减重平板步行训练对脊髓横断大鼠骨骼肌细胞凋亡与萎缩的影响

The effect of spinal cord transection and body-weight-supported treadmill training on cell apoptosis and atrophy of rat soleus muscle

目的研究细胞凋亡是否参与脊髓损伤引起的骨骼肌萎缩过程，观察减重平板步行训练对骨骼肌萎缩及超微结构的影响。方法将70只雌性Wistar大鼠随机分为对照组与脊髓横断7d组（简称横断7d组）、横断15d组、横断30d组以及脊髓横断5d训练2d组（简称训练2d组）、训练10d组、训练25d组。对照组未给予特殊处理，余6组行T8-10水平脊髓完全横断，各训练组大鼠于脊髓横断5d后进行减重平板步行训练。采用TUNEL方法检测比目鱼肌肌细胞凋亡情况，采用透射电镜观察肌纤维超微结构变化。结果实验大鼠脊髓横断后，其比目鱼肌TUNEL阳性细胞核数量较对照组及相应时间点训练组均明显增多（P〈0．05～0．001）；电镜观察发现，随着脊髓横断时间延长，萎缩肌纤维数量逐渐增多，肌节与肌丝排列紊乱加重，细胞核形态不规则，毛细血管管腔狭窄；经减重平板步行训练后上述改变有所改善。结论细胞凋亡参与脊髓损伤后引发的骨骼肌萎缩过程；减重平板步行训练能够抑制肌细胞凋亡、缓解肌萎缩，改善肌肉血供。

Objective To study whether cell apoptosis is involved in the process of skeletal muscle atrophy, and observe the effect of body-weight-supported treadmill training （BWSTT） on skeletal muscle ultramicrostructure after spinal cord transection （ ST）. Methods A total of 70 healthy adult female Wistar rats were divided randomly into 7 groups： a control group, a spinal transection （ST） group consisted of 3 subgroups observing for 7, 15, 30 days, respectively, and a training group subdividing into 3 subgroups observing for 2, 10, 25 days starting from 5 days after spinal transection. The rats in the control group did not undergo surgery,while those in the other groups underwent a complete spinal transection at the thoracic level （T8 -T10 ）. Five days after the ST, BWSTT was employed to treat the rats in the training group. TUNEL technique was used to measure the myonuclear apoptosis of soleus, and transmission electron microscope was used to observe muscle fiber ultramicrostructure. Results The number of TUNEL-positive cell nuclear increased significantly in ST groups as compared with that in the control group and that in the corresponding time points of training group （ P 〈 0.05 - 0. 001 ）. The number of atrophied fibers increased, sarcomeres and myofilaments deranged gradually with the prolonged time after ST, the morphology of myonuclear was irregular, the capillary lumina was narrower than control group. These phenomena were ameliorated after BWSTT. Conclusion The results showed that cell apoptosis contributed to skeletal muscle atrophy. BWSTT could attenuate cell apoptosis, muscle atrophy, and improve blood-supply of muscle.