Abstract: Abstract:Objective  To explore the effect of  astragalus combined with insulin on insulin resistance in diabetic rats and to clarify the action mechanism.Methods The diabetic rat models induced by STZ were randomly divided into  diabetic model(DM) group,astragalus(RA) group,insulin(Ins) group and astragalus combined with insulin(RA+Ins) group.At the same time the normal rats were used as control group.After treatment for 8  weeks,the levels of fasting blood glucose(FBG) and fasting insulin(FINS) of rats were measured,and the contents of MDA and TNF-α in serum were detected,and the levels of insulin receptor substrate-1(IRS-1) and p38MAPK in skeletal muscle were examined by Western blotting.Results Compared with control group,the levels of FBG of rats in DM，RA，Ins and RA+Ins groups were significantly increased (P<0.05)，and the FBG levels in RA,Ins  and RA+Ins groups  were significantly decreased compared with DM group(P<0.05);the FBG level in  RA+Ins group was significantly decreased compared with RA and Ins groups(P<0.05).Compared with DM,RA and control groups,the levels of FINS in Ins and RA+Ins groups  were increased(P<0.05),and the FINS level in  RA+Ins group was decreased compared with Ins group(P<0.05).Compared with control group,the levels of MDA and TNF-α in DM,RA,Ins and RA+Ins groups were significantly increased(P<0.05),and they were  lower in RA,Ins and RA+Ins groups compared with DM group(P<0.05);compared with RA and Ins groups,the MDA and TNF-α in RA+Ins were decreased(P<0.05).The activities of SOD  in DM, RA,Ins and RA+Ins groups were significantly decreased compared with control group(P<0.05),and they were higher in RA,Ins and RA+Ins groups compared with DM group(P<0.05);compared with Ins and RA groups,it was increased in RA+Ins group(P<0.05).The expression levels of IRS-1 in DM,RA and RA+Ins groups were decreased compared with control group(P<0.05),but it was higher in RA+Ins  than DM,RA and Ins groups(P<0.05).The expression levels of p38MAPK in  DM,RA,Ins and RA+Ins groups were increased compared with control group(P<0.05),but  it was lower in RA+Ins group than DM,RA and Ins groups(P<0.05).Conclusion Astragalus combined with insulin significantly improve   the oxidative stress and insulin resistance in  diabetic rats,and its efficacy is better than insulin alone.

Key words: astragalus, diabetes mellitus, insulin resistance, insulin receptor substrate-1, p38 MAPK