Immunoreactivity of SIRT1 in homogenates isolated from NTG and AD-Tg mouse brain following NMN treatment. Each lane represents a different animal. (A) Representative Western blot images. (B) Significantly increased SIRT1 levels (ratio SIRT1:GAPDH) are observed in AD-Tg (vehicle) homogenates compared to NTG vehicle-treated animals. These levels are significantly reduced (~49%) by the addition of NMN in AD-Tg mice although they remain significantly elevated. NTG SIRT1 levels normalized to GAPDH = 0.004 as presented in (B). Data are presented as the average SIRT1 ± SE. N = 6 separate animals per group. **p ≤ 0.05.