Turnover of brain DHA in mice is accurately determined by tracer-free natural abundance carbon isotope ratio analysis[S]
Turnover of brain DHA in mice is accurately determined by tracer-free natural abundance carbon isotope ratio analysis[S]
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DOI：
10.1194/jlr.d119000518
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发表时间：
2020-01-01
影响因子：
6.5
通讯作者：
Bazinet, Richard P.
中科院分区：
文献类型：
--
作者：
Lacombe, R. J. Scott;Lee, Chi-Chiu;Bazinet, Richard P.
大脑富含长链omega-3（n-3）PUFA DHA。由于大脑中局部DHA合成的能力有限，它依赖于循环的持续供应来补充代谢的DHA。以前研究大脑DHA周转和代谢的研究依赖于同位素示踪剂来确定大脑脂肪酸动力学;然而，这种方法繁琐且昂贵。我们通过高精度气相色谱燃烧同位素比质谱法应用天然丰度碳同位素比分析，不使用标记示踪剂，以确定饮食转换实验后小鼠脑DHA的半衰期。喂食含有α-亚麻酸（ALA）或DHA作为唯一膳食n-3 PUFA的饮食的小鼠在6周龄时转换为含有ALA、DHA或ALA + DHA的饮食，而对照小鼠维持其各自的背景饮食。我们在168天的时间过程中测量了大脑DHA碳同位素比率（报告为δ C-13（DHA）签名）。对照组小鼠的大脑δ C-13（DHA）特征在整个时间过程中保持稳定（P > 0.05）。从ALA饮食切换到DHA或ALA + DHA饮食的小鼠的脑δ C-13（DHA）特征随时间变化，分别产生40天和34天的脑掺入半衰期。通过天然丰度碳同位素比分析确定的这些半衰期与动力学同位素示踪研究的估计值一致。我们的研究结果表明，在不使用同位素标记的脂肪酸示踪剂的情况下，天然丰度碳同位素比值分析在脂肪酸代谢研究中的可行性。
The brain is highly enriched in the long-chain omega-3 (n-3) PUFA DHA. Due to the limited capacity for local DHA synthesis in the brain, it relies on a continual supply from the circulation to replenish metabolized DHA. Previous studies investigating brain DHA turnover and metabolism have relied on isotope tracers to determine brain fatty acid kinetics; however, this approach is cumbersome and costly. We applied natural abundance carbon isotope ratio analysis via high-precision gas chromatography combustion isotope ratio mass spectrometry, without the use of labeled tracers, to determine the half-life of brain DHA in mice following a dietary switch experiment. Mice fed diets containing either alpha-linolenic acid (ALA) or DHA as the sole dietary n-3 PUFA were switched onto diets containing ALA, DHA, or ALA + DHA at 6 weeks of age, while control mice were maintained on their respective background diet. We measured brain DHA carbon isotope ratios (reported as delta C-13(DHA) signatures) over a 168-day time course. Brain delta C-13(DHA) signatures of control mice maintained on background diets over the time course were stable (P > 0.05). Brain delta C-13(DHA) signatures of mice switched to the DHA or ALA + DHA diet from the ALA diet changed over time, yielding brain incorporation half-lives of 40 and 34 days, respectively. These half-lives determined by natural abundance carbon isotope ratio analysis were consistent with estimates from kinetic isotope tracer studies. Our results demonstrate the feasibility of natural abundance carbon isotope ratio analysis in the study of fatty acid metabolism without the use of isotopically labeled fatty acid tracers.