Cytosolic phospholipase A 2 alpha modulates NMDA neurotoxicity in mouse hippocampal cultures

The arachidonic acid‐specific cytosolic phospholipase A 2 alpha (cPLA 2 α) has been implicated in the generation of neurological injuries. cPLA 2 α‐dependent neurological injury has been postulated to be mediated through inflammatory and eicosanoid pathways. We determined if cPLA 2 α amplifies the injury of a non‐inflammatory, excitotoxic stimulus by modifying a well‐described toxicity assay to measure the toxicity of N ‐methyl‐ d ‐aspartate (NMDA) in the CA1 region of organotypic, mouse hippocampal cultures. Hippocampal cultures from wild‐type and cPLA 2 α knockout mice were exposed to 5, 7.5 or 10 µ m NMDA for 1 h. Toxicity was measured 23 h later. Cultures derived from cPLA 2 α –/– mice and cultures treated with the selective inhibitor AACOCF 3 were significantly protected from NMDA toxicity, as compared with wild‐type cultures. To determine if cPLA 2 α‐dependent toxicity is cyclooxygenase (COX)‐2 dependent, COX‐2 and PGE 2 levels were measured 7 and 25 h after NMDA treatment. NMDA treatment failed to induce COX‐2 protein or increase PGE 2 in the culture media in either genotype at either time. In contrast, phorbol 12‐myristate 13‐acetate and ionophore treatment caused robust induction of COX‐2 and PGE 2 in both genotypes. We conclude that cPLA 2 α may have a hitherto unrecognized direct effect on excitatory neurotoxicity, suggesting that cPLA 2 α inhibition is a therapeutic candidate for treatment of the early, excitotoxic injury observed in stroke.