DISSOCIATION OF NITRIC-OXIDE GENERATION AND KAINATE-MEDIATED NEURONAL DEGENERATION IN PRIMARY CULTURES OF RAT CEREBELLAR GRANULE CELLS

In the presence of physiological concentrations of Mg2+ and in glycine-free buffer, the relationship between KA-mediated generation of NO and neurotoxicity in cultures of cerebellar granule cells of the rat was examined. The neuronal damage elicited by KA was not dependent on the presence Of L-arginine, a precursor of NO, since neither the potency nor magnitude of KA-mediated cell death was altered in either the absence or presence of exogenously applied L-arginine. Similarly, with the exception of 4-hydroxy-azobenzene-4'-sulfonic acid, disodium salt dihydrate (HBS), the salt associated with N(G)-monomethyl-L-arginine (di-(p-hydroxyazobenzene-p'-sulfonate) (MA(HBS)), treatment with several different competitive NO synthetase inhibitors did not provide protection against the toxicity of KA. However, the ability of KA to induce neuronal damage was significantly decreased in cerebellar granule cells treated with either HBS or alpha-tocopherol (VE). On the basis of these results, it is concluded that the generation of free radicals may be involved in the process of KA-elicited neuronal death in cultures of cerebellar granule cells but that this is unrelated to the synthesis of NO. This conclusion agrees with both in vivo and in vitro studies, implicating the involvement of free radicals in non-NMDA mediated neuronal damage.