GLUTAMATE RECEPTORS INDUCE A BURST OF SUPEROXIDE VIA ACTIVATION OF NITRIC-OXIDE SYNTHASE IN ARGININE-DEPLETED NEURONS

We have previously shown in cultured cerebellar granule neurons (Lafon -Cazal, M., Pietri, S., Culcasi, M., and Bockaert, J. (1993) Nature 36 4, 535-537) that upon N-methyl-D-aspartate stimulation, a nitric oxide synthase (NOS)-independent, arachidonic acid-dependent generation of superoxide free radicals (O-2(radical anion)) is observed after a lag time of 10-15 min. Using the electron spin resonance spin trapping tec hnique, we show that N-methyl-D-aspartate stimulation produced a more rapid burst of O-2(radical anion) in L-arginine (L-Arg)-depleted neuro ns, These O-2(radical anion) radicals are synthesized by NOS. KCl and kainate, which also stimulated NOS in these neurons, produced this rap id burst of O-2(radical anion), which was blocked as follows: (a) in t he presence of L N-G-nitro-arginine (L-Narg), and (b) by L-Arg repleti on. This burst of O-2(radical anion) was arachidonic acid-independent, and its time course was similar to that of nitric oxide production. I t was also responsible for a weak but significant cell death that was suppressed by L-Narg and L-Arg.