Formation of eicosanoids, E2/D2 isoprostanes, and docosanoids following decapitation-induced ischemia, measured in high-energy-microwaved rat brain

Abstract

Inflammatory lipid mediators derived from arachidonic acid (AA) and docosahexaenoic acid (DHA) modify the pathophysiology of brain ischemia. The goal of this work was to investigate the formation of eicosanoids and docosanoids generated from AA and DHA, respectively, during noflow cerebral ischemia. Rats were subjected to head-focused microwave irradiation 5 min following decapitation (complete ischemia) or prior to decapitation (controls). Brain lipids were extracted and analyzed by reverse-phase liquid chromatography-tandem mass spectrometry. After complete ischemia, brain AA, DHA, and docosapentaenoic acid concentrations increased 18-, 5-and 4-fold compared with controls, respectively. Prostaglandin E 2 (PGE 2 ) and PGD 2 could not be detected in control microwaved rat brain, suggesting little endogenous PGE 2 /D 2 production in the brain in the absence of experimental manipulation. Concentrations of thromboxane B 2 , E 2 /D 2 -isoprostanes, 5-hydroxyeicosatetraenoic acid (5-HETE), 5-oxo-eicosatetraenoic acid, and 12-HETE were significantly elevated in ischemic brains. In addition, DHA products such as mono-, di-and trihydroxy-DHA were detected in control and ischemic brains. Monohydroxy-DHA, identified as 17-hydroxy-DHA and thought to be the immediate precursor of neuroprotectin D 1 , was 6.5-fold higher in ischemic than in control brain. The present study demonstrated increased formation of eicosanoids, E 2 /D 2 -IsoPs, and docosanoids following cerebral ischemia. A balance of these lipid mediators may mediate immediate events of ischemic injury and recovery.-Farias, S. E., M. Basselin, L. Chang, K. A. Heidenreich, S. I. Rapoport, and R. C. Murphy. Formation of eicosanoids, E 2 /D 2 isoprostanes, and docosanoids following decapitation-induced ischemia, measured in high-energy-microwaved rat brain. J. Lipid Res.

Lithium modifies brain arachidonic and docosahexaenoic metabolism in rat lipopolysaccharide model of neuroinflammation

“…Subsequent one-way ANOVAs with Bonferroni posthoc tests showed that both doses of LPS compared with aCSF signifi cantly increased brain cPLA 2 -IV activity by 36% and a slight occasional effect of cannula implantation, likely due to minimal neuroinfl ammation around the cannula track ( 37 ). In a prior study, PGE 2 could not be detected in control microwaved rat brain in the absence of a cannula ( 29 ). Low-dose LPS-or aCSF-infused rats with indwelling catheters appeared behaviorally normal after 24 h, whereas high-dose LPS-infused rats were lethargic and docile throughout the 6 day infusion period.…”

“…This method has been validated for quantifying concentrations of unesterifi ed fatty acids and their metabolites in rodent brains that have been subjected to high-energy headfocused microwaving to stop lipid metabolism and limit postmortem alterations ( 29,30 ). Others and we have demonstrated that such radiation is essential for measuring accurate brain concentrations of unesterifi ed fatty acids, eicosanoids, and anandamide ( 31 ).…”

“…Brain lipids were extracted with 80% methanol and purifi ed on a C18 column as described previously ( 29 ). Right and left microwaved cerebral hemispheres were homogenized separately in 4 ml of 80% methanol and 4 -PGE 2 (Cayman Chemicals, Ann Arbor, MI) as internal standards.…”

“…ischemia caused by decapitation, concentrations of unesterifi ed fatty acids are rapidly increased ( 29,30,32 ).…”

“…The goal of this study was to further investigate the interaction between chronic lithium and neuroinfl ammation by measuring concentrations of unesterifi ed polyunsaturated fatty acids and some of their metabolites in high-energy microwaved brain of rats fed LiCl chronically, using RP-HPLC/MS/MS as described in our ischemia study ( 29 ). We quantifi ed concentrations of unesterifi ed AA, DHA, docosapentaenoic acid (DPA; 22:5n-3), 17-OH-DHA, PGE 2 , TXB 2 , 5-, 12-and 15-hydroxyeicosatetraenoic acids (HETEs), and 5-oxo-eicosatetraenoic acid (5-oxo-ETE) in brains from rats subjected to 6 days of intracerebroventricular infusion with a high (250 ng/h) or low (0.5 ng/h) dose of LPS.…”