Effects of Green Tea on Gene Expression of Hepatic Gluconeogenic Enzymes in vivo

Abstract

It has recently been reported that the major green tea polyphenolic constituent, epigallocatechin 3-gallate (EGCG), mimics the cellular effects of insulin including the reductive effect on the gene expression of rate-limiting gluconeogenic enzymes in a cell culture system. We show that administration of green tea that contains EGCG caused a reduction in the level of mRNAs for gluconeogenic enzymes, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase in the mouse liver. EGCG alone was also found to down-regulate the gene expression of these enzymes but not so curcumin or quercetin. The results of this study support the idea that green tea intake may be beneficial in the prevention of diabetes mellitus.

References

• 1 Hofmann C A, Edwards C W, Hillman R M, Colca J R. Treatment of insulin-resistant mice with the oral antidiabetic agent pioglitazone: evaluation of liver GLUT2 and phosphoenolpyruvate carboxykinase expression.  Endocrinology. 1992;  130 735-40
• 2 Noguchi T, Matsuda T, Tomari Y, Yamada K, Imai E, Wang Z. et al . The regulation of gene expression by insulin is differentially impaired in the liver of the genetically obese-hyperglycemic Wistar fatty rats.  FEBS Lett. 1993;  328 145-8
• 3 Valera A, Pujol A, Pelegrin M, Bosch F. Transgenic mice over-expressing phosphoenolpyruvate carboxykinase develop non-insulin-dependent diabetes mellitus.  Proc Natl Acad Sci USA. 1994;  91 9151-4
• 4 Waltner-Law M E, Wang X L, Law B K, Hall R K, Nawano M, Granner D K. Epigallocatechin gallate, a constituent of green tea, represses hepatic glucose production.  J Biol Chem. 2002;  277 34 933-40
• 5 Sayama K, Ozeki K, Taguchi M, Oguni I. Effects of green tea and tea catechins on the development of mammary gland.  Biosci Biotechnol Biochem. 1996;  60 169-70
• 6 Arun N, Nalini N. N. Efficacy of turmeric on blood sugar and polyol pathway in diabetic albino rats.  Plant Foods Hum Nutr. 2002;  57 41-52
• 7 Vessal M, Hemmati M, Vasei M. Antidiabetic effects of quercetin in streptozotocin-induced diabetic rats.  Comp Biochem Physiol C Toxicol Pharmacol. 2003;  135C 357-64
• 8 Miyoshi N, Koyama Y, Katsuno S, Hayakawa S, Mita T, Ohta T. et al . Apoptosis induction associated with cell cycle dysregulation by rice bran agglutinin.  J Biochem (Tokyo). 2001;  130 799-805