Immunohistochemical evidence of vanilloid receptor 1 in normal human urinary bladder

Purpose: Experimental and clinical evidences have shown the importance of the vanilloid receptor I (TRPV I) in the lower urinary tract. In humans, this receptor has been detected in nerve endings of primary sensory neurons, smooth muscle and connective tissue cells and in the rat also in the urothelium. The aim of this study is to identify, by immunohistochemistry, the cell types expressing TRPV1 in the human urinary bladder. Material and Methods: Specimens, obtained from normal urinary bladder by multiple biopsy and from ureter at the time of radical nefrectomy for renal cell carcinoma, were fixed and frozen. Fuil-thickness sections were processed for light and fluorescence microscopes. To label the TRPVI, three polyclonal antibodies were used: the anticapsaicin receptor, the anti-VR1 (N-15) and the anti-VR1 (C-15). Results: Urothelium, smooth muscle cells, mast cells and endothelium were labelled and the labellina was intracytoplasmatic. In the urothelial cells, the labelling was slightly granular. In the bladder urothelium, the superficial cells were more intensely stained than the basal and club-shaped cells. VR1-positive nerve fibers were seen running single and/or in groups in the sub-urothelium and as single varicose fibers in the muscle coat, and VR1-positive nerve endings in the urothellum. Conclusion: The present findings provide the evidence of the presence of TRPVI on normal human urothellium where it could have important unplications in the mechanism of action of intravesical vanillolds (capsalcin and resiniferatoxin). (C) 2004 Elsevier B.V. All rights reserved.