ESTROGEN-RECEPTOR-ALPHA AND ESTROGEN-RECEPTOR-BETA EXPRESSION IN THE EXCURRENT DUCTS OF THE ADULT MALE-RAT REPRODUCTIVE-TRACT

The understanding of estrogen's function in the male reproductive trac t is limited, and estrogen receptor (ER) localization in the reproduct ive tract of the adult male rat has not been described. In the present study, ER alpha was localized by immunohistochemistry using ER21 anti body, which recognizes only ER alpha. Strongest immunoreactivity was s een in epithelia of ductuli efferentes and the initial segment of the epididymis. Nuclei of both ciliated and nonciliated cells were positiv e, The epithelium of the rete testis, and caput, corpus, and cauda epi didymides stained less intensely for ER alpha. The vas deferens epithe lium was ER alpha-negative. Stromal tissue in the excurrent ducts was also ER alpha-positive. Using H-3-estradial autoradiography, specific binding of estradiol was seen in nuclei of ductuli efferentes, Estroge n receptor alpha mRNA expression was greatly enhanced in ductuli effer entes compared to other regions of the male tract and was 3.5x greater than in the uterus. For comparison, the presence of ER beta was deter mined using reverse transcription-polymerase chain reaction (RT-PCR) a mplification. Estrogen receptor beta mRNA was expressed throughout the male tract and in the prostate. These results indicate that all organ s in the male excurrent ductal system of the rat express ER alpha and are potential targets of estrogen. However, the ductuli efferentes are the site of the most intense ER alpha expression. The role of ER beta remains to be determined, but its expression appears ubiguitous in th e male tract.