The experimental study of the relationship between the nitric oxide, vasoactive intestinal peptide and stress urinary incontinence

Objectives To determine both the distribution and expression of non-adrenergic and noncholinergic neurotransmitters(NANC) nitric oxide (NO) and vasoactive intestinal peptide (VIP) in the urethra, vagina, elevator ani muscle of the SUI model rats. And to clarify their roles in the pathogenesis of SUI. Methods Choosing 12 SUI SD rats as experimental group and the other 12 normal SD rats as control group, both groups were killed and taken away the whole pelvic tissue including the urethra, vagina and elevator ani muscle. The urethra, va gina and elevator ani muscle were examined by HE dyeing and immunohistochemically (ABC dyeing). The results of immunohistochemistry were calculated with the integrated optical density and analysed statistically with independent sample t-test. Results (1) HE staining shows that the urethra, vagina, elevator ani muscle have the uniform staining, normal size in all kinds of cells and regularly arranged muscle fibers in control group. However the uneven staining, tissue edema, atrophy thinning, muscle fiber arranged loosely and disordered slightly, a small amount of inflammation and cell necrosis were seen in the experimental group. (2) The immunohistochemical results shows that the integrated optical density of nitric oxide (NO) in urethra, vagina, levator ani muscle were 3.95 ± 1.02, 6.01 ± 1.32, 18.67 ±4.94 in the control group and were 1.04 ±0.38, 1.44 ±0.48, 6. 16 ± 1.32 in the experimental group. In control group, the integrated optical density of vasoactive intestinal peptide (VIP) were 3.57 ±0.77, 7. 15 ±1.67, 20.29 ±3.39 in urethra, vagina, levator ani muscle, which were 0.73 ±0.23, 2.51 ± 0.60, 3.69±1.24 in the experimental group. Both the expression of NO and VIP between the control group and experimental group in urethra, vagina, levator ani muscle have the significant difference. The difference has the statistical significance( P <0.01). Conclusions (1 )The degeneration, edema of pelvic floor muscle, leading to weaken the pelvic floor strength, maybe relate to the pathogenesis of SUI. (2) NO and VIP locate in plasma and are the most near the vascular. The difference of nitric oxide (NO) and vasoactive intestinal peptide ( VIP) in the urethra, vagina, levator ani muscle between the experimental group and control group indicates that NO and VIP may play a role in the development of SUI. Key words: Urinary Incontinence,Stress; Nitric Oxide;  Vasoactive Intestinal Peptide