Sj. Hewett et al., Cyclooxygenase-2 contributes to N-methyl-D-aspartate-mediated neuronal cell death in primary cortical cell culture, J PHARM EXP, 293(2), 2000, pp. 417-425
Citations number
51
Categorie Soggetti
Pharmacology & Toxicology
Journal title
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS
Cyclooxygenase isozymes (COX-1 and COX-2) are found to be constitutively ex
pressed in brain, with neuronal expression of COX-2 being rapidly induced a
fter numerous insults, including cerebral ischemia. Because overactivation
of N-methyl-D-aspartate (NMDA) receptors has been implicated in the cell lo
ss associated with ischemia, we characterized the expression of the COX iso
zymes in murine mixed cortical cell cultures and used isozyme-selective inh
ibitors to determine their relative contribution to NMDA receptor-stimulate
d prostaglandin (PG) production and excitotoxic neuronal cell death. Immuno
cytochemical analysis of mixed cortical cell cultures revealed that COX-2 e
xpression was restricted to neurons, whereas COX-1 was expressed in both ne
urons and astrocytes. Brief exposure to NMDA (5 min; 100 mu M) elicited a t
ime-dependent accumulation of PGs in the culture medium that preceded neuro
nal cell death and correlated with the induction of COX-2 mRNA. COX-1 expre
ssion remained unchanged. Flurbiprofen, a nonselective COX-1/COX-2 inhibito
r, blocked NMDA-stimulated PG production and attenuated neuronal death in a
concentration-dependent manner. Similar results were obtained with the spe
cific COX-2 inhibitor NS-398 (10-30 mu M) but not with the selective COX-1
inhibitor valeryl salicylate (10-300 mu M). Inhibition of total constitutiv
e COX activity with aspirin (100 mM, 1.5 h) before NMDA exposure did not pr
event subsequent NMDA-mediated neuronal cell death. However, neuronal injur
y in aspirin-pretreated cultures was attenuated by flurbiprofen administrat
ion after NMDA exposure. Finally, the protection afforded by COX-2 inhibiti
on was specific for NMDA because neither flurbiprofen nor NS-398 protected
neurons against kainate-mediated neurotoxicity. Together, these results sup
port the conclusion that newly synthesized COX-2 protein contributes to NMD
A-induced neuronal injury.