Cyclooxygenase-2 inhibitor NS-398 protects neuronal cultures from lipopolysaccharide-induced neurotoxicity

Background and Purpose-The prostanoid-synthesizing enzyme cyclooxygenase (C OX)-2 is markedly upregulated after cerebral ischemia and may participate i n the mechanisms by which postischemic inflammation contributes to the late stages of ischemic brain injury. In the present study, we sought to provid e additional evidence for a role of COX-2 in the mechanisms of neurotoxicit y associated with inflammation. Methods-Nine-day-old neuronal-glial cultures, prepared from the cerebral co rtex of newborn C57BL/6J mice, were exposed to lipopolysaccharide (LPS), a potent proinflammatory agent. The contribution of COX-2 was investigated by using the COX-2 inhibitor NS-398. Results LPS produced a dose-dependent (0.001 to 10 mug/mL) and selective ne uronal death that was well developed 72 hours after treatment. The effect w as associated with a marked increase in the concentration of the COX reacti on product prostaglandin E-2 (PGE(2)) and of the cytokine tumor necrosis fa ctor-alpha (TNF-alpha). NS-398 (10 mu mol/L) blocked the PGE(2) increase, a ttenuated the TNF-alpha increase, and prevented the neuronal death produced by LPS. TNF-alpha -blocking antibodies attenuated LPS-induced neuronal dea th, but the protection was less pronounced than that afforded by NS-398. LP S failed to elevate PGE(2) or to produce cell death in neuron-enriched cult ures, suggesting that glial cells are required for these effects. Conclusions-COX-2, in part through TNF-alpha -related mechanisms, contribut es to LPS-induced neuronal death. The data support the hypothesis that COX- 2, in addition to its role in glutamate excitotoxicity, participates in the cytotoxicity associated with inflammation.