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1 Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States; Department of Urology, The Jikei University School of Medicine, Tokyo, Japan
2 Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
3 Department of Urology, The Jikei University School of Medicine, Tokyo, Japan
4 Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
5 Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States; Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
* To whom correspondence should be addressed. E-mail: nyos{at}pitt.edu.
Approximately one-third of patients with stress urinary incontinence (SUI) also suffer from urgency incontinence that is one of the major symptoms of overactive bladder (OAB) syndrome. Pudendal nerve injury has been recognized as a possible cause for both SUI and OAB. Therefore, we investigated the effects of pudendal nerve ligation (PNL) on bladder function and urinary continence in female Sprague-Dawley rats. Conscious cystometry with or without capsaicin pretreatment (125 mg/kg s.c.), leak point pressures (LPPs), contractile responses of bladder muscle strips to carbachol or phenylephrine, and levels of nerve growth factor (NGF) protein and mRNA in the bladder were compared in sham and PNL rats 4 weeks after the injury. Urinary frequency detected by a reduction in intercontraction intervals and voided volume was observed in PNL rats compared with sham rats, but it was not seen in PNL rats with capsaicin pretreatment that desensitizes C-fiber afferent pathways. LPPs in PNL rats were significantly decreased compared with sham rats. The contractile responses of detrusor muscle strips to phenylephrine, but not to carbachol, were significantly increased in PNL rats. The levels of NGF protein and mRNA in the bladder of PNL rats were significantly increased compared with sham rats. These results suggest that pudendal nerve neuropathy induced by PNL may be one of the potential risk factors for OAB as well as SUI. Somato-visceral cross sensitization between somatic (pudendal) and visceral (bladder) sensory pathways that increases NGF expression and
1-adrenoceptor-mediated contractility in the bladder may be involved in this pathophysiological mechanism.
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