Objective:To explore the regulative role of tumor necrosis factor-a(TNF-a)on tumor necrosis factor alpha-stimulated gene-6(TSG-6)gene expression in both undifferentiated and matured 3T3-Ll adipocytes.Methods:3T 3-Ll preadipocytes were cultured and differentiated into the matured adipocytes.Recombinant TNF-a at different co ncentrations( 0.1，1.0,10 .0n g/ml)was added to the Culture medium 2days post-confluent undifferentiated adipocytes(D ay0 )or fully differentiated adipocytes( Day1 0)for various times(0, 0.5, 2.0, 6.0, 12.0, 24.0 h). Total RNA from these adipocytes was extracted and the expression of TSG-6 mRNA was evaluated by RT-PCR.Results:}1 Treatment of un differentiated3 T3-Lla dipocytesw ithT NF-aa tdi ferentco ncentrations (0.1,1. 0,10 .0n g/ml) resulted in the significant decrease in the expression of TSG-6 mRNA. When 0.1 ng/ml TNF-a was applied,the levels of TSG-6 gene expression significantly decreased by 67.30% at 2 h, and 76.05% at 24 h. When 1.0 ng/ml TNF-a was used, the levels of TSG-6 gene expression significantly decreased by 52.79% at 0.5 h, and 99.20% at 24 h. When the cells were treated with 10.0 ng/ml TNFa,TS G-6g enee xpressionw asa lmostfu llyin hibited( 96.14% decreased)at 0 .5h .(2 )Treatment of matured3 T3-Ll adipocytes with TNF-a at different concentrations( 0.1，1.0,10 .0n g/ml)a lsor esultedi nt hes ignificantd ecreasei nt hee xpressiono fT SG-6m RNA.When the cells were treated with 0.1 ng/ml TNF-(x, the levels of TSG-6 gene expression decreased by 33.73% at 6 h, and 97.39% at 12h .W hent reatedw ith1 .0n g/mlT NF-a,th ele velso fT SG-6g enee xpressiond ecreasedb y7 8.68%a t6 h ,which sustained u ntil24 h .Whenter atedw ith1 0.0n g/mlTN F-a,th ele velso fT SG-6g enee xpressiond ecerasedb y9 6.27% at2 h a ndT SG-6gene expression was almost fully inhibited. Conclusion: TNF-a can downregulate the mRNA expression of TSG-6 in both undiferentiated and matured adipocytes. The inhibitive efe ct of TNF-a on TSG -6 gene expression is in dose and time-dependent manne r.