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 (A4), testosterone (T), 17 beta-estradiol (E2), and estrone (E1) in vitro; the metabolic products were separated by HPLC. A4 was poorly metabolized, with 48 to 64% of the substrate remaining even after 24 hr of incubation. The major metabolites of A4 metabolism are E1 and some other unidentified metabolites. T was mostly converted to A4, along with some reduced steroids, but E2 was a minor metabolite. Further, while E2 was almost exclusively transformed into E1, when E1 was used as the precursor, there was little metabolism; the products of E1 metabolism were small amounts of E1 sulfate, glucuronide, E2, 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 E2 to A4 and E1, respectively.