Protective Effect Of Ginsenoside Rg1 On PD Mouse Substantia Nigra Neuron Apoptosis And Its Possible Mechanism

Objective:To make sure whether oxidative stress is involved in 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) -induced apoptosis of substantia nigra neurons in Parkinson's disease(PD) mouse model. And to investigate whether Ginsenoside Rgl has protective effect on this kind of cell death and its possible mechanisms. Methods:6 to 8 weeks old C57B1 male mice were administrated s.c. with MPTP(30mg/kg) once every day for 5 consecutive days to produce PD mouse model, biochemical technique was used to detect the concentration of glutathione(GSH) and the vitality of superoxide dismutase(SOD) in substantia nigra.Niss1 staining and tyrosine hydroxythase(TH) immunohistochemistry were used to observe whether the Pars compacta of substantia nigra(SNpc) were damaged.TUNEL staining was used to observe whether apoptosis occured. Meanwhile, activated Caspase-3-positive neurons, phosphorylated INK (p-JNK) and phosphorylated c-Jun (p-c-Jun) in substantia nigra were detected to observe whether JNK signaling pathway was activated. N-acetylcystein (NAC)( 300mg/kg, s.c.) and different doses of Rg1(5.0mg/kg, 10mg/kg , 20mg/kg and 40mg/kg ) were given respectively for 5 consecutive days prior to MPTP to observe their effects on the above markers using the same techniques. Results:1. In MPTP-produced PD mouse model,Nissl staining and TH immunostaining showed the significant loss of survived neurons and TH-positive neurons in SNpc(p<0.01). TUNEL staining showed an significant increase of apoptotic neurons with typical DNA fragmentation(p<0.01).2.In the PD mouse substantia nigra, MPTP decreased the concentration of GSH and ascended the vitality of SOD, elevated the levels of p-JNK and p-c-Jun, Meanwhile, activated caspase-3-positive neurons increased(p<0.01).3.Pretreatment with Rgl and NAC prevented the loss of TH-positive neurons and nissl staining neurons(p<0.01),and decreased TUNEL staining neurons(p<0.01), also increased the concentration of GSH and descended the vitality of SOD, decreased the levels of p-JNK and p-c-Jun, Meanwhile, activated caspase-3-positive neurons increased(p<0.01).The effects of 10mg/kg Rgl were especially significant(P<0.01) in Rgl pretreatment groups. Conclusion:1. In the MPTP-induced PD mouse substantia nigra, significative apoptosis occured, and concentration of GSH decreased with the vitality of SOD ascended, the levels of p-JNK and p-c-Jun elevated, Meanwhile, activated caspase-3-positive neurons increased. Pretreatment with NAC could reverse above index, effectively protect substantia nigra neurons.This indicated oxidative stress and JNK signaling pathway involved in the process of substantia nigra neurons apoptosis.2.Rgl has protective effect on MPTP-induced apoptosis in PD mouse model and this effect may be due to increase the concentration of GSH and descend the vitality of SOD, and decrease the levels of p-JNK, finally decrease the levels of p-c-Jun and inhibit caspase-3' activation. Rgl may have potential benefit on the therapy of neurodegenerative disease.