MORPHOLOGICAL AND METABOLIC CHANGES ASSOCIATED WITH LARGE DIFFERENCESIN DAILY FOOD-INTAKE IN CROSSED-INTESTINES RATS

Twenty-two inbred male Lewis rats were made into parabiotic pairs and 7 pairs had a further operation in which the small intestines of the 2 rats were connected so that one rat continually lost food into the up per small intestine and bloodstream of its partner. As a result, these rats showed large and sustained changes in daily food intake with one rat (A) in each pair eating more than twice as much as its partner (B ) for the rest of their lives. Measurements of plasma levels of glucos e, insulin, and glucagon did not vary directly with daily food intake, but integrated plasma lactate values were lower in rats that ate more (A) and higher in rats that ate less (B). At sacrifice, the rats that ate more were found to have less fat with reduced fat cell size but t he same cell number in both retroperitoneal and epididymal fat pads. M easurements of the rate and pattern of glucose metabolism in retroperi toneal fat cells with or without insulin stimulation were similar acro ss groups. Rates of lipolysis with and without epinephrine did not dif fer among groups. Lipoprotein lipase varied directly with fat cell siz e and indirectly with dairy food intake. These studies show that daily food intake Varies directly with fat cell size and inversely with pla sma lactate and retroperitoneal lipoprotein lipase levels. (C) 1997 El sevier Science Inc.