Immunohistochemical localization of the amino acid transporter SNAT2 in the rat brain
Immunohistochemical localization of the amino acid transporter SNAT2 in the rat brain
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DOI：
10.1016/j.neuroscience.2004.09.023
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发表时间：
2005-01-01
期刊：
影响因子：
3.3
通讯作者：
Zafra, F
中科院分区：
文献类型：
--
作者：
González-González, IM;Cubelos, B;Zafra, F
SNAT2是一种中性氨基酸载体，属于A系统家族。由于它在神经系统中的功能尚不清楚，我们用特异性抗血清分析了它在大鼠中枢神经系统中的分布。虽然SNAT2在中枢神经系统中广泛表达，但在脊髓和脑干核团中也有丰富的表达，尤其是在听觉系统中。在细胞水平上，SNAT2主要定位于神经元胞体和突起，但在脑膜和室管膜也有较强的表达。在间质细胞中，SNAT2在血管末梢周围、神经胶质细胞、小脑星形胶质细胞和Bergmann胶质细胞中表达较强，而在脑实质星形胶质细胞中表达较弱。在神经元中，中脑三叉神经核的初级感觉神经元似乎是SNAT2表达最强的神经元，但许多其他神经元，包括皮质锥体细胞及其树突也被强烈染色。在一些区域的轴突中发现了转运蛋白，特别是在脑干中，共聚焦显微镜和超微结构研究证实了转运蛋白在树突和轴突中的存在。而SNAT2在大的主树突和小的远端树突中可见，但仅在轴突中可见，终末未见。一些谷氨酸能神经元属于标记较强的细胞，而SNAT2在GABA能神经元上未检测到。SNAT2和SNAT1的表达部分一致，尤其是在谷氨酸能神经元。因此，这两种蛋白在补充谷氨酸库方面可以发挥互补作用，并在不同的生理条件下受到不同的调节。它们似乎也共同定位在非神经细胞中，可能有助于氨基酸通过血脑屏障的流动。(C)2004年IBRO。爱思唯尔有限公司出版。保留所有权利。
SNAT2 is a neutral amino acid carrier that belongs to the system A family. Since its function in the nervous system remains unclear, we have analyzed its distribution in the rat CNS using specific antisera. Although SNAT2 is expressed widely in the CNS, it is enriched in the spinal cord and the brainstem nuclei, especially those of the auditory system. At the cellular level, SNAT2 was preferentially located in neuronal cell bodies and processes, although it was also strongly expressed in the meninges and ependyma. In strocytes, the localization of SNAT2 was more restricted since it was intensely expressed in the perivascular end-feet, glia limitans, cerebellar astrocytes and Bergmann glia, but it was less intense in astrocytes of the cerebral parenchyma. Among neurons, the primary sensory neurons of the mesencephalic trigeminal nucleus appeared to be those that most strongly express SNAT2, but many other neurons, including cortical pyramidal cells and their dendrites were also intensely stained. In several regions the transporter was detected in axons, especially in the brainstem, and its presence in both dendrites and axons was confirmed by confocal microscopy and ultrastructural studies. However, while SNAT2 was observed in the large principal dendrites and the small distal dendrites, it was only found in axonal shafts and was excluded from terminals. Some glutamatergic neurons were among the more intensely labeled cells whereas SNAT2 was not detected on GABAergic neurons. The expression of SNAT2 partially coincides with that reported for SNAT1, especially in glutamatergic neurons. Hence, both proteins could fulfill complementary roles in replenishing glutamate pools and be differentially regulated under different physiological conditions. They also seem to co-localize in nonneuronal cells probably contributing to amino acid fluxes through the blood-brain barrier. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.