Figure 3: AST restores the expression of hippocampal synaptic proteins in aging mice. (A–D) The immunoreactivities of BDNF (A), SYN (B), SIRT1 (C), and PGC-1α (D) in the hippocampal CA3 region by immunofluorescence staining (original magnification, 400×). Compared with the Aβ group, the Aβ + AST group showed stronger immunoreactivities of BDNF, SYN, SIRT1, and PGC-1α. Scale bars: 20 μm. (E) Quantitative analysis of hippocampal synaptic proteins. Data are expressed as the mean ± standard deviation. *P < 0.05, vs. control group; #P < 0.05, vs. Aβ + AST + NAM group (independent samples t-test). AST: Astaxanthin; Aβ: amyloid beta; BDNF: brain-derived neurotrophic factor; NAM: nicotinamide; PGC-1α: peroxisome proliferator-activated receptor gamma co-activator-1α; SIRT1: sirtuin 1; SYN: synaptophysin.