Androgen and estrogen receptors in rat ventral prostate epithelium and stroma

Estrogen and androgen receptors have been investigated in rat ventral prostate epithelium and stoma. High speed supernatants were prepared from unfractionated or fractionated prostates. Cytosols from intact rats were incubated with 2 nM 3H-estradiol (E2) in presence of 80 nM dihydrotestosterone (DHT), and cytosols from 1 day castrated rats were incubated with 2 nM 3H-DHT, at 0 C for 4 h. They were submitted to ultracentrifugation on glycerol-Tris gradients. The amounts of hormones bound to the saturable 8S binding components were determined on a comparative basis. The values for E2-receptor in intact rats were 2.3, 15.4 and 5.9 fmol/mg cytosol protein in unfractionated prostate, stroma and epithelium, respectively. The corresponding values for DHT-binding were 31.9, 17.2 and 29.2 fmol/mg protein. In addition, Scatchard analysis of saturable E2 and DHT binding, using the protamine precipitation technique, essentially confirmed the results of glycerol gradients, and led to the conclusion that, contrary to androgen receptor, the major part of estradiol receptor is localized in stroma.