Polygonatum sibiricum Polysaccharides Protect against MPP-Induced Neurotoxicity via the Akt/mTOR and Nrf2 Pathways

Figure 4

PSP rescues MPP+-induced oxidative stress damage by activating the Nrf2 pathway. (a) LDH assay showed PSP exerts strong cytoprotective activity. The medium was collected from N2a cells that were pretreated with PSP with indicated concentrations for 24 h then MPP+ (500 μM) treatment overnight before cell harvesting (). (b) GSH/GSSG ratio analysis for whole-cell lysates of N2a cells (). (c) Western blot analyses showed that the expression of the proteins in the Nrf2 signaling pathway, as well as TH, was restored after PSP treatment. Blot data are representative of three independent experiments. Quantification of relative protein levels is shown in the right panel (). (d) Representative images of ROS staining by the indicator dye CM-H₂DCFAD for N2a cells. Scale bar, 50 μm. (e) Quantification of ROS intensities using the ratio of fluorescent intensity and cell numbers (). (f) Representative images of immunofluorescent staining of TH/TUNEL in N2a cells treated with indicated conditions. Scale bar, 50 μm. Quantification of TH intensity (g) and TUNEL-positive cells (h) are shown (). Data represent the . , , and by Student’s -test (WB statistics) or one-way ANOVA with Tukey’s multicomparison test (e), (g), and (h).

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