Differential expression of estrogen receptors alpha and beta in adult rat accessory sex glands and lower urinary tract

Estrogens induce pronounced structural and functional changes in male acces sory sex glands and the lower urinary tract in both sexes, but the exact me chanisms of estrogen action are not fully understood. This study was undert aken to localise the tissue cell types that express estrogen receptor in ad ult rats, and to determine the receptor subtype (ER alpha and ER beta) in o rder to identify sites that may respond directly to estrogens. In the male accessory sex glands (seminal vesicles, prostatic lobes and ampullary gland s), ERP mRNA and protein were strongly expressed in the epithelium but not in the stroma, while ER alpha mRNA was present only in the fibromuscular ti ssue surrounding the prostatic collecting ducts in the posterior periurethr al region and in ampullary gland stroma. In the epithelium of the urinary b ladder and urethra of both sexes, high level of ER beta mRNA and protein, b ut no ERa mRNA, was detected. The connective tissue in urinary bladder of b oth males and females, as well as that in prostatic urethra in males expres sed ERa mRNA. The neural cells in the autonomic ganglia of the prostatic pl exus were strongly positive for ERP mRNA, but were completely devoid of ER alpha. We conclude that ER beta is the predominant ER subtype in the epithe lium of adult male rat accessory sex glands and the lower urinary tract of both males and females, as well as in the prostatic neural plexus regulatin g the function of the lower urinary tract in males, while ER alpha is prese nt only in the stromal compartment of distinct sites. These results indicat e that in these tissues in intact adults there are multiple targets for dir ect estrogen action. Furthermore, the differential or complementary express ion of the two ER subtypes suggests that they may have specific functions, and may explain the complex structural and functional changes induced by es trogens. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.