title: Green tea extract with polyethylene glycol-3350 reduces body weight and improves glucose tolerance in db/db and high-fat diet mice.
abstract: Green tea extract (GTE) is regarded to be effective against obesity and type 2 diabetes, but definitive evidences have not been proven. Based on the assumption that the gallated catechins (GCs) in GTE attenuate intestinal glucose and lipid absorption, while enhancing insulin resistance when GCs are present in the circulation through inhibiting cellular glucose uptake in various tissues, this study attempted to block the intestinal absorption of GCs and prolong their residence time in the lumen. We then observed whether GTE containing the nonabsorbable GCs could ameliorate body weight (BW) gain and glucose intolerance in db/db and high-fat diet mice. Inhibition of the intestinal absorption of GCs was accomplished by co-administering the nontoxic polymer polyethylene glycol-3350 (PEG). C57BLKS/J db/db and high-fat diet C57BL/6 mice were treated for 4 weeks with drugs as follows: GTE, PEG, GTE+PEG, voglibose, or pioglitazone. GTE mixed with meals did not have any ameliorating effects on BW gain and glucose intolerance. However, the administration of GTE plus PEG significantly reduced BW gain, insulin resistance, and glucose intolerance, without affecting food intake and appetite. The effect was comparable to the effects of an α-glucosidase inhibitor and a peroxisome proliferator-activated receptor-γ/α agonist. These results indicate that prolonging the action of GCs of GTE in the intestinal lumen and blocking their entry into the circulation may allow GTE to be used as a prevention and treatment for both obesity and obesity-induced type 2 diabetes.
authors.affiliation: Department of Physiology and Endocrinology, Keimyung University School of Medicine, 1095 Dalgubeoldae-Ro, Dalseo-Gu, Daegu, 704-701, South Korea.
authors.forename: Jae-Hyung
authors.initials: JH
authors.lastname: Park
authors.forename: Yoon Jung
authors.initials: YJ
authors.lastname: Choi
authors.forename: Yong Woon
authors.initials: YW
authors.lastname: Kim
authors.forename: Sang Pyo
authors.initials: SP
authors.lastname: Kim
authors.forename: Ho-Chan
authors.initials: HC
authors.lastname: Cho
authors.forename: Shinbyoung
authors.initials: S
authors.lastname: Ahn
authors.forename: Ki-Cheor
authors.initials: KC
authors.lastname: Bae
authors.forename: Seung-Soon
authors.initials: SS
authors.lastname: Im
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Bae
authors.forename: Dae-Kyu
authors.initials: DK
authors.lastname: Song
mesh_terms: D052242:Adiponectin / Q000097:blood; D000273:Adipose Tissue / Q000187:drug effects / Q000473:pathology; D000818:Animals; D019440:Anti-Obesity Agents / Q000008:administration & dosage*; D018938:Caco-2 Cells; D028241:Camellia sinensis; D002392:Catechin / Q000031:analogs & derivatives / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000473:pathology; D059305:Diet, High-Fat; D005947:Glucose / Q000378:metabolism; D018149:Glucose Intolerance / Q000097:blood / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000097:blood / Q000188:drug therapy* / Q000473:pathology; D009929:Organ Size / Q000187:drug effects; D010936:Plant Extracts / Q000008:administration & dosage*; D011092:Polyethylene Glycols / Q000008:administration & dosage*; D054839:Retinol-Binding Proteins, Plasma / Q000378:metabolism
chemical_list: D052242:Adiponectin; C499919:Adipoq protein, mouse; D019440:Anti-Obesity Agents; D010936:Plant Extracts; C502487:Rbp4 protein, mouse; D054839:Retinol-Binding Proteins, Plasma; D011092:Polyethylene Glycols; D002392:Catechin; C045651:epigallocatechin gallate; D005947:Glucose