Demar James C, Ma Kaizong, Chang Lisa, Bell Jane M, Rapoport Stanley I
Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Neurochem. 2005 Aug;94(4):1063-76. doi: 10.1111/j.1471-4159.2005.03258.x.
Adult male unanesthetized rats, reared on a diet enriched in both alpha-linolenic acid (alpha-LNA) and docosahexaenoic acid (DHA), were infused intravenously for 5 min with [1-(14)C]alpha-LNA. Timed arterial samples were collected until the animals were killed at 5 min and the brain was removed after microwaving. Plasma and brain lipid concentrations and radioactivities were measured. Within plasma lipids, > 99% of radioactivity was in the form of unchanged [1-(14)C]alpha-LNA. Eighty-six per cent of brain radioactivity at 5 min was present as beta-oxidation products, whereas the remainder was mainly in 'stable' phospholipid or triglyceride as alpha-LNA or DHA. Equations derived from kinetic modeling demonstrated that unesterified unlabeled alpha-LNA rapidly enters brain from plasma, but that its incorporation into brain phospholipid and triglyceride, as in the form of synthesized DHA, is < or = 0.2% of the amount that enters the brain. Thus, in rats fed a diet containing large amounts of both alpha-LNA and DHA, the alpha-LNA that enters brain from plasma largely undergoes beta-oxidation, and is not an appreciable source of DHA within brain phospholipids.
以富含α-亚麻酸（α-LNA）和二十二碳六烯酸（DHA）的饲料饲养的成年未麻醉雄性大鼠，静脉注射[1-(14)C]α-LNA 5分钟。采集定时动脉样本，直至5分钟后处死动物，并在微波处理后取出大脑。测量血浆和脑脂质浓度及放射性。在血浆脂质中，>99%的放射性以未改变的[1-(14)C]α-LNA形式存在。5分钟时，86%的脑放射性以β-氧化产物形式存在，其余主要以α-LNA或DHA形式存在于“稳定”的磷脂或甘油三酯中。动力学建模得出的方程表明，未酯化的未标记α-LNA从血浆迅速进入大脑，但其以合成DHA形式掺入脑磷脂和甘油三酯的量占进入大脑量的<或=0.2%。因此，在喂食含有大量α-LNA和DHA饲料的大鼠中，从血浆进入大脑的α-LNA大部分经历β-氧化，并非脑磷脂中DHA的可观来源。
