Figure 2.

PGE₂ is neuroprotective in cultured hippocampal neurons but not in organotypic hippocampal slices. A, PGE₂ administration at submicromolar concentrations promotes protection in hippocampal cultures stimulated with glutamate (100 μm) for 24 hr (n = 4 wells per condition; ^*p < 0.02; ^**p < 0.01; representative of 3 experiments). B, Increasing concentrations of PGE₂ had no effect on neuronal viability when assayed in organotypic hippocampal slices treated with 1 hr NMDA (10 μm), suggesting a negative effect of PGE₂ at the level of astrocytes in neutralizing the protective effects of PGE₂ on pure hippocampal cultures. Neuronal death in CA1 is measured by percentage of maximal PI fluorescence (n = 10-15 slices per condition; n = 6 experiments). Concentrations of PGE₂ were used at submicromolar concentrations to avoid the cross-activation of other PG receptors at higher concentrations (Breyer et al., 2001).