Effects of Concurrent and Resistance Training on Calcitonin Gene-Related Peptide (CGRP) Content in Slow and Fast Muscles of Adult Wistar Rats

Calcitonin Gene-Related Peptide (CGRP), a 37-amino acid peptide, is broadly distributed in the peripheral and central nervous systems of vertebrate and invertebrate species. The purpose of the present study was to investigation the effects of Concurrent (Resistance and Endurance) and Resistance Training on the content of CGRP in Slow and Fast Muscles of Adult Wistar Rats. Twenty -three male Wistar rats (10 mo of age, 220 ± 15 gr, Iran Pasteur Institute) were randomly divided in to three groups (control (n=7), concurrent training (n=8), and resistance training (n=8)). They completed 12 weeks of training according to protocols. Animals of the resistance group were placed in metal cage with a wire-mesh tower, with two water bottles set at the top. Concurrent group completed a combination of both resistance and endurance trainings (5 days a week, 60 min/day, 30 m/min speed). Forty-eight hours after the last session of protocols, animals were anaesthetized. The right Soleus (as slow muscle) and Anterior Tibialis (as fast muscle) were removed under sterile condition via an incision on dorsolateral of the hindlimb. The tissues were removed quickly and freezed in liquid Nitrogen and were kept at -70 ° C for later usage. For CGRP assay, ELISA kit was used. One-way ANOVA was used to analyze the data. There was a significant difference between the control and concurrent training groups in slow muscle CGRP content. Moreover, the content of CGRP in both fast and slow muscles was significantly different when resistance training group was compared with the control group. Both resistance and concurrent training increased the content of CGRP in the fast and slow muscles. Therefore, CGRP increase depends on the nature of activity and probably its duration and intensity, more than muscle type.The results should be considered, in the role of CGRP in NMJ remodeling.