Table1_The Effect of Voluntary Physical Activity in an Enriched Environment and Combined Exercise Training on the Satellite Cell Pool in Developing Rats.DOCX

Aim: Postnatal skeletal muscle growth is strongly associated with a satellite cell pool. Early adolescence might be a crucial period when different exercise training interventions have specific consequence on satellite cells. Pax7 and MyoD have been suggested as the leading indicators of satellite cell activation.
Methods: In this study, pre-adolescent male rats (n = 18) were either subjected to an enriched environment that facilitated physical activities or combined training or control for three weeks. The flexor hallucis longus muscle was removed for biochemical and histochemical analysis.
Results: Findings demonstrated that exercise trained rats displayed high levels of serum IGF-1 (p <0.05). There was an increase in Pax7 (p <0.05) and MyoD (p <0.001) mRNA expression. A significant increase in the mean fiber area (p <0.01), satellite cell (p <0.001), and myonuclear numbers (p <0.01) were also observed in both intervention groups. Importantly, enriched rats showed lower corticosterone levels (p <0.05) compared to training ones. Regarding performance, trained and enriched rats had significant improvement in forelimb grip strength (p <0.01) and load-carrying capacity (p <0.05).
Conclusion: Type of physical exercise is an essential part in changing satellite cells pool. Different and frequent physical activities in an enriched environment can be effective for muscle development.

研究目的：产后骨骼肌生长与卫星细胞池（satellite cell pool）密切相关。青春期早期或许是不同运动训练干预对卫星细胞产生特异性影响的关键时期。Pax7与MyoD已被证实是卫星细胞激活的核心标志物。
研究方法：本研究纳入18只青春期前雄性大鼠，将其随机分为促进运动的丰富环境组、联合训练组与对照组，干预周期为3周。随后取大鼠的拇长屈肌（flexor hallucis longus muscle）进行生化与组织化学分析。
研究结果：本研究结果显示，运动训练组大鼠的血清胰岛素样生长因子-1（IGF-1）水平显著升高（p<0.05）；Pax7与MyoD的mRNA表达量均有所上升（Pax7：p<0.05，MyoD：p<0.001）；两个干预组的肌纤维平均横截面积（p<0.01）、卫星细胞数量（p<0.001）以及肌核数目（p<0.01）均出现显著增加。值得注意的是，丰富环境组大鼠的皮质酮水平显著低于联合训练组（p<0.05）。在运动表现方面，训练组与丰富环境组大鼠的前肢握力（p<0.01）与负重能力（p<0.05）均得到显著改善。
研究结论：运动类型是调控卫星细胞池的关键因素。在丰富环境中开展多样化且规律的体育运动，可有效促进骨骼肌发育。