Immunohistochemical analysis of estrogen receptors in the urethra of sexually intact, ovariectomized, and estrogen-substituted ovariectomized sheep

Introduction and hypothesis Urinary incontinence is prevalent in postmenopausal women and spayed dogs and is associated with decreased estrogen plasma concentrations. The objective of the study was to investigate the expression of estrogen receptors (ER) in the urethra of sexually intact, ovariectomized, and estrogen-substituted ovariectomized ewes. Methods Paraffin cross-sections from each urethral quarter were immunohistochemically analyzed. The reactivity of ER was semiquantitatively assessed employing an immunoreactive score (IRS). Results In contrast to ER beta, ER alpha was identified in all urethral compartments; the highest IRS was detected in the epithelium of the distal urethra. The immunoreactivity and distribution of ER alpha did not differ among groups. Highly significant differences in ER alpha concentrations were observed between consecutive urethral quarters in each group. Conclusions Neither ovariectomy nor ovariectomy and estrogen substitution seem to have a significant effect on overall urethral ER alpha concentration. The results demonstrate that the precise location of the investigated urethral part is crucial to the reliable evaluation or possible comparison of ER alpha concentrations.