局灶性脑缺血大鼠神经细胞凋亡及其调控基因bcl-2的表达

Neuronal Apoptosis and Gene bcl-2 Expression Induced by Cerebral Focal Ischemia in Rats

目的 观察大鼠脑缺血再灌注后神经细胞凋亡和 bcl- 2基因表达情况及其相互关系。方法 采用健康雄性SD大鼠大脑中动脉阻断 (MCAO)模型 ,阻断 MCA血流 2 h后再灌注 ,在不同再灌注时间点断头取脑后 ,连续切片分别作 HE染色、TUNEL染色及 bcl- 2蛋白免疫组化染色。结果 1MCAO后 ,缺血区部分神经细胞发生了凋亡 ,随着再灌注时间的延长 ,凋亡细胞数目逐渐增多 ,1天时达高峰 ,各再灌注时间组之间差异显著 (P<0 .0 1)。 2凋亡抑制基因 bcl- 2有不同程度表达 ,再灌注早期 (6 h)即达高峰 ,各组表达有显著差异 (P<0 .0 1) ;3神经细胞凋亡的出现与 bcl- 2表达在一定时程内呈直线负相关 (r=- 0 .747,P<0 .0 1)。结论 脑缺血再灌注损伤时 ,神经细胞凋亡起着重要作用 ,而 bcl- 2的表达则对凋亡起抑制作用。

Objective To investigate the relationship between neuronal apoptosis and its regulating gene bcl-2 in male SD rats subjected to transient focal ischemia and reperfusion injury of the brain. Medthods\ The middle cerebral artery(MCA) of rats was occluded for 2 hours by the MCAO model, and reperfusion was instituted for 0.5, 6, 24 and 72 hours. At each time three slices of rat brains at the level of the anterior commissure were made consecutively for HE staining, TUNEL staining and anit-bcl-2 oncoprotein antibody staining. Results \ ①The number of apoptotic cells increased with the development of reperfusion within a certain time, and reached its peak in 24 hours. The difference of each group was significant (P<0.01). ②The apoptosis -inhibiting gene bcl-2 was highly expressed at the beginning of reperfusion ,and also there was a significant diffence among five groups(P<0.01). ③A negative correlation was observed between the neuronal apoptosis and the expression of bcl-2 oncoprotein during the testing time (r=-0.747, P<0.01). Conclusion\ The neuronal apoptosis may play an important role in cerebral transient focal ischemia and reperfusion. However, the expression of bcl-2 oncoprotein may inhibit the apoptosis.