大鼠皮层神经元机械性损伤模型中p75NTR、Bax、Bcl -2表达及细胞凋亡

Expressions of p75NTR, Bax and Bcl-2 and cell apoptosis in rat cortical neurons following me- chanical injury

目的 研究大鼠神经元机型性损伤后p75 NTR、Bax、Bcl -2表达改变及神经细胞凋亡情况,分别探讨其在神经元凋亡过程中的作用机制及相互作用方式. 方法 制备大鼠神经元体外培养机械性损伤模型,测定损伤后神经元细胞的凋亡率,依据不同损伤程度分为轻、中、重度损伤组和对照组,应用特异性抗体细胞免疫法检测各组别间神经元Bax、Bcl -2表达的差异.应用Western blot法检测各组间p75NTR蛋白表达水平的差异. 结果 损伤后神经元细胞的凋亡率明显高于正常对照组神经元.重度损伤组较中度损伤组和轻度损伤组显著升高（P＜0.05）.机械性损伤各组均有Bax、Bcl -2的表达,且不同损伤程度组别间表达水平差异有统计学意义.重度损伤组Bax显著高于中度损伤组和轻度损伤组（P＜0.05）. 结论 p75 NTR表达、Bax/Bcl -2比值与神经元凋亡密切相关.p75NTR早期表达可能是神经元损伤后细胞凋亡的因素之一,Bax、Bcl -2可能与这一过程相关.

Objective To study the expressions of p75NTR,Bax and Bcl-2 and cell apoptosis in rat cortical neurons following mechanical injury and discuss the mechanism and mutual action way during the apoptosis of rat neurons after mechanical injury. Methods Cortical neuron cultures were prepared from the brain tissues of day 17 rat embryos and were exposed to mechanical injury seven days after seeding.After the traumatic neuron injury models were created,the apoptosis ratio of neurons was tested at several time points.The models were divided into the minor,moderate,severe injury groups according to the injury severity and the control group.The expressions of Bax and Bcl-2 in each group were detected by immunohistochemistry method and that of p75NTR by Western-blot.Combining with cellular apoptosis ratio in each group shown after FCM analysis,the correlation between the expressions of p75NTR,Bax and Bcl-2 and the apoptosis in rat neurons after mechanical injury could be analyzed. Results The apoptosis ratio of the neurons in all the injury groups was obviously higher than that in the control group,with significantly higher apoptosis ratio of the neurons in the severe injury group than the minor and moderate injury groups （P 〈0.05）.P75NTR,Bax and Bcl-2 were all expressed in all the injury groups,with statistical differences between groups.The expression of Bax in the severe injury group was significantly higher than that in the minor and moderate injury groups（P 〈 0.05 ）. Conclusions p75NTR expression and Bax/Bcl-2 ratio are closely correlated with neuron apoptosis.The early expression of p75NTR may be one of mechnisms for neuronal apoptosis after neuron injury,when Bax and Bcl-2 may be involved.