SYNTHESIS OF 17,20-ALPHA BETA-DIHYDROXY-4-PREGNEN-3-ONE AND 5-BETA-PREGNANES IN SPERMATOZOA OF PRIMARY AND 17-ALPHA-METHYLTESTOSTERONE-INDUCED SECONDARY MALE GROUPER (EPINEPHELUS-COIOIDES)/

The in vitro metabolism of [H-3] 17-hydroxyprogesterone by spermatozoa of primary and 17 alpha-methyltestosterone (MT)-induced secondary mal e grouper (Epinephelus coioides) has been examined. With only the labe led precursor, the four predominant 5 beta-pregnanes (17,20 alpha-dihy droxy-5 beta-pregnan-3-one; 5 beta-pregnan-3 alpha, 17,20 alpha-triol; 3 alpha, 17-dihydroxy-5 beta-pregnan-20-one; and 17-hydroxy-5 beta-pr egnan-3,20-dione) accounted for 75% of the total product yield, with t he remainder comprising 17,20 alpha-dihydroxy-4-pregnen-3-one (17,20 a lpha P) and traces (3%) of 17,20 beta-dihydroxy-4-pregnen-3-one. This is the first report of the synthesis of these 5 beta-pregnanes by tele ost spermatozoa. The addition of excess unlabeled precursor caused a m arked shift to the synthesis of only 17,20 alpha beta. The steroidogen ic profile in spermatozoa of the primary and secondary males appears s imilar in both cases. The shift to 17,20aP synthesis at high substrate concentration may suggest a gonadotropin (GtH) control of 17,20 alpha P synthesis, involving the competition for 17P between the high-activ ity, low-capacity SP-reductases and the low-activity high-capacity 20 alpha-HSD. Poor spermiation in MT-induced males may thus be due to the lack of 17P arising from low GtH secretion in vivo in the secondary m ales, (C) 1998 Academic Press.