Protective Effect Of Ginsenoside Rg1 On MPP～+-induced Apoptosis And Its Possible Mechanism

Objective: To explore the involvement of apoptosis in MPP+ (1-methyl-4-phenylpyridinium)-induced death of SHSY5Y cells, to investigate the neuroprotective effect of the ginsenoside Rgl on the apoptosis, and to find out the possible molecular mechanism.Method: The SHSY5Y cells treated with MPP+were used as a cell model of Parkinson' disease. The apoptosis of SHSY5Y induced by MPP+ was observed by AO-EB staining, TUNEL staining, cell ultrastructure and flow cytometry. The apoptosis of SHSY5Y induced by MPP+ was also observed in NAC and Rgl pretreated groups and oligoneucleutide transfected groups. The antisense oligoneucleutides of INK were used as the inhibitor of JNK . Western Blot was used to detect the activity of JNK. Flow cytometry was used to investigate mitochondrial transmembrane potential( A ?m)and reactive oxygen species(ROS) , to measure the positive rates of Bcl-2 and Bax proteins in SHSY5Y cells. Immunocytochemistry staining was used to detect cleaved caspase-3 positive cells. All the above indexs were detected in Rgl pretreated groups to study the possible mechanism of neuroprotective effect of Rgl on MPP+-induced apoptosis of SHSY5Y cells.Result: MPP+ induced apoptosis in SHSY5Y cells is on the dosage and time concern. During the apoptosis, it showed a decrease of mitochondria transmembrane potential increase of ROS , increase of JNK activity and increase of cleaved caspase-3 positive cells. Meanwhile,the expression of Bcl-2 protein was decreased and Bax protein was increased in MPP+ groups. MPP+-induced apoptosis in SHSY5Y cells was obviously inhibited in NAC pretreated groups and in antisense oligoneucleutide transfected groups. MPPMnduced apoptosis in SHSY5Y cells was also inhibited by pretreatment with 10 umol/L Rgl. Although there is no difference of mitochondrial transmembrane potential between Rgl pretreated groups and MPP+ groups. It showed decrease of ROS less of INK activity and lower expression of cleaved caspase 3 in Rgl pretreated groups. Simultaneously, the expression of bcl-2 protein was increased and bax protein was decreased.Conclusion: MPP+ induced apoptosis in SHSY5Y cells. The signal transduction pathway of MPP"1" inducing apoptosis may be ROS-JNK-Caspase 3. Ginsenoside Rgl has significantly protection in against MPP+-induced apoptosis in SHSY5Y cells.The effect might be up-regulation of expression of bcl-2 ^ down-regulation of bax proteins , removing of ROS. Its remove of ROS might inhibit the activity of JNK and expression of cleaved caspase 3.