Spady D K, Woollett L A
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas.
J Lipid Res. 1990 Oct;31(10):1809-19.
These studies were undertaken to determine how polyunsaturated (n-3 and n-6) and saturated triglycerides interact to regulate rates of low density lipoprotein (LDL) production and rates of receptor-dependent and receptor-independent LDL transport. Animals were fed diets containing 20% (by wt) hydrogenated coconut oil or diets in which the coconut oil was progressively removed and replaced with safflower oil or fish oil concentrate. Plasma LDL concentrations fell when either of the polyunsaturated triglycerides was substituted for saturated triglycleride in the diet; however, the reduction in LDL concentrations was greater with fish oil than with safflower oil at all ratios of polyunsaturated to saturated triglyceride that were examined. The lower plasma LDL concentrations when coconut oil was replaced with fish oil could be attributed almost entirely to a much greater increase in hepatic LDL receptor activity when fish oil was used as the substitute than when safflower oil was used as the substitute. To examine the effect of polyunsaturated triglycerides when used to supplement a high saturated fat diet rather than to replace saturated fat in the diet, animals were fed a diet containing 15% coconut oil (by wt) with or without an additional supplement of 5% fish oil or safflower oil. The addition of 15% coconut oil to low fat control diet increased the rate of LDL production causing circulating LDL levels to rise by 40%. The further supplementation of this high saturated fat diet with fish oil concentrate markedly increased hepatic LDL receptor activity causing plasma LDL concentrations to return to control values whereas supplementation with safflower oil had little effect. Thus, at least in the rat, supplementation of a high saturated fat diet with a fish oil concentrate lowers plasma LDL concentrations as effectively as removing the saturated fat from the diet, although in the former case, both the production and the receptor-dependent uptake of LDL are greatly increased.
开展这些研究是为了确定多不饱和脂肪酸（n - 3和n - 6）和饱和甘油三酯如何相互作用来调节低密度脂蛋白（LDL）的生成速率以及受体依赖性和非受体依赖性LDL的转运速率。给动物喂食含20%（重量）氢化椰子油的日粮，或逐渐去除椰子油并用红花油或鱼油浓缩物替代的日粮。当用任何一种多不饱和甘油三酯替代日粮中的饱和甘油三酯时，血浆LDL浓度都会下降；然而，在所检测的多不饱和甘油三酯与饱和甘油三酯的所有比例下，鱼油使LDL浓度的降低幅度都大于红花油。用鱼油替代椰子油时血浆LDL浓度较低，几乎完全可归因于与用红花油替代相比，用鱼油替代时肝脏LDL受体活性有更大幅度的增加。为了研究多不饱和甘油三酯用于补充高饱和脂肪日粮而非替代日粮中饱和脂肪时的作用，给动物喂食含15%（重量）椰子油的日粮，添加或不添加5%的鱼油或红花油。在低脂对照日粮中添加15%的椰子油会增加LDL的生成速率，导致循环LDL水平升高40%。用鱼油浓缩物进一步补充这种高饱和脂肪日粮会显著增加肝脏LDL受体活性，使血浆LDL浓度恢复到对照值，而添加红花油则几乎没有效果。因此，至少在大鼠中，用鱼油浓缩物补充高饱和脂肪日粮降低血浆LDL浓度的效果与从日粮中去除饱和脂肪一样有效，尽管在前一种情况下，LDL的生成和受体依赖性摄取都大幅增加。
