Diabetes slows the recovery from urinary incontinence due to simulated childbirth in female rats

Abstract

This study was done to test the hypothesis that simulated vaginal birth by vaginal distension (VD) causes more severe urinary incontinence and slower recovery in diabetic rats. After measuring baseline leak point pressure (LPP) in 16 diabetes mellitus (DM) and 16 age- and weight-matched control (Ct) female Sprague-Dawley rats, these animals underwent either VD or sham VD (sham). Four and ten days after the procedures, LPP and conscious cystometry were assessed. Tissues were then harvested and examined by light microscopy. LPP at baseline was equal among all four groups. Four days after VD, LPP in both VD groups dropped to significantly lower levels than in sham rats (P < 0.001). Moreover, LPP in the DM+VD group was significantly lower than in the Ct+VD group. At 10 days, LPP in the Ct+VD group had recovered to its baseline value, whereas the LPP in the DM+VD group remained significantly reduced. DM rats had larger bladder capacity and longer voiding intervals than Ct rats. Histological findings included more severe damage to the external sphincter striated musculature of the urethra in DM+VD group compared with Ct+VD. In conclusion, these findings suggest that DM causes increased severity and delayed functional recovery from the effects of simulated childbirth.

Fig. 1

Leak point pressure (LPP) normalized to preoperative LPP values in the four study groups. Data are represented as median LPP and interquartile ranges of normalized LPP values. Each data point represents data from 5-8 animals with diabetes mellitus or controls that underwent vaginal distension (VD) or sham distension (control VD). *Significant difference compared with comparable sham animals at the same time point. +Significant difference compared with control animals at the same time point.

Fig. 2

Light microscopy of urethra and anterior vagina in control rats 10 days after a sham distension (A) or a vaginal distension (B) and in diabetic rats 10 days after a sham distension (C) or a vaginal distension (D). Masson’s trichrome; *, muscle disruption; L, urethral lumen; Sm, smooth muscle; St, skeletal/striated muscle; V, vaginal lumen. Scale bar = 250 μm.

Fig. 3

Light microscopy of urethra in control rats 10 days after a vaginal distension (A) and in diabetic rats 10 days after a vaginal distension (B). Movat pentachrome; *, collagen deposition in yellow in A and increased deposition of collagen around the smooth muscle fibers in B; L, urethral lumen; Sm, smooth muscle; St, skeletal/striated muscle. Scale bar = 100 μm.

Fig. 4

Light microscopy of bladder in control rats 10 days after a sham distension (A) or a vaginal distension (B) and in diabetic rats 10 days after a sham distension (C) or a vaginal distension (D). Movat pentachrome; L, bladder lumen; Sm, smooth muscle. Scale bar = 250 μm.