Suppression of ethanol intake in chickens by fenfluramine and dietary tryptophan

Two groups of 10-week-old White Leghorn cockerels were fed a commercial grower diet with or without an L-tryptophan (0.5%) supplement. After a 24-hr water deprivation and 13 to 14 hr without food, the birds were randomly injected with 0 (saline) 4, 8, or 12 mg of fenfluramine/kg body weight. Thirty minutes after injections, water or a 5% ethanol solution was offered, no choice, to the birds and fluid consumption as well as skin and rectal temperature before and after fluid availability were measured. The ethanol solution in otherwise untreated animals was consumed in similar amounts as water was. Fenfluramine (8 mg/kg) significantly reduced ethanol consumption and tryptophan further significantly reduced ethanol intake. At 12 mg/kg fenfluramine, both water and ethanol intake were sharply reduced. Ethanol decreased body temperature, an effect that was reversed by both tryptophan alone and fenfluramine + tryptophan in a dose-dependent manner. These observations are discussed in reference to the effects of central serotonergic manipulations and ethanol consumption.