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GABA Transporter (gaba + transporter)
Kinds of GABA Transporter Selected AbstractsSynapse-specific localization of vesicular glutamate transporters in the rat olfactory bulbEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007Marie-Madeleine Gabellec Abstract Vesicular glutamate transporters (VGLUTs) mediate the packaging of the excitatory neurotransmitter glutamate into synaptic vesicles. Three VGLUT subtypes have so far been identified, with distinct expression patterns in the adult brain. Here, we investigated the spatial distribution of the three VGLUTs in the rat olfactory bulb, a brain region containing a variety of glutamate synapses, both axodendritic and dendrodendritic. Using multilabelling confocal microscopy and electron microscopic immunocytochemistry, we showed that each VGLUT isoform has a highly selective localization in olfactory bulb synapses. VGLUT1 is present at dendrodendritic synapses established by the output neurones (mitral and tufted cells) with bulbar interneurones in the glomerular layer and external plexiform layer, as well as in axonal synapses of the granule cell layer. By contrast, VGLUT2 is strongly expressed in axon terminals of olfactory sensory neurones, which establish synapses with second-order neurones in the glomerular neuropil. VGLUT2 is also found in the outer part of the external plexiform layer and in the granule cell layer but colocalizes only partially with VGLUT1. Finally, we showed that VGLUT3 is exclusively located in the glomerular neuropil, where it colocalizes extensively with the vesicular inhibitory amino acid transporter vesicular GABA transporter, suggesting that it is associated with a subset of inhibitory synapses. Together, these observations extend previous findings on VGLUT distribution in the forebrain, and suggest that each VGLUT subtype has a specific function in the distinct features of axodendritic and dendrodendritic synapses that characterize the olfactory bulb circuit. [source] Epileptogenic roles of astroglial death and regeneration in the dentate gyrus of experimental temporal lobe epilepsyGLIA, Issue 4 2006Tae-Cheon Kang Abstract Recent studies have demonstrated that blockade of neuronal death in the hippocampus cannot prevent epileptogenesis in various epileptic models. These reports indicate that neurodegeneration alone is insufficient to cause epilepsy, and that the role of astrocytes in epileptogenesis should be reconsidered. Therefore, the present study was designed to elucidate whether altered morphological organization or the functionalities of astrocytes induced by status epilepticus (SE) is responsible for epileptogenesis. Glial responses (reactive microgliosis followed by astroglial death) in the dentate gyrus induced by pilocarpine-induced SE were found to precede neuronal damage and these alterations were closely related to abnormal neurotransmission related to altered vesicular glutamate and GABA transporter expressions, and mossy fiber sprouting in the dentate gyrus. In addition, newly generated astrocytes showed down-regulated expressions of glutamine synthase, glutamate dehydrogenase, and glial GABA transporter. Taken together, our findings suggest that glial responses after SE may contribute to epileptogenesis and the acquisition of the properties of the epileptic hippocampus. Thus, we believe that it is worth considering new therapeutic approaches to epileptogenesis involving targeting the inactivation of microglia and protecting against astroglial loss. © 2006 Wiley-Liss, Inc. [source] GAT-1 regulates both tonic and phasic GABAA receptor-mediated inhibition in the cerebral cortexJOURNAL OF NEUROCHEMISTRY, Issue 5 2008Luca Bragina Abstract ,-Aminobutyric acid 1 (GAT-1) is the most copiously expressed GABA transporter; we studied its role in phasic and tonic inhibition in the neocortex using GAT-1 knockout (KO) mice. Immunoblotting and immunocytochemical studies showed that GAT-2 and GAT-3 levels in KOs were unchanged and that GAT-3 was not redistributed in KOs. Moreover, the expression of GAD65/67 was increased, whereas that of GABA or VGAT was unchanged. Microdialysis studies showed that in KOs spontaneous extracellular release of GABA and glutamate was comparable in WT and KO mice, whereas KCl-evoked output of GABA, but not of glutamate, was significantly increased in KOs. Recordings from layer II/III pyramids revealed a significant increase in GABAAR-mediated tonic conductance in KO mice. The frequency, amplitude and kinetics of spontaneous inhibitory post-synaptic currents (IPSCs) were unchanged, whereas the decay time of evoked IPSCs was significantly prolonged in KO mice. In KO mice, high frequency stimulation of GABAergic terminals induced large GABAAR-mediated inward currents associated with a reduction in amplitude and decay time of IPSCs evoked immediately after the train. The recovery process was slower in KO than in WT mice. These studies show that in the cerebral cortex of GAT-1 KO mice GAT-3 is not redistributed and GADs are adaptively changed and indicate that GAT-1 has a prominent role in both tonic and phasic GABAAR-mediated inhibition, in particular during sustained neuronal activity. [source] GeneChip® analysis after acute spinal cord injury in ratJOURNAL OF NEUROCHEMISTRY, Issue 4 2001Guoqing Song Spinal cord injury (SCI) leads to induction and/or suppression of several genes, the interplay of which governs the neuronal death and subsequent loss of motor function. Using GeneChip®, the present study analyzed changes in the mRNA abundance at 3 and 24 h after SCI in adult rats. SCI was induced at T9 level by the New York University impactor by dropping a 10-g weight from a height of 25 mm. Several transcription factors, immediate early genes, heat-shock proteins, pro-inflammatory genes were up-regulated by 3 h, and persisted at 24 h, after SCI. On the other hand, some neurotransmitter receptors and transporters, ion channels, kinases and structural proteins were down-regulated by 3 h, and persisted at 24 h, after SCI. Several genes that play a role in growth/differentiation, survival and neuroprotection were up-regulated at 24 h after SCI. Using real-time quantitative PCR, the changes observed by GeneChip® were confirmed for seven up-regulated (interleukin-6, heat-shock protein-70, heme oxygenase-1, suppressor of cytokine signaling 2, suppressor of cytokine signaling 3, interferon regulatory factor-1, neuropeptide Y), two down-regulated (vesicular GABA transporter and cholecystokinin precursor) and two unchanged (Cu/Zn-superoxide dismutase and phosphatidyl inositol-3-kinase) genes. The present study shows that inflammation, neurotransmitter dysfunction, increased transcription, ionic imbalance and cytoskeletal damage starts as early as 3 h after SCI. In addition to these effects, 24 h after SCI the repair and regeneration process begins in an attempt to stabilize the injured spinal cord. [source] Constitutive Phosphorylation of the Vesicular Inhibitory Amino Acid Transporter in Rat Central Nervous SystemJOURNAL OF NEUROCHEMISTRY, Issue 4 2000Cécile Bedet Abstract:,-Aminobutyric acid (GABA) and glycine are stored into synaptic vesicles by a recently identified vesicular inhibitory amino acid transporter [VIAAT, also called vesicular GABA transporter (VGAT)]. Immunoblotting analysis revealed that rat brain VIAAT migrated as a doublet during sodium dodecyl sulfate,polyacrylamide gel electrophoresis, with a predominant slower band in all areas examined except olfactory bulb and retina. The slower band corresponded to a phosphorylated form of VIAAT as it was converted to the faster one by treating brain homogenates with alkaline phosphatase or with an endogenous phosphatase identified as type 2A protein,serine/threonine phosphatase using okadaic acid. In contrast, the recombinant protein expressed in COS-7 or PC12 cells co-migrated with the faster band of the brain doublet and was insensitive to alkaline phosphatase. To investigate the influence of VIAAT phosphorylation on vesicular neurotransmitter loading, purified synaptic vesicles were treated with alkaline phosphatase and assayed for amino acid uptake. However, neither GABA nor glycine uptake was affected by VIAAT phosphorylation. These results indicate that VIAAT is constitutively phosphorylated on cytosolic serine or threonine residues in most, but not all, regions of the rat brain. This phosphorylation does not regulate the vesicular loading of GABA or glycine, suggesting that it is involved at other stages of the synaptic vesicle life cycle. [source] Hypoalgesia in mice lacking GABA transporter subtype 1JOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2008Yin Fang Xu Abstract ,-Aminobutyric acid (GABA) transporters play a key role in the regulation of GABA neurotransmission. We reported previously that overexpression of the GABA transporter subtype 1 (GAT1), the major form of the GABA transporter in the CNS, led to hyperalgesia in mice. In the present study, nociceptive responses of GAT1-knockout mice (GAT1,/,) were compared with those of heterozygous (GAT+/,) and wild-type (GAT+/+) mice by four conventional pain models (tail-immersion test, hot-plate test, acetic acid,induced abdominal constriction test, and formalin test). In addition, the analgesic effects of two GAT1-selective inhibitors, NO-711 and tiagabine, were examined in all three genotypes using the same four models. Our data demonstrated that GAT1 deficiency because of genetic knockout or acute blockade by selective inhibitors leads to hypoalgesia in mice. These results confirmed the crucial role of GAT1 in the regulation of nociceptive threshold and suggested that GAT1 inhibitors have the potential for clinical use in pain therapy. © 2007 Wiley-Liss, Inc. [source] Plasmalemmal and vesicular ,-aminobutyric acid transporter expression in the developing mouse retinaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2009Chenying Guo Immunoreactivity for the plasma membrane GABA transporter, GAT-3 (red), in a vertical section of adult mouse retina, with the Müller glia identified with CRALBP antibodies (green) and bipolar cell and some Müller cell somata with Chx10 antibodies (blue). J. Comp. Neurol. 512:6,26, 2009. © 2008 Wiley-Liss, Inc. [source] Plasmalemmal and vesicular ,-aminobutyric acid transporter expression in the developing mouse retinaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2009Chenying Guo Immunoreactivity for the plasma membrane GABA transporter, GAT-3 (red), in a vertical section of adult mouse retina, with the Müller glia identified with CRALBP antibodies (green) and bipolar cell and some Müller cell somata with Chx10 antibodies (blue). J. Comp. Neurol. 512:6,26, 2009. © 2008 Wiley-Liss, Inc. [source] Molecular mechanisms supporting a paracrine role of GABA in rat adrenal medullary cellsTHE JOURNAL OF PHYSIOLOGY, Issue 20 2008Hidetada Matsuoka GABA is known to produce membrane depolarization and secretion in adrenal medullary (AM) cells in various species. However, whether the GABAergic system is intrinsic or extrinsic or both in the adrenal medulla and the role that GABA plays are controversial. Therefore, these issues were addressed by combining a biochemical and functional analysis. Glutamic acid decarboxylase (GAD), a GABA synthesizing enzyme, and vesicular GABA transporter (VGAT) were expressed in rat AM cells at the mRNA and protein levels, and the adrenal medulla had no nerve fibre-like structures immunoreactive to an anti-GAD Ab. The double staining for VGAT and chromogranin A indicates that GABA was stored in chromaffin granules. The ,1, ,3, ,2/3, ,2 and , subunits of GABAA receptors were identified in AM cells at the mRNA and protein levels. Pharmacological properties of GABA-induced Cl, currents, immunoprecipitation experiments and immunocytochemistry indicated the expression of not only ,2-, but also ,-containing GABAA receptors, which have higher affinities for GABA and neurosteroids. Expression of GATs, which are involved in the clearance of GABA at GABAergic synapses, were conspicuously suppressed in the adrenal medulla, compared with expression levels of GABAA receptors. Increases in Ca2+ signal in AM cells evoked trans-synaptically by nerve stimulation were suppressed during the response to GABA, and this suppression was attributed to the shunt effect of the GABA-induced increase in conductance. Overall Ca2+ responses to electrical stimulation and GABA in AM cells were larger or smaller than those to electrical stimulation alone, depending on the frequency of stimulation. The results indicate that GABA functions as a paracrine in rat AM cells and this function may be supported by the suppression of GAT expression and the expression of not only ,2-, but also ,-GABAA receptors. [source] Functional segregation of synaptic GABAA and GABAC receptors in goldfish bipolar cell terminalsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2006Mary J. Palmer The transmission of light responses to retinal ganglion cells is regulated by inhibitory input from amacrine cells to bipolar cell (BC) synaptic terminals. GABAA and GABAC receptors in BC terminals mediate currents with different kinetics and are likely to have distinct functions in limiting BC output; however, the synaptic properties and localization of the receptors are currently poorly understood. By recording endogenous GABA receptor currents directly from BC terminals in goldfish retinal slices, I show that spontaneous GABA release activates rapid GABAA receptor miniature inhibitory postsynaptic currents (mIPSCs) (predominant decay time constant (,decay), 1.0 ms) in addition to a tonic GABAC receptor current. The GABAC receptor antagonist (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) has no effect on the amplitude or kinetics of the rapid GABAA mIPSCs. In addition, inhibition of the GAT-1 GABA transporter, which strongly regulates GABAC receptor currents in BC terminals, fails to reveal a GABAC component in the mIPSCs. These data suggest that GABAA and GABAC receptors are highly unlikely to be synaptically colocalized. Using non-stationary noise analysis of the mIPSCs, I estimate that GABAA receptors in BC terminals have a single-channel conductance (,) of 17 pS and that an average of just seven receptors mediates a quantal event. From noise analysis of the tonic current, GABAC receptor , is estimated to be 4 pS. Identified GABAC receptor mIPSCs exhibit a slow decay (,decay, 54 ms) and are mediated by approximately 42 receptors. The distinct properties and localization of synaptic GABAA and GABAC receptors in BC terminals are likely to facilitate their specific roles in regulating the transmission of light responses in the retina. [source] GABAergic Modulation of the Expression of Genes Involved in GABA Synaptic Transmission and Stress in the Hypothalamus and Telencephalon of the Female Goldfish (Carassius auratus)JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2005C. J. Martyniuk Abstract GABA is one of the most abundant neurotransmitters in the vertebrate central nervous system and is involved in neuroendocrine processes such as development, reproduction, feeding and stress. To examine the effect of GABA on gene expression in the brain, we used a cDNA macroarray containing 26 genes involved in GABA synaptic transmission (GABA receptor subunits, GABA transporters), reproduction (gonadotrophin-releasing hormone isoforms and oestrogen receptor ,), feeding (neuropeptide Y and cholecystokinin), and stress [corticotrophin-releasing factor (CRF)]. To elevate GABA levels in the brain, we injected female goldfish with gamma-vinyl GABA (300 µg/g of body weight) (24 h), an irreversible inhibitor of the enzyme GABA transaminase (GABA-T). We found that increased levels of GABA in the hypothalamus resulted in a 2.2-fold down-regulation of GABAA receptor ,4 subunit mRNA. In the telencephalon, we found that increased GABA levels resulted in a 1.5-fold increase of CRF mRNA and a 1.8-fold decrease of GABAA receptor ,2 subunit mRNA. Increasing GABA in the hypothalamus and telencephalon of the goldfish did not significantly affect the mRNA abundance of genes involved in GABA synthesis (glutamic acid decarboxylase isoforms) and degradation (GABA-T), feeding, or reproduction. Our preliminary study suggests that the regulation of GABA receptor subunit mRNA expression by GABA may be a conserved evolutionary mechanism in vertebrates to modulate GABAergic synaptic transmission. [source] Altered gene expression in frontal cortex and midbrain of 3,4-methylenedioxymethamphetamine (MDMA) treated mice: Differential regulation of GABA transporter subtypesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2003Weiping Peng Abstract Changes in gene expression were examined in the brain of mice treated with a drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, also called Ecstasy). Frontal cortex and midbrain mRNA, analyzed by differential display polymerase chain reaction (DD-PCR) method, showed an altered expression of several cDNAs, 11 of which were isolated, cloned and sequenced. The sequence of one MDMA-induced mRNA corresponds (99.3%) to the mouse ,-amino butyric acid (GABA) transporter 1 (mGAT1). The established involvement of GABA neurotransmission in the activity of several abused drugs prompted us to focus herein on MDMA effect on the GABA transporter gene family. Semi-quantitative PCR analysis with primers selective to the reported mGAT1 sequence confirmed that MDMA treatment increased mGAT1 expression. Time-course study of the expression of the three GABA transporter subtypes showed that MDMA induced a differential temporal activation of mGAT1 and mGAT4, but had no effect on mGAT2. Quantitative real-time PCR further proved the increased expression of mGAT1 and mGAT4 upon MDMA treatment. Western immunoblotting with anti-GAT1 antibodies showed that MDMA also increased GAT1 protein levels, suggesting that neurotransmission of GABA was altered. MDMA effect was also verified in serotonin transporter knockout (,/,) mice that are insensitive behaviorally to MDMA; the drug did not increase GAT1 protein level in these mutants. In mice, tiagabine and NO-711, inhibitors of GABA transporters, restrained MDMA-induced acute toxicity and death. These results should facilitate novel approaches to prevent deleterious effects, including fatality, induced by MDMA and similar abused psychostimulants. © 2003 Wiley-Liss, Inc. [source] The GABAergic-like system in the marine demosponge Chondrilla nuculaMICROSCOPY RESEARCH AND TECHNIQUE, Issue 11 2007Paola Ramoino Abstract Gamma-amino butyric acid (GABA) is believed to be the principal inhibitory neurotransmitter in the mammalian central nervous system, a function that has been extended to a number of invertebrate systems. The presence of GABA in the marine demosponge Chondrilla nucula was verified using immunofluorescence detection and high-pressure liquid chromatography. A strong GABA-like immunoreactivity (IR) was found associated with choanocytes, exopinacocytes, endopinacocytes lining inhalant, and exhalant canals, as well as in archaeocytes scattered in the mesohyl. The capacity to synthesize GABA from glutamate and to transport it into the vesicles was confirmed by the presence in C. nucula of glutamate decarboxylase (GAD) and vesicular GABA transporters (vGATs), respectively. GAD-like and vGAT-like IR show the same distribution as GABA-like IR. Supporting the similarity between sponge and mammalian proteins, bands with an apparent molecular weight of about 65,67 kDa and 57 kDa were detected using antibodies raised against mammalian GAD and vGAT, respectively. A functional metabotropic GABAB -like receptor is also present in C. nucula. Indeed, both GABAB R1 and R2 isoforms were detected by immunoblot and immunofluorescence. Also in this case, IR was found in choanocytes, exopinacocytes, and endopinacocytes. The content of GABA in C. nucula amounts to 1225.75 ± 79 pmol/mg proteins and GABA is released into the medium when sponge cells are depolarized. In conclusion, this study is the first indication of the existence of the GABA biosynthetic enzyme GAD and of the GABA transporter vGAT in sponges, as well as the first demonstration that the neurotransmitter GABA is released extracellularly. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] Acotiamide hydrochloride (Z-338), a novel prokinetic agent, restores delayed gastric emptying and feeding inhibition induced by restraint stress in ratsNEUROGASTROENTEROLOGY & MOTILITY, Issue 9 2008K. Seto Abstract, Acotiamide hydrochloride (Z-338) is a member of new class prokinetic agents currently being developed for the treatment of functional dyspepsia (FD). DNA microarray analysis showed that acotiamide altered the expressions of stress-related genes such as , -aminobutyric acid (GABA) receptors, GABA transporters and neuromedin U (NmU) in the medulla oblongata or hypothalamus after administration of acotiamide. Therefore, effects of acotiamide on stress-related symptoms, delayed gastric emptying and feeding inhibition, in rats were examined. Acotiamide significantly improved both delayed gastric emptying and feeding inhibition in restraint stress-induced model, but did not affect both basal gastric emptying and feeding in intact rats, indicating that acotiamide exerted effects only on gastric emptying and feeding impaired by the stress. On the other hand, mosapride showed significant acceleration of gastric emptying in intact and restraint stress-induced model, and itopride showed no effect on restraint stress-induced delayed gastric emptying. In addition, gene expression of NmU increased by restraint stress was suppressed by administration of acotiamide, while acotiamide had no effect on delayed gastric emptying induced by an intracerebroventricular administration of NmU, suggesting that the suppressive effect of acotiamide on gene expression of NmU might be important to restore delayed gastric emptying or feeding inhibition induced by restraint stress. These findings suggest that acotiamide might play an important role in regulation of stress response. As stress is considered to be a major contributing factor in the development of FD, the observed effects may be relevant for symptom improvement in FD. [source] Modulation and function of the autaptic connections of layer V fast spiking interneurons in the rat neocortexTHE JOURNAL OF PHYSIOLOGY, Issue 12 2010William M. Connelly Neocortical fast-spiking (FS) basket cells form dense autaptic connections that provide inhibitory GABAergic feedback after each action potential. It has been suggested that these autaptic connections are used because synaptic communication is sensitive to neuromodulation, unlike the voltage-sensitive potassium channels in FS cells. Here we show that layer V FS interneurons form autaptic connections that are largely perisomatic, and without perturbing intracellular Cl, homeostasis, that perisomatic GABAergic currents have a reversal potential of ,78 ± 4 mV. Using variance,mean analysis, we demonstrate that autaptic connections have a mean of 14 release sites (range 4,26) with a quantal amplitude of 101 ± 16 pA and a probability of release of 0.64 (Vcommand=,70 mV, [Ca2+]o= 2 mm, [Mg2+]o= 1 mm). We found that autaptic GABA release is sensitive to GABAB and muscarinic acetylcholine receptors, but not a range of other classical neuromodulators. Our results indicate that GABA transporters do not regulate FS interneuron autapses, yet autaptically released GABA does not act at GABAB or extrasynaptic GABAA receptors. This research confirms that the autaptic connections of FS cells are indeed susceptible to modulation, though only via specific GABAergic and cholinergic mechanisms. [source] | |||||||||||||