人脑创伤后神经元凋亡及调节机制的观察

目的：观察人类急性脑创伤后迟发性神经元死亡现象，了解调节人类神经元凋亡的机制及相关基因表达变化，为临床治疗迟发性神经元死亡寻找新的方法。方法：收集急性脑创伤患者脑标本，采用光镜、电镜以及凋亡细胞原位末端标记法（TUNEL）观察创伤后神经元DNA损伤情况；用原位杂交、免疫组化法观察bcl-2、bax、p53、caspase-3 p20亚单位在mRNA与蛋白质水平表达变化。结果：人脑创伤后有细胞凋亡现象发生，24h左右最为明显。正常人脑组织中几乎没有bcl-2、p53 mRNA及蛋白以及活化的caspase-3存在。急性创伤后bcl-2、p53 mRNA及蛋白表达增加；caspase-3被激活。正常人脑组织持续性表达高水平bax mRNA及蛋白，创伤后bax mRNA及蛋白表达升高。结论：人脑创伤后有细胞凋亡现象发生。人脑创伤造成bcl-2、bax、p53 mRNA及蛋白表达增加；caspase-3酶活性增加。

Human neural apoptosis and regulation mechanism of apoptosis-related genes following traumatic brain injury

Objective To observe human neural apoptosis and understand regulation mechanism and expression changes of apoptosis related genes posterior to traumatic brain injury (TBI) so as to explore a fresh therapy for delayed neural death. Methods The specimens from patients with acute TBI were collected to observe the DNA injury by means of light, electrical microscopes and TUNEL after TBI. By RT PCR, in situ hybridization and immunohistochemistry, the expression changes of bcl 2, bax, p53 and caspase 3 p20 subunit at mRNA and protein level were observed. Results Apoptotic neurons occurred following TBI and peaked at the 24th hour. The normal brain tissues rarely contained mRNA or protein of bcl 2 and p53 or activated caspase 3. In a short time after TBI, the mRNA and protein expressions of bcl 2 and p53 increased and caspase 3 was activated. The primary expressions of bax mRNA and bax protein were continuously high in the normal brain tissues. After TBI, the expression level of bax mRNA and bax protein increased and remained high for 2 3 days. Conclusions Following TBI, apoptotic neurons appear around the traumatized focus in human brain, which helps increase the protein and mRNA expressions of bcl 2, bax and p53 and the activity of caspase 3 enzyme.