title: Seasonal changes in the activity of 11 beta-hydroxysteroid dehydrogenase in toad testes.
abstract: In mammals, glucocorticoids (GC) are inactivated by the oxidative activity of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). To study that mechanism in the testes of Bufo arenarum, 11beta-HSD activity and plasma corticosterone (B) were determined in toads from pre- (PR), post- (P), and reproductive (R) periods. Toad 11beta-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, 11beta-HSD could protect testes against GC action.
authors.affiliation: Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
authors.forename: Daniela
authors.initials: D
authors.lastname: Denari
authors.forename: Nora R
authors.initials: NR
authors.lastname: Ceballos
mesh_terms: D042842:11-beta-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D002022:Bufo arenarum / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006034:Glycyrrhetinic Acid / Q000494:pharmacology; D008297:Male; D012621:Seasons; D013737:Testis / Q000187:drug effects / Q000201:enzymology*
chemical_list: D042842:11-beta-Hydroxysteroid Dehydrogenases; D006034:Glycyrrhetinic Acid