Proliferative response of seminal vesicle cells to androgen and estrogen in neonatally castrated mice.

Proliferation and death of androgen- and estrogen-responsive cells in seminal vesicles were compared between neonatally and adult (on Day 60 after birth) castrated mice. Daily injections of either testosterone propionate (TP) or estradiol-17 beta (E2) were started on Day 90 after birth; the incorporation of 5-[125I]iodo-2'-deoxyuridine ([125I]IdUrd) into the whole seminal vesicles was used as an index for proliferation. Although the peak of [125I]IdUrd uptake was observed 3 days after starting TP injections in both neonatally and adult castrated mice, the peak was lower and the period of proliferation was much longer in the former than in the latter. When TP injections were stopped, the fraction of surviving cells that synthesized DNA on Day 3 of TP injections was much larger in neonatally than adult castrated mice. The difference was attributed to the presence of TP-induced proliferation of fibromuscular cells in the neonatally castrated mice but not in the adult castrated mice; only the fibromuscular cells but not epithelial cells survived after stopping TP injections. Although injections of E2 increased the proliferation of epithelial cells but did not the weight of seminal vesicles in adult castrated mice, the same procedure increased the proliferation of both epithelial and fibromuscular cells and the weight in neonatally castrated mice. The E2-induced fibromuscular cells seemed to survive in the presence or absence of E2. The present results seem to indicate that androgen- and estrogen-induced proliferation of fibromuscular cells is irreversible in seminal vesicles of neonatally castrated mice and that the depletion of androgen in the seminal vesicle during neonatal and prepubertal periods is at least in part compensated by the administration of androgen, even after 90 days of age.