Antagonistic effect of androgen on prostatic cell death.

Androgen, besides having the well-established agonistic ability to stimulate prostate cell proliferation, also has an antagonistic ability to inhibit prostatic cell death. This statement is based upon the observations that 1) only 2.1% of the total prostatic cells die per day when serum testosterone level is sufficient for chronic maintenance of the gland; 2) 3 days following castration, when serum testosterone level is less than 10% of the intact value, the percentage of total prostatic cells now dying per day is increased tenfold to a value of 20.8%; and 3) this high rate of prostatic cell death can be inhibited following castration if serum androgen level is appropriately maintained by exogenous testosterone treatment. The serum testosterone level needed to antagonistically inhibit prostatic cell death (ie, 1.4 +/- 0.1 ng/ml) is more than twofold lower than that needed to antagonistically stimulate prostatic cell proliferation (3.3 +/- 0.4 ng/ml). Due to this dose difference, it is experimentally possible in castrated rats to inhibit prostatic cell death selectively without simultaneously stimulating cell proliferation and still completely prevent the rapid involution of the prostate following castration. These results suggest that the rapid involution of the prostate following castration is predominantly due to a decreased antagonistic effect of androgen on prostatic cell death rather than to a decreased agonistic effect of androgen on prostatic cell proliferation and that these two androgenic effects are distinct processes in the prostate.