Resveratrol: phytoestrogen effects on reproductive physiology and behavior in female rats

Resveratrol is a phytoestrogen naturally found in grapes and is a major constituent of wine thought to exert both cardioprotective and chemopreventive activities. Recent studies show that this bioflavonoid binds to and activates gene transcription via the estrogen receptor (ER) subtypes ERalpha and ERbeta. Previous studies have focused primarily on the in vitro effects of resveratrol (RES) in estrogen-sensitive tissues or in carcinogenic cell lines, while frequently neglecting to document its potential effects in animal models with intact neuroendocrine systems. However, the present studies were designed to systematically characterize the in vivo effects of RES on reproductive physiology and behavior in adult female rats. In gonadally intact females, RES consumption reduced body weight, disrupted estrous cyclicity, and induced ovarian hypertrophy. However, in ovariectomized females RES (10-1000 microg) injections did not appear to mimic 17 beta-estradiol benzoate (EB)-induced behavioral responses and had no lasting effects on subsequent estrogen sensitivity or sociosexual behavior. The present studies support recent in vitro findings that RES differs from other phytoestrogens by acting as a possible mixed agonist/antagonist, depending on the availability of specific ER isoforms localized in the reproductive tract and brain of the female rat.