Chaudhry F A, Reimer R J, Bellocchio E E, Danbolt N C, Osen K K, Edwards R H, Storm-Mathisen J
Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway.
J Neurosci. 1998 Dec 1;18(23):9733-50. doi: 10.1523/JNEUROSCI.18-23-09733.1998.
A transporter thought to mediate accumulation of GABA into synaptic vesicles has recently been cloned (McIntire et al., 1997). This vesicular GABA transporter (VGAT), the first vesicular amino acid transporter to be molecularly identified, differs in structure from previously cloned vesicular neurotransmitter transporters and defines a novel gene family. Here we use antibodies specific for N- and C-terminal epitopes of VGAT to localize the protein in the rat CNS. VGAT is highly concentrated in the nerve endings of GABAergic neurons in the brain and spinal cord but also in glycinergic nerve endings. In contrast, hippocampal mossy fiber boutons, which although glutamatergic are known to contain GABA, lack VGAT immunoreactivity. Post-embedding immunogold quantification shows that the protein specifically associates with synaptic vesicles. Triple labeling for VGAT, GABA, and glycine in the lateral oliva superior revealed a higher expression of VGAT in nerve endings rich in GABA, with or without glycine, than in others rich in glycine only. Although the great majority of nerve terminals containing GABA or glycine are immunopositive for VGAT, subpopulations of nerve endings rich in GABA or glycine appear to lack the protein. Additional vesicular transporters or alternative modes of release may therefore contribute to the inhibitory neurotransmission mediated by these two amino acids.
一种被认为介导γ-氨基丁酸（GABA）积累到突触小泡中的转运体最近已被克隆（麦金太尔等人，1997年）。这种囊泡GABA转运体（VGAT）是第一个被分子鉴定的囊泡氨基酸转运体，其结构与先前克隆的囊泡神经递质转运体不同，并定义了一个新的基因家族。在这里，我们使用针对VGAT N端和C端表位的特异性抗体，将该蛋白定位在大鼠中枢神经系统中。VGAT高度集中在大脑和脊髓中GABA能神经元的神经末梢，也存在于甘氨酸能神经末梢中。相比之下，海马苔藓纤维终扣虽然是谷氨酸能的，但已知含有GABA，却缺乏VGAT免疫反应性。包埋后免疫金定量分析表明，该蛋白特异性地与突触小泡相关。对外侧上橄榄核中VGAT、GABA和甘氨酸进行三重标记显示，在富含GABA（无论有无甘氨酸）的神经末梢中，VGAT的表达高于仅富含甘氨酸的其他神经末梢。尽管绝大多数含有GABA或甘氨酸的神经末梢对VGAT呈免疫阳性，但富含GABA或甘氨酸的神经末梢亚群似乎缺乏该蛋白。因此，额外的囊泡转运体或其他释放方式可能有助于这两种氨基酸介导的抑制性神经传递。
