MECHANISMS FOR COMPENSATORY GROWTH OF ADIPOSE TISSUE IN LIPECTOMIZED RATS by

Studies were designed to examine the regulation of body weight/fat by lowering body weight/fat through surgical removal of bilateral epididymal fat pads of adult male Wistar rats. Food intake during the first 4 weeks and energy expenditure on day 7-10 and day 28-31 post surgery were not different between lipectomized and sham operated rats. The carcass composition of lipectomized and sham operated rats was not significantly different 16 weeks post surgery, indicating a compensatory adipose tissue growth in lipectomized rats. The compensatory growth of adipose tissue was fat pad specific: both mesenteric and retroperitoneal fat pads, but not inguinal or perirenal fat pads were significantly heavier in lipectomized rats than in sham operated rats. Lipectomized rats had more total, small and large adipocytes at 4 weeks, and more total and large adipocytes at 16 weeks, than sham operated rats in the retroperitoneal fat depot, suggesting that both hyperplasia and hypertrophy contributed to the compensatory growth. Leptin and insuli