右美托咪定预处理对大鼠心肌缺血再灌注损伤时HMGB1/TLR4/NF-κB信号通路的影响

Effect of Dexmedetomidine Pretreatment on HMGB1/TLR4/NF-κB Signaling Pathway during Myocardial Ischemia-Reperfusion Injury in Rats

目的探讨右美托咪定(Dex)预处理对大鼠心肌缺血再灌注损伤(IRI)时高迁移率族蛋白B1/Toll样受体4/核因子κB(HMGB1/TLR4/NF-κB)信号通路的影响。方法将36只SD大鼠依据随机数字法分为3组:假手术组、IRI组和Dex预处理组,各12只。制备心肌IRI模型,取血比较三组血清白细胞介素(IL)-6、IL-8、IL-12和肿瘤坏死因子-α(TNF-α)水平;取心肌组织,比较谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)和丙二醛(MDA)水平,检测心肌组织中HMGB1、TLR4和NF-κB蛋白表达水平。结果与假手术组相比,IRI组和Dex预处理组IL-6、IL-8、IL-12和TNF-α水平均显著升高(P<0.01);与IRI组相比,Dex预处理组IL-6、IL-8、IL-12和TNF-α水平显著降低[(231.7±24.8)ng/L比(292.1±21.8)ng/L,(137.7±9.5)ng/L比(179.5±13.7)ng/L,(122.4±15.6)ng/L比(174.6±18.8)ng/L,(681.3±31.2)ng/L比(734.9±26.3)ng/L](P<0.05)。与假手术组相比,IRI组和Dex预处理组心肌GSH-Px和SOD水平降低(P<0.01),MPO和MDA水平升高(P<0.01);与IRI组相比,Dex预处理组心肌GSH-Px和SOD水平升高[(14.42±2.58)kU/g比(8.71±1.18)kU/g,(64.22±14.37)kU/g比(51.76±12.81)kU/g](P<0.05),MPO和MDA水平下降[(12.8±1.83)U/g比(16.42±2.11)U/g,(6.57±1.17)μmol/g比(8.64±1.04)μmol/g](P<0.05)。与假手术组相比,IRI组和Dex预处理组心肌HMGB1、TLR4和NF-κB蛋白表达水平均明显升高(P<0.01);与IRI组相比,Dex预处理组心肌HMGB1、TLR4和NF-κB蛋白表达水平明显降低[(0.72±0.14)比(0.97±0.13),(0.84±0.20)比(1.08±0.22),(0.87±0.21)比(1.21±0.11)](P<0.01)。结论心肌IRI时HMGB1/TLR4/NF-κB信号通路被激活,Dex通过抑制该信号通路影响下游靶分子的表达,降低免疫分子和炎症因子水平,从而对心肌IRI发挥保护作用。

Objective To investigate the effect of dexmedetomidine(Dex)pretreatment on high mobility group protein B1/Toll-like receptor 4/nuclear factor-κB(HMGB1/TLR4/NF-κB)signaling pathway during myocardial ischemia-reperfusion injury(IRI)in rats.Methods A total of 36 SD rats were divided into 3 groups by random numbers table method:a sham operation group,an IRI group,a Dex pretreatment group,12 rats in each group.Myocardial IRI models were established,and the serum concentrations of interleukin(IL)-6,IL-8,IL-12 and tumor necrosis factor-α(TNF-α),and the contents of glutathione peroxidase(GSH-Px),superoxide dismutase(SOD),myeloperoxidase(MPO)and malondialdehyde(MDA)in myocardium of the three groups were compared,and the protein expression levels of HMGB1,TLR4 and NF-κB in myocardium were detected.Results Compared with the sham operation group,the concentrations of IL-6,IL-8,IL-12 and TNF-αin the IRI group and Dex group were significantly higher(P<0.01),and the concentrations in the Dex group were obviously lower than the IRI group[(231.7±24.8)ng/L vs(292.1±21.8)ng/L,(137.7±9.5)ng/L vs(179.5±13.7)ng/L,(122.4±15.6)ng/L vs(174.6±18.8)ng/L,(681.3±31.2)ng/L vs(734.9±26.3)ng/L](P<0.05).Compared with the sham operation group,the levels of GSH-Px and SOD in the IRI group and Dex group decreased(P<0.01),the levels of MPO and MDA increased(P<0.01);compared with the IRI group,the levels of GSH-Px and SOD in the Dex group increased[(14.42±2.58)kU/g vs(8.71±1.18)kU/g,(64.22±14.37)kU/g vs(51.76±12.81)kU/g](P<0.05),and the levels of MPO and MDA in the Dex group decreased[(12.8±1.83)U/g vs(16.42±2.11)U/g,(6.57±1.17)μmol/g vs(8.64±1.04)μmol/g](P<0.05).Compared with the sham operation group,protein expression levels of HMGB1,TLR4 and NF-κB in the IRI group and the Dex group obviously increased(P<0.01);compared with the IRI group,the protein expression levels of HMGB1,TLR4 and NF-κB in the Dex group obviously decreased[(0.72±0.14)vs(0.97±0.13),(0.84±0.20)vs(1.08±0.22),(0.87±0.21)vs(1.21±0.11)](P<0.01).Conclusion During myocardial IRI,HMGB1/TLR4/NF-κB signaling pathways are activated,and Dex can protect myocardial IRI by inhibiting the signaling pathway,affecting the expression of downstream target molecules and reducing the levels of immune molecules and inflammatory factors.