Urinary Bladder Function and Somatic Sensitivity in Vasoactive Intestinal Polypeptide (VIP)−/− Mice
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- Studeny, S., Cheppudira, B.P., Meyers, S. et al. J Mol Neurosci (2008) 36: 175. doi:10.1007/s12031-008-9100-8
Vasoactive intestinal polypeptide (VIP) is an immunomodulatory neuropeptide widely distributed in neural pathways that regulate micturition. VIP is also an endogenous anti-inflammatory agent that has been suggested for the development of therapies for inflammatory disorders. In the present study, we examined urinary bladder function and hindpaw and pelvic sensitivity in VIP−/− and littermate wildtype (WT) controls. We demonstrated increased bladder mass and fewer but larger urine spots on filter paper in VIP−/− mice. Using cystometry in conscious, unrestrained mice, VIP−/− mice exhibited increased void volumes and shorter intercontraction intervals with continuous intravesical infusion of saline. No differences in transepithelial resistance or water permeability were demonstrated between VIP−/− and WT mice; however, an increase in urea permeability was demonstrated in VIP−/− mice. With the induction of bladder inflammation by acute administration of cyclophosphamide, an exaggerated or prolonged bladder hyperreflexia and hindpaw and pelvic sensitivity were demonstrated in VIP−/− mice. The changes in bladder hyperreflexia and somatic sensitivity in VIP−/− mice may reflect increased expression of neurotrophins and/or proinflammatory cytokines in the urinary bladder. Thus, these changes may further regulate the neural control of micturition.