Compound-specific isotope analysis resolves the dietary origin of docosahexaenoic acid in the mouse brain
Compound-specific isotope analysis resolves the dietary origin of docosahexaenoic acid in the mouse brain
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DOI：
10.1194/jlr.d077990
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发表时间：
2017-10-01
影响因子：
6.5
通讯作者：
Bazinet, Richard P.
中科院分区：
文献类型：
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作者：
Lacombe, R. J. Scott;Giuliano, Vanessa;Bazinet, Richard P.
DHA(22：6n-3)可来自两种饮食来源，预制膳食DHA或通过合成α-亚麻酸(ALA；18：3n-3)。然而，如果不使用昂贵的标记示踪剂，传统方法无法区分来自这两种来源的DHA。在本研究中，我们证明了化合物特异性同位素分析(CSIA)通过气相色谱-同位素比质谱仪(IRMS)可以根据天然C-13丰度的不同来区分脑DHA的来源。小鼠饲喂含有纯化的ALA或DHA作为唯一n-3多不饱和脂肪酸的饲料。提取的脂肪用CSIA分析天然丰度C-13的丰度。与ALA饮食的小鼠(-28.25‰至-27.49‰)相比，喂食DHA的小鼠的大脑DHA明显更丰富(-23.32ppm至-21.92ppm)。测得的脑DHA碳-13丰度与膳食n-3PUFA来源非常相似，DHA和ALA分别为-21.86‰和-28.22‰。饲料对肝脏和血液中DHA C-13浓缩的影响是相似的。我们的结果表明，CSIA在自然C-13浓缩时，在不需要示踪剂的情况下，可以有效地区分预先形成或合成的DHA并入大脑和其他组织。
DHA (22:6n-3) may be derived from two dietary sources, preformed dietary DHA or through synthesis from alpha-linolenic acid (ALA; 18:3n-3). However, conventional methods cannot distinguish between DHA derived from either source without the use of costly labeled tracers. In the present study, we demonstrate the proof-of-concept that compound-specific isotope analysis (CSIA) by GC-isotope ratio mass spectrometry (IRMS) can differentiate between sources of brain DHA based on differences in natural C-13 enrichment. Mice were fed diets containing either purified ALA or DHA as the sole n-3 PUFA. Extracted lipids were analyzed by CSIA for natural abundance C-13 enrichment. Brain DHA from DHA-fed mice was significantly more enriched (-23.32 parts per thousand to -21.92 parts per thousand) compared with mice on the ALA diet (-28.25 parts per thousand to -27.49 parts per thousand). The measured C-13 enrichment of brain DHA closely resembled the dietary n-3 PUFA source, -21.86 parts per thousand and -28.22 parts per thousand for DHA and ALA, respectively. The dietary effect on DHA C-13 enrichment was similar in liver and blood fractions. Our results demonstrate the effectiveness of CSIA, at natural C-13 enrichment, to differentiate between the incorporation of preformed or synthesized DHA into the brain and other tissues without the need for tracers.