Adrenocorticotrophic and melanocyte-stimulating peptides in the human pituitary.

The adrenocorticotrophic and melanocyte-stimulating peptides of the human pituitary were investigated by means of radioimmunoassay, bioassay and physicochemical procedures. Substantial amounts of adrenocorticotrophin and a peptide resembling beta-lipotrophin were identified in pituitary extracts, but alpha-melanocyte-stimulating hormone, beta-melanocyte-stimulating hormone and corticotrophin-like intermediate lobe peptide, which have been identified in the pars intermedia of pituitaries from other vertebrates, were not found. The absence of beta-melanocyte-stimulating hormone appears to contradict previous chemical and radioimmunological studies. Our results suggest, however, that it is not a natural pituitary peptide but an artefact formed by enzymic degradation of beta-lipotrophin during extraction.