Fig. 4.

Effects of LPS on EP4 and EP2 mRNA expression. a, b LPS strongly depresses EP4 mRNA expression versus naïve cells, whereas it increases EP2 mRNA expression (n = 6–7 in three independent cultures for each cell type) in microglia (a) and astroglia (b) at 8 h. The level of mRNA for each EP and cell type is expressed as fold versus the corresponding basal mRNA levels in non-stimulated cells (control). c The intensity of microglia EP4 immunoreactivity is strongly reduced 24 h after LPS exposure (n = 4 in two independent experiments). d Microglia EP2 immunoreactivity is detected in a peri-nuclear/nuclear localization 24 h after LPS (n = 3 replicates per treatment group in three independent experiments). e Western blotting shows increased EP2 expression after LPS in microglia and macrophages. f Quantification of EP2 protein expression in control microglia and 8 and 24 h after LPS, where values (EP2/GAPDH ratio) are expressed as fold versus control (*p < 0.05, n = 3 replicates per time point in two independent experiments). g Quantification of EP2 protein (EP2/GAPDH ratio) in macrophages (n = 3 replicates in three experiments) also shows a progressive increase with time after LPS. Data were fit to a sigmoidal equation with non-linear regression analysis (r ² = 0.83). h EP2 is found in the nuclear fraction of macrophages 24 h after LPS (three different cultures, n = 3 in each culture). Scale bar, 25 μm. **p <0.01, ***p <0.001 vs. control