Estrogen, progesterone, and androgen receptor expression in levator ani muscle and fascia

Previous studies have reported controversial data on estrogen receptor (ER) expression in levator ani muscle. We investigated ER expression in levator ani muscle and fascia and compared it with the expression of progesterone receptor (PR) and androgen receptor (AR). The study included 55 women undergoing surgery for gynecological (asymptomatic, n = 10) or urogynecological conditions (symptomatic, n = 45). The asymptomatic and 21 of the symptomatic women received no hormone replacement therapy (HRT). The remaining 24 symptomatic women received some form of HRT. Biopsies were taken from the levator ani muscle and the overlying fascia, and quantitative measurements of immunohistochemical staining by image analysis were made. None of the levator ani muscle samples showed any evidence of nuclear ER expression in striated muscle fibers, but some cells in the muscular stroma did express ER. However, PR and AR expression was found in both muscle and stromal cells. Levator ani fascia showed nuclear ER, PR, and AR expression to varying degrees. There was a significant increase (p < 0.03) in ER expression in levator ani fascia of symptomatic patients without HRT when compared with asymptomatic age-matched women. The ER expression was significantly lower (p < 0.001) in postmenopausal symptomatic women receiving long-term estrogen replacement compared with age-matched women without HRT. Our data indicate that ER expression is significantly higher in symptomatic women compared with age-matched asymptomatic females. However, long-term estrogenization causes significant decrease of ER expression.