Protein and carbohydrate self-selection: modification of the effects of fenfluramine and amphetamine by age and feeding regimen.
Age and daily restricted feeding are two frequently manipulated procedural variables that have been shown to alter dietary self-selection of protein and carbohydrate in rats. This study examined whether age and restricted feeding could further interact with drugs such as fenfluramine and amphetamine that are used to manipulate dietary self-selection. At the time of peak blood levels, fenfluramine spared relative intake of protein (as reflected in an increase in %P-E ratio of protein to total energy consumed). This effect, however, was significant at only some doses of fenfluramine and in some groups. At the times of peak blood levels of amphetamine, sparing of protein intake was never observed. In contrast, amphetamine tended to suppress protein intake (decrease in %P-E). This effect was dose-related (0.5, 1.0 and 2.0 mg/kg) in the adult, free-feeding rats, but not apparent in food-restricted rats. Consequently the effect of drugs on the self-selection of protein and carbohydrate diets is influenced by both age and feeding regimen. These results have implications for proposed neurochemical and hormonal hypotheses of protein and carbohydrate regulation as well as the design and interpretation of self-selection experiments.
D000367:Age Factors; D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects; D005277:Fenfluramine / Q000494:pharmacology*; D005508:Food Deprivation; D005518:Food Preferences / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D000662:Amphetamines; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D005277:Fenfluramine