Moore S A, Yoder E, Spector A A
Department of Pathology, University of Iowa, Iowa City 52242.
J Neurochem. 1990 Aug;55(2):391-402. doi: 10.1111/j.1471-4159.1990.tb04150.x.
Elongated, more highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis and mechanism of entry are not well characterized. To investigate the role of the blood-brain barrier in this process, cultured murine cerebromicrovascular endothelia were incubated with [1-14C]18:2 omega-6 or [1-14C]18:3 omega-3 and their elongation/desaturation products determined. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary product from 18:3 omega-3 was 20:5 omega-3. Although these products were found primarily in cell lipids, they were also released from the cells and gradually accumulated in the extracellular fluid. Eicosanoid production was observed from the 20:4 omega-6 and 20:5 omega-3 that were formed. No 22:5 omega-6 or 22:6 omega-3 fatty acids were detected, suggesting that these endothelial cells are not the site of the final desaturation step. Although the uptake of 18:3 omega-3 and 18:2 omega-6 was nearly identical, 18:3 omega-3 was more extensively elongated and desaturated. Competition experiments demonstrated a preference for 18:3 omega-3 by the elongation/desaturation pathway. These findings suggest that the blood-brain barrier can play an important role in the elongation and desaturation of omega-3 and omega-6 essential fatty acids during their transfer from the circulation into the brain.
亚油酸（18:2 ω-6）和亚麻酸（18:3 ω-3）的延长且多不饱和程度更高的衍生物在大脑中蓄积，但其合成部位及进入机制尚未完全明确。为研究血脑屏障在此过程中的作用，将培养的小鼠脑微血管内皮细胞与[1-¹⁴C]18:2 ω-6或[1-¹⁴C]18:3 ω-3共同孵育，并测定其延长/去饱和产物。18:2 ω-6的主要代谢产物是20:4 ω-6，而18:3 ω-3的主要产物是20:5 ω-3。尽管这些产物主要存在于细胞脂质中，但也从细胞中释放出来并逐渐在细胞外液中蓄积。由生成的20:4 ω-6和20:5 ω-3观察到类花生酸的产生。未检测到22:5 ω-6或22:6 ω-3脂肪酸，表明这些内皮细胞不是最终去饱和步骤的发生部位。尽管18:3 ω-3和18:2 ω-6的摄取几乎相同，但18:3 ω-3的延长和去饱和程度更高。竞争实验表明延长/去饱和途径对18:3 ω-3具有偏好性。这些发现表明，在ω-3和ω-6必需脂肪酸从循环转移至大脑的过程中，血脑屏障在其延长和去饱和过程中可能起重要作用。
