Clinical effects of a standardized soy extract in postmenopausal women

Magnetic resonance spectroscopic comparison of the effects of resveratrol (3,4',5-trihydroxy stilbene) to conjugated equine estrogen, tibolone and raloxifene on ovariectomized rat brains

OBJECTIVE

To investigate the effects of resveratrol on basic cerebral metabolites of in the brains of ovariectomized rats.

MATERIALS AND METHODS

Twenty-four bilaterally ovariectomized rats were randomly assigned into six groups with four rats in each group. The groups consisted of sham-operated (control), ovariectomized, resveratrol, conjugated equine estrogen (CEE), tibolone and raloxifene treated rats. Drug administration started at the 5th day following ovariectomy and continued for 35 days. At the end of the entire course, in vivo single voxel magnetic resonance spectroscopy was performed on whole brains to determine choline, creatine and N-acetyl aspartate (NAA) concentrations.

RESULTS

Compared to sham-operated group, ovariectomized group had significantly lower NAA (P<0.008) but significantly higher choline levels (P<0.031). Administration of CEE and resveratrol resulted in NAA levels that were similar to those in the sham-operated group, showing that the NAA decrease due to ovariectomy was prevented. Treatment with tibolone and raloxifene resulted in a smaller increase in NAA and the effect failed to reach significance. Administration of resveratrol, CEE, tibolone and raloxifene resulted in choline levels similar to those in sham-operated group, showing that the increase in the ovariectomy group was prevented.

CONCLUSION

Resveratrol causes levels of cerebral metabolites that is similar to conventional hormone replacement agents. This finding may suggest that neuronal function in the postmenopausal state was preserved. More detailed investigation of this issue should be the task of future research.

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.