运动对2,3,7,8-四氯二苯并二噁英持续暴露大鼠肝脏氧化应激的影响

为探索运动对2,3,7,8-四氯二苯并二噁英(2,3,7,8-TCDD)持续暴露大鼠肝脏氧化应激的影响,本研究将7周龄雄性SD大鼠适应性喂养1周后,随机分为对照(NC)、运动对照(EC)、染毒1(NT1)、运动染毒1(ET1)、染毒2(NT2)、运动染毒2(ET2)、染毒3(NT3)、运动染毒3(ET3)、染毒4(NT4)及运动染毒4(ET4)共10组。染毒组(NTs、ETs)腹腔注射TCDD(溶于玉米油),对照组及各染毒组首次剂量依次为0、0.4、1.6、6.4、25.6μg·kg~(-1)(以单位体重计),之后每周给予上述剂量的21%作为维持剂量,持续染毒8周;运动组尾部负重5%游泳,每周5 d,每次30 min。实验结束取材,测定血清丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、肝组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性及丙二醛(MDA)、活性氧(ROS)含量。结果显示:1)染毒可升高各染毒组大鼠血清AST活性及NT4组大鼠血清ALT活性,增加NT2、NT3组肝脏MDA含量,而降低NT1、NT2组大鼠血清ALT活性;2)运动可升高大鼠血清AST及ALT活性,增加大鼠肝组织GSH-Px活性;3)运动可升高染毒大鼠血清AST活性(T1剂量),降低染毒大鼠血清ALT活性(T1剂量),降低染毒大鼠血清AST活性(T3剂量),升高染毒大鼠血清ALT活性(T3、T4剂量),增加染毒大鼠肝组织SOD活性(T2、T3剂量)、CAT活性(T1、T2、T3剂量)及GSH-Px活性(T2、T3、T4剂量),降低染毒大鼠肝组织MDA含量(T2、T3、T4剂量)及ROS含量(T1、T3剂量)。结果表明,2,3,7,8-TCDD持续暴露8周可引起大鼠肝细胞氧化应激损伤,并产生剂量依赖效应;而有氧运动可增加2,3,7,8-TCDD持续暴露(T2、T3剂量)大鼠肝组织抗氧化酶活性,有效降低氧化应激损伤而减轻肝毒性。

Effect of Exercise on Liver Redox Status in Continuously 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-Exposed Rats

The aim of this study is to investigate the effects of exercise on liver redox status in continuously 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD)-exposed rats.Seven-week-old male SD rats were randomly divided into ten groups:normal control (NC),exercise control (EC),normal toxic 1 (NT1),exercise toxicl (ET1),normal toxic 2 (NT2),exercise toxic 2 (ET2),normal toxic 3 (NT3),exercise toxic 3 (ET3),normal toxic 4 (NT4),and exercise toxic 4 (ET4).2,3,7,8-TCDD (dissolved in corn oil) were intraperitoneally injected in the first week at the dose of 0,0.4,1.6,6.4 and 25.6 μg·kg-1 in control and toxic groups respectively.Then,a maintenance dosage by 21％ of the first dose for the following 2rd-8th weeks were injected.The rats of exercise groups swam 30 min· d-1 with 5％ weights attached to tails.Serum were collected to determine the activities of the aspartate aminotransferase (AST) and the alanine aminotransterase (ALT).Liver was obtained to determine the activities of the superoxide dismutase (SOD),catalase (CAT) and glutathione peroxidase (GSH-Px),and the concentration of reactive oxidative species (ROS) and malondialdehyde (MDA).The results showed that 1) TCDD increased the activities of serum AST in NTs groups and ALT in NT4 group,decreased the activitivies of serum ALT in NT1 and NT2 groups,and increased the content of liver MDA in NT2 and NT3 groups significantly;2)Exercise increased the activities of serum AST and ALT,and liver GSH-Px;3)Exercise could effectively increase the activities of serum AST (T1 dose) and ALT (T3,T4 dose),liver SOD (T2,T3 dose),CAT (T1,T2,T3 dose) and GSH-Px (T2,T3,T4 dose) induced by TCDD,and decreased the activities of serum ALT(T1 dose) and AST (T3 dose),and the content of liver MDA (T2,T3,T4 dose) and ROS (T1,T3 dose) induced by TCDD.It is suggested that 8 weeks' continuous exposure to TCDD could induce the imbalance of the liver redox status and oxidative stress injury which depended on the dosage of toxic exposure.Aerobic exercise could increase the activities of the liver antioxidant enzyme in continuously TCDD-exposed rats (T2,T3),and reduce the oxidative stress injury effectively.