Effect of ethanol feeding upon levels of a male-specific hepatic estrogen-binding protein: a possible mechanism for feminization.

Male, but not female, rat liver cytosol contains an estrogen-binding protein with unique properties: rapid binding of estradiol, high binding capacity, moderate affinity for estradiol, and specificity for steroidal estrogens and weak androgens, but not for nonsteroidal estrogens or other steroids. The estradiol-binding activity of this protein is reduced in cytosol from livers of alcohol-fed rats as compared to that from their isocalorically fed controls. The properties of this male-specific hepatic estrogen-binding protein suggest a role for this protein in the regulation of estrogen levels in the male animal. Moreover, the reduction in activity of this unique protein in the liver of alcohol-fed animals may explain, at least in part, the feminization commonly seen in chronic alcoholic men.