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

Alzheimers disease is characterized by abnormal {beta}-amyloid (A{beta}) 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 myricetins protective effect on the toxicity induced by the A{beta}42 oligomer. Neuronal SH-SY5Y cells were pretreated with myricetin before incubation with A{beta}42 oligomer. The levels of pre- and postsynaptic proteins, mitochondrial division and fusion proteins, glycogen synthase kinase-3 {beta} (GSK-3{beta}) 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 A{beta}42 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 A{beta}42 oligomer. Moreover, myricetin prevented the A{beta}42 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-3{beta} and ERK 1/2 signaling pathways. In conclusion, this study provides new insight into the neuroprotective mechanism of myricetin against A{beta}42 oligomer-induced toxicity.