• M Teresa Macarulla, Alfredo Fernández-Quintela, Amaia Zabala, Virginia Navarro, Enrique Echevarría, Itziar Churruca, Víctor M Rodríguez, and María P Portillo.
• Department of Nutrition and Food Science, Faculty of Pharmacy, University of País Vasco, Vitoria, Spain.
• Nutrition. 2005 Apr 1; 21 (4): 512-9.

ObjectiveThe present work was designed to study the effects of the two main isomers of conjugated linoleic acid (CLA), cis-9,trans-11 and trans-10,cis-12, on liver composition and hepatic fatty acid oxidation in hamsters.MethodsAnimals were divided into three groups that were fed atherogenic diets supplemented with 0.5% linoleic acid, cis-9,trans-11 CLA, or trans-10,cis-12 CLA for 6 wk. Liver lipids, protein, water and DNA contents, and histologic structure were analyzed. Hepatic carnitine palmitoyltransferase-I and acyl coenzyme A oxidase activities were assessed. Triacylglycerol concentration, and aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase activities were evaluated in serum. CLA isomer contents were analyzed by gas chromatography in hepatic triacylglycerols. Peroxisome proliferator-activated receptor-alpha mRNA was determined by reverse transcriptase polymerase chain reaction.ResultsTrans-10,cis-12 CLA led to significantly greater weight, lower levels of triacylglycerol, cholesterol, and phospholipid, and larger total cell number in liver. Carnitine palmitoyltransferase-I and acyl coenzyme A oxidase activities were significantly increased by this isomer. No changes were induced by cis-9,trans-11 CLA. Trans-10,cis-12 CLA was recovered in significantly lower proportions than cis-9,trans-11 in liver triacylglycerols. Histopathologic analysis showed no abnormalities. No significant differences in serum aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase activities or in hepatic mRNA peroxisome proliferator-activated receptor-alpha expression were found among the three experimental groups.ConclusionsThese results suggest that the addition of 0.5% of these CLA isomers to the diet do not induce toxic effects in liver after 6 wk of feeding. Intake of trans-10,cis-12 isomer but not of cis-9,trans-11 CLA increases liver fatty acid oxidation. This effect leads to decreased hepatic and serum triacylglycerols.

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