二十碳五烯酸抑制小鼠胆囊胆固醇结石形成的作用及分子机制

摘要

Objective To observe the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cholesterol gallstones formation in C57BL/6 mice with diet-induced cholesterol gallstone,and then explore the potential mechanism.Methods Fifty C57BL/6 mice were randomly divided into 5 groups (10 mice in each group),referring to control group,experimental group,experimental plus DHA group,experimental plus EPA group,as well as experimental plus DHA and EPA group.The mice in control group were fed with regular diet,and the rest of the mice with lithogenic diet (LD).Subsequent to feeding the mice with separate diets for two weeks,EPA and/or DHA (70 mg · kg-1 · d-1) were orally administered for eight weeks,while the LD feeding was continued during this period.After a total of 10 weeks,the mice were dissected to observe the gallstone formation.The levels of serum lipids,total cholesterol (TC) and phospholipids (PL) in bile,and TC in the liver were tested,and the protein expression of HMGCR,SRBI,ABCG5/ABCG8,CYP7A1 and ABCB11genes in the liver of mice was measured.Results Compared with the experimental group,the experimental plus EPA group had significantly lower TC in liver (0.033 ±0.008 mmolo/g) and bile (1.807 ±0.381 mmolo/L),and lower relative protein expression levels of HMGCR (0.545±0.098),ABCG5 (0.418±0.089) and ABCG8 (0.501 ±0.151)in liver (P＜ 0.05).The contents of TC in liver and bile,and the protein expression of HMGCR,ABCG5andABCG8 in liver were 0.048 ± 0.006 mmol/g and 2.662 ± 0.339 mmolo/L,and 1.011 ± 0.213,1.037 ± 0.276 and 1.266 ±0.312,respectively.No significant differences were observed between experimental plus DHA group and experimental group (P ＞ 0.05).Conclusions EPA could prevent the cholesterol gallstone formation in mice by decreasing the expression of HMGCR and ABCG5/8 genes in liver,therefore reducing cholesterol synthesis and blocking cholesterol transport from liver to bile as well as diminishing cholesterol content in the bile.However,the inhibition effect of DHA on cholesterol gallstone formation was not obvious.%目的 观察二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)对致结石饮食诱导的C57BL/6小鼠胆囊胆固醇结石形成的影响,并探讨其作用机制.方法 50只C57BL/6小鼠随机分为正常组、模型组、模型+DHA组、模型+EPA组和模型+DHA+EPA组,每组10只.正常组喂食普通饲料,其余各组喂以致结石饮食2周,DHA或(和)EPA(70 mg·kg-1·d-1)灌胃8周.造模10周后,检测各组小鼠血脂水平、胆汁中总胆固醇(TC)、磷脂(PL)以及肝脏TC含量,蛋白印迹法检测各组小鼠肝脏HMGCR、SRBI、ABCG5/ABCG8、CYP7A1和ABCB11基因蛋白表达.结果 模型+EPA组小鼠肝脏及胆汁中TC含量分别为(0.033 ±0.008) mmol/g、(1.807±0.381) mmol/L,明显低于模型组的(0.048±0.006) mmol/g和(2.662±0.339) mmol/L(P值均＜0.05).模型+EPA组小鼠肝脏HMGCR、ABCG5、ABCG8蛋白相对表达量分别为(0.545±0.098)、(0.418 ±0.089)、(0.501±0.151),明显低于模型组的(1.011 ±0.213)、(1.037±0.276)、(1.266±0.312)(P值均＜0.05).模型+DHA组与模型组上述指标差异均无统计学意义(P＞0.05).结论 EPA可通过降低小鼠肝脏HMGCR及ABCG5/8基因表达减少肝脏胆固醇的合成及向胆汁中的转运,降低胆汁中胆固醇的含量,抑制胆囊结石的形成,而DHA抑制胆囊结石形成的作用效果并不明显.