Neuroprotective effect of cyosporinA. (Study for mitochordrial permeability transition pore and cytochromeC)

采用mdrla基因敲除(KO)小鼠局灶性脑缺血模型，观察环孢素A(CsA)对脑缺血的疗效。首先建立FVB小鼠(野生型mdria基因敲除小鼠)局灶性脑缺血模型，再灌流期间给予CsA 10 mg/kg，缩小模型的脑梗塞范围。这一结果首次证明CsA对小鼠脑缺血具有神经保护作用。在mdrla KO小鼠中，我们证明了在再灌注后给予CsA 2 mg/kg甚至1 mg/kg可显著减少梗塞面积。这些结果表明，如果CsA到达脑实质，它具有强大的神经保护作用。有趣的是，10 mg/kg CsA对mdrla KO小鼠局灶性脑缺血模型无效。10 mg/kg CsA对mdala KO小鼠来说可能太多了，因为CsA在大脑中的浓度可能异常高。然而，CsA在缺血再灌注损伤中具有保护作用的机制尚不明确。应用我们建立的mdria KO小鼠CsA模型，用免疫印迹法检测再灌流过程中脑组织细胞色素C的变化。CsA 1 mg/kg组小鼠脑内细胞色素C低于赋形剂组小鼠。这一结果提示CsA可阻止线粒体通透性转换孔的开放，并阻止细胞色素C从孔中释放。

We investigated the efficacy of cyclosporin A (CsA) for brain ischemia using focal ischemic model of mdrla knockout (KO) mice which lacks p-glycoprotein resulting CsA easily pass through blood brain bomer (BBB). At first, we made focal ischemic model of FVB mice (wild type of mdria knockout mice), then 10mg/kg CsA administered during reperfusion, diminishes infarct size in the model. This result is the first evidence of CsA's neuroprotective effect in mice brain ischemia. In mdrla KO mice, we demonstrate 2mg/kg and even 1mg/kg CsA significantly reduce infarct size when administered after reperfusion. These results suggest that CsA has potent neuroprotective effect, if it reaches brain parenchyma. Interestingly, 10mg/kg CsA administration is not effective in focal ischemic model of mdrla KO mice. 10mg/kg CsA may be too much for mdala KO mice because CsA concentration in the brain is possibly unusually high. The mechanism whereby CsA is protective in ischemia-reperfusion damage is however equivocal. Using our CsA model of mdria KO mice, cytosolic cytochrome C in the brain was analyzed by Western blot during reperfusion. Cytosolic cytochrome C in CsA 1mg/kg administrated KO mice brain was lower than that of vehicle administrated mice. This result suggests that CsA prevents mitochondrial permeability transition pore opening, and release of cytochrome C from the pore.