Inhibition of Extratesticular Stimuli to Prostatic Growth in the Castrate Rat by Antiandrogens

In the immature castrate rat, the antiandrogens cyproterone (C) (30 or 150 mg⁄ kg) and cyproterone acetate (CA) (10 or 50 mg⁄kg) inhibited the growth of the ventral prostate and seminal vesicles that was induced by dehydroepiandrosterone (DHA), androstenedione (A), or testosterone (T) injected at various doses for 7 days. When the lowest doses of androgen were used (DHA 0.4 mg, A 0.02 mg, and T 0.015 mg), C and CA were often able to maintain the weights of target organs at castrate levels. CA was about 3 times more potent than C in antiandrogenic activity. CA also significantly inhibited the increase in prostatic weight that occurred after 14 days of administration of ACTH (20 U⁄day), prolactin (1 mg⁄day) plus ACTH (5 mg⁄day), or prolactin (1 mg⁄day) plus DHA (0.2 mg⁄day). It is concluded that C and CA can inhibit the known extratesticular stimuli to prostatic growth in the rat. These stimuli may all be mediated by an androgendependent cellular response. (Endocrinology87: 624, 1970)