Sylvestre Duncan A, Otoki Yurika, Metherel Adam H, Bazinet Richard P, Slupsky Carolyn M, Taha Ameer Y
Department of Food Science and Technology, University of California, Davis, USA; Department of Nutrition, University of California, Davis, USA.
Department of Food Science and Technology, University of California, Davis, USA; Food and Biodynamic Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan.
Neurochem Int. 2022 Jun;156:105294. doi: 10.1016/j.neuint.2022.105294. Epub 2022 Jan 31.
It is known that brain energy metabolites such as ATP are quickly depleted during postmortem ischemia; however, a comprehensive assessment on the effects of preceding hypercapnia/ischemia and the dissection process on the larger brain metabolome remains lacking. This study sought to address this unknown by measuring aqueous metabolites impacted by hypercapnia/ischemia and brain dissection using Nuclear Magnetic Resonance. Metabolites were measured in rats subjected to 1) high energy head-focused microwave irradiation (control group); 2) CO-induced hypercapnia/ischemia followed by immediate microwave irradiation; 3) CO followed by decapitation and then microwave irradiation ∼6.4 min later, to simulate a postmortem interval equivalent to typical dissection times; and 4) CO-induced hypercapnia/ischemia followed by dissection within ∼6 min (no microwave fixation) to test the effects of brain dissection on the metabolome. Compared to control rats subjected to head-focused microwave irradiation, concentrations of high-energy phosphate metabolites and glucose were significantly reduced, while β-hydroxybutyrate and lactate were increased in rats subjected to all other treatments. Several amino acids and neurotransmitters (GABA) increased by hypercapnia/ischemia and dissection. Sugar donors involved in glycosylation decreased and nucleotides decreased or increased following hypercapnia/ischemia and dissection. sn-Glycero-3-phosphocholine decreased and its choline byproduct increased in all groups relative to controls, indicating postmortem changes in lipid turnover. Antioxidants increased following hypercapnia/ischemia but decreased to control levels following dissection. This study demonstrates substantial post-mortem changes in brain energy and glycosylation pathways, as well as protein, nucleotide, neurotransmitter, lipid, and antioxidant turnover due to hypercapnia/ischemia and dissection. Changes in phosphate donors, glycosylation and amino acids reflect post-translational modification and protein degradation processes that persist post-mortem. Microwave irradiation is necessary for accurately capturing in vivo brain metabolite concentrations.
已知在死后缺血期间，脑能量代谢物如三磷酸腺苷（ATP）会迅速耗尽；然而，对于先前的高碳酸血症/缺血以及解剖过程对更大范围脑代谢组的影响，仍缺乏全面评估。本研究旨在通过使用核磁共振测量受高碳酸血症/缺血和脑解剖影响的水溶性代谢物来解决这一未知问题。在以下大鼠中测量代谢物：1）高能头部聚焦微波照射（对照组）；2）一氧化碳诱导的高碳酸血症/缺血，随后立即进行微波照射；3）一氧化碳处理后断头，然后在约6.4分钟后进行微波照射，以模拟与典型解剖时间相当的死后间隔；4）一氧化碳诱导的高碳酸血症/缺血，随后在约6分钟内进行解剖（无微波固定），以测试脑解剖对代谢组的影响。与接受头部聚焦微波照射的对照大鼠相比，在所有其他处理的大鼠中，高能磷酸代谢物和葡萄糖的浓度显著降低，而β-羟基丁酸酯和乳酸增加。几种氨基酸和神经递质（γ-氨基丁酸）因高碳酸血症/缺血和解剖而增加。参与糖基化的糖供体减少，核苷酸在高碳酸血症/缺血和解剖后减少或增加。相对于对照组，所有组中的sn-甘油-3-磷酸胆碱减少，其胆碱副产物增加，表明脂质周转的死后变化。抗氧化剂在高碳酸血症/缺血后增加，但在解剖后降至对照水平。本研究表明，由于高碳酸血症/缺血和解剖，脑能量和糖基化途径以及蛋白质、核苷酸、神经递质、脂质和抗氧化剂周转存在大量死后变化。磷酸盐供体、糖基化和氨基酸的变化反映了死后持续存在的翻译后修饰和蛋白质降解过程。为准确捕获体内脑代谢物浓度，微波照射是必要的。
