Docosahexaenoic acid synthesis from α-linolenic acid by rat brain is unaffected by dietary n-3 PUFA deprivation
Docosahexaenoic acid synthesis from α-linolenic acid by rat brain is unaffected by dietary n-3 PUFA deprivation
复制标题
DOI：
10.1194/jlr.m600549-jlr200
复制
发表时间：
2007-05-01
影响因子：
6.5
通讯作者：
Rapoport, Stanley I.
中科院分区：
文献类型：
--
作者：
Igarashi, Miki;DeMar, James C., Jr.;Rapoport, Stanley I.
哺乳动物大脑将α-亚麻酸（α-LNA，18：3 n-3）转化为二十二碳六烯酸（DHA，22：6 n-3）的速率以及大脑在n-3多不饱和脂肪酸（PUFA）饮食剥夺期间上调这些速率的能力尚不清楚。为了回答这些问题，我们测量了断奶后大鼠的转换系数和转换率，这些大鼠喂食n-3 PUFA缺乏（总脂肪酸的0.2% α-LNA，无DHA）或充足（4.6% α-LNA，无DHA）饮食15周。各组未麻醉大鼠静脉输注[1-C-14] α-LNA，分析5分钟时收集的动脉血浆和微波脑。与充足的饮食相比，缺乏的饮食使大脑DHA减少了37%，并增加了大脑花生四烯酸（20：4 n-6）和二十二碳五烯酸（22：5 n-6）。充足的饮食仅使进入大脑的血浆[1-C-14] α-LNA的1%转化为DHA，并且α-LNA向DHA的转化系数不受缺乏饮食的影响。总之，大脑从α-LNA合成DHA的能力非常低，并且不受n-3 PUFA剥夺的影响。由于肝脏的报告能力要高得多，并且可以通过缺乏饮食来上调，因此当饮食中没有DHA时，由肝脏从循环α LNA转化的DHA是大脑DHA的来源。
Rates of conversion of alpha-linolenic acid (alpha-LNA, 18:3n-3) to docosahexaenoic acid (DHA, 22:6n-3) by the mammalian brain and the brain's ability to upregulate these rates during dietary deprivation of n-3 polyunsaturated fatty acids (PUFAs) are unknown. To answer these questions, we measured conversion coefficients and rates in post-weaning rats fed an n-3 PUFA deficient (0.2% alpha-LNA of total fatty acids, no DHA) or adequate (4.6% alpha-LNA, no DHA) diet for 15 weeks. Unanesthetized rats in each group were infused intravenously with [1-C-14]alpha-LNA, and their arterial plasma and microwaved brains collected at 5 minutes were analyzed. The deficient compared with adequate diet reduced brain DHA by 37% and increased brain arachidonic (20:4n-6) and docosapentaenoic 22:5n-6) acids. Only 1% of plasma [1-C-14]alpha-LNA entering brain was converted to DHA with the adequate diet, and conversion coefficients of alpha-LNA to DHA were unchanged by the deficient diet. In summary, the brain's ability to synthesize DHA from alpha-LNA is very low and is not altered by n-3 PUFA deprivation. Because the liver's reported ability is much higher, and can be up-regulated by the deficient diet, DHA converted by the liver from circulating alpha LNA is the source of the brain's DHA when DHA is not in the diet.