Epigallocatechin gallate promotes GLUT4 translocation in skeletal muscle

In this study, We investigated whether epigallocatechin gallate (EGCg) affects glucose uptake activity and the translocation Of insulin-sensitive glucose transporter (GLUT) 4 in skeletal muscle. A single oral administration of EGCg at 75 mg/kg body weight promoted GLUT4 translocation in skeletal muscle of rats. EGCg significantly increased glucose uptake accompanying GLUT4 translocation in L6 myotubes at 1 nM. The translocation of GLUT4 was also observed both in skeletal muscle of mice and rats ex vivo and in insulin-resistant L6 myotubes. Wortmannin, an inhibitor of phosphatidylinositol 3'-kinase, inhibited both EGCg- and insulin-increased glucose uptakes, while genistein, an inhibitor of tyrosine kinase, failed to inhibit the EGC-increasecl uptake. Therefore, ECCg may improve hyperglycemia by promoting GLUT4 translocation in skeletal muscle with partially different mechanism from insulin. (C) 2008 Elsevier Inc. All rights reserved.