Effect of Androgen and Aging on Ornithine Decarboxylase Activity of Rat Ventral Prostate

The age-related alteration of androgen dependency in ornithine decarboxylase (ODC) activity was examined in ventral prostate from: (1) intact rats aged 6, 10, 50 and 100W; (2) castrated rats aged 10 and 100W; (3) 10 and 100W rats castrated for 7 days before injection with testosterone propionate for up to 7 days. Tissue dihydrotestosterone (DHT) contents in ventral prostate from intact rats aged 10 and 100W were also measured. ODC activity of rat ventral prostate declined with aging. Castration resulted in rapid decline in ODC activity of young mature rats (l0W) and the activity was restored to normal value by the injection of testosterone propionate. On the other hand, the changes in ODC activity of old rats (100W) induced by castration and androgen replacement were significantly slower than those of young mature rats. In young mature rats, ODC activity was apparently correlated with prostatic DHT contents. Although prostatic DHT contents of old rats retained a similar level to young mature rats, no such correlation between ODC activity and tissue DHT content was observed.
These results showed androgen-sensitive nature of ODC activity. And the sensitivity might be affected by aging at a step by which androgen showed its action.