Effects of exercise during growth on the expresslon of myostatin in muscle

生长过程中运动对肌肉肌生长抑制素表达的影响

基本信息

批准号：
14380012
负责人：
ISHII Naokata
金额：
$ 2.75万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Exercise stimulus during growth is likely important not only for the development of various physiological functions but also for maintaining these functions throughout the later stages of life. Myostatin, a growth factor that strongly suppresses the proliferation of muscle satellite cells, decreases during growth and also as the muscle is mechanically loaded, so that it may play a part in normal development of muscle. The present study investigated the effects of either exercise or mechanical unloading during early stage of growth on the content of myostatin and the number of satellite cells within muscles during the later stages of growth. Mice (3-wk age) were assigned into control, uphill-run exercise, downhill-run exercise and unloaded groups, and subjected to either treadmill running or hindlimb suspension for 2 wk, thereafter returned to the normal in-cage activity. In all groups, the content of myostatin in gastrocnemius (GA) and soleus (SOL) muscles decreased at 5-8 wk without significant difference between groups. However, the number of satellite cells per muscle fiber was significantly smaller in unloaded group and larger in exercise groups than in control group. In unloaded group, wet weight of both muscles markedly decreased after the hindlimb suspension. Although the muscle weight was recovered at 12 wk, the number of muscle fibers was significantly smaller than in other three groups. Thus in the second part of study, the mice were hindlimb-suspended at 3-5 wk, returned to normal activity until 12 wk, and then trained with uphill running for 2wk. In both GA and SOL, however, no significant differences in muscle weight were seen between hindlimb-suspended and control groups. The results suggest that the mechanical unloading during the early stage of growth persistently impairs the normal development of muscle, but does not strongly affect the adaptability of muscle to relatively low-intensity exercise in adult.

生长过程中的运动刺激不仅对于发展各种生理功能，而且对于在生命的后期阶段保持这些功能也可能很重要。 Myostatin是一种强烈抑制肌肉卫星细胞增殖的生长因子，在生长过程中降低，并且随着肌肉的机械载荷也可以减少，因此它可以在肌肉正常发育中起作用。本研究调查了生长早期阶段运动或机械卸载对肌生抑素含量以及在生长后期肌肉中肌肉中卫星细胞数量的影响。将小鼠（3周龄）分配到控制，上坡运行的运动，下坡运动和卸载的组中，并在2周进行跑步机或后肢悬架，此后恢复到正常的盖子内活动。在所有组中，胃肌抑素（GA）和比目鱼（Sol）肌肉在5-8周降低的肌酸含量降低，而两组之间没有显着差异。但是，在未载的组中，每个肌肉纤维的卫星细胞数量明显小，运动组中的卫星细胞数量要比对照组中的卫星细胞数量要小。在卸载的群体中，后肢悬浮后两种肌肉的湿重都显着减少。尽管在12周时恢复了肌肉重量，但肌肉纤维的数量明显小于其他三组。因此，在研究的第二部分中，将小鼠在3-5周后悬浮在后肢悬浮，恢复了正常的活动，直到12周，然后接受了2WK的上坡训练。但是，在GA和SOL中，后肢悬浮和对照组之间均未看到肌肉体重的显着差异。结果表明，生长的早期阶段的机械卸载会持续损害肌肉的正常发育，但不会强烈影响肌肉对成人相对较低强度运动的适应性。