脑缺血再灌注损伤模型大鼠脑组织缺血半暗带病理进程研究

Pathological process of ischemic penumbra in brain tissue of rats with cerebral ischemia-reperfusion injury

目的探讨SD大鼠脑缺血/再灌注损伤(MCAO/R)模型脑组织缺血半暗带(IP)的形成及持续时间,为研究保护缺血半暗带药物的给药时间提供实验依据。方法采用激光多普勒(LDF)和激光散斑(LSI)监测脑血流量(CBF)变化的条件下线栓法复制大鼠脑缺血/再灌注损伤模型,缺血2 h后实施再灌注,取缺血时脑血流量下降至42%~53%,再灌注后脑血流量恢复至50%以上的大鼠纳入实验研究;术前术后监测大鼠血糖、肝温、体重;于再灌注后0、2、6、12、24、72 h随机处死6只大鼠,采用免疫荧光法检测模型大鼠脑组织微管相关蛋白2(MAP-2)的阳性表达和分布,以脑组织微管相关蛋白2阳性表达消失,视野下呈现黑洞状区域作为坏死中心区,以脑组织微管相关蛋白2标记的神经元出现排列混乱,胞体固缩、树突变短甚至消失的区域作为缺血半暗带区,并观察缺血半暗带区持续存在的时间。结果再灌注后大鼠脑缺血/再灌注损伤模型脑组织微管相关蛋白2的阳性表达逐渐变弱,于缺血2 h再灌注6 h后模型大鼠脑组织出现脑组织微管相关蛋白2的阳性表达消失,呈现黑洞状的缺血中心区,并在周围出现神经细胞排列紊乱,大片神经细胞胞体、树突稀疏的缺血半暗带区域,该区持续至再灌注后72 h消失。结论SD大鼠脑缺血/再灌注损伤模型脑组织于缺血2 h再灌注6 h时可见缺血半暗带区形成,缺血半暗带区可持续至再灌注后72 h。

Objective To investigate the formation and duration of ischemic penumbra(IP)in SD rats with cerebral ischemia/reperfusion injury(MCAO/R)model,and provide an experimental basis for studying the administration time of drugs to protect IP.Methods Using laser Doppler flowmetry(LDF)and laser speckle imaging(LSI)to monitor changes in cerebral blood flow(CBF),the MCAO/R model of rats was replicated by thread embolization.Reperfusion was performed after 2 h ischemia,the rats whose CBF decreased to 42%~53%and recovered to more than 50%after reperfusion were included in the experimental study.Blood glucose,body(anal)temperature and body weight were monitored before and after operation.Six rats were randomly killed at 0,2,6,12,24,72 h after reperfusion,Immunofluorescence method was used to detect the positive expression and distribution of neuronal dendritic protein(MAP-2)in the brain tissue of model rats.The positive expression of MAP-2 disappeared,and the black hole-like region appeared in the field of view as the necrotic center,and the persistence of IP region was observed.Results The positive expression of MAP-2 in brain tissue of rat MCAO/R model gradually weakened after reperfusion.After 2 h of ischemia and 6 h of reperfusion,the positive expression of MAP-2 disappeared and showing a black hole-like ischemic center in the brain tissue of the model rats.There was IP with disordered arrangement of nerve cells,large areas of nerve cell bodies and sparse dendrites,which continued to disappear 72 h after reperfusion in the surrounding area.Conclusion The formation of IP area was observed at 2 h ischemia and 6 h reperfusion in MCAO/R model of SD rats,and the IP area could last up to 72 h after reperfusion.