Condeça, João B.Canario, Adelino V. M.2014-05-152014-05-152001-06-13Condeca, J. B.; Canario, A. V. M.Gonadal steroidogenesis in response to estradiol-17b administration in the sea bream (Sparus aurata L.), General and Comparative Endocrinology, 124, 1, 82-96, 2001.0016-6480AUT: ACA00258;http://hdl.handle.net/10400.1/3965The sea bream (Sparus aurata) is a protandrous hermaphrodite teleost fish in which estrogen administration induces testicular regression without influencing ovarian development. To analyze the changes in steroidogenesis of fish treated with two levels of estrogen (2 and 10 mg · kg−1) and untreated control fish, fragments of gonads were incubated with tritiated 17-hydroxyprogesterone and the metabolites identified. The ability to extract radioactivity decreased with incubation time and was lower in gonads containing a larger proportion of ovarian tissue. The difference in steroidogenic capacity between control and estrogen-treated groups was generally quantitative rather than qualitative and paralleled the observed histological changes. The same metabolites were identified in all three groups, but estrogen treatment caused a marked inhibition of 5β-reduction, 3α-reduction, side-chain cleavage, and 11β-hydroxylation. The main androgens identified were 11β-hydroxy-4-androstene-3,17-dione and 3α-hydroxy-5β-androstane-3,17-dione, and the synthesis of both steroids was inhibited by estrogen treatment. Of the more polar pregnanes, 5β-pregnane-3α,17,20α-triol and 5β-pregnane-3α,17,20β-triol were detected in significant amounts, but only the latter appeared to be associated with development of the testis (in the untreated fish). A feature of sea bream gonadal steroidogenesis less common in other teleosts was the presence of 6α- and 6β-hydroxylation.engSteroidogenesisEstrogenSparus aurataTeleostjournal article2014-05-13http://dx.doi.org/10.1006/gcen.2001.7689