Study of serum leptin in cafeteria-diet-overfed rats - Influence of diet, insulin and corticosterone

In a group of 15 male Wistar rats overfed with cafeteria foods (delivering a mean fat percentage of 60%) during 5 months from the age of 8 weeks and i n a control group of 15 rats fed with a standard chow for the same period, serum leptin, insulin and corticosterone were measured by RIA and body comp osition was determined by dual-energy X-ray absorptiometry. Significantly h igher fasting serum concentrations of leptin, insulin and corticosterone we re found in the cafeteria-diet group. Fasting leptin concentrations were si gnificantly higher in rats with a body fat percentage of more than 25% comp ared to the others, irrespective of the type of feeding. The log serum lept in correlated positively with body fat percentage and fasting insulin conce ntration but not with corticosterone concentration. Leptin concentration co rrected for body fat mass was, however, comparable between the two diet gro ups, while the leptin/insulin ratio was lower in the cafeteria-diet group. In conclusion, chronic overfeeding resulting in an increased body fat perce ntage in rats is associated with hyperleptinemia, hyperinsulinemia and hype rcorticism. Serum leptin levels appear to primarily track total body fat pe rcentage and are unaffected by dietary fat manipulation in cafeteria-diet-i nduced obese rats.