Estrogen levels influence beta-3-adrenoceptor-mediated relaxation of the female rat detrusor muscle.
OBJECTIVE
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.
Matsubara
Shigeji
S
Department of Urology, Kobe University School of Medicine, Kobe, Japan.
Okada
Hiroshi
H
Shirakawa
Toshiro
T
Gotoh
Akinobu
A
Kuno
Takayoshi
T
Kamidono
Sadao
S
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D009126:Muscle Relaxation / Q000502:physiology*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D022702:Receptors, Adrenergic, beta-3 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
D000318:Adrenergic beta-Agonists; D004967:Estrogens; D012333:RNA, Messenger; D022702:Receptors, Adrenergic, beta-3; D007545:Isoproterenol