Function of the Cold Receptor (TRPM8) Associated with Voiding Dysfunction in Bladder Outlet Obstruction in Rats.

PURPOSE: Bladder outlet obstruction (BOO) causes storage and voiding dysfunction in the lower urinary tract. We investigated the expression of transient receptor potential cation channel subfamily M member 8 (TRPM8) to evaluate the relationship between TRPM8 expression and overactive bladder (OAB) in a rat model of BOO. METHODS: Fifty female Sprague-Dawley rats were divided into 4 groups; normal (n=10), normal-menthol (n=10), BOO (n=15), BOO-menthol (n=15). After 3 weeks, cystometry was performed by infusing physiological saline and menthol (3 mM) into the bladder at a slow infusion rate. The histological changes and expression of TRPM8 in the bladder were investigated by Masson's trichrome staining, immunofluorescence and reverse transcription-polymerase chain reaction. RESULTS: Cystometry showed that the intercontraction interval (ICI; 428.2±23.4 vs. 880.4±51.2, P<0.001), micturition pressure (MP; 25.7±1.01 vs. 71.80±3.01, P<0.001), and threshold pressure (2.9±0.25 vs. 9.2±1.58, P<0.01) were significantly increased in BOO rats. The bladder wall was significantly dilated compared with the control. Detrusor muscle hypertrophy and a thick mucosa layer were observed in BOO bladder. After menthol treatment, ICIs were decreased and MPs were increased in the menthol treatment groups. TRPM8-positive cells and mRNA were predominantly increased in the bladder and dorsal root ganglia of all groups compared with the normal group. CONCLUSIONS: Increased bladder wall thickness and proportion of collagen probably affect voiding dysfunction. Furthermore, an increase of TRPM8 expression in BOO may induce entry of Ca(2+) from the extracellular space or stores. The increase of Ca(2+) probably causes contraction of smooth muscle in BOO. However, OAB symptoms were not observed after menthol treatment although the expression of TRPM8 was abundant in the bladder epithelium after menthol treatment. Although OAB in BOO models may be caused by complex pathways, regulation of TRPM8 presents possibilities for OAB treatment.ope

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Dept. of Medical Science/석사Congenital megaureter is a term used in many cases of urinary tract dilatation detected before and after birth. Prior studies have investigated histological changes such as the concomitant decrease in smooth muscle cells and increase in extracellular connective tissue. However, the underlying pathophysiology of obstructive and refluxing megaureter is poorly understood. Megaureter and normal ureter tissues were used to examine differentially expressed proteins to gain a better understanding of the pathogenesis of megaureter. Smooth muscle cells (SMCs) of obstructive megaureters were obtained from 5 patients who underwent open ureteroneocystostomy surgery and 5 control patients with low grade VUR. The obtained SMCs were cultured in M199 medium supplemented with 10% fetal bovine serum (FBS) and 1% antibiotics. To identify differently expressed proteins, protein spots separated by 2D gel electrophoresis were matched and then analyzed using PDQuest software and nanoflow LC-ESI-MS-MS. TPM1, a protein associated with the contraction and migration of SMCs, was selected among the analyzed proteins such as annexin A2, smooth muscle protein and nephronectin etc. to investigate its relationship with megaureter. When α-tropomyosin (TPM1) was artificially over-expressed in normal ureter SMCs, a significant change in morphology was observed. In addition, the rate of apoptosis was increased in transfected SMCs compared with controls. Ureter smooth muscle is known to play an important role in peristalsis and pacemaker activity. Abnormal over-expression of TPM1 in ureter SMCs may induce defects in contractility and increase apoptosis. Empty spaces caused by apoptosis may then be preferentially filled with connective tissue rather than SMCs which have a low migration rate. As a result, contractility is decreased; leading to the development a dilated ureter.From the results of this study, over-expression of TPM1 gives new insights on potential molecular mechanisms associated with the development of megaureter and is expected to be a potentially exploitable protein as putative prognostic biomarkers of fibrosis in ureters and other tissues.ope