Role of astrocytes in brain function

为了阐明星形胶质细胞在脑功能中的作用，我们对星形胶质细胞中的信号转导进行了研究，得到了以下结果：(1)Kakkon-to和Sano-Shashin等Kampo药物能有效地抑制兔星形胶质细胞前列腺素E_2的产生。Ougon是星形胶质细胞磷脂酶A_2的有效抑制剂。这些结果表明，坎波族药材中含有抑制磷脂酶A_2的物质。(2)研究了马斯托帕兰对星形胶质细胞信号转导的影响。马斯托帕兰对兔星形胶质细胞和1321N1人星形细胞瘤细胞磷脂酶C的抑制作用在1321N1人脑星形细胞瘤细胞中，首次证实了马斯多兰以G蛋白不敏感的方式激活磷脂酶D。Mastoparan还通过Gi激活兔星形胶质细胞的磷脂酶A_2。(3)血栓素A_2(TXA_2)受体介导的信号转导分析表明，在人脑星形细胞瘤细胞…中，血栓素A_2受体与GQ偶联S和兔星形胶质细胞较多。1321N1 Himan星形细胞瘤细胞的TXA2受体脱敏过程分为两步，一步是TXA2受体与G蛋白解偶联，另一步是其受体从细胞表面消失(下调)。在TXA2受体脱敏过程中，TXA2受体的mRNA水平没有变化。(4)从生物活性物质海洋来源的影响分析，xestoquone能激活IP_3诱导的1321N1人脑星形细胞瘤细胞内钙离子的释放。辣根毒素诱导1321N1人脑星形细胞瘤细胞胞外钙依赖的磷脂酶C-γ亚型激活。5)神经胶质细胞培养上清液对PC-12细胞的分化有较强的刺激作用，其作用强于神经生长因子。结果提示，星形胶质细胞对中枢神经系统具有多种重要的调控功能，星形胶质细胞的信号转导可能有助于了解脑的功能。较少

In order to clarify the role of astrocytes in brain function, we investigated the signal transduction in astrocytes and obtained the following results.(1) Kampo medicine such as Kakkon-to and san'o-shashin-to potently inhibit prostaglandin E_2 generation in rabbit astrocytes. Ougon (Scutellarie Radix) is a potent inhibitor of phospholipase A_2 in astrocytes. These results suggest that kampo medicines contain substances which inhibit phospholipase A_2. (2) The effect of mastoparan on signal transduction in astrocytes was investigated. Mastoparan inhibits phospholipase C in rabbit astrocytes and 1321N1 human astrocytoma cells. It is demonstrated for the first time that mastoparan activates phospholipase D in a G protein-insensitive manner in 1321N1 human astrocytoma cells. Mastoparan also activates phospholipase A_2 via Gi in rabbit astrocytes. (3) From the analysis of thromboxane A_2 (TXA_2) receptor-mediated signal transduction, TXA_2 receptor is coupled to Gq in human astrocytoma cell … More s and rabbit astrocytes. TXA_2 receptor desensitization in 1321N1 himan astrocytoma cells is divided into two steps, one is uncoupling of TXA_2 receptor and G protein, and the other is its receptor loss from cell surface (downregulation). The mRNA level of TXA_2 receptor is unchanged during TXA_2 receptor desensitization. (4) From the analysis of the effect of bioactive substances marine origin, xestoquinone activates IP_3-induced Ca^<2+> release from store site in 1321N1 human astrocytoma cells. Maitotoxin induces tyrosine kinase-mediated activation of phospholipase C-gamma isoform in a extracellular Ca^<2+>-dependent manner in 1321N1 human astrocytoma cells. 5) Supernatant of glial cell culture potently stimulated the differentiation of PC-12 cells with a potency more than nerve growth factor. The results obtained suggest that astrocytes have several important functions to control central nervous system, and signal transduction of astrocytes may contribute to understand the function of brain. Less