Effect of estrogen on molecular and functional characteristics of the rodent vaginal muscularis

Abstract

Vaginal atrophy is a consequence of menopause, however little is known concerning the effect of estrogen on vaginal smooth muscle function. The goal of this study was to determine the effect of estrogen on molecular and functional characteristics of the vaginal muscularis using a rodent model of surgical menopause. 3–4 month old Sprague Dawley rats underwent sham laparotomy (Sham) or ovariectomy (Ovx). Two weeks following surgery, animals received a subcutaneous osmotic pump containing vehicle (Sham, Ovx) or 17‐ β estradiol (Ovx). Animals were euthanized one week later and the proximal vagina was collected for molecular and in vitro contractility studies. Measurements were analyzed using one way ANOVA followed by post hoc analysis. Ovariectomy decreased 1) mRNA transcript (P<0.05) and protein (P < 0.001) expression of carboxyl‐terminal myosin heavy chain isoform (MHC), SM1, 2) protein expression of h‐caldesmon (P < 0.01) and 3) peak force of vaginal strips in response to KCl (P < 0.001). Estradiol replacement reversed these changes. No differences were detected in the % vaginal muscularis, amino terminal MHC isoform expression and maximal velocity of shortening. Our results suggest that menopause is associated with changes in the vaginal muscularis which may contribute to the increased incidence of pelvic floor disorders with age.Funding: AUA Research Scholar Award, Maureen Basha