BACKGROUND: Soybeans have been widely used to alleviate climacteric symptoms. In this study, we investigated the oestrogenic activities of isoflavones extracted from Aspergillus oryzae-challenged germinated soybeans (AO-GS). Eight-week-old virgin Sprague-Dawley female rats were ovariectomised (OVX). The rats were orally administered 0.1 mg kg(-1) 17α-ethinyl oestradiol or three different doses of AO-GS (0.5, 1.0 2.0 g kg(-1) day(-1)) in distilled water for 6 weeks, while control rats were administered vehicle alone. Uterine weights and levels of oestradiol and testosterone in serum were measured. In addition to serum parameters, bone parameters were also acquired by using micro-computed tomography scanning. RESULTS: Treatments of OVX rats with AO-GS changed the secretory profile of serum oestradiol and testosterone. Serum oestradiol levels were significantly increased in OVX rats treated with and AO-GS (0.5, 1.0, 2.0 g kg(-1) day(-1)), while serum testosterone levels were not significantly increased in OVX rats treated with 1.0 g kg(-1) day(-1) of AO-GS. Furthermore, AO-GS (2.0 g kg(-1) day(-1)) significantly attenuated bone loss, increased trabecular bone volume fraction and trabecular thickness, and significantly decreased trabecular pattern factor. CONCLUSION: AO-GS treatments caused moderate oestrogenic activity in OVX rats compared to those treated with oestradiol, suggesting the potential for the use of AO-GS in the treatment of menopausal symptoms and in osteoporosis caused by oestrogen deficiency.
