Expressions of vaginal endothelial nitric oxide synthase and phosphodiesterase 5 in female sexual dysfunction: a pilot study

Introduction and hypothesis: The objective was to investigate the expression of endothelial nitric oxide synthase (eNOS) and phosphodiesterase (PDE) 5 in vaginal tissue of premenopausal women experiencing stress urinary incontinence (SUI) with and without sexual dysfunction. Methods: Women presenting for treatment of SUI were screened using the Female Sexual Function Index (FSFI) and 10 were selected who met the criteria for female sexual dysfunction (FSD) and 10 asymptomatic controls. Vaginal tissue specimens were obtained from those premenopausal women aged ≥40 years who had had sexual activity ≥2 times every month for the last 6 months and who were scheduled to undergo surgery for SUI. FSD criteria was FSFI scores <18 and arousal domain scores <3. The control group had FSFI scores ≥26 and individual domain scores ≥4. The expressions of eNOS and PDE 5 were compared in the two groups using immunofluorescence staining and western blotting. Results: The mean total FSFI scores were 30.4 ± 2.6 and 15.3 ± 2.3 in the control and FSD groups respectively. In immunofluorescence staining, eNOS and PDE5 were localized in the vaginal epithelium. In western blotting, the expressions of eNOS and PDE5 were significantly lower in the FSD group than in the control group (p = 0.003 and p = 0.038 respectively). Conclusions: eNOS and PDE5 in the vagina may play important roles in the pathophysiology of FSD.