RESUMO
OBJECTIVE: We evaluated whether genistein or estrogen treatment has the same effect when administered immediately or late to rats induced with menopause using ovariectomy. METHODS: Sixty adult female rats were divided into six treatment groups: GI = vehicle immediately after ovariectomy; GII = vehicle 30 days after ovariectomy; GIII = genistein immediately after ovariectomy; GIV = genistein 30 days after ovariectomy; GV = estrogen immediately after ovariectomy; and GVI = estrogen 30 days after ovariectomy. All animals were treated for 30 consecutive days. At the end of the treatment, part of the uteri was removed for subsequent histological studies and another part was used to evaluate estrogen receptors 1 and 2, cell proliferation (cyclin A1 and A2, cyclin D1, cyclin-dependent kinase inhibitors 1, 1B and 2, antigen identified by the monoclonal antibody Ki67) and angiogenesis (vascular endothelial growth factor, VEGF-A) gene expression. RESULTS: Late treatment after castration in rats resulted in more developed endometrium, enhanced cell proliferation and estrogen-signalling pathways, particularly the cyclin-related genes Ki67 and VEGF-A, compared to early treatment. Interestingly, these same effects were less intense with genistein compared to those induced by estrogen, especially when genistein was administered late. CONCLUSION: Our data show that isoflavone renders a lower risk of cancer when compared to estrogen in treatments.
