RESUMEN
PURPOSE: Bladder tissue fibrosis is characterized by the abnormal deposition of connective tissue within different layers of the bladder wall, resulting in "non-compliance". The different etiologies of bladder fibrosis are either neurogenic, which encompasses myelodysplasia and spinal cord injury, or nonneurogenic, due to a bladder outlet obstruction. In this study, bladder fibrosis was examined to see if it was due to the effect of an abnormal innervation or to abnormal bladder dynamics. MATERIALS AND METHODS: Thirty-five male Sprague-Dawley rats (250-300g) were divided into four groups; the normal (n=5), bilateral pelvic nerve transection; denervation (n=10), vesicostomy (n=10) and vesicostomy after denervation (n=10) groups. After 4 weeks, the bladders of the animals in each group were obtained. In the histological study, the collagen to muscle ratio from Masson's trichrome staining, and the elastin density (%) from Van Gieson staining, were determined using a Metamorph ver 4.6r5 image analyzer. The TGF-beta1 and collagen III protein expressions were detected by Western blotting. RESULTS: The collagen to muscle ratios of the normal, vesicostomy, denervation and vesicostomy after denervation groups were; 0.67+/-0.04*, 0.67+/-0.04*, 1.25+/-0.03* and 0.96+/-0.02 (*pvesicostomy after denervation>vesicostomy>normal from the histological study. The levels of TGF-beta1 and of collagen III in the denervation group were higher than those in the vesicostomy after denervation group. The above findings show that pressure and nerve innervation in the bladder both have significant effects on the process of bladder fibrosis. Meanwhile, a vesicostomy could reduce the fibrotic effect caused by denervation, although this is not complete.