【作者】 代国杰；

【导师】 朱建津；

【作者基本信息】 江南大学 ， 营养与食品卫生学， 2009， 硕士

【摘要】 本文研究了褪黑素对LPS刺激小鼠氧化应激和免疫功能的的调节作用,并分析了他们之间的相关性,进一步通过对氧化还原及免疫相关基因的表达的影响探讨其可能的保护机制。选用清洁级三周龄雄性昆明小鼠70只,分成四组:正常组、生理盐水组、低褪黑素组、高褪黑素组。预饲一周后,生理盐水组每天灌胃生理盐水0.2 mL;低褪黑素组每天灌胃1 mg/kg.BW的褪黑素;高褪黑素组每天灌胃2 mg/kg.BW的褪黑素。灌胃三周后,除正常组外,每组均腹腔注射5 mg/kg.BW的LPS 0.2 mL,正常组腹腔注射同剂量的无菌生理盐水,注射后4、16 h,测定机体活性氧(ROS)水平、抗氧化能力;采用ELISA检测血浆中IL-1、TNF-α、IL-10的含量;实时定量PCR检测肝脏金属硫蛋白1(Mt1)、核转录因子-B(NF-κB)、热激蛋白70(HSP70)和转录活化蛋白-1(AP-1)基因表达。实验结果:(1)褪黑素可以显著降低LPS刺激小鼠机体的ROS水平,增强抗氧化酶的活性,提高机体的抗氧化能力。(2)褪黑素可以显著降低LPS刺激小鼠十二指肠MPO活性,抑制血浆炎性细胞因子IL-6、TNF-α分泌,促进抗炎性细胞因子IL-10的分泌,从而减轻机体的炎性损伤。(3)褪黑素可以使LPS刺激小鼠肝脏Mt1 mRNA表达上调、NF-κB mRNA、HSP70 mRNA、AP-1 mRNA表达下调,从而保护机体,改善LPS导致的氧化和炎性损伤。结论:腹腔注射脂多糖,引起机体的急性炎症反应、降低抗氧化能力,导致免疫功能状态失调。而灌胃褪黑素可有效清除LPS诱导的机体过量产生的ROS,提高机体抗氧化能力,并抑制炎性细胞因子的分泌,改善免疫功能。其可能机制为褪黑素通过调节相关基因的表达,改善抗氧化与免疫功能。更多还原

【Abstract】 This investigation was conducted to evaluate the effect of melatonin on the oxidative stress, immune function of mice under the stimulation of lipopolysaccharide, in addition, the possible mechanism was analyzed by the relative gene expression.70 male mice were randomly divided into 4 groups. The control group was fed with basal diet and the other three groups were given with saline respectively, 1mg/kg.BW of Melatonin, 2mg/kg.BW of melatonin. After 3 weeks, the control group was injected with saline intraperitoneally, and the other groups were injected with 0.2ml 5mg/kg.BW of LPS intraperitoneally. After 4 and 16 hours, the ROS levels of blood and organs, the anti-oxidative capacity in plasma and organs were determined. The levels of IL-1, TNF-αand IL-10 in plasma were assayed by ELISA. In order to explore the molecular mechanisms underlying the modulating effect of melatonin on oxidative stress and immune dysfunction induced by LPS, the expression of Mt1, NF-κB, HSP70 and AP-1 in liver of mice by quantitative real-time reverse transcription–polymerase chain reaction was determined by melatonin.The results were as follows: (1) The levels of ROS produced in blood and organs were decreased, and the anti-oxidative capacity of mice under the stimulation of LPS were decreased by melatonin. (2) The contents of inflammatory cytokine interleukin-1 (IL-1) and tumor necrosis factor-α(TNF-α) decreased relatively, and anti-inflammatory cytokine interleukin-10 (IL-10) increased with the supplement of melatonin in mice. (3)The expression of Mt1 in liver significantly lowered and the expressions of NFκB, HSP70 and AP-1 significantly increased in mice under the stimulation of Lipopolysaccharide.Conclusion: Lipopolysaccharide resulted in oxidative stress and dysfunction in immune system. The optimum dose of Melatonin could be able to eliminate the excessive ROS, increase the anti-oxidative capacity, regulate the immune dysfunction of mice under the stimulation of Lipopolysaccharide.更多还原