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Seasonal Changes in the Activity of 11β‐Hydroxysteroid Dehydrogenase in Toad Testes
Author(s) -
DENARI DANIELA,
CEBALLOS NORA R.
Publication year - 2005
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1327.046
Subject(s) - toad , medicine , endocrinology , dehydrogenase , corticosterone , hydroxysteroid dehydrogenase , chemistry , oxidative phosphorylation , nad+ kinase , enzyme , biology , hormone , biochemistry
A bstract : In mammals, glucocorticoids (GC) are inactivated by the oxidative activity of 11β‐hydroxysteroid dehydrogenase (11β‐HSD). To study that mechanism in the testes of Bufo arenarum , 11β‐HSD activity and plasma corticosterone (B) were determined in toads from pre‐ (PR), post‐ (P), and reproductive (R) periods. Toad 11β‐HSD is NAD + ‐dependent and strongly inhibited by glycyrrhetinic acid. V max is higher in the P period (1.37 vs. R: 0.13 and PR: 0.26 pmol/min‐mg protein), whereas K m values (around 200 nM) remain constant. Plasma B concentrations (R: 178; PR: 61; P: 114 nM) are close to K m values, suggesting that, under baseline conditions, 11β‐HSD could protect testes against GC action.