Akt/Nrf2 Activated Upregulation of Heme Oxygenase-1 Involves in the Role of Rg1 Against Ferrous Iron-Induced Neurotoxicity in SK-N-SH Cells

Iron accumulation is considered to be involved in the pathogenesis of Parkinson's disease (PD). Our previous studies have observed that Rg1, a major pharmacologically active ingredient from Ginseng, could protect dopaminergic neurons by reducing nigral iron levels through regulating the expression of iron transporters in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced PD mice. The aim of this study is to investigate other mechanism involved in the cytoprotection of Rg1 against iron-induced neurotoxicity in human neuroblastoma SK-N-SH cells. Significant rescue of Rg1 on cell viability against 100 mu M ferrous iron-induced neurotoxicity was observed. Upregulation of heme oxygenase-1 (HO-1) and Cu-Zn superoxide dismutase (Cu/Zn SOD) were observed in Rg1 pretreated group. Moreover, Rg1 pretreatment induces Nrf2 nuclear translocation, which is upstream of HO-1 expression, and activated PI3K/Akt pathway was also observed in Rg1 pretreated group. This could antagonize iron-induced increase in intracellular reactive oxygen species and decrease in mitochondrial transmembrane potential. These results suggest that the neuroprotective effects of Rg1 against iron toxicity are attributed to the anti-oxidative properties by activating Akt/Nrf2 pathway and increasing Nrf2-induced expression of HO-1 and Cu/Zn SOD.