卫生研究

目的研究灌胃给予二甲基甲酰胺(DMF)对大鼠肝脏抗氧化能力及过氧化物酶体增殖物活化受体(PPAR)α和PPARγ的影响。方法30只雄性8周龄SPF级SD大鼠随机分组,经口灌胃给予DMF 150 mg/kg BW染毒(每组5只),分别在DMF暴露前(D0组),暴露后第1、3、7、14和28天,取外周血进行血常规分析;处死大鼠取肝脏组织,HE染色进行病理观察;试剂盒检测谷胱甘肽过氧化物酶(GSH-Px)及过氧化氢酶(CAT)的水平;采用实时荧光定量PCR方法检测PPARα和PPARγ的mRNA水平;ELISA检测肝脏促炎症细胞因子白介素-1β(IL-1β)、白介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)的水平。结果与D0天(对照组)相比,DMF暴露1天后外周血白细胞水平开始增加[(8.30±0.61)×10⁹/L vs.(12.64±1.02)×10⁹/L,P<0.05],随着暴露时间延长,白细胞水平进一步升高。此外,DMF暴露后可引起显著的肝脏损伤,包括肝细胞肿胀、淋巴细胞浸润、点状坏死等。与D0天相比,GSH-Px在DMF暴露后第一天出现一过性升高[(1006.00±168.60)U vs.(1437.00±321.00)U,P<0.05],CAT在DMF暴露后28天出现显著升高[(35.17±4.90)U/mg蛋白vs.(51.80±10.32)U/mg蛋白,P<0.05]。PPARα和PPARγ的mRNA水平在染毒后第7天出现显著升高[(1.35±1.30)vs.(35.70±10.88),(1.04±0.33)vs.(191.10±44.70),P<0.01]。而PPAR信号通路下游促炎症细胞因子水平(IL-1β、IL-6和TNF-α)降低,其中,与D0天相比,IL-1β在DMF暴露28天显著降低[(34.75±5.94)pg/mL vs.(25.52±1.65)pg/mL,P<0.05],IL-6在DMF暴露14天降低至谷值[(139.10±23.10)pg/mL vs.(97.86±4.15)pg/mL,P<0.01],TNF-α在DMF暴露后持续降低,在暴露28天时最低[(295.40±29.31)pg/mL vs.(217.10±7.43),P<0.01]。结论DMF代谢过程中产生大量ROS,可引起氧化应激能力损伤,导致肝脏炎症,从而负反馈上调PPAR的转录水平,抑制促炎症细胞因子分泌,以减轻炎症反应。

Objective To investigate the effects of N,N-dimethylformamide(DMF)exposure on liver anti-oxidative capacity and peroxisome proliferator activated receptor(PPAR)αand PPARγin rats.MethodsA total of 30 male SD rats were randomly divided into 6 groups and orally administered with DMF 150 mg/kg body weight.Blood and liver tissues were collected on day 0(before DMF exposure),1,3,7,14 and 28 after DMF exposure.Blood were collected for blood routine examination and liver tissues for H&E staining.Glutathione peroxidase(GSH-Px)and catalase(CAT)were detected by kits,the mRNA levels of PPARαand PPARγwere detected by real-time PCR,and proinflammatory cytokines[interleukin-1 beta(IL-1β),interleukin-6(IL-6)and tumor necrosis factor-alpha(TNF-α)]were detected by ELISA kits.ResultsCompared with day 0(control group),white blood cell(WBC)level in blood was significantly increased after 1 day exposure[(8.30±0.61)×10⁹/L vs.(12.64±1.02)×10⁹/L,P<0.05].As exposure time increases,WBC levels were increasing.In addition,DMF causes serious liver damage,including cell swelling,lymphocyte infiltration,and punctuate necrosis.GSH-Px was significantly increased on the first day after DMF exposure[(1006.00±168.60)U vs.(1437.00±321.00)U,P<0.05].However,after DMF exposure,the CAT levels increased significantly on day 28[(35.17±4.90)U/mg vs.(51.80±10.32)U/mg,P<0.05].Compared with day 0,the mRNA levels of PPARαand PPARγwere significantly increased on day 7 after DMF exposure(1.35±1.30 vs.35.70±10.88,1.04±0.33 vs.191.10±44.70,P<0.01).IL-1β,IL-6 and TNF-αdecreased after DMF exposure,in which IL-1β significantly decreased on day 28 after DMF exposure when compared with day 0[(34.75±5.94)pg/mL vs.(25.52±1.65)pg/mL,P<0.05].IL-6 decreased continuously after DMF exposure and the lowest value on day 14 after DMF exposure[(139.10±23.10)pg/mL vs.(97.86±4.15)pg/mL,P<0.01],and TNF-αalso continuously decreased after DMF exposure,and decreased on the bottom value on day 28 after DMF exposure[(295.40±29.31)pg/mL vs.(217.10±7.43)pg/mL,P<0.01].ConclusionA large amount ROS was produced during DMF metabolized by CYP2E1,which can cause oxidative stress and lead to inflammation.Therefore,it negative feedback up-regulates the transcription levels of PPARs and inhibits the proinflammatory cytokines secretions so as to reduce the inflammatory reaction.