Green tea improves carbohydrate and lipid metabolism and regulates cardiac mRNA expression related to insulin, lipid and inflammatory signaling pathways

Abstract

Green tea has multiple benefits to human health. Epidemiologic studies demonstrate that the consumption of green tea polyphenols (GTP) reduces the risk of coronary artery disease and cardiac events. To explore the underlying mechanisms of action at a molecular level, we examined the effects of GTP on the expression of the cardiac genes involved in insulin, lipid and inflammatory signaling pathways, using quantitative real‐time PCR. Rats, fed a high fructose diet for four weeks to induce insulin resistance, were divided into two groups: the control group and GTP group (200 mg/kg body weight daily dissolved in distilled water for 6 weeks). There were no significant differences in average food intake and bodyweight gain between groups. GTP reduced serum blood glucose, cholesterol, triglycerides, free fatty acids and LDL‐C levels, compared with the controls. Supplementation with GTP also increased insulin receptor, IRS1, IRS2, PI3K, Akt1, GLUT1 and GLUT4 mRNA levels in the myocardium; increased cardiac CD36, PTEN, PPARg mRNA levels; but decreased the inflammatory factors: TNFa and IL1ß mRNA levels. In summary, our data demonstrate that green tea polyphenols improve glucose and lipid metabolism and regulate the cardiac gene expression related to insulin, lipid and inflammatory pathways in fructose‐fed insulin resistant rats. (Funded by USDA/ARS and Integrity Nutraceuticals).