Estudo morfológico e molecular da mama de ratas castradas tratadas com isoflavona ou estrogênios Morphological and molecular effects of isoflavone and estrogens on the rat mammary gland

Abstract

OBJETIVO: avaliar os efeitos das isoflavonas e dos estrogênios sobre a morfologia, a morfometria e a expressão do fator de crescimento vascular (VEGF) na mama de ratas adultas. MÉTODOS: Quarenta e cinco ratas, após 28 dias de ooforectomia, foram divididas em três grupos: CON - controle e os grupos que receberam medicação: ISO - isoflavona (100 mg/Kg) e ECE - estrogênios conjugados eqüinos (50 µg/Kg). Após 60 dias, parte das mamas foram fixadas em formol a 10% para processamento histológico, e outra parte congelada para a análise da expressão do VEGF pela técnica da reação em cadeia da polimerase com transcrição reversa (RT-PCR). Para análise dos resultados obtidos foram utilizados inicialmente a análise de variância (ANOVA). Quando houve significância, foi complementada com o teste de comparações múltiplas de Tukey-Kramer. RESULTADOS: Nos grupos CON e ISO as mamas apresentaram glândulas mamárias atróficas, sendo mais desenvolvidas no grupo ECE, onde se notou a presença de inúmeros ductos e de alvéolos mamários. A morfometria mostrou maior número de alvéolos no grupo ECE (12,3 ± 7,1* por mm²; pPURPOSE: to analyze the effects of isoflavones and estrogens on the morphology, morphometry and VEGF expression of the adult female rat mammary gland. METHODS: Forty-five adult female rats were oophorectomized; 28 days after surgery they were divided into 3 groups of 15 animals each: CON - control (treated with propylenoglycol); ISO - isoflavones (100 mg/kg) and CEE - conjugated equine estrogens (50 µg/Kg). Drugs or vehicle were given orally once a day for 60 days. After this, the animals were killed and the first pair of inguinal mammary glands was immediately removed; part of the material was processed for routine histological study and the remaining tissue was frozen for further analyses of the expression of VEGF mRNA by means of the RT-PCR technique. RESULTS: We observed that mammary ducts were atrophic in the control (CON) and isoflavone-treated (ISO) groups. In these groups the mammary glands were composed of a large concentration of adipose tissue with some ducts and rare alveolar structures. In the CEE group the ducts were well developed with many buds and alveolar structures. The number of mammary gland alveoli was higher in CEE than in the other groups (CON = 1.4 ± 2.1; ISO = 1.6 ± 3.8; CEE = 12.3 ± 7.1 alveoli/mm²; p<0.05%); also, the cell volume was higher (CON = 14.9 ± 4.9; ISO = 11.4 ± 6.9; CEE = 27.4 ± 9.7 µm³, p< 0.05%). The same was observed with regard to the number of blood vessels (CON = 16.4 ± 1.5; ISO = 18.4 ± 2.1; CEE = 37.1 ± 4.1 vessels/mm², p< 0.05). The expression of VEGF in the CEE group was higher than in the other groups, which did not significantly differ from each other in this respect. CONCLUSION: Our data did not show any proliferation effect in the mammary tissue of adult oophorectomized rats treated with isoflavones (100 mg/kg) during 60 days.

Keywords

• Mama
• Estrógenos
• Isoflavona
• Morfologia
• Ratos
• Breast
• Estrogens
• Isoflavone
• Morphology
• Rats