title: Regulation of plasma gonadotropin II secretion by sex steroids, aromatase inhibitors, and antiestrogens in the protandrous black porgy, Acanthopagrus schlegeli Bleeker.
abstract: Plasma gonadotropin II (GTH II) concentrations were significantly higher (approx. 15-20-fold) in estradiol-17beta (E(2)) treated (1.0 microg or 2.5 microg g(-1) body weight) female black porgy from days 4 to 12 compared with the control. E(2) (1 microg g(-1) wt.) had a stronger stimulation on plasma GTH II in early recrudescent phase (low GSI) males (11-fold) than in high GSI and late spermiating males (2.6-fold, P< 0.05). No effect of androgens (testosterone, T; 5alpha-dihydrotestosterone, DHT) on plasma GTH II levels was observed either sex. The levels of plasma GTH II were stimulated in 1,4,6-androstatriene-3,17-dione (ATD, 1 microg g(-1), 2 microg g(-1) body wt.) and fadrozole-treated (1 microg g(-1), 3 microg g(-1) body wt.) groups compared to control. Tamoxifen (1 microg g(-1), 3 microg g(-1) body wt.) but not enclomiphene could stimulate high GTH II levels in plasma. In another experiment of ATD in combination with T, T treatment further attenuated the ATD stimulation of plasma GTH II levels. We concluded that GTH II secretion is positively regulated by an estrogen-specific effect in female and male black porgy. Gonadal stage had significant effects on the responsiveness of GTH II to E(2) stimulation in males. A negative aromatase-dependent feedback control of plasma GTH II levels was also suggested in the protandrous black porgy, Acanthopagrus schlegeli.
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, 202, Taiwan, Republic of, Keelung, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Lee
authors.forename: J L
authors.initials: JL
authors.lastname: Du
authors.forename: F P
authors.initials: FP
authors.lastname: Yen
authors.forename: C Y
authors.initials: CY
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Dufour
authors.forename: J D
authors.initials: JD
authors.lastname: Huang
authors.forename: L T
authors.initials: LT
authors.lastname: Sun
authors.forename: C F
authors.initials: CF
authors.lastname: Chang
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D017316:Fadrozole / Q000494:pharmacology; D005246:Feedback / Q000187:drug effects; D005260:Female; D006065:Gonadotropins, Pituitary / Q000097:blood* / Q000378:metabolism*; D006066:Gonads / Q000187:drug effects; D008297:Male; D010473:Perciformes / Q000378:metabolism*; D013256:Steroids / Q000494:pharmacology*; D013629:Tamoxifen / Q000494:pharmacology; D013739:Testosterone / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D004965:Estrogen Antagonists; D020847:Estrogen Receptor Modulators; D006065:Gonadotropins, Pituitary; D013256:Steroids; D013629:Tamoxifen; D013739:Testosterone; D004958:Estradiol; D001141:Aromatase; D017316:Fadrozole