Changes in lipid metabolites and enzymes in rat brain due to ischemia and recirculation.

Thirty and 60-min ischemic insults resulted in an increase in free fatty acid and 1,2- diacylglycerol contents of rat forebrain. No significant changes were detected in phospholipids except phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-bisphosphate during ischemic insult. Phosphatidylinositol 4-monohosphate and phosphatidylinositol 4,5-bisphosphate contents decreased during ischemia. Although the increase in free fatty acid contents continued, 1,2-diacylglycerol did not show further increase after 30-min ischemia. These results suggest that there may be another pathway for the accumulation of free fatty acids in addition to phospholipase C coupled to di- and monoacylglycerol lipase. Free fatty acid and 1,2-diacylglycerol contents increased transiently and thereafter decreased to control levels within 90 min after postischemic recirculation. The decrease in arachidonic acid content preceded those of other FFA. Phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-bisphosphate contents gradually increased after the initiation of recirculation in ischemic brains. Lysophosphatidylcholine decreased gradually after temporary increase during 15 and 5-min recirculations in 30 and 60-min ischemic groups. Phospholipase A, phospholipase C, and di- and monoacylglycerol lipase activities did not show significant changes during entire course of recirculation. Total activities of lysophospholipase and acylation enzymes of lysophospholipid demonstrated 1.5-and 2.2-fold increase during 30-min recirculation.