@article{0488e07658144766bfb9838f18acd423,
title = "Acute Hypercapnia/Ischemia Alters the Esterification of Arachidonic Acid and Docosahexaenoic Acid Epoxide Metabolites in Rat Brain Neutral Lipids",
abstract = "In the brain, approximately 90% of oxylipins are esterified to lipids. However, the significance of this esterification process is not known. In the present study, we (1) validated an aminopropyl solid phase extraction (SPE) method for separating esterified lipids using 100 and 500 mg columns and (2) applied the method to quantify the distribution of esterified oxylipins within phospholipids (PL) and neutral lipids (NL) (i.e. triacylglycerol and cholesteryl ester) in rats subjected to head-focused microwave fixation (controls) or CO2-induced hypercapnia/ischemia. We hypothesized that oxylipin esterification into these lipid pools will be altered following CO2-induced hypercapnia/ischemia. Lipids were extracted from control (n = 8) and CO2-asphyxiated (n = 8) rat brains and separated on aminopropyl cartridges to yield PL and NL. The separated lipid fractions were hydrolyzed, purified with hydrophobic–lipophilic–balanced SPE columns, and analyzed with ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry. Method validation showed that the 500 mg (vs 100 mg) aminopropyl columns yielded acceptable separation and recovery of esterified fatty acid epoxides but not other oxylipins. Two epoxides of arachidonic acid (ARA) were significantly increased, and three epoxides of docosahexaenoic acid (DHA) were significantly decreased in brain NL of CO2-asphyxiated rats compared to controls subjected to head-focused microwave fixation. PL-bound fatty acid epoxides were highly variable and did not differ significantly between the groups. This study demonstrates that hypercapnia/ischemia alters the concentration of ARA and DHA epoxides within NL, reflecting an active turnover process regulating brain fatty acid epoxide concentrations.",
keywords = "Arachidonic acid and docosahexaenoic acid epoxides, Eicosanoids, Esterified oxylipins, Hypercapnia/ischemia, Rat brain, Turnover",
author = "Yurika Otoki and Metherel, {Adam H.} and Theresa Pedersen and Jun Yang and Hammock, {Bruce D.} and Bazinet, {Richard P.} and Newman, {John W.} and Taha, {Ameer Y.}",
note = "Funding Information: This study was supported by the Hellman Family Foundation (AYT) and Natural Sciences and Engineering Research Council of Canada (grant #482597, R.P.B.). Additional support was provided by the National Institutes of Health (U24‐DK097154; J.W.N.) and the USDA (2032‐51530‐022‐00D, J.W.N.), NIEHS/R01 ES002710 (B.D.H.), and NIEHS/Superfund Research Program P42 ES004699 (B.D.H.). The USDA is an equal opportunity provider and employer. Y.O. is a recipient of a fellowship from the JSPS Core‐to‐Core Program (Advanced Research Networks) entitled “Establishment of international agricultural immunology research‐core for a quantum improvement in food safety.” The authors thank Dr. Dmitry Grapov for his efforts in developing the oxygenated complex lipid separation method, Dr. Marie Hennebelle for assistance with the method validation, and Dr. Alex Kitson for assistance with the animal experiments. Funding Information: This study was supported by the Hellman Family Foundation (AYT) and Natural Sciences and Engineering Research Council of Canada (grant #482597, R.P.B.). Additional support was provided by the National Institutes of Health (U24-DK097154; J.W.N.) and the USDA (2032-51530-022-00D, J.W.N.), NIEHS/R01 ES002710 (B.D.H.), and NIEHS/Superfund Research Program P42 ES004699 (B.D.H.). The USDA is an equal opportunity provider and employer. Y.O. is a recipient of a fellowship from the JSPS Core-to-Core Program (Advanced Research Networks) entitled ?Establishment of international agricultural immunology research-core for a quantum improvement in food safety.? The authors thank Dr. Dmitry Grapov for his efforts in developing the oxygenated complex lipid separation method, Dr. Marie Hennebelle for assistance with the method validation, and Dr. Alex Kitson for assistance with the animal experiments. The authors declare that they have no conflicts of interest. A.Y.T. conceived the concept and hypothesis surrounding oxylipin esterification into brain lipid pools during brain injury. A.Y.T., R.P.B., and A.H.M. designed the experiments. A.H.M. conducted the animal experiments. J.W.N. and T.P. guided and advised on the esterified lipid separation method. Y.O. analyzed the rat brain samples and contributed to the interpretation. A.Y.T., A.H.M., R.P.B., B.D.H., and J.Y. designed or performed prior pilot studies leading up to the present study. A.Y.T. wrote the article. All authors reviewed and approved the manuscript. Publisher Copyright: {\textcopyright} 2019 AOCS",
year = "2020",
month = jan,
day = "1",
doi = "10.1002/lipd.12197",
language = "English",
volume = "55",
pages = "7--22",
journal = "Lipids",
issn = "0024-4201",
publisher = "Springer Verlag",
number = "1",
}