全脑缺血再灌注后神经元凋亡的时相和分布特征

The Time and Distribution Characteristics of Neuron Apoptosis Occurred After Global Cerebral Ischemia

【目的】探讨大鼠全脑缺血再灌注后神经元凋亡的时相和分布特征,为神经元损伤的早期干预和继发性脑损害的防治提供实验依据。【方法】建立大鼠全脑缺血模型,采用TTC染色、原位细胞凋亡检测（原位末端标记法,TUNEL）及AO/EB荧光比色法观察大脑缺血再灌后海马、皮层凋亡发生的数量和分布。【结果】TUNEL显示再灌注3h海马部位即出现散在凋亡细胞,并向皮层区域扩展,24~48 h达高峰;坏死细胞迟于凋亡出现,弥散分布于凋亡细胞周围,再灌注48 h后坏死细胞增多,72 h最多。AO/EB法显示海马、额叶和顶叶凋亡细胞总数分布在再灌注后24 h和72 h达高峰,并显著高于对照组（P〈0.05）。TTC染色证实再灌注后不出现梗死灶,在海马及大脑皮层有弥散性坏死。【结论】全脑缺血再灌后受累神经元经历了由凋亡到死亡的演变过程,对缺血敏感的海马神经元首先受损,并向顶叶和额叶皮层扩展,利用凋亡时间窗进行早期干预可能有益于保护和挽救凋亡前期神经元,减小继发性损害的严重程度。

To investigate the time and distribution characteristics of neuron apoptosis occurred after global cerebral ischemia in rats,so as to provide some helpful experimental basis both for the early interference of injured neuron and the prevention and treatment of brain secondary damage.【Methods】In the global cerebral ischemia model with modified 4-vessel occlusion method,the amount and distribution of apoptotic neuron in hippocampus and cortex after ischemia and reperfusion were detected with TTC staining,TUNEL labeling and AO/EB fluorescence examination techniques.【Results】TUNEL showed that apoptotic neurons scattered in hippocampus 3h after reperfusion,then spread around to cortex.The amount of apoptotic cell reached to the peak at 24~48h.The died cells appeared later and mainly dispersed around the apoptotic cell.There was a significant increase of the amount of died cells 72h after ischemia and reperfusion.AO/EB fluorescence examination showed that the total amount of the apoptotic neurons in hippocampus,frontal cortex and parietal cortex reached their peak value at 24h and 72h respectively,and they were significantly higher than in control group（P〈0.05）.The infarct focus was not found after reperfusion by TTC staining,which expanded around hippocampus and cortex.【Conclusion】The injured neurons undergo a process from apoptosis to death after global cerebral ischemia and reperfusion.Hippocampal neurons,which is quite sensitive to ischemia,are injured first,and then the apoptotic process extends to frontal and parietal cortex.The early interferences in the apoptotic time window are of help both in the protection of neuron in pre-apoptosis stage and reduction of secondary damage severity.