雷帕霉素增强大鼠脊髓损伤后神经元自噬对凋亡影响的观察

目的探讨雷帕霉素(Rapamycin)对急性脊髓损伤后神经元的保护作用及其可能机制。方法 150只SD大鼠按随机分成假手术组、损伤组和治疗组,Allen法1]建立大鼠脊髓损伤模型,于损伤后8h、24h、3d、7d、14d取损伤脊髓组织,免疫荧光双标观察神经元LC3表达及凋亡情况,Western blot检测LC3及Caspase-3表达,电镜观察神经元显微结构变化。结果与损伤组相比,治疗组相同时相点LC3阳性神经元增多,凋亡细胞减少(P<0.05);Western blot示LC3Ⅱ损伤后第3天达高峰,治疗组表达较明显,Caspase-3损伤第7天后开始下降,治疗组表达较少(P<0.05);电子显微镜下损伤组及治疗组神经元内均可见自噬小体及自噬溶酶体。结论雷帕霉素增强大鼠脊髓损伤后神经元自噬,减少神经元细胞凋亡,对神经元具有保护作用。

Effects of rapamycin on apoptosis with enhancing neuronal autophagy after spinal cord injury in rats

Objective To explore the protective effect and possible mechanism of rapamycin to the neuronal after spinal cord injury （SCI） in rats. Methods A total of 150 SD rats were randomly divided into three groups, that is, the sham opera tion group, the injury group and the rapamycin treatment group. The SCI model was injured by using the Allen weight dropping technique. The rats were sacrificed and the spinal cord was taken out on five different time-point （8 h, 24 h, 3 d, 7 d and 14 d）. Immunofluorescent double-labeling was done in order to observe the LC3 expression and apoptosis of neurons. We used western blot to analyze the LC3 and Caspase-3 expression. Transmission electronic microscope was used to examine the anatomic formation of autophagy. Results Comparing with injury group, the number of autophagy positive neurons was obviously en haneed in the rapamycin treatment group on the same time-point. The number of apoptosis positive neurons of injury group was higher than rapamycin treatment＇s. We detected significantly elevated level of LC~ 8 h after SCI, and 3 d in the peak. Rapamy- cin evidently increased LC3 expression. We also detected elevated level of Caspase-3 8 h after SCI, and declined until 7 d after SCI. Rapamycin decreased Caspase-3 expression. The existence of antophagosomes and autolysosomes were confirmed in both injury group and rapamycin treatment group. Conclusion Rapamyein promotes neuronal autophagy and decreases neuronal apoptosis, and Rapamycin is protective to neurons.