The actions of prolactin, insulin and cortisol on the conversion of testosterone to dihydrotestosterone in the cultured rat ventral prostate were examined in conditions in which they have been demonstrated to act synergistically with testosterone on the macromolecule synthesis of the prostate. On the other hand oestradiol, progesterone and cyproterone were tested similarly in conditions where they have been shown to be effective antiandrogens.
The metabolism of testosterone to dihydrotestosterone was found to be extremely rapid and approximately 70 % of the radioactive steroids in the tissue was dihydrotestosterone from 5 min onwards, but only insignificant amounts of dihydrotestosterone were found in the culture medium during the first hour. Physiological concentrations of the synandrogens did not alter the metabolism of testosterone or the accumulation of the steroids into the tissue. Oestradiol, progesterone and unlabelled testosterone in a 500-fold concentration markedly reduced the conversion of tritiated testosterone to dihydrotestosterone while cyproterone and dihydrotestosterone had no effect. The possible role of other hormones in the alteration of testosterone metabolism in the target organs as the mechanism of synandrogenic or antiandrogenic action is discussed.