Estrogen levels influence beta-3-adrenoceptor-mediated relaxation of the female rat detrusor muscle

Abstract

Objectives: To observe the expression of beta-3-adrenoceptor in the detrusor muscle in female rats and investigate the relaxant effect of beta-adrenoceptor agonists on detrusor muscle in ovariectomized rats with or without estrogen replacement therapy.

Methods: We first performed reverse transcriptase-polymerase chain reaction to demonstrate mRNA encoding the beta-3-adrenoceptor in the detrusor muscle from female rats. We then performed pharmacologic and physiologic studies to determine the effect of estrogen replacement therapy on the beta-adrenoceptor-mediated relaxation of the detrusor muscle of the ovariectomized rats.

Results: Beta-3-adrenoceptor was expressed in the detrusor muscle in female rats with or without ovariectomy. A nonselective beta-adrenoceptor agonist relaxed precontracted detrusor muscle irrespective of ovariectomy or estrogen replacement in a dose-dependent manner; and a selective beta-3-adrenoceptor agonist relaxed the detrusor muscle more in ovariectomized rats than in ovariectomized rats with estrogen replacement or in control rats.

Conclusions: Selective beta-3-adrenoceptor agonists relaxed the detrusor muscle of female rats with low estrogen levels. This result may give a clue to the treatment of frequent urination or incontinence in postmenopausal women who are not receiving hormonal replacement therapy.