title: Sex steroid binding proteins in the plasma of the green frog, Rana esculenta: changes during the reproductive cycle and dependence on pituitary gland and gonads.
abstract: Sex steroid binding proteins (SSBP) have been reported in the plasma of female and male Rana esculenta. In both sexes SSBP bind [3H]estradiol and [3H]testosterone with medium-high affinity and high specificity. Using ion-exchange chromatography SSBP resolve into two peaks eluting at 0.27 M (peak I) and 0.36 M (peak II) NaCl. Both peaks bind [3H]estradiol and [3H]testosterone equally well. Isoelectrofocusing showed that peak I focused at pH 6.0 and 7.5, whereas peak II focused at pH 6.0. SSBP capacity for [3H]estradiol and [3H]testosterone changes throughout the reproductive cycle, showing low levels during the nonbreeding period and increasing levels during the breeding period. Hypophysectomy and/or gonadectomy result in small changes in SSBP capacity. Short-term steroid hormone treatment of gonadectomized animals does not modify SSBP capacity.
authors.affiliation: Department of Zoology, Università degli Studi di Napoli, Federico II, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Paolucci
authors.forename: M M
authors.initials: MM
authors.lastname: Di Fiore
mesh_terms: D000818:Animals; D004958:Estradiol / Q000097:blood / Q000378:metabolism; D005260:Female; D006801:Humans; D007016:Hypophysectomy; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology*; D010902:Pituitary Gland / Q000502:physiology*; D011893:Rana esculenta / Q000097:blood / Q000502:physiology*; D012738:Sex Hormone-Binding Globulin / Q000302:isolation & purification / Q000378:metabolism*; D012741:Sexual Maturation / Q000502:physiology*; D013737:Testis / Q000502:physiology*; D013739:Testosterone / Q000097:blood / Q000378:metabolism
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol