In vitro effects of 2-hydroxyestradiol-17¦Â on ovarian follicular steroid secretion in the catfish Heteropneustes fossilis and identification of the receptor and signaling mechanisms

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• 作者：T.K. Chourasia ; K.P. Joy ; ^{keerikkattilpailyjoy@yahoo.com} ; ^{kpjoybhu@gmail.com}
• 关键词：Adrenergic receptors ; Catecholestrogen ; Catfish ; Cell signaling pathways ; Germinal vesicle breakdown ; In vitro follicular steroid secretion
• 刊名：General and Comparative Endocrinology
• 出版年：2012
• 出版时间：1 February 2012
• 年：2012
• 卷：175
• 期：3
• 页码：500-513
• 全文大小：2058 K

文摘

Ovarian pieces containing postvitellogenic follicles were incubated in vitro with different concentrations of the catecholestrogen 2-hydroxyestradiol-17¦Â (2-OHE₂) to evaluate its effects on steroid production and germinal vesicle breakdown (GVBD) in the catfish Heteropneustes fossilis. The incubation with 2-OHE₂ induced a shift in steroidogenic pattern: the C₁₉ and C₁₈ steroids testosterone (T) and estradiol-17¦Â (E₂), respectively were significantly decreased with a concomitant significant increase in the C₂₁ steroids progesterone (P₄), 17-hydroxyprogesterone (17-OHP), 17,20¦Â-dihydroxy-4-pregnen-3-one (17,20¦Â-DP), 17,20¦Á-dihydroxy-4-pregnen-3-one (17,20¦Á-DP) and cortisol (F). Concomitantly, the catecholestrogen induced dose-dependently GVBD response, the first sign of meiosis resumption. The co- and pre-incubations of the ovarian pieces with 2-OHE₂, and adrenergic (phentolamine, ¦Á-blocker and propranolol, ¦Â-blocker) or estrogen (tamoxifen) receptor blockers resulted in inhibition of the stimulatory effect of the catecholestrogen on C₂₁ steroids and reversed the inhibition of testosterone and E₂. The ¦Á-blocker was more effective than the ¦Â-blocker. Our results suggest that 2-OHE₂ appears to employ both adrenergic (¦Á-type) and estrogen receptor mechanisms in mediating the effects. The co- or pre-incubation of ovarian pieces with IBMX (a cAMP elevating drug), H89 (a protein kinase A inhibitor), and PD098059 (a MAP kinase kinase inhibitor) significantly inhibited the stimulatory effect of 2-OHE₂ on the C₂₁ steroids. The effect of chelerythrine (a protein kinase C inhibitor), on the other hand, varied with the incubation condition. In the co-incubation, the steroids showed varied effects: 17,20¦Â-DP, testosterone and E₂ were elevated, and P₄ and 17-OHP were decreased. In the pre-incubation set up, all the steroids were inhibited except E₂. The inhibition by the blockers was higher in the pre-incubation groups. Taken together, the data suggest the involvement cAMP-protein kinase A, protein kinase C and MAP kinase pathways in the modulation of the steroidogenic activity.