肌苷对大鼠脑缺血再灌注后钙调神经磷酸酶和环氧合酶-2表达的影响

The effect of Inosine on the expression of Calcineurin and cyclooxygenase-2 following the reperfusion of MCAO in rats

目的:研究肌苷对大鼠脑缺血再灌注后CaN和COX-2蛋白表达的影响,探讨其神经保护作用机制。方法:应用线栓法建立大鼠脑缺血再灌注动物模型,腹腔注射肌苷(100mg/kg),采用免疫组织化学法检测肌苷对大鼠脑缺血再灌注不同时间内CaN及COX-2蛋白的影响。结果:①对照组皮质和纹状体区大鼠脑CaN蛋白表达在脑缺血再灌注6h开始增强,12-24h达高峰,随即下降,至3d已降至再灌注2h水平。与再灌注2h相比,6h-2d组均有显著差异(P<0.01)。肌苷组CaN表达于2h-14d较对照组显著降低(P<0.01)。②对照组皮质和纹状体区COX-2表达在脑缺血再灌注6h开始增强,24h-2d达高峰,然后逐渐降低,14天时几乎未检测到COX-2阳性细胞。与再灌注2h相比,6h-3d组差异均有显著性意义(P<0.01)。肌苷组COX-2表达于脑缺血再灌注2h-14d较对照组显著减低(P<0.01)。皮质中的阳性细胞数高于纹状体区。结论:肌苷对缺血后脑损伤的保护作用可能通过影响大鼠脑CaN、COX-2的表达而实现的。

Objective:From the shift of the expression of Calcineurin (CaN) and clyooxygenase-2(COX-2), to observ its possible mechamism on the ischemic cerebral tissue, and to explore whether the protective effect of Inosine is relevant to the expression after reperfusion of MCAO in rats. Method: The reperfusion of focal cerebral ischemia models were established with SD rats, which were divided into the control group (saline solution was injected intraperitoneally) and the inosine group(inosine was injected intraperitoneally,100mg/kg).Each group was divided into eight subgroups which consisted of 4 rats.At 2h、6h、12h 、24h、2d、3d、7d 、14d after reperfusion of MACO, immunohistochemical techniques were used to investigate the dynamic changes of CaN and COX -2 in cerebral tissue.Result:①CaN:The expression of CaN increased temporarily at 6h,12h and 24h, then decreased immediately after MCAO. On the 3rd day, it dropped to the level of reperfusion 2h in cortex and striatum. Compared with the reperfusion 2h,the level of 6h-3d was obviously increased(P<0.01). After inosine injection, the level of CaN was lower than that in the control group (P<0.01). ②COX-2:The expression of COX-2 occurred at 6h,with the peak at 24h-2d after reperfusion and dropped gradually; and it can scarcely be detected at 14d.Compared with the reperfusion at 2h, the level of 6h-3d were markedly increased(P<0.01). Inosine could significantly decrease the number of COX-2 positive cells compared with the control group,P<0.01.The level of COX-2 in cerebral cortex was higher than that in striatum.Conclusion: Inosine could protect brain tissue against hypoxic-ischemic damage after reperfusion of focal cerebral ischemia, whose role might be reflected by decreasing the expression of CaN and COX-2.