Abstract
BackgroundCholesterol administration has been reported to influence hepatic lipid metabolism in rats. In the present study, the effect of dietary cholesterol on hepatic activity and mRNA expression of the enzymes involved in lipid metabolism were investigated. Fourteen male Wistar rats were randomly divided into 2 groups and fed 1% cholesterol or cholesterol free AIN76 diets for 4 weeks.ResultsThe serum triglyceride and high density lipoprotein cholesterol levels were significantly decreased but the total cholesterol and non high density lipoprotein cholesterol levels were significantly increased in the cholesterol-fed rats compared with the control rats. And the concentrations of the hepatic total cholesterol and triglyceride increased about 4-fold and 20-fold separately by dietary cholesterol. The activities of hepatic malic enzyme, glucose-6-phosphate dehydrogenase, fatty acid synthase, phosphatidate phophatase and carnitine palmitoyl transferase were depressed by the cholesterol feeding (40%, 70%, 50%, 15% and 25% respectively). The results of mRNA expression showed that fatty acid synthase, carnitine palmitoyl transferase 1, carnitine palmitoyl transferase 2, and HMG-CoA reductase were down-regulated (35%, 30%, 50% and 25% respectively) and acyl-CoA: cholesterol acyltransferase and cholesterol 7α-hydroxylase were up regulated (1.6 and 6.5 folds) in liver by the cholesterol administration.ConclusionsThe dietary cholesterol increased the triglyceride accumulation in liver, but did not stimulate the activity and the gene expression of hepatic enzymes related to triglyceride and fatty acid biosynthesis.
Highlights
Cholesterol administration has been reported to influence hepatic lipid metabolism in rats
In early 1990s, Thomas et al [1,2] has investigated the effect of cholesterol on the accumulation of liver lipids through the radioisotope 14C-fatty acid and proposed that the hepatic TG accumulation was developed by the enhancement of hepatic TG synthesis and the reduction of fatty acid beta-oxidation
Xu et al [4] has reported that the impaired hepatic lipid homeostasis because of lipid accumulation attributed to the increasing activity of the enzymes involved in fatty acid biosynthesis in the rats by the dietary cholesterol
Summary
Cholesterol administration has been reported to influence hepatic lipid metabolism in rats. The effect of dietary cholesterol on hepatic activity and mRNA expression of the enzymes involved in lipid metabolism were investigated. Dietary 0.5%-1.0% cholesterol can increase serum VLDL and LDL levels dramatically in rats In this case, dietary cholesterol remarkably disturbed triglyceride (TG) metabolism, the hepatic TG content increased in folds until hepatic steatosis forms. Dietary cholesterol remarkably disturbed triglyceride (TG) metabolism, the hepatic TG content increased in folds until hepatic steatosis forms Thereby, it has been developed as a non-alcoholic fatty. Xu et al [4] has reported that the impaired hepatic lipid homeostasis because of lipid accumulation attributed to the increasing activity of the enzymes involved in fatty acid biosynthesis in the rats by the dietary cholesterol. The mechanism of dietary cholesterol on lipid metabolism is still unclear
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