大鼠大脑中动脉阻塞后DNA单链断裂损伤的实验研究

Experiment about single-strand DNA breaks in permanent middle cerebral artery occlusion of rats

目的观察大鼠永久性大脑中动脉阻塞(pMCAO)后,相应区域DNA断裂损伤情况,探讨DNA单链损伤在pMCAO所致脑组织损伤中的意义。方法采用常规HE组织染色明确大鼠pMCAO模型成功与否及其损伤范围,采用DNA聚合酶-1Klenow片段原位杂交方法检测pMCAO不同时间点DNA单链断裂损伤情况。结果损伤区域单链DNA断裂的Klenow阳性细胞在pMCAO后6h即有表达(P<0.01),在24h时达到高峰(P<0.01),72h时有所下降(P<0.01)。结论单链DNA断裂损伤在pMCAO后6h即可出现,并逐渐积累,成为缺血半暗带内细胞损伤发展过程的重要环节,并可能预示半暗带损伤范围的不断扩大。

Aim To observe DNA-strand damages and di scuss the sig-nificance of DNA single strand break s in damaged regions of rat after per-manent middle cerebral artery occlu sion(pMCAO).Methods We used HE stain method to estimate the success ion of model,and utilized DNA poly-merase-ⅠKlenow fragment-mediated nick end-labeling method to detecte DNA single-strand breaks.Results6h after pMCAO,Klenow-positive cells which mean DNA single-strand b reaks were detected in damaged re-gions(P<0.01),24h after pMCAO,the number of Klenow-positive cells reached peak(P<0.01),72h after pMCAO,Klenow-positive c ells were less than those in 24h (P<0.01).Conclusion DNA single-strand breaks emerged at 6hours after pMCAO,and fr om then on,the damages accumu-lated.We presumed that the DNA singl e-strand break might be an important step in the cell damaged procession o f penumbra,and might indicate the expansion of the ischemia penumbra.A,single-strand;DNA polymerase-Ⅰ