Myricetin protected against Aβ oligomer-induced synaptic impairment, mitochondrial function and oxidative stress in SH-SY5Y cells via ERK1/2/GSK-3β pathways

Abstract

AbstractAlzheimer’s disease is characterized by abnormal β-amyloid (Aβ) plaque accumulation, tau hyperphosphorylation, reactive oxidative stress, mitochondrial dysfunction and synaptic loss. Myricetin, a dietary flavonoid, has been shown to have neuroprotective effects in vitro and in vivo. Here, we aimed to elucidate the mechanism and pathways involved in myricetin’s protective effect on the toxicity induced by the Aβ42 oligomer. Neuronal SH-SY5Y cells were pretreated with myricetin before incubation with Aβ42 oligomer. The levels of pre- and postsynaptic proteins, mitochondrial division and fusion proteins, glycogen synthase kinase-3 β (GSK-3β) and extracellular regulated kinase (ERK) 1/2 were assessed by Western blotting. Flow cytometry assays for mitochondrial membrane potential (JC1) and reactive oxidative stress, as well immunofluorescence staining for lipid peroxidation (4-HNE) and DNA oxidation (8-OHdG), were performed. We found that myricetin prevented Aβ42 oligomer-induced tau phosphorylation and the reduction in pre/postsynaptic proteins. In addition, myricetin reduced reactive oxygen species generation, lipid peroxidation, and DNA oxidation induced by the Aβ42 oligomer. Moreover, myricetin prevented the Aβ42 oligomer-induced reduction in mitochondrial fusion proteins (mitofusin-1, mitofusin-2), fission protein (dynamin-related protein 1) phosphorylation, and mitochondrial membrane potential via the associated GSK-3β and ERK 1/2 signaling pathways. In conclusion, this study provides new insight into the neuroprotective mechanism of myricetin against Aβ42 oligomer-induced toxicity.