Nishimura M, Sato K, Mizuno M, Yoshiya I, Shimada S, Saito N, Tohyama M
Department of Anesthesiology, Osaka University Medical School, Suita, Japan.
Brain Res Mol Brain Res. 1997 May;45(2):268-74. doi: 10.1016/s0169-328x(96)00259-8.
The localization of GABA transporters 1-3 (GAT1-3) was investigated in the rat olfactory bulb by using in situ hybridization and immunohistochemistry. In the glomerular and the internal granular layers, GAT1 mRNA was expressed in most of periglomerular and granule cells, which are known to be GABAergic. In addition, we compared GAT1 mRNA expression with that of glutamic acid decarboxylase67 (GAD67) mRNA. The expressions were very similar in these two layers, indicating that GAT1 mRNA is mainly expressed in GABAergic neurons. However, in the external plexiform and the olfactory nerve layers, we observed more GAT1 mRNA-positive cells than GAD67 ones, suggesting that GAT1 mRNA is also expressed in non-GABAergic neurons and in glial cells. GAT3 mRNA expression was observed in small glial-like cells which might be involved in GABAergic neurotransmission throughout the olfactory bulb. This was confirmed by double-immunostaining studies which showed the expression of both GAT3 and glial fibrillary acidic protein (GFAP) mRNAs in astrocytes. Moreover, GAT2 mRNA was expressed only in the ependyma and arachnoid. These findings suggest that the expression patterns of GABA transporters differ with the type of cells in the rat olfactory bulb where GAT1 and GAT3 may play an imporatant role in GABA-mediated transmission, such as lateral inhibition.
利用原位杂交和免疫组织化学技术，在大鼠嗅球中研究了γ-氨基丁酸转运体1 - 3（GAT1 - 3）的定位。在肾小球层和内颗粒层，GAT1 mRNA在大多数已知为γ-氨基丁酸能的球周细胞和颗粒细胞中表达。此外，我们将GAT1 mRNA的表达与谷氨酸脱羧酶67（GAD67）mRNA的表达进行了比较。这两层中的表达非常相似，表明GAT1 mRNA主要在γ-氨基丁酸能神经元中表达。然而，在外侧丛状层和嗅神经层，我们观察到GAT1 mRNA阳性细胞比GAD67阳性细胞更多，这表明GAT1 mRNA也在非γ-氨基丁酸能神经元和神经胶质细胞中表达。在整个嗅球中，在可能参与γ-氨基丁酸能神经传递的小胶质样细胞中观察到GAT3 mRNA的表达。双重免疫染色研究证实了这一点，该研究显示星形胶质细胞中同时表达GAT3和胶质纤维酸性蛋白（GFAP）mRNA。此外，GAT2 mRNA仅在室管膜和蛛网膜中表达。这些发现表明，γ-氨基丁酸转运体的表达模式因大鼠嗅球中的细胞类型而异，其中GAT1和GAT3可能在γ-氨基丁酸介导的传递（如侧向抑制）中发挥重要作用。
