Localization of oestrogen receptor α, oestrogen receptor β and androgen receptors in the rat reproductive organs

There is now evidence that oestrogens and androgens can influence male and female reproductive systems. In order to accurately identify the sites of action of oestrogens and androgens, we have proceeded to the histological localization of the two oestrogen receptor (ER) subtypes, ER alpha and ER beta, and the androgen receptor (AR) in the reproductive tissues of adult rats of both sexes. AR was detected by immunocytochemistry, while ER alpha and ER beta were localized by both immunocytochemistry and in situ hybridization. In the pituitary gland of animals of both sexes, ER alpha was found in the majority of nuclei of secretory cells in the anterior pituitary. The intermediate and posterior lobes did not show any staining. ER beta was not found to be expressed in any of the pituitary lobes. Using AR antibodies, nuclear staining was detected in about 50% of secretory cells of the anterior lobe, the intermediate and posterior lobes being completely unstained. In the testis, ER alpha was localized in nuclei of Leydig cells as well as in round spermatocytes and spermatids, while ER beta could only be detected in Sertoli cell nuclei. AR immunoreactivity was found in nuclei of Sertoli, peritubular myoid and Leydig cells. In the prostate, ER beta was observed in epithelial cells of tubulo-alveoli, while the stroma was unlabelled. ER alpha was not found to be expressed in any prostate cells. In the prostate, AR was detected in nuclei of epithelial, stromal and endothelial cells. In seminal vesicles, staining of ER alpha was found in nuclei of epithelial and stromal cells. Similar findings were observed using AR antibodies. While ER beta mRNA could not be detected by in situ hybridization, weak staining for ER beta was localized in epithelial cells of seminal vesicles. In the ovary, both ER alpha and ERP were found to be expressed. ER beta mRNA was found in granulosa cells of growing follicles, while ER alpha was present in theca cells, interstitial gland cells and germinal epithelium. AR immunoreactivity was detected in granulosa cell nuclei in growing follicles and also in scattered interstitial cells. In the oviduct and uterus, ER alpha was observed in nuclei of epithelial cells as well as of stromal and muscle cells. Similarly, AR immunoreactivity was present in nuclei of epithelial cells, stromal and muscle cells in both the oviduct and uterus. ER beta was not detected in the oviduct and uterus. The present findings indicate a cell-specific localization of ER alpha, ER beta and AR in reproductive tissues in rats of both sexes. By establishing the precise sites of action of oestrogens and androgens they contribute to a better understanding of the respective role of these steroids in reproduction function.