Catalpol rescues cognitive deficits by attenuating amyloid ß plaques and neuroinflammation.

ABSTRACT

This study sought to investigate the anti-amyloid ß (Aß) and anti-neuroinflammatory effects of catalpol in an Alzheimer's disease (AD) mouse model. METHODS: The effects of catalpol on Aß formation were investigated by thioflavin T assay. The effect of catalpol on generating inflammatory cytokines from microglial cells and the cytotoxicity of microglial cells on HT22 hippocampal cells were assessed by real-time quantitative PCR, ELISA, redox reactions, and cell viability. APPswe/PS1ΔE9 mice were treated with catalpol, and their cognitive ability was investigated using the water maze and novel object recognition tests. Immunohistochemistry and immunofluorescence were used to probe for protein markers of microglia and astrocyte, Aß deposits, and NF-κB pathway activity. Aß peptides, neuroinflammation, and nitric oxide production were examined using ELISA and redox reactions. RESULTS: Catalpol potently inhibited Aß fibril and oligomer formation. In microglial cells stimulated by Aß, catalpol alleviated the expression of the proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and inducible nitric oxide synthase (iNOS) but promoted the expression of the anti-inflammatory cytokine IL-10. Catalpol alleviated the cytotoxic effects of Aß-exposed microglia on HT22 cells. Treatment with catalpol in APPswe/PS1ΔE9 mice downregulated neuroinflammation production, decreased Aß deposits in the brains and alleviated cognitive impairment. Catalpol treatment decreased the number of IBA-positive microglia and GFAP-positive astrocytes and their activities of the NF-κB pathway in the hippocampus of APPswe/PS1ΔE9 mice. CONCLUSION: The administration of catalpol protected neurons by preventing neuroinflammation and Aß deposits in an AD mouse model. Therefore, catalpol may be a promising strategy for treating AD.