Diets rich in polyunsaturated fatty acids: Effect on hepatic metabolism in rats

• Published in: Nutrition (Burbank, Los Angeles County, Calif.) Vol. 19; no. 2; pp. 144 - 149
• Main Authors: Gaíva, Maria Helena, Couto, Rosany C, Oyama, Lila M, Couto, Gilmar E.C, Silveira, Vera L.F, Ribeiro, Eliane B, Nascimento, Cláudia M.O
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.02.2003; Elsevier; Elsevier Limited
• Subjects: Animals; ATP; ATP Citrate (pro-S)-Lyase - drug effects; ATP Citrate (pro-S)-Lyase - metabolism; Biological and medical sciences; Body weight; Body Weight - drug effects; Cholesterol; Cholesterol - blood; Cholesterol - metabolism; Diet; Diet enriched with ω-3 and ω-6 fatty acids; Dietary Fats, Unsaturated - metabolism; Enzymatic activity; Fatty acids; Fatty Acids, Unsaturated - metabolism; Fish oils; Fundamental and applied biological sciences. Psychology; hepatic metabolism; Lipid Metabolism; Lipids; Liver - metabolism; Liver Glycogen - metabolism; Liver. Bile. Biliary tracts; Malate Dehydrogenase - drug effects; Malate Dehydrogenase - metabolism; Male; nutrition; Organ Size - drug effects; Polyunsaturated fatty acids; Proteins; Proteins - drug effects; Proteins - metabolism; Rats; Rats, Wistar; Rodents; Soybean oil; Soybeans; Triglycerides - blood; Triglycerides - metabolism; Vertebrates: digestive system; nutrition; Diet enriched with ω-3 and ω-6 fatty acids; hepatic metabolism; Rat; Digestive system; Liver; Rodentia; Polyunsaturated fatty acid; Lipids; Vegetable oil; Supplemented diet; Edible oil; Metabolism; n-3 fatty acid; Fish oil; Feeding; Vertebrata; Mammalia; n-6 fatty acid; Animal oil; Animal; Unsaturated fatty acid; Soybean oil
• ISSN: 0899-9007; 1873-1244
• DOI: 10.1016/S0899-9007(02)00909-7

We investigated the effect of diets rich in ω-6 and ω-3 fatty acids on hepatic metabolism. Male Wistar rats, just weaned, were fed ad libitum for 8 wk with one of the following diets: rat chow (C), rat chow containing 15% (w/w) soybean oil (S), rat chow containing 15% (w/w) fish oil (F), and rat chow containing 15% soy bean and fish oil (SF; 5:1, w/w). Casein was added to the fatty diets to achieve the same content of protein (20%) as the control chow. The rats were killed by decapitation, and the hepatic tissue was removed and weighed. Tissue lipid, glycogen, and protein content, in vivo lipogenesis rate, and adenosine triphosphate citrate lyase and malic enzyme activities were evaluated. Plasma total lipids, triacylglycerol, and cholesterol concentrations were assessed. Body weight gain was higher in F and SF than in C and S rats. Liver weight, lipid content, and lipogenesis rate increased in F and SF rats, although adenosine triphosphate citrate lyase activity decreased. Glycogen concentration decreased in S, F, and SF rats compared with C rats. Plasma total lipids and triacylglycerol concentrations were lower in F and SF than in C rats. Total and high-density lipoprotein cholesterol (HDL-C) plasma levels decreased in F rats, with maintenance of the total:HDL-C ratio. In SF rats, an increase in HDL-C led to a lower total:HDL-C ratio. These results indicated that an enrichment of the diet with ω-3 polyunsaturated fatty acids produces hypolipidemia but may cause changes in liver metabolism that favor lipid deposition. They also suggested that the addition of a small amount of eicosapentaenoic and docosahexaenoic polyunsaturated fatty acids to an ω-6–rich diet further improve the circulating lipid profile, in comparison with an ω-3–rich diet, but it does not prevent excess liver lipid accumulation.