Introduction: Progressive accumulation of amyloid-β (Aβ) is a pathological trait of Alzheimer's disease (AD). Amyloid-β increases free radical production in neuronal cells, leading to neuronal cell death. Hormone replacement therapy can reduce the incidence of AD, and oestrogen significantly improves the clinical signs in patients with AD. However, the long-term use of oestrogen causes a variety of diseases. Phytoestrogens have been reported to bind and activate oestrogen receptors in mammals and humans to produce oestrogen-like or anti-oestrogen-like effects. Kaempferol is a flavonoid phytoestrogen that can produce a certain protective effect in neurons. However, the molecular mechanism of kaempferol in AD is unclear.
Material and methods: This study used pheochromocytoma (PC-12) cells that were damaged by Aβ25-35 as an in vitro model of AD, and oestradiol was a positive control. The cells were incubated with kaempferol alone or in combination with fulvestrant (an antagonist of ER) and U0126 (an inhibitor of ERK) in Aβ25-35 culture. Cell activity was measured by the MTT method. Cell apoptosis was evaluated by flow cytometry. Gene and protein expression levels were tested by qRT-PCR and Western blotting.
Results: This study demonstrated that kaempferol protected PC-12 cells from Aβ25-35-induced cell death and apoptosis in a dose-dependent manner. Treatment with fulvestrant (an antagonist of ER) and U0126 (an inhibitor of ERK) significantly increased the apoptosis of PC-12 cells. Moreover, kaempferol promoted the expression of anti-apoptotic molecules and inhibited the expression of pro-apoptotic molecules, which were blocked by fulvestrant and U0126.
Conclusions: Kaempferol protected PC-12 cells against Aβ25-35-induced cell apoptosis through the ER/ERK/MAPK signalling pathway.
Keywords: Alzheimer’s disease; MAPK signalling pathway; kaempferol; oestrogen receptors; pheochromocytoma.
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