Steroidogenesis in the testes and seminal vesicles of spawning and non-spawning African catfish, Clarias gariepinus

Abstract

The in vitro biosynthesis of steroids was studied in testes as well as seminal vesicles of non-spawning pond and spawning feral African catfish, collected during the breeding season. In testes of non-spawners the conversion of [3H]-pregnenolone was directed towards 11-oxygenated androgens and 5β-pregnane-3α,17α,20α-triol, whereas in testes of spawners the production of progesterone and 17α-hydroxyprogesterone prevailed. The seminal vesicles, on the other hand, produced mainly pregnenolone ester, androstenedione and testosterone in non-spawning catfish and 5β-reduced steroids in spawning catfish. Furthermore, in these seminal vesicles, steroid glucuronide synthesis dominated much more than in testes. There was, however, no difference in synthesizing capacity between the two groups. Spawning was accompanied by elevated plasma gonadotropin levels.