Efeitos de altas doses de genisteína sobre o epitélio mamário de ratas

PURPOSE: to evaluate the effects of high doses of genistein on the mammary glands of adult female rats. METHODS: Twenty-eight days after oophorectomy, 50 adult female rats were divided into five groups, as follows: a control group (Ctrl), three rats that received genistein (GEN) at the doses of 46 mg/kg (GEN46;), 125 mg/kg (GEN125) and 250 mg/kg (GEN250); one group received conjugated equine estrogen at the dose of 50 µg/g (ECE50). The substances were administered daily for 30 consecutive days by gavage and in the last week of the period of treatment, colpocytological exams were carried out for seven consecutive days. After treatment, the animals were anesthetized, blood samples were collected for estradiol and progesterone determination and the first pair of inguinal mammary glands was removed and processed for histomorphometric analysis. Collected data were subjected to analysis of variance supplemented by the Tukey-Kramer test (p<0.05). RESULTS: the ctrl group and the ones treated with different doses of GEN showed atrophic mammary glands, whereas the glands were more developed in the ECE group, where numerous mammary ducts and alveoli were observed. Morphometry showed a larger area of mammary parenchyma in the ECE group (98.870.1±550.4 µm2* per mm2; p<0.05) compared with other groups (Ctrl=36.875.6±443.4; GEN46=37.001.7±557.4; GEN125=36.480.8±658.3 and GEN250=37.502.8±669.3). The same occurred in the number of alveoli in the ECE group (33.2±6.9* per mm2; p<0.05) compared to the other groups (Ctrl=10.4±2.1, GEN46=11.2±3.1; GEN125=11.6±2.1 and GEN250=12.3±2.3). The estradiol level was higher in the ECE group compared to the other groups (9.4±1.7 pg/mL; p<0.05), whereas serum levels of progesterone were similar in all groups. CONCLUSION: the administration of genistein at high doses had no trophic effect on the mammary glands of rats.