Venkatesan Nandini, Devaraj S Niranjali, Devaraj H
Dept. of Zoology, School of Life Sciences, University of Madras, Guindy Campus, 600025, Chennai, India.
Eur J Nutr. 2003 Oct;42(5):262-71. doi: 10.1007/s00394-003-0420-8.
Research has focussed on the hypocholesterolemic effects of certain types of dietary fiber such as enhancing conversion of hepatic cholesterol to bile acids or increase in catabolism of low density lipoprotein (LDL) via the apo B,E receptor.
The effect of oral administration of a unique fibre cocktail of fenugreek seed powder, guar gum and wheat bran (Fibernat) and its varied effects on some aspects of lipid metabolism and cholesterol homeostasis in rats were examined.
Rats were administered Fibernat along with the atherogenic diet containing 1.5 % cholesterol and 0.1 % cholic acid. Amounts of hepatic lipids, hepatic and fecal bile acids and activity of hepatic triglyceride lipase (HTGL) were determined. Transmission electron microscopic examination of the liver tissue and extent of uptake of (125)I-LDL and (125)I-VLDL by the hepatic apo B,E receptor was carried out.
Food intake and body weight gain were similar between the 3 different dietary groups. Fibernat intake significantly increased apo B,E receptor expression in rat liver as reflected by an increase in the maximum binding capacity (B(max)) of the apo B,E receptor to (125)I-LDL and (125)I-VLDL. The activity of HTGL was increased by approximately 1.5-fold in Fibernat-fed rats as compared to those fed the atherogenic diet alone. A marked hypocholesterolemic effect was observed. Cholesterol homeostasis was achieved in Fibernat-fed rats.
Two possible mechanisms are postulated to be responsible for the observed hypocholesterolemic effect a) an increase in conversion of cholesterol to bile acids and b) possibly by intra-luminal binding which resulted in increased fecal excretion of bile acids and neutral sterols. The resulting reduction in cholesterol content of liver cells coupled with upregulation of hepatic apo B,E receptors and increased clearance of circulating atherogenic lipoproteins-LDL and very low density lipoprotein (LDL and VLDL)-is the main mechanism involved in the hypocholesterolemic effect of Fibernat. The results suggest that Fibernat's effect on plasma LDL concentration is also possibly mediated by increased receptor-mediated catabolism of VLDL. Thus, Fibernat therapy is an effective adjunct to diet therapy and might find potential use in the therapy of hyperlipidemic subjects.
研究聚焦于某些类型膳食纤维的降胆固醇作用，比如增强肝脏胆固醇向胆汁酸的转化，或通过载脂蛋白B、E受体增加低密度脂蛋白（LDL）的分解代谢。
检测口服一种由胡芦巴籽粉、瓜尔豆胶和麦麸组成的独特纤维混合物（Fibernat）的效果，以及其对大鼠脂质代谢和胆固醇稳态某些方面的不同影响。
给大鼠喂食Fibernat，并搭配含1.5%胆固醇和0.1%胆酸的致动脉粥样化饮食。测定肝脏脂质含量、肝脏和粪便中的胆汁酸含量以及肝脏甘油三酯脂肪酶（HTGL）的活性。对肝脏组织进行透射电子显微镜检查，并检测肝脏载脂蛋白B、E受体对（125）I-LDL和（125）I-VLDL的摄取程度。
3个不同饮食组的食物摄入量和体重增加情况相似。Fibernat的摄入显著增加了大鼠肝脏中载脂蛋白B、E受体的表达，这表现为载脂蛋白B、E受体对（125）I-LDL和（125）I-VLDL的最大结合能力（B(max)）增加。与仅喂食致动脉粥样化饮食的大鼠相比，喂食Fibernat的大鼠HTGL活性增加了约1.5倍。观察到明显的降胆固醇作用。喂食Fibernat的大鼠实现了胆固醇稳态。
推测有两种可能的机制导致观察到的降胆固醇作用：a）胆固醇向胆汁酸转化增加；b）可能通过肠腔内结合，导致胆汁酸和中性固醇的粪便排泄增加。肝细胞胆固醇含量的降低，加上肝脏载脂蛋白B、E受体的上调以及循环中致动脉粥样化脂蛋白-LDL和极低密度脂蛋白（LDL和VLDL）清除率的增加，是Fibernat降胆固醇作用的主要机制。结果表明，Fibernat对血浆LDL浓度的影响也可能是通过增加受体介导的VLDL分解代谢来介导的。因此，Fibernat疗法是饮食疗法的有效辅助手段，可能在高脂血症患者的治疗中找到潜在应用。
