To investigate the effects of sulindac on tyrosine/serine phosphorylations of insulin postreceptor signal transducin IRS-1 in 3T3-L1 adipocytes by regulating the activity of IKK pathway in vitro.

3T3-L1 pre-adipocytes were incubated with isobuthyl-methylxanthine, dexamethasone, insulin and differentiated into mature adipocytes as determined by Oil Red O staining. The differentiated maturate adipocytes were divided into the following groups with or without various concentrations of IL-1β (0, 1, 10, 100 ng/m1) . Then the adipocytes of different groups were treated with different concentrations of sulindac (0, 0.1, 1, 10?mmol/l) at the different time points and subjected to real-time RT-PCR and Western Blot analysis for IKK as well as the IRS-1 Tyr/Ser phosphorylation expression. Statistical analysis was performed using one-way ANOVA procedure.

Compared with control group, the relative expression of mRNA expression of IKKβ was significantly increased in IL-1β 10?ng/ml treatment 3T3L1 adipocytes[ (2.85±0.16) ﹪vs (1.00±0.12) ﹪, P < 0.01] while IRS-1 tyrosine phosphorylation obviously decreased, the difference was statistically significant [ (0.72±0.26) ﹪ vs (1.00±0.24) ﹪, P < 0.01]. Further Western Blot results showed that the sulindac treatment significantly up-regulated the relative expression of IRS-1impaired tyrosine phosphorylation induced by IL-1β induction [ (1.72±0.16) ﹪, (1.90±0.08) ﹪vs (1.00±0.13) ﹪, P < 0.01] but decreased IRS-1 serine phosphorylation[ (0.79±0.16) ﹪, (0.66±0.08) ﹪vs (1.00±0.10) ﹪, P < 0.05].

These data suggest that IL-1β can promote the expression of IKKβ in adipocytes, activate the inflammatory pathway of IKK in adipocytes and inhibit the phosphorylation of IRS-1 tyrosine residues which may be one of the causes of insuliresistance, while sulindac can improve the insulin postreceptor signal transduction pathway in adipocytes by regulating the tyrosine/serine residues phosphorylation of IRS-1 in adipocytes.