Expression of glutamate transporters in rat optic nerve oligodendrocytes
Expression of glutamate transporters in rat optic nerve oligodendrocytes
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DOI：
10.1046/j.1460-9568.1999.00639.x
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发表时间：
1999-07-01
影响因子：
3.4
通讯作者：
Matute, C
中科院分区：
文献类型：
--
作者：
Domercq, M;Sánchez-Gómez, MV;Matute, C
为了研究谷氨酸在非突触胶质细胞中的转运作用，我们采用逆转录-聚合酶链反应联合Western blot和免疫化学特异性抗体，对大鼠视神经中三种主要谷氨酸转运体（EAAC1、GLAST和GLT-1）的原位表达进行了表征。GLAST定位于束间少突胶质细胞，而细胞亚群，可能是未成熟的少突胶质细胞，表达EAAC1。相比之下，星形胶质细胞只表达GLT-1，这与GLT-1是这种细胞类型中主要的谷氨酸转运蛋白的观点一致。此外，我们观察到谷氨酸代谢的关键酶谷氨酰胺合成酶在少突胶质细胞中原位定位。为了研究这些谷氨酸转运体的特性，我们在胶质细胞培养中进行了摄取实验。围产大鼠视神经少突胶质细胞钠依赖性谷氨酸摄取动力学与新生大鼠大脑皮层1型星形胶质细胞明显不同，具有更高的亲和力和更低的Vmax。在这两种细胞类型中，谷氨酸转运均被l -反式吡咯烷-2,4-二羧酸酯（t-PDC）抑制。相比之下，二氢海碱盐在少突胶质细胞中的摄取抑制作用明显大于1型星形胶质细胞。这些结果为功能性钠依赖性谷氨酸转运蛋白在视神经少突胶质细胞中的表达提供了证据，并提示这种细胞类型可能在谷氨酸-谷氨酰胺循环中发挥作用。
To investigate the role of glutamate transport in non-synaptic glia, we characterized the expression of three major glutamate transporters (EAAC1, GLAST and GLT-1) in rat optic nerve in situ using reverse transcription-polymerase chain reaction in combination with Western blot and immunochemistry with specific antibodies. GLAST was localized to interfascicular oligodendrocytes, whereas a subpopulation of cells, probably immature oligodendrocyte cells, expressed EAAC1. In contrast, astrocytes, expressed only GLT-1, consistent with the idea that this is the major glutamate transporter in this cell type. In addition, we observed that glutamine synthetase, a key enzyme in glutamate metabolism, was localized in oligodendrocytes in situ. To examine the properties of these glutamate transporters, we conducted uptake experiments in glial cultures. The kinetics of sodium-dependent glutamate uptake in cultured oligodendrocytes from the perinatal rat optic nerve were markedly different from those observed in type-1 astrocytes from the newborn rat cerebral cortex, with higher affinity and lower Vmax. In both cell types, glutamate transport was inhibited by L-trans-pyrrolidine-2,4-dicarboxylate (t-PDC). In contrast, dihydrokainate exhibited significantly more uptake inhibition in oligodendrocytes than in type-1 astrocytes. These results provide evidence for the expression of functional sodium-dependent glutamate transporters in optic nerve oligodendrocytes, and suggest that this cell type may play a role in the glutamate-glutamine cycle.