Green Tea Polyphenol Extract Regulates the Expression of Genes Involved in Glucose Uptake and Insulin Signaling in Rats Fed a High Fructose Diet

Heping Cao,*† Isabelle Hininger-Favier,‡ Meghan A. Kelly,† Rachida Benaraba,‡ Harry D. Dawson,† Sara Coves,§ Anne M. Roussel,‡ and Richard A. Anderson*†
Nutrient Requirements and Functions Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, U.S. Department of Agriculture, Building 307C, BARC-East, 10300 Baltimore Avenue, Beltsville, Maryland 20705, Laboratoire de NVMC (Nutrition, Vieillissement et Maladies Cardiovasculaires), Faculte de Pharmacie, Joseph Fourier University, Domaine de la Merci, 38700 La Tronche, France, and Unilever France, F92842 Rueil Malmaison, France
J. Agric. Food Chem., 2007, 55 (15), pp 6372–6378
DOI: 10.1021/jf070695o
Publication Date (Web): July 6, 2007
Copyright © 2007 American Chemical Society
*

 To whom correspondence should be addressed. Tel:  301-504-5253 ext. 270. Fax:  301-504-9062. E-mail:  (H.C.) Heping.Cao@ars.usda.gov. or peacetd2003@yahoo.com. (R.A.A.) Richard.Anderson@ars.usda.gov.

,
†

 U.S. Department of Agriculture.

,
‡

 Joseph Fourier University.

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§

 Unilever France.

Abstract

Abstract Image

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.

Keywords: Diabetes; fructose-rich diet; green tea; glucose transporter; insulin signaling pathway; obesity; polyphenol extract, rat

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  • Published In Issue July 25, 2007
  • Received for review March 9, 2007. Revised manuscript received May 4, 2007. Accepted May 17, 2007. This work is part of the Scientific Cooperative Convention Agreement (58-1235-4N-F033) between the Human Nutrition Research Center (Beltsville, MD) and the Joseph Fourier University (Grenoble, France).

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