Corticosteroid biosynthesis in vitro by testes of the grouper (Epinephelus coioides) after 17α-methyltestosterone-induced sex inversion

This study reports the unique compartmentalization of cortisol and 11‐deoxycortisol biosynthesis in vitro from [3H]17α‐hydroxyprogesterone (17P) in testicular tissues of groupers after sex inversion induced by 17α‐methyltestosterone (MT). Before MT implantation, the ovarian tissues produced only nonpolar metabolites. Following sex inversion some 6 months later, synthesis of these nonpolar metabolites was not detectable. Instead, cortisol and 11‐deoxycortisol, with yields of about 3% and 14%, respectively, were synthesized together with two other polar metabolites. The corticosteroids and polar metabolites were distinctly nondetectable in ovarian tissues of the control fish throughout the experiment. While the significance of this testicular synthesis of corticosteroids is presently unclear, it could be related to the increased energy demands arising from the reorganization of gonadal tissues during sex inversion. J. Exp. Zool. 287:453–457, 2000. © 2000 Wiley‐Liss, Inc.