Introduction: Exercise training induces the expression of the FNDC5 gene in muscle, producing irisin, which can convert white fat into brown fat, so enhancing metabolic uncoupling and hence caloric expenditure. The aim of this study was to investigate the effect of exercise on the expression of FNDC5 mRNA and miR-665-3p in regulating expression of FNDC5 in gastrocnemius muscle obese male C57BL/6 mice.
Methodology: 18 male mice were obtained from Royan institute at 6 weeks of age with body weight 15-20 g, and randomly divided into two groups: 1) control group fed with standard rodent chow (10% kcal from fat) (n=6) and 2) High Fat Diet (HFD) group fed with a high fat (60% kcal from fat) diet for 12 weeks. After the significant weight difference between the groups, mice were divided to training (obese/Ex) (n=6), sedentary (obese/Sed) (n=6) groups. Training group received exercise on a motor-driven treadmill at 28 m/min (0% grade) for 60 min/day, 5 days/week for 8 weeks. 24 hours after the last exercise session, mice were sacrificed and gastrocnemius muscle was excised and stored at -80° C. For the measurement of gene expression, Real-time PCR method was carried out in this study. All variables were compared by independent t test. Correlation was calculated using the Pearson product moment correlation. P values<0.05 were considered to be significant.
Results: Data revealed that FNDC5 expression was significantly (P<0.05) higher in trained mice when compared with sedentary mice. Also miR-665-3p was significantly (P<0.05) decreased in trained mice. Their expression showed a significant negative correlation.
Discussion: Decreased expression of the miR-665-3p (Regulatory microRNA in FNDC5 expression) followed by endurance training shows that this microRNA has a regulatory role in regulating the expression of FNDC5 mRNA in gastrocnemius muscle of obese male mice.