Fig. 3.

Cortical cultures from WT or PARP-1^−/−(P^−/−) express equal levels of NMDA-R, GluR1, and GluR2/3 as determined by Western blot analysis. The experiment was performed twice with similar results. Cortical cultures from WT or PARP-1^−/− mice exposed to NMDA (500 μm), vehicle alone, and AMPA (50 μm) with or without the presence of the glutamate antagonist DNQX. PARP-1^−/− or WT cultures exposed to AMPA alone demonstrate significant percentage of cell death compared with control or DNQX-treated cultures (p < 0.01; ANOVA; mean ± SD). Unlike the substantial protection exhibited by PARP-1^−/− cultures to NMDA neurotoxicity compared with WT as shown previously (Eliasson et al., 1997), PARP-1^−/− cultures demonstrate a partial but significant percentage of protection to AMPA neurotoxicityin vitro (*p < 0.05, WT compared with PARP knock-outs; significance determined by ANOVA with Newman–Keuls post hoc analysis). Experiments were replicated a minimum of two times with at least 8000–20,000 neurons counted per experiment.