Gene Expression Analysis of the Anti-obesity Effect by Apple Polyphenols in Rats Fed a High Fat Diet or a Normal Diet

Abstract

We previously reported that ingestion of apple polyphenols reduced the weight of visceral adipose tissue and the triglyceride content of blood and liver in rats fed a high-fat diet (1). To further elucidate the mechanism of the improvement of lipid metabolism by dietary polyphenols, the effects of feeding apple- and tea-derived catechins on hepatic gene expression profile was investigated using the GeneChip DNA microarray system. Male Sprague-Dawley rats were fed a normal diet, a high-fat diet, a high-fat diet supplemented with 1.0% apple polyphenols or a high-fat diet supplemented with 1.0% tea catechins for 9 weeks. Both polyphenols reduced the weight of visceral adipose tissue and the triglyceride content in blood and liver. Tea catechins increased the transcription of genes involved in cholesterol synthesis whereas apple polyphenols decreased the transcription of genes involved in fatty acid synthesis. Thus, each polyphenol exerts a different effect on hepatic gene expression. The reduction of the weight of visceral adipose tissue was also observed when apple polyphenols were fed with a normal-fat diet. The genes involved in fatty acid synthesis were down-regulated in both high fat and normal diets. These results suggest that apple polyphenols and tea catechines improve lipid metabolism through different manner of action. Apple polyphenols widely inhibit the expressions of genes involved in fatty acid synthesis.