Neural Regeneration Research ›› 2015, Vol. 10 ›› Issue (7): 1113-1119.doi: 10.4103/1673-5374.160106

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The role of quercetin on the survival of neuron-like PC12 cells and the expression of α-synuclein

Tae-Beom Ahn 1, Beom S. Jeon  2, 3   

  1. 1 Department of Neurology, School of Medicine, Kyung Hee University, Seoul, Republic of Korea
    2 Department of Neurology, College of Medicine, Seoul National University, Seoul, Republic of Korea
    3 Department of Neurology, Movement Disorder Center, Parkinson Study Group, and Neuroscience Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
  • Received:2015-05-06 Online:2015-07-24 Published:2015-07-24
  • Contact: Beom S. Jeon, M.D., Ph.D., brain@snu.ac.kr.
  • Supported by:

    This research was supported by a grant (03-2010-0240) from the Seoul National University Hospital Research Fund (BSJ) and Yuhan Cooperation (Seoul, Republic of Korea; TBA).

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Abstract:

Both genetic and environmental factors are important in the pathogenesis of Parkinson’s disease. As α-synuclein is a major constituent of Lewy bodies, a pathologic hallmark of Parkinson’s disease, genetic aspects of α-synuclein is widely studied. However, the influence of dietary factors such as quercetin on α-synuclein was rarely studied. Herein we aimed to study the neuroprotective role of quercetin against various toxins affecting apoptosis, autophagy and aggresome, and the role of quercetin on α-synuclein expression. PC12 cells were pre-treated with quercetin (100, 500, 1,000 μM) and then together with various drugs such as 1-methyl-4-phenylpyridinium (MPP+; a free radical generator), 6-hydroxydopamine (6-OHDA; a free radical generator), ammonium chloride (an autophagy inhibitor), and nocodazole (an aggresome inhibitor). Cell viability was determined using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltertazolium bromide (MTT) assay. Apoptosis was detected by annexin V-fluorescein isothiocyanate and propidium iodide through the use of fluorescence activated cell sorter. α-Synuclein expression was detected by western blot assay and immunohistochemistry. The role of α-synuclein was further studied by knocking out α-synuclein using RNA interference. Cell viability increased at lower concentrations (100 and 500 μM) of quercetin but decreased at higher concentration (1,000 μM). Quercetin exerted neuroprotective effect against MPP+, ammonium chloride and nocodazole at 100 μM. MPP+ induced apoptosis was decreased by 100 μM quercetin. Quercetin treatment increased α-synuclein expression. However, knocking out α-synuclein exerted no significant effect on cell survival. In conclusion, quercetin is neuroprotective against toxic agents via affecting various mechanisms such as apoptosis, autophagy and aggresome. Because α-synuclein expression is increased by quercetin, the role of quercetin as an environmental factor in Parkinson’s disease pathogenesis needs further investigation.

Key words: quercetin, Parkinson’s disease, α-synuclein, Lewy body, PC12 cells, cell viability, cell death, neuroprotection