METABOLIC RESPONSE TO DIETARY STEARIC-ACID, LINOLEIC-ACID, AND HIGHLY UNSATURATED FATTY-ACID IN CARP

In order to investigate the effect of dietary fatty acids on hepatopancreatic enzyme activities and body composition, carp Cyprinus carpio were fed on a fat-free diet (FF) and three diets containing 2% of stearic acid (SA), linoleic acid (LA) or a mixture of n-3 highly unsaturated fatty acids (HUFA), mainly containing 20:5n-3 and 22:6n-3 for 30 days. The serum triglyceride and cholesterol levels were lower in the SA and HUFA groups than in the FF and LA groups. The activities of lipogenic enzymes such as glucose-6-phosphate dehydrogense and NADP-malate dehydrogenase and the hepatopancreatic fat content were reduced by dietary fatty acids and were the lowest in the HUFA group. The activities of phosphofructokinase and alanine aminotransferase were also lower in the HUFA group than in the other groups. These findings suggest that dietary n-3 HUFA effectively reduced lipogenesis, glycolysis, and amino acid degradation in the hepatopancreas, and that the reduced lipogenesis resulted in a reduction of serum lipid levels.