【作者】 王剑萍；

【导师】 徐德祥；

【作者基本信息】 安徽医科大学 ， 劳动卫生与环境卫生学， 2006， 硕士

【摘要】 目的 研究慢性乙醇接触对小鼠肝脏孕烷X受体（PXR）和Cyp3all基因表达及CYP3A同工酶—红霉素N-脱甲基酶（ERND）活性的影响，并初步探讨肠源性细菌内毒素和Kupffer细胞在此过程中的作用。 方法 为探讨慢性乙醇接触对小鼠肝脏PXR和Cyp3all基因表达及ENRD活性的影响，将雌性ICR小鼠随机分为单纯乙醇高、中、低剂量组和生理盐水对照组。单纯乙醇不同剂量组每天灌胃给予小鼠不同剂量的乙醇（1，2，4 g／kg），生理盐水对照组每天灌胃给予等容量的生理盐水。为探讨肠源性细菌内毒素在慢性乙醇接触下调小鼠肝脏PXR和Cyp3all中的作用，乙醇+抗生素组小鼠于每天给予乙醇前0.5h灌胃给予0.15g／kg的多粘菌素B和0.45 g／kg的新霉素以抑制肠道细菌的生长。为探讨Kupffer细胞在慢性乙醇接触下调小鼠肝脏PXR和Cyp3all中的作用，每天灌胃给予小鼠4g／kg乙醇的同时，每周两次经尾静脉注射给予GdCl₃（10mg／kg）。连续灌胃5w后剖杀小鼠取肝脏组织，用Trizol一步法提取总RNA，用逆转录多聚酶联反应（RT-PCR）检测PXR和Cyp3all mRNA水平。用钙沉淀法制备肝脏微粒体，Nash法检测ENRD活性。 结果 小鼠连续灌胃给予不同剂量的乙醇5w后，肝脏PXR和Cyp3all mRNA水平显著下降并呈明显的剂量-效应关系，慢性乙醇接触也明显抑制小鼠肝脏微粒体ERND活性。抗生素预处理显著降低慢性乙醇接触引起的小鼠血清内毒素水平升高并降低慢性乙醇接触引起的小鼠肝脏CD14和TLR4 mRNA表达。进一步研究发现，抗生素预处理显著逆转慢性乙醇接触对小鼠肝脏PXR和Cyp3all基因表达和ERND活性的下调。GdCl₃处理显著抑制慢性乙醇引起的TNF-α、IL-1β和IL-6mRNA表达。GdCl₃处理显著逆转慢性乙醇接触引起的小鼠肝脏PXR和Cyp3all更多还原

【Abstract】 Objective To investigate the effects of chronic ethanol exposure on the expressions of PXR and Cyp3a11 mRNA and erythromycin N-demethylase （ERND） activity and to explore the role of bacterial endotoxin and Kupffer cells in chronic ethanol-induced downregulation of PXR and Cyp3a11.Methods To investigate the effects of chronic ethanol exposure on the expressions of PXR and its target gene Cyp3a11 in mouse liver, female ICR mice were administered by gavage with different doses （1,2 and 4 g/kg） of ethanol daily for five weeks. To investigate the role of bacterial endotoxin in chronic ethanol-induced downregulation of PXR and Cyp3a11, mice were pretreated with polymyxin B （150 mg/kg/day, po） plus neomycin （450 mg/kg/day, po） to prevent growth of intestinal bacteria. To determine the role of Kupffer cells in downregulation of PXR and Cyp3a11, mice were administered twice weekly with GdCl₃ （10 mg/kg, iv）, a selective Kupffer cell toxicant, to inactivate Kupffer cells. Mouse livers were excised for total RNA extraction and microsome isolation. PXR and Cyp3a11 mRNA levels were measured using RT-PCR. ERND catalytic activity was measured using Nash method.Results Chronic ethanol exposure significantly inhibited the expressions of hepatic PXR and Cyp3a11 mRNA in a dose-dependent manner. Consistent with the downregulation of PXR and Cyp3a11 mRNA, chronic ethanol exposure also significantly decreased ERND activity. Treatment with antibiotics significantly decreased plasma endotoxin concentration and hepatic CD14 and TLR4 mRNA level.更多还原