Effects of conjugated linoleic acid on skeletal muscle triacylglycerol metabolism in hamsters.
OBJECTIVE
The present work evaluated the effects of conjugated linoleic acid (CLA) on various aspects of triacylglycerol metabolism in skeletal muscle to determine the potential involvement of this tissue in the effect of CLA to decrease body fat.


METHODS
Animals were randomized to three groups that were fed atherogenic diets that provided different amounts of trans-10,cis-12 CLA (0%, 0.5%, or 1%) for 6 wk. Muscle triacylglycerol, protein, water, glycogen, and DNA contents and fatty acid profile in triacylglycerols were analyzed. Lipoprotein lipase and carnitine palmitoyltransferase-I (CPT-I) activities were assessed. Triacylglycerol, glucose, and insulin concentrations were evaluated in serum.


RESULTS
The high dose of CLA increased food efficiency and gastrocnemius muscle weight. CLA feeding resulted in decreased muscle triacylglycerol content without changes in protein, water, glycogen, and DNA contents or in cell size (protein/DNA ratio) and produced decreased lipoprotein lipase activity and increased CPT-I activity. No differences were found between CLA doses. CLA feeding led to the saturation of stored triacylglycerols.


CONCLUSIONS
Decreased fatty acid uptake and increased fatty acid oxidation can contribute to the decreased muscle triacylglycerol content observed in hamsters fed the CLA diets. The increase in muscle fatty acid beta-oxidation might ultimately prevent storage of triacylglycerols in adipose tissue. Nevertheless, the lack of matching of lipoprotein lipase and CPT-I modifications makes it difficult to ensure that skeletal muscle is responsible, at least in part, for the effect of CLA on decreasing body fat; thus, further research is needed.
Zabala
Amaia
A
Department of Nutrition and Food Science, Faculty of Pharmacy, University of País Vasco, Vitoria, Spain.
Fernández-Quintela
Alfredo
A
Macarulla
M Teresa
MT
Simón
Edurne
E
Rodríguez
Víctor M
VM
Navarro
Virginia
V
Portillo
María P
MP
D000273:Adipose Tissue / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D007328:Insulin / Q000097:blood; D044243:Linoleic Acids, Conjugated / Q000008:administration & dosage* / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D008647:Mesocricetus; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010084:Oxidation-Reduction; D014280:Triglycerides / Q000032:analysis / Q000378:metabolism*
D001786:Blood Glucose; D007328:Insulin; D044243:Linoleic Acids, Conjugated; D014280:Triglycerides; D002334:Carnitine O-Palmitoyltransferase; D008071:Lipoprotein Lipase