Excitotoxicity assay and neuroprotection by Ono 8711. Fields of neuronal-enriched cultures were photographed before treatment with vehicle (A) or the EP1 receptor antagonist Ono 8711 (B). These cultures were then treated with NMDA (15 μM) and photographed twenty hours later after staining with trypan blue dead cell stain for vehicle (C) and Ono 8711 (D). Examples of cells that survived NMDA treatment and excluded trypan blue are indicated by a black arrow in each panel. An example of a cell in each field that was killed by NMDA (as indicated by staining with trypan blue) is indicated by a green arrow. The numbers of neurons were counted for each of the cultures before and after NMDA (as non Trypan-stained cells). In this example, the addition of 30 nM Ono 8711 increased the percent of surviving neurons from 20% to 50%. Images were captured at 20 × magnification.