Can Resistance Exercise Alter Irisin Levels and Expression Profiles of FNDC5 and UCP1 in Rats?

BACKGROUND Irisin is a new myokine secreted from the skeletal muscle and appears to affect the metabolism of adipose tissue. OBJECTIVES The mechanisms of cellular and molecular identification by which exercise training exerts its benefits remain unclear and are under investigation. METHODS We examined the effect of 8-week resistance exercise on plasma irisin levels and expression profiles of muscle FNDC5 and subcutaneous adipose tissue UCP1 in male rats. Sixteen adult male rats were divided into two groups, control (n = 8) and exercise training (n = 8) groups. The training group received exercise for 3 days/week on a specific ladder (120 cm height) with a carrying load of 50% of body weight, which was attached to their tails. RESULTS The weight of the load was gradually increased during the training sessions, ultimately reaching 200% of the body weight of rats in the final week. There were three sets of five repetitions with a 3-min rest between each set of exercise sessions and 1 minute between repetitions. Plasma irisin levels and relative mRNA expression of the genes UCP1 and FNDC5 were assessed. The results demonstrated a significant increase in the irisin levels after 8 weeks of resistance exercise (P < 0.001, t = 4.48). The relative expression of FNDC5 (P < 0.001, t = 6.18) and UCP1 genes (P < 0.001, t = 13.91) was also significantly increased. CONCLUSIONS Therefore, we can conclude from this study that resistance exercise may improve body composition possibly through increased thermogenesis in white adipose tissue through the secretion of irisin.