模拟失重大鼠间断性站立或离心对抗骨骼肌萎缩的效果比较

Comparison between intermittent standing and centrifug ation in counteracting muscle atrophy induced by simulated weightlessness in rats

目的 比较模拟失重大鼠间断性站立或离心对抗骨骼肌萎缩的效果。 方法 将雄性SD大鼠按体重随机分为 5组 :即对照组 (CON) ,悬吊 4周组 (SUS) ,SU S+站立 1h/d组 (1G) ,SUS+1.5 G离心 1h/d组 (1.5 G) ,与 SUS+2 .6 G离心 1h/d组 (2 .6 G)。取大鼠左后肢的比目鱼肌 (SOL)、腓肠肌内侧头 (MG)和外侧头 (L G)及趾长伸肌 (EDL) ,称重 ,用组织化学方法及图像分析处理技术对肌纤维横截面积 (CSA)、 型纤维比例及毛细血管数 /肌纤维数比值 (C/F)进行定量分析及比较。 结果 SU S组 4种骨骼肌的湿重均下降 (P<0 .0 5 ) ,SOL 与 MG 、 型肌纤维的 CSA、 型纤维的比例及 C/F比值均降低 (P<0 .0 5 ) ,L G 、 型肌纤维的 CSA与 型纤维的比例降低 (P<0 .0 5 )。站立 1h对减轻模拟失重大鼠 SOL 与 MG萎缩的效果最佳 ,1.5 G或 2 .6 G暴露反而使对抗效果下降。L G的变化与 MG相似。EDL 的萎缩变化最轻 ,对 EDL 的对抗效果随 G值增大而增大。 结论 在本实验条件下 ,站立对预防模拟失重大鼠 SOL 和 MG肌萎缩的效果最佳 ,G值升高 ,其对抗效果反而降低。

Objective The aim of the present study was to com pare the effect of intermittent standing and centrifugation in counteracting muscle atrophy induce d by simulated weightlessness in rats. Methods Male SD rats we re divided randomly into five groups: control (CON),tail-suspended for 4 weeks (SUS),SUS + 1 h/d standing (1 G),SUS + 1 h/d 1.5 G centrifugation (1.5 G) and SUS+1 h/d 2.6 G centrifugation (2.6 G). Hind leg muscles, including soleus (SOL ),medial gastrocnemius (MG),lateral gastrocnemius (LG) and extensor digitorum longus (EDL) were dissected, weighted, sectioned and then stained with the ATPas e staining and the alkaline phosphatase staining, respectively. The cross sectio nal area (CSA) of fiber, the relative proportion of typeⅠfibers and the ratio o f capillary/fiber(C/F)were measured using Leica image analysis system. Results As compared with CON group, the wet weights of the 4 muscles in 4 experimental groups were significantly lower (P<0.05), and the CSA, the relative proportion of type Ⅰfibers and the C/F ratio obviously decreased (P<0.05) in SOL and MG. Among the 3 treatment groups, intermittent standing was the best one in protecting th e SOL and MG from atrophy, in contrary, 2.6 G centrifugation was the worst. Chan ges of LG were similar to that of MG, while changes of EDL were the mildest. Conclusion In our experimental condition, intermittent standi ng 1 h/d is the way of choice in alleviating the atrophy of muscles induced by s imulated weightlessness. The efficacy decreases as the centrifugation G increase s.