Further evidence in support of a short-loop feedback action of estrogen on ovarian androgen production |
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Authors: | Peter C.K. Leung David T. Armstrong |
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Affiliation: | Departments of Obstetrics and Gynaecology and of Physiology University of Western Ontario London, Ontario, Canada |
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Abstract: | We have demonstrated previously an ability of estrogen to inhibit ovarian androgen production. We report here further evidence in support of this intraovarian short-loop feedback mechanism. Thecal cells from ovarian follicles of estradiol-17β (E)-treated rats demonstrated an enhanced capability of producing progesterone in response to LH . In contrast, testosterone production by the same thecal preparations was markedly inhibited by pretreatment with E, suggesting a selective inhibitory action of E at the level of the androgen-producing cells in the ovarian follicle. In a somewhat contrasting experiment in hypophysectomized rats, while simultaneous administration of purified follicle-stimulating hormone (FSH) antagonized an inhibitory action of E on ovarian progesterone production, treatment of the hypophysectomized rats with either E alone or concomitantly with E plus FSH still attenuated ovarian testosterone production by these animals in response to acute LH stimulation. These results are consistent with a direct inhibitory action of estrogen at the level of the ovarian C17α-hydroxylase /C17,20-lyase enzyme system. |
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