Bipotentiality of response to sex hormones by the prostate of castrated or hypophysectomized dogs. Direct effects of estrogen.

Prostatic response to administered estradiol-17beta 17-cyclopentylpropionate (ECP) was studied in castrated or hypophysectomized dogs. Ultrastructural investigation identified two types of epithelial cells, squamous and modified glandular, that resulted from estrogen action. Squamous cells, which predominated, appeared to evolve from basal reserve cells. Estrogen-modified glandular cells have features attributable to estrogen and previous androgen stimulation. Thaw-mount autoradiography of explants located radiolabeled estrogen in prostatic epithelium and stroma of normal and ECP-treated animals, suggesting a role of estrogen in prostatic homeostasis. Epithelium from ECP-treated dogs incorporated 3H-thymidine, indicating that estrogen promotes DNA synthesis in these cells. Greatly enhanced conversion of radiotestosterone to 4-androstene-3,17-dione, with sharply decreased formation of 5alpha-reduced hydroxylation products, and attendant elevation in estradiol-17beta oxidoreductase activity are metabolic markers attributable to the induced squamous and responding stromal cells. The duality of prostatic response to sex hormones is apparent from observations that estrogen stimulates regressed glandular epithelium which had undergone androgen-mediated differentiation before ablation.