부산대학교 도서관

The effect of ovariectomy and long-term estrogen replacement on voiding function and muscarinic receptor distribution in the rat.Purposes : An overactive bladder is highly prevalent in middle-aged woman, especially during the postmenopuase period. I postulated that detrusor instability is associated with estrogen deficiency. I used rats to study the relationship between detrusor instability and postmenopause and the effects of estrogen replacement for detrusor instability caused by ovariectomy.Material and Methods : Thirty female Sprague Dawley rats were divided into three groups: the control, the ovariectomy group and the estrogen replacement group after the ovariectomy. The ovariectomy and estrogen replacement groups had bilateral ovariectomies at 12 weeks of age. After 2 weeks, the control and ovariectomy groups were injected weekly with saline through subcutaneous route, while the estrogen replacement group was injected with estradiol benzoate (500㎍/㎏) through subcutaneous route weekly. After 12 weeks, the voiding frequency study was recorded using a metabolic cage and a cystometrogram was performed while awake. They were then sacrificed. The harvested bladders were used in the carbachol-induced detrusor muscle contraction study and the distribution of estrogen, M₂ and M₃ muscarinic receptors in the rats' detrusor muscle and bladder mucosa were also investigated.Results : The ovariectomy group voided more frequently than the others (p=0.005). During the awake cystometrogram, the detrusor characteristics of the ovariectomy group were a higher mean intervoiding pressure and smaller functional bladder capacity than the others (p=0.000). There was no significant statistical difference between the two groups. The other cystometrogram parameters of were not statistically different either. The detrusor muscle contraction study showed no difference between the three groups. There was a significant difference in the distribution of M₂ and M₃ receptors of bladder mucosa between the control and ovariectomy group. The other groups and receptors showed no difference.Conclusions : The detrusor instability that the ovariectomy induced was comfirmed in the postmenopause rat model. This study suggested that the detrusor instability resulted from increased connective tissue ratio and decreased M₂, M₃ receptor in the bladder mucosa. Moreover, estrogen replacement in the postmenopause state had the effect of reversing the functional and pathologic changes caused by an estrogen deficiency in the bladder.