大鼠坐骨神经再生过程中的神经元轴突自噬作用

目的：探讨大鼠坐骨神经变性轴突清除中的自噬作用。方法：横切大鼠坐骨神经制作wallerian变性模型，造模后不同时间点取远断端组织行电镜结构观察和酸性磷酸酶(AcPase)活性检测。结果：坐骨神经横切后轴突发生变性，主要变化为术后第5h～2d轴质肿胀，轴突与髓鞘分离，术后第4d轴质浓缩，轴突与髓鞘完全分离形成游离轴突体。术后初期变性轴突主要形成大小不等的空泡，后期轴突与髓鞘完全分离并形成较大的游离轴突体，轴突体外包一层轴突膜是神经元细胞膜的延续，轴突体轴质浓缩，含大量各级自噬泡和纵横交错的神经丝、微管和微丝。经酸性磷酸酶(AcPase)染色证实自噬泡均呈AcPase阳性，第7d后轴突体被降解吸收，形成的空腔内偶见巨噬细胞。结论：大鼠坐骨神经再生过程中变性轴突的清除主要靠轴突自身的自噬和施万细胞吞噬机制，而巨噬细胞只起辅助作用。

Autophagic role of neuron axon during regeneration of rat sciatic nerves

Objective:To investigate the autophagic role of neuron axon during regeneration of rat sciatic nerves.Methods:Wallerian degeneration model was made by transecting the rat sciatic nerve.Samples from the distal stump were obtained at different time of period post-transaction and ultrathin sections were prepared for examination with electron microscope and acid phosphatase(AcPase)activity.Results:The major changes of the degenerating axon after being transected were the swelling of axoplasm and axon started to separate from myelin sheath from hour 5 to day 2 post-transection.Axoplasm condensed and axon was separated completely from myelin sheath to form dissociative axon body at day 4 post-transection.Vacuoles of different sizes were formed in the axon at early phase after operation and larger dissociative axon bodies were formed when axon was separated completely from myelin sheath at late phase.The axolemma surrounding the axon body was derived from the neuron cytomembrane,the condensed axoplasm contained a lot of autophagic vacuoles at all levels and large number of neurofilaments,microtubules,microfilaments arranged in a crisscross pattern.The autophagic vacuoles exhibited acid phosphatase(AcPase)activities.Axon bodies were absorbed after degradation from day 7 onwards and macrophages were seen by chance in the formative cavity.Conclusion:The degenerating axons were cleared mainly by autophagy mechanism of itself during regeneration of rat sciatic nerve and macrophages only operated assistantly.