Decreased Expression of Urethral Caveolin-1, −2, and −3 in the Rat Model of Overactive Bladder: Potential Mediator of Functional Interaction of Urethra and Urinary Bladder

PURPOSE: To investigate the effect of detrusor overactivity (DO) on the urethral expression of caveolin (CAV)-1, −2, and −3 of urethra in an animal model of cyclophosphamide (CYP)-induced cystitis rat. METHODS: Female Sprague-Dawley rats were divided into the control group (n=20) and the cystitis group (n=20). Cystitis was induced by intraperitoneal injection of CYP (200 mg/kg). An urodynamic study was done 3 days after the CYP injection to measure functional change of the urinary bladder and urethra. Cellular localization and expression of CAV-1, −2, and −3 in the rat urethra were determined by immunohistochemistry (IHC) and Western blot. RESULTS: Urodynamic experiments demonstrated a decreased contraction interval in the cystitis group compared to the control (3.9±1.0 minutes vs. 6.6±1.2 minutes, P<0.05). Conversely, contraction pressure increased significantly in the cystitis group compared to the control (22.4±0.7 mmHg vs. 11.5±0.4 mmHg, P<0.05). The urethral pressure was decreased in the cystitis group compared to the control (4.05±2.5 mmHg vs. 5.8±2.8 mmHg, P<0.05). The IHC and Western blot data showed that CAV-1, −2, and −3 expression decreased significantly in the cystitis group compared control group (P<0.05). CONCLUSIONS: The decreased urethral CAV-1, −2, and −3 in the DO rats suggests that CAVs might be related with the functional change of urethra in association with DO of urinay bladder.