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Updated: Jan 24, 2026

Visualization of Estrogen Receptors in Colons of Mice with TNBS-Induced Crohn's Disease using Immunofluorescence
Published on: March 12, 2020
Estrogen-prolactin dependency in 7,12-dimethylbenz(a)anthracene-induced tumors
Abstract:
Hormonal influences on dimethylbenz(a)anthracene-induced tumor growth were investigated in detail by endocrine ablation and replacement of hormones. The majority of tumors regressed following ablation and most of them were reactivated by subsequent administrations of estrogen (0.1 to 5 mug) or prolactin (2 mg). Increasing numbers of tumors, however, were not stimulated by prolactin when administration was delayed, and a basal level of estradiol (0.01 mug) in addition to prolactin was required for reactivation of tumors. Nafoxidine hydrochloride, a competitor of estrogen at the receptor sites, arrested growth of a large portion of dimethylbenz(a)anthracene-induced tumors in intact animals but failed to retard growth of prolactin-stimulated tumors. On withdrawal of prolactin-nafoxidine, rapid regression of tumor occurred and readministration of prolactin failed to activate most of the tumors for as long as 28 days. Our results give good supporting evidence that estrogen plays a primary role in tumor growth. The interactions of prolactin and estrogen at tumor sites are necessary for regulatory events related to tumor growth.
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