Inhibitory Effect Of Astragalus Polysaccharide On Apoptosis Of MC3T3-E1 Cells Induced By Hydrogen Peroxide By Nrf-2 Pathway

Purpose:Osteoporosis refers to the unit volume of bone loss associated with bone strength reduction. Osteoporosis rows the 7th in common diseases, is a major clinical and public health problem. Osteoporosis can lead to fractures and other complications which may cause the huge cost of treatment and a heavy burden to patients, families and society. Oxidative stress is closely related to the occurrence of osteoporosis. Apoptosis is the final stage of cell physiology and pathology. Osteoblast apoptosis caused by oxidative stress plays an important role in osteoporosis. TCM believes that astragalus is sweet in taste, a little tepid and attributive to the spleen and lung meridians. Astragalus has the roles of invigorating Qi for consolidating superficies, promoting pus discharge and tissue regeneration and Diuresis detumescence. Astragalus polysaccharides(APS) are the main active ingredient of astragalus. APS can promote the proliferation and differentiation of osteoblast cells. Synthetic antioxidants have been shown to have cumulative carcinogenic effects. Natural antioxidants are inevitable alternatives. APS have good thermal stability and non-toxic side effects, so it can become an ideal natural antioxidants. This reseach studies the antioxidant effect of APS, and explore the effect of APS on apoptosis induced by hydrogen peroxide in MC3T3-E1 osteoblast cells.Material and method:Cultured and passaged mouse MC3T3-E1 cells. When cells is in the logarithmic growth phase, the cells were treated with H2O2 and APS. The experiment was divided into four groups: normal control group(0 m M H2O2 + 0 mg/ml APS); H2O2 group(0.6 m M H2O2 + 0 mg/ml APS); APS group(0.6 m M H2O2 + 0.2 mg/ml APS); NAC group(0.6 m M H2O2 + 25 m M NAC). After cultured for 24 hours, we detected of cell apoptosis by Annexin V-FITC/PI. The levels of Nrf-2, HO-1, Bax and cleaved Caspase-3 were measured by Western blot. Statistical analysis was performed using SPSS(Version 17.1). Data were expressed as x± s and threeindependent experiments with six replicates were analyzed. Variance was homogenous for use of standard ANOVA methodology. Student–Newman–Keulstest was used to determine statistical signi fi cance with P value < 0.05 considered signi fi cant.。Results: 1. Compared with the normal group, the ROS levels and apoptosis rate of osteoblast were increased significantly in hydrogen peroxide group. 2. Compared with hydrogen peroxide group, the ROS levels were significantly decreased in APS group and the expression levels antioxidant protein Nrf-2, and antioxidant factors downstream(HO-1) were increased significantly. Compared with the NAC, APS had a stronger antioxidant effect. 3. Compared with hydrogen peroxide group, apoptosis rate and apoptosis-related proteins(Bax, Caspase-3) expression levels of osteoblasts were significantly reduced in APS group.Conclusion:1. APS can significantly reduce oxidative stress in osteoblastic cells. 2. APS can activate anti-oxidation pathway in osteoblasts. 3. APS can inhibit apoptosis induced by hydrogen peroxide in osteoblasts through antioxidant effects.