Western blot analysis of PKR-like ER (PERK), phosphorylate PERK (P-PERK), binding immunoglobulin protein (BIP), inositol-requiring enzyme (IRE-1α) and phosphorylate IRE-1α (P- IRE-1α) in hippocampus (A) and cortex (B). The expression of apoptosis proteinprotein disulfide isomerase (PDI), C/EBP homologous protein (CHOP), initiation factor 2 (eIF-2a) and phosphorylate eIF-2α (P- eIF-2α) in hippocampus (C) and cortex (D). BSYZ-L: Bushen-Yizhi (1.46 g/kg/d); BSYZ-M: Bushen-Yizhi (2.92 g/kg/d); BSYZ-H: Bushen-Yizhi (5.84 g/kg/d); DON: donepezil. Data represent mean ± SEM (n = 20 per group). #P < 0.05, ##P < 0.01, ###P < 0.001 vs. SAMR1; *P < 0.05, **P < 0.01, ***P < 0.001 vs. SAMP8.