Volume 90, Issue 5, November (2003), pp. 887-893 © The Author 2003
doi:10.1079/BJN2003977

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Hepatic fatty acid metabolism in rats fed diets with different contents of C18 : 0, C18 : 1 cis and C18 : 1 trans isomers

Anna M. Giudetti¹, Anton C. Beynen², Arnoldina G. Lemmens³, Gabriele V. Gnoni¹, Math J. H. Geelen^2,4
1Laboratory of Biochemistry, Department of Biological and Environmental Sciences and Technologies, University of Lecce, , Lecce, Italy
²Department of Nutrition, PO Box 80.152, 3508 TD, Utrecht, The Netherlands
³Department of Laboratory Animal Science, and
⁴Laboratory of Veterinary Biochemistry, Graduate School of Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands

 (Received 23 August 2002–Revised 19 June 2003–Accepted 11 July 2003)

In the present study the effects of some C₁₈ fatty acids on hepatic fatty acid metabolism have been compared. Male rats were fed cholesterol-free diets containing either C_18 : 0, C_18 : 1 cis or C_18 : 1 trans isomers as the variables. In accordance with previous work, oleic acid in the diet caused an increase in cholesterol concentration in the liver and in the lipoprotein fraction of density (d; kg/l)<1·006. Oleic acid also reduced the triacylglycerol:cholesterol value in this fraction. Surprisingly, the C_18 : 1 trans isomers diet induced a decrease in the amount of cholesterol in total plasma as well as in the 1·019<d<1·063 lipoprotein fraction. Both oleic acid and C_18 : 1 trans isomers increased the concentration of triacylglycerols in the liver. The two C_18 : 1 fatty acids differently influenced the hepatic activities of carnitine palmitoyltransferase-I and 3-hydroxy-acyl-CoA dehydrogenase; both enzymes were inhibited by C_18 : 1 trans isomers, while no change was induced by oleic acid. The activity of the citrate carrier was lower in the oleic acid- and C_18 : 1 trans isomers-fed rats, when compared with the rats fed stearic acid. No diet effects were seen for the activities of acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, citrate synthase and phosphofructokinase. The results are interpreted in that oleic acid raised liver triacylglycerol by reducing the secretion of it with the d<1·006 lipoprotein fraction whereas the C_18 : 1 trans isomers enhanced liver triacylglycerol by lowering the hepatic oxidation of fatty acids.

Keywords:
Dietary fatty acids, Hepatic enzymes, Liver, Plasma lipoproteins

Abbreviations:
ACC, acetyl-CoA carboxylase, CPT, carnitine palmitoyltransferase, d, density, DGAT, diacylglycerol acyltransferase, 3-HAD, 3-hydroxy-acyl-CoA dehydrogenase, TAG, triacylglycerol