Activated astrocytes surrounding Aβ plaques are decreased in Tg2576 mice following vaccination. Astrocyte reactivity (GFAP, red) preferentially associates with Aβplaques (6E10, green) and is reduced in the hippocampus (A–E) and cortex (F–J) of Tg2576 mice following immunization with PBS control (A, F), 3A oligomer mimics (B, G), Aβ fibrils (C, H), Aβ oligomers (D, I), and IAPP oligomers (E, J). Cell nuclei were stained with DAPI (blue). Scale bar = 100 μm. Quantifications of GFAP immunoreactivity in the hippocampus (K) and cortex (L) demonstrate significant astrocytosis reduction in mice vaccinated with 3A and Aβ fibrils. Error bars represent standard errors of the mean (n = 3). *p < 0.05, ** p < 0.001 by one-way ANOVA test.