[大鼠臂丛神经损伤诱导的萎缩性骨骼肌中的细胞凋亡]

Department of Pathophysiology, Shanghai Medical University, Shanghai 200032, China.

Zhonghua Yi Xue Za Zhi. 2000 Jul;80(7):530-3.

OBJECTIVE

To study the role of apoptosis and the expression of apoptosis-associated genes in skeletal muscle atrophy induced by brachial plexus injury in rats.

METHODS

Rat models of skeletal muscle atrophy were established by cutting off brachial plexus of one upper limb. Apoptosis of muscular cells was investigated by TUNEL, flowcytometry, DNA electrophoresis and electromicroscopic observation. The apoptosis associated genes such as Fas, FADD, Caspase 8, c-myc, P53 and Bcl-2 were detected by immunohistochemical method (ABC) and Northern-blot.

RESULTS

It was found with TUNEL and flowcytometry that the percentage of apoptotic muscle cell rose obviously in atrophic skeletal muscle (P < 0.05). DNA laddering could be seen in DNA gel electrophoresis of atrophic muscle after brachial injury. Morphologic changes of early stage in apoptotic cell could be seen under eletcromicroscope, such as the aggregation of chromosome, the expansion of nucleic cistern and the contraction of nucleus. Fas, FADD and Caspase genes were expressed highly and Bcl-2 gene was expressed lowly with immunohistochemical method in atrophic muscle. The results were all significantly different with that of the controls (P < 0.01). But the expression changes in P53 and c-myc genes were not obvious. The result of Northern-blot indicated that the mRNA of Fas gene rose and that of Bcl-2 gene decreased obviously (P < 0.01) in atrophic muscle induced by brachial plexus injury.

CONCLUSION

There are much more apoptotic cells in atrophic muscle induced by brachial plexus injury, and apoptosis plays an important role in its pathogenesis. The apoptotic signal maybe transmitted through Fas-->FADD-->Caspase 8, and the decrease in Bcl-2 gene expression aggravates the process.

目的

研究凋亡及凋亡相关基因表达在大鼠臂丛神经损伤所致骨骼肌萎缩中的作用。

方法

切断大鼠一侧上肢臂丛神经建立骨骼肌萎缩模型。采用TUNEL法、流式细胞术、DNA电泳及电镜观察等方法研究肌细胞凋亡情况。采用免疫组织化学方法（ABC法）及Northern杂交检测Fas、FADD、Caspase 8、c-myc、P53及Bcl-2等凋亡相关基因。

结果

TUNEL法及流式细胞术检测发现，萎缩骨骼肌中凋亡肌细胞百分比明显升高（P<0.05）。臂丛神经损伤后萎缩肌肉的DNA凝胶电泳可见DNA梯状条带。电镜下可见凋亡细胞早期形态学改变，如染色质聚集、核周池扩张及核固缩等。免疫组织化学方法检测发现，萎缩肌肉中Fas、FADD及Caspase基因高表达，Bcl-2基因低表达。与对照组相比，差异均有统计学意义（P<0.01）。但P53及c-myc基因表达变化不明显。Northern杂交结果显示，臂丛神经损伤所致萎缩肌肉中Fas基因mRNA明显升高，Bcl-2基因mRNA明显降低（P<0.01）。