Amyloid-beta Induced Neurotoxicity Impairs Cognition and Adult Hippocampal Neurogenesis in a Mouse Model for Alzheimer’s Disease

Background: Neurogenesis, the key mechanism to generate new neurons from existing stem cell niches continues throughout the life in the adult mammalian brain, although decelerate with aging or the progression of neurodegenerative disorders like Alzheimer’s disease (AD). In the past few years, impaired adult hippocampal neurogenesis emerged as a contributing hallmark of AD pathophysiology along with amyloid beta (Aβ) and tau hyper phosphorylation-induced neurotoxicity. However, no conclusive evidence exists that indicates the up/down-regulation of adult hippocampal neurogenesis during the course of AD progression. Methods: In this study, we examined alterations in adult hippocampal neurogenesis and cognitive deficits using Aβ(1-42)-induced mouse model of AD. Results: Our results demonstrate that Aβ administration induces an anxiety like behavior and impairs spatial and non-spatial memory and learning in BALB/c mice. Extensive neuronal loss was also evident in the dentate gyrus (DG), CA1, CA2 and CA3 regions of hippocampus in Aβ-treated animals. Furthermore, Aβ-exposure markedly reduced the real-time expression of markers of cell proliferation and migration i.e. Ki67 and DCX, whereas immunohistochemistry analysis revealed a substantial reduction in the expression levels of Ki67 and NeuN. Conclusion: Our findings highlight the association of Aβ-induced neurotoxicity with altered neurogenesis and memory formation; however further insight is warranted to explore the underlying molecular pathway(s). Moreover, the treatment strategies aiming to repair the adult hippocampal neurogenesis hold potential as AD therapeutics.