The Molecular Mechanisms Of Protective Efect Of Tea Polyphenols On MPP-induced PC12 Cell Injury

【Background and Purpose】Parkinson's disease (PD) is an age-related disorder characterized by progressive degeneration of dopaminergic neurons in the substantia nigra (SN)。As the ageing period advent forthcoming, the prevalence and incidence rate of PD increases year by year. The PD has bring up heavy burden owing to its serious injured, progression and incurable.Although the pathogenesis of PD is still indefinite ,Recently, with the development of research about PD ,we found there are several factors that contribute to the PD, such as oxidative stress ,calcium overload and inflammatory. Among all of this factors, oxidative stress was generally accepted as the key factor. so antioxidant strategies have been at focus as a potential approach of neuroprotection of PD. (-)-epigallocatechin gallate(EGCG)is a important antioxidant , Which was shown to attenuate eurotoxicity induced by oxidized low-density lipoprotein in mouse-derived striatal neurons. Tea extracts and EGCG attenuated the neurotoxic action of 6-hydroxydopamine in rat PC12 and human neuroblastoma SH-SY5Y cells. But the research of The neuroprotective molecular mechanisms of (-)-epigallocatechin-3-gallate is rare, so the experiment maybe significant in theory and clinic practice.【Objective】Investigate the Protective effects of EGCG on PC12 cells from MPP~+ induced damage and the mechanisms.【Methods】1,we established an in vitro model induced by PQ in high differentiated PCI2 cells,the PC12 cells was divided into six different groups: they are blank control group(A group), ,MPP~+ group(B group),EGCG group(C group),U120 group(D group),EGCG and MPP~+ group(E group), EGCG and U120 and MPP~+ group(F group).2,MTY assay was used to detect the PC12 cell viability of each group.3,Protein extracts and RNA of each group was prepared, then use Western blot to analyses expression of transcription factor NRF2 and used real-time PCR to analysis the RNA expression of NQO1 and HO-1.4,Statistical analysis.【Results】MPP~+ (500umol/L)decreased the cell viability of PC12 cells, Pretreatment of PC12 cells with lower concentration of EGCG (1.25—10umol/L)for an hour restored the decreasedcell viability。western blot analysis showed that treated with MPP~+ increase NRF2 expression and nuclear level of NRF2, pretreatment of PC12 cells with EGCG obvious increase nuclear level of NRF2, besides, pretreated with U120 could inhibit this effect of EGCG. The difference is obvious (P<0.05).【Conclusions】EGCG was highly effective on inhibiting the MPP~+-induced neurotoxicity in cultured rat adrenal gland pheochromocytoma cell line (PC12 cells). Whose neuroprotective may contribute to activateing the NF-E2-related factor-2 (Nrf2)/antioxidant response element (ARE) signaling pathway and inducing the antioxidant enzymes expression ,such as NQO1 and HO-1. also, our research suggest that the PI3K/AKT pathway might be a crucial upstream signaling pathway that mediates the Nrf2-related cytoprotective effect of EGCG.