031. Neuroprotective properties of low (1 nM) but not high (10 μM) NADA concentrations were solely blocked by AM251 and were absent in CB(1)(-/-) mice. AM630, O-1918, 6-iodonordihydrocapsaicin and HC-030031 showed no effects at all NADA concentrations applied. Our findings demonstrate that NADA protects dentate gyrus granule cells by acting via CB(1). NADA reduced the number of microglial cells at distinct concentrations. TRPV1 and TRPA1 were not involved in NADA mediated neuroprotection. Thus, our data implicate that NADA mediated activation of neuronal CB(1) may serve as a novel pharmacological target to mitigate symptoms of neuronal damage.

  7. Effects of KR-33028, a novel Na+/H+ exchanger-1 inhibitor, on glutamate-induced neuronal cell death and ischemia-induced cerebral infarct.

    Science.gov (United States)

    Lee, Bo Kyung; Lee, Dong Ha; Park, Sok; Park, Sung Lyea; Yoon, Jae-Seok; Lee, Min Goo; Lee, Sunkyung; Yi, Kyu Yang; Yoo, Sung Eun; Lee, Kyung Hee; Kim, You-Sun; Lee, Soo Hwan; Baik, Eun Joo; Moon, Chang-Hyun; Jung, Yi-Sook

    2009-01-12

    We investigated the effects of a novel Na(+)/H(+) exchanger-1 (NHE-1) inhibitor KR-33028 on glutamate excitotoxicity in cultured neuron cells in vitro and cerebral infarct in vivo by comparing its potency with that of zoniporide, a well-known, highly potent NHE-1 inhibitor. KR-33028 inhibited NHE-1 activation in a concentration-dependent manner (IC(50)=2.2 nM), with 18-fold greater potency than that of zoniporide (IC(50)=40.7 nM). KR-33028 significantly attenuated glutamate-induced LDH release with approximately 100 times lower EC(25) than that of zoniporide in cortical neurons in vitro (EC(25) of 0.007 and 0.81 microM, respectively), suggesting its 100-fold greater potency than zoniporide in producing anti-necrotic effect. In addition, the EC(50) of KR-33028 for anti-apoptotic effect was 100 times lower than that of zoniporide shown by TUNEL positivity (0.005 and 0.62 microM, respectively) and caspase-3 activity (0.01 and 2.64 microM, respectively). Furthermore, the EC(50) value of KR-33028 against glutamate-induced intracellular Ca(2+) overload was also 100 times lower than that of zoniporide (EC(50) of 0.004 and 0.65 microM, respectively). In the in vivo cerebral infarct model (60 min middle cerebral artery occlusion followed by 24 h reperfusion), KR-33028 reduced infarct size in a dose-dependent manner. Its ED(25) value, however, was quite similar to that of zoniporide (ED(25) of 0.072 and 0.097 mg/kg, respectively). Hence these results suggest that the novel NHE-1 inhibitor, KR-33028, could be an efficient therapeutic tool to protect neuronal cells against ischemic injury.

  8. The Glutamine-Glutamate/GABA Cycle

    DEFF Research Database (Denmark)

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

    2015-01-01

    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......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...... information about glutamine transfer. The present review will give information about glutamine trafficking and the tools used to map it as exemplified by discussions of published work employing brain cell cultures as well as intact animals. It will be documented that considerably more glutamine is transferred...

  9. 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.

  10. AMPA and NMDA glutamate receptors are found in both peptidergic and non-peptidergic primary afferent neurons in the rat

    OpenAIRE

    Willcockson, Helen; Valtschanoff, Juli

    2008-01-01

    Two distinct classes of nociceptive primary afferents, peptidergic and non-peptidergic, respond similarly to acute noxious stimulation; however the peptidergic afferents are more likely to play a role in inflammatory pain, while the non-peptidergic afferents may be more characteristically involved in neuropathic pain. Using multiple immunofluorescence, we determined the proportions of neurons in the rat L4 dorsal root ganglion (DRG) that co-express AMPA or NMDA glutamate receptors and markers...

  11. Metabotropic glutamate receptors depress glutamate-mediated synaptic input to rat midbrain dopamine neurones in vitro

    OpenAIRE

    Wigmore, Mark A; Lacey, Michael G

    1998-01-01

    Glutamate (AMPA receptor-mediated) excitatory postsynaptic potentials (e.p.s.ps.), evoked by electrical stimulation rostral to the recording site, were examined by intracellular microelectrode recording from dopamine neurones in parasagittal slices of rat ventral midbrain.The e.p.s.p. was depressed by the group III metabotropic glutamate (mGlu) receptor agonist L-2-amino-4-phosphonobutyric acid (L-AP4; 0.01–30 μM) by up to 60% with an EC50 of 0.82 μM. The depression induced by L-AP4 (3 μM) wa...

  12. Pharmacological evaluation of glutamate transporter 1 (GLT-1) mediated neuroprotection following cerebral ischemia/reperfusion injury.

    Science.gov (United States)

    Verma, Rajkumar; Mishra, Vikas; Sasmal, Dinakar; Raghubir, Ram

    2010-07-25

    Recently glutamate transporters have emerged as a potential therapeutic target in a wide range of acute and chronic neurological disorders, owing to their novel mode of action. The modulation of GLT-1, a major glutamate transporter has been shown to exert neuroprotection in various models of ischemic injury and motoneuron degeneration. Therefore, an attempt was made to explore its neuroprotective potential in cerebral ischemia/reperfusion injury using ceftriaxone, a GLT-1 modulator. Pre-treatment with ceftriaxone (100mg/kg. i.v) for five days resulted in a significant reduction (Pceftriaxone-mediated increased glutamine synthetase activity by dihydrokainate (DHK), a GLT-1 specific inhibitor, confirms the specific effect of ceftriaxone on GLT-1 activity. In addition, ceftriaxone also induced a significant (P<0.01) increase in [(3)H]-glutamate uptake, mediated by GLT-1 in glial enriched preparation, as evidenced by use of DHK and DL-threo-beta-benzyloxyaspartate (DL-TBOA). Thus, the present study provides overwhelming evidence that modulation of GLT-1 protein expression and activity confers neuroprotection in cerebral ischemia/reperfusion injury.

  13. Relationship between glutamate in the limbic system and hypothalamus-pituitary-adrenal axis after middle cerebral artery occlusion in rats

    Institute of Scientific and Technical Information of China (English)

    何明利; 陈漫娥; 王景周; 郭光华; 郑衍平; 蒋晓江; 张猛

    2003-01-01

    Objective To investigate the features of glutamate activity in the limbic system and the effects of glutamate on the activation of the hypothalamus-pituitary-adrenal (HPA) axis throughout both acute cerebral ischemia and reperfusion.Methods The changes in glutamate content in the nervous cell gap, in corticotrophin releasing hormone (CHR) mRNA expression level in brain tissue, and in adrenocorticotropic hormone in blood plasma at different time-points after middle cerebral artery occlusion (MCAO) in rats were determined respectively with high-performance liquid chomatography (HPLC) and in situ hybridization.Results Glutamate content in the hippocampus and the hypothalamus increased rapidly at ischemia 15 minutes, and reached peak value (the averages were 21.05 mg/g±2.88 mg/g and 14.20 mg/g±2.58 mg/g, respectively) at 1 hour after middle cerebral artery occlusion. During recirculation, it returned rapidly to the baseline level. At 24 hours after reperfusion, it went up once more, and remained at a relative high level until 48 hours after reperfusion, and then declined gradually. CRH mRNA expression levels in the temporal cortex, hippocampus and hypothalamus were enhanced markedly at 1 hour ischemia and were maintained until 96 hours after reperfusion. At the same time, adrenocorticotropic hormone level in plasma was relatively increased. In the peak stage of reperfusion injury, there was a significantly positive correlation (n=15, r=0.566, P<0.05) of the glutamate contents in the hypothalamus with the number of cells positive for CRH mRNA expression level in the hypothalamus.Conclusion It is probable that the CRH system in the central nervous system is mainly distributed in the limbic system, and glutamate might be one of the trigger factors to induce excessive stress response in the HPA axis.

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

    OpenAIRE

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

    2008-01-01

    Several immobilized enzyme-based electrochemical biosensors for glutamate detection have been developed over the last decade. In this review, we compare first and second generation sensors. Structures, working mechanisms, interference prevention, in vitro detection characteristics and in vivo performance are summarized here for those sensors that have successfully detected brain glutamate in vivo. In brief, first generation sensors have a simpler structure and are faster in glutamate detectio...

  15. [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.

  16. The effect of combined glutamate receptor blockade in the NTS on the hypoxic ventilatory response in awake rats differs from the effect of individual glutamate receptor blockade.

    Science.gov (United States)

    Pamenter, Matthew E; Nguyen, Jetson; Carr, John A; Powell, Frank L

    2014-08-01

    Ventilatory acclimatization to hypoxia (VAH) increases the hypoxic ventilatory response (HVR) and causes persistent hyperventilation when normoxia is restored, which is consistent with the occurrence of synaptic plasticity in acclimatized animals. Recently, we demonstrated that antagonism of individual glutamate receptor types (GluRs) within the nucleus tractus solitarii (NTS) modifies this plasticity and VAH (J. Physiol. 592(8):1839-1856); however, the effects of combined GluR antagonism remain unknown in awake rats. To evaluate this, we exposed rats to room air or chronic sustained hypobaric hypoxia (CSH, PiO2 = 70 Torr) for 7-9 days. On the experimental day, we microinjected artificial cerebrospinal fluid (ACSF: sham) and then a "cocktail" of the GluR antagonists MK-801 and DNQX into the NTS. The location of injection sites in the NTS was confirmed by glutamate injections on a day before the experiment and with histology following the experiment. Ventilation was measured in awake, unrestrained rats breathing normoxia or acute hypoxia (10% O2) in 15-min intervals using barometric pressure plethysmography. In control (CON) rats, acute hypoxia increased ventilation; NTS microinjections of GluR antagonists, but not ACSF, significantly decreased ventilation and breathing frequency in acute hypoxia but not normoxia (P NTS significantly decreased ventilation in normoxia and breathing frequency in hypoxia. A persistent HVR after combined GluR blockade in the NTS contrasts with the effect of individual GluR blockade and also with results in anesthetized rats. Our findings support the hypotheses that GluRs in the NTS contribute to, but cannot completely explain, VAH in awake rats.

  17. 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.

  18. Cystine/glutamate antiporter blockage induces myelin degeneration.

    Science.gov (United States)

    Soria, Federico N; Zabala, Alazne; Pampliega, Olatz; Palomino, Aitor; Miguelez, Cristina; Ugedo, Luisa; Sato, Hideyo; Matute, Carlos; Domercq, María

    2016-08-01

    The cystine/glutamate antiporter is a membrane transport system responsible for the uptake of extracellular cystine and release of intracellular glutamate. It is the major source of cystine in most cells, and a key regulator of extrasynaptic glutamate in the CNS. Because cystine is the limiting factor in the biosynthesis of glutathione, and glutamate is the most abundant neurotransmitter, the cystine/glutamate antiporter is a central player both in antioxidant defense and glutamatergic signaling, two events critical to brain function. However, distribution of cystine/glutamate antiporter in CNS has not been well characterized. Here, we analyzed expression of the catalytic subunit of the cystine/glutamate antiporter, xCT, by immunohistochemistry in histological sections of the forebrain and spinal cord. We detected labeling in neurons, oligodendrocytes, microglia, and oligodendrocyte precursor cells, but not in GFAP(+) astrocytes. In addition, we examined xCT expression and function by qPCR and cystine uptake in primary rat cultures of CNS, detecting higher levels of antiporter expression in neurons and oligodendrocytes. Chronic inhibition of cystine/glutamate antiporter caused high toxicity to cultured oligodendrocytes. In accordance, chronic blockage of cystine/glutamate antiporter as well as glutathione depletion caused myelin disruption in organotypic cerebellar slices. Finally, mice chronically treated with sulfasalazine, a cystine/glutamate antiporter inhibitor, showed a reduction in the levels of myelin and an increase in the myelinated fiber g-ratio. Together, these results reveal that cystine/glutamate antiporter is expressed in oligodendrocytes, where it is a key factor to the maintenance of cell homeostasis. GLIA 2016. GLIA 2016;64:1381-1395. PMID:27247047

  19. The hippocampus and appetitive Pavlovian conditioning: effects of excitotoxic hippocampal lesions on conditioned locomotor activity and autoshaping.

    Science.gov (United States)

    Ito, Rutsuko; Everitt, Barry J; Robbins, Trevor W

    2005-01-01

    The hippocampus (HPC) is known to be critically involved in the formation of associations between contextual/spatial stimuli and behaviorally significant events, playing a pivotal role in learning and memory. However, increasing evidence indicates that the HPC is also essential for more basic motivational processes. The amygdala, by contrast, is important for learning about the motivational significance of discrete cues. This study investigated the effects of excitotoxic lesions of the rat HPC and the basolateral amygdala (BLA) on the acquisition of a number of appetitive behaviors known to be dependent on the formation of Pavlovian associations between a reward (food) and discrete stimuli or contexts: (1) conditioned/anticipatory locomotor activity to food delivered in a specific context and (2) autoshaping, where rats learn to show conditioned discriminated approach to a discrete visual CS+. While BLA lesions had minimal effects on conditioned locomotor activity, hippocampal lesions facilitated the development of both conditioned activity to food and autoshaping behavior, suggesting that hippocampal lesions may have increased the incentive motivational properties of food and associated conditioned stimuli, consistent with the hypothesis that the HPC is involved in inhibitory processes in appetitive conditioning.

  20. Proteolytic fragments of laminin promote excitotoxic neurodegeneration by up-regulation of the KA1 subunit of the kainate receptor.

    Science.gov (United States)

    Chen, Zu-Lin; Yu, Huaxu; Yu, Wei-Ming; Pawlak, Robert; Strickland, Sidney

    2008-12-29

    Degradation of the extracellular matrix (ECM) protein laminin contributes to excitotoxic cell death in the hippocampus, but the mechanism of this effect is unknown. To study this process, we disrupted laminin gamma1 (lamgamma1) expression in the hippocampus. Lamgamma1 knockout (KO) and control mice had similar basal expression of kainate (KA) receptors, but the lamgamma1 KO mice were resistant to KA-induced neuronal death. After KA injection, KA1 subunit levels increased in control mice but were unchanged in lamgamma1 KO mice. KA1 levels in tissue plasminogen activator (tPA)-KO mice were also unchanged after KA, indicating that both tPA and laminin were necessary for KA1 up-regulation after KA injection. Infusion of plasmin-digested laminin-1 into the hippocampus of lamgamma1 or tPA KO mice restored KA1 up-regulation and KA-induced neuronal degeneration. Interfering with KA1 function with a specific anti-KA1 antibody protected against KA-induced neuronal death both in vitro and in vivo. These results demonstrate a novel pathway for neurodegeneration involving proteolysis of the ECM and KA1 KA receptor subunit up-regulation.

  1. Acute Bronchitis

    Science.gov (United States)

    ... of bronchitis: acute and chronic. Most cases of acute bronchitis get better within several days. But your cough ... that cause colds and the flu often cause acute bronchitis. These viruses spread through the air when people ...

  2. 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.

  3. 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

  4. 78 FR 76321 - Monosodium Glutamate From China and Indonesia

    Science.gov (United States)

    2013-12-17

    ... Register of September 20, 2013 (78 FR 57881). The conference was held in Washington, DC, on October 23... 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...

  5. 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.

  6. Chronic prenatal ethanol exposure increases glucocorticoid-induced glutamate release in the hippocampus of the near-term foetal guinea pig.

    Science.gov (United States)

    Iqbal, U; Brien, J F; Kapoor, A; Matthews, S G; Reynolds, J N

    2006-11-01

    Exposure to high cortisol concentration can injure the developing brain, possibly via an excitotoxic mechanism involving glutamate (Glu). The present study tested the hypothesis that chronic prenatal ethanol exposure (CPEE) activates the foetal hypothalamic-pituitary-adrenal axis to produce high cortisol exposure in the foetal compartment and alters sensitivity to glucocorticoid-induced Glu release in the foetal hippocampus. Pregnant guinea pigs received daily oral administration of ethanol (4 g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding from gestational day (GD) 2 until GD 63 (term, approximately GD 68) at which time they were euthanised, 1 h after their final treatment. Adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined in foetal plasma. Basal and electrically stimulated Glu and gamma-aminobutyric acid (GABA) efflux in the presence or absence of dexamethasone (DEX), a selective glucocorticoid-receptor agonist, were determined ex vivo in foetal hippocampal slices. Glucocorticoid receptor (GR), mineralocorticoid receptor (MR) and N-methyl-D-aspartate (NMDA) receptor NR1 subunit mRNA expression were determined in situ in the hippocampus and dentate gyrus. In the near-term foetus, CPEE increased foetal plasma ACTH and cortisol concentrations. Electrically stimulated glutamate, but not GABA, release was increased in CPEE foetal hippocampal slices. Low DEX concentration (0.3 microM) decreased stimulated glutamate, but not GABA, release in both CPEE and control foetal hippocampal slices. High DEX concentration (3.0 microM) increased basal release of Glu, but not GABA, in CPEE foetal hippocampal slices. GR, but not MR, mRNA expression was elevated in the hippocampus and dentate gyrus, whereas NR1 mRNA expression was increased in the CA1 and CA3 fields of the foetal hippocampus. These data demonstrate that CPEE increases high glucocorticoid concentration-induced Glu release in the foetal hippocampus, presumably as a

  7. Role of glutamate transporters in neurotoxicity induced by rotenone%谷氨酸转运体在鱼藤酮神经毒性中的作用

    Institute of Scientific and Technical Information of China (English)

    刘辉; 尹芳秋; 燕颖军; 许崇亮; 贾庆军; 徐忠华

    2011-01-01

    Objective To explore the role of glutamate transporters in the neurotoxicity induced by rotenone. Methods Astrocytes isolated from newborn rats, were cocultured with PC 12 cells, then were divided into 6 groups: control group, rotenone treated group, DHK pretreated group ( I and H ) , and PDC pretreated group ( I and II ). Extracellular glutamate concentrations were detected by high performance liquid chromatography (HPLC) , and the uptake ability of glutamate was determined with isotope labeling method. Results It was showed that the glutamate uptake ability in astrocytes pretreated with PDC was significantly decreased compared with rotenone treated group, while those in astrocytes pretreated with DHK failed to show any significant change. Conclusion GLAST rather than GLT-1 may play a crucial role in excitotoxicity induced by rotenone.%目的 观察谷氨酸转运体在鱼藤酮神经毒性中的作用.方法 建立星形胶质细胞与大鼠嗜铬细胞瘤(PC12)细胞共培养鱼藤酮染毒模型,并用谷氨酸转运体-1(GLT-1)和谷氨酸/天冬氨酸转运体(GLAST)特异性抑制剂二氢卡因酸盐(DHK)、L-反式吡咯烷-2,4-二羧酸(PDC)预处理.高效液相色谱(HPLC)荧光法检测星形胶质细胞胞外谷氨酸(Glu)浓度,同位素标记法检测Glu摄取能力.结果 DHK预处理组星形胶质细胞Glu摄取能力与单纯鱼藤酮中毒组比较差异无统计学意义,而PDC预处理组星形胶质细胞Glu摄取能力明显下降,胞外Glu浓度升高,与单纯鱼藤酮中毒组比较具有显著的统计学意义.结论 谷氨酸转运体GLAST可能在鱼藤酮诱导的兴奋性损伤机制中起主要作用.

  8. Autoimmune epilepsy: distinct subpopulations of epilepsy patients harbor serum autoantibodies to either glutamate/AMPA receptor GluR3, glutamate/NMDA receptor subunit NR2A or double-stranded DNA.

    Science.gov (United States)

    Ganor, Yonatan; Goldberg-Stern, Hadassa; Lerman-Sagie, Tally; Teichberg, Vivian I; Levite, Mia

    2005-06-01

    We studied 82 patients with different types of epilepsy and 49 neurologically intact non-epileptic controls, and identified three different subpopulations of epilepsy patients bearing significantly elevated levels of autoantibodies to either GluR3B-peptide of glutamate/AMPA receptor subtype 3 (17/82; 21% of patients), or to a peptide of NR2A subunit of glutamate/NMDA receptors (15/82; 18%), or to double-stranded (ds) DNA, the hallmark of systemic lupus erythematosus (13/80; 16%). Most patients had only one antibody type, arguing against cross-reactivity. Nearly all anti-dsDNA Ab-positive patients did not harbor anti-nuclear autoantibodies. Most patients had no history of brain damage, febrile convulsions, early onset epilepsy, acute epilepsy or intractable seizures. We suggest to measure the 'autoimmune-fingerprints' of epilepsy patients for diagnostic and therapeutic purposes. PMID:15978777

  9. 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.

  10. Role of spinal cord glutamate transporter during normal sensory transmission and pathological pain states

    Directory of Open Access Journals (Sweden)

    Stephens Robert L

    2005-10-01

    Full Text Available Abstract Glutamate is a neurotransmitter critical for spinal excitatory synaptic transmission and for generation and maintenance of spinal states of pain hypersensitivity via activation of glutamate receptors. Understanding the regulation of synaptically and non-synaptically released glutamate associated with pathological pain is important in exploring novel molecular mechanisms and developing therapeutic strategies of pathological pain. The glutamate transporter system is the primary mechanism for the inactivation of synaptically released glutamate and the maintenance of glutamate homeostasis. Recent studies demonstrated that spinal glutamate transporter inhibition relieved pathological pain, suggesting that the spinal glutamate transporter might serve as a therapeutic target for treatment of pathological pain. However, the exact function of glutamate transporter in pathological pain is not completely understood. This report will review the evidence for the role of the spinal glutamate transporter during normal sensory transmission and pathological pain conditions and discuss potential mechanisms by which spinal glutamate transporter is involved in pathological pain.

  11. 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

  12. 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.

  13. 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.

  14. Biosynthesis of endocannabinoids and their modes of action in neurodegenerative diseases

    DEFF Research Database (Denmark)

    van der Stelt, M.; Veldink, G.A.; Vliegenthart, J.F.G.;

    2003-01-01

    demonstrated that the endocannabinoid system can protect neurons against glutamate excitotoxicity and acute neuronal damage in both in vitro and in vivo models. In this paper we review the data concerning the involvement of the endocannabinoid system in neurodegenerative diseases in which neuronal cell death...

  15. Vaccination for protection of retinal ganglion cells against death from glutamate cytotoxicity and ocular hypertension: Implications for glaucoma

    Science.gov (United States)

    Schori, Hadas; Kipnis, Jonathan; Yoles, Eti; Woldemussie, Elizabeth; Ruiz, Guadalupe; Wheeler, Larry A.; Schwartz, Michal

    2001-03-01

    Our group recently demonstrated that autoimmune T cells directed against central nervous system-associated myelin antigens protect neurons from secondary degeneration. We further showed that the synthetic peptide copolymer 1 (Cop-1), known to suppress experimental autoimmune encephalomyelitis, can be safely substituted for the natural myelin antigen in both passive and active immunization for neuroprotection of the injured optic nerve. Here we attempted to determine whether similar immunizations are protective from retinal ganglion cell loss resulting from a direct biochemical insult caused, for example, by glutamate (a major mediator of degeneration in acute and chronic optic nerve insults) and in a rat model of ocular hypertension. Passive immunization with T cells reactive to myelin basic protein or active immunization with myelin oligodendrocyte glycoprotein-derived peptide, although neuroprotective after optic nerve injury, was ineffective against glutamate toxicity in mice and rats. In contrast, the number of surviving retinal ganglion cells per square millimeter in glutamate-injected retinas was significantly larger in mice immunized 10 days previously with Cop-1 emulsified in complete Freund's adjuvant than in mice injected with PBS in the same adjuvant (2,133 ± 270 and 1,329 ± 121, respectively, mean ± SEM; P myelin. The use of Cop-1 apparently circumvents this antigen specificity barrier. In the rat ocular hypertension model, which simulates glaucoma, immunization with Cop-1 significantly reduced the retinal ganglion cell loss from 27.8%±6.8% to 4.3%±1.6%, without affecting the intraocular pressure. This study may point the way to a therapy for glaucoma, a neurodegenerative disease of the optic nerve often associated with increased intraocular pressure, as well as for acute and chronic degenerative disorders in which glutamate is a prominent participant.

  16. Opioid-glutamate interactions in rat locus coeruleus neurons.

    Science.gov (United States)

    Oleskevich, S; Clements, J D; Williams, J T

    1993-09-01

    1. The effect of mu-opioids on the glutamate response was investigated in rat locus coeruleus (LC) neurons by intracellular recording in the brain slice preparation. Glutamate responses were evoked by bath application of selective glutamate agonists, glutamate iontophoresis, and stimulation of excitatory afferents. 2. The mu-opioid agonist D-Ala2-MePhe4-Gly-ol5-enkephalin (DAMGO; 1 microM) potentiated the response to bath application of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid by 91 and 142%, respectively, in slices cut in the horizontal plane. The mechanism of action of this effect was investigated under conditions that limited the DAMGO-induced hyperpolarization and improved the space clamp of the neuron through 1) addition of barium, 2) increase in extracellular potassium concentration, 3) sectioning of the LC in the coronal plane, and 4) addition of carbenoxolone. Each experimental manipulation decreased the DAMGO outward current and reduced the mu-opioid potentiation of the glutamate response. The results suggest that the mu-opioid-mediated potentiation of the glutamate response is dependent on membrane hyperpolarization. 3. Neither forskolin nor the phorbol ester 4b-phorbol 12,13-dibutyrate (PDBu) altered the glutamate-mediated inward currents. The potentiation of the glutamate response by DAMGO was not affected by PDBu. 4. The mu-opioids DAMGO and [met]5enkephalin (10 microM) did not significantly affect the NMDA receptor-mediated depolarization (mean 14%) evoked by local application of glutamate but inhibited the NMDA receptor-mediated synaptic potential (mean 25%).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7693886

  17. Correlation between afferent rearrangements and behavioral deficits after local excitotoxic insult in the mammalian vestibule: a rat model of vertigo symptoms

    Science.gov (United States)

    Travo, Cécile; Saleur, Aurélie; Broussy, Audrey; Brugeaud, Aurore; Chabbert, Christian

    2016-01-01

    ABSTRACT Damage to inner ear afferent terminals is believed to result in many auditory and vestibular dysfunctions. The sequence of afferent injuries and repair, as well as their correlation with vertigo symptoms, remains poorly documented. In particular, information on the changes that take place at the primary vestibular endings during the first hours following a selective insult is lacking. In the present study, we combined histological analysis with behavioral assessments of vestibular function in a rat model of unilateral vestibular excitotoxic insult. Excitotoxicity resulted in an immediate but transient alteration of the balance function that was resolved within a week. Concomitantly, vestibular primary afferents underwent a sequence of structural changes followed by spontaneous repair. Within the first two hours after the insult, a first phase of pronounced vestibular dysfunction coincided with extensive swelling of afferent terminals. In the next 24 h, a second phase of significant but incomplete reduction of the vestibular dysfunction was accompanied by a resorption of swollen terminals and fiber retraction. Eventually, within 1 week, a third phase of complete balance restoration occurred. The slow and progressive withdrawal of the balance dysfunction correlated with full reconstitution of nerve terminals. Competitive re-innervation by afferent and efferent terminals that mimicked developmental synaptogenesis resulted in full re-afferentation of the sensory epithelia. By deciphering the sequence of structural alterations that occur in the vestibule during selective excitotoxic impairment, this study offers new understanding of how a vestibular insult develops in the vestibule and how it governs the heterogeneity of vertigo symptoms. PMID:27483344

  18. Spermine modulation of the glutamateNMDA receptors is differentially responsive to conantokins in normal and alzheimer disease human cortex

    International Nuclear Information System (INIS)

    Full text: The pharmacological characteristics of human N-methyl-D-aspartate (NMDA) receptors were examined in 12 control and 6 pathologically confirmed Alzheimer disease (AD) cases in six different brain areas, by studying their responses to MK-801, glutamate, spermine, and the NMDA receptor antagonists Ala(7)-conantokinG and Lys(7)-conantokinG. [3H]MK801 binding assays performed by standard protocols on well-washed synoptic plasma membranes showed little variation in kD in all six brain areas, including comparisons between control and matched AD cases. b MAX values showed regional differences within control and AD cases, but there was no significant difference between groups in any of the brain regions. Maximal glutamate-enhanced [3H]MK801 binding did not vary much between the brain regions or between control and AD cases, whereas maximal spermine-enhanced [3H]MK-801 binding differed significantly between certain brain regions and between control and AD cases. In absolute terms in the control cases, the activation values were much lower in the spared regions, occipital and motor cortex, than in other areas; further, areas which are susceptible to damage showed reduced spermine activation in AD cases. These regional differences in the efficacy of spermine activation might be the result of local variations in the subunit composition of the NMDA receptor. Ala(7)-conantokinG and Lys(7)-conantokinG showed slight differences in potency, with the Ala(7) compound as the more potent. Both peptides produced 100% inhibition of spermine-enhanced [3H]MK-801 binding in all brain areas, ana both gave lower IC50 values in AD cases than in control cases. The significant differences in the inhibition of spermine-enhanced [3H]MK-801 binding by the peptides between control and AD cases suggest that AD cases have a particular receptor subunit composition that is responsive to polyamines and which might make them more susceptible to excitotoxic damage. The spermine site may contribute

  19. 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.

  20. Acute Immobilization Stress Modulate GABA Release from Rat Olfactory Bulb: Involvement of Endocannabinoids—Cannabinoids and Acute Stress Modulate GABA Release

    OpenAIRE

    Alejandra Delgado; Erica H. Jaffé

    2011-01-01

    We studied the effects of cannabinoids and acute immobilization stress on the regulation of GABA release in the olfactory bulb. Glutamate-stimulated 3H-GABA release was measured in superfused slices. We report that cannabinoids as WIN55, 212-2, methanandamide, and 2-arachidonoylglycerol were able to inhibit glutamate- and KCl-stimulated 3H-GABA release. This effect was blocked by the CB1 antagonist AM281. On the other hand, acute stress was able per se to increase endocannabinoid activity. Th...

  1. Efficient synthesis of novel glutamate homologues and investigation of their affinity and selectivity profile at ionotropic glutamate receptors.

    Science.gov (United States)

    Pinto, Andrea; Tamborini, Lucia; Mastronardi, Federica; Ettari, Roberta; Romano, Diego; Nielsen, Birgitte; De Micheli, Carlo; Conti, Paola

    2014-04-15

    A convenient synthesis of four new enantiomerically pure acidic amino acids is reported and their affinity at ionotropic glutamate receptors was determined. The new compounds are higher homologues of glutamic acid in which the molecular complexity has been increased by introducing an aromatic/heteroaromatic ring, that is a phenyl or a thiophene ring, that could give additional electronic interactions with the receptors. The results of the present investigation indicate that the insertion of an aromatic/heteroaromatic ring into the amino acid skeleton of glutamate higher homologues is well tolerated and this modification could be exploited to generate a new class of NMDA antagonists. PMID:24630559

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  3. Acute Pancreatitis and Pregnancy

    Science.gov (United States)

    ... Acute Pancreatitis > Acute Pancreatitis and Pregnancy test Acute Pancreatitis and Pregnancy Timothy Gardner, MD Acute pancreatitis is ... of acute pancreatitis in pregnancy. Reasons for Acute Pancreatitis and Pregnancy While acute pancreatitis is responsible for ...

  4. Transport mechanism of a glutamate transporter homologue GltPh

    Science.gov (United States)

    Ji, Yurui; Postis, Vincent L.G.; Wang, Yingying; Bartlam, Mark; Goldman, Adrian

    2016-01-01

    Glutamate transporters are responsible for uptake of the neurotransmitter glutamate in mammalian central nervous systems. Their archaeal homologue GltPh, an aspartate transporter isolated from Pyrococcus horikoshii, has been the focus of extensive studies through crystallography, MD simulations and single-molecule FRET (smFRET). Here, we summarize the recent research progress on GltPh, in the hope of gaining some insights into the transport mechanism of this aspartate transporter. PMID:27284058

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

    OpenAIRE

    Parpura, Vladimir; VERKHRATSKY, ALEXEI

    2012-01-01

    Astroglia is a main type of brain neuroglia, which includes many cell sub-types that differ in their morphology and physiological properties and yet are united by the main function, which is the maintenance of brain homeostasis. Astrocytes employ a variety of mechanisms for communicating with neuronal networks. The communication mediated by neurotransmitter glutamate has received a particular attention. Glutamate is de novo synthesized exclusively in astrocytes; astroglia-derived glutamine is...

  6. The glutamate post-synaptic density in schizophrenia

    OpenAIRE

    Matas, Emmanuel

    2012-01-01

    Non-competitive antagonists of the glutamate N-methyl-D-aspartate receptor (NMDAR) induce a broad range of schizophrenia-like symptoms in humans. Consequently hypothesis has emerged suggesting that glutamate or NMDAR hypofunction may occur in schizophrenia. The NMDAR is localised at dendritic spines of neurons and is embedded in a multi-protein complex called the post-synaptic density (PSD). The biochemical composition of the postsynaptic membrane and the structure of dendritic spines are con...

  7. Dopamine denervation of the prefrontal cortex increases expression of the astrocytic glutamate transporter GLT-1

    OpenAIRE

    Vollbrecht, Peter J.; Simmler, Linda D.; Blakely, Randy D.; Deutch, Ariel Y.

    2014-01-01

    Both dopamine and glutamate are critically involved in cognitive processes such as working memory. Astrocytes, which express dopamine receptors, are essential elements in the termination of glutamatergic signaling: the astrocytic glutamate transporter GLT-1 is responsible for >90% of cortical glutamate uptake. The effect of dopamine depletion on glutamate transporters in the prefrontal cortex (PFC) is unknown. In an effort to determine if astrocytes are a locus of cortical dopamine-glutamate ...

  8. Designing Novel Nanoformulations Targeting Glutamate Transporter Excitatory Amino Acid Transporter 2: Implications in Treating Drug Addiction

    OpenAIRE

    Rao, PSS; Yallapu, Murali M.; Sari, Youssef; Fisher, Paul B.; Kumar, Santosh

    2015-01-01

    Chronic drug abuse is associated with elevated extracellular glutamate concentration in the brain reward regions. Deficit of glutamate clearance has been identified as a contributing factor that leads to enhanced glutamate concentration following extended drug abuse. Importantly, normalization of glutamate level through induction of glutamate transporter 1 (GLT1)/ excitatory amino acid transporter 2 (EAAT2) expression has been described in several in vivo studies. GLT1 upregulators including ...

  9. Therapeutic hypothermia for acute brain injuries.

    Science.gov (United States)

    Andresen, Max; Gazmuri, Jose Tomás; Marín, Arnaldo; Regueira, Tomas; Rovegno, Maximiliano

    2015-06-05

    Therapeutic hypothermia, recently termed target temperature management (TTM), is the cornerstone of neuroprotective strategy. Dating to the pioneer works of Fay, nearly 75 years of basic and clinical evidence support its therapeutic value. Although hypothermia decreases the metabolic rate to restore the supply and demand of O₂, it has other tissue-specific effects, such as decreasing excitotoxicity, limiting inflammation, preventing ATP depletion, reducing free radical production and also intracellular calcium overload to avoid apoptosis. Currently, mild hypothermia (33°C) has become a standard in post-resuscitative care and perinatal asphyxia. However, evidence indicates that hypothermia could be useful in neurologic injuries, such as stroke, subarachnoid hemorrhage and traumatic brain injury. In this review, we discuss the basic and clinical evidence supporting the use of TTM in critical care for acute brain injury that extends beyond care after cardiac arrest, such as for ischemic and hemorrhagic strokes, subarachnoid hemorrhage, and traumatic brain injury. We review the historical perspectives of TTM, provide an overview of the techniques and protocols and the pathophysiologic consequences of hypothermia. In addition, we include our experience of managing patients with acute brain injuries treated using endovascular hypothermia.

  10. Glutamate Delta-1 Receptor Regulates Metabotropic Glutamate Receptor 5 Signaling in the Hippocampus.

    Science.gov (United States)

    Suryavanshi, Pratyush S; Gupta, Subhash C; Yadav, Roopali; Kesherwani, Varun; Liu, Jinxu; Dravid, Shashank M

    2016-08-01

    The delta family of ionotropic glutamate receptors consists of glutamate delta-1 (GluD1) and glutamate delta-2 receptors. We have previously shown that GluD1 knockout mice exhibit features of developmental delay, including impaired spine pruning and switch in the N-methyl-D-aspartate receptor subunit, which are relevant to autism and other neurodevelopmental disorders. Here, we identified a novel role of GluD1 in regulating metabotropic glutamate receptor 5 (mGlu5) signaling in the hippocampus. Immunohistochemical analysis demonstrated colocalization of mGlu5 with GluD1 punctas in the hippocampus. Additionally, GluD1 protein coimmunoprecipitated with mGlu5 in the hippocampal membrane fraction, as well as when overexpressed in human embryonic kidney 293 cells, demonstrating that GluD1 and mGlu5 may cooperate in a signaling complex. The interaction of mGlu5 with scaffold protein effector Homer, which regulates mechanistic target of rapamycin (mTOR) signaling, was abnormal both under basal conditions and in response to mGlu1/5 agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) in GluD1 knockout mice. The basal levels of phosphorylated mTOR and protein kinase B, the signaling proteins downstream of mGlu5 activation, were higher in GluD1 knockout mice, and no further increase was induced by DHPG. We also observed higher basal protein translation and an absence of DHPG-induced increase in GluD1 knockout mice. In accordance with a role of mGlu5-mediated mTOR signaling in synaptic plasticity, DHPG-induced internalization of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunits was impaired in the GluD1 knockout mice. These results demonstrate that GluD1 interacts with mGlu5, and loss of GluD1 impairs normal mGlu5 signaling potentially by dysregulating coupling to its effector. These studies identify a novel role of the enigmatic GluD1 subunit in hippocampal function. PMID:27231330

  11. [Glutamate Metabotropic Receptors: Structure, Localisation, Functions].

    Science.gov (United States)

    Perfilova, V N; Tyurenkov, I N

    2016-01-01

    The data on the structure, location and functions of the metabotropic glutamate receptor is shown. The family consists of 8 mGluRs subtypes and is divided into three groups: I group--mGluRs1/mGluRs5, II group--mGluRs2/mGluRs3, III group--mGluRs4/mGluRs6/mGluRs7/mGluRs8. They are associated with G-protein; signaling in the cells is carried out by IP3 or adenylate cyclase signaling pathways, in the result of which, mGluRs modify glial and neuronal excitability. Receptors are localized in the CNS and periphery in non-neuronal tissues: bone, heart, kidney, pancreas pod and platelets, the gastrointestinal tract, immune system. Their participation in the mechanisms of neurodegenerative diseases, mental and cognitive disorders, autoimmune processes, etc. is displayed. Agonists, antagonists, allosteric modulators of mGluRs are considered as potential medicines for treatment of mental diseases, including depression, fragile X syndrome, anxiety, obsessive-compulsive disorders, Parkinson's disease, etc. PMID:27530046

  12. 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 cortical afferent pre-synaptic terminals have been shown to underlie both cortical sensory adaptation and habituation of odor-evoked reflexes. The present experiment examined whether blockade of sensory cortical adaptation through bilateral infusion of the group III metabotropic glutamate receptor antagonist cyclopropyl-4-phosphonophenylglycine (CPPG) into the anterior piriform cortex could reduce habituation of a more complex odor-driven behavior such as investigation of a scented object or a conspecific. The results demonstrate that time spent investigating a scented jar, or a conspecific, decreases over the course of a continuous 10 minute trial. Acute infusion of CPPG bilaterally into the anterior piriform cortex significantly enhanced the time spent investigating the scented jar compared to investigation time in control rats, without affecting overall behavioral activity levels. Infusions into the brain outside of the piriform cortex were without effect. CPPG infusion into the piriform cortex also produced an enhancement of time spent investigating a conspecific, although this effect was not significant. PMID:16322361

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    such as Alzheimer's, Parkinson's and Huntington's diseases, as well as ischemic stroke and amyotrophic lateral sclerosis. Accurate measurement of glutamate levels in vitro and in vivo for a better understanding of the physiological and pathological role of glutamate in neurotransmission has remained challenging...... is currently the most common method for in vivo glutamate sampling. However, the recent development and improvement of enzyme-based amperometric glutamate biosensors makes them a promising alternative to microdialysis for in vivo applications, as well as valuable devices for in vitro applications in basic......-materials such as nanoparticles, nanotubes and nanowires, which have great potential for sensing applications due to their large surface-to-volume ratio and novel physical properties....

  14. Bronchitis - acute

    Science.gov (United States)

    ... sharing features on this page, please enable JavaScript. Acute bronchitis is swelling and inflammation in the main passages ... present only for a short time. Causes When acute bronchitis occurs, it almost always comes after having a ...

  15. Acute pancreatitis

    OpenAIRE

    Bo-Guang Fan; Åke Andrén-Sandberg

    2010-01-01

    Background : Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims : The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods : We reviewed the English-language literature (Medline) addressing pancreatitis. Results : Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingest...

  16. Acute pancreatitis

    OpenAIRE

    Bo-Guang Fan; Åke Andrén-Sandberg

    2010-01-01

    Background: Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims: The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods: We reviewed the English-language literature (Medline) addressing pancreatitis. Results: Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingestion....

  17. Interaction between neuropeptide Y (NPY) and brain-derived neurotrophic factor in NPY-mediated neuroprotection against excitotoxicity

    DEFF Research Database (Denmark)

    Xapelli, S; Bernardino, L; Ferreira, R;

    2008-01-01

    The neuroprotective effect of neuropeptide Y (NPY) receptor activation was investigated in organotypic mouse hippocampal slice cultures exposed to the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Exposure of 2-week-old slice cultures, derived from 7......) receptor agonist [NPY(13-36), 300 nm]. This effect was sensitive to the presence of the selective Y(2) receptor antagonist (BIIE0246, 1 microm), but was not affected by addition of TrkB-Fc or by a neutralizing antibody against brain-derived neurotrophic factor (BDNF). Moreover, addition of a Y(1) receptor...... antagonist (BIBP3226, 1 microm) or a NPY-neutralizing antibody helped to disclose a neuroprotective role of endogenous NPY in CA1 region. Cultures exposed to 8 microm AMPA for 24 h, displayed, as measured by an enzyme-linked immunosorbent assay, a significant increase in BDNF. In such cultures...

  18. 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

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

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

    Directory of Open Access Journals (Sweden)

    Miaomiao Wu

    Full Text Available 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 (P<0.05 induced oxidative stress in piglets, while this stress was remarkably reduced with glutamic 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.

  20. Acute pancreatitis

    Directory of Open Access Journals (Sweden)

    Bo-Guang Fan

    2010-01-01

    Full Text Available Background : Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims : The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods : We reviewed the English-language literature (Medline addressing pancreatitis. Results : Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingestion. There are a number of important issues regarding clinical highlights in the classification, treatment and prognosis of acute pancreatitis, and treatment options for complications of acute pancreatitis including pancreatic pseudocysts. Conclusions : Multidisciplinary approach should be used for the management of the patient with acute pancreatitis.

  1. Acute pancreatitis

    Directory of Open Access Journals (Sweden)

    Bo-Guang Fan

    2010-05-01

    Full Text Available Background: Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims: The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods: We reviewed the English-language literature (Medline addressing pancreatitis. Results: Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingestion. There are a number of important issues regarding clinical highlights in the classification, treatment and prognosis of acute pancreatitis, and treatment options for complications of acute pancreatitis including pancreatic pseudocysts. Conclusions: Multidisciplinary approach should be used for the management of the patient with acute pancreatitis.

  2. Metabotropic glutamate receptors depress glutamate-mediated synaptic input to rat midbrain dopamine neurones in vitro.

    Science.gov (United States)

    Wigmore, M A; Lacey, M G

    1998-02-01

    1. Glutamate (AMPA receptor-mediated) excitatory postsynaptic potentials (e.p.s.ps.), evoked by electrical stimulation rostral to the recording site, were examined by intracellular microelectrode recording from dopamine neurones in parasagittal slices of rat ventral midbrain. 2. The e.p.s.p. was depressed by the group III metabotropic glutamate (mGlu) receptor agonist L-2-amino-4-phosphonobutyric acid (L-AP4; 0.01-30 microM) by up to 60% with an EC50 of 0.82 microM. The depression induced by L-AP4 (3 microM) was reversed by the group III preferring mGlu receptor antagonist, alpha-methyl-4-phosphonophenylglycine (MPPG; 250 microM). 3. The group I and II mGlu agonist, 1S,3R-aminocyclopentanedicarboxylic acid (ACPD; 3-30 microM) also depressed the e.p.s.p. in a concentration-dependent manner. The effect of ACPD (10 microM) was reversed by (+)-alpha-methyl-4-carboxyphenylglycine (MCPG; 1 mM; 4 cells). This effect of ACPD was also partially antagonized (by 50.3+/-15.7%, 4 cells) by MPPG (250 microM). 4. The selective agonist at group I mGlu receptors, dihydroxyphenylglycine (DHPG; 100 microM), decreased e.p.s.p. amplitude by 27.1+/-8.2% (7 cells), as did the group II mGlu receptor-selective agonist (1S,1R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV; 1 microM) by 26.7+/-4.3% (5 cells). 5. DHPG (10-100 microM) caused a depolarization of the recorded cell, as did ACPD (3-30 microM), whereas no such postsynaptic effect of either L-AP4 or DCG-IV was observed. 6. These results provide evidence for the presence of presynaptic inhibitory metabotropic glutamate autoreceptors from the mGlu receptor groups II and III on descending glutamatergic inputs to midbrain dopamine neurones. Group I mGlu receptors mediate a postsynaptic depolarization, and can also depress glutamatergic transmission, but may not necessarily be localized presynaptically. These sites represent novel drug targets for treatment of schizophrenia and movement disorders of basal ganglia origin. PMID

  3. Glutamate and Dopamine Transmission from Midbrain Dopamine Neurons Share Similar Release Properties But Are Differentially Affected by Cocaine

    Science.gov (United States)

    Adrover, Martín F.; Shin, Jung Hoon

    2014-01-01

    Synaptic transmission between ventral tegmental area and nucleus accumbens (NAc) is critically involved in reward-motivated behaviors and thought to be altered in addiction. In addition to dopamine (DA), glutamate is packaged and released by a subset of mesolimbic DA neurons, eliciting EPSCs onto medium spiny neurons in NAc. Little is known about the properties and modulation of glutamate release from DA midbrain terminals and the effect of cocaine. Using an optogenetic approach to selectively activate midbrain DA fibers, we compared the properties and modulation of DA transients and EPSCs measured using fast-scan cyclic voltammetry and whole-cell recordings in mouse brain slices. DA transients and EPSCs were inhibited by DA receptor D2R agonist and showed a marked paired-pulse depression that required 2 min for full recovery. Cocaine depressed EPSCs amplitude by 50% but enhanced the overall DA transmission from midbrain DA neurons. AMPA and NMDA receptor-mediated EPSCs were equally inhibited by cocaine, suggesting a presynaptic mechanism of action. Pharmacological blockage and genetic deletion of D2R in DA neurons prevented the cocaine-induced inhibition of EPSCs and caused a larger increase in DA transient peak, confirming the involvement of presynaptic D2R. These findings demonstrate that acute cocaine inhibits DA and glutamate release from midbrain DA neurons via presynaptic D2R but has differential overall effects on their transmissions in the NAc. We postulate that cocaine, by blocking DA reuptake, prolongs DA transients and facilitates the feedback inhibition of DA and glutamate release from these terminals. PMID:24573277

  4. 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

  5. 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.

  6. Glutamate receptor homologs in plants: Functions and Evolutionary Origins

    Directory of Open Access Journals (Sweden)

    Michelle Beth Price

    2012-10-01

    Full Text Available The plant glutamate receptors (GLRs are homologs of mammalian ionotropic glutamate receptors (iGluRs which were discovered more than 10 years ago, and are hypothesized to be potential amino acid sensors in plants. Although initial progress on this gene family has been hampered by gene redundancy and technical issues such as gene toxicity; genetic, pharmacological, and electrophysiological approaches are starting to uncover the functions of this protein family. In parallel, there has been tremendous progress in elucidating the structure of animal glutamate receptors (iGluRs, which in turn will help understanding of the molecular mechanisms of plant GLR functions.In this review, we will summarize recent progress on the plant GLRs. Emerging evidence implicates plant GLRs in various biological processes in and beyond N sensing, and implies that there is some overlap in the signaling mechanisms of amino acids between plants and animals. Phylogenteic analysis using glutamate receptors from metazoans, plants and bacteria showed that the plant GLRs are no more closely related to metazoan iGluRs as they are to bacterial glutamate receptors, indicating the separation of plant, eukaryotic, and bacterial GLRs might have happened as early on as the last universal common ancestor. Structural similarities and differences with animal iGluRs, and the implication thereof, are also discussed.

  7. 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.

  8. 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.

  9. 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

  10. [Features of glutamate dehydrogenase in fetal and adult rumen tissue].

    Science.gov (United States)

    Kalachniuk, H I; Fomenko, I S; Kalachniuk, L H; Kavai, Sh; Marounek, M; Savka, O H

    2001-01-01

    Glutamate dehydrogenase (GDH) from rumen mucosa of cow fetus, liver and two forms from mucosa (bacterial and tissue) of the adult animal were partly purified and characterized. The activity of the bacterial glutamate dehydrogenase was shown to depend on qualities of a biomass of microbes, adhered on surface of rumen mucosa. All enzymes from tissues (GDHTRF, TRC, TLC), revealed the hypersensibility to increase in the concentration medium of Zn2+, guanosine triphosphate (GTP), acting here in a role of negative modulators, and also adenosine monophosphate (AMP) and leucine, which acted as activators. However, in the same concentrations these effectors do not influence the activity of the bacterial glutamate dehydrogenase. And if all tissues enzymes are highly specific to coenzyme NADH, the bacterial ones almost in 3 times is more active at NADPH use. PMID:11642036

  11. Determination of Nephrotoxicity and Hepatoxicity of Monosodium Glutamate (MSG Consumption

    Directory of Open Access Journals (Sweden)

    H.M. Inuwa

    2011-08-01

    Full Text Available Investigations were conducted to determine the Nephrotoxicity and Hepatoxicity of Monosodium Glutamata (MSG. Graded doses of monosodium glutamate were administered orally to Adult Wister rats weighing between (160.7-238.6 g for 28 days. Liver and Kidney function tests were carried out on the blood serum. Monosodium glutamate elicited an increase in body weight in an ascending fashion from group B to group D though not statistically significant (p>0.05 Biochemical parameters (Electrolytes, Urea, Creatinine, RBC, Cholesterol and Enzymes were not seriously affected though there were increases in the concentration or levels of same of them. This shows that monosodium glutamate has hepatoxicity and nephrotoxicity tendencies especially when consumed at higher concentrations.

  12. 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. PMID:27266631

  13. 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.

  14. 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.

  15. Transglutaminase is a therapeutic target for oxidative stress, excitotoxicity and stroke: a new epigenetic kid on the CNS block.

    Science.gov (United States)

    Basso, Manuela; Ratan, Rajiv R

    2013-06-01

    Transglutaminases (TGs) are multifunctional, calcium-dependent enzymes that have been recently implicated in stroke pathophysiology. Classically, these enzymes are thought to participate in cell injury and death in chronic neurodegenerative conditions via their ability to catalyze covalent, nondegradable crosslinks between proteins or to incorporate polyamines into protein substrates. Accumulating lines of inquiry indicate that specific TG isoforms can shuttle into the nucleus when they sense pathologic changes in calcium or oxidative stress, bind to chromatin and thereby transduce these changes into transcriptional repression of genes involved in metabolic or oxidant adaptation. Here, we review the evidence that supports principally a role for one isoform of this family, TG2, in cell injury and death associated with hemorrhagic or ischemic stroke. We also outline an evolving model in which TG2 is a critical mediator between pathologic signaling and epigenetic modifications that lead to gene repression. Accordingly, the salutary effects of TG inhibitors in stroke may derive from their ability to restore homeostasis by removing inappropriate deactivation of adaptive genetic programs by oxidative stress or extrasynaptic glutamate receptor signaling. PMID:23571278

  16. Group III metabotropic glutamate receptors and drug addiction

    OpenAIRE

    Mao, Limin; Guo, Minglei; Jin, Daozhong; Xue, Bing; Wang, John Q.

    2013-01-01

    Neuroadaptations of glutamatergic transmission in the limbic reward circuitry are linked to persistent drug addiction. Accumulating data have demonstrated roles of ionotropic glutamate receptors and group I and II metabotropic glutamate receptors (mGluRs) in this event. Emerging evidence also identifies Gαi/o-coupled group III mGluRs (mGluR4/7/8 subtypes enriched in the limbic system) as direct substrates of drugs of abuse and active regulators of drug action. Auto- and heteroreceptors of mGl...

  17. Neuroprotection by α2-Adrenergic Receptor Stimulation after Excitotoxic Retinal Injury: A Study of the Total Population of Retinal Ganglion Cells and Their Distribution in the Chicken Retina

    Science.gov (United States)

    Galindo-Romero, Caridad; Harun-Or-Rashid, Mohammad; Jiménez-López, Manuel; Vidal-Sanz, Manuel; Agudo-Barriuso, Marta

    2016-01-01

    We have studied the effect of α2-adrenergic receptor stimulation on the total excitotoxically injured chicken retinal ganglion cell population. N-methyl-D-aspartate (NMDA) was intraocularly injected at embryonic day 18 and Brn3a positive retinal ganglion cells (Brn3a+ RGCs) were counted in flat-mounted retinas using automated routines. The number and distribution of the Brn3a+ RGCs were analyzed in series of normal retinas from embryonic day 8 to post-hatch day 11 retinas and in retinas 7 or 14 days post NMDA lesion. The total number of Brn3a+ RGCs in the post-hatch retina was approximately 1.9x106 with a density of approximately 9.2x103 cells/mm2. The isodensity maps of normal retina showed that the density decreased with age as the retinal size increased. In contrast to previous studies, we did not find any specific region with increased RGC density, rather the Brn3a+ RGCs were homogeneously distributed over the central retina with decreasing density in the periphery and in the region of the pecten oculli. Injection of 5–10 μg NMDA caused 30–50% loss of Brn3a+ cells and the loss was more severe in the dorsal than in the ventral retina. Pretreatment with brimonidine reduced the loss of Brn3a+ cells both 7 and 14 days post lesion and the protective effect was higher in the dorsal than in the ventral retina. We conclude that α2-adrenergic receptor stimulation reduced the impact of the excitotoxic injury in chicken similarly to what has been shown in mammals. Furthermore, the data show that the RGCs are evenly distributed over in the retina, which challenges previous results that indicate the presence of specific high RGC-density regions of the chicken retina. PMID:27611432

  18. CGP37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger, protects neurons from excitotoxicity by blocking voltage-gated Ca2+ channels.

    Science.gov (United States)

    Ruiz, A; Alberdi, E; Matute, C

    2014-04-10

    Inhibition of the mitochondrial Na(+)/Ca(2+) exchanger (NCLX) by CGP37157 is protective in models of neuronal injury that involve disruption of intracellular Ca(2+) homeostasis. However, the Ca(2+) signaling pathways and stores underlying neuroprotection by that inhibitor are not well defined. In the present study, we analyzed how intracellular Ca(2+) levels are modulated by CGP37157 (10 μM) during NMDA insults in primary cultures of rat cortical neurons. We initially assessed the presence of NCLX in mitochondria of cultured neurons by immunolabeling, and subsequently, we analyzed the effects of CGP37157 on neuronal Ca(2+) homeostasis using cameleon-based mitochondrial Ca(2+) and cytosolic Ca(2+) ([Ca(2+)]i) live imaging. We observed that NCLX-driven mitochondrial Ca(2+) exchange occurs in cortical neurons under basal conditions as CGP37157 induced a decrease in [Ca(2)]i concomitant with a Ca(2+) accumulation inside the mitochondria. In turn, CGP37157 also inhibited mitochondrial Ca(2+) efflux after the stimulation of acetylcholine receptors. In contrast, CGP37157 strongly prevented depolarization-induced [Ca(2+)]i increase by blocking voltage-gated Ca(2+) channels (VGCCs), whereas it did not induce depletion of ER Ca(2+) stores. Moreover, mitochondrial Ca(2+) overload was reduced as a consequence of diminished Ca(2+) entry through VGCCs. The decrease in cytosolic and mitochondrial Ca(2+) overload by CGP37157 resulted in a reduction of excitotoxic mitochondrial damage, characterized here by a reduction in mitochondrial membrane depolarization, oxidative stress and calpain activation. In summary, our results provide evidence that during excitotoxicity CGP37157 modulates cytosolic and mitochondrial Ca(2+) dynamics that leads to attenuation of NMDA-induced mitochondrial dysfunction and neuronal cell death by blocking VGCCs.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  20. 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

  1. 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

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

    OpenAIRE

    Ajay Kumar

    2010-01-01

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

  3. Temperature differentially facilitates spontaneous but not evoked glutamate release from cranial visceral primary afferents.

    Directory of Open Access Journals (Sweden)

    Jessica A Fawley

    Full Text Available Temperature is fundamentally important to all biological functions including synaptic glutamate release. Vagal afferents from the solitary tract (ST synapse on second order neurons in the nucleus of the solitary tract, and glutamate release at this first central synapse controls autonomic reflex function. Expression of the temperature-sensitive Transient Receptor Potential Vanilloid Type 1 receptor separates ST afferents into C-fibers (TRPV1+ and A-fibers (TRPV1-. Action potential-evoked glutamate release is similar between C- and A-fiber afferents, but TRPV1 expression facilitates a second form of synaptic glutamate release in C-fibers by promoting substantially more spontaneous glutamate release. The influence of temperature on different forms of glutamate release is not well understood. Here we tested how temperature impacts the generation of evoked and spontaneous release of glutamate and its relation to TRPV1 expression. In horizontal brainstem slices of rats, activation of ST primary afferents generated synchronous evoked glutamate release (ST-eEPSCs at constant latency whose amplitude reflects the probability of evoked glutamate release. The frequency of spontaneous EPSCs in these same neurons measured the probability of spontaneous glutamate release. We measured both forms of glutamate from each neuron during ramp changes in bath temperature of 4-5 °C. Spontaneous glutamate release from TRPV1+ closely tracked with these thermal changes indicating changes in the probability of spontaneous glutamate release. In the same neurons, temperature changed axon conduction registered as latency shifts but ST-eEPSC amplitudes were constant and independent of TRPV1 expression. These data indicate that TRPV1-operated glutamate release is independent of action potential-evoked glutamate release in the same neurons. Together, these support the hypothesis that evoked and spontaneous glutamate release originate from two pools of vesicles that are

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

    Directory of Open Access Journals (Sweden)

    Santokh Gill

    2010-05-01

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

  5. Astrocyte/neuron ratio and its importance on glutamate toxicity: an in vitro voltammetric study.

    Science.gov (United States)

    Hacimuftuoglu, Ahmet; Tatar, Abdulgani; Cetin, Damla; Taspinar, Numan; Saruhan, Fatih; Okkay, Ufuk; Turkez, Hasan; Unal, Deniz; Stephens, Robert Louis; Suleyman, Halis

    2016-08-01

    The purpose of this study was to clarify the relationship between neuron cells and astrocyte cells in regulating glutamate toxicity on the 10th and 20th day in vitro. A mixed primary culture system from newborn rats that contain cerebral cortex neurons cells was employed to investigate the glutamate toxicity. All cultures were incubated with various glutamate concentrations, then viability tests and histological analyses were performed. The activities of glutamate transporters were determined by using in vitro voltammetry technique. Viable cell number was decreased significantly on the 10th day at 10(-7) M and at 10(-6) M glutamate applications, however, viable cell number was not decreased at 20th day. Astrocyte number was increased nearly six times on the 20th day as compared to the 10th day. The peak point of glutamate reuptake capacity was about 2 × 10(-4) M on the 10th day and 10(-3) M on the 20th day. According to our results, we suggested that astrocyte age was important to maintain neuronal survival against glutamate toxicity. Thus, we revealed activation or a trigger point of glutamate transporters on astrocytes due to time since more glutamate was taken up by astrocytes when glutamate transporters on the astrocyte were triggered with high exogenous glutamate concentrations. In conclusion, the present investigation is the first voltammetric study on the reuptake parameters of glutamate in vitro. PMID:26438331

  6. 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.

  7. 21 CFR 573.500 - Condensed, extracted glutamic acid fermentation product.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Condensed, extracted glutamic acid fermentation... fermentation product. Condensed, extracted glutamic acid fermentation product may be safely used in animal feed... the extraction of glutamic acid, combined with the cells of Corynebacterium lilium used to produce...

  8. Arsenic exposure and glutamate-induced gliotransmitter release from astrocytes

    Institute of Scientific and Technical Information of China (English)

    Yan Wang; Fenghong Zhao; Yingjun Liao; Yaping Jin; Guifan Sun

    2012-01-01

    The present study used cultures of primary astrocytes, isolated from neonatal rats, to verify the hypothesis that arsenite-induced neurotoxicity can influence neuronal function by altering glutamate-induced gliotransmitter release. Primary astrocytes were exposed to 0, 2.5, 5, 10, 20 or 30 μM arsenite for 24 hours. Cell viability and morphological observations revealed that 5 μM arsenic exposure could induce cytotoxicity. Cells were then cultured in the presence of 0, 2.5, 5, or 10 μM arsenite for 24 hours and stimulated with 25 μM glutamate for 10 minutes. Results showed that [Ca2+]i in astrocytes exposed to 5 and 10 μM arsenite was significantly increased and levels of D-serine, γ-aminobutyric acid and glycine in cultures exposed to 2.5–10 μM arsenite were also increased. However, glutamate levels in the media were significantly increased only after treatment with 10 μM arsenite. In conclusion, our findings suggest that arsenic exposure may affect glutamate-induced gliotransmitter release from astrocytes and further disturb neuronal function.

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

    Science.gov (United States)

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

    2013-01-01

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

  10. Glutamate neurotransmission is affected in prenatally stressed offspring

    DEFF Research Database (Denmark)

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

    2015-01-01

    Previous studies from our laboratory have shown that male adult offspring of stressed mothers exhibited higher levels of ionotropic and metabotropic glutamate receptors than control rats. These offspring also showed long-lasting astroglial hypertrophy and a reduced dendritic arborization with syn...

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

    DEFF Research Database (Denmark)

    Jinap, Selamat; Hajeb, Parvaneh; Karim, Roslina;

    2016-01-01

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

  12. Palmitoylethanolamide Inhibits Glutamate Release in Rat Cerebrocortical Nerve Terminals

    Directory of Open Access Journals (Sweden)

    Tzu-Yu Lin

    2015-03-01

    Full Text Available The effect of palmitoylethanolamide (PEA, an endogenous fatty acid amide displaying neuroprotective actions, on glutamate release from rat cerebrocortical nerve terminals (synaptosomes was investigated. PEA inhibited the Ca2+-dependent release of glutamate, which was triggered by exposing synaptosomes to the potassium channel blocker 4-aminopyridine. This release inhibition was concentration dependent, associated with a reduction in cytosolic Ca2+ concentration, and not due to a change in synaptosomal membrane potential. The glutamate release-inhibiting effect of PEA was prevented by the Cav2.1 (P/Q-type channel blocker ω-agatoxin IVA or the protein kinase A inhibitor H89, not affected by the intracellular Ca2+ release inhibitors dantrolene and CGP37157, and partially antagonized by the cannabinoid CB1 receptor antagonist AM281. Based on these results, we suggest that PEA exerts its presynaptic inhibition, likely through a reduction in the Ca2+ influx mediated by Cav2.1 (P/Q-type channels, thereby inhibiting the release of glutamate from rat cortical nerve terminals. This release inhibition might be linked to the activation of presynaptic cannabinoid CB1 receptors and the suppression of the protein kinase A pathway.

  13. 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

  14. Delineation of an in vivo inhibitor for Aspergillus glutamate dehydrogenase.

    Science.gov (United States)

    Choudhury, Rajarshi; Noor, Shahid; Varadarajalu, Lakshmi Prabha; Punekar, Narayan S

    2008-01-01

    NADP-glutamate dehydrogenase (NADP-GDH) along with glutamine synthetase plays a pivotal role in ammonium assimilation. Specific inhibitors were valuable in defining the importance of glutamine synthetase in nitrogen metabolism. Selective in vivo inhibition of NADP-GDH has so far been an elusive desideratum. Isophthalate, a potent in vitro inhibitor of Aspergillus niger NADP-GDH [Noor S, Punekar NS. Allosteric NADP-glutamate dehydrogenase from aspergilli: purification, characterization and implications for metabolic regulation at the carbon-nitrogen interface. Microbiology 2005;151:1409-19], was evaluated for its efficacy in vivo. Dimethyl ester of isophthalate (DMIP), but not isophthalate, inhibited A. niger growth on agar as well as in liquid culture. This was ascribed to the inability of isophthalate to enter fungal mycelia. Subsequent to DMIP addition however, intracellular isophthalate could be demonstrated. Apart from NAD-GDH, no other enzyme including NAD-glutamate synthase was inhibited by isophthalate. A cross-over at NADP-GDH step of metabolism was observed as a direct consequence of isophthalate (formed in vivo from DMIP) inhibiting this enzyme. Addition of ammonium to DMIP-treated A. niger mycelia resulted in intensive vacuolation, retraction of cytoplasm and autolysis. Taken together, these results implicate glutamate dehydrogenase and NADP-GDH in particular, as a key target of in vivo isophthalate inhibition during ammonium assimilation. PMID:22578865

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

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, M;

    1992-01-01

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

  16. 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.

  17. Microbial production and chemical transformation of poly-γ-glutamate.

    Science.gov (United States)

    Ashiuchi, Makoto

    2013-11-01

    Poly-γ-glutamate (PGA), a novel polyamide material with industrial applications, possesses a nylon-like backbone, is structurally similar to polyacrylic acid, is biodegradable and is safe for human consumption. PGA is frequently found in the mucilage of natto, a Japanese traditional fermented food. To date, three different types of PGA, namely a homo polymer of D-glutamate (D-PGA), a homo polymer of L-glutamate (L-PGA), and a random copolymer consisting of D- and L-glutamate (DL-PGA), are known. This review will detail the occurrence and physiology of PGA. The proposed reaction mechanism of PGA synthesis including its localization and the structure of the involved enzyme, PGA synthetase, are described. The occurrence of multiple carboxyl residues in PGA likely plays a role in its relative unsuitability for the development of bio-nylon plastics and thus, establishment of an efficient PGA-reforming strategy is of great importance. Aside from the potential applications of PGA proposed to date, a new technique for chemical transformation of PGA is also discussed. Finally, some techniques for PGA and its derivatives in advanced material technology are presented.

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

    Directory of Open Access Journals (Sweden)

    Hansson Elisabeth

    2004-11-01

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

  19. Acute effects of the ampakine farampator on memory and information processing in healthy elderly volunteers.

    NARCIS (Netherlands)

    Wezenberg, E.; Verkes, R.J.; Ruigt, G.S.F.; Hulstijn, W.; Sabbe, B.G.C.C.

    2007-01-01

    Ampakines act as positive allosteric modulators of AMPA-type glutamate receptors and facilitate hippocampal long-term potentiation (LTP), a mechanism associated with memory storage and consolidation. The present study investigated the acute effects of farampator, 1-(benzofurazan-5-ylcarbonyl) piperi

  20. Maturation of calcium-dependent GABA, glycine, and glutamate release in the glycinergic MNTB-LSO pathway.

    Directory of Open Access Journals (Sweden)

    Javier Alamilla

    Full Text Available The medial nucleus of the trapezoid body (MNTB is a key nucleus in high-fidelity temporal processing that underlies sound localization in the auditory brainstem. While the glycinergic principal cells of the MNTB project to all primary nuclei of the superior olive, during development the projection from MNTB to the lateral superior olive (LSO is of interest because this immature inhibitory projection is known to undergo tonotopic refinement during an early postnatal period, and because during this period individual MNTB terminals in the LSO transiently release glycine GABA and glutamate. Developmental changes in calcium-dependent release are understood to be required to allow various auditory nuclei to follow high frequency activity; however, little is known about maturation of calcium-dependent release in the MNTB-LSO pathway, which has been presumed to have less stringent requirements for high-fidelity temporal following. In acute brainstem slices of rats age postnatal day 1 to 15 we recorded whole-cell responses in LSO principal neurons to electrical stimulation in the MNTB in order to measure sensitivity to external calcium, the contribution of different voltage-gated calcium channel subtypes to vesicular release, and the maturation of these measures for both GABA/glycine and glutamate transmission. Our results establish that release of glutamate at MNTB-LSO synapses is calcium-dependent. Whereas no significant developmental changes were evident for glutamate release, GABA/glycine release underwent substantial changes over the first two postnatal weeks: soon after birth L-type, N-type, and P/Q-type voltage-gated calcium channels (VGCCs together mediated release, but after hearing onset P/Q-type VGCCs predominated. Blockade of P/Q-type VGCCs reduced the estimated quantal number for GABA/gly and glutamate transmission at P5-8 and the frequency of evoked miniature glycinergic events at P12-15, without apparent effects on spontaneous release of

  1. Glutamate and GABA in Vestibulo-Sympathetic Pathway Neurons.

    Science.gov (United States)

    Holstein, Gay R; Friedrich, Victor L; Martinelli, Giorgio P

    2016-01-01

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

  2. Glutamate and GABA in Vestibulo-Sympathetic Pathway Neurons.

    Science.gov (United States)

    Holstein, Gay R; Friedrich, Victor L; Martinelli, Giorgio P

    2016-01-01

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

  3. Glutamate and GABA in vestibulo-sympathetic pathway neurons

    Directory of Open Access Journals (Sweden)

    Gay R Holstein

    2016-02-01

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

  4. D1R/GluN1 complexes in the striatum integrate dopamine and glutamate signalling to control synaptic plasticity and cocaine-induced responses.

    Science.gov (United States)

    Cahill, E; Pascoli, V; Trifilieff, P; Savoldi, D; Kappès, V; Lüscher, C; Caboche, J; Vanhoutte, P

    2014-12-01

    Convergent dopamine and glutamate signalling onto the extracellular signal-regulated kinase (ERK) pathway in medium spiny neurons (MSNs) of the striatum controls psychostimulant-initiated adaptive processes underlying long-lasting behavioural changes. We hypothesised that the physical proximity of dopamine D1 (D1R) and glutamate NMDA (NMDAR) receptors, achieved through the formation of D1R/NMDAR complexes, may act as a molecular bridge that controls the synergistic action of dopamine and glutamate on striatal plasticity and behavioural responses to drugs of abuse. We found that concomitant stimulation of D1R and NMDAR drove complex formation between endogenous D1R and the GluN1 subunit of NMDAR. Conversely, preventing D1R/GluN1 association with a cell-permeable peptide (TAT-GluN1C1) left individual D1R and NMDAR-dependent signalling intact, but prevented D1R-mediated facilitation of NMDAR-calcium influx and subsequent ERK activation. Electrophysiological recordings in striatal slices from mice revealed that D1R/GluN1 complexes control the D1R-dependent enhancement of NMDAR currents and long-term potentiation in D1R-MSN. Finally, intra-striatal delivery of TAT-GluN1C1 did not affect acute responses to cocaine but reduced behavioural sensitization. Our findings uncover D1R/GluN1 complexes as a major substrate for the dopamine-glutamate interaction in MSN that is usurped by addictive drugs to elicit persistent behavioural alterations. They also identify D1R/GluN1 complexes as molecular targets with a therapeutic potential for the vast spectrum of psychiatric diseases associated with an imbalance between dopamine and glutamate transmission. PMID:25070539

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

    Directory of Open Access Journals (Sweden)

    Mortiz eArmbruster

    2014-09-01

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

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

    DEFF Research Database (Denmark)

    Vetterli, Laurène; Carobbio, Stefania; Pournourmohammadi, Shirin;

    2012-01-01

    In pancreatic β-cells, glutamate dehydrogenase (GDH) modulates insulin secretion, although its function regarding specific secretagogues is unclear. This study investigated the role of GDH using a β-cell-specific GDH knockout mouse model, called βGlud1(-/-). The absence of GDH in islets isolated ...

  7. Calmodulin binding to glutamate decarboxylase is required for regulation of glutamate and GABA metabolism and normal development in plants.

    Science.gov (United States)

    Baum, G; Lev-Yadun, S; Fridmann, Y; Arazi, T; Katsnelson, H; Zik, M; Fromm, H

    1996-06-17

    Glutamate decarboxylase (GAD) catalyzes the decarboxylation of glutamate to CO2 and gamma-aminobutyrate (GABA). GAD is ubiquitous in prokaryotes and eukaryotes, but only plant GAD has been shown to bind calmodulin (CaM). Here, we assess the role of the GAD CaM-binding domain in vivo. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain (GADdeltaC plants) exhibit severe morphological abnormalities, such as short stems, in which cortex parenchyma cells fail to elongate, associated with extremely high GABA and low glutamate levels. The morphology of transgenic plants expressing the full-length GAD (GAD plants) is indistinguishable from that of wild-type (WT) plants. In WT and GAD plant extracts, GAD activity is inhibited by EGTA and by the CaM antagonist trifluoperazine, and is associated with a CaM-containing protein complex of approximately 500 kDa. In contrast, GADdeltaC plants lack normal GAD complexes, and GAD activity in their extracts is not affected by EGTA and trifluoperazine. We conclude that CaM binding to GAD is essential for the regulation of GABA and glutamate metabolism, and that regulation of GAD activity is necessary for normal plant development. This study is the first to demonstrate an in vivo function for CaM binding to a target protein in plants.

  8. Simultaneous and selective production of levan and poly(gamma-glutamic acid) by Bacillus subtilis.

    Science.gov (United States)

    Shih, Ing-Lung; Yu, Yun-Ti

    2005-01-01

    Bacillus subtilis(natto) Takahashi, used to prepare the fermented soybean product natto, was grown in a basal medium containing 5% (w/w) sucrose and 1.5% (w/w) L-glutamate and produced 58% (w/w) poly(gamma-glutamic acid) and 42% (w/w) levan simultaneously. After 21 h, 40-50 mg levan ml-1 had been produced in medium containing 20% (w/w) sucrose but without L-glutamate. In medium containing L-glutamic acid but without sucrose, mainly poly(gamma-glutamic acid) was produced. PMID:15703872

  9. Hypoxia regulates glutamate metabolism and membrane transport in rat PC12 cells.

    Science.gov (United States)

    Kobayashi, S; Millhorn, D E

    2001-03-01

    We investigated the effect of hypoxia on glutamate metabolism and uptake in rat pheochromocytoma (PC12) cells. Various key enzymes relevant to glutamate production, metabolism and transport were coordinately regulated by hypoxia. PC12 cells express two glutamate-metabolizing enzymes, glutamine synthetase (GS) and glutamate decarboxylase (GAD), as well as the glutamate-producing enzyme, phosphate-activated glutaminase (PAG). Exposure to hypoxia (1% O(2)) for 6 h or longer increased expression of GS mRNA and protein and enhanced GS enzymatic activity. In contrast, hypoxia caused a significant decrease in expression of PAG mRNA and protein, and also decreased PAG activity. In addition, hypoxia led to an increase in GAD65 and GAD67 protein levels and GAD enzymatic activity. PC12 cells express three Na(+)-dependent glutamate transporters; EAAC1, GLT-1 and GLAST. Hypoxia increased EAAC1 and GLT-1 protein levels, but had no effect on GLAST. Chronic hypoxia significantly enhanced the Na(+)-dependent component of glutamate transport. Furthermore, chronic hypoxia decreased cellular content of glutamate, but increased that of glutamine. Taken together, the hypoxia-induced changes in enzymes related to glutamate metabolism and transport are consistent with a decrease in the extracellular concentration of glutamate. This may have a role in protecting PC12 cells from the cytotoxic effects of glutamate during chronic hypoxia. PMID:11259512

  10. Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells

    Science.gov (United States)

    Brew, Helen; Attwell, David

    1987-06-01

    Glutamate is taken up avidly by glial cells in the central nervous system1. Glutamate uptake may terminate the transmitter action of glutamate released from neurons1, and keep extracellular glutamate at concentrations below those which are neurotoxic. We report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique2. This current seems to be due to an electrogenic glutamate uptake carrier, which transports at least two sodium ions with every glutamate anion carried into the cell. Glutamate uptake is strongly voltage-dependent, decreasing at depolarized potentials: when fully activated, it contributes almost half of the conductance in the part of the glial cell membrane facing the retinal neurons. The spatial localization, glutamate affinity and magnitude of the uptake are appropriate for terminating the synaptic action of glutamate released from photoreceptors and bipolar cells. These data challenge present explanations of how the b-wave of the electroretinogram is generated, and suggest a mechanism for non-vesicular voltage-dependent release of glutamate from neurons.

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

    DEFF Research Database (Denmark)

    Karaca, Melis; Frigerio, Francesca; Migrenne, Stephanie;

    2015-01-01

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

  12. Metabolic pathways and activity-dependent modulation of glutamate concentration in the human brain.

    Science.gov (United States)

    Mangia, Silvia; Giove, Federico; Dinuzzo, Mauro

    2012-11-01

    Glutamate is one of the most versatile molecules present in the human brain, involved in protein synthesis, energy production, ammonia detoxification, and transport of reducing equivalents. Aside from these critical metabolic roles, glutamate plays a major part in brain function, being not only the most abundant excitatory neurotransmitter, but also the precursor for γ-aminobutyric acid, the predominant inhibitory neurotransmitter. Regulation of glutamate levels is pivotal for normal brain function, as abnormal extracellular concentration of glutamate can lead to impaired neurotransmission, neurodegeneration and even neuronal death. Understanding how the neuron-astrocyte functional and metabolic interactions modulate glutamate concentration during different activation status and under physiological and pathological conditions is a challenging task, and can only be tentatively estimated from current literature. In this paper, we focus on describing the various metabolic pathways which potentially affect glutamate concentration in the brain, and emphasize which ones are likely to produce the variations in glutamate concentration observed during enhanced neuronal activity in human studies.

  13. Acute dyspnea

    International Nuclear Information System (INIS)

    Radiodiagnosis is applied to determine the causes of acute dyspnea. Acute dyspnea is shown to aggravate the course of pulmonary diseases (bronchial asthma, obstructive bronchitis, pulmonary edema, throboembolism of pulmonary arteries etc) and cardiovascular diseases (desiseas of myocardium). The main tasks of radiodiagnosis are to determine volume and state of the lungs, localization and type of pulmonary injuries, to verify heart disease and to reveal concomitant complications

  14. Genes involved in Drosophila glutamate receptor expression and localization

    Directory of Open Access Journals (Sweden)

    Featherstone David E

    2005-06-01

    Full Text Available Abstract Background A clear picture of the mechanisms controlling glutamate receptor expression, localization, and stability remains elusive, possibly due to an incomplete understanding of the proteins involved. We screened transposon mutants generated by the ongoing Drosophila Gene Disruption Project in an effort to identify the different types of genes required for glutamate receptor cluster development. Results To enrich for non-silent insertions with severe disruptions in glutamate receptor clustering, we identified and focused on homozygous lethal mutants in a collection of 2185 BG and KG transposon mutants generated by the BDGP Gene Disruption Project. 202 lethal mutant lines were individually dissected to expose glutamatergic neuromuscular junctions, stained using antibodies that recognize neuronal membrane and the glutamate receptor subunit GluRIIA, and viewed using laser-scanning confocal microscopy. We identified 57 mutants with qualitative differences in GluRIIA expression and/or localization. 84% of mutants showed loss of receptors and/or clusters; 16% of mutants showed an increase in receptors. Insertion loci encode a variety of protein types, including cytoskeleton proteins and regulators, kinases, phosphatases, ubiquitin ligases, mucins, cell adhesion proteins, transporters, proteins controlling gene expression and protein translation, and proteins of unknown/novel function. Expression pattern analyses and complementation tests, however, suggest that any single mutant – even if a mutant gene is uniquely tagged – must be interpreted with caution until the mutation is validated genetically and phenotypically. Conclusion Our study identified 57 transposon mutants with qualitative differences in glutamate receptor expression and localization. Despite transposon tagging of every insertion locus, extensive validation is needed before one can have confidence in the role of any individual gene. Alternatively, one can focus on the

  15. 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

  16. Glutamate metabolism in the brain focusing on astrocytes

    DEFF Research Database (Denmark)

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

    2014-01-01

    Metabolism of glutamate, the main excitatory neurotransmitter and precursor of GABA, is exceedingly complex and highly compartmentalized in brain. Maintenance of these neurotransmitter pools is strictly dependent on the de novo synthesis of glutamine in astrocytes which requires both the anaplero......Metabolism of glutamate, the main excitatory neurotransmitter and precursor of GABA, is exceedingly complex and highly compartmentalized in brain. Maintenance of these neurotransmitter pools is strictly dependent on the de novo synthesis of glutamine in astrocytes which requires both......, as well as in nitrogen trafficking and ammonia homeostasis in brain. The anatomical specialization of astrocytic endfeet enables these cells to rapidly and efficiently remove neurotransmitters from the synaptic cleft to maintain homeostasis, and to provide glutamine to replenish neurotransmitter pools...... summarizes the evidence that astrocytes are essential and dynamic partners in both glutamatergic and GABAergic neurotransmission in brain....

  17. [Cardioprotective properties of new glutamic acid derivative under stress conditions].

    Science.gov (United States)

    Perfilova, V N; Sadikova, N V; Berestovitskaia, V M; Vasil'eva, O S

    2014-01-01

    The effect of new glutamic acid derivative on the cardiac ino- and chronotropic functions has been studied in experiments on rats exposed to 24-hour immobilization-and-pain stress. It is established that glutamic acid derivative RGPU-238 (glufimet) at a dose of 28.7 mg/kg increases the increment of myocardial contractility and relaxation rates and left ventricular pressure in stress-tested animals by 13 1,1, 72.4, and 118.6%, respectively, as compared to the control group during the test for adrenoreactivity. Compound RGPU-238 increases the increment of the maximum intensity of myocardium functioning by 196.5 % at 30 sec of isometric workload as compared to the control group. The cardioprotective effect of compound RGPU-238 is 1.5 - 2 times higher than that of the reference drug phenibut. PMID:25365864

  18. 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. PMID:27296644

  19. Functional Insights from Glutamate Receptor Ion Channel Structures

    Science.gov (United States)

    Kumar, Janesh; Mayer, Mark L.

    2014-01-01

    X-ray crystal structures for the soluble amino terminal and ligand binding domains of glutamate receptor ion channels, combined with a 3.6 Å resolution structure of the full length AMPA receptor GluA2 homotetramer, provide unique insights into the mechanisms of iGluR assembly and function. Increasingly sophisticated biochemical, computational and electrophysiological experiments are beginning to reveal the mechanism of action of partial agonists, and yield new models for the mechanism of action of allosteric modulators. Newly identified NMDA receptor ligands acting at novel sites offer hope for development of subtype selective modulators. Many issues remain unsolved, including the role of the ATD in AMPA receptor signaling, and the mechanisms by which auxiliary proteins regulate receptor activity. The structural basis for ion permeation and ion channel block also remain areas of uncertainty, and despite substantial progress, molecular dynamics simulations have yet to reveal how binding of glutamate opens the ion channel pore. PMID:22974439

  20. 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.

  1. Leptin regulates glutamate and glucose transporters in hypothalamic astrocytes

    Science.gov (United States)

    Fuente-Martín, Esther; García-Cáceres, Cristina; Granado, Miriam; de Ceballos, María L.; Sánchez-Garrido, Miguel Ángel; Sarman, Beatrix; Liu, Zhong-Wu; Dietrich, Marcelo O.; Tena-Sempere, Manuel; Argente-Arizón, Pilar; Díaz, Francisca; Argente, Jesús; Horvath, Tamas L.; Chowen, Julie A.

    2012-01-01

    Glial cells perform critical functions that alter the metabolism and activity of neurons, and there is increasing interest in their role in appetite and energy balance. Leptin, a key regulator of appetite and metabolism, has previously been reported to influence glial structural proteins and morphology. Here, we demonstrate that metabolic status and leptin also modify astrocyte-specific glutamate and glucose transporters, indicating that metabolic signals influence synaptic efficacy and glucose uptake and, ultimately, neuronal function. We found that basal and glucose-stimulated electrical activity of hypothalamic proopiomelanocortin (POMC) neurons in mice were altered in the offspring of mothers fed a high-fat diet. In adulthood, increased body weight and fasting also altered the expression of glucose and glutamate transporters. These results demonstrate that whole-organism metabolism alters hypothalamic glial cell activity and suggest that these cells play an important role in the pathology of obesity. PMID:23064363

  2. Acute myelogenous leukemia (AML) - children

    Science.gov (United States)

    Acute myelogenous leukemia - children; AML; Acute myeloid leukemia - children; Acute granulocytic leukemia - children; Acute myeloblastic leukemia - children; Acute non-lymphocytic leukemia (ANLL) - children

  3. Penurunan Jumlah Sperma Hewan Coba Akibat Paparan Monosodium Glutamate

    OpenAIRE

    Eka Roina, Megawati

    2010-01-01

    Monosodium glutamate (MSG) merupakan penyedap rasa yang banyak digunakan karena akan membuat rasa makanan menjadi lebih enak dan lezat dengan rasa umami yang dikategorikan sebagai rasa kelima dari empat rasa dasar yang ada. Tetapi konsumsi MSG dalam jumlah besar (≥100 g/kg berat badan) menimbulkan kecenderungan untuk terjadinya overweight. Sedangkan penelitian terhadap mencit dan tikus pemberian MSG dengan dosis 4 mg/g berat badan baik secara suntikan subkutan ataupun intraperitoneal dapat me...

  4. Glutamate receptors: variation in structure-function coupling

    DEFF Research Database (Denmark)

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

    2006-01-01

    Fast excitatory synaptic transmission in the CNS relies almost entirely on the neurotransmitter glutamate and its family of ion channel receptors. An appreciation of the coupling between agonist binding and channel opening has advanced rapidly during the past five years, largely as a result of ne...... structural information about the agonist-binding site. Recent studies suggest that despite many structural similarities different family members use different mechanisms to translate agonist binding into channel opening....

  5. Glutamate and GABA in Vestibulo-Sympathetic Pathway Neurons

    OpenAIRE

    Holstein, Gay R.; Friedrich, Victor L. Jr.; Martinelli, Giorgio P.

    2016-01-01

    The vestibulo-sympathetic reflex (VSR) actively modulates blood pressure during changes in posture. This reflex allows humans to stand up and quadrupeds to rear or climb without a precipitous decline in cerebral perfusion. The VSR pathway conveys signals from the vestibular end organs to the caudal vestibular nuclei. These cells, in turn, project to pre-sympathetic neurons in the rostral and caudal ventrolateral medulla (RVLM and CVLM, respectively). The present study assessed glutamate- and ...

  6. Crystal structure of a chimaeric bacterial glutamate dehydrogenase

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-23

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

  7. Crystal structure of a chimaeric bacterial glutamate dehydrogenase.

    Science.gov (United States)

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

    2016-06-01

    Glutamate dehydrogenases (EC 1.4.1.2-4) catalyse the oxidative deamination of L-glutamate to α-ketoglutarate using NAD(P)(+) as a cofactor. The bacterial enzymes are hexameric, arranged with 32 symmetry, and each polypeptide consists of an N-terminal substrate-binding segment (domain I) followed by a C-terminal cofactor-binding segment (domain II). The catalytic reaction takes place in the cleft formed at the junction of the two domains. Distinct signature sequences in the nucleotide-binding domain have been linked to the binding of NAD(+) versus NADP(+), but they are not unambiguous predictors of cofactor preference. In the absence of substrate, the two domains move apart as rigid bodies, as shown by the apo structure of glutamate dehydrogenase from Clostridium symbiosum. Here, the crystal structure of a chimaeric clostridial/Escherichia coli enzyme has been determined in the apo state. The enzyme is fully functional and reveals possible determinants of interdomain flexibility at a hinge region following the pivot helix. The enzyme retains the preference for NADP(+) cofactor from the parent E. coli domain II, although there are subtle differences in catalytic activity. PMID:27303899

  8. Group III metabotropic glutamate receptors and drug addiction.

    Science.gov (United States)

    Mao, Limin; Guo, Minglei; Jin, Daozhong; Xue, Bing; Wang, John Q

    2013-12-01

    Neuroadaptations of glutamatergic transmission in the limbic reward circuitry are linked to persistent drug addiction. Accumulating data have demonstrated roles of ionotropic glutamate receptors and group I and II metabotropic glutamate receptors (mGluRs) in this event. Emerging evidence also identifies Gαi/o-coupled group III mGluRs (mGluR4/7/8 subtypes enriched in the limbic system) as direct substrates of drugs of abuse and active regulators of drug action. Auto- and heteroreceptors of mGluR4/7/8 reside predominantly on nerve terminals of glutamatergic corticostriatal and GABAergic striatopallidal pathways, respectively. These presynaptic receptors regulate basal and/or phasic release of respective transmitters to maintain basal ganglia homeostasis. In response to operant administration of common addictive drugs, such as psychostimulants (cocaine and amphetamine), alcohol and opiates, limbic group III mGluRs undergo drastic adaptations to contribute to the enduring remodeling of excitatory synapses and to usually suppress drug seeking behavior. As a result, a loss-of-function mutation (knockout) of individual group III receptor subtypes often promotes drug seeking. This review summarizes the data from recent studies on three group III receptor subtypes (mGluR4/7/8) expressed in the basal ganglia and analyzes their roles in the regulation of dopamine and glutamate signaling in the striatum and their participation in the addictive properties of three major classes of drugs (psychostimulants, alcohol, and opiates). PMID:24078068

  9. An Optimized Glutamate Receptor Photoswitch with Sensitized Azobenzene Isomerization.

    Science.gov (United States)

    Gascón-Moya, Marta; Pejoan, Arnau; Izquierdo-Serra, Mercè; Pittolo, Silvia; Cabré, Gisela; Hernando, Jordi; Alibés, Ramon; Gorostiza, Pau; Busqué, Félix

    2015-10-16

    A new azobenzene-based photoswitch, 2, has been designed to enable optical control of ionotropic glutamate receptors in neurons via sensitized two-photon excitation with NIR light. In order to develop an efficient and versatile synthetic route for this molecule, a modular strategy is described which relies on the use of a new linear fully protected glutamate derivative stable in basic media. The resulting compound undergoes one-photon trans-cis photoisomerization via two different mechanisms: direct excitation of its azoaromatic unit and irradiation of the pyrene sensitizer, a well-known two-photon sensitive chromophore. Moreover, 2 presents large thermal stability of its cis isomer, in contrast to other two-photon responsive switches relying on the intrinsic nonlinear optical properties of push-pull substituted azobenzenes. As a result, the molecular system developed herein is a very promising candidate for evoking large photoinduced biological responses during the multiphoton operation of neuronal glutamate receptors with NIR light, which require accumulation of the protein-bound cis state of the switch upon repeated illumination.

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

    Directory of Open Access Journals (Sweden)

    Nicholas P Vyleta

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

  11. Glutamate dehydrogenase from pumpkin cotyledons: characterization and isoenzymes.

    Science.gov (United States)

    Chou, K H; Splittstoesser, W E

    1972-04-01

    Glutamate dehydrogenase from pumpkin (Cucurbita moschata Pior. cultivar Dickinson Field) cotyledons was found in both soluble and particulate fractions with the bulk of the activity in the soluble fraction. Both enzymes used NAD(H) and NADP(H) but NAD(H) was favored. The enzymes were classified as glutamate-NAD oxidoreductase, deaminating (EC 1.4.1.3). Both enzymes were heat stable, had a pH optimum for reductive amination of 8.0, and were inhibited by high concentrations of NH(4) (+) or alpha-ketoglutarate. The soluble enzyme was more sensitive to NH(4) (+) inhibition and was activated by metal ions after ammonium sulfate fractionation while the solubilized particulate enzyme was not. Inhibition by ethylenediaminetetraacetate was restored by several divalent ions and inhibition by p-hydroxymercuribenzoate was reversed by glutathione. Particulate glutamate dehydrogenase showed a greater activity with NADP. The molecular weights of the enzymes are 250,000. Separation of the enzymes by disc gel electrophoresis showed that during germination the soluble isoenzymes increased from 1 to 7 in number, while only one particulate isoenzyme was found at any time. This particulate isoenzyme was identical with one of the soluble isoenzymes. A number of methods indicated that the soluble isoenzymes were not simply removed from the particulate fraction and that true isoenzymes were found.

  12. Glutamate signalling and its potential application to tissue engineering of bone

    Directory of Open Access Journals (Sweden)

    Mason D.

    2004-04-01

    Full Text Available Mechanical loading of the skeleton is important for maintenance of adequate bone mass and defined mechanical stimuli are highly osteogenic. The identification of mechanoresponsive signalling molecules in bone may allow osteogenic signals to be mimicked. This approach would be useful in the treatment of bone pathologies where the skeleton is too weak to withstand osteogenic forces and to tissue engineering of bone where the mechanical environment of bone cells is disrupted. Glutamate has been implicated as a mediator of mechanical signalling in bone. Evidence for glutamate signalling in bone, its role in mechanotransduction and potential applications of this pathway to tissue engineering of bone is considered in this review. Glutamate receptors, transporters and proteins that regulate glutamate release, are all expressed in bone cells. Glutamate receptor activation affects both osteoblast and osteoclast phenotypes revealing a potential for therapeutic manipulation of glutamate signalling to enhance bone formation. Glutamate transporters contribute to this system by regulating extracellular glutamate concentrations and acting as glutamate-gated ion channels. Artificial regulation of glutamate receptors or transporters may be used to increase the bone forming capacity of osteoblasts. This novel approach may potentially enhance bone tissue engineering strategies.

  13. Glutamate reduces experimental intestinal hyperpermeability and facilitates glutamine support of gut integrity

    Institute of Scientific and Technical Information of China (English)

    Mechteld AR Vermeulen; Jeffrey de Jong; Mathijs J Vaessen; Paul AM van Leeuwen; Alexander PJ Houdijk

    2011-01-01

    AIM: To assess whether glutamate plays a similar role to glutamine in preserving gut wall integrity. METHODS: The effects of glutamine and glutamate on induced hyperpermeability in intestinal cell lines were studied. Paracellular hyperpermeability was induced in Caco2.BBE and HT-29CL.19A cell lines by adding phorbol-12,13-dibutyrate (PDB) apically, after which the effects of glutamine and glutamate on horseradish peroxidase (HRP) diffusion were studied. An inhibitor of glutamate transport (L-trans-pyrrolidine-2,4-dicarboxylic acid: trans-PDC) and an irreversible blocker (acivicin) of the extracellular glutamine to glutamate converting enzyme, γ-glutamyltransferase, were used. RESULTS: Apical to basolateral HRP flux increased significantly compared to controls not exposed to PDB (n = 30, P < 0.001). Glutamine application reduced hyperpermeability by 19% and 39% in the respective cell lines. Glutamate application reduced hyperpermeability by 30% and 20%, respectively. Incubation of HT29CL.19A cells with acivicin and subsequent PDB and glutamine addition increased permeability levels. Incubation of Caco2.BBE cells with trans-PDC followed by PDB and glutamate addition also resulted in high permeability levels. CONCLUSION: Apical glutamate -similar to glutaminecan decrease induced paracellular hyperpermeability. Extracellular conversion of glutamine to glutamate and subsequent uptake of glutamate could be a pivotal step in the mechanism underlying the protective effect of glutamine.

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

    Directory of Open Access Journals (Sweden)

    Bita Forghani

    2012-05-01

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

  15. Glutamate-related gene expression changes with age in the mouse auditory midbrain.

    Science.gov (United States)

    Tadros, Sherif F; D'Souza, Mary; Zettel, Martha L; Zhu, Xiaoxia; Waxmonsky, Nicole C; Frisina, Robert D

    2007-01-01

    Glutamate is the main excitatory neurotransmitter in both the peripheral and central auditory systems. Changes of glutamate and glutamate-related genes with age may be an important factor in the pathogenesis of age-related hearing loss-presbycusis. In this study, changes in glutamate-related mRNA gene expression in the CBA mouse inferior colliculus with age and hearing loss were examined and correlations were sought between these changes and functional hearing measures, such as the auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs). Gene expression of 68 glutamate-related genes was investigated using both genechip microarray and real-time PCR (qPCR) molecular techniques for four different age/hearing loss CBA mouse subject groups. Two genes showed consistent differences between groups for both the genechip and qPCR. Pyrroline-5-carboxylate synthetase enzyme (Pycs) showed down-regulation with age and a high-affinity glutamate transporter (Slc1a3) showed up-regulation with age and hearing loss. Since Pycs plays a role in converting glutamate to proline, its deficiency in old age may lead to both glutamate increases and proline deficiencies in the auditory midbrain, playing a role in the subsequent inducement of glutamate toxicity and loss of proline neuroprotective effects. The up-regulation of Slc1a3 gene expression may reflect a cellular compensatory mechanism to protect against age-related glutamate or calcium excitoxicity.

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

    Directory of Open Access Journals (Sweden)

    Yijen A Huang

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

  17. Postnatal Administration of Allopregnanolone Modifies Glutamate Release but Not BDNF Content in Striatum Samples of Rats Prenatally Exposed to Ethanol

    Directory of Open Access Journals (Sweden)

    Roberto Yunes

    2015-01-01

    Full Text Available Ethanol consumption during pregnancy may induce profound changes in fetal CNS development. We postulate that some of the effects of ethanol on striatal glutamatergic transmission and neurotrophin expression could be modulated by allopregnanolone, a neurosteroid modulator of GABAA receptor activity. We describe the acute pharmacological effect of allopregnanolone (65 μg/kg, s.c. administered to juvenile male rats (day 21 of age on the corticostriatal glutamatergic pathway, in both control and prenatally ethanol-exposed rats (two ip injections of 2.9 g/kg in 24% v/v saline solution on gestational day 8. Prenatal ethanol administration decreased the K+-induced release of glutamate regarding the control group. Interestingly, this effect was reverted by allopregnanolone. Regarding BDNF, allopregnanolone decreases the content of this neurotrophic factor in the striatum of control groups. However, both ethanol alone and ethanol plus allopregnanolone treated animals did not show any change regarding control values. We suggest that prenatal ethanol exposure may produce an alteration of GABAA receptors which blocks the GABA agonist-like effect of allopregnanolone on rapid glutamate release, thus disturbing normal neural transmission. Furthermore, the reciprocal interactions found between GABAergic neurosteroids and BDNF could underlie mechanisms operating during the neuronal plasticity of fetal development.

  18. Activated microglia in acute encephalopathy with biphasic seizures and late reduced diffusion.

    Science.gov (United States)

    Fujita, Yuji; Takanashi, Jun-Ichi; Takei, Haruka; Ota, Setsuo; Fujii, Katsunori; Sakuma, Hiroshi; Hayashi, Masaharu

    2016-07-15

    Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype of infectious pediatric encephalopathy in Japan. The exact pathogenesis of and the best therapeutic strategy for AESD are uncertain. We firstly performed a brain biopsy in a 2-year-old boy with AESD associated with RS viral infection, which revealed activated ameoboid microglia accumulation around degenerated neuron, and astrogliosis in the affected cortex. Glutamate released from activated microglia may play an important role in the pathogenesis of AESD, which is compatible with the previous report of magnetic resonance spectroscopy showing elevated glutamate. PMID:27288783

  19. The Effect of Pro-Neurogenic Gene Expression on Adult Subventricular Zone Precursor Cell Recruitment and Fate Determination After Excitotoxic Brain Injury

    Science.gov (United States)

    Jones, Kathryn S; Connor, Bronwen J

    2016-01-01

    Despite the presence of on-going neurogenesis in the adult mammalian brain, neurons are generally not replaced after injury. Using a rodent model of excitotoxic cell loss and retroviral (RV) lineage tracing, we previously demonstrated transient recruitment of precursor cells from the subventricular zone (SVZ) into the lesioned striatum. In the current study we determined that these cells included migratory neuroblasts and oligodendrocyte precursor cells (OPC), with the predominant response from glial cells. We attempted to override this glial response by ectopic expression of the pro-neurogenic genes Pax6 or Dlx2 in the adult rat SVZ following quinolinic acid lesioning. RV-Dlx2 over-expression stimulated repair at a previously non-neurogenic time point by enhancing neuroblast recruitment and the percentage of cells that retained a neuronal fate within the lesioned area, compared to RV-GFP controls. RV-Pax6 expression was unsuccessful at inhibiting glial fate and intriguingly, increased OPC cell numbers with no change in neuronal recruitment. These findings suggest that gene choice is important when attempting to augment endogenous repair as the lesioned environment can overcome pro-neurogenic gene expression. Dlx2 over-expression however was able to partially overcome an anti-neuronal environment and therefore is a promising candidate for further study of striatal regeneration.

  20. Vesicular glutamate transporter 2 (VGLUT2) is co-stored with PACAP in projections from the rat melanopsin-containing retinal ganglion cells

    DEFF Research Database (Denmark)

    Engelund, Anna Iversen; Fahrenkrug, Jan; Harrison, Adrian Paul;

    2010-01-01

    The retinal ganglion cell layer of the eye comprises a subtype of cells characterized by their intrinsic photosensitivity and expression of melanopsin (ipRGCs). These cells regulate a variety of non-image-forming (NIF) functions such as light entrainment of circadian rhythms, acute suppression......-localized in their projections in the suprachiasmatic nucleus, the intergeniculate leaflet, and the olivary pretectal nucleus. We conclude that there is evidence to support the use of glutamate and PACAP as neurotransmitters in NIF photoperception by rat ipRGCs, and that these neurotransmitters are co-stored and probably...

  1. Synthesis and in vitro pharmacology at AMPA and kainate preferring glutamate receptors of 4-heteroarylmethylidene glutamate analogues

    DEFF Research Database (Denmark)

    Valgeirsson, Jon; Christensen, Jeppe K; Kristensen, Anders S;

    2003-01-01

    affinity for the GluR2 subtype of AMPA receptors. As an attempt to develop new pharmacological tools for studies of GluR5 receptors, (S)-E-4-(2-thiazolylmethylene)glutamic acid (4a) was designed as a structural hybrid between 1 and 3. 4a was shown to be a potent GluR5 agonist and a high affinity ligand...

  2. RAPID DETERMINATION OF L-GLUTAMIC ACIDWITH AN ENZYME REACTOR OF L-GLUTAMIC DECARBOXYLASE IMMOBILIZED ON ION EXCHANGE RESIN

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The preparation and characterization of an immobilized L-glutamic decarboxylase (GDC)were studied This work is to develop a sensitive method for the determination of L-glutamate using a new biosensor, which consists of an enzyme column reactor of GDC immobilized on a novel ion exchange resin (carboxymethyl-copolymer of allyl dextran and N.N'-methylene-bisacrylamide CM-CADB) and ion analyzer coupled with a CO2 electrode. The conditions for the enzyme immobilization were optimized by the parameters: buffer composition and concentration, adsorption equilibration time, amount of enzyme, temperature, ionic strength and pH. The properties of the immobilized enzyme on CM-CADB were studied by investigating the initial rate of the enzyme reaction, the efffect of various parameters on the immobilized GDC activity and its stability. An immobilized GDC enzyme column reactor matched with a flow injection system-ion analyzer coupled with CO2 electrode-data collection system made up the original form of the apparatus of biosensor for determining of L-glutamate acid. The limit of detection is 1.O ×1O-5 M. The linearity response is in the range of 5 × 1O -2-5 × 1O -5 M. The equation of linear regression of the calibration curve is y= 43.3x + 181.6 (y is the milli-volt of electrical potential response, x is the logarithm of the concentration of the substrate of L-glutamate acid). The correlation coefficient equals 0.99. The coefficient of variation equals 2.7%.

  3. [The role of non-NMDA glutamate receptors in the EEG effects of chronic administration of noopept GVS-111 in awake rats].

    Science.gov (United States)

    Kovalev, G I; Vorob'ev, V V

    2002-01-01

    Participation of the non-NMDA glutamate receptor subtype in the formation of the EEG frequency spectrum was studied in wakeful rats upon a long-term (10 x 0.2 mg/kg, s.c.) administration of the nootropic dipeptide GVS-111 (noopept or N-phenylacetyl-L-prolyglycine ethylate). The EEGs were measured with electrodes implanted into somatosensor cortex regions, hippocampus, and a cannula in the lateral ventricle. The acute reactions (characteristic of nootropes) in the alpha and beta ranges of EEG exhibited inversion after the 6th injection of noopept and almost completely vanished after the 9th injection. Preliminary introduction of the non-NMDA antagonist GDEE (glutamic acid diethyl ester) in a dose of 1 mumole into the lateral ventricle restored the EEG pattern observed upon the 6th dose of GVS-111. The role of glutamate receptors in the course of a prolonged administration of nootropes, as well as the possible mechanisms accounting for a difference in the action of GVS-111 and piracetam are discussed. PMID:12596524

  4. Effects of glutamate on distortion-product otoacoustic emissions and auditory brainstem responses in guinea pigs

    Institute of Scientific and Technical Information of China (English)

    SUN Qing; SUN Jian-he; SHAN Xi-zheng; LI Xing-qi

    2008-01-01

    Objective To investigate changes in evoked potentials and structure of the guinea pig cochleae during whole cochlear perfusion with glutamate. Methods CM, CAP, DPOAE, and ABR were recorded as indicators of cochlear functions during whole cochlear perfusion. The morphology of the cochlea was studied via transmission electron microscopy. Results There were no significant changes in DPOAE amplitude before and after glutamate perfusion. CM I/O function remained nonlinear during perfusion. ABR latencies were delayed following glutamate perfusion. The average CAP threshold was elevated 35 dB SPL following glutamate perfusion.. The OHCs appeared normal, but the IHCs and afferent dendrites showed cytoplasmic blebs after glutamate perfusion. Conclusions While being a primary amino acid neurotransmitter at the synapses between hair cells and spiral ganglion neurons, excessive glutamate is neurotoxic and can destroy IHCs and spiral ganglion neurons. The technique used in this study can also be used to build an animal model of auditory neuropathy.

  5. Enzyme-based flow injection analysis system for glutamine and glutamate in mammalian cell culture media.

    Science.gov (United States)

    Mayer, C; Frauer, A; Schalkhammer, T; Pittner, F

    1999-03-01

    We present the setup of a flow injection analysis system designed for on-line monitoring of glutamate and glutamine. These amino acids represent a major energy source in mammalian cell culture. A cycling assay consisting of glutamate dehydrogenase and aspartate aminotransferase produces NADH proportional to the glutamate concentration in the sample. NADH is then measured spectrophotometrically. Glutamine is determined by conversion to glutamate which is fed into the cycling assay. The conversion of glutamine to glutamate is catalyzed by asparaginase. Asparaginase was used in place of glutaminase due to its relatively high reactivity with glutamine and a pH optimum similar to that of glutamate dehydrogenase. The enzymes were immobilized covalently to activated controlled pore glass beads and integrated into the flow injection analysis system. The application of the immobilized enzymes and the technical setup are presented in this paper.

  6. Ex vivo and in vivo neuroprotection induced by argon when given after an excitotoxic or ischemic insult.

    Directory of Open Access Journals (Sweden)

    Hélène N David

    Full Text Available In vitro studies have well established the neuroprotective action of the noble gas argon. However, only limited data from in vivo models are available, and particularly whether postexcitotoxic or postischemic argon can provide neuroprotection in vivo still remains to be demonstrated. Here, we investigated the possible neuroprotective effect of postexcitotoxic-postischemic argon both ex vivo in acute brain slices subjected to ischemia in the form of oxygen and glucose deprivation (OGD, and in vivo in rats subjected to an intrastriatal injection of N-methyl-D-aspartate (NMDA or to the occlusion of middle-cerebral artery (MCAO. We show that postexcitotoxic-postischemic argon reduces OGD-induced cell injury in brain slices, and further reduces NMDA-induced brain damage and MCAO-induced cortical brain damage in rats. Contrasting with its beneficial effect at the cortical level, we show that postischemic argon increases MCAO-induced subcortical brain damage and provides no improvement of neurologic outcome as compared to control animals. These results extend previous data on the neuroprotective action of argon. Particularly, taken together with previous in vivo data that have shown that intraischemic argon has neuroprotective action at both the cortical and subcortical level, our findings on postischemic argon suggest that this noble gas could be administered during but not after ischemia, i.e. before but not after reperfusion has occurred, in order to provide cortical neuroprotection and to avoid increasing subcortical brain damage. Also, the effects of argon are discussed as regards to the oxygen-like chemical, pharmacological, and physical properties of argon.

  7. Berberine Inhibits the Release of Glutamate in Nerve Terminals from Rat Cerebral Cortex

    OpenAIRE

    Tzu-Yu Lin; Yu-Wan Lin; Cheng-Wei Lu; Shu-Kuei Huang; Su-Jane Wang

    2013-01-01

    Berberine, an isoquinoline plant alkaloid, protects neurons against neurotoxicity. An excessive release of glutamate is considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. In this study, we investigated whether berberine could affect endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes) and explored the possible mechanism. Berberine inhibited the release of glutamate evoked by the K(+) channel blocker 4-aminopyr...

  8. Genetic variants of glutamate receptor gene family in Taiwanese Kawasaki disease children with coronary artery aneurysms

    OpenAIRE

    Lin, Ying-Ju; Chang, Jeng-Sheng; Liu, Xiang(Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, 730000, Lanzhou , China); Tsang, Hsinyi; Lin, Ting-Hsu; Liao, Chiu-Chu; Huang, Shao-Mei; Chien, Wen-Kuei; Chen, Jin-Hua; Wu, Jer-Yuarn; Chen, Chien-Hsiun; Chang, Li-Ching; Lin, Cheng-Wen; Ho, Tsung-Jung; Tsai, Fuu-Jen

    2014-01-01

    Background Patients with Kawasaki disease (KD), a pediatric systemic vasculitis, may develop coronary artery aneurysm (CAA) as a complication. To investigate the role of glutamate receptors in KD and its CAA development, we performed genetic association studies. Methods and results We examined the whole family of glutamate receptors by genetic association studies in a Taiwanese cohort of 262 KD patients. We identified glutamate receptor ionotropic, kainate 1 (GRIK1) as a novel susceptibility ...

  9. Role of nitric oxide and cyclic GMP in glutamate-induced neuronal death.

    Science.gov (United States)

    Montoliu, C; Llansola, M; Monfort, P; Corbalan, R; Fernandez-Marticorena, I; Hernandez-Viadel, M L; Felipo, V

    2001-04-01

    Glutamate is the main excitatory neurotransmitter in mammals. However, excessive activation of glutamate receptors is neurotoxic, leading to neuronal degeneration and death. In many systems, including primary cultures of cerebellar neurons, glutamate neurotoxicity is mainly mediated by excessive activation of NMDA receptors, leading to increased intracellular calcium which binds to calmodulin and activates neuronal nitric oxide synthase (NOS), increasing nitric oxide (NO) which in turn activates guanylate cyclase and increases cGMP. Inhibition of NOS prevents glutamate neurotoxicity, indicating that NO mediates glutamate-induced neuronal death in this system. NO generating agents such as SNAP also induce neuronal death. Compounds that can act as "scavengers" of NO such as Croman 6 (CR-6) prevent glutamate neurotoxicity. The role of cGMP in the mediation of glutamate neurotoxicity remains controversial. Some reports indicate that cGMP mediates glutamate neurotoxicity while others indicate that cGMP is neuroprotective. We have studied the role of cGMP in the mediation of glutamate and NO neurotoxicity in cerebellar neurons. Inhibition of soluble guanylate cyclase prevents glutamate and NO neurotoxicity. There is a good correlation between inhibition of cGMP formation and neuroprotection. Moreover 8-Br-cGMP, a cell permeable analog of cGMP, induced neuronal death. These results indicate that increased intracellular cGMP is involved in the mechanism of neurotoxicity. Inhibitors of phosphodiesterase increased extracellular but not intracellular cGMP and prevented glutamate neurotoxicity. Addition of cGMP to the medium also prevented glutamate neurotoxicity. These results are compatible with a neurotoxic effect of increased intracellular cGMP and a neuroprotective effect of increased extracellular cGMP. PMID:14715472

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

    OpenAIRE

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

    2011-01-01

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

  11. Altered vesicular glutamate transporter expression in human temporal lobe epilepsy with hippocampal sclerosis

    OpenAIRE

    Van Liefferinge, J.; Jensen, C.J.; Albertini, G.; Bentea, E.; Demuyser, T.; Merckx, E.; Aronica, E.; Smolders, I; Massie, A.

    2015-01-01

    Vesicular glutamate transporters (VGLUTs) are responsible for loading glutamate into synaptic vesicles. Altered VGLUT protein expression has been suggested to affect quantal size and glutamate release under both physiological and pathological conditions. In this study, we investigated mRNA and protein expression levels of the three VGLUT subtypes in hippocampal tissue of patients suffering from temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS), International League Against Epilepsy...

  12. Glutamate, GABA, and glutamine are synchronously upregulated in the mouse lateral septum during the postpartum period

    OpenAIRE

    Zhao, Changjiu; Gammie, Stephen C.

    2014-01-01

    Dramatic structural and functional remodeling occurs in the postpartum brain for the establishment of maternal care, which is essential for the growth and development of young offspring. Glutamate and GABA signaling are critically important in modulating multiple behavioral performances. Large scale signaling changes occur in the postpartum brain, but it is still not clear to what extent the neurotransmitters glutamate and GABA change and whether the ratio of glutamate/GABA remains balanced. ...

  13. Highly selective and stable microdisc biosensors for l-glutamate monitoring

    OpenAIRE

    Govindarajan, Sridhar; McNeil, Calum J.; Lowry, John P.; McMahon, Colm P.; O'Neill, Robert D.

    2013-01-01

    Glutamate mediates most of the excitatory synaptic transmission in the brain, and its abnormal regulation is considered a key factor underlying the appearance and progression of many neurodegenerative and psychiatric diseases. In this work, a microdisc-based amperometric biosensor for glutamate detection with highly enhanced selectivity and good stability is proposed. The biosensor utilizes the enzyme glutamate oxidase which was dip-coated onto 125 um diameter platinum discs. To i...

  14. Promotion of hexadecyltrimethyleamine bromide to the damage of Alexandrium sp. LC3 by cupric glutamate

    Institute of Scientific and Technical Information of China (English)

    LI Hao; MIAO Jin-lai; CUI Feng-xia; LI Guang-you

    2006-01-01

    The effect of hexadecyltrimethyleamine bromide (HDTMAB) on the removal of A lexandrium sp. LC3 under cupric glutamate stress was investigated. Toxic effect of cupric glutamate on A lexandrium sp. LC3 was significantly promoted in the presence of HDTMAB, especially at 3.0 cmc of HDTMAB. It was found that the sulfhydryl group content of the cell decreased, while the malonaldehyde content and membrane permeability increased when Alexandrium sp. LC3 was treated with HDTMAB and cupric glutamate complex, compared with cupric glutamate alone. The data suggest that HDTMAB might stimulate the damage of A lexandrium sp. LC3 by enhancing the membrane permeability.

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

    Directory of Open Access Journals (Sweden)

    Telma Elita Bertolin

    2011-08-01

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

  16. Effect of Propofol on Glutamate and γ-aminobutyric Acid Release from Rat Hippocampal Synaptosomes

    Institute of Scientific and Technical Information of China (English)

    SHANG You; YAO Shanglong; ZENG Yinming; LIU Hongliang; CAO Junli

    2005-01-01

    To investigate the effect of propofol on the release of glutamate and γ-aminobutyric acid (GABA) from rat hippocampal synatosomes, synaptosomes was made from hippocampus and incubated with artificial cerebrospinal fluid (aCSF). With the experiment of Ca2+-dependent release of glutamate and GABA, dihydrokainic acid (DHK) and nipectic acid were added into aCSF. For the observation of Ca2+-independent release of glutamate and GABA, no DHK, nipectic acid and Ca2+were added from aCSF. The release of glutamate and GABA were evoked by 20μmol/L veratridine or 30 mmol/L KCl. The concentration of glutamate and GABA in aCSF was measured by using high-performance liquid chromatography (HPLC). 30, 100 and 300 μmol/L propofol significantly inhibited veratridine-evoked Ca2+-dependent release of glutamate and GABA (P<0.01 or P<0.05). However, propofol showed no effect on elevated KCl-evoked Ca2+-dependent release of glutamate and GABA (P>0.05). Veratridine or elevated KCl evoked Ca2+ -independent release of glutamate and GABA was not affected significantly by propofol (P>0.05). Propofol could inhibit Ca2+-dependent release of glutamate and GABA. However, it has no effect on the Ca2+-independent release ofglutamate and GABA.

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

    Directory of Open Access Journals (Sweden)

    Andreas eBringmann

    2013-04-01

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

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    The role of glutamate as a possible mediator of neurodegeneration is well described, and the homeostasis of extracellular glutamate is considered of major importance when addressing the pathogenesis of excitatory neurodegeneration. Applying the 'indicator diffusion' method to the microdialysis......-D-aspartate was due to cellular uptake by glutamate transporters. The cell membrane permeability towards 3H-D-aspartate was reduced by approximately 98% due to THA, indicating that the cell membranes per se are highly resistant to diffusion of 3H-D-aspartate. It is concluded that the present method can be used...... in studying the capacity of the glutamate transporters in vivo....

  19. The role of malate in the synthesis of glutamate in Pisum arvense roots

    Directory of Open Access Journals (Sweden)

    Genowefa Kubik-Dorosz

    2014-02-01

    Full Text Available The in vivo and in vitro activities of NADH-dependent glutamate synthase in excised Pisum arvense roots increased several-fold under the influence of malate while pyruvate oxaloacctate. citrate and succinate inhibited this entyme. The plastids isolated from Pisum arvense root,. ahen incubated with glutamine and α-ketoglutarate, released glutamate into the medium Malate clearly stimulated this process. Albizziin (25 mM completely reduced the presence of glutamate in the incubation mixture. These results indicate that reduced pyridine nucleotides arising in P. arvense root plastids during oxidation of malic acid may constitute the indispensable source of electrons for glutamic acid synthesis.

  20. Monosodium glutamate and aspartame in perceived pain in fibromyalgia.

    Science.gov (United States)

    Vellisca, María Y; Latorre, José I

    2014-07-01

    Our aim was to assess the effect of dietary elimination of monosodium glutamate (MSG) and aspartame on perceived pain in fibromyalgia. A total of 72 female patients with fibromyalgia were randomized to discontinuation of dietary MSG and aspartame (n = 36) or waiting list (n = 36). Patients were requested to rate their pain using a seven-point scale. Comparisons between both groups showed no significant differences on pain referred during the baseline or after the elimination of dietary MSG and aspartame. The discontinuation of dietary MSG and aspartame did not improve the symptoms of fibromyalgia.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    synthesis of aspartate via pyruvate carboxylation. In the absence of glucose, lactate production from glutamate via malic enzyme was lower in GDH deficient astrocytes. In conclusions, our studies reveal that metabolism via GDH serves an important anaplerotic role by adding net carbon to the TCA cycle. A...... reduction in GDH activity seems to cause the astrocytes to up-regulate activity in pathways involved in maintaining the amount of TCA cycle intermediates such as pyruvate carboxylation as well as utilization of alternate substrates such as branched chain amino acids....

  2. Acute abdomen

    Directory of Open Access Journals (Sweden)

    Wig J

    1978-01-01

    Full Text Available 550 cases of acute abdomen have been analysed in detail includ-ing their clinical presentation and operative findings. Males are more frequently affected than females in a ratio of 3: 1. More than 45% of patients presented after 48 hours of onset of symptoms. Intestinal obstruction was the commonest cause of acute abdomen (47.6%. External hernia was responsible for 26% of cases of intestinal obstruction. Perforated peptic ulcer was the commonest cause of peritonitis in the present series (31.7% while incidence of biliary peritonitis was only 2.4%.. The clinical accuracy rate was 87%. The mortality in operated cases was high (10% while the over-all mortality rate was 7.5%.

  3. Excitotoxic lesions of the infralimbic, but not prelimbic cortex facilitate reversal of appetitive discriminative context conditioning: the role of the infralimbic cortex in context generalisation.

    Directory of Open Access Journals (Sweden)

    Rachel eAshwell

    2014-02-01

    Full Text Available The prelimbic and infralimbic regions of the rat medial prefrontal cortex (mPFC are important components of the limbic cortico-striatal circuit, receiving converging projections from the hippocampus (HPC and amygdala. Mounting evidence points to these regions having opposing roles in the regulation of the expression of contextual fear and context-induced cocaine-seeking. To investigate this functional differentiation in motivated behaviour further, this study employed a novel radial maze task previously shown to be dependent on the integrity of the hippocampus and its functional connection to the nucleus accumbens shell, to investigate the effects of selective excitotoxic lesions of the PL and IL upon the spatial contextual control over reward learning. To this end, rats were trained to develop discriminative responding towards a reward-associated discrete cue presented in three out of six spatial locations (3 arms out of 6 radial maze arms, and to avoid the same discrete cue presented in the other 3 spatial locations. Once acquired, the reward contingencies of the spatial locations were reversed, such that responding to the cue presented in a previously rewarded location is no longer rewarded. Furthermore, the acquisition of spatial learning was probed separately using conditioned place preference and the monitoring of arm selection at the beginning of each training session. Lesions of the PL transiently attenuated the acquisition of the initial cue approach training and spatial learning, while leaving reversal learning intact. In contrast, IL lesions led to a significantly superior performance of spatial context-dependent discriminative cue approach and reversal learning, in the absence of a significant preference for the new reward-associated spatial locations. These results indicate that the PL and IL have functionally dissociative, and potentially opposite roles in the regulation of spatial contextual control over appetitive learning.

  4. Neuron-microglia crosstalk up-regulates neuronal FGF-2 expression which mediates neuroprotection against excitotoxicity via JNK1/2.

    Science.gov (United States)

    Figueiredo, Catarina; Pais, Teresa F; Gomes, João R; Chatterjee, Sukalyan

    2008-10-01

    Glial cells and neurons are in constant reciprocal signalling both under physiological and neuropathological conditions. Microglial activation is often associated with neuronal death during inflammation of the CNS, although microglial cells are also known to exert a neuroprotective role. In this work, we investigated the interplay between cerebellar granule neurons (CGN) and microglia in the perspective of CGN survival to an excitotoxic stimulus, quinolinic acid (QA), a catabolite of the tryptophan degradation pathway. We observed that CGN succumb to QA challenge via extracellular signal regulated kinase 1 and 2 (ERK) activation. Our data with transgenic mice expressing the natural inhibitor of calpains, calpastatin, indicate that together with cathepsins they mediate QA-induced toxicity acting downstream of the mitogen-activated protein kinase kinase-ERK pathway. Microglial cells are not only resistant to QA but can rescue neurons from QA-mediated toxicity when they are mixed in culture with neurons or by using mixed culture-conditioned medium (MCCM). This effect is mediated via fibroblast growth factor-2 (FGF-2) present in MCCM. FGF-2 is transcriptionally up-regulated in neurons and secreted in the MCCM as a result of neuron-microglia crosstalk. The neuroprotection is associated with the retention of cathepsins in the lysosomes and with transactivation of inducible heat-shock protein 70 downstream of FGF-2. Furthermore, FGF-2 upon release by neurons activates c-jun N-terminal kinase 1 and 2 pathway which also contributes to neuronal survival. We suggest that FGF-2 plays a pivotal role in neuroprotection against QA as an outcome of neuron-microglia interaction.

  5. Genetic insights into migraine and glutamate: a protagonist driving the headache.

    Science.gov (United States)

    Gasparini, Claudia F; Smith, Robert A; Griffiths, Lyn R

    2016-08-15

    Migraine is a complex polygenic disorder that continues to be a great source of morbidity in the developed world with a prevalence of 12% in the Caucasian population. Genetic and pharmacological studies have implicated the glutamate pathway in migraine pathophysiology. Glutamate profoundly impacts brain circuits that regulate core symptom domains in a range of neuropsychiatric conditions and thus remains a "hot" target for drug discovery. Glutamate has been implicated in cortical spreading depression (CSD), the phenomenon responsible for migraine with aura and in animal models carrying FHM mutations. Genotyping case-control studies have shown an association between glutamate receptor genes, namely, GRIA1 and GRIA3 with migraine with indirect supporting evidence from GWAS. New evidence localizes PRRT2 at glutamatergic synapses and shows it affects glutamate signalling and glutamate receptor activity via interactions with GRIA1. Glutamate-system defects have also been recently implicated in a novel FHM2 ATP1A2 disease-mutation mouse model. Adding to the growing evidence neurophysiological findings support a role for glutamate in cortical excitability. In addition to the existence of multiple genes to choreograph the functions of fast-signalling glutamatergic neurons, glutamate receptor diversity and regulation is further increased by the post-translational mechanisms of RNA editing and miRNAs. Ongoing genetic studies, GWAS and meta-analysis implicate neurogenic mechanisms in migraine pathology and the first genome-wide associated locus for migraine on chromosome X. Finally, in addition to glutamate modulating therapies, the kynurenine pathway has emerged as a candidate for involvement in migraine pathophysiology. In this review we discuss recent genetic evidence and glutamate modulating therapies that bear on the hypothesis that a glutamatergic mechanism may be involved in migraine susceptibility. PMID:27423601

  6. Changes in dopamine D2 and GluR-1 glutamate receptor mRNAs in the rat brain after treatment with phencyclidine.

    Directory of Open Access Journals (Sweden)

    Tomita,Hiroaki

    1995-04-01

    Full Text Available In situ hybridization of slide-mounted brain sections from rats subjected to acute and chronic phencyclidine treatment was carried out using synthetic oligonucleotides complementary to dopamine D2-receptor and non-N-methyl-D-aspartate (NMDA glutamate-receptor-subunit (GluR-1 mRNAs. There was no significant difference in either the D2-receptor or the GluR-1 mRNA levels in any brain region of the acute phencyclidine (10 mg/kg-treated and control groups. However, chronic administration of phencyclidine (10 mg/kg/day, 14 days significantly decreased the dopamine D2-receptor mRNA level in the caudate-putamen (by 27%, P < 0.01 and significantly increased the GluR-1 mRNA level in the prefrontal cortex (by 29%, P < 0.001. These results suggest that the chronic pharmaco-behavioral effects of phencyclidine may involve expression of both dopamine- and non-NMDA glutamate-receptor mRNAs.

  7. Structural mechanism of glutamate receptor activation and desensitization.

    Science.gov (United States)

    Meyerson, Joel R; Kumar, Janesh; Chittori, Sagar; Rao, Prashant; Pierson, Jason; Bartesaghi, Alberto; Mayer, Mark L; Subramaniam, Sriram

    2014-10-16

    Ionotropic glutamate receptors are ligand-gated ion channels that mediate excitatory synaptic transmission in the vertebrate brain. To gain a better understanding of how structural changes gate ion flux across the membrane, we trapped rat AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptor subtypes in their major functional states and analysed the resulting structures using cryo-electron microscopy. We show that transition to the active state involves a 'corkscrew' motion of the receptor assembly, driven by closure of the ligand-binding domain. Desensitization is accompanied by disruption of the amino-terminal domain tetramer in AMPA, but not kainate, receptors with a two-fold to four-fold symmetry transition in the ligand-binding domains in both subtypes. The 7.6 Å structure of a desensitized kainate receptor shows how these changes accommodate channel closing. These findings integrate previous physiological, biochemical and structural analyses of glutamate receptors and provide a molecular explanation for key steps in receptor gating. PMID:25119039

  8. Stability of Poly(α-L Glutamic Acid).

    Science.gov (United States)

    Choi, Peter; Chen, Y. Z.; Prohofsky, E. W.

    1996-03-01

    For the protein to go to their folded biologically active state, it must first undergo formation of the stabilizing α-helix structure. Taking the repeating unit cells of Glutamic acid in an α-helix structure, the analysis can be made of the vibrational dynamics of the Poly(α-L Glutamic acid). The method used was mean field, modified, self-consistent phonon theory (MSPA) developed by Prohofsky et al. The modes contributing to the fluctuations of the α-helix hydrogen bonds were analyzed yielding the break down probability from the room temperature to the critical temperature Tc where the hydrogen bond probability is over 0.5. The inverse proportionality of the opening bond probability to the relaxation time τ * was then used to compare our results to ultra sonic and electric-field jump experiments. These experiments were done at temperatures ranging from 295 K to 310 K. The data obtained from these experiments agrees well with the temperature dependent MSPA open bond probabilities with correlation constant of (1.6 ± 0.1)x10e-8. Our calculation also yielded critical melting temperature of Tc=332 K.

  9. Glutamate dehydrogenase: structure, allosteric regulation, and role in insulin homeostasis.

    Science.gov (United States)

    Li, Ming; Li, Changhong; Allen, Aron; Stanley, Charles A; Smith, Thomas J

    2014-01-01

    Glutamate dehydrogenase (GDH) is a homohexameric enzyme that catalyzes the reversible oxidative deamination of L-glutamate to 2-oxoglutarate. Only in the animal kingdom is this enzyme heavily allosterically regulated by a wide array of metabolites. The major activators are ADP and leucine and inhibitors include GTP, palmitoyl CoA, and ATP. Spontaneous mutations in the GTP inhibitory site that lead to the hyperinsulinism/hyperammonemia (HHS) syndrome have shed light as to why mammalian GDH is so tightly regulated. Patients with HHS exhibit hypersecretion of insulin upon consumption of protein and concomitantly extremely high levels of ammonium in the serum. The atomic structures of four new inhibitors complexed with GDH complexes have identified three different allosteric binding sites. Using a transgenic mouse model expressing the human HHS form of GDH, at least three of these compounds blocked the dysregulated form of GDH in pancreatic tissue. EGCG from green tea prevented the hyper-response to amino acids in whole animals and improved basal serum glucose levels. The atomic structure of the ECG-GDH complex and mutagenesis studies is directing structure-based drug design using these polyphenols as a base scaffold. In addition, all of these allosteric inhibitors are elucidating the atomic mechanisms of allostery in this complex enzyme.

  10. The structure and allosteric regulation of mammalian glutamate dehydrogenase.

    Science.gov (United States)

    Li, Ming; Li, Changhong; Allen, Aron; Stanley, Charles A; Smith, Thomas J

    2012-03-15

    Glutamate dehydrogenase (GDH) is a homohexameric enzyme that catalyzes the reversible oxidative deamination of l-glutamate to 2-oxoglutarate. Only in the animal kingdom is this enzyme heavily allosterically regulated by a wide array of metabolites. The major activators are ADP and leucine, while the most important inhibitors include GTP, palmitoyl CoA, and ATP. Recently, spontaneous mutations in the GTP inhibitory site that lead to the hyperinsulinism/hyperammonemia (HHS) syndrome have shed light as to why mammalian GDH is so tightly regulated. Patients with HHS exhibit hypersecretion of insulin upon consumption of protein and concomitantly extremely high levels of ammonium in the serum. The atomic structures of four new inhibitors complexed with GDH complexes have identified three different allosteric binding sites. Using a transgenic mouse model expressing the human HHS form of GDH, at least three of these compounds were found to block the dysregulated form of GDH in pancreatic tissue. EGCG from green tea prevented the hyper-response to amino acids in whole animals and improved basal serum glucose levels. The atomic structure of the ECG-GDH complex and mutagenesis studies is directing structure-based drug design using these polyphenols as a base scaffold. In addition, all of these allosteric inhibitors are elucidating the atomic mechanisms of allostery in this complex enzyme.

  11. Dopamine-glutamate interactions in the basal ganglia.

    Science.gov (United States)

    Schmidt, W J

    1998-01-01

    In an attempt to formulate a working hypothesis of basal-ganglia functions, arguments are considered suggesting that the basal ganglia are involved in a process of response selection i.e. in the facilitation of "wanted" and in the suppression of "unwanted" behaviour. The meso-accumbal dopamine-system is considered to mediate natural and drug-induced reward and sensitization. The meso-striatal dopamine-system seems to fulfill similar functions: It may mediate reinforcement which strengthens a given behaviour when elicited subsequently, but which is not experienced as reward or hedonia. Glutamate as the transmitter of the corticofugal projections to the basal ganglia nuclei and of the subthalamic neurons is critically involved in basal ganglia functions and dysfunctions; for example Parkinson's disease can be considered to be a secondary hyperglutamatergic disease. Additionally, glutamate is an essential factor in the plasticity response of the basal-ganglia. However, opposite to previous suggestions, the NMDA-receptor blocker MK-801 does not prevent psychostimulant- nor morphine-induced day to day increase (sensitization) of locomotion. Also the day to day increase of haloperidol-induced catalepsy was not prevented by MK-801. PMID:9871434

  12. Metabotropic Glutamate Receptor Dependent Cortical Plasticity in Chronic Pain.

    Science.gov (United States)

    Koga, Kohei; Li, Shermaine; Zhuo, Min

    2016-01-01

    Many cortical areas play crucial roles in higher order brain functions such as pain and emotion-processing, decision-making, and cognition. Among them, anterior cingulate cortex (ACC) and insular cortex (IC) are two key areas. Glutamate mediates major excitatory transmission during long-term plasticity in both physiological and pathological conditions. Specifically related to nociceptive or pain behaviors, metabotropic glutamate subtype receptors (mGluRs) have been involved in different types of synaptic modulation and plasticity from periphery to the spinal cord. However, less is known about their functional roles in plasticity related to pain and its related behaviors within cortical regions. In this review, we first summarized previous studies of synaptic plasticity in both the ACC and IC, and discussed how mGluRs may be involved in both cortical long-term potentiation (LTP) and long-term depression (LTD)-especially in LTD. The activation of mGluRs contributes to the induction of LTD in both ACC and IC areas. The loss of LTD caused by peripheral amputation or nerve injury can be rescued by priming ACC or IC with activations of mGluR1 receptors. We also discussed the potential functional roles of mGluRs for pain-related behaviors. We propose that targeting mGluRs in the cortical areas including the ACC and IC may provide a new therapeutic strategy for the treatment of chronic pain, phantom pain or anxiety. PMID:27296638

  13. Synthetic and endogenous cannabinoids protect retinal neurons from AMPA excitotoxicity in vivo, via activation of CB1 receptors: Involvement of PI3K/Akt and MEK/ERK signaling pathways.

    Science.gov (United States)

    Kokona, Despina; Thermos, Kyriaki

    2015-07-01

    Cannabinoids have been suggested to protect retinal ganglion cells in different models of toxicity, but their effects on other retinal neurons are poorly known. We investigated the neuroprotective actions of the endocannabinoid N-arachidonoyl ethanolamine (Anandamide/AEA) and the synthetic cannabinoids R1-Methanandamide (MethAEA) and HU-210, in an in vivo retinal model of AMPA excitotoxicity, and the mechanisms involved in the neuroprotection. Sprague-Dawley rats were intravitreally injected with PBS or AMPA in the absence or presence of the cannabinoid agonists. Brain nitric oxide synthase (bNOS) and choline acetyltransferase (ChAT) immunoreactivity (IR), as well as TUNEL staining, assessed the AMPA-induced retinal amacrine cell loss and the dose-dependent neuroprotection afforded by cannabinoids. The CB1 receptor selective antagonist AM251 and the PI3K/Akt inhibitor wortmannin reversed the cannabinoid-induced neuroprotection, suggesting the involvement of CB1 receptors and the PI3K/Akt pathway in cannabinoids' actions. Experiments with the CB2 agonist JWH015 and [(3)H]CP55940 radioligand binding suggested that the CB2 receptor is not involved in the neuroprotection. AEA and HU-210 induced phosphorylation of Akt but only AEA induced phosphorylation of ERK1/2 kinases, as revealed by western blot analysis. To investigate the role of caspase-3 in the AMPA-induced cell death, the caspase-3 inhibitor Z-DEVD-FMK was co-injected with AMPA. Z-DEVD-FMK had no effect on AMPA excitotoxicity. Moreover, no difference was observed in the phosphorylation of SAPK/JNK kinases between PBS- and AMPA-treated retinas. These results suggest that endogenous and synthetic cannabinoids protect retinal amacrine neurons from AMPA excitotoxicity in vivo via a mechanism involving the CB1 receptors, and the PI3K/Akt and/or MEK/ERK1/2 signaling pathways.

  14. Adenosine A2A Receptors Modulate Acute Injury and Neuroinflammation in Brain Ischemia

    Directory of Open Access Journals (Sweden)

    Felicita Pedata

    2014-01-01

    Full Text Available The extracellular concentration of adenosine in the brain increases dramatically during ischemia. Adenosine A2A receptor is expressed in neurons and glial cells and in inflammatory cells (lymphocytes and granulocytes. Recently, adenosine A2A receptor emerged as a potential therapeutic attractive target in ischemia. Ischemia is a multifactorial pathology characterized by different events evolving in the time. After ischemia the early massive increase of extracellular glutamate is followed by activation of resident immune cells, that is, microglia, and production or activation of inflammation mediators. Proinflammatory cytokines, which upregulate cell adhesion molecules, exert an important role in promoting recruitment of leukocytes that in turn promote expansion of the inflammatory response in ischemic tissue. Protracted neuroinflammation is now recognized as the predominant mechanism of secondary brain injury progression. A2A receptors present on central cells and on blood cells account for important effects depending on the time-related evolution of the pathological condition. Evidence suggests that A2A receptor antagonists provide early protection via centrally mediated control of excessive excitotoxicity, while A2A receptor agonists provide protracted protection by controlling massive blood cell infiltration in the hours and days after ischemia. Focus on inflammatory responses provides for adenosine A2A receptor agonists a wide therapeutic time-window of hours and even days after stroke.

  15. Yokukansan, a kampo medicine, protects PC12 cells from glutamate-induced death by augmenting gene expression of cystine/glutamate antiporter system Xc-.

    Science.gov (United States)

    Kanno, Hitomi; Kawakami, Zenji; Mizoguchi, Kazushige; Ikarashi, Yasushi; Kase, Yoshio

    2014-01-01

    Effects of the kampo medicine yokukansan on gene expression of the cystine/glutamate antiporter system Xc-, which protects against glutamate-induced cytotoxicity, were examined in Pheochromocytoma cells (PC12 cells). Yokukansan inhibited glutamate-induced PC12 cell death. Similar cytoprotective effects were found in Uncaria hook. Experiments to clarify the active compounds revealed that geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook, had cytoprotective effects. These components enhanced gene expressions of system Xc- subunits xCT and 4F2hc, and also ameliorated the glutamate-induced decrease in glutathione levels. These results suggest that the cytoprotective effect of yokukansan may be attributed to geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook. PMID:25551766

  16. Yokukansan, a kampo medicine, protects PC12 cells from glutamate-induced death by augmenting gene expression of cystine/glutamate antiporter system Xc-.

    Directory of Open Access Journals (Sweden)

    Hitomi Kanno

    Full Text Available Effects of the kampo medicine yokukansan on gene expression of the cystine/glutamate antiporter system Xc-, which protects against glutamate-induced cytotoxicity, were examined in Pheochromocytoma cells (PC12 cells. Yokukansan inhibited glutamate-induced PC12 cell death. Similar cytoprotective effects were found in Uncaria hook. Experiments to clarify the active compounds revealed that geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook, had cytoprotective effects. These components enhanced gene expressions of system Xc- subunits xCT and 4F2hc, and also ameliorated the glutamate-induced decrease in glutathione levels. These results suggest that the cytoprotective effect of yokukansan may be attributed to geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook.

  17. Yokukansan, a kampo medicine, protects PC12 cells from glutamate-induced death by augmenting gene expression of cystine/glutamate antiporter system Xc-.

    Science.gov (United States)

    Kanno, Hitomi; Kawakami, Zenji; Mizoguchi, Kazushige; Ikarashi, Yasushi; Kase, Yoshio

    2014-01-01

    Effects of the kampo medicine yokukansan on gene expression of the cystine/glutamate antiporter system Xc-, which protects against glutamate-induced cytotoxicity, were examined in Pheochromocytoma cells (PC12 cells). Yokukansan inhibited glutamate-induced PC12 cell death. Similar cytoprotective effects were found in Uncaria hook. Experiments to clarify the active compounds revealed that geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook, had cytoprotective effects. These components enhanced gene expressions of system Xc- subunits xCT and 4F2hc, and also ameliorated the glutamate-induced decrease in glutathione levels. These results suggest that the cytoprotective effect of yokukansan may be attributed to geissoschizine methyl ether, hirsuteine, hirsutine, and procyanidin B1 in Uncaria hook.

  18. Cocaine challenge enhances release of neuroprotective amino acid taurine in the striatum of chronic cocaine treated rats: a microdialysis study

    OpenAIRE

    Yablonsky-Alter, Elena; Agovic, Mervan S.; Gashi, Eleonora; Lidsky, Theodore I.; Friedman, Eitan; Banerjee, Shailesh P.

    2009-01-01

    Drug addiction is a serious public health problem. There is increasing evidence on the involvement of augmented glutamatergic transmission in cocaine-induced addiction and neurotoxicity. We investigated effects of acute or chronic cocaine administration and cocaine challenge following chronic cocaine exposure on the release of excitotoxic glutamate and neuroprotective taurine in the rat striatum by microdialysis. Cocaine challenge, following withdrawal after repeated cocaine exposure markedly...

  19. Detection and transfer of the glutamate decarboxylase gene in Streptococcus thermophilus

    Science.gov (United States)

    GABA (gamma-aminobutyric acid) is generated from glutamate by the action of glutamic acid decarboxylase (GAD) and characterized by hypotensive, diuretic and tranquilizing effects in humans and animals. The production of GABA by lactic acid starter bacteria would enhance the functionality of fermen...

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

    DEFF Research Database (Denmark)

    de Turco, Elena B; Diemer, Nils Henrik; Bazan, Nicolas G;

    2002-01-01

    To define the significance of glutamate ionotropic receptors in sPLA -mediated neuronal cell death we used the NMDA receptor antagonist MK-801 and the AMPA receptor antagonist PNQX. In primary neuronal cell cultures both MK-801 and PNQX inhibited sPLA - and glutamate-induced neuronal death. [ H]A...

  1. Focal and temporal release of glutamate in the mushroom bodies improves olfactory memory in Apis mellifera.

    Science.gov (United States)

    Locatelli, Fernando; Bundrock, Gesine; Müller, Uli

    2005-12-14

    In contrast to vertebrates, the role of the neurotransmitter glutamate in learning and memory in insects has hardly been investigated. The reason is that a pharmacological characterization of insect glutamate receptors is still missing; furthermore, it is difficult to locally restrict pharmacological interventions. In this study, we overcome these problems by using locally and temporally defined photo-uncaging of glutamate to study its role in olfactory learning and memory formation in the honeybee, Apis mellifera. Uncaging glutamate in the mushroom bodies immediately after a weak training protocol induced a higher memory rate 2 d after training, mimicking the effect of a strong training protocol. Glutamate release before training does not facilitate memory formation, suggesting that glutamate mediates processes triggered by training and required for memory formation. Uncaging glutamate in the antennal lobes shows no effect on memory formation. These results provide the first direct evidence for a temporally and locally restricted function of glutamate in memory formation in honeybees and insects. PMID:16354919

  2. Effect of parenteral glutamate treatment on the localization of neurotransmitters in the mediobasal hypothalamus

    Energy Technology Data Exchange (ETDEWEB)

    Walaas, I.; Fonnum, F.

    1978-01-01

    The localization of cholinergic, aminergic and amino acid-ergic neurones in the mediobasal hypothalamus has been studied in normal rat brain and in brains where neurones in nucleus arcuatus were destroyed by repeated administration of 2 mg/g body weight monosodium glutamate to newborn animals. In normal animals acetylcholinesterase staining, choline acetyltransferase and aromatic L-amino acid decarboxylase were concentrated in the median eminence and the arcuate nucleus. Glutamate decarboxylase was concentrated at the boundary between the ventromedial and the arcuate nuclei, with lower activity in the arcuate nucleus and very low activity in the median eminence. Nucleus arcuatus contained an intermediate level of high affinity glutamate uptake. In the lesioned animals, there were significant decreases in choline acetyltransferase, acetylcholinesterase staining and glutamate decarboxylase in the median eminence, whereas choline acetyltransferase activity and acetylcholinesterase staining, but not glutamate decarboxylase activity, were decreased in nucleus arcuatus. Aromatic L-amino acid decarboxylase was unchanged in all regions studied. The high affinity uptakes of glutamate, dopamine and noradrenaline, and the endogenous amino acid levels were also unchanged in the treated animals. The results indicate the existence of acetylcholine- and GABA-containing elements in the tuberoinfundibular tract. They further indicate that the dopamine cells in the arcuate nucleus are less sensitive to the toxic effect of glutamate than other cell types, possibly because they contain less glutamate receptors.

  3. Characterization of the venom from the spider, Araneus gemma: search for a glutamate antagonist

    International Nuclear Information System (INIS)

    Venom from three spiders, Argiope aurantia, Neoscona arabesca, and Araneus gemma have been shown to inhibit the binding of L-[3H]glutamate to both GBP and synaptic membranes. The venom from Araneus gemma was shown to be the most potent of the three venoms in inhibiting the binding of L-[3H]glutamate to GBP. Therefore, Araneus gemma venom was selected for further characterization. Venom from Araneus gemma appeared to contain two factors which inhibit the binding of L-[3H]glutamate to GBP and at least one factor that inhibits L-glutamate-stimulated 35SCN flux. Factor I is thought to be L-glutamic acid, based on: (1) its similar mobility to glutamic acid in thin-layer chromatography and amino acid analysis, (2) the presence of fingerprint molecular ion peaks for glutamate in the mass spectrum for the methanol:water (17:1) extract and for the fraction from the HPLC-purification of the crude venom, and (3) its L-glutamate-like interaction with the sodium-dependent uptake system. Factor II appears to be a polypeptide, possibly 21 amino acids in length, and does not appear to contain any free amino groups or tryptophan. While the venom does not appear to contain any indoleamines, three catecholamines (epinephrine, epinine, dopamine) and one catecholamine metabolite (DOPAC) were detected

  4. Characterization of the venom from the spider, Araneus gemma: search for a glutamate antagonist

    Energy Technology Data Exchange (ETDEWEB)

    Early, S.L.

    1985-01-01

    Venom from three spiders, Argiope aurantia, Neoscona arabesca, and Araneus gemma have been shown to inhibit the binding of L-(/sup 3/H)glutamate to both GBP and synaptic membranes. The venom from Araneus gemma was shown to be the most potent of the three venoms in inhibiting the binding of L-(/sup 3/H)glutamate to GBP. Therefore, Araneus gemma venom was selected for further characterization. Venom from Araneus gemma appeared to contain two factors which inhibit the binding of L-(/sup 3/H)glutamate to GBP and at least one factor that inhibits L-glutamate-stimulated /sup 35/SCN flux. Factor I is thought to be L-glutamic acid, based on: (1) its similar mobility to glutamic acid in thin-layer chromatography and amino acid analysis, (2) the presence of fingerprint molecular ion peaks for glutamate in the mass spectrum for the methanol:water (17:1) extract and for the fraction from the HPLC-purification of the crude venom, and (3) its L-glutamate-like interaction with the sodium-dependent uptake system. Factor II appears to be a polypeptide, possibly 21 amino acids in length, and does not appear to contain any free amino groups or tryptophan. While the venom does not appear to contain any indoleamines, three catecholamines (epinephrine, epinine, dopamine) and one catecholamine metabolite (DOPAC) were detected.

  5. Determination of Enantiomeric Excess of Glutamic Acids by Lab-made Capillary Array Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Jun WANG; Kai Ying LIU; Li WANG; Ji Ling BAI

    2006-01-01

    Simulated enantiomeric excess of glutamic acid was determined by a lab-made sixteen-channel capillary array electrophoresis with confocal fluorescent rotary scanner. The experimental results indicated that the capillary array electrophoresis method can accurately determine the enantiomeric excess of glutamic acid and can be used for high-throughput screening system for combinatorial asymmetric catalysis.

  6. Regulation of the Glutamate-Glutamine Transport System by Intracellular pH in Streptococcus lactis

    NARCIS (Netherlands)

    POOLMAN, B; HELLINGWERF, KJ; KONINGS, WN

    1987-01-01

    Various methods of manipulation of the intracellular pH in Streptococcus lactis result in a unique relationship between the rate of glutamate and glutamine transport and the cytoplasmic pH. The initial rate of glutamate uptake by S. lactis cells increases more than 30-fold when the intracellular pH

  7. 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

  8. Supplementing monosodium glutamate to partial enteral nutrition slows gastric emptying in preterm pigs

    Science.gov (United States)

    Emerging evidence suggests that free glutamate may play a functional role in modulating gastroduodenal motor function. We hypothesized that supplementing monosodium glutamate (MSG) to partial enteral nutrition stimulates gastric emptying in preterm pigs. Ten-day-old preterm, parenterally fed pigs re...

  9. Biochemical and immunological changes on oral glutamate feeding in male albino rats

    Science.gov (United States)

    Kumar, D.; Bansal, Anju; Thomas, Pauline; Sairam, M.; Sharma, S. K.; Mongia, S. S.; Singh, R.; Selvamurthy, W.

    High altitude stress leads to lipid peroxidation and free radical formation which results in cell membrane damage in organs and tissues, and associated mountain diseases. This paper discusses the changes in biochemical parameters and antibody response on feeding glutamate to male albino Sprague Dawley rats under hypoxic stress. Exposure of rats to simulated hypoxia at 7576 m, for 6 h daily for 5 consecutive days, in an animal decompression chamber at 32+/-2° C resulted in an increase in plasma malondialdehyde level with a concomitant decrease in blood glutathione (reduced) level. Supplementation of glutamate orally at an optimal dose (27 mg/kg body weight) in male albino rats under hypoxia enhanced glutathione level and decreased malondialdehyde concentration significantly. Glutamate feeding improved total plasma protein and glucose levels under hypoxia. The activities of serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) and the urea level remained elevated on glutamate supplementation under hypoxia. Glutamate supplementation increased the humoral response against sheep red blood cells (antibody titre). These results indicate a possible utility of glutamate in the amelioration of hypoxia-induced oxidative stress.

  10. Conditional deletion of the glutamate transporter GLT-1 reveals that astrocytic GLT-1 protects against fatal epilepsy while neuronal GLT-1 contributes significantly to glutamate uptake into synaptosomes.

    Science.gov (United States)

    Petr, Geraldine T; Sun, Yan; Frederick, Natalie M; Zhou, Yun; Dhamne, Sameer C; Hameed, Mustafa Q; Miranda, Clive; Bedoya, Edward A; Fischer, Kathryn D; Armsen, Wencke; Wang, Jianlin; Danbolt, Niels C; Rotenberg, Alexander; Aoki, Chiye J; Rosenberg, Paul A

    2015-04-01

    GLT-1 (EAAT2; slc1a2) is the major glutamate transporter in the brain, and is predominantly expressed in astrocytes, but at lower levels also in excitatory terminals. We generated a conditional GLT-1 knock-out mouse to uncover cell-type-specific functional roles of GLT-1. Inactivation of the GLT-1 gene was achieved in either neurons or astrocytes by expression of synapsin-Cre or inducible human GFAP-CreERT2. Elimination of GLT-1 from astrocytes resulted in loss of ∼80% of GLT-1 protein and of glutamate uptake activity that could be solubilized and reconstituted in liposomes. This loss was accompanied by excess mortality, lower body weight, and seizures suggesting that astrocytic GLT-1 is of major importance. However, there was only a small (15%) reduction that did not reach significance of glutamate uptake into crude forebrain synaptosomes. In contrast, when GLT-1 was deleted in neurons, both the GLT-1 protein and glutamate uptake activity that could be solubilized and reconstituted in liposomes were virtually unaffected. These mice showed normal survival, weight gain, and no seizures. However, the synaptosomal glutamate uptake capacity (Vmax) was reduced significantly (40%). In conclusion, astrocytic GLT-1 performs critical functions required for normal weight gain, resistance to epilepsy, and survival. However, the contribution of astrocytic GLT-1 to glutamate uptake into synaptosomes is less than expected, and the contribution of neuronal GLT-1 to synaptosomal glutamate uptake is greater than expected based on their relative protein expression. These results have important implications for the interpretation of the many previous studies assessing glutamate uptake capacity by measuring synaptosomal uptake. PMID:25834045

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

    Directory of Open Access Journals (Sweden)

    Ana ePalomino

    2014-03-01

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

  12. Effect of phenylsuccinate on potassium- and ischemia-induced release of glutamate in rat hippocampus monitored by microdialysis

    DEFF Research Database (Denmark)

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

    1991-01-01

    The extracellular concentration of glutamate in rat hippocampus during physiological conditions, elevated extracellular K+ and global ischemia was followed by microdialysis and subsequent determination of glutamate by HPLC. The effect of phenylsuccinate, an inhibitor of the mitochondrial dicarbox...

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

    DEFF Research Database (Denmark)

    Kristensen, Jens; Mæng, Michael; Mortensen, Ulrik;

    2005-01-01

    OBJECTIVE: Previous experimental studies indicate that glutamine or glutamate may provide cardioprotection by improving the oxidative metabolism in myocardial ischemia. We investigated the effect of glutamine or glutamate, given during reperfusion, on resulting infarct size and hemodynamic recovery...... outcome measures were the hemodynamic variables. RESULTS: The infarct sizes as a proportion of the area at risk (mean+/-SD) were: control group, 0.64 +/- 0.19 (n = 9); glutamine group, 0.87 +/- 0.07 (p < 0.05 vs control group) (n = 8); glutamate group, 0.72 +/- 0.11 (n = 9). Glutamine increased systemic...... vascular resistance, while glutamate preserved cardiac output during infusion. CONCLUSION: Substrate supplementation with the anaplerotic precursors glutamine and glutamate is ineffective as adjunctive therapy for severe myocardial ischemia. Beneficial effects documented in less complex experimental...

  14. Detection of Glutamate and γ-aminobutyric Acid in Vitreous of Patients with Proliferative Diabetic Retinopathy

    Institute of Scientific and Technical Information of China (English)

    Juan Deng; De-Zheng Wu; Rulong Gao

    2000-01-01

    Purpose: To study the levels of glutamate and γ-aminobutyric acid (GABA) in vitreous of patients with proliferative diabetic retinopathy(PDR) and to investigate their roles in retinal ischemia.Method: Vitreous samples were collected from 25 patients (27 eyes) with PDR and 14patients ( 14 eyes) with idiopathic macular hole. Glutamate and GABA detection were performed by high-performance liquid chromatography (HPLC).Results: Patients with PDR had significantly higher concentrations of glutamate and GABA than the control group. The glutamate level has a significantly positive correlation with GABA level.Conclusion: Detection of glutamate and GABA in vitreous provides biochemical support for the mechanism and treatment of ischemic retinal damage in patients with PDR.

  15. On the Role of Glutamate in Presynaptic Development: Possible Contributions of Presynaptic NMDA Receptors

    Directory of Open Access Journals (Sweden)

    Karlie N. Fedder

    2015-12-01

    Full Text Available Proper formation and maturation of synapses during development is a crucial step in building the functional neural circuits that underlie perception and behavior. It is well established that experience modifies circuit development. Therefore, understanding how synapse formation is controlled by synaptic activity is a key question in neuroscience. In this review, we focus on the regulation of excitatory presynaptic terminal development by glutamate, the predominant excitatory neurotransmitter in the brain. We discuss the evidence that NMDA receptor activation mediates these effects of glutamate and present the hypothesis that local activation of presynaptic NMDA receptors (preNMDARs contributes to glutamate-dependent control of presynaptic development. Abnormal glutamate signaling and aberrant synapse development are both thought to contribute to the pathogenesis of a variety of neurodevelopmental disorders, including autism spectrum disorders, intellectual disability, epilepsy, anxiety, depression, and schizophrenia. Therefore, understanding how glutamate signaling and synapse development are linked is important for understanding the etiology of these diseases.

  16. The effects of combined application of inorganic Martian dust simulant and carbon dots on glutamate transport rat brain nerve terminals

    Science.gov (United States)

    Borisova, Tatiana; Krisanova, Natalia; Nazarova, Anastasiya; Borysov, Arseniy; Pastukhov, Artem; Pozdnyakova, Natalia; Dudarenko, Marina

    2016-07-01

    During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the central nervous system (Oberdorster et al., 2004). Recently, the research team of this study found the minor fractions of nanoparticles with the size ~ 50 -60 nm in Lunar and Martian dust stimulants (JSC-1a and JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin), whereas the average size of the simulants was 1 mm and 4mm, respectively (Krisanova et al., 2013). Also, the research team of this study discovered new phenomenon - the neuromodulating and neurotoxic effect of carbon nano-sized particles - Carbon dots (C-dots), originated from ash of burned carbon-containing product (Borisova et al, 2015). The aims of this study was to analyse acute effects of upgraded stimulant of inorganic Martian dust derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, carbon dots, on the key characteristic of synaptic neurotransmission. Acute administration of carbon-containing Martian dust analogue resulted in a significant decrease in transporter-mediated uptake of L-[14C]glutamate (the major excitatory neurotransmitter) by isolated rat brain nerve terminals. The ambient level of the neurotransmitter in the preparation of nerve terminals increased in the presence of carbon dot-contained Martian dust analogue. These effects were associated with action of carbon component of the upgraded Martian dust stimulant but not with its inorganic constituent.

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

    Directory of Open Access Journals (Sweden)

    Anderson Catherine B

    2010-06-01

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

  18. Molecular Determinants of Substrate Specificity in Sodium-coupled Glutamate Transporters.

    Science.gov (United States)

    Silverstein, Nechama; Ewers, David; Forrest, Lucy R; Fahlke, Christoph; Kanner, Baruch I

    2015-11-27

    Crystal structures of the archaeal homologue GltPh have provided important insights into the molecular mechanism of transport of the excitatory neurotransmitter glutamate. Whereas mammalian glutamate transporters can translocate both glutamate and aspartate, GltPh is only one capable of aspartate transport. Most of the amino acid residues that surround the aspartate substrate in the binding pocket of GltPh are highly conserved. However, in the brain transporters, Thr-352 and Met-362 of the reentrant hairpin loop 2 are replaced by the smaller Ala and Thr, respectively. Therefore, we have studied the effects of T352A and M362T on binding and transport of aspartate and glutamate by GltPh. Substrate-dependent intrinsic fluorescence changes were monitored in transporter constructs containing the L130W mutation. GltPh-L130W/T352A exhibited an ~15-fold higher apparent affinity for l-glutamate than the wild type transporter, and the M362T mutation resulted in an increased affinity of ~40-fold. An even larger increase of the apparent affinity for l-glutamate, around 130-fold higher than that of wild type, was observed with the T352A/M362T double mutant. Radioactive uptake experiments show that GltPh-T352A not only transports aspartate but also l-glutamate. Remarkably, GltPh-M362T exhibited l-aspartate but not l-glutamate transport. The double mutant retained the ability to transport l-glutamate, but its kinetic parameters were very similar to those of GltPh-T352A alone. The differential impact of mutation on binding and transport of glutamate suggests that hairpin loop 2 not only plays a role in the selection of the substrate but also in its translocation.

  19. [Acute myocarditis].

    Science.gov (United States)

    Combes, Alain

    2013-05-01

    Myocarditis is defined as inflammation of the myocardium accompanied by myocellular necrosis. Acute myocarditis must be considered in patients who present with recent onset of cardiac failure or arrhythmia. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness, parvovirus B19, human herpesvirus 6, coxsackievirus and adenovirus being the most frequently viruses responsible for the disease. Treatment of myocarditis remains largely supportive, since immunosuppression has not been proven to be beneficial for acute lymphocytic myocarditis. Trials of antiviral therapies, or immunostimulants such as interferons, suggest a potential therapeutic role but require further investigation. Lastly, early recognition of patients rapidly progressing to refractory cardiac failure and their immediate transfer to a medical-surgical center experienced in mechanical circulatory support is warranted. In this setting, ECMO should be the first-line mechanical assistance. For highly unstable patients, a Mobile Cardiac Assistance Unit, that rapidly travels to primary care hospitals with a portable ECMO system and hooks it up before refractory multiorgan failure takes hold, is the preferred option. PMID:23789482

  20. RECURRENT SEASONAL ACUTE PSYCHOSIS

    OpenAIRE

    Agarwal, Vivek

    1999-01-01

    Acute psychoses have been reported to occur more frequently in summer. This is a report of seasonal recurrence of acute psychosis in a patient. This case report emphasizes towards the biological etiology of acute psychoses.

  1. Acute kidney failure

    Science.gov (United States)

    Kidney failure; Renal failure; Renal failure - acute; ARF; Kidney injury - acute ... To prevent acute kidney failure: Health problems such as high blood pressure or diabetes should be well controlled. Avoid drugs and medicines that can cause kidney injury.

  2. Acute cerebellar ataxia

    Science.gov (United States)

    Cerebellar ataxia; Ataxia - acute cerebellar; Cerebellitis; Post-varicella acute cerebellar ataxia; PVACA ... Acute cerebellar ataxia in children, especially younger than age 3, may occur several weeks after an illness caused by a virus. ...

  3. Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases.

    Science.gov (United States)

    Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A; Jenkins, Andrew; Traynelis, Stephen F

    2015-07-01

    The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases.

  4. Cannabinoid 1 and transient receptor potential vanilloid 1 receptors discretely modulate evoked glutamate separately from spontaneous glutamate transmission.

    Science.gov (United States)

    Fawley, Jessica A; Hofmann, Mackenzie E; Andresen, Michael C

    2014-06-11

    Action potentials trigger synaptic terminals to synchronously release vesicles, but some vesicles release spontaneously. G-protein-coupled receptors (GPCRs) can modulate both of these processes. At cranial primary afferent terminals, the GPCR cannabinoid 1 (CB1) is often coexpressed with transient receptor potential vanilloid 1 (TRPV1), a nonselective cation channel present on most afferents. Here we tested whether CB1 activation modulates synchronous, action potential-evoked (eEPSCs) and/or spontaneous (sEPSCs) EPSCs at solitary tract nucleus neurons. In rat horizontal brainstem slices, activation of solitary tract (ST) primary afferents generated ST-eEPSCs that were rapidly and reversibly inhibited from most afferents by activation of CB1 with arachidonyl-2'-chloroethylamide (ACEA) or WIN 55,212-2 [R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl)(1-naphthalenyl) methanone monomethanesulfonate]. The CB1 antagonist/inverse agonist AM251 [N-1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide] blocked these responses. Despite profound depression of ST-eEPSCs during CB1 activation, sEPSCs in these same neurons were unaltered. Changes in temperature changed sEPSC frequency only from TRPV1(+) afferents (i.e., thermal sEPSC responses only occurred in TRPV1(+) afferents). CB1 activation failed to alter these thermal sEPSC responses. However, the endogenous arachidonate metabolite N-arachidonyldopamine (NADA) promiscuously activated both CB1 and TRPV1 receptors. NADA inhibited ST-eEPSCs while simultaneously increasing sEPSC frequency, and thermally triggered sEPSC increases in neurons with TRPV1(+) afferents. We found no evidence for CB1/TRPV1 interactions suggesting independent regulation of two separate vesicle pools. Together, these data demonstrate that action potential-evoked synchronous glutamate release is modulated separately from TRPV1-mediated glutamate release despite coexistence

  5. 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.

  6. Acute Myopericarditis Mimicking Acute Myocardial Infarction

    OpenAIRE

    Seval İzdeş; Neriman Defne Altıntaş; Gülin Karaaslan; Recep Uygun; Abdulkadir But

    2011-01-01

    Acute coronary syndromes among young adults are relatively low when compared with older population in the intensive care unit. Electrocardiographic abnormalities mimicking acute coronary syndromes may be caused by non-coronary syndromes and the differential diagnosis requires a detailed evaluation. We are reporting a case of myopericarditis presenting with acute ST elevation and elevated cardiac enzymes simulating acute coronary syndrome. In this case report, the literature is reviewed to dis...

  7. Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

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    Signorá Peres Konrad

    2012-10-01

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

  8. The role of glutamate signaling in the pathogenesis and treatment of obsessive-compulsive disorder.

    Science.gov (United States)

    Wu, Ke; Hanna, Gregory L; Rosenberg, David R; Arnold, Paul D

    2012-02-01

    Obsessive-compulsive disorder (OCD) is a common and often debilitating neuropsychiatric condition characterized by persistent intrusive thoughts (obsessions), repetitive ritualistic behaviors (compulsions) and excessive anxiety. While the neurobiology and etiology of OCD has not been fully elucidated, there is growing evidence that disrupted neurotransmission of glutamate within corticalstriatal-thalamocortical (CSTC) circuitry plays a role in OCD pathogenesis. This review summarizes the findings from neuroimaging, animal model, candidate gene and treatment studies in the context of glutamate signaling dysfunction in OCD. First, studies using magnetic resonance spectroscopy are reviewed demonstrating altered glutamate concentrations in the caudate and anterior cingulate cortex of patients with OCD. Second, knockout mouse models, particularly the DLGAP3 and Sltrk5 knockout mouse models, display remarkably similar phenotypes of compulsive grooming behavior associated with glutamate signaling dysfunction. Third, candidate gene studies have identified associations between variants in glutamate system genes and OCD, particularly for SLC1A1 which has been shown to be associated with OCD in five independent studies. This converging evidence for a role of glutamate in OCD has led to the development of novel treatment strategies involving glutamatergic compounds, particularly riluzole and memantine. We conclude the review by outlining a glutamate hypothesis for OCD, which we hope will inform further research into etiology and treatment for this severe neuropsychiatric condition. PMID:22024159

  9. Flux of Nitrogen-13 from L-(N-13)Glutamate in isolated myocardium

    Energy Technology Data Exchange (ETDEWEB)

    Keen, R.E.; Barrio, J.R.; Krivokapich, J.; Phelps, M.E.

    1985-05-01

    Specific activity of nitrogen-13 containing metabolites in tissue and effluent was determined following an intra-arterial bolus of non-carrier added L-(N-13)glutamate (N-13 GLU) given to isolated rabbit septa under different metabolic states which include pyruvate (2 mM), transaminase inhibition (aminooxy-acetate, AOA, 2 mM), or pyruvate with AOA superimposed on the insulin and glucose perfused septa. Six minutes after the N-13 GLU bolus administration relative tissue specific activities of glutamine, alanine, aspartate, and glutamate were approximately 3:38:52:100, respectively, in the control and pyruvate perfused septa. The lower alanine specific activity when compared with control tissue indicated that alanine output was from a pool separate from GPT alanine pools. Higher glutamate specific activity suggested that its output is from a pool(s) different than the larger intra-cellular glutamate pool(s). All interventions with AOA blocked N-13 flux through transminases altering tissue and effluent relative specific activities with increase in % N-13 and specific activities for glutamine, glutamate, ammonia, and protein concomittant with disappearance of labeled aspartate and alanine. These results indicate that N-13 distribution in myocardium after N-13 GLU administration is mainly controlled by glutamate interaction with reversible transaminases. The differences in reactant (N-13 GLU) and product specific activities are a consequence of channeling between different cytosolic and mitochondrial glutamate microcompartments.

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

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    Sang Min Lee

    2012-01-01

    Full Text Available Bee venom (BV, which is extracted from honeybees, is used in traditional Korean medical therapy. Several groups have demonstrated the anti-inflammatory effects of BV in osteoarthritis both in vivo and in vitro. Glutamate is the predominant excitatory neurotransmitter in the central nervous system (CNS. Changes in glutamate release and uptake due to alterations in the activity of glutamate transporters have been reported in many neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. To assess if BV can prevent glutamate-mediated neurotoxicity, we examined cell viability and signal transduction in glutamate-treated neuronal and microglial cells in the presence and absence of BV. We induced glutamatergic toxicity in neuronal cells and microglial cells and found that BV protected against cell death. Furthermore, BV significantly inhibited the cellular toxicity of glutamate, and pretreatment with BV altered MAP kinase activation (e.g., JNK, ERK, and p38 following exposure to glutamate. These findings suggest that treatment with BV may be helpful in reducing glutamatergic cell toxicity in neurodegenerative diseases.

  11. Circadian modulation of gene expression, but not glutamate uptake, in mouse and rat cortical astrocytes.

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    Christian Beaulé

    Full Text Available BACKGROUND: Circadian clocks control daily rhythms including sleep-wake, hormone secretion, and metabolism. These clocks are based on intracellular transcription-translation feedback loops that sustain daily oscillations of gene expression in many cell types. Mammalian astrocytes display circadian rhythms in the expression of the clock genes Period1 (Per1 and Period2 (Per2. However, a functional role for circadian oscillations in astrocytes is unknown. Because uptake of extrasynaptic glutamate depends on the presence of Per2 in astrocytes, we asked whether glutamate uptake by glia is circadian. METHODOLOGY/PRINCIPAL FINDINGS: We measured glutamate uptake, transcript and protein levels of the astrocyte-specific glutamate transporter, Glast, and the expression of Per1 and Per2 from cultured cortical astrocytes and from explants of somatosensory cortex. We found that glutamate uptake and Glast mRNA and protein expression were significantly reduced in Clock/Clock, Per2- or NPAS2-deficient glia. Uptake was augmented when the medium was supplemented with dibutyryl-cAMP or B27. Critically, glutamate uptake was not circadian in cortical astrocytes cultured from rats or mice or in cortical slices from mice. CONCLUSION/SIGNIFICANCE: We conclude that glutamate uptake levels are modulated by CLOCK, PER2, NPAS2, and the composition of the culture medium, and that uptake does not show circadian variations.

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

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    Laurent Ladepeche

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

  13. Effects of Cymbopogon citratus and Ferula assa-foetida extracts on glutamate-induced neurotoxicity.

    Science.gov (United States)

    Tayeboon, Ghazaleh S; Tavakoli, Fatemeh; Hassani, Shokoufeh; Khanavi, Mahnaz; Sabzevari, Omid; Ostad, S Nasser

    2013-10-01

    Many of CNS diseases can lead to a great quantity of release of glutamate and the extreme glutamate induces neuronal cell damage and death. Here, we wanted to investigate the effects of Cymbopogon citratus essential oil and Ferula assa-foetida extracts treatment on glutamate-induced cell damage in a primary culture of rat cerebellar granule neurons. Cerebellums were collected from 7-d rat brains and cerebellar granule neurons were obtained after 8-d culture. CGN cells were treated with C. citratus essential oil and F. assa-foetida extracts at concentration of 100 μg/ml before, after, and during exposure to 30 μM glutamate. The cellular viability was evaluated by 3-(4, 5-dimethytthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide (MTT) staining. The flow cytometry assay was used to examine cell cycle and apoptosis. MTT assay showed a glutamate-induced reduction in cellular viability while treatment with C. citratus essential oil and F. assa-foetida extracts before, during, and after exposure to glutamate was increased. Flow cytometric analysis indicated that F. assa-foetida extracts treatment significantly (p < 0.001) attenuated glutamate-induced apoptotic/necrotic cell death and the necrotic rate was decreased by C. citratus essential oil treatment compared to glutamate group, significantly (p < 0.001). The results show that C. citratus essential oil and F. assa-foetida extracts display neuroprotective effects in glutamate-induced neurotoxicity. These extracts exert antiapoptotic activity in cerebellar granule neurons due to cell cycle arrest in G0G1 phase, which explain the beneficial effects of C. citratus essential oil and F. assa-foetida extracts as therapies for neurologic disorders.

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

    Institute of Scientific and Technical Information of China (English)

    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 glutamate+MCPG group (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,respect...

  15. Avian Imc-tectal projection is mediated by acetylcholine and glutamate.

    Science.gov (United States)

    Wang, S R; Wu, G Y; Felix, D

    1995-03-27

    In the bird, biochemical and histochemical data suggest that the neurotransmitter between nucleus isthmi pars magnocellularis (Imc) and tectum is either acetylcholine or glutamate. There are, however, discrepancies regarding the functional role of acetylcholine. In the present study we investigated the action of acetylcholine and glutamate and their specific antagonists on excitatory isthmo-tectal synaptic transmission using electrophysiological and microiontophoretic techniques. The results show two different population of cells: (1) excitatory cholinergic input, blocked by atropine sulphate but not by glutamate antagonist; (2) excitatory glutamatergic input of NMDA or non-NMDA receptor type, which is blocked or reduced by CPP or CNQX but not by atropine sulphate.

  16. Passive water and urea permeability of a human Na(+)-glutamate cotransporter expressed in Xenopus oocytes

    DEFF Research Database (Denmark)

    Macaulay, Nanna; Gether, Ulrik; Klærke, Dan Arne;

    2002-01-01

    The human Na(+)-glutamate transporter (EAAT1) was expressed in Xenopus laevis oocytes. The passive water permeability, L(p), was derived from volume changes of the oocyte induced by changes in the external osmolarity. Oocytes were subjected to two-electrode voltage clamp. In the presence of Na...... similar to the K(0.5) value for glutamate activation of transport. The specific inhibitor DL-threo-beta-benzyloxyaspartate (TBOA) reduced the EAAT1-specific L(p) to 72 %. EAAT1 supported passive fluxes of [(14)C]urea and [(14)C]glycerol. The [(14)C]urea flux was increased in the presence of glutamate. The...

  17. Glutamate recognition and hydride transfer by Escherichia coli glutamyl-tRNA reductase.

    OpenAIRE

    Lüer, Corinna; Schauer, Stefan; Virus, Simone; Schubert, Wolf-Dieter; Heinz, Dirk W.; Moser, Jürgen; Jahn, Dieter

    2007-01-01

    The initial step of tetrapyrrole biosynthesis in Escherichia coli involves the NADPH-dependent reduction by glutamyl-tRNA reductase (GluTR) of tRNA-bound glutamate to glutamate-1-semialdehyde. We evaluated the contribution of the glutamate moiety of glutamyl-tRNA to substrate specificity in vitro using a range of substrates and enzyme variants. Unexpectedly, we found that tRNA(Glu) mischarged with glutamine was a substrate for purified recombinant GluTR. Similarly unexpectedly, the substituti...

  18. Evaluation of the acute and sub-acute toxicity of the ethanolic extract ofPericampylus glaucus (Lam.) Merr. in BALB/c mice

    Institute of Scientific and Technical Information of China (English)

    Muhammad Kifayatullah; Mohd. Shahimi Mustafa; Pinaki Senguptha; Md. Moklesur Rahman Sarker; Arindam Das; Sreemoy Kanti Das

    2015-01-01

    Objective: To evaluate the safety dose range of ethanolic extract from the leaves of Pericampylus glaucus(Lam.) Merr. by acute and sub-acute oral toxicity study on animal model. Methods: The acute and sub-acute toxicity study was carried out as per Organization for Economic Co-operation and Development guidelines 423 and 407. In acute toxicity study, the oral dose (300, 2 000 and 4 000 mg/kg) of tested plant extract was administered to three groups in single dose and general behavior, adverse effects and mortality were determined up to 72 h and compared to normal group. In sub-acute study, the tested crude plant extract was administered orally at doses of 600 and 1 000 mg/kg for 28 days to the two animals groups and their body weight, hematological, serum hepatic biochemical parameters were evaluated and compared to normal group by sacrificing all group animals. Results: In acute toxicity, all treated groups’ revealed neither mortality nor any significant alteration in behavior only drowsiness, sedation and lethargy were observed in two group, i.e. 2 000 and 4 000 mg/kg of the tested plant extract. In sub-acute toxicity study no change in hematological, biochemical parameter and organ body weight were observed during study compared to the normal group. The kidney function parameters [serum glutamic-oxaloacetic transaminase (aspartate transaminase), serum glutamic pyruvic transaminase (alanine transaminase)] were significantly increased following administration of tested crude plant extract (600, 1 000 mg/kg). Conclusions:The result indicates that the oral administration ofPericampylus glaucus (Lam.) Merr. extract did not produce any significant toxic effect in BALB/c mice. Hence, the extract can be utilized safely for therapeutic use in pharmaceutical formulations.

  19. Prolonged time course of glutamate-operated single channel currents in neuromuscular preparations of small crayfish and a membrane current triggered by glutamate channel gating.

    Science.gov (United States)

    Finger, W; Martin, C; Pareto, A

    1988-08-31

    Single channel currents activated by glutamate were recorded by means of the patch-clamp technique in the abdominal superficial extensor muscle and the claw opener muscle of small (1-3 months old) and large (greater than 16 months old) crayfish. It was found that in small crayfish the time course of glutamate-operated single channel currents was prolonged by a factor of about 4 in these two preparations. In the abdominal superficial extensor muscle, single channel currents activated by 5 mmol/l glutamate had a mean burst length of tau = 2-3 ms in large crayfish and a mean burst length of tau = 8-9 ms in small crayfish. In the claw opener, for large crayfish tau congruent to 0.5 ms and for small crayfish tau = 1.5-2.5 ms resulted (500 mumol/l glutamate). Moreover, single channel currents with long time courses often slowly increased their amplitudes during the open time of the channel and current amplitudes did not decline completely to the baseline after channel closing. In addition, single channel currents with relatively constant amplitude were often followed by a small increasing and decreasing membrane current. The latter results suggest that glutamate channel gating might trigger a membrane current.

  20. Distribution of Vesicular Glutamate Transporter 2 and Ionotropic Glutamate Receptors in the Auditory Ganglion and Cochlear Nuclei of Pigeons (Columba livia).

    Science.gov (United States)

    Karim, M R; Atoji, Y

    2016-02-01

    Glutamate is a principal excitatory neurotransmitter in the auditory system. Our previous studies revealed localization of glutamate receptor mRNAs in the pigeon cochlear nuclei, suggesting the existence of glutamatergic input from the auditory nerve to the brainstem. This study demonstrated localization of mRNAs for vesicular glutamate transporter 2 (vGluT2) and ionotropic glutamate receptors (AMPA, kainate and NMDA) in the auditory ganglion (AG) and cochlear nuclei (magnocellular, angular and laminar nuclei). VGluT2 mRNA was intensely expressed in AG and intensely or moderately in the cochlear nuclei. The AG and cochlear nuclei showed intense-to-moderate mRNA signals for GluA2, GluA3, GluA4, GluK4 and GluN1. These results suggest that the pigeon AG neurons receives glutamatergic input from hair cells and in turn projects to the magnocellular and angular nuclei. Glutamate may play a pivotal role in the excitatory synapse transmission in the peripheral auditory pathway of birds.

  1. Effects of glutamate decarboxylase and gamma-aminobutyric acid (GABA) transporter on the bioconversion of GABA in engineered Escherichia coli.

    Science.gov (United States)

    Le Vo, Tam Dinh; Kim, Tae Wan; Hong, Soon Ho

    2012-05-01

    Gamma-aminobutyric acid (GABA) is a non-essential amino acid and a precursor of pyrrolidone, a monomer of nylon 4. GABA can be biosynthesized through the decarboxylation of L: -glutamate by glutamate decarboxylase. In this study, the effects of glutamate decarboxylase (gadA, gadB), glutamate/GABA antiporter (gadC) and GABA aminotransferase (gabT) on GABA production were investigated in Escherichia coli. Glutamate decarboxylase was overexpressed alone or with the glutamate/GABA antiporter to enhance GABA synthesis. GABA aminotransferase, which redirects GABA into the TCA cycle, was knock-out mutated. When gadB and gadC were co-overexpressed in the gabT mutant strain, a final GABA concentration of 5.46 g/l was obtained from 10 g/l of monosodium glutamate (MSG), which corresponded to a GABA yield of 89.5%.

  2. Efficient production of gamma-aminobutyric acid using Escherichia coli by co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter.

    Science.gov (United States)

    Dung Pham, Van; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho

    2016-01-01

    Gamma-aminobutyric acid (GABA) is an important bio-product, which is used in pharmaceutical formulations, nutritional supplements, and biopolymer monomer. The traditional GABA process involves the decarboxylation of glutamate. However, the direct production of GABA from glucose is a more efficient process. To construct the recombinant strains of Escherichia coli, a novel synthetic scaffold was introduced. By carrying out the co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter, we redirected the TCA cycle flux to GABA pathway. The genetically engineered E. coli strain produced 1.08 g/L of GABA from 10 g/L of initial glucose. Thus, with the introduction of a synthetic scaffold, we increased GABA production by 2.2-fold. The final GABA concentration was increased by 21.8% by inactivating competing pathways.

  3. Pharmacological profiles of the metabotropic glutamate receptor ligands.

    Science.gov (United States)

    Naples, M A; Hampson, D R

    2001-01-01

    Metabotropic glutamate receptors (mGluRs) are a family of G-protein coupled receptors that are expressed in the central and peripheral nervous systems. The purpose of this study was to compare the ligand binding selectivity profiles of the mGluR agonist [(3)H]L-AP4 and the novel radiolabeled phenylglycine antagonist [(3)H]CPPG at all eight rat mGluR subtypes expressed in transfected human embryonic kidney cells. At a concentration of 30 nM [(3)H]L-AP4, no specific binding was detected in membranes expressing the group I receptors mGluR1a or mGluR5a, or in membranes expressing the group II mGluRs, mGluR2 and mGluR3. Among the group III mGluRs, specific [(3)H]L-AP4 binding was detected in cells expressing mGluR4a and mGluR8a but not in cells expressing mGluR6 or mGluR7a. The binding of [(3)H]CPPG showed an exceptional pattern of selectivity amongst the mGluR subtypes; at a concentration of 20 nM [(3)H]CPPG, a high level of specific binding was seen in membranes containing mGluR8a but not in any of the other mGluR subtypes. The affinity constant (K(D)) calculated for [(3)H]CPPG binding to mGluR8a was 183 nM. In competition experiments, the phosphono-substituted phenylglycine congeners including MPPG, (RS)-PPG, and unlabeled CPPG were the most potent inhibitors of [(3)H]CPPG binding while non-phosphonated compounds such as L-glutamate and MCPG were substantially less potent. These results demonstrate that [(3)H]L-AP4 and [(3)H]CPPG can be used as probes to selectively label group III mGluRs and that CPPG and related phenylglycine derivatives are useful for studying differences in the ligand recognition sites of highly homologous mGluRs. PMID:11114395

  4. Hybridization of glutamate aspartate transaminase. Investigation of subunit interaction.

    Science.gov (United States)

    Boettcher, B; Martinez-Carrion, M

    1975-10-01

    Glutamate aspartate transaminase (EC 2.6.1.1) is a dimeric enzyme with identical subunits with each active site containing pyridoxal 5'-phosphate linked via an internal Shiff's base to a lysine residue. It is not known if these sites interact during catalysis but negative cooperativity has been reported for binding of the coenzyme (Arrio-Dupont, M. (1972), Eur. J. Biochem. 30, 307). Also nonequivalence of its subunits in binding 8-anilinonaphthalene-1-sulfonate (Harris, H.E., and Bayley, P. M. (1975), Biochem. J. 145, 125), in modification of only a single tyrosine with full loss of activity (Christen, P., and Riordan, J.F. (1970), Biochemistry 9, 3025), and following modification with 5,5'-dithiobis(2-nitrobenzoic acid) (Cournil, I., and Arrio-Dupont, M. (1973), Biochemie 55, 103) has been reported. However, steady-state and transient kinetic methods as well as direct titration of the active site chromophore with substrates and substrate analogs have not revealed any cooperative phenomena (Braunstein, A. E. (1973), Enzymes, 3rd Ed. 9, 379). It was therefore decided that a more direct approach should be used to clarify the quistion of subunit interaction during the covalent phase of catalysis. To this end a hybrid method was devised in which a hybrid transaminase was prepared which contained one subunit with a functional active site while the other subunit has the internal Shiff's base reduced with NaBH4. The specific activities and amount of "actively bound" pyridoxal 5'-phosphate are both in a 2:1 ratio for the native and hybrid forms. Comparison of the steady-state kinetic properties of the hybrid and native enzyme forms shows that both forms gave parallel double reciprocal plots which is characteristic of the Ping-Pong Bi-Bi mechanism of transamination. The Km values for the substrates L-aspartic acid and alpha-ketoglutaric acid are nearly identical while the Vmax value for the hybrid is one-half the value of the native transaminase. It therefore appears that

  5. Vesicular glutamate transporter 2 is required for the respiratory and parasympathetic activation produced by optogenetic stimulation of catecholaminergic neurons in the rostral ventrolateral medulla of mice in vivo.

    Science.gov (United States)

    Abbott, Stephen B G; Holloway, Benjamin B; Viar, Kenneth E; Guyenet, Patrice G

    2014-01-01

    Catecholaminergic neurons of the rostral ventrolateral medulla (RVLM-CA neurons; C1 neurons) contribute to the sympathetic, parasympathetic and neuroendocrine responses elicited by physical stressors such as hypotension, hypoxia, hypoglycemia, and infection. Most RVLM-CA neurons express vesicular glutamate transporter (VGLUT)2, and may use glutamate as a ionotropic transmitter, but the importance of this mode of transmission in vivo is uncertain. To address this question, we genetically deleted VGLUT2 from dopamine-β-hydroxylase-expressing neurons in mice [DβH(Cre/0) ;VGLUT2(flox/flox) mice (cKO mice)]. We compared the in vivo effects of selectively stimulating RVLM-CA neurons in cKO vs. control mice (DβH(Cre/0) ), using channelrhodopsin-2 (ChR2-mCherry) optogenetics. ChR2-mCherry was expressed by similar numbers of rostral ventrolateral medulla (RVLM) neurons in each strain (~400 neurons), with identical selectivity for catecholaminergic neurons (90-99% colocalisation with tyrosine hydroxylase). RVLM-CA neurons had similar morphology and axonal projections in DβH(Cre/0) and cKO mice. Under urethane anesthesia, photostimulation produced a similar pattern of activation of presumptive ChR2-positive RVLM-CA neurons in DβH(Cre/0) and cKO mice. Photostimulation in conscious mice produced frequency-dependent respiratory activation in DβH(Cre/0) mice but no effect in cKO mice. Similarly, photostimulation under urethane anesthesia strongly activated efferent vagal nerve activity in DβH(Cre/0) mice only. Vagal responses were unaffected by α1 -adrenoreceptor blockade. In conclusion, two responses evoked by RVLM-CA neuron stimulation in vivo require the expression of VGLUT2 by these neurons, suggesting that the acute autonomic responses driven by RVLM-CA neurons are mediated by glutamate.

  6. Electrophysiological evidence for glial-subtype glutamate transporter functional expression in rat cerebellar granule neurons

    Directory of Open Access Journals (Sweden)

    Mafra R.A.

    2003-01-01

    Full Text Available A glutamate-sensitive inward current (Iglu is described in rat cerebellar granule neurons and related to a glutamate transport mechanism. We examined the features of Iglu using the patch-clamp technique. In steady-state conditions the Iglu measured 8.14 ± 1.9 pA. Iglu was identified as a voltage-dependent inward current showing a strong rectification at positive potentials. L-Glutamate activated the inward current in a dose-dependent manner, with a half-maximal effect at about 18 µM and a maximum increase of 51.2 ± 4.4%. The inward current was blocked by the presence of dihydrokainate (0.5 mM, shown by others to readily block the GLT1 isoform. We thus speculate that Iglu could be attributed to the presence of a native glutamate transporter in cerebellar granule neurons.

  7. FREE RADICAL SCAVENGING ACTIVITY OF EVOLVULUS ALSINOIDES ON GLUTAMATE INDUCED NEURODEGENERATION

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    Subramaniyan Navaneetha Krishnan

    2011-01-01

    Full Text Available The whole plant extract of evolvulus alsinoides was evaluated for its antioxidant activity in glutamate induced neurodegeneration. The extract was given orally in to two different doses (200mg/kg and 400 mg/kg for 7 days .Simultaneously rats were treated with monosodium glutamate (5mg/kg; i.p and for comparison purpose NMDA antagonist memantine (5mg/kg was used as a standard drug. Parameters under study were TBAR, SOD, Nitrates and protein. The orally administrated extracts and memantine (5mg/kg; i.p significantly decrease nitrates, TBAR levels and significantly increase the SOD levels in glutamate treated groups. But the extract and memantine did not alter protein level in glutamate treated rats

  8. Importance of Glutamate Dehydrogenase (GDH) in Clostridium difficile Colonization In Vivo

    Science.gov (United States)

    Girinathan, Brintha Parasumanna; Braun, Sterling; Sirigireddy, Apoorva Reddy; Lopez, Jose Espinola; Govind, Revathi

    2016-01-01

    Clostridium difficile is the principal cause of antibiotic-associated diarrhea. Major metabolic requirements for colonization and expansion of C. difficile after microbiota disturbance have not been fully determined. In this study, we show that glutamate utilization is important for C. difficile to establish itself in the animal gut. When the gluD gene, which codes for glutamate dehydrogenase (GDH), was disrupted, the mutant C. difficile was unable to colonize and cause disease in a hamster model. Further, from the complementation experiment it appears that extracellular GDH may be playing a role in promoting C. difficile colonization and disease progression. Quantification of free amino acids in the hamster gut during C. difficile infection showed that glutamate is among preferred amino acids utilized by C. difficile during its expansion. This study provides evidence of the importance of glutamate metabolism for C. difficile pathogenesis. PMID:27467167

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

    International Nuclear Information System (INIS)

    Corynebacterium glutamicum (ATCC 13058) was used for glutamic acid production from sugar cane molasses which contain sufficient. The addition of 5 units ml4 of penicillin G was superior in glutamic acid production (11.5 g L 4). Tweens and their saturated fatty acids were effective on the accumulation of glutamic acid in the culture medium and the maximum yield (16.6 g L4) was the addition of 5 mg ml4 Tween 40. Gamma irradiation prior to Tween-40 treatment of bacterial cells resulted in an obvious increase in glutamic acid production and it was maximum (23.72 g L4) at 0.1 k Gy exposure dose of inocula. 5 tabs

  10. Astrocytic control of biosynthesis and turnover of the neurotransmitters glutamate and GABA

    DEFF Research Database (Denmark)

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

    2013-01-01

    Glutamate and GABA are the quantitatively major neurotransmitters in the brain mediating excitatory and inhibitory signaling, respectively. These amino acids are metabolically interrelated and at the same time they are tightly coupled to the intermediary metabolism including energy homeostasis....... Astrocytes play a pivotal role in the maintenance of the neurotransmitter pools of glutamate and GABA since only these cells express pyruvate carboxylase, the enzyme required for de novo synthesis of the two amino acids. Such de novo synthesis is obligatory to compensate for catabolism of glutamate and GABA...... related to oxidative metabolism when the amino acids are used as energy substrates. This, in turn, is influenced by the extent to which the cycling of the amino acids between neurons and astrocytes may occur. This cycling is brought about by the glutamate/GABA - glutamine cycle the operation of which...

  11. L-Glutamate and its Ionotropic Receptors in the Nervous System of Cephalopods

    OpenAIRE

    Di Cosmo, A; Di Cristo, C; Messenger, JB

    2006-01-01

    In several species of cephalopod molluscs there is good evidence for the presence of L-glutamate in the central and peripheral nervous system and evidence for both classes of ionotropic receptor, AMPA/kainate and NMDA.

  12. Adsorption dynamics of L-glutamic acid copolymers at a heptane/water interface.

    Science.gov (United States)

    Beverung, C J; Radke, C J; Blanch, H W

    1998-02-16

    Random copolymers of glutamic acid (glu-ala, glu-leu, glu-phe, glu-tyr) were employed to investigate the relationship between side chain structure and peptide charge on adsorption behavior at an oil/water boundary. Adsorption of a series of glutamate copolymers at a heptane/water interface was examined by the dynamic pendant-drop method to determine interfacial tension. Incorporation of leucine or phenylalanine into a glutamate copolymer results in greater tension reduction than incorporation of alanine or tyrosine. These effects are amplified at pH values near the isoelectric point of glutamate, where macroscopic adsorbed films of glu-leu and glu-phe exhibit gel-like properties in response to interfacial area compression. Differences in interfacial tension behavior of glu-tyr and glu-phe indicate the importance of the tyrosine p-hydroxyl group on adsorption and aggregation at the oil/water interface. PMID:9540205

  13. High Resolution Mapping of Modafinil Induced Changes in Glutamate Level in Rat Brain

    OpenAIRE

    Haris, Mohammad; Singh, Anup; Cai, Kejia; Nath, Kavindra; Verma, Gaurav; Nanga, Ravi Prakash Reddy; Hariharan, Hari; Detre, John A.; Epperson, Neill; Reddy, Ravinder

    2014-01-01

    Modafinil is marketed in the United States for the treatment of narcolepsy and daytime somnolence due to shift-work or sleep apnea. Investigations of this drug in the treatment of cocaine and nicotine dependence in addition to disorders of executive function are also underway. Modafinil has been known to increase glutamate levels in rat brain models. Proton magnetic resonance spectroscopy (1HMRS) has been commonly used to detect the glutamate (Glu) changes in vivo. In this study, we used a re...

  14. Modified Electrodes for Amperometric Determination of Glucose and Glutamate Using Mediated Electron Transport

    OpenAIRE

    Harper, Alice C

    2005-01-01

    The main goal of this research was to develop an easy to prepare and sensitive biosensor that would be able to detect glutamate in solution using ionic self-assembly methods. This was accomplished by preparing an ionically-self-assembled monolayer that included an electron transport mediator and an enzyme that would generate a current proportional to the concentration of analytes in solution. Biosensors were produced for the detection of glucose and glutamate. Ferrocene poly(allylamine)...

  15. Extrasynaptic glutamate receptor activation as cellular bases for dynamic range compression in pyramidal neurons

    Directory of Open Access Journals (Sweden)

    Katerina D Oikonomou

    2012-08-01

    Full Text Available Repetitive synaptic stimulation overcomes the ability of astrocytic processes to clear glutamate from the extracellular space, allowing some dendritic segments to become submerged in a pool of glutamate. This dynamic arrangement activates extrasynaptic NMDA receptors located on dendritic shafts. We used voltage-sensitive and calcium-sensitive dyes to probe dendritic function in this glutamate-rich location. An excess of glutamate in the extrasynaptic space was achieved either by repetitive synaptic stimulation or by glutamate iontophoresis onto the dendrites of pyramidal neurons. Two successive activations of synaptic inputs produced a typical NMDA spike, whereas five successive synaptic inputs produced characteristic plateau potentials, reminiscent of cortical UP states. While NMDA spikes were coupled with brief calcium transients highly restricted to the glutamate input site, the dendritic plateau potentials were accompanied by calcium influx along the entire dendritic branch. Once initiated, the glutamate-mediated dendritic plateau potentials could not be interrupted by negative voltage pulses. Activation of extrasynaptic NMDA receptors in cellular compartments void of spines is sufficient to initiate and support plateau potentials. The only requirement for sustained depolarizing events is a surplus of free glutamate near a group of extrasynaptic receptors. Highly nonlinear dendritic spikes (plateau potentials are summed in a highly sublinear fashion at the soma, revealing the cellular bases of signal compression in cortical circuits. Extrasynaptic NMDA receptors provide pyramidal neurons with a function analogous to a dynamic range compression in audio engineering. They limit or reduce the volume of loud sounds (i.e. strong glut. inputs and amplify quiet sounds (i.e. glutamatergic inputs that barely cross the dendritic threshold for local spike initiation. Our data also explain why consecutive cortical UP states have uniform amplitudes in a

  16. Glutamate dysregulation in the trigeminal ganglion: a novel mechanism for peripheral sensitization of the craniofacial region.

    Science.gov (United States)

    Laursen, J C; Cairns, B E; Dong, X D; Kumar, U; Somvanshi, R K; Arendt-Nielsen, L; Gazerani, P

    2014-01-01

    In the trigeminal ganglion (TG), satellite glial cells (SGCs) form a functional unit with neurons. It has been proposed that SGCs participate in regulating extracellular glutamate levels and that dysfunction of this SGC capacity can impact nociceptive transmission in craniofacial pain conditions. This study investigated whether SGCs release glutamate and whether elevation of TG glutamate concentration alters response properties of trigeminal afferent fibers. Immunohistochemistry was used to assess glutamate content and the expression of excitatory amino acid transporter (EAAT)1 and EAAT2 in TG sections. SGCs contained glutamate and expressed EAAT1 and EAAT2. Potassium chloride (10 mM) was used to evoke glutamate release from cultured rat SGCs treated with the EAAT1/2 inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)ben zoyl]amino]phenyl]methoxy]-L-aspartic acid (TFB-TBOA) or control. Treatment with TFB-TBOA (1 and 10 μM) significantly reduced the glutamate concentration from 10.6 ± 1.1 to 5.8 ± 1.4 μM and 3.0 ± 0.8 μM, respectively (pTFB-TBOA, whereas mechanical sensitization was only sensitive to APV. Antidromic invasion of muscle afferent fibers by electrical stimulation of the caudal brainstem (10 Hz) or local anesthesia of the brainstem with lidocaine did not alter glutamate-induced mechanical sensitization. These findings provide a novel mechanism whereby dysfunctional trigeminal SGCs could contribute to cranial muscle tenderness in craniofacial pain conditions such as migraine headache. PMID:24144624

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

    Directory of Open Access Journals (Sweden)

    Víctor Martín Vázquez

    2014-06-01

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

  18. Glutamic acid decarboxylase isoform distribution in transgenic mouse septum: an anti-GFP immunofluorescence study.

    Science.gov (United States)

    Verimli, Ural; Sehirli, Umit S

    2016-09-01

    The septum is a basal forebrain region located between the lateral ventricles in rodents. It consists of lateral and medial divisions. Medial septal projections regulate hippocampal theta rhythm whereas lateral septal projections are involved in processes such as affective functions, memory formation, and behavioral responses. Gamma-aminobutyric acidergic neurons of the septal region possess the 65 and 67 isoforms of the enzyme glutamic acid decarboxylase. Although data on the glutamic acid decarboxylase isoform distribution in the septal region generally appears to indicate glutamic acid decarboxylase 67 dominance, different studies have given inconsistent results in this regard. The aim of this study was therefore to obtain information on the distributions of both of these glutamic acid decarboxylase isoforms in the septal region in transgenic mice. Two animal groups of glutamic acid decarboxylase-green fluorescent protein knock-in transgenic mice were utilized in the experiment. Brain sections from the region were taken for anti-green fluorescent protein immunohistochemistry in order to obtain estimated quantitative data on the number of gamma-aminobutyric acidergic neurons. Following the immunohistochemical procedures, the mean numbers of labeled cells in the lateral and medial septal nuclei were obtained for the two isoform groups. Statistical analysis yielded significant results which indicated that the 65 isoform of glutamic acid decarboxylase predominates in both lateral and medial septal nuclei (unpaired two-tailed t-test p first to reveal the dominance of glutamic acid decarboxylase isoform 65 in the septal region in glutamic acid decarboxylase-green fluorescent protein transgenic mice. PMID:26643381

  19. Biosynthetic preparation of L-[13C]- and [15N]glutamate by Brevibacterium flavum.

    OpenAIRE

    Walker, T E; London, R E

    1987-01-01

    The biosynthesis of isotopically labeled L-glutamic acid by the microorganism Brevibacterium flavum was studied with a variety of carbon-13-enriched precursors. The purpose of this study was twofold: to develop techniques for the efficient preparation of labeled L-glutamate with a variety of useful labeling patterns which can be used for other metabolic studies, and to better understand the metabolic events leading to label scrambling in these strains. B. flavum, which is used commercially fo...

  20. Glutamate Imaging (GluCEST) Lateralizes Epileptic Foci in Non-Lesional Temporal Lobe Epilepsy

    OpenAIRE

    Davis, Kathryn Adamiak; Nanga, Ravi Prakash Reddy; Das, Sandhitsu; Stephanie H Chen; Hadar, Peter N.; Pollard, John R.; Lucas, Timothy H.; Shinohara, Russell T.; Litt, Brian; Hariharan, Hari; Elliott, Mark A.; Detre, John A; Reddy, Ravinder

    2015-01-01

    When neuroimaging reveals a brain lesion, drug-resistant epilepsy patients show better outcomes after resective surgery than do the one-third of drug resistant epilepsy patients who have normal brain MRIs. We applied a glutamate imaging method, GluCEST (Glutamate Chemical Exchange Saturation Transfer), to patients with non-lesional temporal lobe epilepsy (TLE) based on conventional MRI. GluCEST correctly lateralized the temporal lobe seizure focus on visual and quantitative analysis in all pa...

  1. Decreased glial and synaptic glutamate uptake in the striatum of HIV-1 gp120 transgenic mice.

    Science.gov (United States)

    Melendez, Roberto I; Roman, Cristina; Capo-Velez, Coral M; Lasalde-Dominicci, Jose A

    2016-06-01

    The mechanisms leading to the neurocognitive deficits in humans with immunodeficiency virus type 1 (HIV-1) are not well resolved. A number of cell culture models have demonstrated that the HIV-envelope glycoprotein 120 (gp120) decreases the reuptake of glutamate, which is necessary for learning, memory, and synaptic plasticity. However, the impact of brain HIV-1 gp120 on glutamate uptake systems in vivo remains unknown. Notably, alterations in brain glutamate uptake systems are implicated in a number of neurodegenerative and neurocognitive disorders. We characterized the kinetic properties of system XAG (sodium-dependent) and systems xc- (sodium-independent) [3H]-L-glutamate uptake in the striatum and hippocampus of HIV-1 gp120 transgenic mice, an established model of HIV neuropathology. We determined the kinetic constant Vmax (maximal velocity) and Km (affinity) of both systems XAG and xc- using subcellular preparations derived from neurons and glial cells. We show significant (30-35 %) reductions in the Vmax of systems XAG and xc- in both neuronal and glial preparations derived from the striatum, but not from the hippocampus of gp120 mice relative to wild-type (WT) controls. Moreover, immunoblot analysis showed that the protein expression of glutamate transporter subtype-1 (GLT-1), the predominant brain glutamate transporter, was significantly reduced in the striatum but not in the hippocampus of gp120 mice. These extensive and region-specific deficits of glutamate uptake likely contribute to the development and/or severity of HIV-associated neurocognitive disorders. Understanding the role of striatal glutamate uptake systems in HIV-1 gp120 may advance the development of new therapeutic strategies to prevent neuronal damage and improve cognitive function in HIV patients. PMID:26567011

  2. Design of highly potent urea-based, exosite-binding inhibitors selective for glutamate carboxypeptidase II.

    Science.gov (United States)

    Tykvart, Jan; Schimer, Jiří; Jančařík, Andrej; Bařinková, Jitka; Navrátil, Václav; Starková, Jana; Šrámková, Karolína; Konvalinka, Jan; Majer, Pavel; Šácha, Pavel

    2015-05-28

    We present here a structure-aided design of inhibitors targeting the active site as well as exosites of glutamate carboxypeptidase II (GCPII), a prostate cancer marker, preparing potent and selective inhibitors that are more than 1000-fold more active toward GCPII than its closest human homologue, glutamate carboxypeptidase III (GCPIII). Additionally, we demonstrate that the prepared inhibitor conjugate can be used for sensitive and selective imaging of GCPII in mammalian cells. PMID:25923815

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    Glutamate dehydrogenase (GDH) uses ammonia to reversibly convert α-ketoglutarate to glutamate using NADP(H) and NAD(H) as cofactors. While GDH in most mammals is encoded by a single GLUD1 gene, humans and other primates have acquired a GLUD2 gene with distinct tissue expression profile. The two h...... of the kidney during systemic acidosis. The reverse could apply for conditions of local or systemic hyperammonemia or alkalosis....

  4. Curcumin Inhibits Glutamate Release from Rat Prefrontal Nerve Endings by Affecting Vesicle Mobilization

    OpenAIRE

    Shu Kuei Huang; Tzu Yu Lin; Cheng Wei Lu; Su Jane Wang

    2012-01-01

    Curcumin, one of the major constituents of Curcuma longa, has been shown to inhibit depolarization-evoked glutamate release from rat prefrontocortical nerve terminals by reducing voltage-dependent Ca2+ entry. This study showed that curcumin inhibited ionomycin-induced glutamate release and KCl-evoked FM1-43 release, suggesting that some steps after Ca2+ entry are regulated by curcumin. Furthermore, disrupting the cytoskeleton ...

  5. Diabetes changes the levels of ionotropic glutamate receptors in the rat retina

    OpenAIRE

    Santiago, Ana R.; Gaspar, Joana M.; Baptista, Filipa I.; Cristóvão, Armando J.; Santos, Paulo F.; Kamphuis, Willem; Ambrósio, António F.

    2009-01-01

    Purpose: Diabetic retinopathy (DR) is a leading cause of vision loss and blindness among adults between the age 20 to 74. Changes in ionotropic glutamate receptor subunit composition can affect retinal glutamatergic neurotransmission and, therefore, contribute to visual impairment. The purpose of this study was to investigate whether diabetes leads to changes in ionotropic glutamate receptor subunit expression at the protein and mRNA level in the rat retina. Methods: Changes in th...

  6. Acute cerebral infarction: pathophysiology and modern treatment concepts

    International Nuclear Information System (INIS)

    This review focuses on the pathophysiological changes in acute cerebral ischemia, with special emphasis on disturbances of the cerebral blood flow (CBF) and the associated penumbra concept. Alternatively, the model of peri-infarct depolarization is demonstrated. Metabolic and molecular changes caused by cerebral ischemia and reperfusion are discussed, namely energy failure, release of glutamate with an excitatoric burst, calcium influx in neurons, generation of free radicals, activation of different proteases, disturbances of protein synthesis, induction of gene expression and apoptosis, loss of membrane integrity, edema formation and microvascular disturbances. In summary, the pathophysiological changes after focal cerebral ischemia and reperfusion are most adequately described by a network of interacting different mechanisms of tissue alterations. The simple concept of a cascade of ischemic effect which would be easy to block seems to be less applicable. A time window of approximately 6 h for the acute stroke therapy is postulated on the base of the above mentioned pathophysiological changes. (orig./AJ)

  7. Neural mechanisms underlying nicotine addiction: acute positive reinforcement and withdrawal.

    Science.gov (United States)

    Watkins, S S; Koob, G F; Markou, A

    2000-02-01

    The neurobiology of nicotine addiction is reviewed within the context of neurobiological and behavioral theories postulated for other drugs of abuse. The roles of various neurotransmitter systems, including acetylcholine, dopamine, serotonin, glutamate, gamma-aminobutyric acid, and opioid peptides in acute nicotine reinforcement and withdrawal from chronic administration are examined followed by a discussion of potential neuroadaptations within these neurochemical systems that may lead to the development of nicotine dependence. The link between nicotine administration, depression and schizophrenia are also discussed. Finally, a theoretical model of the neurobiological mechanisms underlying acute nicotine withdrawal and protracted abstinence involves alterations within dopaminergic, serotonergic, and stress systems that are hypothesized to contribute to the negative affective state associated with nicotine abstinence.

  8. Glutamic acid modified fenton system for degradation of BTEX contamination

    Energy Technology Data Exchange (ETDEWEB)

    Yehia, Fatma Z.; Badawi, Abdelfatah M.; Mady, Amr H. [Department of Petrochemicals, Egyptian Petroleum Research Institute, Nasr City, Cairo (Egypt); Kandile, Nadia G. [Faculty of Women, Department of Chemistry, Ain Shams University, Heliopolis, Cairo (Egypt)

    2012-07-15

    The present study employed a modified Fenton system that aims to extend the optimum pH range towards neutral conditions for studying the oxidation of benzene, toluene, ethyl benzene, xylenes (BTEX) using glutamic acid (Glu) as an iron chelator. Addition of 20 mM Glu greatly enhanced the oxidation rate of BTEX in modified Fenton system at pH 5-7. A rapid mass destruction (>97% after 1 h) of BTEX as a water contaminant carried out in the presence of 500 mM H{sub 2}O{sub 2}, 10 mM Fe{sup 2+}, and 20 mM Glu at pH 5 could be shown. The efficiency of this modified Fenton's system for mass destruction of BTEX in contaminated water was measured to estimate the impact of the major process variables that include initial concentrations of soluble Fe, H{sub 2}O{sub 2}, Glu (as metal chelating agent), and reaction time. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Science.gov (United States)

    Jinap, Selamat; Hajeb, Parvaneh; Karim, Roslina; Norliana, Sarian; Yibadatihan, Simayi; Abdul-Kadir, Razak

    2016-01-01

    Background Excessive dietary sodium intake causes several diseases, such as hypertension, cardiovascular and renal disease, etc. Hence, reducing sodium intake has been highly recommended. In this study the effect of monosodium glutamate (MSG), as an umami substance, on saltiness and sodium reduction was investigated. Methods and Results The trained panellists were presented with basic spicy soups (curry chicken and chili chicken) containing different amounts of sodium chloride (NaCl) (0–1.2%) and MSG (0–1.2%). They tasted the optimum concentrations of NaCl and MSG for the two spicy soups and the overall acceptability were 0.8% and 0.7%, respectively. There was no significant effect of spiciness level on the saltiness and umami taste of both soups. The optimum levels of combined NaCl and MSG for overall acceptance in the chili and curry soups were 0.3% and 0.7%, respectively. The results showed that with the addition of MSG, it is possible to reduce sodium intake without changing the overall acceptability of the spicy soup. A 32.5% reduction in sodium level is made feasible by adding 0.7% MSG to the spicy soups. Conclusions This study suggests that low-sodium soups can be developed by the addition of appropriate amounts of MSG, while maintaining the acceptability of the spicy soups. It was also proven that it is feasible to reduce sodium intake by replacing NaCl with MSG. PMID:27356909

  10. Novel potent selective phenylglycine antagonists of metabotropic glutamate receptors.

    Science.gov (United States)

    Bedingfield, J S; Jane, D E; Kemp, M C; Toms, N J; Roberts, P J

    1996-08-01

    The metabotropic glutamate (mGlu) receptor antagonist properties of novel phenylglycine analogues were investigated in adult rat cortical slices (mGlu receptors negatively coupled to adenylyl cyclase), neonatal rat cortical slices and in cultured rat cerebellar granule cells (mGlu receptors coupled to phosphoinositide hydrolysis). (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG), (RS)-alpha-methyl-4-sulphonophenylglycine (MSPG), (RS)-alpha-methyl-4-tetrazolylphenylglycine (MTPG), (RS)-alpha-methyl-3-carboxymethyl-4-hydroxyphenylglycine (M3CM4HPG) and (RS)-alpha-methyl-4-hydroxy-3-phosphonomethylphenylglycine (M4H3PMPG) were demonstrated to have potent and selective effects against 10 microM L-2-amino-4-phosphonobutyrate (L-AP4)- and 0.3 microM (2S,1'S,2'S)-2-(2-carboxycyclopropyl)glycine (L-CCG-1)-mediated inhibition of forskolin-stimulated cAMP accumulation in the adult rat cortex. In contrast, these compounds demonstrated either weak or no antagonism at mGlu receptors coupled to phosphoinositide hydrolysis in either neonatal rat cortex or in cultured cerebellar granule cells. These compounds thus appear to be useful discriminatory pharmacological tools for mGlu receptors and form the basis for the further development of novel antagonists. PMID:8864696

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

    Directory of Open Access Journals (Sweden)

    Selamat Jinap

    2016-06-01

    Full Text Available Background: Excessive dietary sodium intake causes several diseases, such as hypertension, cardiovascular and renal disease, etc. Hence, reducing sodium intake has been highly recommended. In this study the effect of monosodium glutamate (MSG, as an umami substance, on saltiness and sodium reduction was investigated. Methods and Results: The trained panellists were presented with basic spicy soups (curry chicken and chili chicken containing different amounts of sodium chloride (NaCl (0–1.2% and MSG (0–1.2%. They tasted the optimum concentrations of NaCl and MSG for the two spicy soups and the overall acceptability were 0.8% and 0.7%, respectively. There was no significant effect of spiciness level on the saltiness and umami taste of both soups. The optimum levels of combined NaCl and MSG for overall acceptance in the chili and curry soups were 0.3% and 0.7%, respectively. The results showed that with the addition of MSG, it is possible to reduce sodium intake without changing the overall acceptability of the spicy soup. A 32.5% reduction in sodium level is made feasible by adding 0.7% MSG to the spicy soups. Conclusions: This study suggests that low-sodium soups can be developed by the addition of appropriate amounts of MSG, while maintaining the acceptability of the spicy soups. It was also proven that it is feasible to reduce sodium intake by replacing NaCl with MSG.

  12. Monosodium glutamate intake, dietary patterns and asthma in Chinese adults.

    Directory of Open Access Journals (Sweden)

    Zumin Shi

    Full Text Available OBJECTIVES: Emerging evidence shows that diet is related to asthma. The aim of this analysis was to investigate the association between monosodium glutamate (MSG intake, overall dietary patterns and asthma. METHODS: Data from 1486 Chinese men and women who participated in the Jiangsu Nutrition Study (JIN were analyzed. In this study, MSG intake and dietary patterns were quantitatively assessed in 2002. Information on asthma history was collected during followed-up in 2007. RESULTS: Of the sample, 1.4% reported ever having asthma. MSG intake was not positively associated with asthma. There was a significant positive association between 'traditional' (high loadings on rice, wheat flour, and vegetable food pattern and asthma. No association between 'macho' (rich in meat and alcohol, 'sweet tooth' (high loadings on cake, milk, and yoghurt 'vegetable rich' (high loadings on whole grain, fruit, and vegetable food patterns and asthma was found. Smoking and overweight were not associated with asthma in the sample. CONCLUSION: While a 'Traditional' food pattern was positively associated with asthma among Chinese adults, there was no significant association between MSG intake and asthma.

  13. Glutamate Receptor Modulation Is Restricted to Synaptic Microdomains

    Directory of Open Access Journals (Sweden)

    Gyorgy Lur

    2015-07-01

    Full Text Available A diverse array of neuromodulators governs cellular function in the prefrontal cortex (PFC via the activation of G-protein-coupled receptors (GPCRs. However, these functionally diverse signals are carried and amplified by a relatively small assortment of intracellular second messengers. Here, we examine whether two distinct Gαi-coupled neuromodulators (norepinephrine and GABA act as redundant regulators of glutamatergic synaptic transmission. Our results reveal that, within single dendritic spines of layer 5 pyramidal neurons, alpha-2 adrenergic receptors (α2Rs selectively inhibit excitatory transmission mediated by AMPA-type glutamate receptors, while type B GABA receptors (GABABRs inhibit NMDA-type receptors. We show that both modulators act via the downregulation of cAMP and PKA. However, by restricting the lifetime of active Gαi, RGS4 promotes the independent control of these two distinct target proteins. Our findings highlight a mechanism by which neuromodulatory microdomains can be established in subcellular compartments such as dendritic spines.

  14. Glutamate and GABA as rapid effectors of hypothalamic peptidergic neurons

    Directory of Open Access Journals (Sweden)

    Cornelia eSchöne

    2012-11-01

    Full Text Available Vital hypothalamic neurons regulating hunger, wakefulness, reward-seeking, and body weight are often defined by unique expression of hypothalamus-specific neuropeptides. Gene-ablation studies show that some of these peptides, notably orexin/hypocretin (hcrt/orx, are themselves critical for stable states of consciousness and metabolic health. However, neuron-ablation studies often reveal more severe phenotypes, suggesting key roles for co-expressed transmitters. Indeed, most hypothalamic neurons, including hcrt/orx cells, contain fast transmitters glutamate and GABA, as well as several neuropeptides. What are the roles and relations between different transmitters expressed by the same neuron? Here, we consider signaling codes for releasing different transmitters in relation to transmitter and receptor diversity in behaviorally-defined, widely-projecting peptidergic neurons, such as hcrt/orx cells. We then discuss latest optogenetic studies of endogenous transmitter release from defined sets of axons in situ, which suggest that recently-characterized vital peptidergic neurons (e.g. hcrt/orx, proopiomelanocortin , and agouti-related peptide cells, as well as classical modulatory neurons (e.g. dopamine and acetylcholine cells, all use fast transmitters to control their postsynaptic targets. These optogenetic insights are complemented by recent observations of behavioral deficiencies caused by genetic ablation of fast transmission from specific neuropeptidergic and aminergic neurons. Powerful and fast (millisecond-scale GABAergic and glutamatergic signaling from neurons previously considered to be primarily modulatory raises new questions about the roles of slower co-transmitters they co-express.

  15. The structure and allosteric regulation of glutamate dehydrogenase.

    Science.gov (United States)

    Li, Ming; Li, Changhong; Allen, Aron; Stanley, Charles A; Smith, Thomas J

    2011-09-01

    Glutamate dehydrogenase (GDH) has been extensively studied for more than 50 years. Of particular interest is the fact that, while considered by most to be a 'housekeeping' enzyme, the animal form of GDH is heavily regulated by a wide array of allosteric effectors and exhibits extensive inter-subunit communication. While the chemical mechanism for GDH has remained unchanged through epochs of evolution, it was not clear how or why animals needed to evolve such a finely tuned form of this enzyme. As reviewed here, recent studies have begun to elucidate these issues. Allosteric regulation first appears in the Ciliates and may have arisen to accommodate evolutionary changes in organelle function. The occurrence of allosteric regulation appears to be coincident with the formation of an 'antenna' like feature rising off the tops of the subunits that may be necessary to facilitate regulation. In animals, this regulation further evolved as GDH became integrated into a number of other regulatory pathways. In particular, mutations in GDH that abrogate GTP inhibition result in dangerously high serum levels of insulin and ammonium. Therefore, allosteric regulation of GDH plays an important role in insulin homeostasis. Finally, several compounds have been identified that block GDH-mediated insulin secretion that may be to not only find use in treating these insulin disorders but to kill tumors that require glutamine metabolism for cellular energy.

  16. The glutamate hypothesis of schizophrenia: neuroimaging and drug development.

    Science.gov (United States)

    Egerton, Alice; Stone, James M

    2012-06-01

    Over the last 50 years, evidence for central involvement of glutamatergic neurotransmission in the pathophysiology of schizophrenia has accumulated. Recent advances in neuroimaging technology now allow several components of glutamatergic neurotransmission to be assessed in the living human brain. Positron emission tomography (PET) or single photon emission tomography (SPET) in combination with select radiotracers allows visualization of glutamatergic receptors in vivo, and magnetic resonance (MR) - based techniques allow mapping of the effects of glutamatergic agents on regional brain activation, and the measurement of regional glutamate concentrations. These imaging studies have provided evidence for regional glutamatergic abnormalities in psychosis, and are beginning to describe both the evolution of these abnormalities over the course of the illness and their response to therapeutic intervention. In parallel, advances in small animal imaging and the development of animal models have provided a platform to explore the neuropathological consequences of glutamatergic abnormality, and the potential antipsychotic efficacy of novel compounds. The molecular diversity of the glutamatergic system has driven the design of several compounds targeting aspects of glutamatergic transmission, and clinical trials have yielded encouraging results. Here, we review the contribution of imaging studies to date in understanding glutamatergic abnormalities in psychosis, and discuss the potential of new glutamatergic compounds for treatment of the disorder. PMID:22283750

  17. Glutamate functions in stomatal closure in Arabidopsis and fava bean.

    Science.gov (United States)

    Yoshida, Riichiro; Mori, Izumi C; Kamizono, Nobuto; Shichiri, Yudai; Shimatani, Tetsuo; Miyata, Fumika; Honda, Kenji; Iwai, Sumio

    2016-01-01

    Guard cells are indispensable for higher plants because they control gas exchange and water balance to maintain photosynthetic activity. The signaling processes that govern their movement are controlled by several factors, such as abscisic acid (ABA), blue light, pathogen-associated molecular patterns (PAMPs), and carbon dioxide. Herein, we demonstrated that the amino acid glutamate (Glu), a well-known mammalian neurotransmitter, functions as a novel signaling molecule in stomatal closure in both Arabidopsis and fava bean (Vicia faba L.). Pharmacological and electrophysiological analyses provided important clues for the participation of Glu-receptors, Ca(2+), and protein phosphorylation during the signaling process. Genetic analyses using Arabidopsis ABA-deficient (aba2-1) and ABA-insensitive (abi1-1 and abi2-1) mutants showed that ABA is not required for Glu signaling. However, loss-of-function of the Arabidopsis gene encoding Slow Anion Channel-Associated 1 (SLAC1) and Calcium-Dependent Protein Kinase 6 (CPK6) impaired the Glu response. Moreover, T-DNA knockout mutations of the Arabidopsis Glu receptor-like gene (GLR), GLR3.5, lost their sensitivity to Glu-dependent stomatal closure. Our results strongly support functional Glu-signaling in stomatal closure and the crucial roles of GLRs in this signaling process. PMID:26586261

  18. Anti-glutamic acid decarboxylase antibody positive neurological syndromes.

    Science.gov (United States)

    Tohid, Hassaan

    2016-07-01

    A rare kind of antibody, known as anti-glutamic acid decarboxylase (GAD) autoantibody, is found in some patients. The antibody works against the GAD enzyme, which is essential in the formation of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter found in the brain. Patients found with this antibody present with motor and cognitive problems due to low levels or lack of GABA, because in the absence or low levels of GABA patients exhibit motor and cognitive symptoms. The anti-GAD antibody is found in some neurological syndromes, including stiff-person syndrome, paraneoplastic stiff-person syndrome, Miller Fisher syndrome (MFS), limbic encephalopathy, cerebellar ataxia, eye movement disorders, and epilepsy. Previously, excluding MFS, these conditions were calledhyperexcitability disorders. However, collectively, these syndromes should be known as "anti-GAD positive neurological syndromes." An important limitation of this study is that the literature is lacking on the subject, and why patients with the above mentioned neurological problems present with different symptoms has not been studied in detail. Therefore, it is recommended that more research is conducted on this subject to obtain a better and deeper understanding of these anti-GAD antibody induced neurological syndromes. PMID:27356651

  19. Chloride channel protein 2 prevents glutamate-induced apoptosis in retinal ganglion cells

    Science.gov (United States)

    Bi, Miao-Miao; Hong, Sen; Ma, Ling-Jun; Zhou, Hong-Yan; Lu, Jia; Zhao, Jing; Zheng, Ya-Juan

    2016-01-01

    Objective(s): The purpose of this study was to investigate the role of chloride channel protein 2 (ClC-2) in glutamate-induced apoptosis in the retinal ganglion cell line (RGC-5). Materials and Methods: RGC-5 cells were treated with 1 mM glutamate for 24 hr. The expression of ClC-2, Bax, and Bcl-2 was detected by western blot analysis. Cell survival and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. Caspase-3 and -9 activities were determined by a colorimetric assay. The roles of ClC-2 in glutamate-induced apoptosis were examined by using ClC-2 complementary deoxyribonucleic acid (cDNA) and small inference ribonucleic acid (RNA) transfection technology. Results: Overexpression of ClC-2 in RGC-5 cells significantly decreased glutamate-induced apoptosis and increased cell viability, whereas silencing of ClC-2 with short hairpin (sh) RNA produced opposite effects. ClC-2 overexpression increased the expression of Bcl-2, decreased the expression of Bax, and decreased caspase-3 and -9 activation in RGC-5 cells treated with glutamate, but silencing of ClC-2 produced opposite effects. Conclusion: Our data suggest that ClC-2 chloride channels might play a protective role in glutamate-induced apoptosis in retinal ganglion cells via the mitochondria-dependent apoptosis pathway. PMID:27635193

  20. Activation of muscarinic receptors inhibits glutamate-induced GSK-3β overactivation in PC12 cells

    Institute of Scientific and Technical Information of China (English)

    Ke MA; Li-min YANG; Hong-zhuan CHEN; Yang LU

    2013-01-01

    Aim:To investigate the actions of the muscarinic agonist carbachol on glutamate-induced neurotoxicity in PC12 cells,and the underlying mechanisms.Methods:PC12 cells were treated with different concentrations of glutamate for 24 or 48 h.The cell viability was measured using MTT assay,and the expression and activation of GSK-3β were detected with Western blot.β-Catenin translocation was detected using immunofluorescence.Luciferase reporter assay and real-time PCR were used to analyze the transcriptional activity of β-catenin.Results:Glutamate (1,3,and 10 mmol/L) induced PC12 cell death in a dose-dependent manner.Moreover,treatment of the cells with glutamate (1 mmol/L) caused significant overactivation of GSK-3β and prevented β-catenin translocation to the nucleus.Pretreatment with carbachol (0.01 μmol/L) blocked glutamate-induced cell death and GSK-3β overactivation,and markedly enhanced β-catenin transcriptional activity.Conclusion:Activation of muscarinic receptors exerts neuroprotection in PC12 cells by attenuating glutamate-induced GSK-3β overactivation,suggesting potential benefits of muscarinic agonists for Alzheimer's disease.