INTERMEDIN AND CHANGE OF COLOR IN FROGS: A NEW HYPOTHESIS

Abstract

The indolalkylamines, tryptamine and serotonin, have a slight but distinct melanophorotropic effect on the melanocytes of frog skin. Other work has shown that the skin of amphibians contains large amounts of serotonin. The present work offers evidence that intermedin has an indirect effect on the melanocytes of frogs, that another compound, destroyed by monoamine oxidase and phenol oxidase, is involved in the normal darkening process, and that intermedin promotes the release of a pharmacologically active substance from frog skin in vitro. This is taken as evidence on which to erect the hypothesis that intermedin acts on the skin to release an indolalkylamine which then acts on the melanocytes to bring about the darkening of the skin.