P2X7 receptor stimulation in primary cultures of rat spinal microglia induces downregulation of the activity for glutamate transport
P2X7 receptor stimulation in primary cultures of rat spinal microglia induces downregulation of the activity for glutamate transport
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DOI：
10.1002/glia.20634
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发表时间：
2008-04-01
期刊：
影响因子：
6.2
通讯作者：
Dohi, Toshihiro
中科院分区：
文献类型：
--
作者：
Morioka, Norimitsu;Abdin, Md. Joynal;Dohi, Toshihiro
已有研究表明，表达某些类型谷氨酸转运体的脊髓小胶质细胞在神经发病机制中起着调节作用。本研究旨在探讨三磷酸腺苷(ATP)对培养的脊髓小胶质细胞谷氨酸转运的影响。GLAST和GLT-1在细胞内均有表达。用三磷酸腺苷或P2X(7)受体的选择性激动剂2‘-3’-O-(4-苯甲酰基-苯甲酰基)三磷酸腺苷(2‘-3’-O-(4-苯甲酰-苯甲酰基)三磷酸腺苷(BzATP)预孵育，可显著阻断谷氨酸的摄取。BzATP的作用可被亮蓝G或氧化的ATP所逆转，两者都是P2X(7)的选择性拮抗剂。在无细胞外Na+或Ca~(2+)存在的情况下，P2X(7)受体的激活也有抑制作用，提示该受体通过代谢途径调节谷氨酸的运输。此外，用丝裂原活化蛋白激酶的抑制剂或抗氧化剂进行预处理，可显著逆转BzATP对谷氨酸摄取的抑制作用。与BzATP孵育后，谷氨酸转运的V-max显著降低，而K-m无明显变化。然而，BzATP处理并没有诱导谷氨酸转运体的运输。这些结果表明，脊髓小胶质细胞中P2X(7)受体的激活在调节谷氨酸转运中起重要作用，它是通过激活细胞外信号调节激酶级联和产生氧化剂来实现的。(C)2008年Wiley-Liss，Inc.
It has been shown that spinal microglia expressing certain types of glutamate transporters function in the modulation of neuropathogenesis. In this study, the effect of ATP, potentially able to mediate the communication between neurons and glial cells in the spinal cord on the transport of glutamate in cultured spinal microglia, was investigated. Both GLAST and GLT-1 were detected in the cells. Preincubation with ATP or 2'-3'-O-(4-benzoyl-benzoyl) ATP (BzATP), a selective agonist for the P2X(7) receptor, significantly blocked the uptake of glutamate. The effect of BzATP was reversed by pretreatment with brilliant blue G or oxidized ATP, each a selective antagonist for P2X(7). The inhibitory effect of P2X(7) receptor activation also occurred in the absence of extracellular Na+ or Ca2+, suggesting that the receptor regulates glutamate transport by a metabotropic pathway. Furthermore, pretreatment with inhibitors of mitogen-activated protein kinase kinase, or antioxidants, significantly reversed the inhibitory effect of BzATP on the uptake of glutamate. Incubation with BzATP led to a marked decrease in the V-max, but not the K-m, of glutamate transport. However, treatment with BzATP did not induce the trafficking of glutamate transporters. These results suggest that the activation of P2X(7) receptors in spinal microglia is important in the regulation of glutamate transport via activation of the extracellular signal-regulated kinase cascade and production of oxidants. (C) 2008 Wiley-Liss, Inc.