Irisin Regulates Autophagy Through PI3K/AKT/mTOR Pathway To Improve Islet β Cell Function In Type 2 Diabetic Rats

Objective:To investigate whether Irisin improves pancreatic function in type 2 diabetic rats by regulating autophagy through the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway.Methods:Thirty 8-week-old SPF-grade SD male rats were purchased and randomly divided into normal group(NC group),type 2 diabetes mellitus group(T2DM group),and Irisin intervention group(T2DM+Irisin group).High-fat and high-sugar diet for 5 weeks plus low-dose streptozotocin induced type 2 diabetic rat model.After 8 weeks of intraperitoneal injection of Irisin,rats were tested for fasting glucose,fasting insulin,triglycerides,total cholesterol,LDL cholesterol,and HDL cholesterol.The intraperitoneal glucose tolerance test,intraperitoneal insulin tolerance test and high glucose clamp test were performed to assess islet function and insulin resistance level in each group of rats.The expression levels of PI3K/AKT/m TOR pathway proteins and autophagy-related proteins in the pancreas were subsequently detected by Western blot.The expression levels of insulin,microtubuleassociated protein 1 light chain 3,p62,lysosomal associated membrane protein 2 in rat pancreas were detected by immunohistochemistry.Results:1.Before Irisin intervention,FBG in T2 DM group and T2 DM + Irisin group was significantly higher than that in NC group(P<0.05),but there was no significant difference in FBG between T2 DM + irisin group and T2 DM group(P=0.136).It proved that T2 DM rat model was successfully constructed.There was interaction between FBG and intervention time(F=11.751,P<0.05).With the extension of intervention time,FBG in T2 DM + Irisin group decreased gradually.From the 4th week of intervention,FBG in T2 DM + Irisin group decreased significantly compared with T2 DM group(P<0.05);2.Compared with NC group,the level of FINS in T2 DM group was significantly lower(P<0.05),and FINS in T2 DM group was significantly higher than that in T2 DM group after Irisin intervention(P<0.05);3.Compared with NC group,the serum concentrations of TC,TG and LDL-C in T2 DM group increased significantly(P<0.05),and the concentration of HDL-C decreased(P<0.05).The above indexes in T2 DM + Irisin group were improved(P < 0.05);4.HE staining showed that compared with NC group,the islets of T2 DM group shrank significantly,the total number decreased and the edges were irregular.After Irisin intervention,the number of islets in rats was more than that in T2 DM group,which was round or oval,and the structure was more complete than that in model group β The degree of cell degeneration was reduced;5.Western blot showed that compared with NC group,the expression of p62 and LC3Ⅱ/LC3Ⅰ protein in T2 DM group increased(P<0.05),and the expression of LAMP-2decreased(P<0.05);After Irisin intervention,the expression levels of LC3Ⅱ/LC3Ⅰ and LAMP-2 increased(P<0.05),but the level of p62 protein decreased(P < 0.05).The results of immunohistochemical staining were consistent with those of Western blot;6.Western blot showed that compared with NC group,the levels of p-PI3 K / PI3 K,p-Akt /Akt and p-m TOR / m TOR in T2 DM group decreased(P<0.05),and the above indexes further decreased after Irisin intervention(P<0.05).Conclusion:Irisin can regulate autophagy through PI3K/AKT/m TOR signaling pathway to improve islet β cells function,providing a new idea for the treatment of type 2 diabetes.