Acute effects of exercise on circulating leptin in lean and genetically obese fa/fa rats

Mechanisms of regulation of plasma leptin in lean and genetically obese ani mals are not completely understood. In particular a relation has been propo sed between energy metabolism and leptin. However, it is not clear how ener gy expenditure and leptin are related under exercise in lean and obese anim als. To clarify these aspects we investigated lean and genetically obese (f a/fa) Zucker rats undergoing a single bout (30 min) of swimming and measure d several biochemical and hormonal parameters of energy metabolism and lept in changes throughout the study. Moreover ob-gene expression in adipose tis sue was also measured. Our results showed that plasma leptin is decreased b y 30% at the end of exercise in lean animals while resulting unaffected in obese animals. Leptin changes in lean rats are concomitant with the peak of NEFA and glycerol release from adipose tissue rather than with the reducti on of plasma insulin. Ob-gene expression in adipose tissue was markedly inc reased in fa/fa compared to lean rats, but was not modified by exercise bot h in lean and obese animals. In conclusion our data show that leptin change s during exercise are related to lipolytic events in adipose tissue and sup port a link between leptin and energy expenditure. (C) 1999 Academic Press.