Identification of pro-opiomelanocortin-derived peptides in the human adrenal medulla.

Extracts from adult human adrenals contained high concentrations of immunoreactive beta-endorphin and alpha-melanotropin. Lower quantities of immunoreactive adrenocorticotropic hormone could also be detected. Distribution studies showed the presence of pro-opiomelanocortin fragments in the adrenal medulla. No alpha-melanotropin, beta-endorphin, or adrenocorticotropic hormone could be found in adrenal extracts from several other mammalian species. Analysis of the beta-endorphin-like immunoreactivity using region specific radioimmunoassays interfacing with gel filtration and reverse-phase high-performance liquid chromatography showed the majority of the beta-endorphin-like material to exist as nonacetylated beta-endorphin-(1-31) with a small percentage of lipotropin-sized molecules. The alpha-melanotropin-like immunoreactivity cochromatographed on gel filtration and reverse-phase high-performance liquid chromatography with desacetyl alpha-melanotropin. The data suggest that pro-opiomelanocortin is expressed in the adrenal medulla of humans but is not detectable in the adrenal glands of many other mammalian species.