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  1. Intracellular trafficking pathways of Cx43 gap junction channels.

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    Epifantseva, Irina; Shaw, Robin M

    2017-05-30

    Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Sulforaphane counteracts aggressiveness of pancreatic cancer driven by dysregulated Cx43-mediated gap junctional intercellular communication

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    Zhang, Yiyao; Isayev, Orkhan; Heilmann, Katharina; Schoensiegel, Frank; Liu, Li; Nessling, Michelle; Richter, Karsten; Labsch, Sabrina; Nwaeburu, Clifford C.; Mattern, Juergen; Gladkich, Jury; Giese, Nathalia; Werner, Jens; Schemmer, Peter; Gross, Wolfgang; Gebhard, Martha M.; Gerhauser, Clarissa; Schaefer, Michael; Herr, Ingrid

    2014-01-01

    The extreme aggressiveness of pancreatic ductal adenocarcinoma (PDA) has been associated with blocked gap junctional intercellular communication (GJIC) and the presence of cancer stem cells (CSCs). We examined whether disturbed GJIC is responsible for a CSC phenotype in established and primary cancer cells and patient tissue of PDA using interdisciplinary methods based in physiology, cell and molecular biology, histology and epigenetics. Flux of fluorescent dyes and gemcitabine through gap junctions (GJs) was intact in less aggressive cells but not in highly malignant cells with morphological dysfunctional GJs. Among several connexins, only Cx43 was expressed on the cell surface of less aggressive and GJIC-competent cells, whereas Cx43 surface expression was absent in highly malignant, E-cadherin-negative and GJIC-incompetent cells. The levels of total Cx43 protein and Cx43 phosphorylated at Ser368 and Ser279/282 were high in normal tissue but low to absent in malignant tissue. si-RNA-mediated inhibition of Cx43 expression in GJIC-competent cells prevented GJIC and induced colony formation and the expression of stem cell-related factors. The bioactive substance sulforaphane enhanced Cx43 and E-cadherin levels, inhibited the CSC markers c-Met and CD133, improved the functional morphology of GJs and enhanced GJIC. Sulforaphane altered the phosphorylation of several kinases and their substrates and inhibition of GSK3, JNK and PKC prevented sulforaphane-induced CX43 expression. The sulforaphane-mediated expression of Cx43 was not correlated with enhanced Cx43 RNA expression, acetylated histone binding and Cx43 promoter de-methylation, suggesting that posttranslational phosphorylation is the dominant regulatory mechanism. Together, the absence of Cx43 prevents GJIC and enhances aggressiveness, whereas sulforaphane counteracts this process, and our findings highlight dietary co-treatment as a viable treatment option for PDA. PMID:24742583

  3. HPV16 E6 Controls the Gap Junction Protein Cx43 in Cervical Tumour Cells

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    Peng Sun

    2015-10-01

    Full Text Available Human papillomavirus type 16 (HPV16 causes a range of cancers including cervical and head and neck cancers. HPV E6 oncoprotein binds the cell polarity regulator hDlg (human homologue of Drosophila Discs Large. Previously we showed in vitro, and now in vivo, that hDlg also binds Connexin 43 (Cx43, a major component of gap junctions that mediate intercellular transfer of small molecules. In HPV16-positive non-tumour cervical epithelial cells (W12G Cx43 localised to the plasma membrane, while in W12T tumour cells derived from these, it relocated with hDlg into the cytoplasm. We now provide evidence that E6 regulates this cytoplasmic pool of Cx43. E6 siRNA depletion in W12T cells resulted in restoration of Cx43 and hDlg trafficking to the cell membrane. In C33a HPV-negative cervical tumour cells expressing HPV16 or 18 E6, Cx43 was located primarily in the cytoplasm, but mutation of the 18E6 C-terminal hDlg binding motif resulted in redistribution of Cx43 to the membrane. The data indicate for the first time that increased cytoplasmic E6 levels associated with malignant progression alter Cx43 trafficking and recycling to the membrane and the E6/hDlg interaction may be involved. This suggests a novel E6-associated mechanism for changes in Cx43 trafficking in cervical tumour cells.

  4. Regulation of gap junction conductance by calcineurin through Cx43 phosphorylation: implications for action potential conduction.

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    Jabr, Rita I; Hatch, Fiona S; Salvage, Samantha C; Orlowski, Alejandro; Lampe, Paul D; Fry, Christopher H

    2016-11-01

    Cardiac arrhythmias are associated with raised intracellular [Ca 2+ ] and slowed action potential conduction caused by reduced gap junction (GJ) electrical conductance (Gj). Ventricular GJs are composed of connexin proteins (Cx43), with Gj determined by Cx43 phosphorylation status. Connexin phosphorylation is an interplay between protein kinases and phosphatases but the precise pathways are unknown. We aimed to identify key Ca 2+ -dependent phosphorylation sites on Cx43 that regulate cardiac gap junction conductance and action potential conduction velocity. We investigated the role of the Ca 2+ -dependent phosphatase, calcineurin. Intracellular [Ca 2+ ] was raised in guinea-pig myocardium by a low-Na solution or increased stimulation. Conduction velocity and Gj were measured in multicellular strips. Phosphorylation of Cx43 serine residues (S365 and S368) and of the intermediary regulator I1 at threonine35 was measured by Western blot. Measurements were made in the presence and absence of inhibitors to calcineurin, I1 or protein phosphatase-1 and phosphatase-2.Raised [Ca 2 + ] i decreased Gj, reduced Cx43 phosphorylation at S365 and increased it at S368; these changes were reversed by calcineurin inhibitors. Cx43-S368 phosphorylation was reversed by the protein kinase C inhibitor chelerythrine. Raised [Ca 2+ ] i also decreased I1 phosphorylation, also prevented by calcineurin inhibitors, to increase activity of the Ca 2+ -independent phosphatase, PPI. The PP1 inhibitor, tautomycin, prevented Cx43-365 dephosphorylation, Cx43-S368 phosphorylation and Gj reduction in raised [Ca 2+ ] i . PP2A had no role. Conduction velocity was reduced by raised [Ca 2+ ] i and reversed by calcineurin inhibitors. Reduced action potential conduction and Gj in raised [Ca 2+ ] are regulated by calcineurin-dependent Cx43-S365 phosphorylation, leading to Cx43-S368 dephosphorylation. The calcineurin action is indirect, via I1 dephosphorylation and subsequent activation of PP1.

  5. Neurological manifestations of oculodentodigital dysplasia: a Cx43 channelopathy of the central nervous system?

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    Marijke eDe Bock

    2013-09-01

    Full Text Available The coordination of tissue function is mediated by gap junctions (GJs that enable direct cell-cell transfer of metabolic and electric signals. GJs are formed by connexins of which Cx43 is most widespread in the human body. In the brain, Cx43 GJs are mostly found in astroglia where they coordinate the propagation of Ca2+ waves, spatial K+ buffering and distribution of glucose. Beyond its role in direct intercellular communication, Cx43 also forms unapposed, non-junctional hemichannels in the plasma membrane of glial cells. These allow the passage of several neuro- and gliotransmitters that may, combined with downstream paracrine signaling, complement direct GJ communication among glial cells and sustain glial-neuronal signaling. Mutations in the GJA1 gene encoding Cx43 have been identified in a rare, mostly autosomal dominant syndrome called oculodentodigital dysplasia (ODDD. ODDD patients display a pleiotropic phenotype reflected by eye, hand, teeth and foot abnormalities, as well as craniofacial and bone malformations. Remarkably, neurological symptoms such as dysarthria, neurogenic bladder (manifested as urinary incontinence, spasticity or muscle weakness, ataxia, and epilepsy are other prominent features observed in ODDD patients. Over 10 mutations detected in patients diagnosed with neurological disorders are associated with altered functionality of Cx43 GJs/hemichannels, but the link between ODDD-related abnormal channel activities and neurologic phenotype is still elusive. Here, we present an overview on the nature of the mutants conveying structural and functional changes of Cx43 channels and discuss available evidence for aberrant Cx43 GJ and hemichannel function. In a final step, we examine the possibilities of how channel dysfunction may lead to some of the neurological manifestations of ODDD.

  6. Roles of Cx43 and AKAP95 in ovarian cancer tissues in G1/S phase.

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    Liu, Wenzhi; Hua, Suhang; Dai, Yue; Yuan, Yangyang; Yang, Jinghui; Deng, Jiali; Huo, Yunjie; Chen, Xiaoxuan; Teng, Bogang; Yu, Xiuyi; Zhang, Yongxing

    2015-01-01

    The purpose of this study was to investigate the expression of A-kinase anchor protein 95 (AKAP95), cell cycle protein E1 (cyclinE1) and D1 (cyclinD1), and gap junction protein connexin 43 (Cx43) in ovarian cancer tissues, the relationship between four proteins and clinicopathologic parameters, and the correlation between these proteins. The expression of proteins in 54 cases of ovarian cancer tissues was detected by immunohistochemical method. The positive expression rates of AKAP95, cyclinD1 and cyclinE1 in ovarian cancer tissues were 72.22%, 66.67% and 79.63%, respectively, which were higher than that of ovarian pericarcinoma tissues expressing as 33.33%, 25% and 8.30% (Povarian cancer tissues was 40.74%, which was lower than that of ovarian pericarcinoma tissues expressing as 75%; respectively, and the difference was statistically significant between groups (Povarian cancer tissues was related to the histologic type (P0.05). Additionally, the expression of AKAP95, Cx43 and cyclinE1 in ovarian cancer tissues showed no correlation with the degree of differentiation or the histologic type (P>0.05). Protein expressions of AKAP95, Cx43 and cyclinE1 were correlated with each other (P0.05). AKAP95, cyclinD1 and cyclinE1 play an important role in promoting the process of ovarian cancer formation. The tumor inhibitory effects of Cx43 protein on the pathogenesis of ovarian cancer were weakened. The expression of cyclinD1 in ovarian cancer tissues is related to the histologic type while it shows no correlation with the degree of differentiation. Additionally, the expression of AKAP95, Cx43 and cyclinE1 in ovarian cancer tissues shows no correlation with the degree of differentiation or the histologic type. AKAP95 expression is correlated with Cx43 and cyclinE1 expression; Cx43 expression is correlated with AKAP95, cyclinD1 and cyclinE1 expression; cyclinE1 expression is correlated with AKAP95, Cx43, cyclinD1 expression; cyclinD1 expression is correlated with Cx43 and

  7. Disruption of the Cx43/miR21 pathway leads to osteocyte apoptosis and increased osteoclastogenesis with aging.

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    Davis, Hannah M; Pacheco-Costa, Rafael; Atkinson, Emily G; Brun, Lucas R; Gortazar, Arancha R; Harris, Julia; Hiasa, Masahiro; Bolarinwa, Surajudeen A; Yoneda, Toshiyuki; Ivan, Mircea; Bruzzaniti, Angela; Bellido, Teresita; Plotkin, Lilian I

    2017-06-01

    Skeletal aging results in apoptosis of osteocytes, cells embedded in bone that control the generation/function of bone forming and resorbing cells. Aging also decreases connexin43 (Cx43) expression in bone; and osteocytic Cx43 deletion partially mimics the skeletal phenotype of old mice. Particularly, aging and Cx43 deletion increase osteocyte apoptosis, and osteoclast number and bone resorption on endocortical bone surfaces. We examined herein the molecular signaling events responsible for osteocyte apoptosis and osteoclast recruitment triggered by aging and Cx43 deficiency. Cx43-silenced MLO-Y4 osteocytic (Cx43 def ) cells undergo spontaneous cell death in culture through caspase-3 activation and exhibit increased levels of apoptosis-related genes, and only transfection of Cx43 constructs able to form gap junction channels reverses Cx43 def cell death. Cx43 def cells and bones from old mice exhibit reduced levels of the pro-survival microRNA miR21 and, consistently, increased levels of the miR21 target phosphatase and tensin homolog (PTEN) and reduced phosphorylated Akt, whereas PTEN inhibition reduces Cx43 def cell apoptosis. miR21 reduction is sufficient to induce apoptosis of Cx43-expressing cells and miR21 deletion in miR21 fl/fl bones increases apoptosis-related gene expression, whereas a miR21 mimic prevents Cx43 def cell apoptosis, demonstrating that miR21 lies downstream of Cx43. Cx43 def cells release more osteoclastogenic cytokines [receptor activator of NFκB ligand (RANKL)/high-mobility group box-1 (HMGB1)], and caspase-3 inhibition prevents RANKL/HMGB1 release and the increased osteoclastogenesis induced by conditioned media from Cx43 def cells, which is blocked by antagonizing HMGB1-RAGE interaction. These findings identify a novel Cx43/miR21/HMGB1/RANKL pathway involved in preventing osteocyte apoptosis that also controls osteoclast formation/recruitment and is impaired with aging. © 2017 The Authors. Aging Cell published by the Anatomical Society

  8. Novel Pharmacophores of Connexin43 Based on the “RXP” Series of Cx43-binding Peptides

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    Verma, Vandana; Larsen, Bjarne Due; Coombs, Wanda; Lin, Xianming; Spagnol, Gaelle; Sorgen, Paul L; Taffet, Steven M; Delmar, Mario

    2009-01-01

    Gap junction pharmacology is a nascent field. Previous studies have identified molecules that enhance intercellular communication, and may offer potential for innovative antiarrhythmic therapy. However, their specific molecular target(s) and mechanism(s) of action remain unknown. Previously, we identified a 34-amino acid peptide (RXP-E) that binds the carboxyl terminal domain of Cx43 (Cx43CT) and prevents cardiac gap junction closure and action potential propagation block. These results supported the feasibility of a peptide-based pharmacology to Cx43, but the structure of the core active element in RXP-E, an essential step for pharmacological development, remained undefined. Here, we used a combination of molecular modeling, surface plasmon resonance, nuclear magnetic resonance and patch clamp strategies to define, for the first time, a unique ensemble of pharmacophores that bind Cx43CT and prevent closure of Cx43 channels. Two particular molecules are best representatives of this family: a cyclized heptapeptide (called CyRP-71), and a linear octapeptide of sequence RRNYRRNY. These two small compounds offer the first structural platform for the design of Cx43-interacting gap junction openers. Moreover, the structure of these compounds offers an imprint of a region of Cx43CT that is fundamental to gap junction channel function. PMID:19556520

  9. The Cx43-like connexin protein Cx40.8 is differentially localized during fin ontogeny and fin regeneration.

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    Sarah V Gerhart

    Full Text Available Connexins (Cx are the subunits of gap junctions, membraneous protein channels that permit the exchange of small molecules between adjacent cells. Cx43 is required for cell proliferation in the zebrafish caudal fin. Previously, we found that a Cx43-like connexin, cx40.8, is co-expressed with cx43 in the population of proliferating cells during fin regeneration. Here we demonstrate that Cx40.8 exhibits novel differential subcellular localization in vivo, depending on the growth status of the fin. During fin ontogeny, Cx40.8 is found at the plasma membrane, but Cx40.8 is retained in the Golgi apparatus during regeneration. We next identified a 30 amino acid domain of Cx40.8 responsible for its dynamic localization. One possible explanation for the differential localization is that Cx40.8 contributes to the regulation of Cx43 in vivo, perhaps modifying channel activity during ontogenetic growth. However, we find that the voltage-gating properties of Cx40.8 are similar to Cx43. Together our findings reveal that Cx40.8 exhibits differential subcellular localization in vivo, dependent on a discrete domain in its carboxy terminus. We suggest that the dynamic localization of Cx40.8 differentially influences Cx43-dependent cell proliferation during ontogeny and regeneration.

  10. Subcellular preconditioning of stem cells: mito-Cx43 gene targeting is cytoprotective via shift of mitochondrial Bak and Bcl-xL balance.

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    Lu, Gang; Jiang, Shujia; Ashraf, Muhammad; Haider, Khawaja Husnain

    2012-05-01

    To achieve mitochondria-specific expression of connexin-43 (Cx43) transgene for mitochondrial preconditioning in stem cells to improve their survival post-transplantation during heart cell therapy. Cx43- or GFP-encoding adenoviral vectors with a mitochondrial targeting sequence were constructed for transduction of bone marrow Sca-1(+) cells (>90% transduction efficiency). Double-fluorescence immunostaining for cytochrome-c and Cx43 supported by western blotting confirmed mitochondria-specific Cx43 expression in adenoviral-mito-Cx43-transduced cells ((Cx43)Sca-1(+)). (Cx43)Sca-1(+) showed improved survival under lethal oxygen-glucose deprivation culture conditions. (Cx43)Sca-1(+) showed an increased mitochondrial Bcl-xL:Bak ratio and reduced cytochrome-c release into cytosol with concomitantly abolished caspase-3 activity. An in vivo study was performed such that 2 × 10(6) male (Cx43)Sca-1(+) or (GFP)Sca-1(+) cells were injected into a female rat model of acute myocardial infarction. DMEM-injected rats served as controls. On day 7 post-transplantation, 4.3-fold higher survival of (Cx43)Sca-1(+) cells (p targeted Cx43 expression is a novel approach to improve stem cell survival in the infarcted heart.

  11. Marine sponge depsipeptide increases gap junction length in HTC cells transfected with Cx43-GFP.

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    Rangel, Marisa; Ionta, Marisa; Cristina Pfister, Sandra; Adolpho Sant'anna Ferreira, Raphael; Maria Machado-Santelli, Glaucia

    2010-01-01

    Connexins are membrane proteins that form GJ (gap junction) channels between adjacent cells. Cx43 (connexin 43), the most widely expressed member of the connexin family, has a rapid turnover rate, and its degradation involves both the lysosomal and ubiquitin-proteasome pathway. The goal of this work was to study the effects of geodiamolides, natural peptides from marine sponge that normally are involved with microfilament disruption, on connexin assembly or degradation in the plasma membrane. HTC (hepatocarcinoma cells) expressing Cx43-GFP (green fluorescent protein) were submitted to treatment with 200 nM geodiamolides A, B, H and I for 2 and 4 h. Microfilament distribution and the presence and size of GJ plaques were evaluated by laser scanning confocal microscopy. Among the four peptides tested, only Geo H (geodiamolide H) statistically enhanced the length of GJ plaques. Geodiamolide A also showed activity in the GJ plaque size; however, its effect was less pronounced. Treatment with Geo H could interfere with the delivery of connexins to the degradation structures, similar to proteasomal pathways, keeping the connexins assembled and accumulating GJ plaques. Further experiments, with the cells treated with Geo H, using the fungal antibiotic BFA (brefeldin A), were performed in order to uncouple events leading to GJ assembly from those related to GJ removal, since BFA is known to block protein trafficking within a fused ER (endoplasmic reticulum)/Golgi compartment. GJ plaques were drastically reduced after BFA/Geo H treatment, thus indicating that Geo H affects mainly the delivery pathway of Cx43 protein.

  12. Decreased levels of Cx43 gap junctions result in ameloblast dysregulation and enamel hypoplasia in Gja1Jrt/+ mice.

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    Toth, K; Shao, Q; Lorentz, R; Laird, D W

    2010-06-01

    Coordinated differentiation of the ameloblast cell layer is essential to enamel matrix protein deposition and subsequent mineralization. It has been hypothesized that this process is governed by Cx43-based gap junctional intercellular communication as oculodentodigital dysplasia (ODDD) patients harboring autosomal-dominant mutations in Cx43 exhibit enamel defects typically resulting in early adulthood tooth loss. To assess the role of Cx43 in tooth development we employ a mouse model of ODDD that harbors a G60S Cx43 mutant, Gja1(Jrt)/+, and appears to exhibit tooth abnormalities that mimic the human disease. We found that total Cx43 plaques at all stages of ameloblast differentiation, as well as within the supporting cell layers, were greatly reduced in Gja1(Jrt)/+ incisors compared to wild-type littermate controls. To characterize the Gja1(Jrt)/+ mouse tooth phenotype, mice were sacrificed prior to tooth eruption (postnatal day 7), weaning (postnatal day 21), and adulthood (2 months postnatal). A severely disorganized Gja1(Jrt)/+ mouse ameloblast layer and abnormal accumulation of amelogenin were observed at stages when the cells were active in secretion and mineralization. Differences in enamel thickness became more apparent after tooth eruption and incisor exposure to the oral cavity suggesting that enamel integrity is compromised, leading to rapid erosion. Additional analysis of incisors from mutant mice revealed that they were longer with a thicker dentin layer than their wild-type littermates, which may reflect a mechanical stress response to the depleted enamel layer. Together, these data show that reduced levels of Cx43 gap junctions result in ameloblast dysregulation, enamel hypoplasia, and secondary tissue responses. (c) 2010 Wiley-Liss, Inc.

  13. [Establishment of a two-layer cell spheroid model and its applications in colorectal tumor cell-fibroblast interactions with effect on Cx43 expression].

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    Zhao, Zhimin; Lin, Shanli; Wen, Huan; Deng, Hong

    2014-05-01

    To imitate tumor microenvironment in vivo through construction of two-layer cell spheroid as a three-dimensional tumor model, and to validate its application in the study of Cx43 expression in colorectal cancer cell-fibroblast interactions and colorectal cancer progression. The two-layer cell spheroid was constructed from SW620 colorectal cancer cells and HELF fibroblasts. The expression of Cx43 in the spheroid was detected by immunocytochemistry. The expression of Cx43 in cultured SW620 cells with or without co-cultured fibroblasts was detected by immunocytochemistry and immunofluorescence. The expression of Cx43 in colorectal cancer tissue was detected by immunohistochemistry. The spheroid showed well-defined cellular morphology and clear boundary between two cell lines.Significant expression of Cx43 was found along the boundary.SW620 cells had no expression of Cx43 when cultured alone, while the expression of Cx43 was induced upon co-culturing with fibroblasts.In the colorectal cancer tissue, expression of Cx43 was minimal in the centre of tumor in contrast to an upregulated expression at invasive front. The two-layer cell spheroid is an observable and sensitive model for cell-cell interaction for studies of tumor microenvironment.It can simulate colorectal cancer cell-fibroblast interactions through up-regulation of Cx43 expression.

  14. Beyond Gap Junction Channel Function: the Expression of Cx43 Contributes to Aldosterone-Induced Mesangial Cell Proliferation via the ERK1/2 and PKC Pathways

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    Aiqing Zhang

    2015-06-01

    Full Text Available Aims: This study aimed to explore the precise mechanism and signaling pathways of mesangial cell (MC proliferation from a new point of view considering Connexin 43 (Cx43. Methods: MC proliferation was measured by the incorporation of 3H-thymidine (3H-TdR. Cx43 was over-expressed in MC cells using lipofectamine 2000, and the expression level was tested with reverse transcription-polymerase chain reaction (RT-PCR and Western blot analyses. The gap junction channel function was explored by Lucifer Yellow scrape loading and dye transfer (SLDT, and the intracellular calcium concentrations ([Ca2+]i were characterized by confocal microscopy on cells loaded with Fura-3/AM. Results: There was an inverse correlation between Cx43 expression and MC proliferation (P0.05. Our data also showed that the mineralcorticoid receptor (MR antagonist spironolactone, ERK1/2 inhibitor PD98059 and PKC inhibitor GF109203X could attenuate the down-regulation of Cx43 expression in Aldo-induced MC proliferation; however, the PI3K inhibitor LY294002 could block MC proliferation without affecting Cx43 expression at either the mRNA or protein level. In addition, Aldo promoted MC proliferation in parallel with increasing [Ca2+]i (PConclusions: Our study provides preliminary evidence that Cx43 is an important regulator of Aldo-promoted MC proliferation. Furthermore, reduced Cx43 expression promoted MC proliferation independent of the gap junction channel function, and this process might be mediated through the ERK1/2- and PKC-dependent pathways.

  15. Keratitis-Ichthyosis-Deafness syndrome-associated Cx26 mutants produce nonfunctional gap junctions but hyperactive hemichannels when co-expressed with wild type Cx43

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    García, Isaac E.; Maripillán, Jaime; Jara, Oscar; Ceriani, Ricardo; Palacios-Muñoz, Angelina; Ramachandran, Jayalakshimi; Olivero, Pablo; Pérez-Acle, Tomás; González, Carlos; Sáez, Juan C.; Contreras, Jorge E.; Martínez, Agustín D.

    2015-01-01

    Mutations in Cx26 gene are found in most cases of human genetic deafness. Some mutations produce syndromic deafness associated with skin disorders, like Keratitis Ichthyosis Deafness syndrome (KID). Because in the human skin Cx26 is co-expressed with other connexins, like Cx43 and Cx30, and since KID syndrome is inherited as autosomal dominant condition, it is possible that KID mutations change the way Cx26 interacts with other co-expressed connexins. Indeed, some Cx26 syndromic mutations showed gap junction dominant negative effect when co-expressed with wild type connexins, including Cx26 and Cx43. The nature of these interactions and the consequences on hemichannels and gap junction channels functions remain unknown. In this study we demonstrate that syndromic mutations at the N-terminus segment of Cx26, change connexin oligomerization compatibility, allowing aberrant interactions with Cx43. Strikingly, heteromeric oligomer formed by Cx43/Cx26 (syndromic mutants) show exacerbated hemichannel activity, but nonfunctional gap junction channels; this also occurs for those Cx26 KID mutants that do not show functional homomeric hemichannels. Heterologous expression of these hyperactive heteromeric hemichannels increases cell membrane permeability, favoring ATP release and Ca2+ overload. The functional paradox produced by oligomerization of Cx43 and Cx26 KID mutants could underlie the severe syndromic phenotype in human skin. PMID:25625422

  16. Spatiotemporal changes in Cx30 and Cx43 expression during neuronal differentiation of P19 EC and NT2/D1 cells.

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    Wan, Carthur K; O'Carroll, Simon J; Kim, Sue-Ling; Green, Colin R; Nicholson, Louise F B

    2013-12-01

    While connexins (Cxs) are thought to be involved in differentiation, their expression and role has yet to be fully elucidated. We investigated the temporal expression of Cx30, Cx36 and Cx43 in two in vitro models of neuronal differentiation: human NT2/D1 and murine P19 cells, and the spatial localisation of Cx30 and Cx43 in these models. A temporal Cx43 downregulation was confirmed in both cell lines during RA-induced neuronal differentiation using RT-PCR (P neuronal doublecortin protein. RT-PCR showed Cx36 was upregulated twofold in NT2/D1 cells (P neuronal differentiation. Cx30 exhibited a transient peak in expression midway through the timecourse of differentiation increasing threefold in NT2/D1 cells (P neuronal differentiation markers. The temporal immunolabelling pattern was similar to that seen using RT-PCR. Cx43 was observed intracellularly and on cell surfaces, while Cx30 was seen as puncta. Spatially Cx43 was seen on doublecortin-negative cells, which may indicate Cx43 downregulation is requisite for differentiation in these models. Conversely, Cx30 puncta were observed on doublecortin-positive and -negative cells in NT2/D1 cells and examination of the Cx30 peak showed puncta also localized to nestin-positive cells, with few puncta on MAP2-positive cells. In P19 cells Cx30 was localized on clusters of cells surrounded by MAP2- and doublecortin-positive processes. The expression pattern of Cx30 indicates a role in neuronal differentiation; the nature of that role warrants future investigation.

  17. Changes in Cx43 and NaV1.5 expression precede the occurrence of substantial fibrosis in calcineurin-induced murine cardiac hypertrophy.

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    Magda S C Fontes

    Full Text Available In mice, the calcium-dependent phosphatase calcineurin A (CnA induces a transcriptional pathway leading to pathological cardiac hypertrophy. Interestingly, induction of CnA has been frequently noticed in human hypertrophic and failing hearts. Independently, the arrhythmia vulnerability of such hearts has been regularly associated with remodeling of parameters determining electrical conduction (expression level of connexin43 (Cx43 and NaV1.5, connective tissue architecture, for which the precise molecular basis and sequence of events is still unknown. Recently, we observed reduced Cx43 and NaV1.5 expression in 4-week old mouse hearts, overexpressing a constitutively active form of CnA (MHC-CnA model, but the order of events is still unknown. Therefore, three key parameters of conduction (Cx43, NaV1.5 and connective tissue expression were characterized in MHC-CnA ventricles versus wild-type (WT during postnatal development on a weekly basis. At postnatal week 1, CnA overexpression induced cardiac hypertrophy in MHC-CnA. Moreover, protein and RNA levels of both Cx43 and NaV1.5 were reduced by at least 50% as compared to WT. Cx43 immunoreactive signal was reduced at week 2 in MHC-CnA. At postnatal week 3, Cx43 was less phosphorylated and RNA level of Cx43 normalized to WT values, although the protein level was still reduced. Additionally, MHC-CnA hearts displayed substantial fibrosis relative to WT, which was accompanied by increased RNA levels for genes previously associated with fibrosis such as Col1a1, Col1a2, Col3a1, Tgfb1, Ctgf, Timp1 and microRNA miR-21. In MHC-CnA, reduction in Cx43 and NaV1.5 expression thus coincided with overexpression of CnA and hypertrophy development and preceded significant presence of fibrosis. At postnatal week 4 the alterations in conductional parameters observed in the MHC-CnA model lead to abnormal conduction and arrhythmias, similar to those observed in cardiac remodeling in heart failure patients. The MHC

  18. Correlations of differentially expressed gap junction connexins Cx26, Cx30, Cx32, Cx43 and Cx46 with breast cancer progression and prognosis.

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    Ivett Teleki

    Full Text Available Connexins and their cell membrane channels contribute to the control of cell proliferation and compartmental functions in breast glands and their deregulation is linked to breast carcinogenesis. Our aim was to correlate connexin expression with tumor progression and prognosis in primary breast cancers.Meta-analysis of connexin isotype expression data of 1809 and 1899 breast cancers from the Affymetrix and Illumina array platforms, respectively, was performed. Expressed connexins were also monitored at the protein level in tissue microarrays of 127 patients equally representing all tumor grades, using immunofluorescence and multilayer, multichannel digital microscopy. Prognostic correlations were plotted in Kaplan-Meier curves and tested using the log-rank test and cox-regression analysis in univariate and multivariate models.The expression of GJA1/Cx43, GJA3/Cx46 and GJB2/Cx26 and, for the first time, GJA6/Cx30 and GJB1/Cx32 was revealed both in normal human mammary glands and breast carcinomas. Within their subfamilies these connexins can form homo- and heterocellular epithelial channels. In cancer, the array datasets cross-validated each other's prognostic results. In line with the significant correlations found at mRNA level, elevated Cx43 protein levels were linked with significantly improved breast cancer outcome, offering Cx43 protein detection as an independent prognostic marker stronger than vascular invasion or necrosis. As a contrary, elevated Cx30 mRNA and protein levels were associated with a reduced disease outcome offering Cx30 protein detection as an independent prognostic marker outperforming mitotic index and necrosis. Elevated versus low Cx43 protein levels allowed the stratification of grade 2 tumors into good and poor relapse free survival subgroups, respectively. Also, elevated versus low Cx30 levels stratified grade 3 patients into poor and good overall survival subgroups, respectively.Differential expression of Cx43 and Cx

  19. Neonatal hypothyroidism affects testicular glucose homeostasis through increased oxidative stress in prepubertal mice: effects on GLUT3, GLUT8 and Cx43.

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    Sarkar, D; Singh, S K

    2017-07-01

    Thyroid hormones (THs) play an important role in maintaining the link between metabolism and reproduction and the altered THs status is associated with induction of oxidative stress in various organs like brain, heart, liver and testis. Further, reactive oxygen species play a pivotal role in regulation of glucose homeostasis in several organs, and glucose utilization by Leydig cells is essential for testosterone biosynthesis and thus is largely dependent on glucose transporter 8 (GLUT8). Glucose uptake by Sertoli cells is mediated through glucose transporter 3 (GLUT3) under the influence of THs to meet energy requirement of developing germ cells. THs also modulate level of gap junctional protein such as connexin 43 (Cx43), a potential regulator of cell proliferation and apoptosis in the seminiferous epithelium. Although the role of transient neonatal hypothyroidism in adult testis in terms of testosterone production is well documented, the effect of THs deficiency in early developmental period and its role in testicular glucose homeostasis and oxidative stress with reference to Cx43 in immature mice remain unknown. Therefore, the present study was conducted to evaluate the effect of neonatal hypothyroidism on testicular glucose homeostasis and oxidative stress at postnatal days (PND) 21 and 28 in relation to GLUT3, GLUT8 and Cx43. Hypothyroidism induced by 6-propyl-2-thiouracil (PTU) markedly decreased testicular glucose level with considerable reduction in expression level of GLUT3 and GLUT8. Likewise, lactate dehydrogenase (LDH) activity and intratesticular concentration of lactate were also decreased in hypothyroid mice. There was also a rise in germ cell apoptosis with increased expression of caspase-3 in PTU-treated mice. Further, neonatal hypothyroidism affected germ cell proliferation with decreased expression of proliferating cell nuclear antigen (PCNA) and Cx43. In conclusion, our results suggest that neonatal hypothyroidism alters testicular glucose

  20. All-trans retinoic acid restores gap junctional intercellular communication between oral cancer cells with upregulation of Cx32 and Cx43 expressions in vitro.

    Science.gov (United States)

    Wang, Juan; Dai, Yaohui; Huang, Yulei; Chen, Xiaohua; Wang, Hong; Hong, Yun; Xia, Juan; Cheng, Bin

    2013-07-01

    All-trans retinoic acid (ATRA) has been demonstrated to inhibit tumor growth by restoration of gap junctional intercellular communication (GJIC) via upregulation of connexin (Cx) expression in some solid tumors. However, the relationship between ATRA and GJIC remains unclear in oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the effect of ATRA on the GJIC function of OSCC. We measured the effects of ATRA on the viability and cell cycle distribution of SCC9 and Tca8113 OSCC cells. The GJIC function was observed using the scrape-loading dye transfer technique, and the mRNA and protein levels of Cx32 and Cx43 were detected by qRT-PCR, Western blot, and immunofluorescence assays. ATRA inhibited the growth of OSCC cells in a dose- and time-dependent manner (P <0.05) and caused cell cycle arrest. ATRA-treated cells showed a 2.69-fold and 2.06-fold enhancement of GJIC in SCC9 and Tca8113 cells, respectively (P <0.05). Moreover, ATRA induced upregulation of Cx32 and Cx43 at both the mRNA and protein levels in OSCC cells. Our results indicated that restoration of GJIC via enhanced Cx32 and Cx43 expression might serve as a novel mechanism for the anti-tumor effect of ATRA in OSCC.

  1. HIV increased the release of dickkopf-1 (DKK1) protein from human astrocytes by a Cx43 hemichannel-dependent mechanism

    Science.gov (United States)

    Orellana, Juan Andres; Sáez, Juan Carlos; Bennett, Michael Vander Lann; Berman, Joan Weinberger; Morgello, Susan; Eugenin, Eliseo Alberto

    2015-01-01

    Human immunodeficiency virus-1 (HIV) is a public health issue and a major complication of the disease is NeuroAIDS. In vivo, microglia/macrophages are the main cells infected. However, a low but significant number of HIV infected astrocytes also has been detected, but their role in the pathogenesis of NeuroAIDS is not well understood. Our previous data indicates that gap junction channels amplify toxicity from few HIV infected into uninfected astrocytes. Now, we demonstrated that HIV infection of astrocytes results in opening of connexin43 hemichannels (Cx43 HCs). HIV induced opening of Cx43 HCs resulted in dysregulated secretion of dickkopf-1 protein (DKK1, a soluble wnt pathway inhibitor). Treatment of mixed cultures of neurons and astrocytes with DKK1, in the absence of HIV infection, resulted in collapse of neuronal processes. HIV infection of mixed cultures of human neurons and astrocytes also resulted in collapse of neuronal processes by a DKK1 dependent mechanism. In addition, dysregulated DKK1 expression in astrocytes was observed in human brain tissue sections of individuals with HIV encephalitis as compared to tissue sections from uninfected individuals. Thus, we demonstrated that HIV infection of astrocytes induces dysregulation of DKK1 by a HC-dependent mechanism that contributes to the brain pathogenesis observed in HIV infected individuals. PMID:24134157

  2. Non-dioxin-like organic toxicant PCB153 modulates sphingolipid metabolism in liver progenitor cells: its role in Cx43-formed gap junction impairment.

    Science.gov (United States)

    Pierucci, F; Frati, A; Squecco, R; Lenci, E; Vicenti, C; Slavik, J; Francini, F; Machala, M; Meacci, E

    2017-02-01

    The non-dioxin-like environmental toxicant 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153), member of a group of persistent organic pollutants wide-spread throughout the environment, reduces gap junction intercellular communication (GJIC), an event possibly associated with tumor promotion. Since very few studies have investigated the signaling effectors and mode(s) of action of PCB153, and it is known that the gap junction (GJ) protein Cx43 can be regulated by the bioactive sphingolipid (SL) sphingosine 1-phosphate (S1P), this in vitro study mainly addresses whether SL metabolism is affected by PCB153 in rat liver epithelial WB-F344 cells. PCB153 treatment obtained significant changes in the S1P/ceramide (Cer) ratio, known to be crucial in determining cell fate. In particular, an increase in S1P at 30 min and a decrease of the bioactive lipid at 3 h were observed, whereas Cer level increased at 1 h and 24 h. Notably, a time-dependent modulation of sphingosine kinase (SphK), the enzyme responsible for S1P synthesis, and of its regulators, ERK1/2 and protein phosphatase PP2A, supports the involvement of these signaling effectors in PCB153 toxicity. Electrophysiological analyses, furthermore, indicated that the lipophilic environmental toxicant significantly reduced GJ biophysical properties, affecting both voltage-dependent (such as those formed by Cx43 and/or Cx32) and voltage-independent channels, thereby demonstrating that PCB153 may act differently on GJs formed by distinct Cx isoforms. SphK down-regulation alone induced GJIC impairment, and, when combined with PCB153, the acute effect on GJ suppression was additive. Moreover, after enzyme-specific gene silencing, the SphK1 isoform appears to be responsible for down-regulating Cx43 expression, while being the target of PCB153 at short-term exposure. In conclusion, we provide the first evidence of novel effectors in PCB153 toxic action in rat liver stem-like cells, leading us to consider SLs as potential markers

  3. Different domains are critical for oligomerization compatibility of different connexins

    Science.gov (United States)

    MARTÍNEZ, Agustín D.; MARIPILLÁN, Jaime; ACUÑA, Rodrigo; MINOGUE, Peter J.; BERTHOUD, Viviana M.; BEYER, Eric C.

    2011-01-01

    Oligomerization of connexins is a critical step in gap junction channel formation. Some members of the connexin family can oligomerize with other members and form functional heteromeric hemichannels [e.g. Cx43 (connexin 43) and Cx45], but others are incompatible (e.g. Cx43 and Cx26). To find connexin domains important for oligomerization, we constructed chimaeras between Cx43 and Cx26 and studied their ability to oligomerize with wild-type Cx43, Cx45 or Cx26. HeLa cells co-expressing Cx43, Cx45 or Cx26 and individual chimaeric constructs were analysed for interactions between the chimaeras and the wild-type connexins using cell biological (subcellular localization by immunofluorescence), functional (intercellular diffusion of microinjected Lucifer yellow) and biochemical (sedimentation velocity through sucrose gradients) assays. All of the chimaeras containing the third transmembrane domain of Cx43 interacted with wild-type Cx43 on the basis of co-localization, dominant-negative inhibition of intercellular communication, and altered sedimentation velocity. The same chimaeras also interacted with co-expressed Cx45. In contrast, immunofluorescence and intracellular diffusion of tracer suggested that other domains influenced oligomerization compatibility when chimaeras were co-expressed with Cx26. Taken together, these results suggest that amino acids in the third transmembrane domain are critical for oligomerization with Cx43 and Cx45. However, motifs in different domains may determine oligomerization compatibility in members of different connexin subfamilies. PMID:21348854

  4. Contribution of intracellular calcium and pH in ischemic uncoupling of cardiac gap junction channels formed of connexins 43, 40, and 45: a critical function of C-terminal domain.

    Directory of Open Access Journals (Sweden)

    Giriraj Sahu

    Full Text Available Ischemia is known to inhibit gap junction (GJ mediated intercellular communication. However the detail mechanisms of this inhibition are largely unknown. In the present study, we determined the vulnerability of different cardiac GJ channels formed of connexins (Cxs 43, 40, and 45 to simulated ischemia, by creating oxygen glucose deprived (OGD condition. 5 minutes of OGD decreased the junctional conductance (Gj of Cx43, Cx40 and Cx45 by 53±3%, 64±1% and 85±2% respectively. Reduction of Gj was prevented completely by restricting the change of both intracellular calcium ([Ca(2+]i and pH (pHi with potassium phosphate buffer. Clamping of either [Ca(2+]i or pHi, through BAPTA (2 mM or HEPES (80 mM respectively, offered partial resistance to ischemic uncoupling. Anti-calmodulin antibody attenuated the uncoupling of Cx43 and Cx45 significantly but not of Cx40. Furthermore, OGD could reduce only 26±2% of Gj in C-terminus (CT truncated Cx43 (Cx43-Δ257. Tethering CT of Cx43 to the CT-truncated Cx40 (Cx40-Δ249, and Cx45 (Cx45-Δ272 helped to resist OGD mediated uncoupling. Moreover, CT domain played a significant role in determining the junction current density and plaque diameter. Our results suggest; OGD mediated uncoupling of GJ channels is primarily due to elevated [Ca(2+]i and acidic pHi, though the latter contributes more. Among Cx43, Cx40 and Cx45, Cx43 is the most resistant to OGD while Cx45 is the most sensitive one. CT of Cx43 has major necessary elements for OGD induced uncoupling and it can complement CT of Cx40 and Cx45.

  5. Mono-Heteromeric Configurations of Gap Junction Channels Formed by Connexin43 and Connexin45 Reduce Unitary Conductance and Determine both Voltage Gating and Metabolic Flux Asymmetry

    Directory of Open Access Journals (Sweden)

    Guoqiang Zhong

    2017-05-01

    Full Text Available In cardiac tissues, the expression of multiple connexins (Cx40, Cx43, Cx45, and Cx30.2 is a requirement for proper development and function. Gap junctions formed by these connexins have distinct permeability and gating mechanisms. Since a single cell can express more than one connexin isoform, the formation of hetero-multimeric gap junction channels provides a tissue with an enormous repertoire of combinations to modulate intercellular communication. To study further the perm-selectivity and gating properties of channels containing Cx43 and Cx45, we studied two monoheteromeric combinations in which a HeLa cell co-transfected with Cx43 and Cx45 was paired with a cell expressing only one of these connexins. Macroscopic measurements of total conductance between cell pairs indicated a drastic reduction in total conductance for mono-heteromeric channels. In terms of Vj dependent gating, Cx43 homomeric connexons facing heteromeric connexons only responded weakly to voltage negativity. Cx45 homomeric connexons exhibited no change in Vj gating when facing heteromeric connexons. The distributions of unitary conductances (γj for both mono-heteromeric channels were smaller than predicted, and both showed low permeability to the fluorescent dyes Lucifer yellow and Rhodamine123. For both mono-heteromeric channels, we observed flux asymmetry regardless of dye charge: flux was higher in the direction of the heteromeric connexon for MhetCx45 and in the direction of the homomeric Cx43 connexon for MhetCx43. Thus, our data suggest that co-expression of Cx45 and Cx43 induces the formation of heteromeric connexons with greatly reduced permeability and unitary conductance. Furthermore, it increases the asymmetry for voltage gating for opposing connexons, and it favors asymmetric flux of molecules across the junction that depends primarily on the size (not the charge of the crossing molecules.

  6. Glutamate receptor agonists

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  7. Interfering amino terminal peptides and functional implications for heteromeric gap junction formation

    Directory of Open Access Journals (Sweden)

    Richard David Veenstra

    2013-05-01

    Full Text Available Connexin43 (Cx43 is widely expressed in many different tissues of the human body. In cells of some organs, Cx43 is co-expressed with other connexins (Cx, including Cx46 and Cx50 in lens, Cx40 in atrium, Purkinje fibers, and the blood vessel wall, Cx45 in heart, and Cx37 in the ovary. Interactions with the co-expressed connexins may have profound functional implications. The abilities of Cx37, Cx45, Cx46, and Cx50 to function in heteromeric gap junction combinations with Cx43 are well documented. Different studies disagree regarding the ability of Cx43 and Cx40 to produce functional heteromeric gap junctions with each other. We review previous studies regarding the heteromeric interactions of Cx43. The possibility of negative functional interactions between the cytoplasmic pore-forming amino terminal (NT domains of these connexins was assessed using pentameric connexin sequence-specific NT domain (iNT peptides applied to cells expressing homomeric Cx40, Cx37, Cx45, Cx46, and Cx50 gap junctions. A Cx43 iNT peptide corresponding to amino acids 9 to 13 (Ac-KLLDK-NH2 specifically inhibited the electrical coupling of Cx40 gap junctions in a transjunctional (Vj voltage-dependent manner without affecting the function of homologous Cx37, Cx46, Cx50, and Cx45 gap junctions. A Cx40 iNT (Ac-EFLEE-OH peptide counteracted the Vj-dependent block of Cx40 gap junctions, whereas a similarly charged Cx50 iNT (Ac-EEVNE-OH peptide did not, suggesting that these NT domain interactions are not solely based on electrostatics. These data are consistent with functional Cx43 heteromeric gap junction formation with Cx37, Cx45, Cx46, and Cx50 and suggest that Cx40 uniquely experiences functional suppressive interactions with a Cx43 NT domain sequence. These findings present unique functional implications about the heteromeric interactions between Cx43 and Cx40 that may influence cardiac conduction in atrial myocardium and the specialized conduction system.

  8. History of glutamate production.

    Science.gov (United States)

    Sano, Chiaki

    2009-09-01

    In 1907 Kikunae Ikeda, a professor at the Tokyo Imperial University, began his research to identify the umami component in kelp. Within a year, he had succeeded in isolating, purifying, and identifying the principal component of umami and quickly obtained a production patent. In 1909 Saburosuke Suzuki, an entrepreneur, and Ikeda began the industrial production of monosodium l-glutamate (MSG). The first industrial production process was an extraction method in which vegetable proteins were treated with hydrochloric acid to disrupt peptide bonds. l-Glutamic acid hydrochloride was then isolated from this material and purified as MSG. Initial production of MSG was limited because of the technical drawbacks of this method. Better methods did not emerge until the 1950s. One of these was direct chemical synthesis, which was used from 1962 to 1973. In this procedure, acrylonitrile was the starting material, and optical resolution of dl-glutamic acid was achieved by preferential crystallization. In 1956 a direct fermentation method to produce glutamate was introduced. The advantages of the fermentation method (eg, reduction of production costs and environmental load) were large enough to cause all glutamate manufacturers to shift to fermentation. Today, total world production of MSG by fermentation is estimated to be 2 million tons/y (2 billion kg/y). However, future production growth will likely require further innovation.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    The cellular distribution of transporters and enzymes related to glutamate metabolism led to the concept of the glutamate–glutamine cycle. Glutamate is released as a neurotransmitter and taken up primarily by astrocytes ensheathing the synapses. The glutamate carbon skeleton is transferred back t...

  10. Cytokine effects on gap junction communication and connexin expression in human bladder smooth muscle cells and suburothelial myofibroblasts.

    Directory of Open Access Journals (Sweden)

    Marco Heinrich

    Full Text Available BACKGROUND: The last decade identified cytokines as one group of major local cell signaling molecules related to bladder dysfunction like interstitial cystitis (IC and overactive bladder syndrome (OAB. Gap junctional intercellular communication (GJIC is essential for the coordination of normal bladder function and has been found to be altered in bladder dysfunction. Connexin (Cx 43 and Cx45 are the most important gap junction proteins in bladder smooth muscle cells (hBSMC and suburothelial myofibroblasts (hsMF. Modulation of connexin expression by cytokines has been demonstrated in various tissues. Therefore, we investigate the effect of interleukin (IL 4, IL6, IL10, tumor necrosis factor-alpha (TNFα and transforming growth factor-beta1 (TGFβ1 on GJIC, and Cx43 and Cx45 expression in cultured human bladder smooth muscle cells (hBSMC and human suburothelial myofibroblasts (hsMF. METHODOLOGY/PRINCIPAL FINDINGS: HBSMC and hsMF cultures were set up from bladder tissue of patients undergoing cystectomy. In cytokine stimulated cultured hBSMC and hsMF GJIC was analyzed via Fluorescence Recovery after Photo-bleaching (FRAP. Cx43 and Cx45 expression was assessed by quantitative PCR and confocal immunofluorescence. Membrane protein fraction of Cx43 and Cx45 was quantified by Dot Blot. Upregulation of cell-cell-communication was found after IL6 stimulation in both cell types. In hBSMC IL4 and TGFβ1 decreased both, GJIC and Cx43 protein expression, while TNFα did not alter communication in FRAP-experiments but increased Cx43 expression. GJ plaques size correlated with coupling efficacy measured, while Cx45 expression did not correlate with modulation of GJIC. CONCLUSIONS/SIGNIFICANCE: Our finding of specific cytokine effects on GJIC support the notion that cytokines play a pivotal role for pathophysiology of OAB and IC. Interestingly, the effects were independent from the classical definition of pro- and antiinflammatory cytokines. We conclude, that

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    -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...... of extracellular glutamate independently of the GDH expression level. Moreover, increased intracellular glutamate content was observed in the GDH-deficient cells after a 2-hr incubation in the presence of 100 µM glutamate. It is significant that GDH-deficient cells exhibited an increased utilization of glucose...

  12. Abrogation of Gap Junctional Communication in ES Cells Results in a Disruption of Primitive Endoderm Formation in Embryoid Bodies.

    Science.gov (United States)

    Wörsdörfer, Philipp; Bosen, Felicitas; Gebhardt, Martina; Russ, Nicole; Zimmermann, Katrin; Komla Kessie, David; Sekaran, Thileepan; Egert, Angela; Ergün, Süleyman; Schorle, Hubert; Pfeifer, Alexander; Edenhofer, Frank; Willecke, Klaus

    2017-04-01

    Gap junctional intercellular communication (GJIC) has been suggested to be involved in early embryonic development but the actual functional role remained elusive. Connexin (Cx) 43 and Cx45 are co-expressed in embryonic stem (ES) cells, form gap junctions and are considered to exhibit adhesive function and/or to contribute to the establishment of defined communication compartments. Here, we describe the generation of Cx43/Cx45-double deficient mouse ES cells to achieve almost complete breakdown of GJIC. Cre-loxP induced deletion of both, Cx43 and Cx45, results in a block of differentiation in embryoid bodies (EBs) without affecting pluripotency marker expression and proliferation in ES cells. We demonstrate that GJIC-incompetent ES cells fail to form primitive endoderm in EB cultures, representing the inductive key step of further differentiation events. Lentiviral overexpression of either Cx43 or Cx45 in Cx43/45 mutants rescued the observed phenotype, confirming the specificity and indicating a partially redundant function of both connexins. Upon differentiation GJIC-incompetent ES cells exhibit a strikingly altered subcellular localization pattern of the transcription factor NFATc3. Control EBs exhibit significantly more activated NFATc3 in cellular nuclei than mutant EBs suggesting that Cx-mediated communication is needed for synchronized NFAT activation to induce orchestrated primitive endoderm formation. Moreover, pharmacological inhibition of NFATc3 activation by Cyclosporin A, a well-described inhibitor of calcineurin, phenocopies the loss of GJIC in control cells. Stem Cells 2017;35:859-871. © 2016 The Authors STEM CELLS published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

  13. Cx43, ZO-1, alpha-catenin and beta-catenin in cataractous lens ...

    Indian Academy of Sciences (India)

    2012-10-17

    Oct 17, 2012 ... An ultrastructural study of the posteriorly migrating cells. Arch. Ophthalmol. 98 134–143. Fanning AS, Jameson BJ, Jesaitis LA and Anderson JM 1998 The tight junction protein ZO-1 establishes a link between the trans- membrane protein occludin and the actin cytoskeleton. J. Biol. Chem. 273 29745– ...

  14. Arrhythmogenesis in the remodeled heart : the role of spatially dispersed Cx43 expression

    NARCIS (Netherlands)

    Boulaksil, M.

    2010-01-01

    The heart is able to adapt to new, often pathologic, conditions, so-called cardiac remodeling. Although initially adequate, these adaptations could can become maladaptive over time. One of the adaptations of the heart during pathology is ventricular hypertrophy, which may go hand in hand with an

  15. Permeability of R6G across Cx43 hemichannels through a novel ...

    Indian Academy of Sciences (India)

    We have measured the permeability of rhodamine-6G across C×43 hemichannels reconstituted on a pipette tip. C×43 hemichannels were overexpressed in Sf9 cells, and affinity-purified. The hemichannels were reconstituted in a lipid bilayer on a pipette tip by the tip-dip method. R6G in the pipette permeated across the ...

  16. Regulation of Cx43 gap junctions: the gatekeeper and the password.

    Science.gov (United States)

    Hossain, M Z; Boynton, A L

    2000-10-17

    Gap junctions are regulatable pores that connect the cytoplasms of neighboring cells. Hossain and Boynton focus on connexin 43 gap junctions and their regulation by changing the phosphorylation status of the COOH-terminal domain of connexin 43 or by altering protein-protein interactions in this region. The COOH-terminal domain of connexin 43 appears to be a key player in regulating gap junctional communication (GJC) because many divergent signals in many different cell types modify this domain to inhibit GJC.

  17. Cx43, ZO-1, alpha-catenin and beta-catenin in cataractous lens ...

    Indian Academy of Sciences (India)

    Specimens of the anterior lens capsule with an attached monolayer of lens epithelial cells (LECs) were obtained from patients (=52) undergoing cataract surgery. Specimens were divided into three groups based on the type of cataract: nuclear cataract, cortical cataract and posterior subcapsular cataract (PSC).

  18. Glutamate receptor ligands

    DEFF Research Database (Denmark)

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

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA.......g., IC(50) = 300 microM for (2R,4S)-4-methyl-AA (5d)]. The two unsaturated analogs (S)- (7a) and (R)-(E)-Delta(4)-5-methyl-AA (7b) turned out to be a weak AMPA receptor agonist and a weak mixed NMDA/AMPA receptor antagonist, respectively....

  19. Membrane connexin 43 acts as an independent prognostic marker in oral squamous cell carcinoma.

    Science.gov (United States)

    Brockmeyer, Phillipp; Jung, Klaus; Perske, Christina; Schliephake, Henning; Hemmerlein, Bernhard

    2014-07-01

    The aim of the present study was to evaluate the expression and localization of connexin (Cx) 26, -43 and -45 in a group of 35 patients with primary oral squamous cell carcinoma (OSCC) with the objective of making a more accurate disease prognosis. We analysed the expression of connexins in tissue samples of primary OSCC, matching oral mucosa free of dysplasia, and its associated lymph node metastases (LNM) by semi-quantitative immunohistochemistry of membrane, cytoplasmic and nuclear connexin expression. The levels of expression were correlated with the overall survival time (OS). Cx43 was overexpressed in tumour cells compared to epithelia in dysplasia-free mucosa. High membrane expression of Cx43 on tumour cells was the only statistically significant and independent prognostic factor of short OS (P=0.0088). Membrane expression of Cx43 in matching dysplasia-free mucosa acted similarly, but did not reach statistical significance (P=0.059). No correlation was found between the Cx26, Cx45 expression and OS. We conclude that Cx43 expression in dysplasia-free mucosa may indicate a very early stage of tumour promotion. Although overexpression of Cx43 is found in invasive tumours we only found membrane Cx43 expression to correlate with OS. This observation suggests that cytoplasmic Cx43 serves as storage and only membrane translocation may promote the formation of gap junctions and gap junctional intercellular communication (GJIC) with prognostic relevance.

  20. Substrate and Cation Binding Mechanism of Glutamate Transporter Homologs

    NARCIS (Netherlands)

    Jensen, Sonja

    2017-01-01

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

  1. Glutamic acid as anticancer agent: An overview.

    Science.gov (United States)

    Dutta, Satyajit; Ray, Supratim; Nagarajan, K

    2013-10-01

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

  2. [The glutamate hypothesis of schizophrenia].

    Science.gov (United States)

    Hasan, A; Malchow, B; Falkai, P; Schmitt, A

    2014-08-01

    For many years, the dopamine hypothesis of schizophrenia has been the leading theory explaining the aetiology of schizophrenia. However, since the first observation showed that NMDA-receptor antagonists (e. g., PCP) can induce all kinds of schizophrenia symptoms in humans, the glutamate hypothesis of schizophrenia has been established as an additional explanation model. Apart from the PCP-induced psychoses, many other findings from all areas of modern neuroscience have confirmed and extended the glutamate hypothesis. This review discusses the available evidence for the glutamate hypothesis and puts the different findings into relation. Consecutively, the possibilities for a pharmacological modulation of the glutamate system and recent clinical trials are discussed. To sum up, one could note that the glutamate hypothesis of schizophrenia is now well-established. The development of glutamatergic antipsychotics is still in the early stages, but there is hope for a new generation of antipsychotics based on the glutamate hypothesis of schizophrenia. However, recent findings from registration trials could not provide positive findings for the recently developed glutamatergic drugs. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Metabotropic glutamate receptors in cancer.

    Science.gov (United States)

    Yu, Lumeng J; Wall, Brian A; Wangari-Talbot, Janet; Chen, Suzie

    2017-03-15

    Metabotropic glutamate receptors (mGluRs) are widely known for their roles in synaptic signaling. However, accumulating evidence suggests roles of mGluRs in human malignancies in addition to synaptic transmission. Somatic cell homeostasis presents intriguing possibilities of mGluRs and glutamate signaling as novel targets for human cancers. More recently, aberrant glutamate signaling has been shown to participate in the transformation and maintenance of various cancer types, including glioma, melanoma skin cancer, breast cancer, and prostate cancer, indicating that genes encoding mGluRs, GRMs, can function as oncogenes. Here, we provide a review on the interactions of mGluRs and their ligand, glutamate, in processes that promote the growth of tumors of neuronal and non-neuronal origins. Further, we discuss the evolution of riluzole, a glutamate release inhibitor approved for amyotrophic lateral sclerosis (ALS), but now fashioned as an mGluR1 inhibitor for melanoma therapy and as a radio-sensitizer for tumors that have metastasized to the brain. With the success of riluzole, it is not far-fetched to believe that other drugs that may act directly or indirectly on other mGluRs can be beneficial for multiple applications. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Genotoxicity of monosodium glutamate.

    Science.gov (United States)

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

    2016-05-01

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

  5. Group I Metabotropic Glutamate Receptors

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  6. The impact of caffeine on connexin expression in the embryonic chick cardiomyocyte micromass culture system.

    Science.gov (United States)

    Ahir, Bhavesh K; Pratten, Margaret K

    2016-07-01

    Cardiomyocytes are electrically coupled by gap junctions, defined as clusters of low-resistance multisubunit transmembrane channels composed of connexins (Cxs). The expression of Cx40, Cx43 and Cx45, which are present in cardiomyocytes, is known to be developmentally regulated. This study investigates the premise that alterations in gap junction proteins are one of the mechanisms by which teratogens may act. Specifically, those molecules known to be teratogenic in humans could cause their effects via disruption of cell-to-cell communication pathways, resulting in an inability to co-ordinate tissue development. Caffeine significantly inhibited contractile activity at concentrations above and including 1500 μm (P cell viability and total protein, in the embryonic chick cardiomyocyte micromass culture system. The effects of caffeine on key cardiac gap junction protein (Cx40, Cx43 and Cx45) expression were analysed using immunocytochemistry and in-cell Western blotting. The results indicated that caffeine altered the expression pattern of Cx40, Cx43 and Cx45 at non-cytotoxic concentrations (≥2000 μm), i.e., at concentrations that did not affect total cell protein and cell viability. In addition the effects of caffeine on cardiomyocyte formation and function (contractile activity score) were correlated with modulation of Cxs (Cx40, Cx43 and Cx45) expression, at above and including 2000 μm caffeine concentrations (P < 0.05). These experiments provide evidence that embryonic chick cardiomyocyte micromass culture may be a useful in vitro method for mechanistic studies of perturbation of embryonic heart development. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  7. 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...

  8. Glutamate Metabolism in Major Depressive Disorder

    National Research Council Canada - National Science Library

    Abdallah, Chadi G; Jiang, Lihong; De Feyter, Henk M; Fasula, Madonna; Krystal, John H; Rothman, Douglas L; Mason, Graeme F; Sanacora, Gerard

    2014-01-01

    Research on novel treatments for major depressive disorder focuses quite deeply on glutamate function, and this research would benefit from a brain-imaging technique that precisely quantified glutamate function...

  9. DNA nanopore translocation in glutamate solutions

    NARCIS (Netherlands)

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

    2015-01-01

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

  10. Glutamic acid as anticancer agent: An overview

    National Research Council Canada - National Science Library

    Dutta, Satyajit; Ray, Supratim; Nagarajan, K

    2013-01-01

    The objective of the article is to highlight various roles of glutamic acid like endogenic anticancer agent, conjugates to anticancer agents, and derivatives of glutamic acid as possible anticancer agents...

  11. 21 CFR 182.1045 - Glutamic acid.

    Science.gov (United States)

    2010-04-01

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

  12. [Glutamate signaling and neural plasticity].

    Science.gov (United States)

    Watanabe, Masahiko

    2013-07-01

    Proper functioning of the nervous system relies on the precise formation of neural circuits during development. At birth, neurons have redundant synaptic connections not only to their proper targets but also to other neighboring cells. Then, functional neural circuits are formed during early postnatal development by the selective strengthening of necessary synapses and weakening of surplus connections. Synaptic connections are also modified so that projection fields of active afferents expand at the expense of lesser ones. We have studied the molecular mechanisms underlying these activity-dependent prunings and the plasticity of synaptic circuitry using gene-engineered mice defective in the glutamatergic signaling system. NMDA-type glutamate receptors are critically involved in the establishment of the somatosensory pathway ascending from the brainstem trigeminal nucleus to the somatosensory cortex. Without NMDA receptors, whisker-related patterning fails to develop, whereas lesion-induced plasticity occurs normally during the critical period. In contrast, mice lacking the glutamate transporters GLAST or GLT1 are selectively impaired in the lesion-induced critical plasticity of cortical barrels, although whisker-related patterning itself develops normally. In the developing cerebellum, multiple climbing fibers initially innervating given Purkinje cells are eliminated one by one until mono-innervation is achieved. In this pruning process, P/Q-type Ca2+ channels expressed on Purkinje cells are critically involved by the selective strengthening of single main climbing fibers against other lesser afferents. Therefore, the activation of glutamate receptors that leads to an activity-dependent increase in the intracellular Ca2+ concentration plays a key role in the pruning of immature synaptic circuits into functional circuits. On the other hand, glutamate transporters appear to control activity-dependent plasticity among afferent fields, presumably through adjusting

  13. 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. Introduction to the Glutamate-Glutamine Cycle

    DEFF Research Database (Denmark)

    Sonnewald, Ursula; Schousboe, Arne

    2016-01-01

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

  15. Introduction to the Glutamate-Glutamine Cycle

    DEFF Research Database (Denmark)

    Sonnewald, Ursula; Schousboe, Arne

    2016-01-01

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

  16. Genetics Home Reference: glutamate formiminotransferase deficiency

    Science.gov (United States)

    ... are some genetic conditions more common in particular ethnic groups? Genetic Changes Mutations in the FTCD gene cause glutamate formiminotransferase deficiency . The FTCD gene provides instructions for ...

  17. AMPK Activation Affects Glutamate Metabolism in Astrocytes

    DEFF Research Database (Denmark)

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

    2015-01-01

    acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon...... affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK...

  18. Glutamate signalling in healthy and diseased bone

    Directory of Open Access Journals (Sweden)

    Robert W. Cowan

    2012-07-01

    Full Text Available Bone relies on multiple extracellular signalling systems to maintain homeostasis of its normal structure and functions. The amino acid glutamate is a fundamental extracellular messenger molecule in many tissues, and is used in bone for both neural and non-neural signalling. This review focuses on the non-neural interactions, and examines the evolutionarily ancient glutamate signalling system in the context of its application to normal bone functioning and discusses recent findings on the role of glutamate signalling as they pertain to maintaining healthy bone structure. The underlying mechanisms of glutamate signalling and the many roles glutamate plays in modulating bone physiology are featured, including those involved in osteoclast and osteoblast differentiation and mature cell functions. Moreover, the relevance of glutamate signalling systems in diseases that affect bone, such as cancer and rheumatoid arthritis, is discussed, and will highlight how the glutamate system may be exploited as a viable therapeutic target. We will identify novel areas of research where knowledge of glutamate communication mechanisms may aid in our understanding of the complex nature of bone homeostasis. By uncovering the contributions of glutamate in maintaining healthy bone, the reader will discover how this complex molecular signalling system may advance our capacity to treat bone pathologies.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  20. Glutamate gated spiking Neuron Model.

    Science.gov (United States)

    Deka, Krisha M; Roy, Soumik

    2014-01-01

    Biological neuron models mainly analyze the behavior of neural networks. Neurons are described in terms of firing rates viz an analog signal. The Izhikevich neuron model is an efficient, powerful model of spiking neuron. This model is a reduction of Hodgkin-Huxley model to a two variable system and is capable of producing rich firing patterns for many biological neurons. In this paper, the Regular Spiking (RS) neuron firing pattern is used to simulate the spiking of Glutamate gated postsynaptic membrane. Simulation is done in MATLAB environment for excitatory action of synapses. Analogous simulation of spiking of excitatory postsynaptic membrane potential is obtained.

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

    African Journals Online (AJOL)

    Daisy Ouya

    1) glutamate dehydrogenases (GDH) and (2) glutamine synthetase (GS)/ glutamate synthase (GOGAT). In the GS/ GOGAT route, ammonia is first incorporated into glutamine by the action of GS and subsequently into glutamic acid by GOGAT.

  2. Connexins in skeletal muscle development and disease.

    Science.gov (United States)

    Merrifield, Peter A; Laird, Dale W

    2016-02-01

    Gap junctions consist of clusters of intercellular channels composed of connexins that connect adjacent cells and allow the exchange of small molecules. While the 21 member multi-gene family of connexins are ubiquitously found in humans, only Cx39, Cx40, Cx43 and Cx45 have been documented in developing myoblasts and injured adult skeletal muscle while healthy adult skeletal muscle is devoid of connexins. The use of gap junctional blockers and cultured myoblast cell lines have suggested that these connexins play a critical role in myotube formation and muscle regeneration. More recent genetically-modified mouse models where Cx43 function is greatly compromized or ablated have further supported a role for Cx43 in regulating skeletal muscle development. In the last decade, we have become aware of a cohort of patients that have a development disorder known as oculodentodigital dysplasia (ODDD). These patients harbor either gain or loss of Cx43 function gene mutations that result in many organ anomalies raising questions as to whether they suffer from defects in skeletal muscle formation or regeneration upon injury. Interesting, some ODDD patients report muscle weakness and loss of limb control but it is not clear if this is neurogenic or myogenic in origin. This review will focus on the role connexins play in muscle development and repair and discuss the impact of Cx43 mutants on muscle function. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  3. Impact of obesity on 7,12-dimethylbenz[a]anthracene-induced altered ovarian connexin gap junction proteins in female mice

    Energy Technology Data Exchange (ETDEWEB)

    Ganesan, Shanthi, E-mail: shanthig@iastate.edu; Nteeba, Jackson, E-mail: nteeba@iastate.edu; Keating, Aileen F., E-mail: akeating@iastate.edu

    2015-01-01

    The ovarian gap junction proteins alpha 4 (GJA4 or connexin 37; CX37), alpha 1 (GJA1 or connexin 43; CX43) and gamma 1 (GJC1 or connexin 45; CX45) are involved in cell communication and folliculogenesis. 7,12-dimethylbenz[a]anthracene (DMBA) alters Cx37 and Cx43 expression in cultured neonatal rat ovaries. Additionally, obesity has an additive effect on DMBA-induced ovarian cell death and follicle depletion, thus, we investigated in vivo impacts of obesity and DMBA on CX protein levels. Ovaries were collected from lean and obese mice aged 6, 12, 18, or 24 wks. A subset of 18 wk old mice (lean and obese) were dosed with sesame oil or DMBA (1 mg/kg; ip) for 14 days and ovaries collected 3 days thereafter. Cx43 and Cx45 mRNA and protein levels decreased (P < 0.05) after 18 wks while Cx37 mRNA and protein levels decreased (P < 0.05) after 24 wks in obese ovaries. Cx37 mRNA and antral follicle protein staining intensity were reduced (P < 0.05) by obesity while total CX37 protein was reduced (P < 0.05) in DMBA exposed obese ovaries. Cx43 mRNA and total protein levels were decreased (P < 0.05) by DMBA in both lean and obese ovaries while basal protein staining intensity was reduced (P < 0.05) in obese controls. Cx45 mRNA, total protein and protein staining intensity level were decreased (P < 0.05) by obesity. These data support that obesity temporally alters gap junction protein expression and that DMBA-induced ovotoxicity may involve reduced gap junction protein function. - Highlights: • Ovarian gap junction proteins are affected by ovarian aging and obesity. • DMBA exposure negatively impacts gap junction proteins. • Altered gap junction proteins may contribute to infertility.

  4. Glutamate synthase: An archaeal horizontal gene transfer?

    Indian Academy of Sciences (India)

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

  5. Activities of alkaline phosphatase, glutamate oxaloacetate ...

    African Journals Online (AJOL)

    Alkaline phosphatase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase activities were assessed in rats highly infected with federe strain of Trypanosoma brucei and treated with honey. Therapeutic effect of honey on parasitaemia was also assessed. Results show an extension in the life span of ...

  6. The blood-brain barrier and glutamate.

    Science.gov (United States)

    Hawkins, Richard A

    2009-09-01

    Glutamate concentrations in plasma are 50-100 micromol/L; in whole brain, they are 10,000-12,000 micromol/L but only 0.5-2 micromol/L in extracellular fluids (ECFs). The low ECF concentrations, which are essential for optimal brain function, are maintained by neurons, astrocytes, and the blood-brain barrier (BBB). Cerebral capillary endothelial cells form the BBB that surrounds the entire central nervous system. Tight junctions connect endothelial cells and separate the BBB into luminal and abluminal domains. Molecules entering or leaving the brain thus must pass 2 membranes, and each membrane has distinct properties. Facilitative carriers exist only in luminal membranes, and Na(+)-dependent glutamate cotransporters (excitatory amino acid transporters; EAATs) exist exclusively in abluminal membranes. The EAATs are secondary transporters that couple the Na(+) gradient between the ECF and the endothelial cell to move glutamate against the existing electrochemical gradient. Thus, the EAATs in the abluminal membrane shift glutamate from the ECF to the endothelial cell where glutamate is free to diffuse into blood on facilitative carriers. This organization does not allow net glutamate entry to the brain; rather, it promotes the removal of glutamate and the maintenance of low glutamate concentrations in the ECF. This explains studies that show that the BBB is impermeable to glutamate, even at high concentrations, except in a few small areas that have fenestrated capillaries (circumventricular organs). Recently, the question of whether the BBB becomes permeable in diabetes has arisen. This issue was tested in rats with diet-induced obesity and insulin resistance or with streptozotocin-induced diabetes. Neither condition produced any detectable effect on BBB glutamate transport.

  7. Glutamate and Brain Glutaminases in Drug Addiction.

    Science.gov (United States)

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

    2017-03-01

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

  8. Cocaine-induced neuroadaptations in glutamate transmission

    Science.gov (United States)

    Schmidt, Heath D.; Pierce, R. Christopher

    2017-01-01

    A growing body of evidence indicates that repeated exposure to cocaine leads to profound changes in glutamate transmission in limbic nuclei, particularly the nucleus accumbens. This review focuses on preclinical studies of cocaine-induced behavioral plasticity, including behavioral sensitization, self-administration, and the reinstatement of cocaine seeking. Behavioral, pharmacological, neurochemical, electrophysiological, biochemical, and molecular biological changes associated with cocaine-induced plasticity in glutamate systems are reviewed. The ultimate goal of these lines of research is to identify novel targets for the development of therapies for cocaine craving and addiction. Therefore, we also outline the progress and prospects of glutamate modulators for the treatment of cocaine addiction. PMID:20201846

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Grzegorz Sulkowski

    Full Text Available 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. 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

  13. Biobased synthesis of acrylonitrile from glutamic acid

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    African Journals Online (AJOL)

    ONOS

    2010-09-06

    Sep 6, 2010 ... either MSG or DW. Key words: Monosodium glutamate, total acid phosphatase, prostatic acid phosphatase, prostate cancer, prostatitis, benign prostate hyperplasia, infertility. INTRODUCTION. Elevated total acid phosphatase (TAP) and prostatic acid phosphatase (PAP) activities are among the main.

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

    Science.gov (United States)

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

    2016-01-15

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

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

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    Science.gov (United States)

    Dougherty, Charles M; Dayan, Jean

    1982-01-01

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

  18. Glutamic acid modification of vincristine toxicity.

    Science.gov (United States)

    Jackson, D V; Rosenbaum, D L; Carlisle, L J; Long, T R; Wells, H B; Spurr, C L

    1984-09-01

    The principal limiting feature of the antitumor agent, vincristine, in the clinic has been neurotoxicity; there are no known agents which can routinely prevent or decrease this side effect. Glutamic acid in laboratory and clinical investigations in the early 1960s was found to antagonize vinblastine, another clinically useful vinca alkaloid. Glutamic acid 250 mg/kg/d i.p. was given to normal mice treated with repetitive doses of vincristine 1.5 mg/kg every other day. When glutamic acid was given both before and during vincristine administration, it produced a 49-79% increase in survival compared to control mice receiving vincristine only (p less than 0.01). Other schedules of glutamic acid administration were ineffective. Also, there appeared to be a delay in development of neurotoxic manifestations (toe-walking gait) but the results were not as consistent as the improvement in survival. Glutamic acid given to tumor-bearing mice (P-388 and P-1534 murine leukemia) did not inhibit the antitumor effect of vincristine-induced host toxicity in a schedule-dependent fashion without inhibition of the antitumor effect of vincristine.

  19. Metabotropic Glutamate Receptor 5 and Glutamate Involvement in Major Depressive Disorder: A Multimodal Imaging Study.

    Science.gov (United States)

    Abdallah, Chadi G; Hannestad, Jonas; Mason, Graeme F; Holmes, Sophie E; DellaGioia, Nicole; Sanacora, Gerard; Jiang, Lihong; Matuskey, David; Satodiya, Ritvij; Gasparini, Fabrizio; Lin, Xin; Javitch, Jonathan; Planeta, Beata; Nabulsi, Nabeel; Carson, Richard E; Esterlis, Irina

    2017-07-01

    Preclinical and postmortem studies have implicated the metabotropic glutamate receptor 5 (mGluR5) in the pathophysiology of major depressive disorder (MDD). The goal of the present study was to determine the role of mGluR5 in a large group of individuals with MDD compared to healthy controls (HC) in vivo with [(18)F]FPEB and positron emission tomography (PET). Furthermore, we sought to determine the role glutamate plays on mGluR5 availability in MDD. Sixty-five participants (30 MDD and 35 HC) completed [(18)F]FPEB PET to estimate the primary outcome measure - mGluR5 volume of distribution (VT), and the secondary outcome measure - mGluR5 distribution volume ratio (DVR). A subgroup of 39 participants (16 MDD and 23 HC) completed proton magnetic resonance spectroscopy ((1)H MRS) to estimate anterior cingulate (ACC) glutamate, glutamine, and Glx (glutamate + glutamine) levels relative to creatine (Cr). No significant between-group differences were observed in mGluR5 VT or DVR. Compared to HC, individuals with MDD had higher ACC glutamate, glutamine, and Glx levels. Importantly, the ACC mGluR5 DVR negatively correlated with glutamate/Cr and Glx/Cr levels. In this novel in vivo examination, we show an inverse relationship between mGluR5 availability and glutamate levels. These data highlight the need to further investigate the role of glutamatergic system in depression.

  20. 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.

  1. 78 FR 76321 - Monosodium Glutamate From China and Indonesia

    Science.gov (United States)

    2013-12-17

    ... COMMISSION Monosodium Glutamate From China and Indonesia Determinations On the basis of the record \\1... injured by reason of imports from China and Indonesia of monosodium glutamate, provided for in subheading... imports of monosodium glutamate from China and Indonesia that are subsidized by the Governments of China...

  2. 21 CFR 182.1047 - Glutamic acid hydrochloride.

    Science.gov (United States)

    2010-04-01

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

  3. 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.

  4. Glutamate Mediated Astrocytic Filtering of Neuronal Activity

    Science.gov (United States)

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

    2014-01-01

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

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

    African Journals Online (AJOL)

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  7. 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.

  8. Systemic administration of monosodium glutamate elevates intramuscular glutamate levels and sensitizes rat masseter muscle afferent fibers.

    Science.gov (United States)

    Cairns, Brian E; Dong, Xudong; Mann, Mandeep K; Svensson, Peter; Sessle, Barry J; Arendt-Nielsen, Lars; McErlane, Keith M

    2007-11-01

    There is evidence that elevated tissue concentrations of glutamate may contribute to pain and sensitivity in certain musculoskeletal pain conditions. In the present study, the food additive monosodium glutamate (MSG) was injected intravenously into rats to determine whether it could significantly elevate interstitial concentrations of glutamate in the masseter muscle and whether MSG administration could excite and/or sensitize slowly conducting masseter afferent fibers through N-methyl-D-aspartate (NMDA) receptor activation. The interstitial concentration of glutamate after systemic injection of isotonic phosphate-buffered saline (control) or MSG (10 and 50mg/kg) was measured with a glutamate-selective biosensor. The pre-injection baseline interstitial concentration of glutamate in the rat masseter muscle was 24+/-11 microM. Peak interstitial concentration after injection of 50mg/kg MSG was 63+/-18 microM and remained elevated above baseline for approximately 18 min. In vivo single unit recording experiments were undertaken to assess the effect of MSG (50mg/kg) on masseter afferent fibers. Injection of MSG evoked a brief discharge in one afferent fiber, and significantly decreased ( approximately 25%) the average afferent mechanical threshold (n=10) during the first 5 min after injection of MSG. Intravenous injection of ketamine (1mg/kg), 5 min prior to MSG, prevented the MSG-induced decreases in the mechanical threshold of masseter afferent fibers. The present results indicate that a 2- to 3-fold elevation in interstitial glutamate levels in the masseter muscle is sufficient to excite and induce afferent mechanical sensitization through NMDA receptor activation. These findings suggest that modest elevations of interstitial glutamate concentration could alter musculoskeletal pain sensitivity in humans.

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

    Science.gov (United States)

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

    2015-07-16

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

  10. Glutamate Transporters in the Blood-Brain Barrier

    DEFF Research Database (Denmark)

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

    2017-01-01

    concentration of L-glutamate causes excitotoxicity. A tight control of the brain interstitial fluid L-glutamate levels is therefore imperative, in order to maintain optimal neurotransmission and to avoid such excitotoxicity. The blood-brain barrier, i.e., the endothelial lining of the brain capillaries...... cells. The mechanisms underlying transendothelial L-glutamate transport are however still not well understood. The present chapter summarizes the current knowledge on blood-brain barrier L-glutamate transporters and the suggested pathways for the brain-to-blood L-glutamate efflux....

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    Astrocytes take up glutamate in the synaptic area subsequent to glutamatergic transmission by the aid of high affinity glutamate transporters. Glutamate is converted to glutamine or metabolized to support intermediary metabolism and energy production. Glutamate dehydrogenase (GDH) and aspartate...... synthesis of aspartate via pyruvate carboxylation. In the absence of glucose, lactate production from glutamate via malic enzyme was lower in GDH deficient astrocytes. In conclusions, our studies reveal that metabolism via GDH serves an important anaplerotic role by adding net carbon to the TCA cycle...

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

    Science.gov (United States)

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

    2017-09-05

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

  13. Connexins and the kidney

    DEFF Research Database (Denmark)

    Hanner, Fiona; Sørensen, Charlotte Mehlin; Holstein-Rathlou, Niels-Henrik

    2010-01-01

    Connexins (Cxs) are widely-expressed proteins that form gap junctions in most organs, including the kidney. In the renal vasculature, Cx37, Cx40, Cx43, and Cx45 are expressed, with predominant expression of Cx40 in the endothelial cells and Cx45 in the vascular smooth muscle cells. In the tubules......, the major function of Cxs in the kidney appears to be intercellular communication, although they may also form hemichannels that allow cellular secretion of large signaling molecules. Renal Cxs facilitate vascular conduction, juxtaglomerular apparatus calcium signaling, and tubular purinergic signaling....... Accordingly, current evidence points to roles for these Cxs in several important regulatory mechanisms in the kidney, including the renin angiotensin system, tubuloglomerular feedback, and salt and water reabsorption. At the systemic level, renal Cxs may help regulate blood pressure and may be involved...

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Miranda van der Zeyden

    2008-11-01

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

  16. Localisation of novel forms of glutamate transporters and the cystine-glutamate antiporter in the choroid plexus: Implications for CSF glutamate homeostasis

    Science.gov (United States)

    Lee, Aven; Anderson, Ashley R.; Rayfield, Andrew J.; Stevens, Melissa G.; Poronnik, Philip; Meabon, James S.; Cook, David G.; Pow, David V.

    2012-01-01

    The choroid plexus is a structure within each ventricle of the brain that is composed of fenestrated vessels surrounded by secretory epithelial cells. The epithelial cells are linked by tight junctions to create a permeability barrier. The epithelial cells are derived from neuroectoderm, and are thus defined by some authors as a subtype of macroglia. Glutamate is a tightly regulated substance in the CSF, as it is in the rest of the brain. In the brain macroglia express multiple sodium dependent and independent glutamate transporters and are the main regulators of extracellular glutamate. However, the identities of the transporters in the choroid plexus and their localisations have remained poorly defined. In this study we examined the expression and distribution of multiple splice variants of classical sodium-dependent glutamate transporters, as well as the cystine-glutamate antiporter, and the PDZ protein NHERF1, (which acts as a molecular anchor for proteins such as the glutamate transporter GLAST). We identified three forms of sodium-dependent transporters (GLAST1a, GLAST1c and GLT1b) that are expressed at the apical surface of the epithelial cells, a location that matches the distribution of NHERF1 and the cystine-glutamate antiporter. We propose that this coincident localisation of GLAST1a/GLAST1c/GLT1b and the cystine-glutamate antiporter would permit the cyclical trafficking of glutamate and thus optimise the accumulation of cystine for the formation of glutathione in the choroid plexus. PMID:21982839

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  20. Monosodium glutamate 'allergy': menace or myth?

    Science.gov (United States)

    Williams, A N; Woessner, K M

    2009-05-01

    Monosodium glutamate (MSG) is a salt form of a non-essential amino acid commonly used as a food additive for its unique flavour enhancing qualities. Since the first description of the 'Monosodium glutamate symptom complex', originally described in 1968 as the 'Chinese restaurant syndrome', a number of anecdotal reports and small clinical studies of variable quality have attributed a variety of symptoms to the dietary ingestion of MSG. Descriptions of MSG-induced asthma, urticaria, angio-oedema, and rhinitis have prompted some to suggest that MSG should be an aetiologic consideration in patients presenting with these conditions. This review prevents a critical review of the available literature related to the possible role of MSG in the so-called 'Chinese restaurant syndrome' and in eliciting asthmatic bronchospasm, urticaria, angio-oedema, and rhinitis. Despite concerns raised by early reports, decades of research have failed to demonstrate a clear and consistent relationship between MSG ingestion and the development of these conditions.

  1. The Glutamine-Glutamate/GABA Cycle

    DEFF Research Database (Denmark)

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

    2015-01-01

    The operation of a glutamine-glutamate/GABA cycle in the brain consisting of the transfer of glutamine from astrocytes to neurons and neurotransmitter glutamate or GABA from neurons to astrocytes is a well-known concept. In neurons, glutamine is not only used for energy production and protein...... synthesis, as in other cells, but is also an essential precursor for biosynthesis of amino acid neurotransmitters. An excellent tool for the study of glutamine transfer from astrocytes to neurons is [(14)C]acetate or [(13)C]acetate and the glial specific enzyme inhibitors, i.e. the glutamine synthetase...... 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...

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

    Science.gov (United States)

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

    2017-04-01

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

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Dougherty Patrick M

    2009-07-01

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

  5. From the Cover: Glutamate antagonists limit tumor growth

    Science.gov (United States)

    Rzeski, Wojciech; Turski, Lechoslaw; Ikonomidou, Chrysanthy

    2001-05-01

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

  6. Protons Regulate Vesicular Glutamate Transporters through an Allosteric Mechanism.

    Science.gov (United States)

    Eriksen, Jacob; Chang, Roger; McGregor, Matt; Silm, Katlin; Suzuki, Toshiharu; Edwards, Robert H

    2016-05-18

    The quantal nature of synaptic transmission requires a mechanism to transport neurotransmitter into synaptic vesicles without promoting non-vesicular efflux across the plasma membrane. Indeed, the vesicular transport of most classical transmitters involves a mechanism of H(+) exchange, which restricts flux to acidic membranes such as synaptic vesicles. However, vesicular transport of the principal excitatory transmitter glutamate depends primarily on membrane potential, which would drive non-vesicular efflux, and the role of protons is unclear. Adapting electrophysiology to record currents associated with the vesicular glutamate transporters (VGLUTs), we characterize a chloride conductance that is gated by lumenal protons and chloride and supports glutamate uptake. Rather than coupling stoichiometrically to glutamate flux, lumenal protons and chloride allosterically activate vesicular glutamate transport. Gating by protons serves to inhibit what would otherwise be substantial non-vesicular glutamate efflux at the plasma membrane, thereby restricting VGLUT activity to synaptic vesicles. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Depersonalization disorder may be related to glutamate receptor activation imbalance.

    Science.gov (United States)

    Pikwer, Andreas

    2011-10-01

    Low-dose ketamine administration mimics, both clinically and on gross neuroimaging, depersonalization disorder. The perceptual effects of ketamine may be due to secondary stimulation of glutamate release and lamotrigine, possibly by inhibited glutamate release, may reduce some of ketamine's so-called dissociative effects. However, lamotrigine does not seem to be useful in the treatment of depersonalization disorder. Glutamate release in prefrontal cortex is increased by subanaesthetic doses of ketamine, resulting in increased inhibition, possibly via intercalated GABAerg cells, of projections from amygdala, affecting structures critically involved in depersonalization. I speculate that, in depersonalization disorder, the increased glutamate activity in prefrontal cortex is due to intrinsic imbalance, resulting in long-term potentiation, at the postsynaptic glutamate receptors on the GABAerg interneurons while the same receptor abnormality at the synapses on the intercalated GABAerg cells of the amygdala result in long-term depression in the case of either normal or high glutamate release. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2015-01-01

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

  9. Increased expression of cystine/glutamate antiporter in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Villoslada Pablo

    2011-06-01

    Full Text Available Abstract Background Glutamate excitotoxicity contributes to oligodendrocyte and tissue damage in multiple sclerosis (MS. Intriguingly, glutamate level in plasma and cerebrospinal fluid of MS patients is elevated, a feature which may be related to the pathophysiology of this disease. In addition to glutamate transporters, levels of extracellular glutamate are controlled by cystine/glutamate antiporter xc-, an exchanger that provides intracellular cystine for production of glutathione, the major cellular antioxidant. The objective of this study was to analyze the role of the system xc- in glutamate homeostasis alterations in MS pathology. Methods Primary cultures of human monocytes and the cell line U-937 were used to investigate the mechanism of glutamate release. Expression of cystine glutamate exchanger (xCT was quantified by quantitative PCR, Western blot, flow cytometry and immunohistochemistry in monocytes in vitro, in animals with experimental autoimmune encephalomyelitis (EAE, the animal model of MS, and in samples of MS patients. Results and discussion We show here that human activated monocytes release glutamate through cystine/glutamate antiporter xc- and that the expression of the catalytic subunit xCT is upregulated as a consequence of monocyte activation. In addition, xCT expression is also increased in EAE and in the disease proper. In the later, high expression of xCT occurs both in the central nervous system (CNS and in peripheral blood cells. In particular, cells from monocyte-macrophage-microglia lineage have higher xCT expression in MS and in EAE, indicating that immune activation upregulates xCT levels, which may result in higher glutamate release and contribution to excitotoxic damage to oligodendrocytes. Conclusions Together, these results reveal that increased expression of the cystine/glutamate antiporter system xc- in MS provides a link between inflammation and excitotoxicity in demyelinating diseases.

  10. Modeling of glutamic acid production by Lactobacillus plantarum MNZ

    OpenAIRE

    Zareian,Mohsen; Ebrahimpour,Afshin; Mohamed, Abdul Karim Sabo; Saari, Nazamid

    2013-01-01

    Background: L-glutamic acid, the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism acts as a precursor of γ-amino butyric acid (GABA). In the present study, culture condition for enhanced glutamic acid production by Lactobacillus plantarum MNZ was optimized and the influence of such conditions on GABA production was evaluated. Results: Results indicated that glutamic acid increased up to 3-fold (3.35) under the following condition: pH 4.5, tem...

  11. 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.

  12. Glutamate transporter: an unexpected target for some antibiotics.

    Science.gov (United States)

    Mao, Jianren

    2005-02-09

    Glutamate transporter (GT) plays a major role in the mechanisms of glutamate homeostasis. Can this transporter system be a therapeutic target for glutamate-mediated neurological disorders? In January's edition of Nature, Rothstein et al (2005) reports that the most commonly used class of antibiotics (beta-lactam antibiotics) such as ceftriaxone promoted the expression of GLT1 and demonstrated a functional role in both in vitro and in vivo models of glutamate neurotoxicity. These findings indicate that positive promoters of GT expression may have a unique role in neuroprotection through regulating GT expression. This is also encouraging in search for new pharmacological tools for pain management.

  13. Glutamate. Its applications in food and contribution to health.

    Science.gov (United States)

    Jinap, S; Hajeb, P

    2010-08-01

    This article reviews application of glutamate in food and its benefits and role as one of the common food ingredients used. Monosodium glutamate is one of the most abundant naturally occurring amino acids which frequently added as a flavor enhancer. It produced a unique taste that cannot be provided by other basic taste (saltiness, sourness, sweetness and bitterness), referred to as a fifth taste (umami). Glutamate serves some functions in the body as well, serving as an energy source for certain tissues and as a substrate for glutathione synthesis. Glutamate has the potential to enhance food intake in older individuals and dietary free glutamate evoked a visceral sensation from the stomach, intestine and portal vein. Small quantities of glutamate used in combination with a reduced amount of table salt during food preparation allow for far less salt to be used during and after cooking. Because glutamate is one of the most intensely studied food ingredients in the food supply and has been found safe, the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization and World Health Organization placed it in the safest category for food additives. Despite a widespread belief that glutamate can elicit asthma, migraine headache and Chinese Restaurant Syndrome (CRS), there are no consistent clinical data to support this claim. In addition, findings from the literature indicate that there is no consistent evidence to suggest that individuals may be uniquely sensitive to glutamate. 2010 Elsevier Ltd. All rights reserved.

  14. How Glutamate Is Managed by the Blood–Brain Barrier

    Directory of Open Access Journals (Sweden)

    Richard A. Hawkins

    2016-10-01

    Full Text Available A facilitative transport system exists on the blood–brain barrier (BBB that has been tacitly assumed to be a path for glutamate entry to the brain. However, glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter the brain in appreciable quantities except in those small regions with fenestrated capillaries (circumventricular organs. The situation became understandable when luminal (blood facing and abluminal (brain facing membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exists only on the luminal membranes, whereas Na+-dependent transport systems for glutamate, glutamine, and some other amino acids are present only on the abluminal membrane. The Na+-dependent cotransporters of the abluminal membrane are in a position to actively transport amino acids from the extracellular fluid (ECF into the endothelial cells of the BBB. These powerful secondary active transporters couple with the energy of the Na+-gradient to move glutamate and glutamine into endothelial cells, whereupon glutamate can exit to the blood on the luminal facilitative glutamate transporter. Glutamine may also exit the brain via separate facilitative transport system that exists on the luminal membranes, or glutamine can be hydrolyzed to glutamate within the BBB, thereby releasing ammonia that is freely diffusible. The γ-glutamyl cycle participates indirectly by producing oxoproline (pyroglutamate, which stimulates almost all secondary active transporters yet discovered in the abluminal membranes of the BBB.

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

    DEFF Research Database (Denmark)

    Christgau, Stephan; Odderhede, Jette; Stahl, Kenny

    2005-01-01

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

  16. Glutamate concentration in whole saliva and taste responses to monosodium glutamate in humans.

    Science.gov (United States)

    Scinska-Bienkowska, A; Wrobel, E; Turzynska, D; Bidzinski, A; Jezewska, E; Sienkiewicz-Jarosz, H; Golembiowska, K; Kostowski, W; Kukwa, A; Plaznik, A; Bienkowski, P

    2006-01-01

    It is universally accepted that saliva plays an important role in taste sensations. However, interactions between constituents of whole saliva and the five basic taste modalities are still poorly understood. The aim of the present study was to evaluate possible relationship between endogenous glutamate (Glu) levels in whole saliva and taste responses to a prototypic umami substance, monosodium glutamate (MSG; 0.03-10.0%). Rated intensity and pleasantness of MSG taste was studied in healthy volunteers divided into a high glutamate (HG) in saliva (HG; n = 19) and low glutamate in saliva (LG; n = 18) group based on the median split level of salivary Glu. The HG and LG group did not differ in terms of electrogustometric thresholds, rated intensity of the MSG samples and pleasantness of distilled water and the lower MSG concentrations (0.03-1.0%). Perceived intensity of water taste was significantly (P < 0.05) higher in the LG subjects. The LG group rated the higher MSG concentrations (3.0-10.0%) as more unpleasant (P < 0.01). The difference remained significant after controlling for a between-group difference in age. The present results suggest that individual differences in salivary Glu levels may alter hedonic responses to suprathreshold MSG concentrations.

  17. Rat odontoblasts may use glutamate to signal dentin injury.

    Science.gov (United States)

    Cho, Yi Sul; Ryu, Chang Hyun; Won, Jong Hwa; Vang, Hue; Oh, Seog Bae; Ro, Jin Young; Bae, Yong Chul

    2016-10-29

    Accumulating evidence indicates that odontoblasts act as sensor cells, capable of triggering action potentials in adjacent pulpal nociceptive axons, suggesting a paracrine signaling via a currently unknown mediator. Since glutamate can mediate signaling by non-neuronal cells, and peripheral axons may express glutamate receptors (GluR), we hypothesized that the expression of high levels of glutamate, and of sensory receptors in odontoblasts, combined with an expression of GluR in adjacent pulpal axons, is the morphological basis for odontoblastic sensory signaling. To test this hypothesis, we investigated the expression of glutamate, the thermo- and mechanosensitive ion channels transient receptor potential vanilloid 1 (TRPV1), transient receptor potential ankyrin 1 (TRPA1), and TWIK-1-related K+channel (TREK-1), and the glutamate receptor mGluR5, in a normal rat dental pulp, and following dentin injury. We also examined the glutamate release from odontoblast in cell culture. Odontoblasts were enriched with glutamate, at the level as high as in adjacent pulpal axons, and showed immunoreactivity for TRPV1, TRPA1, and TREK-1. Pulpal sensory axons adjacent to odontoblasts expressed mGluR5. Both the levels of glutamate in odontoblasts, and the expression of mGluR5 in nearby axons, were upregulated following dentin injury. The extracellular glutamate concentration was increased significantly after treating of odontoblast cell line with calcium permeable ionophore, suggesting glutamate release from odontoblasts. These findings lend morphological support to the hypothesis that odontoblasts contain glutamate as a potential neuroactive substance that may activate adjacent pulpal axons, and thus contribute to dental pain and hypersensitivity. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  18. Identification and characterization of a bacterial glutamic peptidase

    Directory of Open Access Journals (Sweden)

    Jensen Kenneth

    2010-12-01

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

  19. Linking tricyclic antidepressants to ionotropic glutamate receptors.

    Science.gov (United States)

    Stoll, Laura; Gentile, Lisa

    2005-07-29

    Although tricyclic antidepressants have been in existence since the 1940s when they were discovered upon screening iminodibenzyl derivatives for other potential therapeutic uses, their mechanism of action has remained unclear [A. Goodman Gilman, T.W. Rall, A.S. Nies, P. Taylor, Goodman and Gilman's The Pharmacological Basis of Therapeutics, eighth ed., Pergamon Press, New York, 1990]. In addition to their ability to hinder the reuptake of biogenic amines, there is mounting evidence that the tricyclic antidepressants inhibit glutamate transmission. Here, intrinsic tryptophan fluorescence spectroscopy is used to document the binding of desipramine, a member of the tricyclic antidepressant family, to a well-defined extracellular glutamate binding domain (S1S2) of the GluR2 subunit of the amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. The binding is distinct from those of other known effectors of the receptor, including the endogenous sulfated neurosteroids pregnenolone sulfate and 3alpha-hydroxy-5beta-pregnan-20-one sulfate, and is consistent with a conformational change upon binding that is allosterically transmitted to the channel region of the receptor.

  20. 21 CFR 522.1125 - Hemoglobin glutamer-200 (bovine).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hemoglobin glutamer-200 (bovine). 522.1125 Section... § 522.1125 Hemoglobin glutamer-200 (bovine). (a) Specifications. Each 125 milliliter bag contains 13 grams per deciliter of polymerized hemoglobin of bovine origin in modified Lactated Ringer's Solution...

  1. Electrochemical Synthesis of Polypyrrole Layers Doped with Glutamic Ions

    NARCIS (Netherlands)

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

    2009-01-01

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

  2. A review of glutamate's role in traumatic brain injury mechanisms

    Science.gov (United States)

    Good, Cameron H.

    2013-05-01

    Glutamate is the primary excitatory neurotransmitter used by the central nervous system (CNS) for synaptic communication, and its extracellular concentration is tightly regulated by glutamate transporters located on nearby astrocytes. Both animal models and human clinical studies have demonstrated elevated glutamate levels immediately following a traumatic brain event, with the duration and severity of the rise corresponding to prognosis. This rise in extracellular glutamate likely results from a combination of excessive neurotransmitter release from damaged neurons and down regulation of uptake mechanisms in local astrocytes. The immediate results of a traumatic event can lead to necrotic tissue in severely injured regions, while prolonged increases in excitatory transmission can cause secondary excitotoxic injury through activation of delayed apoptotic pathways. Initial TBI animal studies utilized a variety of broad glutamate receptor antagonists to successfully combat secondary injury mechanisms, but unfortunately this same strategy has proven inconclusive in subsequent human trials due to deleterious side effects and heterogeneity of injuries. More recent treatment strategies have utilized specific glutamate receptor subunit antagonists in an effort to minimize side effects and have shown promising results. Future challenges will be detecting the concentration and kinetics of the glutamate rise following injury, determining which patient populations could benefit from antagonist treatment based on their extracellular glutamate concentrations and when drugs should be administered to maximize efficacy.

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

    NARCIS (Netherlands)

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

    2001-01-01

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

  4. changes in activities of enzymes of glutamate metabolism in rat ...

    African Journals Online (AJOL)

    regions of brain under sub-acute dosing. Glutamine Synthetase. Glutamine synthetase converts glutamate into glutamine, and glutamine levels in neural tissues help in the m~intenance of glutamate concentration for its general .. function as an amino acid as well as for the neurotransmitter poo! (Shank and. Aprison, 1981 ).

  5. Glutamate Efflux at the Blood-Brain Barrier

    DEFF Research Database (Denmark)

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

    2014-01-01

    L-Glutamate is considered the most important excitatory amino acid in the mammalian brain. Strict control of its concentration in the brain interstitial fluid is important to maintain neurotransmission and avoid excitotoxicity. The role of astrocytes in handling L-glutamate transport and metaboli...

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

    African Journals Online (AJOL)

    Keywords: ammonia assimilation, glutamate dehydrogenase, GDH, Gracilaria sordida, red alga, enzyme activity. Glutamate ... NAD-/NADP- and NADH-/ NADPH-dependent activities were the order of 11:1 and 1:1.8, respectively. The pH optima for ... This work is licensed under a Creative Commons Attribution 3.0 License.

  7. Study on soluble expression of glutamate dehydrogenase from tea ...

    African Journals Online (AJOL)

    Yomi

    2012-03-20

    Mar 20, 2012 ... Glutamate dehydrogenase (GDH; EC1.4.1.2) catalyses the reversible amination of 2-oxoglutarate for the synthesis of glutamate using ... CsGDH2 was predominantly found in insoluble bodies and no soluble protein was detected by either .... phosphatase (TAP) to remove the 50 cap structure from intact full-.

  8. 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

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

    African Journals Online (AJOL)

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

  10. Microscopic picture of the aqueous solvation of glutamic acid

    NARCIS (Netherlands)

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

    2008-01-01

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

  11. Amiodarone reduces depolarization-evoked glutamate release from hippocampual synaptosomes

    Directory of Open Access Journals (Sweden)

    Chia Yu Chang

    2017-03-01

    Full Text Available Decreased brain glutamate level has emerged as a new therapeutic approach for epilepsy. This study investigated the effect and mechanism of amiodarone, an anti-arrhythmic drug with antiepileptic activity, on glutamate release in the rat hippocampus. In a synaptosomal preparation, amiodarone reduced 4-aminopyridine-evoked Ca2+-dependent glutamate release and cytosolic Ca2+ concentration elevation. Amiodarone did not affect the 4-aminopyridine-evoked depolarization of the synaptosomal membrane potential or the Na+ channel activator veratridine-evoked glutamate release, indicating that the amiodarone-mediated inhibition of glutamate release is not caused by a decrease in synaptosomal excitability. The inhibitory effect of amiodarone on 4-aminopyridine-evoked glutamate release was markedly decreased in synaptosomes pretreated with the Cav2.2 (N-type and Cav2.1 (P/Q-type channel blocker ω-conotoxin MVIIC, the calmodulin antagonists W7 and calmidazolium, or the protein kinase A inhibitors H89 and KT5720. However, the intracellular Ca2+-release inhibitors dantrolene and CGP37157 had no effect on the amiodarone-mediated inhibition of glutamate release. Furthermore, amiodarone reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude in hippocampal slices. Our data suggest that amiodarone reduces Ca2+ influx through N- and P/Q-type Ca2+ channels, subsequently reducing the Ca2+-calmodulin/protein kinase A cascade to inhibit the evoked glutamate release from rat hippocampal nerve terminals.

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

    African Journals Online (AJOL)

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

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

    Science.gov (United States)

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

    2017-11-25

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

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

    Science.gov (United States)

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

    2016-11-01

    There are indications for changes in glutamate metabolism in relation to depression or suicide. The glutamate-glutamine cycle and neuronal/glial glutamate transporters mediate the uptake of the glutamate and glutamine. The expression of various components of the glutamate-glutamine cycle and the neuronal/glial glutamate transporters was determined by qPCR in postmortem prefrontal cortex. The anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC) were selected from young MDD patients who had committed suicide (MDD-S; n = 17), from MDD patients who died of non-suicide related causes (MDD-NS; n = 7) and from matched control subjects (n = 12). We also compared elderly depressed patients who had not committed suicide (n = 14) with matched control subjects (n = 22). We found that neuronal located components (EAAT3, EAAT4, ASCT1, SNAT1, SNAT2) of the glutamate-glutamine cycle were increased in the ACC while the astroglia located components (EAAT1, EAAT2, GLUL) were decreased in the DLPFC of MDD-S patients. In contrast, most of the components in the cycle were increased in the DLPFC of MDD-NS patients. In conclusion, the glutamate-glutamine cycle - and thus glutamine transmission - is differentially affected in depressed suicide patients and depressed non-suicide patients in an area specific way. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Reciprocal Regulation of Epileptiform Neuronal Oscillations and Electrical Synapses in the Rat Hippocampus

    Science.gov (United States)

    Kinjo, Erika R.; Higa, Guilherme S. V.; Morya, Edgard; Valle, Angela C.; Kihara, Alexandre H.; Britto, Luiz R. G.

    2014-01-01

    Gap junction (GJ) channels have been recognized as an important mechanism for synchronizing neuronal networks. Herein, we investigated the participation of GJ channels in the pilocarpine-induced status epilepticus (SE) by analyzing electrophysiological activity following the blockade of connexins (Cx)-mediated communication. In addition, we examined the regulation of gene expression, protein levels, phosphorylation profile and distribution of neuronal Cx36, Cx45 and glial Cx43 in the rat hippocampus during the acute and latent periods. Electrophysiological recordings revealed that the GJ blockade anticipates the occurrence of low voltage oscillations and promotes a marked reduction of power in all analyzed frequencies.Cx36 gene expression and protein levels remained stable in acute and latent periods, whereas upregulation of Cx45 gene expression and protein redistribution were detected in the latent period. We also observed upregulation of Cx43 mRNA levels followed by changes in the phosphorylation profile and protein accumulation. Taken together, our results indisputably revealed that GJ communication participates in the epileptiform activity induced by pilocarpine. Moreover, considering that specific Cxs undergo alterations through acute and latent periods, this study indicates that the control of GJ communication may represent a focus in reliable anti-epileptogenic strategies. PMID:25299405

  16. Altered Connexin 43 and Connexin 45 protein expression in the heart as a function of social and environmental stress in the prairie vole.

    Science.gov (United States)

    Grippo, Angela J; Moffitt, Julia A; Henry, Matthew K; Firkins, Rachel; Senkler, Jonathan; McNeal, Neal; Wardwell, Joshua; Scotti, Melissa-Ann L; Dotson, Ashley; Schultz, Rachel

    2015-01-01

    Exposure to social and environmental stressors may influence behavior as well as autonomic and cardiovascular regulation, potentially leading to depressive disorders and cardiac dysfunction including elevated sympathetic drive, reduced parasympathetic function, and ventricular arrhythmias. The cellular mechanisms that underlie these interactions are not well understood. One mechanism may involve alterations in the expression of Connexin43 (Cx43) and Connexin45 (Cx45), gap junction proteins in the heart that play an important role in ensuring efficient cell-to-cell coupling and the maintenance of cardiac rhythmicity. The present study investigated the hypothesis that long-term social isolation, combined with mild environmental stressors, would produce both depressive behaviors and altered Cx43 and Cx45 expression in the left ventricle of prairie voles - a socially monogamous rodent model. Adult, female prairie voles were exposed to either social isolation (n = 22) or control (paired, n = 23) conditions (4 weeks), alone or in combination with chronic mild stress (CMS) (1 week). Social isolation, versus paired control conditions, produced significantly (p Social isolation (alone) reduced (p social and environmental stress in the prairie vole.

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

    Science.gov (United States)

    Rojas, Donald C.

    2014-01-01

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

  18. 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.

  19. Poly(γ-glutamic acid), coagulation? Anticoagulation?

    Science.gov (United States)

    Xu, Tingting; Peng, Fang; Zhang, Tao; Chi, Bo; Xu, Hong; Mao, Chun; Feng, Shuaihui

    2016-11-01

    Poly(γ-glutamic acid) (γ-PGA) powder was usually used as hemostatic agent because of its excellent physical properties of water-absorption and water-locking. However, if γ-PGA absorbs enough water, how about its blood compatibility? Here, the other side of the coin was investigated. The anticoagulant properties of γ-PGA were characterized by in vitro coagulation tests, hemolytic assay, platelet adhesion, and platelet activation. Moreover, cytotoxicity experiments of γ-PGA were also carried out by MTT assay. Results indicated that the sufficient water-absorbed γ-PGA has good anticoagulant property and non-cytotoxicity. It means γ-PGA has good anticoagulant property, non-cytotoxicity. If γ-PGA has absorbed enough water, it can be used as an anticoagulation biomaterial. With double effects (coagulation and anticoagulation), the γ-PGA with desirable bioproperties can be readily tailored to cater to various biomedical applications.

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

    Science.gov (United States)

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

    2016-04-01

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

  1. 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.

  2. 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.

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

    Science.gov (United States)

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

    2015-12-01

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

  4. Targeting glutamate signalling in depression: progress and prospects.

    Science.gov (United States)

    Murrough, James W; Abdallah, Chadi G; Mathew, Sanjay J

    2017-07-01

    Major depressive disorder (MDD) is severely disabling, and current treatments have limited efficacy. The glutamate N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine was recently repurposed as a rapidly acting antidepressant, catalysing the vigorous investigation of glutamate-signalling modulators as novel therapeutic agents for depressive disorders. In this Review, we discuss the progress made in the development of such modulators for the treatment of depression, and examine recent preclinical and translational studies that have investigated the mechanisms of action of glutamate-targeting antidepressants. Fundamental questions remain regarding the future prospects of this line of drug development, including questions concerning safety and tolerability, efficacy, dose-response relationships and therapeutic mechanisms.

  5. Clearance of glutamate inside the synapse and beyond.

    Science.gov (United States)

    Bergles, D E; Diamond, J S; Jahr, C E

    1999-06-01

    The heated debate over the level of postsynaptic receptor occupancy by transmitter has not been extinguished - indeed, new evidence is fanning the flames. Recent experiments using two-photon microscopy suggest that the concentration of glutamate in the synaptic cleft does not attain levels previously suggested. In contrast, recordings from glial cells and studies of extrasynaptic receptor activation indicate that significant quantities of glutamate escape from the cleft following exocytosis. Determining the amount of glutamate efflux from the synaptic cleft and the distance it diffuses is critical to issues of synaptic specificity and the induction of synaptic plasticity.

  6. 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.

  7. The Influence of Glutamate on Axonal Compound Action Potential In Vitro.

    Science.gov (United States)

    Abouelela, Ahmed; Wieraszko, Andrzej

    2016-01-01

    Background  Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives  The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods  Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results  The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion  The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.

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

    Directory of Open Access Journals (Sweden)

    Emmanuelle Goubert

    2017-05-01

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

  9. Glutamate neurotransmission is affected in prenatally stressed offspring

    DEFF Research Database (Denmark)

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

    2015-01-01

    with synaptic loss. Since metabolism of glutamate is dependent on interactions between neurons and surrounding astroglia, our results suggest that glutamate neurotransmitter pathways might be impaired in the brain of prenatally stressed rats. To study the effect of prenatal stress on the metabolism...... uptake capacity for glutamate in the FCx of PS male offspring while no such changes were observed in the HPC. The results show that changes mediated by PS on the adult glutamatergic system are brain region specific. Overall, PS produces long-term changes in the glutamatergic system modulating......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...

  10. Modeling of glutamic acid production by Lactobacillus plantarum MNZ

    National Research Council Canada - National Science Library

    Zareian, Mohsen; Ebrahimpour, Afshin; Mohamed, Abdul Karim Sabo; Saari, Nazamid

    2014-01-01

    ...-amino butyric acid (GABA). In the present study, culture condition for enhanced glutamic acid production by Lactobacillus plantarum MNZ was optimized and the influence of such conditions on GABA production was evaluated. Results...

  11. Receptors of glutamate and neurotrophin in vestibular neuronal functions.

    Science.gov (United States)

    Chan, Y S; Chen, L W; Lai, C H; Shum, D K Y; Yung, K K L; Zhang, F X

    2003-01-01

    The last decade has witnessed advances in understanding the roles of receptors of neurotrophin and glutamate in the vestibular system. In the first section of this review, the biological actions of neurotrophins and their receptors in the peripheral and central vestibular systems are summarized. Emphasis will be placed on the roles of neurotrophins in developmental plasticity and in the maintenance of vestibular function in the adult animal. This is reviewed in relation to the developmental expression pattern of neurotrophins and their receptors within the vestibular nuclei. The second part is focused on the functional role of different glutamate receptors on central vestibular neurons. The developmental expression pattern of glutamate receptor subunits within the vestibular nuclei is reviewed in relation to the potential role of glutamate receptors in regulating the development of vestibular function. Copyright 2003 National Science Council, ROC and S. Karger AG, Basel

  12. Bidirectional Control of Synaptic GABAAR Clustering by Glutamate and Calcium

    Directory of Open Access Journals (Sweden)

    Hiroko Bannai

    2015-12-01

    Full Text Available GABAergic synaptic transmission regulates brain function by establishing the appropriate excitation-inhibition (E/I balance in neural circuits. The structure and function of GABAergic synapses are sensitive to destabilization by impinging neurotransmitters. However, signaling mechanisms that promote the restorative homeostatic stabilization of GABAergic synapses remain unknown. Here, by quantum dot single-particle tracking, we characterize a signaling pathway that promotes the stability of GABAA receptor (GABAAR postsynaptic organization. Slow metabotropic glutamate receptor signaling activates IP3 receptor-dependent calcium release and protein kinase C to promote GABAAR clustering and GABAergic transmission. This GABAAR stabilization pathway counteracts the rapid cluster dispersion caused by glutamate-driven NMDA receptor-dependent calcium influx and calcineurin dephosphorylation, including in conditions of pathological glutamate toxicity. These findings show that glutamate activates distinct receptors and spatiotemporal patterns of calcium signaling for opposing control of GABAergic synapses.

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

    Science.gov (United States)

    Henry-Unaeze, Helen Nonye

    2017-12-01

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

  14. Glutamic Acid Selective Chemical Cleavage of Peptide Bonds.

    Science.gov (United States)

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

    2016-03-04

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

  15. Monosodium glutamate is not likely to be genotoxic.

    Science.gov (United States)

    Rogers, Michael D

    2016-08-01

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

  16. Amiodarone reduces depolarization-evoked glutamate release from hippocampual synaptosomes.

    Science.gov (United States)

    Chang, Chia Yu; Hung, Chi Feng; Huang, Shu Kuei; Kuo, Jinn Rung; Wang, Su Jane

    2017-03-01

    Decreased brain glutamate level has emerged as a new therapeutic approach for epilepsy. This study investigated the effect and mechanism of amiodarone, an anti-arrhythmic drug with antiepileptic activity, on glutamate release in the rat hippocampus. In a synaptosomal preparation, amiodarone reduced 4-aminopyridine-evoked Ca2+-dependent glutamate release and cytosolic Ca2+ concentration elevation. Amiodarone did not affect the 4-aminopyridine-evoked depolarization of the synaptosomal membrane potential or the Na+ channel activator veratridine-evoked glutamate release, indicating that the amiodarone-mediated inhibition of glutamate release is not caused by a decrease in synaptosomal excitability. The inhibitory effect of amiodarone on 4-aminopyridine-evoked glutamate release was markedly decreased in synaptosomes pretreated with the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, the calmodulin antagonists W7 and calmidazolium, or the protein kinase A inhibitors H89 and KT5720. However, the intracellular Ca2+-release inhibitors dantrolene and CGP37157 had no effect on the amiodarone-mediated inhibition of glutamate release. Furthermore, amiodarone reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude in hippocampal slices. Our data suggest that amiodarone reduces Ca2+ influx through N- and P/Q-type Ca2+ channels, subsequently reducing the Ca2+-calmodulin/protein kinase A cascade to inhibit the evoked glutamate release from rat hippocampal nerve terminals. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  17. A Glio-Protective Role of mir-263a by Tuning Sensitivity to Glutamate

    DEFF Research Database (Denmark)

    Aw, Sherry Shiying; Lim, Isaac Kok Hwee; Tang, Melissa Xue Mei

    2017-01-01

    Glutamate is a ubiquitous neurotransmitter, mediating information flow between neurons. Defects in the regulation of glutamatergic transmission can result in glutamate toxicity, which is associated with neurodegeneration. Interestingly, glutamate receptors are expressed in glia, but little is kno...... of glutamate receptor levels protects glia from excitotoxicity, ensuring CNS health. Chronic low-level glutamate receptor overexpression due to mutations affecting microRNA (miRNA) regulation might contribute to glial dysfunction and CNS impairment....

  18. Glutamate Receptor Ion Channels: Structure, Regulation, and Function

    Science.gov (United States)

    Wollmuth, Lonnie P.; McBain, Chris J.; Menniti, Frank S.; Vance, Katie M.; Ogden, Kevin K.; Hansen, Kasper B.; Yuan, Hongjie; Myers, Scott J.; Dingledine, Ray

    2010-01-01

    The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors. PMID:20716669

  19. In vitro evidence for the brain glutamate efflux hypothesis

    DEFF Research Database (Denmark)

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

    2012-01-01

    The concentration of the excitotoxic amino acid, L-glutamate, in brain interstitial fluid is tightly regulated by uptake transporters and metabolism in astrocytes and neurons. The aim of this study was to investigate the possible role of the blood-brain barrier endothelium in brain L-glutamate ho......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...... was shown with immunofluorescence. Overall, the findings suggest that the blood-brain barrier itself may participate in regulating brain L-glutamate concentrations. © 2012 Wiley Periodicals, Inc....

  20. [Glutamic acid as a universal extracellular signal].

    Science.gov (United States)

    Yoneda, Yukio

    2015-08-01

    The prevailing view is that both glutamic (Glu) and gamma-aminobutyric (GABA) acids play a role as an amino acid neurotransmitter released from neurons. However, little attention has been paid to the possible expression and functionality of signaling machineries required for amino acidergic neurotransmission in cells other than central neurons. In line with our first demonstration of the presence of Glu receptors outside the brain, in this review I will outline our recent findings accumulated since then on the physiological and pathological significance of neuronal amino acids as an extracellular signal essential for homeostasis in a variety of phenotypic cells. In undifferentiated neural progenitor cells, for instance, functional expression is seen with different signaling machineries used for glutamatergic and GABAergic neurotransmission in neurons. Moreover, Glu plays a role in mechanisms underlying suppression of proliferation for self-replication in undifferentiated mesenchymal stem cells. There is more accumulating evidence for neuronal amino acids playing a role as an extracellular autocrine or paracrine signal commonly used in different phenotypic cells. Evaluation of drugs currently used could be thus beneficial for the efficient prophylaxis and/or the therapy of a variety of diseases relevant to disturbance of amino acid signaling in diverse organs.

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

    Science.gov (United States)

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

    2017-05-22

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    -expressing transgenic mice. We measured glutamate uptake and metabolism using [(3) H]glutamate, while the effect on metabolic pathways of glutamate and glucose was evaluated by use of (13) C and (14) C substrates and analysis by mass spectrometry and determination of radioactively labeled metabolites...

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

    Science.gov (United States)

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

    2003-03-01

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

  4. Local anesthetics inhibit glutamate release from rat cerebral cortex synaptosomes.

    Science.gov (United States)

    Lin, Tzu-Yu; Chung, Chih-Yang; Lu, Cheng-Wei; Huang, Shu-Kuei; Shieh, Jiann-Sing; Wang, Su-Jane

    2013-09-01

    Local anesthetics have been widely used for regional anesthesia and the treatment of cardiac arrhythmias. Recent studies have also demonstrated that low-dose systemic local anesthetic infusion has neuroprotective properties. Considering the fact that excessive glutamate release can cause neuronal excitotoxicity, we investigated whether local anesthetics might influence glutamate release from rat cerebral cortex nerve terminals (synaptosomes). Results showed that two commonly used local anesthetics, lidocaine and bupivacaine, exhibited a dose-dependent inhibition of 4-AP-evoked release of glutamate. The effects of lidocaine or bupivacaine on the evoked glutamate release were prevented by the chelation of extracellular Ca²⁺ ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate did not have any effect on the action of lidocaine or bupivacaine. Both lidocaine and bupivacaine reduced the depolarization-induced increase in [Ca²⁺]C but did not alter 4-AP-mediated depolarization. Furthermore, the inhibitory effect of lidocaine or bupivacaine on evoked glutamate release was prevented by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but it was not affected by blocking of the ryanodine receptors or the mitochondrial Na⁺/Ca²⁺ exchange. Inhibition of protein kinase C (PKC) and protein kinase A (PKA) also prevented the action of lidocaine or bupivacaine. These results show that local anesthetics inhibit glutamate release from rat cortical nerve terminals. This effect is linked to a decrease in [Ca²⁺]C caused by Ca²⁺ entry through presynaptic voltage-dependent Ca²⁺ channels and the suppression of the PKA and PKC signaling cascades. Copyright © 2013 Wiley Periodicals, Inc.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  7. 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.

  8. 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.

  9. Glutamate excitotoxicity inflicts paranodal myelin splitting and retraction.

    Science.gov (United States)

    Fu, Yan; Sun, Wenjing; Shi, Yunzhou; Shi, Riyi; Cheng, Ji-Xin

    2009-08-20

    Paranodal myelin damage is observed in white matter injury. However the culprit for such damage remains unknown. By coherent anti-Stokes Raman scattering imaging of myelin sheath in fresh tissues with sub-micron resolution, we observed significant paranodal myelin splitting and retraction following glutamate application both ex vivo and in vivo. Multimodal multiphoton imaging further showed that glutamate application broke axo-glial junctions and exposed juxtaparanodal K+ channels, resulting in axonal conduction deficit that was demonstrated by compound action potential measurements. The use of 4-aminopyridine, a broad-spectrum K+ channel blocker, effectively recovered both the amplitude and width of compound action potentials. Using CARS imaging as a quantitative readout of nodal length to diameter ratio, the same kind of paranodal myelin retraction was observed with applications of Ca2+ ionophore A23187. Moreover, exclusion of Ca2+ from the medium or application of calpain inhibitor abolished paranodal myelin retraction during glutamate exposure. Examinations of glutamate receptor agonists and antagonists further showed that the paranodal myelin damage was mediated by NMDA and kainate receptors. These results suggest that an increased level of glutamate in diseased white matter could impair paranodal myelin through receptor-mediated Ca2+ overloading and subsequent calpain activation.

  10. Glutamate excitotoxicity inflicts paranodal myelin splitting and retraction.

    Directory of Open Access Journals (Sweden)

    Yan Fu

    2009-08-01

    Full Text Available Paranodal myelin damage is observed in white matter injury. However the culprit for such damage remains unknown. By coherent anti-Stokes Raman scattering imaging of myelin sheath in fresh tissues with sub-micron resolution, we observed significant paranodal myelin splitting and retraction following glutamate application both ex vivo and in vivo. Multimodal multiphoton imaging further showed that glutamate application broke axo-glial junctions and exposed juxtaparanodal K+ channels, resulting in axonal conduction deficit that was demonstrated by compound action potential measurements. The use of 4-aminopyridine, a broad-spectrum K+ channel blocker, effectively recovered both the amplitude and width of compound action potentials. Using CARS imaging as a quantitative readout of nodal length to diameter ratio, the same kind of paranodal myelin retraction was observed with applications of Ca2+ ionophore A23187. Moreover, exclusion of Ca2+ from the medium or application of calpain inhibitor abolished paranodal myelin retraction during glutamate exposure. Examinations of glutamate receptor agonists and antagonists further showed that the paranodal myelin damage was mediated by NMDA and kainate receptors. These results suggest that an increased level of glutamate in diseased white matter could impair paranodal myelin through receptor-mediated Ca2+ overloading and subsequent calpain activation.

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

    Science.gov (United States)

    Formánek, Pavel; Vranová, Valerie; Lojková, Lea

    2015-02-01

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

  12. The genetics of schizophrenia: glutamate not dopamine?

    Science.gov (United States)

    Collier, David A; Li, Tao

    2003-11-07

    The major targets of current drugs used in mental health, such as neurotransmitter receptors and transporters, are based on serendipitous findings from several decades ago, and there is currently a severe drought of new drug targets. There is a pressing need for novel drugs, and much hope has been placed on the use of molecular genetics to help define them. However, despite evidence for a genetic basis to schizophrenia stretching back for over a century, and a heritability of about 80%, the identification of susceptibility genes has been an uphill struggle. Candidate gene studies, which have generally focussed on obvious candidates from the dopamine and serotonin systems, as well as genes involved in brain development, have not generally been successful, although meta-analysis indicates that the dopamine D3 receptor gene (DRD3) and the serotonin receptor gene type 2A (HTR2A) may have a very small influence on risk. Linkage analysis has provided robust evidence of genetic loci, for example, on chromosomes 8p, 13q and 22q, and also implies shared genetic aetiology with bipolar disorder. The identification of these loci together with advances in genetic technology, especially the characterisation of polymorphisms, the understanding of haplotypes and the development of statistical methods, has lead to the identification of several plausible susceptibility genes, including neuregulin 1, proline dehydrogenase and dysbindin. Interestingly, these genes point more towards a role for the glutamate pathway rather than the dopamine pathway in schizophrenia. We have attempted to replicate some of these findings in schizophrenic patients from SW China, and we find significant association with a novel neuregulin 1 haplotype, with proline dehydrogenase polymorphisms, but not with catechol-O-methyltransferase (COMT). The replication of neuregulin 1 association on chromosome 8p by several investigators is the most convincing to date, and the presence of a syndrome similar to

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

    Science.gov (United States)

    Palucha, A; Pilc, A

    2005-05-01

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

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

    Science.gov (United States)

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

    2006-08-01

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

  15. [PECULIARITIES OF THE CEREBROVASCULAR EFFECTS OF GLUTAMIC ACID].

    Science.gov (United States)

    Gan'shina, T S; Kurza, E V; Kurdyumov, I N; Maslennikov, D V; Mirzoyan, R S

    2016-01-01

    Experiments on nonlinear rats subjected to global transient cerebral ischemia revealed the ability of glutamic acid to improve cerebral circulation. Consequently, the excitatory amino acid can produce adverse (neurotoxic) and positive (anti-ischemic) effects in cerebral ischemia. The cerebrovascular effect of glutamic acid in cerebral ischemia is attenuated on the background action of the MNDA receptor blocker MK-801 (0.5 mg/kg intravenously) and eliminated by bicuculline. When glutamic acid is combined with the non-competitive MNDA receptor antagonist MK-801, neither one nor another drug shows its vasodilator effect. The results are indicative of the interaction between excitatory and inhibitory systems on the level of cerebral vessels and once again confirm our previous conclusion about the decisive role of GABA(A) receptors in brain vessels in the implementation of anti-ischemic activity of endogenous compounds (melatonin) and well-known pharmacological substances (mexidol, afobazole), and new chemical compounds based on GABA-containing lipid derivatives.

  16. Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci

    Directory of Open Access Journals (Sweden)

    Guillermo Hugo Peralta

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

  17. 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.

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

    Science.gov (United States)

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

    2014-06-10

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

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

    Science.gov (United States)

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

    2014-01-01

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

  20. 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...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...

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

    Science.gov (United States)

    Niu, Panqing; Zhang, Zhenyu; Liu, Liming

    2014-08-01

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

  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. Altered vesicular glutamate transporter expression in human temporal lobe epilepsy with hippocampal sclerosis

    NARCIS (Netherlands)

    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

  5. 78 FR 74115 - Monosodium Glutamate From the People's Republic of China and the Republic of Indonesia...

    Science.gov (United States)

    2013-12-10

    ... International Trade Administration Monosodium Glutamate From the People's Republic of China and the Republic of... investigations of monosodium glutamate from Indonesia and the PRC.\\1\\ Currently, the preliminary determinations are due no later than December 27, 2013. \\1\\ See Monosodium Glutamate from the People's Republic of...

  6. 40 CFR 721.3820 - L-Glutamic acid, N-(1-oxododecyl)-, disodium salt.

    Science.gov (United States)

    2010-07-01

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

  7. 40 CFR 180.1187 - L-glutamic acid; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

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

  8. 40 CFR 721.3821 - L-Glutamic acid, N-(1-oxododecyl)-.

    Science.gov (United States)

    2010-07-01

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

  9. [The comparative investigation of antihypoxia activity of glutamic and N-acetylglutamic acids].

    Science.gov (United States)

    Makarova, L M; Pogorelyĭ, V E

    2013-01-01

    Comparative study of antihypoxic activity of glutamic and N-acetylglutamic acid in doses of 1, 10, 50 and 100 mg/kg was realized. It was experimentally ascertained that the most apparent antihypoxic action of study objects occurs in conditions of hypobaric hypoxia of acetylated derivative of glutamic acid considerably exceeds glutamic acid.

  10. Probing the cob(II)alamin Cond UctorHhypothesis with Glutamate ...

    African Journals Online (AJOL)

    The assembly of coenzyme B12 (adenosylcobalamin) with recombinant components GlmS and GlmE of glutamate mutase from Clostridium cochlearium reconstitutes an active holoenzyme that catalyses the reversible rearrangement between (S)-glutamate and (2S,3S)-3-methylaspartate. Glutamate mutase activity was also ...

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

    Science.gov (United States)

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

    2015-01-01

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

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

    African Journals Online (AJOL)

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

  13. The effect of monosodium glutamate (MSG) on blood glucose in ...

    African Journals Online (AJOL)

    This study investigates the effect of monosodium glutamate on fasting blood glucose. 18 adult rabbits (1.6 ± 0.20 Kg), procured from the animal house at the College of Medicine, Ambrose Alli University, Ekpoma, and transferred to the Physiology Laboratory of the same institution were used for this study. The animals were ...

  14. 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.

  15. Function and importance of glutamate for savory foods.

    Science.gov (United States)

    Loliger, J

    2000-04-01

    Flavoring systems are of vital importance in savory food manufacturing. Many industrially prepared foods are particularly attractive to potential consumers primarily because of their typical flavors. Therefore, it is no surprise that the food industry dealing with these product segments shows great interest in the use of food or food ingredients carrying the typical umami taste and flavor enhancement systems. Figures are provided showing the importance of glutamate in traditional cuisines and also in meals prepared by industrial manufacturing. It is also interesting to see how food intake patterns of glutamate differ from one cultural group to another. The ever-growing importance of balanced food formulations (carbohydrates, fats, proteins and minerals) brings special challenges to the use of different ingredients, requiring development of appropriate flavor delivery systems. Again flavor enhancement is of great importance. Questions about the addition of glutamate or the total glutamate content of foods are of little importance, from a scientific point of view. However, in a given legal framework, important business opportunities can be realized. One of the main concerns of manufacturers of savory food is how to provide the consumer with tasty foods while complying with increasingly severe local legal constraints concerning the use of many potent flavoring systems.

  16. 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…

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

    African Journals Online (AJOL)

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

  18. Metabotropic glutamate receptors in cultured cerebellar granule cells: developmental profile

    NARCIS (Netherlands)

    Aronica, E.; Condorelli, D. F.; Nicoletti, F.; Dell'Albani, P.; Amico, C.; Balázs, R.

    1993-01-01

    Excitatory amino acid (EAA)-induced polyphosphoinositide (PPI) hydrolysis was studied during the development in culture of cerebellar granule cells. The developmental pattern was similar using metabotropic glutamate (Glu) receptor (mGluR) agonists, including L-Glu, quisqualate, and

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

    African Journals Online (AJOL)

    dell

    with a peptide mimic that contains the same number of atoms between Co(III) and the adenosine base. Measurements of the kinetic constants of glutamate mutase with coenzyme B12 and 3',5'- dideoxyadenosylcobalamin suggested similar binding properties of the cofactors to the apo- enzyme. However, the catalytic ...

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

    African Journals Online (AJOL)

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

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

    African Journals Online (AJOL)

    Uche

    Annals of Medical and Health Sciences Research – January 2011 – Vol. 1 N0.1. >>>37<<<. Histological Studies of the Effects of Monosodium. Glutamate on the Ovaries of Adult Wistar Rats. Eweka AO* and Om'Iniabohs FAE*. * Department of Anatomy School of Basic Medical Sciences,. College of Medical Sciences ...

  2. Synthesis of Biobased Succinonitrile from Glutamic Acid and Glutamine

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2003-01-01

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  5. Continuous glutamate production using an immobilized whole-cell system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.S.; Ryu, D.D.Y.

    1982-10-01

    For the purpose of saving the energy and raw materials required in a glutamate fermentation, an immobilized whole-cell system was prepared and its performance in a continuous reactor system was evaluated. Corynebacterium glutamicum (a mutant strain of ATCC 13058) whole cell was immobilized in k-carrageenan matrix and the gel structure was strengthened by treatment with a hardening agent. The effective diffusivities of carrageenan gel for glucose and oxygen were formed to decrease significantly with an increase in carrageenan concentration, while the gel strength showed an increasing trend. Based on the physical and chemical properties of carrageenan gel, the immobilized method was improved and the operation of the continuous reactor system was partially optimized. In an air-stirred fermentor, the continuous production of glutamate was carried out. The effect of the dilution rate of glutamate production and operation stability was investigated. The performance of the continuous wbole-cell reactor system was evaluated by measuring glutamate productivity for a period of 30 days; it was found to be far superior to the performance of convention batch reactor systems using free cells.

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

    African Journals Online (AJOL)

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

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

    African Journals Online (AJOL)

    Uche

    One such food additive is. Monosodium Glutamate (MSG) and it is sold in most open market stalls and stores in Nigeria as. “Ajinomoto” marketed by West African Seasoning. Company Limited. Some pathological conditions like cancers result from the body‟s normal responses to abnormal environmental influences.

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

    DEFF Research Database (Denmark)

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

    1992-01-01

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

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

    Indian Academy of Sciences (India)

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

  10. 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

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

    Science.gov (United States)

    Rönnbäck, Lars; Hansson, Elisabeth

    2004-11-04

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

  12. Glutamate-mediated excitotoxicity in schizophrenia: a review.

    Science.gov (United States)

    Plitman, Eric; Nakajima, Shinichiro; de la Fuente-Sandoval, Camilo; Gerretsen, Philip; Chakravarty, M Mallar; Kobylianskii, Jane; Chung, Jun Ku; Caravaggio, Fernando; Iwata, Yusuke; Remington, Gary; Graff-Guerrero, Ariel

    2014-10-01

    Findings from neuroimaging studies in patients with schizophrenia suggest widespread structural changes although the mechanisms through which these changes occur are currently unknown. Glutamatergic activity appears to be increased in the early phases of schizophrenia and may contribute to these structural alterations through an excitotoxic effect. The primary aim of this review was to describe the possible role of glutamate-mediated excitotoxicity in explaining the presence of neuroanatomical changes within schizophrenia. A Medline(®) literature search was conducted, identifying English language studies on the topic of glutamate-mediated excitotoxicity in schizophrenia, using the terms "schizophreni" and "glutam" and (("MRS" or "MRI" or "magnetic resonance") or ("computed tomography" or "CT")). Studies concomitantly investigating glutamatergic activity and brain structure in patients with schizophrenia were included. Results are discussed in the context of findings from preclinical studies. Seven studies were identified that met the inclusion criteria. These studies provide inconclusive support for the role of glutamate-mediated excitotoxicity in the occurrence of structural changes within schizophrenia, with the caveat that there is a paucity of human studies investigating this topic. Preclinical data suggest that an excitotoxic effect may occur as a result of a paradoxical increase in glutamatergic activity following N-methyl-D-aspartate receptor hypofunction. Based on animal literature, glutamate-mediated excitotoxicity may account for certain structural changes present in schizophrenia, but additional human studies are required to substantiate these findings. Future studies should adopt a longitudinal design and employ magnetic resonance imaging techniques to investigate whether an association between glutamatergic activity and structural changes exists in patients with schizophrenia. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

  13. Prefrontal cortex glutamate correlates with mental perspective-taking.

    Directory of Open Access Journals (Sweden)

    Christiane Montag

    Full Text Available BACKGROUND: Dysfunctions in theory of mind and empathic abilities have been suggested as core symptoms in major psychiatric disorders including schizophrenia and autism. Since self monitoring, perspective taking and empathy have been linked to prefrontal (PFC and anterior cingulate cortex (ACC function, neurotransmitter variations in these areas may account for normal and pathological variations of these functions. Converging evidence indicates an essential role of glutamatergic neurotransmission in psychiatric diseases with pronounced deficits in empathy. However, the role of the glutamate system for different dimensions of empathy has not been investigated so far. METHODOLOGY/PRINCIPAL FINDINGS: Absolute concentrations of cerebral glutamate in the ACC, left dorsolateral PFC and left hippocampus were determined by 3-tesla proton magnetic resonance spectroscopy (1H-MRS in 17 healthy individuals. Three dimensions of empathy were estimated by a self-rating questionnaire, the Interpersonal Reactivity Index (IRI. Linear regression analysis showed that dorsolateral PFC glutamate concentration was predicted by IRI factor "perspective taking" (T = -2.710, p = 0.018; adjusted alpha-level of 0.017, Bonferroni but not by "empathic concern" or "personal distress". No significant relationship between IRI subscores and the glutamate levels in the ACC or left hippocampus was detected. CONCLUSIONS/SIGNIFICANCE: This is the first study to investigate the role of the glutamate system for dimensions of theory of mind and empathy. Results are in line with recent concepts that executive top-down control of behavior is mediated by prefrontal glutamatergic projections. This is a preliminary finding that needs a replication in an independent sample.

  14. 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

  15. Tobacco Isoenzyme 1 of NAD(H)-Dependent Glutamate Dehydrogenase Catabolizes Glutamate in Vivo[OA

    Science.gov (United States)

    Purnell, Matthew Peter; Botella, José Ramon

    2007-01-01

    Glutamate (Glu) dehydrogenase (GDH, EC 1.4.1.2–1.4.1.4) catalyzes in vitro the reversible amination of 2-oxoglutarate to Glu. The in vivo direction(s) of the GDH reaction in higher plants and hence the role(s) of this enzyme is unclear, a situation confounded by the existence of isoenzymes comprised totally of either GDH β- (isoenzyme 1) or α- (isoenzyme 7) subunits, as well as another five α-β isoenzyme permutations. To clarify the in vivo direction of the reaction catalyzed by GDH isoenzyme 1, [15N]Glu was supplied to roots of two independent transgenic tobacco (Nicotiana tabacum) lines with increased isoenzyme 1 levels (S4-H and S49-H). The [15N]ammonium (NH4+) accumulation rate in these lines was elevated approximately 65% compared with a null segregant control line, indicating that isoenzyme 1 catabolizes Glu in roots. Leaf glutamine synthetase (GS) was inhibited with a GS-specific herbicide to quantify any contribution by GDH toward photorespiratory NH4+ reassimilation. Transgenic line S49-H did not show enhanced resistance to the herbicide, indicating that the large pool of isoenzyme 1 in S49-H leaves was unable to compensate for GS and suggesting that isoenzyme 1 does not assimilate NH4+ in vivo. PMID:17114271

  16. 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.

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

    Science.gov (United States)

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

    2015-02-01

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

  18. Salidroside protects cortical neurons against glutamate-induced cytotoxicity by inhibiting autophagy.

    Science.gov (United States)

    Yin, Wei-Yong; Ye, Qiang; Huang, Huan-Jie; Xia, Nian-Ge; Chen, Yan-Yan; Zhang, Yi; Qu, Qiu-Min

    2016-08-01

    Recent evidence suggests that glutamate-induced cytotoxicity contributes to autophagic neuron death and is partially mediated by increased oxidative stress. Salidroside has been demonstrated to have neuroprotective effects in glutamate-induced neuronal damage. The precise mechanism of its regulatory role in neuronal autophagy is, however, poorly understood. This study aimed to probe the effects and mechanisms of salidroside in glutamate-induced autophagy activation in cultured rat cortical neurons. Cell viability assay, Western blotting, coimmunoprecipitation, and small interfering RNA were performed to analyze autophagy activities during glutamate-evoked oxidative injury. We found that salidroside protected neonatal neurons from glutamate-induced apoptotic cell death. Salidroside significantly attenuated the LC3-II/LC3-I ratio and expression of Beclin-1, but increased (SQSTM1)/p62 expression under glutamate exposure. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, decreased LC3-II/LC3-I ratio, attenuated glutamate-induced cell injury, and mimicked some of the protective effects of salidroside against glutamate-induced cell injury. Molecular analysis demonstrated that salidroside inhibited cortical neuron autophagy in response to glutamate exposure through p53 signaling by increasing the accumulation of cytoplasmic p53. Salidroside inhibited the glutamate-induced dissociation of the Bcl-2-Beclin-1 complex with minor affects on the PI3K/Akt/mTOR signaling pathways. These data demonstrate that the inhibition of autophagy could be responsible for the neuroprotective effects of salidroside on glutamate-induced neuronal injury.

  19. 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....

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

    Science.gov (United States)

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

    2013-05-01

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

  1. 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

  2. Glutamate Metabolism in Brain Structures in Experimental Hemorrhagic Shock

    Directory of Open Access Journals (Sweden)

    V. N. Jakovlev

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ajit G Thomas

    Full Text Available 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

  4. 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...... areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155...... between the anti-GLURP489-1271 and anti-(EENV)6 antibody responses. The data provide indirect evidence for a protective role of antibodies reacting with recombinant GLURP489-1271 as well as with the synthetic peptide (EENV)6 from the Pf155/RESA....

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

    Directory of Open Access Journals (Sweden)

    Wu Long-Jun

    2009-05-01

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

  6. 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....

  7. 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

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

    Science.gov (United States)

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

    2016-04-01

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

  9. Faster flux of neurotransmitter glutamate during seizure - Evidence from 13C-enrichment of extracellular glutamate in kainate rat model.

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    Keiko Kanamori

    Full Text Available The objective is to examine how the flux of neurotransmitter glutamate from neurons to the extracellular fluid, as measured by the rate of 13C enrichment of extracellular glutamate (GLUECF, changes in response to seizures in the kainate-induced rat model of temporal-lobe epilepsy. Following unilateral intrahippocampal injection of kainate, GLUECF was collected by microdialysis from the CA1/CA3 region of awake rats, in combination with EEG recording of chronic-phase recurrent seizures and intravenous infusion of [2,5-13C]glucose. The 13C enrichment of GLUECF C5 at ~ 10 picomol level was measured by gas-chromatography mass-spectrometry. The rate of 13C enrichment, expressed as the increase of the fractional enrichment/min, was 0.0029 ± 0.0001/min in frequently seizing rats (n = 4; this was significantly higher (p < 0.01 than in the control (0.00167 ± 0.0001/min; n = 6 or in rats with infrequent seizures (0.00172 ± 0.0001/min; n = 6. This result strongly suggests that the flux of the excitatory neurotransmitter from neurons to the extracellular fluid is significantly increased by frequent seizures. The extracellular [12C + 13C]glutamate concentration increased progressively in frequently seizing rats. Taken together, these results strongly suggest that the observed seizure-induced high flux of glutamate overstimulated glutamate receptors, which triggered a chain reaction of excitation in the CA3 recurrent glutamatergic networks. The rate of 13C enrichment of extracellular glutamine (GLNECF at C5 was 0.00299 ± 0.00027/min in frequently seizing rats, which was higher (p < 0.05 than in controls (0.00227 ± 0.00008/min. For the first time in vivo, this study examined the effects of epileptic seizures on fluxes of the neurotransmitter glutamate and its precursor glutamine in the extracellular fluid of the hippocampus. The advantages, limitations and the potential for improvement of this approach for pre-clinical and clinical studies of temporal

  10. LONG-TERM HOMEOSTASIS OF EXTRACELLULAR GLUTAMATE IN THE RAT CEREBRAL CORTEX ACROSS SLEEP AND WAKING STATES

    OpenAIRE

    Dash, Michael B; Douglas, Christopher L.; Vyazovskiy, Vladyslav V.; Cirelli, Chiara; Tononi, Giulio

    2009-01-01

    Neuronal firing patterns, neuromodulators, and cerebral metabolism change across sleep waking states, and the synaptic release of glutamate is critically involved in these processes. Extrasynaptic glutamate can also affect neural function and may be neurotoxic, but whether and how extracellular glutamate is regulated across sleep-waking states is unclear. To assess the effect of behavioral state on extracellular glutamate at high temporal resolution, we recorded glutamate concentration in pre...

  11. Ginsenoside Rd promotes glutamate clearance by up-regulating glial glutamate transporter GLT-1 via PI3K/AKT and ERK1/2 pathways.

    Science.gov (United States)

    Zhang, Xiao; Shi, Ming; Bjørås, Magnar; Wang, Wei; Zhang, Guangyun; Han, Junliang; Liu, Zhirong; Zhang, Yunxia; Wang, Bing; Chen, Jing; Zhu, Yi; Xiong, Lize; Zhao, Gang

    2013-01-01

    Ginsenoside Rd (Rd), one of the main active ingredients in Panax ginseng, has been showed to protect against ischemic cerebral damage both in vitro and in vivo. However, the underlying mechanism of Rd is largely unknown. Excessive extracellular glutamate causes excitatory toxicity, leading to cell death, and neurodegenerative processes after brain ischemia. The clearance of extracellular glutamate by astrocytic glutamate transporter GLT-1 is essential for neuronal survival after stroke. Here we investigated the effects of Rd on the levels of extracellular glutamate and the expression of GLT-1 in vivo and in vitro. After rat middle cerebral artery occlusion, Rd significantly increased the mRNA and protein expression levels of GLT-1, and reduced the burst of glutamate as revealed by microdialysis. Consistently, specific glutamate uptake by cultured astrocytes was elevated after Rd exposure. Furthermore, we showed that Rd increased the levels of phosphorylated protein kinase B (PKB/Akt) and phospho-ERK1/2 (p-ERK1/2) in astrocyte culture after oxygen-glucose deprivation. Moreover, the effect of Rd on GLT-1 expression and glutamate uptake can be abolished by PI3K/AKT agonist LY294002 or ERK1/2 inhibitor PD98059. Taken together, our findings provide the first evidence that Rd can promote glutamate clearance by up-regulating GLT-1 expression through PI3K/AKT and ERK1/2 pathways.

  12. Complete genome sequence of Bacillus amyloliquefaciens LL3, which exhibits glutamic acid-independent production of poly-γ-glutamic acid.

    Science.gov (United States)

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

    2011-07-01

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

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

    OpenAIRE

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

    2011-01-01

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

  14. 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.

  15. 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.

  16. Targeting glutamate uptake to treat alcohol use disorders

    Directory of Open Access Journals (Sweden)

    P.S.S. eRao

    2015-04-01

    Full Text Available Alcoholism is a serious public health concern that is characterized by the development of tolerance to alcohol’s effects, increased consumption, loss of control over drinking and the development of physical dependence. This cycle is often times punctuated by periods of abstinence, craving and relapse. The development of tolerance and the expression of withdrawal effects, which manifest as dependence, have been to a great extent attributed to neuroadaptations within the mesocorticolimbic and extended amygdala systems. Alcohol affects various neurotransmitter systems in the brain including the adrenergic, cholinergic, dopaminergic, GABAergic, glutamatergic, peptidergic and serotonergic systems. Due to the myriad of neurotransmitter and neuromodulator systems affected by alcohol, the efficacies of current pharmacotherapies targeting alcohol dependence are limited. Importantly, research findings of changes in glutamatergic neurotransmission induced by alcohol self- or experimenter-administration have resulted in a focus on therapies targeting glutamatergic receptors and normalization of glutamatergic neurotransmission. Glutamatergic receptors implicated in the effects of ethanol include the ionotropic glutamate receptors (AMPA, Kainate, and NMDA and some metabotropic glutamate receptors. Regarding glutamatergic homeostasis, ceftriaxone, MS-153 and GPI-1046, which upregulate glutamate transporter 1 (GLT1 expression in mesocorticolimbic brain regions, reduce alcohol intake in genetic animal models of alcoholism. Given the hyperglutamatergic/hyperexcitable state of the central nervous system induced by chronic alcohol abuse and withdrawal, the evidence thus far indicates that a restoration of glutamatergic concentrations and activity within the mesocorticolimbic system and extended amygdala as well as multiple memory systems holds great promise for the treatment of alcohol dependence.

  17. 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.

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

    Science.gov (United States)

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

    2017-06-01

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

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2016-10-01

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

  1. A glutamic acid-producing lactic acid bacteria isolated from Malaysian fermented foods.

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  3. 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

    2007-01-05

    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.

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

    Science.gov (United States)

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

    2011-03-01

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

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

    Science.gov (United States)

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

    2014-10-01

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6–8). In this article, we present a L-...... a selective agonist activity profile at mGlu2 (EC50 in the micromolar range), whereas 2c/2d were both selective agonists at group III, subtypes mGlu4,6,8. In general, 2d was 20-fold more potent than 2c and potently activated mGlu4,6,8 in the low–mid nanomolar range.......The metabotropic glutamate (Glu) receptors (mGluRs) play key roles in modulating excitatory neurotransmission in the brain. In all, eight subtypes have been identified and divided into three groups, group I (mGlu1,5), group II (mGlu2,3), and group III (mGlu4,6–8). In this article, we present a L-2......,4-syn-substituted Glu analogue, 1d, which displays selective agonist activity at mGlu2 over the remaining mGluR subtypes. A modeling study and redesign of the core scaffold led to the stereoselective synthesis of four new conformationally restricted Glu analogues, 2a–d. Most interestingly, 2a retained...

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

    DEFF Research Database (Denmark)

    Vetterli, Laurène; Carobbio, Stefania; Pournourmohammadi, Shirin

    2012-01-01

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

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

    DEFF Research Database (Denmark)

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

    2003-01-01

    2-Amino-3-[3-hydroxy-5-(2-thiazolyl)-4-isoxazolyl]propionic acid (1) is a potent AMPA receptor agonist with moderate affinity for native kainic acid (KA) receptors, whereas (S)-E-4-(2,2-dimethylpropylidene)glutamic acid (3) show high affinity for the GluR5 subtype of KA receptors and much lower...... affinity for the GluR2 subtype of AMPA receptors. As an attempt to develop new pharmacological tools for studies of GluR5 receptors, (S)-E-4-(2-thiazolylmethylene)glutamic acid (4a) was designed as a structural hybrid between 1 and 3. 4a was shown to be a potent GluR5 agonist and a high affinity ligand...

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

    Science.gov (United States)

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

    2003-07-20

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

  11. Exogenous glutamate induces short and long-term potentiation in the rat medial vestibular nuclei.

    Science.gov (United States)

    Grassi, S; Frondaroli, A; Pessia, M; Pettorossi, V E

    2001-08-08

    In rat brain stem slices, high concentrations of exogenous glutamate induce long-term potentiation (LTP) of the field potentials evoked in the medial vestibular nuclei (MVN) by vestibular afferent stimulation. At low concentrations, glutamate can also induce short-term potentiation (STP), indicating that LTP and STP are separate events depending on the level of glutamatergic synapse activation. LTP and STP are prevented by blocking NMDA receptors and nitric oxide (NO) synthesis. Conversely, blocking platelet-activating factor (PAF) and group I metabotropic glutamate receptors only prevents the full development of LTP. Moreover, in the presence of blocking agents, glutamate causes transient inhibition, suggesting that when potentiation is impeded, exogenous glutamate can activate presynaptic mechanisms that reduce glutamate release.

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

    Directory of Open Access Journals (Sweden)

    Ian D. Coombs

    2017-08-01

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

  13. Effect of diphenylthiocarbazone (dithizone) on glutamate level in hippocampus preparation in vitro and in vivo.

    Science.gov (United States)

    Kihara, T; Ishihara, T; Baba, A; Iwata, H

    1990-04-01

    To assess the functional interaction between Zn2+ and glutamate in hippocampus, diphenylthiocarbazone (dithizone), a Zn2+ chelator, was used to alter the glutamate level in hippocampus in vitro and in vivo. Dithizone at the concentration of 1 microM stimulated high K(+)- and veratrine-induced release of [3H]glutamate both in the presence and absence of Ca2+ from rat hippocampal slices preloaded with [3H]glutamate without affecting the release of [3H]gamma-aminobutyric acid and [3H]acetylcholine. Metal chelators other than dithizone did not evoke the [3H]glutamate release at the concentration of 10 microM. Two weeks after the intrahippocampal injection of 20 micrograms of dithizone, both Zn2+ and glutamate levels of the hippocampus significantly decreased with no change in the levels of other metals, amino acids, monoamines and acetylcholine.

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

    Science.gov (United States)

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

    2016-07-01

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

  15. Limited energy supply in Müller cells alters glutamate uptake

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  16. A role for glutamate transporters in the regulation of insulin secretion.

    Directory of Open Access Journals (Sweden)

    Runhild Gammelsaeter

    Full Text Available In the brain, glutamate is an extracellular transmitter that mediates cell-to-cell communication. Prior to synaptic release it is pumped into vesicles by vesicular glutamate transporters (VGLUTs. To inactivate glutamate receptor responses after release, glutamate is taken up into glial cells or neurons by excitatory amino acid transporters (EAATs. In the pancreatic islets of Langerhans, glutamate is proposed to act as an intracellular messenger, regulating insulin secretion from β-cells, but the mechanisms involved are unknown. By immunogold cytochemistry we show that insulin containing secretory granules express VGLUT3. Despite the fact that they have a VGLUT, the levels of glutamate in these granules are low, indicating the presence of a protein that can transport glutamate out of the granules. Surprisingly, in β-cells the glutamate transporter EAAT2 is located, not in the plasma membrane as it is in brain cells, but exclusively in insulin-containing secretory granules, together with VGLUT3. In EAAT2 knock out mice, the content of glutamate in secretory granules is higher than in wild type mice. These data imply a glutamate cycle in which glutamate is carried into the granules by VGLUT3 and carried out by EAAT2. Perturbing this cycle by knocking down EAAT2 expression with a small interfering RNA, or by over-expressing EAAT2 or a VGLUT in insulin granules, significantly reduced the rate of granule exocytosis. Simulations of granule energetics suggest that VGLUT3 and EAAT2 may regulate the pH and membrane potential of the granules and thereby regulate insulin secretion. These data suggest that insulin secretion from β-cells is modulated by the flux of glutamate through the secretory granules.

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

    OpenAIRE

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

    2012-01-01

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

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

    Science.gov (United States)

    Sharma, Amod

    2015-10-22

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

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

    OpenAIRE

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

    2011-01-01

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

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

    OpenAIRE

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

    2012-01-01

    L-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rR...

  1. Mutations of the Corynebacterium glutamicum NCgl1221 gene, encoding a mechanosensitive channel homolog, induce L-glutamic acid production.

    Science.gov (United States)

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

    2007-07-01

    Corynebacterium glutamicum is a biotin auxotroph that secretes L-glutamic acid in response to biotin limitation; this process is employed in industrial L-glutamic acid production. Fatty acid ester surfactants and penicillin also induce L-glutamic acid secretion, even in the presence of biotin. However, the mechanism of L-glutamic acid secretion remains unclear. It was recently reported that disruption of odhA, encoding a subunit of the 2-oxoglutarate dehydrogenase complex, resulted in L-glutamic acid secretion without induction. In this study, we analyzed odhA disruptants and found that those which exhibited constitutive L-glutamic acid secretion carried additional mutations in the NCgl1221 gene, which encodes a mechanosensitive channel homolog. These NCgl1221 gene mutations lead to constitutive L-glutamic acid secretion even in the absence of odhA disruption and also render cells resistant to an L-glutamic acid analog, 4-fluoroglutamic acid. Disruption of the NCgl1221 gene essentially abolishes L-glutamic acid secretion, causing an increase in the intracellular L-glutamic acid pool under biotin-limiting conditions, while amplification of the wild-type NCgl1221 gene increased L-glutamate secretion, although only in response to induction. These results suggest that the NCgl1221 gene encodes an L-glutamic acid exporter. We propose that treatments that induce L-glutamic acid secretion alter membrane tension and trigger a structural transformation of the NCgl1221 protein, enabling it to export L-glutamic acid.

  2. ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jorgensen, N R; Geist, S T; Civitelli, R

    1997-01-01

    stores. In one model, IP3 traverses gap junctions and initiates the release of intracellular calcium stores in neighboring cells. Alternatively, calcium waves may be mediated not by gap junctional communication, but rather by autocrine activity of secreted ATP on P2 purinergic receptors. We studied...... mechanically induced calcium waves in two rat osteosarcoma cell lines that differ in the gap junction proteins they express, in their ability to pass microinjected dye from cell to cell, and in their expression of P2Y2 (P2U) purinergic receptors. ROS 17/2.8 cells, which express the gap junction protein...... connexin43 (Cx43), are well dye coupled, and lack P2U receptors, transmitted slow gap junction-dependent calcium waves that did not require release of intracellular calcium stores. UMR 106-01 cells predominantly express the gap junction protein connexin 45 (Cx45), are poorly dye coupled, and express P2U...

  3. 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.

  4. 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.

  5. Positive correlation between rat brain glutamate concentrations and mitochondrial 2-oxoglutarate dehydrogenase activity.

    Science.gov (United States)

    Mkrtchyan, Garik V; Graf, Anastasia; Trofimova, Lidia; Ksenofontov, Alexander; Baratova, Ludmila; Bunik, Victoria

    2018-01-08

    Glutamate is a key metabolite and major excitatory neurotransmitter, degraded through transformation to 2-oxoglutarate which is further catabolized by 2-oxoglutarate dehydrogenase complex (OGDHC). Both the glutamate excitotoxicity and impaired OGDHC activity are hallmarks of neurodegeneration. This work quantifies a relationship between the brain OGDHC activity and glutamate levels, assessing its diagnostic value to characterize (patho)physiology. A moderate to strong positive correlation of the two parameters determined under varied physiological settings (brain regions, seasons, gender, pregnancy, rat line), is revealed. Mitochondrial impairment (OGDHC inhibition or acute hypobaric hypoxia) decreases the interdependence, even when the parameter means do not change significantly. Compared to the cortex, the cerebellum exhibits a lower inter-individual glutamate variation and a weaker glutamate-OGDHC interdependence. Specific metabolism of the brain regions is also characterized by a positive correlation between glutamate and γ-aminobutyric acid (GABA) concentrations in the cortex but not in the cerebellum. In contrast, a strong positive correlation between glutamate and glutamine is present in both the cortex and cerebellum. The differences in metabolic correlations are in line with transcriptomics data which suggest that glutamate distribution between competitive pathways contributes to the brain-region-specific features of the interdependences of glutamate and OGDHC or GABA. Copyright © 2018. Published by Elsevier Inc.

  6. The role of malate in the synthesis of glutamate in Pisum arvense roots

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    Genowefa Kubik-Dorosz

    2014-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

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

    Science.gov (United States)

    Nissen, Jakob D; Lykke, Kasper; Bryk, Jaroslaw; Stridh, Malin H; Zaganas, Ioannis; Skytt, Dorte M; Schousboe, Arne; Bak, Lasse K; Enard, Wolfgang; Pääbo, Svante; Waagepetersen, Helle S

    2017-03-01

    A key enzyme in brain glutamate homeostasis is glutamate dehydrogenase (GDH) which links carbohydrate and amino acid metabolism mediating glutamate degradation to CO2 and expanding tricarboxylic acid (TCA) cycle capacity with intermediates, i.e. anaplerosis. Humans express two GDH isoforms, GDH1 and 2, whereas most other mammals express only GDH1. hGDH1 is widely expressed in human brain while hGDH2 is confined to astrocytes. The two isoforms display different enzymatic properties and the nature of these supports that hGDH2 expression in astrocytes potentially increases glutamate oxidation and supports the TCA cycle during energy-demanding processes such as high intensity glutamatergic signaling. However, little is known about how expression of hGDH2 affects the handling of glutamate and TCA cycle metabolism in astrocytes. Therefore, we cultured astrocytes from cerebral cortical tissue of hGDH2-expressing transgenic mice. We measured glutamate uptake and metabolism using [3 H]glutamate, while the effect on metabolic pathways of glutamate and glucose was evaluated by use of 13 C and 14 C substrates and analysis by mass spectrometry and determination of radioactively labeled metabolites including CO2 , respectively. We conclude that hGDH2 expression increases capacity for uptake and oxidative metabolism of glutamate, particularly during increased workload and aglycemia. Additionally, hGDH2 expression increased utilization of branched-chain amino acids (BCAA) during aglycemia and caused a general decrease in oxidative glucose metabolism. We speculate, that expression of hGDH2 allows astrocytes to spare glucose and utilize BCAAs during substrate shortages. These findings support the proposed role of hGDH2 in astrocytes as an important fail-safe during situations of intense glutamatergic activity. GLIA 2017;65:474-488. © 2016 Wiley Periodicals, Inc.

  9. Rapid glutamate receptor 2 trafficking during retinal degeneration

    Directory of Open Access Journals (Sweden)

    Lin Yanhua

    2012-02-01

    Full Text Available Abstract Background Retinal degenerations, such as age-related macular degeneration (AMD and retinitis pigmentosa (RP, are characterized by photoreceptor loss and anomalous remodeling of the surviving retina that corrupts visual processing and poses a barrier to late-stage therapeutic interventions in particular. However, the molecular events associated with retinal remodeling remain largely unknown. Given our prior evidence of ionotropic glutamate receptor (iGluR reprogramming in retinal degenerations, we hypothesized that the edited glutamate receptor 2 (GluR2 subunit and its trafficking may be modulated in retinal degenerations. Results Adult albino Balb/C mice were exposed to intense light for 24 h to induce light-induced retinal degeneration (LIRD. We found that prior to the onset of photoreceptor loss, protein levels of GluR2 and related trafficking proteins, including glutamate receptor-interacting protein 1 (GRIP1 and postsynaptic density protein 95 (PSD-95, were rapidly increased. LIRD triggered neuritogenesis in photoreceptor survival regions, where GluR2 and its trafficking proteins were expressed in the anomalous dendrites. Immunoprecipitation analysis showed interaction between KIF3A and GRIP1 as well as PSD-95, suggesting that KIF3A may mediate transport of GluR2 and its trafficking proteins to the novel dendrites. However, in areas of photoreceptor loss, GluR2 along with its trafficking proteins nearly vanished in retracted retinal neurites. Conclusions All together, LIRD rapidly triggers GluR2 plasticity, which is a potential mechanism behind functionally phenotypic revisions of retinal neurons and neuritogenesis during retinal degenerations.

  10. Poly-γ-glutamic acid: production, properties and applications.

    Science.gov (United States)

    Ogunleye, Adetoro; Bhat, Aditya; Irorere, Victor U; Hill, David; Williams, Craig; Radecka, Iza

    2015-01-01

    Poly-γ-glutamic acid (γ-PGA) is a naturally occurring biopolymer made up of repeating units of l-glutamic acid, d-glutamic acid or both. γ-PGA can exhibit different properties (conformational states, enantiomeric properties and molecular mass). Owing to its biodegradable, non-toxic and non-immunogenic properties, it has been used successfully in the food, medical and wastewater industries. Amongst other novel applications, it has the potential to be used for protein crystallization, as a soft tissue adhesive and a non-viral vector for safe gene delivery. This review focuses on the production, properties and applications of γ-PGA. Each application of γ-PGA utilizes specific properties attributed to various forms of γ-PGA. As a result of its growing applications, more strains of bacteria need to be investigated for γ-PGA production to obtain high yields of γ-PGA with different properties. Many medical applications (especially drug delivery) have exploited α-PGA. As γ-PGA is essentially different from α-PGA (i.e. it does not involve a chemical modification step and is not susceptible to proteases), it could be better utilized for such medical applications. Optimization of γ-PGA with respect to cost of production, molecular mass and conformational/enantiomeric properties is a major step in making its application practical. Analyses of γ-PGA production and knowledge of the enzymes and genes involved in γ-PGA production will not only help increase productivity whilst reducing the cost of production, but also help to understand the mechanism by which γ-PGA is effective in numerous applications. © 2015 The Authors.

  11. The dissolution of natural and artificial dusts in glutamic acid

    Science.gov (United States)

    Ling, Zhang; Faqin, Dong; Xiaochun, He

    2015-06-01

    This article describes the characteristics of natural dusts, industrial dusts, and artificial dusts, such as mineral phases, chemical components, morphological observation and size. Quartz and calcite are the main phases of natural dusts and industrial dusts with high SiO2 and CaO and low K2O and Na2O in the chemical composition. The dissolution and electrochemical action of dusts in glutamic acid liquor at the simulated human body temperature (37 °C) in 32 h was investigated. The potential harm that the dust could lead to in body glutamic acid acidic environment, namely biological activity, is of great importance for revealing the human toxicological mechanism. The changes of pH values and electric conductivity of suspension of those dusts were similar, increased slowly in the first 8 h, and then the pH values increased rapidly. The total amount of dissolved ions of K, Ca, Na, and Mg was 35.4 to 429 mg/kg, particularly Ca was maximal of 20 to 334 mg/kg. The total amount of dissolved ions of Fe, Zn, Mn, Pb, and Ba was 0.18 to 5.59 mg/kg and in Al and Si was 3.0 to 21.7 mg/kg. The relative solubility order of dusts in glutamic acid is wollastonite > serpentine > sepiolite, the cement plant industrial dusts > natural dusts > power plant industrial dusts. The wollastonite and cement plant industrial dusts have the highest solubility, which also have high content of CaO; this shows that there are a poorer corrosion-resisting ability and lower bio-resistibility. Sepiolite and power plant industrial dusts have lowest solubility, which also have high content of SiO2; this shows that there are a higher corrosion-resisting ability and stronger bio-resistibility.

  12. Clofibrate inhibits the umami-savory taste of glutamate

    OpenAIRE

    Kochem, Matthew; Breslin, Paul A. S.

    2017-01-01

    In humans, umami taste can increase the palatability of foods rich in the amino acids glutamate and aspartate and the 5'-ribonucleotides IMP and GMP. Umami taste is transduced, in part, by T1R1-T1R3, a heteromeric G-protein coupled receptor. Umami perception is inhibited by sodium lactisole, which binds to the T1R3 subunit in vitro. Lactisole is structurally similar to the fibrate drugs. Clofibric acid, a lipid lowering drug, also binds the T1R3 subunit in vitro. The purpose of this study was...

  13. Clofibrate inhibits the umami-savory taste of glutamate.

    Science.gov (United States)

    Kochem, Matthew; Breslin, Paul A S

    2017-01-01

    In humans, umami taste can increase the palatability of foods rich in the amino acids glutamate and aspartate and the 5'-ribonucleotides IMP and GMP. Umami taste is transduced, in part, by T1R1-T1R3, a heteromeric G-protein coupled receptor. Umami perception is inhibited by sodium lactisole, which binds to the T1R3 subunit in vitro. Lactisole is structurally similar to the fibrate drugs. Clofibric acid, a lipid lowering drug, also binds the T1R3 subunit in vitro. The purpose of this study was to determine whether clofibric acid inhibits the umami taste of glutamate in human subjects. Ten participants rated the umami taste intensity elicited by 20 mM monosodium glutamate (MSG) mixed with varying concentrations of clofibric acid (0 to 16 mM). In addition, fourteen participants rated the effect of 1.4 mM clofibric acid on umami enhancement by 5' ribonucleotides. Participants were instructed to rate perceived intensity using a general Labeled Magnitude Scale (gLMS). Each participant was tested in triplicate. Clofibric acid inhibited umami taste intensity from 20 mM MSG in a dose dependent manner. Whereas MSG neat elicited "moderate" umami taste intensity, the addition of 16 mM clofibric acid elicited only "weak" umami intensity on average, and in some subjects no umami taste was elicited. We further show that 1.4 mM clofibric acid suppressed umami enhancement from GMP, but not from IMP. This study provides in vivo evidence that clofibric acid inhibits glutamate taste perception, presumably via T1R1-T1R3 inhibition, and lends further evidence that the T1R1-T1R3 receptor is the principal umami receptor in humans. T1R receptors are expressed extra-orally throughout the alimentary tract and in regulatory organs and are known to influence glucose and lipid metabolism. Whether clofibric acid as a lipid-lowering drug affects human metabolism, in part, through T1R inhibition warrants further examination.

  14. Glutamate-pyruvate transaminase subtypes in Singapore ethnic groups.

    Science.gov (United States)

    Saha, N; Bhattacharyya, S P

    1989-01-01

    Autopsy liver samples from 244 Chinese, 119 Malays and 136 Indians were screened for glutamate-pyruvate transaminase (GPT) subtypes by starch-gel electrophoresis and isoelectric focusing at pH 5-7. Altogether, ten phenotypes controlled by four alleles (GPT1, GPT2A, GPT2B and GPT3) were identified. There was no significant difference in the frequency of GPT alleles between the ethnic groups. The distribution of GPT types was in agreement with the Hardy-Weinberg equilibrium in all the ethnic groups.

  15. Clofibrate inhibits the umami-savory taste of glutamate.

    Directory of Open Access Journals (Sweden)

    Matthew Kochem

    Full Text Available In humans, umami taste can increase the palatability of foods rich in the amino acids glutamate and aspartate and the 5'-ribonucleotides IMP and GMP. Umami taste is transduced, in part, by T1R1-T1R3, a heteromeric G-protein coupled receptor. Umami perception is inhibited by sodium lactisole, which binds to the T1R3 subunit in vitro. Lactisole is structurally similar to the fibrate drugs. Clofibric acid, a lipid lowering drug, also binds the T1R3 subunit in vitro. The purpose of this study was to determine whether clofibric acid inhibits the umami taste of glutamate in human subjects. Ten participants rated the umami taste intensity elicited by 20 mM monosodium glutamate (MSG mixed with varying concentrations of clofibric acid (0 to 16 mM. In addition, fourteen participants rated the effect of 1.4 mM clofibric acid on umami enhancement by 5' ribonucleotides. Participants were instructed to rate perceived intensity using a general Labeled Magnitude Scale (gLMS. Each participant was tested in triplicate. Clofibric acid inhibited umami taste intensity from 20 mM MSG in a dose dependent manner. Whereas MSG neat elicited "moderate" umami taste intensity, the addition of 16 mM clofibric acid elicited only "weak" umami intensity on average, and in some subjects no umami taste was elicited. We further show that 1.4 mM clofibric acid suppressed umami enhancement from GMP, but not from IMP. This study provides in vivo evidence that clofibric acid inhibits glutamate taste perception, presumably via T1R1-T1R3 inhibition, and lends further evidence that the T1R1-T1R3 receptor is the principal umami receptor in humans. T1R receptors are expressed extra-orally throughout the alimentary tract and in regulatory organs and are known to influence glucose and lipid metabolism. Whether clofibric acid as a lipid-lowering drug affects human metabolism, in part, through T1R inhibition warrants further examination.

  16. Modulation of Asymmetric Flux in Heterotypic Gap Junctions by Pore Shape, Particle Size and Charge.

    Science.gov (United States)

    Mondal, Abhijit; Sachse, Frank B; Moreno, Alonso P

    2017-01-01

    Gap junction channels play a vital role in intercellular communication by connecting cytoplasm of adjoined cells through arrays of channel-pores formed at the common membrane junction. Their structure and properties vary depending on the connexin isoform(s) involved in forming the full gap junction channel. Lack of information on the molecular structure of gap junction channels has limited the development of computational tools for single channel studies. Currently, we rely on cumbersome experimental techniques that have limited capabilities. We have earlier reported a simplified Brownian dynamics gap junction pore model and demonstrated that variations in pore shape at the single channel level can explain some of the differences in permeability of heterotypic channels observed in in vitro experiments. Based on this computational model, we designed simulations to study the influence of pore shape, particle size and charge in homotypic and heterotypic pores. We simulated dye diffusion under whole cell voltage clamping. Our simulation studies with pore shape variations revealed a pore shape with maximal flux asymmetry in a heterotypic pore. We identified pore shape profiles that match the in silico flux asymmetry results to the in vitro results of homotypic and heterotypic gap junction formed out of Cx43 and Cx45. Our simulation results indicate that the channel's pore-shape established flux asymmetry and that flux asymmetry is primarily regulated by the sizes of the conical and/or cylindrical mouths at each end of the pore. Within the set range of particle size and charge, flux asymmetry was found to be independent of particle size and directly proportional to charge magnitude. While particle charge was vital to creating flux asymmetry, charge magnitude only scaled the observed flux asymmetry. Our studies identified the key factors that help predict asymmetry. Finally, we suggest the role of such flux asymmetry in creating concentration imbalances of messenger

  17. Motor axon synapses on renshaw cells contain higher levels of aspartate than glutamate.

    Directory of Open Access Journals (Sweden)

    Dannette S Richards

    Full Text Available Motoneuron synapses on spinal cord interneurons known as Renshaw cells activate nicotinic, AMPA and NMDA receptors consistent with co-release of acetylcholine and excitatory amino acids (EAA. However, whether these synapses express vesicular glutamate transporters (VGLUTs capable of accumulating glutamate into synaptic vesicles is controversial. An alternative possibility is that these synapses release other EAAs, like aspartate, not dependent on VGLUTs. To clarify the exact EAA concentrated at motor axon synapses we performed a quantitative postembedding colloidal gold immunoelectron analysis for aspartate and glutamate on motor axon synapses (identified by immunoreactivity to the vesicular acetylcholine transporter; VAChT contacting calbindin-immunoreactive (-IR Renshaw cell dendrites. The results show that 71% to 80% of motor axon synaptic boutons on Renshaw cells contained aspartate immunolabeling two standard deviations above average neuropil labeling. Moreover, VAChT-IR synapses on Renshaw cells contained, on average, aspartate immunolabeling at 2.5 to 2.8 times above the average neuropil level. In contrast, glutamate enrichment was lower; 21% to 44% of VAChT-IR synapses showed glutamate-IR two standard deviations above average neuropil labeling and average glutamate immunogold density was 1.7 to 2.0 times the neuropil level. The results were not influenced by antibody affinities because glutamate antibodies detected glutamate-enriched brain homogenates more efficiently than aspartate antibodies detecting aspartate-enriched brain homogenates. Furthermore, synaptic boutons with ultrastructural features of Type I excitatory synapses were always labeled by glutamate antibodies at higher density than motor axon synapses. We conclude that motor axon synapses co-express aspartate and glutamate, but aspartate is concentrated at higher levels than glutamate.

  18. Chronic Monosodium Glutamate Administration Induced Hyperalgesia in Mice

    Directory of Open Access Journals (Sweden)

    Anca Zanfirescu

    2017-12-01

    Full Text Available Monosodium glutamate (MSG is a widely used food additive. Although it is generally considered safe, some questions regarding the impact of its use on general health have arisen. Several reports correlate MSG consumption with a series of unwanted reactions, including headaches and mechanical sensitivity in pericranial muscles. Endogenous glutamate plays a significant role in nociceptive processing, this neurotransmitter being associated with hyperalgesia and central sensitization. One of the mechanisms underlying these phenomena is the stimulation of Ca2+/calmodulin sensitive nitric oxide synthase, and a subsequent increase in nitric oxide production. This molecule is a key player in nociceptive processing, with implications in acute and chronic pain states. Our purpose was to investigate the effect of this food additive on the nociceptive threshold when given orally to mice. Hot-plate and formalin tests were used to assess nociceptive behaviour. We also tried to determine if a correlation between chronic administration of MSG and variations in central nitric oxide (NO concentration could be established. We found that a dose of 300 mg/kg MSG given for 21 days reduces the pain threshold and is associated with a significant increase in brain NO level. The implications of these findings on food additive-drug interaction, and on pain perception in healthy humans, as well as in those suffering from affections involving chronic pain, are still to be investigated.

  19. Abnormal glutamate release in aged BTBR mouse model of autism.

    Science.gov (United States)

    Wei, Hongen; Ding, Caiyun; Jin, Guorong; Yin, Haizhen; Liu, Jianrong; Hu, Fengyun

    2015-01-01

    Autism is a neurodevelopmental disorder characterized by abnormal reciprocal social interactions, communication deficits, and repetitive behaviors with restricted interests. Most of the available research on autism is focused on children and young adults and little is known about the pathological alternation of autism in older adults. In order to investigate the neurobiological alternation of autism in old age stage, we compared the morphology and synaptic function of excitatory synapses between the BTBR mice with low level sociability and B6 mice with high level sociability. The results revealed that the number of excitatory synapse colocalized with pre- and post-synaptic marker was not different between aged BTBR and B6 mice. The aged BTBR mice had a normal structure of dendritic spine and the expression of Shank3 protein in the brain as well as that in B6 mice. The baseline and KCl-evoked glutamate release from the cortical synaptoneurosome in aged BTBR mice was lower than that in aged B6 mice. Overall, the data indicate that there is a link between disturbances of the glutamate transmission and autism. These findings provide new evidences for the hypothesis of excitation/inhibition imbalance in autism. Further work is required to determine the cause of this putative abnormality.

  20. Mitochondrial dysfunction associated with nitric oxide pathways in glutamate neurotoxicity.

    Science.gov (United States)

    Manucha, Walter

    Multiple mechanisms underlying glutamate-induced neurotoxicity have recently been discussed. Likewise, a clear deregulation of the mitochondrial respiratory mechanism has been described in patients with neurodegeneration, oxidative stress, and inflammation. This article highlights nitric oxide, an atypical neurotransmitter synthesized and released on demand by the post-synaptic neurons, and has many important implications for nerve cell survival and differentiation. Consequently, synaptogenesis, synapse elimination, and neurotransmitter release, are nitric oxide-modulated. Interesting, an emergent role of nitric oxide pathways has been discussed as regards neurotoxicity from glutamate-induced apoptosis. These findings suggest that nitric oxide pathways modulation could prevent oxidative damage to neurons through apoptosis inhibition. This review aims to highlight the emergent aspects of nitric oxide-mediated signaling in the brain, and how they can be related to neurotoxicity, as well as the development of neurodegenerative diseases development. Copyright © 2016 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. Lola regulates glutamate receptor expression at the Drosophila neuromuscular junction

    Directory of Open Access Journals (Sweden)

    Ai Fukui

    2012-02-01

    Communication between pre- and post-synaptic cells is a key process in the development and modulation of synapses. Reciprocal induction between pre- and postsynaptic cells involves regulation of gene transcription, yet the underlying genetic program remains largely unknown. To investigate how innervation-dependent gene expression in postsynaptic cells supports synaptic differentiation, we performed comparative microarray analysis of Drosophila muscles before and after innervation, and of prospero mutants, which show a delay in motor axon outgrowth. We identified 84 candidate genes that are potentially up- or downregulated in response to innervation. By systematic functional analysis, we found that one of the downregulated genes, longitudinals lacking (lola, which encodes a BTB-Zn-finger transcription factor, is required for proper expression of glutamate receptors. When the function of lola was knocked down in muscles by RNAi, the abundance of glutamate receptors (GluRs, GluRIIA, GluRIIB and GluRIII, as well as that of p-21 activated kinase (PAK, was greatly reduced at the neuromuscular junctions (NMJs. Recordings of the synaptic response revealed a decrease in postsynaptic quantal size, consistent with the reduction in GluR levels. Lola appears to regulate the expression of GluRs and PAK at the level of transcription, because the amount of mRNAs encoding these molecules was also reduced in the mutants. The transcriptional level of lola, in turn, is downregulated by increased neural activity. We propose that Lola coordinates expression of multiple postsynaptic components by transcriptional regulation.

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

    Science.gov (United States)

    Ferrari, Anna; Rustichelli, Cecilia; Baraldi, Carlo

    2017-12-01

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

  3. [Effects of dietary monosodium-glutamate on gene expression].

    Science.gov (United States)

    Jurasek, Júlia Vanda; Raposa, László Bence; Gubicskóné Kisbenedek, Andrea; Varga, Veronika; Szabó, Zoltán; Varjas, Tímea

    2017-03-01

    Nowadays, the food industry more often uses different type of additives during the food production. Our aim was to examine the monosodium-glutamate's effect (in animal experiment) on DNA-methyltransferases in gene expression patterns of mRNA levels. In the investigation we used 24 (n=24) CD1 type female mice. The animals were fed with different equivalent human doses of the tested substance. After autopsy, mRNA was isolated from different tissues (lung, liver, kidney, spleen). DNMT1, DNMT3A and DNMT3B levels were determined by Quantitative Real-Time PCR. DNMT1 significantly suppressed the gene expression in all the three treated groups (pmonosodium glutamate, suppressed the DNMT1 and DNMT3A gene expression - on mRNA levels of several organs - in mice. It can be a similar chemopreventive effect to epigallo-catechin-gallate's, curcumin's, genistein's, likopine's and rezveratrol's effects. In this case it can be possible that the MSG has anticarcinogenic effects. Orv. Hetil., 2017, 158(10), 380-385.

  4. Activity-Dependent Plasticity of Astroglial Potassium and Glutamate Clearance

    Directory of Open Access Journals (Sweden)

    Giselle Cheung

    2015-01-01

    Full Text Available Recent evidence has shown that astrocytes play essential roles in synaptic transmission and plasticity. Nevertheless, how neuronal activity alters astroglial functional properties and whether such properties also display specific forms of plasticity still remain elusive. Here, we review research findings supporting this aspect of astrocytes, focusing on their roles in the clearance of extracellular potassium and glutamate, two neuroactive substances promptly released during excitatory synaptic transmission. Their subsequent removal, which is primarily carried out by glial potassium channels and glutamate transporters, is essential for proper functioning of the brain. Similar to neurons, different forms of short- and long-term plasticity in astroglial uptake have been reported. In addition, we also present novel findings showing robust potentiation of astrocytic inward currents in response to repetitive stimulations at mild frequencies, as low as 0.75 Hz, in acute hippocampal slices. Interestingly, neurotransmission was hardly affected at this frequency range, suggesting that astrocytes may be more sensitive to low frequency stimulation and may exhibit stronger plasticity than neurons to prevent hyperexcitability. Taken together, these important findings strongly indicate that astrocytes display both short- and long-term plasticity in their clearance of excess neuroactive substances from the extracellular space, thereby regulating neuronal activity and brain homeostasis.

  5. Characterization of the Genes Encoding d-Amino Acid Transaminase and Glutamate Racemase, Two d-Glutamate Biosynthetic Enzymes of Bacillus sphaericus ATCC 10208

    Science.gov (United States)

    Fotheringham, Ian G.; Bledig, Stefan A.; Taylor, Paul P.

    1998-01-01

    In Bacillus sphaericus and other Bacillus spp., d-amino acid transaminase has been considered solely responsible for biosynthesis of d-glutamate, an essential component of cell wall peptidoglycan, in contrast to the glutamate racemase employed by many other bacteria. We report here the cloning of the dat gene encoding d-amino acid transaminase and the glr gene encoding a glutamate racemase from B. sphaericus ATCC 10208. The glr gene encodes a 28.8-kDa protein with 40 to 50% sequence identity to the glutamate racemases of Lactobacillus, Pediococcus, and Staphylococcus species. The dat gene encodes a 31.4-kDa peptide with 67% primary sequence homology to the d-amino acid transaminase of the thermophilic Bacillus sp. strain YM1. PMID:9696787

  6. 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.

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

    African Journals Online (AJOL)

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

  8. Surface grafting of poly (L-glutamates). 1. Synthesis and characterization

    NARCIS (Netherlands)

    Wieringa, RH; Siesling, EA; Geurts, PFM; Werkman, PJ; Vorenkamp, EJ; Erb, [No Value; Stamm, M; Schouten, AJ

    2001-01-01

    The ring-opening polymerization of N-carboxyanhydrides (NCA) of gamma -benzyl L-glutamate andy-methyl L-glutamate from (gamma -aminopropyl)triethoxysilane (APS) pretreated substrates such as silicon wafers and quartz slides was investigated. FT-IR transmission spectroscopy, circular dichroism

  9. Regulation of the Glutamate-Glutamine Transport System by Intracellular pH in Streptococcus lactis

    NARCIS (Netherlands)

    POOLMAN, B; HELLINGWERF, KJ; KONINGS, WN

    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

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

    African Journals Online (AJOL)

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

  11. 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.

  12. Headache and mechanical sensitization of human pericranial muscles after repeated intake of monosodium glutamate (MSG)

    DEFF Research Database (Denmark)

    Shimada, Akiko; Cairns, Brian; Vad, Nynne

    2013-01-01

    pressure were evaluated before and 15, 30, and 50 min after MSG intake. Whole saliva samples were taken before and 30 min after MSG intake to assess glutamate concentrations. Headache occurred in 8/14 subjects during MSG and 2/14 during placebo (P = 0.041). Salivary glutamate concentrations on Day 5 were...

  13. Differential distribution of group I metabotropic glutamate receptors in developing human cortex

    NARCIS (Netherlands)

    Boer, Karin; Encha-Razavi, Ferechte; Sinico, Martine; Aronica, Eleonora

    2010-01-01

    Neuronal and glial cells in human cerebral cortex are enriched in group I metabotropic glutamate receptors (mGluRs). Developmental regulation of mGluRs has been shown in rodent brain and recent studies suggest an involvement of mGluR-mediated glutamate signaling in the proliferation and survival of

  14. Extracellular striatal dopamine and glutamate after decortication and kainate receptor stimulation, as measured by microdialysis.

    Science.gov (United States)

    Smolders, I; Sarre, S; Vanhaesendonck, C; Ebinger, G; Michotte, Y

    1996-06-01

    Disruption of corticostriatal glutamate input in the striatum decreased significantly extracellular striatal glutamate and dopamine levels. Local administration of 300 microM concentration of excitatory receptor agonist kainic acid increased significantly extracellular striatal dopamine in intact freely moving rats. These findings support the hypothesis that glutamate exerts a tonic facilitatory effect on striatal dopamine release. The effect of kainic acid on extracellular striatal glutamate concentration in intact rats was a biphasic increase. The first glutamate increase can be explained by stimulation of presynaptic kainate receptors present on corticostriatal glutamatergic nerve terminals; the second increase is probably the result of a continuous interaction of the different striatal neurotransmitters after disturbance of their balance. Release of dopamine and glutamate was modulated differently in the intact striatum and in the striatum deprived of corticostriatal input. Dopamine release in the denervated striatum after kainate receptor stimulation was significantly lower than in intact striatum, confirming the so-called cooperativity between glutamate and kainic acid. Loss of presynaptic kainate receptors on the glutamatergic nerve terminals after decortication resulted in a loss of effect of kainic acid on glutamate release in denervated striatum. Aspartate showed no significant changes in this study.

  15. 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...

  16. 78 FR 57881 - Monosodium Glutamate from China and Indonesia; Institution of Antidumping and Countervailing Duty...

    Science.gov (United States)

    2013-09-20

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Monosodium Glutamate from China and Indonesia; Institution of Antidumping and Countervailing Duty... Indonesia of monosodium glutamate, provided for in subheading 2922.42.10 of the Harmonized Tariff Schedule...

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

    Science.gov (United States)

    Mita, Masatoshi

    2017-03-01

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

  18. Techno-economic assessment of the production of bio-based chemicals from glutamic acid

    NARCIS (Netherlands)

    Lammens, T.M.; Gangarapu, S.; Franssen, M.C.R.; Scott, E.L.; Sanders, J.P.M.

    2012-01-01

    In this review, possible process steps for the production of bio-based industrial chemicals from glutamic acid are described, including a techno-economic assessment of all processes. The products under investigation were those that were shown to be synthesized from glutamic acid on lab-scale, namely

  19. 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 glutamic acid decarboxylase isoform 65 in the septal region in glutamic acid decarboxylase-green fluorescent protein transgenic mice.

  20. 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 product. 573.500 Section 573.500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... fermentation product. Condensed, extracted glutamic acid fermentation product may be safely used in animal feed...

  1. 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 citratus essential oil treatment compared to glutamate group, significantly (p 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.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    To define the significance of glutamate ionotropic receptors in sPLA -mediated neuronal cell death we used the NMDA receptor antagonist MK-801 and the AMPA receptor antagonist PNQX. In primary neuronal cell cultures both MK-801 and PNQX inhibited sPLA - and glutamate-induced neuronal death. [ H]A...

  3. 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...

  4. The role of glutamine oxoglutarate aminotransferase and glutamate dehydrogenase in nitrogen metabolism in Mycobacterium bovis BCG.

    Directory of Open Access Journals (Sweden)

    Albertus J Viljoen

    Full Text Available Recent evidence suggests that the regulation of intracellular glutamate levels could play an important role in the ability of pathogenic slow-growing mycobacteria to grow in vivo. However, little is known about the in vitro requirement for the enzymes which catalyse glutamate production and degradation in the slow-growing mycobacteria, namely; glutamine oxoglutarate aminotransferase (GOGAT and glutamate dehydrogenase (GDH, respectively. We report that allelic replacement of the Mycobacterium bovis BCG gltBD-operon encoding for the large (gltB and small (gltD subunits of GOGAT with a hygromycin resistance cassette resulted in glutamate auxotrophy and that deletion of the GDH encoding-gene (gdh led to a marked growth deficiency in the presence of L-glutamate as a sole nitrogen source as well as reduction in growth when cultured in an excess of L-asparagine.

  5. Glutamate system, amyloid β peptides and tau protein: functional interrelationships and relevance to Alzheimer disease pathology

    Science.gov (United States)

    Revett, Timothy J.; Baker, Glen B.; Jhamandas, Jack; Kar, Satyabrata

    2013-01-01

    Alzheimer disease is the most prevalent form of dementia globally and is characterized premortem by a gradual memory loss and deterioration of higher cognitive functions and postmortem by neuritic plaques containing amyloid β peptide and neurofibrillary tangles containing phospho-tau protein. Glutamate is the most abundant neurotransmitter in the brain and is essential to memory formation through processes such as long-term potentiation and so might be pivotal to Alzheimer disease progression. This review discusses how the glutamatergic system is impaired in Alzheimer disease and how interactions of amyloid β and glutamate influence synaptic function, tau phosphorylation and neurodegeneration. Interestingly, glutamate not only influences amyloid β production, but also amyloid β can alter the levels of glutamate at the synapse, indicating that small changes in the concentrations of both molecules could influence Alzheimer disease progression. Finally, we describe how the glutamate receptor antagonist, memantine, has been used in the treatment of individuals with Alzheimer disease and discuss its effectiveness. PMID:22894822

  6. Glutamate system, amyloid ß peptides and tau protein: functional interrelationships and relevance to Alzheimer disease pathology.

    Science.gov (United States)

    Revett, Timothy J; Baker, Glen B; Jhamandas, Jack; Kar, Satyabrata

    2013-01-01

    Alzheimer disease is the most prevalent form of dementia globally and is characterized premortem by a gradual memory loss and deterioration of higher cognitive functions and postmortem by neuritic plaques containing amyloid ß peptide and neurofibrillary tangles containing phospho-tau protein. Glutamate is the most abundant neurotransmitter in the brain and is essential to memory formation through processes such as long-term potentiation and so might be pivotal to Alzheimer disease progression. This review discusses how the glutamatergic system is impaired in Alzheimer disease and how interactions of amyloid ß and glutamate influence synaptic function, tau phosphorylation and neurodegeneration. Interestingly, glutamate not only influences amyloid ß production, but also amyloid ß can alter the levels of glutamate at the synapse, indicating that small changes in the concentrations of both molecules could influence Alzheimer disease progression. Finally, we describe how the glutamate receptor antagonist, memantine, has been used in the treatment of individuals with Alzheimer disease and discuss its effectiveness.

  7. Sodium-stimulated glutamate transport in osmotically shocked cells and membrane vesicles of Escherichia coli.

    Science.gov (United States)

    Miner, K M; Frank, L

    1974-03-01

    Three phenotypically distinct strains of Escherichia coli B were studied: one in which the transport of glutamate was strongly stimulated by sodium, one in which the transport was relatively independent of sodium, and one which did not transport glutamate. Membrane vesicle preparations from the three strains followed the behavior of whole cells with respect to sodium-stimulated transport. Although glutamate-binding material could be released from cells by osmotic shock, its affinity for glutamate was not significantly influenced by sodium. Furthermore, the shocked cells retained sodium-stimulated transport. The accumulated results suggest that the sodium-activated glutamate transport system resides in the cytoplasmic membrane and that releasable binding protein(s) is not intimately involved in its function.

  8. 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.

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

    DEFF Research Database (Denmark)

    Venskutonyte, Raminta; Frydenvang, Karla; Gajhede, Michael

    2011-01-01

    present the first X-ray crystal structure of the ligand binding domain of GluK3 in complex with glutamate, determined to 1.6Å resolution. The structure reveals a conserved glutamate binding mode, characteristic for iGluRs, and a water molecule network in the glutamate binding site similar to that seen...

  10. N-methyl-D-glutamate and N-methyl-L-glutamate in Scapharca broughtonii (Mollusca) and other invertebrates.

    Science.gov (United States)

    Tarui, Atsuko; Shibata, Kimihiko; Takahashi, Shouji; Kera, Yoshio; Munegumi, Toratane; Yamada, Ryo-Hei

    2003-01-01

    The presence of N-methyl-D-glutamate (NMDG) and N-methyl-L-glutamate (NMLG) has been demonstrated in the tissues of Scapharca broughtonii, which are known to contain N-methyl-D-aspartate (NMDA). To our knowledge, this is the first report on the natural occurrence of NMDG and the occurrence of NMLG in eukaryotes. These compounds were identified according to the following findings; (a) their derivatives with (+)- and (-)-l-(9-fluorenyl)ethyl chloroformate (FLEC) showed identical behaviors with those of authentic NMDG and NMLA, respectively, on high-performance liquid chromatography (HPLC), (b) the HPLC peak of NMDG disappeared when the extract, as well as the authentic compound, was treated with D-aspartate oxidase before derivatization, (c) they behaved identically with authentic compounds on thin-layer chromatography and differently from NMDA. Both or either of NMDG and NMLG were also detected in several mollusks and other animals. Concentrations of the enantiomers were comparable in the tissues of S. broughtonii and a few other species.

  11. An amperometric biosensor for L-glutamate determination prepared from L-glutamate oxidase immobilized in polypyrrole-polyvinylsulphonate film.

    Science.gov (United States)

    Şimşek, Şule; Aynacı, Elif; Arslan, Fatma

    2016-01-01

    In this paper, a novel amperometric L-glutamate (Glu) biosensor with immobilization of L-glutamate oxidase (L-GlOx) on polypyrrole-polyvinylsulphonate (PPy-PVS) film has been successfully developed. L-GlOx enzyme was immobilized on PPy-PVS film by cross-linking with glutaraldehyde (GA) and bovine serum albumin (BSA). Determination of Glu was carried out by oxidation of enzymatically produced H2O2 at 0.3 V versus Ag/AgCl. The optimum pH and temperature parameters were found to be 9.0 and 55 °C, respectively. There were three linear parts in the regions between 1.0 × 10(-9) and 1.0 × 10(-8) M (R(2) = 0.847), 5.0 × 10(-8) and 5.0 × 10(-7) M (R(2) = 0.997), 5.0 × 10(-7) and 5.0 × 10(-5) M (R(2) = 0.994). Storage stability, operation stability of the enzyme electrode were also studied.

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

    OpenAIRE

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

    2007-01-01

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

  13. 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.

  14. Long-term NMDAR antagonism correlates reduced astrocytic glutamate uptake with anxiety-like phenotype

    Directory of Open Access Journals (Sweden)

    Eduardo R Zimmer

    2015-06-01

    Full Text Available The role of glutamate N-methyl-D-Aspartate receptor (NMDAR hypofunction has been extensively studied in schizophrenia; however, less is known about its role in anxiety disorders. Recently, it was demonstrated that astrocytic GLT-1 blockade leads to an anxiety-like phenotype. Although astrocytes are capable of modulating NMDAR activity through glutamate uptake transporters, the relationship between astrocytic glutamate uptake and the development of an anxiety phenotype remains poorly explored. Here, we aimed to investigative whether long-term antagonism of NMDAR impacts anxiety-related behaviors and astrocytic glutamate uptake. Memantine, an NMDAR antagonist, was administered daily for 24 days to healthy adult CF-1 mice by oral gavage at doses of 5, 10 or 20 mg/kg. The mice were submitted to a sequential battery of behavioral tests (open field, light-dark box and elevated plus-maze tests. We then evaluated glutamate uptake activity and the immunocontents of glutamate transporters in the frontoparietal cortex and hippocampus. Our results demonstrated that long-term administration of memantine induces anxiety-like behavior in mice in the light-dark box and elevated plus-maze paradigms. Additionally, the administration of memantine decreased glutamate uptake activity in both the frontoparietal cortex and hippocampus without altering the immunocontent of either GLT-1 or GLAST. Remarkably, the memantine-induced reduction in glutamate uptake was correlated with enhancement of an anxiety-like phenotype. In conclusion, long-term NMDAR antagonism with memantine induces anxiety-like behavior that is associated with reduced glutamate uptake activity but that is not dependent on GLT-1 or GLAST protein expression. Our study suggests that NMDAR and glutamate uptake hypofunction may contribute to the development of conditions that fall within the category of anxiety disorders.

  15. Glutamate export at the choroid plexus in health, thiamin deficiency, and ethanol intoxication: review and hypothesis.

    Science.gov (United States)

    Nixon, Peter F

    2008-08-01

    The earliest observed effect in the pathogenesis of experimental Wernicke's encephalopathy and of ethanol intoxication in rats is impairment of the blood cerebrospinal fluid (CSF) barrier at the choroid plexus (CP). For an explanation, these observations direct attention to the role of the CP in maintaining glutamate homeostasis in the CSF. Characteristics of the CP epithelium (CPE) are reviewed, focusing on its role in removal of glutamate from the CSF and its potential for impairment by ethanol oxidation or by thiamin-deficient glucose oxidation. The export of glutamate from CSF to blood at the CP is energy dependent, saturable, and stereospecific. However, the incapacity of the CP to convert glutamate to other metabolites makes it vulnerable to glutamate accumulation should alpha-ketoglutarate dehydrogenase activity be decreased. Elsewhere ethanol metabolism and thiamin-deficiency independently decrease the activity of this mitochondrial enzyme. We argue that they have the same effect within the mitochondria-rich CPE, thereby decreasing energy production necessary for export of glutamate from CSF to blood; diverting its energy metabolism to further glutamate production; and impairing its blood CSF barrier function. This impairment appears to be mediated by glutamate and is attenuated by MK801 but whether it involves one of the CPE glutamate receptors is yet uncertain. This impairment exposes the CSF and hence the paraventricular brain extracellular fluid to neuroactive substances from the blood, including further glutamate, explaining the paraventricular location of neuropathology in Wernicke's encephalopathy. Other organs normally protected from blood by a barrier are affected also by ethanol abuse and by thiamin deficiency, namely the eye, peripheral nerves, and the testis. Much less is known regarding the function of these barriers. Impairment of the CP by ethanol intoxication and by thiamin-deficient carbohydrate metabolism has a common, rational explanation

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

    Science.gov (United States)

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

    2003-01-01

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

  17. Ketamine and other glutamate receptor modulators for depression in adults.

    Science.gov (United States)

    Caddy, Caroline; Amit, Ben H; McCloud, Tayla L; Rendell, Jennifer M; Furukawa, Toshi A; McShane, Rupert; Hawton, Keith; Cipriani, Andrea

    2015-09-23

    Considering the ample evidence of involvement of the glutamate system in the pathophysiology of depression, pre-clinical and clinical studies have been conducted to assess the antidepressant efficacy of glutamate inhibition, and glutamate receptor modulators in particular. This review focuses on the use of glutamate receptor modulators in unipolar depression. To assess the effects - and review the acceptability - of ketamine and other glutamate receptor modulators in comparison to placebo (or saline placebo), other pharmacologically active agents, or electroconvulsive therapy (ECT) in alleviating the acute symptoms of depression in people with unipolar major depressive disorder. We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialised Register (CCDANCTR, to 9 January 2015). This register includes relevant randomised controlled trials (RCTs) from: the Cochrane Library (all years), MEDLINE (1950 to date), EMBASE (1974 to date), and PsycINFO (1967 to date). We did not apply any restrictions to date, language or publication status. Double- or single-blind RCTs comparing ketamine, memantine, or other glutamate receptor modulators with placebo (or saline placebo), other active psychotropic drugs, or electroconvulsive therapy (ECT) in adults with unipolar major depression. Three review authors independently identified studies, assessed trial quality and extracted data. The primary outcomes for this review were response rate and adverse events. We included 25 studies (1242 participants) on ketamine (9 trials), memantine (3), AZD6765 (3), D-cycloserine (2), Org26576 (2), atomoxetine (1), CP-101,606 (1), MK-0657 (1), N-acetylcysteine (1), riluzole (1) and sarcosine (1). Twenty-one studies were placebo-controlled and the majority were two-arm studies (23 out of 25). Twenty-two studies defined an inclusion criteria specifying the severity of depression; 11 specified at least moderate depression; eight, severe depression; and the remaining three

  18. l-Glutamic acid hydrochloride at 153 K

    Directory of Open Access Journals (Sweden)

    Zu-Guang Li

    2008-02-01

    Full Text Available The title compound [systematic name: (S-1,3-dicarboxypropanaminium chloride], C5H10NO4+·Cl−, has been investigated previously by Dawson [Acta Cryst. (1953. 6, 81–83], with R = 0.106 and without the location of H atoms, and then by Sequeira, Rajagopal & Chidambaram [Acta Cryst. (1972. B28, 2514–2519] using neutron diffraction with R = 0.043. The present determination at 153 K has R = 0.017 and all the H atoms are located. There are obvious differences in some C—C bond lengths between the present and previous studies. In the present structure, l-glutamic acid is protonated and is linked to the Cl− anion by an O—H...Cl hydrogen bond. The crystal structure is established by a three-dimensional network of O—H...O, N—H...O and N—H...Cl hydrogen bonds.

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

    DEFF Research Database (Denmark)

    Hogh, B; Petersen, E; Dziegiel, M

    1992-01-01

    areas of repeated amino acid sequences. Antibodies against recombinant GLURP489-1271, as well as against a synthetic peptide corresponding to GLURP899-916, and against a synthetic peptide representing the major glutamate rich repeat sequence from the P. falciparum ring erythrocyte surface antigen (Pf155....../RESA) (EENV)6 were examined in 423 individuals (age range 30 days-78 years) living in a malaria holoendemic area of Liberia. In the 5-9-year-old age group, subjects with anti-GLURP489-1271 antibody concentrations greater than the mean value of the group had lower parasite densities than those with low...... antibody concentrations (P = 0.0151). High levels of anti-GLURP899-916 antibodies did not correlate with low parasite densities. However, high levels of anti-(EENV)6 antibodies were associated with significantly lower parasite densities in the 2-4-year-old age group (P = 0.0189). There was no correlation...

  20. Methodology for Rapid Measures of Glutamate Release in Rat Brain Slices Using Ceramic-Based Microelectrode Arrays: Basic Characterization and Drug Pharmacology

    Science.gov (United States)

    Quintero, Jorge E.; Pomerleau, François; Huettl, Peter; Johnson, Kirk W.; Offord, James; Gerhardt, Greg A.

    2011-01-01

    Excessive excitability or hyperexcitability of glutamate-containing neurons in the brain has been proposed as a possible explanation for anxiety, stress-induced disorders, epilepsy, and some neurodegenerative diseases. However, direct measurement of glutamate on a rapid time scale has proven to be difficult. Here we adapted enzyme-based microelectrode arrays (MEA) capable of detecting glutamate in vivo, to assess the effectiveness of hyperexcitability modulators on glutamate release in brain slices of the rat neocortex. Using glutamate oxidase coated ceramic MEAs coupled with constant voltage amperometry, we measured resting glutamate levels and synaptic overflow of glutamate after K+ stimulation in brain slices. MEAs reproducibly detected glutamate on a second-by-second time scale in the brain slice preparation after depolarization with high K+ to evoke glutamate release. This stimulus-evoked glutamate release was robust, reproducible, and calcium dependent. The K+-evoked glutamate release was modulated by ligands to the a2δ subunit of voltage sensitive calcium channels (PD-0332334 and PD-0200390). Meanwhile, agonists to Group II metabotropic glutamate (mGlu) receptors (LY379268 and LY354740), which are known to alter hyperexcitability of glutamate neurons, attenuated K+-evoked glutamate release but did not alter resting glutamate levels. This new MEA technology provides a means of directly measuring the chemical messengers involved in glutamate neurotransmission and thereby helping to reveal the role multiple glutamatergic system components have on glutamate signaling. PMID:21664606

  1. Ebselen: Mechanisms of Glutamate Dehydrogenase and Glutaminase Enzyme Inhibition.

    Science.gov (United States)

    Yu, Yan; Jin, Yanhong; Zhou, Jie; Ruan, Haoqiang; Zhao, Han; Lu, Shiying; Zhang, Yue; Li, Di; Ji, Xiaoyun; Ruan, Benfang Helen

    2017-11-07

    Ebselen modulates target proteins through redox reactions with selenocysteine/cysteine residues, or through binding to the zinc finger domains. However, a recent contradiction in ebselen inhibition of kidney type glutaminase (KGA) stimulated our interest in investigating its inhibition mechanism with glutamate dehydrogenase (GDH), KGA, thioredoxin reductase (TrxR), and glutathione S-transferase. Fluorescein- or biotin-labeled ebselen derivatives were synthesized for mechanistic analyses. Biomolecular interaction analyses showed that only GDH, KGA, and TrxR proteins can bind to the ebselen derivative, and the binding to GDH and KGA could be competed off by glutamine or glutamate. From the gel shift assays, the fluorescein-labeled ebselen derivative could co-migrate with hexameric GDH and monomeric/dimeric TrxR in a dose-dependent manner; it also co-migrated with KGA but disrupted the tetrameric form of the KGA enzyme at a high compound concentration. Further proteomic analysis demonstrated that the ebselen derivative could cross-link with proteins through a specific cysteine at the active site of GDH and TrxR proteins, but for KGA protein, the binding site is at the N-terminal appendix domain outside of the catalytic domain, which might explain why ebselen is not a potent KGA enzyme inhibitor in functional assays. In conclusion, ebselen could inhibit enzyme activity by binding to the catalytic domain or disruption of the protein complex. In addition, ebselen is a relatively potent selective GDH inhibitor that might provide potential therapeutic opportunities for hyperinsulinism-hyperammonemia syndrome patients who have the mutational loss of GTP inhibition.

  2. Monosodium glutamate neonatal treatment as a seizure and excitotoxic model.

    Science.gov (United States)

    López-Pérez, Silvia Josefina; Ureña-Guerrero, Mónica Elisa; Morales-Villagrán, Alberto

    2010-03-04

    Monosodium glutamate (MSG) subcutaneously administrated to neonatal rats induces several neurochemical alterations in the brain, which have been associated with an excitotoxic process triggered by an over activation of glutamate receptors; however there are few systematic studies about initial changes in intracerebroventricular (i.c.v.) Glu levels produced by MSG in the brain. Thus, to characterize these changes, rat pups were injected with a MSG solution at 1, 3, 5 and 7 postnatal days (PD), and i.c.v. Glu levels and hippocampal total content of related amino acids (Asp, Glu, Gln, Gly, Tau, Ala and GABA) were estimated before, immediately and after each injection. Behavioral and EEG responses were also monitored after MSG administrations. Significant rise in i.c.v. Glu levels were found, mainly in response to the first and second injection. Moreover, the total content of all amino acids evaluated also increased during the first hour after the first MSG administration but only Glu and GABA remained elevated after 24 h. These biochemical modifications were accompanied with behavioral alterations characterized by: screeching, tail stiffness, head nodding, emprosthotonic flexion episodes and generalized tonic-clonic convulsions, which were associated with electroencephalographic pattern alterations. Altered behavior found in animals treated with MSG suggests an initial seizure situation. Although four MSG administrations were used, the most relevant findings were observed after the first and second administrations at PD1 and PD3, suggesting that only two MSG injections could be sufficient to resemble a seizure and/or excitotoxic model. 2009 Elsevier B.V. All rights reserved.

  3. Spinal control of erection by glutamate in rats.

    Science.gov (United States)

    Rampin, Olivier; Monnerie, Régine; Jérôme, Nathalie; McKenna, Kevin; Maurin, Yves

    2004-04-01

    The lumbosacral spinal network controlling penile erection is activated by information from peripheral and supraspinal origins. We tested the hypothesis that glutamate, released by sensory afferents from the genitals, activates this proerectile network. In anesthetized intact and T8 spinalized (i.e., freed from supraspinal inhibition) male rats, the parameters of electrical stimulation of the dorsal penile nerve (DPN) that elicited intracavernous pressure (ICP) rises were determined. In T8 spinalized rats, DPN stimulations were applied in the presence of d(-)-2-amino-5-phosphonopentanoic acid (d-AP5), a competitive NMDA receptor antagonist, or of 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulphonamide (NBQX), an AMPA-kainate receptor antagonist, injected intrathecally at the lumbosacral level. Both antagonists, alone or in combination, dose dependently decreased the ICP rise and increased its latency. In conscious rats, reflexive erections were depressed by d-AP5 and NBQX, as revealed by an increased latency of the first erection and by decreases of the number of rats displaying erections, of the number of erection clusters and of the number of erections per cluster. In anesthetized ats, the combined administration of the glutamatergic agonists NMDA and AMPA elicited ICP rises in the absence of DPN stimulation. In contrast, both agonists moderately decreased the ICP rise elicited by DPN stimulation but did not affect its latency. These results support our hypothesis that glutamate, released on stimulation of the genitals and acting at AMPA and NMDA receptors, is a potent reactivator of the spinal proerectile network.

  4. Presynaptic transporter-mediated release of glutamate evoked by the protonophore FCCP increases under altered gravity conditions

    Science.gov (United States)

    Borisova, T. A.; Krisanova, N. V.

    2008-12-01

    High-affinity Na +-dependent glutamate transporters of the plasma membrane mediate the glutamate uptake into neurons, and thus maintain low levels of extracellular glutamate in the synaptic cleft. The study focused on the release of glutamate by reversal of Na +-dependent glutamate transporters from rat brain nerve terminals (synaptosomes) under conditions of centrifuge-induced hypergravity. Flow cytometric analysis revealed similarity in the size and cytoplasmic granularity between synaptosomal preparations obtained from control and G-loaded animals (10 G, 1 h). The release of cytosolic L-[ 14C]glutamate from synaptosomes was evaluated using the protonophore FCCP, which dissipated synaptic vesicle proton gradient, thus synaptic vesicles were not able to keep glutamate inside and the latter enriched cytosol. FCCP per se induced the greater release of L-[ 14C]glutamate in hypergravity as compared to control (4.8 ± 1.0% and 8.0 ± 1.0% of total label). Exocytotic release of L-[ 14C]glutamate evoked by depolarization was reduced down to zero after FCCP application under both conditions studied. Depolarization stimulated release of cytosolic L-[ 14C]glutamate from synaptosomes preliminary treated with FCCP was considerably increased from 27.0 ± 2.2% of total label in control to 35.0 ± 2.3% in hypergravity. Non-transportable inhibitor of glutamate transporter DL-threo-β-benzyloxyaspartate was found to significantly inhibit high-KCl and FCCP-stimulated release of L-[ 14C]glutamate, confirming the release by reversal of glutamate transporters. The enhancement of transporter-mediated release of glutamate in hypergravity was found to result at least partially from the inhibition of the activity of Na/K-ATPase in the plasma membrane of synaptosomes. We suggested that hypergravity-induced alteration in transporter-mediated release of glutamate indicated hypoxic injury of neurons.

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

    Directory of Open Access Journals (Sweden)

    Naoya Murao

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

  6. Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

    Directory of Open Access Journals (Sweden)

    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.

  7. Beta-lactam antibiotics offer neuroprotection by increasing glutamate transporter expression.

    Science.gov (United States)

    Rothstein, Jeffrey D; Patel, Sarjubhai; Regan, Melissa R; Haenggeli, Christine; Huang, Yanhua H; Bergles, Dwight E; Jin, Lin; Dykes Hoberg, Margaret; Vidensky, Svetlana; Chung, Dorothy S; Toan, Shuy Vang; Bruijn, Lucie I; Su, Zao-Zhong; Gupta, Pankaj; Fisher, Paul B

    2005-01-06

    Glutamate is the principal excitatory neurotransmitter in the nervous system. Inactivation of synaptic glutamate is handled by the glutamate transporter GLT1 (also known as EAAT2; refs 1, 2), the physiologically dominant astroglial protein. In spite of its critical importance in normal and abnormal synaptic activity, no practical pharmaceutical can positively modulate this protein. Animal studies show that the protein is important for normal excitatory synaptic transmission, while its dysfunction is implicated in acute and chronic neurological disorders, including amyotrophic lateral sclerosis (ALS), stroke, brain tumours and epilepsy. Using a blinded screen of 1,040 FDA-approved drugs and nutritionals, we discovered that many beta-lactam antibiotics are potent stimulators of GLT1 expression. Furthermore, this action appears to be mediated through increased transcription of the GLT1 gene. beta-Lactams and various semi-synthetic derivatives are potent antibiotics that act to inhibit bacterial synthetic pathways. When delivered to animals, the beta-lactam ceftriaxone increased both brain expression of GLT1 and its biochemical and functional activity. Glutamate transporters are important in preventing glutamate neurotoxicity. Ceftriaxone was neuroprotective in vitro when used in models of ischaemic injury and motor neuron degeneration, both based in part on glutamate toxicity. When used in an animal model of the fatal disease ALS, the drug delayed loss of neurons and muscle strength, and increased mouse survival. Thus these studies provide a class of potential neurotherapeutics that act to modulate the expression of glutamate neurotransmitter transporters via gene activation.

  8. Circadian modulation of gene expression, but not glutamate uptake, in mouse and rat cortical astrocytes.

    Directory of Open Access Journals (Sweden)

    Christian Beaulé

    2009-10-01

    Full Text Available 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.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.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.

  9. Pinacidil and levamisole prevent glutamate-induced death of hippocampal neuronal cells through reducing ROS production.

    Science.gov (United States)

    Shukry, Mustafa; Kamal, Tarek; Ali, Radi; Farrag, Foad; Almadaly, Essam; Saleh, Ayman A; Abu El-Magd, Mohammed

    2015-10-01

    Activators of both adenosine 5'-triphosphate (ATP)-sensitive K(+) (KATP) channel and cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel have significant in vivo and in vitro neuroprotection against glutamate-induced death of some neuronal cells. Here, the effect of the KATP channel activator, pinacidil, and the CFTR Cl(-) channel opener, levamisole, against glutamate-induced oxidative stress were investigated in mouse hippocampal cells, HT22. The results from cell viability assay (WST-1) showed that pinacidil and levamisole weakly protected cells against glutamate-induced toxicity at 10 μM and their effect increased in a dose-dependent manner till reach maximum protection at 300 μM. Pretreatment with pinacidil or levamisole significantly suppressed the elevation of reactive oxygen species (ROS) triggered by glutamate through stabilising mitochondrial membrane potential and subsequently protected HT22 cells against glutamate-induced death. HT22 cells viability was maintained by pinacidil and levamisole in presence of glutathione inhibitor, BSO. Also, pinacidil and levamisole pretreatment did not induce recovery of glutathione levels decreased by glutamate Expectedly, this protection was abolished by the KATP and CFTR Cl(-) channels blocker, glibenclamide. Thus, both pinacidil and levamisole protect HT22 cells against glutamate-induced cell death through stabilising mitochondrial membrane potential and subsequently decreasing ROS production.

  10. Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents.

    Science.gov (United States)

    Konrad, Signorá Peres; Farah, Vera; Rodrigues, Bruno; Wichi, Rogério Brandão; Machado, Ubiratan Fabres; Lopes, Heno Ferreira; D'Agord Schaan, Beatriz; De Angelis, Kátia; Irigoyen, Maria Cláudia

    2012-10-01

    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. 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. 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. 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.

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

    Science.gov (United States)

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

    2017-08-01

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

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

    Science.gov (United States)

    Ito, Kotaro; Koyama, Yasuji; Hanya, Yoshiki

    2013-01-01

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

  13. 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.

  14. Low Dose Administration of Glutamate Triggers a Non-Apoptotic, Autophagic Response in PC12 Cells

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    Eleni Stamoula

    2015-11-01

    Full Text Available Background/Aims: Increasing amounts of the neurotransmitter glutamate are associated with excitotoxicity, a phenomenon related both to homeostatic processes and neurodegenerative diseases such as multiple sclerosis. Methods: PC12 cells (rat pheochromocytoma were treated with various concentrations of the non-essential amino acid glutamate for 0.5-24 hours. The effect of glutamate on cell morphology was monitored with electron microscopy and haematoxylin-eosin staining. Cell survival was calculated with the MTT assay. Expression analysis of chaperones associated with the observed phenotype was performed using either Western Blotting at the protein level or qRT-PCR at the mRNA level. Results: Administration of glutamate in PC12 cells in doses as low as 10 μM causes an up-regulation of GRP78, GRP94 and HSC70 protein levels, while their mRNA levels show the opposite kinetics. At the same time, GAPDH and GRP75 show reduced protein levels, irrespective of their transcriptional rate. On a cellular level, low concentrations of glutamate induce an autophagy-mediated pro-survival phenotype, which is further supported by induction of the autophagic marker LC3. Conclusion: The findings in the present study underline a discrete effect of glutamate on neuronal cell fate depending on its concentration. It was also shown that a low dose of glutamate orchestrates a unique expression signature of various chaperones and induces cell autophagy, which acts in a neuroprotective fashion.

  15. Expression of connexin genes in the human retina

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    Joussen Antonia

    2010-10-01

    Full Text Available Abstract Background Gap junction channels allow direct metabolically and electrical coupling between adjacent cells in various mammalian tissues. Each channel is composed of 12 protein subunits, termed connexins (Cx. In the mouse retina, Cx43 could be localized mostly between astroglial cells whereas expression of Cx36, Cx45 and Cx57 genes has been detected in different neuronal subtypes. In the human retina, however, the expression pattern of connexin genes is largely unknown. Methods Northern blot hybridizations, RT-PCR as well as immunofluorescence analyses helped to explore at least partially the expression pattern of the following human connexin genes GJD2 (hCx36, GJC1 (hCx45, GJA9 (hCx59 and GJA10 (hCx62 in the human retina. Results Here we report that Northern blot hybridization signals of the orthologuous hCx36 and hCx45 were found in human retinal RNA. Immunofluorescence signals for both connexins could be located in both inner and outer plexiform layer (IPL, OPL. Expression of a third connexin gene denoted as GJA10 (Cx62 was also detected after Northern blot hybridization in the human retina. Interestingly, its gene structure is similar to that of Gja10 (mCx57 being expressed in mouse horizontal cells. RT-PCR analysis suggested that an additional exon of about 25 kb further downstream, coding for 12 amino acid residues, is spliced to the nearly complete reading frame on exon2 of GJA10 (Cx62. Cx59 mRNA, however, with high sequence identity to zebrafish Cx55.5 was only weakly detectable by RT-PCR in cDNA of human retina. Conclusion In contrast to the neuron-expressed connexin genes Gjd2 coding for mCx36, Gjc1 coding for mCx45 and Gja10 coding for mCx57 in the mouse, a subset of 4 connexin genes, including the unique GJA9 (Cx59 and GJA10 (Cx62, could be detected at least as transcript isoforms in the human retina. First immunofluorescence analyses revealed a staining pattern of hCx36 and hCx45 expression both in the IPL and OPL, partially

  16. Acute treatment with doxorubicin affects glutamate neurotransmission in the mouse frontal cortex and hippocampus.

    Science.gov (United States)

    Thomas, Theresa Currier; Beitchman, Joshua A; Pomerleau, Francois; Noel, Teresa; Jungsuwadee, Paiboon; Allan Butterfield, D; Clair, Daret K St; Vore, Mary; Gerhardt, Greg A

    2017-10-01

    Doxorubicin (DOX) is a potent chemotherapeutic agent known to cause acute and long-term cognitive impairments in cancer patients. Cognitive function is presumed to be primarily mediated by neuronal circuitry in the frontal cortex (FC) and hippocampus, where glutamate is the primary excitatory neurotransmitter. Mice treated with DOX (25mg/kg i.p.) were subjected to in vivo recordings under urethane anesthesia at 24h post-DOX injection or 5 consecutive days of cognitive testing (Morris Water Maze; MWM). Using novel glutamate-selective microelectrode arrays, amperometric recordings measured parameters of extracellular glutamate clearance and potassium-evoked release of glutamate within the medial FC and dentate gyrus (DG) of the hippocampus. By 24h post-DOX injection, glutamate uptake was 45% slower in the FC in comparison to saline-treated mice. In the DG, glutamate took 48% longer to clear than saline-treated mice. Glutamate overflow in the FC was similar between treatment groups, however, it was significantly increased in the DG of DOX treated mice. MWM data indicated that a single dose of DOX impaired swim speed without impacting total length traveled. These data indicate that systemic DOX treatment changes glutamate neurotransmission in key nuclei associated with cognitive function within 24h, without a lasting impact on spatial learning and memory. Understanding the functional effects of DOX on glutamate neurotransmission may help us understand and prevent some of the debilitating side effects of chemotherapeutic treatment in cancer survivors. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Glutamate oxidase biosensor based on mixed ceria and titania nanoparticles for the detection of glutamate in hypoxic environments.

    Science.gov (United States)

    Özel, Rıfat Emrah; Ispas, Cristina; Ganesana, Mallikarjunarao; Leiter, J C; Andreescu, Silvana

    2014-02-15

    We report on the design and development of a glutamate oxidase (GmOx) microelectrode for measuring l-glutamic acid (GluA) in oxygen-depleted conditions, which is based on the oxygen storage and release capacity of cerium oxides. To fabricate the biosensor, a nanocomposite of oxygen-rich ceria and titania nanoparticles dispersed within a semi-permeable chitosan membrane was co-immobilized with the enzyme GmOx on the surface of a Pt microelectrode. The oxygen delivery capacity of the ceria nanoparticles embedded in a biocompatible chitosan matrix facilitated enzyme stabilization and operation in oxygen free conditions. GluA was measured by amperometry at a working potential of 0.6 V vs Ag/AgCl. Detection limits of 0.594 µM and 0.493 µM and a sensitivity of 793 pA/µM (RSD 3.49%, n=5) and 395 pA/µM (RSD 2.48%, n=5) were recorded in oxygenated and deoxygenated conditions, with response times of 2s and 5s, respectively. The biosensor had good operational stability and selectivity against common interfering substances. Operation of the biosensor was tested in cerebrospinal fluid. Preliminary in vivo recording in Sprague-Dawley rats to monitor GluA in the cortex during cerebral ischemia and reperfusion demonstrate a potential application of the biosensor in hypoxic conditions. This method provides a solution to ensure functionality of oxidoreductase enzymes in oxygen-free environments. © 2013 Elsevier B.V. All rights reserved.

  18. Assessment of monosodium glutamate (MSG) intake in a rural Thai community: questioning the methodological approach.

    Science.gov (United States)

    Chinna, Karuthan; Karupaiah, Tilakavati

    2013-07-26

    We examined the methodological approach to the assessment of monosodium glutamate intake. The high carbohydrate and low fat consumption characteristic of this study population would be conducive to the development of metabolic syndrome. However, anomalies in the assessment of dietary information limits conclusion to a causal link of monosodium glutamate to metabolic syndrome and overweight because the study lacks data on the main dietary patterns of consumption. Given the current paucity of data from human studies on monosodium glutamate intake and risk, more studies with robust methodology are required to assess causal links to disease.

  19. Glutamate-induced production of nitric oxide in guinea pig vestibular sensory cells.

    Science.gov (United States)

    Takumida, M; Anniko, M

    2000-06-01

    Glutamate-induced production of nitric oxide (NO) in the vestibular organ of the guinea pig was investigated using the new fluorescence indicator, DAF-2DA, for direct detection of NO. Utricular maculae and isolated vestibular sensory cells were examined to locate NO production sites. The fluorescence intensity of the sensory cells was augmented by stimulation with glutamate, NMDA and AMPA. This is the first direct evidence of NO production in the vestibular end organs. NO may play an important role in the glutamate-induced ototoxicity and also be involved in disease of the inner ear.

  20. 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....

  1. Pressor effects of L-glutamate injected into the diagonal band of Broca of unanesthetized rats.

    Science.gov (United States)

    Tavares, Rodrigo Fiacadori; de Aguiar Corrêa, Fernando Morgan

    2003-01-10

    The diagonal band of Broca (dbB) is involved in central cardiovascular control. In the present study we compared the effects of microinjections of L-glutamate into the dbB of unanesthetized rats with those observed after the injection of L-glutamate into the same area in urethane-anesthetized rats. The microinjection of L-glutamate (10, 30, 100 or 200 nmol/200 nl) into the dbB of urethane-anesthetized rats caused dose-related short-lasting depressor responses The depressor responses to L-glutamate were accompanied by dose-related heart rate reduction. The cardiovascular response to the injection of L-glutamate (10, 30 or 100 nmol/200 nl) into the dbB of unanesthetized rats was characterized as a long-lasting pressor response without consistent heart rate changes. The pressor response was dose-related and presented an ED(50) of approximately 30 nmol/200 nl. The fact that the chemical stimulation of the dbB with L-glutamate caused only dose-related pressor responses in unanesthetized rats suggests that under normal conditions the dbB is predominantly a pressor area. After the characterization of the pressor response to L-glutamate microinjected into the dbB of unanesthetized rats we studied the mechanisms involved in the mediation of these responses. The pressor response to L-glutamate (30 nmol/200 nl) into the dbB was blocked by intravenous pretreatment with the vasopressin antagonist dTyr(CH(2))(5)(Me)AVP (50 microg/kg), suggesting the involvement of circulating vasopressin in this response. Further evidence of the involvement of the endocrine vasopressin system in the pressor response to L-glutamate injected into the dbB was provided by hypophysectomy since L-glutamate (30 nmol/200 nl) microinjection into the dbB of hypophysectomized rats caused only depressor responses. We presently report that chemical stimulation of the dbB with L-glutamate caused only pressor responses in unanesthetized rats that were mediated by vasopressin release into the systemic

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Glutamate is the main excitatory transmitter in the brain, while ATP represents the most important energy currency in any living cell. Yet, these chemicals play an important role in both processes, enabling them with dual-acting functions in metabolic and intercellular signaling pathways. Glutamate....... It is astroglial receptors for these dual-acting molecules that could hold a key for medical intervention in pathological conditions. We focus on two examples disclosing the role of activation of astroglial ATP and glutamate receptors in pathology of two kinds of brain tissue, gray matter and white matter......, respectively. Interventions at the interface of metabolism and signaling show promise for translational medicine....

  3. Synthesis and Characterization of Glutamic-Chitosan Hydrogel for Copper and Nickel Removal from Wastewater

    Directory of Open Access Journals (Sweden)

    Huda E. Abdelwahab

    2016-05-01

    Full Text Available Chitosan was reacted with four concentrations (2.5, 5, 10 and 20 mmol of glutamic acid resulting in four types of glutamic-chitosan hydrogels (GCs, the activity of the resulted compounds on the removal of copper(II and nickel(II from wastewater were tested. The results indicated that by increasing glutamic acid concentration from GCs-1 to GCs-4, the efficiency of removing Cu(II and Ni(II were decreased, which may be due to a decrease in the pore size of the hydrogels as a result of the increased degree of crosslinking.

  4. A Two-Input Fluorescent Logic Gate for Glutamate and Zinc.

    Science.gov (United States)

    Yin, Caixia; Huo, Fangjun; Cooley, Nicholas P; Spencer, David; Bartholomew, Kyle; Barnes, Charles L; Glass, Timothy E

    2017-06-21

    The direct visualization of neurotransmitters is a continuing problem in neuroscience; however, functional fluorescent sensors for organic analytes are still rare. Herein, we describe a fluorescent sensor for glutamate and zinc ions. The sensor acts as a fluorescent logic gate, giving a turn-off response to glutamate or zinc ion alone. The combination of analytes produces a large increase in fluorescence. This type of sensor will aid in the study of neurotransmission, in this case, for neurons that copackage high concentrations of zinc and glutamate.

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

    OpenAIRE

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

    2017-01-01

    This study investigated the effects of glutamic acid on production of monacolin K and expression of the monacolin K biosynthetic gene cluster. When Monascus M1 was grown in glutamic medium instead of in the original medium, monacolin K production increased from 48.4 to 215.4?mg?l?1, monacolin K production increased by 3.5 times. Glutamic acid enhanced monacolin K production by upregulating the expression of mokB-mokI; on day 8, the expression level of mokA tended to decrease by Reverse Transc...

  6. Glutamate Transport System as a Novel Therapeutic Target in Chronic Pain

    DEFF Research Database (Denmark)

    Gegelashvili, Georgi; Bjerrum, Ole Jannik

    2017-01-01

    The vast majority of peripheral neurons sensing noxious stimuli and conducting pain signals to the dorsal horn of the spinal cord utilize glutamate as a chemical transmitter of excitation. High-affinity glutamate transporter subtypes GLAST/EAAT1, GLT1/EAAT2, EAAC1/EAAT3, and EAAT4, differentially...... pain treatment. However, design and development of new analgesics based on the modulation of glutamate uptake will require more precise knowledge of molecular mechanisms underlying physiological or aberrant functioning of this transport system in the spinal cord....

  7. Ischemic damage in hippocampal CA1 is dependent on glutamate release and intact innervation from CA3

    DEFF Research Database (Denmark)

    Benveniste, H; Jørgensen, M B; Sandberg, M

    1989-01-01

    The removal of glutamatergic afferents to CA1 by destruction of the CA3 region is known to protect CA1 pyramidal cells against 10 min of transient global ischemia. To investigate further the pathogenetic significance of glutamate, we measured the release of glutamate in intact and CA3-lesioned CA1...... hippocampal tissue. In intact CA1 hippocampal tissue, glutamate increased sixfold during ischemia; in the CA3-lesioned CA1 region, however, glutamate only increased 1.4-fold during ischemia. To assess the neurotoxic potential of the ischemia-induced release of glutamate, we injected the same concentration...... of glutamate into the CA1 region as is released during ischemia in normal, CA3-lesioned, and ischemic CA1 tissue. We found that this particular concentration of glutamate was sufficient to destroy CA1 pyramids in the vicinity of the injection site in intact and CA3-lesioned CA1 tissue when administered during...

  8. 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%.

  9. RuBi-Glutamate: Two-photon and visible-light photoactivation of neurons and dendritic spines

    Directory of Open Access Journals (Sweden)

    Elodie Fino

    2009-05-01

    Full Text Available We describe neurobiological applications of RuBi-Glutamate, a novel caged-glutamate compound based on ruthenium photochemistry. RuBi-Glutamate can be excited with visible wavelengths and releases glutamate after one- or two-photon excitation. It has high quantum efficiency and can be used at low concentrations, partly avoiding the blockade of GABAergic transmission present with other caged compounds. Two-photon uncaging of RuBi-glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics. With laser beam multiplexing, RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution. RuBi-Glutamate therefore enables the photo-activation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single spine, or single cell, precision.

  10. Glutamic acid independent production of poly-γ-glutamic acid by Bacillus amyloliquefaciens LL3 and cloning of pgsBCA genes.

    Science.gov (United States)

    Cao, Mingfeng; Geng, Weitao; Liu, Li; Song, Cunjiang; Xie, Hui; Guo, Wenbin; Jin, Yinghong; Wang, Shufang

    2011-03-01

    A new glutamic acid independent poly-γ-glutamic acid (γ-PGA) producing strain, which was identified as Bacillus amyloliquefaciens LL3 by analysis of 16S rDNA and gyrase subunit A gene (gyrA), was isolated from fermented food. The product had a molecular weight of 470, 801 and l-glutamate monomer content of 98.47%. The pre-optimal medium, based on single-factor tests and orthogonal design, contained 50 g/L sucrose, 2g/L (NH(4))(2)SO(4), 0.6g/L MgSO(4), and provided well-balanced changes in processing parameters and a γ-PGA yield of 4.36 g/L in 200 L system. The γ-PGA synthetase genes pgsBCA were cloned from LL3, and successfully expressed by pTrcLpgs vector in Escherichia coli JM109, resulting the synthesis of γ-PGA without glutamate. This study demonstrates the designedly improved yield of γ-PGA in 200 L system and the first report of pgsBCA from glutamic acid independent strain, which will benefit the metabolized mechanism investigation and the wide-ranging application of γ-PGA. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. High-level exogenous glutamic acid-independent production of poly-(γ-glutamic acid) with organic acid addition in a new isolated Bacillus subtilis C10.

    Science.gov (United States)

    Zhang, Huili; Zhu, Jianzhong; Zhu, Xiangcheng; Cai, Jin; Zhang, Anyi; Hong, Yizhi; Huang, Jin; Huang, Lei; Xu, Zhinan

    2012-07-01

    A new exogenous glutamic acid-independent γ-PGA producing strain was isolated and characterized as Bacillus subtilis C10. The factors influencing the endogenous glutamic acid supply and the biosynthesis of γ-PGA in this strain were investigated. The results indicated that citric acid and oxalic acid showed the significant capability to support the overproduction of γ-PGA. This stimulated increase of γ-PGA biosynthesis by citric acid or oxalic acid was further proved in the 10 L fermentor. To understand the possible mechanism contributing to the improved γ-PGA production, the activities of four key intracellular enzymes were measured, and the possible carbon fluxes were proposed. The result indicated that the enhanced level of pyruvate dehydrogenase (PDH) activity caused by oxalic acid was important for glutamic acid synthesized de novo from glucose. Moreover, isocitrate dehydrogenase (ICDH) and glutamate dehydrogenase (GDH) were the positive regulators of glutamic acid biosynthesis, while 2-oxoglutarate dehydrogenase complex (ODHC) was the negative one. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Hydrochloric acid alters the effect of L-glutamic acid on cell viability in human neuroblastoma cell cultures.

    Science.gov (United States)

    Croce, Nicoletta; Bernardini, Sergio; Di Cecca, Stefano; Caltagirone, Carlo; Angelucci, Francesco

    2013-07-15

    l-Glutamic acid (l-glutamate) is used to induce excitotoxicity and test neuroprotective compounds in cell cultures. However, because l-glutamate powder is nearly insoluble in water, many manufacturers recommend reconstituting l-glutamate in hydrochloric acid (HCl) prior to successive dilutions. Nevertheless, HCl, even at low concentrations, may alter the pH of the cell culture medium and interfere with cell activity. Thus, the aim of this study was to evaluate whether the reconstitution of l-glutamate powder in HCl alters its capacity to induce neurotoxicity in different human neuroblastoma cell lines. SH-SY5Y, IMR-32 and SK-N-BE(2) cells were exposed to various concentrations of l-glutamate, which was either reconstituted in HCl (1M) or post re-equilibrated to the pH of the culture medium (7.5). After 24 and 48h of incubation, changes in the cell viability of treated versus untreated cells were evaluated. The effect of an identical amount of HCl present in the l-glutamate dilutions on neuroblastoma cell survival was also investigated. Our data showed that the neurotoxicity of glutamate reconstituted in HCl was comparable to that of HCl alone. Moreover, the pH variations induced by glutamate or HCl in the culture medium were similar. When the pH of the glutamate stock solution was re-equilibrated, l-glutamate induced variation in cell viability to a lower extent and after a longer incubation time. This study demonstrated that HCl used to reconstitute l-glutamate powder might alter the effect of glutamate itself in neuroblastoma cell cultures. Thus, this information might be useful to scientists who use l-glutamate to induce excitotoxicity or to test neuroprotective agents. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Monosodium glutamate avoidance for chronic asthma in adults and children.

    Science.gov (United States)

    Zhou, Yan; Yang, Ming; Dong, Bi Rong

    2012-06-13

    Monosodium glutamate (MSG) is the sodium salt of the non-essential amino acid, glutamic acid, and is used as a flavour enhancer. It has been implicated in causing adverse reactions, which have been referred to as "Chinese restaurant syndrome". Over the last two decades there have been a number of studies investigating whether MSG ingestion induces an asthmatic response, and several reviews have been published (ILSI 1991; Stevenson 2000; Woods 2001), but no meta-analysis or Cochrane systematic review has been performed. The objectives of this review are to: 1) identify randomised controlled trials (RCTs) of MSG ingestion and asthma response in adults and children older than two years of age with asthma; 2) assess the methodological quality of these trials; and 3) determine the effect of MSG ingestion on asthma outcomes. We searched the Cochrane Airways group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), and bibliographies of existing trials. Searches were current up to May 2012. We included RCTs that investigated the effect of MSG on chronic asthma in adults and children. Two authors independently extracted, entered and analysed data from included studies. We contacted study authors for additional information. Only two cross-over studies involving 24 adults met the eligibility criteria; the challenge dosages of MSG were 1 g, 5 g and 25 mg/kg. They reported the number of subjects who had a maximum fall in forced expiratory volume in the first second (FEV(1)) greater than 15% or 200 mL after MSG or the control challenge. The pooled data found no statistically significant difference between MSG and placebo. One trial reported the mean change at four hours and maximum fall in FEV(1) over four hours after MSG or the placebo challenge, but found no statistically significant difference between interventions. There were no differences in symptom scores, non-specific bronchial hyper-responsiveness (BHR), eosinophil cationic protein

  14. Molecular cloning, expression, and immobilization of glutamate decarboxylase from Lactobacillus fermentum YS2

    Directory of Open Access Journals (Sweden)

    Qian Lin

    2017-05-01

    Conclusions: RAC could be used as an adsorbent in one-step purification and immobilization of CBM-GAD, and the immobilized enzyme could be repeatedly used to catalyze the conversion of glutamate to GABA.

  15. Evaluation of permselective membranes for optimization of intracerebral amperometric glutamate biosensors

    NARCIS (Netherlands)

    Wahono, N.; Qin, S.; Oomen, P.; Cremers, T. I. F.; de Vries, M. G.; Westerink, B. H. C.

    2012-01-01

    Monitoring of extracellular brain glutamate concentrations by intracerebral biosensors is a promising approach to further investigate the role of this important neurotransmitter. However, amperometric biosensors are typically hampered by Faradaic interference caused by the presence of other

  16. Acute cerebellar ataxia and consecutive cerebellitis produced by glutamate receptor delta2 autoantibody.

    Science.gov (United States)

    Shiihara, Takashi; Kato, Mitsuhiro; Konno, Akihiro; Takahashi, Yukitoshi; Hayasaka, Kiyoshi

    2007-05-01

    Acute cerebellar ataxia is usually a self-limited benign disease, which may develop in children after certain viral infections or vaccinations. There are several reports of acute cerebellar ataxia associated with autoantibodies. Glutamate receptor delta2, a member of the glutamate receptor family, is predominantly expressed in cerebellar Purkinje cells and plays a crucial role in cerebellar functions. To date anti-GluRdelta2 autoantibody was detected in a patient with chronic cerebellitis. Herein, an 18-month-old boy presented with cerebellar ataxia 9 days following a mild respiratory tract infection. Although cerebellar ataxia gradually improved, it worsened yet again following mumps and varicella virus infection. Cerebro-spinal fluid examination and magnetic resonance imaging of the brain demonstrated pleocytosis and meningeal enhancement, respectively. Furthermore, glutamate receptor delta2 autoantibody was detected in serum and cerebro-spinal fluid. Thus, we believe that the glutamate receptor delta2 autoantibody may play a role in cerebellar ataxia and consecutive cerebellitis.

  17. Reconsolidation of Reminder-Induced Amnesia: Role of NMDA and AMPA Glutamate Receptors.

    Science.gov (United States)

    Nikitin, V P; Kozyrev, S A; Solntseva, S V

    2015-11-01

    We studied the role of glutamate receptors and reminder in the mechanisms of amnesia maintenance caused by disruption of conditioned food aversion reconsolidation with an antagonist of NMDA glutamate receptor in snails. At the early stage of amnesia (day 3 after induction), injection or NMDA of AMPA glutamate receptor antagonists prior to reminder (presentation of the conditioned food stimulus) led to memory recovery. Reminder alone or injection of antagonists without reminder or after reminder was ineffective. At the late stage of amnesia (day 10), antagonists/reminder had no effect on amnesia maintenance. It was hypothesized that reminder at the early stage of amnesia led to reactivation and reconsolidation of the molecular processes of amnesia including activation NMDA and AMPA glutamate receptors. Injection of antagonists of these receptors prior to reminder led to disruption of reactivation/reconsolidation of amnesia and recovery of the conditioned food aversion memory.

  18. VGLUTs and Glutamate Synthesis—Focus on DRG Neurons and Pain

    Directory of Open Access Journals (Sweden)

    Mariana Malet

    2015-12-01

    Full Text Available The amino acid glutamate is the principal excitatory transmitter in the nervous system, including in sensory neurons that convey pain sensation from the periphery to the brain. It is now well established that a family of membrane proteins, termed vesicular glutamate transporters (VGLUTs, serve a critical function in these neurons: they incorporate glutamate into synaptic vesicles. VGLUTs have a central role both under normal neurotransmission and pathological conditions, such as neuropathic or inflammatory pain. In the present short review, we will address VGLUTs in the context of primary afferent neurons. We will focus on the role of VGLUTs in pain triggered by noxious stimuli, peripheral nerve injury, and tissue inflammation, as mostly explored in transgenic mice. The possible interplay between glutamate biosynthesis and VGLUT-dependent packaging in synaptic vesicles, and its potential impact in various pain states will be presented.

  19. Removal of lead from aqueous solution on glutamate intercalated layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Shen Yanming

    2017-05-01

    Full Text Available Glutamate intercalated Mg–Al layered double hydroxide (LDH was prepared by co-precipitation and the removal of Pb2+ in the aqueous solution was investigated. The prepared samples were characterized by XRD, FT-IR and SEM. It was shown that glutamate can intercalate into the interlayer space of Mg–Al LDH. The glutamate intercalated Mg–Al LDH can effectively adsorb Pb2+ in the aqueous solution with an adsorption capacity of 68.49 mg g−1. The adsorption of Pb2+ on glutamate intercalated Mg–Al LDH fitted the pseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.

  20. 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 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...

  1. [Imbalance of system of glutamin - glutamic acid in the placenta and amniotic fluid at placental insufficiency].

    Science.gov (United States)

    Pogorelova, T N; Gunko, V O; Linde, V A

    2014-01-01

    Metabolism of glutamine and glutamic acid has been investigated in the placenta and amniotic fluid under conditions of placental insufficiency. The development of placental insufficiency is characterized by the increased content of glutamic acid and a decrease of glutamine in both placenta and amniotic fluid. These changes changes were accompanied by changes in the activity of enzymes involved in the metabolism of these amino acids. There was a decrease in glutamate dehydrogenase activity and an increase in glutaminase activity with the simultaneous decrease of glutamine synthetase activity. The compensatory decrease in the activity of glutamine keto acid aminotransferase did not prevent a decrease in the glutamine level. The impairments in the system glutamic acid-glutamine were more pronounced during the development of premature labor.

  2. 78 FR 65278 - Monosodium Glutamate From the People's Republic of China, and the Republic of Indonesia...

    Science.gov (United States)

    2013-10-31

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF COMMERCE... Operations, Office VII, Enforcement and Compliance, International Trade Administration, U.S. Department of... Antidumping Duty Investigation Initiation Checklist: Monosodium Glutamate from Indonesia (Indonesia AD...

  3. 78 FR 65269 - Monosodium Glutamate From the People's Republic of China and the Republic of Indonesia...

    Science.gov (United States)

    2013-10-31

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE..., respectively, AD/CVD Operations, Office 6, Enforcement and Compliance, International Trade Administration, U.S... Countervailing Duty Investigation Initiation Checklist: Monosodium Glutamate from Indonesia (Indonesia CVD...

  4. A selective review of glutamate pharmacological therapy in obsessive–compulsive and related disorders

    Science.gov (United States)

    Grados, Marco A; Atkins, Elizabeth B; Kovacikova, Gabriela I; McVicar, Erin

    2015-01-01

    Glutamate, an excitatory central nervous system neurotransmitter, is emerging as a potential alternative pharmacological treatment when compared to gamma-aminobutyric acid (GABA)-, dopamine-, and serotonin-modulating treatments for neuropsychiatric conditions. The pathophysiology, animal models, and clinical trials of glutamate modulation are explored in disorders with underlying inhibitory deficits (cognitive, motor, behavioral) including obsessive–compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, trichotillomania, excoriation disorder, and nail biting. Obsessive–compulsive disorder, attention deficit hyperactivity disorder, and grooming disorders (trichotillomania and excoriation disorder) have emerging positive data, although only scarce controlled trials are available. The evidence is less supportive for the use of glutamate modulators in Tourette syndrome. Glutamate-modulating agents show promise in the treatment of disorders of inhibition. PMID:25995654

  5. Effect of parental morphine addiction on extracellular glutamate concentration of dentate gyrus in rat offsprings

    Directory of Open Access Journals (Sweden)

    rahele Assaee

    2004-01-01

    Findings: In male offsprings of sham control1, sham control2, test1 and test2 basal and electrical stimulated of extracellular glutamate concentration of dentate gyrus were: 0.67±0.04, 1.11±0.1, and in female offsprings were 0.47±0.06, 0.88±0.05 (n=5. The basal and stimulated extra cellular glutamate concentration of dentate gyrus was decreased in both test1 and test2 offsprings. It was less in test1 than test2 offsprings. The glutamate concentration of dentate gyrus in female offsprings of test1 group was less than that of the male offsprings. conclusion: The results suggest that parental morphine addiction may cause learning deficiency through reduction of extracellular glutamate concentration in dentate gyrus so the side effects of parental morphine addiction in offsprings must be considered.

  6. Evidence of activation of the renal glutamate dehydrogenase pathway in intact acidotic dogs.

    Science.gov (United States)

    Lombardo, J V; Risquez, A; McCarthy, M; Preuss, H G

    1981-04-01

    To determine if activity of the renal glutamate dehydrogenase (GD) pathway changes during chronic acidosis in intact dogs, we assessed the deamination of glutamate formed within renal cells during glutamine and alanine infusions. Infusing glutamine into chronically acidotic, normal and acutely alkalotic dogs enhanced renal ammonia production; more was formed as glutamine loading increased. In 4 acidotic dogs, the ratio of ammonia produced to glutamine extracted by the kidneys during exogenous glutamine loading was 1.93 compared with 0.99 for 5 alkalotic dogs and 1.23 for 2 control dogs. Little glutamate and alanine were released into the renal vein in acidotic dogs, whereas over 50% of the exogenous glutamine extracted in acutely alkalotic dogs could be accounted for as glutamate and alanine released into the renal vein. Renal glutamate concentrations were not elevated in acidosis compared with alkalosis despite greater deamidation. When glutamine infusions increased renal ammoniagenesis in acutely alkalotic and control dogs to levels seen in chronically acidotic dogs receiving no exogenous glutamine, approximately 4 to 6 times more glutamate was released from the kidneys. Infusing alanine into 7 chronically acidotic dogs enhanced ammoniagenesis significantly (p less than 0.01), but lesser augmentation was seen in 3 control dogs and no augmentation was seen in 6 acutely alkalotic dogs. The increases were secondary to enhanced glutamate deamination, not secondary to any changes in glutamine extraction and/or transaminase activity. We conclude that the glutamate dehydrogenase pathway is more active in intact acidotic dogs than it is in control and alkalotic dogs.

  7. The neurotransmitters serotonin and glutamate accelerate the heart rate of the mosquito Anopheles gambiae.

    Science.gov (United States)

    Hillyer, Julián F; Estévez-Lao, Tania Y; Mirzai, Homa E

    2015-10-01

    Serotonin and glutamate are neurotransmitters that in insects are involved in diverse physiological processes. Both serotonin and glutamate have been shown to modulate the physiology of the dorsal vessel of some insects, yet until the present study, their activity in mosquitoes remained unknown. To test whether serotonin or glutamate regulate dorsal vessel physiology in the African malaria mosquito, Anopheles gambiae, live mosquitoes were restrained, and a video of the contracting heart (the abdominal portion of the dorsal vessel) was acquired. These adult female mosquitoes were then injected with various amounts of serotonin, glutamate, or a control vehicle solution, and additional videos were acquired at 2 and 10 min post-treatment. Comparison of the videos taken before and after treatment revealed that serotonin accelerates the frequency of heart contractions, with the cardioacceleration being significantly more pronounced when the wave-like contractions of cardiac muscle propagate in the anterograde direction (toward the head). Comparison of the videos taken before and after treatment with glutamate revealed that this molecule is also cardioacceleratory. However, unlike serotonin, the activity of glutamate does not depend on whether the contractions propagate in the anterograde or the retrograde (toward the posterior of the abdomen) directions. Serotonin or glutamate induces a minor change or no change in the percentage of contractions and the percentage of the time that the heart contracts in the anterograde or the retrograde directions. In summary, this study shows that the neurotransmitters serotonin and glutamate increase the heart contraction rate of mosquitoes. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Glutamate dehydrogenase of the unicellular green alga Scenedesmus acutus : Substrate-induced conformational transition.

    Science.gov (United States)

    Shatilov, V R; Sund, H

    1983-07-01

    The coenzyme-non-specific glutamate dehydrogenase (EC 1.4.1.3) from Scenedesmus acutus in inhibited by p-hydroxymercuribenzoate only in the deamination reaction. From this result and from its stability in the presence of urea it is concluded that this enzyme exhibits and equilibrium between three conformations: aminating and deaminating conformations induced by NADH-2-oxoglutarate and NAD(+)-glutamate, respectively, and the "native" conformation in the absence of substrates.

  9. Cardioprotective effect of L-glutamate in obese type 2 diabetic Zucker fatty rats

    DEFF Research Database (Denmark)

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

    2009-01-01

    was downregulated in hearts from ZDF rats at both the mRNA and protein levels (P change in EAAT3 expression at the protein level. Myocardial L-glutamate content was increased by 43% in diabetic hearts (P ... an elevated threshold for metabolic postischaemic cardioprotection by L-glutamate. These findings may reflect underlying mechanisms of inherent resistance against additional cardioprotection in the diabetic heart....

  10. Robustness in Escherichia coli Glutamate and Glutamine Synthesis Studied by a Kinetic Model

    OpenAIRE

    Lodeiro, Aníbal; Melgarejo, Augusto

    2008-01-01

    Metabolic control of glutamine and glutamate synthesis from ammonia and oxoglutarate in Escherichia coli is tight and complex. In this work, the role of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) regulation in this control was studied. Both enzymes form a linear pathway, which can also have a cyclic topology if glutamate–oxoglutarate amino transferase (GOGAT) activity is included. We modelled the metabolic pathways in the linear or cyclic topologies using a coupled nonlinear...

  11. Intraplantar injection of gangliosides produces nociceptive behavior and hyperalgesia via a glutamate signaling mechanism.

    Science.gov (United States)

    Watanabe, Shun; Tan-No, Koichi; Tadano, Takeshi; Higashi, Hideyoshi

    2011-02-01

    Gangliosides are abundant in neural tissue and play important roles in cell-cell adhesion, signal transduction, and cell differentiation. Gangliosides are divided into 4 groups: asialo-, a-, b-, and c-series gangliosides, based on their biosynthetic pathway. St8sia1 knockout mice, which lack b- and c-series gangliosides, exhibit altered nociceptive responses. The mechanism underlying this defect, however, remains unclear. To address this issue, we first investigated the possibility that gangliosides in peripheral nociceptor endings are involved in nociception. Intraplantar injection of the b-series ganglioside GT1b, but not a-series gangliosides such as GM1, produced nociceptive responses and enhanced low-concentration formalin-induced nociception. N-methyl-d-aspartic acid receptor and type I metabotropic glutamate receptor antagonists inhibited GT1b-induced hyperalgesia, suggesting the involvement of glutamate receptors. Furthermore, microdialysis analysis revealed elevated glutamate content in subdermal tissues due to intraplantar injection of GT1b. Co-injection of glutamate dehydrogenase with GT1b attenuated GT1b-induced hyperalgesia. These findings suggested that GT1b induced extracellular glutamate to accumulate in subdermal tissues, thereafter activating glutamate receptors, which in turn resulted in hyperalgesia and nociception. On the other hand, intraplantar injection of sialidase, which cleaves sialyl residues from glycoconjugates such as gangliosides, attenuated the late phase of 2% formalin-induced nociception. Thus, the antinociceptive effects of sialidase and the nociceptive effects of GT1b indicated that endogenous gangliosides are involved in nociceptive responses. These results suggest that gangliosides play important roles in nociceptive responses originating in peripheral nociceptor endings. Ganglioside GT1b induced extracellular glutamate to accumulate in subdermal tissues, thereafter activating glutamate receptors, which in turn resulted in

  12. Histochemical studies of the effects of monosodium glutamate on the liver of adult wistar rats.

    Science.gov (United States)

    Eweka, Ao; Igbigbi, Ps; Ucheya, Re

    2011-01-01

    Monosodium glutamate (MSG) is a commonly used food additive and there is growing concern that excitotoxins such as MSG play a critical role in the development of several hepatic disorders. The histochemical effect of monosodium glutamate was investigated on the liver of adult Wistar rats. Adult male Wistar rats (n = 24), with an average weight of 230 g were randomly assigned into two treatment groups, (A & B) (n=16) and Control (C) (n=8). The rats in the treatment groups (A & B) received 0.04mg/kg and 0.08mg/kg of monosodium glutamate thoroughly mixed with the grower's mash, respectively on a daily basis for forty-two days. The 0.04mg/kg and 0.08mg/kg monosodium glutamate doses were chosen and extrapolated in this experiment based on the previous work done with the additive. The control group (C) received equal amount of feed (Growers' mash) without monosodium glutamate added for the same period. The rats were given water ad libitum. Both the treatment and control rats were sacrificed by cervical dislocation on day forty-three of the experiment. The Liver was carefully dissected out and quickly fixed in Bouin's fluid for histochemical studies, while blood was collected for estimation of total protein, albumin, transaminasese (aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The histological findings showed changes like dilatation of the central vein, which contained lysed red blood cells, cyto-architectural distortions of the hepatocytes, atrophic and degenerative changes on the liver of the animals that received feed incoporated with monosodium glutamate. Furthermore, the biochemical parameters were significantly higher in the test than control groups (P monosodium glutamate mixed in their feed. These findings showed that monosodium glutamate consumption may have some deleterious effects on the liver of adult Wistar rats at higher doses and by extension may affect the functions of the liver.

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

    Science.gov (United States)

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

    2016-02-01

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

  14. Enhanced glutamic acid production by a H+-ATPase-defective mutant of Corynebacterium glutamicum.

    Science.gov (United States)

    Aoki, Ryo; Wada, Masaru; Takesue, Nobuchika; Tanaka, Kenji; Yokota, Atsushi

    2005-08-01

    Previously we reported that a mutant of Corynebacterium glutamicum ATCC14067 with reduced H+-ATPase activity, F172-8, showed an approximately two times higher specific rate of glucose consumption than the parent, but no glutamic acid productivity under the standard biotin-limited culture conditions, where biotin concentration was set at 5.5 microg/l in the production medium (Sekine et al., Appl. Microbiol. Biotechnol., 57, 534-540 (2001)). In this study, various culture conditions were tested to check the glutamic acid productivity of strain F172-8. The mutant was found to produce glutamic acid under exhaustive biotin limitation, where the biotin concentration of the medium was set at 2.5 microg/l with much smaller inoculum size. When strain F172-8 was cultured under the same biotin-limited conditions using a jar fermentor, 53.7 g/l of glutamic acid was produced from 100 g/l glucose, while the parent produced 34.9 g/l of glutamic acid in a medium with 5.5 microg/l biotin. The glutamic acid yield of strain F172-8 also increased under Tween 40-triggered production conditions (1.2-fold higher than the parent strain). The amounts of biotin-binding enzymes were investigated by Western blot analysis. As compared to the parent, the amount of pyruvate carboxylase was lower in the mutant; however, the amount of acetyl-CoA carboxylase did not significantly change under the glutamic acid production conditions. To the best of our knowledge, this is the first report showing that the H+-ATPase-defective mutant of C. glutamicum is useful in glutamic acid production.

  15. Baseline dietary glutamic acid intake and the risk of colorectal cancer: The Rotterdam study.

    Science.gov (United States)

    Viana Veloso, Gilson G; Franco, Oscar H; Ruiter, Rikje; de Keyser, Catherina E; Hofman, Albert; Stricker, Bruno C; Kiefte-de Jong, Jessica C

    2016-03-15

    Animal studies have shown that glutamine supplementation may decrease colon carcinogenesis, but any relation with glutamine or its precursors has not been studied in humans. The primary aim of this study was to assess whether dietary glutamic acid intake was associated with colorectal cancer (CRC) risk in community-dwelling adults. A secondary aim was to evaluate whether the association could be modified by the body mass index (BMI). This study was embedded in the Rotterdam study, which included a prospective cohort from 1990 onward that consisted of 5362 subjects who were 55 years old or older and were free of CRC at the baseline. Glutamic acid was calculated as a percentage of the total protein intake with a validated food frequency questionnaire at the baseline. Incident cases of CRC were pathology-based. During follow-up, 242 subjects developed CRC. Baseline dietary glutamic acid intake was significantly associated with a lower risk of developing CRC (hazard ratio [HR] per percent increase in glutamic acid of protein, 0.78; 95% confidence interval [CI], 0.62-0.99). After stratification for BMI, the risk reduction for CRC by dietary glutamic acid was 42% for participants with a BMI ≤ 25 kg/m(2) (HR per percent increase in glutamic acid of protein, 0.58; 95% CI, 0.40-0.85), whereas no association was found in participants with a BMI > 25 kg/m(2) (HR per percent increase in glutamic acid of protein, 0.97; 95% CI, 0.73-1.31). Our data suggest that baseline dietary glutamic acid intake is associated with a lower risk of developing CRC, but this association may be mainly present in nonoverweight subjects. © 2015 American Cancer Society.

  16. Study on roles of anaplerotic pathways in glutamate overproduction of Corynebacterium glutamicum by metabolic flux analysis

    Directory of Open Access Journals (Sweden)

    Shioya Suteaki

    2007-06-01

    Full Text Available Abstract Background Corynebacterium glutamicum has several anaplerotic pathways (anaplerosis, which are essential for the productions of amino acids, such as lysine and glutamate. It is still not clear how flux changes in anaplerotic pathways happen when glutamate production is induced by triggers, such as biotin depletion and the addition of the detergent material, Tween 40. In this study, we quantitatively analyzed which anaplerotic pathway flux most markedly changes the glutamate overproduction induced by Tween 40 addition. Results We performed a metabolic flux analysis (MFA with [1-13C]- and [U-13C]-labeled glucose in the glutamate production phase of C. glutamicum, based on the analysis of the time courses of 13C incorporation into proteinogenic amino acids by gas chromatography-mass spectrometry (GC-MS. The flux from phosphoenolpyruvate (PEP to oxaloacetate (Oxa catalyzed by phosphoenolpyruvate carboxylase (PEPc was active in the growth phase not producing glutamate, whereas that from pyruvate to Oxa catalyzed by pyruvate carboxylase (Pc was inactive. In the glutamate overproduction phase induced by the addition of the detergent material Tween 40, the reaction catalyzed by Pc also became active in addition to the reaction catalyzed by PEPc. Conclusion It was clarified by a quantitative 13C MFA that the reaction catalyzed by Pc is most markedly increased, whereas other fluxes of PEPc and PEPck remain constant in the glutamate overproduction induced by Tween 40. This result is consistent with the previous results obtained in a comparative study on the glutamate productions of genetically recombinant Pc- and PEPc-overexpressing strains. The importance of a specific reaction in an anaplerotic pathway was elucidated at a metabolic level by MFA.

  17. Synaptopathy under conditions of altered gravity: changes in synaptic vesicle fusion and glutamate release.

    Science.gov (United States)

    Krisanova, N V; Trikash, I O; Borisova, T A

    2009-12-01

    Glutamate release and synaptic vesicle heterotypic/homotypic fusion were characterized in brain synaptosomes of rats exposed to hypergravity (10 G, 1h). Stimulated vesicular exocytosis determined as KCl-evoked fluorescence spike of pH-sensitive dye acridine orange (AO) was decreased twice in synaptosomes under hypergravity conditions as compared to control. Sets of measurements demonstrated reduced ability of synaptic vesicles to accumulate AO ( approximately 10% higher steady-state baseline level of AO fluorescence). Experiments with preloaded l-[(14)C]glutamate exhibited similar amount of total glutamate accumulated by synaptosomes, equal concentration of ambient glutamate, but the enlarged level of cytoplasmic glutamate measuring as leakage from digitonin-permeabilized synaptosomes in hypergravity. Thus, it may be suggested that +G-induced changes in stimulated vesicular exocytosis were a result of the redistribution of intracellular pool of glutamate, i.e. a decrease in glutamate content of synaptic vesicles and an enrichment of the cytoplasmic glutamate level. To investigate the effect of hypergravity on the last step of exocytosis, i.e. membrane fusion, a cell-free system consisted of synaptic vesicles, plasma membrane vesicles, cytosolic proteins isolated from rat brain synaptosomes was used. It was found that hypergravity reduced the fusion competence of synaptic vesicles and plasma membrane vesicles, whereas synaptosomal cytosolic proteins became more active to promote membrane fusion. The total rate of homo- and heterotypic fusion reaction initiated by Ca(2+) or Mg(2+)/ATP remained unchanged under hypergravity conditions. Thus, hypergravity could induce synaptopathy that was associated with incomplete filling of synaptic vesicles with the neuromediator and changes in exocytotic release.

  18. Hexane extract from Polygonum multiflorum attenuates glutamate-induced apoptosis in primary cultured cortical neurons.

    Science.gov (United States)

    Jang, Ji Yeon; Kim, Ha Neui; Kim, Yu Ri; Choi, Young Whan; Choi, Yung Hyun; Lee, Jun Hyuk; Shin, Hwa Kyoung; Choi, Byung Tae

    2013-01-09

    Polygonum multiflorum has traditionally had wide use as an anti-aging treatment in East Asian countries. We investigated the neuroprotective effects of Polygonum multiflorum against glutamate-induced neurotoxicity with a focus on the anti-apoptotic mechanism in primary cultured cortical neurons. Cell viability, cytotoxicity, morphological, flow cytometry, Western blot, and caspase activity assays were performed for examination of the neuroprotective effects of active hexane extract from Polygonum multiflorum (HEPM). Pretreatment with HEPM resulted in significantly decreased glutamate-induced neurotoxicity in a concentration-dependent manner and also resulted in drastically inhibited glutamate-induced apoptosis. Treatment with HEPM resulted in decreased expression of glutamate-induced death receptor (DR)4, and enhanced expression of glutamate-attenuated anti-apoptotic proteins, including Bcl-2, XIAP, and cIAP-1, and slightly reduced glutamate-induced cleavage of Bid. In addition, treatment with HEPM resulted in suppressed glutamate-induced activation of caspase-8, caspase-9, and caspase-3, and, subsequently, decreased degradation of poly(ADP-ribose) polymerase, β-catenin, and phospholipase Cγ1 protein, which are downstream targets of activated caspase-3. The results of this study demonstrated that HEPM exerts a neuroprotective effect against glutamate-induced neurotoxicity via inhibition of apoptosis. This protection may be mediated through suppression of DR4 and up-regulation of Bcl-2, XIAP, and cIAP-1, as well as inhibition of caspase activation, resulting in prevention of apoptosis of cortical neurons. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  19. 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.

  20. The role of glutamate in neuronal ion homeostasis: A case study of spreading depolarization.

    Directory of Open Access Journals (Sweden)

    Niklas Hübel

    2017-10-01

    Full Text Available Simultaneous changes in ion concentrations, glutamate, and cell volume together with exchange of matter between cell network and vasculature are ubiquitous in numerous brain pathologies. A complete understanding of pathological conditions as well as normal brain function, therefore, hinges on elucidating the molecular and cellular pathways involved in these mostly interdependent variations. In this paper, we develop the first computational framework that combines the Hodgkin-Huxley type spiking dynamics, dynamic ion concentrations and glutamate homeostasis, neuronal and astroglial volume changes, and ion exchange with vasculature into a comprehensive model to elucidate the role of glutamate uptake in the dynamics of spreading depolarization (SD-the electrophysiological event underlying numerous pathologies including migraine, ischemic stroke, aneurysmal subarachnoid hemorrhage, intracerebral hematoma, and trauma. We are particularly interested in investigating the role of glutamate in the duration and termination of SD caused by K+ perfusion and oxygen-glucose deprivation. Our results demonstrate that glutamate signaling plays a key role in the dynamics of SD, and that impaired glutamate uptake leads to recovery failure of neurons from SD. We confirm predictions from our model experimentally by showing that inhibiting astrocytic glutamate uptake using TFB-TBOA nearly quadruples the duration of SD in layers 2-3 of visual cortical slices from juvenile rats. The model equations are either derived purely from first physical principles of electroneutrality, osmosis, and conservation of particles or a combination of these principles and known physiological facts. Accordingly, we claim that our approach can be used as a future guide to investigate the role of glutamate, ion concentrations, and dynamics cell volume in other brain pathologies and normal brain function.

  1. Synthetic cathinone MDPV downregulates glutamate transporter subtype I (GLT-1) and produces rewarding and locomotor-activating effects that are reduced by a GLT-1 activator

    OpenAIRE

    Gregg, Ryan A.; Hicks, Callum; Nayak, Sunil U.; Tallarida, Christopher S.; Nucero, Paul; Reitz, Allen B.; Smith, Garry R.; Rawls, Scott M.

    2016-01-01

    Synthetic cathinones produce dysregulation of monoamine systems, but their effects on the glutamate system and the influence of glutamate on behavioral effects related to cathinone abuse are unknown. A principal regulator of glutamate homeostasis is glutamate transporter subtype 1 (GLT-1), an astrocytic protein that clears glutamate from the extracellular space and influences behavioral effects of established psychostimulants. We hypothesized that repeated administration of the synthetic cath...

  2. Thrombin decreases expression of the glutamate transporter GLAST and inhibits glutamate uptake in primary cortical astrocytes via the Rho kinase pathway.

    Science.gov (United States)

    Piao, Chunshu; Ralay Ranaivo, Hantamalala; Rusie, Allison; Wadhwani, Nitin; Koh, Sookyong; Wainwright, Mark S

    2015-11-01

    Astrocyte glutamate transporters GLAST and GLT1 play a key role in regulating neuronal excitation and their levels are altered in patients with epilepsy, and after traumatic brain injury. The mechanisms which regulate their expression are not well understood. We tested the hypothesis that exposure of astrocytes to high levels of thrombin, as may occur after a compromise of the blood-brain barrier, would reduce astrocyte glutamate transporter levels. In isolated rat cortical astrocytes we examined the effects of thrombin on the expression and function of glutamate transporters, and the signaling pathways involved in these responses by using Western blotting and selective inhibitors. Thrombin induced a selective decrease in the expression of GLAST but not GLT1, with a corresponding decrease in the capacity of astrocytes to take up glutamate. Activation of the thrombin receptor PAR-1 with an activating peptide induced a similar decrease in the expression of GLAST and compromise of glutamate uptake. The downregulation of GLAST induced by thrombin was mediated by the mitogen activated protein kinases p38 MAPK, ERK and JNK, but inhibition of these kinases did not prevent the decrease in glutamate uptake induced by thrombin. In contrast, inhibition of the Rho kinase pathway using the specific inhibitor, Y27632, suppressed both the decrease in the expression of GLAST and the decrease in glutamate uptake induced by thrombin. In hippocampal astrocyte cultures, thrombin caused a decrease in both GLAST and GLT1. In tissue resected from brains of children with intractable epilepsy, we found a decrease in the integrity of the blood-brain barrier along with a reduction in immunoreactivity for both transporters which was associated with an increase in cleaved thrombin and reactive astrogliosis. The in vitro results suggest a specific mechanism by which thrombin may lead to a compromise of astrocyte function and enhanced synaptic excitability after the blood-brain barrier is

  3. 4,4-Dimethyl- and diastereomeric 4-hydroxy-4-methyl-(2S)-glutamate analogues display distinct pharmacological profiles at ionotropic glutamate receptors and excitatory amino acid transporters

    DEFF Research Database (Denmark)

    Bunch, Lennart; Pickering, Darryl S; Gefflaut, Thierry

    2009-01-01

    this approach has provided important insight into the structure-activity relationships (SAR) for ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs), as well as the excitatory amino acid transporters (EAATs). In this work, three 4,4-disubstituted Glu analogues 1-3, which are hybrid structures......Subtype-selective ligands are of great interest to the scientific community, as they provide a tool for investigating the function of one receptor or transporter subtype when functioning in its native environment. Several 4-substituted (S)-glutamate (Glu) analogues were synthesized, and altogether...

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

    Science.gov (United States)

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

    2012-08-01

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

  5. Impact of glutamate levels on neuronal response and cognitive abilities in schizophrenia

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    Liv E. Falkenberg

    2014-01-01

    Full Text Available Schizophrenia is characterized by impaired cognitive functioning, and brain regions involved in cognitive control processes show marked glutamatergic abnormalities. However, it is presently unclear whether aberrant neuronal response is directly related to the observed deficits at the metabolite level in schizophrenia. Here, 17 medicated schizophrenia patients and 17 matched healthy participants underwent functional magnetic resonance imaging (fMRI when performing an auditory cognitive control task, as well as proton magnetic resonance spectroscopy (1H-MRS in order to assess resting-state glutamate in the anterior cingulate cortex. The combined fMRI–1H-MRS analysis revealed that glutamate differentially predicted cortical blood-oxygen level-dependent (BOLD response in patients and controls. While we found a positive correlation between glutamate and BOLD response bilaterally in the inferior parietal lobes in the patients, the corresponding correlation was negative in the healthy control participants. Further, glutamate levels predicted task performance in patients, such that lower glutamate levels were related to impaired cognitive control functioning. This was not seen for the healthy controls. These findings suggest that schizophrenia patients have a glutamate-related dysregulation of the brain network supporting cognitive control functioning. This could be targeted in future research on glutamatergic treatment of cognitive symptoms in schizophrenia.

  6. G-protein coupled receptor-evoked glutamate exocytosis from astrocytes: role of prostaglandins.

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    Cali, Corrado; Lopatar, Jan; Petrelli, Francesco; Pucci, Luca; Bezzi, Paola

    2014-01-01

    Astrocytes are highly secretory cells, participating in rapid brain communication by releasing glutamate. Recent evidences have suggested that this process is largely mediated by Ca(2+)-dependent regulated exocytosis of VGLUT-positive vesicles. Here by taking advantage of VGLUT1-pHluorin and TIRF illumination, we characterized mechanisms of glutamate exocytosis evoked by endogenous transmitters (glutamate and ATP), which are known to stimulate Ca(2+) elevations in astrocytes. At first we characterized the VGLUT1-pHluorin expressing vesicles and found that VGLUT1-positive vesicles were a specific population of small synaptic-like microvesicles containing glutamate but which do not express VGLUT2. Endogenous mediators evoked a burst of exocytosis through activation of G-protein coupled receptors. Subsequent glutamate exocytosis was reduced by about 80% upon pharmacological blockade of the prostaglandin-forming enzyme, cyclooxygenase. On the other hand, receptor stimulation was accompanied by extracellular release of prostaglandin E2 (PGE2). Interestingly, administration of exogenous PGE2 produced per se rapid, store-dependent burst exocytosis of glutamatergic vesicles in astrocytes. Finally, when PGE2-neutralizing antibody was added to cell medium, transmitter-evoked exocytosis was again significantly reduced (by about 50%). Overall these data indicate that cyclooxygenase products are responsible for a major component of glutamate exocytosis in astrocytes and that large part of such component is sustained by autocrine/paracrine action of PGE2.

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

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    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.

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

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

    2016-02-04

    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. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Auditory hindbrain atrophy and anomalous calcium binding protein expression after neonatal exposure to monosodium glutamate.

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    Foran, Lindsey; Blackburn, Kaitlyn; Kulesza, Randy J

    2017-03-06

    Glutamate is the most abundant excitatory neurotransmitter in the central nervous system, and is stored and released by both neurons and astrocytes. Despite the important role of glutamate as a neurotransmitter, elevated extracellular glutamate can result in excitotoxicity and apoptosis. Monosodium glutamate (MSG) is a naturally occurring sodium salt of glutamic acid that is used as a flavor enhancer in many processed foods. Previous studies have shown that MSG administration during the early postnatal period results in neurodegenerative changes in several forebrain regions, characterized by neuronal loss and neuroendocrine abnormalities. Systemic delivery of MSG during the neonatal period and induction of glutamate neurotoxicity in the cochlea have both been shown to result in fewer neurons in the spiral ganglion. We hypothesized that an MSG-induced loss of neurons in the spiral ganglion would have a significant impact on the number of neurons in the cochlear nuclei and superior olivary complex (SOC). Indeed, we found that exposure to MSG from postnatal days 4 through 10 resulted in significantly fewer neurons in the cochlear nuclei and SOC and significant dysmorphology in surviving neurons. Moreover, we found that neonatal MSG exposure resulted in a significant decrease in the expression of both calretinin and calbindin. These results suggest that neonatal exposure to MSG interferes with early development of the auditory brainstem and impacts expression of calcium binding proteins, both of which may lead to diminished auditory function. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Conformational analysis of glutamic acid: a density functional approach using implicit continuum solvent model.

    Science.gov (United States)

    Turan, Başak; Selçuki, Cenk

    2014-09-01

    Amino acids are constituents of proteins and enzymes which take part almost in all metabolic reactions. Glutamic acid, with an ability to form a negatively charged side chain, plays a major role in intra and intermolecular interactions of proteins, peptides, and enzymes. An exhaustive conformational analysis has been performed for all eight possible forms at B3LYP/cc-pVTZ level. All possible neutral, zwitterionic, protonated, and deprotonated forms of glutamic acid structures have been investigated in solution by using polarizable continuum model mimicking water as the solvent. Nine families based on the dihedral angles have been classified for eight glutamic acid forms. The electrostatic effects included in the solvent model usually stabilize the charged forms more. However, the stability of the zwitterionic form has been underestimated due to the lack of hydrogen bonding between the solute and solvent; therefore, it is observed that compact neutral glutamic acid structures are more stable in solution than they are in vacuum. Our calculations have shown that among all eight possible forms, some are not stable in solution and are immediately converted to other more stable forms. Comparison of isoelectronic glutamic acid forms indicated that one of the structures among possible zwitterionic and anionic forms may dominate over the other possible forms. Additional investigations using explicit solvent models are necessary to determine the stability of charged forms of glutamic acid in solution as our results clearly indicate that hydrogen bonding and its type have a major role in the structure and energy of conformers.

  11. Attenuated AMPA receptor expression allows glioblastoma cell survival in glutamate-rich environment.

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    Dannis G van Vuurden

    Full Text Available BACKGROUND: Glioblastoma multiforme (GBM cells secrete large amounts of glutamate that can trigger AMPA-type glutamate receptors (AMPARs. This commonly results in Na(+ and Ca(2+-permeability and thereby in excitotoxic cell death of the surrounding neurons. Here we investigated how the GBM cells themselves survive in a glutamate-rich environment. METHODS AND FINDINGS: In silico analysis of published reports shows down-regulation of all ionotropic glutamate receptors in GBM as compared to normal brain. In vitro, in all GBM samples tested, mRNA expression of AMPAR subunit GluR1, 2 and 4 was relatively low compared to adult and fetal total brain mRNA and adult cerebellum mRNA. These findings were in line with primary GBM samples, in which protein expression patterns were down-regulated as compared to the normal tissue. Furthermore, mislocalized expression of these receptors was found. Sequence analysis of GluR2 RNA in primary and established GBM cell lines showed that the GluR2 subunit was found to be partly unedited. CONCLUSIONS: Together with the lack of functional effect of AMPAR inhibition by NBQX our results suggest that down-regulation and afunctionality of AMPARs, enable GBM cells to survive in a high glutamate environment without going into excitotoxic cell death themselves. It can be speculated that specific AMPA receptor inhibitors may protect normal neurons against the high glutamate microenvironment of GBM tumors.

  12. NADP-glutamate dehydrogenase isoenzymes of Saccharomyces cerevisiae. Purification, kinetic properties, and physiological roles.

    Science.gov (United States)

    DeLuna, A; Avendano, A; Riego, L; Gonzalez, A

    2001-11-23

    In the yeast Saccharomyces cerevisiae, two NADP(+)-dependent glutamate dehydrogenases (NADP-GDHs) encoded by GDH1 and GDH3 catalyze the synthesis of glutamate from ammonium and alpha-ketoglutarate. The GDH2-encoded NAD(+)-dependent glutamate dehydrogenase degrades glutamate producing ammonium and alpha-ketoglutarate. Until very recently, it was considered that only one biosynthetic NADP-GDH was present in S. cerevisiae. This fact hindered understanding the physiological role of each isoenzyme and the mechanisms involved in alpha-ketoglutarate channeling for glutamate biosynthesis. In this study, we purified and characterized the GDH1- and GDH3-encoded NADP-GDHs; they showed different allosteric properties and rates of alpha-ketoglutarate utilization. Analysis of the relative levels of these proteins revealed that the expression of GDH1 and GDH3 is differentially regulated and depends on the nature of the carbon source. Moreover, the physiological study of mutants lacking or overexpressing GDH1 or GDH3 suggested that these genes play nonredundant physiological roles. Our results indicate that the coordinated regulation of GDH1-, GDH3-, and GDH2-encoded enzymes results in glutamate biosynthesis and balanced utilization of alpha-ketoglutarate under fermentative and respiratory conditions. The possible relevance of the duplicated NADP-GDH pathway in the adaptation to facultative metabolism is discussed.

  13. L-Glutamate production by lysozyme-sensitive Corynebacterium glutamicum ltsA mutant strains

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    Nagai Kazuo

    2001-10-01

    Full Text Available Abstract Background A non-pathogenic species of coryneform bacteria, Corynebacterium glutamicum, was originally isolated as an L-glutamate producing bacterium and is now used for fermentative production of various amino acids. A mutation in the C. glutamicum ltsA gene caused susceptibility to lysozyme, temperature-sensitive growth, and L-glutamate production. Results The characteristics of eight lysozyme-sensitive mutants which had been isolated after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis were examined. Complementation analysis with the cloned wild-type ltsA gene and DNA sequencing of the ItsA region revealed that four mutants had a mutation in the ltsA gene. Among them, two mutants showed temperature-sensitive growth and overproduced L-glutamate at higher temperatures, as well as the previously reported ltsA mutant. Other two showed temperature-resistant growth: one missense mutant produced L-glutamate to some extent but the other nonsense mutant did not. These two mutants remained temperature-resistant in spite of introduction of ltsA::kan mutation that causes temperature-sensitive growth in the wild-type background. Conclusions These results indicate that a defect caused by the ltsA mutations is responsible for temperature-sensitive growth and L-glutamate overproduction by C. glutamicum. The two temperature-resistant mutants seem to carry suppressor mutations that rendered cells temperature-resistance and abolished L-glutamate overproduction.

  14. Gender associations with cerebrospinal fluid glutamate and lactate/pyruvate levels after severe traumatic brain injury.

    Science.gov (United States)

    Wagner, Amy K; Fabio, Anthony; Puccio, Ava M; Hirschberg, Ronald; Li, Wei; Zafonte, Ross D; Marion, Donald W

    2005-02-01

    Female sex hormones appear to be neuroprotective after traumatic brain injury by attenuating multiple mechanisms of secondary insult, including excitotoxicity and ischemia. The purpose of this study was to evaluate associations between gender and cerebrospinal fluid glutamate and lactate/pyruvate production and the role of hypothermia with gender in attenuating these markers. Prospectively collected data were analyzed for adult patients with severe traumatic brain injury. Gender comparisons for cerebrospinal fluid glutamate and lactate/pyruvate production were determined using ventricular samples obtained over the first 48 hrs postinjury. University-based level I trauma center. There were 123 patients, male n = 93 and female n = 30 (n = 686 cerebrospinal fluid samples), with severe traumatic brain injury (Glasgow Coma Scale score fluid glutamate production for males compared with females (p = .0023) and a significant interaction between glutamate concentration, gender, and time (p = .0035) by 24 hrs postinjury. Females had lower lactate/pyruvate ratios than males (p = .0006), and there was a significant interaction between lactate/pyruvate, gender, and time (p = .0045) throughout the first 48 hrs postinjury. Hypothermia attenuated glutamate levels, particularly for males, over the time course studied. These data suggest significant gender differences with glutamate and lactate/pyruvate production after severe traumatic brain injury. Gender- and hormone-mediated differences in central nervous system pathophysiology should be considered with clinical trials in traumatic brain injury.

  15. G-Protein Coupled Receptor-Evoked Glutamate Exocytosis from Astrocytes: Role of Prostaglandins

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    Corrado Cali

    2014-01-01

    Full Text Available Astrocytes are highly secretory cells, participating in rapid brain communication by releasing glutamate. Recent evidences have suggested that this process is largely mediated by Ca2+-dependent regulated exocytosis of VGLUT-positive vesicles. Here by taking advantage of VGLUT1-pHluorin and TIRF illumination, we characterized mechanisms of glutamate exocytosis evoked by endogenous transmitters (glutamate and ATP, which are known to stimulate Ca2+ elevations in astrocytes. At first we characterized the VGLUT1-pHluorin expressing vesicles and found that VGLUT1-positive vesicles were a specific population of small synaptic-like microvesicles containing glutamate but which do not express VGLUT2. Endogenous mediators evoked a burst of exocytosis through activation of G-protein coupled receptors. Subsequent glutamate exocytosis was reduced by about 80% upon pharmacological blockade of the prostaglandin-forming enzyme, cyclooxygenase. On the other hand, receptor stimulation was accompanied by extracellular release of prostaglandin E2 (PGE2. Interestingly, administration of exogenous PGE2 produced per se rapid, store-dependent burst exocytosis of glutamatergic vesicles in astrocytes. Finally, when PGE2-neutralizing antibody was added to cell medium, transmitter-evoked exocytosis was again significantly reduced (by about 50%. Overall these data indicate that cyclooxygenase products are responsible for a major component of glutamate exocytosis in astrocytes and that large part of such component is sustained by autocrine/paracrine action of PGE2.

  16. Synaptic vesicles are capable of synthesizing the VGLUT substrate glutamate from α-ketoglutarate for vesicular loading.

    Science.gov (United States)

    Takeda, Kouji; Ishida, Atsuhiko; Takahashi, Kento; Ueda, Tetsufumi

    2012-04-01

    Synaptic vesicle loading of glutamate is a pivotal step in glutamate synaptic transmission. The molecular machinery responsible for this step is comprised of v-type proton-pump ATPase and a vesicular glutamate transporter. Recent evidence indicates that synaptic vesicles are endowed with glycolytic ATP-synthesizing enzymes, providing energy for immediate use by vesicle-bound proton-pump ATPase. In this study, we provide evidence that synaptic vesicles are also capable of synthesizing the vesicular glutamate transporter substrate glutamate, from α-ketoglutarate and l-aspartate (as the amino group donor); glutamate thus produced is taken up into vesicles. We also report a finding that α-ketoglutarate-derived glutamate uptake into synaptic vesicles and aspartate aminotransferase are inhibited by 2,3-pyrazinedicarboxylate. Evidence is given that this is a selective inhibitor for aspartate aminotransferase. These observations provide insight into understanding the nerve endings' mechanism for high efficiency in glutamate transmission. Finding this inhibitor may have implications for further experimentation on the role of α-ketoglutarate-derived glutamate in glutamate transmission. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

  17. Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

    Science.gov (United States)

    Shen, Yao; Tian, Yueyang; Shi, Xiaojie; Yang, Jianbo; Ouyang, Li; Gao, Jieqiong; Lu, Jianxin

    2014-08-01

    Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd.

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

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    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.

  19. Musicogenic reflex seizures in epilepsy with glutamic acid decarbocylase antibodies.

    Science.gov (United States)

    Falip, M; Rodriguez-Bel, L; Castañer, S; Miro, J; Jaraba, S; Mora, J; Bas, J; Carreño, M

    2017-08-02

    Musicogenic reflex seizures (MRS) are a rare form of seizures described in patients with temporal lobe epilepsy (TLE), mainly of unknown etiology. Epilepsy with antibodies against glutamic acid decarboxylase (GAD-ab) is a form of autoimmune epilepsy for which no specific semiology has been described. To retrospectively review the incidence of MRS in the general epileptic population and in the series of patients with epilepsy and GAD-ab and to describe its clinical and paraclinical characteristics. Patients recorded between January 2010 and January 2016 in the Database of Bellvitge Hospital Epilepsy Unit were reviewed. From a group of 1510 epileptic patients, three reported MRS (0.0019%) (two patients with epilepsy and GAD-ab and one patient with cryptogenic TLE). The incidence of MRS in patients with epilepsy and GAD-ab was 2 of 22 (9%). Both patients had a normal magnetic resonance Imaging (MRI), but FDG-PET showed medial temporal lobe hypometabolism (unilateral or bilateral) in both and also in the insula in one of them. MRS (recorded via video-EEG[electroencephalography] in one patient) arose from the right temporal lobe. MRS may be a distinctive seizure type in patients with epilepsy and antiGADab. Determination of GAD-ab should be carried out in all cases of MRS, even those with normal structural MRI. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Novel Functional Properties of Drosophila CNS Glutamate Receptors

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    Li, Yan; Dharkar, Poorva; Han, Tae-Hee; Serpe, Mihaela; Lee, Chi-Hon; Mayer, Mark L.

    2016-12-01

    Phylogenetic analysis reveals AMPA, kainate, and NMDA receptor families in insect genomes, suggesting conserved functional properties corresponding to their vertebrate counterparts. However, heterologous expression of the Drosophila kainate receptor DKaiR1D and the AMPA receptor DGluR1A revealed novel ligand selectivity at odds with the classification used for vertebrate glutamate receptor ion channels (iGluRs). DKaiR1D forms a rapidly activating and desensitizing receptor that is inhibited by both NMDA and the NMDA receptor antagonist AP5; crystallization of the KaiR1D ligand-binding domain reveals that these ligands stabilize open cleft conformations, explaining their action as antagonists. Surprisingly, the AMPA receptor DGluR1A shows weak activation by its namesake agonist AMPA and also by quisqualate. Crystallization of the DGluR1A ligand-binding domain reveals amino acid exchanges that interfere with binding of these ligands. The unexpected ligand-binding profiles of insect iGluRs allows classical tools to be used in novel approaches for the study of synaptic regulation.

  1. Reconsidering the effects of monosodium glutamate: a literature review.

    Science.gov (United States)

    Freeman, Matthew

    2006-10-01

    This article reviews the literature from the past 40 years of research related to monosodium glutamate (MSG) and its ability to trigger a migraine headache, induce an asthma exacerbation, or evoke a constellation of symptoms described as the "Chinese restaurant syndrome." Literature retrieved by a search using PubMed, Medline, Lexis-Nexus, and Infotrac to review articles from the past 40 years. MSG has a widespread reputation for eliciting a variety of symptoms, ranging from headache to dry mouth to flushing. Since the first report of the so-called Chinese restaurant syndrome 40 years ago, clinical trials have failed to identify a consistent relationship between the consumption of MSG and the constellation of symptoms that comprise the syndrome. Furthermore, MSG has been described as a trigger for asthma and migraine headache exacerbations, but there are no consistent data to support this relationship. Although there have been reports of an MSG-sensitive subset of the population, this has not been demonstrated in placebo-controlled trials. Despite a widespread belief that MSG can elicit a headache, among other symptoms, there are no consistent clinical data to support this claim. Findings from the literature indicate that there is no consistent evidence to suggest that individuals may be uniquely sensitive to MSG. Nurse practitioners should therefore concentrate their efforts on advising patients of the nutritional pitfalls of some Chinese restaurant meals and to seek more consistently documented etiologies for symptoms such as headache, xerostomia, or flushing.

  2. 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

    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. 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. 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.

  3. Flavor preferences conditioned by intragastric monosodium glutamate in mice.

    Science.gov (United States)

    Ackroff, Karen; Sclafani, Anthony

    2013-11-01

    The consumption of monosodium glutamate (MSG) solutions has been shown to reinforce preferences for MSG and for MSG-paired flavors in mice. These effects appear to have a strong postoral component, such that MSG detected in the gut is associated with concurrently consumed flavors. Two experiments investigated postoral MSG reward by infusing 400mM MSG intragastrically (IG) to C57BL/6 mice as they consumed a conditioned stimulus (CS+) flavor. An alternate CS- flavor was paired with IG water. In Experiment 1, the grape and cherry CS flavors were unsweetened, and intakes and preferences for the CS+ flavor were modest. Experiment 2 attempted to generate stronger preferences by adding 0.05% saccharin to the CS flavors. Sweet taste did enhance intakes during training and testing but did not significantly increase percent CS+ intake or persistence of the preference. However, only conditioning with the sweet CS+ resulted in the mice expressing a preference for oral MSG in an initial choice test with water. These findings extend recent studies demonstrating postoral MSG conditioning in rats.

  4. Glutamate and GABA as rapid effectors of hypothalamic peptidergic neurons

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    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.

  5. Monosodium glutamate intake, dietary patterns and asthma in Chinese adults.

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    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.

  6. Glutamate and α-ketoglutarate: key players in glioma metabolism.

    Science.gov (United States)

    Maus, Andreas; Peters, Godefridus J

    2017-01-01

    Glioblastoma multiforme (GBM), or grade IV astrocytoma, is the most common type of primary brain tumor. It has a devastating prognosis with a 2-year-overall survival rate of only 26 % after standard treatment, which includes surgery, radiation, and adjuvant chemotherapy with temozolomide. Also lower grade gliomas are difficult to treat, because they diffusely spread into the brain, where extensive removal of tissue is critical. Better understanding of the cancer's biology is a key for the development of more effective therapy approaches. The discovery of isocitrate dehydrogenase (IDH) mutations in leukemia and glioma drew attention to specific metabolic aberrations in IDH-mutant gliomas. In the center of the metabolic alterations is α-ketoglutarate (αKG), an intermediate metabolite in the tricarboxylic acid (TCA) cycle, and the associated amino acid glutamate (Glu). This article highlights the role of these metabolites in glioma energy and lipid production and indicates possible weak spots of IDH-mutant and IDH-wt gliomas.

  7. The good and bad news about glutamate in drug addiction.

    Science.gov (United States)

    Spencer, Sade; Scofield, Michael; Kalivas, Peter W

    2016-11-01

    In 1998 we published a perspective review describing how drug-induced neuroadaptations might serve towards understanding drug craving. We proposed experimental perspectives to help discern data relevant to long-lasting brain changes, and to distinguish dopamine-related changes that were largely pharmacological from glutamatergic changes that were based on drug-environment associations. These perspectives are embedded in drug abuse research, and the last 18 years has witnessed marked development in understanding addiction-associated corticostriatal glutamate plasticity. Here we propose three new perspectives on how the field might approach integrating and using the emerging data on glutamatergic adaptations. (1) Consider adaptations produced in kind across drug classes as most useful towards understanding shared characteristics of addiction, such as relapse. (2) Consider how drug-induced changes in glia and the extracellular matrix may contribute to synaptic alterations. (3) Make measurements not only at late withdrawal, but also during drug seeking events to capture transient changes that mediate active drug seeking that are shared across drug classes. © The Author(s) 2016.

  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. Differing effects of transport inhibitor on glutamate uptake by nerve terminals before and after exposure of rats to artificial gravity.

    Science.gov (United States)

    Borisova, T.; Krisanova, N.; Himmelreich, N.

    Glutamate is the major excitatory neurotransmitter in the brain. Subsequent to its release from glutamatergic neurons and activation of receptors, it is removed from extracellular space by high affinity Na^+-dependent glutamate transporters, which utilize the Na^+/K^+ electrochemical gradient as a driving force and located in nerve terminals and astrocytes. The glutamate transporters may modify the time course of synaptic events. Like glutamate itself, glutamate transporters are somehow involved in almost all aspects of normal and abnormal brain activity (e.g. cerebral ischemia, amyotrophic lateral sclerosis, Alzheimer's disease, traumatic brain injury, epilepsy and schizophrenia). The present study assessed transporter inhibitor for the ability to inhibit glutamate uptake by synaptosomes at the normal and hypergravity conditions (rats were rotated in a long-arm centrifuge at ten-G during one-hour period). DL-threo-beta-benzyloxyaspartate (DL-TBOA) is a newly developed competitive inhibitor of the high-affinity, Na^+-dependent glutamate transporters. As a potent, non- transported inhibitor of glutamate transporters, DL-TBOA promises to be a valuable new compound for the study of glutamatergic mechanisms. We demonstrated that DL-TBOA inhibited glutamate uptake ( 100 μM glutamate, 30 sec incubation period) in dose-dependent manner as in control as in hypergravity. The effect of this transport inhibitor on glutamate uptake by control synaptosomes and synaptosomes prepared of animals exposed to hypergravity was different. IC50 values calculated on the basis of curves of non-linear regression kinetic analysis was 18±2 μM and 11±2 μM ((P≤0,05) before and after exposure to artificial gravity, respectively. Inhibition caused by 10 μM DL-TBOA was significantly increased from 38,0±3,8 % in control group to 51,0±4,1 % in animals, exposed to hypergravity (P≤0,05). Thus, DL-TBOA had complex effect on glutamate uptake process and perhaps, became more potent under

  10. Hispidulin inhibits the release of glutamate in rat cerebrocortical nerve terminals

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tzu-Yu [Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei, 22060, Taiwan (China); Department of Mechanical Engineering, Yuan Ze University, Taoyuan, 320, Taiwan (China); Lu, Cheng-Wei [Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei, 22060, Taiwan (China); Wang, Chia-Chuan; Lu, Jyh-Feng [School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei, 24205, Taiwan (China); Wang, Su-Jane, E-mail: med0003@mail.fju.edu.tw [Graduate Institute of Basic Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei, 24205, Taiwan (China); School of Medicine, Fu Jen Catholic University, No.510, Zhongzheng Rd., Xinzhuang Dist., New Taipei, 24205, Taiwan (China)

    2012-09-01

    Hispidulin, a naturally occurring flavone, has been reported to have an antiepileptic profile. An excessive release of glutamate is considered to be related to neuropathology of epilepsy. We investigated whether hispidulin affected endogenous glutamate release in rat cerebral cortex nerve terminals (synaptosomes) and explored the possible mechanism. Hispidulin inhibited the release of glutamate evoked by the K{sup +} channel blocker 4-aminopyridine (4-AP). The effects of hispidulin on the evoked glutamate release were prevented by the chelation of extracellular Ca{sup 2+} ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate did not have any effect on hispidulin action. Hispidulin reduced the depolarization-induced increase in cytosolic free Ca{sup 2+} concentration ([Ca{sup 2+}]{sub C}), but did not alter 4-AP-mediated depolarization. Furthermore, the effect of hispidulin on evoked glutamate release was abolished by blocking the Ca{sub v}2.2 (N-type) and Ca{sub v}2.1 (P/Q-type) channels, but not by blocking ryanodine receptors or mitochondrial Na{sup +}/Ca{sup 2+} exchange. Mitogen-activated protein kinase kinase (MEK) inhibition also prevented the inhibitory effect of hispidulin on evoked glutamate release. Western blot analyses showed that hispidulin decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synaptic vesicle-associated protein synapsin I, a major presynaptic substrate for ERK; this decrease was also blocked by the MEK inhibitor. Moreover, the inhibition of glutamate release by hispidulin was strongly attenuated in mice without synapsin I. These results show that hispidulin inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca{sup 2+} entry and ERK/synapsin I signaling pathway. -- Highlights: ► Hispidulin inhibited glutamate release from rat

  11. Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier

    Directory of Open Access Journals (Sweden)

    Dorota Sulejczak

    2016-12-01

    Full Text Available An excessive glutamate level can result in excitotoxic damage and death of central nervous system (CNS cells, and is involved in the pathogenesis of many CNS diseases. It may also be related to a failure of the blood-spinal cord barrier (BSCB. This study was aimed at examining the effects of extended administration of monosodium glutamate on the BSCB and spinal cord cells in adult male Wistar rats. The glutamate was delivered by subarachnoidal application of glutamate-carrying electrospun nanofiber mat dressing at the lumbar enlargement level. Half of the rats with the glutamate-loaded mat application were treated systemically with the histone deacetylase inhibitor valproic acid. A group of intact rats and a rat group with subarachnoidal application of an ‘empty’ (i.e., carrying no glutamate nanofiber mat dressing served as controls. All the rats were euthanized three weeks later and lumbar fragments of their spinal cords were harvested for histological, immunohistochemical and ultrastructural studies. The samples from controls revealed normal parenchyma and BSCB morphology, whereas those from rats with the glutamate-loaded nanofiber mat dressing showed many intraparenchymal microhemorrhages of variable sizes. The capillaries in the vicinity of the glutamate-carrying dressing (in the meninges and white matter alike were edematous and leaky, and their endothelial cells showed degenerative changes: extensive swelling, enhanced vacuo­lization and the presence of vascular intraluminal projections. However, endothelial tight junctions were generally well preserved. Some endothelial cells were dying by necrosis or apoptosis. The adjacent parenchyma showed astrogliosis with astrocytic hypertrophy and swelling of perivascular astrocytic feet. Neurons in the parenchyma revealed multiple symptoms of degeneration, including, inter alia, perikaryal, dendritic and axonal swelling, and destruction of organelles. All the damage symptoms were slightly less

  12. Efficient gamma-aminobutyric acid bioconversion by employing synthetic complex between glutamate decarboxylase and glutamate/GABA antiporter in engineered Escherichia coli.

    Science.gov (United States)

    Le Vo, Tam Dinh; Ko, Ji-seun; Park, Si Jae; Lee, Seung Hwan; Hong, Soon Ho

    2013-08-01

    Gamma-aminobutyric acid (GABA) is a precursor of one of the most promising heat-resistant biopolymers, Nylon-4, and can be produced by the decarboxylation of monosodium glutamate (MSG). In this study, a synthetic protein complex was applied to improve the GABA conversion in engineered Escherichia coli. Complexes were constructed by assembling a single protein-protein interaction domain SH3 to the glutamate decarboxylase (GadA and GadB) and attaching a cognate peptide ligand to the glutamate/GABA antiporter (GadC) at the N-terminus, C-terminus, and the 233rd amino acid residue. When GadA and GadC were co-overexpressed via the C-terminus complex, a GABA concentration of 5.65 g/l was obtained from 10 g/l MSG, which corresponds to a GABA yield of 93 %. A significant increase of the GABA productivity was also observed where the GABA productivity increased 2.5-fold in the early culture period due to the introduction of the synthetic protein complex. The GABA pathway efficiency and GABA productivity were enhanced by the introduction of the complex between Gad and glutamate/GABA antiporter.

  13. Prevalence of glutamic acid decarboxylase antibodies amongst young Malaysian diabetics.

    Science.gov (United States)

    Wan Nazaimoon, W M; Faridah, I; Singaraveloo, M; Ismail, I S; Wan Mohamad, W B; Letchuman, R; Rasat, R; Pendek, R; Hew, F L; Sheriff, I H; Khalid, B A

    1999-01-01

    This study determined the prevalence of glutamic acid decarboxylase antibodies (GAD Ab) in a group of 926 young Malaysian diabetics of three ethnic groups, Malay, Chinese, and Indian. Patients were clinically diagnosed to be Type 1 or Type 2 before the age of 40 years. The overall GAD Ab positivity was 17.4% (161/926), significantly higher in the Type 1 than the Type 2 diabetics (35.5%, 116/329 vs. 7.5%, 45/597, P=0.0001). Compared to GAD Ab negative patients, seropositive diabetics were diagnosed at younger age (21.2+/-0.9 vs. 27.4+/-0.3 y, P=0.0001), had lower fasting (289+/-27.4 vs. 640+/-17.6 pmol/l, P=0.0001) and post-glucagon C-peptide levels (527+/-51.8 vs. 1030+/-28.9 pmol/l, P=0.0001). There were no racial differences in the prevalence of GAD Ab; of the total Type 1, 30.8, 36.4, and 39.4% were Malay, Chinese, and Indian diabetics, respectively and of the total Type 2, 8.8, 8.2, and 4.4% were Malay, Chinese, and Indian diabetics respectively. There was a curvilinear relationship between GAD Ab and the post-glucagon C-peptide levels, suggesting that GAD Ab do play a role in the beta-cells destruction and could be an important immune marker for the LADA group. This study reconfirmed previous reports that the autoimmune mechanisms in the Type 1 Asian diabetics are indeed different from the Caucasians, and further investigations should be carried out to explain the differences.

  14. Frequency of glutamic acid decarboxylase autoantibodies in Mexican diabetic children.

    Science.gov (United States)

    Mendoza-Morfín, F; Curiel-Pérez, M O; Cárdenas-Tirado, H; Montero-González, P; Gutiérrez-Avila, C; Bravo-Ríos, L E; Cárdenas-Cornejo, I; Normandía-Almeida, M A

    2000-01-01

    Use radio binding assay (RBA) to quantify the frequency of autoantibodies to glutamic acid decarboxylase in Mexican children with type 1 diabetes mellitus (DM 1). GAD antibodies were measured in 140 mestizo children with DM 1, 66 female (47.14%) and 74 male (52.8%); age 11.7 +/- 3.55 years, and range 1.10 to 18.5 years. Most patients were treated with intermediate acting insulin, and some with the former combined with regular insulin. Mean disease duration was 3.11 +/- 2.94 years, and range 1 month to 14.5 years. Once the signed written consent was obtained, a 5.0-mL blood sample was drawn, immediately centrifuged, and the serum was kept frozen to -20 degrees C until RBA evaluation was performed with a commercial kit. The anti-GAD was positive in 76 DM 1 patients (54.28%) with values from 1.11 to 156.73 U/mL, and negative in 64 (45.71%). In 19 positive anti-GAD patients, the test was repeated and levels were found between 1.38 and 156.62 U/mL. An initial control group consisting of 25 healthy non-related volunteers matched by sex and age, showed negative anti-GAD for all. The frequency of anti-GAD in these patients was lower than that of the DM 1 European patients, but similar to that of Asians. This supports the heterogeneity of the etiopathogenic factors of DM 1 in different ethnic groups.

  15. The sensitivity of male rat reproductive organs to monosodium glutamate

    Directory of Open Access Journals (Sweden)

    Sitthichai Iamsaard

    2014-05-01

    Full Text Available Objective. This study aimed to investigate the sensitivity of the testis, epididymis, seminal vesicle, and sperm acrosome reaction (AR to monosodium L- glutamate (MSG in rats. Materials and methods. Rats were divided into four groups and fed with non-acidic MSG at 0.25, 3 or 6 g/kg body weight for 30 days or without MSG. The morphological changes in the reproductive organs were studied. The plasma testosterone level, epididymal sperm concentration, and sperm AR status were assayed. Results. Compared to the control, no significant changes were discerned in the morphology and weight of the testes, or the histological structures of epididymis, vas deferens and seminal vesicle. In contrast, significant decreases were detected in the weight of the epididymis, testosterone levels, and sperm concentration of rats treated with 6 g/kg body weight of MSG. The weight loss was evident in the seminal vesicle in MSG-administered rats. Moreover, rats treated with MSG 3 and 6 g/kg exhibited partial testicular damage, characterized by sloughing of spermatogenic cells into the seminiferous tubular lumen, and their plasma testosterone levels were significantly decreased. In the 6 g/kg MSG group, the sperm concentration was significantly decreased compared with the control or two lower dose MSG groups. In AR assays, there was no statistically significant difference between MSG-rats and normal rats. Conclusion. Testicular morphological changes, testosterone level, and sperm concentration were sensitive to high doses of MSG while the rate of AR was not affected. Therefore, the consumption of high dose MSG must be avoided because it may cause partial infertility in male.

  16. [Glutamate dehydrogenase. Its diagnostic value in Clostridioides difficile diarrhea].

    Science.gov (United States)

    Vaustat, Daniela; Rollet, Raquel

    2017-11-14

    Clostridioides difficile is the main etiological agent of diarrhea associated with health care, it produces toxins and glutamate dehydrogenase (GDH), an enzyme that is highly conserved in this species. Rapid diagnosis and effective treatment produce prompt improvement of the patient and subsequent control of the microorganism spread. There are several techniques whose results are interpreted in the context of algorithms. However, the optimal diagnostic method is yet unknown. The performance of GDH as a screening test for the diagnosis of C. difficile diarrhea was assessed. Six hundred and fifteen stool samples were studied. The presence of GDH and toxins presence was determined by TECHLAB® C. DIFF QUIK-CHEK COMPLETE and the samples were cultured for the search of C. difficile. The values of sensitivity, specificity, PPV and NPV were calculated with a p value of 0.05 or less. GDH was detected in 266 samples (43.25%), with a sensitivity of 100% and specificity of 87.10%, IC95: 84.58-91.42; toxin/s were detected in 218 (35.45%) and C. difficile developed in 235 cultures (38.21%). From 48 samples with positive GDH and negative toxin/s, 15 toxigenic and 2 non-toxigenic isolates were obtained, the remaining 31 samples were negative for C. difficile. All GDH-negative samples were negative for toxins or culture, therefore, GDH NPV was 100%, while PPV was 81.9%. We conclude that GDH is a suitable screening test for the diagnostic algorithm of C. difficile diarrhea. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Cecilia Gonzalez Campo

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

  18. Repeated phencyclidine administration alters glutamate release and decreases GABA markers in the prefrontal cortex of rats

    Science.gov (United States)

    Amitai, Nurith; Kuczenski, Ronald; Behrens, M. Margarita; Markou, Athina

    2011-01-01

    Repeated phencyclidine (PCP) administration induces cognitive disruptions resembling those seen in schizophrenia. Alterations in glutamate transmission and γ-aminobutyric acid (GABA) function in the prefrontal cortex (PFC) have been implicated in these PCP-induced deficits, as well as in cognitive symptoms of schizophrenia. PCP-induced cognitive deficits are reversed by chronic treatment with the atypical antipsychotic clozapine in rats. We investigated the effects of a single injection vs. repeated administration of PCP on glutamate levels in the PFC using in vivo microdialysis. Furthermore, we examined how these PCP regimens affect GABA neuronal markers in the PFC. Finally, we investigated the effects of clozapine on disruptions in glutamate levels and GABA neuronal markers induced by repeated PCP administration. Acute PCP administration (2 mg/kg) increased extracellular PFC glutamate; this increase appeared blunted, but was not eliminated, after repeated PCP pretreatment. PCP administration also strongly decreased levels of parvalbumin and glutamic acid decarboxylase-67 (two markers of GABA function) in the PFC, an effect that was maintained after a 10 day drug-free washout period and unaltered by the resumption of repeated PCP injections. All of the observed PCP effects were attenuated by chronic treatment with clozapine, an atypical antipsychotic that has partial effectiveness on cognitive impairment in schizophrenia. These findings suggest that abnormal cortical glutamate transmission, possibly driven by pathological changes in GABA function in parvalbumin-positive fast-spiking interneurons, may underlie some of the cognitive deficits in schizophrenia. A better understanding of glutamate and GABA dysregulation in schizophrenia may uncover new treatment targets for schizophrenia-related cognitive dysfunction. PMID:21238466

  19. Glutamate/GABA+ ratio is associated with the psychosocial domain of autistic and schizotypal traits

    Science.gov (United States)

    Nibbs, Richard; Crewther, David P.

    2017-01-01

    Background The autism and schizophrenia spectra overlap to a large degree in the social and interpersonal domains. Similarly, abnormal excitatory glutamate and inhibitory γ-aminobutyric acid (GABA) neurotransmitter concentrations have been reported for both spectra, with the interplay of these neurotransmitters important for cortical excitation to inhibition regulation. This study investigates whether these neurotransmitter abnormalities are specific to the shared symptomatology, and whether the degree of abnormality increases with increasing symptom severity. Hence, the relationship between the glutamate/GABA ratio and autism and schizophrenia spectrum traits in an unmedicated, subclinical population was investigated. Methods A total of 37 adults (19 female, 18 male) aged 18-38 years completed the Autism Spectrum Quotient (AQ) and Schizotypal Personality Questionnaire (SPQ), and participated in the resting state proton magnetic resonance spectroscopy study in which sequences specific for quantification of glutamate and GABA+ concentration were applied to a right and left superior temporal voxel. Results There were significant, moderate, positive relationships between right superior temporal glutamate/GABA+ ratio and AQ, SPQ and AQ+SPQ total scores (p<0.05), SPQ subscales Social Anxiety, No Close Friend, Constricted Affect, Odd Behaviour, Odd Speech, Ideas of Reference and Suspiciousness, and AQ subscales Social Skills, Communication and Attention Switching (p<0.05); increased glutamate/GABA+ coinciding with higher scores on these subscales. Only the relationships between glutamate/GABA+ ratio and Social Anxiety, Constricted Affect, Social Skills and Communication survived multiple comparison correction (p< 0.004). Left superior temporal glutamate/GABA+ ratio reduced with increasing restricted imagination (p<0.05). Conclusion These findings demonstrate evidence for an association between excitatory/inhibitory neurotransmitter concentrations and symptoms that are

  20. Supplementing monosodium glutamate to partial enteral nutrition slows gastric emptying in preterm pigs(1-3).

    Science.gov (United States)

    Bauchart-Thevret, Caroline; Stoll, Barbara; Benight, Nancy M; Olutoye, Oluyinka; Lazar, David; Burrin, Douglas G

    2013-05-01

    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 received partial enteral nutrition (25%) as milk-based formula supplemented with MSG at 0, 1.7, 3.0, and 4.3 times the basal protein-bound glutamate intake (468 mg·kg(-1)·d(-1)) from d 4 to 8 of life (n = 5-8). Whole-body respiratory calorimetry and (13)C-octanoic acid breath tests were performed on d 4, 6, and 8. Body weight gain, stomach and intestinal weights, and arterial plasma glutamate and glutamine concentrations were not different among the MSG groups. Arterial plasma glutamate concentrations were significantly higher at birth than after 8 d of partial enteral nutrition. Also at d 8, the significant portal-arterial concentration difference in plasma glutamate was substantial (∼500 μmol/L) among all treatment groups, suggesting that there was substantial net intestinal glutamate absorption in preterm pigs. MSG supplementation dose-dependently increased gastric emptying time and decreased breath (13)CO2 enrichments, (13)CO2 production, percentage of (13)CO2 recovery/h, and cumulative percentage recovery of (13)C-octanoic acid. Circulating glucagon-like peptide-2 (GLP-2) concentration was significantly increased by MSG but was not associated with an increase in intestinal mucosal growth. In contrast to our hypothesis, our results suggest that adding MSG to partial enteral nutrition slows the gastric emptying rate, which may be associated with an inhibitory effect of increased circulating GLP-2.

  1. Supplementing Monosodium Glutamate to Partial Enteral Nutrition Slows Gastric Emptying in Preterm Pigs123

    Science.gov (United States)

    Bauchart-Thevret, Caroline; Stoll, Barbara; Benight, Nancy M.; Olutoye, Oluyinka; Lazar, David; Burrin, Douglas G.

    2013-01-01

    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 received partial enteral nutrition (25%) as milk-based formula supplemented with MSG at 0, 1.7, 3.0, and 4.3 times the basal protein-bound glutamate intake (468 mg·kg−1·d−1) from d 4 to 8 of life (n = 5–8). Whole-body respiratory calorimetry and 13C-octanoic acid breath tests were performed on d 4, 6, and 8. Body weight gain, stomach and intestinal weights, and arterial plasma glutamate and glutamine concentrations were not different among the MSG groups. Arterial plasma glutamate concentrations were significantly higher at birth than after 8 d of partial enteral nutrition. Also at d 8, the significant portal-arterial concentration difference in plasma glutamate was substantial (∼500 μmol/L) among all treatment groups, suggesting that there was substantial net intestinal glutamate absorption in preterm pigs. MSG supplementation dose-dependently increased gastric emptying time and decreased breath 13CO2 enrichments, 13CO2 production, percentage of 13CO2 recovery/h, and cumulative percentage recovery of 13C-octanoic acid. Circulating glucagon-like peptide-2 (GLP-2) concentration was significantly increased by MSG but was not associated with an increase in intestinal mucosal growth. In contrast to our hypothesis, our results suggest that adding MSG to partial enteral nutrition slows the gastric emptying rate, which may be associated with an inhibitory effect of increased circulating GLP-2. PMID:23446960

  2. Systemic Pregabalin Attenuates Sensorimotor Responses and Medullary Glutamate Release in Inflammatory Tooth Pain Model

    Science.gov (United States)

    Narita, Noriyuki; Kumar, Naresh; Cherkas, Pavel S.; Chiang, Chen Yu; Dostrovsky, Jonathan O.; Coderre, Terence J.; Sessle, Barry J.

    2012-01-01

    Our previous studies have demonstrated that application to the tooth pulp of the inflammatory irritant mustard oil (MO) induces medullary glutamate release and central sensitization in the rat medullary dorsal horn (MDH), as well as nociceptive sensorimotor responses in craniofacial muscles in rats. There is recent evidence that anticonvulsant drugs such as pregabalin that influence glutamatergic neurotransmission are effective in several pain states. The aim of this study was to examine whether systemic administration of pregabalin attenuated glutamate release in the medulla as well as these nociceptive effects reflected in increased electromyographic (EMG) activity induced by MO application to the tooth pulp. Male adult rats were anesthetized with isofluorane (1.0~1.2 %), and jaw and tongue muscle EMG activities were recorded by needle electrodes inserted bilaterally into masseter and anterior digastric muscles and into the genioglossus muscle, and also the medullary release of glutamate was assessed by in vivo microdialysis. Pregabalin or vehicle control (isotonic saline) was administered 30 min before the pulpal application of MO or vehicle control (mineral oil). Application of mineral oil to the maxillary first molar tooth pulp produced no change in baseline EMG activity and glutamate release. However, application of MO to the pulp significantly increased both the medullary release of glutamate and EMG activity in the jaw and tongue muscles for several minutes. In contrast, pre-medication with pregabalin, but not vehicle control, significantly and dose-dependently attenuated the medullary glutamate release and EMG activity in these muscles after MO application to the tooth pulp (ANOVA, ppregabalin may attenuate the medullary release of glutamate and associated nociceptive sensorimotor responses in this acute inflammatory pulpal pain model, and that it may prove useful for the treatment of orofacial inflammatory pain states. PMID:22609939

  3. Neuroprotective effects of α-iso-cubebenol on glutamate-induced neurotoxicity.

    Science.gov (United States)

    Park, Sun Young; Choi, Yung Hyun; Park, Geuntae; Choi, Young-Whan

    2015-09-01

    α-Iso-cubebenol is a natural compound isolated from Schisandra chinensis, and is reported to have beneficial bioactivity including anti-inflammatory and anti-tumor activities. Glutamate-induced oxidative neuronal damage has been implicated in a variety of neurodegenerative disorders. Here we investigated the mechanisms of α-iso-cubebenol protection of mouse hippocampus-derived neuronal cells (HT22 cells) from apoptotic cell death induced by the major excitatory neurotransmitter, glutamate. Pretreatment with α-iso-cubebenol markedly attenuated glutamate-induced loss of cell viability and release of lactate dehydrogenase), in a dose-dependent manner. α-Iso-cubebenol significantly reduced glutamate-induced intracellular reactive oxygen species and calcium accumulation. Strikingly, α-iso-cubebenol inhibited glutamate-induced mitochondrial depolarization, which releases apoptosis-inducing factor from mitochondria. α-Iso-cubebenol also suppressed glutamate-induced phosphorylation of extracellular-signal-regulated kinases. Furthermore, α-iso-cubebenol induced CREB phosphorylation and Nrf-2 nuclear accumulation and increased the promoter activity of ARE and CREB in HT22 cells. α-Iso-cubebenol also upregulated the expression of phase-II detoxifying/antioxidant enzymes such as HO-1 and NQO1. Subsequent studies revealed that the inhibitory effects of α-iso-cubebenol on glutamate-induced apoptosis were abolished by small interfering RNA-mediated knockdown of CREB and Nrf-2. These findings suggest that α-iso-cubebenol prevents excitotoxin-induced oxidative damage to neurons by inhibiting apoptotic cell death, and might be a potential preventive or therapeutic agent for neurodegenerative disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Effect of Glutamine, Glutamic Acid and Nucleotides on the Turnover of Carbon (δC) in Organs of Weaned Piglets

    OpenAIRE

    Alessandro Borges Amorim; Dirlei Antonio Berto; Mayra Anton Dib Saleh; Filipe Garcia Telles; Juliana Célia Denadai; Maria Márcia Pereira Sartori; Fabiana Golin Luiggi; Luan Sousa Santos; Carlos Ducatti

    2016-01-01

    Morphological and physiological alterations occur in the digestive system of weanling piglets, compromising the performance in subsequent phases. This experiment aimed at verifying the influence of glutamine, glutamate and nucleotides on the carbon turnover in the pancreas and liver of piglets weaned at 21 days of age. Four diets were evaluated: glutamine, glutamic acid or nucleotides-free diet (CD); containing 1% glutamine (GD); containing 1% glutamic acid (GAD) and containing 1% nucleotides...

  5. A Detailed Model of Electroenzymatic Glutamate Biosensors to Aid in Sensor Optimization and in Applications in vivo.

    Science.gov (United States)

    Clay, Mackenzie; Monbouquette, Harold G

    2017-10-27

    Simulations conducted with a detailed model of glutamate biosensor performance describe observed sensor performance well, illustrate the limits of sensor performance, and suggest a path toward sensor optimization. Glutamate is the most important excitatory neurotransmitter in the brain, and electroenzymatic sensors have emerged as a useful tool for the monitoring of glutamate signaling in vivo. However, the utility of these sensors currently is limited by their sensitivity and response time. A mathematical model of a typical glutamate biosensor consisting of a Pt electrode coated with a permselective polymer film and a top layer of crosslinked glutamate oxidase has been constructed in terms of differential material balances on glutamate, H2O2 and O2 in one spatial dimension. Simulations suggest that reducing thicknesses of the permselective polymer and enzyme layers can increase sensitivity ~6-fold and reduce response time ~7-fold, and thereby improve resolution of transient glutamate signals. At currently employed enzyme layer thicknesses, both intrinsic enzyme kinetics and enzyme deactivation likely are masked by mass transfer. However, O2 dependence studies show essentially no reduction in signal at the lowest anticipated O2 concentrations for expected glutamate concentrations in the brain, and that O2 transport limitations in vitro are anticipated only at glutamate concentrations in the mM range. Finally, the limitations of current biosensors in monitoring glutamate transients is simulated and used to illustrate the need for optimized biosensors to report glutamate signaling accurately on a subsecond timescale. This work demonstrates how a detailed model can be used to guide optimization of electroenzymatic sensors similar to that for glutamate and to ensure appropriate interpretation of data gathered using such biosensors.

  6. Astrocytes and Glutamate Homoeostasis in Alzheimer's Disease: A Decrease in Glutamine Synthetase, But Not in Glutamate Transporter-1, in the Prefrontal Cortex

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    Magdalena Kulijewicz-Nawrot

    2013-09-01

    Full Text Available Astrocytes control tissue equilibrium and hence define the homoeostasis and function of the CNS (central nervous system. Being principal homoeostatic cells, astroglia are fundamental for various forms of neuropathology, including AD (Alzheimer's disease. AD is a progressive neurodegenerative disorder characterized by the loss of cognitive functions due to specific lesions in mnesic-associated regions, including the mPFC (medial prefrontal cortex. Here, we analyzed the expression of GS (glutamine synthetase and GLT-1 (glutamate transporter-1 in astrocytes in the mPFC during the progression of AD in a triple-transgenic mouse model (3xTg-AD. GS is an astrocyte-specific enzyme, responsible for the intracellular conversion of glutamate into glutamine, whereas the removal of glutamate from the extracellular space is accomplished mainly by astroglia-specific GLT-1. We found a significant decrease in the numerical density (Nv, cells/mm3 of GS-positive astrocytes from early to middle ages (1–9 months; at the age of 1 month by 17%, 6 months by 27% and 9 months by 27% when compared with control animals in parallel with a reduced expression of GS (determined by Western blots, which started at the age of 6 months and was sustained up to 12 months of age. We did not, however, find any changes in the expression of GLT-1, which implies an intact glutamate uptake mechanism. Our results indicate that the decrease in GS expression may underlie a gradual decline in the vital astrocyte-dependent glutamate–glutamine conversion pathway, which in turn may compromise glutamate homoeostasis, leading towards failures in synaptic connectivity with deficient cognition and memory.

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

    Science.gov (United States)

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

    2018-02-14

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

  8. Traumatic Brain Injury Increases Cortical Glutamate Network Activity by Compromising GABAergic Control.

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    Cantu, David; Walker, Kendall; Andresen, Lauren; Taylor-Weiner, Amaro; Hampton, David; Tesco, Giuseppina; Dulla, Chris G

    2015-08-01

    Traumatic brain injury (TBI) is a major risk factor for developing pharmaco-resistant epilepsy. Although disruptions in brain circuitry are associated with TBI, the precise mechanisms by which brain injury leads to epileptiform network activity is unknown. Using controlled cortical impact (CCI) as a model of TBI, we examined how cortical excitability and glutamatergic signaling was altered following injury. We optically mapped cortical glutamate signaling using FRET-based glutamate biosensors, while simultaneously recording cortical field potentials in acute brain slices 2-4 weeks following CCI. Cortical electrical stimulation evoked polyphasic, epileptiform field potentials and disrupted the input-output relationship in deep layers of CCI-injured cortex. High-speed glutamate biosensor imaging showed that glutamate signaling was significantly increased in the injured cortex. Elevated glutamate responses correlated with epileptiform activity, were highest directly adjacent to the injury, and spread via deep cortical layers. Immunoreactivity for markers of GABAergic interneurons were significantly decreased throughout CCI cortex. Lastly, spontaneous inhibitory postsynaptic current frequency decreased and spontaneous excitatory postsynaptic current increased after CCI injury. Our results suggest that specific cortical neuronal microcircuits may initiate and facilitate the spread of epileptiform activity following TBI. Increased glutamatergic signaling due to loss of GABAergic control may provide a mechanism by which TBI can give rise to post-traumatic epilepsy. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Design, synthesis and biological evaluation of small-azo-dyes as potent Vesicular Glutamate Transporters inhibitors.

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    Favre-Besse, Franck-Cyril; Poirel, Odile; Bersot, Tiphaine; Kim-Grellier, Elodie; Daumas, Stephanie; El Mestikawy, Salah; Acher, Francine C; Pietrancosta, Nicolas

    2014-05-06

    Vesicular Glutamate Transporters (VGLUTs) allow the loading of presynapic glutamate vesicles and thus play a critical role in glutamatergic synaptic transmission. VGLUTs have proved to be involved in several major neuropathologies and directly correlated to clinical dementia in Alzheimer and Parkinson's disease. Accordingly VGLUT represent a key biological target or biomarker for neuropathology treatment or diagnostic. Yet, despite the pivotal role of VGLUTs, their pharmacology appears quite limited. Known competitive inhibitors are restricted to some dyes as Trypan Blue (TB) and glutamate mimics. This lack of pharmacological tools has heavily hampered VGLUT investigations. Here we report a rapid access to small molecules that combine benefits of TB and dicarboxylic quinolines (DCQs). Their ability to block vesicular glutamate uptake was evaluated. Several compounds displayed low micromolar inhibitory potency when size related compounds are thirty to forty times less potent (i.e. DCQ). We then confirmed the VGLUT selectivity by measuring the effect of the series on vesicular monoamine transport and on metabotropic glutamate receptor activity. These inhibitors are synthesized in only two steps and count among the best pharmacological tools for VGLUTs studies. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

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

    Science.gov (United States)

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

    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 ceftriaxone, a beta-lactam antibiotic, have been effective in attenuating drug-seeking and drug-consumption behavior in rodent models. However, potential obstacles toward clinical translation of GLT1 (EAAT2) upregulators as treatment for drug addiction might include poor gastrointestinal absorption, serious peripheral adverse effects, and/or suboptimal CNS concentrations. Given the growing success of nanotechnology in targeting CNS ailments, nanoformulating known GLT1 (EAAT2) upregulators for selective uptake across the blood brain barrier presents an ideal therapeutic approach for treating drug addiction. In this review, we summarize the results obtained with promising GLT1 (EAAT2) inducing compounds in animal models recapitulating drug addiction. Additionally, the various nanoformulations that can be employed for selectively increasing the CNS bioavailability of GLT1 (EAAT2) upregulators are discussed. Finally, the applicability of GLT1 (EAAT2) induction via central delivery of drug-loaded nanoformulations is described.

  11. Glutamate oxaloacetate transaminase enables anaplerotic refilling of TCA cycle intermediates in stroke-affected brain.

    Science.gov (United States)

    Rink, Cameron; Gnyawali, Surya; Stewart, Richard; Teplitsky, Seth; Harris, Hallie; Roy, Sashwati; Sen, Chandan K; Khanna, Savita

    2017-04-01

    Ischemic stroke results in excessive release of glutamate, which contributes to neuronal cell death. Here, we test the hypothesis that otherwise neurotoxic glutamate can be productively metabolized by glutamate oxaloacetate transaminase (GOT) to maintain cellular energetics and protect the brain from ischemic stroke injury. The GOT-dependent metabolism of glutamate was studied in primary neural cells and in stroke-affected C57-BL6 mice using magnetic resonance spectroscopy and GC-MS. Extracellular Glu sustained cell viability under hypoglycemic conditions and increased GOT-mediated metabolism in vitro Correction of stroke-induced hypoxia using supplemental oxygen in vivo lowered Glu levels as measured by 1H magnetic resonance spectroscopy. GOT knockdown abrogated this effect and caused ATP loss in the stroke-affected brain. GOT overexpression increased anaplerotic refilling of tricarboxylic acid cycle intermediates in mouse brain during ischemic stroke. Furthermore, GOT overexpression not only reduced ischemic stroke lesion volume but also attenuated neurodegeneration and improved poststroke sensorimotor function. Taken together, our results support a new paradigm that GOT enables metabolism of otherwise neurotoxic extracellular Glu through a truncated tricarboxylic acid cycle under hypoglycemic conditions.-Rink, C., Gnyawali, S., Stewart, R., Teplitsky, S., Harris, H., Roy, S., Sen, C. K., Khanna, S. Glutamate oxaloacetate transaminase enables anaplerotic refilling of TCA cycle intermediates in stroke-affected brain. © FASEB.

  12. Traumatic Brain Injury Increases Cortical Glutamate Network Activity by Compromising GABAergic Control

    Science.gov (United States)

    Cantu, David; Walker, Kendall; Andresen, Lauren; Taylor-Weiner, Amaro; Hampton, David; Tesco, Giuseppina; Dulla, Chris G.

    2015-01-01

    Traumatic brain injury (TBI) is a major risk factor for developing pharmaco-resistant epilepsy. Although disruptions in brain circuitry are associated with TBI, the precise mechanisms by which brain injury leads to epileptiform network activity is unknown. Using controlled cortical impact (CCI) as a model of TBI, we examined how cortical excitability and glutamatergic signaling was altered following injury. We optically mapped cortical glutamate signaling using FRET-based glutamate biosensors, while simultaneously recording cortical field potentials in acute brain slices 2–4 weeks following CCI. Cortical electrical stimulation evoked polyphasic, epileptiform field potentials and disrupted the input–output relationship in deep layers of CCI-injured cortex. High-speed glutamate biosensor imaging showed that glutamate signaling was significantly increased in the injured cortex. Elevated glutamate responses correlated with epileptiform activity, were highest directly adjacent to the injury, and spread via deep cortical layers. Immunoreactivity for markers of GABAergic interneurons were significantly decreased throughout CCI cortex. Lastly, spontaneous inhibitory postsynaptic current frequency decreased and spontaneous excitatory postsynaptic current increased after CCI injury. Our results suggest that specific cortical neuronal microcircuits may initiate and facilitate the spread of epileptiform activity following TBI. Increased glutamatergic signaling due to loss of GABAergic control may provide a mechanism by which TBI can give rise to post-traumatic epilepsy. PMID:24610117

  13. Ganglioside inhibition of glutamate-mediated protein kinase C translocation in primary cultures of cerebellar neurons

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    Vaccarino, F.; Guidotti, A.; Costa, E.

    1987-12-01

    In primary cultures of cerebellar granule cells, protein kinase C (PKC) translocation and activation can be triggered by the stimulation of excitatory amino acid neurotransmitter receptors. Glutamate evokes a dose-related translocation of 4-..beta..-(/sup 3/H)phorbol 12,13-dibutyrate /(/sup 3/H)-P(BtO)/sub 2// binding sites from the cytosol to the neuronal membrane and stimulates the incorporation of /sup 32/P into a number of membrane proteins, particularly protein bands in the range of 80, 50, and 40 kDa. The glutamate-evoked PKC translocation is Mg/sup 2 +/ sensitive, is prevented by 2-amino-5-phosphonovalerate and phencyclidine, is not inhibited by nitrendipine (a voltage-dependent Ca/sup 2 +/-channel-blocker) but is abolished by the removal of Ca/sup 2 +/ from the incubation medium, suggesting that glutamate-mediated Ca/sup 2 +/ influx is operative in the redistribution of PKC. Exposure of granule cells to the gangliosides trisialosylgangliotetraglycosylceramide (GT1b) of monosialosylgangliotetraglycosylceramide (GM1) inhibits the translocation and activation of PKC evoked by glutamate. These glycosphingolipids fail to interfere with glutamate binding to its high-affinity recognition site of with the (/sup 3/H)P(BtO)/sub 2/ binding, nor do they affect the Ca/sup 2 +/ influx. These gangliosides may prevent PKC translocation by interfering with the PKC binding to the neuronal membrane phosphatidylserine.

  14. Glutamate in the parabrachial nucleus of rats during conditioned taste aversion.

    Science.gov (United States)

    Bielavska, E; Miksik, I; Krivanek, J

    2000-12-29

    Brain microdialysis combined with HPLC and spectroscopic detection was used to monitor extracellular glutamate in the parabrachial nucleus (PBN) of rats during acquisition of a conditioned taste aversion (CTA). Microdialysis fractions taken every 20 min were used to assess the effects of presentation of the conditioned stimulus alone (CS, consumption of 0.1% saccharin), the unconditioned stimulus alone (US, intraperitoneal injection of 0.15 M LiCl, 2% b.w. induced malaise after water drinking) as well as that of CS-US pairing. After 15 min of saccharin drinking, the glutamate concentration in the eluate (20 microl/20 min) reached 80% above the baseline but returned to the basal value in the next fraction. LiCl alone (applied 1 h after 15 min drinking of water) increased glutamate only following some delay, i.e. in the second and third post-lithium fraction by 90 and 67%, respectively. However, when LiCl was injected 1 h after the onset of saccharin intake, the glutamate concentration rose significantly (by 95%) already in the first post-LiCl fraction and by 120% in the second one. It appears, therefore, that the 'saccharin trace' facilitates the effect of lithium on extracellular concentration of glutamate in PBN during acquisition of CTA.

  15. Imbalance between Glutamate and GABA in Fmr1 Knockout Astrocytes Influences Neuronal Development

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    Lu Wang

    2016-08-01

    Full Text Available Fragile X syndrome (FXS is a form of inherited mental retardation that results from the absence of the fragile X mental retardation protein (FMRP, the product of the Fmr1 gene. Numerous studies have shown that FMRP expression in astrocytes is important in the development of FXS. Although astrocytes affect neuronal dendrite development in Fmr1 knockout (KO mice, the factors released by astrocytes are still unclear. We cultured wild type (WT cortical neurons in astrocyte-conditioned medium (ACM from WT or Fmr1 KO mice. Immunocytochemistry and Western blotting were performed to detect the dendritic growth of both WT and KO neurons. We determined glutamate and γ-aminobutyric acid (GABA levels using high-performance liquid chromatography (HPLC. The total neuronal dendritic length was reduced when cultured in the Fmr1 KO ACM. This neurotoxicity was triggered by an imbalanced release of glutamate and GABA from Fmr1 KO astrocytes. We found increased glutaminase and GABA transaminase (GABA-T expression and decreased monoamine oxidase B expression in Fmr1 KO astrocytes. The elevated levels of glutamate contributed to oxidative stress in the cultured neurons. Vigabatrin (VGB, a GABA-T inhibitor, reversed the changes caused by glutamate and GABA release in Fmr1 KO astrocytes and the abnormal behaviors in Fmr1 KO mice. Our results indicate that the imbalance in the astrocytic glutamate and GABA release may be involved in the neuropathology and the underlying symptoms of FXS, and provides a therapeutic target for treatment.

  16. Glutamate and dopamine in schizophrenia: an update for the 21st century

    Science.gov (United States)

    Howes, Oliver; McCutcheon, Rob; Stone, James

    2016-01-01

    The glutamate and dopamine hypotheses are leading theories of the pathoaetiology of schizophrenia. Both were initially based on indirect evidence from pharmacological studies supported by post-mortem findings, but have since been substantially advanced by new lines of evidence from in vivo imaging studies. This review provides an up- date on the latest findings on dopamine and glutamate abnormalities in schizophrenia, focusing on the in vivo neuroimaging studies in patients and clinical high risk groups, and considers their implications for understanding the biology and treatment of schizophrenia. These findings have refined both the dopamine and glutamate hypotheses, enabling greater anatomical and functional specificity, and have been complemented by preclinical evidence showing how the risk factors for schizophrenia impact on the dopamine and glutamate systems. The implications of this new evidence for understanding the development and treatment of schizophrenia are considered, and the gaps in current knowledge highlighted. Finally the evidence for an integrated model of the interactions between the glutamate and dopamine systems is reviewed, and future directions discussed. PMID:25586400

  17. 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.

  18. Efficient production of poly-gamma-glutamic acid by Bacillus subtilis ZJU-7.

    Science.gov (United States)

    Shi, Feng; Xu, Zhinan; Cen, Peilin

    2006-06-01

    A strain with high poly-gamma-glutamic acid (gamma-PGA) production was isolated from fermented bean curd, a traditional Chinese food. The strain was named Bacillus subtilis ZJU-7 according to 16s rDNA sequencing and its taxonomic characters. The culture conditions for gamma-PGA production were evaluated. The most suitable carbon and nitrogen sources were sucrose and tryptone, respectively. Exogenous L-glutamic acid was necessary for gamma-PGA production, and the production of gamma-PGA increased on the addition of L-glutamic acid to the medium. In the medium containing 60 g/L of sucrose, 60 g/L of tryptone, 80 g/L of L-glutamic acid, and 10 g/L of NaCl, the yield of gamma-PGA reached 54.4 g/L after cultivation at 37 degrees C for 24 h, which was the highest gamma-PGA production compared with values reported in the literature. The average molecular mass of gamma-PGA produced was about 1.24 x 106 Daltons. B. subtilis ZJU-7 is genetically stable and can synthesize levan instead of gamma-PGA without the addition of L-glutamic acid to the medium.

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

    Science.gov (United States)

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

    2015-03-01

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

  20. Environmental comparison of biobased chemicals from glutamic acid with their petrochemical equivalents.

    Science.gov (United States)

    Lammens, Tijs M; Potting, José; Sanders, Johan P M; De Boer, Imke J M

    2011-10-01

    Glutamic acid is an important constituent of waste streams from biofuels production. It is an interesting starting material for the synthesis of biobased chemicals, thereby decreasing the dependency on fossil fuels. The objective of this paper was to compare the environmental impact of four biobased chemicals from glutamic acid with their petrochemical equivalents, that is, N-methylpyrrolidone (NMP), N-vinylpyrrolidone (NVP), acrylonitrile (ACN), and succinonitrile (SCN). A consequential life cycle assessment was performed, wherein glutamic acid was obtained from sugar beet vinasse. The removed glutamic acid was substituted with cane molasses and ureum. The comparison between the four biobased and petrochemical products showed that for NMP and NVP the biobased version had less impact on the environment, while for ACN and SCN the petrochemical version had less impact on the environment. For the latter two an optimized scenario was computed, which showed that the process for SCN can be improved to a level at which it can compete with the petrochemical process. For biobased ACN large improvements are required to make it competitive with its petrochemical equivalent. The results of this LCA and the research preceding it also show that glutamic acid can be a building block for a variety of molecules that are currently produced from petrochemical resources. Currently, most methods to produce biobased products are biotechnological processes based on sugar, but this paper demonstrates that the use of amino acids from low-value byproducts can certainly be a method as well.

  1. Sequential generation of hydrogen and methane from glutamic acid through combined photo-fermentation and methanogenesis.

    Science.gov (United States)

    Xia, Ao; Cheng, Jun; Lin, Richen; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2013-03-01

    Glutamic acid can hardly produce hydrogen via dark- or photo-fermentation without pretreatment. In this study, a novel process of acidogenic pretreatment with bacteria and zeolite treatment for NH4(+) removal was proposed to use glutamic acid as feedstock in photo-fermentation for efficient hydrogen production. Glutamic acid pretreated with acidogenic bacteria produces soluble metabolite products. After zeolite treatment, the acidulated solution, which mainly contains acetate, butyrate, and NH4(+), shows a decrease in NH4(+) concentration from 36.7mM to 3.2mM (NH4(+) removal efficiency of 91.1%). After NH4(+) removal, the treated solution is incubated with photosynthetic bacteria, exhibiting a maximum hydrogen yield of 292.9mL/g(-glutamic acid) during photo-fermentation. The residual solution from photo-fermentation is reused by methanogenic bacteria to produce a maximum methane yield of 102.7mL/g. The heating value conversion efficiency from glutamic acid to gas fuel significantly increases from 18.9% during photo-fermentation to 40.9% in the combined photo-fermentation and methanogenesis process. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2017-12-01

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

  3. Astrocyte VAMP3 vesicles undergo Ca2+-independent cycling and modulate glutamate transporter trafficking

    Science.gov (United States)

    Li, Dongdong; Hérault, Karine; Zylbersztejn, Kathleen; Lauterbach, Marcel A; Guillon, Marc; Oheim, Martin; Ropert, Nicole

    2015-01-01

    Key points Mouse cortical astrocytes express VAMP3 but not VAMP2. VAMP3 vesicles undergo Ca2+-independent exo- and endocytotic cycling at the plasma membrane. VAMP3 vesicle traffic regulates the recycling of plasma membrane glutamate transporters. cAMP modulates VAMP3 vesicle cycling and glutamate uptake. Abstract Previous studies suggest that small synaptic-like vesicles in astrocytes carry vesicle-associated vSNARE proteins, VAMP3 (cellubrevin) and VAMP2 (synaptobrevin 2), both contributing to the Ca2+-regulated exocytosis of gliotransmitters, thereby modulating brain information processing. Here, using cortical astrocytes taken from VAMP2 and VAMP3 knock-out mice, we find that astrocytes express only VAMP3. The morphology and function of VAMP3 vesicles were studied in cultured astrocytes at single vesicle level with stimulated emission depletion (STED) and total internal reflection fluorescence (TIRF) microscopies. We show that VAMP3 antibodies label small diameter (∼80 nm) vesicles and that VAMP3 vesicles undergo Ca2+-independent exo-endocytosis. We also show that this pathway modulates the surface expression of plasma membrane glutamate transporters and the glutamate uptake by astrocytes. Finally, using pharmacological and optogenetic tools, we provide evidence suggesting that the cytosolic cAMP level influences astrocytic VAMP3 vesicle trafficking and glutamate transport. Our results suggest a new role for VAMP3 vesicles in astrocytes. PMID:25864578

  4. MADP, a salidroside analog, protects hippocampal neurons from glutamate induced apoptosis.

    Science.gov (United States)

    Xian, Hua; Zhao, Jing; Zheng, Yuan; Wang, Meihong; Huang, Jun; Wu, Bingxin; Sun, Cheng; Yang, Yumin

    2014-05-08

    To investigate the anti-apoptotic effect of MADP, an analog of salidroside, against glutamate induced apoptosis in the cultured rat hippocampal neurons. Cytotoxicity was determined by the MTT method and lactate dehydrogenase release to the medium. Cell apoptosis was evaluated by Hoechst 33342 staining, TUNEL assay and flow cytometric analysis. Western blotting was applied for detecting protein levels of cellular signaling molecules. Our results showed that glutamate exposure significantly induces cell apoptosis, whereas the pretreatment of salidroside or MADP remarkably improves cell viability. Most importantly, the anti-apoptotic effect of MADP against glutamate insult is superior to salidroside. To explore the involved mechanisms, we measured some pro-apoptotic and anti-apoptotic protein levels, and several cell survival signaling pathways were analyzed as well. No visible alterations in Bcl-2 and Bax protein levels were observed by MADP or salidroside. Akt and JNK phosphorylation was robustly stimulated by MADP in the glutamate-treated neurons. Salidroside treatment results in a slight activation in Akt, while no significant alteration in JNK activity was observed. MADP exhibits higher capacity to attenuate glutamate induced cell apoptosis in the cultured rat hippocampal neurons, suggesting that MADP might be a better candidate than salidroside for developing novel drugs treating neuron loss associated disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Opening of pannexin- and connexin-based channels increases the excitability of nodose ganglion sensory neurons.

    Science.gov (United States)

    Retamal, Mauricio A; Alcayaga, Julio; Verdugo, Christian A; Bultynck, Geert; Leybaert, Luc; Sáez, Pablo J; Fernández, Ricardo; León, Luis E; Sáez, Juan C

    2014-01-01

    Satellite glial cells (SGCs) are the main glia in sensory ganglia. They surround neuronal bodies and form a cap that prevents the formation of chemical or electrical synapses between neighboring neurons. SGCs have been suggested to establish bidirectional paracrine communication with sensory neurons. However, the molecular mechanism involved in this cellular communication is unknown. In the central nervous system (CNS), astrocytes present connexin43 (Cx43) hemichannels and pannexin1 (Panx1) channels, and the opening of these channels allows the release of signal molecules, such as ATP and glutamate. We propose that these channels could play a role in glia-neuron communication in sensory ganglia. Therefore, we studied the expression and function of Cx43 and Panx1 in rat and mouse nodose-petrosal-jugular complexes (NPJcs) using confocal immunofluorescence, molecular and electrophysiological techniques. Cx43 and Panx1 were detected in SGCs and in sensory neurons, respectively. In the rat and mouse, the electrical activity of vagal nerve increased significantly after nodose neurons were exposed to a Ca(2+)/Mg(2+)-free solution, a condition that increases the open probability of Cx hemichannels. This response was partially mimicked by a cell-permeable peptide corresponding to the last 10 amino acids of Cx43 (TAT-Cx43CT). Enhanced neuronal activity was reduced by Cx hemichannel, Panx1 channel and P2X7 receptor blockers. Moreover, the role of Panx1 was confirmed in NPJc, because in those from Panx1 knockout mice showed a reduced increase of neuronal activity induced by Ca(2+)/Mg(2+)-free extracellular conditions. The data suggest that Cx hemichannels and Panx channels serve as paracrine communication pathways between SGCs and neurons by modulating the excitability of sensory neurons.

  6. Glutamate stimulation of (/sup 3/H)dopamine release from dissociated cell cultures of rat ventral mesencephalon

    Energy Technology Data Exchange (ETDEWEB)

    Mount, H.; Welner, S.; Quirion, R.; Boksa, P.

    1989-04-01

    In dissociated cell cultures of fetal rat ventral mesencephalon preloaded with (3H)dopamine, glutamate (10(-5)-10(-3) M) stimulated the release of (3H)dopamine. Glutamate stimulation of (3H)dopamine release was Ca2+ dependent and was blocked by the glutamate antagonist, cis-2,3-piperidine dicarboxylic acid. Glutamate stimulation of (3H)dopamine release was not due to glutamate neurotoxicity because (1) glutamate did not cause release of a cytosolic marker, lactate dehydrogenase, and (2) preincubation of cultures with glutamate did not impair subsequent ability of the cells to take up or release (3H)dopamine. Thus, these dissociated cell cultures appear to provide a good model system to characterize glutamate stimulation of dopamine release. Release of (3H)dopamine from these cultures was stimulated by veratridine, an activator of voltage-sensitive Na+ channels, and this stimulation was blocked by tetrodotoxin. However, glutamate-stimulated (3H)dopamine release was not blocked by tetrodotoxin or Zn2+. Substitution of NaCl in the extracellular medium by sucrose, LiCl, or Na2SO4 had no effect on glutamate stimulation of (3H)dopamine release; however, release was inhibited when NaCl was replaced by choline chloride or N-methyl-D-glucamine HCl. Glutamate-stimulated (3H)-dopamine release was well maintained (60-82% of control) in the presence of Co2+, which blocks Ca2+ action potentials, and was unaffected by the local anesthetic, lidocaine. These results are discussed in terms of the receptor and ionic mechanisms involved in the stimulation of dopamine release by excitatory amino acids.

  7. Elevated systemic glutamic acid level in the non-obese diabetic mouse is Idd linked and induces beta cell apoptosis.

    Science.gov (United States)

    Banday, Viqar Showkat; Lejon, Kristina

    2017-02-01

    Although type 1 diabetes (T1D) is a T-cell-mediated disease in the effector stage, the mechanism behind the initial beta cell assault is less understood. Metabolomic differences, including elevated levels of glutamic acid, have been observed in patients with T1D before disease onset, as well as in pre-diabetic non-obese diabetic (NOD) mice. Increased levels of glutamic acid damage both neurons and beta cells, implying that this could contribute to the initial events of T1D pathogenesis. We investigated the underlying genetic factors and consequences of the increased levels of glutamic acid in NOD mice. Serum glutamic acid levels from a (NOD×B6)F2 cohort (n = 182) were measured. By genome-wide and Idd region targeted microsatellite mapping, genetic association was detected for six regions including Idd2, Idd4 and Idd22. In silico analysis of potential enzymes and transporters located in and around the mapped regions that are involved in glutamic acid metabolism consisted of alanine aminotransferase, glutamic-oxaloacetic transaminase, aldehyde dehydrogenase 18 family, alutamyl-prolyl-tRNA synthetase, glutamic acid transporters GLAST and EAAC1. Increased EAAC1 protein expression was observed in lysates from livers of NOD mice compared with B6 mice. Functional consequence of the elevated glutamic acid level in NOD mice was tested by culturing NOD. Rag2-/- Langerhans' islets with glutamic acid. Induction of apoptosis of the islets was detected upon glutamic acid challenge using TUNEL assay. Our results support the notion that a dysregulated metabolome could contribute to the initiation of T1D. We suggest that targeting of the increased glutamic acid in pre-diabetic patients could be used as a potential therapy. © 2016 John Wiley & Sons Ltd.

  8. Aldrin-induced stimulation of locomotor activity and brain regional glutamate.

    Science.gov (United States)

    Jamaluddin, S; Poddar, M K

    2001-05-01

    Single administration of aldrin (2-10 mg/kg) to adult male albino rats (120-130 g) enhanced locomotor activity (LA), with the maximum effect reached 2 h after treatment. The measurement of steady state levels of glutamate, glutamine and the activities of their metabolizing enzymes in different regions of the brains of rats treated with aldrin under its nontolerant condition showed that aldrin enhanced the activity of the neuronal glutamate system in the cerebral cortex, cerebellum and hypothalamus. Moreover, treatment with the glutamatergic NMDA receptor antagonist D,L-2-amino-7-phosphonoheptanoic acid, in the absence and presence of aldrin, reduced the LA of control rats and attenuated the aldrin-induced increase in LA of treated rats. These results suggest that aldrin-induced activation of the central glutamate system may be a cause of stimulation of LA with aldrin under its nontolerant condition.

  9. Glutamate Imaging (GluCEST) Lateralizes Epileptic Foci in Non-Lesional Temporal Lobe Epilepsy

    Science.gov (United States)

    Davis, Kathryn Adamiak; Nanga, Ravi Prakash Reddy; Das, Sandhitsu; Chen, Stephanie H.; 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 patients. MR spectra, available in a subset of patients and controls, corroborated the GluCEST findings. Hippocampal volumes were not significantly different between hemispheres. GluCEST allowed for high-resolution functional imaging of brain glutamate and has potential to identify the epileptic focus in patients previously deemed non-lesional. This method may lead to improved clinical outcomes for temporal lobe epilepsy as well as other localization-related epilepsies. PMID:26468323

  10. 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

    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 data...... suggest that the permeability depends on the conformational equilibrium of the EAAT1. At positive potentials and in the presence of Na(+) and glutamate, the pore is enlarged and water and urea penetrate more readily. The L(p) was larger when measured with urea or glycerol as osmolytes as compared...... with mannitol. Apparently, the properties of the pore are not uniform along its length. The outer section may accommodate urea and glycerol in an osmotically active form, giving rise to larger water fluxes. The physiological role of EAAT1 for water homeostasis in the central nervous system is discussed....

  11. Riluzole protects against glutamate-induced slowing of neurofilament axonal transport.

    LENUS (Irish Health Repository)

    Stevenson, Alison

    2009-04-24

    Riluzole is the only drug approved for the treatment of amyotrophic lateral sclerosis (ALS) but its precise mode of action is not properly understood. Damage to axonal transport of neurofilaments is believed to be part of the pathogenic mechanism in ALS and this has been linked to defective glutamate handling and increased phosphorylation of neurofilament side-arm domains. Here, we show that riluzole protects against glutamate-induced slowing of neurofilament transport. Protection is associated with decreased neurofilament side-arm phosphorylation and inhibition of the activities of two neurofilament kinases, ERK and p38 that are activated in ALS. Thus, the anti-glutamatergic properties of riluzole include protection against glutamate-induced changes to neurofilament phosphorylation and transport.

  12. Asynchronous presynaptic glutamate release enhances neuronal excitability during the post-spike refractory period.

    Science.gov (United States)

    Iremonger, Karl J; Bains, Jaideep S

    2016-02-15

    Many excitatory synapses in the brain release glutamate with both synchronous and asynchronous components. Immediately following an action potential, neurons display a reduced excitability due to the post-spike afterhyperpolarization (AHP). This gives rise to a relative refractory period. When an action potential is evoked by glutamate synaptic input possessing asynchronous release, the delayed glutamate release events act to depolarize the neuron during the AHP and overcome the relative refractory period. These results demonstrate a new role for asynchronous release in regulating post-spike excitability and the relative refractory period in central neurons. Post-spike afterhyperpolarizations (AHPs) functionally inhibit neuronal excitability for tens to hundreds of milliseconds following each action potential. This imposes a relative refractory period during which synaptic excitation is less effective at evoking spikes. Here we asked whether some synapses have mechanisms in place that allow them to overcome the AHP and drive spiking in target cells during this period of reduced excitability. We examined glutamate synapses onto oxytocin and vasopressin neurons in the paraventricular nucleus of the hypothalamus. These synapses can display pronounced asynchronous glutamate release following a single presynaptic spike, with the time course of release being similar to that of the post-spike AHP. To test whether asynchronous release is more effective at overcoming the relative refractory period, we evoked a single action potential with either a brief synchronous depolarization or an asynchronous potential and then assessed excitability at multiple time points following the spike. Neurons receiving asynchronous depolarizing synaptic inputs had a shorter relative refractory period than those receiving synchronous depolarizations. Our data demonstrate that synapses releasing glutamate in an asynchronous and delayed manner are ideally adapted to counter the AHP. By

  13. Evidence of alterations in brain structure and antioxidant status following 'low-dose' monosodium glutamate ingestion.

    Science.gov (United States)

    Onaolapo, Olakunle James; Onaolapo, Adejoke Yetunde; Akanmu, M A; Gbola, Olayiwola

    2016-09-01

    The study investigated the effects of low dose monosodium glutamate (MSG) on the brain, with a view to providing information on its effects on neuronal morphology and antioxidant status in mice. Sixty male mice (20-22 g) were divided into six groups of ten animals each. Vehicle (distilled water), a standard (l-glutamate at 10mg/kg body weight) or MSG (10, 20, 40 and 80mg/kg body weight) were administered orally for 28days. Sections of the cerebrum, hippocampus and cerebellum were processed and stained using hematoxylin and eosin, examined under a microscope and captured images analysed. Plasma and brain levels of glutamate, glutamine, and antioxidants were assayed. Data obtained were analysed using descriptive and inferential statistics. MSG ingestion did not significantly alter body weight. Relative brain weight increased at 40 and 80mg/kg compared to vehicle. Histological and histomorphometric changes consistent with neuronal damage were seen in the cerebrum, hippocampus and cerebellum at 40 and 80mg/kg. Plasma glutamate and glutamine assay showed significant increase at 40 and 80mg/kg while no significant difference in total brain glutamate or glutamine levels were seen. Levels of brain superoxide dismutase and catalase decreased with increasing doses of MSG, while nitric oxide (NO) increased at these doses. The study showed morphological alterations consistent with neuronal injury, biochemical changes of oxidative stress and a rise in plasma glutamate and glutamine. These data therefore still support the need for cautious consideration in the indiscriminate use of MSG as a dietary flavor enhancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Neonatal exposure to monosodium glutamate results in dysmorphology of orofacial lower motor neurons.

    Science.gov (United States)

    Foran, Lindsey; Kupelian, Chloe; Laroia, Swati; Esper, Jeffrey; Kulesza, Randy Joseph

    2017-06-14

    Glutamate is the most abundant excitatory neurotransmitter in the central nervous system, and is stored and released by both neurons and astrocytes. Despite the important role of glutamate as a neurotransmitter, high levels of extracellular glutamate can result in excitotoxicity and apoptosis. Monosodium glutamate (MSG) is a naturally occurring sodium salt of glutamic acid that is used as a flavor enhancer in many processed foods. Neonatal exposure to MSG has been shown to result in neurodegeneration in several forebrain regions, characterized by neuronal loss and neuroendocrine abnormalities. However, the brainstem effects of neonatal monosodium glutamate exposure have not been investigated. It is therefore hypothesized that MSG exposure during the early postnatal period would impact brainstem lower motor neurons involved in feeding behavior. The effect of neonatal MSG exposure on brainstem lower motor neurons was investigated by exposing rat pups to either 4mg/g MSG or saline from postnatal day (P) 4 through 10. On P28, brains were preserved by vascular perfusion with fixative, frozen sectioned and stained for Nïssl substance. The number, size and shape of brainstem motor neurons were compared between MSG and saline-exposed animals. MSG exposure had no impact on the total number of neurons in the nuclei examined. However, MSG exposure was associated with a significant increase in the number of round somata in both the trigeminal and facial nuclei. Furthermore, MSG exposure resulted in significantly smaller neurons in all motor nuclei examined. These results suggest that neonatal exposure to MSG impacts the development of brainstem lower motor neurons which may impact feeding and swallowing behaviors in young animals.

  15. 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.

  16. Towards a glutamate hypothesis of depression: an emerging frontier of neuropsychopharmacology for mood disorders.

    Science.gov (United States)

    Sanacora, Gerard; Treccani, Giulia; Popoli, Maurizio

    2012-01-01

    Half a century after the first formulation of the monoamine hypothesis, compelling evidence implies that long-term changes in an array of brain areas and circuits mediating complex cognitive-emotional behaviors represent the biological underpinnings of mood/anxiety disorders. A large number of clinical studies suggest that pathophysiology is associated with dysfunction of the predominant glutamatergic system, malfunction in the mechanisms regulating clearance and metabolism of glutamate, and cytoarchitectural/morphological maladaptive changes in a number of brain areas mediating cognitive-emotional behaviors. Concurrently, a wealth of data from animal models have shown that different types of environmental stress enhance glutamate release/transmission in limbic/cortical areas and exert powerful structural effects, inducing dendritic remodeling, reduction of synapses and possibly volumetric reductions resembling those observed in depressed patients. Because a vast majority of neurons and synapses in these areas and circuits use glutamate as neurotransmitter, it would be limiting to maintain that glutamate is in some way 'involved' in mood/anxiety disorders; rather it should be recognized that the glutamatergic system is a primary mediator of psychiatric pathology and, potentially, also a final common pathway for the therapeutic action of antidepressant agents. A paradigm shift from a monoamine hypothesis of depression to a neuroplasticity hypothesis focused on glutamate may represent a substantial advancement in the working hypothesis that drives research for new drugs and therapies. Importantly, despite the availability of multiple classes of drugs with monoamine-based mechanisms of action, there remains a large percentage of patients who fail to achieve a sustained remission of depressive symptoms. The unmet need for improved pharmacotherapies for treatment-resistant depression means there is a large space for the development of new compounds with novel mechanisms

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

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

    2017-02-15

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

  19. Metabolic pathways of ammoniogenesis in the shrimp Crangon crangon L.: possible role of glutamate dehydrogenase.

    Science.gov (United States)

    Batrel, Y; Regnault, M

    1985-01-01

    The oxidative deamination of glutamate by glutamate dehydrogenase (GDH) was determined in crude homogenates of the shrimp Crangon crangon. The GDH activity of whole shrimps (1.192 +/- 0.164 UI/g wet wt and 0.032 +/- 0.004 UI mg protein) (+/- SD) is probably sufficient to account for all the ammonia excretion of this species. Starvation markedly influenced GDH activity. A 50% decrease of GDH activity was observed following 7 days of fasting but subsequently no further decrease in GDH activity was noticed during starvation up to a maximum of 17 days.

  20. The Monosodium Glutamate Story: The Commercial Production of MSG and Other Amino Acids

    Science.gov (United States)

    Ault, Addison

    2004-03-01

    Examples of the industrial synthesis of pure amino acids are presented. The emphasis is on the synthesis of ( S )-glutamic acid and, to a lesser extent, ( S )-lysine and ( R,S )-methionine. These amino acids account for about 90% of the total world production of amino acids, ( S )-glutamic acid being used as a flavor-enhancing additive (MSG) for the human diet, and ( S )-lysine and ( R,S )-methionine as supplements for the feeding of domestic animals. Examples include chemical, enzymatic, and fermentation synthesis, and two clever continuous processes for the resolution of enantiomers. See Featured Molecules .

  1. Synthesis and pharmacological evaluation of conformationally constrained glutamic acid higher homologues.

    Science.gov (United States)

    Tamborini, Lucia; Cullia, Gregorio; Nielsen, Birgitte; De Micheli, Carlo; Conti, Paola; Pinto, Andrea

    2016-11-15

    Homologation of glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. In the present work, starting from two potent and selective unnatural amino acids previously developed by us, we investigated the effects on the activity/selectivity profile produced by a further increase in the distance between the amino acidic moiety and the distal carboxylate group. Interestingly, the insertion of an aromatic ring as a spacer produced a low micromolar affinity NMDA ligand that might represent a lead for the development of a new class of NMDA antagonists. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Synthesis and pharmacological evaluation of conformationally constrained glutamic acid higher homologues

    DEFF Research Database (Denmark)

    Tamborini, Lucia; Cullia, Gregorio; Nielsen, Birgitte

    2016-01-01

    Homologation of glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. In the present work, starting from two potent and selective unnatural amino acids previously developed by us, we...... investigated the effects on the activity/selectivity profile produced by a further increase in the distance between the amino acidic moiety and the distal carboxylate group. Interestingly, the insertion of an aromatic ring as a spacer produced a low micromolar affinity NMDA ligand that might represent a lead...

  3. Effects of glutamate receptor activation on NG2-glia in the rat optic nerve.

    Science.gov (United States)

    Hamilton, Nicola; Hubbard, Paul S; Butt, Arthur M

    2009-02-01

    NG2-glia are a substantial population of cells in the central nervous system (CNS) that can be identified by their specific expression of the NG2 chondroitin sulphate (CSPG). NG2-glia can generate oligodendrocytes, but it is unlikely this is their only function; indeed, they may be multipotent neural stem cells. Moreover, NG2-glia are a highly reactive cell type and a major function is to help form the axon growth inhibitory glial scar in response to CNS injury. The factors that regulate these diverse behaviours of NG2-glia are not fully resolved, but NG2-glia express receptors to the neurotransmitter glutamate, which has known potent effects on other glia. Here, we have examined the actions of glutamate receptor activation on NG2-glia in the rat optic nerve, a typical CNS white matter tract that does not contain neuronal cell bodies. Glutamate induces an increase in [Ca(2+)](i) in immuno-identified NG2-glia in situ and in vitro. In addition, we examined the effects of glutamate receptor activation in vivo by focal injection of the glutamate receptor agonist kainate into the optic nerve; saline was injected in controls. Changes in glial and axonal function were determined at 7 days post injection (dpi), by immunohistochemistry and electrophysiological measurement of the compound action potential (CAP). Injection of kainate resulted in a highly localized 'injury response' in NG2-glia, marked by dense labelling for NG2 at the lesion site, as compared to astrocytes, which displayed a more extensive reactive astrogliosis. Furthermore, injection of kainate resulted in an axonal conduction block. These glial and axonal changes were not observed following injection of saline vehicle. In addition, we provide evidence that endogenous glutamate induces calcium-dependent phosphorylation of extracellular signal-regulated kinases (ERK1/2), which may provide a potential mechanism by which glutamate-mediated changes in raised intracellular calcium could regulate the observed

  4. AUTOANTIBODIES TO GLUTAMIC ACID DECARBOXYLASE AS A PATHOGENETIC MARKER OF TYPE I DIABETES MELLITUS

    Directory of Open Access Journals (Sweden)

    N. V. Piven

    2011-01-01

    Full Text Available Abstract. A new method of enzyme-linked immunosorbent assay (in solid-phase ELISA format has been developed to determine concentrations of autoantibodies to glutamic acid decarboxylase, as well as an evidencebased methodology is proposed for its medical implications, as a quantitative pathogenetic predictive marker of autoimmune diagnostics in type 1 diabetes mellitus. This technique could be implied for serial production of diagnostic reagent kits, aimed for detection of autoantibodies to glutamic acid decarboxylase by means of ELISA approach. (Med. Immunol., 2011, vol. 13, N 2-3, pp 257-260

  5. Capture ELISA for IgM antibodies against Plasmodium falciparum glutamate rich protein

    DEFF Research Database (Denmark)

    Dziegiel, Morten Hanefeld; Borre, M B; Petersen, E

    1992-01-01

    This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta-galactos......This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta...

  6. Magnetic-Resonance Studies of the Geometry of Bound Substrate, Coenzyme and Activator on Bovine-Liver Glutamate Dehydrogenase

    NARCIS (Netherlands)

    Zantema, Alt; de Smet, Marie-José; Robillard, George T.

    ADP and ATP with a spin-label linked to the terminal phosphate are activators of glutamate dehydrogenase and bind to the same site as the activator ADP. There is hardly any interaction with the coenzyme site. Glutamate dehydrogenase can be modified with a ketone spin-label at a site in the active

  7. Glutamate in dorsolateral prefrontal cortex and auditory verbal hallucinations in patients with schizophrenia : A (1)H MRS study

    NARCIS (Netherlands)

    Curcic-Blake, Branisalava; Bais, Leonie; Sibeijn-Kuiper, Anita; Pijnenborg, Hendrika Maria; Knegtering, Henderikus; Liemburg, Edith; Aleman, André

    2017-01-01

    Purpose: Glutamatergic models of psychosis propose that dysfunction of N-methyl-D-aspartate (NMDA) receptors, and associated excess of glutamate, may underlie psychotic experiences in people with schizophrenia. However, little is known about the specific relation between glutamate and auditory

  8. On-chip microfluidic systems for determination of L-glutamate based on enzymatic recycling of substrate

    DEFF Research Database (Denmark)

    Laiwattanapaisal, W.; Yakovleva, J.; Bengtsson, Martin

    2009-01-01

    Two microfluidic systems have been developed for specific analysis of L-glutamate in food based on substrate recycling fluorescence detection. L-glutamate dehydrogenase and a novel enzyme, D-phenylglycine aminotransferase, were covalently immobilized on (i) the surface of silicon microchips conta...

  9. Silicon Wafer-Based Platinum Microelectrode Array Biosensor for Near Real-Time Measurement of Glutamate in Vivo

    Directory of Open Access Journals (Sweden)

    Nigel T. Maidment

    2008-08-01

    Full Text Available Using Micro-Electro-Mechanical-Systems (MEMS technologies, we have developed silicon wafer-based platinum microelectrode arrays (MEAs modified with glutamate oxidase (GluOx for electroenzymatic detection of glutamate in vivo. These MEAs were designed to have optimal spatial resolution for in vivo recordings. Selective detection of glutamate in the presence of the electroactive interferents, dopamine and ascorbic acid, was attained by deposition of polypyrrole and Nafion. The sensors responded to glutamate with a limit of detection under 1μM and a sub-1-second response time in solution. In addition to extensive in vitro characterization, the utility of these MEA glutamate biosensors was also established in vivo. In the anesthetized rat, these MEA glutamate biosensors were used for detection of cortically-evoked glutamate release in the ventral striatum. The MEA biosensors also were applied to the detection of stress-induced glutamate release in the dorsal striatum of the freely-moving rat.

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

    NARCIS (Netherlands)

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

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

  11. A density functional and quantum Monte Carlo study of glutamic acid in vacuo and in a dielectric continuum medium

    NARCIS (Netherlands)

    Floris, F.; Filippi, Claudia; Amovilli, C.

    2012-01-01

    We present density functional theory (DFT) and quantum Monte Carlo (QMC) calculations of the glutamic acid and glutamate ion in vacuo and in various dielectric continuum media within the polarizable continuum model (PCM). In DFT, we employ the integral equation formalism variant of PCM while, in

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  13. Characterization of glutamate-induced formation of N- acylphosphatidylethanolamine and N-acylethanolamine in cultured neocortical neurons

    DEFF Research Database (Denmark)

    Hansen, Harald S.; Lauritzen, L.; Strand, A.M.

    1997-01-01

    -induced formation was seen in 2-day-old cultures, whereas glutamate induced a pronounced formation in 6-day-old cultures. The calcium ionophore A23187 (2 µM) stimulated, within 2 h, formation of NAPE in 2-day-old cultures (fourfold) as well as in 6-day-old cultures (eightfold). Glutamate exerted its effect via NMDA...

  14. Age-related changes in glutamate release in the CA3 and dentate gyrus of the rat hippocampus

    Science.gov (United States)

    Stephens, Michelle L.; Quintero, Jorge E.; Pomerleau, Francois; Huettl, Peter; Gerhardt, Greg A.

    2012-01-01

    The present studies employed a novel microelectrode array recording technology to study glutamate release and uptake in the dentate gyrus, CA3 and CA1 hippocampal subregions in anesthetized young, late-middle aged and aged male Fischer 344 rats. The mossy fiber terminals in CA3 showed a significantly decreased amount of KCl-evoked glutamate release in aged rats compared to both young and late-middle-aged rats. Significantly more KCl-evoked glutamate release was seen from perforant path terminals in the DG of late-middle-aged rats compared young and aged rats. The DG of aged rats developed an increased glutamate uptake rate compared to the DG of young animals, indicating a possible age-related change in glutamate regulation to deal with increased glutamate release that occurred in late-middle age. No age-related changes in resting levels of glutamate were observed in the DG, CA3 and CA1. Taken together, these data support dynamic changes to glutamate regulation during aging in subregions of the mammalian hippocampus that are critical for learning and memory. PMID:19535175

  15. Oligomers of Amyloid β Prevent Physiological Activation of the Cellular Prion Protein-Metabotropic Glutamate Receptor 5 Complex by Glutamate in Alzheimer Disease.

    Science.gov (United States)

    Haas, Laura T; Strittmatter, Stephen M

    2016-08-12

    The dysfunction and loss of synapses in Alzheimer disease are central to dementia symptoms. We have recently demonstrated that pathological Amyloid β oligomer (Aβo) regulates the association between intracellular protein mediators and the synaptic receptor complex composed of cellular prion protein (PrP(C)) and metabotropic glutamate receptor 5 (mGluR5). Here we sought to determine whether Aβo alters the physiological signaling of the PrP(C)-mGluR5 complex upon glutamate activation. We provide evidence that acute exposure to Aβo as well as chronic expression of familial Alzheimer disease mutant transgenes in model mice prevents protein-protein interaction changes of the complex induced by the glutamate analog 3,5-dihydroxyphenylglycine. We further show that 3,5-dihydroxyphenylglycine triggers the phosphorylation and activation of protein-tyrosine kinase 2-β (PTK2B, also referred to as Pyk2) and of calcium/calmodulin-dependent protein kinase II in wild-type brain slices but not in Alzheimer disease transgenic brain slices or wild-type slices incubated with Aβo. This study further distinguishes two separate Aβo-dependent signaling cascades, one dependent on extracellular Ca(2+) and Fyn kinase activation and the other dependent on the release of Ca(2+) from intracellular stores. Thus, Aβo triggers multiple distinct PrP(C)-mGluR5-dependent events implicated in neurodegeneration and dementia. We propose that targeting the PrP(C)-mGluR5 complex will reverse aberrant Aβo-triggered states of the complex to allow physiological fluctuations of glutamate signaling. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Nonsynonymous single nucleotide polymorphisms in human tas1r1, tas1r3, and mGluR1 and individual taste sensitivity to glutamate

    National Research Council Canada - National Science Library

    Raliou, Mariam; Wiencis, Anna; Pillias, Anne-Marie; Planchais, Aurore; Eloit, Corinne; Boucher, Yves; Trotier, Didier; Montmayeur, Jean-Pierre; Faurion, Annick

    2009-01-01

    .... Our objective was to study possible relations between phenotype (sensitivity to glutamate) and genotype (polymorphisms in candidate glutamate taste receptors tas1r1, tas1r3, mGluR4, and mGluR1...

  17. Immunohistochemical localization of group I and II metabotropic glutamate receptors in control and amyotrophic lateral sclerosis human spinal cord: upregulation in reactive astrocytes

    NARCIS (Netherlands)

    Aronica, E.; Catania, M. V.; Geurts, J.; Yankaya, B.; Troost, D.

    2001-01-01

    Excitotoxicity, which is mediated by the excessive activation of glutamate receptors, has been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). There is substantial information about the distribution and function of ionotropic glutamate receptors in the spinal cord, although

  18. 7T Proton Magnetic Resonance Spectroscopy of Gamma-Aminobutyric Acid, Glutamate, and Glutamine Reveals Altered Concentrations in Patients With Schizophrenia and Healthy Siblings

    NARCIS (Netherlands)

    Thakkar, Katharine N; Rösler, Lara; Wijnen, Jannie P; Boer, Vincent O.; Klomp, Dennis W J; Cahn, Wiepke; Kahn, René S; Neggers, Sebastiaan F W

    BACKGROUND: The N-methyl-D-aspartate receptor hypofunction model of schizophrenia predicts dysfunction in both glutamatergic and gamma-aminobutyric acidergic (GABAergic) transmission. We addressed this hypothesis by measuring GABA, glutamate, glutamine, and the sum of glutamine plus glutamate

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

    Directory of Open Access Journals (Sweden)

    Jeong-Woong Park

    2017-05-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    ) and related this to the expression of CGRP and its receptor in rhesus trigeminal ganglion. Pituitary adenylate cyclase-activating polypeptide (PACAP) and glutamate were examined and related to the CGRP system. Furthermore, we examined if the trigeminal ganglion is protected by the blood-brain barrier (BBB......), and the distribution of PACAP and glutamate in rhesus and rat TG. Evans blue was used to examine large molecule penetration into the rat TG. High receptor binding densities were found in rhesus TG. Immunofluorescence revealed expression of CGRP, CLR and RAMP1 in trigeminal cells. CGRP positive neurons expressed PACAP...... but not glutamate. Some neurons expressing CLR and RAMP1 co-localized with glutamate. Evans blue revealed that the TG is not protected by BBB. This study demonstrates CGRP receptor binding sites and expression of the CGRP receptor in rhesus and rat TG. The expression pattern of PACAP and glutamate suggests...

  1. Poly(glutamic acid) nanofibre modified glassy carbon electrode: Characterization by atomic force microscopy, voltammetry and electrochemical impedance

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Daniela Pereira; Zanoni, Maria Valnice Boldrin; Bergamini, Marcio Fernando [Departamento de Quimica Analitica, Instituto de Quimica, Universidade Estadual Paulista, Caixa Postal 355, 14800-900 Araraquara, S.P. (Brazil); Chiorcea-Paquim, Ana-Maria; Diculescu, Victor Constantin [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra (Portugal); Oliveira Brett, Ana-Maria [Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra (Portugal)], E-mail: brett@ci.uc.pt

    2008-04-20

    Glassy carbon electrodes (GCE) were modified with poly(glutamic acid) acid films prepared using three different procedures: glutamic acid monomer electropolymerization (MONO), evaporation of poly(glutamic acid) (PAG) and evaporation of a mixture of poly(glutamic acid)/glutaraldehyde (PAG/GLU). All three films showed good adherence to the electrode surface. The performance of the modified GCE was investigated by cyclic voltammetry and differential pulse voltammetry, and the films were characterized by atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). The three poly(glutamic acid) modified GCEs were tested using the electrochemical oxidation of ascorbic acid and a decrease of the overpotential and the improvement of the oxidation peak current was observed. The PAG modified electrode surfaces gave the best results. AFM morphological images showed a polymeric network film formed by well-defined nanofibres that may undergo extensive swelling in solution, allowing an easier electron transfer and higher oxidation peaks.

  2. Astrocytic energy metabolism and glutamate formation--relevance for 13C-NMR spectroscopy and importance of cytosolic/mitochondrial trafficking.

    Science.gov (United States)

    Hertz, Leif

    2011-12-01

    Glutamate plays a double role in (13)C-nuclear magnetic resonance (NMR) spectroscopic determination of glucose metabolism in the brain. Bidirectional exchange between initially unlabeled glutamate and labeled α-ketoglutarate, formed from pyruvate via pyruvate dehydrogenase (PDH), indicates the rate of energy metabolism in the tricarboxylic acid (V(TCA)) cycle in neurons (V(PDH, n)) and, with additional computation, also in astrocytes (V(PDH, g)), as confirmed using the astrocyte-specific substrate [(13)C]acetate. Formation of new molecules of glutamate during increased glutamatergic activity occurs only in astrocytes by combined pyruvate carboxylase (V(PC)) and astrocytic PDH activity. V(PDH, g) accounts for ~15% of total pyruvate metabolism in the brain cortex, and V(PC) accounts for another ~10%. Since both PDH-generated and PC-generated pyruvates are needed for glutamate synthesis, ~20/25 (80%) of astrocytic pyruvate metabolism proceed via glutamate formation. Net transmitter glutamate [γ-aminobutyric acid (GABA)] formation requires transfer of newly synthesized α-ketoglutarate to the astrocytic cytosol, α-ketoglutarate transamination to glutamate, amidation to glutamine, glutamine transfer to neurons, its hydrolysis to glutamate and glutamate release (or GABA formation). Glutamate-glutamine cycling, measured as glutamine synthesis rate (V(cycle)), also transfers previously released glutamate/GABA to neurons after an initial astrocytic accumulation and measures predominantly glutamate signaling. An empirically established ~1/1 ratio between glucose metabolism and V(cycle) may reflect glucose utilization associated with oxidation/reduction processes during glutamate production, which together with associated transamination processes are balanced by subsequent glutamate oxidation after cessation of increased signaling activity. Astrocytic glutamate formation and subsequent oxidative metabolism provide large amounts of adenosine triphosphate used for

  3. Derepression of nitrogenase by addition of malate to cultures of Rhodospirillum rubrum grown with glutamate as the carbon and nitrogen source.

    Science.gov (United States)

    Hoover, T R; Ludden, P W

    1984-07-01

    Rhodospirillum rubrum grown in continuous culture with glutamate as the sole fixed C and N source produced no nitrogenase, and the cultures were characterized by high extracellular ammonium concentrations. Addition of organic acids derepressed nitrogenase. Glutamate dehydrogenase, glutamine synthetase, glutamate synthase, malate dehydrogenase, nitrogenase, and ammonium were assayed before and after malate addition.

  4. Septal and hippocampal glutamate receptors modulate the output of acetylcholine in hippocampus : A microdialysis study

    NARCIS (Netherlands)

    Moor, E; Auth, F; DeBoer, P; Westerink, BHC

    In the present study, glutamate receptor agonists and antagonists were administered by retrograde microdialysis into either the medial septum/vertical limb of the diagonal band-(MS/vDB), or hippocampus, and the output of acetylcholine (ACh) was measured in the hippocampus by using intracerebral

  5. Capture ELISA for IgM antibodies against Plasmodium falciparum glutamate rich protein

    DEFF Research Database (Denmark)

    Dziegiel, M; Borre, Mette; Petersen, E

    1992-01-01

    This report describes a novel mu chain capture ELISA for the detection of IgM antibodies against a Plasmodium falciparum antigen. A fragment of the 220 kDa P. falciparum glutamate rich protein containing amino acid residues 489-1271 was expressed in E. coli as a recombinant chimeric beta-galactosidase...

  6. Utilization of barley or wheat bran to bioconvert glutamate to γ-aminobutyric acid (GABA).

    Science.gov (United States)

    Jin, Wen-Jie; Kim, Min-Ju; Kim, Keun-Sung

    2013-09-01

    This study deals with the utilization of agro-industrial wastes created by barley and wheat bran in the production of a value-added product, γ-aminobutyric acid (GABA). The simple and eco-friendly reaction requires no pretreatment or microbial fermentation steps but uses barley or wheat bran as an enzyme source, glutamate as a substrate, and pyridoxal 5'-phosphate (PLP) as a cofactor. The optimal reaction conditions were determined on the basis of the temperatures and times used for the decarboxylation reactions and the initial concentrations of barley or wheat bran, glutamate, and PLP. The optimal reactions produced 9.2 mM of GABA from 10 mM glutamate, yielding a 92% GABA conversion rate, when barley bran was used and 6.0 mM of GABA from 10 mM glutamate, yielding a 60% GABA conversion rate, when wheat bran was used. The results imply that barley bran is more efficient than wheat bran in the production of GABA. © 2013 Institute of Food Technologists®

  7. Glutamate dehydrogenase contributes to leucine sensing in the regulation of autophagy

    NARCIS (Netherlands)

    Lorin, Séverine; Tol, Marc J.; Bauvy, Chantal; Strijland, Anneke; Poüs, Christian; Verhoeven, Arthur J.; Codogno, Patrice; Meijer, Alfred J.

    2013-01-01

    Amino acids, leucine in particular, are known to inhibit autophagy, at least in part by their ability to stimulate MTOR-mediated signaling. Evidence is presented showing that glutamate dehydrogenase, the central enzyme in amino acid catabolism, contributes to leucine sensing in the regulation of

  8. Age-Dependent Glutamate Induction of Synaptic Plasticity in Cultured Hippocampal Neurons

    Science.gov (United States)

    Ivenshitz, Miriam; Segal, Menahem; Sapoznik, Stav

    2006-01-01

    A common denominator for the induction of morphological and functional plasticity in cultured hippocampal neurons involves the activation of excitatory synapses. We now demonstrate massive morphological plasticity in mature cultured hippocampal neurons caused by a brief exposure to glutamate. This plasticity involves a slow, 70%-80% increase in…

  9. Ciliary neurotrophic factor protects striatal neurons against excitotoxicity by enhancing glial glutamate uptake.

    Directory of Open Access Journals (Sweden)

    Corinne Beurrier

    Full Text Available Ciliary neurotrophic factor (CNTF is a potent neuroprotective cytokine in different animal models of glutamate-induced excitotoxicity, although its action mechanisms are still poorly characterized. We tested the hypothesis that an increased function of glial glutamate transporters (GTs could underlie CNTF-mediated neuroprotection. We show that neuronal loss induced by in vivo striatal injection of the excitotoxin quinolinic acid (QA was significantly reduced (by approximately 75% in CNTF-treated animals. In striatal slices, acute QA application dramatically inhibited corticostriatal field potentials (FPs, whose recovery was significantly higher in CNTF rats compared to controls (approximately 40% vs. approximately 7%, confirming an enhanced resistance to excitotoxicity. The GT inhibitor DL-threo-beta-benzyloxyaspartate greatly reduced FP recovery in CNTF rats, supporting the role of GT in CNTF-mediated neuroprotection. Whole-cell patch-clamp recordings from striatal medium spiny neurons showed no alteration of basic properties of striatal glutamatergic transmission in CNTF animals, but the increased effect of a low-affinity competitive glutamate receptor antagonist (gamma-D-glutamylglycine also suggested an enhanced GT function. These data strongly support our hypothesis that CNTF is neuroprotective via an increased function of glial GTs, and further confirms the therapeutic potential of CNTF for the clinical treatment of progressive neurodegenerative diseases involving glutamate overflow.

  10. ISOLATION AND CHARACTERIZATION OF THE RAT GENE ENCODING GLUTAMATE-DEHYDROGENASE

    NARCIS (Netherlands)

    DAS, AT; ARNBERG, AC; MALINGRE, H; MOERER, P; CHARLES, R; MOORMAN, AFM; LAMERS, WH

    1993-01-01

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

  11. Embryonic alcohol exposure promotes long-term effects on cerebral glutamate transport of adult zebrafish.

    Science.gov (United States)

    Baggio, Suelen; Mussulini, Ben Hur; de Oliveira, Diogo Losch; Zenki, Kamila Cagliari; Santos da Silva, Emerson; Rico, Eduardo Pacheco

    2017-01-01

    Ethanol is a widely consumed substance throughout the world. During development it can substantially damage the human fetus, whereas the developing brain is particularly vulnerable. The brain damage induced by prenatal alcohol exposure may lead to a variety of long-lasting behavioral and neurochemical problems. However, there are no data concerning the effects of developmental ethanol exposure on the glutamatergic system, where extracellular glutamate acts as signaling molecule. Here we investigated the effect of ethanol exposure for 2h (concentrations of 0.0%, 0.1%, 0.25%, 0.50%, and 1.00%) in embryos at 24h post-fertilization (hpf) by measuring the functionality of glutamate transporters in the brain of adult (4 months) zebrafish. However, ethanol 0.1%, 0.25% and 0.50% decreased transport of glutamate to 81.96%, 60.65% and 45.91% respectively, when compared with the control group. Interestingly, 1.00% was able to inhibit the transport activity to 68.85%. In response to the embryonic alcohol exposure, we found impairment in the function of cerebral glutamate transport in adult fish, contributing to long-term alteration in the homeostasis glutamatergic signaling. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Imaging increased glutamate in children with Sturge-Weber syndrome: association with epilepsy severity

    OpenAIRE

    Gertler, Tracy S.; Stack, Cynthia V.

    2017-01-01

    Investigators from Wayne State University studied a cohort of children with Sturge-Weber syndrome (SWS) and epilepsy using both glucose-based positron emission tomography (FDG-PET) to evaluate metabolic activity and proton magnetic resonance spectroscopic imaging (MRSI) to evaluate glutamate turnover.

  13. A new and efficient method for purification of poly-γ- glutamic acid ...

    African Journals Online (AJOL)

    The viscosity of the fermentation broth was determined by digital viscometer with spindle SP-2 at 25 oC. The concentrations of glucose and L-glutamate were analyzed with a biosensor equipped with both glucose oxidase and Lglutamate oxidase electrodes. The pigment in the fermentation liquid was scanned with a UV ...

  14. Lack of the Metabotropic Glutamate Receptor Subtype 7 Selectively Modulates Theta Rhythm and Working Memory

    Science.gov (United States)

    Holscher, Christian; Schmid, Susanne; Pilz, Peter K. D.; Sansig, Gilles; van der Putten, Herman; Plappert, Claudia F.

    2005-01-01

    Metabotropic glutamate receptors (mGluRs) are known to play a role in synaptic plasticity and learning. We have previously shown that mGluR7 deletion in mice produces a selective working memory (WM) impairment, while other types of memory such as reference memory remain unaffected. Since WM has been associated with Theta activity (6-12 Hz) in…

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

    African Journals Online (AJOL)

    Knapp CM, Mercado M, Markley TL, Crosby S, Ciraulo. DA, et al. Zonisamide decreases ethanol intake in rats and mice. Pharmacol Biochem Behav 2007; 87: 65-72. 17. McCool BA, Chappell AM. Persistent enhancement of ethanol drinking following a monosodium glutamate- substitution procedure in C57BL6/J and ...

  16. Extended studies on the effect of glutamate antagonists on ischemic CA-1 damage

    DEFF Research Database (Denmark)

    Diemer, Nils Henrik; Balchen, T; Bruhn, T

    1996-01-01

    Glutamate receptors are numerous on the ischemia vulnerable CA-1 pyramidal cells. Postischemic use of the AMPA antagonist NBQX has shown up to 80% protection against cell death. Three aspects of this were studied: In the first study, male Wistar rats were given NBQX (30 mg/kg x 3) either 20 hours...

  17. DPD epitope-specific glutamic acid decarboxylase GAD)65 autoantibodies in children with Type 1 diabetes

    Science.gov (United States)

    To study whether DPD epitope-specific glutamate decarboxylase autoantibodies are found more frequently in children with milder forms of Type 1 diabetes. We prospectively evaluated 75 children with new-onset autoimmune Type 1 diabetes, in whom we collected demographic, anthropometric and clinical dat...

  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

    technique, we present a method that is suitable for the in vivo investigation of the capacity of cellular uptake of glutamate. Using 14C-mannitol as reference, we measured the cellular extraction and the cell membrane permeability of the test substance 3H-D-aspartate in the corpus striatum of the rat brain...

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

    DEFF Research Database (Denmark)

    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 ...

  20. Metabolomic profiling of urinary changes in mice with monosodium glutamate-induced obesity

    Czech Academy of Sciences Publication Activity Database

    Pelantová, Helena; Bártová, Simona; Anýž, J.; Holubová, Martina; Železná, Blanka; Maletínská, Lenka; Novák, D.; Lacinová, Z.; Šulc, Miroslav; Haluzík, M.; Kuzma, Marek

    2016-01-01

    Roč. 408, č. 2 (2016), s. 567-578 ISSN 1618-2642 R&D Projects: GA ČR GA13-14105S; GA MŠk LO1509 Institutional support: RVO:61388971 ; RVO:61388963 Keywords : Mouse model * Monosodium glutamate (MSG) induced obesity * Diabetes Subject RIV: CE - Biochemistry Impact factor: 3.431, year: 2016