| Abstract
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High performance liquid chromatography (HPLC) was used to identify steroids (unconjugated (free) and conjugated) in the plasma and eggs of five-year-old adult female Arctic charr (Salvelinus alpinus). High levels of androgens, 11-oxygenated androgens, estrogens, progestogens and glucucorticoids were identified in the plasma, whereas in the eggs the predominant steroids were progestogens, such as 17,20usd\betausd-dihydroxy-4-pregnen-3-one(17,20usd\betausdP). Steroid hormone metabolism was studied during the early embryonic development of the Arctic charr. The embryos were able to metabolize progesterone, 17-hydroxyprogesterone, cortisol, androgens and estrogens in vitro, converting these steroid hormones into various metabolites that have either no or low biological activity. This marked ability to metabolize a wide range of steroid precursors suggests that a corresponding complement of steroidogenic enzymes essential for biosynthesis of all major steroid hormones are expressed during the early embryonic development. In addition, the embryos employed reduction, hydroxylation and conjugation as the means of "deactivating" some steroids suggesting the expression of reductases, hydroxylases, sulphotransferases and glucuronyl transferases. Of some interest was the production of 17,20usd\betausdP (and its sulphate) following incubation of the embryos with (H) 17-hydroxyprogesterone, and 11usd\betausd-hydroxyandrostenedione (11usd\betausdOHA) as the principal product of (H) cortisol metabolism.
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