Metabolism of estrogens and androgens by embryonic tissues of Arctic charr, Salvelinus alpinus

This study examines the ability of Arctic charr (Salvelinus alpinus) embryos to metabolize tritiated androstenedione (A(4)), testosterone (T), 17 beta-estradiol (E-2), and estrone (E-1) in vitro; the metabolic products were separated by HPLC. A(4) was poorly metabolized, with 48 to 64% of the substrate remaining even after 24 hr of incubation. The major metabolites of A(4) metabolism are E-1 and some other unidentified metabolites. T was mostly converted to A(4), along with some reduced steroids, but E-2 was a minor metabolite. Further, while E-2 was almost exclusively transformed into E-1, when E-1 was used as the precursor, there was little metabolism; the products of E-1 metabolism were small amounts of E-1 sulfate, glucuronide, E-2, and an unknown metabolite which cochromatographed with reference steroid androstenetrione (also called 11-ketoandrostenedione). It is concluded that in Arctic charr embryos there is preferential expression of a form of 17 beta-hydroxysteroid dehydrogenase resembling the type 2 isozyme of mammals that converts T and E-2 to A(4) and E-1, respectively. (C) 1997 Academic Press.