慢性脑低灌注诱导神经细胞凋亡的实验研究

Experimental study on neuronal apoptosis induced by chronic cerebral hypoperfusion in rats

亡的时程变化。方法30只SD大鼠随机分为对照组(n=5)、模型不灌注组(n=5)、模型再灌注组动物按正常灌注压恢复后不同时间点分组(0h,n=5;12h,n=5;24h,n=5;72h,n=5)。模型组动物行右侧颈外静脉-颈总动脉端侧吻合,同时结扎左侧横窦引流静脉和双侧颈外动脉。术后3个月,阻断颈部动静脉分流造成模型组动物脑组织再灌注。流式细胞仪定量检测并比较各组动物右侧大脑中动脉区脑组织中神经细胞凋亡率,透射电镜观察神经元的超微结构。结果术后3个月,对照组和模型不灌注组动物脑组织中神经细胞凋亡率无明显差别。模型组动物再灌注即刻(0h)未见明显的神经细胞凋亡,再灌注12h神经细胞凋亡率开始明显增加,24h达高峰,72h降低。电镜证实神经细胞凋亡的存在。结论在慢性脑低灌注状态下,恢复正常灌注压可导致继发性神经细胞损害,可能与脑动静脉畸形切除术后迟发性神经功能障碍有关。

Objective A new animal model of chronic cerebral hypoperfusion was created to study the time-course of neuronal apoptosis during restoration of normal perfusion pressure. Methods Thirty Sprague-Dawley rats were randomly divided into either a control group (n=5), a model group with no reperfusion (n=5), or a model group with reperfusion assessed at various time points after restoration of normal perfusion pressure(0h,n=5;12h,n=5;24h,n=5;72h,n=5). Animals in model group were accomplished by end-to-side anastomosis between the right external jugular vein and common carotid artery, as well as ligation of the left vein draining the transverse sinus and bilateral external carotid arteries. Three months later, occlusion of carotid-jugular shunting resulted in reperfusion in rat brains of the model group. Flow cytometry was used to assess the percentage of apoptotic cells quantitatively in the right cortical tissues of the middle cerebral artery (MCA) territory in all groups, which was also confirmed by transmission electron microscopy. Results There was no difference of the percentage of apoptotic cells in rat brains between the control group and the model group with no reperfusion using flow cytometry. No prominent apoptotic cells was found in the model group with reperfusion at 0h. However, the percentage of apoptotic cells increased significantly in rat brains of the model group with reperfusion at 12h, peaked at 24h, and decreased at 72h after reperfusion. Electron microscopy examination confirmed the presence of apoptotic cells. Conclusion Restoration of normal perfusion pressure under chronic cerebral hypoperfusion may result in secondary neuronal damage in rats, which may be related to delayed neurological deterioration following resection of cerebral AVMs.