The effects of soy extract on the uterus of castrated adult rats

Abstract

Objective: the aim of this study was to evaluate the effects of different doses of a standardized soy extract on the uterus of castrated rats.Methods: Fifty-six adult castrated female Wistar rats were randomly divided into seven groups (eight animals in each) that received: GI-drug vehicle (propylene glycol); GII-soy extract 10mg/kg per day; GIII-soy extract 50mg/kg per day; GIV-soy extract 100mg/kg per day; GV-soy extract 300mg/kg per day; GVI-soy extract 600mg/kg per day; GVII-conjugated equine estrogens (CEE) 200 mu g/kg per day. After 21 days of treatment, all animals were sacrificed and fragments of the uterine horns were immediately removed, fixed in 10% formaldehyde and submitted to routine histological techniques for morphometric study. the endometrial cell proliferation index was determined with the PCNA antibody PC-10 and expressed as the percentuals of the PCNA-positive nuclei relative to the total countings. Other fragments were immediately frozen in liquid nitrogen for RNA extraction and VEGF analysis using RT-PCR technique.Results: the minimal dose of soy extract that produced a significant increase of the morphometric parameters was 100 mg/kg (GIV). the maximum effects on endometrial and myometrial morphometry were detected in the groups treated with 300 and 600 mg/kg of soy extract (groups V and VI) and CEE (GVII). the expression of PCNA in the endometrial epithelium and stroma was increased by treatment with 100-600 mg/kg per day of soy extract (groups IV-VI) or with CCE (group VII). Doses equal to or higher than 50 mg/kg of soy extract (groups III-VI) and CEE stimulated the expression of VEGF.Conclusion: the treatment of adult castrated rats during 21 days with doses of 100 mg/kg per day or higher of soy extract may determine significant proliferation in the endometrium and myometrium. (c) 2006 Published by Elsevier Ireland Ltd.