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Vesicular GABA Transporter (vesicular + 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] 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] 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] 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] | ||||||||||