AP bursting protects against NMDA-induced cell death. (A) Hippocampal neurons with (+) or without (-) 16 h bicuculline pretreatment (Bic) were incubated with (+) or without (-) 20 μM NMDA for 10 min. Five hours after NMDA washout the cells were fixed and stained with Hoechst 33258. Arrowheads indicate dead cells. Scale bar is equal to 10 μm. (B) Evaluation of neuronal cultures following treatment with bicuculline and NMDA showed the protective effect of bicuculline pretreatment on NMDA induced cell death. The graph represents the mean and SEM of five independent experiments. *** p < 0.001 independent samples t-test.