| ObjectiveTo study the effect of Glucagon-like peptide-1(GLP-1)analogue,Liragluted(LG)to ischemia-reperfusion(I/R)injury in a rat model of metabolic syndrome(MS),as well as hypoxia/reoxygenation(H/R)cardio myocytes cultured in high glucose,we investigated the protective effects and the mechanism underlying LG improved I/R.Methods and Results1.Protective effects of LG on myocardial I/R injury and autophagy in rats with MSFour weeks old male OLETF(otsuka Long-Evans to Kushima fatty,OLETF)rats were fed with high-fat diet to establish MS model.MS rats were divided into sham operation(S),I/R+NS,I/R+LG,I/R+LG+CQ and I/R+CQ group.The dose of LG was 4 mg/kg and chloroquine(CQ)was 25 mg/kg,once a day,intraperitoneally injected for consecutive 8 weeks.Myocardial I/R injury model was established by ligating the anterior descending artery 30 minutes and reperfusion 120 minutes.The components of MS,cTnT were monitored;cardiac function was evaluated by color Doppler echocardiography;mitochondrial area and autophagy were observed by electron microscopy;myocardial infarction area was observed by TTC staining;myocardial interstitial fibers were observed by Masson staining;autophagy-related proteins and autophagy upstream pathway-related proteins were detected by Western blot.Results: MS model was successfully established at 24 weeks.The metabolic components of MS rats were improved after LG was applied.Compared with I/R+NS group,myocardial infarction area in I/R+LG decreased significantly,CTnT level decreased,cardiac function improved,myocardial infarction area increased,CTnT level and cardiac function were partly reversed after application of chloroquine.The autophagy level of cardiac myocytes in I/R+LG was higher than that in I/R+NS group.After CQ application,the autophagy level of cells decreased.AMPK/mTOR pathway was activated by LG.2.Protective effects of LG on hypoxic-reoxygenated neonatal rat cardiomyocytes cultured with high glucose and its effect on autophagyThe optimum concentration of LG was treated in cells was determined via CCK8.Cells were divided into control,H/R,HH/R,LG,HH/R+LG,HH/R+LG+CQ and HH/R+LG+CC group.In addition,in order to exclude the effect of osmotic pressure on myocardial cell survival,H/R + Mannitol group was set up.LG was added 3 hours before hypoxia and reoxygenation.High glucose concentration was 50 mmol/L,H/R group glucose was 5.5 mmol/L and mannitol was 44.5 mmol/L.The survival rate of myocardial cells in each group was measured.Wsestern blot was used to detect autophagy-related proteins and upstream pathway-related proteins.The changes of autophagic flow were observed by GFP-mRFP-LC3 adenovirus transfection into neonatal rat cardiomyocytes.Results: There was no significant difference in cell viability between NH/R+Mannitol group and NH/R group.The cell viability in H/R group was higher than HH/R group,and the autophagy level in H/R group was higher than HH/R group.The cell viability and the autophagy level in HH/R+LG group was higher than HH/R group.The cell viability in HH/R+LG+CQ group was significantly lower than that in HH/R+LG group after adding autophagy inhibitors.The phosphorylation level of AMPK in HH/R+LG group was higher than HH/R group and the phosphorylation level of mTOR in HH/R+LG group was lower than HH/R group.The autophagy level and cell viability in HH/R+LG+CC group was lower than HH/R+LG group.Conclusion: 1.in this study,LG significantly improved the metabolic components in MS rats.It had protective effects on myocardial I/R injury in MS rats,and could improve the level of myocardial autophagy and autophagic flow.2.The neonatal rat cardiomyocyte of H/R were cultured with high glucose,pretreated with liraglutide,and treated with autophagy inhibitors and AMPK inhibitors,suggesting that LG can increase the level of autophagy of cardiac myocytes,improve autophagic flow and exert the protective effect of cardiac myocytes by activating AMPK/mTOR pathway.. |
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