Soybean concentrated extract counteracts oxidative stress in the uterus of rats

To evaluate the effects of soy isoflavone extract in the pro-oxidant/antioxidant balance in the uterus of ovariectomized rats.

Twenty 3-month-old adult female Wistar rats were divided into four equal groups: GI: sham-operated (estrous phase); GII: control ovariectomized rats; GIII: ovariectomized rats treated with genistein (50 μg/kg/day) by gavage; GIV: ovariectomized rats subcutaneously treated with estrogen (10 μg/kg/day). After 30 consecutive days of treatment, the rats were euthanized and the uterus removed. The distal thirds of the uterine horns were processed for histomorphometric analyses of endometrial and myometrial thicknesses and glandular area. Other regions of the uteri were kept in liquid nitrogen and subsequently processed for analysis of reactive species quantification (DCF), total antioxidant capacity (TAC) and lipid oxidation status (TBARS). Data were statistically analyzed by one-way ANOVA, complemented by the Tukey-Kramer test (p < 0.05).

GII and GIII exhibited lower endometrial thickness, glandular area and myometrial thickness than GI and GIV, while a higher myometrial thickness was observed in GIV compared with the other groups. Moreover, the isoflavone-treated group showed lower DCF and TBARS compared to GII, and also an improvement of TAC compared to GI and GIV. Despite the significant decrease in TBARS, no significant difference in DCF nor a decrease in TAC were observed in GIV when compared to GII.

Our data show that isoflavones improve antioxidant status and counteract oxidative stress, without promoting a trophic effect in the uterus of rats.