Resveratrol modulates adipokine expression and improves insulin sensitivity in adipocytes: Relative to inhibition of inflammatory responses

Abstract

Resveratrol is a potent inhibitor of inflammation and has anti-diabetic potentiality, however whether its anti-inflammatory potency contributes to the amelioration of diabetes or insulin resistance remains to be determined. This study aims at evaluating the effects of resveratrol on inflammation-related adipokines expression and insulin sensitivity in adipocytes. We stimulated RAW264.7 cells with LPS and collected the supernatant as a conditioned medium (CM) for the culture of adipocytes. Resveratrol, at concentrations ranging from 0.1 to 10 muM, effectively inhibited lipopolysaccharide (LPS)-induced TNF-alpha and IL-6 production with the downregulation of relative genes expression in macrophages. Exposing differentiated 3T3-L1 cells to RAW264.7 CM resulted in gene over-expressions of TNF-alpha, IL-6 and resistin, however, mRNA expression of adiponectin and PPARgamma were down-regulated. Pretreatment of CM from resveratrol-treated macrophages reduced the elevated levels of TNF-alpha and IL-6, and significantly reversed inflammation-related changes in adipokine gene expression in 3T3-L1 adipocytes. Resveratrol suppressed extracellular receptor-activated kinase (ERK) and transcription factor-kappaB (NF-kappaB) activation by reducing the phosphorylation of ERK1/2 and NF-kappaB p65; moreover, it modulated insulin signaling transduction by modification of Ser/Thr phosphorylation of insulin receptor substrate-1 (IRS-1) and downstream AKT (T308), and thereby improved insulin sensitivity in adiposities. These results demonstrated that resveratrol modulated adipokines expression and improved insulin sensitivity which relative to inhibition of inflammatory-like response in adipocytes.