短暂性脑缺血对老年大鼠海马神经元凋亡的影响

目的 探讨短暂性脑缺血对老年大鼠海马神经元凋亡的影响。方法 健康老年雄性Wistar大鼠100只，按Pusinelli方法建立四动脉阻断法全脑缺血模型，随机分为4组（n=25）：脑缺血1min组（I1组）、脑缺血3min组（I3组）、脑缺血5min组（15组）和假手术组（C组）。每组均于再灌注12h、1d,2d、3d和7d各随机处死5只大鼠。随机取其中4只大鼠的海马组织制作石蜡切片，另1只大鼠断头处死后，冰上提取海马CAl区脑组织，制作电镜标本。透射电镜观察神经元超微结构，TUNEL法检测神经元凋亡，免疫组织化学法检测caspase．3的表达。结果 各组于光镜和电镜下均可见凋亡神经元。与C组、I1组相比，I3组、I5组凋亡细胞数和caspase-3表达阳性细胞数均增高（P〈0．05）；与I3组相比，I5组凋亡细胞数和caspase-3表达阳性细胞数均增高（P〈0．05）。结论 脑缺血3～5min对老年大鼠不产生预处理的效果，可引起脑神经元凋亡。

Effects of transient global cerebral ischemia on apoptosis in hippocampal neurons in aged rats

Objective To investigate the effects of transient global cerebral ischemia on apoptosis in hippocampal neurons in aged rats.Methods One hundred healthy old male Wistar rats aged 19-21 months (corresponding to 60 year old human being)weighing 420-670 g were randomly divided into 4 groups(n=25 each):group A acute global cerebral ischemia 1 min;group B 3 min ischemia;grouop C 5 min ischemia and group D sham operation(control).The animals were killed at the end of predetermined duration of reperfusion 12 h,1 d,2 d,3 d and 7 d respectively.The brains were immediately removed and hippocampal CA1 region was isolated for(1)light and electron microscopic examination of hippocampal neurons,(2)detection of apoptotic neurons(TUNEL)and(3)determination of caspase-3 protein expression using SABC immuno-histochemical technique.Results There was no significant difference in the number of apoptotic neurons and expression of caspase-3 protein in hippocampal CA 1 region between group A(1 min ischemia)and D(control).The number of apoptotic neurons and caspase-3 protein expression were significantly increased in group B and C(3 and 5 min ischemia)as compared with group A and D.The increase in the number of apoptotic neurons and caspase-3 protein expression started at the end of 12 h reperfusion,reached the plateau on the 1st,2nd and 3rd day of reperfusion and was declining on the 7th day of reperfusion.Conclusion The aged rats are more sensitive to cerebral ischemia/reperfusion injury.Three to five minute transient cerebral ischemia can significantly increase the number of apoptotic neurons and caspase-3 protein expression in hippocampal CA1 region.