Alterations of M2-muscarinic receptor protein and mRNA expression in the urothelium and muscle layer of the streptozotocin-induced diabetic rat urinary bladder

Diabetes associated alterations of M2-muscarinic receptors (M2-mAChR) in the urothelium and muscle layer of the urinary bladder were studied using streptozotocin (STZ)-induced diabetic rats. Male Wistar rats were divided into two groups; group I: normal control rats; group II: STZ-induced diabetic rats, 2 weeks after induction. The bladder was divided into urothelium and muscle layer by microdissection. Tissue M2-mAChR protein levels were measured by Western blotting. Expression of the mRNA that encoded M2-mAChR was estimated using the method of reverse transcription combined with polymerase chain reaction (RT-PCR). M2-mAChR protein and mRNA expressions were found in both the urothelium and muscle layer of the rat urinary bladder. In control rats, the M2-mAChR protein expression ratio in the urothelium and muscle layer was 1:1.66; that for mRNA was 1:0.97. Two weeks after induction of diabetes, the M2-mAChR mRNA expression in the urothelium and muscle layer were significantly increased by 44.4% (P < 0.01, n = 8) and 28.6% (P < 0.01, n = 8), respectively. Correspondently, the bladder M2-mAChR protein levels were significantly increased by 33.3% (P < 0.001, n = 8) in the urothelium and 25.3% (P < 0.01, n = 8) in the muscle layer of the diabetic rats. In conclusion, M2-mAChR mRNA and protein are expressed in both the urothelium and muscle layer of the rat urinary bladder. STZ-induced diabetes increases mRNA and protein expression of the M2-mAChR in the urothelium as well as the muscle layer.