Kanda K, Hashizume K
Department of Central Nervous System, Tokyo Metropolitan Institute of Gerontology, Japan.
Neurosci Res. 1998 May;31(1):69-75. doi: 10.1016/s0168-0102(98)00026-1.
We examined the number and size of motoneurons and myelinated nerve fibers innervating the medial gastrocnemius (MG) muscle in the hindlimb of rats that were subjected to swimming for 10 months (30 min, 3 days/week) from 17 to 27 months of age. The number of MG motoneurons in exercised aged rats was slightly, but not significantly, greater than that in sedentary aged rats, and the number for both aged groups was significantly less compared to that in middle-aged (17-month-old) rats. The size of motoneuronal somata in the exercised aged rats was significantly larger than that in sedentary aged rats. Morphological parameters (fascicular area, fiber density, and axonal diameter) for the MG nerve in the exercised rats showed intermediate values between those for middle-aged and sedentary aged rats, although all of the differences in the means between groups were not significant. Thus, the overall changes seen in the exercised rats seem less compared to the changes in the sedentary rats, suggesting that long-term moderate exercise retards the progressive changes in motoneurons and peripheral nerves that develop in old age.
我们研究了17至27月龄大鼠后肢中支配腓肠肌内侧（MG）的运动神经元和有髓神经纤维的数量及大小。这些大鼠从17月龄至27月龄进行了为期10个月的游泳训练（每周3天，每次30分钟）。运动老龄大鼠的MG运动神经元数量略高于久坐老龄大鼠，但差异不显著，且两个老龄组的运动神经元数量均显著少于中年（17月龄）大鼠。运动老龄大鼠的运动神经元胞体大小显著大于久坐老龄大鼠。运动大鼠MG神经的形态学参数（束面积、纤维密度和轴突直径）介于中年大鼠和久坐老龄大鼠之间，尽管组间均值的所有差异均不显著。因此，与久坐大鼠的变化相比，运动大鼠的总体变化似乎较小，这表明长期适度运动可延缓老年期运动神经元和周围神经的渐进性变化。
