Epigallocatechin gallate promotes GLUT4 translocation in skeletal muscle

• Published in: Biochemical and biophysical research communications 2008-12, Vol.377 (1), p.286-290
• Main Authors: Ueda, Manabu, Nishiumi, Shin, Nagayasu, Hironobu, Fukuda, Itsuko, Yoshida, Ken-ichi, Ashida, Hitoshi
• Format: Article
• Language: English
• Subjects: Androstadienes - pharmacology; Animals; Camellia sinensis - chemistry; Catechin - analogs & derivatives; Catechin - pharmacology; Epigallocatechin gallate; Genistein - pharmacology; Glucose - metabolism; Glucose transporter; Glucose Transporter Type 4 - metabolism; Insulin - pharmacology; Insulin Resistance; Mice; Mice, Inbred C57BL; Muscle; Muscle Fibers, Skeletal - drug effects; Muscle Fibers, Skeletal - metabolism; Muscle, Skeletal - drug effects; Muscle, Skeletal - metabolism; Protein Transport - drug effects; Rats; Rats, Sprague-Dawley; Tea
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2008.09.128

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 EGCg-increased uptake. Therefore, EGCg may improve hyperglycemia by promoting GLUT4 translocation in skeletal muscle with partially different mechanism from insulin.