瘤胃異常代謝產物LPS對肝細胞凋亡和脂代謝基因表達的影響

李和平 王月影 楊國宇

摘 要：瘤胃酸中毒對瘤胃微生物和代謝產物產生的影響一直備受關注，但很少有關于瘤胃酸中毒引起的全身效應。高谷物或高脂肪的飲食引起脂多糖（LPS）釋放到胃腸道已涉及反芻動物的脂質代謝紊亂。肝臟對入侵的病原體的急性期反應起著至關重要的作用。SARA引起的內毒素對肝臟脂質代謝的影響尚未明確。選用12只初產薩能奶山羊，隨機分為對照組和LPS組，每組6只，試驗結束后，采集肝臟組織，利用熒光定量PCR的方法檢測肝臟TLR4信號通路關鍵分子、脂肪合成和轉運關鍵基因的表達，闡明LPS對奶山羊肝臟脂代謝關鍵基因表達的影響，為乳脂肪前體物在肝臟的代謝和重分配研究提供理論依據。結果發現LPS能上調TLR4、MyD88、IRAK4和NF-κB基因的表達，下調LXRα、CD36、VLDLR、APOB、ACC和SCD的表達，對LXRβ和PPAR的表達影響不大。提示LPS誘導肝損傷的同時能下調肝臟脂代謝基因的表達，進而降低肝臟合成與轉運脂肪的能力。用LPS處理培養的奶牛肝細胞，發現LPS處理后肝細胞由不規則三角形循環（收縮）變換，收縮的細胞數呈上升趨勢與LPS劑量的增加。提示LPS可促進細胞收縮、脫壁，并最終導致細胞凋亡，肝細胞收縮的數量隨LPS作用時間的延長而增加，利用實時熒光定量PCR檢測肝細胞脂質代謝的關鍵酶基因的表達探討LPS對肝臟脂質代謝的影響，結果發現，LPS介導的TLR4信號通路可抑制脂肪酸合成基因mRNA的表達和增加脂肪酸轉運基因的表達。

關鍵詞：LPS 肝臟 奶山羊 奶牛肝細胞 脂代謝基因

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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