Piroxicam and NS-398 rescue neurones from hypoxia/reoxygenation damage by a mechanism independent of cyclo-oxygenase inhibition.
We studied whether NS-398, a selective cyclo-oxygenase-2 (COX-2) enzyme inhibitor, and piroxicam, an inhibitor of COX-2 and the constitutively expressed COX-1, protect neurones against hypoxia/reoxygenation injury. Rat spinal cord cultures were exposed to hypoxia for 20 h followed by reoxygenation. Hypoxia/reoxygenation increased lactate dehydrogenase (LDH) release, which was inhibited by piroxicam (180-270 microM) and NS-398 (30 microM). Cell counts confirmed the neuroprotection. Western blotting revealed no COX-1 or COX-2 proteins even after hypoxia/reoxygenation. Production of prostaglandin E2 (PGE2), a marker of COX activity, was barely measurable and piroxicam and NS-398 had no effect on the negligible PGE2 production. Hypoxia/reoxygenation increased nuclear factor-kappa B (NF-kappaB) binding activity, which was inhibited by piroxicam but not by NS-398. AP-1 binding activity after hypoxia/reoxygenation was inhibited by piroxicam but strongly enhanced by NS-398. However, both COX inhibitors induced activation of extracellular signal-regulated kinase (ERK) in neurones and phosphorylation of heavy molecular weight neurofilaments, cytoskeletal substrates of ERK. It is concluded that piroxicam and NS-398 protect neurones against hypoxia/reperfusion. The protection is independent of COX activity and not solely explained by modulation of NF-kappaB and AP-1 binding activity. Instead, piroxicam and NS-398-induced phosphorylation through ERK pathway may contribute to the increased neuronal survival.
Vartiainen
N
N
A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Finland.
Huang
C Y
CY
Salminen
A
A
Goldsteins
G
G
Chan
P H
PH
Koistinaho
J
J
D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology; D024202:Electrophoretic Mobility Shift Assay; D002534:Hypoxia, Brain / Q000378:metabolism; D007150:Immunohistochemistry; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology*; D010894:Piroxicam / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*
D016861:Cyclooxygenase Inhibitors; D009578:Nitrobenzenes; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D010894:Piroxicam; D007770:L-Lactate Dehydrogenase; D011451:Prostaglandin-Endoperoxide Synthases