Figure 4

PARP-1 regulates Aβ-induced microglial activation. A, Photomicrographs show microglial morphology and Iba-1expression (red) in mouse hippocampus 6 h after stereotaxic injection of FAM-Aβ (green) or saline vehicle. The needle track is visible (and the edge is drawn) at the left-hand edge of each composite image. Microglial activation induced by Aβ injection was blocked by the PARP-1 inhibitor PJ34 (PJ) and in PARP1 ^-/- microglia. Injection of saline or reverse sequence Aβ (rAβ, not shown) produced microglial activation only at the needle track. B, High magnification views show ramified microglia with numerous long, thin, branched processes (arrows), and activated microglia with shorter, thickened processes (arrowheads). C, Quantification of microglia activation is presented in stacked columns presenting the scores for both microglial number and morphology. * p < 0.05; # p < 0.05 vs. saline; n = 4.