周围神经损伤修复后早期骨骼肌细胞凋亡的初步研究

A preliminary study of apoptosis in skeletal muscles at the early stage of peripheral never regeneration in rats

目的探讨神经修复后早期大鼠骨骼肌的细胞凋亡情况。方法取SD大鼠54只，随机分为3组：失神经组（A组）18只，神经缝合组（B组）18只，健康对照组（C组）18只。A组大鼠切除左侧1cm长坐骨神经，B组大鼠横断左侧坐骨神经后立即用10-0医用尼龙线行外膜缝合，C组大鼠不做任何处理。以腓肠肌肌湿重作为骨骼肌萎缩指标。分别应用脱氧核糖核苷酸末端转移酶介导的缺口末端标记法（rnINEI．）和分光光度法检测术后2d、14d、28d时骨骼肌凋亡细胞核和天冬氨酸特异性半胱氨酸蛋白酶（Caspase）-3与Caspase-8活性。结果神经缝合后早期骨骼肌与正常骨骼肌比较，细胞凋亡现象增加，凋亡相关蛋白Caspase-3和Caspase-8活性上升，但程度弱于失神经骨骼肌。结论细胞凋亡可能是神经修复后早期骨骼肌萎缩原因之一，死亡受体信号通路参与神经修复后早期骨骼肌凋亡过程中。

Objective To explore skeletal muscle apeptosis at the early stage of peripheral never regeneration in rats. Methods A total of 54 male SD rats were randoraly assigned to 3 groups （n = 18/ group）： denervation group （A）, neurerrhaphy group （B）, normal control group （C）. In group A, a 1 cm segment of the left sciatic nerve was removed. In group B, the left sciatic nerve was transected above the bifurcation and immediately repaired with 10-0 sutures. No surgery was done in group C. The gastrnenemius muscle wet weight served as an indicator of the degree of musch atrophy. Marker of apeptosis, nuclear DNA fragmemation, was detected using terminal decxyribonuclectidyl tramfemse mediated dUTP nick end labeling （the TUNEL method） and observed under eonfocal microscopy at 2, 14 and 28 days postoperatively. Another pert.ion of the gastrecnemius muscle was homogenized to analyze the activity of caspase-3 and-8 by spectrophotometry. Results TUNEL labaling of fragmented DNA on hlstologieal sections in the neuorrhaphy group revealed levels of apeptotie nuclei higher than the control group and lower than the denervation group at the early stage （ 〈 28 days）. The activity of easpase-3 and -8 in the neuorrhaphy group was also higher than the control group but lower than the denervation group. Conclusion At the initial stage of peripheral never regeneration, apeptosls may contribute to muscle atrophy and extrinsic apoptotic pathways may take part in it.