Localization and regulation of estrogen, progestin and androgen receptors in the seminal vesicle of the rhesus monkey

We have used monoclonal antibodies against the estrogen (E), progestin (P) and androgen (A) receptors (R) to study receptor localization and regulation in the seminal vesicles of rhesus monkeys under different hormonal conditions. The antibodies caused substantial shifts of the appropriately labeled receptors on sucrose gradients. ER levels were lower in intact males than in immature, castrate, and estrogen-treated castrates. With immunocytochemistry, ER were detectable only in stromal and smooth muscle cells, not the epithelium. The number of ER-positive stromal cells was significantly lower in intact males than in immature, castrate, and estrogen-treated castrates, and low in a DHT-treated castrate animal. Androgen receptors were localized in epithelial as well as stromal and smooth muscle cells, and the number of AR-positive stromal cells was highest in intact adults and lowest in castrated and immature animals. Estrogen treatment at the time of castration induced PR in the ER-positive stromal cells, prevented a decline in the number of AR-positive stromal cells, and caused stromal hypertrophy. In summary, in the seminal vesicle, as in the prostate, ER is restricted to the fibromuscular stroma, is suppressed by androgens, and can mediate induction of PR on estrogen treatment. Androgen receptors are present in epithelial as well as stromal and smooth muscle cells, but variations in hormonal state appear to affect regulation of AR more in the stroma than the epithelium.