The Conversion of Testosterone to 5 ~-Androstan-17~-ol-3-one by Rat Prostate in Viwo and in Vitro*

The identity of the nonpolar transformation products of testosterone-1,S3H, the time course of the appearance of these metabolites in various tissue compartments, and the subcellular distribution of testosterone and its metabolites in prostate have been investigated following the intravenous administration of the hormone to normal and to functionally hepatectomized rats. Evidence has been obtained in both types of animals that within 1 min following its administration testosterone is taken up by the prostate, and at least 90% is converted to three products, androstandiol, dihydrotestosterone, and androsterone. From prostatic nuclei, however, only testosterone-3H and dihydrotestosterone-3H were recovered for as long as 2 hours following testosterone injection. Furthermore, it has been shown that in the presence of a NADPHz-generating system prostatic nuclei convert testosterone to dihydrotestosterone, whereas prostatic cytoplasm, in addition, reduces dihydrotestosterone to androstandiol. The nuclear enzyme which performs this reaction has been partially characterized and appears to be located within the chromatin. Finally, the tissue distribution of dihydrotestosterone-3H has been investigated at a short time interval following testosterone-l ,2-3H injection; this metabolite was detected only in prostate, seminal vesicle, preputial gland, kidney, and plasma.