title: High-dose Resveratrol Inhibits Insulin Signaling Pathway in 3T3-L1 Adipocytes.
abstract: BACKGROUND
  Insulin resistance is a major factor in the development of metabolic syndrome and is associated with central obesity and glucose intolerance. Resveratrol, a polyphenol found in fruits, has been shown to improve metabolic conditions. Although it has been widely studied how resveratrol affects metabolism, little is known about how resveratrol regulates lipogenesis with insulin signaling in 3T3-L1 adipocytes.
  
  
  METHODS
  We treated differentiated 3T3-L1 adipocytes with resveratrol to observe whether resveratrol is effective at reducing lipid accumulation.
  
  
  RESULTS
  Resveratrol treatment after mitotic clonal expansion resulted in decreased lipid accumulation accompanied by reduced fatty acid synthase expression. Decreased glucose uptake was observed with inhibited GLUT4 translocation in cells treated with 100 μM resveratrol, suggesting that high doses of resveratrol block insulin signaling in adipocytes. Insulin-stimulated Akt phosphorylation is also dose-dependently reduced with resveratrol treatment. Interestingly, Akt phosphorylation is upregulated when cells are treated with long-term low doses of resveratrol, suggesting that only low doses of resveratrol improve metabolic conditions.
  
  
  CONCLUSIONS
  High doses of resveratrol block the insulin signaling pathway, thereby reducing glucose uptake and lipid accumulation in vitro. The results also provide information about in vivo administration dosages and may explain the discrepancy between in vitro and in vivo effects of resveratrol.
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Genetic Science ; Brain Korea 21 Project for Medical Science.
authors.forename: Haemi
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Genetic Science ; Integrated Genome Research Center for Metabolic Regulation, Yonsei University College of Medicine ; Brain Korea 21 Project for Medical Science ; Department of Biomedical Science, WCU Program of Graduate School, Yonsei University, Seoul, Korea.
authors.forename: Jae-Woo
authors.initials: JW
authors.lastname: Kim
keywords: Adipocyte; Glucose uptake; Insulin signaling pathway; Lipid accumulation; Resveratrol