title: Green tea polyphenol extract regulates the expression of genes involved in glucose uptake and insulin signaling in rats fed a high fructose diet.
abstract: Green tea has antidiabetic, antiobesity, and anti-inflammatory activities in animal models, but the molecular mechanisms of these effects have not been fully understood. Quantitative real-time polymerase chain reaction (PCR) was used to investigate the relative expression levels and the effects of green tea (1 and 2 g solid extract/kg diet) on the expression of glucose transporter family genes (Glut1/Slc2a1, Glut2/Slc2a2, Glut3/Slc2a3, and Glut4/Slc2a4) and insulin signaling pathway genes (Ins1, Ins2, Insr, Irs1, Irs2, Akt1, Grb2, Igf1, Igf2, Igf1r, Igf2r, Gsk3b, Gys1, Pik3cb, Pik3r1, Shc1, and Sos1) in liver and muscle of rats fed a high-fructose diet known to induce insulin resistance and oxidative stress. Glut2 and Glut4 were the major Glut mRNAs in rat liver and muscle, respectively. Green tea extract (1 g) increased Glut1, Glut4, Gsk3b, and Irs2 mRNA levels by 110, 160, 30, and 60% in the liver, respectively, and increased Irs1 by 80% in the muscle. Green tea extract (2 g) increased Glut4, Gsk3b, and Pik3cb mRNA levels by 90, 30, and 30% but decreased Shc1 by 60% in the liver and increased Glut2, Glut4, Shc1, and Sos1 by 80, 40, 60, and 50% in the muscle. This study shows that green tea extract at 1 or 2 g/kg diet regulates gene expression in the glucose uptake and insulin signaling pathway in rats fed a fructose-rich diet.
authors.affiliation: Nutrient Requirements and Functions Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, USA. Heping.Cao@ars.usda.gov
authors.forename: Heping
authors.initials: H
authors.lastname: Cao
authors.forename: Isabelle
authors.initials: I
authors.lastname: Hininger-Favier
authors.forename: Meghan A
authors.initials: MA
authors.lastname: Kelly
authors.forename: Rachida
authors.initials: R
authors.lastname: Benaraba
authors.forename: Harry D
authors.initials: HD
authors.lastname: Dawson
authors.forename: Sara
authors.initials: S
authors.lastname: Coves
authors.forename: Anne M
authors.initials: AM
authors.lastname: Roussel
authors.forename: Richard A
authors.initials: RA
authors.lastname: Anderson
mesh_terms: D000818:Animals; D005419:Flavonoids / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism*; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics; D007328:Insulin / Q000378:metabolism*; D008297:Male; D010636:Phenols / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D059808:Polyphenols; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000235:genetics*; D013662:Tea / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D051246:Glucose Transport Proteins, Facilitative; D007328:Insulin; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D012333:RNA, Messenger; D013662:Tea; D005947:Glucose