Department of Rehabilitation Sciences, College of Health Sciences, University of Kentucky, Lexington, Kentucky.
Center for Muscle Biology, University of Kentucky, Lexington, Kentucky.
Am J Physiol Cell Physiol. 2019 Oct 1;317(4):C719-C724. doi: 10.1152/ajpcell.00260.2019. Epub 2019 Jul 17.
It is postulated that testosterone-induced skeletal muscle hypertrophy is driven by myonuclear accretion as the result of satellite cell fusion. To directly test this hypothesis, we utilized the Pax7-DTA mouse model to deplete satellite cells in skeletal muscle followed by testosterone administration. Pax7-DTA mice (6 mo of age) were treated for 5 days with either vehicle [satellite cell replete (SC+)] or tamoxifen [satellite cell depleted (SC-)]. Following a washout period, a testosterone propionate or sham pellet was implanted for 21 days. Testosterone administration caused a significant increase in muscle fiber cross-sectional area in SC+ and SC- mice in both oxidative (soleus) and glycolytic (plantaris and extensor digitorum longus) muscles. In SC+ mice treated with testosterone, there was a significant increase in both satellite cell abundance and myonuclei that was completely absent in testosterone-treated SC- mice. These findings provide direct evidence that testosterone-induced muscle fiber hypertrophy does not require an increase in satellite cell abundance or myonuclear accretion.Listen to a podcast about this Rapid Report with senior author E. E. Dupont-Versteegden (https://ajpcell.podbean.com/e/podcast-on-paper-that-shows-testosterone-induced-skeletal-muscle-hypertrophy-does-not-need-muscle-stem-cells/).
据推测，睾丸激素引起的骨骼肌肥大是由于卫星细胞融合导致肌核积累的结果。为了直接验证这一假说，我们利用 Pax7-DTA 小鼠模型在骨骼肌中耗尽卫星细胞，然后给予睾丸激素处理。Pax7-DTA 小鼠（6 月龄）用载体[卫星细胞再填充（SC+）]或他莫昔芬[卫星细胞耗竭（SC-）]处理 5 天。经过洗脱期后，植入丙酸睾酮或假丸 21 天。睾丸激素处理导致 SC+和 SC-小鼠的氧化（比目鱼肌）和糖酵解（跖肌和趾长伸肌）肌肉中的肌纤维横截面积显著增加。在接受睾丸激素治疗的 SC+小鼠中，卫星细胞丰度和肌核均显著增加，而在接受睾丸激素治疗的 SC-小鼠中则完全不存在。这些发现提供了直接证据，表明睾丸激素诱导的肌纤维肥大不需要增加卫星细胞丰度或肌核积累。
请注意，关于这篇快速报告的播客，资深作者 E.E. Dupont-Versteegden 讲述了其中的内容（https://ajpcell.podbean.com/e/podcast-on-paper-that-shows-testosterone-induced-skeletal-muscle-hypertrophy-does-not-need-muscle-stem-cells/）。
