Localization of steroid hormone receptors in the pelvic muscles.

After the menopause the pelvic floor becomes progressively weaker, one consequence of which is the increasing incidence of prolapse and urinary incontinence. It is plausible that the reduction in estrogen levels postmenopausally is an etiological factor in these problems. For the pelvic floor muscles to be considered as target organs for estrogen, demonstration of the presence of estrogen receptors is required. The present study aims to confirm previous findings of estrogen and progesterone receptors in the levator ani muscle, and to further localize them histologically. In seven women biopsies from the levator ani muscle were taken and analyzed immunohistologically with monoclonal antibodies for estrogen and progesterone receptors. The receptors were detected in the nuclei of connective tissue cells and striated muscle cells. These findings provide a scientific basis for a possible beneficial effect of estrogen therapy, as a complement to other therapies, in prolapse and urinary incontinence.