Anorexigenic substance isolated from feces of rat and mouse

A substance was isolated from the feces of conventional rats and mice which were fed laboratory diets. Marked reduction in food intake occurred for a few hours after intraperitoneal administration of this substance, while water intake also decreased. Two hr after the injection, when the anorectic effect appeared to be the strongest, no change was found in body temperature or blood glucose, but free amino acids in plasma were decreased. A comparative study using germfree and conventional mice indicated that the anorexigenic substance was produced by gastrointestinal microflora, since the yields of the anorexigenic substance from germfree mice was less than one tenth of that from conventional mice. A partially purified form of the substance, with large molecular weight, was isolated by Sephadex G-150 fractionation. It contained protein but the anorexigenic activity was not diminished by protein digestion.