大鼠的局灶性脑缺血再灌注损伤分区及再灌注时间窗

目的　研究脑缺血早期神经元损伤、半暗带及再灌注时间窗。方法　采用线栓法制做大鼠大脑中动脉梗阻 /再灌注模型。动物分为 :正常对照组 ;假手术组 ;缺血 (不再灌注 ) 30min组 ;缺血 (不再灌注 ) 1 ,2 ,4,6 ,2 4h ;缺血 1 ,2 ,3h后再灌注 2 4h组。每组 6只。恒温冰冻切片 ,行微管相关蛋白 (MAP2 )免疫组化染色 ;嗜银Ⅲ染色法复染 ;甲苯胺蓝染色。结果　MAP2免疫染色可显示神经元形态和皮质结构 ,显示缺血 30min的神经元病变。病变可分为 :中心区———MAP2阳性消失区 ;半暗带———MAP2阳性减弱伴选择性表达增强 ;继发损伤反应区———MAP2表达增强。缺血 6h内半暗带被迅速扩大的中心区取代 ,同时半暗带的神经元病变进行性加重。再灌注的时间窗应在缺血 3h以内。嗜银神经元集中分布于中心区边缘 ,半暗带也有散在分布 ,MAP2表达增强的神经元不易被银染。结论　MAP2表达增加可能是神经元对抗缺血的保护性反应 ;MAP2免疫染色是显示半暗带的理想的组织学方法

An experimental study on penumbra and reperfusion window in rat focal cerebral ischemia reperfusion model

Objective To determine ischemic penumbra with histological method is important to the study of stroke. However, it is difficult to observe abnormality in early ischemic focus by routine histochemical method. Microtubule associated protein 2 (MAP2) is sensitive to ischemic injury. The objective of present study is to investigate ischemic penumbra and sensitive therapeutic window of reperfusion by MAP2 immunostaining and argyrophil Ⅲ method. Methods Intraluminal suture method was used to develop reversible middle cerebral artery occlusion (MCAO). For ischemia groups, rats were subjected to MCAO for 30minutes, 1, 2, 4, 6 and 24hours respectively. For reperfusion groups, rats were subjected to MCAO for 1, 2 and 3 hours followed by reperfusion for 24 hours. Results MAP2 immunostaining showed neuronal injury within 30 minutes after ischemia and made the ischemic core, penumbra and secondary injury zone clearly visible. The penumbra radically deteriorated in 6 hours after MCAO. The therapeutic window of reperfusion was within 3 hours after MACO. While MAP2 immunoactivity was diminished rapidly in ischemia zone, some neurons in penumbra displayed enhanced perikaryal MAP2 expression, which made them resistant to argyrophil Ⅲ staining. Argyrophil neurons were distributed mainly in ischemic core, less densely in penumbra and not in secondary injury zone. Conclusions MAP2 immunoactivity can be used as a marker to determine penumbra histologically. Selective elevation of neuron MAP2 expression in penumbra may be the protective reaction of the neurons to ischemic injury.