Abstract
It has been thought that the etiology of bladder cooling reflex is related to unmyelinated C-afferent fibers in pelvic nerve that is not involved in the normal micturition reflex. Some investigators reported that the bladder mucosa have the thermoreceptor and can detect cold sensation that generally occurred below 30°C.) Recently, TRPM8 has been identified in urogenital organ, but it is unknown the function of this receptor in these area. We investigated the relationship between TRPM8 and voiding behavior. A catheter was inserted into wistar female rat bladder dome, and the cystometry was performed postoperative 72 hours later. After saline (37°C) was infused into the bladder for two hours, menthol (Sigma-0.06 mM, 0.6 mM, 6 mM) was infused applied for 15 min. Menthol increased a voiding pressure in a dose-dependent manner but no change in menthol decreased a voiding interval. The immunohistochemistry was done to define the distribution of TRPM8 in lower urinary tract. Fluorogold was injected into bladder wall, after 5 days, the bladder and L6-S1 DRG was extirpated and enbeded in OCT and sectioned on a cryostat. In DRG, TRPM8 positive neurons contained fluorogold, while in bladder, urotherial layer was positive to TRPM8, and nerve fibers were merged with NF200. [J Physiol Sci. 2007;57 Suppl:S223]
