Heterogeneity in mouse seminal vesicle epithelial cells responding to androgen as evaluated by incorporation of [125I]iododeoxyuridine.

When the uptake of 5-[125I]iodo-2'-deoxyuridine ([125I]IdUrd) into the seminal vesicle of castrated mice was measured 3 days after starting injections of various doses of testosterone propionate (TP), logarithmic values of [125I]IdUrd uptake were proportional to the logarithmic doses of TP in the range of 0.04-2 micrograms/g BW. The [125I]IdUrd uptake values correlated well with the labeling and mitotic indices of epithelial cells. Since daily injections of 0.4 microgram TP/g BW did not increase significantly the weight or DNA content or protein content of the seminal vesicle, the [125I]IdUrd uptake is a sensitive index of androgen action. Moreover, this suggests that low doses of androgen induce division of epithelial cells without resulting in the increase in cell number. The [125I]IdUrd radioactivity in the seminal vesicle was measured 2-15 days after the injection of [125I]IdUrd, since the value represented the fraction of surviving cells synthesizing DNA at the time of [125I]IdUrd injection. When injections of 4 micrograms TP/g BW were continued, the incorporated radioactivity was retained. In contrast, continuous injections of 0.2 microgram TP/g BW did not maintain the radioactivity, of which incorporation was induced by the same dose of TP. Thus, the present result suggests the presence of heterogeneity in androgen-responsive epithelial cells of the seminal vesicle.