EXPRESSION OF ESTROGEN-RECEPTOR-BETA (ER-BETA) IN MULTIPLE RAT-TISSUES VISUALIZED BY IMMUNOHISTOCHEMISTRY

Steroid hormones regulate cell function via specific receptors, member s of a super family of ligand activated transcription factors, express ed in their target tissues. A second oestrogen receptor (ER beta) has recently been shown by RT-PCR to have a wide tissue distribution disti nct from that of oestrogen receptor alpha (ER alpha). We have raised a polyclonal antiserum using a peptide specific for ER beta in order to determine the cellular sites of expression of the receptor. In the ad ult rat ER beta was localised to cell nuclei in a wide range of tissue s including ovary, oviduct, uterus, lung, adrenal, seminal vesicle, bl adder, heart, prostate and testis. In the ovary ER beta was present in multiple cell types including granulosa cells in small, medium and la rge follicles, theca and corpora lutea whereas ER alpha was undetectab le in these cell types. In the uterus ER beta and ER alpha were both p resent in epithelial cells lining the lumen and glands. In the lung ER beta was present in the cells lining the bronchioles and alveoli as w ell as in smooth muscle. In bladder and seminal vesicle immunostaining was intense in epithelial cells but the receptor was also expressed i n nuclei of smooth muscle cells. Cell nuclei of the heart ventricle we re immunopositive for ER beta as were most cells of the adult rat adre nal. In the seminiferous epithelium of the testis, nuclei of Sertoli c ells were immunopositive but expression was not stage dependent. In co nclusion, immunohistochemistry has proved invaluable in visualising sp ecific sites of expression of ER beta in complex tissues including tho se of the reproductive tract.