| Objective:The purpose of this study was to investigate the potential mechanism of sacral nerve magnetic stimulation in the treatment of diabetic bladder dysfunction(DBD)from the perspective of detrusor function and to observe the effect of sacral nerve magnetic stimulation on voiding function in DBD rats.This study also aimed to provide experimental support for early intervention of DBD and delaying the progression of the disease.Method:30 rats were randomly divided into two groups,normal group(n = 10)and DBD group(n = 20).After weighing the body weight,the rats in DBD group were intraperitoneally injected with streptozotocin(Streptozotocin,STZ)at a dose of40mg/kg,and STZ was dissolved in 1% citrate buffer.At the same time,the normal rats were injected with the same amount of citrate buffer as the control.After 72 hours,the blood was taken from the tail vein,and the blood glucose of the rats was ≥16.7mmol/L for three consecutive times,which could be considered as a successful model of diabetic rats.Rats in the normal group were regarded as rats in group A,and rats in the DBD group were divided into two groups according to whether they were given sacral nerve magnetic stimulation or not: group B: sham stimulation for 4weeks,control group;group C,sacral nerve magnetic stimulation for 4 weeks,as the experimental group.During the whole experimental cycle,the general physiological and biochemical characteristics such as overall status,blood glucose,body weight and24-hour urine volume were collected and recorded.At the end of the experiment,the rats were killed and the wet weight of bladder was weighed,and the expression and localization of Myosin Light Chain Kinase(MLCK)and Phospho-Myosin Light Chain(p-MLC)were measured by Western Blot and immunohistochemistry.Histomorphological changes of rats in each group were observed by HE staining.Results:In the whole experimental cycle,a total of 25 rats completed the experiment(including group A(n = 10),group B(n = 7)and group C(n = 8).The rats in group B and C all showed the symptoms of polydipsia,polyuria and polyuria,accompanied by strong rotten apple smell of ketoacidosis,lethargy and dull coat color,while the rats in group A were in good condition.The results of other experiments are as follows:1.Blood glucose: before modeling,there was no discernible difference in the blood sugar levels of groups A,B,and C(P > 0.05),but after modeling,the glucose levels of the rats in groups B and C dramatically increased each week and were higher than16.7mmol/L and those in group A(P < 0.05).However,there was no significant difference between group B and C(P > 0.05).2.Body weight: Before modeling,there were no appreciable differences in body weight among groups A,B,and C(P > 0.05).Following modeling,the body weight of the rats in group A climbed gradually during the course of the trial,whereas the weight of the rats in groups B and C fluctuated a little.Rats in groups B and C had considerably lower body weights than rats in group A at the sixth and tenth weeks(P<0.05),but there was no discernible difference between groups B and C(P > 0.05).3.24-hour urine volume: there was no significant difference in 24-hour urine volume before modeling in groups A,B and C(P > 0.05),but at the 6th and 10 th week after modeling,the 24-hour urine volume in group B and C was significantly higher than that in group A(P < 0.01).After 4 weeks of sacral nerve magnetic stimulation,there was no significant difference in 24-hour urine volume between group B and group C(P > 0.05).4.Wet weight of bladder: at the end of the stimulation cycle,the rats in group A,B and C were killed,the intact bladder tissue was separated,the size and morphology of the tissue was observed,and the wet weight of bladder was weighed.Compared with group A,the wet weight of bladder in group B and C was significantly higher than that in group A(P < 0.01),but there was no significant difference between group B and C(P > 0.05).5.Western Blot : after 4 weeks of sacral nerve magnetic stimulation,the expression of MLCK protein in bladder tissue of diabetic rats in group B and C was significantly higher than that in normal control group(P < 0.01),and the level of MLCK protein in group C was significantly lower than that in group B(P < 0.01).After 4 weeks of sacral nerve magnetic stimulation,the expression of p-MLC protein in bladder tissue of diabetic rats in group B and C was significantly higher than that in normal control group,and the level of p-MLC protein in group C was significantly lower than that in group B(P < 0.01).6.Immunohistochemistry: MLCK was mainly distributed in the smooth muscle cell layer of rat bladder and expressed in the cytoplasm,compared with group A,the expression of MLCK in bladder tissue of group B was significantly higher than that of group B,and the expression of MLCK in bladder tissue of group C was significantly lower than that of group B after four-week sacral nerve magnetic stimulation.P-MLC was mainly distributed in the smooth muscle layer and urothelial layer of rat bladder and expressed in the cytoplasm,and the expression of p-MLC in group B and group C was significantly higher than that in group A(P < 0.01).The expression of p-MLC in bladder tissue of rats in group C was significantly lower than that in group B(P <0.01).7.Detrusor muscle strip test: the results of detrusor muscle strip test in rats showed that the maximum bladder contractility induced by electrical stimulation in group B was significantly stronger than that in group A(P < 0.01),and that in group C was significantly stronger than that in group A(P < 0.05).The maximum contractile force of bladder in group C was lower than that in group B,but there was no significant difference between group B and group C(P > 0.05).8.HE staining: the results of HE pathological staining showed that the morphology of bladder tissue in group A was intact.In group B,the epithelial tissue was disordered,with a large number of vacuolar cells,vascular dilatation and abnormal hyperemia in the lamina propria,obvious thickening of the muscular layer and disordered arrangement of muscle bundles.In group C,the transitional epithelial cells in the mucous layer of bladder tissue were not arranged neatly,the vacuolar cells were less,the vasodilation and hyperemia in the lamina propria were less,and the muscle layer was thickened and arranged unevenly.Conclusion:1.The use of sacral nerve magnetic stimulation in the early stage of DBD did not change the general physiological characteristics caused by osmotic diuresis,such as24-hour urine volume and wet weight of bladder,but could reduce the expression of MLCK and p-MLC protein in detrusor muscle of diabetic rats,restore bladder morphology and promote the recovery of bladder function in DBD rats.2.Considering that the production of DBD is caused by many factors,the specific effect and therapeutic mechanism of sacral nerve magnetic stimulation on the improvement of contractile force in the early stage of DBD still need to be further studied. |
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