Mounting evidence suggests that mitochondrial dysfunction and impaired mitophagy lead to Parkinson's disease (PD). Quercetin, one of the most abundant polyphenolic flavonoids, displays many health-promoting biological effects in many diseases. We explored the neuroprotective effect of quercetin in vivo in the 6-hydroxydopamine (6-OHDA)-lesioned rat model of PD and in vitro in 6-OHDA-treated PC12 cells. In vitro, we found that quercetin (20 μM) treatment improved mitochondrial quality control, reduced oxidative stress, increased the levels of the mitophagy markers PINK1 and Parkin and decreased α-synuclein protein expression in 6-OHDA-treated PC12 cells. Moreover, our in vivo findings demonstrated that administration of quercetin also relieved 6-OHDA-induced progressive PD-like motor behaviors, mitigated neuronal death and reduced mitochondrial damage and α-synuclein accumulation in PD rats. Furthermore, the neuroprotective effect of quercetin was suppressed by knockdown of either Pink1 or Parkin.
