Paeonolum protected against MPP+-induced neurotoxicity in cultured PC12 cells. Cells were preincubated with paeonolum for 30 min and then exposed to 250 μM MPP+ for an additional 24 h. Pretreatment with different concentrations of paeonolum significantly attenuated MPP+-induced PC12 cell damage. Cell viability is indicated by MTT values of each experimental group and are expressed as a percentage of the of control group. Cellular morphological changes were detected by inverted microscopy. Representative images were selected from four independent experiments. Bar graph shows the percentage of cells with abnormal nuclei content in different experimental groups. Values are means ± SEM. *P < 0.01 compared with vehicle control. The results were obtained from four independent experiments performed in triplicate.