Comparison of three types of stress urinary incontinence rat models: electrocauterization, pudendal denervation, and vaginal distension.

OBJECTIVE: To investigate the differences in the histopathologic and functional characteristics of 3 rat models of stress urinary incontinence.
MATERIALS AND METHODS: A total of 24 female, 10-week-old, Sprague-Dawley rats were randomly divided into 4 groups: normal, electrocauterization, pudendal denervation, and vaginal distension. At 2 weeks after surgery, the leak point pressure was measured to detect urinary leakage. Urethral tissue samples were collected for histological examination.
RESULTS: The smooth muscle content in the electrocauterization group was significantly decreased compared with that in all other groups, indicating that electrocauterization caused the most severe injury. A blood vessel marker, von Willebrand factor, was co-stained with α-smooth muscle actin to detect the blood vessel distribution. No significant differences were seen in von Willebrand factor expression among the 4 groups, other than in the electrocauterization group, in which we could hardly observe blood vessel expression. Protein gene product 9.5 staining was used to detect nerve fibers and cells. Protein gene product 9.5 expression was significantly lower in all the treatment groups compared with that in the normal group (P <.05), in particular, in the electrocauterization and pudendal denervation groups (P <.01). The leak point pressure was significantly lower in the electrocauterization (P <.01), pudendal denervation (P <.01), and vaginal distension (P <.05) groups than in the normal group.
CONCLUSION: The vaginal distension model should mainly be used as the myogenic damage stress urinary incontinence animal model; the pudendal denervation model mainly as the neurogenic damage stress urinary incontinence animal model; and the electrocauterization model as the vasculogenic, neurogenic, and myogenic damage animal model.