Abstract
Magnolol may have the potential to alleviate the progression of Alzheimer's disease (AD). The present study was conducted to investigate the broader mechanism of action of magnolol in AD pathogenesis. C57BL/6 mice were randomly divided into five groups (n=6 mice/group): i) Control; ii) AD model; iii) 5 mg/kg magnolol + AD model; iv) 10 mg/kg magnolol + AD model; and v) 20 mg/kg magnolol + AD model. A total of 7 days after modeling, the treatment groups were administered different doses of magnolol (5, 10 and 20 mg/kg) by gavage every day, and a Morris water maze test was conducted after 2 months of treatment. The impacts of magnolol on amyloid β (Aβ) plaque deposition and neuroinflammation were assessed using Congo red and immunofluorescence staining. Immunofluorescence staining results were supplemented with western blotting and reverse transcription-quantitative PCR to ascertain the role of magnolol in other pivotal pathological mechanisms, including the formation of intracellular neurofibrillary tangles, compromised synaptic plasticity, and astrocyte and microglia activation. Administration of magnolol effectively mitigated cognitive impairment, reduced Aβ plaque deposition and inhibited neuroinflammation in Aβ1-42-induced mice. Moreover, hippocampal levels of tau, phosphorylated (p-)tau, glycogen synthase kinase 3β (GSK3β), p-GSK3β, synaptophysin, brain-derived neurotrophic factor, glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 revealed that magnolol also limited neurofibrillary tangle formation, repaired synaptic plasticity, and inhibited astrocyte and microglia activation. In conclusion, the present findings broaden the current understanding of the mechanisms explaining the neuroprotective effects of magnolol against AD progression. Notably, it may inhibit multiple manifestations of AD, including plaques and neuroinflammation, while also exhibiting the capacity to restore AD-related neurological damage.