Deoxyribonucleic Acid and Polyamine Synthesis in Rat Ventral Prostate EFFEC S OF AGE OF THE INTACT RATAND ANDROGEN STIMULATION OF THE CASTRATED RAT WITH TESTOSTERONE, 5a-DIHYDROTESTOSTERONE AND 5a-ANDROSTANE-3fl,17f8-DIOL

The relationship between polyamine synthesis, growth and secretion in vivo was examined in ventral prostates from: (a) intact rats aged 3-60 weeks; (b) animals castrated for 7 days before injection with 5r-dihydrotestosterone (17,8-hydroxy-5a-androstan-3-one), testosterone and 5 r-androstane-3,8,17,f-diol for up to 10 days; (c) rats injected with the 3fi,17fidiol immediately after castration. Ornithine decarboxylase activity and the concentrations of putrescine, spermidine and spermine were measured. DNA-synthetic activity was monitored by measuring [1251]iododeoxyuridine incorporation. An enhanced spermidine/ spermine molar ratio reflected increased activity ofthe prostate. The ratio was higher (>2) in prostates from sexually immature animals, than in the intact adult (1.5), suggesting that the ratio was indicative ofthe proliferative activity ofthe tissue. However, in the androgenstimulated castrated rat, enhanced spermidine/spermine ratios tended to correlate with hypertrophy and secretion. In both sets of experiments there was a linear relationship between protein and spermidine content. High spermidine/spermine molar ratios were the consequence ofa relatively low rate ofaccumulation of spermine relative to spermidine and protein. The relationship between polyamine synthesis and DNA-synthetic activity was investigated in cultured prostate. A combination of insulin (3 ug/ml) and testosterone (0.1 jUM) caused a stimulatory response in the incorporation of [1251]iododeoxyuridine and in cell division, despite a depleted polyamine content and low ornithine decarboxylase activity in the cultured tissue.