Dietary quercetin does not affect pituitary lutenizing hormone (LH) expression and has no uterotropic effects in ovariectomized Sprague-Dawley rats

Introduction: The aim of this study was to investigate the potency of LH suppression and the uterotrophic effects of quercetin, a flavonoid widely present in our diet which in vitro has been shown to posses estrogenic properties. Methods: Fifty-nine female Sprague-Dawley (SD) rats were ovariectomized (ovx) and fed with soy-free rodent chow with the addition of quercetin or estradiol-3 benzoate (E2B). Quercetin was added to the rodent chow at the dose of 200 mg/kg (n = 12) and 1000 mg/kg (n = 11) which on average corresponded to 3.55 mg and 18.42 mg per animal per day, respectively, and E2B at the dose of 4.3 mg/kg (n = 12) or 17.3 mg/kg (n = 12) which corresponded to 0.07 mg and 0.20 mg per animal per day, respectively. The control group (n = 12) received soy-free chow only. After three months of treatment, animals were sacrificed and using real time RT-PCR, pituitary LH beta and uterine insulin like growth factor (IGF)-1, progesterone receptor (PR) and complement 3 protein (C-3) mRNA levels were measured. Additionally, the in vitro binding capacity of quercetin with a porcine cytosolic ER preparation was evaluated. Results: In contrast to E2B, dietary quercetin did not decrease pituitary LH expression, had no effects on uterine weight and uterine expression of estrogen regulated genes. The binding capacity of quercetin with the ERs was also 35000-fold lower compared with 17 beta-estradiol (E2). Conclusion: Our study shows that quercetin does not show any estrogenic effects in the pituitary and the uterus of the ovx SD rats. (C) 2007 Elsevier Ltd. All rights reserved.