The Effects of Estrogen on Detrusor Contraction and the Expression of Muscarinic Receptors in Ovariectomized Rats

Abstract

of Medicine, Daejeon, Korea Purpose: The purpose of this study was to evaluate the effects of estrogen on detrusor contraction and the expression of muscarinic receptors in ovariectomized rats. Materials and Methods: 24 Sprague-Dawley female virgin rats (12 weeks old) were separated into three groups of 8 rats each. Group I served as a control group, group II was the ovariectomized only rats (Ovx group) and Group III was given estradiol benzoate (0.8mg/kg/day) subcutaneously for 7 consecutive days, beginning 1 week after ovariectomy (Ovx+E group). At the end of the experimental period, each rat was sacrificed and the urinary bladder was removed for contractile studies. The expressions of M2 and M3 receptors in the bladder epithelium and the muscle layer were investigated by performing immunofluorescent staining. Results: The Ovx group showed a significantly decreased bladder contractile function on the KCl and carbachol-induced contractile tests, whereas the Ovx＋E group showed increased contractility (p＜0.05). The Ovx＋E group showed an increase of smooth muscle compared to the other groups. Ovariectomy induced a significant increase in the M3 receptors density in the bladder body, as compared to the control group (p＜0.05) but there was no significant difference between the Ovx group and the Ovx+E group. Conclusions: Bladder dysfunction of menopausal women is thought not to be related with the changes of muscarinic receptors. Our results suggest that the detrusor contractility of menopausal women might be improved