Mechanism of dexmetomidine alleviating inflammatory injury in rats with lipopolysaccharide-induced myocarditis
Objective To investigate the effect of dexmedetomidine(Dex)on inflammatory injury in rats with lipopolysaccharide(LPS)-induced myocarditis(Myo)by regulating AMP-activated protein kinase(AMPK)/silent information regulator 1(SIRT1)/nuclear factor κB(NF-κB)signaling pathway.Methods Rats were randomly divide into the NC group,the Myo group,and the L-Dex group(10 μg/kg Dex),the M-Dex group(30 μg/kg Dex),the H-Dex group(50 μg/kg Dex),the AICAR group(100 mg/kg AMPK/SIRT1/NF-κB signal pathway activator),the H-Dex+GSK690693 group(50 μg/kg Dex+0.2 μmol/kg AMPK/SIRT1/NF-κB signal pathway inhibitor GSK690693),with 10 rats in each group.M-mode echocardiography system was used to evaluate the cardiac function of rats;ELISA kit was used to detect the levels of serum interleukin-1β(IL-1β),interleukin-6(IL-6),tumor necrosis factor-α(TNF-α),superoxide dismutase(SOD),and malondialdehyde(MDA)in rats;TUNEL staining was used to observe cell apoptosis;HE staining was used to observe the pathological changes of myocardial tissue;RT-qPCR was used to detect the mRNA expression of C-X-C motif chemokine ligand 1(CXCL1),C-X-C motif chemokine ligand 2(CXCL2),and vascular cell adhesion molecule-1(VCAM-1)in rat myocardial tissue;Western blot was used to detect the expression of AMPK/SIRT1/NF-κB pathway-related proteins in rat myocardial tissue.Results There was no abnormal change in cardiomyocytes in the NC group,and cardiomyocytes in the Myo group showed deformation,necrosis,inflammatory cell infiltra-tion,and mesenchymal congestion;necrosis,inflammatory cell infiltration,and mesenchymal congestion in the L-Dex group,the M-Dex group,the H-Dex group,and the AICAR group were improved compared with that in the Myo group;changes in cardiomyocytes in the H-Dex group and the AICAR group were similar to those in the NC group,and changes in cardiomyocytes in the H-Dex+GSK690693 group were similar to those in the Myo group.Compared with the NC group,the left ventricular ejection fraction(LVEF),left ventricular fractional shortening(LVFS),expression levels of SOD,p-AMPK/AMPK,p-SIRT1/SIRT1 in the Myo group were obviously decreased(P<0.05),left ventricular end-systolic volume(LVESV),left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic diameter(LVESD),left ventricular end-diastolic diameter(LVEDD),expression levels of IL-1β,IL-6,TNF-α,MDA,CXCL1,CXCL2,VCAM-1,p-NF-κB/NF-κB,NF-κB p65 and cardiomyocyte apoptosis rate were obviously increased(P<0.05).Compared with the Myo group,the LVEF,LVFS,expression levels of SOD,p-AMPK/AMPK,p-SIRT1/SIRT1 in the L-Dex group,the M-Dex group,the H-Dex group and the AICAR group were obviously increased(P<0.05),LVESV,LVEDV,LVESD,LVEDD,expression levels of IL-1β,IL-6,TNF-α,MDA,CXCL1,CXCL2,VCAM-1,p-NF-κB/NF-κB,NF-κB p65 and cardiomyocyte apoptosis rate were obviously decreased(P<0.05),and the effects were more obvious with the increase of the dosage of Dex.There was no significant difference in the above results between the AICAR group and the H-Dex group(P>0.05).Compared with the H-Dex group,the LVEF,LVFS,expression levels of SOD,p-AMPK/AMPK,p-SIRT1/SIRT1 in the H-Dex+GSK690693 group were obviously decreased(P<0.05),LVESV,LVEDV,LVESD,LVEDD,levels of IL-1β,IL-6,TNF-α,MDA,cardiomyocyte apoptosis rate,the expression of CXCL1,CXCL2,VCAM-1,p-NF-κB/NF-κB and NF-κB p65 protein were obviously increased(P<0.05).Conclusion Dex may alleviate LPS-induced inflammatory injury in Myo rats by up-regulating AMPK/SIRT1/NF-κB signaling pathway.
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