Melanocyte-stimulating hormone—mimetic action of the phenothiazines

Abstract

Abstract We have compared the melanophore-stimulating action of four phenothiazines, trifluoperazine, perphenazine, chlorpromazine, and prochlorperazine, with α-MSH on the skin of the lizard Anolis carolinensis, using a new rate method of bioassay. The dose-response curves for the phenothiazines were parallel to that of α-MSH, and when given together α-MSH and chlorpromazine were additive. The phenothiazines may therefore stimulate melanosome dispersion in the lizard skin by the same mechanism as α-MSH; a MSH-mimetic action of phenothiazines may similarly explain their pigmentary action in man. The pigmentary potency of the phenothiazines corresponded with their therapeutic potency in man; this is in keeping with a neuro-regulatory role for MSH peptides and suggests a possible therapeutic use for them.