缺血后处理对脑缺血再灌注损伤大鼠的脑保护作用及其最佳时间窗的探讨

目的探讨缺血后处理(IP)对大鼠局灶性脑缺血再灌注(I/R)神经保护作用的最佳时间窗。方法 80只雄性SD大鼠,随机分为5组(假手术组、对照组、IP 15s组、IP 30s组和IP 1min组)。假手术组和对照组行单纯I/R;IP 15s组、IP 30s组和IP 1min组,反复3次缺血再灌注。除假手术组外的大鼠均采用线栓法闭塞大鼠大脑中动脉(MACO)建立脑缺血SD大鼠模型。所有大鼠行神经功能障碍评分(NDS),并应用组织原位标记凋亡细胞检测、免疫组织化学等技术观察IP后海马CA1区细胞凋亡及肿瘤坏死因子(TNF-α)表达的变化。结果再灌注24 h后,IP各组NDS明显低于对照组(P<0.05),其中IP 15s组、IP 30s组NDS低于IP 1min组(P<0.05)。对照组海马CA1区TNF-α、凋亡细胞表达量明显增加,IP 15s组、IP 30s组海马CA1区TNF-α、凋亡细胞的表达量较IP 1min组明显下降(P<0.05)。结论 IP可改善局灶性脑缺血大鼠的神经功能、减少海马CA1区炎性因子TNF-α及细胞凋亡的表达。大鼠局灶性脑缺血再灌注损伤保护作用的最佳时间窗为15s、30s。

Neuroprotection and optimal time window of ischemic postconditioning against cerebral ischemia reperfusion injury in rats

Objective To investigate the optimal time window of ischemic postconditioning(IP) against focal cerebral ischemia-reperfusion(I/R) injury.Methods Eighty male SD rats were randomly assigned into five groups: a sham-operated,a control and three IP(different time intervals: 15 s,30 s and 1 min).Focal cerebral ischemia model was established via middle cerebral artery occlusion(MCAO) with the intraluminal filament technique.The neurological deficit scores(NDS) were evaluated 24 hours after reperfusion.The apoptosis of brain cells and the levels of TNF-α in the hippocampal CA1 area were evaluated by TUNEL and immune stained method respectively.Results The behavioral tests showed IP attenuated neurological deficits after I/R.The NDS in the IP groups decreased significantly compared with the control group(P<0.05),and the NDS in the IP 15s and IP 30s groups were lower than in the IP 1min group(P<0.05).The number of surviving neurons increased significantly in the IP groups as compared with the control group(P<0.05).IP significantly decreased the level of TNF-α in the hippocampal CA1 area compared with the control group(P<0.05).The level of TNF-α was significantly higher in the IP1min group than in the IP 15s and IP 30s groups(P<0.05).Conclusions IP could improve functional outcomes,decrease the expression of TNF-α and reduce the nerve cell apoptosis.The optimal time window of IP against cerebral I/R injury may be 15 s and 30 s.