中文摘要：

本试验旨在通过脂多糖（LPS）诱导猪空肠上皮细胞（IPEC-J2）来建立氧化应激模型,探讨壳寡糖（COS）的抗氧化作用效果。采用噻唑蓝（MTT）法检测LPS和COS对IPEC-J2作用12、24、48 h后细胞增殖活性的变化;选择适宜浓度LPS（1.0μg/m L）和COS（200μg/m L）作用于IPEC-J2,分为对照组、LPS组、COS组、LPS＋COS组。采用Western Blot法检测核因子E2相关因子2（Nrf2）、血红素氧合酶-1（HO-1）蛋白的表达;试剂盒检测超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性及丙二醛（MDA）的含量。结果表明：1.0μg/m L的LPS对IPEC-J2作用24 h,细胞增殖的抑制率为41.6%,为造模的最适浓度和作用时间;COS在一定浓度范围内对IPEC-J2有增殖作用,其浓度为200μg/m L时效果最佳,作用时间为24 h时,细胞增殖率达到126.3%。LPS＋COS组较对照组的SOD、CAT活性和M DA含量差异不显著（P〉0.05）,Nrf2和HO-1蛋白相对表达量显著升高（P〈0.05）;LPS＋COS组较LPS组的Nrf2蛋白相对表达量显著升高（P〈0.05）,HO-1有升高趋势,但差异不显著（P〉0.05）,SOD、CAT活性显著升高（P〈0.05）,M DA含量显著降低（P〈0.05）。由此可见,LPS诱导IPEC-J2氧化应激,而COS可进一步促进Nrf2和HO-1蛋白的高表达,并提高抗氧化酶的活性,降低氧化产物含量,从而增强细胞对氧化应激的抵抗力,起到保护作用。

英文摘要：

This study was designed to investigate the effect of chitooligosaccharide（ COS） on oxidative stress and used lipopolysaccharide（ LPS） induced epithelial cells of pig jejunum（ IPEC-J2） as an in vitro model of oxidative stress. The IPEC-J2 were incubated with LPS and COS for 12,24 and 48 h,and then used methylthiazolyldiphenyl-tetrazolium bromide（ MTT） method to detect the activity of cell proliferation; the appropriate concentrations of LPS（ 1.0 μg/m L） and COS（ 200 μg/m L） were chosen in the IPEC-J2 cells,divided into control group,LPS group,COS group and LPS ＋COS group,and then detected the expression of NF-E2-related factor 2（ Nrf2） and heme oxygenase 1（ HO-1） by W estern Blot; and detected superoxide dismutase（ SOD）,catalase（ CAT） activities and malonaldehyde（ MDA） content by the kit. The results showed that the optimum concentration of LPS and incubated time for model was 1. 0 μg/m L and 24 h,the inhibition of cell proliferation was 41.6%; COS promoted the proliferation of IPEC-J2,worked the best when its concentration was 200 μg/m L and incubated 24 h,the cell proliferation rate was 126.3%. Compared with the control group,LPS ＋COS group was not significantly different in SOD,CAT activities and MDA content（ P〈0. 05）,but Nrf2 and HO-1 protein expression was significantly increased（ P〈0. 05）; compared with LPS group,Nrf2 protein expression of LPS ＋COS group was significantly higher（ P〈0. 05）,and there was an increasing trend of HO-1 protein expression,but the difference was not significant（ P〉0.05）,moreover,SOD,CAT activities were significantly increased and MDA content was significantly reduced（ P〈0. 05）. It is concluded that LPS induce oxidative stress of IPEC-J2,but COS can induce high expression of Nrf2 and HO-1 protein,and improve the activity of antioxidant enzymes,reduce the content of oxidative products,so increase cellular resistance to oxidative stress,and play a protective role.