Objective      To determine the effect of high density lipoprotein (HDL) on the mRNA expression of tumor necrosis factor-α (TNF-α) in oxidized low density lipoprotein (oxLDL)-stimulated 3T3-L1 adipocytes.       Methods      Fully differentiated 3T3-L1 adipocytes were incubated in the medium containing various concentrations of HDL (10 to 100 μg/ml) with oxLDL (50 μg/ml) stimulation

with/without H-89 (10 μmol/L) preincubation. TNF-α mRNA expression was determined by RT-PCR

NF-κB activity was measured by ELISA

and IκB protein level was tested by Western blotting.       Results      OxLDL stimulation induced a significant increase of TNF-α mRNA and NF-κB activity in 3T3-L1 adipocytes. HDL inhibited TNF-α mRNA expression

NF-κB activation and IκB degradation in a dose-dependent manner. Compared with oxLDL stimulation

HDL at 100 μg/ml resulted in a decrease of TNF-α mRNA expression by 64.5% and NF-κB activation by 49%

and an increase of IκB protein. The anti-inflammatory effect of HDL was abolished by PKA inhibitor H-89 partially.       Conclusion      HDL could suppress TNF-α mRNA expression in oxLDL-stimulated 3T3-L1 adipocytes through PKA- IκBα-NF-κB signaling pathway

without any direct contact between HDL and oxLDL.