Intraperitoneal injections of tryptophan inhibit food intake in the fowl

The effects of intraperitoneal injections of tryptophan on food intake in the chicken were examined. Four levels of tryptophan (12.5, 25, 50, 100 mg), and a saline control were tested in birds that were ad libitum fed or fasted 24 hr. The tryptophan treatments decreased food intake in the ad libitum-fed chickens in a dose-dependent manner. Food intake of the 24-hr fasted chickens was not influenced by the tryptophan injections. It is not known whether tryptophan is acting centrally or peripherally to decrease food intake of ad libitum-fed chickens.