Location and concentration of estrogen, progesterone, and androgen receptors in the bladder and urethra of the rabbit.

The objective of this study was to determine location and concentration of estrogen, androgen, and progesterone receptors in the bladder and urethra of the rabbit. Two urethral and two bladder specimens were obtained from four 12-week-old female New Zealand white rabbits. Rat monoclonal antibody (AN1-15) to human androgen receptor and (H222) to human estrogen receptor and mouse monoclonal antibody (PR6) to chicken progesterone receptor were used. Immunocytochemical staining was performed and specimens were evaluated for presence and location of steroid receptors. Androgen receptors were found in the highest concentrations in urethral and bladder epithelium. Low to low/moderate concentration were found in smooth muscle. Estrogen receptors were found in moderate to moderate/high concentrations in urethral epithelium and bladder and urethral smooth muscle. Progesterone receptors were not found in appreciable concentrations from any location, though the animals were not pretreated with estrogen. The rabbit model suggests a mechanism by which estrogen therapy can be effective in treating postmenopausal lower urinary tract symptoms. Progesterone receptors were not found in appreciable concentrations, suggesting progesterone therapy may not diminish the effectiveness of estrogen therapy by acting on urethral progesterone receptors. The effect of androgens on the lower urinary tract needs further investigation to determine if androgen therapy can alleviate lower urinary tract symptoms.