Estrogen Receptor (α and β) Expression in the Excurrent Ducts of the Adult Male Rat Reproductive Tract

Abstract

ABSTRACT: The understanding of estrogen's function in the male reproductive tract is limited, and estrogen receptor (ER) localization in the reproductive tract of the adult male rat has not been described. In the present study, ERα was localized by immunohistochemistry using ER21 antibody, which recognizes only ERα. Strongest immunoreactivity was seen in epithelia of ductuli efferentes and the initial segment of the epididymis. Nuclei of both ciliated and nonciliated cells were positive. The epithelium of the rete testis, and caput, corpus, and cauda epididymides stained less intensely for ERα. The vas deferens epithelium was ERα‐negative. Stromal tissue in the excurrent ducts was also ERα‐positive. Using 3 H‐estradiol autoradiography, specific binding of estradiol was seen in nuclei of ductuli efferentes. Estrogen receptor α mRNA expression was greatly enhanced in ductuli efferentes compared to other regions of the male tract and was 3.5x greater than in the uterus. For comparison, the presence of ERβ was determined using reverse transcription‐polymerase chain reaction (RT‐PCR) amplification. Estrogen receptor β mRNA was expressed throughout the male tract and in the prostate. These results indicate that all organs in the male excurrent ductal system of the rat express ERα and are potential targets of estrogen. However, the ductuli efferentes are the site of the most intense ERα expression. The role of ERβ remains to be determined, but its expression appears ubiguitous in the male tract.