Department of Neurology, Ohio State University, Columbus, OH, USA.
Department of Neurology, Ohio State University, Columbus, OH, USA; Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA.
Neurobiol Aging. 2018 Jul;67:128-136. doi: 10.1016/j.neurobiolaging.2018.03.016. Epub 2018 Mar 23.
In older adults, the loss of muscle strength (dynapenia) and the loss of muscle mass (sarcopenia) are important contributors to the loss of physical function. We sought to investigate dynapenia, sarcopenia, and the loss of motor unit function in aging mice. C57BL/6J mice were analyzed with cross-sectional (males: 3 vs. 27 months; males and females: 8 vs. 12 vs. 20 months) and longitudinal studies (males: 10-25 months) using in vivo electrophysiological measures of motor unit connectivity (triceps surae compound muscle action potential and motor unit number estimation), in vivo measures of plantar flexion torque, magnetic resonance imaging of hind limb muscle volume, and grip strength. Compound muscle action potential amplitude, motor unit number estimation, and plantar flexion torque were decreased at 20 months. In contrast, grip strength was reduced at 24 months. Motor unit number estimates correlated with muscle torque and hind limb muscle volume. Our results demonstrate that the loss of motor unit connectivity is an early finding in aging male and female mice and that muscle size and contractility are both associated with motor unit number.
在老年人中，肌肉力量的丧失（动力不足）和肌肉质量的丧失（肌肉减少症）是身体功能丧失的重要原因。我们试图研究衰老小鼠中的动力不足、肌肉减少症和运动单位功能丧失。使用活体电生理测量（三腿肌复合肌肉动作电位和运动单位数量估计）、活体跖屈扭矩测量、后肢肌肉体积磁共振成像和握力对 C57BL/6J 小鼠进行了横断面（雄性：3 与 27 个月；雄性和雌性：8 与 12 与 20 个月）和纵向研究（雄性：10-25 个月）。复合肌肉动作电位幅度、运动单位数量估计和跖屈扭矩在 20 个月时降低。相比之下，握力在 24 个月时降低。运动单位数量估计与肌肉扭矩和后肢肌肉体积相关。我们的结果表明，运动单位连接的丧失是雄性和雌性衰老小鼠的早期发现，并且肌肉大小和收缩性都与运动单位数量相关。
