Glutamate toxicity in primary cerebellar cultures from mouse brain is unaffected by changes in cGMP levels

During evaluation of potential end-points for in vitro neurotoxicity screening we investigated what influence changes in cyclic GMP (cGMP) levels might exert on the degree of glutamate (Glu)-induced neurotoxicity in primary cultures of mouse cerebellar granule cells. Depletion of Glu-stimulated cGMP levels by N-methyl-D-aspartate receptor antagonists fully protected against Glu-induced toxicity. However, when Glu-stimulated cGMP levels were either depleted or elevated by the use of a variety of pharmacological agents acting intracellularly at various points of the NO/cGMP signalling pathway the degree of cytotoxicity exerted by Glu was unaltered. These results imply that cGMP and NO do not modulate the toxic effects of Glu and are therefore unsuitable as biomarkers of excitotoxicity in these cells.