面神经损伤模型中的半胱氨酸天冬氨酸蛋白酶相关蛋白表达与损伤相关性

摘要

背景：半胱氨酸天冬氨酸蛋白酶在细胞凋亡中发挥着关键作用，但不同形式面神经损伤对半胱氨酸天冬氨酸蛋白酶3和8和cyto-c蛋白表达的影响及其相互关系，目前尚不清楚。　　目的：构建大鼠面神经压榨伤及低位切断伤模型，观察面运动神经元的形态学改变和死亡相关基因半胱氨酸天冬氨酸蛋白酶3和8及cyto-c的表达变化并分析其相关性。　　方法：制作大鼠右侧面神经的压榨伤和低位切断伤模型，左侧为正常对照侧。用甲苯胺蓝染色及透射电镜观测面运动神经元形态学变化及其死亡情况，免疫组织化学法检测切断伤及压榨伤后半胱氨酸天冬氨酸蛋白酶3和8及cyto-c的表达变化。　　结果与结论：面神经切断伤及压榨伤均可引起面运动神经元死亡，死亡形式以凋亡为主。半胱氨酸天冬氨酸蛋白酶3、8，cyto-c蛋白表达阳性神经元分布于正常面神经核各亚核，切断伤组损伤侧细胞染色重于压榨伤组。损伤后3 d时各蛋白表达开始增强，半胱氨酸天冬氨酸蛋白酶3、8表达于伤后14 d而cyto-c则于伤后7 d时达到高峰。相关性分析结果显示：损伤后半胱氨酸天冬氨酸蛋白酶3、8和cyto-c蛋白表达变化与面神经损伤形式、损伤时间有关，半胱氨酸天冬氨酸蛋白酶8、cyto-c表达与半胱氨酸天冬氨酸蛋白酶3表达相关。提示：半胱氨酸天冬氨酸蛋白酶8，cyto-c可能参与了激活半胱氨酸天冬氨酸蛋白酶3的过程。半胱氨酸天冬氨酸蛋白酶级联反应在面运动神经元凋亡过程中有重要作用。%BACKGROUND:Caspase plays a crucial role in the cellapoptosis, but the influence of different facial nerve injury on caspase 1, caspase 8, cyto-c protein expression and their correlation stil remain unclear. OBJECTIVE:To construct facial nerve crush or distal transection injury models, observe the morphological changes of facial motoneurons, investigate death gene caspase 3, caspase 8, cyto-c expression, and analyze their correlation. METHODS:Facial nerve crush or distal transection injury model was established in the right facial nerve of rats, while the left facial nerve served as normal controls. We observed the morphology and the death of facial motoneurons with toluidine blue staining and transmission electron microscope. Expressions of caspase 3, caspase 8 and cyto-c proteins were studied by immunohistochemistry analysis fol owing facial nerve injury. RESULTS AND CONCLUSION:Both facial nerve distal transection and crush injury resulted in the death of facial motoneurons, and the death pattern was mainly apoptosis. Caspase 3, caspase 8 and cyto-c protein expressions were observed in the subnucleus of normal rat facial nucleus. cells of the distal transection group were stained more intensely than that of crush group. Expressions of these proteins began to increase at 3 days after the injuries. Caspase 3 and caspase 8 protein expression peaked at 14 days, whereas cyto-c protein expression peaked at 7 days after the injuries. Expressions of caspase 3, caspase 8 and cyto-c proteins were correlated with facial nerve injury type and injury time. Expressions of caspase 8 and cyto-c protein were correlated with expression of caspase 3 protein. The findings indicate that, caspase 8 and cyto-c contribute to activate caspase 3, and caspase cascade reaction plays an important role in the apoptosis of facial motoneurons.