白杨素通过下调p38-MAPK磷酸化减轻脓毒症大鼠心肌损伤

Chrysin attenuates myocardial injury in a rat septic model via the downregulation of p38-MAPK activity

目的探讨白杨素对脓毒症模型大鼠心肌损伤的作用机制。方法清洁级SD大鼠100只,按随机字母表法分成对照组、模型组、地塞米松组(0.27mg/kg)、白杨素低、高剂量组(20、40mg/kg),每组20只。模型组、地塞米松组、白杨素低、高剂量组建立脓毒症模型;建模成功后,地塞米松组、白杨素低、高剂量组给予相应药物灌胃,对照组及模型组给予等体积生理盐水。连续给药4周后,测定大鼠心功能指标,苏木精-伊红(HE)染色观察大鼠心肌组织病理学变化,实时荧光定量PCR(qRT-PCR)及蛋白免疫印迹(Western blot)测定大鼠心肌p38、磷酸化MAPK(p-MAPK)mRNA和蛋白水平。结果与对照组比较,模型组大鼠左心室舒张末期内径(LVEDD)[(7.86±0.32)mm比(5.69±0.23)mm]、左心室收缩末期内径(LVESD)[(7.16±0.85)mm比(2.99±0.59)mm]、p38 mRNA[(5.41±0.41)比(0.86±0.36)]、p-MAPK mRNA[(5.54±0.39)比(0.83±0.37)]、p38蛋白[(1.32±0.23)比(0.43±0.18)]、p-MAPK蛋白[(1.26±0.19)比(0.40±0.16)]水平升高(P均<0.05),短轴缩短分数(FS)[(27.56±7.59)%比(49.98±7.96)%]、射血分数(EF)[(41.42±6.63)%比(79.43±6.74)%]水平降低(P均<0.05)。与模型组比较,地塞米松组、白杨素低、高剂量组LVEDD[(5.99±0.28)mm、(7.08±0.35)mm、(6.02±0.34)mm比(7.86±0.32)mm]、LVESD[(3.98±0.59)mm、(5.90±0.64)mm、(3.97±0.63)mm比(7.16±0.85)mm]、p38 mRNA[(1.83±0.43)、(3.52±0.46)、(1.82±0.39)比(5.41±0.41)]、p-MAPK mRNA[(2.35±0.31)、(4.34±0.28)、(2.36±0.39)比(5.54±0.39)]、p38蛋白[(0.81±0.20)、(1.04±0.21)、(0.79±0.17)比(1.32±0.23)]、p-MAPK蛋白[(0.75±0.17)、(0.97±0.19)、(0.73±0.18)比(1.26±0.19)]水平降低(P均<0.05),FS[(42.54±5.59)%、(34.48±5.93)%、(41.43±6.85)%比(27.56±7.59)%]、EF[(65.42±11.74)%、(49.62±12.85)%、(64.61±8.85)%比(41.42±6.63)%]水平升高(P均<0.05)。白杨素高剂量组LVEDD、LVESD、FS、EF水平、p38、p-MAPK mRNA和蛋白水平较低剂量组改善更明显(P均<0.05),与地塞米松组比较无明显差异(P>0.05)。结论白杨素能够减轻脓毒症模型大鼠心肌损伤,减轻心肌细胞炎症反应;其机制可能与白杨素显著抑制脓毒症大鼠心肌细胞p38-MAPK磷酸化有关。

Objective To investigate the effect of chrysin on myocardial injury in sepsis rats and the underlying molecular events.Methods A total of 100 Sprague-Dawley rats(a clean grade)were randomly divided into the control,model,and model plus dexamethasone(0.27mg/kg),and model plus low(20mg/kg)and high-dose(40mg/kg)chrysin groups(n=20 per group).The sepsis model groups of rats were subjected to the cecal ligation and perforation(CLP)and dexamethasone and chrysin were administrated for four weeks by oral gavage,while the control and model-only groups were given an equal volume of normal saline.After that,index of the cardiac function was measured and H&E staining was used to assess the histological changes in rat myocardium.Levels of p38 and MAPK mRNA and protein or phosphorylated MAPK protein(p-MAPK)were assessed using quantitative real-time PCR(qRT-PCR)and western blot,respectively.Results Compared with the control group,there was a significantly increased level of the left ventricular end diastolic diameter(LVEDD;7.86±0.32 vs.5.69±0.23mm;P<0.05),the left ventricular end systolic diameter(LVESD;7.16±0.85 vs.2.99±0.59mm;P<0.05),p38 mRNA(5.41±0.41 vs.0.86±0.36;P<0.05),p38 protein(1.32±0.23 vs.0.43±0.18;P<0.05),MAPK mRNA(5.54±0.39 vs.0.83±0.37;P<0.05),and p-MAPK protein(1.26±0.19 vs.0.40±0.16;P<0.05),while a decreased level of of fractional shortening(FS;27.56±7.59 vs.49.98±7.96%;P<0.05)and the ejection fraction(EF;41.42±6.63 vs.79.43±6.74%;P<0.05)in the model group.Moreover,compared with the model group,there was a significant decreased level of LVEDD(5.99±0.28,7.08±0.35,and 6.02±0.34 vs.7.86±0.32mm;all P<0.05),LVESD(3.98±0.59,5.90±0.64,and 3.97±0.63 vs.7.16±0.85mm;all P<0.05),p38 mRNA(1.83±0.43,3.52±0.46,and 1.82±0.39 vs.5.41±0.41;all P<0.05),p38 protein(0.81±0.20,1.04±0.21,and 0.79±0.17 vs.1.32±0.23;all P<0.05),p-MAPK mRNA(2.35±0.31,4.34±0.28,and 2.36±0.39 vs.5.54±0.39;all P<0.05),and p-MAPK protein(0.75±0.17,0.97±0.19,and 0.73±0.18 vs.1.26±0.19;all P<0.05),and a significantly increased level of FS(42.54±5.59,34.48±5.93,and 41.43±6.85 vs.27.56±7.59;all P<0.05)and EF(65.42±11.74,49.62±12.85,and 64.61±8.85 vs.41.42±6.63;all P<0.05)among dexamethasone and low and high-dose chrysin groups.Compared with the low-dose chrysin group,levels of LVEDD,LVESD,FS,EF,and p38 and MAPK mRNA and protein in the high-dose chrysin group were significantly improved(all P<0.05).However,there was no significant difference in LVEDD,LVESD,FS,EF,and p38 and MAPK mRNA and protein between dexamethasone and the high-dose chrysin groups(P>0.05).Conclusion Chrysin was able to alleviate myocardial injury and reduce myocardial inflammatory response in septic rats via the inhibition of the p38-MAPK signaling.