Mechanism Of Ferroptosis Suppression By MOTS-c And Aerobic Exercise In Improving Diabetic Cardiac Dysfunction

OBJECTIVE: To explore the effects of MOTS-c,aerobic exercise and their combination on cardiac dysfunction in diabetes rats,and further explore the effects of MOTS-c,aerobic exercise and their combination on myocardial ferroptosis in diabetic rats.METHODS: A total of 83 male SD rats aged 6 weeks were randomly divided into a control group(C,n=15)and a diabetes pre-model group(p D,n=68).The model of diabetes rats was established by feeding them with high fat and high sugar diet for 6weeks combined with a low dose of streptozotocin(STZ,30mg/kg).The diabetic rats were randomly divided into diabetes group(D,n=13),diabetes+ aerobic exercise group(DE,n=14),diabetes+ MOTS-c injection group(DM,n=14)and diabetes+ MOTS-c injection+ aerobic exercise group(DME,n=13).Exercise protocol: treadmill exercise was applied,with a slope of 0 °,20 m/min,60 min/day,5 days a week,8 weeks in total.MOTS-c injection protocol: 0.5 mg/kg/day,5 days per week for 8 weeks.M-mode echocardiography was used to detect the changes of cardiac function in rats.The morphological and structural changes of myocardium were evaluated by HE staining and transmission electron microscopy(TEM).The biochemical indexes related to ferroptosis were determined by colorimetry.The content of reactive oxygen species(ROS)in myocardium was measured by flow cytometry.The gene expression of Atf3 and Ptgs2 was determined by q PCR,and the protein levels of Atf3,Ptgs2,Slc7a11,Gpx4 and Mb was determined by Western blotting.RESULTS:(1)Compared with group C,the myocardial cell gap of group D was observed increased.There was more lipid accumulation in the myocardial fiber gap,and some myocardial cells were vacuolar degeneration and nuclear pyknosis.Some myocardial fibers were also bent and deformed.In addition,the myocardial mitochondrial cristae of rats in group D decreased or disappeared,and there were vacuoles in the mitochondria.There were many mitochondria with reduced volume,part of the mitochondrial membrane ruptured,and the nucleus was basically normal.Compared with the rats in group D,the lipid accumulation in the myocardial fiber gap of the rats in the DE,DM and DME groups was reduced,the myocardial fibers were arranged more neatly,the mitochondrial cristae increased,the vacuoles decreased,and the mitochondria basically returned to normal size;(2)Compared with group C,EF and E/A of rats in group D decreased significantly(p<0.05,p<0.01).Both indicators of rats in group DE,DM and DME were significantly improved(EF: p<0.05,p<0.01,p<0.01;E/A: p<0.01,p<0.01,p<0.01);(3)Compared with group C,myocardial ferrous ion and ROS content and MDA in group D were significantly increased(p<0.01),GSH and GSH/GSSG significantly decreased(p<0.01),Atf3 and Ptgs2 protein levels were significantly increased(p<0.01,p<0.05),Slc7a11,Gpx4 and Mb protein levels were significantly decreased(p<0.01,p<0.05,p<0.01).Compared with group D,myocardial ferrous ion in group DE had no significant change(p>0.05),ROS content and MDA decreased significantly(p<0.05,p<0.01),GSH and GSH/GSSG increased significantly(p<0.05),Atf3 and Ptgs2 protein expression decreased significantly(p<0.01),Slc7a11 and Gpx4 protein expression significantly increased(p<0.05),while Mb protein expression showed an upward trend(p>0.05).In the group DM,myocardial ferrous ions were significantly increased(p<0.05),ROS content and MDA were significantly decreased(p<0.01),GSH and GSH/GSSG were significantly increased(p<0.05,p<0.01),The protein expressions of Atf3 and Ptgs2 were significantly decreased(p<0.01),and the protein expressions of Slc7a11,Gpx4 and Mb were significantly increased(p<0.05,p<0.05,p<0.01).Myocardial ferrous ion in DME rats was significantly increased(p<0.01),ROS content and MDA were significantly decreased(p<0.01),GSH and GSH/GSSG were significantly increased(p<0.01).The protein expressions of Atf3 and Ptgs2 were significantly decreased(p<0.01),and the protein expressions of Slc7a11,Gpx4 and Mb were significantly increased(p<0.05,p<0.01,p<0.01).CONCLUSIONS:(1)Both aerobic exercise and MOTS-c can improve cardiac dysfunction in diabetes.(2)Both aerobic exercise and MOTS-c intervention can reduce myocardial ferroptosis through the Atf3-Slc7a11-Gpx4 axis(decrease the expression of Atf3 and increase the expression of Slc7a11 and Gpx4),thereby effectively improving diabetic myocardial injury and improving cardiac function.