[An unusual estrogen-binding liver protein and the dynamics of sex steroids: estrogen stimulation of testosterone metabolism in the male rat in vivo].

A study was made of the influence of estrogens on the nature of 3H-testosterone metabolism in the liver of male and female rats. Estradiol stimulation of intensity and modulation of character of testosterone metabolism in the liver of male rats were demonstrated by thin layer chromatography. A simultaneous increase in the level of radioactivity of testosterone and its metabolites was noted in the liver and blood serum. The role of the unusual estrogen binding protein (UEBP) as a mediator in this estradiol action was demonstrated by the hormonal specificity of the efficacy of estrogens corresponding to the specificity of their affinity to UEBP. In female rats estradiol inhibited testosterone metabolism. Taking account of the data obtained UEBP possible functions with relation to the regulation of sex steroid metabolism were analysed.