大鼠尺神经损伤平面和修复时间对爪内肌细胞凋亡的影响

Apoptosis and uitrastructure changes in claw muscles of rats at different injury level and restoration time of ulnar nerve

目的研究尺神经损伤修复后靶肌功能恢复的影响因素。方法42只SD雄性大鼠分为肘部、腕部2组实验组和1组正常对照组;实验组在肘部和腕部完全离断两前肢尺神经后即刻、1个月、3个月修复一侧神经(另一侧为对照侧),应用免疫组织化学染色和电镜技术,观察和比较大鼠爪内肌细胞凋亡及细胞超微结构变化。结果即刻修复组大鼠爪内肌促细胞凋亡基因Fas、Caspase-3表达与正常组之间的差异无统计学意义;随修复时间延长,其表达逐渐增高,且组间有显著性差异(P<0.05)。抑细胞凋亡基因Bcl-2蛋白表达随修复时间延长而逐渐降低。伤后即刻、1月组实验侧Fas和Caspase-3蛋白表达较相应对照侧低(P<0.05);而3月组实验侧与相应对照侧比较无明显差异(P>0.05);相同修复时间,不同损伤平面组间表达差异均无统计学意义。结论靶肌超微结构改变及细胞凋亡的发生与神经损伤后修复时间有密切关系,与损伤平面关系较小。在法医学鉴定时机认定方面,尚需进一步研究验证。

Objective To study the factors influencing the uhrastructure and apoptosis frequency on target muscle when the ulnar nerve was cut off by different injury level （IL） and repaired at different restoration time （RT）. Methods 42 SD rats were randomly divided into 3 groups, including 2 experimental groups with IL at wrist and elbow separately and 1 normal control group. The ulnar nerves of two front limbs were cut at elbow level or wrist level and the nerve of one side was repaired at different time （immediately, 1 month later and 3 months later）, while the other side was treated unrepaired as matching control. 3he apoptosis-related proteins, including Fas, -3 and Bcl-2, were detected by inrnunohistochemistry assay and the uhrastructural changes of claw muscle were observed by electron-microscope. Results The expression of pro-apoptosis protein Fas and Caspase-3 was not significantly different between the immediately repaired group and the normal control group. Increased expression of pro-apoptosis protein was detected in 1 month group and 3 months group, which both showed significant difference with normal control group （P 〈0.05）. Decreased expression of Bcl-2 was also observed as the RT prolonged in experimental groups. Compared with the unrepaired limbs of the experimental groups, the expression of protein Fas and Caspase-3 in the repaired immediately and 1 month later groups was lower （ P 〈 0. 05 ） , while it showed no obvious difference in 3 months group （ P 〉 0.05 ）. The expression of all the three proteins was not significantly different between each matching pair with the same RT but different IL. Conclusion The ultrastructural changes and apoptosis frequency of target muscles were greatly dependent on the restoration time after injury while the level of injury was not considered as significant. It may provide new insights for expertises in clinical forensic to identify the exact time of peripheral nerve injury. However the application needs further clinical researches on human.