几丁寡糖对脂肪酸代谢紊乱的抑制作用及分子机制

Inhibition of chitin oligosaccharide on dyslipidemia and the potential molecular mechanism exploration

旨在从细胞学实验及整体动物水平探讨几丁寡糖(NACOS)对机体脂代谢紊乱的抑制作用及其潜在的分子机制。在细胞学实验中,HepG2细胞被分为4组,即对照组、棕榈酸(Palmitic acid,PA)组、几丁寡糖(NACOS)组、NACOS+PA组。在体内实验中,将雄性C57BL/6小鼠随机分为4组(n=5),即正常对照(NCD)组、高脂饮食(HFD)组、NACOS组、NACOS+HFD组,实验共20周。主要检测方法如下:采用油红O染色检测细胞脂质沉积,RT-PCR方法检测脂代谢调控分子及炎症因子的转录表达水平,Western blotting方法检测MAPKs及PI3K/Akt通路中相关蛋白激酶的蛋白磷酸化水平。细胞学实验表明,NACOS对HepG2没有明显的细胞毒性作用,并能显著降低细胞内脂滴颗粒的沉积,下调肝细胞及小鼠肝脏组织中脂代谢相关调控因子(PGC1α、Cox5b及Mcad)及炎症因子IL-1β的转录表达水平(P<0.05或0.01),抑制肝细胞及肝脏组织中p38、ERK1/2及Akt蛋白激酶的激活(P<0.05或0.01)。基于上述研究,NACOS可抑制肝脏线粒体脂肪酸氧化和脂质从头合成途径,阻断炎症反应的发生,从而预防脂代谢紊乱的发生。

The inhibitory effect of NACOS on dyslipidemia and potential molecular mechanisms by in vitro and in vivo experiments were investigated. For in vitro study, four experimental groups were designed by using HepG2 cells, including the control group, palmitic acid （PA） treatment alone group, NACOS treatment alone group and NACOS ＋ PA treatment group. For in vivo study, male C57BL/6 mice were divided into four groups （n=5） at random including the normal control group （NCD）, high fat diet （HFD） group, NACOS treatment alone group, NACOS＋HFD group, which were treated for 20 weeks. The used methods in this study were as follows： the observation of lipid droplet deposition in HepG2 cells by oil red O staining, the detection of mRNA levels of lipid metabolism-related regulators and inflammatory cytokine by RT-PCR method, the monitoring of MAPKs and PI3K/Akt pathway activation by Western blotting method. The in vitro study shows that, NACOS had no toxicity on the viability of HepG2 cells at 25-100 ~tg/mL and significantly reduced the deposition of lipid droplet. Also, based on both in vitro and in vivo investigation, NACOS evidently down-regulated the expression of lipid metabolism-related regulators （PGC let, Cox5b, Mcad） and inflammatory cytokine （IL-113） at mRNA level （P〈0.05 or 0.01）, and suppressed the activation of p38, ERK1/2 and Akt in HepG2 cells and lever tissues from HFD-fed mice （P〈0.05 or 0.01）. Based on the above, NACOS may inhibit the oxidation of liver mitochondrial fatty acid and the lipid biosynthesis, block the inflammatory responses and prevent the HepG2 cells and C57BL/6 mice from lipidemia.