Regional differences in arachidonic acid release in rat hippocampal CA1 and CA3 regions during cerebral ischemia

Changes in the levels of arachidonic acid during ischemia in selectively vulnerable areas of the hippocampus were studied in the rat brain. Since neurons in the CA1 region are more vulnerable to ischemia than neurons in the adjacent CA3 region, the release of arachidonic acid in these two regions was measured during decapitation ischemia of 4- to 12-min duration. The concentration of free arachidonic acid increased with the duration of ischemia in both regions. However, the level was significantly higher in CA1 than in CA3 after 8 and 12 min of ischemia. This difference in arachidonic acid accumulation may reflect differences between the regions in agonist-dependent phospholipid breakdown as well as calcium-dependent phospholipase activity. The importance for the development of neuronal necrosis is discussed.