Effects of High-Fat Diets Containing Different Fats on Cholesterol Metabolism in Starvation-Refeeding Rats

Reiko Inai,Tatsuhiro Matsuo

doi:10.4236/fns.2011.26090

Reiko Inai, Tatsuhiro Matsuo

Open Access

https://doi.org/10.4236/fns.2011.26090

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Abstract

The present study was performed to investegate the effects of high-fat diets containing different fats on cholesterol metabolism in starvation-refeeding rats. Forty female Donryu rats were divided into two groups and then fed high-fat diets containing beef tallow or corn oil without cholesterol for 14 days. Then, 10 rats from each group were divided into high-cholesterol and cholesterol-free groups (Experiment 1). Another 10 rats from beef tallow and corn oil groups were divided into high-cholesterol and high-cholesterol-cholestyramine groups (Experiment 2). All rats were fasted for 2 days followed by 3 days of feeding. In Experiment 1, the high-cholesterol diet caused significant increases in plasma total cholesterol and cholesteryl ester concentrations in the beef tallow diet group. In Experiment 2, dietary cholestyramine markedly decreased plasma and liver cholesterol levels; however, these cholesterol levels were higher in the beef tallow diet group even if cholestyramine was added to the diet. These results suggested that the cholesterol- lowering effect of dietary corn oil may not be due solely to reabsorption of bile acids. This study suggested that high-fat diets containing different fats affected cholesterol metabolism under conditions of starvation-refeeding.

Highlights

It is well established that starvation followed by refeeding causes an increase in mammalian hepatic lipogenesis in comparison to the levels obtained with the same diet fed ad libitum [1,2,3,4,5,6,7]
We found that dietary supplemental 1% cholesterol increased plasma cholesterol concentration in rats fed a beef tallow diet compared to rats fed a corn oil diet under the starvetion-refeeding conditions
The increase of cholesteryl ester concentration indicated that a beef tallow diet may influence the synthesis of hepatic acylCoA: cholesterol acyltransferase (ACAT; EC2.3.2.26) [27]

Summary

Introduction

It is well established that starvation followed by refeeding (starvation-refeeding) causes an increase in mammalian hepatic lipogenesis (de novo synthesis of longchain fatty acids) in comparison to the levels obtained with the same diet fed ad libitum [1,2,3,4,5,6,7]. Cholesterol, a physiologically significant lipid, as well as triacylglycerol (TG) or fatty acids, is present in tissues and in plasma lipoprotein either as free cholesterol or, in combination with long-chain fatty acids, as cholesteryl ester [14]. It is synthesized in many tissues from acetyl-CoA and is eliminated from the body in the bile as cholesterol or bile salts. Cholesterol synthesis in the liver may be accelerated under conditions of activated hepatic lipogenesis because cholesterol and fatty acids are closely related to mammalian lipid metabolism [15]

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