title: Effects of mGnRH on testicular steroidogenesis in the toad Bufo arenarum.
abstract: GnRH controls vertebrate reproduction in several ways. This hormone not only affects the secretion of gonadotropins from the pituitary gland but also has a direct influence on several gonadal functions such as steroidogenesis, spermatogenesis, and spermiation. In the present paper we have studied the in vitro effects of GnRH on the testicular steroidogenesis of Bufo arenarum to ascertain the role of this peptide in the control of the steroidogenic pathway previously described in this species. It was found that GnRH is able to reduce basal as well as hCG-stimulated testosterone release, having an inhibitory effect on P450(c17) activity. Thus, GnRH could be involved in the mechanism that regulates the metabolic change in the testicular steroidogenesis. Additionally, testicular GnRH binding site has been characterised, showing a K(d) of 34 nM and a maximum binding of 4.7 pmol/mg protein.
authors.affiliation: Laboratorio de Endocrinología Comparada, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales and PRHOM-CONICET, Pabellón 2, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Canosa
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Pozzi
authors.forename: Gustavo M
authors.initials: GM
authors.lastname: Somoza
authors.forename: Nora R
authors.initials: NR
authors.lastname: Ceballos
mesh_terms: D000818:Animals; D002022:Bufo arenarum; D002855:Chromatography, Thin Layer; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D008297:Male; D011863:Radioimmunoassay; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis*; D013737:Testis / Q000187:drug effects / Q000378:metabolism*
chemical_list: D013256:Steroids; D007987:Gonadotropin-Releasing Hormone; D013254:Steroid 17-alpha-Hydroxylase