Comparative Effect of Fish Oil Feeding and Other Dietary Fatty Acids on Plasma Lipoproteins, Biliary Lipids, and Hepatic Expression of Proteins Involved in Reverse Cholesterol Transport in the Rat

Abstract

Background: While elevated plasma high-density lipoprotein (HDL) levels has been associated to a reduction in cardiovascular risk, dietary fish oils rich in omega–3 polyunsaturated fatty acids (PUFAs) may protect against this disease. The protective effect of HDL is associated to its participation in the reverse cholesterol transport pathway. On the other hand, omega–3 PUFAs decrease plasma HDL levels compared to other fatty acids, which may suggest an effect on reverse cholesterol transport. Aim: In this work, the effect of dietary fish oil on the fatty acid composition of hepatic membranes, plasma lipoprotein cholesterol profile, biliary lipids, and the expression of proteins involved in reverse cholesterol transport, was compared to other dietary oils having a different degree of fatty acid unsaturation. Methods: Male rats were fed a semi synthetic diet containing fish oil (omega–3), sunflower oil (omega–6), olive oil (omega–9) or coconut oil (saturated). Hepatic membrane fatty acid composition, plasma cholesterol levels, lipoprotein cholesterol profile, biliary lipids, hepatic mRNA levels for lecithin cholesterol acyltransferase, hepatic lipase, apo E, and apo A-I, and hepatic protein levels of the scavenger receptor class B type I, caveolin-1, and the ATP binding cassette transporter A1 were analyzed. Plasma apo A-I and apo E protein levels were also evaluated. Results: Compared to the other diets, omega–3 PUFAs significantly changed omega–3/omega–6 fatty acid ratio of hepatic membranes, caused a reduction of plasma total and HDL cholesterol, and selectively increased biliary cholesterol secretion. No modification in the expression levels of lecithin cholesterol acyltransferase, hepatic lipase, apo A-I and apo E mRNA was observed. Hepatic scavenger receptor class B type I, caveolin-1, and the ATP binding cassette transporter A1 protein levels were also not affected. Plasma apo A-I, but not apo E, was reduced. Conclusions: These results show that dietary omega–3 PUFAs reduce plasma HDL cholesterol and increase biliary cholesterol without concomitant modifications in the expression of key genes and proteins involved in reverse cholesterol transport. These findings suggest that functional changes in the activity of these proteins as consequence of the incorporation of omega-3 PUFAs into hepatic membranes and plasma lipoproteins may underlie the effect of fish oil feeding on plasma and hepatic cholesterol metabolism in the rat.

Regulation of intestinal NPC1L1 expression by dietary fish oil and docosahexaenoic acid

“…Polyenoic fatty acids derived from fish oil (n-3 fatty acids) have been shown to decrease cholesterol absorption (20)(21)(22) and reduce plasma cholesterol in both animal models and humans (23)(24)(25)(26)(27)(28)(29). The mechanism for how fish oil-derived fatty acids interfere with cholesterol absorption is not clear.…”

Effect of docosahexaenoic acid monoacylglyceride on systemic hypertension and cardiovascular dysfunction

“…Aortic wall thickness has been found to be negatively associated with -3 fatty acids of all tissues but positively associated with TC and TG concentrations (29). Analysis of the present data showed that the aortic wall was significantly thinner, with TC, TG, and LDL-VLDL levels being significantly lower in the MAG-DHA-treated group relative to the untreated HFHC group.…”

“…Moreover, fish intake has been shown to reduce coronary artery atherosclerosis progression (14), whereas trans fat accelerated its progression (28). Concomitantly, previous studies consistently found that fish oil consumption decreased TG, TC, and LDL levels and increased HDL cholesterol levels (25,29,39).…”

Ações do óleo de peixe e triglicerídeos de cadeia média na esteatose hepática e estresse oxidativo induzidos pela dieta hiperlipídica em ratos

“…A dieta rica em gordura saturada é associada ao aumento do colesterol sérico (Morgado, Rigotti et al 2005). A dieta hiperlipídica utilizada no estudo, é rica em ácidos graxos saturados e colesterol provenientes da gordura animal, e apesar das alterações no acúmulo de gordura hepática, não foi associada ao aumento dos (Turkenkopf, Maggio et al 1982;Geelen, Schoots et al 1995;Discussão Lieber, DeCarli et al 2008) e do Colesterol Total, quando são associados à dieta hiperlipídica rica em colesterol (Wollin, Wang et al 2004).…”

“…Os ácidos graxos poli-insaturados n-3 presentes no óleo de peixe são associados à redução nos níveis de colesterol total e triglicerídeos séricos (Fickova, Hubert et al 1998;Morgado, Rigotti et al 2005;Sudheendran, Chang et al 2010). A redução da LDL col sérica em animais alimentados com óleo de peixe é associada à redução da sua produção hepática (Ventura, Woollett et al 1989).…”