Binding of synthetic anabolic steroids to testosterone-estradiol binding globulin and to rat prostate cytosol.

The binding of five synthetic anabolic steroids and two natural androgens to testosterone-estradiol binding globulin (TeBG) and to cytoplasmic fraction containing androgen receptors from prostates of castrated rats was compared. The binding affinity to TeBg decreased in sequence: dihydrotestosterone--testosterone--methyltestosterone-methandienone--nortestosterone--dimethylandrostanolone--nortestosterone--phenylpropionate (no binding); in the prostatic cytosol the following fecreasing sequence was found: dihydrostestosterone--methyltestosterone--methandienone--nortestosterone--nortestosterone phenylpropionate--testosterone--dimethylandrostanolone. The law binding to TeBG of 17alpha-methylated steroids possessing at the same time high affinity to cytoplasmic receptors may enhance their effect in target tissues.