Purpose: to evaluate the morphologic and morphometric alterations produced by tamoxifen and conjugated estrogens in the mammary epithelium of rats in persistent estrus. Methods: thirty-three adult female rats in persistent estrus induced with 1.25 mg testosterone propionate were divided at random into three groups: GI -- which received only water, control group (n = 12); GII -- treated with 500 mug tamoxifen daily (n = 10); GIII -- treated with 30 mug conjugated estrogens per day (n = 11). The first inguinal-abdominal pair of mammary glands of the animals was extirpated and processed for morphologic and morphometric study. Data were analyzed statistically by the Kruskal-Wallis rank analysis of variance (p < 0.05). Results: the morphologic study revealed signs of epithelial atrophy and the morphometric study showed a statistically significant reduction in the 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 group I (25.0 and 6.6, respectively). There was no significant difference between groups II and III. Conclusions: the results of this study indicate that tamoxifen as well as conjugated estrogens at the tested doses produced mammary epithelial atrophy in rats in persistent estrus.
Normal breast; Hormonal replacement therapy; Antiestrogens
