Effects Of Different Intensity Treadmill Exercise Combined With Fasting On Pancreatic β-cell Function In T2DM Mice

Objective: To explore the intervention effect of different intensity treadmill exercise combined with fasting on T2 DM KM mice,and to analyze its protective effect on isletβ-cell function through high-fat and high-sugar diet combined with STZ injection,in order to obtain the optimal intensity treadmill exercise combined with fasting scheme for the protection of pancreatic β-cell function.Methods: Forty SPF 4-week-old KM male mice were purchased from the Animal Center of Xinjiang Medical University,weighing 16-20 g.They were randomly divided into blank control group（C group,n=8）and high-fat group（HF group,n=32）,fed with normal diet and high-fat diet,respectively,with free food and water.After 4 weeks of high-fat feeding,intraperitoneal injection of STZ induced the establishment of a T2 DM model,and the success of the model was judged by continuously detecting the fasting blood glucose（FBG）of mice for one week.After successful modeling,the HF group was randomly divided into diabetes control group（DC group,n=8）,30% calorie restriction group（30% CR group,n=8）,and low-intensity exercise+30%calorie restriction group（LI+30%CR,n=8）,moderate-intensity exercise+30% calorie restriction group（MI+30%CR,n=8）.The calorie restriction group restricted their daily calorie intake to70%,while the exercise + 30% calorie restriction group exercised while fasting and was given free access to water.Body weight（BW）and FBG were measured weekly during the intervention period.The mice were sacrificed after anesthesia and blood was collected from the eyeballs.IR)and insulin secretion index（HOMA-β）were tested.Histomorphological analysis of mouse pancreas was performed by HE staining technique.The protein expressions of mouse pancreaticβ-cell-related proteins Bax,BCL2,caspase-3,glucose transporter 2（Gult2）and phosphoenolpyruvate carboxykinase 1（Pck1）were determined by Western blotting.The transcript levels of mouse pancreatic β-cell-specific genes INS,Pdx1,NKX6.1 and Neurod1 were determined by RT-q PCR.Results:（1）Both fasting and exercise combined with fasting can reduce body weight,fat content and FGB level in T2 DM mice,but had little effect on organ index.MI+30%CR could change the organ index of pancreas,heart and spleen（P<0.05）.（2）Both fasting and exercise combined with fasting can increase the levels of blood glucose metabolism-related indicators INS,GLU and HOMA-β,and reduce the levels of GHb,GC and HOMA-IR in T2 DM mice,and the effect of LI+30% CR is more effective.Significant（P<0.05）.（3）Fasting and exercise combined with fasting can improve the pancreas tissue morphology of T2 DM mice,and the effect of MI+30%CR is more obvious（P<0.05）.（4）Both fasting and exercise combined with fasting can up-regulate the transcription level of INS gene,thereby up-regulating the protein expression of the glucose transport-related protein GULT2,and down-regulating the protein expression of the gluconeogenesis-related protein PCK1.The effect of LI+30% CR is more pronounced.Significant（P<0.05）.（5）Fasting and exercise combined with fasting can have a protective effect on pancreatic islet β cells.By up-regulating the transcription levels of isletβ-cell-specific genes Neurodl,Pdx1 and NKx6.1 in T2 DM mice,up-regulating the anti-apoptotic protein BCL2 The protein expression of pro-apoptotic proteins BAX and caspase-3 were down-regulated,and the effect of MI+30% CR was more obvious（P<0.05）.（6）Fasting and exercise combined with fasting can reduce the content of MDA,increase the activity of SOD,and then up-regulate the protein expression of the anti-apoptotic protein BCL2 and down-regulate the protein expression of the pro-apoptotic proteins BAX and caspase-3,of which MI+30% The effect of CR was more obvious（P<0.05）.Conclusion: Both fasting and exercise combined with fasting can improve glucose metabolism,reduce oxidative stress,inhibit islet β-cell apoptosis,and then improve islet β-cell function.The exercise combined with fasting program has the best effect,which is better than the30% CR program.The possible action pathways are:（1）Exercise combined with prohibition is through up-regulating the transcription level of the pancreatic islet β-cell-specific gene INS in T2 DM mice,thereby up-regulating the protein expression of the glucose transport-related protein GULT2,and down-regulating the gluconeogenesis-related protein PCK1.Protein expression,thereby improving blood glucose metabolism-related indicators in T2 DM mice,and exerting a protective effect on islet β-cell function.（2）Exercise combined with fasting up-regulated the transcription levels of pancreatic β-cell-specific genes Neurodl,Pdx1 and NKx6.1 in T2 DM mice,which in turn up-regulated the protein expression of the anti-apoptotic protein BCL2 and down-regulated the expression of the pro-apoptotic proteins BAX and caspase-3.Protein expression promotes pancreatic development and islet beta cell differentiation,regulates islet beta cell proliferation and apoptosis,and has a protective effect on islet beta cell function.（3）Exercise combined with fasting can improve the antioxidant capacity of mice,and then down-regulate the protein expression of pro-apoptotic proteins BAX and caspase-3,and up-regulate the protein expression of anti-apoptotic protein BCL2,so as to improve the function of pancreatic β cells.Effect.（4）The LI+30%CR regimen is more effective in protecting the function of islet β cells by improving glucose metabolism,while the MI+30%CR regimen protects islet β cells by reducing oxidative stress,regulating the proliferation and apoptosis of islet β cells The effect of cell function is more obvious.