Itouji A, Sakai N, Tanaka C, Saito N
Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Japan.
Brain Res Mol Brain Res. 1996 Apr;37(1-2):309-16. doi: 10.1016/0169-328x(95)00342-p.
The localization of GABA transporters (GAT1 and GAT3) was examined immunocytochemically in the rat cerebellum at both light and electron microscopic levels using antibodies specific for each subtype. Immunoblot analysis showed that the antibodies against GAT1 and GAT3 specifically recognized their respective antigens in the cerebellum. Both GAT1 and GAT3 were found in the neuropil but not in neuronal somata or glial cell bodies. GAT1 immunoreactivity was seen throughout all layers of the cerebellar cortex with the highest immunoreactivity in the molecular layer, but little immunoreactivity was found in the deep cerebellar nuclei. GAT1 immunoreactivity was seen in the pinceau area of the Purkinje cell layer and in the mossy fiber glomeruli in addition to the neuropil of the molecular layer. Weak GAT3 immunoreactivity was found in the granular layer of the cerebellar cortex, and intense immunoreactivity was observed around the unstained large neurons in the deep cerebellar nuclei. Electron microscopic analysis of the cerebellum revealed that GAT1 immunoreactivity was predominantly localized in the presynaptic terminals, while GAT3 immunoreactivity was localized in the glial processes. These results suggested that GABAergic transmission at synapses is terminated by three GABA uptake systems, (1) only neuronal uptake through GAT1, (2) only glial uptake through GAT3, and (3) both neuronal and glial uptake through GAT1 and GAT3 respectively, and also that the GABA uptake system is different in each type of GABAergic neuron.
利用针对每种亚型的特异性抗体，通过免疫细胞化学方法在光镜和电镜水平上研究了大鼠小脑γ-氨基丁酸转运体（GAT1和GAT3）的定位。免疫印迹分析表明，抗GAT1和GAT3的抗体在小脑中能特异性识别各自的抗原。GAT1和GAT3均存在于神经毡中，但在神经元胞体或胶质细胞体中未发现。GAT1免疫反应性在小脑皮质的所有层均可见，分子层的免疫反应性最高，但在小脑深部核团中免疫反应性较低。除了分子层的神经毡外，在浦肯野细胞层的夹钳区和苔藓纤维小球中也可见GAT1免疫反应性。在小脑皮质颗粒层发现较弱的GAT3免疫反应性，在小脑深部核团中未染色的大神经元周围观察到强烈的免疫反应性。对小脑的电镜分析显示，GAT1免疫反应性主要定位于突触前终末，而GAT3免疫反应性定位于胶质细胞突起。这些结果表明，突触处的γ-氨基丁酸能传递通过三种γ-氨基丁酸摄取系统终止，（1）仅通过GAT1的神经元摄取，（2）仅通过GAT3的胶质细胞摄取，以及（3）分别通过GAT1和GAT3的神经元和胶质细胞摄取，并且γ-氨基丁酸摄取系统在每种γ-氨基丁酸能神经元类型中是不同的。
