Disparate Effect of Tamoxifen in Rats with Experimentally Induced Endometriosis*

R Kadaba, C. Wayne Simpson, C W Simpson
Endocrinology · 1990 · vol. 126(6) , pp. 3263–3267 · doi:10.1210/endo-126-6-3263 · PMID:2351116 · W2001650297
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Tamoxifen treatment induced regression of experimentally induced endometriosis implants in rats, but their recurrence was observed upon withdrawal or co-administration with estradiol, while progesterone blocked recurrence.

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Abstract

The effect of tamoxifen on the growth of endometrial implants was examined in rats with experimentally induced endometriosis. Administration of tamoxifen (1 mg/kg x day) for 60 days completely regressed the endometrial implants. When tamoxifen treatment was withdrawn, recurrence of endometrial implants was observed. Ectopic endometrial implants regressed completely 2 months after ovariectomy in rats with experimentally induced endometriosis. Tamoxifen administration (1 mg/kg x day) for 60 days to ovariectomized rats with regressed implants led to complete recurrence of ectopic endometrial implants. In ovariectomized rats administration of tamoxifen antagonized estradiol-enhanced thymidine incorporation into uterine DNA, but tamoxifen per se stimulated thymidine incorporation. This indicates the agonist/antagonist nature of tamoxifen. Treatment of rats with tamoxifen blocked the normal estrous cycle. However, serum progesterone levels were higher during tamoxifen treatment in rats with intact ovaries than in ovariectomized rats. When ovariectomized rats with regressed implants were administered tamoxifen (1 mg/kg x day) and progesterone (10 mg/kg x day) for 60 days, recurrence of ectopic endometrial implants was not observed. These findings suggest that tamoxifen is effective in regressing endometrial implants in rats with experimentally induced endometriosis, and ovarian progesterone may have a facilitatory effect.

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Condition tags

mesh:D004715endometriosis

MeSH descriptors

Disease Models, Animal Endometriosis Tamoxifen Animals DNA DNA Endometriosis Endometriosis Endometrium Endometrium Estradiol Estradiol Estrus Estrus Female Ovariectomy Progesterone Progesterone Rats Rats, Inbred Strains

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References (16)

Cited by (8)

SciLite annotations

chemicals 18
tamoxifen tamoxifen tamoxifen tamoxifen tamoxifen tamoxifen estradiol thymidine tamoxifen thymidine tamoxifen tamoxifen progesterone tamoxifen tamoxifen progesterone tamoxifen progesterone
organisms 8
rattus sp. rattus sp. rattus sp. rattus sp. rattus sp. rattus sp. rattus sp. rattus sp.

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