Effect of dietary conjugated linoleic acid on molecular markers for bile acid metabolism, cholesterol synthesis and inflammation in rats
Abstract
Several investigators have shown that dietary conjugated linoleic acid (CLA) reduced atherosclerosis in experimental animals (Wilson et al., 2000; Kritchevsky et al., 2004; Valeille et al., 2004). Although the mechanisms involved in this phenomenon have not been established, reduced de novo cholesterol synthesis, increased bile acid excretion and suppressed inflammation have been implicated. The purpose of the present study was to examine in more detail the potential molecular effects of dietary CLA on regulation of enzymes involved in regulation of cholesterol and bile acid metabolism and to evaluate its influence on markers of inflammation in rats. CLA refers to a mixture of linoleic acid isomers containing conjugated double bonds and found predominately in foods derived from ruminant animals. Two experiments were conducted in which Wistar rats were fed diets containing butter enriched with CLA or fortified with commercial CLA was compared with corn oil fortified with similar levels of CLA. In the first experiment, feeding CLA to rats resulted in no significant changes in hepatic mRNA levels of key enzymes involved in regulation of cholesterol or bile acid metabolism that could definitively connect CLA's anti-atherosclerotic mechanism to altered cholesterol levels or cholesterol balance. Additionally, no suppression of inflammatory markers was observed. Similar findings were observed in the second experiment in which the diet also contained cholesterol. These results indicated that, in the Wistar rat, CLA does not alter cholesterol balance or inflammation suggesting that observed changes in atherosclerosis are a result of species differences or are due to a mechanism not examined in the present study. However, the impact of dietary CLA appeared to be influenced by the presence of other dietary lipids (butter vs. corn oil) and may warrant further investigation.
Degree
Ph.D.
Advisors
Donkin, Purdue University.
Subject Area
Nutrition|Molecular biology
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