Effects of conjugated linoleic acid on liver composition and fatty acid oxidation are isomer-dependent in hamster.
OBJECTIVE
The 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.


METHODS
Animals 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.


RESULTS
Trans-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.


CONCLUSIONS
These 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.
Macarulla
M Teresa
MT
Department of Nutrition and Food Science, Faculty of Pharmacy, University of País Vasco, Vitoria, Spain.
Fernández-Quintela
Alfredo
A
Zabala
Amaia
A
Navarro
Virginia
V
Echevarría
Enrique
E
Churruca
Itziar
I
Rodríguez
Víctor M
VM
Portillo
María P
MP
D042962:Acyl-CoA Oxidase / Q000187:drug effects / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002334:Carnitine O-Palmitoyltransferase / Q000187:drug effects / Q000378:metabolism; D002849:Chromatography, Gas / Q000379:methods; D006224:Cricetinae; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology*; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D011506:Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors; D014166:Transferases / Q000097:blood; D014280:Triglycerides / Q000097:blood; D014867:Water / Q000378:metabolism
D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D011506:Proteins; D014280:Triglycerides; D014867:Water; D004247:DNA; D042962:Acyl-CoA Oxidase; D014166:Transferases; D002334:Carnitine O-Palmitoyltransferase; D000469:Alkaline Phosphatase