Effects of Various Dietary Fats on Lipid Metabolism in Hamster Small Intestine

Abstract

The hypolipidemic and anti-atherosclerotic effects of EPA have been reported in some studies. We investigated the effects of EPA on lipid metabolism in hamster small intestine as compared to other dietary fats.
Male golden hamsters were fed the following diets for 20 days: a control diet, a diet containing 20% safflower oil, a diet containing 20% coconut oil, and a diet plus 300mg/kg EPA. The lipid levels were measured by the enzymatic method. Microsomal HMG CoA reductase (HMG-CR) activity was measured following by the method of Field et al.
1) EPA significantly decreased plasma TC and TC—HDL-C levels, and tended to decrease plasma TG levels. 2) Safflower oil failed to significantly change plasma lipid levels. Coconut oil significantly increased plasma TC, TG and TC—HDL-C levels. 3) EPA significantly decreased microsomal TC, FC, and TG contents in the small intestine. On the contrary, safflower oil and coconut oil increased these lipid contents. 4) EPA significantly decreased microsomal HMG-CR activity in small intestine. Safflower oil failed to cause significant change to microsomal HMG-CR activity, and coconut oil significantly increased it.
These results suggest that EPA causes a reduction in cholesterol synthesis and decreases microsomal free cholesterol contents. Based on this evidence, we conclude that LDL receptor activity can be regulated upward by the suppression of HMG CoA reductase activity with EPA, and consequently plasma cholesterol levels are lowered.