Abstract: Objective In order to investigate anti-ageing mechanisms of the notoginsenoside Rg1，we used AβSUB>1-42/SUB> and D-galactose to establish aging rat model. Methods Ninety rats were divided into three groups at random: sham group, model group, treatment group. Aging rat models were established by injecting peritoneally Dgalactose (100 mg/kg) to the rats for 56 days and after 35 days aggregated AβSUB>1-42/SUB>(μg) was injected to the right lateral ventricle of rats. Meantime, rats were treated by intragastric administration the notoginsenoside Rg1 Then spatial memory of experimental rats was examined with the Morris water maze(MWM). The thiol antioxidants including glutathione reductase (GR) and glutathione peroxidase (GSH-Px) activities were examined by colorimetric method. The concentration of the proCaspase-3 and Bcl-2 were examined by the immunohistochemistry and Western blotting method. Results In aging model rats escape latercies were significantly prolonged (P<0.05), while decreases were seen in the time of staying the third quadrants of platform, the number of crossing over a platform, the concentration of the GR, GSH-Px, and proCaspase-3 as compared with the sham group(P<0.05). After treatment of the notoginsenoside Rg1, the aging model rats exhibited significant increases in the time of staying the third quadrants of platform, the number of crossing over a platform, the concentration of the GR, GSH-Px, and proCaspase-3(P<0.05), while a decrease was observed in escape latercies as compared to control group(P<0.05). Moreover there was no significant difference in the expression of the Bcl-2(P>005). Conclusion The results from our study indicate that the notoginsenoside Rg1 could improve the oriented

Key words: Notoginsenoside Rg1, AβSUB>1-42/SUB>, D-galactose, Thiol antioxidant, Pro-Caspase-3, Immunohistochemistry, Western blotting, Rat