Studies on food intake in the fasted rat.

1. The effects of orally- and intravenously-administered d-amphetamine-SO4, fenfluramine-HCl and cocaine-HCl on food intake in the fasted rat were compared. 2. During the first hour after presentation of food to the animals, ED50 values for suppression of food intake after intravenous injection were: d-amphetamine-SO4, 0.1 mg/kg; fenfluramine-HCl, 0.6 mg/kg; cocaine-HCl, 1.0 mg/kg, ED50 values for suppression of food intake after oral administration were: d-amphetamine-SO4, 0.3 mg/kg; fenfluramine-HCl, 0.7 mg/kg; cocaine-HCl, 9 mg/kg. 3. Over a 4 hr test period, d-amphetamine, fenfluramine and cocaine produced dose-dependent anorexigenic effects only when orally administered. 4. Orally-administered quipazine-maleate and mazindol also decreased food intake, their respective ED50 values being 7 mg/kg and 1.2 mg/kg for the first hour of testing; the anorexigenic effect of mazindol appeared to be more sustained than those of the other anorexigenic agents tested in that it was evident on the day after drug administration. 5. Orally-administered diazepam increased food intake on the day of its administration, but decreased food intake on the day after its administration. 6. In addition to providing further evidence for the effects of several typical anorexigenic agents, the model described might be useful for further studies on anorexigenic agents and minor tranquillizers.