Effect of dietary eicosapentaenoic and docosahexaenoic acid on expression of rat liver genes controlling cholesterol homeostasis and on plasma cholesterol level

Abstract

A hypothesis that eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) lower plasma cholesterol via increased expression of the Insig-1 gene with ensuing decrease of expression of genes coding for 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr) and low density lipoprotein receptor (Ldlr) was tested in rats fed a diet with 3% of fish oil (FO). Expression of the Insig-1 gene in the liver of the FO-fed rats was 730% (P < 0.05) of the control. However, contrary to the hypothesis, expression of the Hmgcr gene and Ldlr gene was 165% and 210% of the control (P > 0.05). Nevertheless, FO in the diet decreased (P < 0.05) plasma cholesterol of rats by 10% (from 1.19 to 1.07 mmol/l); it was therefore concluded that the cholesterol-lowering effect of EPA+DHA is at least partly based on mechanisms other than tested in the present experiment.