吗啡对急性心肌缺血大鼠的作用及机制研究

Effect and mechanism of morphine on acute myocardial ischemia in rats

目的研究吗啡对急性心肌缺血大鼠心肌损伤的影响及其机制。方法按照体重将SD大鼠随机分为3组:假手术组、模型组、实验组,每组20只。以诱导局部心肌缺血再灌注法建立大鼠急性心肌损伤模型。在大鼠心肌缺血模型再灌注后,实验组大鼠静脉注射吗啡3 mg·kg^(-1),每天1次,连续5 d;假手术组和模型组静脉注射等量生理盐水。通过超声心动图确定射血分数和左心室缩短分数,氯化三苯基四氮唑(TTC)法检测心肌梗死面积,酶联免疫吸附实验检测大鼠血清中乳酸盐脱氢酶(LDH)、超氧化物歧化酶(SOD)和丙二醛(MDA)的含量,末端标记(TUNEL)染色法检测心肌细胞凋亡,蛋白质印迹法检测心肌组织中磷酸化的JNK(p-JNK)、磷酸化的p38(p-p38)的蛋白表达。结果假手术组、模型组、实验组大鼠心肌射血分数分别为(81.21±2.14)%,(42.56±3.84)%和(61.43±4.89)%;这3组大鼠左心室缩短分数分别为(67.51±5.14)%,(40.11±3.55)%和(50.18±4.78)%;这3组大鼠心肌梗死面积分别为(5.01±0.18)%,(57.34±3.64)%和(23.78±1.98)%;这3组大鼠血清中LDH的含量分别为(5.34±0.26),(28.79±1.67)和(15.64±1.24)nmol·mL^(-1);这3组大鼠血清中MDA的含量分别为(0.78±0.04),(1.89±0.14)和(1.13±0.10)nmol·mL^(-1);这3组大鼠血清中SOD的含量分别为(10.59±0.98),(3.85±0.27)和(6.52±0.43)U·mL^(-1);这3组细胞凋亡率分别为(10.21±0.98)%,(34.65±2.89)%和(26.46±2.34)%;这3组p-JNK蛋白水平分别为0.26±0.02,0.68±0.06和0.35±0.03;这3组p-p38蛋白水平分别为0.31±0.03,0.79±0.07和0.42±0.04。上述指标:模型组与假手术组比较,差异均有统计学意义(均P<0.05);实验组与模型组比较,差异均有统计学意义(均P<0.05)。结论吗啡可减轻急性缺血大鼠的心肌损伤,其机制与抑制JNK/p38信号通路相关。

Objective To study the effect of morphine on myocardial injury in rats with acute myocardial ischemia and its mechanism.Methods The SD rats were randomly divided into three groups according to weight:sham operation group,model group,experimental group,20 rats in each group.A rat model of acute myocardial injury was established by the method of inducing local myocardial ischemia and reperfusion.In the experimental group,after the rat myocardial ischemia model was reperfused,the rats were given intravenous injection of 3mg·kg^(-1),morphine ones a day for 5 d.The sham operation group and the model group should be injected with the same amount of normal saline intravenously.Echocardiography was used to determine the ejection fraction and left ventricular shortening fraction.The area of myocardial infarction was detected by triphenyltetrazolium chloride.The contents of lactate dehydrogenase lactate dehydrogenase(LDH),superoxide dismutase(SOD),malondialdehyde(MDA)in rat serum were detected by enzyme linked immunosorbent assay.The apoptosis were detected by Td T-mediated d UTP Nick end labeling.Western blot was used to detect the protein expression of phosphorylated JNK(p-JNK)and phosphorylated p38(p-p38)in myocardial tissue.Results The myocardial ejection fraction in sham operation group,model group,and experimental group were(81.21±2.14)%,(42.56±3.84)%,and(61.43±4.89)%,respectively;the left ventricular shortening fractions of the three groups of rats were(67.51±5.14)%,(40.11±3.55)%,(50.18±4.78)%,respectively;the myocardial infarction area of the three groups of rats were(5.01±0.18)%,(57.34±3.64)%,(23.78±1.98)%;the levels of LDH in the three groups were(5.34±0.26),(28.79±1.67),(15.64±1.24)nmol·m L-1;the contents of MDA in the three groups of rats were(0.78±0.04),(1.89±0.14),(1.13±0.10)nmol·m L-1;the contents of SOD in the three groups were(10.59±0.98),(3.85±0.27),(6.52±0.43)U·m L-1;the apoptosis rates of these three groups were(10.21±0.98)%,(34.65±2.89)%,(26.46±2.34)%,respectively;the levels of p-JNK protein in these 3groups were 0.26±0.02,0.68±0.06,0.35±0.03,respectively;the p-p38 protein levels in these three groups were0.31±0.03,0.79±0.07,0.42±0.04,respectively.The above indicators:the difference between the model group and the sham operation group was statistically significant(all P<0.05);the experimental group and the model group,the difference was statistically significant(all P<0.05).Conclusion Morphine can alleviate myocardial injury in rats with acute ischemia,and its mechanism is related to the inhibition of JNK/p38 signaling pathway.