DIETARY-FAT TYPE INFLUENCES PROTEIN CONSUMPTION IN RATS GIVEN 8-HYDROXY-2-(DI-N-PROPYLAMINO)TETRALIN

Our previous work indicates that type and level of dietary fat influen ces selection of protein and carbohydrate diets. Serotonin (5HT) appea rs to be involved in this feeding behavior. In the present study, we e xamined the effects of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DP AT) on feeding behavior, and fenfluramine on in vitro 5HT and 5-hydrox yindoleacetic acid (5HIAA) release from the brain in rats fed tallow o r corn oil. Male, Sprague-Dawley rats were given a diet containing cor n oil or tallow for 2 days. In Experiment 1, rats received an injectio n of 8-OH-DPAT (a 5HT(1A) agonist) or saline and were then allowed to select from two diets: low protein/high carbohydrate or high protein/l ow carbohydrate. Prior exposure to tallow caused an increased intake o f protein and 8-OH-DPAT blunted this effect. In Experiment 2, the dors al raphe from rats fed tallow or corn oil was superfused with fenflura mine or vehicle. Superfusates were collected for analysis of 5HT and 5 HIAA. Fenfluramine increased serotonin release in tallow-fed animals a s compared to basal. These results suggest that serotonin may be invol ved in mediating tallow's effect on macronutrient selection. (C) 1998 Elsevier Science Inc.