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瘤胃异常代谢产物LPS对肝细胞凋亡和脂代谢基因表达的影响

来源:用户上传      作者: 李和平 王月影 杨国宇

  摘 要:瘤胃酸中毒对瘤胃微生物和代谢产物产生的影响一直备受关注,但很少有关于瘤胃酸中毒引起的全身效应。高谷物或高脂肪的饮食引起脂多糖(LPS)释放到胃肠道已涉及反刍动物的脂质代谢紊乱。肝脏对入侵的病原体的急性期反应起着至关重要的作用。SARA引起的内毒素对肝脏脂质代谢的影响尚未明确。选用12只初产萨能奶山羊,随机分为对照组和LPS组,每组6只,试验结束后,采集肝脏组织,利用荧光定量PCR的方法检测肝脏TLR4信号通路关键分子、脂肪合成和转运关键基因的表达,阐明LPS对奶山羊肝脏脂代谢关键基因表达的影响,为乳脂肪前体物在肝脏的代谢和重分配研究提供理论依据。结果发现LPS能上调TLR4、MyD88、IRAK4和NF-κB基因的表达,下调LXRα、CD36、VLDLR、APOB、ACC和SCD的表达,对LXRβ和PPAR的表达影响不大。提示LPS诱导肝损伤的同时能下调肝脏脂代谢基因的表达,进而降低肝脏合成与转运脂肪的能力。用LPS处理培养的奶牛肝细胞,发现LPS处理后肝细胞由不规则三角形循环(收缩)变换,收缩的细胞数呈上升趋势与LPS剂量的增加。提示LPS可促进细胞收缩、脱壁,并最终导致细胞凋亡,肝细胞收缩的数量随LPS作用时间的延长而增加,利用实时荧光定量PCR检测肝细胞脂质代谢的关键酶基因的表达探讨LPS对肝脏脂质代谢的影响,结果发现,LPS介导的TLR4信号通路可抑制脂肪酸合成基因mRNA的表达和增加脂肪酸转运基因的表达。
  关键词:LPS 肝脏 奶山羊 奶牛肝细胞 脂代谢基因
  Effects of Rumen Abnormal Metabolite LPS on Apoptosis and Expression of Lipid Metabolism in Liver
  Li Heping Wang Yueying Yang Guoyu
  (He'nan Agricultural University)
  Abstract:The influence of ruminal acidosis on ruminal microbiology and metabolite production has received considerable attention, but less is known about systemic manifestations that arise from ruminal acidosis. The lipopolysaccharides(LPS) released in the gastrointestinal tractduring feeding of high-grain or high-fat diets has beenimplicated in the etiology of multiple energy- and lipidrelatedmetabolic disturbances in ruminants. The liver plays a crucial role in the acute phase response to intruding pathogens.The effect of blood LPS in SARAon lipid metabolism in the liver has not yetbeen established.Twelve primiparity Saanen dairy goats were used in this paper, they were randomly divided into control group and LPS group, six goats each group. After end of experiment, liver tissue were obtained. To clarify the effect ofLPSon the expression of lipid metabolism key genes in liver of dairy goats, providing theorical basis for metabolism and re-distribution of milk fat precursor in liver. The expression of key genes for TLR4 signal pathway, lipid synthesize and transport was detected by fluorescence quantitative PCR methods. The results displayed that LPS could up-regulate the expression of TLR4, MyD88, IRAK4 and NF-κB genes, down-regulate the expression of LXRα, CD36, VLDLR, APOB, ACC and SCD genes, no effect on the expression of LXRβand PPAR genes. It suggested that LPS induced liver injury, and could up-regulate the expression of lipid metabolism genes in liver, and then decreased the ability of lipid synthesize and transport in liver.Cell cultures were observed and photographed using an inverted microscope.The results showed that hepatocytechanged from irregular triangle to circular (contraction) transformation, contractioncell number showed increasing trendwith the increasing doses of LPS. These suggested that LPS can promote cell contraction and take off the wall, and ultimately lead to cellapoptosis, with the time of LPS action, the number ofhepatocytesalso changes. We explored lipid metabolism in the liver by using qRT-PCR to detect lipid metabolism key enzymes gene expression in hepatocytes. We found that TLR4 signaling pathway mediated by LPS canattenuate mRNA expression of fatty acid synthesis genes and increase fat acid transport genes in dairy cow primary hepatocyte following LPS treatment.
  Key Words:LPS; Liver; Dairy goat; Dairy cow hepatocyte; Lipid metabolism gene
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