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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.

生长期间的运动刺激可能不仅对各种生理功能的发展很重要，而且对在生命的后期维持这些功能也很重要。肌生长抑制素是一种强烈抑制肌肉卫星细胞增殖的生长因子，在生长过程中以及肌肉受到机械负荷时减少，因此它可能在肌肉的正常发育中发挥作用。本研究探讨了生长早期运动和机械去负荷对生长后期肌肉中肌生成抑制素含量和卫星细胞数量的影响。将3周龄的小鼠分为对照组、上坡跑运动组、下坡跑运动组和无负荷组，分别进行跑台运动或后肢悬吊2周，然后恢复正常笼内活动。各组大鼠腓肠肌和比目鱼肌肌生长抑制素含量在5-8周时均下降，但组间差异无统计学意义。然而，每个肌纤维的卫星细胞数量在无负荷组中显著小于对照组，而在运动组中显著大于对照组。无负荷组，后肢悬吊后两侧肌肉湿重均明显下降。12 wk时肌重虽有所恢复，但肌纤维数明显少于其他3组。因此，在研究的第二部分中，小鼠在3-5 wk后肢悬吊，直到12 wk恢复正常活动，然后进行2 wk的上坡跑训练。然而，在GA和SOL中，后肢悬吊组和对照组之间的肌肉重量没有显著差异。结果表明，生长早期的机械性去负荷持续损害肌肉的正常发育，但对成年后肌肉对相对低强度运动的适应性影响不大。