谷物膳食纤维对高胆固醇饮食小鼠脂质代谢及肠道菌群的影响

Effects of Grain Dietary Fiber on Lipid Metabolism and Intestinal Microflora in Mice with High Cholesterol Diet

本研究旨在探讨谷物膳食纤维(DF)对高胆固醇饮食小鼠的脂质代谢和肠道菌群的影响。选取C57BL/6J小鼠30只,并根据体重随机分为4组,分别饲喂基础饲粮(对照,CO组,n=8)、基础饲粮+5 g/kg DF(CO+DF组,n=8)、高脂高胆固醇饲粮(HF组,n=7)及高脂高胆固醇饲粮+5 g/kg DF(HF+DF组,n=7)。试验期8周,测定各组小鼠生长性能、血清和肝脏生化指标、粪便总胆固醇(TC)、短链脂肪酸(SCFA)、相关肝脏胆固醇和胆汁酸(BA)蛋白表达及肠道菌群。结果表明:1)CO+DF组的最终体重显著低于CO组(P<0.05),与HF组相比,CO组和HF+DF组的4周和最终体重均显著降低(P<0.05),肝脏和脂肪的重量显著减少(P<0.05)。且与HF组相比,DF+HF组摄食效率显著降低(P<0.05)。2)CO+DF组血清TC、甘油三酯(TG)含量及天冬氨酸转氨酶(AST)和丙氨酸转氨酶(ALT)活性以及肝脏TC和TG含量显著低于CO组(P<0.05),CO组和HF+DF组显著低于HF组(P<0.05),粪便TC含量仅在HF+DF组显著低于HF组(P<0.05)。3)DF对肝脏胆固醇调节元件结合蛋白-2(SREBP-2)、3-羟基-3-甲基戊二酰辅酶A还原酶(HMGR)、肝脏X受体α(LXRα)、微管相关蛋白1轻链3-Ⅰ(LC3-Ⅰ)和微管相关蛋白1轻链3-Ⅱ(LC3-Ⅱ)蛋白表达没有显著影响(P>0.05)。CO+DF组肝脏胆固醇7-羟化酶(Cyp7a1)的蛋白表达水平显着低于CO组(P<0.05),但HF组和HF+DF组之间没有显著差异(P>0.05)。4)HF+DF组的粪便总SCFA和丙酸盐含量显著高于HF组(P<0.05)。与相应的对照组相比,CO+DF组和HF+DF组的粪便丁酸盐含量显著增加(P<0.05)。5)在门水平上,DF组厚壁菌门(Firmicutes)相对丰度减少,HF+DF组的拟杆菌门(Bacteroidetes)相对丰度高于HF组。梭状芽孢杆菌属ⅪⅤa(ClostridiumⅪⅤ)相对丰度在CO+DF组和HF+DF组显著增加(P<0.05)。此外,与其他组相比,仅HF+DF组中阿克曼菌属(Akkermansia)相对丰度显著增加(P<0.05)。由此可见,每千克饲粮添加5 g DF可降低饲喂含脂45%饲粮小鼠的体重和肝脏脂肪含量,降低血清TC、TG含量及AST和ALT活性以及肝脏TC和TG含量,降低胆固醇合成相关蛋白Cyp7a1的表达水平,提高总SCFA含量及肠道有益菌群和优势菌群相对丰度。

The purpose of this study was to investigate the effects of grain dietary fiber(DF)on lipid metabolism and intestinal flora in mice with high cholesterol diet.Thirty C57BL/6J mice were selected and randomly divided into four groups according to body weight.They were fed a basal diet(CO group,n=8)and the basal diet+5 g/kg DF(CO+DF group,n=8),high fat and high cholesterol diet(HF group,n=7)and the high fat and high cholesterol diet+5 g/kg DF diet(HF+DF group,n=7).The experiment period was 8 weeks,and the growth performance,serum and liver biochemical indicators,the contents of fecal total cholesterol(TC),short-chain fatty acid(SCFA),related liver cholesterol and bile acid(BA)protein expression and intestinal flora of each group were measured.The results showed as follows:1)the final body weight in the CO+DF group was significantly lower than that in the CO group(P<0.05).Compared with the HF group,the CO group and the HF+DF group had significant reductions in body weight at 4 weeks and final(P<0.05),and the weights of liver and fat were significantly reduced(P<0.05).Compared with the HF group,the feeding efficiency in DF+HF group significantly reduced(P<0.05).2)The contents of TC,triglyceride(TG),the activities of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)in serum and the contents of TC and TG in liver in CO+DF group were significantly lower than those in CO group(P<0.05),CO group and HF+DF group were significantly lower than HF group(P<0.05),fecal TC content in HF+DF group was significantly lower than that in the HF group(P<0.05).3)DF did not affect the protein expression of sterol regulatory element binding protein-2(SREBP-2),3-hydroxy-3-methylglutaryl coenzyme A reductase(HMGR),liver X receptorα(LXRα),microtubule-associated protein 1 light chain 3(LC3-Ⅰ)and-Ⅱ(P>0.05).The expression level of cholesterol 7α-hydroxylase(Cyp7a1)in the CO+DF group was significantly lower than that in the CO group(P<0.05),but there was no significant difference between the HF and HF+DF groups(P>0.05).4)The fecal total SCFA and propionate contents in the HF+DF group were significantly higher than those in the HF group(P<0.05).Compared with the corresponding control group,the fecal butyrate content in the CO+DF and HF+DF groups increased significantly(P<0.05).5)At the phylum level,DF reduced Firmicutes relative abundance,and the relative abundance of Bacteroidetes in the HF+DF group was significantly higher than that in the HF group.The relative abundance of ClostridiumⅪⅤa was significantly increased in the CO+DF and HF+DF groups(P<0.05).In addition,compared to other groups,only the relative abundance of Akkermansia in the HF+DF group increased significantly(P<0.05).In conclusion,it’s shown that adding 5 g DF per kilogram of diet can reduce body weight and fat content of mice fed 45%fat diet,reduce the contents of TC and TG and the activities of AST and ALT in serum,the contents of TC and TG in liver,reduce the expression level of cholesterol synthesis-related protein Cyp7a1,and increase total SCFA content,intestinal beneficial flora and the relative abundance of dominant flora.