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 EGCg-increased uptake. Therefore, EGCg may improve hyperglycemia by promoting GLUT4 translocation in skeletal muscle with partially different mechanism from insulin.
Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan.
Manabu
M
Ueda
Shin
S
Nishiumi
Hironobu
H
Nagayasu
Itsuko
I
Fukuda
Ken-ichi
K
Yoshida
Hitoshi
H
Ashida
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077191:Wortmannin
D000730:Androstadienes; D051275:Glucose Transporter Type 4; D007328:Insulin; D002392:Catechin; C045651:epigallocatechin gallate; D019833:Genistein; D005947:Glucose; D000077191:Wortmannin