Estradiol and phytoestrogens differently influence the rodent postmenopausal mammary gland
- 1 January 2006
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Menopause
- Vol. 13 (1), 72-79
- https://doi.org/10.1097/01.gme.0000191208.05491.94
Abstract
Objective: In the following study, we investigated treatment-related changes in mammary gland histomorphology and structure after the administration of soy to adult virgin ovariectomized (OVX) female rats. Additionally, mammary receptor regulation was extensively evaluated by immunohistochemical analysis, and tissue proliferative activity analyzed by cell nuclear proliferating antigen expression (Ki67). Design: OVX rats were treated, for 6 weeks, with either the vehicle, the soy extract (SSE 100 mg/kg/d PO), or 17β-estradiol (0.5 mg/kg/d PO); a sham control group (SHAM) was also included in the study. When killed, mammary glands were collected and subsequently processed for light microscopy or immunohistochemistry. Immunoreactivity was quantified by a scoring system that took into account both the percentage of positive cells and the intensity of the staining. Results: The 17β-estradiol--treated rats had stimulated mammary glands compared with OVX rats, with an average lobulo-alveolar development not different from the SHAM controls. Only a partial regression of the glandular atrophy was observed in OVX rats receiving 100 mg/kg/d SSE, with a histological appearance between that of the OVX and SHAM controls. No significant changes were observed among experimental groups in the median ERα scores of the epithelial compartment (score of 3 in all groups); in the stromal compartment, a tendency toward decreased expression was seen with 17β-estradiol rats compared with OVX controls (scores of 2 and 5, respectively). A significant reduction in ERβ immunostaining was observed in the mammary glands of SSE-treated rats, in both epithelium and stroma (scores of 4 and 3, respectively), compared with those of OVX controls (score of 8 in both compartments). The ERβ receptor status was not significantly affected by 17β-estradiol. Compared with OVX rats (score of 1), PR expression was up-regulated by 17β-estradiol (score of 6), whereas an ovariectomy-like pattern was observed after the administration of SSE (score of 0). Ki67 immunoreactivity in the epithelium and stroma was increased by the administration of 17β-estradiol (scores of 4 and 5, respectively) and was unchanged after SSE treatment (scores of 0 and 2, respectively), compared with OVX controls (scores of 1 and 2, respectively). Conclusions: The differences observed in the histological pattern, hormonal receptor status regulation, and Ki67 modulation suggest a different role for phytoestrogens and 17β-estradiol in postmenopausal rodent mammary glands.Keywords
This publication has 20 references indexed in Scilit:
- Guidelines for the hormone treatment of women in the menopausal transition and beyond: Position Statement by the Executive Committee of the International Menopause SocietyMaturitas, 2004
- Why a consensus conference on hormone replacement therapy and the cardiovascular system?Maturitas, 2004
- Breast cancer and hormone-replacement therapy: the Million Women StudyThe Lancet, 2003
- Estrogen plus Progestin and the Risk of Coronary Heart DiseaseNew England Journal of Medicine, 2003
- Risks and Benefits of Estrogen Plus Progestin in Healthy Postmenopausal Women: Principal Results From the Women's Health Initiative Randomized Controlled TrialJAMA, 2002
- Cardiovascular Disease Outcomes During 6.8 Years of Hormone TherapyJAMA, 2002
- Use of alternative therapies for menopause symptoms: results of a population-based surveyObstetrics & Gynecology, 2002
- Soy for Breast Cancer Survivors: A Critical Review of the LiteratureJournal of Nutrition, 2001
- Postmenopausal Hormone-Replacement TherapyNew England Journal of Medicine, 2001
- Dietary Isoflavones: Biological Effects and Relevance to Human HealthJournal of Nutrition, 1999