Feeding supression after a lipid meal in normal and obese rats

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We tested the satiation after intraduodenal infusion of triglyceride with or without Pluronic L-81 (L-81) in rats to evaluate postabsorptive factors for satiation after a lipid meal. L-81 suppresses lipid transport into mesenteric lymph by preventing the formation of chylomicrons. Under unrestrained condition, a lipid emulsion was infused into 24h fasted rats intraduodenally for 8h. Following the infusion, food intake during the first 30 min and blood samples were measured. Food intake after the 8-h lipid infusion decreased significantly compared to that of rats infused with vehicle only. The satiation effect of the lipid was lost as a result of L-81 treatment but food intake was still significantly decreased. The loss of inhibition of food intake by the feeding of lipid plus L-81 was totally reversed by the cessation of L-81 intusion. In rats infused with the lipid emulsion, plasma level of triglyceride and apolipoprotein A-IV increased significantly. This increase was abolished by the presence of L-81 in the lipid infusate. The present study indicates that postabsorptive factors are important for anorexia observed after a lipid meal in addition to preabsorptive factors. This anorectic effect was attenuated in Zucker obese rats, indicating that loss of sensitivity to post-absorptive factors in Zucker obese rats contributed to the development of their obesity. This study further supports our previous conclusion that apolipoprotein A-IV is an important postabsorptive factor for satiation after a lipid meal.