Antagonism of estrogen action with a new benzothiophene derived antiestrogen

doi:10.1016/0024-3205(83)90935-9

Life Sciences

Volume 32, Issue 9, 28 February 1983, Pages 1031-1036

https://doi.org/10.1016/0024-3205(83)90935-9 Get rights and content

Abstract

A new benzothiophene derived antiestrogen, LY139481, inhibited the uterotropic action of estradiol in a dose related fashion, and at 1 mg per day suppressed more than 90 percent of estradiol's activity in immature rats. LY139481 induced minimal uterotropic activity, and that activity declined in relation to dose. The relative binding affinity of LY139481 for rat uterine cytosol estrogen receptors was greater than that of estradiol in competitive assays and increased in relation to temperature (2.9 ± 0.5 × estradiol at 30° C). LY139481 caused estradiol-induced uterine hypertrophy to regress in a manner similar to that which resulted from withdrawal of estradiol treatment. Three successive daily injections of LY139481 slightly increased uterine weight, and blocked additional uterotropic action in response to estradiol and LY139481 administration on subsequent days. Furthermore, ten daily injections of estradiol alone did not increase uterine weight in animals pretreated with LY139481 for three days. In contrast, LY139481 did not prevent the partial uterotropic action of tamoxifen administration.

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Antagonism of estrogen action with a new benzothiophene derived antiestrogen

Abstract

Rec. Prog. Horm. Res.

Life Sci.

Mol. Cell Endo.

J. Reprod. Fert.