Protective Effect of baicalin on the TNF TNF-α-Mediated Development of Insulin Resistance in Differentiated 3T3-L1 Cells

Adipose tissue-derived chronic inflammation contributes to development of insulin resistance in obesity, leading to type 2 diabetes and cardiovascular disease. Baicalin, a flavonoid, has antioxidant, antiinflammatory, antihyperglycemic, anti-adipogenic, and antiobesity effects. However, whether baicalin attenuates adipose tissue-derived development of insulin resistance remains still unclear. This study was to investigate effect of baicalin on the inflammatory changes involved in the development of insulin resistance in adipose tissue. RAW 264.7 cells and differentiated 3T3-L1 adipocytes were pretreated with various concentrations of baicalin in complete media for 1 h and then cultured in the presence or absence of LPS or TNF-α. Our results demonstrated that baicalin remarkably inhibited LPS-induced production of TNF-α, IL-6, and NO by RAW 264.7 cells in a dose-dependent manner. Baicalin also inhibited TNF-α-induced production of IL-6 and PGE2 in differentiated 3T3-L1 cells in a dose-dependent manner, while upregulated TNF-α-suppressed expression of adiponectin and PPAR-γ mRNA and IRS-1 protein. These findings suggest that baicalin may prevent the adipose tissue-derived development of insulin resistance in obesity.