Presence of pro-opiomelanocortin-related peptides in dog adrenal gland

Coupling high performance liquid chromatography to specific radioimmunoassays, this study evaluates the presence of several pro-opiomelanocortin(POMC)-related peptides in dog adrenal gland. In addition to Met-enkephalin, adrenals contain β-lipotropin, β-endorphin, ACTH, α-MSH, des-acetyl-α-MSH and acetyl-gamma-EP. β-endorphin is the peptide more represented in the gland, and despite the presence of acetylated peptides, no acetyl-β-endorphin was detected. The content of both melanotropins prevails over that of ACTH suggesting an extensive processing of POMC, like that occurring in intermediate pituitary and brain. These data demonstrate that dog adrenal gland could be a source of POMC-derived opioid peptides. Their high contents (equal or even higher than those of pituitary) suggest a possible local function, i.e. modulating steroidogenesis.