Identification of Pro-Opiomelanocortin-Derived Peptides in the Human Adrenal Medulla

Extracts from adult human adrenals contained high concentrations of immunoreactive β-endorphin and α-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 $-melanotorpin, $\beta $-endorphin, or adrenocorticotropic hormone could be found in adrenal extracts from several other mammalian species. Analysis of the β-endorphin like immunoreactivity using region specific radioimmunoassays interfacing with gel filtration and reverse-phase high-performance liquid chromatography showed the majority of the β-endorphin-like material to exist as nonacetylated β-endorphin-(1-31) with a small percentage of lipotropin-sized molecules. The α-melanotropin-like immunoreactivity cochromatographed on gel filtration and reverse-phase high-performance liquid chromatography with desacetyl α-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.