Differential effects of amphetamine and fenfluramine on dietary self-selection in rats

Effect of Hypercaloric versus Isocaloric Lipid Diet Ration on Diurnal/Nocturnal Eating Pattern in Self-Selecting Rats.

“…1,1993 and light phases and the depression of carbohydrate intake during the 12-h light phase and on a 24-h basis. The use of separate sources of the three macronutrients and substitution of an isocaloric fat ration for a high-caloric fat ration in another study led to a decrease in percent fat and protein intakes and an increase in carbohydrate intake [6]. The discrepancy between the results of the latter study and the present one regarding fat intake may be due to the type of fat employed (vegetable fat and safflower oil in [6] vs. vegetable fat and soybean in our study).…”

“…Indeed, simply altering the type of fat available led to modifications in fat intake [7] . The present results, however, extend the previous findings [6,7] showing that rats fed a high fat ration selectively increase their protein intake during the light and dark phases but decrease their intake of carbohydrate during the light phase only when compared with rats offered an isocaloric-fat ration.…”

Effect of sibutramine on macronutrient selection in male and female rats

“…The fat-rich diet was initially decreased as weIl but remained lower than control values for the entire 6-h feeding period. Orthen-Gambill and Kanarek (1982) examined the effect of 0.5-2mg/kg of d-amphetamine on the intake ofboth a regime ofthree macronutrient-specific diets with a high-caloric fat ration (CHO: 56.9% comstarch, 27.5% dextrin, and 9.8% sucrose; PRO: 94.1 % casein; FAT: 83% vegetable fat and 4.4% safflower oil) and a regime with three isocaloric macronutrient-specific diets (CHO: 56.9% comstarch, 27.5% dextrin, and 9.8% sucrose; PRO: 94.1% casein; FAT: 39.4% vegetable fat and 2.1% safflower oil). These diets were offered to 175-gram female Sprague-Dawley rats for an 8-h period during the light phase.…”

Effect of Diet Textural Characteristics on the Temporal Rhythms of Feeding in Rats

“…However, studies have shown conflicting results on the effects of dI-fenfluramine, a 5-HT agonist, on the intakes of protein-rich and carbohydrate-rich diets (Wurtman and Wurtman, 1977;Ashley et al 1979;Orthen-Gambill and Kanarek, 1981;Peters et al 1983). Wurtman and Wurtman (1977) reported that following intraperitoneal (ip) injection of di-fenfluramine in doses of 2.5 or 5 mg/kg, young male rats (strain not mentioned) fully adapted to a two-way choice between a protein-rich (45% casein, 5% dextrin) diet and an isocaloric carbohydrate-rich (5% casein, 45% dextrin) diet, inereased their kcal intake of the protein-rieh diet relative to that of the carbohydrate-rich diet over the following 3-h period.…”

“…Peters et al (1983) observed in young male albino rats that ip injections of L-tryptophan (100 mg/kg) did not alter their choice between two diets differing in protein and carbohydrate content (15% casein, 37% comstarch, 37% Iow glucose monohydrate and 55% casein, 17% comstarch, 17% Iow glucose monohydrate), despite increases of 50% in brain concentrations of 5-HT and 5-hydroxy indoleacetic acid (5-IllAA; a 5-HT metaboIite). AIso, Orthen-Gambill and Kanarek (1981) allowed adult female SpragueDawley rats to choose between three isocaloric diets: carbohydrate (57% comstarch, 27% dextrin, 10% sucrose), protein (94% casein) and fat (39% hydrogenated vegetable oil, 2% safflower oil, 52% alphaceI). They found that ip injection of dl-fenfluramine at doses of 1.5, 3 and 6 mg/lcg reduced the kcal intake of fat ooly over an 8-h feeding period.…”