Intraduodenal infusions of fat inhibit sham feeding in Zucker rats.

Intraduodenal infusions of Intralipid in concentrations of 0.125 kcal/ml to 1 kcal/ml inhibited sham feeding of lean and obese Zucker rats significantly. The inhibitory potency of the fat infusions on sham feeding in both genotypes was a function of the concentration of Intralipid infused. The inhibition of sham feeding by Intralipid infusions was accompanied by the specific sequence of behaviors that characterizes satiety. Evidence supporting differential effectiveness of intraduodenal fat in producing satiety in obese and lean rats was equivocal. A conservative interpretation is that obese rats are not less sensitive than leans to the satiating potency of intraduodenal fat. We conclude that previously reported differences in the satiating potency of fats for obese and lean Zucker rats are not likely to be mediated by small intestinal mechanisms.