ARC and Alzheimer disease: At 15 months-of-age, mice in the AD LPS-E group had lower (vs. the LPS group) or higher (vs. the CON group) levels of Syt1 and Arc mRNAs in CA1 and CA3 (P < 0.05 for all) and Syt1 mRNA in the DG (Ps < 0.01; Figures 6(b), 6(c), 6(e), and 6(f)).