Regulation of plasma gonadotropin II secretion by sex steroids, aromatase inhibitors, and antiestrogens in the protandrous black porgy, Acanthopagrus schlegeli Bleeker
| Autor: | Cheng-Yen Lee, Fan-Pin Yen, Yan-Horn Lee, Jin-Lien Du, Lian-Tien Sun, Jing-Duan Huang, Sylvie Dufour, Ching-Fong Chang |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Male
endocrine system medicine.medical_specialty Physiology medicine.drug_class Feedback control Stimulation Biochemistry Feedback Aromatase Estrogen Receptor Modulators Internal medicine medicine Acanthopagrus schlegeli Animals Secretion Testosterone Enzyme Inhibitors Gonads Molecular Biology Enclomiphene biology Estradiol Fadrozole Aromatase Inhibitors Estrogen Antagonists Antiestrogen Perciformes Tamoxifen Endocrinology Gonadotropins Pituitary biology.protein Female Steroids Gonadotropin |
| Zdroj: | Comparative biochemistry and physiology. Part B, Biochemistrymolecular biology. 129(2-3) |
| ISSN: | 1096-4959 |
| Popis: | 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, P0.05). 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. |
| Databáze: | OpenAIRE |
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