Curcumin Improves Neurogenesis in Alzheimer's Disease Mice via the Upregulation of Wnt/β-Catenin and BDNF

Adult neurogenesis in the dentate gyrus (DG) is impaired during Alzheimer's disease (AD) progression. Curcumin has been reported to reduce cell apoptosis and stimulate neurogenesis. This study aimed to investigate the influence of curcumin on adult neurogenesis in AD mice and its potential mechanism. Two-month-old male C57BL/6J mice were injected with soluble beta-amyloid (A beta 1-42) using lateral ventricle stereolocalization to establish AD models. An immunofluorescence assay, including bromodeoxyuridine (BrdU), doublecortin (DCX), and neuron-specific nuclear antigen (NeuN), was used to detect hippocampal neurogenesis. Western blot and an enzyme-linked immunosorbent assay (ELISA) were used to test the expression of related proteins and the secretion of brain-derived neurotrophic factor (BDNF). A Morris water maze was used to detect the cognitive function of the mice. Our results showed that curcumin administration (100 mg/kg) rescued the impaired neurogenesis of A beta 1-42 mice, shown as enhanced BrdU+/DCX+ and BrdU+/NeuN+ cells in DG. In addition, curcumin regulated the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) -mediated glycogen synthase kinase-3 beta (GSK3 beta) /Wingless/Integrated (Wnt)/beta-catenin pathway and cyclic adenosine monophosphate response element-binding protein (CREB)/BDNF in A beta 1-42 mice. Inhibiting Wnt/beta-catenin and depriving BDNF could reverse both the upregulated neurogenesis and cognitive function of curcumin-treated A beta 1-42 mice. In conclusion, our study indicates that curcumin, through targeting PI3K/Akt, regulates GSK3 beta/Wnt/beta-catenin and CREB/BDNF pathways, improving the adult neurogenesis of AD mice.