Berlin E, Bhathena S J, McClure D, Peters R C
Metabolism and Nutrient Interactions, Beltsville Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
J Nutr. 1998 Sep;128(9):1421-8. doi: 10.1093/jn/128.9.1421.
Fatty acids in the diet are readily incorporated into lipids in various tissues. However, it is not clear whether all tissues have the same level of incorporation. Second, (n-6) unsaturated fatty acids increase the fluidity of membranes, but this has not been shown for (n-3) fatty acids. In this study, we measured the incorporation of (n-6) and (n-3) fatty acids into erythrocyte membrane lipids and studied their effects on the fluidity of erythrocyte membranes. One group of female miniature swine was made hypercholesterolemic by feeding the swine cholesterol and lard for 2 mo; the other group served as controls and was fed a stock diet. Both groups were then fed either corn oil or menhaden oil or a mixture of the two for 23 additional weeks. Blood was collected at 0, 2, 4, 12 and 23 wk after initialization of the experimental diets, and fatty acid composition of phospholipids was assessed. Membrane phospholipids of pigs fed menhaden oil had elevated (n-3) fatty acids (20:5 and 22:6), and lower 18:2 than those fed corn oil. There was no difference in 20:4 content. The fatty acid changes occurred as early as 2 wk after consumption of the corn oil or menhaden oil in pigs previously fed a stock diet, but it took longer in pigs previously fed lard + cholesterol, indicating residual effects of pretreatment. Menhaden oil increased anisotropy (indicating decreased fluidity) more than corn oil for the nonpolar probe diphenylhexatriene (DPH) at earlier time points, but not at 23 wk. Erythrocyte membrane fluidity was significantly related to membrane polyunsaturate content, with (n-6) fatty acids having a greater influence than (n-3) fatty acids. A comparison of the present red blood cell fatty acid compositions with brain synaptosome fatty acid compositions for the same animals showed poor correlations for some of the fatty acids. There was no significant direct relationship between docosahexaenoate (DHA) concentrations in erythrocyte membranes with DHA concentrations in brain synaptosomes from cerebellum, forebrain and caudate nucleus.
饮食中的脂肪酸很容易被纳入各种组织中的脂质中。然而，尚不清楚所有组织的纳入水平是否相同。其次，（n-6）不饱和脂肪酸会增加膜的流动性，但（n-3）脂肪酸尚未显示出这种作用。在本研究中，我们测量了（n-6）和（n-3）脂肪酸纳入红细胞膜脂质的情况，并研究了它们对红细胞膜流动性的影响。一组雌性小型猪通过喂食胆固醇和猪油2个月使其患高胆固醇血症；另一组作为对照，喂食常规饲料。然后两组再额外喂食23周玉米油或鲱鱼油或两者的混合物。在实验性饮食开始后的0、2、4、12和23周采集血液，并评估磷脂的脂肪酸组成。喂食鲱鱼油的猪的膜磷脂中（n-3）脂肪酸（20:5和22:6）含量升高，18:2含量低于喂食玉米油的猪。20:4含量没有差异。脂肪酸变化在先前喂食常规饲料的猪食用玉米油或鲱鱼油后最早2周出现，但在先前喂食猪油+胆固醇的猪中出现得更晚，表明预处理有残留影响。在较早时间点，对于非极性探针二苯基己三烯（DPH），鲱鱼油比玉米油更能增加各向异性（表明流动性降低），但在23周时并非如此。红细胞膜流动性与膜多不饱和物含量显著相关，（n-6）脂肪酸的影响大于（n-3）脂肪酸。将同一动物的当前红细胞脂肪酸组成与脑突触体脂肪酸组成进行比较，发现某些脂肪酸的相关性较差。红细胞膜中二十二碳六烯酸（DHA）浓度与小脑、前脑和尾状核脑突触体中DHA浓度之间没有显著的直接关系。
