摘要目的 观察木犀草素对葡聚糖硫酸钠(DSS)诱导的小鼠溃疡性结肠炎(UC)的干预作用.方法 3％ DSS溶液诱导小鼠UC模型,40只C57BL/6小鼠随机均分为正常对照组、DSS模型组、木犀草素低、中、高剂量组,进行疾病活动指数评分(DAI);比较各组小鼠结肠长度,苏木素-伊红染色观察结肠组织病理变化;反转录-聚合酶链反应(RT-PCR)检测核因子相关因子2(Nrf2)、血红素加氧酶-1(HO-1)、苯醌氧化还原酶(NQO1)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)mRNA水平;Western blot检测核内Nrf2蛋白含量.结果 木犀草素各剂量组DAI明显低于DSS模型组[(3.17±0.65)、(2.03 ±0.40)、(1.27±0.25)分比(3.90±0.36)分,P=0.046、0.000、0.000];木犀草素各剂量组不同程度抑制结肠缩短[(4.27±0.75)、(5.17±0.35)、(5.97±0.50) cm比(3.67±0.65) cm],中、高剂量组与DSS模型组比较差异有统计学意义(P =0.003、0.001);结肠组织病理结果显示,木犀草素各剂量组病变程度较DSS模型组均减轻;RT-PCR结果显示,木犀草素各剂量组Nrf2、HO-1、NQO1含量较DSS模型组(0.18±0.08、0.16±0.13、0.19±0.10)均升高,差异有统计学意义(P =0.025、0.000、0.000;P=0.002、0.000、0.000;P=0.049、0.038、0.001);TNF-α、IL-6水平较DSS模型组(1.59±0.47、2.02±0.36)均下降,差异有统计学意义(P =0.005、0.002、0.001;P =0.002、0.000、0.000).Western blot结果显示,与DSS模型组比较,木犀草素各剂量组Nrf2核内蛋白含量明显增加,差异有统计学意义(0.13±0.62比0.28±0.50、0.37±0.80、0.51±0.92,P=0.026、0.002、0.000).结论 木犀草素干预能减轻实验性小鼠UC,其机制可能为激活Nrf2信号通路,促进Nrf2入核,进而上调下游靶基因HO-1、NQO1 mRNA水平,抑制促炎因子TNF-α、IL-6 mRNA的表达,增强结肠抗氧化活性,调控氧化/抗氧化平衡.

abstractsObjective To investigate the effects of luteolin ondextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice.Methods Experimental acute colitis was induced by administering 3％ DSS in the drinking water.40 C57BL/6 mice were randomly divided into normal control group,DSS model group,low,medium,high-dose luteolin groups.The disease activity index (DAI),colon length,histological assessment,mRNA expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2),heme oxygenase-1 (HO-1),nicotinamide adenine dinucleotide phosphate (NADPH),quinone oxidoreductase 1 (NQO1),tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6),protein expression of Nrf2 were examined.Results Treatment with luteolin markedly attenuated the DAI compared with DSS model group (3.17±0.65,2.03 ±0.40,1.27 ±0.25 vs.3.90 ±0.36,P=0.046,0.000,0.000);Administration of luteolin ameliorated colon shortening on different levels (4.27 ± 0.75,5.17 ± 0.35,5.97 ± 0.50 vs.3.67 ± 0.65),medium,high-dose luteolingroups had significant difference in comparison with DSS model group (P =0.003,0.001);Histopathological analysis showed that luteolin effectively reduced histological alterations;reverse transcriptase-polymerase chain reaction (RT-PCR) displayed that luteolin activated the expression of Nrf2 and its downstream targets,including HO-1,NQO1 compared with DSS model group (0.18 ±0.08,0.16 ±0.13,0.19 ±0.10).Luteolin also significantly (P =0.005,0.002,0.001;P=0.002,0.000,0.000);reduced the levels of TNF-α,IL-6 in comparison with DSS model group (1.59 ± 0.47,2.02 ± 0.36).Western blotting shown that compared with DSS model group,luteolin significantly elevated the nuclear protein expression of Nrf2 (0.13 ±0.62 vs.0.28 ± 0.50,0.37±0.80,0.51 ±0.92;P=0.026,0.002,0.000).Conclusion Administration of luteolin has protective effect on experimental colitis,maybe the mechanism is activating Nrf2 signaling pathway,promoting Nrf2 into nucleus and elevating mRNA levels of its downstream targets HO-1 and NQO1,suppressing mRNA expressions of TNF-α,IL-6,thus enhancing colon antioxidant ability and regulating the oxidation/antioxidant balance.