Brain acyl-coa concentration in gerbil ischemia-reperfusion

Ischemia-reperfusion in brain results in the release of lipid mediators, especially arachidonic acid (AA), which have been linked to post-ischemic neuronal loss. To determine the potential in brain for post-ischemic reincorporation of high levels of released fatty acid, the status of acyl-CoA, a metabolic intermediate, must be analyzed. A surgical thread was looped around both common carotid arteries in halothane-anestheüzed male gerbils. In addition, control animals were sham operated. After animals recovered, the carotid arteries were occluded for 5 min. Following 5 min of reperfusion, the animals were rapidly anesthetized and killed by microwave irradiation (MW). The cerebellum was discarded and 0.35 to 0.6 g of brain analyzed for acyl-CoA by a procedure involving solubilization, solid phase extraction and HPLC. The last step resolved individual molecular species of acyl-CoA, including AA- and docosahexaenoyl(DHA)-CoA. 100 mg brain was also analyzed for unesterified fatty acid by TLC isolation and gas chromatography of fatty acid methyl esters. After ischemia-reperfusion, a 4.7 fold increase in total brain free fatty acid concentration was observed, with the relative change in AA being the highest (30 fold). Stearoyl(STE)CoA was significantly increased by 46% whereas palmitoyl-CoA was reduced by 25%. AA-CoA increased dramatically, by 540%, whereas DHA-CoA decreased by 75%. Dramatic changes in the acyl-CoA pool after ischemia-reperfusion indicate altered rates for fatty acid reincorporation into phospholipid. The increased concentrations of STE- and AA-CoA suggest that re-incorporation of these fatty acids is favored during reperfusion phase, when functional ATP levels are re-established.