The effect of 14 weeks of endurance training with two different Intensity on serum irisin level, gene expression of skeletal muscle PGC1-α and FNDC5 and subcutaneous adipose tissue UCP1 in obese rats

Irisin is a new myokine that has a beneficial effects of exercise on energy metabolism. However, irisin response to different intensities of endurance training is not completely understood. In the current experimental study, 18 male Wistar rats were fed a high-fat diet and 6 rats were nourished a standard diet for 12 weeks. After 12 weeks, obese rats were randomly divided into 3 groups: high-intensity training (34 m/min ~85% VO2max), moderate-intensity training (28 m/min ~70% VO2max) and control. Exercise groups trained 5 days/week for 12 weeks on a rodent treadmill. Serum irisin level and gene expression changes were measured using ELISA and Real Time-PCR method, respectively. In high and moderate-intensity endurance training expression of PGC1-α (P=0.001 and P=0.001), FNDC5 (P=0.013 and P=0.049) and UCP1 (P=0.001 and P=0.001) were significantly more than the control group. Serum irisin level only after high-intensity training was more than the control group (P=0.014). A positive correlation was observed between serum irisin and UCP1 in both of high (P=0.017) and moderate-intensity (P=0.046) training groups. High-intensity endurance training has a positive effect on the level of serum irisin. Also, there is a positive correlation between irisin and UCP1 gene expression in subcutaneous adipose tissue. However, irisin isn’t the only factor affecting on exercise-induced UCP1 gene expression.