Beneficial effects of exercise on the prevention and treatment of life-style relateddisease are well known, affecting physiologically active molecules such as ghrelin.Because long-term effects of exercise on ghrelin dynamics are to be elucidated in relation to the formation of obesity, we investigated effects of spontaneous exercise on these parameters in high-fat diet (HFD) induced obese rats.
　Male Sprague Dawley rats at 4 weeks-old were fed either control diet (CD; 10 kcal% fat) or HFD (60 kcal% fat) for 12 weeks. They were further subdivided into 4 groups according to the performance of spontaneous exercise (in the chamber equipped with running-wheel for 3 days, biweekly) or not. In results, CD without exercise (CD-S), CD with exercise (CD-Ex), HFD without exercise (HFD-Ex) and HFD-with exercise (HFD-Ex) were compared at 16 week-old.
　Although body weight and visceral fat were significantly higher in HFD-S than CD-S, the induction of spontaneous exercise to HFD rats restored these parameters equivalent to the level of CD-Ex. Abnormal rhythms of activity and feeding were observed in HFD-S, which had been normalized by spontaneous exercise. Furthermore, spontaneous exercise restored plasma and stomach ghrelin concentrations and ghrelin production which had been significantly reduced in HFD-S.
　It is shown that spontaneous exercise has an effect to suppress the formation of HFD-induced obesity, normalizing activity and feeding rhythms and restoring ghrelin synthesis.

DESCENTE SPORTS SCIENCE Vol.36/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE