Retrotope, Inc., Pre-Clinical and Pharmaceutical Development, Los Altos Hills, CA 94022, USA.
Toxicol Lett. 2011 Nov 30;207(2):97-103. doi: 10.1016/j.toxlet.2011.07.020. Epub 2011 Aug 10.
Oxidative damage of membrane polyunsaturated fatty acids (PUFA) is thought to play a major role in mitochondrial dysfunction related to Parkinson's disease (PD). The toxic products formed by PUFA oxidation inflict further damage on cellular components and contribute to neuronal degeneration. Here, we tested the hypothesis that isotopic reinforcement, by deuteration of the bisallylic sites most susceptible to oxidation in PUFA may provide at least partial protection against nigrostriatal injury in a mouse model of oxidative stress and cell death, the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model. Mice were fed a fat-free diet supplemented with saturated acids, oleic acid and essential PUFA: either normal, hydrogenated linoleic (LA, 18:2n-6) and α-linolenic (ALA, 18:3n-3) or deuterated 11,11-D2-LA and 11,11,14,14-D4-ALA in a ratio of 1:1 (to a total of 10% mass fat) for 6 days; each group was divided into two cohorts receiving either MPTP or saline and then continued on respective diets for 6 days. Brain homogenates from mice receiving deuterated PUFA (D-PUFA) vs. hydrogenated PUFA (H-PUFA) demonstrated a significant incorporation of deuterium as measured by isotope ratio mass-spectrometry. Following MPTP exposure, mice fed H-PUFA revealed 78.7% striatal dopamine (DA) depletion compared to a 46.8% reduction in the D-PUFA cohort (as compared to their respective saline-treated controls), indicating a significant improvement in DA concentration with D-PUFA. Similarly, higher levels of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were detected in MPTP-exposure mice administered D-PUFA; however, saline-treated mice revealed no change in DA or DOPAC levels. Western blot analyses of tyrosine hydroxylase (TH) confirmed neuroprotection with D-PUFA, as striatal homogenates showed higher levels of TH immunoreactivity in D-PUFA (88.5% control) vs. H-PUFA (50.4% control) in the MPTP-treated cohorts. In the substantia nigra, a significant improvement was noted in the number of nigral dopaminergic neurons following MPTP exposure in the D-PUFA (79.5% control) vs. H-PUFA (58.8% control) mice using unbiased stereological cell counting. Taken together, these findings indicate that dietary isotopic reinforcement with D-PUFA partially protects against nigrostriatal damage from oxidative injury elicited by MPTP in mice.
氧化损伤的膜多不饱和脂肪酸（PUFA）被认为在帕金森病（PD）相关的线粒体功能障碍中发挥主要作用。PUFA 氧化形成的有毒产物对细胞成分造成进一步的损害，并导致神经元变性。在这里，我们测试了这样一个假设，即通过对 PUFA 中最易氧化的双烯位点进行氘化，同位素强化至少可以为 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）模型中的氧化应激和细胞死亡的黑质纹状体损伤提供部分保护，1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）模型。将小鼠喂以无脂肪饮食，补充饱和酸、油酸和必需的多不饱和脂肪酸：正常、氢化亚油酸（LA，18:2n-6）和α-亚麻酸（ALA，18:3n-3）或氘化 11,11-D2-LA 和 11,11,14,14-D4-ALA 以 1:1 的比例（总质量脂肪为 10%）喂养 6 天；每组分为两组，一组接受 MPTP 或生理盐水，然后继续分别喂食 6 天。与氢化多不饱和脂肪酸（H-PUFA）相比，接受氘化多不饱和脂肪酸（D-PUFA）的小鼠的脑匀浆通过同位素比质谱法显示出显著的氘掺入。在接受 MPTP 暴露后，与各自的生理盐水处理对照相比，用 H-PUFA 喂养的小鼠的纹状体多巴胺（DA）耗竭率为 78.7%，而 D-PUFA 组的耗竭率为 46.8%，表明 D-PUFA 组的 DA 浓度显著改善。同样，在接受 MPTP 暴露的小鼠中，检测到更高水平的 DA 代谢物 3,4-二羟基苯乙酸（DOPAC）；然而，生理盐水处理的小鼠的 DA 或 DOPAC 水平没有变化。酪氨酸羟化酶（TH）的 Western blot 分析证实了 D-PUFA 的神经保护作用，因为在 MPTP 处理的组中，纹状体匀浆中 D-PUFA（88.5%对照）的 TH 免疫反应性明显高于 H-PUFA（50.4%对照）。在黑质中，通过无偏立体细胞计数，在用 MPTP 处理的 D-PUFA（79.5%对照）和 H-PUFA（58.8%对照）小鼠中，黑质多巴胺能神经元的数量显著改善。综上所述，这些发现表明，通过饮食同位素强化 D-PUFA 可以部分保护小鼠免受 MPTP 引起的黑质纹状体氧化损伤。
