Effects of 2 G on adiposity, leptin, lipoprotein lipase, and uncoupling protein-1 in lean and obese Zucker rats

Male Zucker rats were exposed to 2 G for 8 wk to test the hypothesis that t he leptin regulatory pathway contributes to recovery from effects of 2 G on feeding, growth, and nutrient partitioning. After initial hypophagia, body mass-independent food intake of the lean rats exposed to 2 G surpassed tha t of the lean rats maintained at 1 G, but food intake of the obese rats exp osed to 2 G remained low. After 8 wk at 2 G, body mass and carcass fat were less in both genotypes. Leptin and percent fat were lower in lean rats exp osed to 2 G vs. 1 G but did not differ in obese rats exposed to 2 G vs. 1 G . Although exposure to 2 G did not alter uncoupling protein-1 levels, it di d elicit white fat pad-specific changes in lipoprotein lipase activity in o bese but not lean rats. We conclude that 2 G affects both genotypes but tha t the lean Zucker rats recover their food intake and growth rate and retain "normal" lipoprotein lipase activity to a greater degree than do the obese rats, emphasizing the importance of a functional leptin regulatory pathway in this acclimation.