Efeitos do tamoxifeno e dos estrogênios conjugados no epitélio mamário de ratas em estro permanente Effects of tamoxifen and conjugated estrogens on the mammary epithelium of rats in persistent estrus

Objetivo: avaliar as alterações morfológicas e morfométricas produzidas pelo tamoxifeno e pelos estrogênios conjugados no epitélio mamário de ratas em estro permanente. Métodos: foram utilizadas 33 ratas adultas, induzidas a estro permanente com 1,25 mg de propionato de testosterona e divididas ao acaso em três grupos: GI -- que receberam apenas água, servindo como controle (n = 12); GII -- tratadas com 500 mig de tamoxifeno diariamente (n = 10); GIII -- tratadas com 30 mig de estrogênios conjugados ao dia (n = 11). O primeiro par mamário abdômino-inguinal dos animais foi extirpado e processado para estudo morfológico e morfométrico. Os dados foram analisados estatisticamente pela análise de variância por postos de Kruskal-Wallis (p 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