Differential roles of cyclooxygenase isoforms after kainic acid-induced prostaglandin E₂ production and neurodegeneration in cortical and hippocampal cell cultures

Prostaglandins, which are cyclooxygenase (COX) products, are pathologically up-regulated, and have been proven to be closely associated with neuronal death. In this study, we investigated a role of COX isoforms (COX-1 and COX-2) in kainic acid-induced neuronal death in cultured murine cortical or hippocampal neurons. In primary cortical neurons, both indomethacin (COX-1/-2 nonselective inhibitor) and aspirin (COX-1 preferential inhibitor) reduced basal and kainic acid-induced PGE₂ production significantly and prevented neuronal cell death after kainic acid treatment. In contrast, NS398 (COX-2 selective inhibitor) had no effect on kainic acid-induced neuronal cell death. In hippocampal neurons, however, COX-2 inhibitors prevented both kainic acid-induced neuronal death and PGE₂ production. COX-2 expression was remarkably up-regulated by kainic acid in hippocampal neurons; whereas in cortical neurons, COX-2 expression was comparatively less significant. Astrocytes were unresponsive to kainic acid in terms of PGE₂ production and cell death. In conclusion, we suggest that the release of PGE₂ induced by kainic acid occurred through COX-1 activity rather than COX-2 in cortical neurons. The inhibition of PGE₂ release by COX-1 inhibitors prevented kainic acid-induced cortical neuronal death, while in the hippocampal neurons, COX-2 inhibitors prevented kainic acid-induced PGE₂ release and hippocampal neuronal death.