Testosterone 5 alpha-reductase activity as related to proliferative status in mouse accessory sex glands

Testosterone 5 alpha-reductase activity has been measured during the proliferative response of the seminal vesicle and coagulating gland of the castrated mouse after continuous treatment with tesotsterone. Daily subcutaneous injections were begun either 3 or 14 days after castration. At 3 days after castration, a pre-replicative period of 50-60 h occurred before the onset of DNA synthesis, and a continuous [3H]thymidine labelling procedure revealed that only a minority of epithelial cells were subsequently involved in the transitory proliferative response. At 14 days after castration, cells were able to prepare more quickly for DNA synthesis (20-30 h), and the subsequent proliferative response involved a higher proportion of the epithelial cells present. At 14 days after castration, testosterone treatment resulted in the activity of the enzyme/mg homogenate increasing fourfold in the seminal vesicle and tenfold in the coagulating gland, to values almost double those of control (intact animals. At 3 days after castration, testosterone treatment resulted in much slower increases in enzyme activity, and at the completion of day 5 of treatment, levels were close to control values. It is concluded that a relationship may exist between the initial increase in 5 alpha-reductase activity and the duration of the pre-replicative period before DNA synthesis begins. Although testosterone and its resultant effects upon 5 alpha-reductase activity are clearly implicated in the genesis of the proliferative response, the ultimate control of cell proliferation must be independent of androgenic hormones. When cell division was effectively curtailed at the completion of day 4 of testosterone treatment, abnormally high levels of enzyme activity were still present.