Neuronal expression of EP1 receptor in cultures with or without microglia. Neuronal-enriched cultures (A), neuronal-enriched cultures with microglia (B) and mixed cultures (C) were immunostained with antibodies against the neuronal-specific marker, MAP-2 (green), EP1 (red) and nuclei were stained with propidium iodide (PI) (blue) prior to confocal microscopy. Nuclei with different amounts of EP1 staining are indicated with arrows in each panel. All images were captured at 60× magnification and the bar indicates 10 microns. The relative amounts (+SEM) of nuclear EP1 expression for neuronal-enriched (NE), NE + microglia, and mixed cultures was determined for 60–75 neurons for each condition (see methods) and plotted in panel D. The neuronal-enriched cultures lacking microglia had significantly higher amounts of nuclear EP1 expression (ANOVA Tukey-Kramer multiple comparison test).