The Effects Of Electroacupuncture On Glucose And Lipid Metabolism In ZDF Rats Were Studied Based On APN/AMPK/PPAR? And GLUT4 Pathways

BACKGROUNDInsulin resistance(IR)characterized by decreased insulin sensitivity and impaired glucose utilization in peripheral tissue,especially in muscle tissue,is a key factor in the progression of type 2 diabetes mellitus(T2DM),which is caused by hyperglycemia.Dyslipidemia is an important sign of the occurrence and development of insulin resistance,and insulin resistance is the key link of dyslipidemia.They influence and promote each other,forming a vicious circle.Therefore,effective control of blood lipids is of great significance in improving insulin resistance in T2DM.It has been shown that electroacupuncture(EA)therapy could effectively reduce blood glucose and lipid,regulate serum adiponectin(APN)secretion,and improve insulin resistance in T2DM rats in our previous studies,which focused on the the mechanism of EA in lowering blood glucose,lacking in clarification on the mechanism of EA to reduce lipid and improve IR.Therefore,on the basis of previous research and the support of the National Natural Science Foundation general project(Effect of electro-acupuncture in regulation of fast and slow twitch muscle fibers through the AMPK/PGC-1? pathway to improve insulin resistance,No:81973935),our study observed the effects of EA on serum APN level,adiponectin receptor 1(AdipoRl),AMP activated protein kinase(AMPK),peroxisome proliferator activated receptor-?(PPAR?),glucose transporter-4(GLUT4)protein expression and morphological changes of skeletal muscle in zucker diabetic fatty(ZDF)rats,as to provide scientific evidence for the clinical application of EA in the treatment of glucose and lipid metabolism disorders in T2DM.OBJECTIVEBased on the disorder of glucose and lipid metabolism in T2DM,we further explored the mechanism of EA in reducing glucose and lipid by using technology and method of modern science:?to observe the effects of EA on levels of blood glucose,body weight,blood lipid,serum insulin,C-peptide and insulin resistance index in ZDF rats,and to explore whether EA can regulate glucose and lipid metabolism and improve insulin resistance.?to observe the effect of EA on serum adiponectin level,skeletal muscle signal molecules expression of AdipoR1,AMPK,PPARa and GLUT4 and morphological changes in ZDF rats.The above results are to explore the molecular mechanism of EA in improving glucose and lipid metabolism and insulin resistance and to provide a reliable experimental evidence for the clinical application and promotion of EA therapy.METHODSTwelve 2-month-old male ZDF rats of SPF grade and six 2-month-old male Zucker lean(ZL)rats of SPF grade were selected.The rats were fed with Purina#5008 high-fat diet for four weeks to induce T2DM model after adaptive feeding with normal diet for one week.ZDF rats were randomly divided into model group and EA group according to blood glucose level after modeling and 6 ZL rats were used as blank group.Rates in EA group were treated with bilateral "Pishu"(BL20),"Weiwanxiashu"(EX-B3),"Zusanli"(ST36)and,"Sanyinjiao"(SP6)low-frequency 15Hz continuous wave EA for 4 weeks,once a day and 6 times a week.Model group and Blank group were grabbed and fixed in the same way as EA group.Fasting blood glucose(FBG)and body weight of rats in each group were measured every weekend during modeling and intervention.After intervention,serum insulin(INS),C-peptide(C-P)and APN levels were measured by radioimmunoassay,free fatty acid(FFA),low-density lipoprotein(LDL),cholesterol(TC)and triglyceride(TG)contents were determined by enzyme colorimetry and insulin resistance index(HOMA-IR)was calculated.The protein expression levels of AdipoR1,AMPK,PPARa and GLUT4 in quadriceps femoris were detected by Western Blot and morphological changes of quadriceps femoris muscle were observed by HE staining.RESULTS1.General condition:Compared with the blank group,the rats in the model group were significantly obese,depressed,less active,less glossy fur and fur broken,increased diet and drinking,significantly increased defecation and urination,which with obvious peculiar smell.Compared with the model group,the rats in the EA group had no significant change in physique,but improved in activity,mental state,fur color,fur broken,defecation and urination.2.Fasting blood glucose:Before modeling,there was no significant difference in FBG level among the three groups(P>0.05).Before intervention,the FBG level of the model group was significantly higher than that of the blank group(P<0.01),and there was no significant difference between the EA group and the model group(P>0.05).After intervention,FBG in the model group was significantly higher than that in the blank group(P<0.01),and FBG in the EA group was significantly lower than that in the model group(P<0.05).Compared with the beginning of intervention,FBG in the blank group and the model group was significantly increased(P<0.05,P<0.01),but there was no significant change in FBG in the EA group(P>0.05).3.Body weight:Before modeling,before and after intervention,the body weight of the model group was significantly higher than that of the blank group(P<0.01)and there was no significant difference between the EA group and the model group(P>0.05).The difference of body mass before and after modeling in the model group was higher than that in the blank group(P<0.01),almost equal to that in the EA group(P>0.05),The body mass increment before and after intervention of the model group was significantly lower than that of the blank group(P<0.05),higher than that in the EA group(P<0.05).4.Serum insulin,C-peptide levels and insulin resistance index:After intervention,compared with the blank group,the serum C-P,INS and HOMA-IR of the model group were significantly increased(P<0.01),those of the EA group were significantly decreased compared with the model group(P<0.01).5.Blood lipid and serum APN levels:Compared with the blank group,the serum FFA,LDL,TC and TG levels of the model group were significantly increased(P<0.05,P<0.01),while the levels of serum APN was decreased(P<0.01).Compared with model group,the levels of serum FFA,LDL and TC in EA group were significantly decreased(P<0.01)and the level of serum APN was increased(P<0.01),while there was no statistical difference compared with the model group although the serum TG level of the EA group was decreased(P>0.05).6.Expression of AdipoR1,AMPK,PPARa and GLUT4 protein in skeletal muscle:Compared with the blank group,the expression of AdipoR1,AMPK,PPARa and GLUT4 protein in skeletal muscle of the model group was decreased(P<0.01,P<0.05)and those of the EA group were significantly increased compared with the model group(P<0.01).7.Morphological changes of skeletal muscle:Compared with the blank group,the arrangement of skeletal muscle cells in the model group was disordered,the muscle fibers were broken and unclear,the gap between muscle fibers was enlarged,and a small amount of fat cells were seen in the local area.Compared with the model group,the arrangement of muscle fibers in the EA group was improved,and there was a small amount of local adipocyte infiltration.CONCLUSION1.ZDF rats fed purina#5008 diet could induce spontaneous T2DM model,as a suitable model of type 2 diabetes,insulin resistance and obesity,which has the characteristics of abnormal blood glucose,lipid levels,obesity,hyperinsulinemia and insulin resistance,showed typical symptoms of type 2 diabetes,such as polydipsia,polyphagia,polyuria,peculiar smell in urine,mental depression,dull hair and so on.2.EA could regulate the blood glucose and lipid levels,reduce the secretion of insulin and C-peptide,alleviate the symptoms of IR,and then reduce the load of islet ? cells in ZDF rats.3.EA could improve the level of serum adiponectin,and then play the biological effect of hypoglycemic and lipid-lowering.4.EA could further promote the expression of adiponectin receptor and the conduction of AMPK/GLUT4 and AMPK/PPARa signaling pathway in skeletal muscle by increasing the serum adiponectin level,which up regulates skeletal muscle glucose uptake and fatty acid oxidation utilization.5.EA could improve the arrangement of skeletal muscle fibers,protect the morphology of skeletal muscle,and regulate the function of skeletal muscle to alleviate the disorder of glucose and lipid metabolism and IR in T2DM rats.