| Objective: To discover the role of M3 muscarinic receptors in detrusor in themechanism of diabetic cystopathy, we researched the alteration of detrusorcontraction and M3 muscarinic receptor mRNA and M3 subtype muscarinicreceptor protein of detrusor in the type 2 diabetes mellitus rats.Materials and methods: Sixty 2-day-old Wistar female rats were divided into six groups at random,including three diabetic groups and three contral groups. Each group had ten rats.The experiments were carried through at the 2-week, the 4-week, andthe12-week of the course of type 2 diabetes mellitus. The type 2 diabetic ratswere developed by the intraperitoneal injection of streptozotocin (STZ) and highcaloric diet. The identical-week-old Wistar rats were used as normoglycemiccontrol rats. We studied the contractile functions of the whole bladder. Fordetermination of the amount of M3 muscarinic receptor mRNA in the bladderbody tissue, the method of RT-PCR was employed. The amount of M3 receptorprotein was measured by the method of western blotting.Results: The results of the whole bladder contractile function experiments showedthat the bladder contractile function of the 2-week diabetic rats was increasedwhen compared with the control rats. The former was (20.37 ± 2.20)cm H2O/100mg, and the latter was (17.27±1.77)cm H2O/100mg(P<0.05). When1mmol/L carbachol was existed, the bladder contractile function of the 2-weekdiabetic rats was increased than the control groups, those were (43.61±2.51)VS (36.63±2.26) cmH2O/100mg (P<0.01). There was no significant differencein the contractile function between the 4-week diabetic rats and the control ratsby about (21.31±2.68) VS (21.54±3.09)cmH2O/100mg (P=0.88). When1mmol/L carbachol was existed, there was also no significant difference in thecontractile function between the 4-week diabetic rats and the control rats byabout (44.45±2.62) VS (45.63±3.12)cmH2O/100mg (P>0.05). The bladdercontractile function of the 12-week diabetic rats was decreased when comparedwith the control rats by about (17.61±3.62) VS (24.57±4.20)cmH2O/100mg(P<0.01). When 1mmol/L carbachol was existed, the bladder contractilefunction of the 12-week diabetic rats was decreased than the control rats byabout (36.38±3.65) VS (46.34±4.29)cmH2O/100mg(P<0.01). The results ofthe RT-PCR showed that the amounts of M3 muscarinic receptor mRNA of the2-week , the 4-week and the 12-week diabetic rats bladders were increased thanthe control groups by about (42.42±3.00)% VS (33.23±5.12)% (p<0.01),(57.27±3.94)% VS (36.48±3.91)% (P<0.01), (63.53±3.54)% VS (39.37±3.70)% (P<0.01). Western blotting demonstrated that the amounts of M3muscarinic receptor protein of the 2-week , the 4-week and the 12-week diabeticrats bladders were increased than the control rats by about(25.13±1.61)% VS(17.47±2.73)% (P<0.01), (36.23±1.70)% VS (24.07±1.66)% (P<0.01),(43.53±1.59)% VS (25.39±1.40)% (P<0.01). As the amount of M3 muscarinicreceptor mRNA increaseing, the amount of M3 muscarinic receptor proteinincreased (r=0.951,P<0.01).Conclusion: These results suggest that the changes of M3 muscarinic receptor mRNAand M3 subtype muscarinic receptor protein of the type 2 diabetic rat urinarybladder are similar. At the 2-week diabetes mellitus course, the amounts of M3muscarinic receptor mRNA, M3 muscarinic receptor protein and the detrusorcontractile function are all increased. However, at the 4-week and the 12-weekdiabetes mellitus course, the amounts of M3 muscarinic receptor mRNA andreceptor protein are increased; the contractile function is decreased. Inconclusion, we think that the alteration of M3 muscarinic receptors is one of themerchanisms of DCP. |
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