Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada.
Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada; Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile.
J Lipid Res. 2023 May;64(5):100357. doi: 10.1016/j.jlr.2023.100357. Epub 2023 Mar 21.
The brain is rich in DHA, which plays important roles in regulating neuronal function. Recently, using compound-specific isotope analysis that takes advantage of natural differences in carbon-13 content (C/C ratio or δC) of the food supply, we determined the brain DHA half-life. However, because of methodological limitations, we were unable to capture DHA turnover rates in peripheral tissues. In the current study, we applied compound-specific isotope analysis via high-precision GC combustion isotope ratio mass spectrometry to determine half-lives of brain, liver, and plasma DHA in mice following a dietary switch experiment. To model DHA tissue turnover rates in peripheral tissues, we added earlier time points within the diet switch study and took advantage of natural variations in the δC-DHA of algal and fish DHA sources to maintain DHA pool sizes and used an enriched (uniformly labeled C) DHA treatment. Mice were fed a fish-DHA diet (control) for 3 months, then switched to an algal-DHA treatment diet, the C enriched-DHA treatment diet, or they stayed on the control diet for the remainder of the study time course. In mice fed the algal and C enriched-DHA diets, the brain DHA half-life was 47 and 46 days, the liver half-life was 5.6 and 7.2 days, and the plasma half-life was 4.7 and 6.4 days, respectively. By using improved methodologies, we calculated DHA turnover rates in the liver and plasma, and our study for the first time, by using an enriched DHA source (very high δC), validated its utility in diet switch studies.
大脑富含 DHA，其在调节神经元功能方面发挥着重要作用。最近，我们利用食物供应中碳-13 含量（C/C 比或 δC）的天然差异，通过特定于化合物的同位素分析来确定大脑 DHA 的半衰期。然而，由于方法学的限制，我们无法捕捉到外周组织中 DHA 的周转率。在当前的研究中，我们应用了特定于化合物的同位素分析，通过高精度 GC 燃烧同位素比质谱法，在饮食转换实验后确定了小鼠大脑、肝脏和血浆 DHA 的半衰期。为了模拟外周组织中 DHA 组织的周转率，我们在饮食转换研究中增加了更早的时间点，并利用藻类和鱼类 DHA 来源的 δC-DHA 的天然变化来维持 DHA 池的大小，并使用富含（均匀标记 C）DHA 的处理方法。小鼠先喂食含鱼源 DHA 的饮食（对照组）3 个月，然后切换到含藻源 DHA 的处理饮食、富含 C 的 DHA 处理饮食，或在其余的研究时间内继续喂食对照组饮食。在喂食藻源和富含 C 的 DHA 饮食的小鼠中，大脑 DHA 的半衰期分别为 47 天和 46 天，肝脏的半衰期分别为 5.6 天和 7.2 天，血浆的半衰期分别为 4.7 天和 6.4 天。通过使用改进的方法，我们计算了肝脏和血浆中 DHA 的周转率，并且我们的研究首次使用富含 DHA 的来源（非常高的 δC）验证了其在饮食转换研究中的实用性。
