Résumé
In this study, we analysed the implication of superoxide (
O
2
.
) and nitric oxide (NO
.) free radicals and their resulting product peroxynitrite (ONOO
−) in the neuronal death induced by the activation of the glutamatergic receptor of the
N-
methyl-
d-aspartate
(NMDA) subtype using cultured cerebellar granule cells. The NO
. donor SIN-1 (3-morpholinosydnonimine
N-ethylcarbamide), at concentrations which produced a much higher guanylate cyclase activation (i.e. NO
. concentration) than NMDA, was not neurotoxic and did not increase the NMDA-induced neuronal death. The absence of involvement of NO
. in NMDA-induced neuronal death was confirmed by the ineffectiveness of
l
-N
G
-
nitroarginine
(
l-Narg) as a neuroprotective compound. Electron paramagnetic resonance (EPR) experiments, using 5,5-dimethyl pyrroline 1-oxide (DMPO) as a spin trap, indicated that NMDA receptor stimulation led to the generation of
O
2
.
from at least 15–30 min. The generation of
O
2
.
by xanthine (XA)-xanthine oxidase (XO) induced a neuronal death similar to that of NMDA. XA-XO-induced neuronal death was suppressed by addition of either superoxide dismutase (SOD) plus catalase (CAT), or DMPO in the incubation medium. In contrast, NMDA-induced neuronal death was widely blocked by DMPO and other spin trap compounds, but not by SOD ± CAT. XA-XO-induced neuronal death was not potentiated by SIN-1 indicating that ONOO
− is not more toxic than
O
2
.
in our neuronal model.