BrdU injections and tissue preparation
The TgAPP/PS1 and the WT mice were intraperitonially injected with 75 mg/kg 5-bromo-2-deoxyuridine solution (BrdU; Sigma, St. Louis, MO, USA) daily during the last 7 days of treatment. One day after the last injection, animals were anesthetized with phenobarbital and perfused transcar- dially with 4% paraformaldehyde in phosphate buffer (PF). The brains were removed, stored overnight in 4% PF, and transferred into 30% sucrose. Coronal sections (30 m) were cut on a Bright OTF5000 Cryostat (Jencons Scientific Inc., Bridgeville, PA, USA) and stored at 20°C in a cryopro- tectant. For Western blotting, the hippocampus was dissected immediately after removal of the brain from non-BrdU- injected mice and stored at 80°C.