Expression of TβR-2, Smad3 and Smad7 in the vaginal anterior wall of postpartum rats with stress urinary incontinence.

PURPOSE: The objective of this study is to quantify and evaluate the expression of several important proteins in TGF-β1/Smad pathway in the anterior vaginal wall in postpartum rats with stress urinary incontinence (SUI).

METHODS: Forty 8-week-old Sprague-Dawley (SD) female rats were randomized into three groups: blank group (n = 10), control group (n = 10) and SUI group (n = 20). Rats in blank group were non-pregnant, while rats in the control and SUI groups underwent normal parturition and normal parturition plus immediate postpartum vaginal balloon dilation, respectively. 1 week after dilation, a sneezing experiment and pad test were performed and the anterior vaginal wall was collected. The histological changes of the anterior vaginal wall were assessed by hematoxylin-eosin (HE) staining, and the expression of TβR-2, Smad3 and Smad7 in the anterior vaginal wall was detected by immunohistochemical staining and Western blotting.

RESULTS: HE staining showed that collagen was more fragmented, sparse and disorganized in the SUI group compared with the control and blank groups. Compared with the blank group, the expression of TβR-2 and Smad7 protein was significantly increased in the vaginal anterior wall in the control and SUI groups (P < 0.05), while their levels in the SUI group were significantly higher than those in the control group (P < 0.05). Expression of Smad3 protein in the anterior vaginal wall of SUI rats was significantly decreased compared with the blank and control groups (P < 0.05).

CONCLUSION: Dysregulation of the TGF-β1/Smad signaling pathway may involve in the pathogenesis of SUI.