Objective To investigate the effect of insulin (INS) on nuclear factor-kappa B (NF-KB) activation in glomerular mesangial cells(GMC) of the Zucker rats,and the correlation between the activity of NF-kB induced by insulin to the ages and genotype of Zucker rats. Methods (1) Four groups of cultured GMCs(O3m,O10m,L3m and L10m) from the Zucker obese rats(3 months old and 10 months old) and Zucker lean rats(3 months old and 10 months old) were stimulated by insulin. (2) Electrophoretic mobility shift assay (EMSA) was used to detect the activity of NF-KB. Gel supershift assay was used to detect the subunit of NF-KB dimer. (3) The protein of NF-KB p65 in cytoplasm and cytoblast was analysed by Western Blot. Results (1) NF-KB activity in 4 groups GMCs was significantly higher than that in control group after induced of INS ( F=219. 65 P