全小麦纤维对载脂蛋白E基因敲除小鼠肝脏脂代谢的影响

目的探讨全小麦纤维通过改善肝脏脂代谢发挥抗动脉粥样硬化(AS)的作用及机制。方法 20只7周龄雄性载脂蛋白E基因敲除(ApoE-/-)小鼠,按体重随机分为AS模型组和全小麦纤维组,同时选相同遗传背景的C57BL/6小鼠作为空白对照组。预防性干预18周后,取主动脉和肝脏进行HE染色,肝匀浆行总胆固醇(TC)、甘油三酯(TG)和游离脂肪酸(FFAs)测定;蛋白质印迹法(Western blot)测定肝脏组织中胆固醇调节元件结合蛋白-1(SREBP-1)、脂肪酸合成酶(FAS)、乙酰辅酶A羧化酶(ACC)以及SREBP-2、低密度脂蛋白受体(LDLR)和B族1型清道夫受体(SR-B1)的蛋白表达水平。结果实验结束时,与空白对照组相比,AS模型组小鼠主动脉内膜明显增生,管腔内大量泡沫细胞和无结构样坏死物,全小麦纤维组小鼠管腔内泡沫细胞减少,粥样斑块面积明显减少;AS模型组小鼠肝脏有明显的肝细胞脂肪变性,全小麦纤维组小鼠肝脏脂肪空泡的数目明显减少,肝细胞脂肪变性有所改善;与AS模型组相比,全小麦纤维组肝匀浆TC水平降低[(60.56±13.49)μmol/g vs.(51.10±5.94)μmol/g](P<0.05);肝脏组织中SREBP-1、FAS、ACC的蛋白表达量降低(P<0.05),SREBP-2和SR-B1的蛋白表达量增加(P<0.05)。结论全小麦纤维可通过调控参与肝脏脂代谢相关蛋白的表达,改善肝脏脂代谢,发挥抗AS作用。

Effects of wheat bran fiber on lipid metabolism in ApoE~(-/-) mice

OBJECTIVE To explore the effect and mechanism of wheat bran fiber on lipid metabolism in ApoE-/-mice fed a high fat diet. METHODS Twenty 7-week-old male ApoE-/-mice were randomly divided into two groups and fed either a high fat diet as AS model group or a high fat diet adding 0.8% wheat bran fiber as W-fiber group. And five C57 BL/6 mice with the same genetic background were used as control group. After 18 weeks feeding, HE staining were performed for atherosclerotic lesions from transverse section of the aorta and hepatic histological examination. Liver homogenate total cholesterol(TC),triglyceride(TG)and free fatty acids(FFAs)were analyzed. Western blot was used to determine the protein expressions involved in hepatic lipid metabolism, including sterol regulatory element binding protein 1(SREBP-1), fatty acid synthase(FAS), acetyl-coA carboxylase(ACC), sterol regulatory element binding protein 2(SREBP-2), low-density lipoproteins receptor(LDLR) and scavenger receptor B1(SR-B1). RESULTS At the end of the experiment, compared with control group, atherosclerotic plaque of the aorta and hepatic steatosis was obvious in the mice of AS model group, and wheat bran fiber alleviated the area of atheromatous plaque and hepatic lipid accumulation. Compared with AS model group, wheat bran fiber decreased liver homogenate TC level((60.56±13.49)μmol/g vs.(51.10±5.94)μmol/g)(P<0.05), reduced protein expression of SREBP-1, FAS and ACC(P<0.05), increased protein expression of SREBP-2和SR-B1(P<0.05). CONCLUSION Taken together, wheat bran fiber can delay the occurance of AS by regulating the related protein expressions involved in lipid metabolism and improving hepatic lipid metabolism.