Epigallocatechin gallate stimulates glucose uptake through the phosphatidylinositol 3-kinase-mediated pathway in L6 rat skeletal muscle cells

J Med Food. 2008 Sep;11(3):429-34. doi: 10.1089/jmf.2007.0107.

Abstract

The effect of epigallocatechin gallate (EGCG) on glucose uptake was studied in L6 rat skeletal muscle cells. Glucose uptake assay revealed that EGCG increased glucose uptake >70% compared to control. EGCG-stimulated glucose uptake was blocked by LY294002, an inhibitor of phosphatidylinositol (PI) 3-kinase, which is a major regulatory molecule in glucose uptake pathways. However, AMP-activated protein kinase (AMPK), which is another crucial mediator in independent glucose uptake pathways, did not inhibit EGCG-stimulated glucose uptake by SB203585, a specific inhibitor of the AMPK downstream mediator, p38 mitogen-activated protein kinase (MAPK). We also found that EGCG increased the phosphorylation level of protein kinase B and PI 3-kinase activity, when assessed by PI 3-kinase assay, whereas no increase in the phosphorylation level of AMPK and p38 MAPK was observed. Taken together, these results suggest that EGCG might stimulate glucose uptake, not AMPK-mediated but PI 3-kinase-mediated, in skeletal muscle cells, thereby contributing to glucose homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism*
  • Animals
  • Antioxidants / pharmacology*
  • Catechin / analogs & derivatives*
  • Catechin / pharmacology
  • Cells, Cultured
  • Glucose / pharmacokinetics*
  • Hypoglycemic Agents
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation / drug effects
  • Rats

Substances

  • Antioxidants
  • Hypoglycemic Agents
  • Catechin
  • epigallocatechin gallate
  • Phosphatidylinositol 3-Kinases
  • AMP-Activated Protein Kinases
  • Glucose