琥珀酸脱氢酶抑制剂对内毒素血症大鼠心肌组织内琥珀酸代谢和炎性损伤的影响

Effects of succinate dehydrogenase inhibitor on succinate metabolism and inflammatory injury in myocardial tissue of endotoxemic rats

目的探讨琥珀酸脱氢酶抑制剂对内毒素血症大鼠心肌组织内琥珀酸代谢和炎性损伤的影响。方法 SPF级健康雄性SD大鼠40只,体质量200~220 g,采用随机数字表法,将大鼠随机分为4组(n=10):正常对照组(C组)、琥珀酸脱氢酶抑制剂(丙二酸二甲酯)对照组(DC组)、内毒素血症组(E组)和抑制剂+内毒素血症组(DE组)。E组和DE组腹腔注射脂多糖(lipopolysaccharide, LPS)20 mg/kg建立内毒素血症模型,C组和DC组给予等容量生理盐水。LPS处理4 h后,DC组和DE组大鼠腹腔注射琥珀酸脱氢酶抑制剂160 mg/kg,C组和E组给予等容量生理盐水。采用ELISA检测血清肌钙蛋白I(cTnI)浓度以及心肌组织肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)和白介素-1β(interleukin-1β,IL-1β)的含量。采用琥珀酸含量检测试剂盒检测心肌组织内琥珀酸的含量。采用Western blot法和免疫荧光法检测琥珀酸脱氢酶的表达。采用Western blot检测心肌组织核因子κB抑制蛋白-α(inhibitor of NF-κB,IκB-α)磷酸化程度和缺氧诱导因子-1α(hypoxia inducible factor-1α,HIF-1α)的表达。结果与C组比较,E组和DE组大鼠血清cTnI浓度、心肌组织琥珀酸、琥珀酸脱氢酶、IκB-α磷酸化程度、HIF-α、TNF-α和IL-1β水平显著升高(P<0.05)。与E组比较,DE组大鼠血清cTnI浓度及心肌组织琥珀酸、IκB-α磷酸化程度、HIF-α、TNF-α和IL-1β水平显著降低(P<0.05)。结论内毒素血症大鼠心肌组织内琥珀酸和琥珀酸脱氢酶含量显著升高,抑制琥珀酸脱氢酶活性可有效降低琥珀酸的堆积,进而可能通过抑制NF-κB和HIF-1α通路降低心肌组织内炎性细胞因子的产生。

Objective To investigate the effects of succinate dehydrogenase(SDH) inhibitor on succinate metabolism and inflammatory injury in myocardial tissue of endotoxemic rats. Methods Forty specific pathogen free male Sprague-Dawley rats, weighing 200~220 g, were randomly divided into 4 groups(n=10): saline treatment group(group C), SDH inhibitor dimethyl malonate(DMM)+saline treatment group(group DC), LPS treatment group(group E) and DMM+LPS treatment group(group DE). Lipopolysaccharide(LPS, 20 mg/kg) was intraperitoneally injected to rats in group E and DE to establish the endotoxemia model. After LPS administration for 4 h, the rats in the group DC and DE were treated with DMM(160 mg/kg) through intraperitoneal injection. After DMM administration for 4 h, the serum level of cardiac troponin I(cTnI), and the contents of TNF-α and IL-1β in myocardial tissue were detected with enzyme-linked immunosorbent assay. The myocardial succinate level was determined with a commercial succinate detection kit. The myocardial SDH expression was detected with Western blotting and immunofluorescence assay. The myocardial expression levels of hypoxia inducible factor-1α(HIF-1α), phosphorylated inhibitor of NF-κB(p-IκB-α) and total IκB-α were determined with Western blotting. Results Compared with those in group C, the levels of cTnI, succinate, SDH, HIF-1α, p-IκB-α, TNF-α and IL-1β were significantly elevated in group E and group DE(P<0.05). And the levels of cTnI, succinate, TNF-α, IL-1β, HIF-1α and p-IκB-αe were markedly decreased in the group DE than the group E(P<0.05). Conclusion The myocardial contents of succinate and SDH are remarkably increased in endotoxemic rats. SDH inhibition with DMM can effectively attenuate the accumulation of succinate and subsequently alleviate the productions of TNF-α and IL-1β, which possibly through suppressing the NF-κB and HIF-1α pro-inflammatory pathway.