脑缺血再灌流损伤神经细胞凋亡与Bcl-2和caspase-3的关系

The neuronal apoptosis and its relation to the expression of Bcl-2 and Caspase-3 after focal cerebral ischemia reperfusion in rats

目的 探讨大鼠局灶性脑缺血再灌流后神经细胞凋亡及其与 Bcl- 2和 caspase- 3基因表达的关系。方法 应用原位末端标记 (TUNEL)和原位杂交技术分别观察脑缺血再灌流不同时间点神经细胞凋亡的变化与 Bcl- 2 m RNA和 caspase- 3 m RNA的表达。结果 (1 )脑缺血再灌流后凋亡神经细胞主要分布于缺血周围区 ,随着再灌流时间的延长凋亡细胞数逐渐增加 ,至 2 4 h达高峰 ,2 d开始下降 ,1 4 d时仍高于假手术组。 (2 )脑缺血再灌注 2 h后 ,神经细胞 Bcl- 2 m RNA开始表达 ,并随着再灌流时间的延长而增强 ,1 2～ 2 4 h达高峰 ,2 d后逐渐下降 ,至 1 4 d略高于假手术组。 (3)脑缺血再灌流后 ,神经细胞 caspase- 3 m RNA的表达与 Bcl- 2 m RNA的表达规律相似 ,但于再灌流 2 4 h达高峰。结论 脑缺血再灌流后 ,缺血周围区神经细胞的凋亡是一个动态的渐进过程 ,Bcl- 2基因表达可能抑制细胞凋亡 ,caspase- 3基因在介导脑缺血损伤神经元凋亡过程中起关键作用。

Objective To explore the neuronal apoptosis and its relationship to the expression of Bcl-2 and Caspase-3 genes after focal cerebral ischemia reperfusion in rats.Methods The variations of apoptosis on the different time points after focal cerebral ischemia reperfusion were observed with terminal deoxynucleotidyl tranferase mediated dUTP-flourescein nick end-labeling (TUNEL) assay. The expression of Bcl-2 mRNA and Caspase-3 mRNA was determined by in situ hybridization.Results (1) TUNEL-positive cells were located in the inner boundary zone of the infarction and progressively increased and peaked at 24 h after reperfusion, then decreased at 2 d. But the numbers of apoptosis cells were still in high level after 14 h compared with sham-operated group. (2) The expression of Bcl-2 mRNA began at 2 h after reperfusion, peaked at 12 h^24 h, and then decreased at 2 d. The time-phase pattern of Bcl-2 was similar to that of apoptosis. (3) The expression of Caspase-3 mRNA reached a peak at 24 h after reperfusion. The temporal and spatial profile of Caspase-3 mRNA expression was consistent with that of Bcl-2 mRNA.Conclusions The neuronal apoptosis after focal cerebral ischemia reperfusion was a dynamic ongoing process. The expression of Bcl-2 might inhibit apoptosis. Caspase-3 might play a key role in neuronal apoptosis of ischemic brain injury.