Effects of estrogens on the expression of caveolin-1 in the urinary bladders of female rats

Loss of Caveolin 1 is Associated With the Expression of Aquaporin 1 and Bladder Dysfunction in Mice

Purpose:

It is suggested that caveolin and aquaporin might be closely associated with bladder signal activity. We investigated the effect of the deletion of caveolin 1, using caveolin 1 knockout mice, on the expression of aquaporin 1 in order to identify their relation in the urothelium of the urinary bladder.

Methods:

The cellular localization and expressions of aquaporin 1 and caveolin 1, in the wild type and caveolin 1 knockout mice urinary bladder, were examined by Western blot and immunofluorescence techniques.

Results:

Aquaporin 1 and caveolin 1 were coexpressed in the arterioles, venules, and capillaries of the suburothelial layer in the wild type controls. Aquaporin 1 protein expression was significantly higher in the caveolin 1 knockout mice than in the wild type controls (P <0.05).

Conclusions:

The results imply that aquaporin 1 and caveolin 1 may share a distinct relation with the bladder signal activity. This might play a specific role in bladder dysfunction.

Overexpression of aquaporin-1 and caveolin-1 in the rat urinary bladder urothelium following bladder outlet obstruction

PURPOSE

This study was designed to investigate the effect of detrusor overactivity induced by partial bladder outlet obstruction (BOO) on the expression of aquaporin 1 (AQP1) and caveolin 1 (CAV1) in the rat urinary bladder, and to determine the role of these molecules in detrusor overactivity.

METHODS

Female Sprague-Dawley rats were divided into control (n=30) and experimental (n=30) groups. The BOO group underwent partial BOO, and the control group underwent a sham operation. After 4 weeks, an urodynamic study was performed to measure the contraction interval and contraction pressure. The expression and cellular localization of AQP1 and CAV1 were determined by western blot and immunofluorescence experiments in the rat urinary bladder.

RESULTS

In cystometrograms, the contraction interval was significantly lower in the BOO group (2.9±1.5 minutes) than in the control group (6.7±1.0 minutes) (P<0.05). Conversely, the average contraction pressure was significantly higher in the BOO group (21.2±3.3 mmHg) than in the control group (13.0±2.5 mmHg) (P<0.05). AQP1 and CAV1 were coexpressed in the capillaries, arterioles, and venules of the suburothelial layer. AQP1 and CAV1 protein expression was significantly increased in the BOO rats compared to the control rats (P<0.05).

CONCLUSIONS

Detrusor overactivity induced by BOO causes a significant increase in the expression of AQP1 and CAV1, which were coexpressed in the suburothelial microvasculature. This finding suggests that AQP1 and CAV1 might be closely related to bladder signal activity and may have a functional role in BOO-associated detrusor overactivity.

Altered expression of caveolin 2 and 3 in smooth muscle of rat urinary bladder by 17β-estradiol

Background

The purpose of this study was to investigate the effect of estrogen alteration on the expression of caveolin 2 and 3 in rat smooth muscle of urinary bladder.

Methods

Female Sprague–Dawley rats were divided into three groups: control, bilateral ovariectomy (Ovx), and bilateral ovariectomy followed by subcutaneous injections of 17β-estradiol (Ovx?+?Est). After 4 weeks, urodynamic measurements were taken to ascertain the contraction interval and contraction pressure. The expression and cellular localization of caveolin 2 and 3 were determined by Western blot and immunohistochemistry in rat urinary bladder smooth muscle.

Results

In cystometrograms, the contraction interval (min) was significantly lower in the Ovx group (3.1?±?1.5) than in the control group (5.6?±?1.2), but was increased after estrogen treatment (9.3?±?1.0). Conversely, the average contraction pressure (mmHg) was higher in the Ovx group (26.2?±?2.3) than in the control group (21.9?±?3.1), and was decreased after estrogen treatment (23.8?±?3.5). Caveolin 2 and 3 expression was localized in the cell membrane of the smooth muscle. The protein expression of both caveolin 2 and 3 was significantly lower after ovariectomy and was restored to the control levels after 17β-estradiol treatment.

Conclusions

Hormonal alteration causes a significant change in the expression of caveolin 2 and 3 in smooth muscle of rat urinary bladder. These findings suggest that these molecules might have functional roles in the detrusor overactivity that occurs in association with hormonal alteration.

Expression of caveolin-1 in rat urinary bladder with cyclophosphamide-induced cystitis

Purpose

The purposes of this study were to investigate the effect of cyclophosphamide (CYP)-induced inflammatory cystitis on caveolin 1 in rat urinary bladder and to determine the role of these molecules in the bladder dysfunction that occurs in inflammatory change in rat urinary bladder.

Methods

Female Sprague-Dawley rats were divided into control (n=30) and experimental (n=30) groups. Cystitis in experimental group was induced by intraperitoneal injection of CYP (200 mg/kg). The control group underwent an intraperitoneal saline injection. After 3 days, urodynamic studies were done to measure the contraction interval and contraction pressure. The expression and cellular localization of caveolin 1 were determined by Western blot and immunofluorescent study in rat urinary bladder.

Results

In cystometrograms, the contraction interval (minute) was significantly increased in the CYP-induced cystitis rats (15.8±1.5) than in the control group (6.3±0.5) (P<0.05). Conversely, the average contraction pressure (mmHg) was significantly higher in the CYP-induced cystitis rats (15.6±1.7) than in the control group (11.3±0.5) (P<0.05). Caveolin 1 was expressed in the capillaries, arteriols and venules. The protein expression of caveolin 1 was significantly decreased in the CYP-induced cystitis rats (P<0.05).

Conclusions

Inflammatory change of urinary bladder maybe causes a significant change in the expression of caveolin 1. These findings suggest that caveolin 1 might have a functional role in the bladder dysfunction related with cystitis in rat urinary bladder.

Does estrogen have any real effect on voiding dysfunction in women?

For many years, estrogen has been used to treat lower urinary tract dysfunction in postmenopausal women. The data supporting this practice vary. Large multi-institutional studies have shown little role for systemic estrogens in the treatment of urinary incontinence. Vaginal estrogen preparations show superiority to systemic estrogens for the treatment of irritative voiding symptoms in meta-analysis, but there is significant study heterogeneity and the practice remains debatable. Data from randomized controlled trials support estrogen use in the prevention of recurrent urinary tract infections. This article reviews the relevant literature addressing the role of estrogen therapy in urinary incontinence, irritative voiding symptoms, and recurrent urinary tract infections.