中文摘要：

目的：研究槲皮素（quercetin，QUE）预处理对氧化低密度脂蛋白（oxidized low—density lipoprotein，OX-LDL）所致小鼠巨噬细胞脂质蓄积和过氧化的影响，并探讨可能的分子机制。方法：体外培养小鼠RAW264．7巨噬细胞，给予20、40和80p,mol／LQUE预处理30win，再加入OX—LDL（100ms／L）继续培养24h。采用油红O染色检测细胞内脂质蓄积，测定培养液乳酸脱氢酶（1acticdehydrogenase，LDH）、丙二醛（malondialdehyde，MDA）和细胞内活性氧（reactiveoxygenspecies，ROS）水平，以评价细胞膜完整性和脂质过氧化程度。分别采用real-timePCR和免疫印迹技术检测清道夫受体CD36mRNA和蛋白表达变化。结果：QUE（20，40和80μmol／L）预处理显著抑制OX-LDL所诱导的巨噬细胞内脂质蓄积和泡沫细胞形成，且呈浓度依赖性。Ox-LDL组细胞LDH释放增加，而QUE预处理则显著抑制OX．LDL的上述细胞毒性。与OX-LDL组比较，QUE预处理组细胞内ROS含量和培养液中MDA水平明显降低。另外QUE预处理在mRNA和蛋白水平均明显抑制OX-LDL所诱导的CD36表达上调。结论：QUE可减轻OX-LDL所诱导的小鼠巨噬细胞脂质蓄积和过氧化，其机制可能部分是通过下调CD36表达实现的。

英文摘要：

AIM： To investigate the effect of quercetin （QUE） preconditioning on oxidized low-density lipoprotein （ox-LDL） -induced lipid accumulation and peroxidation in mouse RAW264.7 macrophages and the underlying molecular mechanisms. METItODS： RAW264.7 ceils were pretreated with different concentrations （20, 40 and 80 μmol/ L） of QUE for 30 rain and then treated with ox-LDL （ 100 rag/L） for 24 h. Intracellular lipid droplets were assayed by oil red O staining. Extracellular lactate dehydrogenase （LDH） and malondialdehyde （MDA） and intracellular reactive oxygen species （ROS） were determined to characterize the membrane integrity and the lipid peroxidation, respectively. The mRNA and protein levels of CD36, an important scavenger receptor which mediates ox-LDL uptake, were examined by real-time PCR and Western blotting, respectively. RESULTS： Pretreatment with QUE （20, 40 and 80 retooL/L） significantly attenuated ox-LDL-induced lipid accumulation in RAW264.7 ceils and foam cell formation in a dose-dependent manner. Ox-LDL induced LDH release in RAW264.7 cells. This eytotoxie effect was significantly inhibited by QUE pretreatment. Compared with Ox-LDL group, the intracellular ROS content and MDA level in culture medium decreased markedly in QUE group. In addition, pretreatment with QUE attenuated ox-LDL-indueed up-regulation of CD36 at mRNA and protein levels. CONCLUSION： QUE inhibits ox-LDL-induced lipid accumulation and peroxidation in mouse macrophages and the mechanism may partially involve its ability to down-regulate CD36 expression. [