Effect of unsaturated fat intake from Mediterranean diet on rat liver mRNA expression profile: selective modulation of genes involved in lipid metabolism

Background and aim: The lipid content of Mediterranean diet is mostly accounted for its disease preventive action. We investigated whether the short term nutritional effect of a fat quota mainly derived from olive and fish oil affects liver mRNA expression profile in rats. Methods and results: The study was carried out using DNA microarray techniques. The effect was evaluated at liver mRNA expression level. to identify genes whose expression was regulated by dietary modifications. Two groups of six rats were alternatively supplied for two weeks with either a control or with an experimental diet. Both diets were semisynthetic and isocaloric, with identical major nutrients composition (protein 20%, carbohydrates 56% and lipids 22% of total energy) being different only in the quality of fats. The lipid quota of the control diet contained exclusively saturated animal fats, derived from butter, while in the experimental diet some unsaturated fats were present, being derived also from olive and fish oil (10% and 6% of total energy, respectively). Out of 26,334 genes analyzed, 11,292 were found expressed in the liver, 72 were induced and 180 were inhibited from the experimental diet. Out of these, 33 of the induced and 59 of the inhibited species have a well known function. Conclusions: The diet with olive and fish oil modulates several genes related to lipolysis or lipogenesis and newly identified responders from other metabolisms. Some of these genes are also reported to be similarly modulated by the action of fibrates, but without the complete gene activation typical of these PPAR alpha ligands. (c) 2005 Elsevier Ltd. All rights reserved.