Sex specific expression of progesterone receptor in mouse lower urinary tract

Progesterone receptor (PR) was investigated immunohistochemically in the lower urinary tract of the male and female mouse. Estrogen receptor (ER)-subtype-deficient mice (ERKO, BERKO) were used to determine the possible regulation of PR expression in an ER-subtype-specific manner. PR was found to be co-expressed with ERalpha in cell nuclei of urothelium, lamina propria fibroblasts and smooth muscle cells in the female urethra. Only few PR positive cells were seen in female ERKO mice. Ovariectomy reduced and estrogen treatment restored the urethral PR expression in female wild type and BERKO mice. Thus, the expression of PR in the female urethra is estrogen-inducible via ERalpha. In male urethra, PR was co-expressed with ERbeta in the rhabdosphincter. In male, no evidence was obtained for the ER-linked control of the PR expression. No PR-positive cells were observed in the body of the bladder of either sex or any strain.