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Sample records for acid gaba ergic

  1. Further evidence for involvement of the dorsal hippocampus serotonergic and γ-aminobutyric acid (GABA)ergic pathways in the expression of contextual fear conditioning in rats.

    PubMed

    Almada, Rafael C; Albrechet-Souza, Lucas; Brandão, Marcus L

    2013-12-01

    Intra-dorsal hippocampus (DH) injections of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a serotonin-1A (5-hydroxytryptamine (5-HT)-1A) receptor agonist, were previously shown to inhibit the expression of contextual fear when administered six hours after conditioning. However, further understanding of the consolidation and expression of aversive memories requires investigations of these and other mechanisms at distinct time points and the regions of the brain to which they are transferred. Thus, the purpose of the present study was to investigate the role of DH serotonergic and γ-aminobutyric acid (GABA)ergic mechanisms in the expression of contextual fear 24 h after conditioning, reflected by fear-potentiated startle (FPS) and freezing behavior. The recruitment of the amygdala and medial prefrontal cortex (mPFC) in these processes was also evaluated by measuring Fos protein immunoreactivity. Although intra-DH injections of 8-OH-DPAT did not produce behavioral changes, muscimol reduced both FPS and the freezing response. Fos protein immunoreactivity revealed that contextual fear promoted wide activation of the mPFC, which was significantly reduced after intra-DH infusions of muscimol. The present findings, together with previous data, indicate that in contrast to 5-HT, which appears to play a role during the early phases of contextual aversive memory consolidation, longer-lasting GABA-mediated mechanisms are recruited during the expression of contextual fear memories.

  2. [Ammonia and GABA-ergic neurotransmission in pathogenesis of hepatic encephalopathy].

    PubMed

    Helewski, Krzysztof; Kowalczyk-Ziomek, Grazyna; Konecki, Janusz

    2003-01-01

    Pathogenesis of hepatic encephalopathy has not been fully revealed and there are many factors which may affect its development. Ammonia and changes in GABA-ergic neurotransmission seem to be the most essential of these factors. Hepatic encephalopathy is frequently, though not always, accompanied by elevated blood ammonia level. Due to the changes in permeability of blood-brain barrier the ammonia level in the brain also increases which results in both stimulating and inhibitory neurotransmission disturbances. Ammonia also affects abnormal interaction of metabolic neurones and astrocytes as well as glutamine-serotonin balance. Another essential factor affecting hepatic encephalopathy development are disturbances in GABA-ergic neurotransmission connected with GABAA receptor complex. When the liver is damaged GABA-ergic neurotransmission increases due to a higher GABA level, natural benzodiazepine receptor agonists as well as neurosteroids synthesised in astrocytes. Many studies point to the fact that ammonia and GABA-ergic neurotransmission disturbances interrelate with each other. There is a concept saying that both these factors cause hepatic encephalopathy. Ammonia may indirectly increase GABA-ergic neurotransmission and also inhibit the function of the central nervous system by synergistic activity with benzodiazepine receptor ligands. So far it is not known whether GABA-ergic neurotransmission is affected by ammonia only or by other factors as well. PMID:15058165

  3. Friedreich ataxia: failure of GABA-ergic and glycinergic synaptic transmission in the dentate nucleus.

    PubMed

    Koeppen, Arnulf H; Ramirez, R Liane; Becker, Alyssa B; Feustel, Paul J; Mazurkiewicz, Joseph E

    2015-02-01

    Atrophy of large neurons in the dentate nucleus (DN) is an important pathologic correlate of neurologic disability in patients with Friedreich ataxia (FA). Thinning of the DN was quantified in 29 autopsy cases of FA and 2 carriers by measuring the thickness of the gray matter ribbon on stains with anti-glutamic acid decarboxylase, the rate-limiting enzyme in the biosynthesis of γ-amino-butyric acid (GABA). The DN was thinner than normal in all cases of FA, and atrophy correlated inversely with disease duration but not with age at onset or length of the homozygous guanine-adenine-adenine trinucleotide expansions. In 13 of the FA cases, frozen DN tissue was available for assay of frataxin. Dentate nucleus atrophy was more severe when frataxin was very low. Immunohistochemical staining for glutamic acid decarboxylase revealed grumose reaction and preservation of small GABA-ergic neurons in the DN of FA patients. Residual small DN neurons and varicose axons also contained the glycine transporter 2, identifying them as glycinergic. Immunohistochemistry also confirmed severe loss of GABA-A and glycine receptors in the DN with comparable depletion of the receptor-anchoring protein gephyrin. Thus, loss of gephyrin and failure to position GABA-A and glycine receptors correctly may reduce trophic support of large DN neurons and contribute to their atrophy. By contrast, Purkinje cells may escape retrograde atrophy in FA by issuing new axonal sprouts to small surviving DN neurons where they form reparative grumose clusters.

  4. Parvalbumin and neuropeptide Y expressing hippocampal GABA-ergic inhibitory interneuron numbers decline in a model of Gulf War illness

    PubMed Central

    Megahed, Tarick; Hattiangady, Bharathi; Shuai, Bing; Shetty, Ashok K.

    2015-01-01

    Cognitive dysfunction is amongst the most conspicuous symptoms in Gulf War illness (GWI). Combined exposure to the nerve gas antidote pyridostigmine bromide (PB), pesticides and stress during the Persian Gulf War-1 (PGW-1) are presumed to be among the major causes of GWI. Indeed, our recent studies in rat models have shown that exposure to GWI-related (GWIR) chemicals and mild stress for 4 weeks engenders cognitive impairments accompanied with several detrimental changes in the hippocampus. In this study, we tested whether reduced numbers of hippocampal gamma-amino butyric acid (GABA)-ergic interneurons are among the pathological changes induced by GWIR-chemicals and stress. Animals were exposed to low doses of GWIR-chemicals and mild stress for 4 weeks. Three months after this exposure, subpopulations of GABA-ergic interneurons expressing the calcium binding protein parvalbumin (PV), the neuropeptide Y (NPY) and somatostatin (SS) in the hippocampus were stereologically quantified. Animals exposed to GWIR-chemicals and stress for 4 weeks displayed reduced numbers of PV-expressing GABA-ergic interneurons in the dentate gyrus and NPY-expressing interneurons in the CA1 and CA3 subfields. However, no changes in SS+ interneuron population were observed in the hippocampus. Furthermore, GABA-ergic interneuron deficiency in these animals was associated with greatly diminished hippocampus neurogenesis. Because PV+ and NPY+ interneurons play roles in maintaining normal cognitive function and neurogenesis, and controlling the activity of excitatory neurons in the hippocampus, reduced numbers of these interneurons may be one of the major causes of cognitive dysfunction and reduced neurogenesis observed in GWI. Hence, strategies that improve inhibitory neurotransmission in the hippocampus may prove beneficial for reversing cognitive dysfunction in GWI. PMID:25620912

  5. Development of the GABA-ergic signaling system and its role in larval swimming in sea urchin.

    PubMed

    Katow, Hideki; Abe, Kouki; Katow, Tomoko; Zamani, Alemeh; Abe, Hirokazu

    2013-05-01

    The present study aimed to elucidate the development and γ-amino butyric acid (GABA)-ergic regulation of larval swimming in the sea urchin Hemicentrotus pulcherrimus by cloning glutamate decarboxylase (Hp-gad), GABAA receptor (Hp-gabrA) and GABAA receptor-associated protein (Hp-gabarap), and by performing immunohistochemistry. The regulation of larval swimming was increasingly dependent on the GABAergic system, which was active from the 2 days post-fertilization (d.p.f.) pluteus stage onwards. GABA-immunoreactive cells were detected as a subpopulation of secondary mesenchyme cells during gastrulation and eventually constituted the ciliary band and a subpopulation of blastocoelar cells during the pluteus stage. Hp-gad transcription was detected by RT-PCR during the period when Hp-Gad-positive cells were seen as a subpopulation of blastocoelar cells and on the apical side of the ciliary band from the 2 d.p.f. pluteus stage. Consistent with these observations, inhibition of GAD with 3-mercaptopropioninc acid inhibited GABA immunoreactivity and larval swimming dose dependently. Hp-gabrA amplimers were detected weakly in unfertilized eggs and 4 d.p.f. plutei but strongly from fertilized eggs to 2 d.p.f. plutei, and Hp-GabrA, together with GABA, was localized at the ciliary band in association with dopamine receptor D1 from the two-arm pluteus stage. Hp-gabarap transcription and protein expression were detected from the swimming blastula stage. Inhibition of the GABAA receptor by bicuculline inhibited larval swimming dose dependently. Inhibition of larval swimming by either 3-mercaptopropionic acid or bicuculline was more severe in older larvae (17 and 34 d.p.f. plutei) than in younger ones (1 d.p.f. prism larvae). PMID:23307803

  6. Learning-Dependent Plasticity of the Barrel Cortex Is Impaired by Restricting GABA-Ergic Transmission.

    PubMed

    Posluszny, Anna; Liguz-Lecznar, Monika; Turzynska, Danuta; Zakrzewska, Renata; Bielecki, Maksymilian; Kossut, Malgorzata

    2015-01-01

    Experience-induced plastic changes in the cerebral cortex are accompanied by alterations in excitatory and inhibitory transmission. Increased excitatory drive, necessary for plasticity, precedes the occurrence of plastic change, while decreased inhibitory signaling often facilitates plasticity. However, an increase of inhibitory interactions was noted in some instances of experience-dependent changes. We previously reported an increase in the number of inhibitory markers in the barrel cortex of mice after fear conditioning engaging vibrissae, observed concurrently with enlargement of the cortical representational area of the row of vibrissae receiving conditioned stimulus (CS). We also observed that an increase of GABA level accompanied the conditioning. Here, to find whether unaltered GABAergic signaling is necessary for learning-dependent rewiring in the murine barrel cortex, we locally decreased GABA production in the barrel cortex or reduced transmission through GABAA receptors (GABAARs) at the time of the conditioning. Injections of 3-mercaptopropionic acid (3-MPA), an inhibitor of glutamic acid decarboxylase (GAD), into the barrel cortex prevented learning-induced enlargement of the conditioned vibrissae representation. A similar effect was observed after injection of gabazine, an antagonist of GABAARs. At the behavioral level, consistent conditioned response (cessation of head movements in response to CS) was impaired. These results show that appropriate functioning of the GABAergic system is required for both manifestation of functional cortical representation plasticity and for the development of a conditioned response.

  7. Role of noradrenergic and GABA-ergic inputs in pedunculopontine tegmentum for regulation of rapid eye movement sleep in rats.

    PubMed

    Pal, Dinesh; Mallick, Birendra Nath

    2006-07-01

    Rapid eye movement (REM) sleep disturbance is associated with several psycho-behavioral disorders, hence, it is important to understand its neural mechanism of regulation. Although it was known that the noradrenergic (NA-ergic) neurons from locus coeruleus (LC) project to the pedunculopontine tegmentum (PPT), the role of noradrenaline (NA) alone and in association with GABA, an inhibitory neurotransmitter, in PPT for REM sleep regulation was not known and was investigated in this study in freely moving normally behaving rats. Rats were surgically prepared for electrophysiological sleep-wake recording and simultaneous bilateral microinjections into PPT. 200nl of prazosin (alpha1-antagonist) or clonidine (alpha2-agonist) or propranolol (beta-antagonist) or combination of picrotoxin (GABA-A antagonist) and clonidine or vehicle (control) was microinjected bilaterally into PPT using a remote-controlled pump and the effects on REM sleep compared. Prazosin, clonidine and propranolol increased the total time spent in REM sleep whereas co-injection of picrotoxin and clonidine did not affect REM sleep. The results suggest that NA in PPT tonically inhibits REM sleep, possibly by acting on the cholinergic REM-ON neurons, while GABA inhibits the release of NA for REM sleep regulation. A model of neural connections explaining such regulation has been presented.

  8. Neural Stem Cell or Human Induced Pluripotent Stem Cell-Derived GABA-ergic Progenitor Cell Grafting in an Animal Model of Chronic Temporal Lobe Epilepsy.

    PubMed

    Upadhya, Dinesh; Hattiangady, Bharathi; Shetty, Geetha A; Zanirati, Gabriele; Kodali, Maheedhar; Shetty, Ashok K

    2016-01-01

    Grafting of neural stem cells (NSCs) or GABA-ergic progenitor cells (GPCs) into the hippocampus could offer an alternative therapy to hippocampal resection in patients with drug-resistant chronic epilepsy, which afflicts >30% of temporal lobe epilepsy (TLE) cases. Multipotent, self-renewing NSCs could be expanded from multiple regions of the developing and adult brain, human embryonic stem cells (hESCs), and human induced pluripotent stem cells (hiPSCs). On the other hand, GPCs could be generated from the medial and lateral ganglionic eminences of the embryonic brain and from hESCs and hiPSCs. To provide comprehensive methodologies involved in testing the efficacy of transplantation of NSCs and GPCs in a rat model of chronic TLE, NSCs derived from the rat medial ganglionic eminence (MGE) and MGE-like GPCs derived from hiPSCs are taken as examples in this unit. The topics comprise description of the required materials, reagents and equipment, methods for obtaining rat MGE-NSCs and hiPSC-derived MGE-like GPCs in culture, generation of chronically epileptic rats, intrahippocampal grafting procedure, post-grafting evaluation of the effects of grafts on spontaneous recurrent seizures and cognitive and mood impairments, analyses of the yield and the fate of graft-derived cells, and the effects of grafts on the host hippocampus. © 2016 by John Wiley & Sons, Inc. PMID:27532817

  9. Neural Stem Cell or Human Induced Pluripotent Stem Cell-Derived GABA-ergic Progenitor Cell Grafting in an Animal Model of Chronic Temporal Lobe Epilepsy.

    PubMed

    Upadhya, Dinesh; Hattiangady, Bharathi; Shetty, Geetha A; Zanirati, Gabriele; Kodali, Maheedhar; Shetty, Ashok K

    2016-08-17

    Grafting of neural stem cells (NSCs) or GABA-ergic progenitor cells (GPCs) into the hippocampus could offer an alternative therapy to hippocampal resection in patients with drug-resistant chronic epilepsy, which afflicts >30% of temporal lobe epilepsy (TLE) cases. Multipotent, self-renewing NSCs could be expanded from multiple regions of the developing and adult brain, human embryonic stem cells (hESCs), and human induced pluripotent stem cells (hiPSCs). On the other hand, GPCs could be generated from the medial and lateral ganglionic eminences of the embryonic brain and from hESCs and hiPSCs. To provide comprehensive methodologies involved in testing the efficacy of transplantation of NSCs and GPCs in a rat model of chronic TLE, NSCs derived from the rat medial ganglionic eminence (MGE) and MGE-like GPCs derived from hiPSCs are taken as examples in this unit. The topics comprise description of the required materials, reagents and equipment, methods for obtaining rat MGE-NSCs and hiPSC-derived MGE-like GPCs in culture, generation of chronically epileptic rats, intrahippocampal grafting procedure, post-grafting evaluation of the effects of grafts on spontaneous recurrent seizures and cognitive and mood impairments, analyses of the yield and the fate of graft-derived cells, and the effects of grafts on the host hippocampus. © 2016 by John Wiley & Sons, Inc.

  10. Effect of two GABA-ergic drugs on the cognitive functions of rapid eye movement in sleep-deprived and recovered rats

    PubMed Central

    Bao, Lidao; Si, Lengge; Wang, Yuehong; Wuyun, Gerile; Bo, Agula

    2016-01-01

    Rapid eye movement (REM) sleep is closely associated with nervous functions. The present study aimed to evaluate the effects of gabazine and tiagabine on the cognitive functions (CF) of REM sleep-deprived and sleep recovered rats. Rats were divided into REM sleep deprivation, blank control (CC) and environmental groups. The REM sleep deprivation group was further divided into non-operation (nonOP), sham-operated (Sham), gabazine (SR) and tiagabine groups. Each group was evaluated over five time points: Sleep deprived for 1 day (SD 1 day), SD 3 day, SD 5 day, sleep recovery 6 h (RS 6 h) and RS 12 h. A rat model of REM sleep deprivation was established by a modified multi-platform water method, with CF assessed by Morris water maze. Hypothalamic γ-aminobutyric acid (GABA) and glutamic acid contents were measured via high performance liquid chromatography. The number and morphology of hypocretin (Hcrt) neurons and Fos in the hypothalamus, and GABAARα1-induced integral optical density were detected by immunofluorescence. Compared to the CC group, the nonOP and Sham group rats CF were significantly diminished, Fos-positive and Fos-Hcrt double positive cells were significantly increased, and GABA content and GABAARα1 expression levels were significantly elevated (P<0.05). The tiagabine and CC groups exhibited similar results at three time points. The CF of rats in the SR group were diminished and the number of Fos-positive and Fos-Hcrt double positive cells were significantly increased (P<0.05) at RS 6 h and RS l2 h. GABA content and GABAARα1 expression levels were significantly increased in the SR group at all time points (P<0.05), whereas only GABAARα1 expression levels were significantly increased in the tiagabine group at SD 5 day (P<0.05). The results of the present study indicated that REM sleep deprivation diminished CF, increased the number of Hcrt neurons, GABA content and GABAARα1 expression. Furthermore, all alterations were positively correlated with

  11. The role of the GABA system in amphetamine-type stimulant use disorders

    PubMed Central

    Jiao, Dongliang; liu, Yao; Li, Xiaohong; liu, Jinggen; Zhao, Min

    2015-01-01

    Abuse of amphetamine-type stimulants (ATS) has become a global public health problem. ATS causes severe neurotoxicity, which could lead to addiction and could induce psychotic disorders or cognitive dysfunctions. However, until now, there has been a lack of effective medicines for treating ATS-related problems. Findings from recent studies indicate that in addition to the traditional dopamine-ergic system, the GABA (gamma-aminobutyric acid)-ergic system plays an important role in ATS abuse. However, the exact mechanisms of the GABA-ergic system in amphetamine-type stimulant use disorders are not fully understood. This review discusses the role of the GABA-ergic system in ATS use disorders, including ATS induced psychotic disorders and cognitive dysfunctions. We conclude that the GABA-ergic system are importantly involved in the development of ATS use disorders through multiple pathways, and that therapies or medicines that target specific members of the GABA-ergic system may be novel effective interventions for the treatment of ATS use disorders. PMID:25999814

  12. Effects of glutamate decarboxylase and gamma-aminobutyric acid (GABA) transporter on the bioconversion of GABA in engineered Escherichia coli.

    PubMed

    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%.

  13. Role of GABA-ergic and serotonergic systems in the anxiolytic-like mechanism of action of a 5-HT-moduline antagonist in the mouse elevated plus maze.

    PubMed

    Clénet, Florence; Hascoët, Martine; Fillion, Gilles; Galons, Hervé; Bourin, Michel

    2005-03-30

    5-HT-moduline is an endogenous tetrapeptide, which acts specifically as an antagonist of 5-HT1B auto- and heteroreceptors. HG1 is an ethyl arylmethyloxypiperidine acetate and an antagonist of 5-HT-moduline, which has no 5-HT-moduline agonist effect. In a pilot study, HG1 has demonstrated an anxiolytic-like profile in three mouse models of anxiety (elevated plus maze, light/dark, four plates). The aim of our study was to examine the mechanism of the anxiolytic-like effects of HG1 in the mouse elevated plus maze. Male Swiss mice were acutely administered HG1 at active doses in association with GABA antagonists such as flumazenil, bicuculline and picrotoxine, then, with 5-HT1A (NAN 190, WAY 100635) and 5-HT1B receptor antagonist (methiothepine). Finally, we tried to potentiate non-active doses of HG1 with 5-HT1A (8-OHDPAT) and 5-HT1B receptor agonists (anpirtoline) in the mouse elevated plus maze. Regarding GABA antagonists, only flumazenil antagonised active doses of HG1 in an incomplete manner. Moreover, non-active doses of HG1 were potentiated by low doses of WAY 100635 and by anpirtoline but not by 8-OHDPAT. Finally, the anxiolytic-like effects of HG1 at active doses were antagonised by all serotonergic antagonists (WAY 100635 at higher dose, NAN 190 and methiothepin). HG1 mechanism of action in the mouse elevated plus maze seems to associate a GABA-ergic component exerting a limited regulation of 5-HT neuronal activity and a major serotonergic component, which seems to implicate presynaptic 5-HT1A and 5-HT1B receptors.

  14. Signal Transduction in Astrocytes during Chronic or Acute Treatment with Drugs (SSRIs, Antibipolar Drugs, GABA-ergic Drugs, and Benzodiazepines) Ameliorating Mood Disorders

    PubMed Central

    Li, Baoman; Du, Ting; Xu, Junnan; Chen, Ye; Peng, Liang

    2014-01-01

    Chronic treatment with fluoxetine or other so-called serotonin-specific reuptake inhibitor antidepressants (SSRIs) or with a lithium salt “lithium”, carbamazepine, or valproic acid, the three classical antibipolar drugs, exerts a multitude of effects on astrocytes, which in turn modulate astrocyte-neuronal interactions and brain function. In the case of the SSRIs, they are to a large extent due to 5-HT2B-mediated upregulation and editing of genes. These alterations induce alteration in effects of cPLA2, GluK2, and the 5-HT2B receptor, probably including increases in both glucose metabolism and glycogen turnover, which in combination have therapeutic effect on major depression. The ability of increased levels of extracellular K+ to increase [Ca2+]i is increased as a sign of increased K+-induced excitability in astrocytes. Acute anxiolytic drug treatment with benzodiazepines or GABAA receptor stimulation has similar glycogenolysis-enhancing effects. The antibipolar drugs induce intracellular alkalinization in astrocytes with lithium acting on one acid extruder and carbamazepine and valproic acid on a different acid extruder. They inhibit K+-induced and transmitter-induced increase of astrocytic [Ca2+]i and thereby probably excitability. In several cases, they exert different changes in gene expression than SSRIs, determined both in cultured astrocytes and in freshly isolated astrocytes from drug-treated animals. PMID:24707399

  15. Suppression of γ-aminobutyric acid (GABA) transaminases induces prominent GABA accumulation, dwarfism and infertility in the tomato (Solanum lycopersicum L.).

    PubMed

    Koike, Satoshi; Matsukura, Chiaki; Takayama, Mariko; Asamizu, Erika; Ezura, Hiroshi

    2013-05-01

    Tomatoes accumulate γ-aminobutyric acid (GABA) at high levels in the immature fruits. GABA is rapidly converted to succinate during fruit ripening through the activities of GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH). Although three genes encoding GABA-T and both pyruvate- and α-ketoglutarate-dependent GABA-T activities have been detected in tomato fruits, the mechanism underlying the GABA-T-mediated conversion of GABA has not been fully understood. In this work, we conducted loss-of-function analyses utilizing RNA interference (RNAi) transgenic plants with suppressed pyruvate- and glyoxylate-dependent GABA-T gene expression to clarify which GABA-T isoforms are essential for its function. The RNAi plants with suppressed SlGABA-T gene expression, particularly SlGABA-T1, showed severe dwarfism and infertility. SlGABA-T1 expression was inversely associated with GABA levels in the fruit at the red ripe stage. The GABA contents in 35S::SlGABA-T1(RNAi) lines were 1.3-2.0 times and 6.8-9.2 times higher in mature green and red ripe fruits, respectively, than the contents in wild-type fruits. In addition, SlGABA-T1 expression was strongly suppressed in the GABA-accumulating lines. These results indicate that pyruvate- and glyoxylate-dependent GABA-T is the essential isoform for GABA metabolism in tomato plants and that GABA-T1 primarily contributes to GABA reduction in the ripening fruits.

  16. Production of gaba (γ – Aminobutyric acid) by microorganisms: a review

    PubMed Central

    Dhakal, Radhika; Bajpai, Vivek K.; Baek, Kwang-Hyun

    2012-01-01

    GABA (γ-aminobutyric acid) is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB), which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods. PMID:24031948

  17. [Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress].

    PubMed

    Wang, Chun-Yan; Li, Jing-Rui; Xia, Qing-Ping; Wu, Xiao-Lei; Gao, Hong-Bo

    2014-07-01

    This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen.

  18. [Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress].

    PubMed

    Wang, Chun-Yan; Li, Jing-Rui; Xia, Qing-Ping; Wu, Xiao-Lei; Gao, Hong-Bo

    2014-07-01

    This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen. PMID:25345052

  19. Co-Localization of GABA Shunt Enzymes for the Efficient Production of Gamma-Aminobutyric Acid via GABA Shunt Pathway in Escherichia coli.

    PubMed

    Pham, Van Dung; Somasundaram, Sivachandiran; Park, Si Jae; Lee, Seung Hwan; Hong, Soon Ho

    2016-04-28

    Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.

  20. Synthesis and proton NMR spectroscopy of intra-vesicular gamma-aminobutyric acid (GABA).

    PubMed

    Wang, Luke Y-J; Tong, Rong; Kohane, Daniel S

    2013-01-01

    We report the synthesis of vesicles containing gamma-aminobutyric acid (GABA), and their proton nuclear magnetic resonance ((1)H NMR) spectra. These vesicles were constructed to more closely mimic the intracellular environment wherein GABA exists. For this study, these GABA-containing vesicles were examined under (1)H NMR as a potential platform for future studies on the differences between aqueous phantoms, ex vivo brain extracts, and in vivo magnetic resonance spectroscopy results. We found that intra-vesicular GABA faithfully yielded the chemical shifts and J-coupling constants of free aqueous GABA, alongside the chemical shift signals of the vesicle wall.

  1. Development of imidazole alkanoic acids as mGAT3 selective GABA uptake inhibitors.

    PubMed

    Hack, Silke; Wörlein, Babette; Höfner, Georg; Pabel, Jörg; Wanner, Klaus T

    2011-05-01

    A new series of potential GABA uptake inhibitors starting from of 1H-imidazol-4-ylacetic acid with the carboxylic acid side chain originating from different positions and varying in length have been synthesized and tested for the inhibitory potency at the four GABA uptake transporters mGAT1-4 stably expressed in HEK cells. Further two bicyclic compounds with a rigidified carboxylic acid side chain were included in this study. The results of the biological tests indicated that most ω-imidazole alkanoic and alkenoic acid derivatives exhibit the highest potencies as GABA uptake inhibitors at mGAT3.

  2. A functional role for both γ-aminobutyric acid (GABA) transporter-1 and GABA transporter-3 in the modulation of extracellular GABA and GABAergic tonic conductances in the rat hippocampus

    PubMed Central

    Kersanté, Flavie; Rowley, Samuel C S; Pavlov, Ivan; Gutièrrez-Mecinas, María; Semyanov, Alexey; Reul, Johannes M H M; Walker, Matthew C; Linthorst, Astrid C E

    2013-01-01

    Tonic γ-aminobutyric acid (GABA)A receptor-mediated signalling controls neuronal network excitability in the hippocampus. Although the extracellular concentration of GABA (e[GABA]) is critical in determining tonic conductances, knowledge on how e[GABA] is regulated by different GABA transporters (GATs) in vivo is limited. Therefore, we studied the role of GATs in the regulation of hippocampal e[GABA] using in vivo microdialysis in freely moving rats. Here we show that GAT-1, which is predominantly presynaptically located, is the major GABA transporter under baseline, quiescent conditions. Furthermore, a significant contribution of GAT-3 in regulating e[GABA] was revealed by administration of the GAT-3 inhibitor SNAP-5114 during simultaneous blockade of GAT-1 by NNC-711. Thus, the GABA transporting activity of GAT-3 (the expression of which is confined to astrocytes) is apparent under conditions in which GAT-1 is blocked. However, sustained neuronal activation by K+-induced depolarization caused a profound spillover of GABA into the extrasynaptic space and this increase in e[GABA] was significantly potentiated by sole blockade of GAT-3 (i.e. even when uptake of GAT-1 is intact). Furthermore, experiments using tetrodotoxin to block action potentials revealed that GAT-3 regulates extrasynaptic GABA levels from action potential-independent sources when GAT-1 is blocked. Importantly, changes in e[GABA] resulting from both GAT-1 and GAT-3 inhibition directly precipitate changes in tonic conductances in dentate granule cells as measured by whole-cell patch-clamp recording. Thus, astrocytic GAT-3 contributes to the regulation of e[GABA] in the hippocampus in vivo and may play an important role in controlling the excitability of hippocampal cells when network activity is increased. PMID:23381899

  3. Attenuation of γ-aminobutyric acid (GABA) transaminase activity contributes to GABA increase in the cerebral cortex of mice exposed to β-cypermethrin.

    PubMed

    Han, Y; Cao, D; Li, X; Zhang, R; Yu, F; Ren, Y; An, L

    2014-03-01

    The current study investigated the γ-aminobutyric acid (GABA) levels and GABA metabolic enzymes (GABA transaminase (GABA(T)) and glutamate decarboxylase (GAD)) activities at 2 and 4 h after treatment, using a high-performance liquid chromatography with ultraviolet detectors and colorimetric assay, in the cerebral cortex of mice treated with 20, 40 or 80 mg/kg β-cypermethrin by a single oral gavage, with corn oil as vehicle control. In addition, GABA protein (4 h after treatment), GABA(T) protein (2 h after treatment) and GABA receptors messenger RNA (mRNA) expression were detected by immunohistochemistry, Western blot and real-time quantitative reverse transcriptase polymerase chain reaction, respectively. β-Cypermethrin (80 mg/kg) significantly increased GABA levels in the cerebral cortex of mice, at both 2 and 4 h after treatment, compared with the control. Also, GABA immunohistochemistry results suggested that the number of positive granules was increased in the cerebral cortex of mice 4 h after exposure to 80 mg/kg β-cypermethrin when compared with the control. Furthermore, the results also showed that GABA(T) activity detected was significantly decreased in the cerebral cortex of mice 2 h after β-cypermethrin administration (40 or 80 mg/kg). No significant changes were found in GAD activity, or the expression of GABA(T) protein and GABAB receptors mRNA, in the cerebral cortex of mice, except that 80 mg/kg β-cypermethrin caused a significant decrease, compared with the vehicle control, in GABAA receptors mRNA expression 4 h after administration. These results suggested that attenuated GABA(T) activity induced by β-cypermethrin contributed to increased GABA levels in the mouse brain. The downregulated GABAA receptors mRNA expression is most likely a downstream event.

  4. GABA production by glutamic acid decarboxylase is regulated by a dynamic catalytic loop.

    PubMed

    Fenalti, Gustavo; Law, Ruby H P; Buckle, Ashley M; Langendorf, Christopher; Tuck, Kellie; Rosado, Carlos J; Faux, Noel G; Mahmood, Khalid; Hampe, Christiane S; Banga, J Paul; Wilce, Matthew; Schmidberger, Jason; Rossjohn, Jamie; El-Kabbani, Ossama; Pike, Robert N; Smith, A Ian; Mackay, Ian R; Rowley, Merrill J; Whisstock, James C

    2007-04-01

    Gamma-aminobutyric acid (GABA) is synthesized by two isoforms of the pyridoxal 5'-phosphate-dependent enzyme glutamic acid decarboxylase (GAD65 and GAD67). GAD67 is constitutively active and is responsible for basal GABA production. In contrast, GAD65, an autoantigen in type I diabetes, is transiently activated in response to the demand for extra GABA in neurotransmission, and cycles between an active holo form and an inactive apo form. We have determined the crystal structures of N-terminal truncations of both GAD isoforms. The structure of GAD67 shows a tethered loop covering the active site, providing a catalytic environment that sustains GABA production. In contrast, the same catalytic loop is inherently mobile in GAD65. Kinetic studies suggest that mobility in the catalytic loop promotes a side reaction that results in cofactor release and GAD65 autoinactivation. These data reveal the molecular basis for regulation of GABA homeostasis.

  5. A Fluorescence-Coupled Assay for Gamma Aminobutyric Acid (GABA) Reveals Metabolic Stress-Induced Modulation of GABA Content in Neuroendocrine Cancer

    PubMed Central

    Ippolito, Joseph E.; Piwnica-Worms, David

    2014-01-01

    Pathways involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA) have been implicated in the pathogenesis of high grade neuroendocrine (NE) neoplasms as well as neoplasms from a non-NE lineage. Using The Cancer Genome Atlas, overexpression of the GABA synthetic enzyme, glutamate decarboxylase 1 (GAD1), was found to be associated with decreased disease free-survival in prostate adenocarcinoma and decreased overall survival in clear cell renal cell carcinomas. Furthermore, GAD1 was found to be expressed in castrate-resistant prostate cancer cell lines, but not androgen-responsive cell lines. Using a novel fluorescence-coupled enzymatic microplate assay for GABA mediated through reduction of resazurin in a prostate neuroendocrine carcinoma (PNEC) cell line, acid microenvironment-induced stress increased GABA levels while alkaline microenvironment-induced stress decreased GABA through modulation of GAD1 and glutamine synthetase (GLUL) activities. Moreover, glutamine but not glucose deprivation decreased GABA through modulation of GLUL. Consistent with evidence in prokaryotic and eukaryotic organisms that GABA synthesis mediated through GAD1 may play a crucial role in surviving stress, GABA may be an important mediator of stress survival in neoplasms. These findings identify GABA synthesis and metabolism as a potentially important pathway for regulating cancer cell stress response as well as a potential target for therapeutic strategies. PMID:24551133

  6. A fluorescence-coupled assay for gamma aminobutyric acid (GABA) reveals metabolic stress-induced modulation of GABA content in neuroendocrine cancer.

    PubMed

    Ippolito, Joseph E; Piwnica-Worms, David

    2014-01-01

    Pathways involved in the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA) have been implicated in the pathogenesis of high grade neuroendocrine (NE) neoplasms as well as neoplasms from a non-NE lineage. Using The Cancer Genome Atlas, overexpression of the GABA synthetic enzyme, glutamate decarboxylase 1 (GAD1), was found to be associated with decreased disease free-survival in prostate adenocarcinoma and decreased overall survival in clear cell renal cell carcinomas. Furthermore, GAD1 was found to be expressed in castrate-resistant prostate cancer cell lines, but not androgen-responsive cell lines. Using a novel fluorescence-coupled enzymatic microplate assay for GABA mediated through reduction of resazurin in a prostate neuroendocrine carcinoma (PNEC) cell line, acid microenvironment-induced stress increased GABA levels while alkaline microenvironment-induced stress decreased GABA through modulation of GAD1 and glutamine synthetase (GLUL) activities. Moreover, glutamine but not glucose deprivation decreased GABA through modulation of GLUL. Consistent with evidence in prokaryotic and eukaryotic organisms that GABA synthesis mediated through GAD1 may play a crucial role in surviving stress, GABA may be an important mediator of stress survival in neoplasms. These findings identify GABA synthesis and metabolism as a potentially important pathway for regulating cancer cell stress response as well as a potential target for therapeutic strategies.

  7. A tonoplast Glu/Asp/GABA exchanger that affects tomato fruit amino acid composition.

    PubMed

    Snowden, Christopher J; Thomas, Benjamin; Baxter, Charles J; Smith, J Andrew C; Sweetlove, Lee J

    2015-03-01

    Vacuolar accumulation of acidic metabolites is an important aspect of tomato fruit flavour and nutritional quality. The amino acids Asp and Glu accumulate to high concentrations during ripening, while γ-aminobutyrate (GABA) shows an approximately stoichiometric decline. Given that GABA can be catabolised to form Glu and subsequently Asp, and the requirement for the fruit to maintain osmotic homeostasis during ripening, we hypothesised the existence of a tonoplast transporter that exports GABA from the vacuole in exchange for import of either Asp or Glu. We show here that the tomato vacuolar membrane possesses such a transport property: transport of Glu across isolated tonoplast vesicle membranes was trans-stimulated in counterexchange mode by GABA, Glu and Asp. We identified SlCAT9 as a candidate protein for this exchanger using quantitative proteomics of a tonoplast-enriched membrane fraction. Transient expression of a SlCAT9-YFP fusion in tobacco confirmed a tonoplast localisation. The function of the protein was examined by overexpression of SlCAT9 in transgenic tomato plants. Tonoplast vesicles isolated from transgenic plants showed higher rates of Glu and GABA transport than wild-type (WT) only when assayed in counterexchange mode with Glu, Asp, or GABA. Moreover, there were substantial increases in the content of all three cognate amino acids in ripe fruit from the transgenic plants. We conclude that SlCAT9 is a tonoplast Glu/Asp/GABA exchanger that strongly influences the accumulation of these amino acids during fruit development.

  8. Dual action of isoflurane on the gamma-aminobutyric acid (GABA)-mediated currents through recombinant alpha(1)beta(2)gamma(2L)-GABA(A)-receptor channels.

    PubMed

    Neumahr, S; Hapfelmeier, G; Scheller, M; Schneck, H; Franke, C; Kochs, E

    2000-05-01

    Isoflurane (ISO) increased the agonist-induced chloride flux through the gamma-aminobutyric acid A receptor (GABA(A)R). This may reflect an anesthetic-induced increase in the apparent agonist affinity. A dual effect of anesthetics was postulated for both the nicotinic acetylcholine receptor (nAChR) and the GABA(A)R. We tested the hypothesis that, in addition to a blocking effect, ISO increases gamma-aminobutyric acid (GABA)-gated currents through recombinant GABA(A)R channels. HEK293 cells were transfected with rat cDNA for alpha(1),beta(2),gamma(2L) subunits. Currents elicited by 1 mM or 0. 01 mM GABA, respectively, alone, or with increasing concentrations of ISO, were recorded by using standard patch clamp techniques. ISO reduced the peak current elicited by 1 mM GABA. Currents induced by 0.01 mM GABA were potentiated by small ISO (twofold at 0.5 mM ISO) and inhibited by larger concentrations. Withdrawal of ISO and GABA induced rebound currents, suggesting an open-channel block by ISO. These currents increased with increasing concentrations of ISO. At large concentrations of ISO, the inhibitory effect predominated and was caused by, at least partly, an open-channel block. At small concentrations of ISO, potentiation of the GABA-gated currents was more prominent. This dual action of ISO indicates different binding sites at the GABA(A)R. The balance between potentiation and block depends on the concentrations of both ISO and GABA.

  9. Relating MEG measured motor cortical oscillations to resting γ-aminobutyric acid (GABA) concentration.

    PubMed

    Gaetz, W; Edgar, J C; Wang, D J; Roberts, T P L

    2011-03-15

    The human motor cortex exhibits characteristic beta (15-30 Hz) and gamma oscillations (60-90 Hz), typically observed in the context of transient finger movement tasks. The functional significance of these oscillations, such as post-movement beta rebound (PMBR) and movement-related gamma synchrony (MRGS) remains unclear. Considerable animal and human non-invasive studies, however, suggest that the networks supporting these motor cortex oscillations depend critically on the inhibitory neurotransmitter γ-Aminobutyric acid (GABA). Despite such speculation, a direct relation between MEG measured motor cortex oscillatory power and frequency with resting GABA concentrations has not been demonstrated. In the present study, motor cortical responses were measured from 9 healthy adults while they performed a cued button-press task using their right index finger. In each participant, PMBR and MRGS measures were obtained from time-frequency plots obtained from primary motor (MI) sources, localized using beamformer differential source localization. For each participant, complimentary magnetic resonance spectroscopy (MRS) GABA measures aligned to the motor hand knob of the left central sulcus were also obtained. GABA concentration was estimated as the ratio of the motor cortex GABA integral to a cortical reference NAA resonance at 2 ppm. A significant linear relation was observed between MI GABA concentration and MRGS frequency (R(2)=0.46, p<0.05), with no association observed between GABA concentration and MRGS power. Conversely, a significant linear relation was observed between MI GABA concentration and PMBR power (R(2)=0.34, p<0.05), with no relation observed for GABA concentration and PMBR frequency. Finally, a significant negative linear relation between the participant's age and MI gamma frequency was observed, such that older participants had a lower gamma frequency (R(2)=0.40, p<0.05). Present findings support a role for GABA in the generation and modulation of

  10. Production of gamma-aminobutyric acid in black raspberry juice during fermentation by Lactobacillus brevis GABA100.

    PubMed

    Kim, Ja Young; Lee, Moo Young; Ji, Geun Eog; Lee, Yeon Sook; Hwang, Keum Taek

    2009-03-15

    Black raspberry juice was fermented to produce gamma-aminobutyric acid (GABA) using lactic acid bacteria (Lactobacillus brevis GABA 100) at different temperatures (25, 30, or 37 degrees C) and pHs (3.5, 4, 4.5, 5, 5.5, or 6) for 15 days. Concentrations of GABA in the juices were determined during fermentation using HPLC. GABA was produced continuously even if the viable bacterial counts markedly decreased. The fermentation at 30 degrees C generally showed higher production of GABA in the juices than those at 25 and 37 degrees C. The GABA in the juices fermented at 30 degrees C reached the maximum levels on the 12th day. The juices fermented at lower pH and lower temperature showed a lower degradation of monomeric anthocyanins. The results suggest that black raspberry juice can be GABA enriched using lactic acid bacteria.

  11. Contents of Neo-flavored Tea (GABA Kintaro) Containing γ-Aminobutyric Acid

    NASA Astrophysics Data System (ADS)

    Shiraki, Yoshiya

    The contents of γ-aminobutyric acid (GABA), catechins, theaflavins, caffeine and pheophorbide-a in neo-flavored tea (GABA Kintaro tea) were analyzed. 1)The amounts of GABA were increased over 1.5mg/g by means of infrared ray irradiation with agitation treatment. 2)There was a tendency for the amount of catechins to be decreased by this treatment, whereas the amount of theaflavins tended to increase with the same treatment. The composition of these contents in this GABA Kintaro tea was almost the same as that of black tea. 3)There was a tendency for the amount of caffeine to be decreased by this treatment. 4)There was a tendency for the amount of pheophorbide-a to be increased by this treatment. 5)The result of this study showed that the amounts of GABA and theaflavins in this GABA Kintaro tea were higher than ordinary green tea but contained few catechins.It became clear that the amount of pheophorbide-a in this GABA Kintaro tea was less than the standard value established in processed chlorella.

  12. γ-Aminobutyric acid (GABA) homeostasis regulates pollen germination and polarized growth in Picea wilsonii.

    PubMed

    Ling, Yu; Chen, Tong; Jing, Yanping; Fan, Lusheng; Wan, Yinglang; Lin, Jinxing

    2013-11-01

    γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid found in a wide range of organisms. Recently, GABA accumulation has been shown to play a role in the stress response and cell growth in angiosperms. However, the effect of GABA deficiency on pollen tube development remains unclear. Here, we demonstrated that specific concentrations of exogenous GABA stimulated pollen tube growth in Picea wilsonii, while an overdose suppressed pollen tube elongation. The germination percentage of pollen grains and morphological variations in pollen tubes responded in a dose-dependent manner to treatment with 3-mercaptopropionic acid (3-MP), a glutamate decarboxylase inhibitor, while the inhibitory effects could be recovered in calcium-containing medium supplemented with GABA. Using immunofluorescence labeling, we found that the actin cables were disorganized in 3-MP treated cells, followed by the transition of endo/exocytosis activating sites from the apex to the whole tube shank. In addition, variations in the deposition of cell wall components were detected upon labeling with JIM5, JIM7, and aniline blue. Our results demonstrated that calcium-dependent GABA signaling regulates pollen germination and polarized tube growth in P. wilsonii by affecting actin filament patterns, vesicle trafficking, and the configuration and distribution of cell wall components.

  13. Identification of a lithium interaction site in the gamma-aminobutyric acid (GABA) transporter GAT-1.

    PubMed

    Zhou, Yonggang; Zomot, Elia; Kanner, Baruch I

    2006-08-01

    The sodium- and chloride-dependent electrogenic gamma-aminobutyric acid (GABA) transporter GAT-1, which transports two sodium ions together with GABA, is essential for synaptic transmission by this neurotransmitter. Although lithium by itself does not support GABA transport, it has been proposed that lithium can replace sodium at one of the binding sites but not at the other. To identify putative lithium selectivity determinants, we have mutated the five GAT-1 residues corresponding to those whose side chains participate in the sodium binding sites Na1 and Na2 of the bacterial leucine-transporting homologue LeuT(Aa). In GAT-1 and in most other neurotransmitter transporter family members, four of these residues are conserved, but aspartate 395 replaces the Na2 residue threonine 354. At varying extracellular sodium, lithium stimulated sodium-dependent transport currents as well as [3H]GABA uptake in wild type GAT-1. The extent of this stimulation was dependent on the GABA concentration. In mutants in which aspartate 395 was replaced by threonine or serine, the stimulation of transport by lithium was abolished. Moreover, these mutants were unable to mediate the lithium leak currents. This phenotype was not observed in mutants at the four other positions, although their transport properties were severely impacted. Thus at saturating GABA, the site corresponding to Na2 behaves as a low affinity sodium binding site where lithium can replace sodium. We propose that GABA participates in the other sodium binding site, just like leucine does in the Na1 site, and that at limiting GABA, this site determines the apparent sodium affinity of GABA transport.

  14. Cloning of the. gamma. -aminobutyric acid (GABA). rho. sub 1 cDNA: A GABA receptor subunit highly expressed in the retina

    SciTech Connect

    Cutting, G.R.; Lu, Luo; Kasch, L.M.; Montrose-Rafizadeh, C.; Antonarakis, S.E.; Guggino, W.B.; Kazazian, H.H. Jr. ); O'Hara, B.F.; Donovan, D.M.; Shimada, Shoichi ); Uhl, G.R. Johns Hopkins Univ. School of Medicine, Baltimore, MD )

    1991-04-01

    Type A {gamma}-aminobutyric acid (GABA{sub A}) receptors are a family of ligand-gated chloride channels that are the major inhibitory neurotransmitter receptors in the nervous system. Molecular cloning has revealed diversity in the subunits that compose this heterooligomeric receptor, but each previously elucidated subunit displays amino acid similarity in conserved structural elements. The authors have used these highly conserved regions to identify additional members of this family by using the polymerase chain reaction (PCR). One PCR product was used to isolate a full-length cDNA from a human retina cDNA library. The mature protein predicted from this cDNA sequence is 458 amino acids long and displays between 30 and 38% amino acid similarity to the previously identified GABA{sub A} subunits. This gene is expressed primarily in the retina but transcripts are also detected in the brain, lung, and thymus. Injection of Xenopus oocytes with RNA transcribed in vitro produces a GABA-responsive chloride conductance and expression of the cDNA in COS cells yields GABA-displaceable muscimol binding. These features are consistent with our identification of a GABA subunit, GABA {rho}{sub 1}, with prominent retinal expression that increases the diversity and tissue specificity of this ligand-gated ion-channel receptor family.

  15. Effects of traditionally used anxiolytic botanicals on enzymes of the gamma-aminobutyric acid (GABA) system.

    PubMed

    Awad, R; Levac, D; Cybulska, P; Merali, Z; Trudeau, V L; Arnason, J T

    2007-09-01

    In Canada, the use of botanical natural health products (NHPs) for anxiety disorders is on the rise, and a critical evaluation of their safety and efficacy is required. The purpose of this study was to determine whether commercially available botanicals directly affect the primary brain enzymes responsible for gamma-aminobutyric acid (GABA) metabolism. Anxiolytic plants may interact with either glutamic acid decarboxylase (GAD) or GABA transaminase (GABA-T) and ultimately influence brain GABA levels and neurotransmission. Two in vitro rat brain homogenate assays were developed to determine the inhibitory concentrations (IC50) of aqueous and ethanolic plant extracts. Approximately 70% of all extracts that were tested showed little or no inhibitory effect (IC50 values greater than 1 mg/mL) and are therefore unlikely to affect GABA metabolism as tested. The aqueous extract of Melissa officinalis (lemon balm) exhibited the greatest inhibition of GABA-T activity (IC50 = 0.35 mg/mL). Extracts from Centella asiatica (gotu kola) and Valeriana officinalis (valerian) stimulated GAD activity by over 40% at a dose of 1 mg/mL. On the other hand, both Matricaria recutita (German chamomile) and Humulus lupulus (hops) showed significant inhibition of GAD activity (0.11-0.65 mg/mL). Several of these species may therefore warrant further pharmacological investigation. The relation between enzyme activity and possible in vivo mode of action is discussed. PMID:18066140

  16. Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera)

    PubMed Central

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2016-01-01

    γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis. PMID:27455877

  17. Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera).

    PubMed

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2016-07-26

    γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis.

  18. Metabolic pathways regulated by γ-aminobutyric acid (GABA) contributing to heat tolerance in creeping bentgrass (Agrostis stolonifera).

    PubMed

    Li, Zhou; Yu, Jingjin; Peng, Yan; Huang, Bingru

    2016-01-01

    γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis. PMID:27455877

  19. Utilization of barley or wheat bran to bioconvert glutamate to γ-aminobutyric acid (GABA).

    PubMed

    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.

  20. Neuronal gamma-aminobutyric acid (GABA) type A receptors undergo cognate ligand chaperoning in the endoplasmic reticulum by endogenous GABA

    PubMed Central

    Wang, Ping; Eshaq, Randa S.; Meshul, Charles K.; Moore, Cynthia; Hood, Rebecca L.; Leidenheimer, Nancy J.

    2015-01-01

    GABAA receptors mediate fast inhibitory neurotransmission in the brain. Dysfunction of these receptors is associated with various psychiatric/neurological disorders and drugs targeting this receptor are widely used therapeutic agents. Both the efficacy and plasticity of GABAA receptor-mediated neurotransmission depends on the number of surface GABAA receptors. An understudied aspect of receptor cell surface expression is the post-translational regulation of receptor biogenesis within the endoplasmic reticulum (ER). We have previously shown that exogenous GABA can act as a ligand chaperone of recombinant GABAA receptors in the early secretory pathway leading us to now investigate whether endogenous GABA facilitates the biogenesis of GABAA receptors in primary cerebral cortical cultures. In immunofluorescence labeling experiments, we have determined that neurons expressing surface GABAA receptors contain both GABA and its degradative enzyme GABA transaminase (GABA-T). Treatment of neurons with GABA-T inhibitors, a treatment known to increase intracellular GABA levels, decreases the interaction of the receptor with the ER quality control protein calnexin, concomittantly increasing receptor forward-trafficking and plasma membrane insertion. The effect of GABA-T inhibition on the receptor/calnexin interaction is not due to the activation of surface GABAA or GABAB receptors. Consistent with our hypothesis that GABA acts as a cognate ligand chaperone in the ER, immunogold-labeling of rodent brain slices reveals the presence of GABA within the rough ER. The density of this labeling is similar to that present in mitochondria, the organelle in which GABA is degraded. Lastly, the effect of GABA-T inhibition on the receptor/calnexin interaction was prevented by pretreatment with a GABA transporter inhibitor. Together, these data indicate that endogenous GABA acts in the rough ER as a cognate ligand chaperone to facilitate the biogenesis of neuronal GABAA receptors. PMID

  1. Modulation of GABA receptors expressed in Xenopus oocytes by 13-L-hydroxylinoleic acid and food additives.

    PubMed

    Aoshima, H; Tenpaku, Y

    1997-12-01

    To study the effects of 13-L-hydroxylinoleic acid (LOH) and food additives on gamma-aminobutyric acid (GABA) receptors, ionotropic GABA receptors were expressed in Xenopus oocytes by injecting mRNAs prepared from rat whole brain. LOH, which was prepared by reduction of 13-L-hydroperoxylinoleic acid (LOOH), inhibited the response of GABA receptors in the presence of high concentrations of GABA. LOH also inhibited nicotinic acetylcholine, glycine, and kainate receptors, while it had little effect on NMDA receptors expressed in Xenopus oocytes. However, LOH potentiated the response of GABA receptors as well as LOOH in the presence of low concentrations of GABA, possibly increasing the affinity of GABA for the receptors, while linoleic acid did not. Since some modification of the compounds seemed to change their effects on GABA receptors, the responses of GABA receptors elicited by 10 microM GABA were measured in the presence of compounds with various kinds of functional groups or the structural isomers of pentanol. Potentiation of GABA receptors depended strongly on the species of functional groups and also depended on the structure of the isomers. Then effects of various kinds of food additives on GABA receptors were also examined; perfumes such as alcohols or esters potentiated the responses strongly, while hexylamine, nicotinamide, or caffeine inhibited the responses, mainly in a competitive manner, and vanillin inhibited the responses noncompetitively. These results suggest the possibility that production of LOOH and LOH, or intake of much of some food additives, modulates the neural transmission in the brain, especially through ionotropic GABA receptors and changes the frame of the human mind, as alcohol or tobacco does.

  2. Subchronic toxicity evaluation of γ-aminobutyric acid (GABA) in rats.

    PubMed

    Takeshima, Kazuhito; Yamatsu, Atsushi; Yamashita, Yusuke; Watabe, Kazuya; Horie, Noriko; Masuda, Kazuyuki; Kim, Mujo

    2014-06-01

    γ-Aminobutyric acid (GABA) is an amino acid compound contained in vegetables such as tomatoes and also widely distributed in mammals. GABA acts as an inhibitory neurotransmitter and promotes parasympathetic activity to provide several beneficial effects, for instance, relaxation, anti-stress, and insomnia. GABA, produced via a fermentation process, has been available as a functional food ingredient. As part of a program to assess its safety, GABA was administered by oral gavage at doses of 500, 1250, and 2500mg/kg body weight to groups of 10 male and 10 female Sprague-Dawley rats for 13weeks. Treatment was not associated with the test substance-related mortality and appeared to be well tolerated. There were no toxicologically and statistically significant changes in urinalysis, hematology, clinical chemistry parameters, and in necropsy findings. A few statistically significant changes in food consumption and body weights were noted in the male groups while any significant changes were not noted in female groups. There was no effect of treatment on organ weights or on the results of the histopathological examinations. The results of toxicity evaluation support the safety use of GABA and the potential use as a functional food ingredient.

  3. γ-Aminobutyric acid (GABA) concentration inversely correlates with basal perfusion in human occipital lobe.

    PubMed

    Donahue, Manus J; Rane, Swati; Hussey, Erin; Mason, Emily; Pradhan, Subechhya; Waddell, Kevin W; Ally, Brandon A

    2014-03-01

    Commonly used neuroimaging approaches in humans exploit hemodynamic or metabolic indicators of brain function. However, fundamental gaps remain in our ability to relate such hemo-metabolic reactivity to neurotransmission, with recent reports providing paradoxical information regarding the relationship among basal perfusion, functional imaging contrast, and neurotransmission in awake humans. Here, sequential magnetic resonance spectroscopy (MRS) measurements of the primary inhibitory neurotransmitter, γ-aminobutyric acid (GABA+macromolecules normalized by the complex N-acetyl aspartate-N-acetyl aspartyl glutamic acid: [GABA(+)]/[NAA-NAAG]), and magnetic resonance imaging (MRI) measurements of perfusion, fractional gray-matter volume, and arterial arrival time (AAT) are recorded in human visual cortex from a controlled cohort of young adult male volunteers with neurocognitive battery-confirmed comparable cognitive capacity (3 T; n=16; age=23±3 years). Regression analyses reveal an inverse correlation between [GABA(+)]/[NAA-NAAG] and perfusion (R=-0.46; P=0.037), yet no relationship between AAT and [GABA(+)]/[NAA-NAAG] (R=-0.12; P=0.33). Perfusion measurements that do not control for AAT variations reveal reduced correlations between [GABA(+)]/[NAA-NAAG] and perfusion (R=-0.13; P=0.32). These findings largely reconcile contradictory reports between perfusion and inhibitory tone, and underscore the physiologic origins of the growing literature relating functional imaging signals, hemodynamics, and neurotransmission.

  4. Determination and comparison of γ-aminobutyric acid (GABA) content in pu-erh and other types of Chinese tea.

    PubMed

    Zhao, Ming; Ma, Yan; Wei, Zhen-zhen; Yuan, Wen-xia; Li, Ya-li; Zhang, Chun-hua; Xue, Xiao-ting; Zhou, Hong-jie

    2011-04-27

    Two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. However, two other researchers have demonstrated that the GABA content of several pu-erh teas was low. Due to the high value and health benefits of GABA, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with GABA. A high-performance liquid chromatography (HPLC) method was developed for the determination of GABA in tea, the results of which were verified by amino acid analysis using an Amino Acid Analyzer (AAA). A total of 114 samples of various types of Chinese tea, including 62 pu-erh teas, 13 green teas, 8 oolong teas, 8 black teas, 3 white teas, 4 GABA teas, and 16 process samples from two industrial fermentations of pu-erh tea (including the raw material and the first to seventh turnings), were analyzed using HPLC. Statistical analysis demonstrated that the GABA content in pu-erh tea was significantly lower than that in other types of tea (p < 0.05) and that the GABA content decreased during industrial fermentation of pu-erh tea (p < 0.05). This mass analysis and comparison suggested GABA was not a major bioactive constituent and resolved the disagreement GABA content in pu-erh tea. In addition, the GABA content in white tea was found to be significantly higher than that in the other types of tea (p < 0.05), leading to the possibility of producing GABA-enriched white tea.

  5. The inhibitory role of γ-aminobutyric acid (GABA) on immunomodulation of Pacific oyster Crassostrea gigas.

    PubMed

    Li, Meijia; Qiu, Limei; Wang, Lingling; Wang, Weilin; Xin, Lusheng; Li, Yiqun; Liu, Zhaoqun; Song, Linsheng

    2016-05-01

    γ-aminobutyric acid (GABA) is an inhibitory neurotransmitter to suppress the immune-mediated pro-inflammatory reactions, and it has been used in the treatment of many inflammation-related diseases in vertebrates, while its immunomodulatory role in invertebrates has never been reported. In the present study, GABA was found to exist in the hemolymph of Pacific oyster Crassostrea gigas, and its concentration decreased slightly from 8.00 ± 0.37 μmol L(-1) at normal condition to 7.73 ± 0.15 μmol L(-1) at 6 h after LPS stimulation, and then increased to 9.34 ± 0.15 μmol L(-1), 8.86 ± 0.68 μmol L(-1) at 12 h and 48 h, respectively. After LPS stimulation, the mRNA expressions of pro-inflammatory cytokines (CgIL-17 and CgTNF) and immune effectors (CgSOD and CgBPI), and the protein expression of NOS increased significantly, and these increased trends were remarkably inhibited by GABA stimulation. At the same time, the phagocytosis rate and apoptosis rate of immunocytes also increased obviously after LPS stimulation, whereas the increase was repressed with the addition of GABA. The results collectively demonstrated that GABA was an indispensable inhibitory agent for both humoral and cellular immune response, which mainly functioned at the late phase of immune response to avoid the excess immune reactions and maintain the immune homeostasis.

  6. Correlation Between Hepatocyte Growth Factor (HGF) and Gamma-Aminobutyric Acid (GABA) Plasma Levels in Autistic Children.

    PubMed

    Russo, Anthony J

    2013-01-01

    There is much support for the role of Gamma-Aminobutyric acid (GABA) in the etiology of autism. Recent research has shown that hepatocyte growth factor (HGF) modulates GABAergic inhibition and seizure susceptibility. This study was designed to determine and correlate plasma levels of HGF, GABA, as well as symptom severity, in autistic children and neurotypical controls. Plasma from 48 autistic children and 29 neurotypical controls was assessed for HGF and GABA concentration using ELISAs. Symptom severity was assessed in these autistic individuals and compared to HGF and GABA concentrations. We previously reported that autistic children had significantly decreased levels of HGF. In this study, the same autistic children had significantly increased plasma levels of GABA (P = 0.002) and decreased HGF levels correlated with these increased GABA levels (r = 0.3; P = 0.05). High GABA levels correlated with increasing hyperactivity (r = 0.6; P = 0.0007) and impulsivity severity (r = 0.5; P = 0.007), tip toeing severity (r = 0.35; P = 0.03), light sensitivity (r = 0.4; P = 0.02), and tactile sensitivity (r = 0.4; P = 0.01). HGF levels did not correlate significantly with any symptom severity. These results suggest an association between HGF and GABA levels and suggest that plasma GABA levels are related to symptom severity in autistic children.

  7. Genetic manipulation of the γ-aminobutyric acid (GABA) shunt in rice: overexpression of truncated glutamate decarboxylase (GAD2) and knockdown of γ-aminobutyric acid transaminase (GABA-T) lead to sustained and high levels of GABA accumulation in rice kernels.

    PubMed

    Shimajiri, Yasuka; Oonishi, Takayuki; Ozaki, Kae; Kainou, Kumiko; Akama, Kazuhito

    2013-06-01

    Gamma-aminobutyric acid (GABA) is a non-protein amino acid commonly present in all organisms. Because cellular levels of GABA in plants are mainly regulated by synthesis (glutamate decarboxylase, GAD) and catabolism (GABA-transaminase, GABA-T), we attempted seed-specific manipulation of the GABA shunt to achieve stable GABA accumulation in rice. A truncated GAD2 sequence, one of five GAD genes, controlled by the glutelin (GluB-1) or rice embryo globulin promoters (REG) and GABA-T-based trigger sequences in RNA interference (RNAi) cassettes controlled by one of these promoters as well, was introduced into rice (cv. Koshihikari) to establish stable transgenic lines under herbicide selection using pyriminobac. T₁ and T₂ generations of rice lines displayed high GABA concentrations (2-100 mg/100 g grain). In analyses of two selected lines from the T₃ generation, there was a strong correlation between GABA level and the expression of truncated GAD2, whereas the inhibitory effect of GABA-T expression was relatively weak. In these two lines both with two T-DNA copies, their starch, amylose, and protein levels were slightly lower than non-transformed cv. Koshihikari. Free amino acid analysis of mature kernels of these lines demonstrated elevated levels of GABA (75-350 mg/100 g polished rice) and also high levels of several amino acids, such as Ala, Ser, and Val. Because these lines of seeds could sustain their GABA content after harvest (up to 6 months), the strategy in this study could lead to the accumulation GABA and for these to be sustained in the edible parts.

  8. [Combined effect of diazepam and GABAA-ergic ligands on the activity of Cl(-)-ATPase from plasma membrane of bream brain (Abramis brama L.)].

    PubMed

    Menzikov, S A; Menzikova, O V

    2004-01-01

    We studied the combined effect of diazepam and GABAA-ergic ligands on the activity of Cl- -ATPase from plasma membrane of bream brain. of The membranes were preincubated and incubated with diazepam as well as with other GABAA-ergic ligands at physiological pH (7.4), i.e. under the conditions when Cl- -ATPase activity is undetectable. GABA (0.1-100 microM) induced Cl- -ATPase activity with the maximum effect at 10 microM. Diazepam (0.1 microM) enhanced the effect of low GABA concentrations (0.1-1 microM) on Cl- -ATPase activity but had no effect on the enzyme in the presence of high GABA concentrations (10-100 microM). At the same time, GABA (1 microM) enhanced the effect of low diazepam concentrations (0.1-1 microM) on the enzyme activity but had no effect on it in the presence of high concentrations of the ligand. Blockers of GABAA-ergic receptors, picrotoxin (50 microM) and bicuculline (5 microM), canceled the combined effect of diazepam and GABA on the enzyme activity. The obtained data demonstrate that the combined effect of diazepam and GABAA-ergic ligands on Cl- -ATPase activity at physiological pH is similar to the effect of these ligands on GABAA/benzodiazepine/Cl- channel.

  9. Gas release-based prescreening combined with reversed-phase HPLC quantitation for efficient selection of high-γ-aminobutyric acid (GABA)-producing lactic acid bacteria.

    PubMed

    Wu, Qinglong; Shah, Nagendra P

    2015-02-01

    High γ-aminobutyric acid (GABA)-producing lactobacilli are promising for the manufacture of GABA-rich foods and to synthesize GRAS (generally recognized as safe)-grade GABA. However, common chromatography-based screening is time-consuming and inefficient. In the present study, Korean kimchi was used as a model of lactic acid-based fermented foods, and a gas release-based prescreening of potential GABA producers was developed. The ability to produce GABA by potential GABA producers in de Man, Rogosa, and Sharpe medium supplemented with or without monosodium glutamate was further determined by HPLC. Based on the results, 9 isolates were regarded as high GABA producers, and were further genetically identified as Lactobacillus brevis based on the sequences of 16S rRNA gene. Gas release-based prescreening combined with reversed-phase HPLC confirmation was an efficient and cost-effective method to identify high-GABA-producing LAB, which could be good candidates for probiotics. The GABA that is naturally produced by these high-GABA-producing LAB could be used as a food additive.

  10. Prolonged treatment with gamma-aminobutyric acid (GABA)-mimetic substances in prepubertal male rats.

    PubMed

    Debeljuk, L; Díaz, M D; Maines, V M; Seilicovich, A

    1983-06-01

    The effect of chronic treatment with a gamma-aminobutyric acid (GABA)-mimetic compound, progabide, and an inhibitor of GABA-transaminase, gamma-acetylenic GABA (GAG), was tested in prepubertal male rats. The effect of gamma-butyrolactone (GBL), given orally, was also tested. The rats treated with progabide did not show any difference in body, testicular, or seminal vesicle weights or serum prolactin levels, as compared with control rats. Treatment with GAG, at both dose levels used, did not significantly affect body weight. Testicular weight was significantly lower in the group of rats treated with the low dosage of GAG (5 mg/kg), and serum prolactin was significantly lower in the rats treated with the high dosage of GAG (20 mg/kg) as compared with control rats. In the first experiment performed with GBL, the rats given this compound had significantly lower body and testicular weights as compared with control rats. In the second experiment, GBL-treated rats had body weights similar to those of control rats, but testicular weights were significantly decreased. Prolonged treatment with GABA mimetics may affect the hypothalamic-pituitary-testicular axis.

  11. Gamma-amino butyric acid (GABA) release in the ciliated protozoon Paramecium occurs by neuronal-like exocytosis.

    PubMed

    Ramoino, P; Milanese, M; Candiani, S; Diaspro, A; Fato, M; Usai, C; Bonanno, G

    2010-04-01

    Paramecium primaurelia expresses a significant amount of gamma-amino butyric acid (GABA). Paramecia possess both glutamate decarboxylase (GAD)-like and vesicular GABA transporter (vGAT)-like proteins, indicating the ability to synthesize GABA from glutamate and to transport GABA into vesicles. Using antibodies raised against mammalian GAD and vGAT, bands with an apparent molecular weight of about 67 kDa and 57 kDa were detected. The presence of these bands indicated a similarity between the proteins in Paramecium and in mammals. VAMP, syntaxin and SNAP, putative proteins of the release machinery that form the so-called SNARE complex, are present in Paramecium. Most VAMP, syntaxin and SNAP fluorescence is localized in spots that vary in size and density and are primarily distributed near the plasma membrane. Antibodies raised against mammal VAMP-3, sintaxin-1 or SNAP-25 revealed protein immunoblot bands having molecular weights consistent with those observed in mammals. Moreover, P. primaurelia spontaneously releases GABA into the environment, and this neurotransmitter release significantly increases after membrane depolarization. The depolarization-induced GABA release was strongly reduced not only in the absence of extracellular Ca(2+) but also by pre-incubation with bafilomycin A1 or with botulinum toxin C1 serotype. It can be concluded that GABA occurs in Paramecium, where it is probably stored in vesicles capable of fusion with the cell membrane; accordingly, GABA can be released from Paramecium by stimulus-induced, neuronal-like exocytotic mechanisms.

  12. Novel dose-dependent alterations in excitatory GABA during embryonic development associated with lead (Pb) neurotoxicity

    PubMed Central

    Wirbisky, Sara E.; Weber, Gregory J.; Lee, Jang-Won; Cannon, Jason R.; Freeman, Jennifer L.

    2014-01-01

    Lead (Pb) is a heavy metal that is toxic to numerous physiological processes. Its use in industrial applications is widespread and results in an increased risk of human environmental exposure. The central nervous system (CNS) is most sensitive to Pb exposure during early development due to rapid cell proliferation and migration, axonal growth, and synaptogenesis. One of the key components of CNS development is the Gamma-aminobutyric acid (GABA)ergic system. GABA is the primary inhibitory neurotransmitter in the adult brain. However, during development GABA acts as an excitatory neurotrophic factor which contributes to these cellular processes. Multiple studies report effects of Pb on GABA in the mature brain; however, little is known regarding the adverse effects of Pb exposure on the GABAergic system during embryonic development. To characterize the effects of Pb on the GABAergic system during development, zebrafish embryos were exposed to 10, 50, or 100 ppb Pb or a control treatment. Tissue up-take, gross morphological alterations, gene expression, and neurotransmitter levels were analyzed. Analysis revealed that alterations in gene expression throughout the GABAergic system and GABA levels were dose and developmental time point specific. These data provide a framework for further analysis of the effects of Pb on the GABAergic system during the excitatory phase and as GABA transitions to an inhibitory neurotransmitter during development. PMID:24875535

  13. Mutations in γ-aminobutyric acid (GABA) transaminase genes in plants or Pseudomonas syringae reduce bacterial virulence.

    PubMed

    Park, Duck Hwan; Mirabella, Rossana; Bronstein, Philip A; Preston, Gail M; Haring, Michel A; Lim, Chun Keun; Collmer, Alan; Schuurink, Robert C

    2010-10-01

    Pseudomonas syringae pv. tomato DC3000 is a bacterial pathogen of Arabidopsis and tomato that grows in the apoplast. The non-protein amino acid γ-amino butyric acid (GABA) is produced by Arabidopsis and tomato and is the most abundant amino acid in the apoplastic fluid of tomato. The DC3000 genome harbors three genes annotated as gabT GABA transaminases. A DC3000 mutant lacking all three gabT genes was constructed and found to be unable to utilize GABA as a sole carbon and nitrogen source. In complete minimal media supplemented with GABA, the mutant grew less well than wild-type DC3000 and showed strongly reduced expression of hrpL and avrPto, which encode an alternative sigma factor and effector, respectively, associated with the type III secretion system. The growth of the gabT triple mutant was weakly reduced in Arabidopsis ecotype Landberg erecta (Ler) and strongly reduced in the Ler pop2-1 GABA transaminase-deficient mutant that accumulates higher levels of GABA. Much of the ability to grow on GABA-amended minimal media or in Arabidopsis pop2-1 leaves could be restored to the gabT triple mutant by expression in trans of just gabT2. The ability of DC3000 to elicit the hypersensitive response (HR) in tobacco leaves is dependent upon deployment of the type III secretion system, and the gabT triple mutant was less able than wild-type DC3000 to elicit this HR when bacteria were infiltrated along with GABA at levels of 1 mm or more. GABA may have multiple effects on P. syringae-plant interactions, with elevated levels increasing disease resistance.

  14. Effect of diphenylhydantoin on gamma aminobutyric acid (GABA) and succinate activity in rat Purkinje cells.

    PubMed Central

    Hitchcock, E; Gabra-Sanders, T

    1977-01-01

    A study has been made of the effect of diphenylhydantoin (DPH) upon the levels of gamma aminobutyric acid (GABA) and succinic dehydrogenase in rat Purkinje cells. DPH was administered over 26 days in chronic experiments using controls receiving the same injection vehicle without DPH. Animals in this group received daily 1.25 mg/kg body weight, 12.5 mg/kg body weight, and 50 mg/kg body weight DPH. Acute experiments were carried out over the course of not more than four days, three groups of animals receiving 75 mg/kg body weight, 87.5 mg/kg body weight, and 100 mg/kg body weight DPH. No effect upon succinic dehydrogenase could be demonstrated at any dose level. There was a significant progressive loss of GABA with increasing dosage of DPH. Images PMID:903771

  15. Efficient production of gamma-aminobutyric acid using Escherichia coli by co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter.

    PubMed

    Dung Pham, Van; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho

    2016-01-01

    Gamma-aminobutyric acid (GABA) is an important bio-product, which is used in pharmaceutical formulations, nutritional supplements, and biopolymer monomer. The traditional GABA process involves the decarboxylation of glutamate. However, the direct production of GABA from glucose is a more efficient process. To construct the recombinant strains of Escherichia coli, a novel synthetic scaffold was introduced. By carrying out the co-localization of glutamate synthase, glutamate decarboxylase, and GABA transporter, we redirected the TCA cycle flux to GABA pathway. The genetically engineered E. coli strain produced 1.08 g/L of GABA from 10 g/L of initial glucose. Thus, with the introduction of a synthetic scaffold, we increased GABA production by 2.2-fold. The final GABA concentration was increased by 21.8% by inactivating competing pathways.

  16. Involvement of gamma-amino butyric acid (GABA) in the anticonvulsant action of methaqualone.

    PubMed

    Naik, S R; Naid, P R; Sheth, U K

    1978-04-14

    The effects of methaqualone on isonicotinic acid hydrazide, 6-mercapto propionic acid, picrotoxin, and strychnine-induced convulsion were studied in mice and the results compared with diazepam. Methaqualone, like diazepam, was found to be a selective antagonist of isoniazid-induced convulsion and a much less effective inhibitor of strychnine convulsion. Methaqualone elicits muscle-relaxant, sedative, and anticonvulsant effects at different dose levels. At low, nonsedative doses the drug produces anticonvulsant effects, and at higher doses, muscle-relaxant and sedative effects. It appears that the mechanism(s) of action of methaqualone in on GABA deficiency or receptor blockade, rather than on glycine receptors.

  17. Genetic Modulation of GABA Levels in the Anterior Cingulate Cortex by GAD1 and COMT

    PubMed Central

    Marenco, Stefano; Savostyanova, Antonina A; van der Veen, Jan Willem; Geramita, Matthew; Stern, Alexa; Barnett, Alan S; Kolachana, Bhaskar; Radulescu, Eugenia; Zhang, Fengyu; Callicott, Joseph H; Straub, Richard E; Shen, Jun; Weinberger, Daniel R

    2010-01-01

    γ-Aminobutyric acid (GABA)-ergic transmission is critical for normal cortical function and is likely abnormal in a variety of neuropsychiatric disorders. We tested the in vivo effects of variations in two genes implicated in GABA function on GABA concentrations in prefrontal cortex of living subjects: glutamic acid decarboxylase 1 (GAD1), which encodes GAD67, and catechol-o-methyltransferase (COMT), which regulates synaptic dopamine in the cortex. We studied six single nucleotide polymorphisms (SNPs) in GAD1 previously associated with risk for schizophrenia or cognitive dysfunction and the val158met polymorphism in COMT in 116 healthy volunteers using proton magnetic resonance spectroscopy. Two of the GAD1 SNPs (rs1978340 (p=0.005) and rs769390 (p=0.004)) showed effects on GABA levels as did COMT val158met (p=0.04). We then tested three SNPs in GAD1 (rs1978340, rs11542313, and rs769390) for interaction with COMT val158met based on previous clinical results. In this model, rs11542313 and COMT val158met showed significant main effects (p=0.001 and 0.003, respectively) and a trend toward a significant interaction (p=0.05). Interestingly, GAD1 risk alleles for schizophrenia were associated with higher GABA/Cre, and Val-Val homozygotes had high GABA/Cre levels when on a GAD1 risk genotype background (N=6). These results support the importance of genetic variation in GAD1 and COMT in regulating prefrontal cortical GABA function. The directionality of the effects, however, is inconsistent with earlier evidence of decreased GABA activity in schizophrenia. PMID:20357758

  18. Mutations in y-aminobutyric acid (GABA) transaminase genes in plants or Pseudomonas syringae reduce bacterial virulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas syringae pv. tomato DC3000 is a bacterial pathogen of Arabidopsis and tomato that grows in the apoplast. The non-protein amino acid '-amino butyric acid (GABA) is produced by Arabidopsis and tomato and is the most abundant amino acid in the apoplastic fluid of tomato. The DC3000 genome h...

  19. The central nervous system convulsant pentylenetetrazole stimulates gamma-aminobutyric acid (GABA)-activated current in picrotoxin-resistant GABA(A) receptors in HEK293 cells.

    PubMed

    Dibas, M I; Dillon, G H

    2000-05-19

    We tested the ability of the central nervous system convulsant pentylenetetrazole (PTZ) to inhibit gamma-aminobutyric acid (GABA)-gated current in receptors expressing a mutation that rendered them resistant to picrotoxin. Consistent with previous reports, receptors expressing beta2(T246F), along with alpha3 and gamma2 subunits, resulted in a greatly diminished sensitivity to picrotoxin. Sensitivity to PTZ was completely abolished in the mutant receptor, confirming the hypothesis that PTZ acts at the picrotoxin site. Quite unexpected, however, was our finding that PTZ elicited marked stimulation (up to 400% of control) in the mutated receptors. This stimulatory effect was not mediated via an interaction with the benzodiazepine site, as preincubation with the benzodiazepine antagonist flumazenil did not block the PTZ-induced stimulation. Our results reveal the existence of a novel stimulatory domain of PTZ in GABA(A) receptors.

  20. Effects of NaCl Replacement with Gamma-Aminobutyric acid (GABA) on the Quality Characteristics and Sensorial Properties of Model Meat Products

    PubMed Central

    Chun, Ji-Yeon; Cho, Hyung-Yong; Min, Sang-Gi

    2014-01-01

    This study investigated the effects of γ-aminobutylic acid (GABA) on the quality and sensorial properties of both the GABA/NaCl complex and model meat products. GABA/NaCl complex was prepared by spray-drying, and the surface dimensions, morphology, rheology, and saltiness were characterized. For model meat products, pork patties were prepared by replacing NaCl with GABA. For characteristics of the complex, increasing GABA concentration increased the surface dimensions of the complex. However, GABA did not affect the rheological properties of solutions containing the complex. The addition of 2% GABA exhibited significantly higher saltiness than the control (no GABA treatment). In the case of pork patties, sensory testing indicated that the addition of GABA decreased the saltiness intensity. Both the intensity of juiciness and tenderness of patties containing GABA also scored lower than the control, based on the NaCl reduction. These results were consistent with the quality characteristics (cooking loss and texture profile analysis). Nevertheless, overall acceptability of the pork patties showed that up to 1.5%, patties containing GABA did not significantly differ from the control. Consequently, the results indicated that GABA has a potential application in meat products, but also manifested a deterioration of quality by the NaCl reduction, which warrants further exploration. PMID:26761294

  1. Presence of Gamma-Aminobutyric Acid (Gaba) in the Pedal Mucus of the Critically Endangered Species Patella ferruginea.

    PubMed

    Rivera-Ingraham, G A; Espinosa, F; Krock, B

    2015-05-01

    Patella ferruginea is a giant patellid limpet endemic to the Mediterranean Sea. It presently is in danger of extinction, and many have called for developing conservation measures including the mass production of spats for re-introduction projects. However, so far all attempts have been relatively unsuccessful. Previous work analyzing the effects of gamma-aminobutyric acid (GABA) on the recruitment of patellid limpets has shown that larvae respond to the presence of this signaling molecule. This response could explain the gregarious distribution typical of this species. In the present study, we demonstrated that GABA is naturally secreted by P. ferruginea in the pedal mucus. GABA is preferentially secreted during the summer, coinciding with the reproductive resting period of the species. Further research should aim to analyze the effects of GABA on larval development and metamorphosis in order to assess its potential use to improve conservation efforts.

  2. Effect of GABA on oxidative stress in the skeletal muscles and plasma free amino acids in mice fed high-fat diet.

    PubMed

    Xie, Z X; Xia, S F; Qiao, Y; Shi, Y H; Le, G W

    2015-06-01

    Increased levels of plasma free amino acids (pFAAs) can disturb the blood glucose levels in patients with obesity, diabetes mellitus and metabolic syndrome (MS) and are associated with enhanced protein oxidation. Oxidation of proteins, especially in the muscles, can promote protein degradation and elevate the levels of pFAAs. Gamma-aminobutyric acid (GABA), a food additive, can reduce high-fat diet (HFD)-induced hyperglycaemia; however, the mechanisms remain unclear. The aim of this study was to evaluate the effects of GABA on protein oxidation and pFAAs changes. One hundred male C57BL/6 mice were randomly divided into five groups that were fed with control diet, HFD and HFD supplied with 0.2%, 0.12% and 0.06% GABA in drinking water for 20 weeks respectively. HFD feeding led to muscular oxidative stress, protein oxidation, pFAA disorders, hyperglycaemia and augmented plasma GABA levels. Treatment with GABA restored normally fasting blood glucose level and dose-dependently inhibited body weight gains, muscular oxidation and protein degradation. While medium and low doses of GABA mitigated HFD-induced pFAA disorders, the high dose of GABA deteriorated the pFAA disorders. Medium dose of GABA increased the levels of GABA, but high dose of GABA reduced the levels of plasma GABA and increased the activity of succinic semialdehyde dehydrogenase in the liver. Therefore, treatment with GABA mitigated HFD-induced hyperglycaemia probably by repairing HFD-induced muscular oxidative stress and pFAA disorders in mice. Our data also suggest that an optimal dose of GABA is crucial for the prevention of excess GABA-related decrease in the levels of pFAA and GABA as well as obesity. PMID:25266692

  3. Oxo-4-methylpentanoic acid directs the metabolism of GABA into the Krebs cycle in rat pancreatic islets.

    PubMed

    Hernández-Fisac, Inés; Fernández-Pascual, Sergio; Ortsäter, Henrik; Pizarro-Delgado, Javier; Martín del Río, Rafael; Bergsten, Peter; Tamarit-Rodriguez, Jorge

    2006-11-15

    OMP (oxo-4-methylpentanoic acid) stimulates by itself a biphasic secretion of insulin whereas L-leucine requires the presence of L-glutamine. L-Glutamine is predominantly converted into GABA (gamma-aminobutyric acid) in rat islets and L-leucine seems to promote its metabolism in the 'GABA shunt' [Fernández-Pascual, Mukala-Nsengu-Tshibangu, Martín del Río and Tamarit-Rodríguez (2004) Biochem. J. 379, 721-729]. In the present study, we have investigated how 10 mM OMP affects L-glutamine metabolism to uncover possible differences with L-leucine that might help to elucidate whether they share a common mechanism of stimulation of insulin secretion. In contrast with L-leucine, OMP alone stimulated a biphasic insulin secretion in rat perifused islets and decreased the islet content of GABA without modifying its extracellular release irrespective of the concentration of L-glutamine in the medium. GABA was transaminated to L-leucine whose intracellular concentration did not change because it was efficiently transported out of the islet cells. The L-[U-14C]-Glutamine (at 0.5 and 10.0 mM) conversion to 14CO2 was enhanced by 10 mM OMP within 30% and 70% respectively. Gabaculine (250 microM), a GABA transaminase inhibitor, suppressed OMP-induced oxygen consumption but not L-leucine- or glucose-stimulated respiration. It also suppressed the OMP-induced decrease in islet GABA content and the OMP-induced increase in insulin release. These results support the view that OMP promotes islet metabolism in the 'GABA shunt' generating 2-oxo-glutarate, in the branched-chain alpha-amino acid transaminase reaction, which would in turn trigger GABA deamination by GABA transaminase. OMP, but not L-leucine, suppressed islet semialdehyde succinic acid reductase activity and this might shift the metabolic flux of the 'GABA shunt' from gamma-hydroxybutyrate to succinic acid production.

  4. GABA-BZD Receptor Modulating Mechanism of Panax quinquefolius against 72-h Sleep Deprivation Induced Anxiety like Behavior: Possible Roles of Oxidative Stress, Mitochondrial Dysfunction and Neuroinflammation

    PubMed Central

    Chanana, Priyanka; Kumar, Anil

    2016-01-01

    Rationale: Panax quinquefolius (American Ginseng) is known for its therapeutic potential against various neurological disorders, but its plausible mechanism of action still remains undeciphered. GABA (Gamma Amino Butyric Acid) plays an important role in sleep wake cycle homeostasis. Thus, there exists rationale in exploring the GABA-ergic potential of Panax quinquefolius as neuroprotective strategy in sleep deprivation induced secondary neurological problems. Objective: The present study was designed to explore the possible GABA-ergic mechanism in the neuro-protective effect of Panax quinquefolius against 72-h sleep deprivation induced anxiety like behavior, oxidative stress, mitochondrial dysfunction, HPA-axis activation and neuroinflammation. Materials and Methods: Male laca mice were sleep deprived for 72-h by using Grid suspended over water method. Panax quinquefolius (American Ginseng 50, 100, and 200 mg/kg) was administered alone and in combination with GABA modulators (GABA Cl− channel inhibitor, GABA-benzodiazepine receptor inhibitor and GABAA agonist) for 8 days, starting 5 days prior to 72-h sleep deprivation period. Various behavioral (locomotor activity, mirror chamber test), biochemical (lipid peroxidation, reduced glutathione, catalase, nitrite levels), mitochondrial complexes, neuroinflammation marker (Tumor Necrosis Factor, TNF-alpha), serum corticosterone, and histopathological sections of brains were assessed. Results: Seventy two hours sleep deprivation significantly impaired locomotor activity, caused anxiety-like behavior, conditions of oxidative stress, alterations in mitochondrial enzyme complex activities, raised serum corticosterone levels, brain TNFα levels and led to neuroinflammation like signs in discrete brain areas as compared to naive group. Panax quinquefolius (100 and 200 mg/kg) treatment restored the behavioral, biochemical, mitochondrial, molecular and histopathological alterations. Pre-treatment of GABA Cl− channel

  5. Reproducibility and effect of tissue composition on cerebellar γ-aminobutyric acid (GABA) MRS in an elderly population.

    PubMed

    Long, Zaiyang; Dyke, Jonathan P; Ma, Ruoyun; Huang, Chaorui C; Louis, Elan D; Dydak, Ulrike

    2015-10-01

    MRS provides a valuable tool for the non-invasive detection of brain γ-aminobutyric acid (GABA) in vivo. GABAergic dysfunction has been observed in the aging cerebellum. The study of cerebellar GABA changes is of considerable interest in understanding certain age-related motor disorders. However, little is known about the reproducibility of GABA MRS in an aged population. Therefore, this study aimed to explore the feasibility and reproducibility of GABA MRS in the aged cerebellum at 3.0 T and to examine the effect of differing tissue composition on GABA measurements. MRI and (1)H MRS examinations were performed on 10 healthy elderly volunteers (mean age, 75.2 ± 6.5 years) using a 3.0-T Siemens Tim Trio scanner. Among them, five subjects were scanned twice to assess the short-term reproducibility. The MEGA-PRESS (Mescher-Garwood point-resolved spectroscopy) J-editing sequence was used for GABA detection in two volumes of interest (VOIs) in the left and right cerebellar dentate. MRS data processing and quantification were performed with LCModel 6.3-0L using two separate basis sets, generated from density matrix simulations using published values for chemical shifts and J couplings. Raw metabolite levels from LCModel outputs were corrected for cerebrospinal fluid contamination and relaxation. GABA-edited spectra yielded robust and stable GABA measurements with averaged intra-individual coefficients of variation for corrected GABA+ between 4.0 ± 2.8% and 13.4 ± 6.3%, and inter-individual coefficients of variation between 12.6% and 24.2%. In addition, there was a significant correlation between GABA+ obtained with the two LCModel basis sets. Overall, our results demonstrated the feasibility and reproducibility of cerebellar GABA-edited MRS at 3.0 T in an elderly population. This information might be helpful for studies using this technique to study GABA changes in normal or diseased aging brain, e.g. for power calculations and the interpretation of longitudinal

  6. Reproducibility and effect of tissue composition on cerebellar γ-aminobutyric acid (GABA) MRS in an elderly population.

    PubMed

    Long, Zaiyang; Dyke, Jonathan P; Ma, Ruoyun; Huang, Chaorui C; Louis, Elan D; Dydak, Ulrike

    2015-10-01

    MRS provides a valuable tool for the non-invasive detection of brain γ-aminobutyric acid (GABA) in vivo. GABAergic dysfunction has been observed in the aging cerebellum. The study of cerebellar GABA changes is of considerable interest in understanding certain age-related motor disorders. However, little is known about the reproducibility of GABA MRS in an aged population. Therefore, this study aimed to explore the feasibility and reproducibility of GABA MRS in the aged cerebellum at 3.0 T and to examine the effect of differing tissue composition on GABA measurements. MRI and (1)H MRS examinations were performed on 10 healthy elderly volunteers (mean age, 75.2 ± 6.5 years) using a 3.0-T Siemens Tim Trio scanner. Among them, five subjects were scanned twice to assess the short-term reproducibility. The MEGA-PRESS (Mescher-Garwood point-resolved spectroscopy) J-editing sequence was used for GABA detection in two volumes of interest (VOIs) in the left and right cerebellar dentate. MRS data processing and quantification were performed with LCModel 6.3-0L using two separate basis sets, generated from density matrix simulations using published values for chemical shifts and J couplings. Raw metabolite levels from LCModel outputs were corrected for cerebrospinal fluid contamination and relaxation. GABA-edited spectra yielded robust and stable GABA measurements with averaged intra-individual coefficients of variation for corrected GABA+ between 4.0 ± 2.8% and 13.4 ± 6.3%, and inter-individual coefficients of variation between 12.6% and 24.2%. In addition, there was a significant correlation between GABA+ obtained with the two LCModel basis sets. Overall, our results demonstrated the feasibility and reproducibility of cerebellar GABA-edited MRS at 3.0 T in an elderly population. This information might be helpful for studies using this technique to study GABA changes in normal or diseased aging brain, e.g. for power calculations and the interpretation of longitudinal

  7. Potato (Solanum tuberosum) juice exerts an anticonvulsant effect in mice through binding to GABA receptors.

    PubMed

    Muceniece, Ruta; Saleniece, Kristine; Krigere, Liga; Rumaks, Juris; Dzirkale, Zane; Mezhapuke, Rudolfs; Kviesis, Jorens; Mekss, Peteris; Klusa, Vija; Schiöth, Helgi B; Dambrova, Maija

    2008-04-01

    Naturally occurring benzodiazepines have been identified in regular food such as wheat and potato, but there is still no evidence that potato extracts can affect CNS responses in vivo. Here we found that undiluted potato juice and potato juice diluted with saline 1 : 2 administered 10 min intracisternally ( I. C.) and 30 min per os before bicuculline exerted significant anticonvulsant activity in the bicuculline-induced seizure threshold test in mice. In vitro, potato juice from different harvests at dilution series from 10 % to 0.000001 %, diluted 100,000-fold, displaced 50 % of gamma-aminobutyric acid (GABA) receptor ligand [ (3)H]GABA and diluted 40-fold displaced 50 % of [(3)H]flunitrazepam from binding sites in mice forebrain membranes. The low content of diazepam (0.04 +/- 0.01 mg/kg) determined by HPLC and mass spectrometry in the potato extracts could not sustain the anticonvulsant activity of potato juice in vivo; therefore we hypothesized that potato juice might contain GABA (A) receptor GABA-site active compounds. The findings of this study suggest that potato juice as well as potato taken as food may have the capacity of influencing brain GABA-ergic activity.

  8. Manganese accumulation in membrane fractions of primary astrocytes is associated with decreased γ-aminobutyric acid (GABA) uptake, and is exacerbated by oleic acid and palmitate.

    PubMed

    Fordahl, Steve C; Erikson, Keith M

    2014-05-01

    Manganese (Mn) exposure interferes with GABA uptake; however, the effects of Mn on GABA transport proteins (GATs) have not been identified. We sought to characterize how Mn impairs GAT function in primary rat astrocytes. Astrocytes exposed to Mn (500 μM) had significantly reduced (3)H-GABA uptake despite no change in membrane or cytosolic GAT3 protein levels. Co-treatment with 100 μM oleic or palmitic acids (both known to be elevated in Mn neurotoxicity), exacerbated the Mn-induced decline in (3)H-GABA uptake. Mn accumulation in the membrane fraction of astrocytes was enhanced with fatty acid administration, and was negatively correlated with (3)H-GABA uptake. Furthermore, control cells exposed to Mn only during the experimental uptake had significantly reduced (3)H-GABA uptake, and the addition of GABA (50 μM) blunted cytosolic Mn accumulation. These data indicate that reduced GAT function in astrocytes is influenced by Mn and fatty acids accumulating at or interacting with the plasma membrane.

  9. Exogenous γ-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase.

    PubMed

    Yu, Guang-Hui; Zou, Jie; Feng, Jing; Peng, Xiong-Bo; Wu, Ju-You; Wu, Ying-Liang; Palanivelu, Ravishankar; Sun, Meng-Xiang

    2014-07-01

    γ-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca(2+)-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca(2+) increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca(2+)-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca(2+)-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes.

  10. GABA shunt and polyamine degradation pathway on γ-aminobutyric acid accumulation in germinating fava bean (Vicia faba L.) under hypoxia.

    PubMed

    Yang, Runqiang; Guo, Qianghui; Gu, Zhenxin

    2013-01-01

    GABA shunt and polyamine degradation pathway on γ-aminobutyric acid (GABA) accumulation in germinating fava bean under hypoxia was investigated. GABA content, GAD and DAO activity were significantly increased under hypoxia treatment. Glu and polyamine contents enhanced largely and thus supplied as sufficient substrates for GABA formation. In contrast, GABA content decreased, mainly in the embryo, after removing the hypoxia stress. DAO activity, Glu and polyamines contents decreased, while an increment of GAD activity was observed. This indicated that GAD activity can be not only regulated by hypoxia, but by the rapid growth of embryo after the recovery from hypoxia stress. When treated with AG, DAO activity was almost inhibited completely, and the GABA content decreased by 32.96% and 32.07% after treated for 3 and 5 days, respectively. Hence, it can be inferred that about 30% of GABA formed in germinating fava bean under hypoxia was supplied by polyamine degradation pathway. PMID:23017406

  11. GABA shunt and polyamine degradation pathway on γ-aminobutyric acid accumulation in germinating fava bean (Vicia faba L.) under hypoxia.

    PubMed

    Yang, Runqiang; Guo, Qianghui; Gu, Zhenxin

    2013-01-01

    GABA shunt and polyamine degradation pathway on γ-aminobutyric acid (GABA) accumulation in germinating fava bean under hypoxia was investigated. GABA content, GAD and DAO activity were significantly increased under hypoxia treatment. Glu and polyamine contents enhanced largely and thus supplied as sufficient substrates for GABA formation. In contrast, GABA content decreased, mainly in the embryo, after removing the hypoxia stress. DAO activity, Glu and polyamines contents decreased, while an increment of GAD activity was observed. This indicated that GAD activity can be not only regulated by hypoxia, but by the rapid growth of embryo after the recovery from hypoxia stress. When treated with AG, DAO activity was almost inhibited completely, and the GABA content decreased by 32.96% and 32.07% after treated for 3 and 5 days, respectively. Hence, it can be inferred that about 30% of GABA formed in germinating fava bean under hypoxia was supplied by polyamine degradation pathway.

  12. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize

    PubMed Central

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L-1 and 50 mg L-1, in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms. PMID:27446149

  13. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize.

    PubMed

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L(-1) and 50 mg L(-1), in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms.

  14. Exogenous γ-aminobutyric Acid (GABA) Application Improved Early Growth, Net Photosynthesis, and Associated Physio-Biochemical Events in Maize.

    PubMed

    Li, Wu; Liu, Jianhua; Ashraf, Umair; Li, Gaoke; Li, Yuliang; Lu, Wenjia; Gao, Lei; Han, Fuguang; Hu, Jianguang

    2016-01-01

    γ-aminobutyric acid (GABA) is an endogenous signaling molecule and involved in growth regulations and plant development, however, a little information is available on the consequences of exogenous GABA application on growth, development, and associated physio-biochemical processes in maize. The present study examined the GABA-induced regulations in early growth, net photosynthetic rate, gas exchange, osmoregulation, and enzymatic activities in three maize cultivars, i.e., Yuecainuo 6, Zhengtian 68, and Yuecainuo 2. Two levels of GABA, i.e., 0 mg L(-1) and 50 mg L(-1), in solution form, with total application volume of 100 ml per pot containing 15 maize seedlings were exogenously applied. Results revealed that exogenous GABA application improved seedling growth in terms of seedling length and biomass accumulation in all maize cultivars at both 3 and 7 days after treatment (DAT). It also promoted net photosynthesis and variably affected gas exchange attributes, i.e., stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as leaves SPAD value. Furthermore, lipid peroxidation [in terms of malondialdehyde (MDA)] under GABA treated maize seedlings were also remained variable; however, osmolyte accumulation (protein and proline) and activities of anti-oxidants enzymes, i.e., super-oxide dismutase and peroxidase were also affected differently at both 3 and 7 DAT in all maize cultivars. Furthermore, enzymes involved in nitrogen metabolism, e.g., nitrate reductase and glutamine synthetase were improved. These results suggest the involvement of GABA in various physio-metablical mechanisms which might lead to improvement in morphological growth of maize. In future, research is still needed at molecular and genetic levels to unravel the involvement of GABA-mediated regulations in growth and its associated physio-biochemical mechanisms. PMID:27446149

  15. Determination of γ-Aminobutyric Acid (GABA) in Rambutan Fruit cv. Rongrian by HPLC-ELSD and Separation of GABA from Rambutan Fruit Using Dowex 50W-X8 Column.

    PubMed

    Meeploy, Maneerat; Deewatthanawong, Rujira

    2016-03-01

    A high-performance liquid chromatography method coupled with an evaporative light scattering detector (ELSD) was validated for the determination of γ-aminobutyric acid (GABA) in rambutan fruit without any sample pretreatment or derivatization. In the concentration range of 0.05-1.0 mg/mL GABA, the ELSD response was linear with a correlation coefficient (r) >0.999. Limit of detection and limit of quantitation were found to be 0.7 and 2.0 µg/mL, respectively. The method enabled the complete separation of GABA in the aqueous extract of rambutan flesh from the impurity peaks at 45.7 min. The recoveries of sample added GABA were obtained in the range of 92.0-99.3%. Intraday and interday relative standard deviations were <5.3%. Repeatability of the extraction process showed the acceptable precision. From the analysis of GABA content in rambutan flesh, 0.71 ± 0.23 mg of GABA was found in 1 g fresh weight. The recovery of GABA after passing through the Dowex 50W-X8 column was 96.65%. The analytical methodology could be potentially applied to the detection and quantification of GABA in other fruits and complex matrices when a sufficient quantity is available. PMID:26590236

  16. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0

    PubMed Central

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-01-01

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes. PMID:27212081

  17. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0

    NASA Astrophysics Data System (ADS)

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-05-01

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.

  18. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0.

    PubMed

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-05-23

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.

  19. Artificial Autopolyploidization Modifies the Tricarboxylic Acid Cycle and GABA Shunt in Arabidopsis thaliana Col-0.

    PubMed

    Vergara, Fredd; Kikuchi, Jun; Breuer, Christian

    2016-01-01

    Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid cycle (TCA) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the TCA and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes. PMID:27212081

  20. Efficient gamma-aminobutyric acid bioconversion by employing synthetic complex between glutamate decarboxylase and glutamate/GABA antiporter in engineered Escherichia coli.

    PubMed

    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.

  1. Co-localization of glutamic acid decarboxylase and vesicular GABA transporter in cytochrome oxidase patches of macaque striate cortex.

    PubMed

    Adams, Daniel L; Economides, John R; Horton, Jonathan C

    2015-01-01

    The patches in primary visual cortex constitute hot spots of metabolic activity, manifested by enhanced levels of cytochrome oxidase (CO) activity. They are also labeled preferentially by immunostaining for glutamic acid decarboxylase (GAD), γ-aminobutyric acid (GABA), and parvalbumin. However, calbindin shows stronger immunoreactivity outside patches. In light of this discrepancy, the distribution of the vesicular GABA transporter (VGAT) was examined in striate cortex of two normal macaques. VGAT immunoreactivity was strongest in layers 4B, 4Cα, and 5. In tangential sections, the distribution of CO, GAD, and VGAT was compared in layer 2/3. There was a close match between all three labels. This finding indicates that GABA synthesis is enriched in patches, and that inhibitory synapses are more active in patches than interpatches. PMID:26579566

  2. Evaluation of commercial soy sauce koji strains of Aspergillus oryzae for γ-aminobutyric acid (GABA) production.

    PubMed

    Ab Kadir, Safuan; Wan-Mohtar, Wan Abd Al Qadr Imad; Mohammad, Rosfarizan; Abdul Halim Lim, Sarina; Sabo Mohammed, Abdulkarim; Saari, Nazamid

    2016-10-01

    In this study, four selected commercial strains of Aspergillus oryzae were collected from soy sauce koji. These A. oryzae strains designated as NSK, NSZ, NSJ and NST shared similar morphological characteristics with the reference strain (A. oryzae FRR 1675) which confirmed them as A. oryzae species. They were further evaluated for their ability to produce γ-aminobutyric acid (GABA) by cultivating the spore suspension in a broth medium containing 0.4 % (w/v) of glutamic acid as a substrate for GABA production. The results showed that these strains were capable of producing GABA; however, the concentrations differed significantly (P < 0.05) among themselves. Based on the A. oryzae strains, highest GABA concentration was obtained from NSK (194 mg/L) followed by NSZ (63 mg/L), NSJ (51.53 mg/L) and NST (31.66 mg/L). Therefore, A. oryzae NSK was characterized and the sequence was found to be similar to A. oryzae and A. flavus with 99 % similarity. The evolutionary distance (K nuc) between sequences of identical fungal species was calculated and a phylogenetic tree prepared from the K nuc data showed that the isolate belonged to the A. oryzae species. This finding may allow the development of GABA-rich ingredients using A. oryzae NSK as a starter culture for soy sauce production.

  3. Evaluation of commercial soy sauce koji strains of Aspergillus oryzae for γ-aminobutyric acid (GABA) production.

    PubMed

    Ab Kadir, Safuan; Wan-Mohtar, Wan Abd Al Qadr Imad; Mohammad, Rosfarizan; Abdul Halim Lim, Sarina; Sabo Mohammed, Abdulkarim; Saari, Nazamid

    2016-10-01

    In this study, four selected commercial strains of Aspergillus oryzae were collected from soy sauce koji. These A. oryzae strains designated as NSK, NSZ, NSJ and NST shared similar morphological characteristics with the reference strain (A. oryzae FRR 1675) which confirmed them as A. oryzae species. They were further evaluated for their ability to produce γ-aminobutyric acid (GABA) by cultivating the spore suspension in a broth medium containing 0.4 % (w/v) of glutamic acid as a substrate for GABA production. The results showed that these strains were capable of producing GABA; however, the concentrations differed significantly (P < 0.05) among themselves. Based on the A. oryzae strains, highest GABA concentration was obtained from NSK (194 mg/L) followed by NSZ (63 mg/L), NSJ (51.53 mg/L) and NST (31.66 mg/L). Therefore, A. oryzae NSK was characterized and the sequence was found to be similar to A. oryzae and A. flavus with 99 % similarity. The evolutionary distance (K nuc) between sequences of identical fungal species was calculated and a phylogenetic tree prepared from the K nuc data showed that the isolate belonged to the A. oryzae species. This finding may allow the development of GABA-rich ingredients using A. oryzae NSK as a starter culture for soy sauce production. PMID:27541157

  4. Accumulation of GABAergic Neurons, Causing a Focal Ambient GABA Gradient, and Downregulation of KCC2 Are Induced During Microgyrus Formation in a Mouse Model of Polymicrogyria

    PubMed Central

    Wang, Tianying; Kumada, Tatsuro; Morishima, Toshitaka; Iwata, Satomi; Kaneko, Takeshi; Yanagawa, Yuchio; Yoshida, Sachiko; Fukuda, Atsuo

    2014-01-01

    Although focal cortical malformations are considered neuronal migration disorders, their formation mechanisms remain unknown. We addressed how the γ-aminobutyric acid (GABA)ergic system affects the GABAergic and glutamatergic neuronal migration underlying such malformations. A focal freeze-lesion (FFL) of the postnatal day zero (P0) glutamic acid decarboxylase–green fluorescent protein knock-in mouse neocortex produced a 3- or 4-layered microgyrus at P7. GABAergic interneurons accumulated around the necrosis including the superficial region during microgyrus formation at P4, whereas E17.5-born, Cux1-positive pyramidal neurons outlined the GABAergic neurons and were absent from the superficial layer, forming cell-dense areas in layer 2 of the P7 microgyrus. GABA imaging showed that an extracellular GABA level temporally increased in the GABAergic neuron-positive area, including the necrotic center, at P4. The expression of the Cl– transporter KCC2 was downregulated in the microgyrus-forming GABAergic and E17.5-born glutamatergic neurons at P4; these cells may need a high intracellular Cl– concentration to induce depolarizing GABA effects. Bicuculline decreased the frequency of spontaneous Ca2+ oscillations in these microgyrus-forming cells. Thus, neonatal FFL causes specific neuronal accumulation, preceded by an increase in ambient GABA during microgyrus formation. This GABA increase induces GABAA receptor-mediated Ca2+ oscillation in KCC2-downregulated microgyrus-forming cells, as seen in migrating cells during early neocortical development. PMID:23246779

  5. Impact of Precooling and Controlled-Atmosphere Storage on γ-Aminobutyric Acid (GABA) Accumulation in Longan (Dimocarpus longan Lour.) Fruit.

    PubMed

    Zhou, Molin; Ndeurumio, Kessy H; Zhao, Lei; Hu, Zhuoyan

    2016-08-24

    Longan (Dimocarpus longan Lour.) fruit cultivars 'Chuliang' and 'Shixia' were analyzed for γ-aminobutyric acid (GABA) accumulation after precooling and in controlled-atmosphere storage. Fruit were exposed to 5% O2 plus 3%, 5%, or 10% CO2 at 4 °C, and GABA and associated enzymes, aril firmness, and pericarp color were measured. Aril softening and pericarp browning were delayed by 5% CO2 + 5% O2. GABA concentrations and glutamate decarboxylase (GAD; EC 4.1.1.15) activities declined during storage at the higher-CO2 treatments. However, GABA aminotransferase (GABA-T; EC 2.6.1.19) activities in elevated CO2-treated fruit fluctuated during storage. GABA concentrations increased after precooling treatments. GAD activity and GABA-T activity were different between cultivars after precooling. GABA concentrations in fruit increased after 3 days of 10% CO2 + 5% O2 treatment and then declined as storage time increased. GABA accumulation was associated with stimulation of GAD activity rather than inhibition of GABA-T activity.

  6. Impact of Precooling and Controlled-Atmosphere Storage on γ-Aminobutyric Acid (GABA) Accumulation in Longan (Dimocarpus longan Lour.) Fruit.

    PubMed

    Zhou, Molin; Ndeurumio, Kessy H; Zhao, Lei; Hu, Zhuoyan

    2016-08-24

    Longan (Dimocarpus longan Lour.) fruit cultivars 'Chuliang' and 'Shixia' were analyzed for γ-aminobutyric acid (GABA) accumulation after precooling and in controlled-atmosphere storage. Fruit were exposed to 5% O2 plus 3%, 5%, or 10% CO2 at 4 °C, and GABA and associated enzymes, aril firmness, and pericarp color were measured. Aril softening and pericarp browning were delayed by 5% CO2 + 5% O2. GABA concentrations and glutamate decarboxylase (GAD; EC 4.1.1.15) activities declined during storage at the higher-CO2 treatments. However, GABA aminotransferase (GABA-T; EC 2.6.1.19) activities in elevated CO2-treated fruit fluctuated during storage. GABA concentrations increased after precooling treatments. GAD activity and GABA-T activity were different between cultivars after precooling. GABA concentrations in fruit increased after 3 days of 10% CO2 + 5% O2 treatment and then declined as storage time increased. GABA accumulation was associated with stimulation of GAD activity rather than inhibition of GABA-T activity. PMID:27412947

  7. gamma-Aminobutyric acidA (GABAA) receptors modulate [3H]GABA release from isolated neuronal growth cones in the rat.

    PubMed

    Lockerbie, R O; Gordon-Weeks, P R

    1985-04-19

    Potassium-induced release of gamma-[3H]aminobutyric acid [( 3H]GABA) from a growth cone-enriched fraction isolated from neonatal rat forebrain was inhibited by the GABA mimetic muscimol in a dose-dependent manner (IC50 15 nM). The GABA antagonist bicuculline completely reversed the effect of muscimol. Bicuculline alone slightly potentiated the K+-induced release of [3H]GABA. Baclofen, a proposed selective agonist for a bicuculline-insensitive GABAB receptor, was found to cause only a slight reduction in the K+-induced release of [3H]GABA. These results are compatible with the presence of a negative feedback mechanism mediated by GABAA receptors for controlling [3H]GABA release from growth cones of the developing rat forebrain.

  8. Neurons and glia in cat superior colliculus accumulate [3H]gamma-aminobutyric acid (GABA).

    PubMed

    Mize, R R; Spencer, R F; Sterling, P

    1981-11-01

    We have examined by autoradiography the labeling pattern in the cat superior colliculus following injection of tritiated gamma-aminobutyric acid (GABA). Silver grains were heavily distributed within the zonal layer and the upper 200 micrometer of the superficial gray. Fewer grains were observed deeper within the superficial gray, and still fewer were found within the optic and intermediate gray layers. The accumulation of label was restricted to certain classes of neuron and glia. Densely labeled neurons were small (8-12 micrometer in diameter) and located primarily within the upper 200 micrometer. Dark oligodendrocytes and astrocytes showed a moderate accumulation of label while pale oligodendrocytes and microglia were unlabeled. Label was also selectively accumulated over several other types of profile within the neuropil, including presynaptic dendrites, axons, and axon terminals.

  9. Enhancement of γ-aminobutyric acid (GABA) in Nham (Thai fermented pork sausage) using starter cultures of Lactobacillus namurensis NH2 and Pediococcus pentosaceus HN8.

    PubMed

    Ratanaburee, Anussara; Kantachote, Duangporn; Charernjiratrakul, Wilawan; Sukhoom, Ampaitip

    2013-10-15

    The aim was to produce Nham that was enriched with γ-aminobutyric acid (GABA); therefore two GABA producing lactic acid bacteria (Pediococcus pentosaceus HN8 and Lactobacillus namurensis NH2) were used as starter cultures. By using the central composite design (CCD) we showed that addition of 0.5% monosodium glutamate (MSG) together with an inoculum size of roughly 6logCFU/g of each of the two strains produced a maximal amounts of GABA (4051 mg/kg) in the 'GABA Nham' product. This was higher than any current popular commercial Nham product by roughly 8 times. 'GABA Nham' with the additions of both starters and MSG (TSM) supported maximum populations of lactic acid bacteria (LAB) with a minimum of yeasts and no staphylococci or molds when compared to the controls that had no addition of any starters or MSG (TNN), or only the addition of MSG (TNM), or with only the starter (TSN). Based on proximate analysis among the Nham sets, 'GABA Nham' was low in fat, carbohydrate and energy although its texture and color were slightly different from the control (TNN). However, sensory evaluations of 'GABA Nham' were more acceptable than the controls and commercial Nham products for all tested parameters. Hence, a unique novel 'GABA Nham' fermented pork sausage was successfully developed.

  10. Application of γ-aminobutyric acid demonstrates a protective role of polyamine and GABA metabolism in muskmelon seedlings under Ca(NO3)2 stress.

    PubMed

    Hu, Xiaohui; Xu, Zhiran; Xu, Weinan; Li, Jianming; Zhao, Ning; Zhou, Yue

    2015-07-01

    The effects of exogenous γ-aminobutyric acid (GABA) application on growth, polyamine and endogenous GABA metabolism in muskmelon leaves and roots were measured. Plants were treated under control or 80 mM Ca(NO3)2 stress conditions with or without foliar spraying 50 mM GABA. Ca(NO3)2 stress significantly suppressed seedling growth and GABA transaminase activity, and enhanced glutamate decarboxylase (GAD) activity and endogenous GABA levels. Polyamine (PA) biosynthesis and degradation capacity increased in parallel with increasing GAD activity. Exogenous GABA application effectively alleviated the growth inhibition caused by Ca(NO3)2 stress, and significantly enhanced the activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), polyamine oxidase (PAO), and diamine oxidase (DAO). Exogenous GABA also significantly reduced the accumulation of free putrescine (Put) and increased the levels of free spermidine (Spd) and spermine (Spm) in leaves, which improved the capacity for polyamine biosynthesis. Application of exogenous GABA under Ca(NO3)2 stress enables the plants to maintain a higher ratio of free Spd and free Spm with respect to free Put. Our data suggest that exogenous GABA has an important role in improving muskmelon seedling tolerance to Ca(NO3)2 stress by improving biosynthesis of PAs and GABA, and by preventing PA degradation. There is a potential positive feedback mechanism that results from higher endogenous GABA content and the combined effects of Ca(NO3)2 stress and exogenous GABA, which coordinately alleviate Ca(NO3)2 stress injury by enhancing PA biosynthesis and converting free Put to an insoluble bound PA form, and reduce PA degradation in muskmelon seedlings.

  11. α4βδ GABA(A) receptors are high-affinity targets for γ-hydroxybutyric acid (GHB).

    PubMed

    Absalom, Nathan; Eghorn, Laura F; Villumsen, Inge S; Karim, Nasiara; Bay, Tina; Olsen, Jesper V; Knudsen, Gitte M; Bräuner-Osborne, Hans; Frølund, Bente; Clausen, Rasmus P; Chebib, Mary; Wellendorph, Petrine

    2012-08-14

    γ-Hydroxybutyric acid (GHB) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. However, the mechanistic links between these lines of data are unknown. To identify molecular targets for specific GHB high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several GABA(A) receptor subunits as possible candidates. A subsequent functional screening of various recombinant GABA(A) receptors in Xenopus laevis oocytes using the two-electrode voltage clamp technique showed GHB to be a partial agonist at αβδ- but not αβγ-receptors, proving that the δ-subunit is essential for potency and efficacy. GHB showed preference for α4 over α(1,2,6)-subunits and preferably activated α4β1δ (EC(50) = 140 nM) over α4β(2/3)δ (EC(50) = 8.41/1.03 mM). Introduction of a mutation, α4F71L, in α4β1(δ)-receptors completely abolished GHB but not GABA function, indicating nonidentical binding sites. Radioligand binding studies using the specific GHB radioligand [(3)H](E,RS)-(6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid showed a 39% reduction (P = 0.0056) in the number of binding sites in α4 KO brain tissue compared with WT controls, corroborating the direct involvement of the α4-subunit in high-affinity GHB binding. Our data link specific GHB forebrain binding sites with α4-containing GABA(A) receptors and postulate a role for extrasynaptic α4δ-containing GABA(A) receptors in GHB pharmacology and physiology. This finding will aid in elucidating the molecular mechanisms behind the proposed function of GHB as a neurotransmitter and its unique therapeutic effects in narcolepsy and alcoholism.

  12. The effects of lowered extracellular sodium on gamma-aminobutyric acid (GABA)-induced currents of Muller (glial) cells of the skate retina.

    PubMed

    Qian, H; Malchow, R P; Ripps, H

    1993-04-01

    1. The effects of external sodium on GABA-induced chloride currents were examined with whole-cell voltage-clamp recordings obtained from enzymatically dissociated solitary Muller cells in culture. Our goal was to determine whether a sodium-dependent GABA uptake mechanism influences the GABAa-mediated responses of skate Muller cells. 2. At low concentrations of GABA (0.01 to 0.5 microM), removal of sodium from the external solution resulted in a marked increase in the ligand-gated currents mediated by activation of GABAa receptors. The enhancement by lowered sodium was greatest at hyperpolarizing potentials and decreased progressively as the cell was depolarized. 3. The reversal potential for the GABA-induced response was not significantly altered by the removal of sodium, suggesting that sodium ions did not directly contribute to the GABAa-mediated current. 4. Lowering external sodium had no effect on the currents induced by the GABAa-agonist muscimol, consistent with its much lower affinity for the GABA transport carrier. 5. Application of the GABA uptake blocker nipecotic acid also abolished the effects of lowered sodium. 6. These findings suggest that the effects of lowered external sodium resulted from a decrease in the uptake of GABA into the Muller cells, thus raising the effective concentration of GABA acting upon the GABAa receptors. PMID:8394215

  13. Expression of the γ-Aminobutyric Acid (GABA) Plasma Membrane Transporter-1 in Monkey and Human Retina

    PubMed Central

    Casini, Giovanni; Rickman, Dennis W.; Brecha, Nicholas C.

    2010-01-01

    Purpose To determine the expression pattern of the predominant γ-aminobutyric acid (GABA) plasma membrane transporter GAT-1 in Old World monkey (Macaca mulatta) and human retina. Methods GAT-1 was localized in retinal sections by using immunohistochemical techniques with fluorescence and confocal microscopy. Double-labeling studies were performed with the GAT-1 antibody using antibodies to GABA, vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH), and the bipolar cell marker Mab115A10. Results The pattern of GAT-1 immunostaining was similar in human and monkey retinas. Numerous small immunoreactive somata were in the inner nuclear layer (INL) and were present rarely in the inner plexiform layer (IPL) of all retinal regions. Medium GAT-1 somata were in the ganglion cell layer in the parafoveal and peripheral retinal regions. GAT-1 fibers were densely distributed throughout the IPL. Varicose processes, originating from both the IPL and somata in the INL, arborized in the outer plexiform layer (OPL), forming a sparse network in all retinal regions, except the fovea. Sparsely occurring GAT-1 processes were in the nerve fiber layer in parafoveal regions and near the optic nerve head but not in the optic nerve. In the INL, 99% of the GAT-1 somata contained GABA, and 66% of the GABA immunoreactive somata expressed GAT-1. GAT-1 immunoreactivity was in all VIP-containing cells, but it was absent in TH-immunoreactive amacrine cells and in Mab115A10 immunoreactive bipolar cells. Conclusions GAT-1 in primate retinas is expressed by amacrine and displaced amacrine cells. The predominant expression of GAT-1 in the inner retina is consistent with the idea that GABA transporters influence neurotransmission and thus participate in visual information processing in the retina. PMID:16565409

  14. Analogues of gamma-aminobutyric acid (GABA) and trans-4-aminocrotonic acid (TACA) substituted in the 2 position as GABAC receptor antagonists.

    PubMed

    Chebib, M; Vandenberg, R J; Johnston, G A

    1997-12-01

    1. gamma-Aminobutyric acid (GABA) and trans-4-aminocrotonic acid (TACA) have been shown to activate GABAC receptors. In this study, a range of C2, C3, C4 and N-substituted GABA and TACA analogues were examined for activity at GABAC receptors. 2. The effects of these compounds were examined by use of electrophysiological recording from Xenopus oocytes expressing the human rho 1 subunit of GABAC receptors with the two-electrode voltage-clamp method. 3. trans-4-Amino-2-fluorobut-2-enoic acid was found to be a potent agonist (KD = 2.43 microM). In contrast, trans-4-amino-2-methylbut-2-enoic acid was found to be a moderately potent antagonist (IC50 = 31.0 microM and KB = 45.5 microM). These observations highlight the possibility that subtle structural substitutions may change an agonist into an antagonist. 4. 4-Amino-2-methylbutanoic acid (KD = 189 microM), 4-amino-2-methylenebutanoic acid (KD = 182 microM) and 4-amino-2-chlorobutanoic acid (KD = 285 microM) were weak partial agonists. The intrinsic activities of these compounds were 12.1%, 4.4% and 5.2% of the maximal response of GABA, respectively. These compounds more effectively blocked the effects of the agonist, GABA, giving rise to KB values of 53 microM and 101 microM, respectively. 5. The sulphinic acid analogue of GABA, homohypotaurine, was found to be a potent partial agonist (KD = 4.59 microM, intrinsic activity 69%). 6. It was concluded that substitution of a methyl or a halo group in the C2 position of GABA or TACA is tolerated at GABAC receptors. However, there was dramatic loss of activity when these groups were substituted at the C3, C4 and nitrogen positions of GABA and TACA. 7. Molecular modelling studies on a range of active and inactive compounds indicated that the agonist/competitive antagonist binding site of the GABAC receptor may be smaller than that of the GABAA and GABAB receptors. It is suggested that only compounds that can attain relatively flat conformations may bind to the GABAC receptor

  15. Dual effects of slightly acidic electrolyzed water (SAEW) treatment on the accumulation of γ-aminobutyric acid (GABA) and rutin in germinated buckwheat.

    PubMed

    Hao, Jianxiong; Wu, Tongjiao; Li, Huiying; Wang, Wei; Liu, Haijie

    2016-06-15

    In the present study, the dual effects of slightly acidic electrolyzed water (SAEW) treatment on γ-aminobutyric acid (GABA) and rutin accumulation of germinated buckwheat were evaluated during germination. The results showed that SAEW treatment (pH 5.83, ACC of 20.3 mg/L) could promote the accumulation of GABA and rutin in germinated buckwheat. The GABA and rutin contents of SAEW-germinated buckwheat reached 143.20 and 739.9 mg/100 g respectively, which is significantly higher than those of control (P<0.05). Moreover, SAEW treatment could increase the activity of glutamic acid decarboxylase (GAD) and phenylalanine ammonialyase (PAL) and thus result in the GABA and rutin accumulation of germinated buckwheat. The results suggested that SAEW treatment could promote the rutin accumulation of germinated buckwheat by influencing phenylpropanoid secondary metabolic pathway instead of the inhibition of rutin degrading enzyme (RDE) activity. In addition, SAEW treatment had no adverse impact on the sprouts growth and could reduce the microbial populations of germinated buckwheat during germination.

  16. Dual effects of slightly acidic electrolyzed water (SAEW) treatment on the accumulation of γ-aminobutyric acid (GABA) and rutin in germinated buckwheat.

    PubMed

    Hao, Jianxiong; Wu, Tongjiao; Li, Huiying; Wang, Wei; Liu, Haijie

    2016-06-15

    In the present study, the dual effects of slightly acidic electrolyzed water (SAEW) treatment on γ-aminobutyric acid (GABA) and rutin accumulation of germinated buckwheat were evaluated during germination. The results showed that SAEW treatment (pH 5.83, ACC of 20.3 mg/L) could promote the accumulation of GABA and rutin in germinated buckwheat. The GABA and rutin contents of SAEW-germinated buckwheat reached 143.20 and 739.9 mg/100 g respectively, which is significantly higher than those of control (P<0.05). Moreover, SAEW treatment could increase the activity of glutamic acid decarboxylase (GAD) and phenylalanine ammonialyase (PAL) and thus result in the GABA and rutin accumulation of germinated buckwheat. The results suggested that SAEW treatment could promote the rutin accumulation of germinated buckwheat by influencing phenylpropanoid secondary metabolic pathway instead of the inhibition of rutin degrading enzyme (RDE) activity. In addition, SAEW treatment had no adverse impact on the sprouts growth and could reduce the microbial populations of germinated buckwheat during germination. PMID:26868552

  17. Systematic analysis of γ-aminobutyric acid (GABA) metabolism and function in the social amoeba Dictyostelium discoideum.

    PubMed

    Wu, Yuantai; Janetopoulos, Chris

    2013-05-24

    While GABA has been suggested to regulate spore encapsulation in the social amoeba Dictyostelium discoideum, the metabolic profile and other potential functions of GABA during development remain unclear. In this study, we investigated the homeostasis of GABA metabolism by disrupting genes related to GABA metabolism and signaling. Extracellular levels of GABA are tightly regulated during early development, and GABA is generated by the glutamate decarboxylase, GadB, during growth and in early development. However, overexpression of the prespore-specific homologue, GadA, in the presence of GadB reduces production of extracellular GABA. Perturbation of extracellular GABA levels delays the process of aggregation. Cytosolic GABA is degraded by the GABA transaminase, GabT, in the mitochondria. Disruption of a putative vesicular GABA transporter (vGAT) homologue DdvGAT reduces secreted GABA. We identified the GABAB receptor-like family member GrlB as the major GABA receptor during early development, and either disruption or overexpression of GrlB delays aggregation. This delay is likely the result of an abolished pre-starvation response and late expression of several "early" developmental genes. Distinct genes are employed for GABA generation during sporulation. During sporulation, GadA alone is required for generating GABA and DdvGAT is likely responsible for GABA secretion. GrlE but not GrlB is the GABA receptor during late development.

  18. GABA predicts visual intelligence.

    PubMed

    Cook, Emily; Hammett, Stephen T; Larsson, Jonas

    2016-10-01

    Early psychological researchers proposed a link between intelligence and low-level perceptual performance. It was recently suggested that this link is driven by individual variations in the ability to suppress irrelevant information, evidenced by the observation of strong correlations between perceptual surround suppression and cognitive performance. However, the neural mechanisms underlying such a link remain unclear. A candidate mechanism is neural inhibition by gamma-aminobutyric acid (GABA), but direct experimental support for GABA-mediated inhibition underlying suppression is inconsistent. Here we report evidence consistent with a global suppressive mechanism involving GABA underlying the link between sensory performance and intelligence. We measured visual cortical GABA concentration, visuo-spatial intelligence and visual surround suppression in a group of healthy adults. Levels of GABA were strongly predictive of both intelligence and surround suppression, with higher levels of intelligence associated with higher levels of GABA and stronger surround suppression. These results indicate that GABA-mediated neural inhibition may be a key factor determining cognitive performance and suggests a physiological mechanism linking surround suppression and intelligence. PMID:27495012

  19. Design, synthesis and SAR studies of GABA uptake inhibitors derived from 2-substituted pyrrolidine-2-yl-acetic acids.

    PubMed

    Steffan, Tobias; Renukappa-Gutke, Thejavathi; Höfner, Georg; Wanner, Klaus T

    2015-03-15

    In this paper, we disclose the design and synthesis of a series of 2-substituted pyrrolidine-2-yl-acetic acid as core structures and the N-arylalkyl derivatives thereof as potential GABA transport inhibitors. The 2-position in the side chain of pyrrolidine-2-yl-acetic acid derivatives was substituted with alkyl, hydroxy and amino groups to modulate the activity and selectivity to mGAT1 and mGAT4 proteins. SAR studies of the compounds performed for the four mouse GABA transporter proteins (mGAT1-mGAT4) implied significant potencies and subtype selectivities for 2-hydroxy-2-pyrrolidine-2-yl-acetic acid derivatives. The racemate rac-(u)-13c exhibited the highest potency (pIC50 5.67) at and selectivity for mGAT1 in GABA uptake assays. In fact, the potency of rac-(u)-13c at hGAT-1 (pIC50 6.14) was even higher than its potency at mGAT1. These uptake results for rac-(u)-13c are in line with the binding affinities to the aforesaid proteins mGAT1 (pKi 6.99) and hGAT-1 (pKi 7.18) determined by MS Binding Assay based on NO711 as marker quantified by LC-ESI-MS-MS analysis. Interestingly, the 2-hydroxy-2-pyrrolidine-2-yl-acetic acid rac-(u)-13d containing 2-{[tris(4-methoxyphenyl)]methoxy} ethyl group at the nitrogen atom of the pyrrolidine ring showed high potency at mGAT4 and a comparatively better selectivity for this protein (>15 against mGAT3) than the well known mGAT4 uptake inhibitor (S)-SNAP-5114.

  20. A Dendritic Golgi Satellite between ERGIC and Retromer.

    PubMed

    Mikhaylova, Marina; Bera, Sujoy; Kobler, Oliver; Frischknecht, Renato; Kreutz, Michael R

    2016-01-12

    The local synthesis of transmembrane proteins underlies functional specialization of dendritic microdomains in neuronal plasticity. It is unclear whether these proteins have access to the complete machinery of the secretory pathway following local synthesis. In this study, we describe a probe called pGolt that allows visualization of Golgi-related organelles for live imaging in neurons. We show that pGolt labels a widespread microsecretory Golgi satellite (GS) system that is, in contrast to Golgi outposts, present throughout basal and apical dendrites of all pyramidal neurons. The GS system contains glycosylation machinery and is localized between ERGIC and retromer. Synaptic activity restrains lateral movement of ERGIC, GS, and retromer close to one another, allowing confined processing of secretory cargo. Several synaptic transmembrane proteins pass through and recycle back to the GS system. Thus, the presence of an ER-ERGIC-GS-retromer microsecretory system in all neuronal dendrites enables autonomous local control of transmembrane protein synthesis and processing. PMID:26748700

  1. Gestational changes of GABA levels and GABA binding in the human uterus

    SciTech Connect

    Erdoe, S.L.; Villanyi, P.; Laszlo, A.

    1989-01-01

    The concentrations of gamma-aminobutyric acid (GABA), the activities of L-glutamate decarboxylase and GABA-transaminase, and the nature of the sodium-independent binding of GABA were examined in uterine tissue pieces obtained surgically from pregnant and non-pregnant women. GABA concentrations were reduced, while the activity of GABA-transaminase and the specific binding of (/sup 3/H)GABA significantly increased in specimens from pregnant subjects. These findings suggest some gestation-related functional role for the GABA system in the human uterus.

  2. Role of glutamic acid decarboxylase 67 in regulating cortical parvalbumin and GABA membrane transporter 1 expression: Implications for schizophrenia

    PubMed Central

    Curley, Allison A.; Eggan, Stephen M.; Lazarus, Matt S.; Huang, Z. Josh; Volk, David W.; Lewis, David A.

    2012-01-01

    Markers of GABA neurotransmission are altered in multiple regions of the neocortex in individuals with schizophrenia. Lower levels of glutamic acid decarboxylase 67 (GAD67) mRNA and protein, which is responsible for most cortical GABA synthesis, are accompanied by lower levels of GABA membrane transporter 1 (GAT1) mRNA. These alterations are thought to be most prominent in the parvalbumin (PV)-containing subclass of interneurons, which also contain lower levels of PV mRNA. Since GAT1 and PV each reduce the availability of GABA at postsynaptic receptors, lower levels of GAT1 and PV mRNAs have been hypothesized to represent compensatory responses to an upstream reduction in cortical GABA synthesis in schizophrenia. However, such cause-and-effect hypotheses cannot be directly tested in a human illness. Consequently, we used two mouse models with reduced GAD67 expression specifically in PV neurons (PVGAD67+/−) or in all interneurons (GABAGAD67+/−) and quantified GAD67, GAT1 and PV mRNA levels using methods identical to those employed in studies of schizophrenia. Cortical levels of PV or GAT1 mRNAs were not altered in PVGAD67+/− mice during postnatal development or in adulthood. Furthermore, cellular analyses confirmed the predicted reduction in GAD67 mRNA, but failed to show a deficit in PV mRNA in these animals. Levels of PV and GAT1 mRNAs were also unaltered in GABAGAD67+/− mice. Thus, mouse lines with cortical reductions in GAD67 mRNA that match or exceed those present in schizophrenia, and that differ in the developmental timing and cell typespecificity of the GAD67 deficit, failed to provide proof-of-concept evidence that lower PV and GAT1 expression in schizophrenia are a consequence of lower GAD67 expression. Together, these findings suggest that the correlated decrements in cortical GAD67, PV and GAT1 mRNAs in schizophrenia may be a common consequence of some other upstream factor. PMID:23103418

  3. Stable isotope dilution HILIC-MS/MS method for accurate quantification of glutamic acid, glutamine, pyroglutamic acid, GABA and theanine in mouse brain tissues.

    PubMed

    Inoue, Koichi; Miyazaki, Yasuto; Unno, Keiko; Min, Jun Zhe; Todoroki, Kenichiro; Toyo'oka, Toshimasa

    2016-01-01

    In this study, we developed the stable isotope dilution hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS) technique for the accurate, reasonable and simultaneous quantification of glutamic acid (Glu), glutamine (Gln), pyroglutamic acid (pGlu), γ-aminobutyric acid (GABA) and theanine in mouse brain tissues. The quantification of these analytes was accomplished using stable isotope internal standards and the HILIC separating mode to fully correct the intramolecular cyclization during the electrospray ionization. It was shown that linear calibrations were available with high coefficients of correlation (r(2)  > 0.999, range from 10 pmol/mL to 50 mol/mL). For application of the theanine intake, the determination of Glu, Gln, pGlu, GABA and theanine in the hippocampus and central cortex tissues was performed based on our developed method. In the region of the hippocampus, the concentration levels of Glu and pGlu were significantly reduced during reality-based theanine intake. Conversely, the concentration level of GABA increased. This result showed that transited theanine has an effect on the metabolic balance of Glu analogs in the hippocampus.

  4. Role of a gamma-aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. The corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was partially controlled by ...

  5. Enhancing Contents of γ-Aminobutyric Acid (GABA) and Other Micronutrients in Dehulled Rice during Germination under Normoxic and Hypoxic Conditions.

    PubMed

    Ding, Junzhou; Yang, Tewu; Feng, Hao; Dong, Mengyi; Slavin, Margaret; Xiong, Shanbai; Zhao, Siming

    2016-02-10

    Biofortification of staple grains with high contents of essential micronutrients is an important strategy to overcome micronutrient malnutrition. However, few attempts have targeted at γ-aminobutyric acid (GABA), a functional nutrient for aging populations. In this study, two rice cultivars, Heinuo and Xianhui 207, were used to investigate changes in GABA and other nutritional compounds of dehulled rice after germination under normoxic and hypoxic conditions. Forty-one metabolites were identified in both cultivars treated by normoxic germination, whereas the germinated dehulled rice of Heinuo and Xianhui 207 under hypoxic treatment had 43 and 41 metabolites identified, respectively. GABA increased in dehulled rice after germination, especially under hypoxia. Meanwhile, a number of other health-beneficial and/or flavor-related compounds such as lysine and d-mannose increased after the hypoxic treatment. The accumulation of GABA exhibited genotype-specific modes in both normoxic and hypoxic treatments. With regard to GABA production, Xianhui 207 was more responsive to the germination process than Heinuo, whereas Heinuo was more responsive to hypoxia than Xianhui 207. This study provides a promising approach to biofortify dehulled rice with increased GABA and other nutrients through metabolomic-based regulation.

  6. GABA(B) receptors in neuroendocrine regulation.

    PubMed

    Lux-Lantos, Victoria A; Bianchi, María S; Catalano, Paolo N; Libertun, Carlos

    2008-09-01

    Gamma-amino butyric acid (GABA), in addition to being a metabolic intermediate and the main inhibitory neurotransmitter in the synaptic cleft, is postulated as a neurohormone, a paracrine signaling molecule, and a trophic factor. It acts through pre- and post-synaptic receptors, named GABA(A) and GABA(C) (ionotropic receptors) and GABA(B) (metabotropic receptor). Here we reviewed the participation of GABA(B) receptors in the regulation of the hypothalamic-pituitary-gonadal axis, using physiological, biochemical, and pharmacological approaches in rats, as well as in GABA(B1) knock-out mice, that lack functional GABA(B) receptors. Our general conclusion indicates that GABA(B )receptors participate in the regulation of pituitary hormone secretion acting both in the central nervous system and directly on the gland. PRL and gonadotropin axes are affected by GABA(B) receptor activation, as demonstrated in the rat and also in the GABA(B1) knock-out mouse. In addition, hypothalamic and pituitary GABA(B) receptor expression is modulated by steroid hormones. GABA participation in the brain control of pituitary secretion through GABA(B) receptors depends on physiological conditions, being age and sex critical factors.These results indicate that patients receiving GABA(B) agonists/antagonists should be monitored for possible endocrine side effects.

  7. Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors functional regulation during enhanced liver cell proliferation by GABA and 5-HT chitosan nanoparticles treatment.

    PubMed

    Shilpa, Joy; Pretty, Mary Abraham; Anitha, Malat; Paulose, Cheramadathikudyil Skaria

    2013-09-01

    Liver is one of the major organs in vertebrates and hepatocytes are damaged by many factors. The liver cell maintenance and multiplication after injury and treatment gained immense interest. The present study investigated the role of Gamma aminobutyric acid (GABA) and serotonin or 5-hydroxytryptamine (5-HT) coupled with chitosan nanoparticles in the functional regulation of Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors mediated cell signaling mechanisms, extend of DNA methylation and superoxide dismutase activity during enhanced liver cell proliferation. Liver injury was achieved by partial hepatectomy of male Wistar rats and the GABA and 5-HT chitosan nanoparticles treatments were given intraperitoneally. The experimental groups were sham operated control (C), partially hepatectomised rats with no treatment (PHNT), partially hepatectomised rats with GABA chitosan nanoparticle (GCNP), 5-HT chitosan nanoparticle (SCNP) and a combination of GABA and 5-HT chitosan nanoparticle (GSCNP) treatments. In GABA and 5-HT chitosan nanoparticle treated group there was a significant decrease (P<0.001) in the receptor expression of Gamma aminobutyric acid B and a significant increase (P<0.001) in the receptor expression of 5-hydroxy tryptamine 2A when compared to PHNT. The cyclic adenosine monophosphate content and its regulatory protein, presence of methylated DNA and superoxide dismutase activity were decreased in GCNP, SCNP and GSCNP when compared to PHNT. The Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors coupled signaling elements played an important role in GABA and 5-HT chitosan nanoparticles induced liver cell proliferation which has therapeutic significance in liver disease management.

  8. Subchronic phencyclidine in rats: alterations in locomotor activity, maze performance, and GABA(A) receptor binding.

    PubMed

    Beninger, Richard J; Beuk, Jonathan; Banasikowski, Tomek J; van Adel, Michael; Boivin, Gregory A; Reynolds, James N

    2010-02-01

    Phencyclidine (PCP), an antagonist at the N-methyl-D-aspartate subtype of ionotropic glutamatergic receptors, decreases gamma-aminobutyric acid (GABA)ergic inhibition, suggesting that changes in GABAergic receptor function underlie behavioral and cognitive deficits resulting from repeated administration of PCP. To test this hypothesis, male Sprague-Dawley rats treated with PCP (4.5 mg/kg, intraperitoneal, twice a day for 7 consecutive days) or saline were tested in behavioral and cognitive tasks 7 days after injections. The PCP group showed increased amphetamine (1.5 mg/kg)-stimulated locomotor activity, and exhibited a greater number of errors in the double Y-maze memory task, when compared with controls. Subchronic PCP treatment increased [H]muscimol-binding sites and decreased affinity for [H]muscimol binding in frontal cortex, hippocampus, and striatum in comparison with controls. There were no changes in the expression of glutamic acid decarboxylase or the GABA membrane transporter protein. These data show that subchronic PCP administration induces an impaired performance of a previously learned task and an enhanced response to amphetamine in the rat. The observed changes in GABAA receptors in the rat brain are consistent with the notion that alterations in GABAergic receptor function contribute to the behavioral and cognitive impairments associated with repeated exposure to PCP. PMID:19949321

  9. Luteinizing hormone releasing hormone (LHRH) neurons maintained in nasal explants decrease LHRH messenger ribonucleic acid levels after activation of GABA(A) receptors.

    PubMed

    Fueshko, S M; Key, S; Wray, S

    1998-06-01

    Inhibition of the LHRH system appears to play an important role in preventing precocious activation of the hypothalamic-pituitary-gonadal axis. Evidence points to gamma-aminobutyric acid (GABA) as the major negative regulator of postnatal LHRH neuronal activity. Changes in LHRH messenger RNA (mRNA) levels after alterations of GABAergic activity have been reported in vivo. However, the extent to which GABA acts directly on LHRH neurons to effect LHRH mRNA levels has been difficult to ascertain. The present work evaluates the effect of GABAergic activity, via GABA(A) receptors, on LHRH neuropeptide gene expression in LHRH neurons maintained in olfactory explants generated from E11.5 mouse embryos. These explants maintain large numbers of primary LHRH neurons that migrate from bilateral olfactory pits in a directed manner. Using in situ hybridization histochemistry and single cell analysis, we report dramatic alterations in LHRH mRNA levels. Inhibition of spontaneous synaptic activity by GABA(A) antagonists, bicuculline (10(-5) M) or picrotoxin (10(-4) M), or of electrical activity by tetrodotoxin (TTX, 10(-6) M) significantly increased LHRH mRNA levels. In contrast, LHRH mRNA levels decreased in explants cultured with the GABA(A) receptor agonist, muscimol (10(-4) M), or KCl (50 mM). The observed responses suggest that LHRH neurons possess functional pathways linking GABA(A) receptors to repression of neuropeptide gene expression and indicate that gene expression in embryonic LHRH neurons, outside the CNS, is highly responsive to alterations in neuronal activity.

  10. During postnatal development endogenous neurosteroids influence GABA-ergic neurotransmission of mouse cortical neurons

    PubMed Central

    Brown, Adam R.; Mitchell, Scott J.; Peden, Dianne R.; Herd, Murray B.; Seifi, Mohsen; Swinny, Jerome D.; Belelli, Delia; Lambert, Jeremy J.

    2016-01-01

    As neuronal development progresses, GABAergic synaptic transmission undergoes a defined program of reconfiguration. For example, GABAA receptor (GABAAR)-mediated synaptic currents, (miniature inhibitory postsynaptic currents; mIPSCs), which initially exhibit a relatively slow decay phase, become progressively reduced in duration, thereby supporting the temporal resolution required for mature network activity. Here we report that during postnatal development of cortical layer 2/3 pyramidal neurons, GABAAR-mediated phasic inhibition is influenced by a resident neurosteroid tone, which wanes in the second postnatal week, resulting in the brief phasic events characteristic of mature neuronal signalling. Treatment of cortical slices with the immediate precursor of 5α-pregnan-3α-ol-20-one (5α3α), the GABAAR-inactive 5α-dihydroprogesterone, (5α-DHP), greatly prolonged the mIPSCs of P20 pyramidal neurons, demonstrating these more mature neurons retain the capacity to synthesize GABAAR-active neurosteroids, but now lack the endogenous steroid substrate. Previously, such developmental plasticity of phasic inhibition was ascribed to the expression of synaptic GABAARs incorporating the α1 subunit. However, the duration of mIPSCs recorded from L2/3 cortical neurons derived from α1 subunit deleted mice, were similarly under the developmental influence of a neurosteroid tone. In addition to principal cells, synaptic GABAARs of L2/3 interneurons were modulated by native neurosteroids in a development-dependent manner. In summary, local neurosteroids influence synaptic transmission during a crucial period of cortical neurodevelopment, findings which may be of importance for establishing normal network connectivity. PMID:26626485

  11. Imidase catalyzing desymmetric imide hydrolysis forming optically active 3-substituted glutaric acid monoamides for the synthesis of gamma-aminobutyric acid (GABA) analogs.

    PubMed

    Nojiri, Masutoshi; Hibi, Makoto; Shizawa, Hiroaki; Horinouchi, Nobuyuki; Yasohara, Yoshihiko; Takahashi, Satomi; Ogawa, Jun

    2015-12-01

    The recent use of optically active 3-substituted gamma-aminobutyric acid (GABA) analogs in human therapeutics has identified a need for an efficient, stereoselective method of their synthesis. Here, bacterial strains were screened for enzymes capable of stereospecific hydrolysis of 3-substituted glutarimides to generate (R)-3-substituted glutaric acid monoamides. The bacteria Alcaligenes faecalis NBRC13111 and Burkholderia phytofirmans DSM17436 were discovered to hydrolyze 3-(4-chlorophenyl) glutarimide (CGI) to (R)-3-(4-chlorophenyl) glutaric acid monoamide (CGM) with 98.1% enantiomeric excess (e.e.) and 97.5% e.e., respectively. B. phytofirmans DSM17436 could also hydrolyze 3-isobutyl glutarimide (IBI) to produce (R)-3-isobutyl glutaric acid monoamide (IBM) with 94.9% e.e. BpIH, an imidase, was purified from B. phytofirmans DSM17436 and found to generate (R)-CGM from CGI with specific activity of 0.95 U/mg. The amino acid sequence of BpIH had a 75% sequence identity to that of allantoinase from A. faecalis NBRC13111 (AfIH). The purified recombinant BpIH and AfIH catalyzed (R)-selective hydrolysis of CGI and IBI. In addition, a preliminary investigation of the enzymatic properties of BpIH and AfIH revealed that both enzymes were stable in the range of pH 6-10, with an optimal pH of 9.0, stable at temperatures below 40 °C, and were not metalloproteins. These results indicate that the use of this class of hydrolase to generate optically active 3-substituted glutaric acid monoamide could simplify the production of specific chiral GABA analogs for drug therapeutics.

  12. Enhancement of GABA release through endogenous activation of axonal GABA(A) receptors in juvenile cerebellum.

    PubMed

    Trigo, Federico F; Chat, Mireille; Marty, Alain

    2007-11-14

    Recent evidence indicates the presence of presynaptic GABA(A) receptors (GABA(A)Rs) in the axon domain of several classes of central neurons, including cerebellar basket and stellate cells. Here, we investigate the possibility that these receptors could be activated in the absence of electrical or chemical stimulation. We find that low concentrations of GABA increase the frequency of miniature GABAergic synaptic currents. Submaximal concentrations of a GABA(A)R blocker, gabazine, decrease both the miniature current frequency and the probability of evoked GABA release. Zolpidem, an agonist of the benzodiazepine binding site, and NO-711 (1-[2-[[(diphenylmethylene)imino]oxy]ethyl]-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid hydrochloride), a blocker of GABA uptake, both increase the frequency of miniature currents. These effects occur up to postnatal day 14, but not later. Immunohistochemistry indicates the presence of alpha1-containing GABA(A)Rs in interneuron presynaptic terminals with a similar age dependence. We conclude that, under resting conditions, axonal GABA(A)Rs are significantly activated, that this activation results in enhanced GABA release, and that it can be augmented by increasing the affinity of GABA(A)Rs or reducing GABA uptake. Our findings suggest the existence of a positive-feedback mechanism involving presynaptic GABA(A)Rs that maintains a high release rate and a high local GABA concentration in the immature cerebellar network.

  13. trans-4-Amino-2-methylbut-2-enoic acid (2-MeTACA) and (+/-)-trans-2-aminomethylcyclopropanecarboxylic acid ((+/-)-TAMP) can differentiate rat rho3 from human rho1 and rho2 recombinant GABA(C) receptors.

    PubMed

    Vien, Jimmy; Duke, Rujee K; Mewett, Kenneth N; Johnston, Graham A R; Shingai, Ryuzo; Chebib, Mary

    2002-02-01

    1. This study investigated the effects of a number of GABA analogues on rat rho3 GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. 2. The potency order of agonists was muscimol (EC(50)=1.9 +/- 0.1 microM) (+)-trans-3-aminocyclopentanecarboxylic acids ((+)-TACP; EC(50)=2.7 +/- 0.9 microM) trans-4-aminocrotonic acid (TACA; EC(50)=3.8 +/-0.3 microM) GABA (EC(50)=4.0 +/- 0.3 microM) > thiomuscimol (EC(50)=24.8 +/- 2.6 microM) > (+/-)-cis-2-aminomethylcyclopropane-carboxylic acid ((+/-)-CAMP; EC(50)=52.6 +/-8.7 microM) > cis-4-aminocrotonic acid (CACA; EC(50)=139.4 +/- 5.2 microM). 3. The potency order of antagonists was (+/-)-trans-2-aminomethylcyclopropanecarboxylic acid ((+/-)-TAMP; K(B)=4.8+/-1.8 microM) (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA; K(B)=4.8 +/-0.8 microM) > (piperidin-4-yl)methylphosphinic acid (P4MPA; K(B)=10.2+/-2.3 microM) 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP; K(B)=10.2+/-0.3 microM) imidazole-4-acetic acid (I4AA; K(B)=12.6+/-2.7 microM) > 3-aminopropylphosphonic acid (3-APA; K(B)=35.8+/-13.5 microM). 4. trans-4-Amino-2-methylbut-2-enoic acid (2-MeTACA; 300 microM) had no effect as an agonist or an antagonist indicating that the C2 methyl substituent is sterically interacting with the ligand-binding site of rat rho3 GABA(C) receptors. 5. 2-MeTACA affects rho1 and rho2 but not rho3 GABA(C) receptors. In contrast, (plus minus)-TAMP is a partial agonist at rho1 and rho2 GABA(C) receptors, while at rat rho3 GABA(C) receptors it is an antagonist. Thus, 2-MeTACA and (+/-)-TAMP could be important pharmacological tools because they may functionally differentiate between rho1, rho2 and rho3 GABA(C) receptors in vitro. PMID:11861315

  14. GABA deficiency in NF1

    PubMed Central

    Patricio, Miguel; Bernardino, Inês; Rebola, José; Abrunhosa, Antero J.; Ferreira, Nuno; Castelo-Branco, Miguel

    2016-01-01

    Objective: To provide a comprehensive investigation of the γ-aminobutyric acid (GABA) system in patients with neurofibromatosis type 1 (NF1) that allows understanding the nature of the GABA imbalance in humans at pre- and postsynaptic levels. Methods: In this cross-sectional study, we employed multimodal imaging and spectroscopy measures to investigate GABA type A (GABAA) receptor binding, using [11C]-flumazenil PET, and GABA concentration, using magnetic resonance spectroscopy (MRS). Fourteen adult patients with NF1 and 13 matched controls were included in the study. MRS was performed in the occipital cortex and in a frontal region centered in the functionally localized frontal eye fields. PET and MRS acquisitions were performed in the same day. Results: Patients with NF1 have reduced concentration of GABA+ in the occipital cortex (p = 0.004) and frontal eye fields (p = 0.026). PET results showed decreased binding of GABAA receptors in patients in the parieto-occipital cortex, midbrain, and thalamus, which are not explained by decreased gray matter levels. Conclusions: Abnormalities in the GABA system in NF1 involve both GABA concentration and GABAA receptor density suggestive of neurodevelopmental synaptopathy with both pre- and postsynaptic involvement. PMID:27473134

  15. Autoradiographic analysis of 3H-glutamate, 3H-dopamine, and 3H-GABA accumulation in rabbit retina after kainic acid treatment

    SciTech Connect

    Hampton, C.K.; Redburn, D.A.

    1983-01-01

    We have previously reported that exposure of isolated rabbit retina to 10(-3) M kainic acid produces profound morphological changes in specific retinal neurons (Hampton et al, 1981). We noted specific swelling of horizontal cell bodies and neurites, necrosis of cell bodies in the amacrine and ganglion cell layers, and swelling of elements in the inner plexiform layer. We now report a differential sensitivity to kainic acid of specific subclasses of amacrine cells autoradiographically labeled with 3H-glutamate, 3H-GABA, or 3H-dopamine. Three different effects were observed: (1) Labeling of neurons after incubation in 3H-glutamate was uniformly reduced while labeling of glia was much less affected. (2) The accumulation of 3H-dopamine was also decreased by kainic acid in two of the three labeled bands of the inner plexiform layer. The outermost labeled band was insensitive to kainic acid at the highest concentration tested (10(-2) M). These findings provide a basis for the subclassification of dopaminergic amacrine cells into at least two subclasses based on their sensitivity to kainic acid. (3) Kainic acid caused a dramatic increase in the labeling of GABAergic amacrine cell bodies and their terminals. This increased intensity may reflect a compensatory increase in uptake activity in response to kainic acid-induced depletion of endogenous GABA stores. These results confirm the highly toxic nature of kainic acid and demonstrate a high degree of specificity and complexity in its action in the retina.

  16. Use of sourdough fermentation and pseudo-cereals and leguminous flours for the making of a functional bread enriched of gamma-aminobutyric acid (GABA).

    PubMed

    Coda, Rossana; Rizzello, Carlo Giuseppe; Gobbetti, Marco

    2010-02-28

    Lactobacillus plantarum C48 and Lactococcus lactis subsp. lactis PU1, previously selected for the biosynthesis of gamma-aminobutyric acid (GABA), were used for sourdough fermentation of cereal, pseudo-cereal and leguminous flours. Chickpea, amaranth, quinoa and buckwheat were the flours most suitable to be enriched of GABA. The parameters of sourdough fermentation were optimized. Addition of 0.1mM pyridoxal phosphate, dough yield of 160, inoculum of 5 x 10(7)CFU/g of starter bacteria and fermentation for 24h at 30 degrees C were found to be the optimal conditions. A blend of buckwheat, amaranth, chickpea and quinoa flours (ratio 1:1:5.3:1) was selected and fermented with baker's yeast (non-conventional flour bread, NCB) or with Lb. plantarum C48 sourdough (non-conventional flour sourdough bread, NCSB) and compared to baker's yeast started wheat flour bread (WFB). NCSB had the highest concentration of free amino acids and GABA (ca. 4467 and 504 mg/kg, respectively). The concentration of phenolic compounds and antioxidant activity of NCSB bread was the highest, as well as the rate of in vitro starch hydrolysis was the lowest. Texture analysis showed that sourdough fermentation enhances several characteristics of NCSB with respect to NCB, thus approaching the features of WFB. Sensory analysis showed that sourdough fermentation allowed to get good palatability and overall taste appreciation.

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

    PubMed

    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.

  18. The sushi domains of secreted GABA(B1) isoforms selectively impair GABA(B) heteroreceptor function.

    PubMed

    Tiao, Jim Y; Bradaia, Amyaouch; Biermann, Barbara; Kaupmann, Klemens; Metz, Michaela; Haller, Corinne; Rolink, Antonius G; Pless, Elin; Barlow, Paul N; Gassmann, Martin; Bettler, Bernhard

    2008-11-01

    GABA(B) receptors are the G-protein-coupled receptors for gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the brain. GABA(B) receptors are promising drug targets for a wide spectrum of psychiatric and neurological disorders. Receptor subtypes exhibit no pharmacological differences and are based on the subunit isoforms GABA(B1a) and GABA(B1b). GABA(B1a) differs from GABA(B1b) in its ectodomain by the presence of a pair of conserved protein binding motifs, the sushi domains (SDs). Previous work showed that selectively GABA(B1a) contributes to heteroreceptors at glutamatergic terminals, whereas both GABA(B1a) and GABA(B1b) contribute to autoreceptors at GABAergic terminals or to postsynaptic receptors. Here, we describe GABA(B1j), a secreted GABA(B1) isoform comprising the two SDs. We show that the two SDs, when expressed as a soluble protein, bind to neuronal membranes with low nanomolar affinity. Soluble SD protein, when added at nanomolar concentrations to dissociated hippocampal neurons or to acute hippocampal slices, impairs the inhibitory effect of GABA(B) heteroreceptors on evoked and spontaneous glutamate release. In contrast, soluble SD protein neither impairs the activity of GABA(B) autoreceptors nor impairs the activity of postsynaptic GABA(B) receptors. We propose that soluble SD protein scavenges an extracellular binding partner that retains GABA(B1a)-containing heteroreceptors in proximity of the presynaptic release machinery. Soluble GABA(B1) isoforms like GABA(B1j) may therefore act as dominant-negative inhibitors of heteroreceptors and control the level of GABA(B)-mediated inhibition at glutamatergic terminals. Of importance for drug discovery, our data also demonstrate that it is possible to selectively impair GABA(B) heteroreceptors by targeting their SDs.

  19. Subcellular localization and complements of GABA(A) and GABA(C) receptors on bullfrog retinal bipolar cells.

    PubMed

    Du, J L; Yang, X L

    2000-08-01

    gamma-Aminobutyric acid (GABA) receptors on retinal bipolar cells (BCs) are highly relevant to spatial and temporal integration of visual signals in the outer and inner retina. In the present work, subcellular localization and complements of GABA(A) and GABA(C) receptors on BCs were investigated by whole cell recordings and local drug application via multi-barreled puff pipettes in the bullfrog retinal slice preparation. Four types of the BCs (types 1-4) were identified morphologically by injection of Lucifer yellow. According to the ramification levels of the axon terminals and the responses of these cells to glutamate (or kainate) applied at their dendrites, types 1 and 2 of BCs were supposed to be OFF type, whereas types 3 and 4 of BCs might be ON type. Bicuculline (BIC), a GABA(A) receptor antagonist, and imidazole-4-acetic acid (I4AA), a GABA(C) receptor antagonist, were used to distinguish GABA receptor-mediated responses. In all BCs tested, not only the axon terminals but also the dendrites showed high GABA sensitivity mediated by both GABA(A) and GABA(C) receptors. Subcellular localization and complements of GABA(A) and GABA(C) receptors at the dendrites and axon terminals were highly related to the dichotomy of OFF and ON BCs. In the case of OFF BCs, GABA(A) receptors were rather evenly distributed at the dendrites and axon terminals, but GABA(C) receptors were predominantly expressed at the axon terminals. Moreover, the relative contribution of GABA(C) receptors to the axon terminals was prevalent over that of GABA(A) receptors, while the situation was reversed at the dendrites. In the case of ON BCs, GABA(A) and GABA(C) receptors both preferred to be expressed at the axon terminals; relative contributions of these two GABA receptor subtypes to both the sites were comparable, while GABA(C) receptors were much less expressed than GABA(A) receptors. GABA(A), but not GABA(C) receptors, were expressed clusteringly at axons of a population of BCs. In a

  20. The Uptake of GABA in Trypanosoma cruzi.

    PubMed

    Galvez Rojas, Robert L; Ahn, Il-Young; Suárez Mantilla, Brian; Sant'Anna, Celso; Pral, Elizabeth Mieko Furusho; Silber, Ariel Mariano

    2015-01-01

    Gamma aminobutyric acid (GABA) is widely known as a neurotransmitter and signal transduction molecule found in vertebrates, plants, and some protozoan organisms. However, the presence of GABA and its role in trypanosomatids is unknown. Here, we report the presence of intracellular GABA and the biochemical characterization of its uptake in Trypanosoma cruzi, the etiological agent of Chagas' disease. Kinetic parameters indicated that GABA is taken up by a single transport system in pathogenic and nonpathogenic forms. Temperature dependence assays showed a profile similar to glutamate transport, but the effect of extracellular cations Na(+) , K(+) , and H(+) on GABA uptake differed, suggesting a different uptake mechanism. In contrast to reports for other amino acid transporters in T. cruzi, GABA uptake was Na(+) dependent and increased with pH, with a maximum activity at pH 8.5. The sensitivity to oligomycin showed that GABA uptake is dependent on ATP synthesis. These data point to a secondary active Na(+) /GABA symporter energized by Na(+) -exporting ATPase. Finally, we show that GABA occurs in the parasite's cytoplasm under normal culture conditions, indicating that it is regularly taken up from the culture medium or synthesized through an still undescribed metabolic pathway.

  1. The Uptake of GABA in Trypanosoma cruzi.

    PubMed

    Galvez Rojas, Robert L; Ahn, Il-Young; Suárez Mantilla, Brian; Sant'Anna, Celso; Pral, Elizabeth Mieko Furusho; Silber, Ariel Mariano

    2015-01-01

    Gamma aminobutyric acid (GABA) is widely known as a neurotransmitter and signal transduction molecule found in vertebrates, plants, and some protozoan organisms. However, the presence of GABA and its role in trypanosomatids is unknown. Here, we report the presence of intracellular GABA and the biochemical characterization of its uptake in Trypanosoma cruzi, the etiological agent of Chagas' disease. Kinetic parameters indicated that GABA is taken up by a single transport system in pathogenic and nonpathogenic forms. Temperature dependence assays showed a profile similar to glutamate transport, but the effect of extracellular cations Na(+) , K(+) , and H(+) on GABA uptake differed, suggesting a different uptake mechanism. In contrast to reports for other amino acid transporters in T. cruzi, GABA uptake was Na(+) dependent and increased with pH, with a maximum activity at pH 8.5. The sensitivity to oligomycin showed that GABA uptake is dependent on ATP synthesis. These data point to a secondary active Na(+) /GABA symporter energized by Na(+) -exporting ATPase. Finally, we show that GABA occurs in the parasite's cytoplasm under normal culture conditions, indicating that it is regularly taken up from the culture medium or synthesized through an still undescribed metabolic pathway. PMID:25851259

  2. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics.

    PubMed

    Jin, Zhe; Bhandage, Amol K; Bazov, Igor; Kononenko, Olga; Bakalkin, Georgy; Korpi, Esa R; Birnir, Bryndis

    2014-01-01

    The central amygdala (CeA) has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic) transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n = 9) and matched controls (n = 9) were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR). Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate) receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence. PMID:25278838

  3. Gamma-aminobutyric acid (GABA) and neuropeptides in neural areas mediating motion-induced emesis

    NASA Technical Reports Server (NTRS)

    Damelio, F.; Daunton, Nancy G.; Fox, Robert A.

    1991-01-01

    Immunocytochemical methods were employed to localize the neurotransmitter amino acid gamma-aminobutyric acid and the neuropeptides substance P and Met-enkephalin in the area postrema (AP), area subpostrema (ASP), nucleus of the tractus solitarius (NTS), dorsal motor nucleus of the vagus nerve (DMNV), and lateral vestibular nucleus (LVN). Glutamic acid decarboxylase immunoreactive (GAD-IR) terminals and fibers were observed in the AP and particularly in the ASP. A gradual decrease in the density of terminals was seen towards the solitary complex. The DMNV revealed irregularly scattered GAD-IR terminals within the neuropil or closely surrounding neuronal cell bodies. The LVN, particularly the dorsal division, showed numerous axon terminals which were mostly localize around large neurons and their proximal dendrites. Substance P immunoreactive (SP-IR) terminals and fibers showed high density in the solitary complex, in particular within the lateral division. The ASP showed medium to low density of SP-IR fibers and terminals. The AP exhibited a small number of fibers and terminals irregularly distributed. The DMNV revealed a high density of SP-IR terminals and fibers that were mainly concentrated in the periphery. Very few terminals were detected in the LVN. Met-enkephalin immunoreactive (Met-Enk-IR) fibers and terminals showed high density and uniform distribution in the DMNV. Scattered terminals and fibers were observed in the AP, ASP, and NTS (particularly the lateral division). The very few fibers were observed in the LVN surrounded the neuronal cell bodies. The present report is part of a study designed to investigate the interaction between neuropeptides and conventional neurotransmitters under conditions producing motion sickness and in the process of sensory-motor adaptation.

  4. The effect of folic acid on GABA(A)-B 1 receptor subunit.

    PubMed

    Vasquez, Kizzy; Kuizon, Salomon; Junaid, Mohammed; Idrissi, Abdeslem El

    2013-01-01

    Autism contains a spectrum of behavioral and cognitive disturbances of childhood development that is manifested by deficits in social interaction, impaired communication, repetitive behavior, and/or restricted interest. Much research has been dedicated to finding the genes that are responsible for autism, but less than 10% of the cases can be attributed to one gene. Autism prevalence has increased in the last decade and there may be environmental components that are leading to this increase. There are reports of disruption of epigenetic mechanisms controlling the regulation of gene expression as probable cause for autism. Folic acid (FA) is prescribed to women during pregnancy, and can cause epigenetic changes. GABAergic pathway is involved in inhibitory neurotransmission in the central nervous system and plays a crucial role during early embryonic development. Autism may entail defect or deregulation of the GABAergic receptor pathway in the brain. Gamma-aminobutyric acid (type A) beta 1 receptor (GABRB1) disruption has been implicated in autism. In the present study, we investigated GABRB1 expression in response to FA supplementation in neuronal cells. Western blot analysis showed GABRB1 protein levels increased in the FA-treated cells in a concentration-dependent manner. FA-dependent increased expression of GABRB1 was further confirmed at the mRNA level using quantitative RT-PCR. These results suggest that epigenetic control of gene expression may affect the expression of GABRB1 and disrupt inhibitory synaptic transmission during embryonic development. PMID:23392927

  5. Role for pro-inflammatory cytokines in regulating expression of GABA transporter type 1 and 3 in specific brain regions of kainic acid-induced status epilepticus.

    PubMed

    Su, Jing; Yin, Jian; Qin, Wei; Sha, Suxu; Xu, Jun; Jiang, Changbin

    2015-03-01

    In general, pro-inflammatory cytokines (PICs) contribute to regulation of epilepsy-associated pathophysiological processes in the central nerve system. In this report, we examined the specific activation of PICs, namely IL-1β, IL-6 and TNF-α in rat brain after kainic acid (KA)-induced status epilepticus (SE). Also, we examined the role played by PICs in regulating expression of GABA transporter type 1 and 3 (GAT-1 and GAT-3, respectively), which are the two important subtypes of GATs responsible for the regulation of extracellular GABA levels in the brain. Our results show that IL-1β, IL-6 and TNF-α were significantly increased in the parietal cortex, hippocampus and amygdala of KA-rats as compared with sham control animals (P < 0.05, KA rats vs. control rats). KA-induced SE also significantly increased (P < 0.05 vs. controls) the protein expression of GAT-1 and GAT-3 in those brain regions. In addition, central administration of antagonists to IL-1β and TNF-α receptors significantly attenuated amplified GAT-1 and GAT-3 (P < 0.05 vs. vehicle control for each antagonist group). However, antagonist to IL-6 receptor failed to attenuate enhancement in expression of GAT-1 and GAT-3 induced by KA-induced SE. Overall, our data demonstrate that PIC pathways are activated in the specific brain regions during SE which thereby selectively leads to upregulation of GABA transporters. As a result, it is likely that de-inhibition of GABA system is increased in the brain. This support a role for PICs in engagement of the adaptive mechanisms associated with epileptic activity, and has pharmacological implications to target specific PICs for neuronal dysfunction and vulnerability related to epilepsy. PMID:25708016

  6. Kinetic studies on the inhibition of GABA-T by gamma-vinyl GABA and taurine.

    PubMed

    Sulaiman, Saba A J; Suliman, Fakhr Eldin O; Barghouthi, Samira

    2003-08-01

    Gamma-aminobutyric acid transaminase (GABA-T, EC 2.6.1.19) is a pyridoxal phosphate (PLP) dependent enzyme that catalyzes the degradation of gamma-aminobutyric acid. The kinetics of this reaction are studied in vitro, both in the absence, and in the presence of two inhibitors: gamma-vinyl GABA (4-aminohex-5-enoic acid), and a natural product, taurine (ethylamine-2-sulfonic acid). A kinetic model that describes the transamination process is proposed. GABA-T from Pseudomonas fluorescens is inhibited by gamma-vinyl GABA and taurine at concentrations of 51.0 and 78.5 mM. Both inhibitors show competitive inhibition behavior when GABA is the substrate and the inhibition constant (Ki) values for gamma-vinyl GABA and taurine were found to be 26 +/- 3 mM and 68 +/- 7 mM respectively. The transamination process of alpha-ketoglutarate was not affected by the presence of gamma-vinyl GABA, whereas, taurine was a noncompetitive inhibitor of GABA-T when alpha-ketoglutarate was the substrate. The inhibition dissociation constant (Kii) for this system was found to be 96 +/- 10 mM. The Michaelis-Menten constant (Km) in the absence of inhibition, was found to be 0.79 +/- 0.11 mM, and 0.47 +/- 0.10 mM for GABA and alpha-ketoglutarate respectively.

  7. γ-Aminobutyric Acid (GABA) Production and Angiotensin-I Converting Enzyme (ACE) Inhibitory Activity of Fermented Soybean Containing Sea Tangle by the Co-Culture of Lactobacillus brevis with Aspergillus oryzae.

    PubMed

    Jang, Eun Kyeong; Kim, Nam Yeun; Ahn, Hyung Jin; Ji, Geun Eog

    2015-08-01

    To enhance the γ-aminobutyric acid (GABA) content, the optimized fermentation of soybean with added sea tangle extract was evaluated at 30°C and pH 5.0. The medium was first inoculated with Aspergillus oryzae strain FMB S46471 and fermented for 3 days, followed by the subsequent inoculation with Lactobacillus brevis GABA 100. After fermentation for 7 days, the fermented soybean showed approximately 1.9 g/kg GABA and exhibited higher ACE inhibitory activity than the traditional soybean product. Furthermore, several peptides in the fraction containing the highest ACE inhibitory activity were identified. The novel fermented soybean enriched with GABA and ACE inhibitory components has great pharmaceutical and functional food values.

  8. Two groups of amino acids interact with GABA-A receptors coupled to t-[35S]butylbicyclophosphorothionate binding sites: possible involvement with seizures associated with hereditary amino acidemias.

    PubMed

    Squires, R F; Saederup, E; Lajtha, A

    1988-09-01

    Seven L-amino acids (Trp, Arg, Lys, Met, Ile, Val, and Phe) partially (28-81%) reversed the inhibitory action of 1 microM gamma-aminobutyric acid (GABA) on t-[35S]butylbicyclophosphorothionate ([35S]TBPS) binding to rat brain membranes, with EC50 values ranging from 5 to 120 mM. D-Trp, D-Arg, D-Lys, D-Met, D-Val, and D-Phe were approximately equipotent with their L-isomers. Tyramine, phenethylamine, and tryptamine, the decarboxylation products of the aromatic amino acids (Tyr, Phe, and Trp, respectively), reversed the inhibitory action of 1 microM GABA on [35S]TBPS binding more potently than the parent amino acids (EC50 values = 1.5-3.0 mM). Human hereditary amino acidemias involving Arg, Lys, Ile, Val, and Phe are associated with seizures, and these amino acids and/or their metabolites may block GABA-A receptors. Five other L-amino acids (ornithine, His, Glu, Pro, and Ala) as well as Gly and beta-Ala inhibited [35S]TBPS binding with IC50 values ranging from 0.1 to 37 mM, and these inhibitions were reversed by the GABA-A receptor blocker R 5135 in all cases. The inhibitory effects of L-ornithine, L-Ala, L-Glu, and L-Pro were stereospecific, because the corresponding D-isomers were considerably less inhibitory. L-His, D-His, and L-Glu gave incomplete (plateau) inhibitions. Human hereditary amino acidemias involving L-ornithine, His, Pro, Gly, and beta-Ala are also associated with seizures, and we speculate that these GABA-mimetic amino acids may desensitize GABA-A receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. GABA[subscript A] Receptor Downregulation in Brains of Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Thuras, Paul D.

    2009-01-01

    Gamma-aminobutyric acid A (GABA[subscript A]) receptors are ligand-gated ion channels responsible for mediation of fast inhibitory action of GABA in the brain. Preliminary reports have demonstrated altered expression of GABA receptors in the brains of subjects with autism suggesting GABA/glutamate system dysregulation. We investigated the…

  10. Targeting γ-aminobutyric acid (GABA) carriers to the brain: potential relevance as antiepileptic pro-drugs.

    PubMed

    Semreen, Mohammad H; El-Shorbagi, Abdel-Nasser; Al-Tel, Taleb H; Alsalahat, Izzeddin M M

    2010-05-01

    The search for antiepileptic compounds with more selective activity continues to be an area of intensive investigation in medicinal chemistry. 3,5-Disubstituted tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) derivatives, 3a-g, potential prodrugs incorporating the neurotransmitter GABA were synthesized and studied for crossing the blood-brain barrier (BBB). Compounds were prepared from primary amines and carbon disulfide to give dithiocarbamates 2a-g which upon reaction in situ with formaldehyde provided the intermediates Ia-g. Addition of Ia-g onto GABA furnished the title compounds 3a-g. The structures were verified by spectral data and the amounts of the compounds in the brain were investigated by using HPLC. The concentration profiles of the tested compounds in mice brain were determined and the in vivo anticonvulsant activity was measured. PMID:20632978

  11. Corticotropin Releasing Factor–Induced Amygdala Gamma-Aminobutyric Acid Release Plays a Key Role in Alcohol Dependence

    PubMed Central

    Roberto, Marisa; Cruz, Maureen T.; Gilpin, Nicholas W.; Sabino, Valentina; Schweitzer, Paul; Bajo, Michal; Cottone, Pietro; Madamba, Samuel G.; Stouffer, David G.; Zorrilla, Eric P.; Koob, George F.; Siggins, George R.; Parsons, Loren H.

    2010-01-01

    Background Corticotropin-releasing factor (CRF) and gamma-aminobutyric acid (GABA)ergic systems in the central amygdala (CeA) are implicated in the high-anxiety, high-drinking profile associated with ethanol dependence. Ethanol augments CeA GABA release in ethanol-naive rats and mice. Methods Using naive and ethanol-dependent rats, we compared electrophysiologic effects and interactions of CRF and ethanol on CeA GABAergic transmission, and we measured GABA dialyzate in CeA after injection of CRF1 antagonists and ethanol. We also compared mRNA expression in CeA for CRF and CRF1 using real-time polymerase chain reaction. We assessed effects of chronic treatment with a CRF1 antagonist on withdrawal-induced increases in alcohol consumption in dependent rats. Results CRF and ethanol augmented CeA GABAergic transmission in naive rats via increased GABA release. Three CRF1 receptor (CRF1) antagonists decreased basal GABAergic responses and abolished ethanol effects. Ethanol-dependent rats exhibited heightened sensitivity to CRF and CRF1 antagonists on CeA GABA release. Intra-CeA CRF1 antagonist administration reversed dependence–related elevations in GABA dialysate and blocked ethanol-induced increases in GABA dialyzate in both dependent and naive rats. Polymerase chain reaction studies indicate increased expression of CRF and CRF1 in CeA of dependent rats. Chronic CRF1 antagonist treatment blocked withdrawal-induced increases in alcohol drinking by dependent rats and tempered moderate increases in alcohol consumption by nondependent rats in intermittent testing. Conclusions These combined findings suggest a key role for specific presynaptic CRF-GABA interactions in CeA in the development and maintenance of ethanol dependence. PMID:20060104

  12. Effect of γ-Aminobutyric Acid (GABA) Producing Bacteria on In vitro Rumen Fermentation, Biogenic Amine Production and Anti-oxidation Using Corn Meal as Substrate.

    PubMed

    Ku, Bum Seung; Mamuad, Lovelia L; Kim, Seon-Ho; Jeong, Chang Dae; Soriano, Alvin P; Lee, Ho-Il; Nam, Ki-Chang; Ha, Jong K; Lee, Sang Suk

    2013-06-01

    The effects and significance of γ-amino butyric acid (GABA) producing bacteria (GPB) on in vitro rumen fermentation and reduction of biogenic amines (histamine, methylamine, ethylamine, and tyramine) using corn meal as a substrate were determined. Ruminal samples collected from ruminally fistulated Holstein cows served as inoculum and corn was used as substrate at 2% dry matter (DM). Different inclusion rates of GPB and GABA were evaluated. After incubation, addition of GPB had no significant effect on in vitro fermentation pH and total gas production, but significantly increased the ammonia nitrogen (NH3-N) concentration and reduced the total biogenic amines production (p<0.05). Furthermore, antioxidation activity was improved as indicated by the significantly higher concentration of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) among treated samples when compared to the control (p<0.05). Additionally, 0.2% GPB was established as the optimum inclusion level. Taken together, these results suggest the potential of utilizing GPB as feed additives to improve growth performance in ruminants by reducing biogenic amines and increasing anti-oxidation.

  13. Effect of γ-Aminobutyric Acid (GABA) Producing Bacteria on In vitro Rumen Fermentation, Biogenic Amine Production and Anti-oxidation Using Corn Meal as Substrate

    PubMed Central

    Ku, Bum Seung; Mamuad, Lovelia L.; Kim, Seon-Ho; Jeong, Chang Dae; Soriano, Alvin P.; Lee, Ho-Il; Nam, Ki-Chang; Ha, Jong K.; Lee, Sang Suk

    2013-01-01

    The effects and significance of γ-amino butyric acid (GABA) producing bacteria (GPB) on in vitro rumen fermentation and reduction of biogenic amines (histamine, methylamine, ethylamine, and tyramine) using corn meal as a substrate were determined. Ruminal samples collected from ruminally fistulated Holstein cows served as inoculum and corn was used as substrate at 2% dry matter (DM). Different inclusion rates of GPB and GABA were evaluated. After incubation, addition of GPB had no significant effect on in vitro fermentation pH and total gas production, but significantly increased the ammonia nitrogen (NH3-N) concentration and reduced the total biogenic amines production (p<0.05). Furthermore, antioxidation activity was improved as indicated by the significantly higher concentration of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) among treated samples when compared to the control (p<0.05). Additionally, 0.2% GPB was established as the optimum inclusion level. Taken together, these results suggest the potential of utilizing GPB as feed additives to improve growth performance in ruminants by reducing biogenic amines and increasing anti-oxidation. PMID:25049853

  14. How and why does tomato accumulate a large amount of GABA in the fruit?

    PubMed Central

    Takayama, Mariko; Ezura, Hiroshi

    2015-01-01

    Gamma-aminobutyric acid (GABA) has received much attention as a health-promoting functional compound, and several GABA-enriched foods have been commercialized. In higher plants, GABA is primarily metabolized via a short pathway called the GABA shunt. The GABA shunt bypasses two steps (the oxidation of α-ketoglutarate to succinate) of the tricarboxylic acid (TCA) cycle via reactions catalyzed by three enzymes: glutamate decarboxylase, GABA transaminase, and succinic semialdehyde dehydrogenase. The GABA shunt plays a major role in primary carbon and nitrogen metabolism and is an integral part of the TCA cycle under stress and non-stress conditions. Tomato is one of the major crops that accumulate a relatively high level of GABA in its fruits. The GABA levels in tomato fruits dramatically change during fruit development; the GABA levels increase from flowering to the mature green stage and then rapidly decrease during the ripening stage. Although GABA constitutes up to 50% of the free amino acids at the mature green stage, the molecular mechanism of GABA accumulation and the physiological function of GABA during tomato fruit development remain unclear. In this review, we summarize recent studies of GABA accumulation in tomato fruits and discuss the potential biological roles of GABA in tomato fruit development. PMID:26322056

  15. Library screening by means of mass spectrometry (MS) binding assays-exemplarily demonstrated for a pseudostatic library addressing γ-aminobutyric acid (GABA) transporter 1 (GAT1).

    PubMed

    Sindelar, Miriam; Wanner, Klaus T

    2012-09-01

    In the present study, the application of mass spectrometry (MS) binding assays as a tool for library screening is reported. For library generation, dynamic combinatorial chemistry (DCC) was used. These libraries can be screened by means of MS binding assays when appropriate measures are taken to render the libraries pseudostatic. That way, the efficiency of MS binding assays to determine ligand binding in compound screening with the ease of library generation by DCC is combined. The feasibility of this approach is shown for γ-aminobutyric acid (GABA) transporter 1 (GAT1) as a target, representing the most important subtype of the GABA transporters. For the screening, hydrazone libraries were employed that were generated in the presence of the target by reacting various sets of aldehydes with a hydrazine derivative that is delineated from piperidine-3-carboxylic acid (nipecotic acid), a common fragment of known GAT1 inhibitors. To ensure that the library generated is pseudostatic, a large excess of the nipecotic acid derivative is employed. As the library is generated in a buffer system suitable for binding and the target is already present, the mixtures can be directly analyzed by MS binding assays-the process of library generation and screening thus becoming simple to perform. The binding affinities of the hits identified by deconvolution were confirmed in conventional competitive MS binding assays performed with single compounds obtained by separate synthesis. In this way, two nipecotic acid derivatives exhibiting a biaryl moiety, 1-{2-[2'-(1,1'-biphenyl-2-ylmethylidene)hydrazine]ethyl}piperidine-3-carboxylic acid and 1-(2-{2'-[1-(2-thiophenylphenyl)methylidene]hydrazine}ethyl)piperidine-3-carboxylic acid, were found to be potent GAT1 ligands exhibiting pK(i) values of 6.186 ± 0.028 and 6.229 ± 0.039, respectively. This method enables screening of libraries, whether generated by conventional chemistry or DCC, and is applicable to all kinds of targets including

  16. Library screening by means of mass spectrometry (MS) binding assays-exemplarily demonstrated for a pseudostatic library addressing γ-aminobutyric acid (GABA) transporter 1 (GAT1).

    PubMed

    Sindelar, Miriam; Wanner, Klaus T

    2012-09-01

    In the present study, the application of mass spectrometry (MS) binding assays as a tool for library screening is reported. For library generation, dynamic combinatorial chemistry (DCC) was used. These libraries can be screened by means of MS binding assays when appropriate measures are taken to render the libraries pseudostatic. That way, the efficiency of MS binding assays to determine ligand binding in compound screening with the ease of library generation by DCC is combined. The feasibility of this approach is shown for γ-aminobutyric acid (GABA) transporter 1 (GAT1) as a target, representing the most important subtype of the GABA transporters. For the screening, hydrazone libraries were employed that were generated in the presence of the target by reacting various sets of aldehydes with a hydrazine derivative that is delineated from piperidine-3-carboxylic acid (nipecotic acid), a common fragment of known GAT1 inhibitors. To ensure that the library generated is pseudostatic, a large excess of the nipecotic acid derivative is employed. As the library is generated in a buffer system suitable for binding and the target is already present, the mixtures can be directly analyzed by MS binding assays-the process of library generation and screening thus becoming simple to perform. The binding affinities of the hits identified by deconvolution were confirmed in conventional competitive MS binding assays performed with single compounds obtained by separate synthesis. In this way, two nipecotic acid derivatives exhibiting a biaryl moiety, 1-{2-[2'-(1,1'-biphenyl-2-ylmethylidene)hydrazine]ethyl}piperidine-3-carboxylic acid and 1-(2-{2'-[1-(2-thiophenylphenyl)methylidene]hydrazine}ethyl)piperidine-3-carboxylic acid, were found to be potent GAT1 ligands exhibiting pK(i) values of 6.186 ± 0.028 and 6.229 ± 0.039, respectively. This method enables screening of libraries, whether generated by conventional chemistry or DCC, and is applicable to all kinds of targets including

  17. The aging human cochlear nucleus: Changes in the glial fibrillary acidic protein, intracellular calcium regulatory proteins, GABA neurotransmitter and cholinergic receptor.

    PubMed

    Sharma, Saroj; Nag, Tapas C; Thakar, Alok; Bhardwaj, Daya N; Roy, Tara Sankar

    2014-03-01

    The human auditory system is highly susceptible to environmental and metabolic insults which further affect the biochemical and physiological milieu of the cells that may contribute to progressive, hearing loss with aging. The cochlear nucleus (CN) is populated by morphologically diverse types of neurons with discrete physiological and neurochemical properties. Between the dorsal and the ventral cochlear nucleus (DCN and VCN), the VCN is further sub-divided into the rostral (rVCN) and caudal (cVCN) sub-divisions. Although, information is available on the age related neurochemical changes in the mammalian CN similar reports on human CN is still sparse. The morphometry and semiquantitative analysis of intensity of expression of glial fibrillary acidic protein (GFAP), calcium binding proteins (calbindin, calretinin and parvalbumin), gamma amino butyric acid (GABA) and nicotinic acetyl choline receptor (nAchR) beta 2 immunostaining were carried out in all three sub-divisions of the human CN from birth to 90 years. There was increased GFAP immunoreactivity in decades 2 and 3 in comparison to decade 1 in the CN. But no change was observed in rVCN from decade 4 onwards, whereas intense staining was also observed in decades 5 and 6 in cVCN and DCN. All three calcium binding proteins were highly expressed in early to middle ages, whereas a significant reduction was found in later decades in the VCN. GABA and nAchR beta 2 expressions were unchanged throughout in all the decades. The middle age may represent a critical period of onset and progression of aging changes in the CN and these alterations may add to the deterioration of hearing responses in the old age.

  18. The aging human cochlear nucleus: Changes in the glial fibrillary acidic protein, intracellular calcium regulatory proteins, GABA neurotransmitter and cholinergic receptor.

    PubMed

    Sharma, Saroj; Nag, Tapas C; Thakar, Alok; Bhardwaj, Daya N; Roy, Tara Sankar

    2014-03-01

    The human auditory system is highly susceptible to environmental and metabolic insults which further affect the biochemical and physiological milieu of the cells that may contribute to progressive, hearing loss with aging. The cochlear nucleus (CN) is populated by morphologically diverse types of neurons with discrete physiological and neurochemical properties. Between the dorsal and the ventral cochlear nucleus (DCN and VCN), the VCN is further sub-divided into the rostral (rVCN) and caudal (cVCN) sub-divisions. Although, information is available on the age related neurochemical changes in the mammalian CN similar reports on human CN is still sparse. The morphometry and semiquantitative analysis of intensity of expression of glial fibrillary acidic protein (GFAP), calcium binding proteins (calbindin, calretinin and parvalbumin), gamma amino butyric acid (GABA) and nicotinic acetyl choline receptor (nAchR) beta 2 immunostaining were carried out in all three sub-divisions of the human CN from birth to 90 years. There was increased GFAP immunoreactivity in decades 2 and 3 in comparison to decade 1 in the CN. But no change was observed in rVCN from decade 4 onwards, whereas intense staining was also observed in decades 5 and 6 in cVCN and DCN. All three calcium binding proteins were highly expressed in early to middle ages, whereas a significant reduction was found in later decades in the VCN. GABA and nAchR beta 2 expressions were unchanged throughout in all the decades. The middle age may represent a critical period of onset and progression of aging changes in the CN and these alterations may add to the deterioration of hearing responses in the old age. PMID:24412669

  19. Detection of Reduced GABA Synthesis Following Inhibition of GABA Transaminase Using in Vivo Magnetic Resonance Signal of [13C]GABA C1

    PubMed Central

    Yang, Jehoon; Johnson, Christopher; Shen, Jun

    2009-01-01

    Previous in vivo magnetic resonance spectroscopy (MRS) studies of gamma-aminobutyric acid (GABA) synthesis have relied on 13C label incorporation into GABA C2 from [1-13C] or [1,6-13C2]glucose. In this study, the [13C]GABA C1 signal at 182.3 ppm in the carboxylic/amide spectral region of localized in vivo 13C spectra was detected. GABA-transaminase of rat brain was inhibited by administration of gabaculine after pre-labeling of GABA C1 and its metabolic precursors with exogenous [2,5-13C2]glucose. A subsequent isotope chase experiment was performed by infusing unlabeled glucose, which revealed a markedly slow change in the labeling of GABA C1 accompanying the blockade of the GABA shunt. This slow labeling of GABA at elevated GABA concentration was attributed to the relatively small intercompartmental GABA-glutamine cycling flux that constitutes the main route of 13C label loss during the isotope chase. Because this study showed that using low RF power broadband stochastic proton decoupling is feasible at very high field strength, it has important implications for the development of carboxylic/amide 13C MRS methods to study brain metabolism and neurotransmission in human subjects at high magnetic fields. PMID:19540876

  20. Impact of exogenous GABA treatments on endogenous GABA metabolism in anthurium cut flowers in response to postharvest chilling temperature.

    PubMed

    Aghdam, Morteza Soleimani; Naderi, Roohangiz; Jannatizadeh, Abbasali; Babalar, Mesbah; Sarcheshmeh, Mohammad Ali Askari; Faradonbe, Mojtaba Zamani

    2016-09-01

    Anthurium flowers are susceptible to chilling injury, and the optimum storage temperature is 12.5-20 °C. The γ-aminobutyric acid (GABA) shunt pathway may alleviate chilling stress in horticultural commodities by providing energy (ATP), reducing molecules (NADH), and minimizing accumulation of reactive oxygen species (ROS). In this experiment, the impact of a preharvest spray treatment with 1 mM GABA and postharvest treatment of 5 mM GABA stem-end dipping on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) in response to cold storage (4 °C for 21 days) was investigated. GABA treatments resulted in lower glutamate decarboxylase (GAD) and higher GABA transaminase (GABA-T) activities in flowers during cold storage, which was associated with lower GABA content and coincided with higher ATP content. GABA treatments also enhanced accumulation of endogenous glycine betaine (GB) in flowers during cold storage, as well as higher spathe relative water content (RWC). These findings suggest that GABA treatments may alleviate chilling injury of anthurium cut flowers by enhancing GABA shunt pathway activity leading to provide sufficient ATP and promoting endogenous GB accumulation. PMID:27135813

  1. Impact of exogenous GABA treatments on endogenous GABA metabolism in anthurium cut flowers in response to postharvest chilling temperature.

    PubMed

    Aghdam, Morteza Soleimani; Naderi, Roohangiz; Jannatizadeh, Abbasali; Babalar, Mesbah; Sarcheshmeh, Mohammad Ali Askari; Faradonbe, Mojtaba Zamani

    2016-09-01

    Anthurium flowers are susceptible to chilling injury, and the optimum storage temperature is 12.5-20 °C. The γ-aminobutyric acid (GABA) shunt pathway may alleviate chilling stress in horticultural commodities by providing energy (ATP), reducing molecules (NADH), and minimizing accumulation of reactive oxygen species (ROS). In this experiment, the impact of a preharvest spray treatment with 1 mM GABA and postharvest treatment of 5 mM GABA stem-end dipping on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) in response to cold storage (4 °C for 21 days) was investigated. GABA treatments resulted in lower glutamate decarboxylase (GAD) and higher GABA transaminase (GABA-T) activities in flowers during cold storage, which was associated with lower GABA content and coincided with higher ATP content. GABA treatments also enhanced accumulation of endogenous glycine betaine (GB) in flowers during cold storage, as well as higher spathe relative water content (RWC). These findings suggest that GABA treatments may alleviate chilling injury of anthurium cut flowers by enhancing GABA shunt pathway activity leading to provide sufficient ATP and promoting endogenous GB accumulation.

  2. Guinea Pig Horizontal Cells Express GABA, the GABA-Synthesizing Enzyme GAD65, and the GABA Vesicular Transporter

    PubMed Central

    Guo, Chenying; Hirano, Arlene A.; Stella, Salvatore L.; Bitzer, Michaela; Brecha, Nicholas C.

    2013-01-01

    γ-Aminobutyric acid (GABA) is likely expressed in horizontal cells of all species, although conflicting physiological findings have led to considerable controversy regarding its role as a transmitter in the outer retina. This study has evaluated key components of the GABA system in the outer retina of guinea pig, an emerging retinal model system. The presence of GABA, its rate-limiting synthetic enzyme glutamic acid decarboxylase (GAD65 and GAD67 isoforms), the plasma membrane GABA transporters (GAT-1 and GAT-3), and the vesicular GABA transporter (VGAT) was evaluated by using immunohistochemistry with well-characterized antibodies. The presence of GAD65 mRNA was also evaluated by using laser capture microdissection and reverse transcriptase-polymerase chain reaction. Specific GABA, GAD65, and VGAT immunostaining was localized to horizontal cell bodies, as well as to their processes and tips in the outer plexiform layer. Furthermore, immunostaining of retinal whole mounts and acutely dissociated retinas showed GAD65 and VGAT immunoreactivity in both A-type and B-type horizontal cells. However, these cells did not contain GAD67, GAT-1, or GAT-3 immunoreactivity. GAD65 mRNA was detected in horizontal cells, and sequencing of the amplified GAD65 fragment showed approximately 85% identity with other mammalian GAD65 mRNAs. These studies demonstrate the presence of GABA, GAD65, and VGAT in horizontal cells of the guinea pig retina, and support the idea that GABA is synthesized from GAD65, taken up into synaptic vesicles by VGAT, and likely released by a vesicular mechanism from horizontal cells. PMID:20235161

  3. [Autoantibodies to glutamate and GABA in opiate addiction].

    PubMed

    Vetrile, L A; Fomina, V G; Nevidimova, T I; Vetlugina, T P; Batukhtina, E I; Savochkina, D N; Zakharova, I A; Davydova, T V

    2015-01-01

    Blood serum from 129 patients with opium addiction at different stages of the disease and 63 donors (control group) was examined for the presence of autoantibodies to the exciting and inhibitory amino acids glutamate and GABA. It was shown enhanced production of autoantibodies to glutamate and GABA. Dependence of the level and frequency of detec- tion of autoantibodies to glutamate and GABA on the stage of the disease was revealed.

  4. [Autoantibodies to glutamate and GABA in opiate addiction].

    PubMed

    Vetrile, L A; Fomina, V G; Nevidimova, T I; Vetlugina, T P; Batukhtina, E I; Savochkina, D N; Zakharova, I A; Davydova, T V

    2015-01-01

    Blood serum from 129 patients with opium addiction at different stages of the disease and 63 donors (control group) was examined for the presence of autoantibodies to the exciting and inhibitory amino acids glutamate and GABA. It was shown enhanced production of autoantibodies to glutamate and GABA. Dependence of the level and frequency of detec- tion of autoantibodies to glutamate and GABA on the stage of the disease was revealed. PMID:26852594

  5. Afferents of the lamprey optic tectum with special reference to the GABA input: combined tracing and immunohistochemical study.

    PubMed

    Robertson, Brita; Saitoh, Kazuya; Ménard, Ariane; Grillner, Sten

    2006-11-01

    The optic tectum in the lamprey midbrain, homologue of the superior colliculus in mammals, is important for eye movement control and orienting responses. There is, however, only limited information regarding the afferent input to the optic tectum except for that from the eyes. The objective of this study was to define specifically the gamma-aminobutyric acid (GABA)-ergic projections to the optic tectum in the river lamprey (Lampetra fluviatilis) and also to describe the tectal afferent input in general. The origin of afferents to the optic tectum was studied by using the neuronal tracer neurobiotin. Injection of neurobiotin into the optic tectum resulted in retrograde labelling of cell groups in all major subdivisions of the brain. The main areas shown to project to the optic tectum were the following: the caudoventral part of the medial pallium, the area of the ventral thalamus and dorsal thalamus, the nucleus of the posterior commissure, the torus semicircularis, the mesencephalic M5 nucleus of Schober, the mesencephalic reticular area, the ishtmic area, and the octavolateral nuclei. GABAergic projections to the optic tectum were identified by combining neurobiotin tracing and GABA immunohistochemistry. On the basis of these double-labelling experiments, it was shown that the optic tectum receives a GABAergic input from the caudoventral part of the medial pallium, the dorsal and ventral thalamus, the nucleus of M5, and the torus semicircularis. The afferent input to the optic tectum in the lamprey brain is similar to that described for other vertebrate species, which is of particular interest considering its position in phylogeny. PMID:16958107

  6. Effects of prenatal exposure to 2,4-D/2,4,5-T mixture on postnatal changes in rat brain glutamate, GABA protein, and nucleic acid levels

    SciTech Connect

    Mohammad, F.K.; Omer, V.E.V.

    1988-02-01

    The opportunity of maternal exposure to various chemicals in the work place and the general environments have increased, and the fetus and neonate may be at greater risk than the adult. However, the embryotoxic and teratogenic effects of the chlorinated phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), the main chemicals in Agent Orange, are well documented only in laboratory animals. The brain of the developing fetus is vulnerable to the toxic effects of the phenoxy herbicides which readily cross the placental barrier and distribute into fetal tissues, including brain. Although the neurochemical basis for the behavioral teratogenicity of the phenoxy herbicides is not know, it was recently reported that non-teratogenic doses of a 1:1 mixture of 2,4-D and 2,4,5-T delayed the ontogeny of dopamine and serotonin in the brain of the developing rate. This communication provides further descriptive information about the ontogeny of rat brain nucleic acid, protein, glutamate and ..gamma..-aminobutyrate (GABA) following in utero exposure to non-teratogenic levels of a 1:1 mixture of 2,4-D/2,4,5-T.

  7. TANGO1 recruits ERGIC membranes to the endoplasmic reticulum for procollagen export

    PubMed Central

    Santos, António JM; Raote, Ishier; Scarpa, Margherita; Brouwers, Nathalie; Malhotra, Vivek

    2015-01-01

    Previously we showed that membrane fusion is required for TANGO1-dependent export of procollagen VII from the endoplasmic reticulum (ER) (Nogueira, et al., 2014). Along with the t-SNARE Syntaxin 18, we now reveal the complete complement of SNAREs required in this process, t-SNAREs BNIP1 and USE1, and v-SNARE YKT6. TANGO1 recruits YKT6-containing ER Golgi Intermediate Compartment (ERGIC) membranes to procollagen VII-enriched patches on the ER. Moreover residues 1214-1396, that include the first coiled coil of TANGO1, specifically recruit ERGIC membranes even when targeted to mitochondria. TANGO1 is thus pivotal in concentrating procollagen VII in the lumen and recruiting ERGIC membranes on the cytoplasmic surface of the ER. Our data reveal that growth of a mega transport carrier for collagen export from the ER is not by acquisition of a larger patch of ER membrane, but instead by addition of ERGIC membranes to procollagen-enriched domains of the ER by a TANGO1-mediated process. DOI: http://dx.doi.org/10.7554/eLife.10982.001 PMID:26568311

  8. EXP-1 is an excitatory GABA-gated cation channel.

    PubMed

    Beg, Asim A; Jorgensen, Erik M

    2003-11-01

    Gamma-aminobutyric acid (GABA) mediates fast inhibitory neurotransmission by activating anion-selective ligand-gated ion channels. Although electrophysiological studies indicate that GABA may activate cation-selective ligand-gated ion channels in some cell types, such a channel has never been characterized at the molecular level. Here we show that GABA mediates enteric muscle contraction in the nematode Caenorhabditis elegans via the EXP-1 receptor, a cation-selective ligand-gated ion channel. The EXP-1 protein resembles ionotropic GABA receptor subunits in almost all domains. In the pore-forming domain of EXP-1, however, the residues that confer anion selectivity are exchanged for those that specify cation selectivity. When expressed in Xenopus laevis oocytes, EXP-1 forms a GABA receptor that is permeable to cations and not anions. We conclude that some of the excitatory functions assigned to GABA are mediated by cation channels rather than by anion channels.

  9. Regulation of Mac-2BP secretion is mediated by its N-glycan binding to ERGIC-53.

    PubMed

    Chen, Yang; Hojo, Sanae; Matsumoto, Naoki; Yamamoto, Kazuo

    2013-07-01

    The leguminous-type (L-type) lectin ER-Golgi intermediate compartment (ERGIC)-53, a homo-oligomeric endoplasmic reticulum (ER)-Golgi recycling protein, functions as a transport receptor for newly synthesized glycoproteins in the early secretory pathway. Although a limited subset of cargo glycoproteins transported by ERGIC-53, such as the coagulation factors V and VIII, cathepsin C and Z and α1-antitrypsin, has been identified, the exact role of the N-glycan binding of ERGIC-53 in the transport of secretory glycoproteins for ER exit has yet to be clarified. By screening a cDNA library isolated from HepG2 cells via a green fluorescent protein fragment complementation assay, we assessed several candidate luminal ERGIC-53-interacting partners and identified Mac-2 binding protein (Mac-2BP) as a novel ERGIC-53-transported cargo glycoprotein. Using an N-glycan-binding-deficient mutant of ERGIC-53 (N156A) or treatment with N-glycosylation processing inhibitors, as well as the introduction of the ER-mis-targeting mutant (KKAA), we demonstrated that the high-mannose-type N-glycan binding of ERGIC-53 contributes to its interaction with Mac-2BP, which is essential for the ERGIC-53-mediated ER-Golgi transport of nascent proteins during early secretion. Furthermore, we also provide evidence that MCFD2 is involved in the secretion of Mac-2BP. These observations reveal a distinct role for the N-glycan binding of ERGIC-53 in the receptor-mediated ER exit of newly synthesized Mac-2BP in the early secretion pathway.

  10. Distribution of 3H-GABA uptake sites in the nematode Ascaris

    SciTech Connect

    Guastella, J.; Stretton, A.O. )

    1991-05-22

    The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, located at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.

  11. Chronic noise stress-induced alterations of glutamate and gamma-aminobutyric acid and their metabolism in the rat brain.

    PubMed

    Kazi, Amajad Iqbal; Oommen, Anna

    2014-01-01

    Chronic stress induces neurochemical changes that include neurotransmitter imbalance in the brain. Noise is an environmental factor inducing stress. Chronic noise stress affects monoamine neurotransmitter systems in the central nervous system. The effect on other excitatory and inhibitory neurotransmitter systems is not known. The aim was to study the role of chronic noise stress on the glutamatergic and gamma-aminobutyric acid (GABA)ergic systems of the brain. Female Wistar rats (155 ± 5 g) were unintentionally exposed to noise due to construction (75-95 db, 3-4 hours/day, 5 days a week for 7-8 weeks) in the vicinity of the animal care facility. Glutamate/GABA levels and their metabolic enzymes were evaluated in different rat brain regions (cortex, hippocampus, striatum, and cerebellum) and compared with age and gender matched nonexposed rats. Chronic noise stress decreased glutamate levels and glutaminase activity 27% and 33% in the cortex, 15% and 24% in the cerebellum. Glutamate levels increased 10% in the hippocampus, 28% in striatum and glutaminase activity 15% in striatum. Glutamine synthetase activity increased significantly in all brain regions studied, that is, cortex, hippocampus, striatum, and cerebellum (P < 0.05). Noise stress-increased GABA levels and glutamate alpha decarboxylase activity 20% and 45% in the cortex, 13% and 28% in the hippocampus respectively. GABA levels and glutamate alpha decarboxylase activity decreased 15% and 14%, respectively in the striatum. GABA transaminase activity was significantly reduced in the cortex (55%), hippocampus (17%), and cerebellum (33%). Chronic noise stress differentially affected glutamatergic and GABAergic neurotransmitter systems in the rat brain, which may alter glutamate and GABA neurotransmission.

  12. Cloning and expression of a rat brain GABA transporter

    SciTech Connect

    Guastella, J.; Czyzyk, L.; Davidson, N.; Lester, H.A. ); Nelson, N.; Nelson, H.; Miedel, M.C. ); Keynan, S.; Kanner, B.I. )

    1990-09-14

    A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter {gamma}-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in Xenopus oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated ({sup 3}H)GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium- and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters. The GAT-1 protein shares antigenic determinants with a native rat brain GABA transporter. The nucleotide sequence of GAT-1 predicts a protein of 599 amino acids with a molecular weight of 67 kilodaltons. Hydropathy analysis of the deduced protein suggests multiple transmembrane regions, a feature shared by several cloned transporters; however, database searches indicate that GAT-1 is not homologous to any previously identified proteins. Therefore, GAT-1 appears to be a member of a previously uncharacterized family of transport molecules.

  13. 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid stimulates GABA release from interneurons projecting to CA1 pyramidal neurons in the rat hippocampus via pre-synaptic alpha7 acetylcholine receptors.

    PubMed

    Kanno, Takeshi; Yaguchi, Takahiro; Yamamoto, Satoshi; Yamamoto, Hideyuki; Fujikawa, Hirokazu; Nagata, Tetsu; Tanaka, Akito; Nishizaki, Tomoyuki

    2005-11-01

    Nicotinic acetylcholine (ACh) receptors, such as alpha7, alpha3beta4 and alpha4beta2 receptors in the hippocampus, are suggested to modulate neurotransmitter release. 8-[2-(2-Pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA) (100 nM), a linoleic acid derivative, potentiated responses of alpha7, alpha3beta4 and alpha4beta2 ACh receptors expressed in Xenopus oocytes that are blocked by 3-(1-[dimethylaminopropyl] indol-3-yl)-4-[indol-3-yl] maleimide (GF109203X), a selective inhibitor of protein kinase C (PKC), except for alpha3beta4 ACh receptors. DCP-LA enhanced the nicotine-triggered release of GABA from rat hippocampal slices in the presence of tetrodotoxin in a bell-shaped dose-dependent manner at concentrations ranging from 10 nM to 10 microM, although DCP-LA by itself had no effect on GABA release. The DCP-LA action was inhibited by GF109203X or alpha-bungarotoxin, an inhibitor of alpha7 ACh receptors, but not by mecamylamine or dihydro-beta-erithroidine, an inhibitor of alpha3beta4 and alpha4beta2 ACh receptors. A similar effect on GABA release was obtained with 12-O-tetradecanoylphorbol 13-acetate, a PKC activator. DCP-LA (100 nM) also enhanced GABA release triggered by choline, an agonist of alpha7 ACh receptors, but not 3-[2(s)-azetidinylmethoxy] pyridine, an agonist of alpha4beta2 ACh receptors. In addition, DCP-LA (100 nM) increased the rate of nicotine-triggered GABA(A) receptor-mediated miniature inhibitory post-synaptic currents, monitored from CA1 pyramidal neurons of rat hippocampal slices, and the effect was also inhibited by GF109203X or alpha-bungarotoxin but not by mecamylamine. Thus, the results of the present study indicate that DCP-LA stimulates GABA release by enhancing activity of pre-synaptic alpha7 ACh receptors present on the GABAergic terminals of interneurons that transmit to CA1 pyramidal neurons via a PKC pathway. PMID:16248884

  14. THE INTRACELLULAR CARGO RECEPTOR ERGIC-53 IS REQUIRED FOR THE PRODUCTION OF INFECTIOUS ARENAVIRUS, CORONAVIRUS, AND FILOVIRUS PARTICLES

    PubMed Central

    Klaus, Joseph; Eisenhauer, Philip; Russo, Joanne; Mason, Anne; Do, Danh; King, Benjamin; Taatjes, Douglas; Cornillez-Ty, Cromwell; Boyson, Jonathan E.; Thali, Markus; Zheng, Chunlei; Liao, Lujian; Yates, John R.; Zhang, Bin; Ballif, Bryan A.; Botten, Jason

    2013-01-01

    SUMMARY Arenaviruses and hantaviruses cause severe and often fatal diseases in humans. Little is known regarding host proteins required for their propagation. We identified human proteins that interact with the glycoproteins (GPs) of a prototypic arenavirus and hantavirus and show that the lectin ERGIC-53 - a cargo receptor required for cellular glycoprotein trafficking within the early exocytic pathway - associates with arenavirus, hantavirus, coronavirus, orthomyxovirus, and filovirus GPs. ERGIC-53 binds to arenavirus GPs through a lectin-independent mechanism, traffics to arenavirus budding sites, and is incorporated into arenavirus particles. ERGIC-53 is required for arenavirus, coronavirus, and filovirus propagation; in its absence, GP-containing virus particles form, but are noninfectious due, in part, to their inability to attach to host cells. Thus, we have identified a class of pathogen-derived ERGIC-53 ligands, a lectin-independent basis for their association with ERGIC-53, and a role for ERGIC-53 in the propagation of several highly pathogenic RNA virus families. PMID:24237698

  15. Neurotoxins from Snake Venoms and α-Conotoxin ImI Inhibit Functionally Active Ionotropic γ-Aminobutyric Acid (GABA) Receptors*

    PubMed Central

    Kudryavtsev, Denis S.; Shelukhina, Irina V.; Son, Lina V.; Ojomoko, Lucy O.; Kryukova, Elena V.; Lyukmanova, Ekaterina N.; Zhmak, Maxim N.; Dolgikh, Dmitry A.; Ivanov, Igor A.; Kasheverov, Igor E.; Starkov, Vladislav G.; Ramerstorfer, Joachim; Sieghart, Werner; Tsetlin, Victor I.; Utkin, Yuri N.

    2015-01-01

    Ionotropic receptors of γ-aminobutyric acid (GABAAR) regulate neuronal inhibition and are targeted by benzodiazepines and general anesthetics. We show that a fluorescent derivative of α-cobratoxin (α-Ctx), belonging to the family of three-finger toxins from snake venoms, specifically stained the α1β3γ2 receptor; and at 10 μm α-Ctx completely blocked GABA-induced currents in this receptor expressed in Xenopus oocytes (IC50 = 236 nm) and less potently inhibited α1β2γ2 ≈ α2β2γ2 > α5β2γ2 > α2β3γ2 and α1β3δ GABAARs. The α1β3γ2 receptor was also inhibited by some other three-finger toxins, long α-neurotoxin Ls III and nonconventional toxin WTX. α-Conotoxin ImI displayed inhibitory activity as well. Electrophysiology experiments showed mixed competitive and noncompetitive α-Ctx action. Fluorescent α-Ctx, however, could be displaced by muscimol indicating that most of the α-Ctx-binding sites overlap with the orthosteric sites at the β/α subunit interface. Modeling and molecular dynamic studies indicated that α-Ctx or α-bungarotoxin seem to interact with GABAAR in a way similar to their interaction with the acetylcholine-binding protein or the ligand-binding domain of nicotinic receptors. This was supported by mutagenesis studies and experiments with α-conotoxin ImI and a chimeric Naja oxiana α-neurotoxin indicating that the major role in α-Ctx binding to GABAAR is played by the tip of its central loop II accommodating under loop C of the receptors. PMID:26221036

  16. GABA transporter subtype 1 and GABA transporter subtype 3 modulate glutamatergic transmission via activation of presynaptic GABA(B) receptors in the rat globus pallidus.

    PubMed

    Jin, Xiao-Tao; Paré, Jean-Francois; Smith, Yoland

    2012-08-01

    The intra-pallidal application of γ-aminobutyric acid (GABA) transporter subtype 1 (GAT-1) or GABA transporter subtype 3 (GAT-3) transporter blockers [1-(4,4-diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride (SKF 89976A) or 1-[2-[tris(4-methoxyphenyl)methoxy]ethyl]-(S)-3-piperidinecarboxylic acid (SNAP 5114)] reduces the activity of pallidal neurons in monkey. This effect could be mediated through the activation of presynaptic GABA(B) heteroreceptors in glutamatergic terminals by GABA spillover following GABA transporter (GAT) blockade. To test this hypothesis, we applied the whole-cell recording technique to study the effects of SKF 89976A and SNAP 5114 on evoked excitatory postsynaptic currents (eEPSCs) in the presence of gabazine, a GABA(A) receptor antagonist, in rat globus pallidus slice preparations. Under the condition of postsynaptic GABA(B) receptor blockade by the intra-cellular application of N-(2,6-dimethylphenylcarbamoylmethyl)-triethylammonium bromide (OX314), bath application of SKF 89976A (10 μM) or SNAP 5114 (10 μM) decreased the amplitude of eEPSCs, without a significant effect on its holding current and whole cell input resistance. The inhibitory effect of GAT blockade on eEPSCs was blocked by (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl](phenylmethyl)phosphinic acid, a GABA(B) receptor antagonist. The paired-pulse ratio of eEPSCs was increased, whereas the frequency, but not the amplitude, of miniature excitatory postsynaptic currents was reduced in the presence of either GAT blocker, demonstrating a presynaptic effect. These results suggest that synaptically released GABA can inhibit glutamatergic transmission through the activation of presynaptic GABA(B) heteroreceptors following GAT-1 or GAT-3 blockade. In conclusion, our findings demonstrate that presynaptic GABA(B) heteroreceptors in putative glutamatergic subthalamic afferents to the globus pallidus are sensitive to increases in extracellular GABA induced

  17. A mitochondrial GABA permease connects the GABA shunt and the TCA cycle, and is essential for normal carbon metabolism.

    PubMed

    Michaeli, Simon; Fait, Aaron; Lagor, Kelly; Nunes-Nesi, Adriano; Grillich, Nicole; Yellin, Ayelet; Bar, Dana; Khan, Munziba; Fernie, Alisdair R; Turano, Frank J; Fromm, Hillel

    2011-08-01

    In plants, γ-aminobutyric acid (GABA) accumulates in the cytosol in response to a variety of stresses. GABA is transported into mitochondria, where it is catabolized into TCA cycle or other intermediates. Although there is circumstantial evidence for mitochondrial GABA transporters in eukaryotes, none have yet been identified. Described here is an Arabidopsis protein similar in sequence and topology to unicellular GABA transporters. The expression of this protein complements a GABA-transport-deficient yeast mutant. Thus the protein was termed AtGABP to indicate GABA-permease activity. In vivo localization of GABP fused to GFP and immunobloting of subcellular fractions demonstrate its mitochondrial localization. Direct [(3) H]GABA uptake measurements into isolated mitochondria revealed impaired uptake into mitochondria of a gabp mutant compared with wild-type (WT) mitochondria, implicating AtGABP as a major mitochondrial GABA carrier. Measurements of CO(2) release, derived from radiolabeled substrates in whole seedlings and in isolated mitochondria, demonstrate impaired GABA-derived input into the TCA cycle, and a compensatory increase in TCA cycle activity in gabp mutants. Finally, growth abnormalities of gabp mutants under limited carbon availability on artificial media, and in soil under low light intensity, combined with their metabolite profiles, suggest an important role for AtGABP in primary carbon metabolism and plant growth. Thus, AtGABP-mediated transport of GABA from the cytosol into mitochondria is important to ensure proper GABA-mediated respiration and carbon metabolism. This function is particularly essential for plant growth under conditions of limited carbon.

  18. Relative efficacies of 1,4-diazepines on GABA-stimulated chloride influx in rat brain vesicles

    SciTech Connect

    Ikeda, Masaaki; Weber, K.H.; Bechtel, W.D.; Malatynska, E.; Yamamura, H.I.

    1989-01-01

    The effects of 1,4-diazepines with two annelated heterocycles (brotizolam (WE 941), ciclotizolam (WE 973) and WE 1008) on gamma-aminobutyric acid (GABA)-stimulated chloride influx into rat brain membrane vesicles were examined. Brotizolam enhanced GABA-stimulated /sup 36/Cl/sup /minus// influx, while ciclotizolam and WE 1008 showed only a small enhancement of GABA-stimulated /sup 36/Cl/sup /minus// uptake. Brotizolam resulted in a left shift of the GABA dose response curve at lower concentrations of GABA, while at higher concentrations of GABA, brotizolam caused a reduction of the maximal response. The enhancement of GABA-stimulated /sup 36/Cl/sup /minus// uptake by brotizolam was antagonized by Ro 15-1788. At higher concentration of GABA (300 /mu/M), brotizolam inhibited GABA-stimulated /sup 36/Cl/sup /minus// uptake in a dose dependent manner and Ro 15-1788 failed to antagonize this effect.

  19. A Gut Feeling about GABA: Focus on GABAB Receptors

    PubMed Central

    Hyland, Niall P.; Cryan, John F.

    2010-01-01

    γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the body and hence GABA-mediated neurotransmission regulates many physiological functions, including those in the gastrointestinal (GI) tract. GABA is located throughout the GI tract and is found in enteric nerves as well as in endocrine-like cells, implicating GABA as both a neurotransmitter and an endocrine mediator influencing GI function. GABA mediates its effects via GABA receptors which are either ionotropic GABAA or metabotropic GABAB. The latter which respond to the agonist baclofen have been least characterized, however accumulating data suggest that they play a key role in GI function in health and disease. Like GABA, GABAB receptors have been detected throughout the gut of several species in the enteric nervous system, muscle, epithelial layers as well as on endocrine-like cells. Such widespread distribution of this metabotropic GABA receptor is consistent with its significant modulatory role over intestinal motility, gastric emptying, gastric acid secretion, transient lower esophageal sphincter relaxation and visceral sensation of painful colonic stimuli. More intriguing findings, the mechanisms underlying which have yet to be determined, suggest GABAB receptors inhibit GI carcinogenesis and tumor growth. Therefore, the diversity of GI functions regulated by GABAB receptors makes it a potentially useful target in the treatment of several GI disorders. In light of the development of novel compounds such as peripherally acting GABAB receptor agonists, positive allosteric modulators of the GABAB receptor and GABA producing enteric bacteria, we review and summarize current knowledge on the function of GABAB receptors within the GI tract. PMID:21833169

  20. Estimation of ambient GABA levels in layer I of the mouse neonatal cortex in brain slices.

    PubMed

    Dvorzhak, Anton; Myakhar, Olga; Unichenko, Petr; Kirmse, Knut; Kirischuk, Sergei

    2010-07-01

    GABAergic synapses on Cajal-Retzius neurons in layer I of the murine neocortex experience GABA(B) receptor (GABA(B)R)-mediated tonic inhibition. Extracellular GABA concentration ([GABA](o)) that determines the strength of GABA(B)R-mediated inhibition is controlled by GABA transporters (GATs). In this study, we hypothesized that the strength of presynaptic GABA(B)R activation reflects [GABA](o) in the vicinity of synaptic contacts. Slices obtained from two age groups were used, namely postnatal days (P)2-3 and P5-7. GABAergic postsynaptic currents (IPSCs) were recorded using the whole-cell patch-clamp technique. Minimal electrical stimulation in layer I was applied to elicit evoked IPSCs (eIPSCs) using a paired-pulse protocol. Three parameters were selected for comparison: the mean eIPSC amplitude, paired-pulse ratio, and failure rate. When GAT-1 and GAT-2/3 were blocked by NO-711 (10 microM) and SNAP-5114 (40 microM), respectively, no tonic GABA(B)R-mediated inhibition was observed. In order to restore the control levels of GABA(B)R-mediated inhibition, 250 and 125 nm exogenous GABA was required at P2-3 and P5-7, respectively. Addition of 3-mercaptopropionic acid, a glutamate decarboxylase inhibitor, did not significantly change the obtained values arguing against the suggestion that a mechanism different from GATs contributes to [GABA](o) control. We conclude that juxtasynaptic [GABA](o) is higher (about 250 nM) at P2-3 than at P5-7 (about 125 nM). As both radial cell migration and corticogenesis in general are strongly dependent on [GABA](o) and the formation of the last layer 2/3 is finished by P4 in rodents, the observed [GABA](o) reduction in layer I might reflect this crucial event in the cortical development. PMID:20421290

  1. Stable expression of the vesicular GABA transporter following photothrombotic infarct in rat brain.

    PubMed

    Frahm, C; Siegel, G; Grass, S; Witte, O W

    2006-07-01

    Before exocytotic release of the inhibitory neurotransmitter GABA, this amino acid has to be stored in synaptic vesicles. Accumulation of GABA in vesicles is achieved by a specific membrane-integrated transporter termed vesicular GABA transporter. This vesicular protein is mainly located at presynaptic terminals of GABAergic interneurons. In the present study we investigated the effects of focal ischemia on the expression of the vesicular GABA transporter. Vesicular GABA transporter mRNA and protein expression was examined after photothrombosis in different cortical and hippocampal brain regions of Wistar rats. In situ hybridization and quantitative real-time RT-PCR were performed to analyze vesicular GABA transporter mRNA. Both vesicular GABA transporter mRNA-stained perikarya and mRNA expression levels remained unaffected. Vesicular GABA transporter protein-containing synaptic terminals and somata were visualized by immunohistochemistry. The pattern of vesicular GABA transporter immunoreactivity as well as the protein expression level revealed by semiquantitative image analysis and by Western blot remained stable after stroke. The steady expression of vesicular GABA transporter mRNA and protein after photothrombosis indicates that the exocytotic release mechanism of GABA is not affected by ischemia.

  2. An Electrostatic Funnel in the GABA-Binding Pathway

    PubMed Central

    Lightstone, Felice C.

    2016-01-01

    The γ-aminobutyric acid type A receptor (GABAA-R) is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a ‘funnel’ that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site. PMID:27119953

  3. An Electrostatic Funnel in the GABA-Binding Pathway.

    PubMed

    Carpenter, Timothy S; Lightstone, Felice C

    2016-04-01

    The γ-aminobutyric acid type A receptor (GABAA-R) is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a 'funnel' that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site. PMID:27119953

  4. Identification and functional characterization of a dual GABA/taurine transporter in the bullfrog retinal pigment epithelium

    PubMed Central

    1995-01-01

    Intracellular microelectrodes, fluorescence imaging, and radiotracer flux techniques were used to investigate the physiological response of the retinal pigment epithelium (RPE) to the major retinal inhibitory neurotransmitter, gamma-aminobutyric acid (GABA). GABA is released tonically in the dark by amphibian horizontal cells, but is not taken up by the nearby Muller cells. Addition of GABA to the apical bath produced voltage responses in the bullfrog RPE that were not blocked nor mimicked by any of the major GABA-receptor antagonists or agonists. Nipecotic acid, a substrate for GABA transport, inhibited the voltage effects of GABA. GABA and nipecotic acid also inhibited the voltage effects of taurine, suggesting that the previously characterized beta- alanine sensitive taurine carrier also takes up GABA. The voltage responses of GABA, taurine, nipecotic acid, and beta-alanine all showed first-order saturable kinetics with the following Km's: GABA (Km = 160 microM), beta-alanine (Km = 250 microM), nipecotic acid (Km = 420 microM), and taurine (Km = 850 microM). This low affinity GABA transporter is dependent on external Na, partially dependent on external Cl, and is stimulated in low [K]o, which approximates subretinal space [K]o during light onset. Apical GABA also produced a significant conductance increase at the basolateral membrane. These GABA-induced conductance changes were blocked by basal Ba2+, suggesting that GABA decreased basolateral membrane K conductance. In addition, the apical membrane Na/K ATPase was stimulated in the presence of GABA. A model for the interaction between the GABA transporter, the Na/K ATPase, and the basolateral membrane K conductance accounts for the electrical effects of GABA. Net apical-to-basal flux of [3H]-GABA was also observed in radioactive flux experiments. The present study shows that a high capacity GABA uptake mechanism with unique pharmacological properties is located at the RPE apical membrane and could play an

  5. Evidence for a Revised Ion/Substrate Coupling Stoichiometry of GABA Transporters.

    PubMed

    Willford, Samantha L; Anderson, Cynthia M; Spencer, Shelly R; Eskandari, Sepehr

    2015-08-01

    Plasma membrane γ-aminobutyric acid (GABA) transporters (GATs) are electrogenic transport proteins that couple the cotranslocation of Na(+), Cl(-), and GABA across the plasma membrane of neurons and glia. A fundamental property of the transporter that determines its ability to concentrate GABA in cells and, hence, regulate synaptic and extra-synaptic GABA concentrations, is the ion/substrate coupling stoichiometry. Here, we scrutinized the currently accepted 2 Na(+):1 Cl(-):1 GABA stoichiometry because it is inconsistent with the measured net charge translocated per co-substrate (Na(+), Cl(-), and GABA). We expressed GAT1 and GAT3 in Xenopus laevis oocytes and utilized thermodynamic and uptake under voltage-clamp measurements to determine the stoichiometry of the GABA transporters. Voltage-clamped GAT1-expressing oocytes were internally loaded with GABA, and the reversal potential (V rev) of the transporter-mediated current was recorded at different external concentrations of Na(+), Cl(-), or GABA. The shifts in V rev for a tenfold change in the external Na(+), Cl(-), and GABA concentration were 84 ± 4, 30 ± 1, and 29 ± 1 mV, respectively. To determine the net charge translocated per Na(+), Cl(-), and GABA, we measured substrate fluxes under voltage clamp in cells expressing GAT1 or GAT3. Charge flux to substrate flux ratios were 0.7 ± 0.1 charge/Na(+), 2.0 ± 0.2 charges/Cl(-), and 2.1 ± 0.1 charges/GABA. Altogether, our results strongly suggest a 3 Na(+):1 Cl(-):1 GABA coupling stoichiometry for the GABA transporters. The revised stoichiometry has important implications for understanding the contribution of GATs to GABAergic signaling in health and disease.

  6. In vivo molecular imaging of the GABA/benzodiazepine receptor complex in the aged rat brain.

    PubMed

    Hoekzema, Elseline; Rojas, Santiago; Herance, Raúl; Pareto, Deborah; Abad, Sergio; Jiménez, Xavier; Figueiras, Francisca P; Popota, Foteini; Ruiz, Alba; Flotats, Núria; Fernández, Francisco J; Rocha, Milagros; Rovira, Mariana; Víctor, Víctor M; Gispert, Juan D

    2012-07-01

    The GABA-ergic system, known to regulate neural tissue genesis during cortical development, has been postulated to play a role in cerebral aging processes. Using in vivo molecular imaging and voxel-wise quantification, we aimed to assess the effects of aging on the benzodiazepine (BDZ) recognition site of the GABA(A) receptor. To visualize BDZ site availability, [(11)C]-flumazenil microPET acquisitions were conducted in young and old rats. The data were analyzed and region of interest analyses were applied to validate the voxel-wise approach. We observed decreased [(11)C]-flumazenil binding in the aged rat brains in comparison with the young control group. More specifically, clusters of reduced radioligand uptake were detected in the bilateral hippocampus, cerebellum, midbrain, and bilateral frontal and parieto-occipital cortex. Our results support the pertinence of voxel-wise quantification in the analysis of microPET data. Moreover, these findings indicate that the aging process involves declines in neural BDZ recognition site availability, proposed to reflect alterations in GABA(A) receptor subunit polypeptide expression.

  7. Influence of cold stress on contents of soluble sugars, vitamin C and free amino acids including gamma-aminobutyric acid (GABA) in spinach (Spinacia oleracea).

    PubMed

    Yoon, Young-Eun; Kuppusamy, Saranya; Cho, Kye Man; Kim, Pil Joo; Kwack, Yong-Bum; Lee, Yong Bok

    2017-01-15

    The contents of soluble sugars (sucrose, fructose, glucose, maltose and raffinose), vitamin C and free amino acids (34 compounds, essential and non-essential) were quantified in open-field and greenhouse-grown spinaches in response to cold stress using liquid chromatography. In general, greenhouse cultivation produced nutritionally high value spinach in a shorter growing period, where the soluble sugars, vitamin C and total amino acids concentrations, including essential were in larger amounts compared to those grown in open-field scenarios. Further, low temperature exposure of spinach during a shorter growth period resulted in the production of spinach with high sucrose, ascorbate, proline, gamma-aminobutyric acid, valine and leucine content, and these constitute the most important energy/nutrient sources. In conclusion, cultivation of spinach in greenhouse at a low temperature (4-7°C) and exposure for a shorter period (7-21days) before harvest is recommended. This strategy will produce a high quality product that people can eat. PMID:27542466

  8. Influence of cold stress on contents of soluble sugars, vitamin C and free amino acids including gamma-aminobutyric acid (GABA) in spinach (Spinacia oleracea).

    PubMed

    Yoon, Young-Eun; Kuppusamy, Saranya; Cho, Kye Man; Kim, Pil Joo; Kwack, Yong-Bum; Lee, Yong Bok

    2017-01-15

    The contents of soluble sugars (sucrose, fructose, glucose, maltose and raffinose), vitamin C and free amino acids (34 compounds, essential and non-essential) were quantified in open-field and greenhouse-grown spinaches in response to cold stress using liquid chromatography. In general, greenhouse cultivation produced nutritionally high value spinach in a shorter growing period, where the soluble sugars, vitamin C and total amino acids concentrations, including essential were in larger amounts compared to those grown in open-field scenarios. Further, low temperature exposure of spinach during a shorter growth period resulted in the production of spinach with high sucrose, ascorbate, proline, gamma-aminobutyric acid, valine and leucine content, and these constitute the most important energy/nutrient sources. In conclusion, cultivation of spinach in greenhouse at a low temperature (4-7°C) and exposure for a shorter period (7-21days) before harvest is recommended. This strategy will produce a high quality product that people can eat.

  9. GABA Signaling and Neuroactive Steroids in Adrenal Medullary Chromaffin Cells

    PubMed Central

    Harada, Keita; Matsuoka, Hidetada; Fujihara, Hiroaki; Ueta, Yoichi; Yanagawa, Yuchio; Inoue, Masumi

    2016-01-01

    Gamma-aminobutyric acid (GABA) is produced not only in the brain, but also in endocrine cells by the two isoforms of glutamic acid decarboxylase (GAD), GAD65 and GAD67. In rat adrenal medullary chromaffin cells only GAD67 is expressed, and GABA is stored in large dense core vesicles (LDCVs), but not synaptic-like microvesicles (SLMVs). The α3β2/3γ2 complex represents the majority of GABAA receptors expressed in rat and guinea pig chromaffin cells, whereas PC12 cells, an immortalized rat chromaffin cell line, express the α1 subunit as well as the α3. The expression of α3, but not α1, in PC12 cells is enhanced by glucocorticoid activity, which may be mediated by both the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). GABA has two actions mediated by GABAA receptors in chromaffin cells: it induces catecholamine secretion by itself and produces an inhibition of synaptically evoked secretion by a shunt effect. Allopregnanolone, a neuroactive steroid which is secreted from the adrenal cortex, produces a marked facilitation of GABAA receptor channel activity. Since there are no GABAergic nerve fibers in the adrenal medulla, GABA may function as a para/autocrine factor in the chromaffin cells. This function of GABA may be facilitated by expression of the immature isoforms of GAD and GABAA receptors and the lack of expression of plasma membrane GABA transporters (GATs). In this review, we will consider how the para/autocrine function of GABA is achieved, focusing on the structural and molecular mechanisms for GABA signaling. PMID:27147972

  10. Identification and selective inhibition of the channel mode of the neuronal GABA transporter 1.

    PubMed

    Krause, Stephan; Schwarz, Wolfgang

    2005-12-01

    The function of GAT1, the transporter for the inhibitory neurotransmitter GABA, is characterized by expression in Xenopus laevis oocytes and measurements of GABA-induced uptake of [3H]GABA, 22Na+, and 36Cl-, and GABA-evoked currents under voltage-clamp conditions. N-[4,4-Diphenyl-3-butenyl]-nipecotic acid (SKF-89976-A), a specific inhibitor of GAT1, is used in our system as a pharmacological tool. The GABA-evoked current can be decomposed into a transport current, which is coupled to the GABA uptake, and a transmitter-gated current, which is uncoupled from the GABA uptake. The transport current results from a fixed stoichiometry of 1 GABA/2 Na+/1 Cl- transported during each cycle, as determined by radioactive tracer flux measurements. The transmitter-gated current is mediated by an Na+-conductance pathway. As a competitive inhibitor for GABA uptake, SKF-89976-A can separate the two current components. The GABA uptake is blocked with a K(I) value of approximately 7 microM, whereas the uncoupled transmitter-gated current is inhibited with a K(I) value of approximately 0.03 microM. Thus, the results of this study not only identify the transport mode and the channel mode of GAT1 but also raise the possibility of separating these components in a physiological environment.

  11. Extent of colocalization of serotonin and GABA in neurons of the ventral medulla oblongata in rat.

    PubMed

    Millhorn, D E; Hökfelt, T; Seroogy, K; Verhofstad, A A

    1988-09-27

    The colocalization of serotonin (5-hydroxytryptamine; 5-HT) and gamma-aminobutyric acid (GABA) in the ventral aspect of the rat medulla oblongata was studied using antibodies directed against 5-HT and GABA. Although 5-HT- and GABA-immunoreactive cell bodies were observed over the entire rostral-caudal extent of the ventral medulla, the colocalization of these two classical neurotransmitters in single cells was, for the most part, limited to a region that corresponds anatomically to nucleus raphe magnus/nucleus paragigantocellularis. Schematic drawings showing the distribution of 5-HT/GABA cell bodies in the ventral medulla are provided. PMID:3066433

  12. Aldehyde dehydrogenase 1a1 mediates a GABA synthesis pathway in midbrain dopaminergic neurons.

    PubMed

    Kim, Jae-Ick; Ganesan, Subhashree; Luo, Sarah X; Wu, Yu-Wei; Park, Esther; Huang, Eric J; Chen, Lu; Ding, Jun B

    2015-10-01

    Midbrain dopamine neurons are an essential component of the basal ganglia circuitry, playing key roles in the control of fine movement and reward. Recently, it has been demonstrated that γ-aminobutyric acid (GABA), the chief inhibitory neurotransmitter, is co-released by dopamine neurons. Here, we show that GABA co-release in dopamine neurons does not use the conventional GABA-synthesizing enzymes, glutamate decarboxylases GAD65 and GAD67. Our experiments reveal an evolutionarily conserved GABA synthesis pathway mediated by aldehyde dehydrogenase 1a1 (ALDH1a1). Moreover, GABA co-release is modulated by ethanol (EtOH) at concentrations seen in blood alcohol after binge drinking, and diminished ALDH1a1 leads to enhanced alcohol consumption and preference. These findings provide insights into the functional role of GABA co-release in midbrain dopamine neurons, which may be essential for reward-based behavior and addiction.

  13. Parkinson's Disease and Neurodegeneration: GABA-Collapse Hypothesis.

    PubMed

    Błaszczyk, Janusz W

    2016-01-01

    Neurodegenerative diseases constitute a heterogeneous group of age-related disorders that are characterized by a slow but irreversible deterioration of brain functions. Evidence accumulated over more than two decades has implicated calcium-related homeostatic mechanisms, giving rise to the Ca(2+) hypothesis of brain aging and, ultimately, cell death. Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter within the central (CNS), peripheral and enteric nervous systems. It appears to be involved in a wide variety of physiological functions within and outside the nervous system, that are maintained through a complex interaction between GABA and calcium-dependent neurotransmission and cellular metabolic functions. Within CNS the Ca(2+)/GABA mechanism stabilizes neuronal activity both at cellular and systemic levels. Decline in the Ca(2+)/GABA control initiates several cascading processes leading to both weakened protective barriers (in particular the blood-brain barrier) and accumulations of intracellular deposits of calcium and Lewy bodies. Linking such a vital mechanism of synaptic transmission with metabolism (both at cellular and tissue level) by means of a common reciprocal Ca(2+)/GABA inhibition results in a fragile balance, which is prone to destabilization and auto-destruction. The GABA decline etiology proposed here appears to apply to all human neurodegenerative processes initiated by abnormal intracellular calcium levels. Therefore, the original description of Parkinson's disease (PD) as due to the selective damage of dopaminergic neurons in the mesencephalon should be updated into the concept of a severe multisystemic neurodegenerative disorder of the nervous system, whose clinical symptoms reflect the localization and progression of the most advanced GABA pathology. A future and more complete therapeutic approach to PD should be aimed first at slowing (or stopping) the progression of Ca(2+)/GABA functional decline. PMID:27375426

  14. Parkinson's Disease and Neurodegeneration: GABA-Collapse Hypothesis

    PubMed Central

    Błaszczyk, Janusz W.

    2016-01-01

    Neurodegenerative diseases constitute a heterogeneous group of age-related disorders that are characterized by a slow but irreversible deterioration of brain functions. Evidence accumulated over more than two decades has implicated calcium-related homeostatic mechanisms, giving rise to the Ca2+ hypothesis of brain aging and, ultimately, cell death. Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter within the central (CNS), peripheral and enteric nervous systems. It appears to be involved in a wide variety of physiological functions within and outside the nervous system, that are maintained through a complex interaction between GABA and calcium-dependent neurotransmission and cellular metabolic functions. Within CNS the Ca2+/GABA mechanism stabilizes neuronal activity both at cellular and systemic levels. Decline in the Ca2+/GABA control initiates several cascading processes leading to both weakened protective barriers (in particular the blood-brain barrier) and accumulations of intracellular deposits of calcium and Lewy bodies. Linking such a vital mechanism of synaptic transmission with metabolism (both at cellular and tissue level) by means of a common reciprocal Ca2+/GABA inhibition results in a fragile balance, which is prone to destabilization and auto-destruction. The GABA decline etiology proposed here appears to apply to all human neurodegenerative processes initiated by abnormal intracellular calcium levels. Therefore, the original description of Parkinson's disease (PD) as due to the selective damage of dopaminergic neurons in the mesencephalon should be updated into the concept of a severe multisystemic neurodegenerative disorder of the nervous system, whose clinical symptoms reflect the localization and progression of the most advanced GABA pathology. A future and more complete therapeutic approach to PD should be aimed first at slowing (or stopping) the progression of Ca2+/GABA functional decline. PMID:27375426

  15. A study on quality components and sleep-promoting effects of GABA black tea.

    PubMed

    Zhao, Wenfang; Li, Yun; Ma, William; Ge, Yazhong; Huang, Yahui

    2015-10-01

    The aims of this study were to analyze the changes in quality components of gamma (γ)-aminobutyric acid (GABA) black tea during processing, and to investigate the effect of three dosages of GABA black tea on sleep improvement. The results showed that the GABA content was increased significantly up to 2.70 mg g(-1) after vacuum anaerobic and aerobic treatment. In addition, the content of GABA after drying reached 2.34 mg g(-1), which achieved the standard of GABA tea. During the entire processing of GABA black tea, the contents of tea polyphenols, caffeine and total catechins displayed a gradually descending trend, while the contents of free amino acids and GABA were firstly increased, and then reduced. The GABA black tea had significant effects on prolonging the sleeping time with sodium pentobarbital (P < 0.05) and significantly enhancing the sleeping rate induced by sodium pentobarbital at a sub-threshold dose (P < 0.05). But its effect on shortening the sleeping latency period induced by sodium barbital was not significant (P > 0.05). It had no effect on directly inducing sleep and the mouse body weight. The extract of GABA black tea improved the sleeping quality of mice to extend with an optimal effect being found in the high dose-treated mice. PMID:26290415

  16. A study on quality components and sleep-promoting effects of GABA black tea.

    PubMed

    Zhao, Wenfang; Li, Yun; Ma, William; Ge, Yazhong; Huang, Yahui

    2015-10-01

    The aims of this study were to analyze the changes in quality components of gamma (γ)-aminobutyric acid (GABA) black tea during processing, and to investigate the effect of three dosages of GABA black tea on sleep improvement. The results showed that the GABA content was increased significantly up to 2.70 mg g(-1) after vacuum anaerobic and aerobic treatment. In addition, the content of GABA after drying reached 2.34 mg g(-1), which achieved the standard of GABA tea. During the entire processing of GABA black tea, the contents of tea polyphenols, caffeine and total catechins displayed a gradually descending trend, while the contents of free amino acids and GABA were firstly increased, and then reduced. The GABA black tea had significant effects on prolonging the sleeping time with sodium pentobarbital (P < 0.05) and significantly enhancing the sleeping rate induced by sodium pentobarbital at a sub-threshold dose (P < 0.05). But its effect on shortening the sleeping latency period induced by sodium barbital was not significant (P > 0.05). It had no effect on directly inducing sleep and the mouse body weight. The extract of GABA black tea improved the sleeping quality of mice to extend with an optimal effect being found in the high dose-treated mice.

  17. GABA shapes the dynamics of bistable perception.

    PubMed

    van Loon, Anouk M; Knapen, Tomas; Scholte, H Steven; St John-Saaltink, Elexa; Donner, Tobias H; Lamme, Victor A F

    2013-05-01

    Sometimes, perception fluctuates spontaneously between two distinct interpretations of a constant sensory input. These bistable perceptual phenomena provide a unique window into the neural mechanisms that create the contents of conscious perception. Models of bistable perception posit that mutual inhibition between stimulus-selective neural populations in visual cortex plays a key role in these spontaneous perceptual fluctuations. However, a direct link between neural inhibition and bistable perception has not yet been established experimentally. Here, we link perceptual dynamics in three distinct bistable visual illusions (binocular rivalry, motion-induced blindness, and structure from motion) to measurements of gamma-aminobutyric acid (GABA) concentrations in human visual cortex (as measured with magnetic resonance spectroscopy) and to pharmacological stimulation of the GABAA receptor by means of lorazepam. As predicted by a model of neural interactions underlying bistability, both higher GABA concentrations in visual cortex and lorazepam administration induced slower perceptual dynamics, as reflected in a reduced number of perceptual switches and a lengthening of percept durations. Thus, we show that GABA, the main inhibitory neurotransmitter, shapes the dynamics of bistable perception. These results pave the way for future studies into the competitive neural interactions across the visual cortical hierarchy that elicit conscious perception. PMID:23602476

  18. Conformationally sensitive proximity of extracellular loops 2 and 4 of the γ-aminobutyric acid (GABA) transporter GAT-1 inferred from paired cysteine mutagenesis.

    PubMed

    Hilwi, Maram; Dayan, Oshrat; Kanner, Baruch I

    2014-12-01

    The sodium- and chloride-coupled GABA transporter GAT-1 is a member of the neurotransmitter:sodium:symporters, which are crucial for synaptic transmission. Structural work on the bacterial homologue LeuT suggests that extracellular loop 4 closes the extracellular solvent pathway when the transporter becomes inward-facing. To test whether this model can be extrapolated to GAT-1, cysteine residues were introduced at positions 359 and 448 of extracellular loop 4 and transmembrane helix 10, respectively. Treatment of HeLa cells, expressing the double cysteine mutant S359C/K448C with the oxidizing reagent copper(II)(1,10-phenantroline)3, resulted in a significant inhibition of [(3)H]GABA transport. However, transport by the single cysteine mutant S359C was also inhibited by the oxidant, whereas its activity was almost 4-fold stimulated by dithiothreitol. Both effects were attenuated when the conserved cysteine residues, Cys-164 and/or Cys-173, were replaced by serine. These cysteines are located in extracellular loop 2, the role of which in the structure and function of the eukaryotic neurotransmitter:sodium:symporters remains unknown. The inhibition of transport of S359C by the oxidant was markedly reduced under conditions expected to increase the proportion of inward-facing transporters, whereas the reactivity of the mutants to a membrane-impermeant sulfhydryl reagent was not conformationally sensitive. Our data suggest that extracellular loops 2 and 4 come into close proximity to each other in the outward-facing conformation of GAT-1.

  19. Downregulation of GABA[Subscript A] Receptor Protein Subunits a6, ß2, d, e, ?2, ?, and ?2 in Superior Frontal Cortex of Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rustan, Oyvind G.; Rooney, Robert J.; Thuras, Paul D.

    2014-01-01

    We measured protein and mRNA levels for nine gamma-aminobutyric acid A (GABA[subscript A]) receptor subunits in three brain regions (cerebellum, superior frontal cortex, and parietal cortex) in subjects with autism versus matched controls. We observed changes in mRNA for a number of GABA[subscript A] and GABA[subscript B] subunits and overall…

  20. Comparative Mapping of GABA-Immunoreactive Neurons in the Buccal Ganglia of Nudipleura Molluscs.

    PubMed

    Gunaratne, Charuni A; Katz, Paul S

    2016-04-15

    Phylogenetic comparisons of neurotransmitter distribution are important for understanding the ground plan organization of nervous systems. This study describes the γ-aminobutyric acid (GABA)-immunoreactive (GABA-ir) neurons in the buccal ganglia of six sea slug species (Mollusca, Gastropoda, Euthyneura, Nudipleura). In the nudibranch species, Hermissenda crassicornis, Tritonia diomedea, Tochuina tetraquetra, and Dendronotus iris, the number of GABA-ir neurons was highly consistent. Another nudibranch, Melibe leonina, however, contained approximately half the number of GABA-ir neurons. This may relate to its loss of a radula and its unique feeding behavior. The GABA immunoreactivity in a sister group to the nudibranchs, Pleurobranchaea californica, differed drastically from that of the nudibranchs. Not only did it have significantly more GABA-ir neurons but it also had a unique GABA distribution pattern. Furthermore, unlike the nudibranchs, the Pleurobranchaea GABA distribution was also different from that of other, more distantly related, euopisthobranch and panpulmonate snails and slugs. This suggests that the Pleurobranchaea GABA distribution may be a derived feature, unique to this lineage. The majority of GABA-ir axons and neuropil in the Nudipleura were restricted to the buccal ganglia, commissures, and connectives. However, in Tritonia and Pleurobranchaea, we detected a few GABA-ir fibers in buccal nerves that innervate feeding muscles. Although the specific functions of the GABA-ir neurons in the species in this study are not known, the innervation pattern suggests these neurons may play an integrative or regulatory role in bilaterally coordinated behaviors in the Nudipleura. PMID:26355705

  1. Thioperamide, a histamine H3 receptor antagonist, increases GABA release from the rat hypothalamus.

    PubMed

    Yamamoto, Y; Mochizuki, T; Okakura-Mochizuki, K; Uno, A; Yamatodani, A

    1997-06-01

    Using a microdialysis method and a new high performance liquid chromatography (HPLC)-fluorometric method for the detection of gamma-aminobutyric acid (GABA), we investigated the effect of thioperamide, an H3 receptor antagonist, on the GABA content in the dialysate from the anterior hypothalamic area of rats anesthetized with urethane. The addition of thioperamide to the perfusion fluid increased the release of GABA and histamine. Depleting neuronal histamine with alpha-fluoromethylhistidine, a specific inhibitor of histidine decarboxylase, and the administration of immepip, an H3 agonist, had no effect on basal- and thioperamide-induced GABA release. In addition, an infusion of clobenpropit, the most specific H3 receptor antagonist available, did not alter the basal release of GABA. On the other hand, histamine release was decreased by immepip and increased by thioperamide and clobenpropit. Removing Ca2+ from the perfusion fluid did not alter the effect of thioperamide on the GABA release, whereas that on histamine release was abrogated. These results suggest that the effect of thioperamide on GABA release is not mediated by histamine H3 receptors and that thioperamide acts on the transporter to cause an efflux of GABA from neurons and/or glia. Thioperamide is a popular H3 receptor antagonist which has been used applied to many studies. However, results using this compound should be interpreted in consideration of its effects on GABA release.

  2. Edited Magnetic Resonance Spectroscopy Detects an Age-Related Decline in Nonhuman Primate Brain GABA Levels

    PubMed Central

    Killiany, Ronald J.

    2016-01-01

    Recent research had shown a correlation between aging and decreasing Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. However, how GABA level varies with age in the medial portion of the brain has not yet been studied. The purpose of this study was to investigate the GABA level variation with age focusing on the posterior cingulate cortex, which is the “core hub” of the default mode network. In this study, 14 monkeys between 4 and 21 years were recruited, and MEGA-PRESS MRS was performed to measure GABA levels, in order to explore a potential link between aging and GABA. Our results showed that a correlation between age and GABA+/Creatine ratio was at the edge of significance (r = −0.523, p = 0.081). There was also a near-significant trend between gray matter/white matter ratio and the GABA+/Creatine ratio (r = −0.518, p = 0.0848). Meanwhile, the correlation between age and grey matter showed no significance (r = −0.028, p = 0.93). Therefore, age and gray matter/white matter ratio account for different part of R-squared (adjusted R-squared = 0.5187) as independent variables for predicting GABA levels. Adjusted R-squared is about 0.5 for two independent variables. These findings suggest that there is internal neurochemical variation of GABA levels in the nonhuman primates associated with normal aging and structural brain decline.

  3. Neurotransmitters as food supplements: the effects of GABA on brain and behavior

    PubMed Central

    Boonstra, Evert; de Kleijn, Roy; Colzato, Lorenza S.; Alkemade, Anneke; Forstmann, Birte U.; Nieuwenhuis, Sander

    2015-01-01

    Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown. It has long been thought that GABA is unable to cross the blood–brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest. We suggest that any veridical effects of GABA food supplements on brain and cognition might be exerted through BBB passage or, more indirectly, via an effect on the enteric nervous system. We conclude that the mechanism of action of GABA food supplements is far from clear, and that further work is needed to establish the behavioral effects of GABA. PMID:26500584

  4. Differential effects of petit mal anticonvulsants and convulsants on thalamic neurones: GABA current blockade.

    PubMed Central

    Coulter, D. A.; Huguenard, J. R.; Prince, D. A.

    1990-01-01

    1. Currents evoked by applications of gamma-aminobutyric acid (GABA) to acutely dissociated thalamic neurones were analysed by voltage-clamp techniques, and the effects of the anticonvulsant succinimides ethosuximide (ES) and alpha-methyl-alpha-phenylsuccinimide (MPS) and the convulsants tetramethylsuccinimide (TMS), picrotoxin, pentylenetetrazol (PTZ), and bicuculline methiodide were assessed. 2. TMS (1 microM-10 microM) reduced responses to iontophoretically applied GABA, as did picrotoxin (0.1-100 microM), PTZ (1-100 mM) and bicuculline (1-100 microM). 3. ES, in high concentrations (1-10 mM), reduced GABA responses to a lesser extent, and also occluded the reductions in GABA-evoked currents produced by TMS, picrotoxin, and PTZ. ES did not occlude the effects of bicuculline on GABA responses. Therefore, we propose that ES acts as a partial agonist at the picrotoxin GABA-blocking receptor. 4. MPS had no effect on GABA responses (at a concentration of 1 mM), and, like ES, occluded the GABA-blocking actions of TMS, apparently acting as a full antagonist. 5. The anticonvulsant actions of ES and MPS against TMS and PTZ-induced seizures may thus involve two independent mechanisms: (1) the occlusion of TMS and PTZ GABA-blocking effects; and (2) the previously described specific effect of ES and MPS on low-threshold calcium current of thalamic neurones. The latter cellular mechanism may be more closely related to petit mal anticonvulsant activity. PMID:2119843

  5. GABA promotes human β-cell proliferation and modulates glucose homeostasis.

    PubMed

    Purwana, Indri; Zheng, Juan; Li, Xiaoming; Deurloo, Marielle; Son, Dong Ok; Zhang, Zhaoyun; Liang, Christie; Shen, Eddie; Tadkase, Akshaya; Feng, Zhong-Ping; Li, Yiming; Hasilo, Craig; Paraskevas, Steven; Bortell, Rita; Greiner, Dale L; Atkinson, Mark; Prud'homme, Gerald J; Wang, Qinghua

    2014-12-01

    γ-Aminobutyric acid (GABA) exerts protective and regenerative effects on mouse islet β-cells. However, in humans it is unknown whether it can increase β-cell mass and improve glucose homeostasis. To address this question, we transplanted a suboptimal mass of human islets into immunodeficient NOD-scid-γ mice with streptozotocin-induced diabetes. GABA treatment increased grafted β-cell proliferation, while decreasing apoptosis, leading to enhanced β-cell mass. This was associated with increased circulating human insulin and reduced glucagon levels. Importantly, GABA administration lowered blood glucose levels and improved glucose excursion rates. We investigated GABA receptor expression and signaling mechanisms. In human islets, GABA activated a calcium-dependent signaling pathway through both GABA A receptor and GABA B receptor. This activated the phosphatidylinositol 3-kinase-Akt and CREB-IRS-2 signaling pathways that convey GABA signals responsible for β-cell proliferation and survival. Our findings suggest that GABA regulates human β-cell mass and may be beneficial for the treatment of diabetes or improvement of islet transplantation.

  6. Unique insecticide specificity of human homomeric rho 1 GABA(C) receptor.

    PubMed

    Ratra, Gurpreet S; Erkkila, Brian E; Weiss, David S; Casida, John E

    2002-03-24

    Several convulsants and major insecticides block the gamma-aminobutyric acid (GABA)-gated chloride channel in brain on binding to the GABA(A) receptor. The GABA(C) receptor, important in retina and present in brain, is also coupled to a chloride channel and is therefore a potential target for toxicant action examined here in radioligand binding and electrophysiological experiments. Human homomeric rho 1 GABA(C) receptor expressed in human embryonic kidney cells (HEK293) undergoes specific and saturable high-affinity binding of 4-n-[3H]propyl-4' -ethynylbicycloorthobenzoate ([3H]EBOB) using a cyano analog (CNBOB) to determine non-specific binding. This GABA(C) rho 1 receptor is very sensitive to CNBOB and lindane relative to alpha-endosulfan, tert-butylbicyclophosphorothionate, picrotoxinin and fipronil (IC(50) values of 23, 91, 800, 1080, 4000 and >10000 nM, respectively, in displacing [3H]EBOB). A similar potency sequence (except for picrotoxinin) is observed for inhibition of GABA-induced currents of rho 1 receptor expressed in Xenopus oocytes. The present study does not consider rho 2 homomeric and rho 1 rho 2 heteromeric GABA(C) receptors which are known to be more sensitive than rho 1 to picrotoxinin. The inhibitor sensitivity and specificity of this rho 1 GABA(C) receptor differ greatly from those of human homomeric beta 3 and native GABA(A) receptors.

  7. Edited Magnetic Resonance Spectroscopy Detects an Age-Related Decline in Nonhuman Primate Brain GABA Levels

    PubMed Central

    Killiany, Ronald J.

    2016-01-01

    Recent research had shown a correlation between aging and decreasing Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. However, how GABA level varies with age in the medial portion of the brain has not yet been studied. The purpose of this study was to investigate the GABA level variation with age focusing on the posterior cingulate cortex, which is the “core hub” of the default mode network. In this study, 14 monkeys between 4 and 21 years were recruited, and MEGA-PRESS MRS was performed to measure GABA levels, in order to explore a potential link between aging and GABA. Our results showed that a correlation between age and GABA+/Creatine ratio was at the edge of significance (r = −0.523, p = 0.081). There was also a near-significant trend between gray matter/white matter ratio and the GABA+/Creatine ratio (r = −0.518, p = 0.0848). Meanwhile, the correlation between age and grey matter showed no significance (r = −0.028, p = 0.93). Therefore, age and gray matter/white matter ratio account for different part of R-squared (adjusted R-squared = 0.5187) as independent variables for predicting GABA levels. Adjusted R-squared is about 0.5 for two independent variables. These findings suggest that there is internal neurochemical variation of GABA levels in the nonhuman primates associated with normal aging and structural brain decline. PMID:27660760

  8. An acidic amino acid transmembrane helix 10 residue conserved in the neurotransmitter:sodium:symporters is essential for the formation of the extracellular gate of the γ-aminobutyric acid (GABA) transporter GAT-1.

    PubMed

    Ben-Yona, Assaf; Kanner, Baruch I

    2012-03-01

    GAT-1 mediates transport of GABA together with sodium and chloride in an electrogenic process enabling efficient GABAergic transmission. Biochemical and modeling studies based on the structure of the bacterial homologue LeuT are consistent with a mechanism whereby the binding pocket is alternately accessible to either side of the membrane and which predicts that the extracellular part of transmembrane domain 10 (TM10) exhibits aqueous accessibility in the outward-facing conformation only. In this study we have engineered cysteine residues in the extracellular half of TM10 of GAT-1 and probed their state-dependent accessibility to sulfhydryl reagents. In three out of four of the accessible cysteine mutants, the inhibition of transport by a membrane impermeant sulfhydryl reagent was diminished under conditions expected to increase the proportion of inward-facing transporters, such as the presence of GABA together with the cotransported ions. A conserved TM10 aspartate residue, whose LeuT counterpart participates in a "thin" extracellular gate, was found to be essential for transport and only the D451E mutant exhibited residual transport activity. D451E exhibited robust sodium-dependent transient currents with a voltage-dependence indicative of an increased apparent affinity for sodium. Moreover the accessibility of an endogenous cysteine to a membrane impermeant sulfhydryl reagent was enhanced by the D451E mutation, suggesting that sodium binding promotes an outward-facing conformation of the transporter. Our results support the idea that TM10 of GAT-1 lines an accessibility pathway from the extracellular space into the binding pocket and plays a role in the opening and closing of the extracellular transporter gate.

  9. Amiloride and GMQ Allosteric Modulation of the GABA-A ρ1 Receptor: Influences of the Intersubunit Site.

    PubMed

    Snell, Heather D; Gonzales, Eric B

    2015-06-01

    Amiloride, a diuretic used in the treatment of hypertension and congestive heart failure, and 2-guanidine-4-methylquinazoline (GMQ) are guanidine compounds that modulate acid-sensing ion channels. Both compounds have demonstrated affinity for a variety of membrane proteins, including members of the Cys-loop family of ligand-gated ion channels, such as the heteromeric GABA-A αβγ receptors. The actions of these guanidine compounds on the homomeric GABA-A ρ1 receptor remains unclear, especially in light of how many GABA-A αβγ receptor modulators have different effects in the GABA-A ρ1 receptors. We sought to characterize the influence of amiloride and GMQ on the human GABA-A ρ1 receptors using whole-cell patch-clamp electrophysiology. The diuretic amiloride potentiated the human GABA-A ρ1 GABA-mediated current, whereas GMQ antagonized the receptor. Furthermore, a GABA-A second transmembrane domain site, the intersubunit site, responsible for allosteric modulation in the heteromeric GABA-A receptors mediated amiloride's positive allosteric actions. In contrast, the mutation did not remove GMQ antagonism but only changed the guanidine compound's potency within the human GABA-A ρ1 receptor. Through modeling and introduction of point mutations, we propose that the GABA-A ρ1 intersubunit site plays a role in mediating the allosteric effects of amiloride and GMQ.

  10. Amiloride and GMQ Allosteric Modulation of the GABA-A ρ1 Receptor: Influences of the Intersubunit Site

    PubMed Central

    Snell, Heather D.

    2015-01-01

    Amiloride, a diuretic used in the treatment of hypertension and congestive heart failure, and 2-guanidine-4-methylquinazoline (GMQ) are guanidine compounds that modulate acid-sensing ion channels. Both compounds have demonstrated affinity for a variety of membrane proteins, including members of the Cys-loop family of ligand-gated ion channels, such as the heteromeric GABA-A αβγ receptors. The actions of these guanidine compounds on the homomeric GABA-A ρ1 receptor remains unclear, especially in light of how many GABA-A αβγ receptor modulators have different effects in the GABA-A ρ1 receptors. We sought to characterize the influence of amiloride and GMQ on the human GABA-A ρ1 receptors using whole-cell patch-clamp electrophysiology. The diuretic amiloride potentiated the human GABA-A ρ1 GABA-mediated current, whereas GMQ antagonized the receptor. Furthermore, a GABA-A second transmembrane domain site, the intersubunit site, responsible for allosteric modulation in the heteromeric GABA-A receptors mediated amiloride’s positive allosteric actions. In contrast, the mutation did not remove GMQ antagonism but only changed the guanidine compound’s potency within the human GABA-A ρ1 receptor. Through modeling and introduction of point mutations, we propose that the GABA-A ρ1 intersubunit site plays a role in mediating the allosteric effects of amiloride and GMQ. PMID:25829529

  11. [PARTICIPATION OF NO-ERGIC MECHANISMS IN REALIZATION OF RESPIRATORY EFFECTS OF PRO-INFLAMMATORY CYTOKINE INTERLEUKIN-1-BETA].

    PubMed

    Aleksandrov, V G; Aleksandrova, N P; Tumanova, T S; Evseeva, A D; Merkuriev, V A

    2015-12-01

    The role of NO-ergic mechanisms in the realization of the respiratory effects of pro-inflammatory cytokine IL-1beta was investigated in acute experiments on anesthetized rats. To achieve this, we studied the effect of intravenous administration of IL-1beta during inhibition of NO-synthase by N-nitro-L-arginine methyl ester (L-NAME, a non-specific blocker of NO-synthase) on the parameters of breathing and the Hering-Breuer inspiratory-inhibitory reflex. It was shown that the effect of L-NAME eliminates the IL-1beta-dependent increase of the Hering-Breuer reflex, whereas effects on breathing pattern does not change: the increase in IL-1beta system-level evokes an increase in respiratory rate, tidal volume and lung ventilation. It is assumed that one of the mechanisms of enhance in the strength inspiratory-inhibitory reflex by increasing circulatory IL-1beta level is the increased glutamate-ergic transmission on pump-neurons induced by increase in nitric oxide synthesis in cerebrovascular endothelial cells. In conclusion, NO-ergic mechanisms participate in the modulation of the vagal respiratory reflexes during the development of the acute phase of systemic inflammation.

  12. Potentiation of the ionotropic GABA receptor response by whiskey fragrance.

    PubMed

    Hossain, Sheikh Julfikar; Aoshima, Hitoshi; Koda, Hirofumi; Kiso, Yoshinobu

    2002-11-01

    It is well-known that the target of most mood-defining compounds is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activity in the human brain. To study the effects of whiskey fragrance on the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting rat whole brain mRNA or cRNA prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors. Most whiskey components such as phenol, ethoxy, and lactone derivatives potentiated the electrical responses of GABA(A) receptors, especially ethyl phenylpropanoate (EPP), which strongly potentiated the response. When this compound was applied to mice through respiration, the convulsions induced by pentetrazole were delayed, suggesting that EPP was absorbed by the brain, where it could potentiate the GABA(A) receptor responses. The extract of other alcoholic drinks such as wine, sake, brandy, and shochu also potentiated the responses to varying degrees. Although these fragrant components are present in alcoholic drinks at low concentrations (extremely small quantities compared with ethanol), they may also modulate the mood or consciousness of the human through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic fragrant compounds are easily absorbed into the brain through the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response.

  13. Potentiation of the ionotropic GABA receptor response by whiskey fragrance.

    PubMed

    Hossain, Sheikh Julfikar; Aoshima, Hitoshi; Koda, Hirofumi; Kiso, Yoshinobu

    2002-11-01

    It is well-known that the target of most mood-defining compounds is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activity in the human brain. To study the effects of whiskey fragrance on the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting rat whole brain mRNA or cRNA prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors. Most whiskey components such as phenol, ethoxy, and lactone derivatives potentiated the electrical responses of GABA(A) receptors, especially ethyl phenylpropanoate (EPP), which strongly potentiated the response. When this compound was applied to mice through respiration, the convulsions induced by pentetrazole were delayed, suggesting that EPP was absorbed by the brain, where it could potentiate the GABA(A) receptor responses. The extract of other alcoholic drinks such as wine, sake, brandy, and shochu also potentiated the responses to varying degrees. Although these fragrant components are present in alcoholic drinks at low concentrations (extremely small quantities compared with ethanol), they may also modulate the mood or consciousness of the human through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic fragrant compounds are easily absorbed into the brain through the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response. PMID:12405783

  14. [Effect of naloxone on the activity of Cl(-)-activated Mg(2+)-ATPase from plasma membrane fraction of the common bream brain (Abramis brama L.) in the presence of GABAa-ergic substances].

    PubMed

    Menzikov, S A; Menzikova, O V

    2003-01-01

    We studied the effect of naloxone--an antagonist of the opioid receptors--on sensitivity of Cl(-)-activated Mg(2+)-ATPase from the plasma membrane fraction of bream brain (Abramis brama L.) to GABAa-ergic substances. Preincubation of the plasma membranes with 1-100 microM naloxone increased the basal Mg(2+)-ATPase activity and suppressed its activation by chloride ions. The same effects were observed in the presence of the agonists of GABAa/benzodiazepine receptors: 0.1-100 microM GABA, 1-500 microM pentobarbital, and 0.1-100 microM phenazepam. Naloxone (10 microM) inhibited the activation of the basal Mg(2+)-ATPase by the studied ligands and regenerated the enzyme sensitivity to Cl-. However, the effect of naloxone was not observed in the presence of high concentrations of pentobarbital (500 microM) and phenazepam (100 microM). The obtained data show that naloxone modulates the activity of Cl(-)-activated Mg(2+)-ATPase from the plasma membranes of bream brain and antagonizes the GABAa receptor ligands.

  15. Role of proline and GABA in sexual reproduction of angiosperms.

    PubMed

    Biancucci, Marco; Mattioli, Roberto; Forlani, Giuseppe; Funck, Dietmar; Costantino, Paolo; Trovato, Maurizio

    2015-01-01

    Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabidopsis mutants affected in the first and rate-limiting step in proline synthesis produce aberrant and infertile pollen grains, indicating that proline synthesis is required for pollen development and fertility. Concerning GABA, a large body of evidence points to this glutamate derivative as a key determinant of post-pollination fertilization. Intriguingly, proline has also been associated with pollination, another aspect of sexual reproduction, since honeybees were reported to show a strong preference for proline-enriched nectars. In this review, we survey current knowledge on the roles of proline and GABA in plant fertility, and discuss future perspectives potentially capable to improve our understanding on the functions of these amino acids in pollen development, pollination, and pollen tube guidance.

  16. Role of proline and GABA in sexual reproduction of angiosperms

    PubMed Central

    Biancucci, Marco; Mattioli, Roberto; Forlani, Giuseppe; Funck, Dietmar; Costantino, Paolo; Trovato, Maurizio

    2015-01-01

    Two glutamate derivatives, proline and γ-aminobutyric acid (GABA), appear to play pivotal roles in different aspects of sexual reproduction in angiosperms, although their precise function in plant reproduction and the molecular basis of their action are not yet fully understood. Proline and GABA have long been regarded as pivotal amino acids in pollen vitality and fertility. Proline may constitute up to 70% of the free amino acid pool in pollen grains and it has been recently shown that Arabidopsis mutants affected in the first and rate-limiting step in proline synthesis produce aberrant and infertile pollen grains, indicating that proline synthesis is required for pollen development and fertility. Concerning GABA, a large body of evidence points to this glutamate derivative as a key determinant of post-pollination fertilization. Intriguingly, proline has also been associated with pollination, another aspect of sexual reproduction, since honeybees were reported to show a strong preference for proline-enriched nectars. In this review, we survey current knowledge on the roles of proline and GABA in plant fertility, and discuss future perspectives potentially capable to improve our understanding on the functions of these amino acids in pollen development, pollination, and pollen tube guidance. PMID:26388884

  17. Actions of insecticides on the insect GABA receptor complex

    SciTech Connect

    Bermudez, I.; Hawkins, C.A.; Taylor, A.M.; Beadle, D.J. )

    1991-01-01

    The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using (35S)t-butylbicyclophosphorothionate (( 35S)TBPS) binding and voltage-clamp techniques. Specific binding of (35S)TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 {plus minus} 2.9 nM and a Bmax value of 1770 {plus minus} 40 fmol/mg protein. (35S)TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of (35S)TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on (35S)TBPS binding. These results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current.

  18. Cytoskeletal rearrangement and Src and PI-3K-dependent Akt activation control GABA(B)R-mediated chemotaxis.

    PubMed

    Barati, Michelle T; Lukenbill, Janice; Wu, Rui; Rane, Madhavi J; Klein, Jon B

    2015-06-01

    The γ-amino butyric acid (GABA) type B receptors (GABA(B)R) function as chemoattractant receptors in response to GABA(B)R agonists in human neutrophils. The goal of this study was to define signaling mechanisms regulating GABA(B)R-mediated chemotaxis and cytoskeletal rearrangement. In a proteomic study we identified serine/threonine kinase Akt, tyrosine kinases Src and Pyk2, microtubule regulator kinesin and microtubule affinity-regulating kinase (MARK) co-immunoprecipitating with GABA(B)R. To define the contributions of these candidate signaling events in GABA(B)R-mediated chemotaxis, we used rat basophilic leukemic cells (RBL-2H3 cells) stably transfected with human GABA(B1b) and GABA(B2) receptors. The GABA(B)R agonist baclofen induced Akt phosphorylation and chemotaxis by binding to its specific GABA(B)R since pretreatment of cells with CGP52432, a GABA(B)R antagonist, blocked such effects. Moreover, baclofen induced Akt phosphorylation was shown to be dependent upon PI-3K and Src kinases. Baclofen failed to stimulate actin polymerization in suspended RBL cells unless exposed to a baclofen gradient. However, baclofen stimulated both actin and tubulin polymerization in adherent RBL-GABA(B)R cells. Blockade of actin and tubulin polymerization by treatment of cells with cytochalasin D or nocodazole respectively, abolished baclofen-mediated chemotaxis. Furthermore, baclofen stimulated Pyk2 and STAT3 phosphorylation, both known regulators of cell migration. In conclusion, GABA(B)R stimulation promotes chemotaxis in RBL cells which is dependent on signaling via PI3-K/Akt, Src kinases and on rearrangement of both microtubules and actin cytoskeleton. These data define mechanisms of GABA(B)R-mediated chemotaxis which may potentially be used to therapeutically regulate cellular response to injury and disease.

  19. Microperfusion of 3-MPA into the brain augments GABA

    PubMed Central

    Mayer, Andrew P.; Osorio, Ivan; Lunte, Craig E.

    2014-01-01

    In vivo effects of microperfusion of a GABA synthesis inhibitor (3-MPA) into the striatum and hippocampus on amino acid concentrations and electrical neuronal activity were investigated. Paradoxical elevations in GABA in the striatum (5-fold in anesthetized and 50-fold in awake rats) and hippocampus (2-fold in anesthetized and 15-fold in awake rats) were documented under steady-state concentrations of 3-MPA along with expected increases in glutamate (a 15-fold increase and a 250-fold increase in the striatum of anesthetized and awake rats, respectively; a 7-fold increase and a 25-fold increase in the hippocampus of anesthetized and awake rats, respectively). There was no clear epileptiform or seizure activity. Explanations for the paradoxical increase in GABA are offered, and emphasis is placed on the dependency of disinhibition on the model in which its effects are studied as well as on the prevailing level of activation of the probed network. PMID:24094842

  20. Intracellular calcium ions decrease the affinity of the GABA receptor.

    PubMed

    Inoue, M; Oomura, Y; Yakushiji, T; Akaike, N

    Intracellular free Ca2+ [( Ca2+]i) plays a crucial role in the transduction of extracellular signals. It has been implicated in the modulation of light sensitivity in Limulus photoreceptors and in the efficacy of synaptic transmission; calcium ion fluxes are also involved in the postsynaptic facilitation of nicotinic transmission seen in sympathetic ganglia, and in activation of the acetylcholine (ACh) receptor. [Ca2+]i is also a second messenger for many biologically active substances. We recorded neuronal activities of sensory neurones from the bullfrog (Rana catesbiana), using the suction pipette method and a 'concentration clamp' technique to apply gamma-aminobutyric acid (GABA) to the cell. We report the first evidence that [Ca2+]i suppresses the GABA-activated Cl- conductance, by decreasing the apparent affinity of the GABA receptor. PMID:2431316

  1. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters

    PubMed Central

    Ramesh, Sunita A.; Tyerman, Stephen D.; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A.; Ryan, Peter R.; Gillham, Matthew

    2015-01-01

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms. PMID:26219411

  2. Insect Herbivory-Elicited GABA Accumulation in Plants is a Wound-Induced, Direct, Systemic, and Jasmonate-Independent Defense Response.

    PubMed

    Scholz, Sandra S; Reichelt, Michael; Mekonnen, Dereje W; Ludewig, Frank; Mithöfer, Axel

    2015-01-01

    The non-proteinogenic amino acid γ-aminobutyric acid (GABA) is present in all organisms analyzed so far. In invertebrates GABA acts as a neurotransmitter; in plants different functions are under discussion. Among others, its involvement in abiotic stress reactions and as a defensive compound against feeding insects is suggested. GABA is synthesized from glutamate by glutamate decarboxylases and degraded by GABA-transaminases. Here, in Arabidopsis thaliana, gad1/2 double mutants showing reduced GABA concentrations as well as GABA-enriched triple mutants (gad1/2 x pop2-5) were generated and employed for a systematic study of GABA induction, accumulation and related effects in Arabidopsis leaves upon herbivory. The results demonstrate that GABA accumulation is stimulated by insect feeding-like wounding by a robotic caterpillar, MecWorm, as well as by real insect (Spodoptera littoralis) herbivory. Higher GABA levels in both plant tissue and artificial dietary supplements in turn affect the performance of feeding larvae. GABA enrichment occurs not only in the challenged but also in adjacent leaf. This induced response is neither dependent on herbivore defense-related phytohormones, jasmonates, nor is jasmonate induction dependent on the presence of GABA. Thus, in Arabidopsis the rapid accumulation of GABA very likely represents a general, direct and systemic defense reaction against insect herbivores. PMID:26734035

  3. Insect Herbivory-Elicited GABA Accumulation in Plants is a Wound-Induced, Direct, Systemic, and Jasmonate-Independent Defense Response

    PubMed Central

    Scholz, Sandra S.; Reichelt, Michael; Mekonnen, Dereje W.; Ludewig, Frank; Mithöfer, Axel

    2015-01-01

    The non-proteinogenic amino acid γ-aminobutyric acid (GABA) is present in all organisms analyzed so far. In invertebrates GABA acts as a neurotransmitter; in plants different functions are under discussion. Among others, its involvement in abiotic stress reactions and as a defensive compound against feeding insects is suggested. GABA is synthesized from glutamate by glutamate decarboxylases and degraded by GABA-transaminases. Here, in Arabidopsis thaliana, gad1/2 double mutants showing reduced GABA concentrations as well as GABA-enriched triple mutants (gad1/2 x pop2-5) were generated and employed for a systematic study of GABA induction, accumulation and related effects in Arabidopsis leaves upon herbivory. The results demonstrate that GABA accumulation is stimulated by insect feeding-like wounding by a robotic caterpillar, MecWorm, as well as by real insect (Spodoptera littoralis) herbivory. Higher GABA levels in both plant tissue and artificial dietary supplements in turn affect the performance of feeding larvae. GABA enrichment occurs not only in the challenged but also in adjacent leaf. This induced response is neither dependent on herbivore defense-related phytohormones, jasmonates, nor is jasmonate induction dependent on the presence of GABA. Thus, in Arabidopsis the rapid accumulation of GABA very likely represents a general, direct and systemic defense reaction against insect herbivores. PMID:26734035

  4. Does extracellular calcium determine what pool of GABA is the target for alpha-latrotoxin?

    PubMed

    Storchak, L G; Linetska, M V; Himmelreich, N H

    2002-04-01

    Presynaptic neurotoxin alpha-latrotoxin, from the venom of Latrodectus mactans tredecimguttatus, causes massive [(3)H]GABA release from rat brain synaptosomes, irrespective of calcium presence in the extracellular medium. Whether the binding of alpha-latrotoxin to Ca(2+)-dependent (neurexin 1 alpha) or to Ca(2+)-independent (latrophilin) receptor triggers [(3)H]GABA release by the same mechanisms or different ones, inducing either exocytotic process or outflow by mobile membrane GABA transporter, is unknown. We examined alpha-latrotoxin-evoked [(3)H]GABA release from synaptosomes which cytosolic [(3)H]GABA pool was depleted either by applying competitive inhibitors of the GABA transporter, nipecotic acid and 2,4-diaminobutyric acid, or by permeation with digitonin. We also compared the effect of the GABA transporter inhibitors on depolarisation-evoked and alpha-latrotoxin-evoked [(3)H]GABA release using as depolarising agents 4-aminopyridine and high KCl in the Ca(2+)-containing and in Ca(2+)-free medium, respectively. Incubation of synaptosomes with nipecotic acid induced the essential acceleration of unstimulated [(3)H]GABA release and deep inhibition of high KCl-evoked Ca(2+)-independent [(3)H]GABA release. In contrast, at the similar conditions the effect of alpha-latrotoxin was greatly augmented with respect to the control response. Another way to assay what GABA pool was involved in alpha-latrotoxin-induced release lays in an analysis of the effects of depolarisation and alpha-latrotoxin in consecutive order. The preliminary 4-aminopyridine-stimulated [(3)H]GABA release attenuated the toxin effect. But when depolarisation occurred in Ca(2+)-free medium, no influence on alpha-latrotoxin effect was revealed. Employing digitonin-permeated synaptosomes, we have shown that alpha-latrotoxin could stimulate [3H]GABA release in the medium with 1mM EGTA, this effect of the toxin was blocked by concanavalin A and was ATP-dependent. The latter suggests that alpha

  5. Actions of picrotoxinin analogues on an expressed, homo-oligomeric GABA receptor of Drosophila melanogaster.

    PubMed

    Shirai, Y; Hosie, A M; Buckingham, S D; Holyoke, C W; Baylis, H A; Sattelle, D B

    1995-04-01

    The actions of picrotoxinin and four of its analogues were tested on a Drosophila melanogaster homo-oligomeric GABA (gamma-aminobutyric acid) receptor formed when RDL (resistance to dieldrin) subunits were expressed in Xenopus oocytes. In agreement with previously reported studies on native insect GABA receptors and native expressed vertebrate GABA receptors, acetylation of the bridgehead hydroxyl group (picrotoxinin acetate) greatly reduced the activity of the molecule, but surprisingly, substitution with flourine at the same position also reduced the activity. Conversion of the terminal isopropenyl group to an acetyl (alpha-picrotoxinone) or hydration of the double bond (picrotin) also reduced activity, in agreement with findings for native insect and mammalian receptors. The present results suggest that interactions of convulsants with homo-oligomeric and multimeric GABA receptors are qualitatively similar. Thus, the RDL homo-oligomer exhibits a pharmacological profile for picrotoxinin analogues resembling that of native GABA receptors. PMID:7603613

  6. [MOLECULAR MECHANISMS OF ERK1/2 KINASES REGULATION IN THE GLUTAMATE- AND GABA-ERGIC NEURONS DURING SEIZURE EXPRESSION IN KRUSHINSKY-MOLODKINA RATS].

    PubMed

    Korotkov, A A; Glazova, M V; Nikitina, L S; Dorofeeva, N A; Kirillova, O D; Chernigovskaya, E V

    2015-10-01

    The aim of the present study was to analyze a role of the ERK1/2 signaling pathway in the regulation of excitation and inhibitory neurons in the hippocampus and the temporal cortex of Krushinsky-Molodkina rats during seizure development finalizing with ataxia. Analysis was done by Western bloting as well as by immunohistochemistry. The results demonstrated significant up-regulation of ERK1/2 activity in the hippocampus in several seconds after sound stimulation. At the same time increased ERK1/2 activity was correlated with enhanced level of SNARE protein SNAP-25 and activation of synapsin I, the proteins which regulate exocytosis machinery. Decreased level of VGLUT2 associated with activation of ERK1/2 and exocytosis proteins supposed activation of glutamate release in the hippocampus, while in the temporal cortex diminished activity of ERK1/2 and synapsin I associated with VGLUT2 up-regulation assumed inhibition of glutamatergic transmission. Our data let us supposed that decreasing of glutamate release in th& temporal cortex could be a trigger for the inhibition of hippocampal glutamatergic system and the beginning of further ataxia stage. Our data demonstrated correlation between expression and activity of exocytosis proteins and ERK1/2 mainly in the glutamategic neurons of the hippocampus and the temporal cortex that let us proposed significant role of ERK1/2 kinases as a positive regulator of glutamate release and as a result initiation of seizure expression. PMID:26827493

  7. Temperature dependence and GABA modulation of (TH)triazolam binding in the rat brain

    SciTech Connect

    Earle, M.E.; Concas, A.; Wamsley, J.K.; Yamamura, H.I.

    1987-07-27

    The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of (TH)TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0C; K/sub d/ = 1.96 +/- 0.85 nM at 37C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0C and 1160 +/- 383 fmoles/mg protein at 37C). Saturation studies of (TH)TZ binding in the presence or absence of GABA (100 M) showed a GABA-shift. At 0C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables.

  8. Segregation of Acetylcholine and GABA in the Rat Superior Cervical Ganglia: Functional Correlation

    PubMed Central

    Elinos, Diana; Rodríguez, Raúl; Martínez, Luis Andres; Zetina, María Elena; Cifuentes, Fredy; Morales, Miguel Angel

    2016-01-01

    Sympathetic neurons have the capability to segregate their neurotransmitters (NTs) and co-transmitters to separate varicosities of single axons; furthermore, in culture, these neurons can even segregate classical transmitters. In vivo sympathetic neurons employ acetylcholine (ACh) and other classical NTs such as gamma aminobutyric acid (GABA). Herein, we explore whether these neurons in vivo segregate these classical NTs in the superior cervical ganglia of the rat. We determined the topographical distribution of GABAergic varicosities, somatic GABAA receptor, as well as the regional distribution of the segregation of ACh and GABA. We evaluated possible regional differences in efficacy of ganglionic synaptic transmission, in the sensitivity of GABAA receptor to GABA and to the competitive antagonist picrotoxin (PTX). We found that sympathetic preganglionic neurons in vivo do segregate ACh and GABA. GABAergic varicosities and GABAA receptor expression showed a rostro-caudal gradient along ganglia; in contrast, segregation exhibited a caudo-rostral gradient. These uneven regional distributions in expression of GABA, GABAA receptors, and level of segregation correlate with stronger synaptic transmission found in the caudal region. Accordingly, GABAA receptors of rostral region showed larger sensitivity to GABA and PTX. These results suggest the presence of different types of GABAA receptors in each region that result in a different regional levels of endogenous GABA inhibition. Finally, we discuss a possible correlation of these different levels of GABA modulation and the function of the target organs innervated by rostral and caudal ganglionic neurons. PMID:27092054

  9. Mutation of the Drosophila vesicular GABA transporter disrupts visual figure detection

    PubMed Central

    Fei, Hao; Chow, Dawnis M.; Chen, Audrey; Romero-Calderón, Rafael; Ong, Wei S.; Ackerson, Larry C.; Maidment, Nigel T.; Simpson, Julie H.; Frye, Mark A.; Krantz, David E.

    2010-01-01

    The role of gamma amino butyric acid (GABA) release and inhibitory neurotransmission in regulating most behaviors remains unclear. The vesicular GABA transporter (VGAT) is required for the storage of GABA in synaptic vesicles and provides a potentially useful probe for inhibitory circuits. However, specific pharmacologic agents for VGAT are not available, and VGAT knockout mice are embryonically lethal, thus precluding behavioral studies. We have identified the Drosophila ortholog of the vesicular GABA transporter gene (which we refer to as dVGAT), immunocytologically mapped dVGAT protein expression in the larva and adult and characterized a dVGATminos mutant allele. dVGAT is embryonically lethal and we do not detect residual dVGAT expression, suggesting that it is either a strong hypomorph or a null. To investigate the function of VGAT and GABA signaling in adult visual flight behavior, we have selectively rescued the dVGAT mutant during development. We show that reduced GABA release does not compromise the active optomotor control of wide-field pattern motion. Conversely, reduced dVGAT expression disrupts normal object tracking and figure–ground discrimination. These results demonstrate that visual behaviors are segregated by the level of GABA signaling in flies, and more generally establish dVGAT as a model to study the contribution of GABA release to other complex behaviors. PMID:20435823

  10. Effect of GABA, a bacterial metabolite, on Pseudomonas fluorescens surface properties and cytotoxicity.

    PubMed

    Dagorn, Audrey; Chapalain, Annelise; Mijouin, Lily; Hillion, Mélanie; Duclairoir-Poc, Cécile; Chevalier, Sylvie; Taupin, Laure; Orange, Nicole; Feuilloley, Marc G J

    2013-01-01

    Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA) and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens. Exposure of a psychotropic strain of P. fluorescens (MF37) to GABA (10-5 M) increased its necrotic-like activity on eukaryotic (glial) cells, but reduced its apoptotic effect. Conversely, muscimol and bicuculline, the selective agonist and antagonist of eukaryote GABAA receptors, respectively, were ineffective. P. fluorescens MF37 did not produce biosurfactants, and its caseinase, esterase, amylase, hemolytic activity or pyoverdine productions were unchanged. In contrast, the effect of GABA was associated to rearrangements of the lipopolysaccharide (LPS) structure, particularly in the lipid A region. The surface hydrophobicity of MF37 was marginally modified, and GABA reduced its biofilm formation activity on PVC, but not on glass, although the initial adhesion was increased. Five other P. fluorescens strains were studied, and only one, MFP05, a strain isolated from human skin, showed structural differences of biofilm maturation after exposure to GABA. These results reveal that GABA can regulate the LPS structure and cytotoxicity of P. fluorescens, but that this property is specific to some strains. PMID:23743829

  11. GABA-shunt enzymes activity in GH3 cells with reduced level of PMCA2 or PMCA3 isoform

    SciTech Connect

    Kowalski, Antoni

    2011-08-12

    Highlights: {yields} Suppression of PMCA2 or PMCA3 slows down proliferation of GH3 cells. {yields} PMCA2 suppression lowers the activity of GABA-shunt enzymes. {yields} PMCA3 suppression increases the expression of glutamate decarboxylase 65. {yields} PMCA2 and PMCA3 function appears to be linked to regulation of GABA metabolism. -- Abstract: GABA ({gamma}-aminobutyric acid) is important neurotransmitter and regulator of endocrine functions. Its metabolism involves three enzymes: glutamate decarboxylase (GAD65 and GAD67), GABA aminotransferase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH). As many cellular processes GABA turnover can depend on calcium homeostasis, which is maintained by plasma membrane calcium ATPases (PMCAs). In excitable cells PMCA2 and PMCA3 isoforms are particularly important. In this study we focused on GABA-metabolizing enzymes expression and activity in rat anterior pituitary GH3 cells with suppressed expression of PMCA2 or PMCA3. We observed that PMCA3-reduced cells have increased GAD65 expression. Suppression of PMCA2 caused a decrease in total GAD and GABA-T activity. These results indicate that PMCA2 and PMCA3 presence may be an important regulatory factor in GABA metabolism. Results suggest that PMCA2 and PMCA3 function is rather related to regulation of GABA synthesis and degradation than supplying cells with metabolites, which can be potentially energetic source.

  12. Fabrication of the Optical Fiber GABA Sensor Based on the NADP+ -Functionalized Quantum Dots.

    PubMed

    Zhao, Fei; Yoo, Jeongha; Kim, Jongsung

    2016-02-01

    A novel quantum dots (QDs)-based optical fiber biosensor has been developed to detect gamma-amino butyric acid (GABA) directly, via QD fluorescence quenching and recovery. QDs were immobilized on the surface of an optical-fiber through the EDC/Sulfo-NHS coupling reaction. The QDs were functionalized by 3-aminophenyl boronic acid and then by NADP+. The fluorescence of the NADP+ -functionalized QDs was quenched by electron transfer from QDs to NADP+. However, by the metabolic conversion of GABA to succinic acid by GABase, NADP+ was reduced to NADPH, which hindered the electron transfer. As a result, the fluorescence of the QDs could recover. The recovery rate of the fluorescence intensity of QDs depended on the concentration of GABA. This shows the possibility of detection of low concentrations of GABA via measurement of the fluorescence intensity.

  13. Fabrication of the Optical Fiber GABA Sensor Based on the NADP+ -Functionalized Quantum Dots.

    PubMed

    Zhao, Fei; Yoo, Jeongha; Kim, Jongsung

    2016-02-01

    A novel quantum dots (QDs)-based optical fiber biosensor has been developed to detect gamma-amino butyric acid (GABA) directly, via QD fluorescence quenching and recovery. QDs were immobilized on the surface of an optical-fiber through the EDC/Sulfo-NHS coupling reaction. The QDs were functionalized by 3-aminophenyl boronic acid and then by NADP+. The fluorescence of the NADP+ -functionalized QDs was quenched by electron transfer from QDs to NADP+. However, by the metabolic conversion of GABA to succinic acid by GABase, NADP+ was reduced to NADPH, which hindered the electron transfer. As a result, the fluorescence of the QDs could recover. The recovery rate of the fluorescence intensity of QDs depended on the concentration of GABA. This shows the possibility of detection of low concentrations of GABA via measurement of the fluorescence intensity. PMID:27433599

  14. The blockade of GABA mediated responses in the frog spinal cord by ammonium ions and furosemide.

    PubMed Central

    Nicoll, R A

    1978-01-01

    1. A variety of compounds which are known to block chloride transport in a variety of systems have been examined for their effects on amino acid and synaptic responses in the frog spinal cord in vitro. 2. A number of monocarboxylic aromatic acids, copper sulphate, and acetazolamide had no effect on any of the responses. 3. Ammonium ions blocked the motoneurone hyperpolarizing responses to all the neutral amino acids. In addition it selectively blocked dorsal root potentials and the action of GABA and beta-alanine on primary afferents. 5. Intracellular recording from dorsal root ganglion cells demonstrated that furosemide had little effect on the reversal potential for the GABA response. These results suggest that furosemide acts primarily by blocking the conductance increase elicited by GABA. 6. The results with furosemide provide indirect evidence that chloride ions are involved in generating the GABA depolarizations of primary afferent terminals and dorsal root potentials. PMID:722571

  15. Vesicular GABA transporter (VGAT) transports β-alanine.

    PubMed

    Juge, Narinobu; Omote, Hiroshi; Moriyama, Yoshinori

    2013-11-01

    Vesicular GABA transporter (VGAT) is expressed in GABAergic and glycinergic neurons, and is responsible for vesicular storage and subsequent exocytosis of these inhibitory amino acids. In this study, we show that VGAT recognizes β-alanine as a substrate. Proteoliposomes containing purified VGAT transport β-alanine using Δψ but not ΔpH as a driving force. The Δψ-driven β-alanine uptake requires Cl(-). VGAT also facilitates Cl(-) uptake in the presence of β-alanine. A previously described VGAT mutant (Glu213Ala) that disrupts GABA and glycine transport similarly abrogates β-alanine uptake. These findings indicated that VGAT transports β-alanine through a mechanism similar to those for GABA and glycine, and functions as a vesicular β-alanine transporter. Vesicular GABA transporter (VGAT) is expressed in GABAergic and glycinergic neurons, and is responsible for vesicular storage and subsequent exocytosis of these inhibitory amino acids. In the present study, we showed that proteoliposomes containing purified VGAT transport β-alanine using Δψ as a driving force. VGAT also facilitates Cl(-) uptake. Our findings indicated that VGAT functions as a vesicular β-alanine transporter.

  16. A comparative density functional theory study of electronic structure and optical properties of γ-aminobutyric acid and its cocrystals with oxalic and benzoic acid

    NASA Astrophysics Data System (ADS)

    da Silva Filho, J. G.; Freire, V. N.; Caetano, E. W. S.; Ladeira, L. O.; Fulco, U. L.; Albuquerque, E. L.

    2013-11-01

    In this letter, we study the electronic structure and optical properties of the active medicinal component γ-aminobutyric acid (GABA) and its cocrystals with oxalic (OXA) and benzoic (BZA) acid by means of the density functional theory formalism. It is shown that the cocrystallization strongly weakens the zwitterionic character of the GABA molecule leading to striking differences among the electronic band structures and optical absorption spectra of the GABA crystal and GABA:OXA, GABA:BZA cocrystals, originating from distinct sets of hydrogen bonds. Calculated band widths and Δ-sol band gap estimates indicate that both GABA and GABA:OXA, GABA:BZA cocrystals are indirect gap insulators.

  17. GABA Production in Lactococcus lactis Is Enhanced by Arginine and Co-addition of Malate.

    PubMed

    Laroute, Valérie; Yasaro, Chonthicha; Narin, Waranya; Mazzoli, Roberto; Pessione, Enrica; Cocaign-Bousquet, Muriel; Loubière, Pascal

    2016-01-01

    Lactococcus lactis NCDO 2118 was previously selected for its ability to decarboxylate glutamate to γ-aminobutyric acid (GABA), an interesting nutritional supplement able to improve mood and relaxation. Amino acid decarboxylation is generally considered as among the biochemical systems allowing lactic acid bacteria to counteracting acidic stress and obtaining metabolic energy. These strategies also include arginine deiminase pathway and malolactic fermentation but little is known about their possible interactions of with GABA production. In the present study, the effects of glutamate, arginine, and malate (i.e., the substrates of these acid-resistance pathways) on L. lactis NCDO 2118 growth and GABA production performances were analyzed. Both malate and arginine supplementation resulted in an efficient reduction of acidity and improvement of bacterial biomass compared to glutamate supplementation. Glutamate decarboxylation was limited to narrow environmental conditions (pH < 5.1) and physiological state (stationary phase). However, some conditions were able to improve GABA production or activate glutamate decarboxylation system even outside of this compass. Arginine clearly stimulated glutamate decarboxylation: the highest GABA production (8.6 mM) was observed in cultures supplemented with both arginine and glutamate. The simultaneous addition of arginine, malate, and glutamate enabled earlier GABA production (i.e., during exponential growth) at relatively high pH (6.5). As far as we know, no previous study has reported GABA production in such conditions. Although further studies are needed to understand the molecular basis of these phenomena, these results represent important keys suitable of application in GABA production processes. PMID:27458444

  18. Glutamate and GABA activate different receptors and Cl(-) conductances in crab peptide-secretory neurons.

    PubMed

    Duan, S; Cooke, I M

    2000-01-01

    Responses to rapid application of glutamic acid (Glu) and gamma-aminobutyric acid (GABA), 0.01-3 mM, were recorded by whole-cell patch clamp of cultured crab (Cardisoma carnifex) X-organ neurons. Responses peaked within 200 ms. Both Glu and GABA currents had reversal potentials that followed the Nernst Cl(-) potential when [Cl(-)](i) was varied. A Boltzmann fit to the normalized, averaged dose-response curve for Glu indicated an EC(50) of 0.15 mM and a Hill coefficient of 1.05. Rapid (t(1/2) approximately 1 s) desensitization occurred during Glu but not GABA application that required >2 min for recovery. Desensitization was unaffected by concanavalin A or cyclothiazide. N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, quisqualate, and kainate (to 1 mM) were ineffective, nor were Glu responses influenced by glycine (1 microM) or Mg(2+) (0-26 mM). Glu effects were imitated by ibotenic acid (0.1 mM). The following support the conclusion that Glu and GABA act on different receptors: 1) responses sum; 2) desensitization to Glu or ibotenic acid did not diminish GABA responses; 3) the Cl(-)-channel blockers picrotoxin and niflumic acid (0.5 mM) inhibited Glu responses by approximately 90 and 80% but GABA responses by approximately 50 and 20%; and 4) polyvinylpyrrolydone-25 (2 mM in normal crab saline) eliminated Glu responses but left GABA responses unaltered. Thus crab secretory neurons have separate receptors responsive to Glu and to GABA, both probably ionotropic, and mediating Cl(-) conductance increases. In its responses and pharmacology, this crustacean Glu receptor resembles Cl(-)-permeable Glu receptors previously described in invertebrates and differs from cation-permeable Glu receptors of vertebrates and invertebrates.

  19. GABA Production in Lactococcus lactis Is Enhanced by Arginine and Co-addition of Malate

    PubMed Central

    Laroute, Valérie; Yasaro, Chonthicha; Narin, Waranya; Mazzoli, Roberto; Pessione, Enrica; Cocaign-Bousquet, Muriel; Loubière, Pascal

    2016-01-01

    Lactococcus lactis NCDO 2118 was previously selected for its ability to decarboxylate glutamate to γ-aminobutyric acid (GABA), an interesting nutritional supplement able to improve mood and relaxation. Amino acid decarboxylation is generally considered as among the biochemical systems allowing lactic acid bacteria to counteracting acidic stress and obtaining metabolic energy. These strategies also include arginine deiminase pathway and malolactic fermentation but little is known about their possible interactions of with GABA production. In the present study, the effects of glutamate, arginine, and malate (i.e., the substrates of these acid-resistance pathways) on L. lactis NCDO 2118 growth and GABA production performances were analyzed. Both malate and arginine supplementation resulted in an efficient reduction of acidity and improvement of bacterial biomass compared to glutamate supplementation. Glutamate decarboxylation was limited to narrow environmental conditions (pH < 5.1) and physiological state (stationary phase). However, some conditions were able to improve GABA production or activate glutamate decarboxylation system even outside of this compass. Arginine clearly stimulated glutamate decarboxylation: the highest GABA production (8.6 mM) was observed in cultures supplemented with both arginine and glutamate. The simultaneous addition of arginine, malate, and glutamate enabled earlier GABA production (i.e., during exponential growth) at relatively high pH (6.5). As far as we know, no previous study has reported GABA production in such conditions. Although further studies are needed to understand the molecular basis of these phenomena, these results represent important keys suitable of application in GABA production processes. PMID:27458444

  20. GABA release from mouse axonal growth cones

    PubMed Central

    Gao, Xiao-Bing; van den Pol, Anthony N

    2000-01-01

    Using developing hypothalamic neurons from transgenic mice that express high levels of green fluorescent protein in growing axons, and an outside-out patch from mature neuronal membranes that contain neurotransmitter receptors as a sensitive detector, we found that GABA is released by a vesicular mechanism from the growth cones of developing axons prior to synapse formation. A low level of GABA release occurs spontaneously from the growth cone, and this is substantially increased by evoked action potentials. Neurotransmitters such as acetylcholine can enhance protein kinase C (PKC) activity even prior to synapse formation; PKC activation caused a substantial increase in spontaneous GABA release from the growth cone, probably acting at the axon terminal. These data indicate that GABA is secreted from axons during a stage of neuronal development when GABA is excitatory, and that neuromodulators could alter GABA release from the growing axon, potentially enabling other developing neurons of different transmitter phenotype to modulate the early actions of GABA. PMID:10718743

  1. Molecular and pharmacological properties of GABA-rho subunits from white perch retina.

    PubMed

    Qian, H; Dowling, J E; Ripps, H

    1998-11-01

    Five gamma-aminobutyric acid (GABA)-rho subunits were cloned from a white perch retinal cDNA library and expressed in Xenopus oocytes. The deduced amino acid sequences indicated that all are highly homologous to the GABA-rho subunits cloned from mammalian retinas; two clones (perch-rho 1A and perch-rho 1B) were in the rho 1 family, two (perch-rho 2A and perch-rho 2B) were in the rho 2 family, and one clone has been tentatively identified as a perch-rho 3 subunit. When expressed in Xenopus oocytes, all but one of the subunits (rho 3) formed functional homooligomeric receptors. However, the receptors expressed by each of the GABA-rho subunits displayed unique response properties that distinguished one from the other. For example, receptors formed by perch-rho 1B subunits were more sensitive to GABA than the receptors formed by other GABA-rho subunits, the dose-response curves for the various receptors revealed different Hill coefficients, and there were differences in the kinetics of the GABA-induced currents. In addition, the GABA-mediated current-voltage curve for rho 2 receptors was approximately linear, whereas the responses from rho 1 receptors showed outward rectification. A further division in the properties of the GABA-rho subunits was revealed in their responses to imidazole-4-acetic acid (I4AA); the drug behaved as an antagonist on A-type rho receptors and a partial agonist on the B-type rho receptors. These results suggest that there is a large diversity of GABAC receptors in the vertebrate retina, probably formed by homooligomeric and heterooligomeric combinations of GABA rho subunits, that exhibit different functional properties. PMID:9805275

  2. Elevated levels of GABA+ in migraine detected using (1) H-MRS.

    PubMed

    Aguila, Maria-Eliza R; Lagopoulos, Jim; Leaver, Andrew M; Rebbeck, Trudy; Hübscher, Markus; Brennan, Patrick C; Refshauge, Kathryn M

    2015-07-01

    γ-Aminobutyric acid (GABA) has been implicated in several pain conditions, yet no study has systematically evaluated GABA levels in migraine using (1) H-MRS. The accurate detection, separation and quantification of GABA in individuals with migraine could elucidate the role of this neurotransmitter in migraine pathophysiology. Such information may eventually be useful in the diagnosis and development of more effective treatments for migraine. The aims of this study were therefore to compare the concentration of GABA+ in individuals with migraine with that in asymptomatic individuals, and to determine the diagnostic potential of GABA+ in the classification of those with or without migraine. In this case-control study, GABA+ levels in the brain were determined in 19 participants with migraine and 19 matched controls by (1) H-MRS using Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence. The diagnostic accuracy of GABA+ for the detection of migraine and the optimal cut-off value were determined by receiver operating characteristic analysis. GABA+ levels were significantly higher (p = 0.002) in those with migraine [median, 1.41 institutional units (IU); interquartile range, 1.31-1.50 IU] than in controls (median, 1.18 IU; interquartile range, 1.12-1.35 IU). The GABA+ concentration appears to have good accuracy for the classification of individuals with or without migraine [area under the curve (95% confidence interval), 0.837 (0.71-0.96); p < 0.001]. The optimal GABA+ cut-off value for migraine was 1.30 IU, with a sensitivity of 84.2%, specificity of 68.4% and positive likelihood ratio of +2.67. The outcomes of this study suggest altered GABA metabolism in migraine. These results add to the scarce evidence on the putative role of GABA in migraine and provide a basis to further explore the causal relationship between GABA+ and the pathophysiology of migraine. This study also demonstrates that GABA+ concentration has good diagnostic accuracy for migraine

  3. The Memory-Impairing Effects of Septal GABA Receptor Activation Involve GABAergic Septo-Hippocampal Projection Neurons

    ERIC Educational Resources Information Center

    Krebs-Kraft, Desiree L.; Wheeler, Marina G.; Parent, Marise B.

    2007-01-01

    Septal infusions of the [gamma]-aminobutyric acid (GABA)[subscript A] agonist muscimol impair memory, and the effect likely involves the hippocampus. GABA[subscript A] receptors are present on the perikarya of cholinergic and GABAergic septo-hippocampal (SH) projections. The current experiments determined whether GABAergic SH projections are…

  4. Focal Uncaging of GABA Reveals a Temporally Defined Role for GABAergic Inhibition during Appetitive Associative Olfactory Conditioning in Honeybees

    ERIC Educational Resources Information Center

    Raccuglia, Davide; Mueller, Uli

    2013-01-01

    Throughout the animal kingdom, the inhibitory neurotransmitter ?-aminobutyric acid (GABA) is a key modulator of physiological processes including learning. With respect to associative learning, the exact time in which GABA interferes with the molecular events of learning has not yet been clearly defined. To address this issue, we used two…

  5. GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies

    PubMed Central

    Chiapponi, Chiara; Piras, Federica; Piras, Fabrizio; Caltagirone, Carlo; Spalletta, Gianfranco

    2016-01-01

    Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional–biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA

  6. GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies.

    PubMed

    Chiapponi, Chiara; Piras, Federica; Piras, Fabrizio; Caltagirone, Carlo; Spalletta, Gianfranco

    2016-01-01

    Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional-biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA MRS

  7. CGP 36216 is a selective antagonist at GABA(B) presynaptic receptors in rat brain.

    PubMed

    Ong, J; Bexis, S; Marino, V; Parker, D A; Kerr, D I; Froestl, W

    2001-03-01

    In rat neocortical preparations maintained in Mg(2+)-free Krebs medium, baclofen depressed the frequency of spontaneous discharges in a concentration-dependent manner (EC(50) = 6 microM), sensitive to (3-aminopropyl)ethylphosphinic acid (CGP 36216) (100, 300 and 500 microM) (pA(2) = 3.9 +/- 0.1). By contrast, CGP 36216, up to 1 mM, was ineffective in antagonising baclofen-induced hyperpolarisations, mediated through gamma-aminobutyric acid(B) (GABA(B)) postsynaptic receptors. In electrically stimulated brain slices preloaded with [3H]GABA, CGP 36216 increased [3H]GABA release (IC(50) = 43 microM), which was reversed by baclofen (20 microM). While CGP 36216 is ineffective at GABA(B) postsynaptic receptors, it is appreciably more active at presynaptic receptors.

  8. GABA metabolism pathway genes, UGA1 and GAD1, regulate replicative lifespan in Saccharomyces cerevisiae.

    PubMed

    Kamei, Yuka; Tamura, Takayuki; Yoshida, Ryo; Ohta, Shinji; Fukusaki, Eiichiro; Mukai, Yukio

    2011-04-01

    Many of the genes involved in aging have been identified in organisms ranging from yeast to human. Our previous study showed that deletion of the UGA3 gene-which encodes a zinc-finger transcription factor necessary for γ-aminobutyric acid (GABA)-dependent induction of the UGA1 (GABA aminotransferase), UGA2 (succinate semialdehyde dehydrogenase), and UGA4 (GABA permease) genes-extends replicative lifespan in the budding yeast Saccharomyces cerevisiae. Here, we found that deletion of UGA1 lengthened the lifespan, as did deletion of UGA3; in contrast, strains with UGA2 or UGA4 deletions exhibited no lifespan extension. The Δuga1 strain cannot deaminate GABA to succinate semialdehyde. Deletion of GAD1, which encodes the glutamate decarboxylase that converts glutamate into GABA, also increased lifespan. Therefore, two genes in the GABA metabolism pathway, UGA1 and GAD1, were identified as aging genes. Unexpectedly, intracellular GABA levels in mutant cells (except for Δuga2 cells) did not differ from those in wild-type cells. Addition of GABA to culture media, which induces transcription of the UGA structural genes, had no effect on replicative lifespan of wild-type cells. Multivariate analysis of (1)H nuclear magnetic resonance spectra for the whole-cell metabolite levels demonstrated a separation between long-lived and normal-lived strains. Gas chromatography-mass spectrometry analysis of identified metabolites showed that levels of tricarboxylic acid cycle intermediates positively correlated with lifespan extension. These results strongly suggest reduced activity of the GABA-metabolizing enzymes extends lifespan by shifting carbon metabolism toward respiration, as calorie restriction does.

  9. Action of tremorgenic mycotoxins on GABA/sub A/ receptor

    SciTech Connect

    Gant, D.B.; Cole, R.J.; Valdes, J.J.; Eldefrawi, M.E.; Eldefrawi, A.T.

    1987-11-09

    The effects of four tremorgenic and one nontremorgenic mycotoxins were studied on ..gamma..-aminobutyric acid (GABA/sub A/) receptor binding and function in rat brain and on binding of a voltage-operated Cl/sup -/ channel in Torpedo electric organ. None of the mycotoxins had significant effect on (/sup 3/H)muscimol or (/sup 3/H)flunitrazepam binding to the GAMA/sup A/ receptor. However, only the four tremorgenic mycotoxins inhibited GABA-induced /sup 36/Cl/sup -/ influx and (/sup 35/S)t-butylbicyclophosphorothionate ((/sup 35/S)TBPS) binding in rate brain membranes, while the nontremorgenic verruculotoxin had no effect. Inhibition of (/sup 35/S)TBPS binding by paspalinine was non-competitive. This suggests that tremorgenic mycotoxins inhibit GABA/sub A/ receptor function by binding close to the receptor's Cl/sup -/ channel. On the voltage-operated Cl/sup -/ channel, only high concentrations of verruculogen and verruculotoxin caused significant inhibition of the channel's binding of (/sup 35/S)TBPS. The data suggest that the tremorgenic action of these mycotoxins may be due in part to their inhibition of GABA/sub A/ receptor function. 21 references, 4 figures, 2 tables.

  10. GABA metabolism pathway genes, UGA1 and GAD1, regulate replicative lifespan in Saccharomycescerevisiae

    SciTech Connect

    Kamei, Yuka; Tamura, Takayuki; Yoshida, Ryo; Ohta, Shinji; Fukusaki, Eiichiro; Mukai, Yukio

    2011-04-01

    Highlights: {yields}We demonstrate that two genes in the yeast GABA metabolism pathway affect aging. {yields} Deletion of the UGA1 or GAD1 genes extends replicative lifespan. {yields} Addition of GABA to wild-type cultures has no effect on lifespan. {yields} Intracellular GABA levels do not differ in longevity mutants and wild-type cells. {yields} Levels of tricarboxylic acid cycle intermediates positively correlate with lifespan. -- Abstract: Many of the genes involved in aging have been identified in organisms ranging from yeast to human. Our previous study showed that deletion of the UGA3 gene-which encodes a zinc-finger transcription factor necessary for {gamma}-aminobutyric acid (GABA)-dependent induction of the UGA1 (GABA aminotransferase), UGA2 (succinate semialdehyde dehydrogenase), and UGA4 (GABA permease) genes-extends replicative lifespan in the budding yeast Saccharomycescerevisiae. Here, we found that deletion of UGA1 lengthened the lifespan, as did deletion of UGA3; in contrast, strains with UGA2 or UGA4 deletions exhibited no lifespan extension. The {Delta}uga1 strain cannot deaminate GABA to succinate semialdehyde. Deletion of GAD1, which encodes the glutamate decarboxylase that converts glutamate into GABA, also increased lifespan. Therefore, two genes in the GABA metabolism pathway, UGA1 and GAD1, were identified as aging genes. Unexpectedly, intracellular GABA levels in mutant cells (except for {Delta}uga2 cells) did not differ from those in wild-type cells. Addition of GABA to culture media, which induces transcription of the UGA structural genes, had no effect on replicative lifespan of wild-type cells. Multivariate analysis of {sup 1}H nuclear magnetic resonance spectra for the whole-cell metabolite levels demonstrated a separation between long-lived and normal-lived strains. Gas chromatography-mass spectrometry analysis of identified metabolites showed that levels of tricarboxylic acid cycle intermediates positively correlated with lifespan

  11. Gad1 mRNA as a reliable indicator of altered GABA release from orexigenic neurons in the hypothalamus

    PubMed Central

    Dicken, Matthew S.; Hughes, Alexander R.; Hentges, Shane T.

    2016-01-01

    The strength of γ-aminobutyric acid (GABA)-mediated inhibitory synaptic input is a principle determinant of neuronal activity. However, because of differences in the number of GABA afferent inputs and the sites of synapses, it is difficult to directly assay for altered GABA transmission between specific cells. The present study tested the hypothesis that the level of mRNA for the GABA synthetic enzyme glutamate decarboxylase (GAD) can provide a reliable proxy for GABA release. This was tested in a mouse hypothalamic circuit important in the regulation of energy balance. Fluorescent in situ hybridization results show that the expression of Gad1 mRNA (encoding the GAD67 enzyme) was increased in hypothalamic neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons after an overnight fast, consistent with the ability of GABA from these neurons to stimulate food intake. Optogenetic studies confirmed that the observed increase in Gad1 mRNA correlated with an increase in the probability of GABA release from NPY/AgRP neurons onto downstream proopiomelanocortin neurons. Likewise, there was an increase in the readily releasable pool of GABA in NPY/AgRP neurons. Selective inhibition of GAD activity in NPY/AgRP neurons decreased GABA release, indicating that GAD67 activity, which is largely dictated by expression level, is a key determinant of GABA release. Altogether, it appears that Gad expression may be a reliable proxy of altered GABAergic transmission. Examining changes in Gad mRNA as a proxy for GABA release may be particularly helpful when the downstream targets are not known or when limited tools exist for detecting GABA release at a particular synapse. PMID:26370162

  12. Release of GABA from sensory neurons transduced with a GAD67-expressing vector occurs by non-vesicular mechanisms.

    PubMed

    Liu, Jun; Tai, Changfeng; de Groat, William C; Peng, Xiang-min; Mata, Marina; Fink, David J

    2006-02-16

    We have demonstrated that dorsal root ganglion neurons transduced with a recombinant replication-defective herpes simplex virus vector coding for glutamic acid decarboxylase (QHGAD67) release GABA to produce an analgesic effect in rodent models of pain. In this study, we examined the mechanism of transgene-mediated GABA release from dorsal root ganglion neurons in vitro and in vivo. Release of GABA from dorsal root ganglion neurons transduced with QHGAD67 was not increased by membrane depolarization induced by 60 mM extracellular K+ nor reduced by the removal of Ca2+ from the medium. Release of GABA from transduced dorsal root ganglion neurons was, however, blocked in a dose-dependent manner by NO-711, a selective inhibitor of the GABA transporter-1. The amount of GABA released from a spinal cord slice preparation, prepared from animals transduced by subcutaneous inoculation of QHGAD67 in the hind paws, was substantially increased compared to animals transduced with control vector Q0ZHG or normal animals, but the amount of GABA released was not changed by stimulation of the dorsal roots at either low (0.1 mA, 0.5-ms duration) or high (10 mA, 0.5-ms duration) intensity. We conclude that QHGAD67-mediated GABA release from dorsal root ganglion neurons is non-vesicular, independent of electrical depolarization, and that this efflux is mediated through reversal of the GABA transporter.

  13. Regulation of (/sup 3/H)GABA release from strips of guinea pig urinary bladder

    SciTech Connect

    Shirakawa, J.; Taniyama, K.; Iwai, S.; Tanaka, C.

    1988-12-01

    The presence of receptors that regulate the release of gamma-aminobutyric acid (GABA) was studied in strips of the guinea pig urinary bladder. GABA (10(-8)-10(-5) M) and muscimol (10(-8)-10(-5) M), but not baclofen (10(-5) M), reduced the Ca2+-dependent, tetrodotoxin-resistant release of (/sup 3/H)GABA evoked by high K+ from the urinary bladder strips preloaded with (/sup 3/H)GABA. The inhibitory effect of muscimol was antagonized by bicuculline and potentiated by diazepam, clonazepam, and pentobarbital sodium. The potentiating effect of clonazepam was antagonized by Ro 15-1788. Acetylcholine (ACh) inhibited the high K+-evoked release of (/sup 3/H)GABA. The inhibitory effect of ACh was antagonized by atropine sulfate and pirenzepine but not by hexamethonium. Norepinephrine (NE) inhibited the evoked release of (/sup 3/H)GABA. The inhibitory effect of NE was mimicked by clonidine, but not by phenylephrine, and was antagonized by yohimbine but not by prazosin. These results provide evidence that the release of GABA from strips of guinea pig urinary bladder is regulated via the bicuculline-sensitive GABAA receptor, M1-muscarinic, and alpha 2-adrenergic receptors.

  14. Imbalance between Glutamate and GABA in Fmr1 Knockout Astrocytes Influences Neuronal Development

    PubMed Central

    Wang, Lu; Wang, Yan; Zhou, Shimeng; Yang, Liukun; Shi, Qixin; Li, Yujiao; Zhang, Kun; Yang, Le; Zhao, Minggao; Yang, Qi

    2016-01-01

    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. PMID:27517961

  15. New Pharmacotherapy Targeting Cognitive Dysfunction of Schizophrenia via Modulation of GABA Neuronal Function

    PubMed Central

    Jeon, Won Je; Sumiyoshi, Tomiki; Kurachi, Masayoshi

    2015-01-01

    Schizophrenia is considered a neurodevelopmental and neurodegenerative disorder. Cognitive impairment is a core symptom in patients with the illness, and has been suggested a major predictor of functional outcomes. Reduction of parvalbumin (PV)-positive γ-aminobutyric acid (GABA) interneurons has been associated with the pathophysiology of schizophrenia, in view of the link between the abnormality of GABA neurons and cognitive impairments of the disease. It is assumed that an imbalance of excitatory and inhibitory (E-I) activity induced by low activity of glutamatergic projections and PV-positive GABA interneurons in the prefrontal cortex resulted in sustained neural firing and gamma oscillation, leading to impaired cognitive function. Therefore, it is important to develop novel pharmacotherapy targeting GABA neurons and their activities. Clinical evidence suggests serotonin (5-HT) 1A receptor agonist improves cognitive disturbances of schizophrenia, consistent with results from preclinical studies, through mechanism that corrects E-I imbalance via the suppression of GABA neural function. On the other hand, T-817MA, a novel neurotrophic agent, ameliorated loss of PV-positive GABA neurons in the medial prefrontal cortex and reduction of gamma-band activity, as well as cognitive dysfunction in animal model of schizophrenia. In conclusion, a pharmacotherapy to alleviate abnormalities in GABA neurons through 5-HT1A agonists and T-817MA is expected to prevent the onset and/or progression of schizophrenia. PMID:26630957

  16. Differential effects of GABA in modulating nociceptive vs. non-nociceptive synapses.

    PubMed

    Wang, Y; Summers, T; Peterson, W; Miiller, E; Burrell, B D

    2015-07-01

    GABA (γ-amino-butyric acid) -mediated signaling is normally associated with synaptic inhibition due to ionotropic GABA receptors that gate an inward Cl(-) current, hyperpolarizing the membrane potential. However, there are also situations where ionotropic GABA receptors trigger a Cl(-) efflux that results in depolarization. The well-characterized central nervous system of the medicinal leech was used to study the functional significance of opposing effects of GABA at the synaptic circuit level. Specifically, we focused on synapses made by the nociceptive N cell and the non-nociceptive P (pressure) cell that converge onto a common postsynaptic target. It is already known that GABA hyperpolarizes the P cell, but depolarizes the N cell and that inhibition of ionotropic GABA receptors by bicuculline (BIC) has opposing effects on the synapses made by these two inputs; enhancing P cell synaptic transmission, but depressing N cell synapses. The goal of the present study was to determine whether the opposing effects of GABA were due to differences in Cl(-) homeostasis between the two presynaptic neurons. VU 0240551 (VU), an inhibitor of the Cl(-) exporter K-Cl co-transporter isoform 2 (KCC2), attenuated GABA-mediated hyperpolarization of the non-nociceptive afferent while bumetanide (BUM), an inhibitor of the Cl(-) importer Na-K-Cl co-transporter isoform 1 (NKCC1), reduced GABA-mediated depolarization of the nociceptive neuron. VU treatment also enhanced P cell synaptic signaling, similar to the previously observed effects of BIC and consistent with the idea that GABA inhibits synaptic signaling at the presynaptic level. BUM treatment depressed N cell synapses, again similar to what is observed following BIC treatment and suggests that GABA has an excitatory effect on these synapses. The opposing effects of GABA could also be observed at the behavioral level with BIC and VU increasing responsiveness to non-nociceptive stimulation while BIC and BUM decreased responsiveness

  17. Anion transport and GABA signaling

    PubMed Central

    Hübner, Christian A.; Holthoff, Knut

    2013-01-01

    Whereas activation of GABAA receptors by GABA usually results in a hyperpolarizing influx of chloride into the neuron, the reversed chloride driving force in the immature nervous system results in a depolarizing efflux of chloride. This GABAergic depolarization is deemed to be important for the maturation of the neuronal network. The concept of a developmental GABA switch has mainly been derived from in vitro experiments and reliable in vivo evidence is still missing. As GABAA receptors are permeable for both chloride and bicarbonate, the net effect of GABA also critically depends on the distribution of bicarbonate. Whereas chloride can either mediate depolarizing or hyperpolarizing currents, bicarbonate invariably mediates a depolarizing current under physiological conditions. Intracellular bicarbonate is quickly replenished by cytosolic carbonic anhydrases. Intracellular bicarbonate levels also depend on different bicarbonate transporters expressed by neurons. The expression of these proteins is not only developmentally regulated but also differs between cell types and even subcellular regions. In this review we will summarize current knowledge about the role of some of these transporters for brain development and brain function. PMID:24187533

  18. Electrospray ionization tandem mass spectrometric study on the effect of N-terminal beta- and gamma-carbo amino acids on fragmentation of GABA-hybrid peptides.

    PubMed

    Ramesh, V; Ramesh, M; Srinivas, R; Sharma, G V M; Jayaprakash, P

    2008-11-01

    The fragmentations of protonated and deprotonated ions of a new class of N-blocked hybrid Boc-carbopeptides containing repeats of gamma-Caa/gammaAbu- and beta-Caa/gammaAbu- (Caa==C-linked carbo gamma(4)-/beta(3)- amino acids derived from D-xylose, gammaAbu = gamma-aminobutyric acid) have been studied using electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MS/MS of a pair of these protonated diastereomers produces distinct fragmentation of the Boc group. The formation of [M + H-56](+) corresponding to loss of isobutylene is more pronounced for Boc-NH-(R)-gamma-Caa-gammaAbu-OH (2) whereas it is of low abundance for Boc-NH-(S)-gamma-Caa-gammaAbu--OH (1). Similarly, MS(2) of [M--H](-) of 2 produces an abundant [M--H--C(CH(3))(3)OH--CO(2)](-) ion, which is absent for its diastereomeric isomer 1. From this, it can be suggested that MS/MS of N-blocked Boc-protected carbopeptides may be helpful in distinguishing the stereochemistry of the N-terminus Caa. MS(3) of [M + H-Boc + H](+) ions of peptides with a gamma-amino acid (gamma-Caa/gammaAbu) at the N-terminus produces only abundant y(n) (+) ions. On the other hand, characteristic fragmentations involving the peptide backbone (b(n) (+) and y(n) (+)) and the side chain are seen when beta-Caa is at the N-terminus of the peptides. MS(3) of the [M--H--C(CH(3))(3)OH](-) ion of peptides containing gamma-Caa/gammaAbu at the N-terminus gave y(n) (-) and [M--H--C(CH(3))(3)OH--CO(2)](-) ions, whereas the presence of beta-Caa at the N-terminus yielded predominantly [M--H--C(CH(3))(3)OH--HNCO](-). Thus, on the basis of our previous study and that presented here we propose that the fragmentation of these hybrid carbopeptides is highly influenced by the type of carbo amino acid present at the N-terminus. PMID:18837002

  19. Correlation between the enhancement of flunitrazepam binding by GABA and seizure susceptibility in mice

    SciTech Connect

    Marley, R.J.; Wehner, J.M.

    1987-06-08

    Various populations of mice exhibit differential sensitivity to seizure-inducing agents. The relationship of seizure susceptibility to alterations in the GABA receptor complex was investigated in six different populations of mice consisting of four inbred strains (C57BL, DBA, C3H, and BALB) and two selected lines (long sleep and short sleep). Seizure activity was induced by intraperitoneal administration of the GAD inhibitor, 3-mercaptopropionic acid, and latencies to seizure onset and tonus were measured. In naive mice of the same populations, GABA enhancement of TH-flunitrazepam binding was measured in extensively washed whole brain membranes at several GABA concentrations. Both differential seizure sensitivity to 3-mercaptopropionic acid and differential enhancement of TH-flunitrazepam binding by GABA were observed in these six populations of mice. Correlational analyses indicated a positive correlation between the degree of GABA enhancement of TH-flunitrazepam binding and resistance to the seizure-inducing properties of 3-mercaptopropionic acid. These data suggest that genetic differences in sensitivity to seizure-inducing agents that disrupt the GABAergic system may be related to differences in coupling between the various receptors associated with the GABA receptor complex.

  20. Comparison of taurine, GABA, Glu, and Asp as scavengers of malondialdehyde in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Deng, Yan; Wang, Wei; Yu, Pingfeng; Xi, Zhijiang; Xu, Lijian; Li, Xiaolong; He, Nongyue

    2013-04-01

    The purpose of this study is to determine if amino acid neurotransmitters such as gamma-aminobutyric acid (GABA), taurine, glutamate (Glu), and aspartate (Asp) can scavenge activated carbonyl toxicants. In vitro, direct reaction between malondialdehyde (MDA) and amino acids was researched using different analytical methods. The results indicated that scavenging activated carbonyl function of taurine and GABA is very strong and that of Glu and Asp is very weak in pathophysiological situations. The results provided perspective into the reaction mechanism of taurine and GABA as targets of activated carbonyl such as MDA in protecting nerve terminals. In vivo, we studied the effect of taurine and GABA as antioxidants by detecting MDA concentration and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. It was shown that MDA concentration was decreased significantly, and the activities of SOD and GSH-Px were increased significantly in the cerebral cortex and hippocampus of acute epileptic state rats, after the administration of taurine and GABA. The results indicated that the peripherally administered taurine and GABA can scavenge free radicals and protect the tissue against activated carbonyl in vivo and in vitro.

  1. Sleep-promoting effects of the GABA/5-HTP mixture in vertebrate models.

    PubMed

    Hong, Ki-Bae; Park, Yooheon; Suh, Hyung Joo

    2016-09-01

    The aim of this study was to investigate the sleep-promoting effect of combined γ-aminobutyric acid (GABA) and 5-hydroxytryptophan (5-HTP) on sleep quality and quantity in vertebrate models. Pentobarbital-induced sleep test and electroencephalogram (EEG) analysis were applied to investigate sleep latency, duration, total sleeping time and sleep quality of two amino acids and GABA/5-HTP mixture. In addition, real-time PCR and HPLC analysis were applied to analyze the signaling pathway. The GABA/5-HTP mixture significantly regulated the sleep latency, duration (p<0.005), and also increased the sleep quality than single administration of the amino acids (p<0.000). Long-term administration increased the transcript levels of GABAA receptor (1.37-fold, p<0.000) and also increased the GABA content compared with the control group 12h after administration (1.43-fold, p<0.000). Our available evidence suggests that the GABA/5-HTP mixture modulates both GABAergic and serotonergic signaling. Moreover, the sleep architecture can be controlled by the regulation of GABAA receptor and GABA content with 5-HTP. PMID:27150227

  2. High-resolution autoreactive epitope mapping and structural modeling of the 65 kDa form of human glutamic acid decarboxylase.

    PubMed

    Schwartz, H L; Chandonia, J M; Kash, S F; Kanaani, J; Tunnell, E; Domingo, A; Cohen, F E; Banga, J P; Madec, A M; Richter, W; Baekkeskov, S

    1999-04-16

    The smaller isoform of the GABA-synthesizing enzyme, glutamic acid decarboxylase 65 (GAD65), is unusually susceptible to becoming a target of autoimmunity affecting its major sites of expression, GABA-ergic neurons and pancreatic beta-cells. In contrast, a highly homologous isoform, GAD67, is not an autoantigen. We used homolog-scanning mutagenesis to identify GAD65-specific amino acid residues which form autoreactive B-cell epitopes in this molecule. Detailed mapping of 13 conformational epitopes, recognized by human monoclonal antibodies derived from patients, together with two and three-dimensional structure prediction led to a model of the GAD65 dimer. GAD65 has structural similarities to ornithine decarboxylase in the pyridoxal-5'-phosphate-binding middle domain (residues 201-460) and to dialkylglycine decarboxylase in the C-terminal domain (residues 461-585). Six distinct conformational and one linear epitopes cluster on the hydrophilic face of three amphipathic alpha-helices in exons 14-16 in the C-terminal domain. Two of those epitopes also require amino acids in exon 4 in the N-terminal domain. Two distinct epitopes reside entirely in the N-terminal domain. In the middle domain, four distinct conformational epitopes cluster on a charged patch formed by amino acids from three alpha-helices away from the active site, and a fifth epitope resides at the back of the pyridoxal 5'-phosphate binding site and involves amino acid residues in exons 6 and 11-12. The epitopes localize to multiple hydrophilic patches, several of which also harbor DR*0401-restricted T-cell epitopes, and cover most of the surface of the protein. The results reveal a remarkable spectrum of human autoreactivity to GAD65, targeting almost the entire surface, and suggest that native folded GAD65 is the immunogen for autoreactive B-cells. PMID:10222205

  3. The transporter GAT1 plays an important role in GABA-mediated carbon-nitrogen interactions in Arabidopsis

    PubMed Central

    Batushansky, Albert; Kirma, Menny; Grillich, Nicole; Pham, Phuong A.; Rentsch, Doris; Galili, Gad; Fernie, Alisdair R.; Fait, Aaron

    2015-01-01

    Glutamate derived γ-aminobutyric acid (GABA) is synthetized in the cytosol prior to delivery to the mitochondria where it is catabolized via the TCA cycle. GABA accumulates under various environmental conditions, but an increasing number of studies show its involvement at the crossroad between C and N metabolism. To assess the role of GABA in modulating cellular metabolism, we exposed seedlings of A. thaliana GABA transporter gat1 mutant to full nutrition medium and media deficient in C and N combined with feeding of different concentrations (0.5 and 1 mM) of exogenous GABA. GC-MS based metabolite profiling showed an expected effect of medium composition on the seedlings metabolism of mutant and wild type alike. That being said, a significant interaction between GAT1 deficiency and medium composition was determined with respect to magnitude of change in relative amino acid levels. The effect of exogenous GABA treatment on metabolism was contingent on both the medium and the genotype, leading for instance to a drop in asparagine under full nutrition and low C conditions and glucose under all tested media, but not to changes in GABA content. We additionally assessed the effect of GAT1 deficiency on the expression of glutamate metabolism related genes and genes involved in abiotic stress responses. These results suggest a role for GAT1 in GABA-mediated metabolic alterations in the context of the C-N equilibrium of plant cells. PMID:26483804

  4. Interrelation of resting state functional connectivity, striatal GABA levels, and cognitive control processes.

    PubMed

    Haag, Lauren; Quetscher, Clara; Dharmadhikari, Shalmali; Dydak, Ulrike; Schmidt-Wilcke, Tobias; Beste, Christian

    2015-11-01

    Important issues for cognitive control are response selection processes, known to depend on fronto-striatal networks with recent evidence suggesting that striatal gamma-amino butyric acid (GABA) levels play an important role. Regional GABA concentrations have also been shown to modulate intrinsic connectivity, e.g. of the default mode network. However, the interrelation between striatal GABA levels, basal ganglia network (BGN) connectivity, and performance in cognitive control is elusive. In the current study, we measure striatal GABA levels using magnetic resonance spectroscopy (MRS) and resting state parameters using functional magnetic resonance imaging (fMRI). Resting state parameters include activity within the BGN, as determined by the low frequency power (LFP) within the network, and the functional connectivity between the BGN and somatomotor network (SMN). Specifically, we examine the interrelation between GABA, resting state parameters, and performance (i.e., accuracy) in conflict monitoring using a Simon task. Response control was affected by striatal GABA+ levels and activity within the BGN, especially when response selection was complicated by altered stimulus-response mappings. The data suggest that there are two mechanisms supporting response selection accuracy. One is related to resting state activity within the BGN and modulated by striatal GABA+ levels. The other is related to decreased cortico-striatal network connectivity, unrelated to the GABAergic system. The inclusion of all three factors (i.e., striatal GABA+ levels, activity within the BGN, and BGN-SMN network connectivity) explained a considerable amount of variance in task accuracy. Striatal neurobiochemical (GABA+) and parameters of the resting state BGN represent important modulators of response control. PMID:26354091

  5. Aging of whiskey increases the potentiation of GABA(A) receptor response.

    PubMed

    Koda, Hirofumi; Hossain, Sheikh Julfikar; Kiso, Yoshinobu; Aoshima, Hitoshi

    2003-08-27

    It is known that the target of most mood-defining compounds such as ethanol is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activities in the human brain. Because both extracts of whiskey by pentane and fragrant components in whiskey potentiate the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting cRNAs prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors in order to study the effects of whiskey itself on the GABA(A) receptor-mediated response. Whiskey itself also potentiated the electrical responses of GABA(A) receptors generally more than ethanol at the same concentration as that of the whiskey. The potentiation of the GABA(A) receptor-mediated response increased with the aging period of the whiskey. Inhalation of whiskey to mice increased the sleeping time induced by pentobarbital more than that of the same concentration of ethanol as the whiskey. These results suggest that not only ethanol but also minor components in whiskey play an important role in the potentiation of GABA(A) receptor-mediated response and possibly the sedative effect of whiskey. Although the minor components are present in extremely small quantities compared with ethanol in alcoholic beverages, they may modulate the mood or consciousness of humans through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic compounds are easily absorbed into the brain across the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response.

  6. Microtransplantation of cellular membranes from squid stellate ganglion reveals ionotropic GABA receptors.

    PubMed

    Conti, Luca; Limon, Agenor; Palma, Eleonora; Miledi, Ricardo

    2013-02-01

    The squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. While the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. In this study we investigated whether γ-aminobutyric acid (GABA) activates neurotransmitter receptors in stellate ganglia membranes. To overcome the low abundance of GABA-like mRNAs in invertebrates and the low expression of GABA in cephalopods, we used a two-electrode voltage clamp technique to determine if Xenopus laevis oocytes injected with cell membranes from squid stellate ganglia responded to GABA. Using this method, membrane patches containing proteins and ion channels from the squid's stellate ganglion were incorporated into the surface of oocytes. We demonstrated that GABA activates membrane receptors in cellular membranes isolated from squid stellate ganglia. Using the same approach, we were able to record native glutamate-evoked currents. The squid's GABA receptors showed an EC(50) of 98 μmol l(-1) to GABA and were inhibited by zinc (IC(50) = 356 μmol l(-1)). Interestingly, GABA receptors from the squid were only partially blocked by bicuculline. These results indicate that the microtransplantation of native cell membranes is useful to identify and characterize scarce membrane proteins. Moreover, our data also support the role of GABA as an ionotropic neurotransmitter in cephalopods, acting through chloride-permeable membrane receptors.

  7. Interaction between cyclodextrin and neuronal membrane results in modulation of GABA(A) receptor conformational transitions.

    PubMed

    Pytel, Maria; Mercik, Katarzyna; Mozrzymas, Jerzy W

    2006-06-01

    Cyclodextrins (CDs) are nanostructures widely applied in biotechnology and chemistry. Owing to partially hydrophobic character, CDs interact with biological membranes. While the mechanisms of CDs interactions with lipids were widely studied, their effects on proteins are less understood. In the present study we investigated the effects of beta cyclodextrin (betaCD) on GABA(A) receptor (GABA(A)R) gating. To reliably resolve the kinetics of conformational transitions, currents were elicited by ultrafast gamma-aminobutyric acid (GABA) applications to outside-out patches from rat cultured hippocampal neurons. betaCD increased the amplitude of responses to saturating GABA concentration ([GABA]) in a dose-dependent manner and this effect was accompanied by profound alterations in the current kinetics. Current deactivation was slowed down by betaCD but this effect was biphasic with a maximum at around 0.5 mM betaCD. While the fast deactivation time constant was monotonically slowed down within considered betaCD concentration range, the slow component first increased and then, at millimolar betaCD concentration, decreased. The rate and extent of desensitization was decreased by betaCD in a dose-dependent manner. The analysis of current responses to nonsaturating [GABA] indicated that betaCD affected the GABA(A)R agonist binding site by slowing down the unbinding rate. Modulation of GABA(A)R desensitization and binding showed different concentration-dependence suggesting different modualtory sites with higher affinity of the latter one. All the betaCD effects were fully reversible indicating that cholesterol uptake into betaCD was not the primary mechanism. We conclude that betaCD is a strong modulator of GABA(A)R conformational transitions.

  8. Aging of whiskey increases the potentiation of GABA(A) receptor response.

    PubMed

    Koda, Hirofumi; Hossain, Sheikh Julfikar; Kiso, Yoshinobu; Aoshima, Hitoshi

    2003-08-27

    It is known that the target of most mood-defining compounds such as ethanol is an ionotropic gamma-aminobutyric acid receptor (GABA(A) receptor). The potentiation of the response of these inhibitory neurotransmitter receptors induces anxiolytic, sedative, and anesthetic activities in the human brain. Because both extracts of whiskey by pentane and fragrant components in whiskey potentiate the GABA(A) receptor-mediated response, GABA(A) receptors were expressed in Xenopus oocyte by injecting cRNAs prepared from the cloned cDNA for the alpha(1) and beta(1) subunits of the bovine receptors in order to study the effects of whiskey itself on the GABA(A) receptor-mediated response. Whiskey itself also potentiated the electrical responses of GABA(A) receptors generally more than ethanol at the same concentration as that of the whiskey. The potentiation of the GABA(A) receptor-mediated response increased with the aging period of the whiskey. Inhalation of whiskey to mice increased the sleeping time induced by pentobarbital more than that of the same concentration of ethanol as the whiskey. These results suggest that not only ethanol but also minor components in whiskey play an important role in the potentiation of GABA(A) receptor-mediated response and possibly the sedative effect of whiskey. Although the minor components are present in extremely small quantities compared with ethanol in alcoholic beverages, they may modulate the mood or consciousness of humans through the potentiation of the GABA(A) receptor response after absorption into the brain, because these hydrophobic compounds are easily absorbed into the brain across the blood-brain barrier and are several thousands times as potent as ethanol in the potentiation of the GABA(A) receptor-mediated response. PMID:12926865

  9. Increased GABA Levels in Medial Prefrontal Cortex of Young Adults with Narcolepsy

    PubMed Central

    Kim, Seog Ju; Lyoo, In Kyoon; Lee, Yujin S.; Sung, Young Hoon; Kim, Hengjun J.; Kim, Jihyun H.; Kim, Kye Hyun; Jeong, Do-Un

    2008-01-01

    Study Objectives: To explore absolute concentrations of brain metabolites including gamma amino-butyric acid (GABA) in the medial prefrontal cortex and basal ganglia of young adults with narcolepsy. Design: Proton magnetic resonance (MR) spectroscopy centered on the medial prefrontal cortex and the basal ganglia was acquired. The absolute concentrations of brain metabolites including GABA and glutamate were assessed and compared between narcoleptic patients and healthy comparison subjects. Setting: Sleep and Chronobiology Center at Seoul National University Hospital; A high strength 3.0 Tesla MR scanner in the Department of Radiology at Seoul National University Hospital. Patients or Participants: Seventeen young adults with a sole diagnosis of HLA DQB1 0602 positive narcolepsy with cataplexy (25.1 ± 4.6 years old) and 17 healthy comparison subjects (26.8 ± 4.8 years old). Interventions: N/A. Measurements and Results: Relative to comparison subjects, narcoleptic patients had higher GABA concentration in the medial prefrontal cortex (t = 4.10, P <0.001). Narcoleptic patients with nocturnal sleep disturbance had higher GABA concentration in the medial prefrontal cortex than those without nocturnal sleep disturbance (t = 2.45, P= 0.03), but had lower GABA concentration than comparison subjects (t = 2.30, P = 0.03). Conclusions: The current study reports that young adults with narcolepsy had a higher GABA concentration in the medial prefrontal cortex, which was more prominent in patients without nocturnal sleep disturbance. Our findings suggest that the medial prefrontal GABA level may be increased in narcolepsy, and the increased medial prefrontal GABA might be a compensatory mechanism to reduce nocturnal sleep disturbances in narcolepsy. Citation: Kim SJ; Lyoo IK; Lee YS; Sung YH; Kim HJ; Kim JH; Kim KH; Jeong DU. Increased GABA levels in medial prefrontal cortex of young adults with narcolepsy. SLEEP 2008;31(3):342-347. PMID:18363310

  10. GABA and GAD expression in the X-organ sinus gland system of the Procambarus clarkii crayfish: inhibition mediated by GABA between X-organ neurons.

    PubMed

    Pérez-Polanco, Paola; Garduño, Julieta; Cebada, Jorge; Zarco, Natanael; Segovia, José; Lamas, Mónica; García, Ubaldo

    2011-09-01

    In crustaceans, the X-organ-sinus gland (XO-SG) neurosecretory system is formed of distinct populations of neurons that produce two families of neuropeptides: crustacean hyperglycemic hormone and adipokinetic hormone/red pigment-concentrating hormone. On the basis of electrophysiological evidence, it has been proposed that γ-aminobutyric acid (GABA) regulates both electrical and secretory activity of the XO-SG system. In this work we observed that depolarizing current pulses to neurons located in the external rim of the X-organ induced repetitive firing that suppressed the spontaneous firing of previously active X-organ neurons. Picrotoxin reversibly blocked this inhibitory effect suggesting that the GABA released from the stimulated neuron inhibited neighboring cells. Immunoperoxidase in X-organ serial sections showed co-localization of GABA and glutamic acid decarboxylase (GAD) including the aforementioned neurons. Immunofluorescence in whole mount preparations showed that two subpopulations of crustacean hyperglycemic hormone-containing neurons colocalized with GABA. The expression of GAD mRNA was determined in crayfish tissue and X-organ single cells by RT-PCR. Bioinformatics analysis shows, within the amplified region, 90.4% consensus and 41.9% identity at the amino acid level compared with Drosophila melanogaster and Caenorhabditis elegans. We suggest that crustacean hyperglycemic hormone-GABA-containing neurons can regulate the excitability of other X-organ neurons that produce different neurohormones. PMID:21626307

  11. Depolarizing effect of GABA in horizontal cells of the rabbit retina.

    PubMed

    Varela, Carolina; Rivera, Luis; Blanco, Román; De la Villa, Pedro

    2005-11-01

    Gamma-amino butyric acid (GABA) has been characterized as an inhibitory neurotransmitter acting through chloride mediated channels in the adult nervous system. Using gramicidin-perforated patch clamp recordings from horizontal cells dissociated from the retinas of adult rabbits, we found that GABA is able to induce cell depolarization. Ionic currents induced by GABA in dissociated horizontal cells showed a reversal potential close to -30 mV. This value is more positive than the resting potential of these cells (ca. -70 mV). Therefore, according to the Nernst equation, the intracellular chloride concentration in horizontal cells was estimated to be of 44 mM. The depolarizing effect of GABA at the dendrites of horizontal cells may serve to shape the center-surround organization of the receptive fields in retinal cells, thereby securing the shape discrimination of visual input.

  12. The Arabidopsis pop2-1 mutant reveals the involvement of GABA transaminase in salt stress tolerance

    PubMed Central

    2010-01-01

    Background GABA (γ-aminobutyric acid) is a non protein amino acid that has been reported to accumulate in a number of plant species when subjected to high salinity and many other environmental constraints. However, no experimental data are to date available on the molecular function of GABA and the involvement of its metabolism in salt stress tolerance in higher plants. Here, we investigated the regulation of GABA metabolism in Arabidopsis thaliana at the metabolite, enzymatic activity and gene transcription levels upon NaCl stress. Results We identified the GABA transaminase (GABA-T), the first step of GABA catabolism, as the most responsive to NaCl. We further performed a functional analysis of the corresponding gene POP2 and demonstrated that the previously isolated loss-of-function pop2-1 mutant was oversensitive to ionic stress but not to osmotic stress suggesting a specific role in salt tolerance. NaCl oversensitivity was not associated with overaccumulation of Na+ and Cl- but mutant showed a slight decrease in K+. To bring insights into POP2 function, a promoter-reporter gene strategy was used and showed that POP2 was mainly expressed in roots under control conditions and was induced in primary root apex and aerial parts of plants in response to NaCl. Additionally, GC-MS- and UPLC-based metabolite profiling revealed major changes in roots of pop2-1 mutant upon NaCl stress including accumulation of amino acids and decrease in carbohydrates content. Conclusions GABA metabolism was overall up-regulated in response to NaCl in Arabidopsis. Particularly, GABA-T was found to play a pivotal function and impairment of this step was responsible for a decrease in salt tolerance indicating that GABA catabolism was a determinant of Arabidopsis salt tolerance. GABA-T would act in salt responses in linking N and C metabolisms in roots. PMID:20122158

  13. The Arabidopsis her1 mutant implicates GABA in E-2-hexenal responsiveness.

    PubMed

    Mirabella, Rossana; Rauwerda, Han; Struys, Eduard A; Jakobs, Cornelis; Triantaphylidès, Christian; Haring, Michel A; Schuurink, Robert C

    2008-01-01

    When wounded or attacked by herbivores or pathogens, plants produce a blend of six-carbon alcohols, aldehydes and esters, known as C6-volatiles. Undamaged plants, when exposed to C6-volatiles, respond by inducing defense-related genes and secondary metabolites, suggesting that C6-volatiles can act as signaling molecules regulating plant defense responses. However, to date, the molecular mechanisms by which plants perceive and respond to these volatiles are unknown. To elucidate such mechanisms, we decided to isolate Arabidopsis thaliana mutants in which responses to C6-volatiles were altered. We observed that treatment of Arabidopsis seedlings with the C6-volatile E-2-hexenal inhibits root elongation. Among C6-volatiles this response is specific to E-2-hexenal, and is not dependent on ethylene, jasmonic and salicylic acid. Using this bioassay, we isolated 18 E-2-hexenal-response (her) mutants that showed sustained root growth after E-2-hexenal treatment. Here, we focused on the molecular characterization of one of these mutants, her1. Microarray and map-based cloning revealed that her1 encodes a gamma-amino butyric acid transaminase (GABA-TP), an enzyme that degrades GABA. As a consequence of the mutation, her1 plants accumulate high GABA levels in all their organs. Based on the observation that E-2-hexenal treatment induces GABA accumulation, and that high GABA levels confer resistance to E-2-hexenal, we propose a role for GABA in mediating E-2-hexenal responses.

  14. Gating allosterism at a single class of etomidate sites on alpha1beta2gamma2L GABA A receptors accounts for both direct activation and agonist modulation.

    PubMed

    Rüsch, Dirk; Zhong, Huijun; Forman, Stuart A

    2004-05-14

    At clinical concentrations, the potent intravenous general anesthetic etomidate enhances gamma-aminobutyric acid, type A (GABA(A)) receptor activity elicited with low gamma-aminobutyric acid (GABA) concentrations, whereas much higher etomidate concentrations activate receptors in the absence of GABA. Therefore, GABA(A) receptors may possess two types of etomidate sites: high affinity GABA-modulating sites and low affinity channel-activating sites. However, GABA modulation and direct activation share stereoselectivity for the (R)(+)-etomidate isomer and display parallel dependence on GABA(A) beta subunit isoforms, suggesting that these two actions may be mediated by a single class of etomidate site(s) that exert one or more molecular effects. In this study, we assessed GABA modulation by etomidate using leftward shifts of electrophysiological GABA concentration responses in cells expressing human alpha1beta2gamma2L receptors. Etomidate at up to 100 microm reduced GABA EC(50) values by over 100-fold but without apparent saturation, indicating the absence of high affinity etomidate sites. In experiments using a partial agonist, P4S, etomidate both reduced EC(50) and increased maximal efficacy, demonstrating that etomidate shifts the GABA(A) receptor gating equilibrium toward open states. Results were quantitatively analyzed using equilibrium receptor gating models, wherein a postulated class of equivalent etomidate sites both directly activates receptors and enhances agonist gating. A Monod-Wyman-Changeux co-agonist mechanism with two equivalent etomidate sites that allosterically enhance GABA(A) receptor gating independently of agonist binding most simply accounts for direct activation and agonist modulation. This model also correctly predicts the actions of etomidate on GABA(A) receptors containing a point mutation that increases constitutive gating activity.

  15. Prefrontal Cortical GABA Abnormalities Are Associated With Reduced Hippocampal Volume In Major Depressive Disorder

    PubMed Central

    Abdallah, Chadi G.; Jackowski, Andrea; Sato, João R.; Mao, Xiangling; Kang, Guoxin; Cheema, Raminder; Coplan, Jeremy D.; Mathew, Sanjay J.; Shungu, Dikoma C.

    2015-01-01

    Hippocampal volume reduction has been related to treatment-resistant depression (TRD) and is hypothesized to reflect impaired amino-acid neurotransmission. To better understand the role of amino acid neurotransmission in hippocampal volume deficits, and subsequent resistance to treatment, this study investigated the relationship between hippocampal volumes and GABA levels in the anterior cingulate cortex (ACC), previously associated with TRD. Thirty-three medication-free major depressive disorder (MDD; 14 TRD and 19 non-TRD) and 26 healthy controls (HC) subjects were studied. Participants underwent high-resolution magnetic resonance imaging (MRI) to estimate hippocampal volume and proton MR spectroscopy (1H MRS) to measure ACC GABA levels. MDD patients, with known ACC GABA levels, were divided into two groups: MDD Low GABA and MDD High GABA. We found a significant reduction in hippocampal volume in the MDD Low GABA group compared to MDD High GABA (p < 0.001) and HC (p = 0.01). The relationship between hippocampal volume and cortical GABA was population (i.e. MDD group) and region specific (i.e. prefrontal cortex). Comparing TRD, non-TRD and HC groups, there was a main effect of group on hippocampal volume (p = 0.04), which post hoc analysis revealed as smaller hippocampal volume in TRD subjects than in non-TRD (p = 0.05) and HC groups (p = 0.03). No hippocampal volume differences between non-TRD and HC groups. The data provides insight into the role of prefrontal neurochemical deficits in the limbic structural abnormalities observed in MDD. In addition, it replicates the relationship between TRD and smaller hippocampal volumes. PMID:25983019

  16. Prefrontal cortical GABA abnormalities are associated with reduced hippocampal volume in major depressive disorder.

    PubMed

    Abdallah, Chadi G; Jackowski, Andrea; Sato, João R; Mao, Xiangling; Kang, Guoxin; Cheema, Raminder; Coplan, Jeremy D; Mathew, Sanjay J; Shungu, Dikoma C

    2015-08-01

    Hippocampal volume reduction has been related to treatment-resistant depression (TRD) and is hypothesized to reflect impaired amino-acid neurotransmission. To better understand the role of amino acid neurotransmission in hippocampal volume deficits, and subsequent resistance to treatment, this study investigated the relationship between hippocampal volumes and GABA levels in the anterior cingulate cortex (ACC), previously associated with TRD. Thirty-three medication-free major depressive disorder (MDD; 14 TRD and 19 non-TRD) and 26 healthy controls (HC) subjects were studied. Participants underwent high-resolution magnetic resonance imaging (MRI) to estimate hippocampal volume and proton MR spectroscopy ((1)H MRS) to measure ACC GABA levels. MDD patients, with known ACC GABA levels, were divided into two groups: MDD Low GABA and MDD High GABA. We found a significant reduction in hippocampal volume in the MDD Low GABA group compared to MDD High GABA (p<0.001) and HC (p=0.01). The relationship between hippocampal volume and cortical GABA was population (i.e. MDD group) and region specific (i.e. prefrontal cortex). Comparing TRD, non-TRD and HC groups, there was a main effect of group on hippocampal volume (p=0.04), which post hoc analysis revealed as smaller hippocampal volume in TRD subjects than in non-TRD (p=0.05) and HC groups (p=0.03). No hippocampal volume differences between non-TRD and HC groups. The data provides insight into the role of prefrontal neurochemical deficits in the limbic structural abnormalities observed in MDD. In addition, it replicates the relationship between TRD and smaller hippocampal volumes.

  17. mRNA and Protein Levels for GABA[subscript A][alpha]4, [alpha]5, [beta]1 and GABA[subscript B]R1 Receptors are Altered in Brains from Subjects with Autism

    ERIC Educational Resources Information Center

    Fatemi, S. Hossein; Reutiman, Teri J.; Folsom, Timothy D.; Rooney, Robert J.; Patel, Diven H.; Thuras, Paul D.

    2010-01-01

    We have shown altered expression of gamma-aminobutyric acid A (GABA[subscript A]) and gamma-aminobutyric acid B (GABA[subscript B]) receptors in the brains of subjects with autism. In the current study, we sought to verify our western blotting data for GABBR1 via qRT-PCR and to expand our previous work to measure mRNA and protein levels of 3…

  18. Mood regulation. GABA/glutamate co-release controls habenula output and is modified by antidepressant treatment.

    PubMed

    Shabel, Steven J; Proulx, Christophe D; Piriz, Joaquin; Malinow, Roberto

    2014-09-19

    The lateral habenula (LHb), a key regulator of monoaminergic brain regions, is activated by negatively valenced events. Its hyperactivity is associated with depression. Although enhanced excitatory input to the LHb has been linked to depression, little is known about inhibitory transmission. We discovered that γ-aminobutyric acid (GABA) is co-released with its functional opponent, glutamate, from long-range basal ganglia inputs (which signal negative events) to limit LHb activity in rodents. At this synapse, the balance of GABA/glutamate signaling is shifted toward reduced GABA in a model of depression and increased GABA by antidepressant treatment. GABA and glutamate co-release therefore controls LHb activity, and regulation of this form of transmission may be important for determining the effect of negative life events on mood and behavior.

  19. GABA localization in the nematode Ascaris

    SciTech Connect

    Guastella, J.

    1988-01-01

    A histochemical approach was used to examine the distribution of GABA-associated neurons in the nematode Ascaris, an organism whose small number of morphologically simple neurons make it an excellent preparation for analyzing neuronal phenotypes. Two GABAergic markers were examined: GABA-like immunoreactivity (GLIR), a marker for endogenous stores of GABA; and ({sup 3}H)-GABA uptake, a marker for GABA uptake sites. Strong GLIR was present in the cell bodies, neurites and commissures of dorsal and ventral inhibitory motorneurons present in this region. Strong GLIR was also present in the cell bodies and processes of the four RME neurons in the nerve ring and in several other ganglionic neurons. Staining was absent in excitatory motorneurons, in ventral cord interneurons and in muscle cells and hypodermis. GABA uptake sites were found in single neural processes in both the ventral and dorsal nerve cords. ({sup 3}H)-GABA labeling was also observed in the other two RME cells and several other cephalic neurons. Four putative cholinergic excitatory motorneurons in the retrovesicular ganglion (RVG) were heavily labeled. Ventral and dorsal nerve cord inhibitory motorneurons did not take up ({sup 3}H)-GABA. Labeling of the ventral cord excitatory motorneuron somata and cell bodies was at or slightly above background. Heavy labeling of muscle cells was also observed.

  20. Structure, function, and plasticity of GABA transporters

    PubMed Central

    Scimemi, Annalisa

    2014-01-01

    GABA transporters belong to a large family of neurotransmitter:sodium symporters. They are widely expressed throughout the brain, with different levels of expression in different brain regions. GABA transporters are present in neurons and in astrocytes and their activity is crucial to regulate the extracellular concentration of GABA under basal conditions and during ongoing synaptic events. Numerous efforts have been devoted to determine the structural and functional properties of GABA transporters. There is also evidence that the expression of GABA transporters on the cell membrane and their lateral mobility can be modulated by different intracellular signaling cascades. The strength of individual synaptic contacts and the activity of entire neuronal networks may be finely tuned by altering the density, distribution and diffusion rate of GABA transporters within the cell membrane. These findings are intriguing because they suggest the existence of complex regulatory systems that control the plasticity of GABAergic transmission in the brain. Here we review the current knowledge on the structural and functional properties of GABA transporters and highlight the molecular mechanisms that alter the expression and mobility of GABA transporters at central synapses. PMID:24987330

  1. Investigation of Retinoic Acid Function During Embryonic Brain Development Using Retinaldehyde-Rescued Rdh10 Knockout Mice

    PubMed Central

    Chatzi, Christina; Cunningham, Thomas J.; Duester, Gregg

    2013-01-01

    Background Retinoic acid (RA) signaling controls patterning and neuronal differentiation within the hindbrain, but forebrain RA function remains controversial. RA is produced from metabolism of retinol to retinaldehyde by retinol dehydrogenase (RDH), followed by metabolism of retinaldehyde to RA by retinaldehyde dehydrogenase (RALDH). Previous studies on Raldh2−/− and Raldh3−/− mice demonstrated an RA requirement for γ-aminobutyric acid (GABA)ergic and dopaminergic differentiation in forebrain basal ganglia, but no RA requirement was observed during early forebrain patterning or subsequent fore-brain cortical expansion. However, other studies suggested that RA controls forebrain patterning, and analysis of ethylnitrosourea-induced Rdh10 mutants suggested that RA synthesized in the meninges stimulates forebrain cortical expansion. Results We generated Rdh10−/− mouse embryos that lack RA activity early in the head and later in the meninges. We observed defects in hindbrain patterning and eye RA signaling, but early forebrain patterning was unaffected. Retinaldehyde treatment of Rdh10−/− embryos from E7–E9 rescues a cranial skeletal defect, resulting in E14.5 embryos lacking meningeal RA activity but maintaining normal forebrain shape and cortical expansion. Conclusions Rdh10−/− embryos demonstrate that RA controls hindbrain but not early forebrain patterning, while studies on retinaldehyde-rescued Rdh10−/− embryos show that meningeal RA synthesis is unnecessary to stimulate forebrain cortical expansion. PMID:23765990

  2. Characterization of GABA/sub A/ receptor-mediated /sup 36/chloride uptake in rat brain synaptoneurosomes

    SciTech Connect

    Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.

    1987-09-07

    ..gamma..-Aminobutyric acid (GABA) receptor-mediated /sup 36/chloride (/sup 36/Cl/sup -/) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated /sup 36/Cl/sup -/ uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated /sup 36/Cl/sup -/ uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated /sup 36/Cl/sup -/ uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br/sup -/>Cl/sup -/greater than or equal toNO/sub 3//sup -/>I/sup -/greater than or equal toSCN/sup -/>>C/sub 3/H/sub 5/OO/sup -/greater than or equal toClO/sub 4//sup -/>F/sup -/, consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl/sup -/ channel. 43 references, 4 figures, 3 tables.

  3. GABA regulates synaptic integration of newly generated neurons in the adult brain

    NASA Astrophysics Data System (ADS)

    Ge, Shaoyu; Goh, Eyleen L. K.; Sailor, Kurt A.; Kitabatake, Yasuji; Ming, Guo-Li; Song, Hongjun

    2006-02-01

    Adult neurogenesis, the birth and integration of new neurons from adult neural stem cells, is a striking form of structural plasticity and highlights the regenerative capacity of the adult mammalian brain. Accumulating evidence suggests that neuronal activity regulates adult neurogenesis and that new neurons contribute to specific brain functions. The mechanism that regulates the integration of newly generated neurons into the pre-existing functional circuitry in the adult brain is unknown. Here we show that newborn granule cells in the dentate gyrus of the adult hippocampus are tonically activated by ambient GABA (γ-aminobutyric acid) before being sequentially innervated by GABA- and glutamate-mediated synaptic inputs. GABA, the major inhibitory neurotransmitter in the adult brain, initially exerts an excitatory action on newborn neurons owing to their high cytoplasmic chloride ion content. Conversion of GABA-induced depolarization (excitation) into hyperpolarization (inhibition) in newborn neurons leads to marked defects in their synapse formation and dendritic development in vivo. Our study identifies an essential role for GABA in the synaptic integration of newly generated neurons in the adult brain, and suggests an unexpected mechanism for activity-dependent regulation of adult neurogenesis, in which newborn neurons may sense neuronal network activity through tonic and phasic GABA activation.

  4. Tolerance to allopregnanolone with focus on the GABA-A receptor

    PubMed Central

    Turkmen, Sahruh; Backstrom, Torbjorn; Wahlstrom, Goran; Andreen, Lotta; Johansson, Inga-Maj

    2011-01-01

    Many studies have suggested a relationship between stress, sex steroids, and negative mental and mood changes in humans. The progesterone metabolite allopregnanolone is a potent endogenous ligand of the γ-amino butyric acid –A (GABA-A) receptor, and the most discussed neuroactive steroid. Variations in the levels of neuroactive steroids that influence the activity of the GABA-A receptor cause a vulnerability to mental and emotional pathology. There are physiological conditions in which allopregnanolone production increases acutely (e.g. stress) or chronically (e.g. menstrual cycle, pregnancy), thus exposing the GABA-A receptor to high and continuous allopregnanolone concentrations. In such conditions, tolerance to allopregnanolone may develop. We have shown that both acute and chronic tolerances can develop to the effects of allopregnanolone. Following the development of acute allopregnanolone tolerance, there is a decrease in the abundance of the GABA-A receptor α4 subunit and the expression of the α4 subunit mRNA in the ventral-posteriomedial nucleus of the thalamus. Little is known about the mechanism behind allopregnanolone tolerance and its effects on assembly of the GABA-A receptor composition. The exact mechanism of the allopregnanolone tolerance phenomena remains unclear. The purpose of this review is to summarize certain aspects of current knowledge concerning allopregnanolone tolerance and changes in the GABA-A receptors. PMID:20883478

  5. Growth cones isolated from developing rat forebrain: uptake and release of GABA and noradrenaline.

    PubMed

    Lockerbie, R O; Gordon-Weeks, P R; Pearce, B R

    1985-08-01

    A growth cone-enriched fraction isolated from neonatal rat forebrain was shown to accumulate gamma-amino [3H]butyric acid ([3H]-GABA) and [3H]noradrenaline ([3H]NA). Uptake of both neurotransmitters was sodium- and temperature-dependent and exhibited saturation kinetics with Km values of 17.7 microM and 4.5 microM respectively and Vmax values of 114 pmol/min/mg protein and 59 pmol/min/mg protein respectively. Electron microscopic autoradiography showed that about 50% of isolated growth cones can accumulate [3H]GABA. Inhibitor studies showed that beta-alanine was a relatively weak inhibitor of [3H]GABA uptake compared to nipecotic acid and diamino-butyric acid. Growth cone fractions preloaded with [3H]GABA and [3H]NA demonstrated a K+ (25 mM) -induced release of both neurotransmitters. Of the K+-stimulated release of [3H]GABA 50% was Ca2+-dependent, whereas the release of [3H]NA was entirely Ca2+-independent.

  6. 3-Chloro,4-methoxyfendiline is a potent GABA(B) receptor potentiator in rat neocortical slices.

    PubMed

    Ong, Jennifer; Parker, David A S; Marino, Victor; Kerr, David I B; Puspawati, Ni Made; Prager, Rolf H

    2005-01-10

    Using grease-gap recording from rat neocortical slices, the GABA(B) receptor agonist baclofen elicited reversible and concentration-dependent hyperpolarizing responses (EC50=18+/-2.3 microM). The hyperpolarizations were antagonised by the GABA(B) receptor antagonist Sch 50911 [(+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid). (+)-N-1-(3-chloro-4-methoxyphenyl)ethyl-3,3-diphenylpropylamine (3-chloro,4-methoxyfendiline; 3-Cl,4-MeO-fendiline) reversibly potentiated baclofen-induced hyperpolarizing responses, which were reduced by Sch 50911, producing leftward shifts of the baclofen concentration-response curves, with a marked increase in the maximal hyperpolarization (EC50=2+/-0.5 microM). In slices preincubated with either [3H]GABA or [3H]glutamic acid, 3-Cl,4-MeO-fendiline (1 microM) potentiated the inhibitory effect of baclofen (2 microM) on the electrically evoked release of [3H]GABA and had a similar effect on the release of [3H]glutamic acid at a concentration of 0.5 microM, without affecting the basal release. These effects were blocked by Sch 50911 (10 microM). Our findings suggest that 3-Cl,4-MeO-fendiline is a potent potentiator of pre- and postsynaptic GABA(B) receptor-mediated functions.

  7. Pontine Reticular Formation (PnO) Administration of Hypocretin-1 Increases PnO GABA Levels and Wakefulness

    PubMed Central

    Watson, Christopher J.; Soto-Calderon, Haideliza; Lydic, Ralph; Baghdoyan, Helen A.

    2008-01-01

    Study Objectives: GABAergic transmission in the oral part of the pontine reticular formation (PnO) increases wakefulness. The hypothalamic peptide hypocretin-1 (orexin A) promotes wakefulness, and the PnO receives hypocretinergic input. The present study tested the hypothesis that PnO administration of hypocretin-1 increases PnO GABA levels and increases wakefulness. This study also tested the hypothesis that wakefulness is either increased or decreased, respectively, by PnO administration of drugs known to selectively increase or decrease GABA levels. Design: A within-subjects design was used for microdialysis and microinjection experiments. Setting: University of Michigan. Patients or Participants: Experiments were performed using adult male Crl:CD® (SD)IGS BR (Sprague-Dawley) rats (n = 46). Interventions: PnO administration of hypocretin-1, nipecotic acid (a GABA uptake inhibitor that increases extracellular GABA levels), 3-mercaptopropionic acid (a GABA synthesis inhibitor that decreases extracellular GABA levels; 3-MPA), and Ringer solution (vehicle control). Measurements and Results: Dialysis administration of hypocretin-1 to the PnO caused a statistically significant, concentration-dependent increase in PnO GABA levels. PnO microinjection of hypocretin-1 or nipecotic acid caused a significant increase in wakefulness and a significant decrease in non-rapid eye movement (NREM) sleep and REM sleep. Microinjecting 3-MPA into the PnO caused a significant increase in NREM sleep and REM sleep and a significant decrease in wakefulness. Conclusions: An increase or a decrease in PnO GABA levels causes an increase or decrease, respectively, in wakefulness. Hypocretin-1 may promote wakefulness, at least in part, by increasing GABAergic transmission in the PnO. Citation: Watson CJ; Soto-Calderon H; Lydic R; Baghdoyan HA. Pontine reticular formation (PnO) administration of hypocretin-1 increases PnO GABA levels and wakefulness. SLEEP 2008;31(4):453-464. PMID:18457232

  8. {gamma}-aminobutyric acid{sub A} (GABA{sub A}) receptor regulates ERK1/2 phosphorylation in rat hippocampus in high doses of Methyl Tert-Butyl Ether (MTBE)-induced impairment of spatial memory

    SciTech Connect

    Zheng Gang; Zhang Wenbin; Zhang Yun; Chen Yaoming; Liu Mingchao; Yao Ting; Yang Yanxia; Zhao Fang; Li Jingxia; Huang Chuanshu; Luo Wenjing Chen Jingyuan

    2009-04-15

    Experimental and occupational exposure to Methyl Tert-Butyl Ether (MTBE) has been reported to induce neurotoxicological and neurobehavioral effects, such as headache, nausea, dizziness, and disorientation, etc. However, the molecular mechanisms involved in MTBE-induced neurotoxicity are still not well understood. In the present study, we investigated the effects of MTBE on spatial memory and the expression and function of GABA{sub A} receptor in the hippocampus. Our results demonstrated that intraventricular injection of MTBE impaired the performance of the rats in a Morris water maze task, and significantly increased the expression of GABA{sub A} receptor {alpha}1 subunit in the hippocampus. The phosphorylation of ERK1/2 decreased after the MTBE injection. Furthermore, the decreased ability of learning and the reduction of phosphorylated ERK1/2 level of the MTBE-treated rats was partly reversed by bicuculline injected 30 min before the training. These results suggested that MTBE exposure could result in impaired spatial memory. GABA{sub A} receptor may play an important role in the MTBE-induced impairment of learning and memory by regulating the phosphorylation of ERK in the hippocampus.

  9. GABA receptor subunit composition relative to insecticide potency and selectivity.

    PubMed

    Ratra, G S; Casida, J E

    2001-07-01

    Three observations on the 4-[(3)H]propyl-4'-ethynylbicycloorthobenzoate ([(3)H]EBOB) binding site in the gamma-aminobutyric acid (GABA) receptor indicate the specific target for insecticide action in human brain and a possible mechanism for selectivity. First, from published data, alpha-endosulfan, lindane and fipronil compete for the [(3)H]EBOB binding site with affinities of 0.3--7 nM in both human recombinant homooligomeric beta 3 receptors and housefly head membranes. Second, from structure-activity studies, including new data, GABAergic insecticide binding potency on the pentameric receptor formed from the beta 3 subunit correlates well with that on the housefly receptor (r=0.88, n=20). This conserved inhibitor specificity is consistent with known sequence homologies in the housefly GABA receptor and the human GABA(A) receptor beta 3 subunit. Third, as mostly new findings, various combinations of alpha 1, alpha 6, and gamma 2 subunits coexpressed with a beta 1 or beta 3 subunit confer differential insecticide binding sensitivity, particularly to fipronil, indicating that subunit composition is a major factor in insecticide selectivity.

  10. Comparison between the modes of action of novel meta-diamide and macrocyclic lactone insecticides on the RDL GABA receptor.

    PubMed

    Nakao, Toshifumi; Banba, Shinichi; Hirase, Kangetsu

    2015-05-01

    Macrocyclic lactones, avermectins, and milbemycins are widely used to control arthropods, nematodes, and endo- and ectoparasites in livestock and pets. Their main targets are glutamate-gated chloride channels. Furthermore, macrocyclic lactones reportedly interact with insect RDL γ-aminobutyric acid (GABA) receptors, but their modes of action on insect RDL GABA receptors remain unknown. In this study, we attempted to better understand the modes of action of macrocyclic lactones on RDL GABA receptors. We observed that ivermectin and milbemectin behaved as allosteric agonists of the Drosophila RDL GABA receptor. G336A, G336S, and G336T mutations had profound effects on the activities of ivermectin and milbemectin, and a G336M mutation abolished the allosteric agonist and antagonist activities of these macrocyclic lactones. These results suggest that G336 in TM3 of the Drosophila RDL GABA receptor is important for the binding of macrocyclic lactones. Recently, it has been suggested that a novel RDL GABA receptor antagonist, 3-benzamido-N-(2-bromo-4-perfluoroisopropyl-6-(trifluoromethyl)phenyl)-2-fluorobenzamide (meta-diamide 7), binds to the transmembrane intersubunit pocket near G336 in the Drosophila RDL GABA receptor. Thus, we compared the effects of mutations around G336 and A302 mutations in TM2 on the activities of macrocyclic lactone and meta-diamide 7. The effects of L281C, V340Q, V340N, A302S, and A302N mutations on the activity of meta-diamide 7 differed from those on ivermectin and milbemectin. Molecular modeling studies showed that macrocyclic lactones docked in the intersubunit pocket near G336 in the Drosophila RDL GABA receptor in the open state. In contrast, meta-diamide 7 docked into the Drosophila RDL GABA receptor in the closed state. This suggests that the modes of action of macrocyclic lactone binding to the wild-type Drosophila RDL GABA receptor differ from those of meta-diamide binding.

  11. Dark-rearing-induced reduction of GABA and GAD and prevention of the effect by BDNF in the mouse retina.

    PubMed

    Lee, Eun-Jin; Gibo, Tricia L; Grzywacz, Norberto M

    2006-10-01

    Gamma-aminobutyric acid (GABA) is an important retinal neurotransmitter. We studied the expression of GABA, glutamate decarboxylase 65 (GAD65) and GAD67 by immunocytochemistry and Western blot, in the retinas of control and dark-reared C57BL/6J black mice. This study asked three questions. First, is visual input necessary for the normal expression of GABA, GAD65 and GAD67? Second, can the retina recover from the effects of dark-rearing if returned to a normal light-dark cycle? Third, does BDNF prevent the influence of dark-rearing on the expression of GABA and GAD? At postnatal day 10 (P10), before eye opening, GABA immunoreactivity was present in the ganglion cell layer (GCL), in the innermost rows of the inner nuclear layer (INL) and throughout the inner plexiform layer (IPL) of control and dark-reared retinas. In P30 control retinas, GABA immunoreactivity showed similar patterns to those at P10. However, in P30 dark-reared retinas, the density of GABA-immunoreactive cells was lower in both the INL and GCL than in control retinas. In addition, visual deprivation retarded GABA immunoreactivity in the IPL. Western blot analysis showed corresponding differences in the levels of GAD65 but not of GAD67 expression between control and dark-rearing conditions. In our study, dark-rearing effects were reversed when the mice were put in normal cyclic light-dark conditions for 2 weeks. Moreover, dark-reared retinas treated with BDNF showed normal expression of both GABA and GAD65. Our data indicate that normal expression of GABA and GAD65 is dependent on visual input. Furthermore, the data suggest that BDNF controls this dependence.

  12. Insula and anterior cingulate GABA levels in post-traumatic stress disorder: Preliminary findings using magnetic resonance spectroscopy

    PubMed Central

    Rosso, Isabelle M.; Weiner, Melissa R.; Crowley, Davidan J; Silveri, Marisa M.; Rauch, Scott L.; Jensen, J. Eric

    2013-01-01

    Background Increased reactivity of the insular cortex and decreased activity of the dorsal anterior cingulate (ACC) are seen in functional imaging studies of post-traumatic stress disorder (PTSD), and may partly explain the persistent fear- and anxiety-proneness that characterize the disorder. A possible neurochemical correlate is altered function of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). We report results from what we believe is the first study applying proton magnetic resonance spectroscopy (1H-MRS) to measure brain GABA in PTSD. Methods Thirteen adults with DSM-IV PTSD and 13 matched healthy control subjects underwent single voxel 1H-MRS at 4 Tesla. GABA was measured in the right anterior insula and dorsal anterior cingulate, using MEGAPRESS spectral editing. Subjects were interviewed with the Structured Clinical Interview for DSM-IV and the Clinician Administered PTSD Scale, and also completed the State and Trait Anxiety Inventory. Results Insula GABA was significantly lower in PTSD subjects than in controls, and dorsal ACC GABA did not differ significantly between the groups. Insula GABA was not significantly associated with severity of PTSD symptoms. However, lower insula GABA was associated with significantly higher state and trait anxiety in the subject sample as a whole. Conclusions PTSD is associated with reduced GABA in the right anterior insula. This preliminary evidence of the 1H-MRS GABA metabolite as a possible biomarker of PTSD encourages replication in larger samples and examination of relations with symptom dimensions. Future studies also should examine whether insula GABA is a marker of anxiety proneness, cutting across clinical diagnostic categories. PMID:23861191

  13. Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases.

    PubMed

    Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A; Jenkins, Andrew; Traynelis, Stephen F

    2015-07-01

    The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases. PMID:25904555

  14. Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases.

    PubMed

    Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A; Jenkins, Andrew; Traynelis, Stephen F

    2015-07-01

    The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases.

  15. Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases

    PubMed Central

    Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A.; Jenkins, Andrew

    2015-01-01

    The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases. PMID:25904555

  16. The impact of GABA in harpin-elicited biotic stress responses in Nicotiana tabaccum.

    PubMed

    Dimlioğlu, Gizem; Daş, Zeycan Akcan; Bor, Melike; Özdemir, Filiz; Türkan, İsmail

    2015-09-01

    Harpin is a bacterial elicitor protein that was first isolated from Erwinia amylovora. Infiltration of this elicitor into the leaves of plants activates systemic acquired resistance against a variety of plant pathogens via the salicyclic acid defense pathway. The non-protein amino acid, neurotransmission inhibitor molecule of mammals-GABA- is found in all organisms and is known to be an important component of stress responses in plants. We hypothesized a possible interaction between harpin-induced defense responses and GABA shunt. Therefore, we conducted experiments on harpin-infiltrated tobacco and analyzed the components of GABA shunt in relation to growth, photosynthesis and H2O2 levels. RGR, RWC and photosynthetic efficiency were all affected in harpin-infiltrated tobacco leaves, but the rate of decline was more remarkable on RGR. H2O2 levels showed significant difference on 7 days after harpin infiltration when the necrotic lesions were also visible. GABA accumulation was increased and glutamate levels were decreased parallel to the differences in GDH and GAD enzyme activities, especially on days 5 and 7 of harpin infiltration. Transcript abundance of GDH and GAD encoding genes were differentially regulated in harpin-infiltrated leaves as compared to that of control and mock groups. In the present study, for the first time we showed a relationship between harpin-elicited responses and GABA in tobacco that was not mediated by H2O2 accumulation. Harpin infiltration significantly induced the first components of the GABA shunt such as GDH, GAD, glutamate and GABA in tobacco. PMID:26432406

  17. Interleukin-15 receptor is essential to facilitate GABA transmission and hippocampal dependent memory

    PubMed Central

    He, Yi; Wu, Xiaojun; Hsuchou, Hung; Kastin, Abba J.; Khan, Reas S.; Pistell, Paul J.; Wang, Wei-Hsung; Feng, Jiming; Li, Zengbiao; Guo, Xiaochuan; Pan, Weihong

    2010-01-01

    Interleukin-15 (IL15) is a cytokine produced by normal brain, but the functions of the IL15 system in normal adults are not yet clear. The hypothesis that the hippocampal IL15 system is essential for memory consolidation was tested by use of IL15Rα knockout mice in behavioral, biochemical, immunohistological, and electron microscopic analyses. The knockout mice showed deficits in memory, determined by the Stone T-maze and fear conditioning. In their hippocampi, the concentration of γ-aminobutyric acid (GABA) was significantly lower. There were region specific changes of the GABA synthesizing enzyme glutamic acid decarboxidase (GAD), with increased GAD-67 immunopositive interneurons in the stratum oriens of the CA1 region of the hippocampus, accompanied by non-significant reduction of GAD-67 synapses in the CA3 region. Western blotting showed an increase of GAD-65, but not GAD-67, in the hippocampal homogenate. The ultrastructure of the hippocampus remained intact in the knockout mice. To further test the hypothesis that IL15 directly modulates GABA turnover by reuptake mechanisms, the dose-response relationship of IL15 on 3H-GABA uptake was determined in two neuronal cell lines. The effective and non-toxic dose was further used in the synaptosomal uptake studies. IL15 decreased the uptake of 3H-GABA in synaptosomes from the forebrain of wildtype mice. Consistent with this, IL15Rα knockout mice had increased synaptosomal uptake of 3H-GABA. Overall, the results show novel functions of a unique cytokine in normal hippocampal activity by regulating GABA transmission. PMID:20357123

  18. GABA and glycine in the developing brain.

    PubMed

    Ito, Susumu

    2016-09-01

    GABA and glycine are major inhibitory neurotransmitters in the CNS and act on receptors coupled to chloride channels. During early developmental periods, both GABA and glycine depolarize membrane potentials due to the relatively high intracellular Cl(-) concentration. Therefore, they can act as excitatory neurotransmitters. GABA and glycine are involved in spontaneous neural network activities in the immature CNS such as giant depolarizing potentials (GDPs) in neonatal hippocampal neurons, which are generated by the synchronous activity of GABAergic interneurons and glutamatergic principal neurons. GDPs and GDP-like activities in the developing brains are thought to be important for the activity-dependent functiogenesis through Ca(2+) influx and/or other intracellular signaling pathways activated by depolarization or stimulation of metabotropic receptors. However, if GABA and glycine do not shift from excitatory to inhibitory neurotransmitters at the birth and in maturation, it may result in neural disorders including autism spectrum disorders. PMID:26951057

  19. GABA concentration in superior temporal sulcus predicts gamma power and perception in the sound-induced flash illusion.

    PubMed

    Balz, Johanna; Keil, Julian; Roa Romero, Yadira; Mekle, Ralf; Schubert, Florian; Aydin, Semiha; Ittermann, Bernd; Gallinat, Jürgen; Senkowski, Daniel

    2016-01-15

    In everyday life we are confronted with inputs of multisensory stimuli that need to be integrated across our senses. Individuals vary considerably in how they integrate multisensory information, yet the neurochemical foundations underlying this variability are not well understood. Neural oscillations, especially in the gamma band (>30Hz) play an important role in multisensory processing. Furthermore, gamma-aminobutyric acid (GABA) neurotransmission contributes to the generation of gamma band oscillations (GBO), which can be sustained by activation of metabotropic glutamate receptors. Hence, differences in the GABA and glutamate systems might contribute to individual differences in multisensory processing. In this combined magnetic resonance spectroscopy and electroencephalography study, we examined the relationships between GABA and glutamate concentrations in the superior temporal sulcus (STS), source localized GBO, and illusion rate in the sound-induced flash illusion (SIFI). In 39 human volunteers we found robust relationships between GABA concentration, GBO power, and the SIFI perception rate (r-values=0.44 to 0.53). The correlation between GBO power and SIFI perception rate was about twofold higher when the modulating influence of the GABA level was included in the analysis as compared to when it was excluded. No significant effects were obtained for glutamate concentration. Our study suggests that the GABA level shapes individual differences in audiovisual perception through its modulating influence on GBO. GABA neurotransmission could be a promising target for treatment interventions of multisensory processing deficits in clinical populations, such as schizophrenia or autism.

  20. GabaB receptors activation in the NTS blocks the glycemic responses induced by carotid body receptor stimulation.

    PubMed

    Lemus, Mónica; Montero, Sergio; Cadenas, José Luis; Lara, José Jesús; Tejeda-Chávez, Héctor Rafael; Alvarez-Buylla, Ramón; de Alvarez-Buylla, Elena Roces

    2008-08-18

    The carotid body receptors participate in glucose regulation sensing glucose levels in blood entering the cephalic circulation. The carotid body receptors information, is initially processed within the nucleus tractus solitarius (NTS) and elicits changes in circulating glucose and brain glucose uptake. Previous work has shown that gamma-aminobutyric acid (GABA) in NTS modulates respiratory reflexes, but the role of GABA within NTS in glucose regulation remains unknown. Here we show that GABA(B) receptor agonist (baclofen) or antagonists (phaclofen and CGP55845A) locally injected into NTS modified arterial glucose levels and brain glucose retention. Control injections outside NTS did not elicit these responses. In contrast, GABA(A) agonist and antagonist (muscimol or bicuculline) produced no significant changes in blood glucose levels. When these GABAergic drugs were applied before carotid body receptors stimulation, again, only GABA(B) agonist or antagonist significantly affected glycemic responses; baclofen microinjection significantly reduced the hyperglycemic response and brain glucose retention observed after carotid body receptors stimulation, while phaclofen produced the opposite effect, increasing significantly hyperglycemia and brain glucose retention. These results indicate that activation of GABA(B), but not GABA(A), receptors in the NTS modulates the glycemic responses after anoxic stimulation of the carotid body receptors, and suggest the presence of a tonic inhibitory mechanism in the NTS to avoid hyperglycemia.

  1. VTA GABA neurons modulate specific learning behaviors through the control of dopamine and cholinergic systems

    PubMed Central

    Creed, Meaghan C.; Ntamati, Niels R.; Tan, Kelly R.

    2014-01-01

    The mesolimbic reward system is primarily comprised of the ventral tegmental area (VTA) and the nucleus accumbens (NAc) as well as their afferent and efferent connections. This circuitry is essential for learning about stimuli associated with motivationally-relevant outcomes. Moreover, addictive drugs affect and remodel this system, which may underlie their addictive properties. In addition to dopamine (DA) neurons, the VTA also contains approximately 30% γ-aminobutyric acid (GABA) neurons. The task of signaling both rewarding and aversive events from the VTA to the NAc has mostly been ascribed to DA neurons and the role of GABA neurons has been largely neglected until recently. GABA neurons provide local inhibition of DA neurons and also long-range inhibition of projection regions, including the NAc. Here we review studies using a combination of in vivo and ex vivo electrophysiology, pharmacogenetic and optogenetic manipulations that have characterized the functional neuroanatomy of inhibitory circuits in the mesolimbic system, and describe how GABA neurons of the VTA regulate reward and aversion-related learning. We also discuss pharmacogenetic manipulation of this system with benzodiazepines (BDZs), a class of addictive drugs, which act directly on GABAA receptors located on GABA neurons of the VTA. The results gathered with each of these approaches suggest that VTA GABA neurons bi-directionally modulate activity of local DA neurons, underlying reward or aversion at the behavioral level. Conversely, long-range GABA projections from the VTA to the NAc selectively target cholinergic interneurons (CINs) to pause their firing and temporarily reduce cholinergic tone in the NAc, which modulates associative learning. Further characterization of inhibitory circuit function within and beyond the VTA is needed in order to fully understand the function of the mesolimbic system under normal and pathological conditions. PMID:24478655

  2. Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

    2014-03-01

    The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs. PMID:24638845

  3. Comparative mapping of GABA-immunoreactive neurons in the central nervous systems of nudibranch molluscs.

    PubMed

    Gunaratne, Charuni A; Sakurai, Akira; Katz, Paul S

    2014-03-01

    The relative simplicity of certain invertebrate nervous systems, such as those of gastropod molluscs, allows behaviors to be dissected at the level of small neural circuits composed of individually identifiable neurons. Elucidating the neurotransmitter phenotype of neurons in neural circuits is important for understanding how those neural circuits function. In this study, we examined the distribution of γ-aminobutyric-acid;-immunoreactive (GABA-ir) neurons in four species of sea slugs (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia): Tritonia diomedea, Melibe leonina, Dendronotus iris, and Hermissenda crassicornis. We found consistent patterns of GABA immunoreactivity in the pedal and cerebral-pleural ganglia across species. In particular, there were bilateral clusters in the lateral and medial regions of the dorsal surface of the cerebral ganglia as well as a cluster on the ventral surface of the pedal ganglia. There were also individual GABA-ir neurons that were recognizable across species. The invariant presence of these individual neurons and clusters suggests that they are homologous, although there were interspecies differences in the numbers of neurons in the clusters. The GABAergic system was largely restricted to the central nervous system, with the majority of axons confined to ganglionic connectives and commissures, suggesting a central, integrative role for GABA. GABA was a candidate inhibitory neurotransmitter for neurons in central pattern generator (CPG) circuits underlying swimming behaviors in these species, however none of the known swim CPG neurons were GABA-ir. Although the functions of these GABA-ir neurons are not known, it is clear that their presence has been strongly conserved across nudibranchs.

  4. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

    PubMed

    Xu, Yan; Furutani, Shogo; Ihara, Makoto; Ling, Yun; Yang, Xinling; Kai, Kenji; Hayashi, Hideo; Matsuda, Kazuhiko

    2015-01-01

    Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori) larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA)-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR) RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.

  5. Synaptic GABA release prevents GABA transporter type-1 reversal during excessive network activity

    PubMed Central

    Savtchenko, Leonid; Megalogeni, Maria; Rusakov, Dmitri A.; Walker, Matthew C.; Pavlov, Ivan

    2015-01-01

    GABA transporters control extracellular GABA, which regulates the key aspects of neuronal and network behaviour. A prevailing view is that modest neuronal depolarization results in GABA transporter type-1 (GAT-1) reversal causing non-vesicular GABA release into the extracellular space during intense network activity. This has important implications for GABA uptake-targeting therapies. Here we combined a realistic kinetic model of GAT-1 with experimental measurements of tonic GABAA receptor currents in ex vivo hippocampal slices to examine GAT-1 operation under varying network conditions. Our simulations predict that synaptic GABA release during network activity robustly prevents GAT-1 reversal. We test this in the 0 Mg2+ model of epileptiform discharges using slices from healthy and chronically epileptic rats and find that epileptiform activity is associated with increased synaptic GABA release and is not accompanied by GAT-1 reversal. We conclude that sustained efflux of GABA through GAT-1 is unlikely to occur during physiological or pathological network activity. PMID:25798861

  6. A tight coupling between β₂Y97 and β₂F200 of the GABA(A) receptor mediates GABA binding.

    PubMed

    Tran, Phu N; Laha, Kurt T; Wagner, David A

    2011-10-01

    The GABA(A) receptor is an oligopentameric chloride channel that is activated via conformation changes induced upon the binding of the endogenous ligand, GABA, to the extracellular inter-subunit interfaces. Although dozens of amino acid residues at the α/β interface have been implicated in ligand binding, the structural elements that mediate ligand binding and receptor activation are not yet fully described. In this study, double-mutant cycle analysis was employed to test for possible interactions between several arginines (α₁R67, α₁R120, α₁R132, and β₂R207) and two aromatic residues (β₂Y97 and β₂F200) that are present in the ligand-binding pocket and are known to influence GABA affinity. Our results show that neither α₁R67 nor α₁R120 is functionally coupled to either of the aromatics, whereas a moderate coupling exists between α₁R132 and both aromatic residues. Significant functional coupling between β₂R207 and both β₂Y97 and β₂F200 was found. Furthermore, we identified an even stronger coupling between the two aromatics, β₂Y97 and β₂F200, and for the first time provided direct evidence for the involvement of β₂Y97 and β₂F200 in GABA binding. As these residues are tightly linked, and mutation of either has similar, severe effects on GABA binding and receptor kinetics, we believe they form a single functional unit that may directly coordinate GABA.

  7. GABA/benzodiazepine receptor complex in long-sleep and short-sleep mice

    SciTech Connect

    Marley, R.J.

    1987-01-01

    LS mice are more sensitive to benzodiazepine-induced anesthesia; however, the two lines do not differ in their hypothermic response to flurazepam. SS mice are more resistant to 3-mercaptopropionic acid-induced seizures and more sensitive to the anticonvulsant effects of benzodiazepines. The various correlates of GABA and benzodiazepine actions probably are the results of different mechanisms of action and/or differential regional control. Bicuculline competition for /sup 3/H-GABA binding sites is greater in SS cerebellar tissue and /sup 3/H-flunitrazepam binding is greater in the mid-brain region of LS mice. GABA enhancement of /sup 3/H-flunitrazepma binding is greater in SS mice. Ethanol also enhances /sup 3/H-flunitrazepam binding and increases the levels of /sup 3/H-flunitrazepam binding above those observed for GABA. Using correlational techniques on data from LS and SS mice and several inbred mouse strains, it was demonstrated that a positive relationship exists between the degree of receptor coupling within the GABA receptor complex and the degree of resistance to seizures.

  8. An investigation of the involvement of GABA in certain pharmacological effects of delta-9-tetrahydrocannabinol.

    PubMed

    Pertwee, R G; Browne, S E; Ross, T M; Stretton, C D

    1991-11-01

    Experiments were performed with mice to determine whether doses of the benzodiazepine, flurazepam, or the GABA uptake inhibitor, NO-328, known to potentiate catalepsy induced by delta-9-tetrahydrocannabinol (THC), would also interact synergistically with THC in the production of certain other effects. No synergism was detected either in the production of antinociception (tail flick test) or in a test in which the ability of flurazepam to delay onset of clonic convulsions induced by intravenous infusion of pentylenetetrazole was compared in the presence and absence of THC or cannabidiol. The hypothermic effect of THC was unaffected by NO-328 but enhanced by flurazepam, albeit only at doses higher than those needed to potentiate THC-induced catalepsy. In vitro experiments with guinea pig ileum showed that the ability of THC to inhibit electrically evoked contractions was unaffected by delta-amino-n-valeric acid, a GABA(B) receptor antagonist, and that preparations rendered tolerant to GABA responded normally to THC. Contractions induced by GABA in unstimulated ileal longitudinal muscle were attenuated by THC. We conclude that there is little evidence from our data that any of the THC effects studied were GABA mediated.

  9. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease.

    PubMed

    Salminen, Antero; Jouhten, Paula; Sarajärvi, Timo; Haapasalo, Annakaisa; Hiltunen, Mikko

    2016-01-01

    We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis. PMID:26617286

  10. Methamphetamine-induced enhancement of hippocampal long-term potentiation is modulated by NMDA and GABA receptors in the shell-accumbens.

    PubMed

    Heysieattalab, Soomaayeh; Naghdi, Nasser; Hosseinmardi, Narges; Zarrindast, Mohammad-Reza; Haghparast, Abbas; Khoshbouei, Habibeh

    2016-08-01

    Addictive drugs modulate synaptic transmission in the meso-corticolimbic system by hijacking normal adaptive forms of experience-dependent synaptic plasticity. Psychostimulants such as METH have been shown to affect hippocampal synaptic plasticity, albeit with a less understood synaptic mechanism. METH is one of the most addictive drugs that elicit long-term alterations in the synaptic plasticity in brain areas involved in reinforcement learning and reward processing. Dopamine transporter (DAT) is one of the main targets of METH. As a substrate for DAT, METH decreases dopamine uptake and increases dopamine efflux via the transporter in the target brain regions such as nucleus accumbens (NAc) and hippocampus. Due to cross talk between NAc and hippocampus, stimulation of NAc has been shown to alter hippocampal plasticity. In this study, we tested the hypothesis that manipulation of glutamatergic and GABA-ergic systems in the shell-NAc modulates METH-induced enhancement of long term potentiation (LTP) in the hippocampus. Rats treated with METH (four injections of 5 mg/kg) exhibited enhanced LTP as compared to saline-treated animals. Intra-NAc infusion of muscimol (GABA receptor agonist) decreased METH-induced enhancement of dentate gyrus (DG)-LTP, while infusion of AP5 (NMDA receptor antagonist) prevented METH-induced enhancement of LTP. These data support the interpretation that reducing NAc activity can ameliorate METH-induced hippocampal LTP through a hippocampus-NAc-VTA circuit loop. Synapse 70:325-335, 2016. © 2016 Wiley Periodicals, Inc. PMID:27029021

  11. Genetic differences in the ethanol sensitivity of GABA sub A receptors expressed in Xenopus oocytes

    SciTech Connect

    Wafford, K.A.; Burnett, D.M.; Dunwiddie, T.V.; Harris, R.A. )

    1990-07-20

    Animal lines selected for differences in drug sensitivity can be used to help determine the molecular basis of drug action. Long-sleep (LS) and short-sleep (SS) mice differ markedly in their genetic sensitivity to ethanol. To investigate the molecular basis for this difference, mRNA from brains of LS and SS mice was expressed in Xenopus oocytes and the ethanol sensitivity of gamma-aminobutyric acid A (GABA{sub A})- and N-methyl D-aspartate (NMDA) - activated ion channels was tested. Ethanol facilitated GABA responses in oocytes injected with mRNA from LS mice but antagonized responses in oocytes injected with mRNA from SS animals. Ethanol inhibited NMDA responses equally in the two lines. Thus, genes coding for the GABA{sub A} receptor or associated proteins may be critical determinants of individual differences in ethanol sensitivity.

  12. Ornithine aminotransferase vs. GABA aminotransferase. Implications for the design of new anticancer drugs

    PubMed Central

    Lee, Hyunbeom; Juncosa, Jose I.; Silverman, Richard B.

    2015-01-01

    Ornithine aminotransferase (OAT) and γ-aminobutyric acid aminotransferase (GABA-AT) are classified under the same evolutionary subgroup and share a large portion of structural, functional, and mechanistic features. Therefore, it is not surprising that many molecules that bind to GABA-AT also bind well to OAT. Unlike GABA-AT, OAT had not been viewed as a potential therapeutic target until recently; consequently, the number of therapeutically viable molecules that target OAT is very limited. In this review the two enzymes are compared with respect to their active site structures, catalytic and inactivation mechanisms, and selective inhibitors. Insight is offered that could aid in the design and development of new selective inhibitors of OAT for the treatment of cancer. PMID:25145640

  13. Zinc-induced collapse of augmented inhibition by GABA in a temporal lobe epilepsy model.

    PubMed

    Buhl, E H; Otis, T S; Mody, I

    1996-01-19

    In the kindling model of temporal lobe epilepsy, several physiological indicators of inhibition by gamma-aminobutyric acid (GABA) in the hippocampal dentate gyrus are consistent with an augmented, rather than a diminished, inhibition. In brain slices obtained from epileptic (kindled) rats, the excitatory drive onto inhibitory interneurons was increased and was paralleled by a reduction in the presynaptic autoinhibition of GABA release. This augmented inhibition was sensitive to zinc most likely after a molecular reorganization of GABAA receptor subunits. Consequently, during seizures, inhibition by GABA may be diminished by the zinc released from aberrantly sprouted mossy fiber terminals of granule cells, which are found in many experimental models of epilepsy and in human temporal lobe epilepsy.

  14. Proton Magnetic Resonance Spectroscopy: Relevance of Glutamate and GABA to Neuropsychology.

    PubMed

    Ende, Gabriele

    2015-09-01

    Proton Magnetic Resonance Spectroscopy (MRS) has been widely used to study the healthy and diseased brain in vivo. The availability of whole body MR scanners with a field strength of 3 Tesla and above permit the quantification of many metabolites including the neurotransmitters glutamate (Glu) and γ-aminobutyric acid (GABA). The potential link between neurometabolites identified by MRS and cognition and behavior has been explored in numerous studies both in healthy subjects and in patient populations. Preliminary findings suggest direct or opposite associations between GABA or Glu with impulsivity, anxiety, and dexterity. This chapter is intended to provide an overview of basic principles of MRS and the literature reporting correlations between GABA or Glu and results of neuropsychological assessments.

  15. Mutations in the GABA Transporter SLC6A1 Cause Epilepsy with Myoclonic-Atonic Seizures

    PubMed Central

    Carvill, Gemma L.; McMahon, Jacinta M.; Schneider, Amy; Zemel, Matthew; Myers, Candace T.; Saykally, Julia; Nguyen, John; Robbiano, Angela; Zara, Federico; Specchio, Nicola; Mecarelli, Oriano; Smith, Robert L.; Leventer, Richard J.; Møller, Rikke S.; Nikanorova, Marina; Dimova, Petia; Jordanova, Albena; Petrou, Steven; Helbig, Ingo; Striano, Pasquale; Weckhuysen, Sarah; Berkovic, Samuel F.; Scheffer, Ingrid E.; Mefford, Heather C.

    2015-01-01

    GAT-1, encoded by SLC6A1, is one of the major gamma-aminobutyric acid (GABA) transporters in the brain and is responsible for re-uptake of GABA from the synapse. In this study, targeted resequencing of 644 individuals with epileptic encephalopathies led to the identification of six SLC6A1 mutations in seven individuals, all of whom have epilepsy with myoclonic-atonic seizures (MAE). We describe two truncations and four missense alterations, all of which most likely lead to loss of function of GAT-1 and thus reduced GABA re-uptake from the synapse. These individuals share many of the electrophysiological properties of Gat1-deficient mice, including spontaneous spike-wave discharges. Overall, pathogenic mutations occurred in 6/160 individuals with MAE, accounting for ∼4% of unsolved MAE cases. PMID:25865495

  16. Contribution of polyamines metabolism and GABA shunt to chilling tolerance induced by nitric oxide in cold-stored banana fruit.

    PubMed

    Wang, Yansheng; Luo, Zisheng; Mao, Linchun; Ying, Tiejin

    2016-04-15

    Effect of exogenous nitric oxide (NO) on polyamines (PAs) catabolism, γ-aminobutyric acid (GABA) shunt, proline accumulation and chilling injury of banana fruit under cold storage was investigated. Banana fruit treated with NO sustained lower chilling injury index than the control. Notably elevated nitric oxide synthetase activity and endogenous NO level were observed in NO-treated banana fruit. PAs contents in treated fruit were significantly higher than control fruit, due to the elevated activities of arginine decarboxylase and ornithine decarboxylase. NO treatment increased the activities of diamine oxidase, polyamine oxidase and glutamate decarboxylase, while reduced GABA transaminase activity to lower levels compared with control fruit, which resulted the accumulation of GABA. Besides, NO treatment upregulated proline content and significantly enhanced the ornithine aminotransferase activity. These results indicated that the chilling tolerance induced by NO treatment might be ascribed to the enhanced catabolism of PAs, GABA and proline.

  17. Influence of GABA and GABA-producing Lactobacillus brevis DPC 6108 on the development of diabetes in a streptozotocin rat model.

    PubMed

    Marques, T M; Patterson, E; Wall, R; O'Sullivan, O; Fitzgerald, G F; Cotter, P D; Dinan, T G; Cryan, J F; Ross, R P; Stanton, C

    2016-06-01

    The aim of this study was to investigate if dietary administration of γ-aminobutyric acid (GABA)-producing Lactobacillus brevis DPC 6108 and pure GABA exert protective effects against the development of diabetes in streptozotocin (STZ)-induced diabetic Sprague Dawley rats. In a first experiment, healthy rats were divided in 3 groups (n=10/group) receiving placebo, 2.6 mg/kg body weight (bw) pure GABA or L. brevis DPC 6108 (~10(9)microorganisms). In a second experiment, rats (n=15/group) were randomised to five groups and four of these received an injection of STZ to induce type 1 diabetes. Diabetic and non-diabetic controls received placebo [4% (w/v) yeast extract in dH2O], while the other three diabetic groups received one of the following dietary supplements: 2.6 mg/kg bw GABA (low GABA), 200 mg/kg bw GABA (high GABA) or ~10(9) L. brevis DPC 6108. L. brevis DPC 6108 supplementation was associated with increased serum insulin levels (P<0.05), but did not alter other metabolic markers in healthy rats. Diabetes induced by STZ injection decreased body weight (P<0.05), increased intestinal length (P<0.05) and stimulated water and food intake. Insulin was decreased (P<0.05), whereas glucose was increased (P<0.001) in all diabetic groups, compared with non-diabetic controls. A decrease (P<0.01) in glucose levels was observed in diabetic rats receiving L. brevis DPC 6108, compared with diabetic-controls. Both the composition and diversity of the intestinal microbiota were affected by diabetes. Microbial diversity in diabetic rats supplemented with low GABA was not reduced (P>0.05), compared with non-diabetic controls while all other diabetic groups displayed reduced diversity (P<0.05). L. brevis DPC 6108 attenuated hyperglycaemia induced by diabetes but additional studies are needed to understand the mechanisms involved in this reduction. PMID:27013462

  18. The Relation Between GABA and L-Arginine Levels With Some Stroke Risk Factors in Acute Ischemic Stroke Patients

    PubMed Central

    Hosinian, Mohsen; Qujeq, Durdi; Ahmadi Ahangar, Alijan

    2016-01-01

    Changes in extra and intracellular neurotransmitter amino acids concentration in the early stage of acute cerebral ischemia have been reported. In this the study, serum level of gamma aminobutyric acid (GABA) and L-Arginine in acute ischemic stroke patients was assessed. 60 patients with acute ischemic stroke and sixthy healthy volunteers as a control group were assessed. Serum GABA was measured with modified enzymatic method and serum L- Arginine was measured by modified Sakaguchi method. Serum GABA level in stroke cases was lower than that of the control group. There was no relationship between GABA level and age or gender. Also, no significant correlation was observed between GABA levels with ischemic stroke risk factors such as smoking, diabetes mellitus, and hypertension. Serum L- Arginine level in patients was slightly increased in comparison with control group. There was a positive relationship between serum L- Arginine level and acute ischemic stroke risk factors. Serum GABA level was reduced in patients and had no correlation with acute ischemic stroke risk factors. PMID:27478806

  19. Acute increases in synaptic GABA detectable in the living human brain: a [¹¹C]Ro15-4513 PET study.

    PubMed

    Stokes, Paul R A; Myers, Jim F; Kalk, Nicola J; Watson, Ben J; Erritzoe, David; Wilson, Sue J; Cunningham, Vincent J; Riano Barros, Daniela; Hammers, Alexander; Turkheimer, Federico E; Nutt, David J; Lingford-Hughes, Anne R

    2014-10-01

    The inhibitory γ-aminobutyric acid (GABA) neurotransmitter system is associated with the regulation of normal cognitive functions and dysregulation has been reported in a number of neuropsychiatric disorders including anxiety disorders, schizophrenia and addictions. Investigating the role of GABA in both health and disease has been constrained by difficulties in measuring acute changes in synaptic GABA using neurochemical imaging. The aim of this study was to investigate whether acute increases in synaptic GABA are detectable in the living human brain using the inverse agonist GABA-benzodiazepine receptor (GABA-BZR) positron emission tomography (PET) tracer, [(11)C]Ro15-4513. We examined the effect of 15 mg oral tiagabine, which increases synaptic GABA by inhibiting the GAT1 GABA uptake transporter, on [(11)C]Ro15-4513 binding in 12 male participants using a paired, double blind, placebo-controlled protocol. Spectral analysis was used to examine synaptic α1 and extrasynaptic α5 GABA-BZR subtype availability in brain regions with high levels of [(11)C]Ro15-4513 binding. We also examined the test-retest reliability of α1 and a5-specific [(11)C]Ro15-4513 binding in a separate cohort of 4 participants using the same spectral analysis protocol. Tiagabine administration produced significant reductions in hippocampal, parahippocampal, amygdala and anterior cingulate synaptic α1 [(11)C]Ro15-4513 binding, and a trend significance reduction in the nucleus accumbens. These reductions were greater than test-retest reliability, indicating that they are not the result of chance observations. Our results suggest that acute increases in endogenous synaptic GABA are detectable in the living human brain using [(11)C]Ro15-4513 PET. These findings have potentially major implications for the investigation of GABA function in brain disorders and in the development of new treatments targeting this neurotransmitter system. PMID:24844747

  20. Self-enhancement of GABA in rice bran using various stress treatments.

    PubMed

    Kim, Hyun Soo; Lee, Eun Jung; Lim, Seung-Taik; Han, Jung-Ah

    2015-04-01

    Gamma-aminobutyric acid (GABA) may be synthesized in plant tissues when the organism is under stressful conditions. Rice bran byproduct obtained from the milling of brown rice was treated under anaerobic storage with nitrogen at different temperatures (20-60 °C) and moisture contents (10-50%) up to 12h. For the GABA synthesis, the storage at 30% moisture content and 40 °C appeared optimal. Utilisation of an electrolyzed oxidizing water (EOW, pH 3.3) for moisture adjustment and addition of glutamic acid increased the GABA content in rice bran. The maximum GABA content in rice bran (523 mg/100g) could be achieved by the anaerobic storage at 30% EOW for 5h at 40 °C after an addition of glutamic acid (5mM). This amount was approximately 17 times higher than that in the control (30 mg/100g). The use of EOW also prevented bacterial growth by decreasing the colony counts almost by half.

  1. Inhibition of GABA synthesis in the prefrontal cortex increases locomotor activity but does not affect attention in the 5-choice serial reaction time task.

    PubMed

    Asinof, Samuel K; Paine, Tracie A

    2013-02-01

    Attention deficits are a core cognitive symptom of schizophrenia; the neuropathology underlying these deficits is not known. Attention is regulated, at least in part, by the prefrontal cortex (PFC), a brain area in which pathology of γ-aminobutyric acid (GABA) neurons has been consistently observed in post-mortem analysis of the brains of people with schizophrenia. Specifically, expression of the 67-kD isoform of the GABA synthesis enzyme glutamic acid decarboxylase (GAD67) is reduced in parvalbumin-containing fast-spiking GABA interneurons. Thus it is hypothesized that reduced cortical GABA synthesis and release may contribute to the attention deficits in schizophrenia. Here the effect of reducing cortical GABA synthesis with l-allylglycine (LAG) on attention was tested using three different versions of the 5-choice serial reaction time task (5CSRTT). Because 5CSRTT performance can be affected by locomotor activity, we also measured this behavior in an open field. Finally, the expression of Fos protein was used as an indirect measure of reduced GABA synthesis. Intra-cortical LAG (10 μg/0.5 μl/side) infusions increased Fos expression and resulted in hyperactivity in the open field. Intra-cortical LAG infusions did not affect attention in any version of the 5CSRTT. These results suggest that a general decrease in GABA synthesis is not sufficient to cause attention deficits. It remains to be tested whether a selective decrease in GABA synthesis in parvalbumin-containing GABA neurons could cause attention deficits. Decreased cortical GABA synthesis did increase locomotor activity; this may reflect the positive symptoms of schizophrenia.

  2. Changes in vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide and neuropeptide Y-ergic structures of the enteric nervous system in the carcinoma of the human large intestine.

    PubMed

    Godlewski, Janusz; Łakomy, Ireneusz Mirosław

    2010-01-01

    This investigation was aimed at immunohistochemical analysis of potential changes in the enteric nervous system caused by cancer of the large intestine. In this purpose, neurons and nerve fibers of intestinal plexuses containing neuropeptides: vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP) and neuropeptide Y (NPY), in pathologically changed part of the large intestine were microscpically observed and compared. Samples were taken from patients operated due to cancer of the sigmoid colon and rectum. The number of neurons and density of nerve fibres containing neuropeptides found in sections with cancer tissues were compared to those observed in sections from the uninvolved intestinal wall. Changes relating to reductions in the number of NPY-ergic neurons and density of nerve fibres in submucous and myenteric plexuses in the sections with cancer tissues (pathological sections) were statistically significant. A statistically similar presence of VIP-ergic and PACAP-ergic neurons in the submucosal and myenteric plexuses was observed in both the pathological and control sections. On the other hand, in the pathological sections, VIP-ergic nerve fibres in the myenteric plexuses and PACAP-ergic nerve fibres in the submucosal and myenteric plexuses were found to be less dense. Analysis revealed changes in pathologically affected part of the large intestine may caused disruption of proper intestinal function. Observed changes in the neural elements which are responsible for relaxation of the intestine may suggest dysfunction in the innervation of this part of the colon.

  3. Succinic semialdehyde as a substrate for the formation of gamma-aminobutyric acid.

    PubMed

    van Bemmelen, F J; Schouten, M J; Fekkes, D; Bruinvels, J

    1985-11-01

    The conversion of succinic semialdehyde into gamma-aminobutyric acid (GABA) by GABA-transaminase was measured in rat brain homogenate in the presence of different concentrations of the cosubstrate glutamate. The calculated kinetic parameters of succinic semialdehyde for GABA-transaminase were a limiting Km value of 168 microM and a limiting Vmax value of 38 mumol g-1 h-1. Combination with previously obtained data for the conversion of GABA into succinic semialdehyde revealed a kEq value of 0.04, indicating that equilibrium of GABA-transaminase is biased toward the formation of GABA. The increased formation of GABA in the presence of succinic semialdehyde was not due to an increased conversion of glutamate into GABA by glutamic acid decarboxylase. Therefore these results indicate that succinic semialdehyde can act as a precursor for GABA synthesis.

  4. Valerian inhibits rat hepatocarcinogenesis by activating GABA(A) receptor-mediated signaling.

    PubMed

    Kakehashi, Anna; Kato, Ayumi; Ishii, Naomi; Wei, Min; Morimura, Keiichirou; Fukushima, Shoji; Wanibuchi, Hideki

    2014-01-01

    Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the γ-aminobutyric acid (GABA) A receptor (GABA(A)R) system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(A)R agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis) at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN). Formation of glutathione S-transferase placental form positive (GST-P(+)) foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2'-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P(+) foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21(Waf1/Cip1), p53 and Bax mRNA expression. Interestingly, expression of the GABA(A)R alpha 1 subunit was observed in GST-P(+) foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P(+) foci by activating GABA(A)R-mediated signaling. PMID:25419570

  5. Ventral tegmental area GABA projections pause accumbal cholinergic interneurons to enhance associative learning.

    PubMed

    Brown, Matthew T C; Tan, Kelly R; O'Connor, Eoin C; Nikonenko, Irina; Muller, Dominique; Lüscher, Christian

    2012-12-20

    The ventral tegmental area (VTA) and nucleus accumbens (NAc) are essential for learning about environmental stimuli associated with motivationally relevant outcomes. The task of signalling such events, both rewarding and aversive, from the VTA to the NAc has largely been ascribed to dopamine neurons. The VTA also contains GABA (γ-aminobutyric acid)-releasing neurons, which provide local inhibition and also project to the NAc. However, the cellular targets and functional importance of this long-range inhibitory projection have not been ascertained. Here we show that GABA-releasing neurons of the VTA that project to the NAc (VTA GABA projection neurons) inhibit accumbal cholinergic interneurons (CINs) to enhance stimulus-outcome learning. Combining optogenetics with structural imaging and electrophysiology, we found that VTA GABA projection neurons selectively target NAc CINs, forming multiple symmetrical synaptic contacts that generated inhibitory postsynaptic currents. This is remarkable considering that CINs represent a very small population of all accumbal neurons, and provide the primary source of cholinergic tone in the NAc. Brief activation of this projection was sufficient to halt the spontaneous activity of NAc CINs, resembling the pause recorded in animals learning stimulus-outcome associations. Indeed, we found that forcing CINs to pause in behaving mice enhanced discrimination of a motivationally important stimulus that had been associated with an aversive outcome. Our results demonstrate that VTA GABA projection neurons, through their selective targeting of accumbal CINs, provide a novel route through which the VTA communicates saliency to the NAc. VTA GABA projection neurons thus emerge as orchestrators of dopaminergic and cholinergic modulation in the NAc.

  6. Decreased GABA receptor in the cerebral cortex of epileptic rats: effect of Bacopa monnieri and Bacoside-A

    PubMed Central

    2012-01-01

    Abstact Background Gamma amino butyric acid (GABA), the principal inhibitory neurotransmitter in the cerebral cortex, maintains the inhibitory tones that counter balances neuronal excitation. When this balance is perturbed, seizures may ensue. Methods In the present study, alterations of the general GABA, GABAA and GABAB receptors in the cerebral cortex of the epileptic rat and the therapeutic application of Bacopa monnieri were investigated. Results Scatchard analysis of [3H]GABA, [3H]bicuculline and [3H]baclofen in the cerebral cortex of the epileptic rat showed significant decrease in Bmax (P < 0.001) compared to control. Real Time PCR amplification of GABA receptor subunits such as GABAAά1, GABAAγ, GABAAδ, GABAB and GAD where down regulated (P < 0.001) in epileptic rats. GABAAά5 subunit and Cyclic AMP responsible element binding protein were up regulated. Confocal imaging study confirmed the decreased GABA receptors in epileptic rats. Epileptic rats have deficit in radial arm and Y maze performance. Conclusions Bacopa monnieri and Bacoside-A treatment reverses epilepsy associated changes to near control suggesting that decreased GABA receptors in the cerebral cortex have an important role in epileptic occurrence; Bacopa monnieri and Bacoside-A have therapeutic application in epilepsy management. PMID:22364254

  7. The transmembrane sodium gradient influences ambient GABA concentration by altering the equilibrium of GABA transporters.

    PubMed

    Wu, Yuanming; Wang, Wengang; Richerson, George B

    2006-11-01

    Tonic inhibition is widely believed to be caused solely by "spillover" of GABA that escapes the synaptic cleft and activates extrasynaptic GABA(A) receptors. However, an exclusively vesicular source is not consistent with the observation that tonic inhibition can still occur after blocking vesicular release. Here, we made patch-clamp recordings from neurons in rat hippocampal cultures and measured the tonic current that was blocked by bicuculline or gabazine. During perforated patch recordings, the tonic GABA current was decreased by the GAT1 antagonist SKF-89976a. Zero calcium solution did not change the amount of tonic current, despite a large reduction in vesicular GABA release. Perturbations that would be expected to alter the transmembrane sodium gradient influenced the tonic current. For example, in zero calcium Ringer, TTX (which can decrease cytosolic [Na(+)]) reduced tonic current, whereas veratridine (which can increase cytosolic [Na(+)]) increased tonic current. Likewise, removal of extracellular sodium led to a large increase in tonic current. The increases in tonic current induced by veratridine and sodium removal were completely blocked by SKF89976a. When these experiments were repeated in hippocampal slices, similar results were obtained except that a GAT1- and GAT3-independent nonvesicular source(s) of GABA was found to contribute to the tonic current. We conclude that multiple sources can contribute to ambient GABA, including spillover and GAT1 reversal. The source of GABA release may be conceptually less important in determining the amount of tonic inhibition than the factors that control the equilibrium of GABA transporters.

  8. Cardiovascular and behavioral effects produced by administration of liposome-entrapped GABA into the rat central nervous system.

    PubMed

    Vaz, G C; Bahia, A P C O; de Figueiredo Müller-Ribeiro, F C; Xavier, C H; Patel, K P; Santos, R A S; Moreira, F A; Frézard, F; Fontes, M A P

    2015-01-29

    Liposomes are nanosystems that allow a sustained release of entrapped substances. Gamma-aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter of the central nervous system (CNS). We developed a liposomal formulation of GABA for application in long-term CNS functional studies. Two days after liposome-entrapped GABA was injected intracerebroventricularly (ICV), Wistar rats were submitted to the following evaluations: (1) changes in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) to ICV injection of bicuculline methiodide (BMI) in anesthetized rats; (2) changes in cardiovascular reactivity to air jet stress in conscious rats; and (3) anxiety-like behavior in conscious rats. GABA and saline-containing pegylated liposomes were prepared with a mean diameter of 200 nm. Rats with implanted cannulas targeted to lateral cerebral ventricle (n = 5-8/group) received either GABA solution (GS), empty liposomes (EL) or GABA-containing liposomes (GL). Following (48 h) central microinjection (2 μL, 0.09 M and 99 g/L) of liposomes, animals were submitted to the different protocols. Animals that received GL demonstrated attenuated response of RSNA to BMI microinjection (GS 48 ± 9, EL 43 ± 9, GL 11 ± 8%; P < 0.05), blunted tachycardia in the stress trial (ΔHR: GS 115 ± 14, EL 117 ± 10, GL 74 ± 9 bpm; P<0.05) and spent more time in the open arms of elevated plus maze (EL 6 ± 2 vs. GL 18 ± 5%; P = 0.028) compared with GS and EL groups. These results indicate that liposome-entrapped GABA can be a potential tool for exploring the chronic effects of GABA in specific regions and pathways of the central nervous system.

  9. Effects of benzodiazepines and non-benzodiazepine compounds on the GABA-induced response in frog isolated sensory neurones.

    PubMed Central

    Yakushiji, T.; Fukuda, T.; Oyama, Y.; Akaike, N.

    1989-01-01

    1. The effects of benzodiazepines and non-benzodiazepine compounds on the gamma-aminobutyric acid (GABA)-induced chloride current (ICl) were studied in frog isolated sensory neurones by use of a concentration-jump (termed 'concentration-clamp') technique, under single-electrode voltage-clamp conditions. The drugs used were classified into four categories as follows: full benzodiazepine receptor agonists (diazepam, clonazepam, nitrazepam, midazolam, clotiazepam and etizolam), partial agonists (CL 218,872, Ro 16-6028, Ro 17-1812 and Ro 23-0364), inverse agonists (Ro 15-3505, FG 7142 and beta-CCE) and a benzodiazepine receptor antagonist, Ro 15-1788 (flumazenil). 2. All full agonists at concentrations of 3 x 10(-6) M or less increased dose-dependently the peak amplitude of ICl elicited by 3 x 10(-6) M GABA to twice to three times larger than the control. However, no further augmentation of the GABA response was observed at concentrations of 1 x 10(-5) M or higher. Partial agonists also showed a dose-dependent augmentation of the GABA response at concentrations ranging from 3 x 10(-8) M to 3 x 10(-5) M, but their efficacies of augmentation of the GABA response were only about half or less of those of full agonists. Of the inverse agonists, beta-CCE had a unique dose-dependent effect on the GABA response. Beta-CCE reduced dose-dependently the GABA response at concentrations of less than 3 x 10(-6) M, but augmented it at concentrations of 3 x 10(-5) M and 6 x 10(-5) M. The inverse agonists reduced dose-dependently the GABA response.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2574062

  10. Low visual cortex GABA levels in hepatic encephalopathy: links to blood ammonia, critical flicker frequency, and brain osmolytes.

    PubMed

    Oeltzschner, Georg; Butz, Markus; Baumgarten, Thomas J; Hoogenboom, Nienke; Wittsack, Hans-Jörg; Schnitzler, Alfons

    2015-12-01

    The pathogenesis of hepatic encephalopathy (HE) is not fully understood yet. Hyperammonemia due to liver failure and subsequent disturbance of cerebral osmolytic balance is thought to play a pivotal role in the emergence of HE. The aim of this in-vivo MR spectroscopy study was to investigate the levels of γ-aminobutyric acid (GABA) and its correlations with clinical symptoms of HE, blood ammonia, critical flicker frequency, and osmolytic levels. Thirty patients with minimal HE or HE1 and 16 age-matched healthy controls underwent graduation of HE according to the West-Haven criteria and including the critical flicker frequency (CFF), neuropsychometric testing and blood testing. Edited proton magnetic resonance spectroscopy ((1)H MRS) was used to non-invasively measure the concentrations of GABA, glutamate (Glu), glutamine (Gln), and myo-inositol (mI) - all normalized to creatine (Cr) - in visual and sensorimotor cortex. GABA/Cr in the visual area was significantly decreased in mHE and HE1 patients and correlated both to the CFF (r = 0.401, P = 0.013) and blood ammonia levels (r = -0.434, P = 0.006). Visual GABA/Cr was also strongly linked to mI/Cr (r = 0.720, P < 0.001) and Gln/Cr (r = -0.699, P < 0.001). No group differences or correlations were found for GABA/Cr in the sensorimotor area. Hepatic encephalopathy is associated with a regional specific decrease of GABA levels in the visual cortex, while no changes were revealed for the sensorimotor cortex. Correlations of visual GABA/Cr with CFF, blood ammonia, and osmolytic regulators mI and Gln indicate that decreased visual GABA levels might contribute to HE symptoms, most likely as a consequence of hyperammonemia.

  11. Menthol shares general anesthetic activity and sites of action on the GABA(A) receptor with the intravenous agent, propofol.

    PubMed

    Watt, Erin E; Betts, Brooke A; Kotey, Francesca O; Humbert, Danielle J; Griffith, Theanne N; Kelly, Elizabeth W; Veneskey, Kelley C; Gill, Nikhila; Rowan, Kathleen C; Jenkins, Andrew; Hall, Adam C

    2008-08-20

    Menthol and related compounds were investigated for modulation of recombinant human gamma-aminobutyric acid type A (GABA(A), alpha(1)beta(2)gamma(2s)) receptor currents expressed in Xenopus oocytes. Sub-maximal (EC(20)) GABA currents were typically enhanced by co-applications of 3-300 microM (+)-menthol (e.g. by approximately 2-fold at 50 microM) > isopulegol > isomenthol> alpha-terpineol > cyclohexanol. We studied menthol's actions on GABA(A) receptors compared to sedatives (benzodiazepines) and intravenous anesthetics (barbiturates, steroids, etomidate and propofol). Flumazenil (a benzodiazepine antagonist) did not inhibit menthol enhancements while currents directly activated by 50 microM propofol were significantly inhibited (by 26+/-3%) by 50 microM (+)-menthol. GABA(A) receptors containing beta(2) subunits with either a point mutation in a methionine residue to a tryptophan at the 286 position (in transmembrane domain 3, TM-3) or a tyrosine to a tryptophan at the 444 position (TM-4) are insensitive to modulation by propofol. Enhancements of GABA EC(20) currents by menthol were equally abolished in GABA(A) alpha(1)beta(2)(M286W)gamma(2s) and alpha(1)beta(2)(Y444W)gamma(2s) receptors while positive modulations by benzodiazepines, barbiturates and steroids were unaffected. Menthol may therefore exert its actions on GABA(A) receptors via sites distinct from benzodiazepines, steroids and barbiturates, and via sites important for modulation by propofol. Finally, using an in vivo tadpole assay, addition of (+)-menthol resulted in a loss of righting reflex with an EC(50) of 23.5+/-4.7 microM (approximately10-fold less potent anesthesia than propofol). Thus, menthol and analogs share general anesthetic action with propofol, possibly via action at similar sites on the GABA(A) receptor. PMID:18593637

  12. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation.

    PubMed

    Qin, Pengmin; Duncan, Niall W; Wiebking, Christine; Gravel, Paul; Lyttelton, Oliver; Hayes, Dave J; Verhaeghe, Jeroen; Kostikov, Alexey; Schirrmacher, Ralf; Reader, Andrew J; Northoff, Georg

    2012-01-01

    Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  13. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA

    PubMed Central

    Nesterkina, Mariia; Kravchenko, Iryna

    2016-01-01

    Novel esters of γ-aminobutyric acid (GABA) with monocyclic terpenes were synthesized via Steglich esterification and characterized by 1H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate acute pain more than the reference drug benzocaine after their topical application. GABA esters of l-menthol and thymol were also shown to exceed the reference drug ibuprofen in their ability to decrease the inflammatory state induced by intraplantar injection of the TRPA1 activator AITC. The present findings indicate that GABA esters of carvacrol and guaiacol are not a classical prodrug and possess their own pharmacological activity. Prolonged antiseizure action of the ester based on the amino acid and guaiacol (200 mg/kg) was revealed at 24 h after oral administration. Furthermore, orally co-administered gidazepam (1 mg/kg) and GABA esters of l-menthol, thymol and carvacrol produce synergistic seizure prevention effects. PMID:27304960

  14. Effects of increasing brain GABA on the meal patterns of genetically obese vs. lean Zucker rats.

    PubMed

    Coscina, D V; Castonguay, T W; Stern, J S

    1992-06-01

    To explore recent suggestions that genetically obese Zucker rats show less anorexia when brain gamma-aminobutyric acid (GABA) is elevated, obese vs. lean littermates received 100, 50 and 0 micrograms of the GABA-transaminase inhibitor, ethanolamine-O-sulfate (EOS), intra-cisternally in a longitudinal design where their feeding patterns were monitored 24 h daily. Obese rats were refractory to EOS-induced anorexia as evidenced by less suppression of daily food intake and fewer alterations to both meal size and meal frequency, particularly in the night. This effect was not due to an inability of EOS to increase brain GABA since equivalent, specific dose-dependent increments were seen in the brains of separate obese vs. lean rats after analysis of endogenous GABA and seven other amino acids. An unexpected finding was elevated levels of brain taurine for obese rats regardless of EOS dosage, implying a hitherto unknown neurochemical trait whose potential significance is unclear. The primary data obtained provide further support for recent hypotheses that obese Zucker rats possess altered brain GABAergic mechanisms that may serve as one contributor to their over-eating.

  15. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA.

    PubMed

    Nesterkina, Mariia; Kravchenko, Iryna

    2016-06-13

    Novel esters of γ-aminobutyric acid (GABA) with monocyclic terpenes were synthesized via Steglich esterification and characterized by ¹H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate acute pain more than the reference drug benzocaine after their topical application. GABA esters of l-menthol and thymol were also shown to exceed the reference drug ibuprofen in their ability to decrease the inflammatory state induced by intraplantar injection of the TRPA1 activator AITC. The present findings indicate that GABA esters of carvacrol and guaiacol are not a classical prodrug and possess their own pharmacological activity. Prolonged antiseizure action of the ester based on the amino acid and guaiacol (200 mg/kg) was revealed at 24 h after oral administration. Furthermore, orally co-administered gidazepam (1 mg/kg) and GABA esters of l-menthol, thymol and carvacrol produce synergistic seizure prevention effects.

  16. Synthesis and Pharmacological Properties of Novel Esters Based on Monocyclic Terpenes and GABA.

    PubMed

    Nesterkina, Mariia; Kravchenko, Iryna

    2016-01-01

    Novel esters of γ-aminobutyric acid (GABA) with monocyclic terpenes were synthesized via Steglich esterification and characterized by ¹H-NMR, IR and mass spectral studies. Their anticonvulsant, analgesic and anti-inflammatory activities were evaluated by a PTZ-induced convulsion model, AITC-induced hyperalgesia and AITC-induced paw edema, respectively. All studied esters, as well as their parent terpenes, were found to produce antinociceptive effects in the AITC-induced model and attenuate acute pain more than the reference drug benzocaine after their topical application. GABA esters of l-menthol and thymol were also shown to exceed the reference drug ibuprofen in their ability to decrease the inflammatory state induced by intraplantar injection of the TRPA1 activator AITC. The present findings indicate that GABA esters of carvacrol and guaiacol are not a classical prodrug and possess their own pharmacological activity. Prolonged antiseizure action of the ester based on the amino acid and guaiacol (200 mg/kg) was revealed at 24 h after oral administration. Furthermore, orally co-administered gidazepam (1 mg/kg) and GABA esters of l-menthol, thymol and carvacrol produce synergistic seizure prevention effects. PMID:27304960

  17. Distribution and ultrastructure of neurons in opossum piriform cortex displaying immunoreactivity to GABA and GAD and high-affinity tritiated GABA uptake

    SciTech Connect

    Haberly, L.B.; Hansen, D.J.; Feig, S.L.; Presto, S.

    1987-12-08

    GABAergic neurons have been identified in the piriform cortex of the opossum at light and electron microscopic levels by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase and by autoradiographic visualization of high-affinity /sup 3/H-GABA uptake. Four major neuron populations have been distinguished on the basis of soma size, shape, and segregation at specific depths and locations: large horizontal cells in layer Ia of the anterior piriform cortex, small globular cells with thin dendrites concentrated in layers Ib and II of the posterior piriform cortex, and multipolar and fusiform cells concentrated in the deep part of layer III in anterior and posterior parts of the piriform cortex and the subjacent endopiriform nucleus. All four populations were well visualized with both antisera, but the large layer Ia horizontal cells displayed only very light /sup 3/H-GABA uptake, thus suggesting a lack of local axon collaterals or lack of high-affinity GABA uptake sites. The large, ultrastructurally distinctive somata of layer Ia horizontal cells receive a very small number of symmetrical synapses; the thin, axonlike dendrites of small globular cells are exclusively postsynaptic and receive large numbers of both symmetrical and asymmetrical synapses, in contrast to somata which receive a small number of both types; and the deep multipolar and fusiform cells receive a highly variable number of symmetrical and asymmetrical synapses on somata and proximal dendrites. Labeled puncta of axon terminal dimensions were found in large numbers in the neuropil surrounding pyramidal cell somata in layer II and in the endopiriform nucleus. Moderately large numbers of labeled puncta were found in layer I at the depth of pyramidal cell apical dendrites with greater numbers in layer Ia at the depth of distal apical segments than in layer Ib.

  18. Molecular cloning and expression of a GABA receptor subunit from the crayfish Procambarus clarkii.

    PubMed

    Jiménez-Vázquez, Eric N; Díaz-Velásquez, Clara E; Uribe, R M; Arias, Juan M; García, Ubaldo

    2016-02-01

    Molecular cloning has introduced an unexpected, large diversity of neurotransmitter hetero- oligomeric receptors. Extensive research on the molecular structure of the γ-aminobutyric acid receptor (GABAR) has been of great significance for understanding how the nervous system works in both vertebrates and invertebrates. However, only two examples of functional homo-oligomeric GABA-activated Cl(-) channels have been reported. In the vertebrate retina, the GABAρ1 subunit of various species forms homo-oligomeric receptors; in invertebrates, a cDNA encoding a functional GABA-activated Cl(-) channel has been isolated from a Drosophila melanogaster head cDNA library. When expressed in Xenopus laevis oocytes, these subunits function efficiently as a homo-oligomeric complex. To investigate the structure-function of GABA channels from the crayfish Procambarus clarkii, we cloned a subunit and expressed it in human embryonic kidney cells. Electrophysiological recordings show that this subunit forms a homo-oligomeric ionotropic GABAR that gates a bicuculline-insensitive Cl(-) current. The order of potency of the agonists was GABA > trans-4-amino-crotonic acid = cis-4-aminocrotonic acid > muscimol. These data support the notion that X-organ sinus gland neurons express at least two GABA subunits responsible for the formation of hetero-oligomeric and homo-oligomeric receptors. In addition, by in situ hybridization studies we demonstrate that most X-organ neurons from crayfish eyestalk express the isolated pcGABAA β subunit. This study increases the knowledge of the genetics of the crayfish, furthers the understanding of this important neurotransmitter receptor family, and provides insight into the evolution of these genes among vertebrates and invertebrates.

  19. Effects of ABA and CaCl₂ on GABA accumulation in fava bean germinating under hypoxia-NaCl stress.

    PubMed

    Yang, Runqiang; Hui, Qianru; Gu, Zhenxin

    2016-01-01

    Effects of exogenous abscisic acid (ABA) and CaCl2 on γ-aminobutyric acid (GABA) accumulation of germinated fava bean under hypoxia-NaCl stress were investigated. Exogenous ABA resulted in the enhancement of glutamate decarboxylase (GAD) and diamine oxidase (DAO) activity as well as GABA content in cotyledon and shoot. CaCl2 increased both enzyme activities in shoot and GABA content in cotyledon and shoot. ABA downregulated GAD expression in cotyledon and radicle, while upregulated that in shoot; it also upregulated DAO expression in each organ. CaCl2 upregulated GAD expression in cotyledon, while downregulated that in radicle. However, it upregulated DAO expression in shoot, downregulated that in radicle. ABA inhibitor fluridon and ethylenediaminetetraacetic acid inhibited GAD and DAO activities significantly so that inhibited GABA accumulation through reducing ABA biosynthesis and chelating Ca(2+), respectively. However, they upregulated GAD and DAO expression in varying degrees. These results indicate that ABA and Ca(2+) participate in GABA biosynthesis in fava bean during germination under hypoxia-NaCl stress.

  20. Effects of ABA and CaCl₂ on GABA accumulation in fava bean germinating under hypoxia-NaCl stress.

    PubMed

    Yang, Runqiang; Hui, Qianru; Gu, Zhenxin

    2016-01-01

    Effects of exogenous abscisic acid (ABA) and CaCl2 on γ-aminobutyric acid (GABA) accumulation of germinated fava bean under hypoxia-NaCl stress were investigated. Exogenous ABA resulted in the enhancement of glutamate decarboxylase (GAD) and diamine oxidase (DAO) activity as well as GABA content in cotyledon and shoot. CaCl2 increased both enzyme activities in shoot and GABA content in cotyledon and shoot. ABA downregulated GAD expression in cotyledon and radicle, while upregulated that in shoot; it also upregulated DAO expression in each organ. CaCl2 upregulated GAD expression in cotyledon, while downregulated that in radicle. However, it upregulated DAO expression in shoot, downregulated that in radicle. ABA inhibitor fluridon and ethylenediaminetetraacetic acid inhibited GAD and DAO activities significantly so that inhibited GABA accumulation through reducing ABA biosynthesis and chelating Ca(2+), respectively. However, they upregulated GAD and DAO expression in varying degrees. These results indicate that ABA and Ca(2+) participate in GABA biosynthesis in fava bean during germination under hypoxia-NaCl stress. PMID:26644273

  1. Double isotopic method using dansyl chloride for the determination of GABA in rat C6 astrocytoma cell cultures

    SciTech Connect

    Kohl, R.L.; Quay, W.B.; Perez-Polo, J.R.

    1986-01-01

    Methods are described for the quantitative measurement of GABA in culture. The method can be adapted to any amino acid or dansyl-chloride-reactive species. The sensitivity and selectivity of the procedure result from the double isotopic design in which (/sup 14/C)-labeled internal standard was added to the samples before reaction with (3M)-labeled dansyl chloride. Values obtained by ion-exchange amino acid analysis of cultures agree closely with the values obtained by the double isotopic method. This method is sensitive enough to measure GABA intracellularly and the condition medium.

  2. Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the meninges and the choroid plexus: implications for non-neuronal sources for GABA in the developing mouse brain.

    PubMed

    Tochitani, Shiro; Kondo, Shigeaki

    2013-01-01

    Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11-E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development.

  3. GABA{sub A} receptor open-state conformation determines non-competitive antagonist binding

    SciTech Connect

    Chen Ligong; Xue Ling; Giacomini, Kathleen M.; Casida, John E.

    2011-02-01

    The {gamma}-aminobutyric acid (GABA) type A receptor (GABA{sub A}R) is one of the most important targets for insecticide action. The human recombinant {beta}3 homomer is the best available model for this binding site and 4-n-[{sup 3}H]propyl-4'-ethynylbicycloorthobenzoate ([{sup 3}H]EBOB) is the preferred non-competitive antagonist (NCA) radioligand. The uniquely high sensitivity of the {beta}3 homomer relative to the much-less-active but structurally very-similar {beta}1 homomer provides an ideal comparison to elucidate structural and functional features important for NCA binding. The {beta}1 and {beta}3 subunits were compared using chimeragenesis and mutagenesis and various combinations with the {alpha}1 subunit and modulators. Chimera {beta}3/{beta}1 with the {beta}3 subunit extracellular domain and the {beta}1 subunit transmembrane helices retained the high [{sup 3}H]EBOB binding level of the {beta}3 homomer while chimera {beta}1/{beta}3 with the {beta}1 subunit extracellular domain and the {beta}3 subunit transmembrane helices had low binding activity similar to the {beta}1 homomer. GABA at 3 {mu}M stimulated heteromers {alpha}1{beta}1 and {alpha}1{beta}3 binding levels more than 2-fold by increasing the open probability of the channel. Addition of the {alpha}1 subunit rescued the inactive {beta}1/{beta}3 chimera close to wildtype {alpha}1{beta}1 activity. EBOB binding was significantly altered by mutations {beta}1S15'N and {beta}3N15'S compared with wildtype {beta}1 and {beta}3, respectively. However, the binding activity of {alpha}1{beta}1S15'N was insensitive to GABA and {alpha}1{beta}3N15'S was stimulated much less than wildtype {alpha}1{beta}3 by GABA. The inhibitory effect of etomidate on NCA binding was reduced more than 5-fold by the mutation {beta}3N15'S. Therefore, the NCA binding site is tightly regulated by the open-state conformation that largely determines GABA{sub A} receptor sensitivity. - Graphical Abstract: Display Omitted Research Highlights

  4. Characteristics of GABA release induced by free radicals in mouse hippocampal slices.

    PubMed

    Saransaari, Pirjo; Oja, Simo S

    2008-03-01

    and S-nitroso-N-penicillamine enhanced the release. The regulation of GABA release induced by free radical production proved thus to be rather complex. Under potentially cell-damaging conditions, the potentiation of GABA release may be a mechanism to counteract hyperactivity and reduce the effects of excitatory amino acid release. On the other hand, reduction of GABA release could be harmful and contribute to excitotoxic damage and neuronal degeneration.

  5. Increased GABA concentrations in type 2 diabetes mellitus are related to lower cognitive functioning.

    PubMed

    van Bussel, Frank C G; Backes, Walter H; Hofman, Paul A M; Puts, Nicolaas A J; Edden, Richard A E; van Boxtel, Martin P J; Schram, Miranda T; Stehouwer, Coen D A; Wildberger, Joachim E; Jansen, Jacobus F A

    2016-09-01

    Type 2 diabetes mellitus is associated with accelerated cognitive decline. The underlying pathophysiological mechanisms still remain to be elucidated although it is known that insulin signaling modulates neurotransmitter activity, including inhibitory γ-aminobutyric acid (GABA) and excitatory glutamate (Glu) receptors. Therefore, we examined whether levels of GABA and Glu are related to diabetes status and cognitive performance.Forty-one participants with type 2 diabetes and 39 participants without type 2 diabetes underwent detailed cognitive assessments and 3-Tesla proton MR spectroscopy. The associations of neurotransmitters with type 2 diabetes and cognitive performance were examined using multivariate regression analyses controlling for age, sex, education, BMI, and percentage gray/white matter ratio in spectroscopic voxel.Analysis revealed higher GABA+ levels in participants with type 2 diabetes, in participants with higher fasting blood glucose levels and in participants with higher HbA1c levels, and higher GABA+ levels in participants with both high HbA1c levels and less cognitive performance.To conclude, participants with type 2 diabetes have alterations in the GABAergic neurotransmitter system, which are related to lower cognitive functioning, and hint at the involvement of an underlying metabolic mechanism. PMID:27603392

  6. A novel GABA-mediated corticotropin-releasing hormone secretory mechanism in the median eminence

    PubMed Central

    Kakizawa, Keisuke; Watanabe, Miho; Mutoh, Hiroki; Okawa, Yuta; Yamashita, Miho; Yanagawa, Yuchio; Itoi, Keiichi; Suda, Takafumi; Oki, Yutaka; Fukuda, Atsuo

    2016-01-01

    Corticotropin-releasing hormone (CRH), which is synthesized in the paraventricular nucleus (PVN) of the hypothalamus, plays an important role in the endocrine stress response. The excitability of CRH neurons is regulated by γ-aminobutyric acid (GABA)–containing neurons projecting to the PVN. We investigated the role of GABA in the regulation of CRH release. The release of CRH was impaired, accumulating in the cell bodies of CRH neurons in heterozygous GAD67-GFP (green fluorescent protein) knock-in mice (GAD67+/GFP), which exhibited decreased GABA content. The GABAA receptor (GABAAR) and the Na+-K+-2Cl− cotransporter (NKCC1), but not the K+-Cl− cotransporter (KCC2), were expressed in the terminals of the CRH neurons at the median eminence (ME). In contrast, CRH neuronal somata were enriched with KCC2 but not with NKCC1. Thus, intracellular Cl− concentrations ([Cl−]i) may be increased at the terminals of CRH neurons compared with concentrations in the cell body. Moreover, GABAergic terminals projecting from the arcuate nucleus were present in close proximity to CRH-positive nerve terminals. Furthermore, a GABAAR agonist increased the intracellular calcium (Ca2+) levels in the CRH neuron terminals but decreased the Ca2+ levels in their somata. In addition, the increases in Ca2+ concentrations were prevented by an NKCC1 inhibitor. We propose a novel mechanism by which the excitatory action of GABA maintains a steady-state CRH release from axon terminals in the ME. PMID:27540587

  7. A novel GABA-mediated corticotropin-releasing hormone secretory mechanism in the median eminence.

    PubMed

    Kakizawa, Keisuke; Watanabe, Miho; Mutoh, Hiroki; Okawa, Yuta; Yamashita, Miho; Yanagawa, Yuchio; Itoi, Keiichi; Suda, Takafumi; Oki, Yutaka; Fukuda, Atsuo

    2016-08-01

    Corticotropin-releasing hormone (CRH), which is synthesized in the paraventricular nucleus (PVN) of the hypothalamus, plays an important role in the endocrine stress response. The excitability of CRH neurons is regulated by γ-aminobutyric acid (GABA)-containing neurons projecting to the PVN. We investigated the role of GABA in the regulation of CRH release. The release of CRH was impaired, accumulating in the cell bodies of CRH neurons in heterozygous GAD67-GFP (green fluorescent protein) knock-in mice (GAD67(+/GFP)), which exhibited decreased GABA content. The GABAA receptor (GABAAR) and the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1), but not the K(+)-Cl(-) cotransporter (KCC2), were expressed in the terminals of the CRH neurons at the median eminence (ME). In contrast, CRH neuronal somata were enriched with KCC2 but not with NKCC1. Thus, intracellular Cl(-) concentrations ([Cl(-)]i) may be increased at the terminals of CRH neurons compared with concentrations in the cell body. Moreover, GABAergic terminals projecting from the arcuate nucleus were present in close proximity to CRH-positive nerve terminals. Furthermore, a GABAAR agonist increased the intracellular calcium (Ca(2+)) levels in the CRH neuron terminals but decreased the Ca(2+) levels in their somata. In addition, the increases in Ca(2+) concentrations were prevented by an NKCC1 inhibitor. We propose a novel mechanism by which the excitatory action of GABA maintains a steady-state CRH release from axon terminals in the ME. PMID:27540587

  8. Increased GABA concentrations in type 2 diabetes mellitus are related to lower cognitive functioning

    PubMed Central

    van Bussel, Frank C.G.; Backes, Walter H.; Hofman, Paul A.M.; Puts, Nicolaas A.J.; Edden, Richard A.E.; van Boxtel, Martin P.J.; Schram, Miranda T.; Stehouwer, Coen D.A.; Wildberger, Joachim E.; Jansen, Jacobus F.A.

    2016-01-01

    Abstract Type 2 diabetes mellitus is associated with accelerated cognitive decline. The underlying pathophysiological mechanisms still remain to be elucidated although it is known that insulin signaling modulates neurotransmitter activity, including inhibitory γ-aminobutyric acid (GABA) and excitatory glutamate (Glu) receptors. Therefore, we examined whether levels of GABA and Glu are related to diabetes status and cognitive performance. Forty-one participants with type 2 diabetes and 39 participants without type 2 diabetes underwent detailed cognitive assessments and 3-Tesla proton MR spectroscopy. The associations of neurotransmitters with type 2 diabetes and cognitive performance were examined using multivariate regression analyses controlling for age, sex, education, BMI, and percentage gray/white matter ratio in spectroscopic voxel. Analysis revealed higher GABA+ levels in participants with type 2 diabetes, in participants with higher fasting blood glucose levels and in participants with higher HbA1c levels, and higher GABA+ levels in participants with both high HbA1c levels and less cognitive performance. To conclude, participants with type 2 diabetes have alterations in the GABAergic neurotransmitter system, which are related to lower cognitive functioning, and hint at the involvement of an underlying metabolic mechanism. PMID:27603392

  9. The pharmacology of spontaneously open alpha 1 beta 3 epsilon GABA A receptor-ionophores.

    PubMed

    Maksay, Gábor; Thompson, Sally A; Wafford, Keith A

    2003-06-01

    Human alpha(1)beta(3) epsilon GABA(A) receptors were expressed in Xenopus oocytes and examined using the conventional two-electrode voltage-clamp technique and compared to alpha(1)beta(3)gamma(2) receptors. The effects of several GABA(A) agonists were studied, and the allosteric modulation of the channel by a number of GABAergic modulators investigated. The presence of the epsilon subunit increased the potency and efficacy of direct activation by partial GABA(A) agonists (piperidine-4-sulphonic acid and thio-4-PIOL), pentobarbital and neuro-steroids. Direct activation by 3-hydroxylated neurosteroids was restricted to 3alpha epimers, while chirality at C5 was indifferent. The 3beta-sulfate esters of pregnenolone and dehydroepiandrosterone inhibited the spontaneous currents with efficacies higher, while bicuculline methiodide and SR 95531 did so lower than picrotoxin and TBPS. Furosemide, fipronil, triphenylcyanoborate and Zn(2+) blocked the spontaneous currents of alpha(1)beta(3) epsilon receptors with different efficacies. Flunitrazepam and 4'-chlorodiazepam inhibited the spontaneous currents with micromolar potencies. In conclusion, spontaneously active alpha(1)beta(3) epsilon GABA(A) receptors can be potentiated and blocked by GABAergic agents within a broad range of efficacy.

  10. Presynaptic Na+-dependent transport and exocytose of GABA and glutamate in brain in hypergravity.

    NASA Astrophysics Data System (ADS)

    Borisova, T.; Pozdnyakova, N.; Krisanova, N.; Himmelreich, N.

    γ-Aminobutyric acid (GABA) and L-glutamate are the most widespread neurotransmitter amino acids in the mammalian central nervous system. GABA is now widely recognized as the major inhibitory neurotransmitter. L-glutamate mediates the most of excitatory synaptic neurotransmission in the brain. They involved in the main aspects of normal brain function. The nerve terminals (synaptosomes) offer several advantages as a model system for the study of general mechanisms of neurosecretion. Our data allowed to conclude that exposure of animals to hypergravity (centrifugation of rats at 10G for 1 hour) had a profound effect on synaptic processes in brain. Comparative analysis of uptake and release of GABA and glutamate have demonstrated that hypergravity loading evokes oppositely directed alterations in inhibitory and excitatory signal transmission. We studied the maximal velocities of [^3H]GABA reuptake and revealed more than twofold enhancement of GABA transporter activity (Vmax rises from 1.4 |pm 0.3 nmol/min/mg of protein in the control group to 3.3 ± 0.59 nmol/min/mg of protein for animals exposed to hypergravity (P ≤ 0.05)). Recently we have also demonstrated the significant lowering of glutamate transporter activity (Vmax of glutamate reuptake decreased from 12.5 ± 3.2 nmol/min/mg of protein in the control group to 5.6 ± 0.9 nmol/min/mg of protein in the group of animals, exposed to the hypergravity stress (P ≤ 0.05)). Significant changes occurred in release of neurotransmitters induced by stimulating exocytosis with the agents, which depolarized nerve terminal plasma membrane. Depolarization-evoked Ca2+-stimulated release was more abundant for GABA (7.2 ± 0.54% and 11,74 ±1,2 % of total accumulated label for control and hypergravity, respectively (P≤0.05)) and was essentially less for glutamate (14.4 ± 0.7% and 6.2 ± 1.9%) after exposure of animals to centrifuge induced artificial gravity. Changes observed in depolarization-evoked exocytotic release

  11. The effect of antivitamin B6 administration on gamma-aminobutyric acid metabolism in retina and electroretinogram.

    PubMed

    Mizuno, A; Kamada, Y; Kunita, M; Matsuda, M

    1980-01-01

    The effect of several antivitamin B6 on gamma-aminobutyric acid (GABA) metabolism was studied in the rat retina. The rat electroretinogram (ERG) was also recorded after administration of these drugs. Aminooxyacetic acid (AOAA) and hydrazine administration increased the GABA content and inhibited the GABA degrading enzyme, GABA transaminase in retina. In addition, there drugs elongated the peak latency of the oscillatory potential in the rat ERG. In contrast, 4-deoxypyridoxine (DOP) or isonicotinic acid hydrazide (INAH) administration decreased the GABA content and inhibited the GABA synthesizing enzyme, glutamic acid decarboxylase in retina, and administration of these drugs together with AOAA lessened the degrees of elevation of GABA content and of the elongation of the peak latency produced as compared with AOAA alone, though neither of the former drugs had a significant effect on ERG. The retinal GABA seems to play an important role in relation to the oscillatory potential of ERG.

  12. Redirection of Metabolic Flux into Novel Gamma-Aminobutyric Acid Production Pathway by Introduction of Synthetic Scaffolds Strategy in Escherichia Coli.

    PubMed

    Pham, Van Dung; Somasundaram, Sivachandiran; Lee, Seung Hwan; Park, Si Jae; Hong, Soon Ho

    2016-04-01

    In general, gamma-aminobutyric acid (GABA) pathway involves the decarboxylation of glutamate, which is produced from sugar by Corynebacterium fermentation. GABA can be used for the production of pharmaceuticals and functional foods. Due to the increasing demand of GABA, it is essential to create an effective alternative pathway for the GABA production. In this study, Escherichia coli were engineered to produce GABA from glucose via GABA shunt, which consists of succinate dehydrogenase, succinate-semialdehyde dehydrogenase, and GABA aminotransferase. The three enzymes were physically attached to each other through a synthetic scaffold, and the Krebs cycle flux was redirected to the GABA pathway. By introduction of synthetic scaffold, 0.75 g/l of GABA was produced from 10 g/l of glucose at 30 °C and pH 6.5. The inactivation of competing metabolic pathways provided 15.4 % increase in the final GABA concentration. PMID:26667817

  13. P2Y1 receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes.

    PubMed

    Jacob, Pedro F; Vaz, Sandra H; Ribeiro, Joaquim A; Sebastião, Ana M

    2014-08-01

    Astrocytes express a variety of purinergic (P2) receptors, involved in astrocytic communication through fast increases in [Ca(2+) ]i . Of these, the metabotropic ATP receptors (P2Y) regulate cytoplasmic Ca(2+) levels through the PLC-PKC pathway. GABA transporters are a substrate for a number of Ca(2+) -related kinases, raising the possibility that calcium signalling in astrocytes impact the control of extracellular levels of the major inhibitory transmitter in the brain. To access this possibility we tested the influence of P2Y receptors upon GABA transport into astrocytes. Mature primary cortical astroglial-enriched cultures expressed functional P2Y receptors, as evaluated through Ca(2+) imaging, being P2Y1 the predominant P2Y receptor subtype. ATP (100 μM, for 1 min) caused an inhibition of GABA transport through either GAT-1 or GAT-3 transporters, decreasing the Vmax kinetic constant. ATP-induced inhibition of GATs activity was still evident in the presence of adenosine deaminase, precluding an adenosine-mediated effect. This, was mimicked by a specific agonist for the P2Y1,12,13 receptor (2-MeSADP). The effect of 2-MeSADP on GABA transport was blocked by the P2 (PPADS) and P2Y1 selective (MRS2179) receptor antagonists, as well as by the PLC inhibitor (U73122). 2-MeSADP failed to inhibit GABA transport in astrocytes where intracellular calcium had been chelated (BAPTA-AM) or where calcium stores were depleted (α-cyclopiazonic acid, CPA). In conclusion, P2Y1 receptors in astrocytes inhibit GABA transport through a mechanism dependent of P2Y1 -mediated calcium signalling, suggesting that astrocytic calcium signalling, which occurs as a consequence of neuronal firing, may operate a negative feedback loop to enhance extracellular levels of GABA. PMID:24733747

  14. Identification of gamma-aminobutyric acid and its binding sites in Caenorhabditis elegans

    SciTech Connect

    Schaeffer, J.M.; Bergstrom, A.R.

    1988-01-01

    Gamma-aminobutyric acid (GABA), glutamate decarboxylase and GABA-transaminase were identified in the nematode Caenorhabditis elegans. The concentration of GABA in C. elegans is approximately 10-fold lower than the concentration of GABA in rat brain. Glutamate decarboxylase and GABA-transaminase, the GABA anabolic and catabolic enzymes, are also present in C. elegans. Crude membrane fractions were prepared from C. elegans and used to study specific (/sup 3/H) GABA binding sites. GABA binds to C. elegans membranes with high affinity and low capacity. Muscimol is a competitive inhibitor of specific GABA binding with a K/sub I/ value of 120 nM. None of the other GABA agonists or antagonists inhibited greater than 40% of the specific GABA binding at concentrations up to 10/sup -4/M. Thirteen spider venoms were examined as possible GABA agonists or antagonists, the venom from Calilena agelenidae inhibits specific GABA binding with a K/sub I/ value of 6 nl/ml. These results suggest that GABA has a physiological role as a neurotransmitter in C. elegans.

  15. Vibrational Spectra of γ-Aminobutyric Acid

    NASA Astrophysics Data System (ADS)

    Suresh, D. M.; Sajan, D.; Laladas, K. P.; Joe, I. Hubert; Jayakumar, V. S.

    2008-11-01

    The NIR-FT Raman, FT-IR spectral analysis of γ-Aminobutyric acid (GABA) a simple amino acid is carried out by density functional computations. The vibrational spectra confirm the existence of NH3+ in GABA. Hydroxyl groups H-bonded to the different extents are analysed, supported by computed results.

  16. Conserved Regional Patterns of GABA-Related Transcript Expression in the Neocortex of Subjects With Schizophrenia

    PubMed Central

    Hashimoto, Takanori; Bazmi, H. Holly; Mirnics, Karoly; Wu, Qiang; Sampson, Allan R.; Lewis, David A.

    2010-01-01

    Objective Individuals with schizophrenia exhibit disturbances in a number of cognitive, affective, sensory, and motor functions that depend on the circuitry of different cortical areas. The cognitive deficits associated with dysfunction of the dorsolateral prefrontal cortex result, at least in part, from abnormalities in GABA neurotransmission, as reflected in a specific pattern of altered expression of GABA-related genes. Consequently, the authors sought to determine whether this pattern of altered gene expression is restricted to the dorsolateral prefrontal cortex or could also contribute to the dysfunction of other cortical areas in subjects with schizophrenia. Method Real-time quantitative polymerase chain reaction was used to assess the levels of eight GABA-related transcripts in four cortical areas (dorsolateral prefrontal cortex, anterior cingulate cortex, and primary motor and primary visual cortices) of subjects (N=12) with schizophrenia and matched normal comparison subjects. Results Expression levels of seven transcripts were lower in subjects with schizophrenia, with the magnitude of reduction for each transcript comparable across the four areas. The largest reductions were detected for mRNA encoding somatostatin and parvalbumin, followed by moderate decreases in mRNA expression for the 67-kilodalton isoform of glutamic acid decarboxylase, the GABA membrane transporter GAT-1, and the α1 and δ subunits of GABAA receptors. In contrast, the expression of calretinin mRNA did not differ between the subject groups in any of the four areas. Conclusions Because the areas examined represent the major functional domains (e.g., association, limbic, motor, and sensory) of the cerebral cortex, our findings suggest that a conserved set of molecular alterations affecting GABA neurotransmission contribute to the pathophysiology of different clinical features of schizophrenia. PMID:18281411

  17. In vivo GABA T2 determination with J-refocused echo time extension at 7 T.

    PubMed

    Andreychenko, A; Klomp, D W J; de Graaf, R A; Luijten, P R; Boer, V O

    2013-11-01

    A method to measure the T2 relaxation time of GABA with spectral editing techniques is proposed. Spectral editing techniques can be used to unambiguously extract signals of low concentration J-coupled spins such as γ-aminobutyric acid (GABA) from overlapping resonances such as creatine and macromolecules. These sequences, however, generally have fixed and relatively long echo times. Therefore, for the absolute quantification of the edited spectrum, the T2 relaxation time must be taken into account. To measure the T2 relaxation time, the signal intensity has to be obtained at multiple echo times. However, on a coupled spin system such as GABA this is challenging, since the signal intensity of the target resonances is modulated not only by T2 decay but also by the J-coupling, which strongly influences the shapes and amplitudes of the edited signals, depending on the echo time. Here, we propose to refocus the J-modulation of the edited signal at different echo times by using chemical shift selective refocusing. In this way the echo time can be arbitrarily extended while preserving the shape of the edited signal. The method was applied in combination with the MEGA-sLASER editing technique to measure the in vivo T2 relaxation time of GABA (87 ± 11 ms, n = 10) and creatine (109 ± 8 ms, n = 10) at 7 T. The T1 relaxation time of these metabolites in a single subject was also determined (GABA, 1334 ± 158 ms; Cr, 1753 ± 12 ms). The T2 decay curve of coupled spin systems can be sampled in an arbitrary fashion without the need for signal shape correction. Furthermore, the method can be applied with any spectral editing technique. The shortest echo time of the method is limited by the echo time of the spectral editing technique.

  18. Colocalization of serotonin and GABA in retinal neurons of Ichthyophis kohtaoensis (amphibia; Gymnophiona).

    PubMed

    Dünker, N

    1998-01-01

    Ichthyophis kohtaoensis, a member of the limbless Gymnophiona, has a specialized subterranean burrowing mode of life and a predominantly olfactory-guided orientation. The only visually guided behavior seems to be negative phototaxis. As these animals possess extremely small eyes (only 540 microm in diameter in adults), functional investigations of single retinal cells by electrophysiological methods have so far failed. Therefore, the content and distribution of retinal transmitters have been investigated as indications of a functioning sense organ in an animal that is supposed to be blind. Previous immunohistochemical investigation of the retinal transmitter system revealed immunoreactivity for gamma-aminobutyric acid (GABA), serotonin, dopamine and tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthetic pathway. The present studies have been performed in order to determine a possible colocalization of serotonin and GABA in retinal neurons of the caecilian retina. Therefore retinal cryostat sections of various developmental stages have been investigated by the indirect fluorescence method. In single-label preparations, serotonin is localized to cells in the inner nuclear layer and the ganglion cell layer. GABA immunocytochemistry labels a variety of cell types in the inner nuclear layer as well as cell bodies in the ganglion cell layer. In double-label preparations, some of the serotonergic cells are found to express GABA immunoreactivity and some GABAergic neurons also label for serotonin immunocytochemistry. Thus, despite the fact that caecilians mainly rely on olfaction and are believed to have a reduced visual system, their retina exhibits a surprisingly "normal" distribution of neurotransmitters and neuromodulators, also typical of other anamniotes with a well-developed visual system, including the partial colocalization of serotonin and GABA at all developmental stages of I. kohtaoensis. These results indicate that a functional system

  19. Effects of beer and hop on ionotropic gamma-aminobutyric acid receptors.

    PubMed

    Aoshima, Hitoshi; Takeda, Katsuichi; Okita, Yoichi; Hossain, Sheikh Julfikar; Koda, Hirofumi; Kiso, Yoshinobu

    2006-04-01

    Beer induced the response of the ionotropic gamma-aminobutyric acid receptors (GABA(A) receptors) expressed in Xenopus oocytes, indicating the presence of gamma-aminobutyric acid (GABA)-like activity. Furthermore, the pentane extract of the beer, hop (Humulus lupulus L.) oil, and myrcenol potentiated the GABA(A) receptor response elicited by GABA. The GABA(A) receptor responses were also potentiated by the addition of aliphatic esters, most of which are reported to be present in beer flavor. Aliphatic esters showed the tendency to decrease in the potentiation of the GABA(A) receptor response with an increase in their carbon chain length. When myrcenol was injected to mice prior to intraperitoneal administration of pentobarbital, the pentobarbital-induced sleeping time of mice increased additionally. Therefore, the beer contained not only GABA-like activity but also the modulator(s) of the GABA(A) receptor response.

  20. Muscimol prevents long-lasting potentiation of dorsal horn field potentials in rats with chronic constriction injury exhibiting decreased levels of the GABA transporter GAT-1.

    PubMed

    Miletic, Gordana; Draganic, Pero; Pankratz, Matthew T; Miletic, Vjekoslav

    2003-09-01

    The inhibitory activity of gamma-aminobutyric acid (GABA) is considered critical in setting the conditions for synaptic plasticity, and many studies support an important role of GABA in the suppression of nociceptive transmission in the dorsal horn. Consequently, any injury-induced modification of the GABA action has the potential to critically modify spinal synaptic plasticity. We have previously reported that chronic constriction injury of the sciatic nerve was accompanied by long-lasting potentiation of superficial spinal dorsal horn field potentials following high-frequency tetanus. In this study we examined whether the GABA-A receptor agonist muscimol would modify post-tetanic responses in rats with chronic constriction injury. In animals exhibiting maximal thermal hyperalgesia as one sign of neuropathic pain 7 days after loose ligation of the sciatic nerve, spinal application of muscimol (5, 10 or 20 microg) before the high-frequency (50 Hz) tetanus produced a long-lasting depression (rather than potentiation) of spinal dorsal horn field potentials. In separate but related Western immunoblot experiments, we also established that the chronic constriction injury was accompanied by significant decreases in the content of the GABA transporter GAT-1. These data demonstrated that GABA-A receptor agonists may effectively influence the expression of long-lasting synaptic plasticity in the spinal dorsal horn, and that an injury-induced loss in GABA transporter content may have contributed to a depletion of GABA from its terminals within the spinal dorsal horn. These data lent further support to the notion that the loss of GABA inhibition may have important consequences for the development of neuropathic pain. PMID:14499453

  1. Enhancement by GABA of the association rate of picrotoxin and tert-butylbicyclophosphorothionate to the rat cloned alpha 1 beta 2 gamma 2 GABAA receptor subtype.

    PubMed Central

    Dillon, G. H.; Im, W. B.; Carter, D. B.; McKinley, D. D.

    1995-01-01

    1. We examined how gamma-aminobutyric acid (GABA) influences interaction of picrotoxin and tert-butylbicyclophosphorothionate (TBPS) with recombinant rat alpha 1 beta 2 gamma 2 GABAA receptors stably expressed in human embryonic kidney cells (HEK293), as monitored with changes in Cl- currents measured by the whole-cell patch clamp technique. 2. During application of GABA (5 microM) for 15 s, picrotoxin and TBPS dose-dependently accelerated the decay of inward GABA-induced currents (a holding potential of -60 mV under a symmetrical Cl- gradient). The drugs, upon preincubation with the receptors, also reduced the initial current amplitude in a preincubation time and concentration-dependent manner. This indicates their interaction with both GABA-bound and resting receptors. 3. The half maximal inhibitory concentration for picrotoxin and TBPS at the beginning of a 15 s GABA (5 microM) pulse was several times greater than that obtained at the end of the pulse. GABA thus appears to enhance picrotoxin and TBPS potency, but only at concentrations leading to occupancy of both high and low affinity GABA sites, i.e., 5 microM. Preincubation of the receptors with the drugs in the presence of GABA at 200 nM, which leads to occupancy of only high affinity GABA sites in the alpha 1 beta 2 gamma 2 subtype, produced no appreciable change in potency of picrotoxin or TBPS. This indicates that they preferentially interact with multiliganded, but not monoliganded receptors, unlike U-93631, a novel ligand to the picrotoxin site, which has higher affinity to both mono- and multiliganded receptors than resting receptors.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7582470

  2. Connections between EM2-containing terminals and GABA/μ-opioid receptor co-expressing neurons in the rat spinal trigeminal caudal nucleus.

    PubMed

    Li, Meng-Ying; Wu, Zhen-Yu; Lu, Ya-Cheng; Yin, Jun-Bin; Wang, Jian; Zhang, Ting; Dong, Yu-Lin; Wang, Feng

    2014-01-01

    Endomorphin-2 (EM2) demonstrates a potent antinociceptive effect via the μ-opioid receptor (MOR). To provide morphological evidence for the pain control effect of EM2, the synaptic connections between EM2-immunoreactive (IR) axonal terminals and γ-amino butyric acid (GABA)/MOR co-expressing neurons in lamina II of the spinal trigeminal caudal nucleus (Vc) were investigated in the rat. Dense EM2-, MOR- and GABA-IR fibers and terminals were mainly observed in lamina II of the Vc. Within lamina II, GABA- and MOR-neuronal cell bodies were also encountered. The results of immunofluorescent histochemical triple-staining showed that approximately 14.2 or 18.9% of GABA-IR or MOR-IR neurons also showed MOR- or GABA-immunopositive staining in lamina II; approximately 45.2 and 36.1% of the GABA-IR and MOR-IR neurons, respectively, expressed FOS protein in their nuclei induced by injecting formalin into the left lower lip of the mouth. Most of the GABA/MOR, GABA/FOS, and MOR/FOS double-labeled neurons made close contacts with EM2-IR fibers and terminals. Immuno-electron microscopy confirmed that the EM2-IR terminals formed synapses with GABA-IR or MOR-IR dendritic processes and neuronal cell bodies in lamina II of the Vc. These results suggest that EM2 might participate in pain transmission and modulation by binding to MOR-IR and GABAergic inhibitory interneuron in lamina II of the Vc to exert inhibitory effect on the excitatory interneuron in lamina II and projection neurons in laminae I and III.

  3. Cocaine disinhibits dopamine neurons in the ventral tegmental area via use-dependent blockade of GABA neuron voltage-sensitive sodium channels.

    PubMed

    Steffensen, Scott C; Taylor, Seth R; Horton, Malia L; Barber, Elise N; Lyle, Laura T; Stobbs, Sarah H; Allison, David W

    2008-11-01

    The aim of this study was to evaluate the effects of cocaine on gamma-aminobutyric acid (GABA) and dopamine (DA) neurons in the ventral tegmental area (VTA). Utilizing single-unit recordings in vivo, microelectrophoretic administration of DA enhanced the firing rate of VTA GABA neurons via D2/D3 DA receptor activation. Lower doses of intravenous cocaine (0.25-0.5 mg/kg), or the DA transporter (DAT) blocker methamphetamine, enhanced VTA GABA neuron firing rate via D2/D3 receptor activation. Higher doses of cocaine (1.0-2.0 mg/kg) inhibited their firing rate, which was not sensitive to the D2/D3 antagonist eticlopride. The voltage-sensitive sodium channel (VSSC) blocker lidocaine inhibited the firing rate of VTA GABA neurons at all doses tested (0.25-2.0 mg/kg). Cocaine or lidocaine reduced VTA GABA neuron spike discharges induced by stimulation of the internal capsule (ICPSDs) at dose levels 0.25-2 mg/kg (IC(50) 1.2 mg/kg). There was no effect of DA or methamphetamine on ICPSDs, or of DA antagonists on cocaine inhibition of ICPSDs. In VTA GABA neurons in vitro, cocaine reduced (IC(50) 13 microm) current-evoked spikes and TTX-sensitive sodium currents in a use-dependent manner. In VTA DA neurons, cocaine reduced IPSCs (IC(50) 13 microm), increased IPSC paired-pulse facilitation and decreased spontaneous IPSC frequency, without affecting miniature IPSC frequency or amplitude. These findings suggest that cocaine acts on GABA neurons to reduce activity-dependent GABA release on DA neurons in the VTA, and that cocaine's use-dependent blockade of VTA GABA neuron VSSCs may synergize with its DAT inhibiting properties to enhance mesolimbic DA transmission implicated in cocaine reinforcement.

  4. Neuroprotective effect of vitamin C against the ethanol and nicotine modulation of GABA(B) receptor and PKA-alpha expression in prenatal rat brain.

    PubMed

    Naseer, M I; Lee, H Y; Kim, M O

    2010-06-01

    Prenatal ethanol exposure has various deleterious effects on neuronal development and can induce various defects in developing brain, resulting in fetal alcohol syndrome (FAS). gamma-Aminobutyric acid (GABA(B)) receptor (R) is known to play an important role during the development of the central nervous system (CNS). Our study was designed to investigate the effect of ethanol (100 mM), nicotine (50 microM) (for 30 min and 1 h), vitamin C (vitC, 0.5 mM), ethanol plus vitC, and nicotine plus vitC on expression level of GABA(B1), GABA(B2)R, and protein kinase A-alpha (PKA) in prenatal rat cortical and hippocampal neurons at gestational days (GD) 17.5. The results showed that, upon ethanol and nicotine exposure, GABA(B1) and GABA(B2)R protein expression increased significantly in the cortex and hippocampus for a short (30 min) and long term (1 h), whereas only GABA(B2)R subunit was decreased upon nicotine exposure for a long term in the cortex. Furthermore, PKA expression in cortex and hippocampus increased with ethanol exposure during short term, whereas long-term exposure results increased in cortex and decreased in hippocampus. Moreover, the cotreatment of vitC with ethanol and nicotine showed significantly decreased expression of GABA(B1), GABA(B2)R, and PKA in cortex and hippocampus for a long-term exposure. Mitochondrial membrane potential, Fluoro-jade-B, and propidium iodide staining were used to elucidate possible neurodegeneration. Our results suggest the involvement of GABA(B)R and PKA in nicotine and ethanol-mediated neurodevelopmental defects and the potential use of vitC as a effective protective agent for FAS-related deficits.

  5. Dysfunction in GABA signalling mediates autism-like stereotypies and Rett syndrome phenotypes.

    PubMed

    Chao, Hsiao-Tuan; Chen, Hongmei; Samaco, Rodney C; Xue, Mingshan; Chahrour, Maria; Yoo, Jong; Neul, Jeffrey L; Gong, Shiaoching; Lu, Hui-Chen; Heintz, Nathaniel; Ekker, Marc; Rubenstein, John L R; Noebels, Jeffrey L; Rosenmund, Christian; Zoghbi, Huda Y

    2010-11-11

    Mutations in the X-linked MECP2 gene, which encodes the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2), cause Rett syndrome and several neurodevelopmental disorders including cognitive disorders, autism, juvenile-onset schizophrenia and encephalopathy with early lethality. Rett syndrome is characterized by apparently normal early development followed by regression, motor abnormalities, seizures and features of autism, especially stereotyped behaviours. The mechanisms mediating these features are poorly understood. Here we show that mice lacking Mecp2 from GABA (γ-aminobutyric acid)-releasing neurons recapitulate numerous Rett syndrome and autistic features, including repetitive behaviours. Loss of MeCP2 from a subset of forebrain GABAergic neurons also recapitulates many features of Rett syndrome. MeCP2-deficient GABAergic neurons show reduced inhibitory quantal size, consistent with a presynaptic reduction in glutamic acid decarboxylase 1 (Gad1) and glutamic acid decarboxylase 2 (Gad2) levels, and GABA immunoreactivity. These data demonstrate that MeCP2 is critical for normal function of GABA-releasing neurons and that subtle dysfunction of GABAergic neurons contributes to numerous neuropsychiatric phenotypes. PMID:21068835

  6. Dysfunction in GABA signalling mediates autism-like stereotypies and Rett syndrome phenotypes.

    PubMed

    Chao, Hsiao-Tuan; Chen, Hongmei; Samaco, Rodney C; Xue, Mingshan; Chahrour, Maria; Yoo, Jong; Neul, Jeffrey L; Gong, Shiaoching; Lu, Hui-Chen; Heintz, Nathaniel; Ekker, Marc; Rubenstein, John L R; Noebels, Jeffrey L; Rosenmund, Christian; Zoghbi, Huda Y

    2010-11-11

    Mutations in the X-linked MECP2 gene, which encodes the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2), cause Rett syndrome and several neurodevelopmental disorders including cognitive disorders, autism, juvenile-onset schizophrenia and encephalopathy with early lethality. Rett syndrome is characterized by apparently normal early development followed by regression, motor abnormalities, seizures and features of autism, especially stereotyped behaviours. The mechanisms mediating these features are poorly understood. Here we show that mice lacking Mecp2 from GABA (γ-aminobutyric acid)-releasing neurons recapitulate numerous Rett syndrome and autistic features, including repetitive behaviours. Loss of MeCP2 from a subset of forebrain GABAergic neurons also recapitulates many features of Rett syndrome. MeCP2-deficient GABAergic neurons show reduced inhibitory quantal size, consistent with a presynaptic reduction in glutamic acid decarboxylase 1 (Gad1) and glutamic acid decarboxylase 2 (Gad2) levels, and GABA immunoreactivity. These data demonstrate that MeCP2 is critical for normal function of GABA-releasing neurons and that subtle dysfunction of GABAergic neurons contributes to numerous neuropsychiatric phenotypes.

  7. Excitatory Amino Acid Receptors Mediate Asymmetry and Lateralization in the Descending Cardiovascular Pathways from the Dorsomedial Hypothalamus

    PubMed Central

    Xavier, Carlos Henrique; Ianzer, Danielle; Lima, Augusto Martins; Marins, Fernanda Ribeiro; Pedrino, Gustavo Rodrigues; Vaz, Gisele; Menezes, Gustavo Batista; Nalivaiko, Eugene; Fontes, Marco Antônio Peliky

    2014-01-01

    The dorsomedial hypothalamus (DMH) and lateral/dorsolateral periaqueductal gray (PAG) are anatomically and functionally connected. Both the DMH and PAG depend on glutamatergic inputs for activation. We recently reported that removal of GABA-ergic tone in the unilateral DMH produces: asymmetry, that is, a right- (R-) sided predominance in cardiac chronotropism, and lateralization, that is, a greater increase in ipsilateral renal sympathetic activity (RSNA). In the current study, we investigated whether excitatory amino acid (EAA) receptors in the DMH–PAG pathway contribute to the functional interhemispheric difference. In urethane (1.2 to 1.4 g/kg, i.p.) anesthetized rats, we observed that: (i) nanoinjections of N-methyl D-aspartate (NMDA 100 pmol/100 nl) into the unilateral DMH produced the same right-sided predominance in the control of cardiac chronotropy, (ii) nanoinjections of NMDA into the ipsilateral DMH or PAG evoked lateralized RSNA responses, and (iii) blockade of EAA receptors in the unilateral DMH attenuated the cardiovascular responses evoked by injection of NMDA into either the R- or left- (L-) PAG. In awake rats, nanoinjection of kynurenic acid (1 nmol/100 nL) into the L-DMH or R- or L-PAG attenuated the tachycardia evoked by air stress. However, the magnitude of stress-evoked tachycardia was smallest when the EAA receptors of the R-DMH were blocked. We conclude that EAA receptors contribute to the right-sided predominance in cardiac chronotropism. This interhemispheric difference that involves EAA receptors was observed in the DMH but not in the PAG. PMID:25397884

  8. Role of the alpha subunit in the modulation of GABA(A) receptors by anabolic androgenic steroids.

    PubMed

    Yang, Paul; Jones, Brian L; Henderson, Leslie P

    2005-09-01

    Neural transmission mediated by circuits expressing alpha2 subunit-containing gamma-aminobutyric acid type A (GABA(A)) receptors is critical for the expression of behaviors known to be altered by anabolic androgenic steroids (AAS). Here we show that micromolar concentrations of AAS, which reflect levels found in steroid abusers, induce positive modulation of currents from alpha2beta3 gamma2L recombinant receptors elicited by pulses of GABA that mimic synaptic conditions in a manner that is mechanistically distinct from modulation induced at alpha1beta3 gamma2L receptors. Specifically, at alpha2-containing receptors, the AAS, 17alpha-methyltestosterone (17alpha-MeT) enhanced peak current, slowed deactivation, diminished desensitization, and promoted entry of receptors into more distal states along the activation pathway. Analysis of GABA(A) receptor-mediated synaptic currents in primary cortical neurons followed by single cell real-time RT-PCR demonstrated that 17alpha-MeT enhancement of synaptic currents is proportional to the ratio of alpha2 to alpha1 subunit mRNA. Finally, we show that the modulation elicited by AAS is not comparable to that produced by micromolar concentrations of other positive allosteric modulators at alpha2-containing receptors. In sum, these data indicate that AAS elicit effects on GABA(A) receptor function that depend significantly on alpha subunit composition and that the mechanism of AAS modulation of GABA(A) receptors is distinct from that of other positive allosteric modulators.

  9. Adenosine A2A receptor stimulation decreases GAT-1-mediated GABA uptake in the globus pallidus of the rat.

    PubMed

    Gonzalez, Brenda; Paz, Francisco; Florán, Leonor; Aceves, Jorge; Erlij, David; Florán, Benjamín

    2006-07-01

    We examined modulation of [(3)H]GABA uptake in slices of the rat globus pallidus because stimulation of adenosine A(2A) receptors increases extracellular GABA in this structure. Pharmacological analysis showed that GAT-1 is the main transporter present in these slices. Both adenosine and the A(2A) agonist CGS 21680 reduced GABA uptake. Antagonist ZM 241385 prevented these effects. Agents that increase protein kinase A activity like forskolin and 8-bromo-cAMP also inhibited GABA uptake. The inhibition of uptake produced by these substances and by CGS 21680 was prevented by the protein kinase A blocker H-89. The protein phosphatase blocker okadaic acid reduced uptake; this effect and the response to CGS 21680 were not additive. The effective concentrations of adenosine (EC(50)=15.2microM) are within the range measured in the interstitial fluid under some physiological conditions. Thus, inhibition of uptake may be important in increasing interstitial GABA during endogenous adenosine release.

  10. Receptive-field size of S1 cortical neurones is altered by methaqualone via a GABA mechanism.

    PubMed

    Hicks, T P; Kaneko, T; Oka, J I

    1990-02-01

    Methaqualone (Mtq; quaaludes or 'ludes) is a controlled substance, having a molecular structure related to the imidiazobenzodiazepine series of drugs, that has gained some notoriety recently due to its history of widespread abuse on the street. Users report experiencing peripheral paresthesia and transient numbness on body parts receiving dense cutaneous innervation (lips, fingertips, etc.). Since the receptive-field (RF)-sizes of many primary somatosensory (S1) cortical neurones are controlled by local, gamma-aminobutyric acid (GABA)-mediated inhibitory processes, we tested Mtq to see whether its clinical symptoms might have a basis in an action through central GABA-mediated synaptic processes. This report supports this contention and describes a likely pharmacological mechanism involved as one being related to the Ro 15-1788-sensitive benzodiazepine (Bzd) recognition site(s) of the GABA receptor complex. PMID:2311013

  11. Receptive-field size of S1 cortical neurones is altered by methaqualone via a GABA mechanism.

    PubMed

    Hicks, T P; Kaneko, T; Oka, J I

    1990-02-01

    Methaqualone (Mtq; quaaludes or 'ludes) is a controlled substance, having a molecular structure related to the imidiazobenzodiazepine series of drugs, that has gained some notoriety recently due to its history of widespread abuse on the street. Users report experiencing peripheral paresthesia and transient numbness on body parts receiving dense cutaneous innervation (lips, fingertips, etc.). Since the receptive-field (RF)-sizes of many primary somatosensory (S1) cortical neurones are controlled by local, gamma-aminobutyric acid (GABA)-mediated inhibitory processes, we tested Mtq to see whether its clinical symptoms might have a basis in an action through central GABA-mediated synaptic processes. This report supports this contention and describes a likely pharmacological mechanism involved as one being related to the Ro 15-1788-sensitive benzodiazepine (Bzd) recognition site(s) of the GABA receptor complex.

  12. A1R-A2AR heteromers coupled to Gs and G i/0 proteins modulate GABA transport into astrocytes.

    PubMed

    Cristóvão-Ferreira, Sofia; Navarro, Gemma; Brugarolas, Marc; Pérez-Capote, Kamil; Vaz, Sandra H; Fattorini, Giorgia; Conti, Fiorenzo; Lluis, Carmen; Ribeiro, Joaquim A; McCormick, Peter J; Casadó, Vicent; Franco, Rafael; Sebastião, Ana M

    2013-09-01

    Astrocytes play a key role in modulating synaptic transmission by controlling extracellular gamma-aminobutyric acid (GABA) levels via GAT-1 and GAT-3 GABA transporters (GATs). Using primary cultures of rat astrocytes, we show here that a further level of regulation of GABA uptake occurs via modulation of the GATs by the adenosine A1 (A1R) and A2A (A2AR) receptors. This regulation occurs through A1R-A2AR heteromers that signal via two different G proteins, Gs and Gi/0, and either enhances (A2AR) or inhibits (A1R) GABA uptake. These results provide novel mechanistic insight into how GPCR heteromers signal. Furthermore, we uncover a previously unknown mechanism where adenosine, in a concentration-dependent manner, acts via a heterocomplex of adenosine receptors in astrocytes to significantly contribute to neurotransmission at the tripartite (neuron-glia-neuron) synapse.

  13. Modulation of diazepam-insensitive GABA(A) receptors by micromolar concentrations of thyroxine and related compounds in vitro.

    PubMed

    Ishibashi, Hitoshi; Witt, Michael-Robin; Nabekura, Junichi; Nielsen, Mogens

    2013-01-15

    The effects of thyroxine and its related compounds on the benzodiazepine-insensitive γ-aminobutyric acid type A (GABA(A)) receptors were studied. Thyroxine at micromolar concentrations potentiated the (3)H-Ro15-4513 binding to rat brain membranes in-vitro in the thalamus, striatum, cortex and hippocampus, but not in cerebellum. In the thalamus, the rank order of potency was the following: 3,3',5,5'-tetraiodothyroacetic acid (TETRAC)>L-thyroxine>3,5-diiodo-l-thyronine (3,5-T2). TETRAC induced a slight potentiation of flumazenil binding to diazepam-sensitive GABA(A) receptors in the thalamus and striatum while no effect was found in cortex and hippocampus. Consequently, we examined whether these compounds could exert their modulatory effect on the currents mediated by benzodiazepine-insensitive GABA(A) receptors. The diazepam-insensitive GABA(A) receptor-mediated currents were recorded from acutely isolated rat ventrobasal thalamic neurons by applying low concentrations of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP). TETRAC and thyroxine at low μM concentrations potentiated the THIP-evoked currents, although 3,5-T2 had no effect on the THIP-induced currents. Ethanol had no effect on the enhancing effects of TETRAC. TETRAC itself evoked GABA(A) receptor-mediated currents at high concentrations beyond 30 μM. Although the effects of TETRAC and thyroxine were observed at non-physiological concentrations of hormones, the present results might lead to new lead structures with specificity to diazepam-insensitive GABA(A) receptor subtypes.

  14. GABA-A Receptor Modulation and Anticonvulsant, Anxiolytic, and Antidepressant Activities of Constituents from Artemisia indica Linn

    PubMed Central

    Khan, Imran; Karim, Nasiara; Ahmad, Waqar; Abdelhalim, Abeer; Chebib, Mary

    2016-01-01

    Artemisia indica, also known as “Mugwort,” has been widely used in traditional medicines. However, few studies have investigated the effects of nonvolatile components of Artemisia indica on central nervous system's function. Fractionation of Artemisia indica led to the isolation of carnosol, ursolic acid, and oleanolic acid which were evaluated for their effects on GABA-A receptors in electrophysiological studies in Xenopus oocytes and were subsequently investigated in mouse models of acute toxicity, convulsions (pentylenetetrazole induced seizures), depression (tail suspension and forced swim tests), and anxiety (elevated plus maze and light/dark box paradigms). Carnosol, ursolic acid, and oleanolic acid were found to be positive modulators of α1β2γ2L GABA-A receptors and the modulation was antagonized by flumazenil. Carnosol, ursolic acid, and oleanolic acid were found to be devoid of any signs of acute toxicity (50–200 mg/kg) but elicited anticonvulsant, antidepressant, and anxiolytic activities. Thus carnosol, ursolic acid, and oleanolic acid demonstrated CNS activity in mouse models of anticonvulsant, antidepressant, and anxiolysis. The anxiolytic activity of all three compounds was ameliorated by flumazenil suggesting a mode of action via the benzodiazepine binding site of GABA-A receptors. PMID:27143980

  15. Co-localization of glycine and gaba immunoreactivity in interneurons in Macaca monkey cerebellar cortex.

    PubMed

    Crook, J; Hendrickson, A; Robinson, F R

    2006-09-15

    of 120 cells/linear mm. Their morphology indicates that they include Golgi and Lugaro cell types with the majority containing both glycine and GABA or glutamic acid decarboxylase. These data are consistent with the proposal that, as in the rat cerebellum, these granular cell layer interneurons corelease glycine and GABA in the primate cerebellum. The patterns of labeling for glycine and GABA within Golgi and Lugaro cells also indicate that there are biochemical sub-types which are morphologically similar. Further, we find that glycine, GABA and glutamic acid decarboxylase identified candelabrum cells adjacent to the Purkinje cells which is the first time that this interneuron has been reported in primate cerebellar cortex. We propose that candelabrum cells, like the majority of Golgi and Lugaro cells, release both glycine and GABA.

  16. Electrophoretic method for the determination of the proportion of gamma-aminobutyric acid in a mixture of labeled neurotransmitter and its catabolites

    SciTech Connect

    Cupello, A.; Rapallino, M.V.; Besio, G.; Mainardi, P.

    1987-01-01

    An electrophoretic method for the separation of gamma-aminobutyric acid (GABA) from its metabolites after GABA-transaminase attack is presented. The method is based on the fact that at neutral pH GABA has no net electrical charge, whereas its major metabolites, succinic acid and Krebs cycle intermediates, are negatively charged. The method appears to be especially suitable for evaluation of true-labeled neurotransmitter within the radioactivity which is found in synaptosomes after labeled GABA-uptake studies.

  17. A new role for GABA: inhibition of tumor cell migration.

    PubMed

    Ortega, Arturo

    2003-04-01

    GABA, the main inhibitory neurotransmitter in the vertebrate brain, participates outside the CNS in diverse functions such as platelet aggregation and the acrosomal reaction in spermatozoa. A recent study now demonstrates that GABA inhibits the migration of colon carcinoma cells, paving the way to the development of specific pharmacological agents that delay or inhibit invasion and metastasis of various cancer types.

  18. A comparison of gamma-aminobutyric acid and the semi-rigid analogues 4-aminotetrolic acid, 4-aminocrotonic acid and imidazole-4-acetic acid on the isolated superior cervical ganglion of the rat.

    PubMed Central

    Bowery, N G; Jones, G P

    1976-01-01

    1 The rat superior cervical ganglion possesses receptors for gamma-aminobutyric acid (GABA). This can be demonstrated in vitro by recording the changes in ganglionic surface potential which occur after the addition of GABA to the bathing solution. 2 The action of three conformationally-restricted analogues of GABA namely 4-aminotetrolic acid (4-ATA), trans 4-aminocrotonic acid (4-ACA) and imidazole-4-acetic acid (IAA) have been examined for activity at this peripheral receptor. 3 All three analogues depolarized the ganglion in a manner similar to GABA. Their actions were transient and were 'occluded' by GABA; also the dose-response curve in each case was parallel to that of GABA. Molar potencies relative to GABA (= 1) were 4-ACA = 1.48, IAA = 0.100, 4-ATA = 0.0028. 4 The action of each analogue could be blocked by the GABA antagonists bicuculline and tetramethylenedisulphotetramine at doses which had relatively little effect on responses to the cholinomimetic carbachol. 5 4-ACA and IAA (1 mM) significantly reduced the ganglionic accumulation of [3H]-GABA (0.2 muM) by 88% and 58% respectively whereas 4-ATA (1 mM), caused no significant reduction in [3H]-GABA accumulation. PMID:1260178

  19. Assignment of the human GABA transporter gene (GABATHG) locus to chromosome 3p24-p25

    SciTech Connect

    Huang, Fang; Fei, Jian; Guo, Li-He

    1995-09-01

    An essential regulatory process of synaptic transmission is the inactivation of released neurotransmitters by the transmitter-specific uptake mechanism, {gamma}-Aminobutyric acid (GABA) is an inhibitory transmitter in the vertebrate central nervous system; its activity is terminated by a high-affinity Na{sup +} and Cl{sup -} -dependent specific GABA transporter (GAT), which carries the neurotransmitter to the presynaptic neuron and/or glial elements surrounding the synaptic cleft. Deficiency of the transporter may cause epilepsy and some other nervous diseases. The human GAT gene (GABATHG), approximately 25 kb in length, has been cloned and sequenced by our colleagues (7). Here the results of the in situ hybridization mapping with the gene are presented. 10 refs., 1 fig.

  20. Treating enhanced GABAergic inhibition in Down syndrome: use of GABA α5-selective inverse agonists.

    PubMed

    Martínez-Cué, Carmen; Delatour, Benoît; Potier, Marie-Claude

    2014-10-01

    Excess inhibition in the brain of individuals carrying an extra copy of chromosome 21 could be responsible for cognitive deficits observed throughout their lives. A change in the excitatory/inhibitory balance in adulthood would alter synaptic plasticity, potentially triggering learning and memory deficits. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mature central nervous system and binds to GABAA receptors, opens a chloride channel, and reduces neuronal excitability. In this review we discuss methods to alleviate neuronal inhibition in a mouse model of Down syndrome, the Ts65Dn mouse, using either an antagonist (pentylenetetrazol) or two different inverse agonists selective for the α5-subunit containing receptor. Both inverse agonists, which reduce inhibitory GABAergic transmission, could rescue learning and memory deficits in Ts65Dn mice. We also discuss safety issues since modulation of the excitatory-inhibitory balance to improve cognition without inducing seizures remains particularly difficult when using GABA antagonists.

  1. Laser photolysis of DPNI-GABA, a tool for investigating the properties and distribution of GABA receptors and for silencing neurons in situ.

    PubMed

    Trigo, Federico F; Papageorgiou, George; Corrie, John E T; Ogden, David

    2009-07-30

    Laser photolysis to release GABA at precisely defined times and locations permits investigation of the distribution of functional GABA(A) receptors in neuronal compartments, the activation kinetics and pharmacology of GABA(A) receptors in situ, and the role of individual neurons in neural circuits by selective silencing with low GABA concentrations. We describe the experimental evaluation and applications of a new nitroindoline-caged GABA, DPNI-GABA, modified to minimize the pharmacological interference commonly found with caged GABA reagents, but retaining the advantages of nitroindoline cages. Unlike the 5-methoxycarbonylmethyl-7-nitroindolinyl-GABA tested previously, DPNI-GABA inhibited GABA(A) receptors with much lower affinity, reducing peak GABA-evoked responses with an IC(50) of approximately 0.5 mM. Most importantly, the kinetics of receptor activation, determined as 10-90% rise-times, were comparable to synaptic events and were little affected by DPNI-GABA present at 1mM concentration, permitting photolysis of DPNI-GABA to mimic synaptic activation of GABA(A) receptors. With a laser spot of 1 microm applied to cerebellar molecular layer interneurons, the spatial resolution of uncaging DPNI-GABA in dendrites was estimated as 2 microm laterally and 7.5 microm focally. Finally, at low DPNI-GABA concentration, photorelease restricted to the area of the soma suppressed spiking in single Purkinje neurons or molecular layer interneurons for periods controlled by the flash intensity and duration. DPNI-GABA has properties better adapted for fast kinetic studies with laser photolysis at GABA(A) receptors than previously reported caged GABA reagents, and can be used in experiments where spatial resolution is determined by the dimensions of the laser light spot.

  2. Study of GABA in Healthy Volunteers: Pharmacokinetics and Pharmacodynamics

    PubMed Central

    Li, Junfeng; Zhang, Zhaoyun; Liu, Xiaoxia; Wang, Yi; Mao, Fei; Mao, Junjun; Lu, Xiaolan; Jiang, Dongdong; Wan, Yun; Lv, Jia-Ying; Cao, Guoying; Zhang, Jing; Zhao, Naiqing; Atkinson, Mark; Greiner, Dale L.; Prud'homme, Gerald J.; Jiao, Zheng; Li, Yiming; Wang, Qinghua

    2015-01-01

    Preclinical studies show that GABA exerts anti-diabetic effects in rodent models of type 1 diabetes. Because little is known about its absorption and effects in humans, we investigated the pharmacokinetics and pharmacodynamics of GABA in healthy volunteers. Twelve subjects were subjected to an open-labeled, three-period trial involving sequential oral administration of placebo, 2 g GABA once, and 2 g GABA three times/day for 7 days, with a 7-day washout between each period. GABA was rapidly absorbed (Tmax: 0.5 ~ 1 h) with the half-life (t1/2) of 5 h. No accumulation was observed after repeated oral GABA administration for 7 days. Remarkably, GABA significantly increased circulating insulin levels in the subjects under either fasting (1.6-fold, single dose; 2.0-fold, repeated dose; p < 0.01) or fed conditions (1.4-fold, single dose; 1.6-fold, repeated dose; p < 0.01). GABA also increased glucagon levels only under fasting conditions (1.3-fold, single dose, p < 0.05; 1.5-fold, repeated dose, p < 0.01). However, there were no significant differences in the insulin-to-glucagon ratio and no significant change in glucose levels in these healthy subjects during the study period. Importantly, GABA significantly decreased glycated albumin levels in the repeated dosing period. Subjects with repeated dosing showed an elevated incidence of minor adverse events in comparison to placebo or the single dosing period, most notably transient discomforts such as dizziness and sore throat. However, there were no serious adverse events observed throughout the study. Our data show that GABA is rapidly absorbed and tolerated in human beings; its endocrine effects, exemplified by increasing islet hormonal secretion, suggest potential therapeutic benefits for diabetes. PMID:26617516

  3. Plant GABA:proline ratio modulates dissemination of the virulence Ti plasmid within the Agrobacterium tumefaciens hosted population.

    PubMed

    Lang, Julien; Faure, Denis

    2016-05-01

    Accumulation of amino acids is a common plant response to several biotic and abiotic stresses, even if the roles of these accumulations remain often poorly understood. In a recent study we measured the levels of different amino acids in tumors of Arabidopsis thaliana induced by the phytopathogen Agrobacterium tumefaciens and correlated these data with changes of gene expressions in both organisms. This led to the demonstration that the non-protein amino acid GABA plays an important role for the adaptation of the bacteria to the plant tumor environment, and especially in the control of the virulent Ti plasmid dissemination. Here we present a model that describes how different GABA:proline ratios in the A. thaliana host may have different impacts on the conjugation of A. tumefaciens Ti plasmid, and advance the view that the amino acid metabolism of plant hosts could be critical for the propagation of the virulence genes in A. tumefaciens populations. PMID:27110651

  4. Obstructive sleep apnea is associated with low GABA and high glutamate in the insular cortex.

    PubMed

    Macey, Paul M; Sarma, Manoj K; Nagarajan, Rajakumar; Aysola, Ravi; Siegel, Jerome M; Harper, Ronald M; Thomas, M Albert

    2016-08-01

    The insular cortex is injured in obstructive sleep apnea (OSA) and responds inappropriately to autonomic challenges, suggesting neural reorganization. The objective of this study was to assess whether the neural changes might result from γ-aminobutyric acid (GABA) and glutamate alterations. We studied 14 OSA patients [mean age ± standard deviation (SD): 47.5 ± 10.5 years; nine male; apnea-hypopnea index (AHI): 29.5 ± 15.6 events h(-1) ] and 22 healthy participants (47.5 ± 10.1 years; 11 male), using magnetic resonance spectroscopy to detect GABA and glutamate levels in insular cortices. We localized the cortices with anatomical scans, and measured neurochemical levels from anterior to mid-regions. Left and right anterior insular cortices showed lower GABA and higher glutamate in OSA versus healthy subjects [GABA left: OSA n = 6: 0.36 ± 0.10 (mean ± SD), healthy n = 5: 0.62 ± 0.18; P < 0.05), right: OSA n = 11: 0.27 ± 0.09, healthy n = 14: 0.45 ± 0.16; P < 0.05; glutamate left: OSA n = 6: 1.61 ± 0.32, healthy n = 8: 0.94 ± 0.34; P < 0.05, right: OSA n = 14: 1.26 ± 0.28, healthy n = 19: 1.02 ± 0.28; P < 0.05]. GABA and glutamate levels were correlated only within the healthy group in the left insula (r: -0.9, P < 0.05). The altered anterior insular levels of GABA and glutamate may modify integration and projections to autonomic areas, contributing to the impaired cardiovascular regulation in OSA.

  5. An Evolutionarily Conserved Switch in Response to GABA Affects Development and Behavior of the Locomotor Circuit of Caenorhabditis elegans

    PubMed Central

    Han, Bingjie; Bellemer, Andrew; Koelle, Michael R.

    2015-01-01

    The neurotransmitter gamma-aminobutyric acid (GABA) is depolarizing in the developing vertebrate brain, but in older animals switches to hyperpolarizing and becomes the major inhibitory neurotransmitter in adults. We discovered a similar developmental switch in GABA response in Caenorhabditis elegans and have genetically analyzed its mechanism and function in a well-defined circuit. Worm GABA neurons innervate body wall muscles to control locomotion. Activation of GABAA receptors with their agonist muscimol in newly hatched first larval (L1) stage animals excites muscle contraction and thus is depolarizing. At the mid-L1 stage, as the GABAergic neurons rewire onto their mature muscle targets, muscimol shifts to relaxing muscles and thus has switched to hyperpolarizing. This muscimol response switch depends on chloride transporters in the muscles analogous to those that control GABA response in mammalian neurons: the chloride accumulator sodium-potassium-chloride-cotransporter-1 (NKCC-1) is required for the early depolarizing muscimol response, while the two chloride extruders potassium-chloride-cotransporter-2 (KCC-2) and anion-bicarbonate-transporter-1 (ABTS-1) are required for the later hyperpolarizing response. Using mutations that disrupt GABA signaling, we found that neural circuit development still proceeds to completion but with an ∼6-hr delay. Using optogenetic activation of GABAergic neurons, we found that endogenous GABAA signaling in early L1 animals, although presumably depolarizing, does not cause an excitatory response. Thus a developmental depolarizing-to-hyperpolarizing shift is an ancient conserved feature of GABA signaling, but existing theories for why this shift occurs appear inadequate to explain its function upon rigorous genetic analysis of a well-defined neural circuit. PMID:25644702

  6. GABA/progesterone-induced polyphosphoinositide (PPI) breakdown and its role in the acrosome reaction of guinea pig spermatozoa in vitro.

    PubMed

    Yuan, Y; Mao, L; Shi, Q; Roldan, E R; Chen, W; Yu, S; Zhuang, Y; Xu, S

    2001-08-01

    To investigate whether GABA/progesterone (P(4)) stimulates PPI breakdown and its role in the acrosome reaction (AR), spermatozoa of guinea pig were preincubated in MCM-LCa(2+) for 5.5 h and then labeled with [(32)P]pi for 1 h. Samples were washed through a three-step gradient Percoll, adjusted to 5x10(7) cells/mL and exposed to 2 mmol/L Ca(2+), 5 micromol/L GABA, 10 micromol/L P(4) and other agents. Lipids were separated by t.l.c. and radioactivity in spots determined by scintillation counting. The AR was assessed by phase-contrast microscopy. The results showed that (i) when spermatozoa were treated with GABA,(32)P-label diminished rapidly in phosphatidylinositol 4, 5-bisphosphate (PIP(2)), phosphatidylinositol 4-phosphate (PIP), and increased in phosphatidic acid (PA). The loss of label from PPI was almost completed by 10 min. The time-course of the AR was much slower than PPI when spermatozoa reached a maximal response by 15 min; (ii) the pattern of PPI hydrolysis and stimulation of AR was similar for the three agonists tested; their potency followed the order A23187>progesterone> or =GABA; (iii) GABA-induced PIP(2) hydrolysis and rise in PA and the AR were prevented by inclusion of 10 mmol/L neomycin; (iv) the loss of PIP(2) labeling and the increase in PA labeling abolished when spermatozoa were exposed to EGTA or Ca(2+) channel blocker. These results indicate that GABA or P(4)-induced PPI breakdown is an important and essential event in the series of changes to membrane fusion during the AR of guinea pig spermatozoa and this effect is mediated via calcium by activation of phosphatidylinositol-specific phospholipase C. PMID:18726415

  7. Cyclohexanol analogues are positive modulators of GABA(A) receptor currents and act as general anaesthetics in vivo.

    PubMed

    Hall, Adam C; Griffith, Theanne N; Tsikolia, Maia; Kotey, Francesca O; Gill, Nikhila; Humbert, Danielle J; Watt, Erin E; Yermolina, Yuliya A; Goel, Shikha; El-Ghendy, Bahaa; Hall, C Dennis

    2011-09-30

    GABA(A) receptors meet all the pharmacological criteria required to be considered important general anaesthetic targets. In the following study, the modulatory effects of various commercially available and novel cyclohexanols were investigated on recombinant human γ-aminobutyric acid (GABA(A), α(1)β(2)γ(2s)) receptors expressed in Xenopus oocytes, and compared to the modulatory effects on GABA currents observed with exposures to the intravenous anaesthetic agent, propofol. Submaximal EC(20) GABA currents were typically enhanced by co-applications of 3-300 μM cyclohexanols. For instance, at 30 μM 2,6-diisopropylcyclohexanol (a novel compound) GABA responses were increased ~3-fold (although similar enhancements were achieved at 3 μM propofol). As regards rank order for modulation by the cyclohexanol analogues at 30 μM, the % enhancements for 2,6-dimethylcyclohexanol~2,6-diethylcyclohexanol~2,6-diisopropylcyclohexanol~2,6-di-sec-butylcyclohexanol ≫2,6-di-tert-butylcyclohexanol~4-tert-butylcyclohexanol>cyclohexanol~cyclopentanol~2-methylcyclohexanol. We further tested the potencies of the cyclohexanol analogues as general anaesthetics using a tadpole in vivo assay. Both 2,6-diisopropylcyclohexanol and 2,6-dimethylcyclohexanol were effective as anaesthetics with EC(50)s of 14.0 μM and 13.1 μM respectively, while other cyclohexanols with bulkier side chains were less potent. In conclusion, our data indicate that cyclohexanols are both positive modulators of GABA(A) receptors currents and anaesthetics. The positioning and size of the alkyl groups at the 2 and 6 positions on the cyclohexanol ring were critical determinants of activity.

  8. Role of GABAB Receptor and L-Arg in GABA-Induced Vasorelaxation in Non-diabetic and Streptozotocin-Induced Diabetic Rat Vessels

    PubMed Central

    Kharazmi, Fatemah; Soltani, Nepton; Rezaei, Sana; Keshavarz, Mansoor; Farsi, Leila

    2015-01-01

    Background: Hypertension is considered an independent risk factor for cardiovascular mortality in diabetic patients. The present study was designed to determine the role of gamma amino butyric acid B (GABAB) receptor and L-arginine (L-Arg) in GABA-induced vasorelaxation in normal and streptozotocin-induced diabetic rat vessels. Methods: Diabetes was induced by a single i.p. injection of streptozotocin (STZ, 60 mg/kg). Eight weeks later, superior mesenteric arteries of all groups were isolated and perfused according to the McGregor method. Results: Baseline perfusion pressure of STZ diabetic rats was significantly higher than non-diabetic rats in both intact and denuded endothelium. In the presence of faclofen, a selective GABAB receptor blocker, GABA-induced relaxation in intact and denuded endothelium mesenteric beds of STZ diabetic rats was suppressed, but this response in non-diabetic rats was not suppressed. Our results showed that in the presence of L-Arg, a nitric oxide precursor, GABA induced vasorelaxation in both diabetic and non-diabetic vessels. Conclusion: From the results of this study, it may be concluded that the vasorelaxatory effect of GABA in diabetic vessel is mediated by the GABAB receptor and nitric oxide, but it seems that in non-diabetic vessel GABAB receptor does not play any role in GABA-induced vasorelaxation, but nitric oxide induced GABA relaxation in non-diabetic vessel. PMID:25864813

  9. The effect of GABA stimulation on GABAA receptor subunit protein and mRNA expression in rat cultured cerebellar granule cells.

    PubMed Central

    Platt, K. P.; Zwartjes, R. E.; Bristow, D. R.

    1996-01-01

    1. After 8 days in vitro, rat cerebellar granule cells were exposed to 1 mM gamma-aminobutyric acid (GABA) for periods of 1, 2, 4, 6, 8 and 10 days. The effect of the GABA exposure on GABAA receptor alpha 1, alpha 6 and beta 2,3 subunit protein expression and alpha 1 and alpha 6 subunit steady-state mRNA levels, was examined using Western blotting and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. 2. GABA exposure for 2 days decreased alpha 1 (35 +/- 10%, mean +/- s.e.mean), beta 2,3 (21 +/- 9%) and alpha 6 (28 +/- 10%) subunit protein expression compared to control levels. The GABA-mediated reduction in alpha 1 subunit expression after 2 days treatment was abolished in the presence of the GABAA receptor antagonist, Ru 5135 (10 microM). 3. GABA exposure for 8 days increased alpha 1 (26 +/- 10%, mean +/- s.e.mean) and beta 2,3 (56 +/- 23%) subunit protein expression over control levels, whereas alpha 6 subunit protein expression remained below control levels (by 38 +/- 10%). However, after 10 days GABA exposure, alpha 6 subunit protein expression was also increased over control levels by 65 +/- 29% (mean +/- s.e.mean). 4. GABA exposure did not change the alpha 1 or alpha 6 subunit steady-state mRNA levels over and 8 day period, nor did it alter the expression of cyclophilin mRNA over 1-8 days. 5. These results suggest that chronic GABA exposure of rat cerebellar granule cells has a bi-phasic effect on GABAA receptor subunit expression that is independent of changes to mRNA levels. Therefore, the regulation of the GABAA receptor expression by chronic agonist treatment appears to involve post-transcriptional and/or post-translational processes. Images Figure 1 Figure 3 Figure 4 PMID:8968548

  10. Gamma-aminobutyric acid loaded halloysite nanotubes and in vitro-in vivo evaluation for brain delivery.

    PubMed

    Kırımlıoğlu, Gülsel Yurtdaş; Yazan, Yasemin; Erol, Kevser; Çengelli Ünel, Çiğdem

    2015-11-30

    Gamma-aminobutyric acid (GABA) is a key neurotransmitter where it usually inhibits impulse transmission. GABA release blockage or postsynaptic reaction were determined to provoke epileptic convulsions. The aim of the present study was the development of brain-targeted, nanosized, nontoxic, biocompatible, highly specific formulations. Incorporation of GABA into halloysite nanotubes (HNT) was performed using different methods. Particle size, zeta potential and pH measurements, morphological, thermal, XRD, FTIR analyses and GABA quantification by validated HPLC method were used for the characterization of the systems prepared. Release pattern of GABA from the nanotubes was determined using a dialysis membrane. Following successful incorporation of GABA into HNTs for brain delivery, nanotube formulation coded HNT-GABA H1 was selected for in vivo studies. Smaller particle size with narrow size distribution, possible HNT-GABA interaction indicated by thermal, XRD and FTIR analyses and prolonged release were the parameters considered in this selection. Moreover, HNT-GABA H1 remained stable for 3-month storage period and showed higher cell viability values than GABA. Rats were used in in vivo studies and potential of anticonvulsant effect of GABA was determined in the pentylenetetrazole model of seizure. HNT-GABA H1 was found to increase latency of seizure, decrease ending time of the convulsion, duration of severe convulsion and mortality rate significantly compared to pure GABA. After administration of HNT-GABA H1, GABA concentration in Stratum corsatum measured by enzyme immune assay showed that it was not significantly higher than GABA administered alone. These findings suggest that GABA loaded HNTs reduces the duration of all phases of convulsion indicating efficient delivery of GABA to all brain areas to interfere with epileptic mechanism.

  11. Modulation of the release of norepinephrine by gamma-aminobutyric acid and morphine in the frontal cerebral cortex of the rat

    SciTech Connect

    Peoples, R.W.

    1989-01-01

    Agents that enhance gamma-aminobutyric acid, or GABA, neurotransmission modulate certain effects of opioids, such as analgesia. Opioid analgesia is mediated in part by norepinephrine in the forebrain. In this study, the interactions between morphine and GABAergic agents on release of ({sup 3}H) norepinephrine from rat frontal cerebral cortical slices were examined. GABA, 5 {times} 10{sup {minus}5}-10{sup {minus}3} M, enhanced potassium stimulated ({sup 3}H) norepinephrine release and reversed the inhibitory effect of morphine in a noncompetitive manner. GABA did not enhance release of ({sup 3}H) norepinephrine stimulated by the calcium ionophore A23187. The effect of GABA was reduced by the GABA{sub A} receptor antagonists bicuculline methiodide or picrotoxin, and by the selective inhibitor of GABA uptake SKF 89976A, but was blocked completely only when bicuculline methiodide and SKF 89976A were used in combination. The GABA{sub A} agonist muscimol, 10{sup {minus}4} M, mimicked the effect of GABA, but the GABA{sub B} agonist ({plus minus})baclofen, 10{sup {minus}4} M, did not affect the release of ({sup 3}H) norepinephrine in the absence or the presence of morphine. Thus GABA appears to produce this effect by stimulating GABA uptake and GABA{sub A}, but not GABA{sub B}, receptors. In contrast to the results that would be predicted for an event involving GABA{sub A} receptors, however, the effect of GABA did not desensitize, and benzodiazepine agonists did not enhance the effect of GABA at any concentration tested between 10{sup {minus}8} and 10{sup {minus}4} M. Thus these receptors may constitute a subclass of GABA{sub A} receptors. These results support a role of GABA uptake and GABA{sub A} receptors in enhancing the release of norepinephrine and modulating its inhibition by opioids in the frontal cortex of the rat.

  12. Novel parent structures for inhibitors of the murine GABA transporters mGAT3 and mGAT4.

    PubMed

    Kragler, Andrea; Höfner, Georg; Wanner, Klaus T

    2005-09-01

    Searching for potent and subtype selective parent structures of the murine gamma-aminobutyric acid (GABA) transporter subtypes mGAT3 and mGAT4 a series of amino acids was characterised in a uniform [3H]GABA uptake test system based on transiently expressed mGAT1-4. From several potent inhibitors showing IC50 values at mGAT3 and mGAT4 in the low microM range cis-4-aminocrotonic acid and (RS)-2,3-diaminopropionic acid turned out to be most subtype selective for these transporters. With (RS)-isoserine--a compound unknown as GAT inhibitor until now--one of the most potent amino acids selectively inhibiting mGAT3 and mGAT4 was found. Furthermore, (2-amino-1,3-thiazol-4-yl)acetic acid was identified as the first parent structure exhibiting a clear, though still moderate, selective inhibition of GABA uptake at mGAT3.

  13. [Pharmacological influences on the brain level and transport of GABA. II) Effect of various psychoactive drugs on brain level and uptake of GABA].

    PubMed

    Gabana, M A; Varotto, M; Saladini, M; Zanchin, G; Battistin, L

    1981-04-30

    The effects of some psychoactive drugs on the level and uptake of GABA in the mouse brain was studied using well standardized procedures, mainely the silica-gel cromatography for determining the GABA content and the brain slices for measuring GABA uptake. It was found that levomepromazine, sulpiride, haloperidol and amytryptiline were without effects on the cerebral level of GABA; it was also found that these drugs do not influence the rates of uptake of GABA by mouse brain slices. Such results do indicate that the psychoactive drugs studied are without effects on the level and uptake of GABA in the brain.

  14. Corelease of acetylcholine and GABA from cholinergic forebrain neurons

    PubMed Central

    Saunders, Arpiar; Granger, Adam J; Sabatini, Bernardo L

    2015-01-01

    Neurotransmitter corelease is emerging as a common theme of central neuromodulatory systems. Though corelease of glutamate or GABA with acetylcholine has been reported within the cholinergic system, the full extent is unknown. To explore synaptic signaling of cholinergic forebrain neurons, we activated choline acetyltransferase expressing neurons using channelrhodopsin while recording post-synaptic currents (PSCs) in layer 1 interneurons. Surprisingly, we observed PSCs mediated by GABAA receptors in addition to nicotinic acetylcholine receptors. Based on PSC latency and pharmacological sensitivity, our results suggest monosynaptic release of both GABA and ACh. Anatomical analysis showed that forebrain cholinergic neurons express the GABA synthetic enzyme Gad2 and the vesicular GABA transporter (Slc32a1). We confirmed the direct release of GABA by knocking out Slc32a1 from cholinergic neurons. Our results identify GABA as an overlooked fast neurotransmitter utilized throughout the forebrain cholinergic system. GABA/ACh corelease may have major implications for modulation of cortical function by cholinergic neurons. DOI: http://dx.doi.org/10.7554/eLife.06412.001 PMID:25723967

  15. Conserved site for neurosteroid modulation of GABA A receptors.

    PubMed

    Hosie, Alastair M; Clarke, Laura; da Silva, Helena; Smart, Trevor G

    2009-01-01

    This study addresses whether the potentiation site for neurosteroids on GABA(A) receptors is conserved amongst different GABA(A) receptor isoforms. The neurosteroid potentiation site was previously identified in the alpha1beta2gamma2S receptor by mutation of Q241 to methionine or leucine, which reduced the potentiation of GABA currents by the naturally occurring neurosteroids, allopregnanolone or tetrahydrodeoxycorticosterone (THDOC). By using heterologous expression of GABA(A) receptors in HEK cells, in combination with whole-cell patch clamp recording methods, a relatively consistent potentiation by allopregnanolone of GABA-activated currents was evident for receptors composed of one alpha subunit isoform (alpha2-5) assembled with beta3 and gamma2S subunits. Using mutant alphabetagamma receptors, the neurosteroid potentiation was universally dependent on the conserved glutamine residue in M1 of the respective alpha subunit. Studying wild-type and mutant receptors composed of alpha4beta3delta subunits revealed that the delta subunit is unlikely to contribute to the neurosteroid potentiation binding site and probably affects the efficacy of potentiation. Thus, in keeping with the ability of neurosteroids to potentiate GABA currents via a broad variety of GABA(A) receptor isoforms in neurons, the potentiation site is structurally highly conserved on this important neurotransmitter receptor family.

  16. Comparative activities of the enantiomeric GABA(B) receptor agonists CGP 44532 and 44533 in central and peripheral tissues.

    PubMed

    Ong, J; Bexis, S; Marino, V; Parker, D A; Kerr, D I; Froestl, W

    2001-01-19

    In neocortical slices maintained in Mg(2+)-free Krebs medium, the gamma-aminobutyric acid (GABA(B)) receptor agonists baclofen, (3-amino-2(S)-hydroxypropyl)methylphosphinic acid (CGP 44532), and its (R)-enantiomer CGP 44533 depressed the frequency of spontaneous discharges in a concentration-dependent manner (EC(50)=10, 6.5, and 50 microM, respectively). These effects were reversibly antagonised by the GABA(B) receptor antagonist (+)-(S)-5,5 dimethylmorpholinyl-2-acetic acid (Sch 50911) (3, 10, and 30 microM) (average pA(2) value=6.0+/-0.2). In neocortical wedges, baclofen, CGP 44532 and CGP 44533 elicited concentration-dependent hyperpolarisations (the EC(50)s were 14, 7.5 and 16 microM, respectively) sensitive to Sch 50911 (1, 5, 10 microM) (average pA(2) value=6.0+/-0.1), whilst they also depressed ileal electrically elicited cholinergic twitch contractions (EC(50)=11, 7, and 50 microM) that were antagonised by Sch 50911 (average pA(2) value=6.0+/-0.1). In electrically stimulated brain slices preloaded with [3H]GABA, baclofen, CGP 44532 and CGP 44533 decreased [3H]GABA release (IC(50)=5, 0.45, and 10 microM); this effect was reversed by Sch 50911 (50 microM). It is concluded that CGP 44532 is a far more potent agonist at GABA(B) autoreceptors than at central or peripheral heteroreceptors.

  17. Acute Modulation of Cortical Glutamate and GABA Content by Physical Activity.

    PubMed

    Maddock, Richard J; Casazza, Gretchen A; Fernandez, Dione H; Maddock, Michael I

    2016-02-24

    Converging evidence demonstrates that physical activity evokes a brain state characterized by distinctive changes in brain metabolism and cortical function. Human studies have shown that physical activity leads to a generalized increase in electroencephalography power across regions and frequencies, and a global increase in brain nonoxidative metabolism of carbohydrate substrates. This nonoxidative consumption of carbohydrate has been hypothesized to include increased de novo synthesis of amino acid neurotransmitters, especially glutamate and GABA. Here, we conducted a series of proton magnetic resonance spectroscopy studies in human volunteers before and after vigorous exercise (≥80% of predicted maximal heart rate). Results showed that the resonance signals of both glutamate and GABA increased significantly in the visual cortex following exercise. We further demonstrated a similar increase in glutamate following exercise in an executive region, the anterior cingulate cortex. The increase in glutamate was similar when using echo times of 30 and 144 ms, indicating that exercise-related T2 relaxation effects across this range of relaxation times did not account for the findings. In addition, we found preliminary evidence that more physical activity during the preceding week predicts higher resting glutamate levels. Overall, the results are consistent with an exercise-induced expansion of the cortical pools of glutamate and GABA, and add to a growing understanding of the distinctive brain state associated with physical activity. A more complete understanding of this brain state may reveal important insights into mechanisms underlying the beneficial effects of physical exercise in neuropsychiatric disorders, neurorehabilitation, aging, and cognition.

  18. Linking GABA and glutamate levels to cognitive skill acquisition during development.

    PubMed

    Cohen Kadosh, Kathrin; Krause, Beatrix; King, Andrew J; Near, Jamie; Cohen Kadosh, Roi

    2015-11-01

    Developmental adjustments in the balance of excitation and inhibition are thought to constrain the plasticity of sensory areas of the cortex. It is unknown however, how changes in excitatory or inhibitory neurochemical expression (glutamate, γ-aminobutyric acid (GABA)) contribute to skill acquisition during development. Here we used single-voxel proton magnetic resonance spectroscopy (1H-MRS) to reveal how differences in cortical glutamate vs. GABA ratios relate to face proficiency and working memory abilities in children and adults. We show that higher glutamate levels in the inferior frontal gyrus correlated positively with face processing proficiency in the children, but not the adults, an effect which was independent of age-dependent differences in underlying cortical gray matter. Moreover, we found that glutamate/GABA levels and gray matter volume are dissociated at the different maturational stages. These findings suggest that increased excitation during development is linked to neuroplasticity and the acquisition of new cognitive skills. They also offer a new, neurochemical approach to investigating the relationship between cognitive performance and brain development across the lifespan. PMID:26350618

  19. Retrograde release of endocannabinoids inhibits presynaptic GABA release to second-order baroreceptive neurons in NTS.

    PubMed

    Chen, Chao-Yin; Bonham, Ann C; Dean, Caron; Hopp, Francis A; Hillard, Cecilia J; Seagard, Jeanne L

    2010-12-01

    In prior studies, we found that activation of cannabinoid-1 receptors in the nucleus tractus solitarii (NTS) prolonged baroreflex-induced sympathoinhibition in rats. In many regions of the central nervous system, activation of cannabinoid-1 receptors presynaptically inhibits γ-aminobutyric acid (GABA) release, disinhibiting postsynaptic neurons. To determine if cannabinoid-1 receptor-mediated presynaptic inhibition of GABA release occurs in the NTS, we recorded miniature inhibitory postsynaptic currents in anatomically identified second-order baroreceptive NTS neurons in the presence of ionotropic glutamate receptor antagonists and tetrodotoxin. The cannabinoid-1 receptor agonists, WIN 55212-2 (0.3-30 μM) and methanandamide (3 μM) decreased the frequency of miniature inhibitory postsynaptic currents in a concentration-dependent manner, an effect that was blocked by the cannabinoid-1 receptor antagonist, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM 251, 5 μM). Importantly, depolarization of second-order baroreceptive neurons decreased the frequency of miniature inhibitory postsynaptic currents; an effect which was blocked by the cannabinoid-1 receptor antagonist. The data indicate that depolarization of second-order baroreceptive NTS neurons induces endocannabinoid release from the neurons, leading to activation of presynaptic cannabinoid-1 receptors, inhibition of GABA release and subsequent enhanced baroreflex signaling in the NTS. The data suggest that endocannabinoid signaling in the NTS regulates short-term synaptic plasticity and provide a mechanism for endocannabinoid modulation of central baroreflex control.

  20. Extrasynaptic GABA(A) receptors in the brainstem and spinal cord: structure and function.

    PubMed

    Delgado-Lezama, Rodolfo; Loeza-Alcocer, Emanuel; Andrés, Carmen; Aguilar, Justo; Guertin, Pierre A; Felix, Ricardo

    2013-01-01

    γ-aminobutyric acid (GABA) plays many of its key roles in embryonic development and functioning of the central nervous system (CNS) by acting on ligand gated chloride-permeable channels known as GABAA receptors (GABAAR). Classically, GABAARmediated synaptic communication is tailored to allow rapid and precise transmission of information to synchronize the activity of large populations of cells to generate and maintain neuronal networks oscillations. An alternative type of inhibition mediated by GABAA receptors, initially described about 25 years ago, is characterized by a tonic activation of receptors that react to ambient extracellular GABA. The receptors that mediate this action are wide-spread throughout the nerve cells but are located distant from the sites of GABA release, and therefore they have been called extrasynaptic GABAA receptors. The molecular nature of the extrasynaptic GABAA receptors and the tonic inhibitory current they generate have been characterized in many brain structures, and due to its relevance in controlling neuron excitability they have become attractive pharmacological targets for a variety of neurological disorders such as schizophrenia, epilepsy and Parkinson disease. In the spinal cord, early studies have implicated these receptors in anesthesia, chronic pain, motor control, and locomotion. This review highlights past and present developments in the field of extrasynaptic GABAA receptors and emphasizes their subunit containing distribution and physiological role in the spinal cord. PMID:23360278

  1. Bioassay-guided fractionation of lemon balm (Melissa officinalis L.) using an in vitro measure of GABA transaminase activity.

    PubMed

    Awad, Rosalie; Muhammad, Asim; Durst, Tony; Trudeau, Vance L; Arnason, John T

    2009-08-01

    A novel pharmacological mechanism of action for the anxiolytic botanical Melissa officinalis L. (lemon balm) is reported. The methanol extract was identified as a potent in vitro inhibitor of rat brain GABA transaminase (GABA-T), an enzyme target in the therapy of anxiety, epilepsy and related neurological disorders. Bioassay-guided fractionation led to the identification and isolation of rosmarinic acid (RA) and the triterpenoids, ursolic acid (UA) and oleanolic acid (OA) as active principles. Phytochemical characterization of the crude extract determined RA as the major compound responsible for activity (40% inhibition at 100 microg/mL) since it represented approximately 1.5% of the dry mass of the leaves. Synergistic effects may also play a role. PMID:19165747

  2. Bioassay-guided fractionation of lemon balm (Melissa officinalis L.) using an in vitro measure of GABA transaminase activity.

    PubMed

    Awad, Rosalie; Muhammad, Asim; Durst, Tony; Trudeau, Vance L; Arnason, John T

    2009-08-01

    A novel pharmacological mechanism of action for the anxiolytic botanical Melissa officinalis L. (lemon balm) is reported. The methanol extract was identified as a potent in vitro inhibitor of rat brain GABA transaminase (GABA-T), an enzyme target in the therapy of anxiety, epilepsy and related neurological disorders. Bioassay-guided fractionation led to the identification and isolation of rosmarinic acid (RA) and the triterpenoids, ursolic acid (UA) and oleanolic acid (OA) as active principles. Phytochemical characterization of the crude extract determined RA as the major compound responsible for activity (40% inhibition at 100 microg/mL) since it represented approximately 1.5% of the dry mass of the leaves. Synergistic effects may also play a role.

  3. Dorsal raphe 5-HT(2C) receptor and GABA networks regulate anxiety produced by cocaine withdrawal.

    PubMed

    Craige, Caryne P; Lewandowski, Stacia; Kirby, Lynn G; Unterwald, Ellen M

    2015-06-01

    The serotonin system is intimately linked to both the mediation of anxiety and long-term effects of cocaine, potentially through interaction of inhibitory 5-HT2C receptor and gamma-aminobutyric acid (GABA) networks. This study characterized the function of the dorsal raphe (DR) 5-HT2C receptor and GABA network in anxiety produced by chronic cocaine withdrawal. C57BL/6 mice were injected with saline or cocaine (15 mg/kg) 3 times daily for 10 days, and tested on the elevated plus maze 30 min, 25 h, or 7 days after the last injection. Cocaine-withdrawn mice showed heightened anxiety-like behavior at 25 h of withdrawal, as compared to saline controls. Anxiety-like behavior was not different when mice were tested 30 min or 7 days after the last cocaine injection. Electrophysiology data revealed that serotonin cells from cocaine-withdrawn mice exhibited increased GABA inhibitory postsynaptic currents (IPSCs) in specific DR subregions dependent on withdrawal time (25 h or 7 d), an effect that was absent in cells from non-withdrawn mice (30 min after the last cocaine injection). Increased IPSC activity was restored to baseline levels following bath application of the 5-HT2C receptor antagonist, SB 242084. In a separate cohort of cocaine-injected mice at 25 h of withdrawal, both global and intra-DR blockade of 5-HT2C receptors prior to elevated plus maze testing attenuated anxiety-like behavior. This study demonstrates that DR 5-HT2C receptor blockade prevents anxiety-like behavior produced by cocaine withdrawal, potentially through attenuation of heightened GABA activity, supporting a role for the 5-HT2C receptor in mediating anxiety produced by cocaine withdrawal.

  4. Mechanisms of carbacholine and GABA action on resting membrane potential and Na+/K+-ATPase of Lumbricus terrestris body wall muscles.

    PubMed

    Volkov, Eugeny M; Nurullin, Leniz F; Volkov, Michael E; Nikolsky, Eugeny E; Vyskočil, Frantisek

    2011-04-01

    This work was aimed to identify the action of several ion channel and pump inhibitors as well as nicotinic, GABAergic, purinergic and serotoninergic drugs on the resting membrane potential (RMP) and assess the role of cholinergic and GABAergic sensitivity in earthworm muscle electrogenesis. The nicotinic agonists acetylcholine (ACh), carbacholine (CCh) and nicotine depolarize the RMP at concentrations of 5 μM and higher. The nicotinic antagonists (+)tubocurarine, α-bungarotoxin, muscarinic antagonists atropine and hexamethonium do not remove or prevent the CCh-induced depolarization. Verapamil, tetrodotoxin, removal of Cl(-) and Ca(2+) from the solution also cannot prevent the depolarization by CCh. In a Na(+)-free medium, however, CCh lost this depolarization ability and this indicates that the drug opens the sodium permeable pathway. Serotonin, glutamate, glycine, adenosine triphosphate (ATP) and cis-4-aminocrotonic acid (GABA(C) receptor antagonist) had no effect on the RMP. On the other hand, isoguvacin, γ-aminobutyric acid (GABA) and baclofen (GABA(B) receptor agonist) hyperpolarized the RMP. Ouabain, bicucullin (GABA(A) antagonist) and phaclofen (GABA(B) antagonist), as well as the removal of Cl(-), suppressed the effect of GABA and baclofen. CCh did not enhance the depolarization generated by ouabain but, on the other hand, hindered the hyperpolarizing activity of baclofen both in the absence and presence of atropine and (+)tubocurarine. The long-term application of CCh depolarizes the RMP primarily by inhibiting the Na(+)/K(+)-ATPase. The muscle membrane also contains A and B type GABA binding sites, the activation of which increases the RMP at the expense of increasing the action of ouabain- and Cl(-) -sensitive electrogenic pumps. PMID:21184841

  5. Burst firing in gonadotrophin-releasing hormone neurones does not require ionotrophic GABA or glutamate receptor activation.

    PubMed

    Lee, K; Liu, X; Herbison, A E

    2012-12-01

    Burst firing is a feature of many neuroendocrine cell types, including the hypothalamic gonadotrophin-releasing hormone (GnRH) neurones that control fertility. The role of intrinsic and extrinsic influences in generating GnRH neurone burst firing is presently unclear. In the present study, we investigated the role of fast amino acid transmission in burst firing by examining the effects of receptor antagonists on bursting displayed by green fluorescent protein GnRH neurones in sagittal brain slices prepared from adult male mice. Blockade of AMPA and NMDA glutamate receptors with a cocktail of CNQX and AP5 was found to have no effects on burst firing in GnRH neurones. The frequency of bursts, dynamics of individual bursts, or percentage of firing clustered in bursts was not altered. Similarly, GABA(A) receptor antagonists bicuculline and picrotoxin had no effects upon burst firing in GnRH neurones. To examine the importance of both glutamate and GABA ionotrophic signalling, a cocktail including picrotoxin, CNQX and AP5 was used but, again, this was found to have no effects on GnRH neurone burst firing. To further question the impact of endogenous amino acid release on burst firing, electrical activation of anteroventral periventricular nuclei GABA/glutamate inputs to GnRH neurones was undertaken and found to have no impact on burst firing. Taken together, these observations indicate that bursting in GnRH neurones is not dependent upon acute ionotrophic GABA and glutamate signalling and suggest that extrinsic inputs to GnRH neurones acting through AMPA, NMDA and GABA(A) receptors are unlikely to be required for burst initiation in these cells.

  6. Frequent coexpression of the vesicular glutamate transporter 1 and 2 genes, as well as coexpression with genes for choline acetyltransferase or glutamic acid decarboxylase in neurons of rat brain.

    PubMed

    Danik, Marc; Cassoly, Estelle; Manseau, Frédéric; Sotty, Florence; Mouginot, Didier; Williams, Sylvain

    2005-08-15

    It is widely believed that expression of the vesicular glutamate transporter genes VGLUT1 and VGLUT2 is restricted to glutamatergic neurons and that the two transporters segregate in different sets of neurons. Using single-cell multiplex RT-PCR (sc-RT-mPCR), we show that VGLUT1 and VGLUT2 mRNAs were coexpressed in most of the sampled neurons from the rat hippocampus, cortex, and cerebellum at postnatal Day (P)14 but not P60. In accordance, changes in VGLUT1 and VGLUT2 mRNA concentrations were found to occur in these and other brain areas between P14 and P60, as revealed by semiquantitative RT-PCR and quantitated by ribonuclease protection assay. VGLUT1 and -2 coexpression in the hippocampal formation is supported further by in situ hybridization data showing that virtually all cells in the CA1-CA3 pyramidal and granule cell layers were highly positive for both transcripts until P14. It was revealed using sc-RT-mPCR that transcripts for VGLUT1 and VGLUT2 were also present in neurons of the cerebellum, striatum, and septum that expressed markers for gamma-aminobutyric acid (GABA)ergic or cholinergic phenotypes, as well as in hippocampal cells containing transcripts for the glial fibrillary acidic protein. Our study suggests that VGLUT1 and VGLUT2 proteins may often transport glutamate into vesicles within the same neuron, especially during early postnatal development, and that they are expressed widely in presumed glutamatergic, GABAergic, and cholinergic neurons, as well as in astrocytes. Furthermore, our study shows that such coexpressing neurons remain in the adult brain and identifies several areas that contain them in both young and adult rats. PMID:15983996

  7. Metabotropic GABA signalling modulates longevity in C. elegans

    PubMed Central

    Chun, Lei; Gong, Jianke; Yuan, Fengling; Zhang, Bi; Liu, Hongkang; Zheng, Tianlin; Yu, Teng; Xu, X. Z. Shawn; Liu, Jianfeng

    2015-01-01

    The nervous system plays an important but poorly understood role in modulating longevity. GABA, a prominent inhibitory neurotransmitter, is best known to regulate nervous system function and behaviour in diverse organisms. Whether GABA signalling affects aging, however, has not been explored. Here we examined mutants lacking each of the major neurotransmitters in C. elegans, and find that deficiency in GABA signalling extends lifespan. This pro-longevity effect is mediated by the metabotropic GABAB receptor GBB-1, but not ionotropic GABAA receptors. GBB-1 regulates lifespan through G protein-PLCβ signalling, which transmits longevity signals to the transcription factor DAF-16/FOXO, a key regulator of lifespan. Mammalian GABAB receptors can functionally substitute for GBB-1 in lifespan control in C. elegans. Our results uncover a new role of GABA signalling in lifespan regulation in C. elegans, raising the possibility that a similar process may occur in other organisms. PMID:26537867

  8. [GABA-Receptors in Modulation of Fear Memory Extinction].

    PubMed

    Dubrovina, N I

    2016-01-01

    GABA is the major inhibitory neurotransmitter in the central nervous system determining the efficacy of neuronal interaction. GABA-receptors play a key role in different aspects of fear memory--acquisition and consolidation, retention, reconsolidation and extinction. Extinction is an important behavioural phenomenon which allows organism to adapt its behavior to a changing environment. Extinction of fear memory is a form of new inhibitory learning which interferes with expression of the initial acquired fear conditioning. Resistance to extinction is symptom of depression and posttraumatic stress disorder. The aim of the present review was to summarize own and literary data about GABAergic modulation of fear extinction and pharmacological correction of extinction impairment at influences on GABA(A)- and GABA(B)- receptors. PMID:27538279

  9. Biochemical and electrophysiological characteristics of mammalian GABA receptors.

    PubMed

    Enna, S J; Gallagher, J P

    1983-01-01

    The concept that GABA is a neurotransmitter in the mammalian CNS is supported by both electrophysiological and biochemical data. Whereas the electrophysiological studies are essential for demonstrating a specific functional response to GABA, the biochemical approach is useful for characterizing the molecular properties of this site. As a result of these studies the concept of the GABA receptor has progressed from a simple model of a single recognition site associated with a chloride channel to a more complex structure having a variety of interacting components. Thus, both electrophysiological and biochemical data support the existence of at least two pharmacologically distinct types of GABA receptors, based on the sensitivity to bicuculline. Also, anatomically, there appear to be two different types of receptors, those located postsynaptically on the soma or dendrites of a neighboring cell and those found presynaptically on GABAergic and other neurotransmitter terminals. From biochemical studies it appears that the GABA receptor may be composed of at least three distinct interacting components. One of these, the recognition site, may exist in two conformations, with one preferring agonists and the other having a higher affinity for antagonists. Ion channels may be considered a second component, with some of these regulating the passage of chloride ion, whereas others may be associated with calcium transport. The third major element of GABA receptors appears to be a benzodiazepine recognition site, although only a certain population of GABA receptors may be endowed with this property. In addition to these, the GABA receptor complex appears to contain substances that modulate the recognition site by influencing the availability of higher affinity binding proteins. It would appear therefore that changes affecting any one of these constituents can influence the characteristics of the others. While increasing the complexity of the system, this arrangement makes for a

  10. Inter- and intracellular relationship of substance P-containing neurons with serotonin and GABA in the dorsal raphe nucleus: combination of autoradiographic and immunocytochemical techniques

    SciTech Connect

    Magoul, R.; Onteniente, B.; Oblin, A.; Calas, A.

    1986-06-01

    Double-labeling experiments were performed at the electron microscopic level in the dorsal raphe nucleus of rat, in order to study the inter- and intracellular relationship of substance P with gamma-aminobutyric acid (GABA) and serotonin. Autoradiography for either (/sup 3/H)serotonin or (/sup 3/H)GABA was coupled, on the same tissue section, with peroxidase-antiperoxidase immunocytochemistry for substance P in colchicine-treated animals. Intercellular relationships were represented by synaptic contacts made by (/sup 3/H)serotonin-labeled terminals on substance P-containing somata and dendrites, and by substance P-containing terminals on (/sup 3/H)GABA-labeled cells. Intracellular relationships were suggested by the occurrence of the peptide within (/sup 3/H)serotonin-containing and (/sup 3/H)GABA-containing cell bodies and fibers. Doubly labeled varicosities of the two kinds were also observed in the supraependymal plexus adjacent to the dorsal raphe nucleus. The results demonstrated that, in addition to reciprocal synaptic interactions made by substance P with serotonin and GABA, the dorsal raphe nucleus is the site of intracellular relationships between the peptide and either the amine or the amino acid.

  11. Experiment K-6-18. Study of muscarinic and gaba (benzodiazepine) receptors in the sensory-motor cortex, hippcampus and spinal code

    NASA Technical Reports Server (NTRS)

    Daunton, N.; Damelio, F.; Krasnov, I.

    1990-01-01

    Frontal lobe samples of rat brains flown aboard Cosmos 1887 were processed for the study of muscarinic (cholinergic) and GABA (benzodiazepine) receptors and for immunocytochemical localization of the neurotransmitter gamma-aminobutyric acid (GABA) and glial fibrillary acidic protein (GFAP). Although radioactive labeling of both muscarinic cholinergic and GABA (benzodiazepine) receptors proved to be successful with the techniques employed, distinct receptor localization of individual laminae of the frontal neocortex was not possible since the sampling of the area was different in the various groups of animals. In spite of efforts made for proper orientation and regional identification of laminae, it was found that a densitometric (quantitation of autoradiograms) analysis of the tissue did not contribute to the final interpretation of the effects of weightlessness on these receptors. As to the immunocytochemical studies the use of both markers, GFAP and GABA antiserum, confirmed the suitability of the techniques for use in frozen material. However, similar problems to those encountered in the receptor studies prevented an adequate interpretation of the effects of micro-G exposure on the localization and distribution of GABA and GFAP. This study did, however, confirm the feasibility of investigating neurotransmitters and their receptors in future space flight experiments.

  12. Effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine by their transporters heterologously expressed in COS cells and in rat brain synaptosomes.

    PubMed

    Sugimura, M; Kitayama, S; Morita, K; Irifune, M; Takarada, T; Kawahara, M; Dohi, T

    2001-08-01

    Although the neurotransmitter uptake system is considered a possible target for the presynaptic action of anesthetic agents, observations are inconsistent concerning effects on the transporter and their clinical relevance. The present study examined the effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine in COS cells heterologously expressing the transporters for these neurotransmitters and in the rat brain synaptosomes. Halothane and isoflurane, but not thiamylal or thiopental, significantly inhibited uptake by COS cell systems of GABA, dopamine and glutamic acid in a concentration-dependent manner within clinically relevant ranges for anesthesia induced by these agents. Similarly, in synaptosomes halothane and isoflurane but not thiopental significantly suppressed the uptake of GABA and glutamic acid, respectively. These results do not support the hypothesis that volatile and intravenous anesthetics exert their action via specific inhibition of GABA uptake to enhance inhibitory GABAergic neuronal activity. Rather, they suggest that presynaptic uptake systems for various neurotransmitters including GABA may be the molecular targets for volatile anesthetic agents.

  13. GABA withdrawal syndrome: a model of the epilepsia partialis continua.

    PubMed

    Kunimoto, M; Tanaka, T; Fukuda, H; Yonemasu, Y; Naquet, R

    1990-06-01

    After the chronic infusion of GABA into the cortex of baboon Papio Papio, a sudden stop of the infusion provoked cortical epileptic discharges around the infused area. And the baboon exhibited partial epilepsy for about 3 days. The result suggested that GABA withdrawal syndrome should be a good model not only to understand the mechanism of epilepsia partialis continua but also partial epilepsy with a circumscribed cortical focus.

  14. [Influence of GABA(C)-Receptor Antagonist on Formation of Evoked Potentials in Columns of the Rat Somatosensory Cortex].

    PubMed

    Matukhno, A E; Lysenko, L V; Andreeva, Y V; Sukhov, A G

    2015-01-01

    Microelectrode studies of evoked potentials (EP) in neuronal column of rats barrel cortex show activating action of selective GABA(C)-receptor antagonist 1,2,5,6-tetrahydropyridin-4-yl-methylphosphinic acid (TPMPA) mainly on secondary components of EP of supragranular afferent layers of column compared to the efferent infragranular layers. These data suggest localization of GABA(C)-receptors on pre- synaptic terminals of thalamo-cortical glutamatergic afferents and ascending apical dendrites of pyramidal cells. A blockade of GABA(C)-receptors with the selective antagonist TPM PA leads to dose-dependent afferent depolarization with development of presynaptic inhibition and suppression of primary components of EP GABA(C)-receptors blocker produces different effects on secondary components of EP in supragranular layers of the cortex caused by the development of neuronal after hyperpolarization followed by high-amplitude primary response and afterdepolarization followed by low-amplitude primary responses with subsequent activation of different voltage-gated channels and formation of different level of cortical direct current potential gradients.

  15. Identification of GABA A receptor modulators in Kadsura longipedunculata and assignment of absolute configurations by quantum-chemical ECD calculations

    PubMed Central

    Zaugg, Janine; Ebrahimi, Samad Nejad; Smiesko, Martin; Baburin, Igor; Hering, Steffen; Hamburger, Matthias

    2011-01-01

    A petroleum ether extract of Kadsura longipedunculata enhanced the GABA-induced chloride current (IGABA) by 122.5 ± 0.3% (n = 2) when tested at 100 μg/ml in Xenopus laevis oocytes expressing GABA A receptors (α1β2γ2S subtype) in two-microelectrode voltage clamp measurements. Thirteen compounds were subsequently identified by HPLC-based activity profiling as responsible for GABA A receptor activity and purified in preparative scale. 6-Cinnamoyl-6,7-dihydro-7-myrceneol and 5,6-dihydrocuparenic acid were thereby isolated for the first time. The determination of the absolute stereochemistry of these compounds was achieved by comparison of experimental and calculated ECD spectra. All but one of the 13 isolated compounds from K. longipedunculata potentiated IGABA through GABA A receptors composed of α1β2γ2S subunits in a concentration-dependent manner. Potencies ranged from 12.8 ± 3.1 to 135.6 ± 85.7 μM, and efficiencies ranged from 129.7 ± 36.8% to 885.8 ± 291.2%. The phytochemical profiles of petroleum ether extracts of Kadsura japonica fruits (114.1 ± 2.6% potentiation of IGABA at 100 μg/ml, n = 2), and Schisandra chinensis fruits (inactive at 100 μg/ml) were compared by HPLC-PDA-ESIMS with that of K. longipedunculata. PMID:21889177

  16. Cloning of the mouse GABA-benzodiazepine receptor. alpha. 1 subunit in a study of alcohol neurosensitivity

    SciTech Connect

    Keir, W.J.; Deitrich, R.A.; Sikela, J.M. )

    1989-02-09

    The inhibitory action of gamma amino butyric acid (GABA) is mediated by its binding to the benzodiazepine (BDZ) receptor and opening of a chloride channel. This receptor contains a variety of binding sites for several behavorially active drugs. Recent studies with SS and LS mice which were selected for differential neurosensitivity to ethanol, suggest that the GABAergic system plays a role in this differential sensitivity. Thus genes controlling the GABAergic system may also influence the acute hypnotic actions of ethanol. As a fist step towards verifying this hypothesis we have cloned and partially sequenced the mouse GABA-BDZ {alpha}1 subunit cDNA using a 40 bp oligonucleotide derived from the N terminus of a published bovine {alpha} subunit cDNA. A positive clone from a mouse brain cDNA library was identified and contains an insert of approximately 2.5 Kb. Partial sequence analysis indicates that this clone corresponds to the mouse homolog of the {alpha}1 subunit of the GABA-BDZ receptor. This clone is being used as a probe to identify restriction fragment length polymorphisms in several mouse genotypes which differ in their neurosensitivity to ethanol in an attempt to identify molecular genetic changes in the GABA-BDZ receptor that are related to differential ethanol neurosensitivity.

  17. Stress metabolism in green coffee beans (Coffea arabica L.): expression of dehydrins and accumulation of GABA during drying.

    PubMed

    Kramer, Daniela; Breitenstein, Björn; Kleinwächter, Maik; Selmar, Dirk

    2010-04-01

    In order to produce tradeable standard green coffee, processed beans must be dried. The drying procedure affects the abundance of relevant aroma substances, e.g. carbohydrates. Using molecular tools, the corresponding metabolic basis is analyzed. A decrease in water potential of the still living coffee seeds induces massive drought stress responses. As a marker for these stress reactions, accumulation of a general stress metabolite, GABA (gamma-aminobutyric acid), and associated gene expression of drought stress-associated dehydrins were monitored. The results of this study indicate that metabolism in drying coffee beans is quite complex since several events trigger accumulation of GABA. The first peak of GABA accumulation during drying is correlated with expression of isocitrate lyase and thus with ongoing germination processes in coffee seeds. Two subsequent peaks of GABA accumulation correspond to maxima of dehydrin gene expression and are thought to be induced directly by drought stress in the embryo and endosperm tissue, respectively. Apart from the significance for understanding basic seed physiology, metabolic changes in coffee seeds during processing provide valuable information for understanding the role and effect of the steps of green coffee processing on the quality of the resulting coffee.

  18. [Influence of GABA(C)-Receptor Antagonist on Formation of Evoked Potentials in Columns of the Rat Somatosensory Cortex].

    PubMed

    Matukhno, A E; Lysenko, L V; Andreeva, Y V; Sukhov, A G

    2015-01-01

    Microelectrode studies of evoked potentials (EP) in neuronal column of rats barrel cortex show activating action of selective GABA(C)-receptor antagonist 1,2,5,6-tetrahydropyridin-4-yl-methylphosphinic acid (TPMPA) mainly on secondary components of EP of supragranular afferent layers of column compared to the efferent infragranular layers. These data suggest localization of GABA(C)-receptors on pre- synaptic terminals of thalamo-cortical glutamatergic afferents and ascending apical dendrites of pyramidal cells. A blockade of GABA(C)-receptors with the selective antagonist TPM PA leads to dose-dependent afferent depolarization with development of presynaptic inhibition and suppression of primary components of EP GABA(C)-receptors blocker produces different effects on secondary components of EP in supragranular layers of the cortex caused by the development of neuronal after hyperpolarization followed by high-amplitude primary response and afterdepolarization followed by low-amplitude primary responses with subsequent activation of different voltage-gated channels and formation of different level of cortical direct current potential gradients. PMID:26841661

  19. Correlation between GABA(A) receptor density and vagus nerve stimulation in individuals with drug-resistant partial epilepsy.

    PubMed

    Marrosu, Francesco; Serra, Alessandra; Maleci, Alberto; Puligheddu, Monica; Biggio, Giovanni; Piga, Mario

    2003-01-01

    Vagus nerve stimulation (VNS) is an important option for the treatment of drug-resistant epilepsy. Through delivery of a battery-supplied intermittent current, VNS protects against seizure development in a manner that correlates experimentally with electrophysiological modifications. However, the mechanism by which VNS inhibits seizures in humans remains unclear. The impairment of gamma-aminobutyric acid (GABA)-mediated neuronal inhibition associated with epilepsy has suggested that GABA(A) receptors might contribute to the therapeutic efficacy of VNS. We have now applied single photon emission computed tomography (SPECT) with the benzodiazepine receptor inverse agonist [123I]iomazenil to examine cortical GABA(A) receptor density (GRD) before and 1 year after implantation of a VNS device in 10 subjects with drug-resistant partial epilepsy. VNS therapeutic responses resulted significantly correlated with the normalization of GRD. Moreover, a comparable control group, scheduled for a possible VNS implant, failed to show significant GRD variations after 1 year of a stable anti-epileptic treatment. These results suggest that VNS may modulate the cortical excitability of brain areas associated with epileptogenesis and that GABA(A) receptor plasticity contributes to this effect.

  20. Thienyl-GABA derivatives as specific baclofen agonists in the rat and cat spinal cord in vivo.

    PubMed

    Lacey, G; Berthelot, P; Vaccher, C; Flouquet, N; Vaccher, M P; Debaert, M; Curtis, D R

    1993-09-01

    The depression of the amplitude of extracellularly recorded monosynaptic excitatory field potentials in the lumbar spinal cord of pentobarbitone anaesthetised rats and cats by three thienyl derivatives of GABA: 4-amino-3-(2-thienyl)-butanoic acid; 4-amino-3-(2-thienyl-5-methyl)-butanoic acid and 4-amino-3-(2-thienyl-5-chloro)-butanoic acid was reversibly blocked by the (-)-baclofen antagonist 3-aminopropyl-diethoxymethyl-phosphinic acid (CGP 35348). These compounds, of which the most potent, the 5-chloro derivative, was weaker than (-)-baclofen, thus activate baclofen receptors in the cat and rat spinal cord.

  1. Production of γ-Amino Butyric Acid in Tea Leaves wit Treatment of Lactic Acid Bacteria

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuko; Hayakawa, Kiyoshi; Ueno, Hiroshi

    Lactic acid bacteria was searched for producing termented tea that contained a lot of γ-amino butyric acid(GABA). Also examined were the growth condition, GABA production and changes in catechin contents in the tea leaves. Lactobacillus brevis L12 was found to be suitable for the production of fermented tea since it gave as much GABA as gabaron tea when tea leaves being suspended with water at 10% and incubated for 4 days at 25°C. The amount of GABA produced was more than calculated based upon the content of glutamic acid in tea leaves. It is probable to assume that glutamate derived from glutamine and theanine is converted into GABA.

  2. Control of cortical neuronal migration by glutamate and GABA

    PubMed Central

    Luhmann, Heiko J.; Fukuda, A.; Kilb, W.

    2015-01-01

    Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca2+ transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e., neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g., anti-epileptics, anesthetics, alcohol) may disturb the normal migration pattern when present during early corticogenesis. PMID:25688185

  3. Control of cortical neuronal migration by glutamate and GABA.

    PubMed

    Luhmann, Heiko J; Fukuda, A; Kilb, W

    2015-01-01

    Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca(2+) transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e., neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g., anti-epileptics, anesthetics, alcohol) may disturb the normal migration pattern when present during early corticogenesis.

  4. GABA-independent GABAA Receptor Openings Maintain Tonic Currents

    PubMed Central

    Wlodarczyk, Agnieszka I.; Sylantyev, Sergiy; Herd, Murray B.; Kersanté, Flavie; Lambert, Jeremy J.; Rusakov, Dmitri A.; Linthorst, Astrid C.E.; Semyanov, Alexey; Belelli, Delia; Pavlov, Ivan; Walker, Matthew C.

    2013-01-01

    Activation of GABAA receptors (GABAARs) produces two forms of inhibition: ‘phasic’ inhibition generated by the rapid, transient activation of synaptic GABAARs by presynaptic GABA release, and tonic inhibition generated by the persistent activation of peri- or extrasynaptic GABAARs which can detect extracellular GABA. Such tonic GABAAR-mediated currents are particularly evident in dentate granule cells in which they play a major role in regulating cell excitability. Here we show that in rat dentate granule cells in ex-vivo hippocampal slices, tonic currents are predominantly generated by GABA-independent GABAA receptor openings. This tonic GABAAR conductance is resistant to the competitive GABAAR antagonist SR95531, which at high concentrations acts as a partial agonist, but can be blocked by an open channel blocker picrotoxin. When slices are perfused with 200 nM GABA, a concentration that is comparable to cerebrospinal fluid concentrations but is twice that measured by us in the hippocampus in vivo using zero-net-flux microdialysis, negligible GABA is detected by dentate granule cells. Spontaneously opening GABAARs, therefore, maintain dentate granule cell tonic currents in the face of low extracellular GABA concentrations. PMID:23447601

  5. Regionally Specific Human GABA Concentration Correlates with Tactile Discrimination Thresholds

    PubMed Central

    Puts, Nicolaas A. J.; Edden, Richard A. E.; Evans, C. John; McGlone, Francis; McGonigle, David J.

    2012-01-01

    The neural mechanisms underlying variability in human sensory perception remain incompletely understood. In particular, few studies have attempted to investigate the relationship between in vivo measurements of neurochemistry and individuals’ behavioral performance. Our previous work found a relationship between GABA concentration in the visual cortex and orientation discrimination thresholds (Edden et al., 2009). In the present study, we used magnetic resonance spectroscopy of GABA and psychophysical testing of vibrotactile frequency thresholds to investigate whether individual differences in tactile frequency discrimination performance are correlated with GABA concentration in sensorimotor cortex. Behaviorally, individuals showed a wide range of discrimination thresholds ranging from 3 to 7.6 Hz around the 25 Hz standard. These frequency discrimination thresholds were significantly correlated with GABA concentration (r = −0.58; p < 0.05) in individuals’ sensorimotor cortex, but not with GABA concentration in an occipital control region (r = −0.04). These results demonstrate a link between GABA concentration and frequency discrimination in vivo, and support the hypothesis that GABAergic mechanisms have an important role to play in sensory discrimination. PMID:22090482

  6. Modulation of radioligand binding to the GABA(A)-benzodiazepine receptor complex by a new component from Cyperus rotundus.

    PubMed

    Ha, Jeoung-Hee; Lee, Kwang-Youn; Choi, Hyoung-Chul; Cho, Jungsook; Kang, Byung-Soo; Lim, Jae-Chul; Lee, Dong-Ung

    2002-01-01

    Four sesquiterpenes, beta-selinene, isocurcumenol, nootkatone and aristolone and one triterpene, oleanolic acid were isolated from the ethylacetate fraction of the rhizomes of Cyperus rotundus and tested for their ability to modulate gamma-aminobutyric acid (GABA(A))-benzodiazepine receptor function by radioligand binding assays using rat cerebrocortical membranes. Among these compounds, only isocurcumenol, one of the newly identified constituents of this plant, was found to inhibit [3H]Ro15-1788 binding and enhance [3H]flunitrazepam binding in the presence of GABA. These results suggest that isocurcumenol may serve as a benzodiazepine receptor agonist and allosterically modulate GABAergic neurotransmission via enhancement of endogenous receptor ligand binding. PMID:11824542

  7. Evaluation of improved γ-aminobutyric acid production in yogurt using Lactobacillus plantarum NDC75017.

    PubMed

    Shan, Y; Man, C X; Han, X; Li, L; Guo, Y; Deng, Y; Li, T; Zhang, L W; Jiang, Y J

    2015-04-01

    Most γ-aminobutyric acid (GABA)-producing microorganisms are lactic acid bacteria (LAB), but the yield of GABA is limited in most of these GABA-producing strains. In this study, the production of GABA was carried out by using Lactobacillus plantarum NDC75017, a strain screened from traditional fermented dairy products in China. Concentrations of substrate (l-monosodium glutamate, L-MSG) and coenzyme (pyridoxal-5-phosphate, PLP) of glutamate decarboxylase (GAD) and culture temperature were investigated to evaluate their effects on GABA yield of Lb. plantarum NDC75017. The results indicated that GABA production was related to GAD activity and biomass of Lb. plantarum NDC75017. Response surface methodology was used to optimize conditions of GABA production. The optimal factors for GABA production were L-MSG at 80 mM, PLP at 18 μM, and a culture temperature of 36 °C. Under these conditions, production of GABA was maximized at 314.56 mg/100 g. Addition of Lb. plantarum NDC75017 to a commercial starter culture led to higher GABA production in fermented yogurt. Flavor and texture of the prepared yogurt and the control yogurt did not differ significantly. Thus, Lb. plantarum NDC75017 has good potential for manufacture of GABA-enriched fermented milk products.

  8. gamma-Hydroxybutyrate (GHB) induces GABA(B) receptor independent intracellular Ca2+ transients in astrocytes, but has no effect on GHB or GABA(B) receptors of medium spiny neurons in the nucleus accumbens.

    PubMed

    Molnár, T; Antal, K; Nyitrai, G; Emri, Z

    2009-08-18

    We report on cellular actions of the illicit recreational drug gamma-hydroxybutyrate (GHB) in the brain reward area nucleus accumbens. First, we compared the effects of GHB and the GABA(B) receptor agonist baclofen. Neither of them affected the membrane currents of medium spiny neurons in rat nucleus accumbens slices. GABAergic and glutamatergic synaptic potentials of medium spiny neurons, however, were reduced by baclofen but not GHB. These results indicate the lack of GHB as well as postsynaptic GABA(B) receptors, and the presence of GHB insensitive presynaptic GABA(B) receptors in medium spiny neurons. In astrocytes GHB induced intracellular Ca(2+) transients, preserved in slices from GABA(B) receptor type 1 subunit knockout mice. The effects of tetrodotoxin, zero added Ca(2+) with/without intracellular Ca(2+) store depletor cyclopiazonic acid or vacuolar H-ATPase inhibitor bafilomycin A1 indicate that GHB-evoked Ca(2+) transients depend on external Ca(2+) and intracellular Ca(2+) stores, but not on vesicular transmitter release. GHB-induced astrocytic Ca(2+) transients were not affected by the GHB receptor-specific antagonist NCS-382, suggesting the presence of a novel NCS-382-insensitive target for GHB in astrocytes. The activation of astrocytes by GHB implies their involvement in physiological actions of GHB. Our findings disclose a novel profile of GHB action in the nucleus accumbens. Here, unlike in other brain areas, GHB does not act on GABA(B) receptors, but activates an NCS-382 insensitive GHB-specific target in a subpopulation of astrocytes. The lack of either post- or presynaptic effects on medium spiny neurons in the nucleus accumbens distinguishes GHB from many drugs and natural rewards with addictive properties and might explain why GHB has only a weak reinforcing capacity.

  9. A pharmacological characterization of GABA, THIP and DS2 at binary α4β3 and β3δ receptors: GABA activates β3δ receptors via the β3(+)δ(-) interface.

    PubMed

    Lee, H J; Absalom, N L; Hanrahan, J R; van Nieuwenhuijzen, P; Ahring, P K; Chebib, M

    2016-08-01

    There is growing evidence that GABA (γ-aminobutyric acid) can activate GABAA receptors (GABAARs) in the absence of an α subunit. In this study, we compared the pharmacology of homomeric and binary α4, β3 or δ subunits with ternary α4β3δ to identify subunit interfaces that contribute to the pharmacology of GABA, THIP, and DS2, and the antagonists, Zn(2+), gabazine and bicuculline. β3δ receptors form functional GABA-gated channels when expressed in Xenopus oocytes with a pharmacology that differs to homomeric β3, binary α4β3 and ternary α4β3δ receptors. GABA had similar potency at α4β3 and β3δ receptors (25µM and 26µM, respectively) but differed at α4β3δ receptors where GABA exhibited a biphasic concentration-response (EC50 (1)=12.6nM; EC50 (2)=6.3μM). THIP activated β3δ receptors (EC50=456μM) but was a more potent activator of α4β3 (EC50=27μM) and α4β3δ receptors (EC50 (1)=27.5nM; EC50 (2)=29.5μΜ), indicating that the α4 subunit significantly contribute to its potency. The δ-preferring modulator, DS2 had marginal or no effect at β3δ and α4β3 receptors, indicating a role for both the α4 and δ subunits for its potency. Gabazine inhibited GABA-elicited currents at β3δ receptors whereas bicuculline activated these receptors. Mutational analysis verified that GABA binds to the β3(+)δ(-) interface formed by the β3 and δ subunits. In conclusion, evaluating agents against binary GABAARs such as β3δ and α4β3 receptors enables identification of interfaces that may contribute to the pharmacology of the more complex ternary α4β3δ receptors.

  10. Altered GABA Signaling in Early Life Epilepsies

    PubMed Central

    Briggs, Stephen W.; Galanopoulou, Aristea S.

    2011-01-01

    The incidence of seizures is particularly high in the early ages of life. The immaturity of inhibitory systems, such as GABA, during normal brain development and its further dysregulation under pathological conditions that predispose to seizures have been speculated to play a major role in facilitating seizures. Seizures can further impair or disrupt GABAA signaling by reshuffling the subunit composition of its receptors or causing aberrant reappearance of depolarizing or hyperpolarizing GABAA receptor currents. Such effects may not result in epileptogenesis as frequently as they do in adults. Given the central role of GABAA signaling in brain function and development, perturbation of its physiological role may interfere with neuronal morphology, differentiation, and connectivity, manifesting as cognitive or neurodevelopmental deficits. The current GABAergic antiepileptic drugs, while often effective for adults, are not always capable of stopping seizures and preventing their sequelae in neonates. Recent studies have explored the therapeutic potential of chloride cotransporter inhibitors, such as bumetanide, as adjunctive therapies of neonatal seizures. However, more needs to be known so as to develop therapies capable of stopping seizures while preserving the age- and sex-appropriate development of the brain. PMID:21826277

  11. Chronic anabolic-androgenic steroid treatment affects brain GABA(A) receptor-gated chloride ion transport.

    PubMed

    Bitran, D; Hilvers, R J; Frye, C A; Erskine, M S

    1996-01-01

    Previous research in this laboratory has shown that chronic treatment of adult male rats with an anabolic-androgenic steroid (AAS) produced anxiolytic behavior and increased the functional response of cortical gamma-aminobutyric acid(A) (GABA(A)) receptors. The experiments reported here were aimed at further characterizing the effect of chronic AAS exposure on cerebral cortical GABA(A) receptors. Adult male rats were injected with dianabol (1,4-androstadien-17alpha-methyl-17beta-ol-3-one; 10 mg/kg/day, SC) for 4 weeks. A significant decrease in ventral prostate gland weight was found after 2 weeks of dianabol, and returned to control levels 3 and 10 days after steroid discontinuation. Testicular weights decreased throughout the treatment period but reached statistical significance only during the withdrawal period. Serum 3alpha-androstanediol level was marginally increased afer 2 weeks of dianabol injection, and was significantly decreased at 3 and 10 days after withdrawal. GABA-stimulated 36chloride (Cl-) influx in cortical synaptoneurosomes was increased in animals treated with dianabol for 2 and 4 weeks, and remained elevated 3 days after dianabol withdrawal, returning to control levels at withdrawal day 10. The increase in receptor efficacy was associated with a transient increase in receptor sensitivity (inverse of EC50), apparent after 2 weeks of AAS treatment and at withdrawal day 3. In a follow-up experiment, metabolites of dianabol were tested for the in vitro efficacy in potentiating GABA-stimulated Cl- transport. Only 3alpha-androstanedial and androsterone were found to have potent stimulatory effects. The 3beta-reduced metabolites were inactive, as were metabolites that contained a methyl group at the 17alpha position. These results point to significant facilitative effects of dianabol treatment on brain GABA(A) receptors via the metabolic formation of neuroactive steroids. PMID:8632710

  12. Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

    2011-02-01

    Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS.

  13. Molecular analysis of the A322D mutation in the GABA receptor alpha-subunit causing juvenile myoclonic epilepsy.

    PubMed

    Krampfl, Klaus; Maljevic, Snezana; Cossette, Patrick; Ziegler, Elke; Rouleau, Guy A; Lerche, Holger; Bufler, Johannes

    2005-07-01

    Juvenile myoclonic epilepsy (JME) belongs to the most common forms of hereditary epilepsy, the idiopathic generalized epilepsies. Although the mode of inheritance is usually complex, mutations in single genes have been shown to cause the disease in some families with autosomal dominant inheritance. The first mutation in a multigeneration JME family has been recently found in the alpha1-subunit of the GABAA receptor (GABRA1), predicting the single amino acid substitution A322D. We further characterized the functional consequences of this mutation by coexpressing alpha1-, beta2- and gamma2-subunits in human embryonic kidney (HEK293) cells. By using an ultrafast application system, mutant receptors have shown reduced macroscopic current amplitudes at saturating GABA concentrations and a highly reduced affinity to GABA compared to the wild-type (WT). Dose-response curves for current amplitudes, activation kinetics, and GABA-dependent desensitization parameters showed a parallel shift towards 30- to 40-fold higher GABA concentrations. Both deactivation and resensitization kinetics were considerably accelerated in mutant channels. In addition, mutant receptors labelled with enhanced green fluorescent protein (EGFP) were not integrated in the cell membrane, in contrast to WT receptors. Therefore, the A322D mutation leads to a severe loss-of-function of the human GABAA receptor by several mechanisms, including reduced surface expression, reduced GABA-sensitivity, and accelerated deactivation. These molecular defects could decrease and shorten the resulting inhibitory postsynaptic currents (IPSCs) in vivo, which can induce a hyperexcitability of the postsynaptic membrane and explain the occurrence of epileptic seizures.

  14. Response kinetics and pharmacological properties of heteromeric receptors formed by coassembly of GABA rho- and gamma 2-subunits.

    PubMed

    Qian, H; Ripps, H

    1999-12-01

    Two of the gamma-aminobutyric acid (GABA) receptors, GABAA and GABAC, are ligand-gated chloride channels expressed by neurons in the retina and throughout the central nervous system. The different subunit composition of these two classes of GABA receptor result in very different physiological and pharmacological properties. Although little is known at the molecular level as to the subunit composition of any native GABA receptor, it is thought that GABAC receptors are homomeric assemblies of rho-subunits. However, we found that the kinetic and pharmacological properties of homomeric receptors formed by each of the rho-subunits cloned from perch retina did not resemble those of the GABAC receptors on perch bipolar cells. Because both GABAA and GABAC receptors are present on retinal bipolar cells, we attempted to determine whether subunits of these two receptor classes are capable of interacting with each other. We report here that, when coexpressed in Xenopus oocytes, heteromeric (rho 1B gamma 2) receptors formed by coassembly of the rho 1B-subunit with the gamma 2-subunit of the GABAA receptor displayed response properties very similar to those obtained with current recordings from bipolar cells. In addition to being unresponsive to bicuculline and diazepam, the time-constant of deactivation, and the sensitivities to GABA, picrotoxin and zinc closely approximated the values obtained from the native GABAC receptors on bipolar cells. These results provide the first direct evidence of interaction between GABA rho and GABAA receptor subunits. It seems highly likely that coassembly of GABAA and rho-subunits contributes to the molecular organization of GABAC receptors in the retina and perhaps throughout the nervous system. PMID:10643085

  15. Elevated prefrontal cortex GABA in patients with major depressive disorder after TMS treatment measured with proton magnetic resonance spectroscopy

    PubMed Central

    Dubin, Marc J.; Mao, Xiangling; Banerjee, Samprit; Goodman, Zachary; Lapidus, Kyle A.B.; Kang, Guoxin; Liston, Conor; Shungu, Dikoma C.

    2016-01-01

    Background GABAergic and glutamatergic neurotransmitter systems are central to the pathophysiology of depression and are potential targets of repetitive transcranial magnetic stimulation (rTMS). We assessed the effect of 10-Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) of patients with major depressive disorder on the levels of medial prefrontal cortex (MPFC) γ-aminobutyric acid (GABA) and the combined resonance of glutamate and glutamine (Glx) as assessed in vivo with proton magnetic resonance spectroscopy (1H MRS). Methods Currently depressed individuals between the ages of 23 and 68 years participated in a 5-week naturalistic, open-label treatment study of rTMS, with 1H MRS measurements of MPFC GABA and Glx levels at baseline and following 5 weeks of the rTMS intervention. We applied rTMS pulses over the left DLPFC at 10 Hz and 80%–120% of motor threshold for 25 daily sessions, with each session consisting of 3000 pulses. We assessed therapeutic response using the 24-item Hamilton Rating Scale for Depression (HAMD24). The GABA and Glx levels are expressed as ratios of peak areas relative to the area of the synchronously acquired and similarly fitted unsuppressed voxel water signal (W). Results Twenty-three currently depressed individuals (7 men) participated in the study. GABA/W in the MPFC increased 13.8% (p = 0.013) in all depressed individuals. There were no significant effects of rTMS on Glx/W. GABA/W and Glx/W were highly correlated in severely depressed patients at baseline but not after TMS. Limitations The primary study limitations are the open-label design and the inclusion of participants currently taking stable regimens of antidepressant medications. Conclusion These results implicate GABAergic and glutamatergic systems in the mechanism of action of rTMS for major depression, warranting further investigation in larger samples. PMID:26900793

  16. Virus-induced gene silencing reveals control of reactive oxygen species accumulation and salt tolerance in tomato by γ-aminobutyric acid metabolic pathway.

    PubMed

    Bao, Hexigeduleng; Chen, Xianyang; Lv, Sulian; Jiang, Ping; Feng, Juanjuan; Fan, Pengxiang; Nie, Lingling; Li, Yinxin

    2015-03-01

    γ-Aminobutyric acid (GABA) accumulates in many plant species in response to environmental stress. However, the physiological function of GABA or its metabolic pathway (GABA shunt) in plants remains largely unclear. Here, the genes, including glutamate decarboxylases (SlGADs), GABA transaminases (SlGABA-Ts) and succinic semialdehyde dehydrogenase (SlSSADH), controlling three steps of the metabolic pathway of GABA, were studied through virus-induced gene silencing approach in tomato. Silencing of SlGADs (GABA biosynthetic genes) and SlGABA-Ts (GABA catabolic genes) led to increased accumulation of reactive oxygen species (ROS) as well as salt sensitivity under 200 mm NaCl treatment. Targeted quantitative analysis of metabolites revealed that GABA decreased and increased in the SlGADs- and SlGABA-Ts-silenced plants, respectively, whereas succinate (the final product of GABA metabolism) decreased in both silenced plants. Contrarily, SlSSADH-silenced plants, also defective in GABA degradation process, showed dwarf phenotype, curled leaves and enhanced accumulation of ROS in normal conditions, suggesting the involvement of a bypath for succinic semialdehyde catabolism to γ-hydroxybutyrate as reported previously in Arabidopsis, were less sensitive to salt stress. These results suggest that GABA shunt is involved in salt tolerance of tomato, probably by affecting the homeostasis of metabolites such as succinate and γ-hydroxybutyrate and subsequent ROS accumulation under salt stress.

  17. The influence of fig proteases on the inhibition of angiotensin I-converting and GABA formation in meat.

    PubMed

    Li, Jinyue; Izumimoto, Masatoshi; Yonehara, Makiko; Hirotsu, Seiya; Kuriki, Takayoshi; Naito, Ichiro; Yamada, Hidenori

    2009-12-01

    The purposes of this research were to use fig protease for texture tenderizing, and to inhibit angiotensin I-converting enzyme (ACE) action and gamma-aminobutyric acid (GABA) formation of meat. Liberated peptides by the enzymatic action of fig protease in processing meat and free amino acids were determined and ACE inhibitory activity was assayed. Meat treated with fig protease became tender as indicated by shear force value (SFV) which was half of those of non-fig treated meat during storage even at 5 degrees C. Liberated peptides, free amino acids and GABA increased while extremely low levels of Glu were detected after storage. The optimal temperature of fig protease against meat was 80 degrees C. However, the activity of fig protease decreased after pre-heating more than 40 degrees C. High ACE inhibitory activity of a mixture of fig and meat was found around 80 degrees C, and the value corresponded to the amount of liberated peptide. A lot of liberated peptides were found at 60-80 degrees C and pasterization of meat product becomes convenient to produce peptides. Production of ACE inhibitory peptides and GABA can be expected as the healthy functional meat product such as antihypertensive activity and improve brain function.

  18. Cerebral radioprotection by pentobarbital: Dose-response characteristics and association with GABA agonist activity

    SciTech Connect

    Olson, J.J.; Friedman, R.; Orr, K.; Delaney, T.; Oldfield, E.H. )

    1990-05-01

    Pentobarbital reduces cerebral radiation toxicity; however, the mechanism of this phenomenon remains unknown. As an anesthetic and depressant of cerebral metabolism, pentobarbital induces its effects on the central nervous system by stimulating the binding of gamma-aminobutyric acid (GABA) to its receptor and by inhibiting postsynaptic excitatory amino acid activity. The purpose of this study is to investigate the role of these actions as well as other aspects of the radioprotective activity of pentobarbital. Fischer 344 rats were separated into multiple groups and underwent two dose-response evaluations. In one set of experiments to examine the relationship of radioprotection to pentobarbital dose, a range of pentobarbital doses (0 to 75 mg/kg) were given intraperitoneally prior to a constant-level radiation dose (70 Gy). In a second series of experiments to determine the dose-response relationship of radiation protection to radiation dose, a range of radiation doses (10 to 90 Gy) were given with a single pentobarbital dose. Further groups of animals were used to evaluate the importance of the timing of pentobarbital administration, the function of the (+) and (-) isomers of pentobarbital, and the role of an alternative GABA agonist (diazepam). In addition, the potential protective effects of alternative methods of anesthesia (ketamine) and induction of cerebral hypometabolism (hypothermia) were examined. Enhancement of survival time from acute radiation injury due to high-dose single-fraction whole-brain irradiation was maximal with 60 mg/kg of pentobarbital, and occurred over the range of all doses examined between 30 to 90 Gy. Protection was seen only in animals that received the pentobarbital before irradiation. Administration of other compounds that enhance GABA binding (Saffan and diazepam) also significantly enhanced survival time.

  19. Γ-aminobutyric acid receptors affect the progression and migration of tumor cells.

    PubMed

    Zhang, Xiaoxue; Du, Zuoyi; Liu, Jun; He, Jianxing

    2014-12-01

    Γ-aminobutyric acid (GABA) is a multifunctional molecule found in the nervous system and non-neuronal tissues. GABA receptors combine with GABA molecules and transmit signal stimuli into cells. In addition to traditional neurotransmission and regulation of secretion, GABA and GABA receptors are involved in cell differentiation and proliferation throughout peripheral organs, as well as in tumorigenesis. The exact mechanism of the GABAergic system in regulating tumor development is unclear, but many studies have revealed that GABA receptors exert critical regulative effects on tumor cell proliferation and migration. In this review, the molecular structure, distribution and biological function of GABA receptors associated with tumorigenesis are described. Recent advances in the elucidation of mechanisms underlying GABAergic signaling control over tumor growth are also discussed.

  20. Expression of GABA transporters, GAT-1 and GAT-3, in the cerebral cortex and thalamus of the rat during postnatal development.

    PubMed

    Vitellaro-Zuccarello, L; Calvaresi, N; De Biasi, S

    2003-09-01

    The cellular and subcellular localization of two GABA transporters, GAT-1 and GAT-3, was investigated using immunocytochemical methods in the rat cerebral cortex and thalamus during postnatal development. The distribution of the transporters is compared with that of the neuronal marker GABA, and with that of vimentin and of glial fibrillary acidic protein, which identify immature and mature astrocytes, respectively. Our observations show that the two transporters are already expressed at birth in both brain areas with the same cellular localization as in adult rats, as GAT-1 is present in growth cones and terminals only in the cortex, whereas both transporters are expressed in astrocytes in the cortex and thalamus. The distribution of GAT-1 and GAT-3 undergoes postnatal changes reflecting in general the neurogenetic events of the neocortex and thalamus and, more specifically, the maturation of GABAergic innervation. The adult-like pattern of expression is achieved in the third postnatal week in the cortex and in the second postnatal week in the thalamus. The early expression of GAT-1 in GABAergic terminals confirms previous studies showing the existence of neuronal mechanisms of GABA uptake from the embryonic stages. As for the glial localization, the precocious existence of two astrocytic GABA transporters suggests that they operate through different functional mechanisms from birth, whereas their exclusively glial expression in the thalamus indicates that the astroglia plays a major role in the transport, recycling and metabolism of thalamic GABA.

  1. Differential expression of gamma-aminobutyric acid type B receptor subunit mRNAs in the developing nervous system and receptor coupling to adenylyl cyclase in embryonic neurons.

    PubMed

    Martin, Stella C; Steiger, Janine L; Gravielle, María Clara; Lyons, Helen R; Russek, Shelley J; Farb, David H

    2004-05-17

    gamma-Aminobutyric acid type B receptors (GABA(B)Rs) mediate both slow inhibitory synaptic activity in the adult nervous system and motility signals for migrating embryonic cortical cells. Previous papers have described the expression of GABA(B)Rs in the adult brain, but the expression and functional significance of these gene products in the embryo are largely unknown. Here we examine GABA(B)R expression from rat embryonic day 10 (E10) to E18 compared with adult and ask whether embryonic cortical neurons contain functional GABA(B)R. GABA(B)R1 transcript levels greatly exceed GABA(B)R2 levels in the developing neural tube at E11, and olfactory bulb and striatum at E17 but equalize in most regions of adult nervous tissue, except for the glomerular and granule cell layers of the main olfactory bulb and the striatum. Consistent with expression differences, the binding affinity of GABA for GABA(B)Rs is significantly lower in adult striatum compared with cerebellum. Multiple lines of evidence from in situ hybridization, RNase protection, and real-time PCR demonstrate that GABA(B)R1a, GABA(B)R1b, GABA(B)R1h (a subunit subtype, lacking a sushi domain, that we have identified in embryonic rat brain), GABA(B)R2, and GABA(B)L transcript levels are not coordinately regulated. Despite the functional requirement for a heterodimer of GABA(B)R subunits, the expression of each subunit mRNA is under independent control during embryonic development, and, by E18, GABA(B)Rs are negatively coupled to adenylyl cyclase in neocortical neurons. The presence of embryonic GABA(B)R transcripts and protein and functional receptor coupling indicates potentially important roles for GABA(B)Rs in modulation of synaptic transmission in the developing embryonic nervous system.

  2. Protons inhibit Cl- conductance by direct or allosteric interaction with the GABA-binding site in the rat recombinant alpha1beta2gamma2L and alpha1beta2 GABAA receptor.

    PubMed

    Wang, Ming-De; Rahman, Mozibur; Zhu, Di

    2005-12-28

    Functional roles of external pH on the Cl- conductance were examined on Xenopus oocytes expressing rat recombinant alpha1beta2gamma2L and alpha1beta2 GABAA receptors. Acidic pH inhibited GABA-response in a reversible and concentration-dependent manner, significantly increasing the EC50 without appreciably changing the slope or maximal currents induced by GABA in the alpha1beta2gamma2L and alpha1beta2 receptors. In contrast, protonation did not influence the pentobarbital-gated currents in the alpha1beta2gamma2L receptors, suggesting that protons do not modulate channel activity by directly affecting the channel gating process. Protons competitively inhibited the bicuculline-induced antagonism on GABA in the alpha1beta2gamma2L receptors. The data support the hypothesis that protons inhibit GABAA receptor function by direct or allosteric interaction with the GABA-binding site.

  3. Extrasynaptic release of GABA and dopamine by retinal dopaminergic neurons

    PubMed Central

    Hirasawa, Hajime; Contini, Massimo; Raviola, Elio

    2015-01-01

    In the mouse retina, dopaminergic amacrine (DA) cells synthesize both dopamine and GABA. Both transmitters are released extrasynaptically and act on neighbouring and distant retinal neurons by volume transmission. In simultaneous recordings of dopamine and GABA release from isolated perikarya of DA cells, a proportion of the events of dopamine and GABA exocytosis were simultaneous, suggesting co-release. In addition, DA cells establish GABAergic synapses onto AII amacrine cells, the neurons that transfer rod bipolar signals to cone bipolars. GABAA but not dopamine receptors are clustered in the postsynaptic membrane. Therefore, dopamine, irrespective of its site of release—synaptic or extrasynaptic—exclusively acts by volume transmission. Dopamine is released upon illumination and sets the gain of retinal neurons for vision in bright light. The GABA released at DA cells' synapses probably prevents signals from the saturated rods from entering the cone pathway when the dark-adapted retina is exposed to bright illumination. The GABA released extrasynaptically by DA and other amacrine cells may set a ‘GABAergic tone’ in the inner plexiform layer and thus counteract the effects of a spillover of glutamate released at the bipolar cell synapses of adjacent OFF and ON strata, thus preserving segregation of signals between ON and OFF pathways. PMID:26009765

  4. Design and mechanism of tetrahydrothiophene-based γ-aminobutyric acid aminotransferase inactivators.

    PubMed

    Le, Hoang V; Hawker, Dustin D; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L; Silverman, Richard B

    2015-04-01

    Low levels of γ-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinson's disease, Alzheimer's disease, Huntington's disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the blood-brain barrier and inhibit the activity of γ-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a π-π interaction with Phe-189, and a weak nonbonded S···O═C interaction with Glu-270, thereby inactivating the enzyme.

  5. GABA and Dopamine Release from Different Brain Regions in Mice with Chronic Exposure to Organophosphate Methamidophos

    PubMed Central

    Noriega-Ortega, Blanca Rosa; Armienta-Aldana, Ernesto; Cervantes-Pompa, José Ángel; Armienta-Aldana, Eduardo; Hernández-Ruíz, Enrique; Chaparro-Huerta, Verónica; Bravo-Cuellar, Alejandro; Beas-Zárate, Carlos

    2011-01-01

    Organophosphates such as methamidophos, usually used in the agricultural field, have harmful effects on humans. Exposures to insecticides has been associated with many disorders, including damage to the central and peripheral nervous system. Chronic exposure to organophosphates may lead to persistent neurological and neurobehavioral effects. This study was conducted to determine the effect of methamidophos on [3H]-dopamine (DA) and gamma aminobutyric acid (GABA) release from different brain regions after chronic exposure to it for 3, 6 or 9 months. After a six-month methamidophos treatment, the mice showed high susceptibility to convulsive seizures and a reduction in stimulated gamma aminobutyric acid release from the cerebral cortex and hippocampal slices, whereas stimulated (DA) release was slightly decreased from the striatum after three months of methamidophos exposure. The results indicate changes in gamma aminobutyric acid and dopamine neurotransmission, suggesting a specific neuronal damage. PMID:22272056

  6. GABA depolarizes immature neurons and inhibits network activity in the neonatal neocortex in vivo.

    PubMed

    Kirmse, Knut; Kummer, Michael; Kovalchuk, Yury; Witte, Otto W; Garaschuk, Olga; Holthoff, Knut

    2015-01-01

    A large body of evidence from in vitro studies suggests that GABA is depolarizing during early postnatal development. However, the mode of GABA action in the intact developing brain is unknown. Here we examine the in vivo effects of GABA in cells of the upper cortical plate using a combination of electrophysiological and Ca(2+)-imaging techniques. We report that at postnatal days (P) 3-4, GABA depolarizes the majority of immature neurons in the occipital cortex of anaesthetized mice. At the same time, GABA does not efficiently activate voltage-gated Ca(2+) channels and fails to induce action potential firing. Blocking GABA(A) receptors disinhibits spontaneous network activity, whereas allosteric activation of GABA(A) receptors has the opposite effect. In summary, our data provide evidence that in vivo GABA acts as a depolarizing neurotransmitter imposing an inhibitory control on network activity in the neonatal (P3-4) neocortex. PMID:26177896

  7. GABA- and glycine-mediated fall of intracellular pH in rat medullary neurons in situ.

    PubMed

    Lückermann, M; Trapp, S; Ballanyi, K

    1997-04-01

    In the region of the ventral respiratory group in brain stem slices from neonatal rats, intracellular pH (pHi) and membrane currents (I(m)) or potentials were measured in neurons dialyzed with the pH-sensitive dye 2',7'-bis-carboxyethyl-5(6)-carboxyfluorescein. Currents and increases in membrane conductance (g(m)) during bath application of 0.1 or 1 mM gamma-aminobutyric acid (GABA) were accompanied by a delayed mean fall of pHi by 0.17 and 0.25 pH units, respectively, from a pHi baseline of 7.33. These effects were reversibly suppressed by 50-100 microM bicuculline. Similar effects on I(m), g(m), and pHi were revealed on administration of 0.1 or 1 mM glycine. These responses were abolished by 10-100 microM strychnine. Dialysis of the cells with 15-30 microM carbonic anhydrase led to an acceleration of the kinetics and a potentiation of the GABA-induced pHi decrease. GABA- and glycine-evoked pHi decreases were very similar during recordings with either high- or low-Cl- patch electrodes, although the reversal potential of the accompanying currents differed by approximately 60 mV. The GABA-induced pHi decrease, but not the accompanying I(m) and g(m) responses, was suppressed in CO2/HCO3(-)-free, N-2-hydroxy-ethylpiperazine-N'-2-ethane sulphonic acid pH-buffered solution. Depolarization from -60 to +30 mV resulted in a sustained fall of pHi by maximally 0.5 pH units. In this situation, the GABA-induced fall of pHi turned into an intracellular alkalosis of 0.09-0.15 pH units. The results confirm and extend previous findings obtained in vivo that GABA- or glycine-induced intracellular acidosis of respiratory neurons is due to efflux of HCO3- via the receptor-coupled Cl- channel.

  8. Discrete regional distribution of biochemical markers for the dopamine, noradrenaline, serotonin, GABA and acetylcholine systems in the monkey brain (Cebus Apella). Effects of stress.

    PubMed

    Häggström, J E; Sjöquist, B; Eckernäs, S A; Ingvast, A; Gunne, L M

    1984-01-01

    Brains from Cebus Apella monkeys have been mapped biochemically using a cryo-section technique which enables exact micro-dissectioning of tissue. Two neurotransmitters; noradrenaline (NA) and gamma-amino-butyric acid (GABA) were measured by gas chromatography-masspectrometry technique. In addition biochemical markers reflecting metabolic activity in the dopamine (homovanillic acid, HVA, 3, 4-dihydroxyphenylacetic acid, DOPAC), serotonin (5-hydroxyindoleacetic acid, 5-HIAA), noradrenaline (4-hydroxy-3-methoxy-phenylglycol, HMPG), acetylcholine (choline acetyltransferase, CAT) and GABA (glutamic acid decarboxylase, GAD) transmitter systems were assayed. The distribution of these transmitter markers roughly corresponded to earlier studies in other non-human primates, whereas similar studies on the human brain generally show lower concentrations and enzyme activities. One monkey exposed to severe stress immediately before death deviated from the normal animals with regard to HVA, 5-HIAA, GAD and GABA. For the study of neuroleptic drugs, and notably their neurological side-effects, Cebus Apella monkeys have turned out to be particularly useful. In our laboratory we have employed this species of monkey to develop a model for acute dystonia and tardive dyskinesia (Gunne and Barany 1976, 1979, Barany et al. 1979). As a first step in the topological mapping of brain neuro-chemistry in these animals we here present data from normal monkeys, not treated with neuroleptics. During the ongoing project there was an unplanned "stress experiment" in one monkey, which had a nightly fight with a cage partner and had to be sacrificed the morning after due to severe wounds. The present communication describes a method for obtaining well-defined samples from monkey brains and presents the data on homovanillic acid (HVA), 3.4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), noradrenaline (NA), 4-hydroxy-3-methoxy-phenyl glycol (HMPG), choline acetyltransferase (Ch

  9. Regulation of Local Ambient GABA Levels via Transporter-Mediated GABA Import and Export for Subliminal Learning.

    PubMed

    Hoshino, Osamu

    2015-06-01

    Perception of supraliminal stimuli might in general be reflected in bursts of action potentials (spikes), and their memory traces could be formed through spike-timing-dependent plasticity (STDP). Memory traces for subliminal stimuli might be formed in a different manner, because subliminal stimulation evokes a fraction (but not a burst) of spikes. Simulations of a cortical neural network model showed that a subliminal stimulus that was too brief (10 msec) to perceive transiently (more than about 500 msec) depolarized stimulus-relevant principal cells and hyperpolarized stimulus-irrelevant principal cells in a subthreshold manner. This led to a small increase or decrease in ongoing-spontaneous spiking activity frequency (less than 1 Hz). Synaptic modification based on STDP during this period effectively enhanced relevant synaptic weights, by which subliminal learning was improved. GABA transporters on GABAergic interneurons modulated local levels of ambient GABA. Ambient GABA molecules acted on extrasynaptic receptors, provided principal cells with tonic inhibitory currents, and contributed to achieving the subthreshold neuronal state. We suggest that ongoing-spontaneous synaptic alteration through STDP following subliminal stimulation may be a possible neuronal mechanism for leaving its memory trace in cortical circuitry. Regulation of local ambient GABA levels by transporter-mediated GABA import and export may be crucial for subliminal learning. PMID:25774546

  10. GABA-B receptor activation and conflict behavior

    SciTech Connect

    Ketelaars, C.E.J.; Bollen, E.L.; Rigter, H.; Bruinvels, J.

    1988-01-01

    Baclofen and oxazepam enhance extinction of conflict behavior in the Geller-Seifter test while baclofen and diazepam release punished behavior in Vogel's conflict test. In order to investigate the possibility that the effect of the selective GABA-B receptor agonist baclofen is mediated indirectly via the GABA-A/benzodiazepine receptor complex, the effect of pretreatment of rats with baclofen on (/sup 3/H)-diazepam binding to washed and unwashed cortical and cerebellar membranes of rats has been studied. Baclofen pretreatment increase Bmax in washed cerebellar membranes when bicuculline was present in the incubation mixture. No effect was seen in cortical membranes. The present results render it unlikely that the effect of baclofen on extinction of conflict behavior and punished drinking is mediated via the GABA-A/benzodiazepine receptor complex. 50 references, 1 figure, 4 tables.

  11. GABA excitation in mouse hilar neuropeptide Y neurons

    PubMed Central

    Fu, Li-Ying; van den Pol, Anthony N

    2007-01-01

    Neuropeptide Y-containing interneurons in the dentate hilar area play an important role in inhibiting the activity of hippocampal circuitry. Hilar cells are often among the first lost in hippocampal epilepsy. As many types of neurons are found in the hilus, we used a new transgenic mouse expressing green fluorescent protein (GFP) in a subset of neurons that colocalized neuropeptide Y (NPY), somatostatin (SST), and GABA for whole-cell, perforated, and cell-attached recording in 240 neurons. As these neurons have not previously been identifiable in live slices, they have not been the focus of physiological analysis. Hilar NPY neurons showed modest spike frequency adaptation, a large 15.6 ± 1.0 mV afterhyperpolarization, a mean input resistance of 335 ± 26 mΩ, and were capable of fast-firing. Muscimol-mediated excitatory actions were found in a nominally Ca2+-free/high-Mg2+ bath solution using cell-attached recording. GABAA receptor antagonists inhibited half the recorded neurons and blocked burst firing. Gramicidin perforated-patch recording revealed a GABA reversal potential positive to both the resting membrane potential and spike threshold. Together, these data suggest GABA is excitatory to many NPY cells. NPY and SST consistently hyperpolarized and reduced spike frequency in these neurons. No hyperpolarization of NPY on membrane potential was detected in the presence of tetrodotoxin, AP5, CNQX and bicuculline, supporting an indirect effect. Under similar conditions, SST hyperpolarized the cells, suggesting a direct postsynaptic action. Depolarizing actions of GABA and GABA-dependent burst-firing may synchronize a rapid release of GABA, NPY, and SST, leading to pre- and postsynaptic inhibition of excitatory hippocampal circuits. PMID:17204505

  12. Ion binding and permeation at the GABA transporter GAT1.

    PubMed

    Mager, S; Kleinberger-Doron, N; Keshet, G I; Davidson, N; Kanner, B I; Lester, H A

    1996-09-01

    This study addresses the binding of ions and the permeation of substrates during function of the GABA transporter GAT1. GAT1 was expressed in Xenopus oocytes and studied electrophysiologically as well as with [3H]GABA flux; GAT1 was also expressed in mammalian cells and studied with [3H]GABA and [3H]tiagabine binding. Voltage jumps, Na+ and Cl- concentration jumps, and exposure to high-affinity blockers (NO-05-711 and SKF-100330A) all produce capacitive charge movements. Occlusive interactions among these three types of perturbations show that they all measure the same population of charges. The concentration dependences of the charge movements reveal (1) that two Na+ ions interact with the transporter even in the absence of GABA, and (2) that Cl- facilitates the binding of Na+. Comparison between the charge movements and the transport-associated current shows that this initial Na(+)-transporter interaction limits the overall transport rate when [GABA] is saturating. However, two classes of manipulation--treatment with high-affinity uptake blockers and the W68L mutation-"lock" Na+ onto the transporter by slowing or preventing the subsequent events that release the substrates to the intracellular medium. The Na+ substitutes Li+ and Cs+ do not support charge movements, but they can permeate the transporter in an uncoupled manner. Our results (1) support the hypothesis that efficient removal of synaptic transmitter by the GABA transporter GAT1 depends on the previous binding of Na+ and Cl-, and (2) indicate the important role of the conserved putative transmembrane domain 1 in interactions with the permeant substrates. PMID:8757253

  13. Sodium valproate alters GnRH-GABA interactions during development in seizure-prone mice.

    PubMed

    Illig, A M; Melia, K; Snyder, P J; Badura, L L

    2000-12-01

    During reproductive maturation, characteristic changes occur in the morphology of the gonadotropin releasing hormone (GnRH) cell population within the hypothalamus. In the early stages of development, GnRH neurons are bipolar cells; however, just before pubertal onset, the majority of these neurons transform into unipolar cells. Our laboratory has reported that valproic acid (VPA), an antiepileptic medication that has previously been shown to slow the velocity of pubertal development in both humans and seizure-prone mice, is capable of delaying the normal process of GnRH morphological differentiation. As VPA is primarily believed to act via a GABAergic mechanism, the present study investigated potential influences of VPA on GnRH-GABA interactions within the medial preoptic area (mPOA) across pubertal development (experiment 1), as well as in adult animals (experiment 2). The results from experiment 1 revealed the expected drug effects on GnRH cell morphology. For VPA animals, there was a greater percentage of bipolar neurons at every time period except for the 24-day sample. Additionally, VPA animals had greater numbers of bipolar and unipolar GnRH neurons with GABA associations across all ages. However, experiment 2 showed a lack of drug effects on GnRH-GABA interactions in adulthood. These results suggest that VPA may delay GnRH cell morphological maturation by altering the density of GABAergic inputs to GnRH neurons. These inputs may normally play a role in timing the activation of the GnRH pulse generator. However, any neuroendocrine effects of VPA in adulthood are most likely due to the actions of VPA at another level of the hypothalamic-pituitary-gonadal axis.

  14. Inhibition of the kinase WNK1/HSN2 ameliorates neuropathic pain by restoring GABA inhibition.

    PubMed

    Kahle, Kristopher T; Schmouth, Jean-François; Lavastre, Valérie; Latremoliere, Alban; Zhang, Jinwei; Andrews, Nick; Omura, Takao; Laganière, Janet; Rochefort, Daniel; Hince, Pascale; Castonguay, Geneviève; Gaudet, Rébecca; Mapplebeck, Josiane C S; Sotocinal, Susana G; Duan, JingJing; Ward, Catherine; Khanna, Arjun R; Mogil, Jeffrey S; Dion, Patrick A; Woolf, Clifford J; Inquimbert, Perrine; Rouleau, Guy A

    2016-03-29

    HSN2is a nervous system predominant exon of the gene encoding the kinase WNK1 and is mutated in an autosomal recessive, inherited form of congenital pain insensitivity. The HSN2-containing splice variant is referred to as WNK1/HSN2. We created a knockout mouse specifically lacking theHsn2exon ofWnk1 Although these mice had normal spinal neuron and peripheral sensory neuron morphology and distribution, the mice were less susceptible to hypersensitivity to cold and mechanical stimuli after peripheral nerve injury. In contrast, thermal and mechanical nociceptive responses were similar to control mice in an inflammation-induced pain model. In the nerve injury model of neuropathic pain, WNK1/HSN2 contributed to a maladaptive decrease in the activity of the K(+)-Cl(-)cotransporter KCC2 by increasing its inhibitory phosphorylation at Thr(906)and Thr(1007), resulting in an associated loss of GABA (γ-aminobutyric acid)-mediated inhibition of spinal pain-transmitting nerves. Electrophysiological analysis showed that WNK1/HSN2 shifted the concentration of Cl(-)such that GABA signaling resulted in a less hyperpolarized state (increased neuronal activity) rather than a more hyperpolarized state (decreased neuronal activity) in mouse spinal nerves. Pharmacologically antagonizing WNK activity reduced cold allodynia and mechanical hyperalgesia, decreased KCC2 Thr(906)and Thr(1007)phosphorylation, and restored GABA-mediated inhibition (hyperpolarization) of injured spinal cord lamina II neurons. These data provide mechanistic insight into, and a compelling therapeutic target for treating, neuropathic pain after nerve injury. PMID:27025876

  15. GABA levels in the ventromedial prefrontal cortex during the viewing of appetitive and disgusting food images.

    PubMed

    Padulo, Caterina; Delli Pizzi, Stefano; Bonanni, Laura; Edden, Richard A E; Ferretti, Antonio; Marzoli, Daniele; Franciotti, Raffaella; Manippa, Valerio; Onofrj, Marco; Sepede, Gianna; Tartaro, Armando; Tommasi, Luca; Puglisi-Allegra, Stefano; Brancucci, Alfredo

    2016-10-01

    Characterizing how the brain appraises the psychological dimensions of reward is one of the central topics of neuroscience. It has become clear that dopamine neurons are implicated in the transmission of both rewarding information and aversive and alerting events through two different neuronal populations involved in encoding the motivational value and the motivational salience of stimuli, respectively. Nonetheless, there is less agreement on the role of the ventromedial prefrontal cortex (vmPFC) and the related neurotransmitter release during the processing of biologically relevant stimuli. To address this issue, we employed magnetic resonance spectroscopy (MRS), a non-invasive methodology that allows detection of some metabolites in the human brain in vivo, in order to assess the role of the vmPFC in encoding stimulus value rather than stimulus salience. Specifically, we measured gamma-aminobutyric acid (GABA) and, with control purposes, Glx levels in healthy subjects during the observation of appetitive and disgusting food images. We observed a decrease of GABA and no changes in Glx concentration in the vmPFC in both conditions. Furthermore, a comparatively smaller GABA reduction during the observation of appetitive food images than during the observation of disgusting food images was positively correlated with the scores obtained to the body image concerns sub-scale of Body Uneasiness Test (BUT). These results are consistent with the idea that the vmPFC plays a crucial role in processing both rewarding and aversive stimuli, possibly by encoding stimulus salience through glutamatergic and/or noradrenergic projections to deeper mesencephalic and limbic areas. PMID:27436536

  16. Role of human GABA(A) receptor beta3 subunit in insecticide toxicity.

    PubMed

    Ratra, G S; Kamita, S G; Casida, J E

    2001-05-01

    The gamma-aminobutyric acid type A (GABA(A)) receptor is the target for the major insecticides alpha-endosulfan, lindane, and fipronil and for many analogs. Their action as chloride channel blockers is directly measured by binding studies with [(3)H]ethynylbicycloorthobenzoate ([(3)H]EBOB). This study tests the hypothesis that GABA(A) receptor subunit composition determines the sensitivity and selectivity of insecticide toxicity. Human receptor subtypes were expressed individually (alpha1, alpha6, beta1, beta3, and gamma2) and in combination in insect Sf9 cells. Binding parameters were similar for [(3)H]EBOB in the beta3 homooligomer, alpha1beta3gamma2 heterooligomer, and native brain membranes, but toxicological profiles were very different. Surprisingly, alpha-endosulfan, lindane, and fipronil were all remarkably potent on the recombinant beta3 homooligomeric receptor (IC50 values of 0.5-2.4 nM), whereas they were similar in potency on the alpha1beta3gamma2 subtype (IC50 values of 16-33 nM) and highly selective on the native receptor (IC50 values of 7.3, 306, and 2470 nM, respectively). The selectivity order for 29 insecticides and convulsants as IC50 ratios for native/beta3 or alpha1beta3gamma2/beta3 was as follows: fipronil > lindane > 19 other insecticides including alpha-endosulfan and picrotoxinin > 4 trioxabicyclooctanes and dithianes (almost nonselective) > tetramethylenedisulfotetramine, 4-chlorophenylsilatrane, or alpha-thujone. Specificity between mammals and insects at the target site (fipronil > lindane > alpha-endosulfan) paralleled that for toxicity. Potency at the native receptor is more predictive for inhibition of GABA-stimulated chloride uptake than that at the beta3 or alpha1beta3gamma2 receptors. Therefore, the beta3 subunit contains the insecticide target and other subunits differentially modulate the binding to confer compound-dependent specificity and selective toxicity.

  17. GABA uptake in astrocytes in primary cultures: coupling with two sodium ions.

    PubMed

    Larsson, O M; Hertz, L; Schousboe, A

    1980-01-01

    The influence of sodium ions on GABA uptake into astrocytes in primary cultures has been investigated performing kinetic analysis of GABA uptake at different sodium concentrations in the range 16 to 151 mM. These investigations reveal that sodium affects both the Km and the Vmax of the saturable component of the astroglial GABA uptake. Uptake rates as a function of the sodium concentration at high GABA concentrations (greater than or equal to 50 microM) were clearly sigmoid whereas at lower GABA concentrations this sigmoid shape was not obvious. Accordingly, Hill plots of the sodium dependency at high GABA concentrations exhibited straight lines with slopes of 2.0 to 2.5, suggesting that the coupling ratio between sodium and GABA is at least two. Corresponding Hill plots at lower GABA concentrations exhibited slopes of 1.6 to 1.8. Moreover, plots of 1/v versus 1/Na2 gave better fits to straight lines than plots of 1/v versus 1/Na which were curvilinear upward. Again, this curvilinearity was more pronounced at high GABA concentrations that at low GABA concentrations. From these results it is concluded that GABA uptake into astrocytes in primary cultures requires the binding of at least two sodium ions per GABA molecule transported.

  18. Levels of glutamate, aspartate, GABA, and taurine in different regions of the cerebellum after x-irradiation-induced neuronal loss

    SciTech Connect

    Rea, M.A.; McBride, W.J.; Rohde, B.H.

    1981-01-01

    The levels of glutamate (Glu), aspartate (Asp), gamma-amino-n-butyric acid (GABA), and taurine (Tau) were determined in the cortex, molecular layer, and deep nuclei of cerebella of adult rats exposed to X-irradiation at 12-15 days following birth (to prevent the acquisition of late-forming granule cells; 12-15x group) and 8-15 days following birth (to prevent the acquisition of granule and stellate cells; 8-15x group). Also, the levels of the four amino acids were measured in the crude synaptosomal fraction (P2) isolated from the whole cerebella of the control, 12-15x, and 8-15x groups. The level of Glu was significantly decreased by (1) 6-20% in the cerebellar cortex; (2) 15-20% in the molecular layer; and (3) 25-50% in the P2 fraction of the X-irradiated groups relative to control values. The content of Glu in the deep nuclei was not changed by X-irradiation treatment. Regional levels of Asp were unchanged by X-irradiation, while its level in P2 decreased by 15-30% after treatment. The levels of GABA and Tau in the molecular layer, deep nuclei, or P2 were not changed in the experimental groups. However, there was a 15% increase in the levels of GABA and Tau in the cerebellar cortex of the 8-15x group relative to control values. The data support the proposed role of glutamate as the excitatory transmitter released from the cerebellar granule cells but are inconclusive regarding a transmitter role for either Tau or GABA from cerebellar stellate cells.

  19. Active transport of. gamma. -aminobutyric acid and glycine into synaptic vesicles

    SciTech Connect

    Kish, P.E.; Fischer-Bovenkerk, C.; Ueda, T. )

    1989-05-01

    Although {gamma}-aminobutyric acid (GABA) and glycine are recognized as major amino acid inhibitory neurotransmitters in the central nervous system, their storage is poorly understood. In this study the authors have characterized vesicular GABA and glycine uptakes in the cerebrum and spinal cord, respectively. They present evidence that GABA and glycine are each taken up into isolated synaptic vesicles in an ATP-dependent manner and that the uptake is driven by an electrochemical proton gradient. Uptake for both amino acids exhibited kinetics with low affinity similar to a vesicular glutamate uptake. The ATP-dependent GABA uptake was not inhibited by the putative amino acid neurotransmitters glycine, taurine, glutamate, or aspartate or by GABA analogs, agonists, and antagonists. Similarly, ATP-dependent glycine uptake was hardly affected by GABA, taurine, glutamate, or aspartate or by glycine analogs or antagonists. The GABA uptake was not affected by chloride, which is in contrast to the uptake of the excitatory neurotransmitter glutamate, whereas the glycine uptake was slightly stimulated by low concentrations of chloride. Tissue distribution studies indicate that the vesicular uptake systems for GABA, glycine, and glutamate are distributed in different proportions in the cerebrum and spinal cord. These results suggest that the vesicular uptake systems for GABA, glycine, and glutamate are distinct from each other.

  20. Metabolome analysis of milk fermented by γ-aminobutyric acid-producing Lactococcus lactis.

    PubMed

    Hagi, Tatsuro; Kobayashi, Miho; Nomura, Masaru

    2016-02-01

    γ-Aminobutyric acid (GABA) is one of the most important functional components in fermented foods because of its physiological functions, such as neurotransmission and antihypertensive activities. However, little is known about components other than GABA in GABA-rich fermented foods. A metabolomic approach offers an opportunity to discover bioactive and flavor components in fermented food. To find specific components in milk fermented with GABA-producing Lactococcus lactis 01-7, we compared the components found in GABA-rich fermented milk with those found in control milk fermented without GABA production using capillary electrophoresis time-of-flight mass spectrometry. A principal component analysis score plot showed a clear differentiation between the control milk fermented with L. lactis 01-1, which does not produce GABA, and GABA-rich milk fermented with a combination of L. lactis strains 01-1 and 01-7. As expected, the amount of GABA in GABA-rich fermented milk was much higher (1,216-fold) than that of the control milk. Interestingly, the amount of Orn was also much higher (27-fold) than that of the control milk. Peptide analysis showed that levels of 6 putative angiotensin-I-converting enzyme (ACE)-inhibitory peptides were also higher in the GABA-rich fermented milk. Furthermore, ACE-inhibitory activity of GABA-rich fermented milk tended to be higher than that of the control milk. These results indicate that the GABA-producing strain 01-7 provides fermented milk with other functional components in addition to GABA.

  1. Differential distribution of glutamate- and GABA-gated chloride channels in the housefly Musca domestica.

    PubMed

    Kita, Tomo; Ozoe, Fumiyo; Azuma, Masaaki; Ozoe, Yoshihisa

    2013-09-01

    l-Glutamic acid (glutamate) mediates fast inhibitory neurotransmission by affecting glutamate-gated chloride channels (GluCls) in invertebrates. The molecular function and pharmacological properties of GluCls have been well studied, but not much is known about their physiological role and localization in the insect body. The distribution of GluCls in the housefly (Musca domestica L.) was thus compared with the distribution of γ-aminobutyric acid (GABA)-gated chloride channels (GABACls). Quantitative PCR and ligand-binding experiments indicate that the GluCl and GABACl transcripts and proteins are predominantly expressed in the adult head. Intense GluCl immunostaining was detected in the lamina, leg motor neurons, and legs of adult houseflies. The GABACl (Rdl) immunostaining was more widely distributed, and was found in the medulla, lobula, lobula plate, mushroom body, antennal lobe, and ellipsoid body. The present findings suggest that GluCls have physiological roles in different tissues than GABACls.

  2. Hyperglycosylation and reduced GABA currents of mutated GABRB3 polypeptide in remitting childhood absence epilepsy.

    PubMed

    Tanaka, Miyabi; Olsen, Richard W; Medina, Marco T; Schwartz, Emily; Alonso, Maria Elisa; Duron, Reyna M; Castro-Ortega, Ramon; Martinez-Juarez, Iris E; Pascual-Castroviejo, Ignacio; Machado-Salas, Jesus; Silva, Rene; Bailey, Julia N; Bai, Dongsheng; Ochoa, Adriana; Jara-Prado, Aurelio; Pineda, Gregorio; Macdonald, Robert L; Delgado-Escueta, Antonio V

    2008-06-01

    Childhood absence epilepsy (CAE) accounts for 10% to 12% of epilepsy in children under 16 years of age. We screened for mutations in the GABA(A) receptor (GABAR) beta 3 subunit gene (GABRB3) in 48 probands and families with remitting CAE. We found that four out of 48 families (8%) had mutations in GABRB3. One heterozygous missense mutation (P11S) in exon 1a segregated with four CAE-affected persons in one multiplex, two-generation Mexican family. P11S was also found in a singleton from Mexico. Another heterozygous missense mutation (S15F) was present in a singleton from Honduras. An exon 2 heterozygous missense mutation (G32R) was present in two CAE-affected persons and two persons affected with EEG-recorded spike and/or sharp wave in a two-generation Honduran family. All mutations were absent in 630 controls. We studied functions and possible pathogenicity by expressing mutations in HeLa cells with the use of Western blots and an in vitro translation and translocation system. Expression levels did not differ from those of controls, but all mutations showed hyperglycosylation in the in vitro translation and translocation system with canine microsomes. Functional analysis of human GABA(A) receptors (alpha 1 beta 3-v2 gamma 2S, alpha 1 beta 3-v2[P11S]gamma 2S, alpha 1 beta 3-v2[S15F]gamma 2S, and alpha 1 beta 3-v2[G32R]gamma 2S) transiently expressed in HEK293T cells with the use of rapid agonist application showed that each amino acid transversion in the beta 3-v2 subunit (P11S, S15F, and G32R) reduced GABA-evoked current density from whole cells. Mutated beta 3 subunit protein could thus cause absence seizures through a gain in glycosylation of mutated exon 1a and exon 2, affecting maturation and trafficking of GABAR from endoplasmic reticulum to cell surface and resulting in reduced GABA-evoked currents.

  3. The Role of Genetic Sex in Affect Regulation and Expression of GABA-Related Genes Across Species

    PubMed Central

    Seney, Marianne L.; Chang, Lun-Ching; Oh, Hyunjung; Wang, Xingbin; Tseng, George C.; Lewis, David A.; Sibille, Etienne

    2013-01-01

    Although circulating hormones and inhibitory gamma-aminobutyric acid (GABA)-related factors are known to affect mood, considerable knowledge gaps persist for biological mechanisms underlying the female bias in mood disorders. Here, we combine human and mouse studies to investigate sexual dimorphism in the GABA system in the context of major depressive disorder (MDD) and then use a genetic model to dissect the role of sex-related factors in GABA-related gene expression and anxiety-/depressive-like behaviors in mice. First, using meta-analysis of gene array data in human postmortem brain (N = 51 MDD subjects, 50 controls), we show that the previously reported down-regulation in MDD of somatostatin (SST), a marker of a GABA neuron subtype, is significantly greater in women with MDD. Second, using gene co-expression network analysis in control human subjects (N = 214; two frontal cortex regions) and expression quantitative trait loci mapping (N = 170 subjects), we show that expression of SST and the GABA-synthesizing enzymes glutamate decarboxylase 67 (GAD67) and GAD65 are tightly co-regulated and influenced by X-chromosome genetic polymorphisms. Third, using a rodent genetic model [Four Core Genotypes (FCG) mice], in which genetic and gonadal sex are artificially dissociated (N ≥ 12/group), we show that genetic sex (i.e., X/Y-chromosome) influences both gene expression (lower Sst, Gad67, Gad65 in XY mice) and anxiety-like behaviors (higher in XY mice). This suggests that in an intact male animal, the observed behavior represents the outcomes of male genetic sex increasing and male-like testosterone decreasing anxiety-like behaviors. Gonadal sex was the only factor influencing depressive-like behavior (gonadal males < gonadal females). Collectively, these combined human and mouse studies provide mechanistic insight into sexual dimorphism in mood disorders, and specifically demonstrate an unexpected role of male-like factors (XY genetic sex) on

  4. Expression of estrogen and progesterone receptors in glutamate and GABA neurons of the pubertal female monkey hypothalamus.

    PubMed

    Thind, K K; Goldsmith, P C

    1997-05-01

    We have previously reported direct glutamate (Glu) synapses upon GnRH-containing neurons in the primate hypothalamus, and extensive interactions between Glu and aminobutyric acid (GABA) neurons in areas associated with reproductive function. Both Glu and GABA are known to affect peripubertal GnRH neurohormone release, but their relative roles remain unclear. In a developmental survey, estrogen receptors (ER) and progesterone receptors (PR) were virtually undetectable after immunostaining the hypothalamus of prepubertal monkeys, but were clearly evident in neurons of adults. We hypothesized, therefore, that Glu and GABA neurons which develop ER or PR expression during puberty may participate in reactivation of the hypothalamic-pituitary-gonadal axis. To identify those neurons in midpubertal female cynomolgus monkeys, we performed immunofluorescence staining for ER or for PR in separate sets of hypothalamic sections, and then immunostained for Glu or for glutamate decarboxylase (GAD, to identify GABA neurons) using a contrasting fluorophore. ER and PR were localized in the cytoplasm and nuclei of Glu and GAD neurons in nine hypothalamic and related brain regions. Quantitation revealed intranuclear ER in an average of 80% of the Glu neurons in all regions analyzed, and an average of 84% of the GAD neurons in all regions except the supraoptic nucleus (28%). Intranuclear PR expression was more variable, occurring in an average of 93% of the Glu neurons in seven regions, but in only 41% in the medial preoptic area, and 0% in the arcuate-periventicular zone. In addition, while intranuclear PR was seen in 96% of the GAD neurons in the septum, it appeared in 67% of the GAD neurons in the paraventricular nucleus, 47% in the medial preoptic area, 40% in the periventricular zone, and was absent from neurons in the supraoptic nucleus and mammillary bodies. In summary, certain subpopulations of Glu and GABA neurons in principal hypothalamic regions of the female monkey express

  5. Pregnenolone sulfate block of GABA(A) receptors: mechanism and involvement of a residue in the M2 region of the alpha subunit.

    PubMed

    Akk, G; Bracamontes, J; Steinbach, J H

    2001-05-01

    Neurosteroids are produced in the brain, and can have rapid actions on membrane channels of neurons. Pregnenolone sulfate (PS) is a sulfated neurosteroid which reduces the responses of the [gamma]-aminobutyric acid A (GABA(A)) receptor. We analysed the actions of PS on single-channel currents from recombinant GABA(A) receptors formed from [alpha]1, [beta]2 and [gamma]2L subunits. Currents were elicited by a concentration of GABA eliciting a half-maximal response (50 microM) and a saturating concentration (1 mM). PS reduced the duration of clusters of single-channel activity at either concentration of GABA. PS had no discernable effect on rapid processes: no effects were apparent on channel opening and closing, nor on GABA affinity, and a rapidly recovering desensitised state was not affected. Instead, PS produced a slowly developing block which occurred at a similar rate for receptors with open or closed channels and with one or two bound GABA molecules. The rate of block was independent of membrane potential, implying that the charged sulfate moiety does not move through the membrane field. Change in a specific residue near the intracellular end of the channel lining portion of the [alpha]1 subunit had a major effect on the rate of block. Mutation of the residue [alpha]1 V256S reduced the rate of block by 30-fold. A mutation at the homologous position of the [beta]2 subunit ([beta]2 A252S) had no effect, nor did a complementary mutation in the [gamma]2L subunit ([gamma]2L S266A). It seems likely that this residue is involved in a conformational change underlying block by PS, instead of forming part of the binding site for PS.

  6. GABA inhibition of luminescence from lantern shark (Etmopterus spinax) photophores.

    PubMed

    Claes, Julien M; Krönström, Jenny; Holmgren, Susanne; Mallefet, Jérôme

    2011-03-01

    Photogenic organs (photophores) of the velvet belly lantern shark (Etmopterus spinax) are under hormonal control, since melatonin (MT) and prolactin (PRL) trigger luminescence while α-melanocyte-stimulating hormone (α-MSH) prevents this light to be emitted. A recent study supported, however, the presence of numerous nerve fibres in the photogenic tissue of this shark. Immunohistochemical and pharmacological results collected in this work support these nerve fibres to be inhibitory GABAergic nerves since (i) GABA immunoreactivity was detected inside the photogenic tissue, where previous labelling detected the nerve fibre structures and (ii) GABA was able to inhibit MT and PRL-induced luminescence, which was on the other hand increased by the GABA(A) antagonist bicuculline (BICU). In addition, we also demonstrated that BICU can induce light per se by provoking pigment retraction in the pigmented cells composing the iris-like structure of the photophore, attaining, however, only about 10% of hormonally induced luminescence intensity at 10(-3)mol L(-1). This strongly supports that a GABA inhibitory tonus controls photophore "aperture" in the photogenic tissue of E. spinax but also that MT and PRL have more than one target cell type in the photophores.

  7. Single rodent mesohabenular axons release glutamate and GABA

    PubMed Central

    Root, David H.; Mejias-Aponte, Carlos; Zhang, Shiliang; Wang, Huiling; Hoffman, Alexander F.; Lupica, Carl R.; Morales, Marisela

    2016-01-01

    The lateral habenula (LHb) is involved in reward, aversion, addiction, and depression, through descending interactions with several brain structures, including the ventral teg