慢性低频电刺激对模拟失重后肌萎缩及肌梭传入放电的影响

目的　观察在吊尾的不同时期 (3、7、14d)及吊尾加慢性低频电刺激 (CLFS) 14d后比目鱼肌肌梭的传入放电有何改变。方法　采用电生理技术 ,在大鼠脊髓背根分离神经细束 ,记录吊尾不同时期比目鱼肌在动静式(ramp and hold)牵拉过程中肌梭的传入放电 ,以及吊尾加CLFS 14d后肌梭传入放电的变化。结果　①模拟失重14d后 ,比目鱼肌发生明显的萎缩 ,比目鱼肌湿重体重比由吊尾前的 38.8(mg·10 0 g- 1 )降低到 2 3.1,而吊尾加CLFS 14d后比目鱼肌湿重体重比仅下降到 32 .5 ,表明CLFS可有效的防止模拟失重所造成的肌萎缩。②模拟失重 14d后 ,比目鱼肌肌梭的传入放电比正常对照组明显减少 ,而吊尾加CLFS 14d后 ,肌梭传入放电的各项指标均有不同程度的升高 ,与单纯吊尾组相比 ,有显著性差异 (P <0 .0 5 )。结论　本研究结果提示模拟失重可引起肌肉萎缩及肌梭的传入放电减少 ,而慢性低频电刺激可以部分地对抗这些变化。

The effects of chronic low frequency stimulation on muscle atrophy and the discharges of muscle spindle after tail-suspension

Objective To investigate the effects of different time periods of tail suspension and chronic low frequency stimulation (CLFS) on discharges of muscle spindle and muscle atrophy. Methods Discharges from single units were recorded electrophysiologically from the centrally cut filaments of the dorsal roots innervating muscle spindles of the soleus muscle and its responses were observed during ramp and hold stretch. Results ①After 14 days of tail suspension, the ratio of wet weight of soleus muscle to body weight dropped from 38.8 to 23.1. The CLFS was administered at the same time as 14 days' tail suspension. However, the ratio of wet weight of soleus muscle to body weight only decreased to 32.5. ②The discharges of muscle spindle decreased after 14 days' tail suspension. While after 14 days of tail suspension with CLFS, the unit activity increased as compared with 14 days of simple tail suspension. Conclusion The results indicate that tail suspension produces muscle atrophy and decreases discharges of muscle spindle, and both changes can be prevented by CLFS.