Publication Abstract

Extragonadal production of17,20-dihydroxy-4-pregnen-3-ones in teleost fish

M. Ebrahimi, A.P. Scott and D.E. Kime

Muscle, heart,eye, testis, blood, and sperm of trout and goldfish have been examined for the presence of20-hydroxysteroid dehydrogenase by incubation with [³H] 17hydroxyprogesteronein the presence of 0, 0.1, 1, or 10 µg/ml of unlabeled substrate. In trout,17-hydroxyprogesterone was metabolized only by sperm and testis, with 17,20β-dihydroxy-4- pregnen-3-one (17,20αP) asthe major product and traces (< 2%) of 17,20α-dihydroxy4-pregnen-3-one (17,20αP). In goldfish, maximum conversion of 17-hydroxyprogesterone to17,20αP was over30% per 100 mg tissue in eyeball, heart, and testis, 12% per 20 µl blood, and 18% per 20µ.l sperm, but less than 5% per 100 mg muscle. 17,20αP was the only metabolite of 17-hydroxyprogesterone in allincubations of nongonadal tissue in goldfish. Within the cyprinid eye, there was nosignificant activity in the lens, the fluids, or the retina. The possible relationshipbetween the teleost 20α- and 20β-hydroxysteroiddehydrogenases, the mammalian 20-hydroxysteroid dehydrogenases, and members of thealdo-keto reductase and short-chain dehydrogenase superfamilies is discussed.

Reference:

M. Ebrahimi, A.P. Scott and D.E. Kime, 1996. Extragonadal production of17,20-dihydroxy-4-pregnen-3-ones in teleost fish. General and Comparative Endocrinology,104: 296-303.