Santos MA, Florencio-Silva R, Teixeira CP, Sasso GRDS, Marinho DS, Simões RS, Simões MJ, Carbonel AF. Effects of early and late treatment with soy isoflavones in the mammary gland of ovariectomized rats.
Climacteric 2015;
19:77-84. [PMID:
26606166 DOI:
10.3109/13697137.2015.1094783]
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Abstract
INTRODUCTION
Soy isoflavones have been shown to be an alternative to hormone therapy at menopause, without causing side-effects such as breast cancer. However, the effects of early and late treatment with isoflavones on the mammary gland remain controversial.
OBJECTIVE
To investigate the effects of early and late treatment with soy isoflavones on the mammary gland of ovariectomized rats.
METHODS
Thirty 3-month-old rats were ovariectomized and divided equally into groups: Control, treated with vehicle solution; or with 150 mg/kg/body weight of isoflavones by gavage; or subcutaneously treated with 10 μg/kg/body weight with 17β-estradiol. Treatments started 3 days (early treatment) or 30 days (late treatment) after ovariectomy and lasted for 30 consecutive days. Thereafter, the animals were euthanized and the mammary glands were removed and processed for paraffin embedding. Sections were stained with hematoxylin and eosin for histomorphometry or subjected to immunohistochemical detection of Ki-67 and VEGF-A.
RESULTS
The ductal, lobular and total epithelial fractions were similar between controls and the early/late isoflavone groups, but they were significantly higher in the groups treated with estradiol. In both epithelial and stromal regions, the immunoreactivity of VEGF-A and the percentage of Ki-67-positive cells were significantly higher in the groups treated with estradiol, while they were similar in the early/late isoflavone groups and control groups.
CONCLUSION
Our results indicate that early and late treatment with soy isoflavones at the dose of 150 mg/kg/body weight does not show proliferative and angiogenic effects on the mammary gland of ovariectomized rats.
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