Bravo E, Flora L, Cantafora A, De Luca V, Tripodi M, Avella M, Mayes P A, Botham K M
Instituto Superiore di Sanita, Laboratory of Metabolism and Pathological Biochemistry, Rome, Italy.
Eur J Biochem. 1997 May 15;246(1):92-102. doi: 10.1111/j.1432-1033.1997.t01-2-00092.x.
The fate of [3H]cholesterol carried in chylomicrons prepared from rats given a meal of palm oil (rich in long-chain saturated fatty acids), olive oil (rich in monounsaturated fatty acids) or corn oil (rich in n-6 polyunsaturated fatty acids) was investigated in vivo in rats fed a low-fat diet or a diet supplemented with the corresponding oil (to provide 40% of the calories) for 21 days. In the low-fat-fed groups, radioactivity was removed from the blood and secreted into bile over 180 min more rapidly when the chylomicrons were derived from corn oil as compared to palm or olive oil. After feeding the corresponding high-fat diets, however, both parameters were decreased in rats fed palm and corn oil, but not olive oil. As a result of these changes, the rates of removal of radioactivity from the blood and secretion into bile were similar in animals given the olive oil and corn oil diets, and higher than those in rats fed the palm oil diet. All the high-fat diets tended to increase the proportion of the radioactivity in the plasma found in the 1.006-1.050-g/ml fraction (low-density lipoprotein) and decrease that in the 1.050-1.25-g/ml (high-density lipoprotein) fraction in comparison to the respective low-fat diet groups, but the transfer of radioactivity to the plasma high-density lipoprotein fraction was particularly slow in palm-oil-fed rats. These findings indicate that diets high in saturated or n-6 polyunsaturated fat retard the metabolism of chylomicron cholesterol in comparison to diets low in fat, while those high in monounsaturated fat do not have this effect. As a consequence of this, the rate of removal of cholesterol of dietary origin from the body is slower in animals fed saturated as compared to monounsaturated or n-6 polyunsaturated fat. Thus, differential metabolism of chylomicron cholesterol clearly plays an important role in the hyper- and hypo-cholesterolaemic effects of these dietary fats.
研究了用棕榈油（富含长链饱和脂肪酸）、橄榄油（富含单不饱和脂肪酸）或玉米油（富含n-6多不饱和脂肪酸）喂养大鼠后制备的乳糜微粒中[3H]胆固醇的体内命运。将大鼠分为低脂饮食组或补充相应油脂（提供40%热量）的饮食组，持续喂养21天。在低脂喂养组中，与棕榈油或橄榄油来源的乳糜微粒相比，当乳糜微粒来源于玉米油时，放射性在180分钟内从血液中清除并分泌到胆汁中的速度更快。然而，在喂养相应的高脂饮食后，喂食棕榈油和玉米油的大鼠的这两个参数均降低，但喂食橄榄油的大鼠未出现这种情况。由于这些变化，喂食橄榄油和玉米油饮食的动物从血液中清除放射性和分泌到胆汁中的速度相似，且高于喂食棕榈油饮食的大鼠。与各自的低脂饮食组相比，所有高脂饮食都倾向于增加血浆中1.006 - 1.050 g/ml部分（低密度脂蛋白）中放射性的比例，并降低1.050 - 1.25 g/ml（高密度脂蛋白）部分中的放射性比例，但在喂食棕榈油的大鼠中，放射性向血浆高密度脂蛋白部分的转移特别缓慢。这些发现表明，与低脂饮食相比，富含饱和或n-6多不饱和脂肪的饮食会延缓乳糜微粒胆固醇的代谢，而富含单不饱和脂肪的饮食则没有这种作用。因此，与喂食单不饱和或n-6多不饱和脂肪的动物相比，喂食饱和脂肪的动物从体内清除膳食来源胆固醇的速度较慢。因此，乳糜微粒胆固醇的差异代谢显然在这些膳食脂肪的高胆固醇血症和低胆固醇血症作用中起着重要作用。
