Oestrogen receptor alpha and beta in rat prostate and epididymis

The cellular localization of two oestrogen receptor (ER) subtypes, ER alpha and ER beta, was investigated in neonatal, postnatal, immature and adult m ale rats to determine whether these receptor subtypes are differentially ex pressed in prostate and epididymis. A monoclonal antibody against ER alpha and two polyclonal ERP antibodies were used. Paraffin sections revealed a s pecific nuclear immunoreaction product in certain cells but not in others. In the epididymis, nuclear ER alpha immunoreactivity (IR) was detected in e pithelial cells of efferent ductules and initial segments as well as in con nective tissue surrounding the tubules in caput, corpus and cauda. No IR wa s observed in rete testis. Epithelial cells of the prostate lacked ER alpha IR, but connective tissue cells surrounding prostatic buds in the early ne onatal period revealed IR. In prostate, ER beta IR was expressed in epithel ial cells of the ventral and dorsolateral lobes, but the IR intensity was h igher in the ventral lobe. III neonatal rats, ER beta was expressed in the epididymis but not in the prostate gland. Weak ER beta expression was found in the prostates of 5-day-old rats, and the reaction increased in intensit y thereafter. In the epididymis, a similar developmental expression pattern of ER beta was observed. ER beta expression in prostate and epididymis was similar to expression of androgen receptors reported previously for these organs. The results support that both ER alpha and ER beta may be involved in oestrogen modulation of prostate and epididymal functions.