Effect and mechanism of NF-κB activation on myocardial ischemia-reperfusion injury under hyperglycemic condition
Objective To investigate the effect and mechanism of the activation of nuclear factor κB(NF-κB)on myocardial ischemia-reperfusion(IR)injury under hyperglycemic condition.Methods Forty-eight male C57BL/6J mice were acclimated for one week and were randomly assigned into six groups:non-diabetic sham-operated group(NG-Sham group),non-diabetic ischemia-reperfusion group(NG-IR group),diabetic sham-operated group(DM-Sham group),diabetic ischemia-reperfusion group(DM-IR group),diabetic ischemia-reperfusion negative control group(DM-IR-NC group),and diabetic ischemia-reperfusion NF-κB recombinant protein intervention group(DM-IR-NF-κB group),with eight mice in each group.Mice in the NG-Sham and NG-IR groups were fed the normal diet.Mice in the NG-IR group underwent myocardial infarction(MI)modeling by ligation of the left anterior descending(LAD)coronary artery,while mice in the NG-Sham group had the LAD artery exposed but not ligated.Mice in the DM-IR group received intraperi-toneal injections of streptozotocin(STZ)at 40 mg/kg for four consecutive days to induce diabetes mellitus(DM).One week after the establishment of the DM model,MI was induced by LAD ligation.Mice in the DM-Sham group underwent the same procedure for DM induction and had the LAD artery exposed but not ligated.Mice in the DM-IR-NF-κB and DM-IR-NC groups underwent the same DM induction procedure and MI modeling.Mice in the DM-IR-NF-κB group received an intravenous injection of NF-κB recombinant protein at 0.5 mg/kg via the tail vein 30 minutes before chest opening,while mice in the DM-IR-NC group did not receive the NF-κB recombinant protein.The myocardial infarct area in the NG-IR and DM-IR groups was assessed by TTC staining.The mRNA expression levels of NF-κB,IL-6,IL-1β,and TNF-α in the myocardial tissues were measured by RT-qPCR.The mitochondrial membrane potential in the NG-Sham,NG-IR,DM-Sham,and DM-IR groups was evaluated using JC-1 staining,and mitochondrial reactive oxygen species(ROS)content was assessed using MitoSOX staining.AMPK and p-AMPK protein expression levels in the myocardial tis-sues were determined by Western blotting.Serum AST and LDH activities in the DM-IR-NC and DM-IR-NF-κB groups were measured by colorimetric assays,and the content of serum CK-MB was determined using double-antibody sandwich ELISA.Results Compared with the NG-IR group,the myocardial infarct area increased(P<0.05)and the mRNA expression of NF-κB in the myocardial tissues was up-regulated(P<0.05),while the mRNA expression levels of IL-6,IL-1β,and TNF-α did not show significant changes in the DM-IR group(all P>0.05).Compared with the NG-Sham group,the NG-IR and DM-Sham groups exhibited decreased mitochondrial membrane potential and increased ROS content(both P<0.05);compared with the NG-IR group,the DM-IR group showed further decreased mitochondrial membrane potential and increased ROS content(both P<0.05).Pearson correlation analysis showed that there was a significant posi-tive correlation between the NF-κB mRNA level and mitochondrial membrane potential in the myocardial tissues of IR mice(r=0.496,P<0.05).Compared with the NG-IR group,the DM-IR group exhibited up-regulated AMPK protein expres-sion,down-regulated p-AMPK protein expression,and decreased p-AMPK/AMPK ratio(all P<0.05).Compared with the DM-IR-NC group,the content of serum AST,LDH,and CK-MB increased(all P<0.05),the relative expression levels of p-AMPK protein and p-AMPK/AMPK in the myocardial tissues decreased(all P<0.05),while the relative expression of AMPK protein did not change significantly in the DM-IR-NF-κB group(P>0.05).Conclusion The activation of NF-κB can promote the susceptibility of the myocardium to IR injury under hyperglycemic condition,and the mechanism may be that NF-κB induces the inactivation of the AMPK signaling pathway and disorder of mitochondrial quality control.
myocardial ischemia-reperfusion injuryhyperglycemianuclear factor κBadenosine monophosphate-activated protein kinasemitochondrial qualitymice
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