Purpose: To evaluate the morphological and morphometric alterations produced by tamoxifen and conjugated estrogens in the mammary epithelium of rats in persistent estrus.
Methods: 33 adult female rats with persistent estrus induced by 1.25 mg testosterone propionate were divided at random into three groups: group I (n=12), receiving only water and used as a control; group II (n=10), treated with 500 microg tamoxifen daily; group III (n= 11), treated with 30 microg conjugated estrogens daily. The first abdominal-inguinal pair of breasts was extirpated and processed for morphological and morphometric study. Data were analyzed statistically by the Kruskal-Wallis rank analysis of variance (p<0.05).
Results: The morphological study revealed signs of epithelial atrophy and the morphometric study showed a significant reduction in mean number of ducts and alveoli in groups II (10.1 and 1.9, respectively) and III (11.1 and 3.5, respectively) compared to the control group 1 (25.0 and 6.6, respectively). There was no significant difference between groups II and III.
Conclusions: The present results indicate that, at the doses and during the time of treatment used, both tamoxifen and conjugated estrogens induced atrophy of the mammary epithelium of rats in persistent estrus.