Effect of adrenocorticotropin and other proopiomelanocortin-derived peptides on testosterone secretion by the in vitro perfused testis.

Abstract

Several lines of evidence have demonstrated the presence of POMC-derived peptides in testicular tissue. Consequently, this study was designed to determine the effects of ACTH and other POMC-derived peptides on testosterone secretion by the in vitro perfused testis. Infusion of synthetic human ACTH-(1-24) at a concentration of 500 ng/ml increased (P less than 0.01) testosterone secretion over that in nontreated controls by in vitro perfused rabbit and guinea pig testes, but not by rat, hamster, or dog testes. This increase in testosterone secretion after ACTH treatment, however, was less (P less than 0.01) than that after the infusion of a maximally stimulating concentration of ovine LH (100 ng/ml). Using rabbit testes, the testosterone response to ACTH was demonstrated to be dose dependent and specific, since similar responses were observed after the infusion of synthetic human ACTH-(1-39) and purified porcine ACTH-(1-39) and since no response was observed after the infusion of a variety of ACTH fragments. Infusion of alpha MSH, beta-endorphin, or naloxone had no effect (P greater than 0.10) on testosterone secretion by either rabbit or rat testes at the doses used. These data show that rabbit and guinea pig, but not rat, hamster, and dog, testes secrete testosterone in response to ACTH.