Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester M1 5GD, UK.
Muscle Nerve. 2011 Feb;43(2):212-22. doi: 10.1002/mus.21822.
If myonuclear loss initiates muscle wasting, it should precede the loss of muscle mass. As aging affects muscle plasticity, the time-course of muscle atrophy during disuse may differ between young and old animals. To investigate this, gastrocnemius muscles of 5- and 25-month-old rats were exposed to 1, 2, or 4 weeks of denervation, whereas the contralateral gastrocnemius muscles served as controls. Muscle fibers of each type responded similarly to 4 weeks of denervation. For both ages most of the atrophy (36%; P < 0.001) occurred in the first 2 weeks. In young-adult muscles, the myonuclear number remained constant, but in old muscles it decreased to below control level after 4 weeks of denervation (P < 0.05). Despite this differential response, myonuclear domain size decreased similarly at both ages (P < 0.001). In both young-adult and old rats, denervation-induced atrophy was not preceded by a loss of myonuclei.
如果肌核丢失引发肌肉减少，那么它应该先于肌肉质量的损失。随着衰老影响肌肉的可塑性，在不用期间肌肉萎缩的时间进程在年轻和老年动物之间可能不同。为了研究这一点，将 5 月龄和 25 月龄大鼠的腓肠肌暴露于去神经支配 1、2 或 4 周，而对侧腓肠肌作为对照。每种类型的肌纤维对 4 周的去神经支配反应相似。对于两个年龄段，大多数萎缩（36%；P < 0.001）发生在最初的 2 周内。在年轻成年肌肉中，肌核数量保持不变，但在老年肌肉中，去神经支配 4 周后降至对照水平以下（P < 0.05）。尽管存在这种差异反应，但在两个年龄段，肌核域大小的减小相似（P < 0.001）。在年轻成年和老年大鼠中，去神经诱导的萎缩并不先于肌核的丢失。
