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Otoki Y, Metherel AH, Pedersen T, Yang J, Hammock BD, Bazinet RP, Newman JW, Taha AY. Acute Hypercapnia/Ischemia Alters the Esterification of Arachidonic Acid and Docosahexaenoic Acid Epoxide Metabolites in Rat Brain Neutral Lipids. Lipids 2020; 55:7-22. [PMID: 31691988 PMCID: PMC7220815 DOI: 10.1002/lipd.12197] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/15/2022]
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.
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Affiliation(s)
- Yurika Otoki
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
- Food and Biodynamic Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan
| | - Adam H. Metherel
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, ON, M5S 1A8, Canada
| | - Theresa Pedersen
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Jun Yang
- Department of Entomology and Nematology, College of Agriculture and Environmental Sciences, University of California, Davis, CA 95616, USA
- Comprehensive Cancer Center, Medical Center, University of California, Davis, CA 95616, USA
| | - Bruce D. Hammock
- Department of Entomology and Nematology, College of Agriculture and Environmental Sciences, University of California, Davis, CA 95616, USA
- Comprehensive Cancer Center, Medical Center, University of California, Davis, CA 95616, USA
- West Coast Metabolomics Center, Genome Center, University of California–Davis, Davis, CA 95616, USA
| | - Richard P. Bazinet
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, ON, M5S 1A8, Canada
| | - John W. Newman
- West Coast Metabolomics Center, Genome Center, University of California–Davis, Davis, CA 95616, USA
- Department of Nutrition, University of California–Davis, Davis, CA 95616, USA
- United States Department of Agriculture, Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA 95616, USA
| | - Ameer Y. Taha
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
- West Coast Metabolomics Center, Genome Center, University of California–Davis, Davis, CA 95616, USA
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Taha AY, Trepanier MO, Coibanu FA, Saxena A, Jeffrey MA, Taha NMY, Burnham WM, Bazinet RP. Dietary Omega-3 Polyunsaturated Fatty Acid Deprivation Does Not Alter Seizure Thresholds but May Prevent the Anti-seizure Effects of Injected Docosahexaenoic Acid in Rats. Front Neurol 2019; 9:1188. [PMID: 30804888 PMCID: PMC6370649 DOI: 10.3389/fneur.2018.01188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 12/24/2018] [Indexed: 02/02/2023] Open
Abstract
Background: Brain concentrations of omega-3 docosahexaenoic acid (DHA, 22:6n-3) have been reported to positively correlate with seizure thresholds in rodent seizure models. It is not known whether brain DHA depletion, achieved by chronic dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency, lowers seizure thresholds in rats. Objective: The present study tested the hypothesis that lowering brain DHA concentration with chronic dietary n-3 PUFA deprivation in rats will reduce seizure thresholds, and that compared to injected oleic acid (OA), injected DHA will raise seizure thresholds in rats maintained on n-3 PUFA adequate and deficient diets. Methods: Rats (60 days old) were surgically implanted with electrodes in the amygdala, and subsequently randomized to the AIN-93G diet containing adequate levels of n-3 PUFA derived from soybean oil or an n-3 PUFA-deficient diet derived from coconut and safflower oil. The rats were maintained on the diets for 37 weeks. Afterdischarge seizure thresholds (ADTs) were measured every 4–6 weeks by electrically stimulating the amygdala. Between weeks 35 and 37, ADTs were assessed within 1 h of subcutaneous OA or DHA injection (600 mg/kg). Seizure thresholds were also measured in a parallel group of non-implanted rats subjected to the maximal pentylenetetrazol (PTZ, 110 mg/kg) seizure test. PUFA composition was measured in the pyriform-amygdala complex of another group of non-implanted rats sacrificed at 16 and 32 weeks. Results: Dietary n-3 PUFA deprivation did not significantly alter amygdaloid seizure thresholds or latency to PTZ-induced seizures. Acute injection of OA did not alter amygdaloid ADTs of rats on the n-3 PUFA adequate or deficient diets, whereas acute injection of DHA significantly increased amygdaloid ADTs in rats on the n-3 PUFA adequate control diet as compared to rats on the n-3 PUFA deficient diet (P < 0.05). Pyriform-amygdala DHA percent composition did not significantly differ between the groups, while n-6 docosapentaenoic acid, a marker of n-3 PUFA deficiency, was significantly increased by 2.9-fold at 32 weeks. Conclusion: Chronic dietary n-3 PUFA deficiency does not alter seizure thresholds in rats, but may prevent the anti-seizure effects of DHA.
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Affiliation(s)
- Ameer Y Taha
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, Davis, CA, United States.,EpLink, the Epilepsy Research Program of the Ontario Brain Institute, Toronto, ON, Canada
| | - Marc-Olivier Trepanier
- EpLink, the Epilepsy Research Program of the Ontario Brain Institute, Toronto, ON, Canada.,Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Flaviu A Coibanu
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Anjali Saxena
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Melanie A Jeffrey
- EpLink, the Epilepsy Research Program of the Ontario Brain Institute, Toronto, ON, Canada.,Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Nadeen M Y Taha
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - W McIntyre Burnham
- EpLink, the Epilepsy Research Program of the Ontario Brain Institute, Toronto, ON, Canada.,Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Richard P Bazinet
- EpLink, the Epilepsy Research Program of the Ontario Brain Institute, Toronto, ON, Canada.,Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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