骨骼肌失神经和再神经化时肌卫星细胞的变化

目的探讨骨骼肌失神经和再神经化时肌卫星细胞的变化规律，了解肌肉相应形态功能变化的细胞学机制。方法取1月龄Wistar大鼠27只制成失神经肌萎缩模型，于术后1～6个月，逐月取3只大鼠双侧小腿三头肌行组织学、组织化学等形态学检测；同时于术后1、2、3周和1～6个月逐月各取1只大鼠双侧小腿三头肌行细胞生物学检查。取1月龄Wistar大鼠35只制成神经再生模型，分别于失神经即时、术后1～6个月逐月取5只大鼠行神经植入手术，动态观察电生理指标变化至植入术后8周，然后进行形态学指标检测。结果骨骼肌失神经组显示肌湿重、肌细胞截面积迅速减少，胶原纤维含量逐渐增加，失神经后3～4个月DNA增殖期核所占百分比最高，后迅速减少，肌卫星细胞失神经3周数量开始明显增加，但2个月后急剧下降，至4个月时含量已极低。神经再生组神经植入后4～5周可引出肌诱发动作电位，以萎缩2～3个月后神经植入再生效果好，此时肌卫星细胞的分化能力较强。结论骨骼肌失神经支配4个月后卫星细胞数量极少导致肌肉进入萎缩的不可逆期；当失神经2～3个月时再神经化，增殖能力活跃的肌卫星细胞促使此时的萎缩肌功能恢复较好。

CHANGES IN MUSCLE SATELLITE CELLS IN DENERVATED AND INNERVATED MUSCLES

Objective To explore the rule of changes in the myoblast stem cells (satellite cells) in the denervated and innervated muscles and to find out the cellular mechanism of the changes in the muscle morphology and function. Methods The denervated muscle-atrophy models were established from 27 Wistar rats aged 1 month. One to six months after operation, examinations of the histology, histochemistry, and morphology were performed on the specimens from the bilateral triceps muscle of the calves of 3 rats in each month. Meanwhile, examination of the cell biology was performed on the specimens from the bilateral triceps muscle of the calves of 1 rat 1, 2 and 3 weeks after operation, and monthly for 1-6 months after operation. The innervation models were established from 35 Wistar rats aged 1 month. Immediately after the denervation, and monthly for 1-6 months after operation, 5 denervated rats underwent the nerve implantation. The changes in the electrophysiological index were observed dynamically until 8 weeks after the nerve implantation. Results After the denervation, the muscle wet weight and the muscle cell area decreased rapidly, but the content of the collagen fibers increased gradually. The number of the nucleus in the period of proliferation was the greatest 3-4 months after the denervation, and then decreased rapidly. The muscle satellite cells began to increase obviously 3 weeks after the denervation, but 2 months later they decreased rapidly and 4 months later the number of the cells was the smallest. Four to five weeks after innervation, the muscle action potential could be induced, and the best innervation effect could be achieved in the implanted nerve after the 2-3 months on denervation, and at this time the differentiation ability of the satellite cells was the strongest. Conclusion Four months after the denervation of the skeletal muscle, an extremely small number of the satellite cells can make the muscle enter the irreversible atrophy. However, when the innervation is performed 2-3 months after the denervation, the actively-growing satellite cells can promote a better functional recovery of the atrophic muscle.