Inhibition by Tamoxifen of the stimulatory action of FSH on oestradiol-17 synthesis by rat ovaries in vitro

Abstract

Previous studies (Watson, Anderson, Alam, O'Grady & Heald, 1975) have established that the compound Tamoxifen (ICI 46,474) either delays or inhibits implantation in the rat depending on the dose. This effect on implantation is associated with delay or prevention of the oestrogen surge normally required for implantation in the rat, and studies in vitro have demonstrated that at least part of the antifertility action of Tamoxifen is to inhibit directly the ovarian synthesis of oestradiol (Watson & Alam, 1976). Because the site of the inhibition appears to be at the aromatizing system (Watson & Alam, 1976) and FSH has been reported as having a stimulatory effect on the aromatizing enzyme complex (Moon, Dorrington & Armstrong, 1975), the purpose of the present investigation was to determine whether Tamoxifen acts by blocking the stimulatory action of FSH.