title: In vitro hCG and human recombinant FSH actions on testicular steroidogenesis in the toad Bufo arenarum.
abstract: In order to study the regulation of testicular steroidogenesis in the toad Bufo arenarum, the effect of gonadotropins (hCG and hrFSH) on steroidogenic enzymes was determined using an in vitro system. 3beta-Hydroxysteroid dehydrogenase/isomerase activity was not affected by any of the gonadotropins, at any of the concentrations used. In contrast, 5alpha-reductase activity was strongly reduced by both hCG and hrFSH. Human chorionic gonadotropin inhibited the activity of cytochrome P450 17alpha-hydroxylase-C(17-20) lyase (P450(c17)), only at the highest concentration used, while hrFSH strongly reduced P450(c17) activity at all the doses assayed. In conclusion, these data suggest that LH (hCG) and FSH regulate steroidogenic enzymes such as 5alphaRed and P450(c17). The results also suggest that FSH could be involved in the regulation of the change in steroidogenesis undergone by the testis during the breeding season. In turn, the inhibition of P450(c17) activity could result in a reduction of androgen production and an increment of C21 steroids.
authors.affiliation: PRHOM-CONICET and Laboratorio de Endocrinología Comparada, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Pabellón 2, Universidad de Buenos Aires, C1428 EHA Buenos Aires, Argentina.
authors.forename: L F
authors.initials: LF
authors.lastname: Canosa
authors.forename: N R
authors.initials: NR
authors.lastname: Ceballos
mesh_terms: D000818:Animals; D002022:Bufo arenarum; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D011375:Progesterone Reductase / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D013251:Steroid Isomerases / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis*; D013737:Testis / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism
chemical_list: C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D006063:Chorionic Gonadotropin; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D013256:Steroids; D005640:Follicle Stimulating Hormone; D010088:Oxidoreductases; D011375:Progesterone Reductase; D013254:Steroid 17-alpha-Hydroxylase; C021936:3-oxo-5 beta-steroid delta 4-dehydrogenase; D013251:Steroid Isomerases