Abstract: AimTo explore possible signal transmission way through which ginsenoside Rg1 protect cells from MPP⁺-induced apoptosis. MethodsThe apoptosis of SHSY5Y induced by 1-methyl-4-phenylpyridinium (MPP⁺) was observed by AO-EB staining. Flow cytometry was used to quantitate the reactive oxygen species (ROS). Western Blotting was used to detect the c-jun NH₂-terminal kinase (JNK) activity in SHSY5Y cells. Immunocytochemistry staining was used to detect cleaved Caspase-3 positive cells. ResultsMPP⁺ was shown to induce apoptosis in SHSY5Y cells. The percentage of apoptotic SHSY5Y cells induced by MPP⁺ was obviously lower in those groups pretreated with 10 μmol·L^-1 Rg1 or 2.5 mmol·L^-1 N-acetylcysyteine (NAC). It showed more ROS in MPP⁺ groups than in control. JNK activity increased with time within 72 hours in 1 mmol·L^-1 MPP⁺ group. Simultaneously, it showed decrease of ROS, less activity of JNK and lower expression of cleaved Caspase-3 in 10 μmol·L^-1 Rg1 and 2.5 mmol·L^-1 NAC pretreated groups compared with groups treated with MPP⁺ only. ConclusionRg1 protects against MPP⁺-induced apoptosis in SHSY5Y cells and the effect might be attributed to its removal of ROS, inhibition of the activity of JNK and expression of cleaved Caspase-3.