Homonko D A, Theriault E
The Toronto Hospital Research Institute, Toronto Western Division, Toronto, Ontario, Canada M5T 2S8.
J Appl Physiol (1985). 2000 Nov;89(5):1928-36. doi: 10.1152/jappl.2000.89.5.1928.
Calcitonin gene-related peptide (CGRP) is present in some spinal cord motoneurons and at neuromuscular junctions in skeletal muscle. We previously reported increased numbers of CGRP-positive (CGRP+) motoneurons supplying hindlimb extensors after downhill exercise (Homonko DA and Theriault E, Inter J Sport Med 18: 1-7, 1997). The present study identifies the responding population with respect to muscle and motoneuron pool and correlates changes in CGRP with muscle fiber type-identified end plates. Twenty seven rats were divided into the following groups: control and 72 h and 2 wk postexercise. FluoroGold was injected into the soleus, lateral gastrocnemius, and the proximal (mixed fiber type) or distal (fast-twitch glycolytic) regions of the medial gastrocnemius (MG). Untrained animals ran downhill on a treadmill for 30 min. The number of FluoroGold/CGRP+ motoneurons within proximal and distal MG increased by 72 h postexercise (P<0.05). No significant changes were observed in soleus or lateral gastrocnemius motoneurons postexercise. The number of alpha-bungarotoxin/CGRP+ motor end plates in the MG increased exclusively at fast-twitch glycolytic muscle fibers 72 h and 2 wk postexercise (P<0.05). One interpretation of these results is that unaccustomed exercise preferentially activates fast-twitch glycolytic muscle fibers in the MG.
降钙素基因相关肽（CGRP）存在于一些脊髓运动神经元和骨骼肌的神经肌肉接头处。我们之前报道过，下坡运动后，供应后肢伸肌的CGRP阳性（CGRP+）运动神经元数量增加（Homonko DA和Theriault E，《国际运动医学杂志》18: 1 - 7，1997）。本研究确定了对运动做出反应的肌肉和运动神经元池，并将CGRP的变化与通过肌肉纤维类型确定的终板相关联。27只大鼠被分为以下几组：对照组、运动后72小时组和运动后2周组。将荧光金注射到比目鱼肌、外侧腓肠肌以及内侧腓肠肌（MG）的近端（混合纤维类型）或远端（快缩糖酵解型）区域。未训练的动物在跑步机上进行30分钟的下坡跑。运动后72小时，近端和远端MG内的荧光金/CGRP+运动神经元数量增加（P<0.05）。运动后比目鱼肌或外侧腓肠肌运动神经元未观察到显著变化。运动后72小时和2周，MG中α - 银环蛇毒素/CGRP+运动终板的数量仅在快缩糖酵解型肌纤维处增加（P<0.05）。这些结果的一种解释是，不习惯的运动会优先激活MG中的快缩糖酵解型肌纤维。
