| Objective:For a long time,domestic and foreign research on the treatment of diabetes has never stopped.Because it has not had good ideas to cure diabetes so far.There are many types of diabetes,of which type ? diabetes accounted for more than 90%of patients.Apart from a small number of gestational diabetes patients,the remaining proportion of patients with type ? diabetes about 5%-10%.Nonetheless,studies of type ? diabetes are not uncommon.Because it is the highest severity,the highest mortality,and its complications are the most serious.Cardiac dysfunction is one of the major complications of type ? diabetes(Type 1 diabetes,T1DM),and the heart is vital to the human body.Therefore,the development of TIDM-induced rehabilitation of heart disease is very critical.Today,physical therapy(including exercise therapy and physical therapy)is now a universal adjuvant therapy,because of its noninvasive,no side effects and concern.Sports fitness has always been recognized by the public,a number of studies have confirmed that intermittent high-intensity exercise to improve the cardiovascular system better than the traditional moderate intensity of continuous movement;on the other hand,the electromagnetic field as one of the physical therapy,has long been used in the hospital and rehabilitation departments,but the study of magnetic field rehabilitation is mainly concentrated in the field of repair of osteoporosis,the rehabilitation of heart disease rarely reported..In view of this,this study attempts to learn from the previous method,adopt the intermittent weight-bearing treadmill exercise mode,at the same time,by means of low-frequency pulsed electromagnetic field,and combining the two ways to study whether it can improve the heart function of T1DM rats.In addition,weight-bearing ladder exercise has been experimentally demonstrated that can inhibit Myostatin(MSTN),through the PI3K/Akt pathway to improve myocardial function.Therefore,this study will from the biochemical,morphological,protein,gene and other different levels to further explore the molecular mechanism to improve cardiac function,and whether the intervention of this experiment is also through the inhibition of MSTN pathway to improve cardiac function.Methods:In this study,60 male Sprague-Dawley(SD)rats were purchased(quality certificate number:shan medical card words 08-004),weighing 220?240g.All rats were placed in a sterile environment and kept in cages(10 rats per cage).And free diet.Three days after adaptive feeding,they were randomly divided into normal group(NC,n = 10)and T1DM group(DM,n = 50).T1DM rats were injected with 12%STZ(0.1M,pH = 4.5,sodium citrate,protected from light)at a dose of 60mg/kg for building type I diabetes models,while NC group were injected with the same amount of sodium citrate buffer.Record food intake and water intake everyday,and measure weight and fasting blood glucose every 3d.At the 10th day,the typical clinical symptoms of diabetes mellitus appeared,the rats were randomly divided into 5 groups:model control group(Diabetes Control,DC group),positive control group(Diabetes + INS,DI),electromagnetic field intervention group(Diabetes + LFPEMF,DE),the intermittent weight-bearing treadmill intervention group(Diabetes + Weight-bearing Training,DWT)and electromagnetism + intermittent weight-bearing treadmill combined intervention group(Diabetes + LFPEMF +Weight-bearing Training,D+E+WT).8 rats in each group.The changes of cardiac morphological function,cardiac physiological function and the expression of key molecular proteins and genes,such as myocardial insulin receptor,MSTN and receptor,and other key molecular in PI3K/Akt signaling pathway,were analyzed by hemodynamics,ultrasonography,grasping force,myocardial enzyme activity,HE staining,Western Blot,RT-PCR and so on.Results:1.After injection of STZ,the weight of diabetic rats was gradually decreased,while the body weight of NC rats was increasing(P<0.05).And there was significant difference between the 7th day and the 10th day(P<0.01).At the 10th day of modeling,compared with NC group,the amount of food and water intake of DC group increased significantly(P<0.05,P<0.01),and the weights of them were significantly reduced(P<0.01).The fasting serum insulin in DC group was significantly lower than that in NC group(P<0.01),and fasting blood glucose was significantly higher than NC group(P<0.01).OGTT results showed that the blood glucose of DC group increased significantly faster than that of NC group,and the blood glucose level of NC group reached the highest level at the 60th min,and then decreased gradually.The blood glucose of DC group increased until 90min began to decline,and still in the range of high blood sugar.DC group and NC group were significantly different(P<0.01).Type 1 diabetes model was established successfully.2.There was no significant difference between the other groups except for the NC group after 6 weeks of intervention.The cardiac weight of DWT group and NC group was significantly higher than that of DC group(P<0.05).The heart coefficient of DE?DWT?D+E+WT group was significantly higher than that of DC group(P<0.05),and the effect of DWT group was extremely significant(P<0.01).The grip force results showed that D+E+WT group was significantly higher than that of DC group(P<0.05),while the other groups were extremely significantly higher than DC group(P<0.01).3.Doppler ultrasonography showed that the results of left ventricular ejection fraction(EF)and left ventricular fraction shortening(FS)were consistent,NC group was significantly higher than other groups(P<0.01);DI group and DWT group were significantly higher than DC group(P<0.05 or P<0.01).While DE group and D+E+WT group were higher than DC group,but the result was not statistically significant.Cardiac hemodynamics results showed that the heart rate and LVEDP in DI,DWT and D+E+WT groups were significantly lower than those in DC group(P<0.05 or P<0.01),While DE group were lower,but the result was not statistically significant;LVSP,± dp/dtmax showed that the results of DI,DWT and D+E+WT were significantly higher than those in DC group(P<0.05 or P<0.01),but DE group was significantly higher in LVSP(P<0.01),and there was no significant increase in ± dp/dtmax.In the two indexes of ± dp/dtmax,the increased significantly(P<0.05 or P<0.01)compared with the DE group,while D+E+WT group only significantly increased in the-dp/dtmax index compared with the DWT group(P<0.05),HE staining showed that the myocardial fibers in the NC group were neat and compact,and the nuclei were clearly visible.The myocardial fibers in the DC group were disturbed,the cells were swollen and the rupture was more obvious,and the pathological phenomena were obvious.The myocardial cells of DI,DE,DWT and D+E+WT groups were relatively homogeneous,and compared with NC group,there were slight hypertrophy.Compared with NC group,the myocardial fiber diameter of DC group was significantly longer(P<0.01).The myocardial fiber diameters of DI group,DE group,DWT group were shorter than DC group(P<0.01 or P<0.05).The D+E+WT group was slightly shorter than the DC group,but the result was not statistically significant.4.Serum levels of CK,LDH,AST(also known as GOT)and a-HBDH showed that the serum levels of DI,DE,DWT and D+E+WT were significantly lower than those in DC group(P<0.05 or P<0.01).And only the CK index reflects that the D+E+WT group was significantly lower than that in DE group(P<0.01).The contents of NO and NOS in myocardium were similar to those in serum creatinine:DI,DE,DWT and D+E+WT were significantly higher than those in DC group(P<0.05 or P<0.01),and only the NOS index reflects that the D+E+WT group was significantly higher than that in DE group(P<0.01).5.The results of Western Blot and RT-qPCR showed that insulin injection,electromagnetic field treatment,intermittent weight-bearing treadmill and combined intervention could increase the protein expression and mRNA transcription level of insulin receptor(InsR)(DI group was not statistically significant,the other 3 groups P<0.01),reduce the protein expression and mRNA transcription level of MSTN and its receptor(P<0.01),and then promote the phosphorylation of Akt(P<0.05 or P<0.01)and enhance the transcription level of Akt mRNA(P<0.05 or P<0.01),significantly increase the expression of GLUT4 protein(P<0.01),significantly reduce the protein expression and mRNA transcription level of p-GSK3?(P<0.05 or P<0.01),significantly increase the expression of mTOR protein and mRNA transcription level(P<0.05 or P<0.01)and significantly decrease FoxO1 protein expression and mRNA transcription level(P<0.01).However,the interaction between exercise and electromagnetic field intervention group were only several times——MSTN and its receptor protein expression,Glut4 protein expression,p-GSK3? and FOXO1 mRNA transcription-better than the single intervention group?Most of time,the effect of combined intervention were not better than single intervention.Conclusion:1.Intermittent heavy-duty exercise with its unique short-term mixed exercise mode on T1DM rats,can improve the myocardial systolic function of T1DM rats,prevent myocardial cell damage,promote myocardial protein and glycogen synthesis.2.Low-frequency pulsed electromagnetic field can prevent the damage of myocardial cells in T1DM rats,promote the synthesis of protein and glycogen in cardiomyocytes,but the effect of improving myocardial contractility is not obvious.The reasons may be that the electromagnetic field parameters are not the best,yet to be further studied,the latter can try to adjust the electromagnetic field strength or frequency to find more suitable for heart rehabilitation electromagnetic field parameters.3.The molecular mechanism of intermittent weight-bearing treadmill and low frequency pulsed electromagnetic field to improve cardiac function in T1DM rats is to inhibit MSTN-based,activative InsR as the auxiliary,so as to activate Akt,activative or inhibit Glut4,GSK3?,mTOR,FoxO1,then to improve glucose transport,synthesis rate,promote glycogen,protein synthesis,etc.At last,they will promote myocardial cell growth and proliferation,relieve myocardial atrophy and failure.4.The combined effect of electromagnetic fields and intermittent weight-bearing training does not have a further additive effect on the heart in T1DM rats,and at least this conclusion can not be drawn from this study.There may be experimental program unreasonable.It may also need to adjust the electromagnetic field parameters.This is subject to further study in the future. |
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