Intraperitoneally injected d11-11(12)-epoxyeicosatrienoic acid is rapidly incorporated and esterified within rat plasma and peripheral tissues but not the brain - PubMed (original) (raw)
Intraperitoneally injected d11-11(12)-epoxyeicosatrienoic acid is rapidly incorporated and esterified within rat plasma and peripheral tissues but not the brain
Sho Watanabe et al. Prostaglandins Leukot Essent Fatty Acids. 2024 Mar.
Abstract
Epoxyeicosatrienoic acids (EpETrEs) are bioactive lipid mediators of arachidonic acid cytochrome P450 oxidation. In vivo, the free (unbound) form of EpETrEs regulate multiple processes including blood flow, angiogenesis and inflammation resolution. Free EpETrEs are thought to rapidly degrade via soluble epoxide hydrolase (sEH); yet, in many tissues, the majority of EpETrEs are esterified to complex lipids (e.g. phospholipids) suggesting that esterification may play a major role in regulating free, bioactive EpETrE levels. This hypothesis was tested by quantifying the metabolism of intraperitoneally injected free d11-11(12)-Epoxyeicosatrienoic acid (d11-11(12)-EpETrE) in male and female rats. Plasma and tissues (liver, adipose and brain) were obtained 3 to 4 min later and assayed for d11-11(12)-EpETrE and its sEH metabolite, d11-11,12-dihydroxyeicosatrienoic acid (d11-11,12-diHETrE) in both the free and esterified lipid fractions. In both males and females, the majority of injected tracer was recovered in liver followed by plasma and adipose. No tracer was detected in the brain, indicating that brain levels are maintained by endogenous synthesis from precursor fatty acids. In plasma, liver, and adipose, the majority (>54 %) of d11-11(12)-EpETrE was found esterified to phospholipids or neutral lipids (triglycerides and cholesteryl esters). sEH-derived d11-11,12-diHETrE was not detected in plasma or tissues, suggesting negligible conversion within the 3-4 min period post tracer injection. This study shows that esterification is the main pathway regulating free 11(12)-EpETrE levels in vivo.
Keywords: Acyl-CoA synthetase; Acyltransferase; Esterification; Fatty acid epoxide; Mass spectrometry (MS); Metabolic tracer; Rodents.
Copyright © 2024 Elsevier Ltd. All rights reserved.
Figures
Fig. 1.
Proposed pathway for 11(12)-EpETrE metabolism in vivo. The first pathway involves the degradation of EpETrE into DiHETrE via sEH. The second pathway is esterification into various lipid fractions, including PLs and NLs (i.e., triglycerides and cholesteryl esters). The third pathway is distrbution of free and esterified EpETrEs into tissues. AA: arachidonic acid; EpETrE: epoxyeicosatrienoic acid; DiHETrE: dihydroxyeicosatrienoic acid; sEH: soluble epoxide hydrolase; PL: phospholipid; NL: neutral lipid.
Fig. 2.
Representative chromatograms of free, NL- and PL- bound d11-11(12)-EpETrE in plasma, liver, adipose and brain from a female non-perfused rat. NL: neutral lipid; PL: phospholipid; EpETrE: epoxyeicosatrienoic acid. The chromatograms were obtained under multiple reaction monitoring conditions (m/z 330.2–167.2). Large peak areas do not necessarily reflect greater concentrations, as concentrations can only be derived after correcting for losses during extraction with the internal standard and the initial weight of tissues.
Fig. 3.
Representative chromatograms of free, NL- and PL- bound d11-11,12-DiHETrE in plasma, liver, adipose and brain from a female non-perfused rat. Retention time of d11-11,12-DiHETrE is around 9.9 to 10.0. NL: neutral lipid; PL: phospholipid; DiHETrE: dihydroxyeicosatrienoic acid.
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