Purpose: Beneficial effects of green tea (GT) polyphenols against obesity have been reported. However, until this moment the molecular mechanisms of how green tea can modulate obesity and regulates fat metabolism, particularly in adipose tissue, remain poorly understood. The aim of this study was to evaluate the role of GT extract in the adipose tissue of obese animals and its effect on weight gain, metabolism and function (de novo lipogenesis and lipolysis), and the involvement of AMP-activated protein kinase (AMPK).
Methods and results: Male Wistar rats were treated with GT by gavage (12 weeks/5 days/week; 500 mg/kg of body weight), and obesity was induced by cafeteria diet (8 weeks). Here, we show that obese rats treated with GT showed a significant reduction in indicators of obesity such as hyperlipidemia, fat synthesis, body weight, and fat depots as compared to those treated with standard control diet. AMPK was induced in adipose tissue in rats that were treated with GT and likely restored insulin sensitivity, increased mRNA expression of GLUT4, reducing the concentrations of plasma and liver lipid content, also stimulating fatty acid oxidation in the same tissue. Importantly, repression of de novo lipogenesis in the adipose tissue, reduced lipid droplets in the liver, and the development of insulin resistance in diet-induced obese rats were accompanied by AMPK activation.
Conclusion: Our study identified that metabolic changes caused by GT intake induced AMPK activation and modulate the expression of genes involved in metabolism, particularly in adipose tissue, thus offering a therapeutic strategy to combat insulin resistance, dyslipidemia, and obesity in rats.
Keywords: Flavonoids; Gene expression; Metabolism; Obesity; Polyphenols.