脓毒症大鼠脑线粒体功能损伤与氧化应激的关系

Preliminary study on cerebral mitochondrial dysfunction in septic rats

目的:探索脓毒症脑组织线粒体功能及可能损伤机制.方法:选取40只清洁级雄性SD大鼠(180～220g),以抽签方式随机分为4组:正常对照组,3h脓毒症组(3LPS组),6h脓毒症组(6LPS组)和24h脓毒症组(24LPS组),每组10只.腹腔注射革兰阴性菌脂多糖(LPS)溶液建立脓毒症大鼠动物模型,各脓毒症组大鼠在相应时点处死后分离获得线粒体.测定各组大鼠脑线粒体膜电位、线粒体丙二醛(mtMDA)含量、线粒体一氧化氮合酶(mtNOS)活性以及线粒体一氧化氮(mtNO)浓度.结果:3LPS组大鼠脑线粒体膜电位较正常对照组明显降低[(0.5±0.5)vs(1.2±0.6),P<0.05];6LPS组和24LPS组大鼠脑线粒体膜电位与正常对照组无明显差异[(1.4±0.7)vs(1.2±0.6),(1.6±0.7)vs(1.2±0.6)].3LPS组和6LPS组大鼠脑mtMDA含量较正常对照组明显升高[(12.0±2.1)μmol/Lvs(5.7±0.8)μmol/L,(8.7±0.8)μmol/Lvs(5.7±0.8)μmol/L,P<0.01];24LPS组大鼠脑mtMDA含量较正常对照组无明显差别[(6.5±1.6)μmol/Lvs(5.7±0.8)μmol/L].3LPS组和6LPS组大鼠脑mtNOS活性较正常对照组明显升高[(74±24)μkat/gvs(16±13)μkat/g,P<0.01;(32±10)μkat/gvs(16±13)μkat/g,P<0.05];24LPS组大鼠脑mtNOS活性较正常对照组无明显差别[(28±12)μkat/gvs(16±13)μkat/g].3LPS组、6LPS组和24LPS组大鼠脑mtNO浓度均较正常对照组明显升高[(15.4±4.8)μmol/gvs(1.2±2.6)μmol/g,(6.5±3.8)μmol/gvs(1.2±2.6)μmol/g,(3.6±2.1)μmol/gvs(1.2±2.6)μmol/g,P<0.01].脓毒症大鼠脑mtMDA含量、mtNOS活性和mtNO浓度与脑线粒体膜电位存在明显负相关性(r=-0.677,P<0.01;r=-0.738,P<0.01;r=-0.715,P<0.01).结论:大鼠脓毒症病程中存在可逆性脑线粒体功能损伤;脓毒血症时脑线粒体损伤发生高峰在3～6h;氧化应激是导致脓毒症大鼠脑线粒体功能损伤的主要机制之一,其中mtNOS和mtNO在这一机制中发挥了重要作用.

AIM： To study the pathogenesis of cerebral mitochondrial dysfunction in septic rats. METHODS： Forty clean level SD male rats were randomly divided into 4 groups： control group, 3-h sepsis group, 6-h sepsis group and 24-h sepsis group. The sepsis model was established by intraperitoneal injection of lipopolysaccharide （ LPS, from Escherichia coli 0111 ： B4 ）. Cerebral mitochondrial membrane potential was determined and the levels of MDA, NOS and NO in cerebral mitochondria were also determined. RESULTS： Cerebral mitochondrial membrane potential in 3-h sepsis group decreased significantly compared with that in control group [ （ 0.5 ± 0.5 ） vs （ 1.2 ± 0.6 ） 1. The cerebral mitoehondrial MDA concentration in 3-h and 6-h sepsis groups increased significantly compared with that in control group[ （12.0 ± 2.1 ） txmol/L vs （5.7±0.8） μmol/L, （8.7 ± 0. 8） μmol/L vs （5.7 ±0.8）μmol/L]. The cerebral mitochondrial NOS activity in 3-h and 6-h sepsis groups inereased significantly compared with that in control group[ （74 ± 24） μkat/g vs （ 16 ± 13 ） μkat/g, （ 32 ± 10） μkat/g vs （16 ± 13 ）μkat/g]. The cerebral mitoehondrial NO coneentration in all septic groups increased significantly compared with that in control group[ （15. 4 ±4. 8） μmol/g vs （1.2±2.6）μmol/g, （6.5± 3.8） μmol/g vs （ 1.2 ± 2.6） μmol/g, （ 3. 6 ± 2. 1 ） μ mol/g vs （ 1.2 ±2. 6 ） μmol/g ]. The cerebral mitochondrial MDA, NOS and NO showed significant negative linear correlations with cerebral mitochondrial membrane potential （ r = - 0. 677, P 〈 0. 01 ; r = -0.738, P〈0.01; r= -0.715, P〈0.01）. CONCLUSION： There is reversible cerebral mitochondrial dysfunction in septic rats. Oxidative stress is a main pathogenie eause of eerebral mitochondrial dysfunction in septic rats. mtNOS and mtNO play some important roles in cerebral mitochondria oxidative stress injury.