Aims: Baicalin (BAI), a flavonoid compound isolated from the root of Scutellaria baicalensis Georgi, has been established to have potent anti-inflammation and neuroprotective properties; however, its effects during Alzheimer's disease (AD) treatment have not been well studied. This study aimed to investigate the effects of BAI pretreatment on cognitive impairment and neuronal protection against microglia-induced neuroinflammation and to explore the mechanisms underlying its anti-inflammation effects.
Methods: To determine whether BAI plays a positive role in ameliorating the memory and cognition deficits in APP (amyloid beta precursor protein)/PS1 (presenilin-1) mice, behavioral experiments were conducted. We assessed the effects of BAI on microglial activation, the production of proinflammatory cytokines, and neuroinflammation-mediated neuron apoptosis in vivo and in vitro using Western blot, RT-PCR, ELISA, immunohistochemistry, and immunofluorescence. Finally, to elucidate the anti-inflammation mechanisms underlying the effects of BAI, the protein expression of NLRP3 inflammasomes and the expression of proteins involved in the TLR4/NF-κB signaling pathway were measured using Western blot and immunofluorescence.
Results: The results indicated that BAI treatment attenuated spatial memory dysfunction in APP/PS1 mice, as assessed by the passive avoidance test and the Morris water maze test. Additionally, BAI administration effectively decreased the number of activated microglia and proinflammatory cytokines, as well as neuroinflammation-mediated neuron apoptosis, in APP/PS1 mice and LPS (lipopolysaccharides)/Aβ-stimulated BV2 microglial cells. Lastly, the molecular mechanistic study revealed that BAI inhibited microglia-induced neuroinflammation via suppression of the activation of NLRP3 inflammasomes and the TLR4/NF-κB signaling pathway.
Conclusion: Overall, the results of the present study indicated that BAI is a promising neuroprotective compound for use in the prevention and treatment of microglia-mediated neuroinflammation during AD progression.
Keywords: Alzheimer's disease; baicalin; cognitive impairment; neuroinflammation; neuronal protection.
© 2018 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd.