Alshuaib W B, Fahim M A
Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191.
Neurobiol Aging. 1990 Sep-Oct;11(5):555-61. doi: 10.1016/0197-4580(90)90117-i.
To determine the effect of endurance exercise on physiological age-related change at the mouse neuromuscular junction (NMJ), synaptic function was studied for extensor digitorum longus (EDL) and soleus muscles of three C57BL/6J mouse groups, 1) young adult control (YC: 10 months), 2) old control (OC: 20 months), and 3) old mice which exercised (OE: 20 months) since young-adulthood. Electrophysiological properties were studied with intracellular recording techniques. Safety margin was studied by measuring indirect isometric twitch tension in different calcium concentrations. With sedentary aging, EDL and soleus quantal contents increased. Following aging combined with 10 months of exercise, the EDL quantal contents in OE and YC animals were similar. In contrast, soleus quantal content was greater in OE than in YC animals. Determined safety margins were OC greater than YC = OE for EDL, and OC = YC = OE for soleus. This is the first study to indicate that physiological age-related changes at NMJs of EDL and soleus muscles are affected differently by endurance exercise. Exercise prevented all physiological age-related changes in EDL NMJs but not in soleus NMJs, this suggests that EDL changes are associated with inactivity during aging, while soleus changes are "fundamental" age changes.
为了确定耐力运动对小鼠神经肌肉接头（NMJ）处与生理年龄相关变化的影响，研究了三个C57BL/6J小鼠组的趾长伸肌（EDL）和比目鱼肌的突触功能，这三组分别为：1）年轻成年对照组（YC：10个月），2）老年对照组（OC：20个月），以及3）成年后开始运动的老年小鼠组（OE：20个月）。采用细胞内记录技术研究电生理特性。通过测量不同钙浓度下的间接等长抽搐张力来研究安全边际。随着久坐不动导致衰老，EDL和比目鱼肌的量子含量增加。在衰老并经过10个月运动后，OE组和YC组动物的EDL量子含量相似。相比之下，OE组比目鱼肌的量子含量高于YC组动物。测定的安全边际显示，EDL的安全边际为OC大于YC = OE，比目鱼肌的安全边际为OC = YC = OE。这是第一项表明耐力运动对EDL和比目鱼肌NMJ处与生理年龄相关变化的影响存在差异的研究。运动阻止了EDL神经肌肉接头处所有与生理年龄相关的变化，但对比目鱼肌神经肌肉接头处没有作用，这表明EDL的变化与衰老过程中的不活动有关，而比目鱼肌的变化是“基本的”年龄变化。
