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), 17β-estradiol (E 2), and estrone (E 1) in vitro;the metabolic products were separated by HPLC. A 4was poorly metabolized, with 48 to 64% of the substrate remaining even after 24 hr of incubation. The major metabolites of A 4metabolism are E 1and some other unidentified metabolites. T was mostly converted to A 4, along with some reduced steroids, but E 2was a minor metabolite. Further, while E 2was almost exclusively transformed into E 1, when E 1was used as the precursor, there was little metabolism; the products of E 1metabolism were small amounts of E 1sulfate, 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 17β-hydroxysteroid dehydrogenase resembling the type 2 isozyme of mammals that converts T and E 2to A 4and E 1, respectively.