cpg15在脑缺血后海马星形胶质细胞的谷氨酸转运和代谢中的作用及机制

谷氨酸兴奋毒是脑缺血引起神经损伤的一大主要机制。星形胶质细胞（AS细胞）表达的谷氨酸转运体及谷氨酰胺合成酶，是介导谷氨酸摄取和代谢，从而降低兴奋毒的关键蛋白，但其功能调控机制尚不清楚。我们的前期研究提示，神经营养因子cpg15可能通过上调这两类蛋白的基因表达，来促进脑缺血后AS细胞对谷氨酸的摄取和代谢，从而促进其神经保护功能。本项目将在我们前期研究的基础上，采用组织化学、细胞化学、及分子生物学手段，在小鼠脑缺血模型和海马AS细胞氧-糖剥夺模型上，利用基因表达沉默、蛋白免疫吸附、或重组蛋白等方法干预cpg15，或用特异抑制剂干预cpg15下游可能的信号通路分子, 通过比较cpg15 或其下游分子干预前后，AS细胞的两种主要谷氨酸转运体（GLT-1和GLAST）及谷氨酰胺合成酶的表达、以及AS细胞摄取谷氨酸能力等的差异，来探讨cpg15在脑缺血后海马AS细胞的神经保护作用中的功能和机制。

Glutamate induced excitotoxicity is an important mechanism which leads to ischemic neuronal injury. Glutamate transporters and glutamine synthetase expressed by astrocytes are the key proteins that mediate the uptake and metabolism of glutamate respectively and reduce the excitotoxicity. However, the regulation mechanisms of their functions are unknown by far. The results of our previous studies suggest that neurotrophic factor cpg15 might reduce the excitotoxicity neuronal injury induced by cerebral ischemia via up-regulating the gene expression of these two types of proteins, which could increase the astrocytic uptake and metabolism of glutamate. In the present project, histochemistry, cytochemistry and molecular biological analyses will be comprehensively used to investigate the function and mechanism of cpg15 in the neuroprotective function of hippocampal astrocytes after cerebral ischemia, in the transient global cerebral ischemic model of mice, and the oxygen-glucose deprivation model (OGD) of cultured hippocampal astrocytes. The expression level of GLT-1 and GLAST (the two major glutamate transporters in astrocytes) and the glutamine sythetase, and the ability of glutamate-uptake of the astrocytes will be characterized to determine the differences induced by altering cpg15 protein concentration via gene silencing, immunoadsorption, or recombinant cpg15 protein. In addition, inhibition of several possible related signal molecules will be used to investigate the roles of these signal pathways in mediating cpg15-induced neuroprotection.