Exercise-Induced Circulating Irisin Level Is Correlated with Improved Cardiac Function in Rats

Irisin, a recently identified myokine, plays an important physiological role in modulating energy homeostasis. However, the role of irisin in cardiac function during exercise has not been evaluated. In this study, we investigated the effect of exercise on irisin, pro-inflammatory cytokines, and cardiac function during 12 weeks of exercise in rats. Eight-week-old Sprague-Dawley male rats were randomly divided into two groups (n = 9 per group): sedentary control (CON) and exercise (EXE) groups. The EXE group was trained on a motorized treadmill at 20 m/min, for 60 min/day, five times/week for 12 weeks. The EXE group showed a decrease in abdominal visceral fat (p < 0.05), epididymal fat (p < 0.01), and total cholesterol (TC) (p < 0.05) and an increase in irisin levels (p < 0.01). Irisin negatively correlated with abdominal visceral (p < 0.05) and epididymal fat (p < 0.05) and positively correlated with the ejection fraction (p < 0.05), fractional shortening (p < 0.05), and cardiac output (p < 0.05). In conclusion, exercise decreases the abdominal visceral and epididymal fat and TC levels, possibly caused by elevated irisin levels, thus improving the cardiac function. This suggests that exercise-induced circulating irisin levels correlate with improved cardiac function in rats.