Role of catecholestrogens on ovarian prostaglandin secretion in vitro in the catfish Heteropneustes fossilis and possible mechanism of regulation

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• 作者：T.K. Chourasia ; K.P. Joy ; ^{keerikkattilpailyjoy@yahoo.com} ; ^{kpjoybhu@gmail.com}
• 关键词：Adrenergic receptors ; Catecholestrogens ; Catfish ; Cell signaling pathway ; Estrogen receptor ; Prostaglandins
• 刊名：General and Comparative Endocrinology
• 出版年：2012
• 期刊代码：169_00166480
• 类别：bio
• 出版时间：15 May, 2012
• 卷：177
• 期：1
• 页码：128-142
• 文件大小：2560 K

摘要

Seasonal, periovulatory and 2-hydroxyestradiol-17尾 (2-OHE₂)-induced changes on ovarian prostaglandin (PG) E₂ and F_2伪 were investigated under in vivo or in vitro in the female catfish Heteropneustes fossilis. Both PGE₂ and PGF_2伪 increased significantly during ovarian recrudescence with the peak levels in spawning phase. The PGs showed periovulatory changes with the peak levels at 16 h after the hCG treatment. Incubation of postvitellogenic ovary fragments with estradiol-17尾 (E₂), 2-OHE₂ or 2-methoxyE₂ produced concentration-dependent increases in PG levels; 2-OHE₂ was more effective. In order to identify the receptor mechanism involved in the 2-OHE₂-induced PG stimulation, the ovarian pieces were incubated with phentolamine (an 伪-adrenergic antagonist), propranolol (a 尾-adrenergic antagonist) or tamoxifen (an estrogen receptor blocker) alone or in combination with 2-OHE₂. The incubation of the tissues with the receptor blockers alone did not produce any significant effect on basal PG levels. However, co- and pre-incubation of the tissues with the blockers resulted in inhibition of the stimulatory effect of 2-OHE₂ on the PGs. Phentolamine was more effective than propranolol. The signal transduction pathway(s) involved in the 2-OHE₂-induced PG secretion was investigated. The incubation of the ovarian pieces with 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor), chelerythrine (a protein kinase C inhibitor) and PD098059 (a mitogen-activated protein kinase inhibitor) significantly lowered the basal secretion of PGF_2伪 and PGE₂. In contrast, H89 (a protein kinase A inhibitor) increased the basal secretion of PGs at 1 and 5 渭M concentration and decreased it at 10 渭M concentration. The co- or pre-incubation with IBMX, H89, chelerythrine and PD098059 significantly inhibited the stimulatory effect of 2-OHE₂ on PGF_2伪 and PGE₂ levels. The inhibition was higher in the pre-incubation groups. Chelerythrine was the most effective followed by PD098059, IBMX and H89. The results suggest that 2-OHE₂ may employ both adrenergic and estrogen receptors, or a novel receptor mechanism having properties of both adrenergic and estrogen receptors.