Effects of <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 conjugated linoleic acid on cholesterol metabolism in hypercholesterolaemic hamsters |
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Authors: | Virginia Navarro M Teresa Macarulla Alfredo Fernández-Quintela Víctor M Rodríguez Edurne Simón María P Portillo |
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Institution: | (1) Dept. of Nutrition and Food Science, Faculty of Pharmacy, University of País Vasco, Paseo de la Universidad 7, 01006 Vitoria, Spain |
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Abstract: | Background Conjugated linoleic acid (CLA) has received great attention in recent years because of its pleiotropic biological activities,
but considerably fewer studies have been published addressing its role in serum lipids and atherosclerosis compared to other
topics covered.
Aims of the study The aim of the present study was to assess the effects of the trans-10,cis-12 isomer of CLA on cholesterolaemia and on several metabolic pathways involved in cholesterol metabolism in hamsters.
Methods Animals were fed atherogenic diets supplemented with 0.5% linoleic acid, 0.5% trans-10,cis-12 CLA or 1.0% trans-10,cis-12 CLA, for 6 weeks. Serum lipoproteins were separated by FPLC. Cholesterol in serum and liver, as well as triacylglycerols
and phospholipids in liver were assessed by spectrophotometry. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoAR),
acyl-coenzyme A:cholesterol acyltransferase (ACAT) and cholesteryl ester hydrolase (CEH) activities were measured by radiometry,
and LDL receptors were determined by Western blot.
Results
trans-10,cis-12 CLA feeding did not modify food intake nor final body weight. Although serum total cholesterol remained unchanged, when
cholesterol fractions were analyzed a significant decrease in VLDL-cholesterol was observed in CLA-fed animals, without changes
in HDL-cholesterol or LDL-cholesterol. trans-10,cis-12 CLA decreased cholesterol ester content and increased free cholesterol in liver. The activity of HMGCoAR was not modified.
In contrast, ACAT activity was reduced by both CLA doses and CEH was increased by the high CLA dose. LDL receptors were significantly
reduced by trans-10,cis-12 feeding when expressed as arbitrary units per mg of protein, however, the total receptor mass remained unchanged.
Conclusions These results suggest that, under the present experimental conditions, trans-10,cis-12 CLA feeding reduces cholesterol esterification in liver and decreases the minority serum VLDL-cholesterol fraction, but
it does not show a hypocholesterolaemic effect. A dose–response effect was not observed. |
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Keywords: | CLA cholesterol hamster liver |
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