Fig. 9. Effect of prolonged treatment with NMDA on granule neuron viability. 7 DIV (A-C) or 14 DIV (D-F) cells were incubated with vehicle (control), or 100 µM NMDA for 48 hours and then incubated for 30 minutes in Locke's solution in the presence of the viability/cytotoxicity probes ethidium homodimer (8 µM) and calcein-AM (1 µM). Cell images were taken under the fluorescence microscope by exciting at 495 nm. A 590 nm band pass emission filter was used for the ethidium homodimer (B,E) and one of 530 nm band pass for calcein (A,D). Bar charts (C,E) represent the mean ± s.e.m. of the relative number of EthD-1 labelled cells in different preparations (three different cultures in which four different fields were counted. The total number of cells per field varies from 115 to 200) subjected to the treatment indicated. ^*P<0.05, ^**P<0.01 indicates a significant difference from control conditions (non-treated cells).