Protective effects of Gynostemma pentaphyllum polysaccharides on PC12 cells impaired by MPP+

The aim of the present study was to explore the neuroprotective effects of Gynostemma pentaphyllum polysaccharides (GP) in a 1-methyl-4-phenylpyridiniumion (MPP+)-induced cellular model of Parkinson's disease (PD) and the underlying mechanisms. Our results indicated that exposure of PC12 cells to 1 mM MPP+ significantly decreased the cell viability when examined by MTT assay, LDH assay, and annexin-V-FITC and propidium iodide (PI) apoptosis detection assays. MPP+-induced apoptosis in PC12 cells was accompanied by an increased Bax/Bcl-2 ratio, release of mitochondrial cytochrome c into the cytosol, activation of caspase-3/9 and cleavage of poly (ADP-ribose) polymerase (PARP). However, pretreatment of PC12 cells with 50 μg/ml GP prior to MPP+ exposure effectively attenuated the cytotoxicity and improved cell viability via inhibiting elevated Bax/Bcl-2 ratio, as well as the release of cytosolic cytochrome c. Furthermore, GP was effective in attenuating caspase-3/9 activation and cleavage of PARP in MPP+-exposed PC12 cells. These results suggest that the GP has protective effects against MPP+-induced neuronal apoptosis in PC12 cells by suppressing apoptosis-related protein, and therefore, might likely be a promising candidate for the treatment of Parkinson's disease (PD).