P2X6 (A), P2Y2 (B), and P2Y14 (C) mRNA expression does not significantly change with age. P2R mRNA levels in freshly-isolated microglia from male and female mice of different ages and mixed-sex primary neonatal microglial cultures were determined using qRT-PCR. Expression was normalized to β-actin and average folds (+/- SEM) are graphed relative to the 3d time point of each sex. n = 4–6; for primary cells n = 5 separate culture preparations. # 0.05 < p ≤ 0.10 vs. 3d.