The Research Of Neuroprotective Effect Of Edaravone For The Differentiated PC12 Cells Infected By PrP106-126 Peptide

Prion protein diseases are infectious, inherited, sporadic spongiform degeneration encephalopathies caused by prion protein conformational change. CJD is the most common form of human being prion protein diseases. CJD is a rare disease that occurs in three forms: sporadic, genetic, and iatrogenic. More recently, a new variants of CJD(nvCJD) has been reported. All forms of transmissible spongiform encephalopathies (TSEs) are characterized by spongiform degeneration of the brain, reactive gliosis, and neuronal loss. They are associated with the accumulation of an abnormal isoform (PrPsc) of the cellular prion protein (PrPc) in the brain. The scrapie prion protein (PrPsc), which is formed from PrPc, is assumed to be the etiological agent of TSE.PrP106-126 is a synthetic peptide consisting of amino-acid residues 106-126 of human PrPc , is able to polymerize into amyloid-like fibrils in vitro, like PrPsc. It is neurotoxic and induces activation of astroglial and microglial cells in vitro. So PrP106-126 can serve as a model to study the cellular effects of PrPsc.Edaravone (2-methyl-1-phenyl-2-pyrazolin-5-one, MCI-186) is free-radial scavenger that has been evaluated as a neuroprotective compound which reduces the increase of hydroxyl radical and superoxide anion level in several models of cerebral ischemia. In addition, edaravone not only has antioxident action, but also protects cells from apoptosis. However, little information is available on antioxidant edaravone in regulating oxidative stress and apoptosis such as the Bcl-2/Bax apoptotic pathway via mitochondria after the differentiated PC12 cells infected by prion protein 106-126 peptide at cellular level.In this experiment, the neuroprotective effects of free scavenger( edaravone ) for the differentiated PC12 cells infected by prion protein 106-126 peptide was investigated. Our results showed that edaravone is a relatively more potent neuroprotective drug for preventing PC12 cells from PrP106-126 damage. First, we found a perfect model to study the cellular toxicity of prion protein 106-126 peptide. Then by observing the nuclear morphology changes and flow cytometric analysis, edaravone showed its significant effect on protecting differentiated PC12 cells against prion protein 106-126 peptide induced apoptotic cell death. In these cells, the level of glutathione(GSH) and activities of superoxide dismutase(SOD) were augmented and malondialdehyde(MDA) were abased. In addition, edaravone also protected against cell damage induced by PrP106-126, which generated hydroxy radicals(.OH) by the Fenton reaction. These results suggest that edaravone is very effective in preventing oxidative stress triggered by deterioration of cellular functions to reduce ROS levels. Edaravone can protect the differentiated PC12 cells infected by prion protein 106-126 peptide against oxidative stress probably due to stimulating endogenous antioxidant defense mechanism.Treatment with edaravone significantly protected against PrP106- 126-induced apoptosis/necrosis observed the nuclear morphological changes and measured useing flow cytometric analysis. Both necrosis and apoptosis were precisely quantified using propidium ioide(PI) and Annexin-â…¤dual staining. The apoptosis in PrP106-126-induced PC12 cells was associated with loss of mitochondrial membrane potential, the formation of ROS, GSH depletion, suppressions of SOD, activation of caspase-3 , down-regulation of Bcl-2 and up-regulation of Bax. In contrast, treatment of PC12 cells with edaravone significantly prevented the above-mentioned mitochondrial dysfunction.In summary, our results extended edaravone neuroprotective mechanism, to determine that edaravone protects PC12 cells from apoptosis through attenuating the damage of mitochondria, suppresses the Bax protein overexpression, elevating the Bcl-2 protein expression on the critical hinge for apoptosis, inhibits the molecular pathway upstream of caspase. Our research showed that edaravone is a very safe and effective neuroprotective drug against oxidative stress, apoptosis and provide a useful therapeutic strategy for the treatment of oxidative stress-induced neurodegenerative disease such as prion protein diseases.