title: Epigallocatechin gallate stimulates glucose uptake through the phosphatidylinositol 3-kinase-mediated pathway in L6 rat skeletal muscle cells.
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.
authors.affiliation: Department of Clinical Pharmacology, College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Jung
authors.forename: Han Sung
authors.initials: HS
authors.lastname: Choi
authors.forename: Dong Hwan
authors.initials: DH
authors.lastname: Kim
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Han
authors.forename: Un Jae
authors.initials: UJ
authors.lastname: Chang
authors.forename: Sung-Vin
authors.initials: SV
authors.lastname: Yim
authors.forename: Byeng Chun
authors.initials: BC
authors.lastname: Song
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Kim
authors.forename: Soon Ah
authors.initials: SA
authors.lastname: Kang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D005947:Glucose / Q000493:pharmacokinetics*; D007004:Hypoglycemic Agents; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats
chemical_list: D000975:Antioxidants; D007004:Hypoglycemic Agents; D002392:Catechin; C045651:epigallocatechin gallate; D019869:Phosphatidylinositol 3-Kinases; D055372:AMP-Activated Protein Kinases; D005947:Glucose