Loss of synapses has been correlated with dementia in Alzheimer's disease (AD) as an early event during the disease progression. Hence, synaptogenesis and neurogenesis in adulthood could serve as a therapeutic target for the prevention and treatment of AD. Recently, we have demonstrated enhanced hippocampal neurogenesis by oral administration of Ginkgo biloba extract (EGb 761) to a mouse model of AD. This study aims to identify the constituents that contribute to EGb 761-induced neurogenesis. Among the constituents tested, bilobalide and quercetin significantly increased cell proliferation in the hippocampal neurons in a dose-dependent manner. Bilobalide and quercetin also enhanced phosphorylation of cyclic-AMP Response Element Binding Protein (CREB) in these cells, and elevated the levels of pCREB and, brain-derived neurotrophic factor in mice brain. Immunofluorescence staining of synaptic markers shows remarkable dendritic processes in hippocampal neurons treated with either quercetin or bilobalide. Furthermore, both constituents restored amyloid-β oligomers (also known as ADDL)-induced synaptic loss and phosphorylation of CREB. The present findings suggest that enhanced neurogenesis and synaptogenesis by bilobalide and quercetin may share a common final signaling pathway mediated by phosphorylation of CREB. Despite a recent report showing that EGb 761 was insufficient in prevent dementia, its constituents still warrant future investigation.
- Amyloid-beta derived diffusible ligands (ADDL)
ASJC Scopus subject areas
- Clinical Psychology
- Geriatrics and Gerontology
- Psychiatry and Mental health