Abstract Aim: Nicotinic acetylcholine receptors (nAChRs) are integral membrane proteins and prototypic members of the ligand-gated ion-channel super-family. The Purpose of the present study was to investigate the effect of endurance, resistance and concurrent training on the content of nAChR in fast skeletal muscles of male Wistar rats.

Method: Thirty male Wistar rats (220±15 gr) randomly were divided to four groups and followed 12 weeks of training according to the protocols. Animals of the endurance training group were exercised on treadmill for 12 weeks, 5 times a week, and 60 minutes a day at velocities up to 30 m/min. Animals of the Resistance group were housed in metal cage with a 2m high wire-mesh tower, with water bottles set at the top. Concurrent training group did both resistance and endurance trainings. Forty-eight hours after last session of protocols, animals were anaesthetized and the tibialis anterior (AT) was removed. For nAChR assay and for data analysis, ANOVA and independent- samples t- test were used.

Results: Data analysis showed that fast muscle nAChR content significantly difference between endurance, resistance and concurrent training groups with control group (P<0.01).

Conclusion: content of nAChR increased in the fast muscle by endurance, resistance and concurrent training protocols. It seems that these training protocols might lead to the remodeling of NMJ, part of which could be the increase in the content of nAChR probably through the role of neurotrophic factors, such as CGRP, which has been shown to contribute in the synthesis and clustering of nAChR.

Key words: Endurance training, Resistance training, Concurrent training, Nicotinic acetylcholine receptors, Fast muscle