齐留通对大鼠心肌缺血再灌注炎症损伤的抑制作用观察

Inhibitory effect of zileuton on inflammatory injury to myocardium following ischemia/reperfusion in rats

目的探讨5-脂氧合酶(5-LO)选择性抑制剂齐留通(zileuton)对缺血再灌注心肌的保护作用及其可能机制。方法健康成年雌性SD大鼠30只,随机分为假手术组(S组,n=10)、缺血再灌注组(I/R组,n=10)、齐留通组(Z组,n=10),采用结扎前降支造成缺血45min、松开结扎线灌注120min的方法建立缺血再灌注模型。Z组于手术前15min给予3mg/kg齐留通。再灌注结束后处死动物,HE染色观察心肌的病理损伤情况,TUNEL法检测心肌细胞凋亡率,ELISA法检测血浆中白三烯B4(LTB4)、IL-1β、TNF-α的含量,Western blotting和免疫荧光法检测中性粒细胞中的5-LO分布变化。结果与I/R组比较,齐留通处理可以明显减轻缺血再灌注所致的心肌病理损伤,降低心肌细胞凋亡率,降低血浆中炎症因子LTB4、IL-1β和TNF-α的水平,抑制5-LO的激活转位,差异有统计学意义(P<0.05),但各组5-LO表达总量无明显差异(P>0.05)。结论齐留通对缺血再灌注心肌具有一定的保护作用,其机制可能与抑制5-LO转位激活,进而减轻炎症损伤、抑制心肌凋亡有关。

Objective To investigate the protective effect of zileuton, an inhibitor of 5-1ipoxygenase （5-LO）, on ischemia/ reperfusion （I/R） injury of rat myocardium, and its probable mechanisms. Methods Thirty female SD rats were randomly divided into 3 groups （10 each）： sham group （S group）, ischemic/reperfusion group （I/R group）, and zileuton group （Z group）. The I/ R model was reproduced by left anterior descending （LAD） artery occlusion for 45min followed by 120-min reperfusion. To rats of Z group 3mg/kg zileuton was given 15min before ischemia. Animals were sacrificed after reperfusion. The degree of myocardial damage was determined by means of pathological examination. Myocardial apoptosis was identified by TUNEL assay. The levels of leukotriene B4 （LTB4）, interleukin-1β（IL-1β） and tumor necrosis factor-a （TNF-a） in plasma were determined by ELISA; the distribution of 5-LO in neutrophils was determined by immunofluorescence and Western blotting. Results Compared with I/ R group, zileuton attenuated the I/R-induced myocardial damage significantly. TUNEL assay demonstrated a significant decrease in myocardial apoptosis by zileuton （P〈0.05）. Inflammatory cytokines, including LTB4, IL-1βand TNF-a in the plasma were significantly decreased in Z group than in I/R group （P〈0.05）. Additionally, immunofluoiescence and Western blotting showed that zileuton significantly inhibited the activation and redistribution of 5-LO （P〈0.05）. However, no significant difference in total 5-LO protein expression was found among the three groups （P〉0.05）. Conclusion Zileuton may protect myocardium from I/R injury in rats through suppressing myocardial apoptosis and inflammation by inhibiting the S-LO activation and redistribution.