Chronic administration of eicosapentaenoic acid and docosahexaenoic acid as ethyl esters reduced plasma cholesterol and changed the fatty acid composition in rat blood and organs

Abstract

Fish oils rich in n-3 fatty acids have been shown to decrease plasma lipid levels, but the underlying mechanism has not yet been elucidated. This investigation was performed in order to further clarify the effects of purified ethyl esters of eicosapentaenoic acid (EPA-EE) and docosahexaenoic acid (DHA-EE) on lipid metabolism in rats. The animals were fed EPA-EE, DHA-EE, palmitic acid, or corn oil (1 g/kg/d) by orogastric intubation along with a chow background diet for three months. At the end the animals were sacrificed. Plasma and liver lipids were measured, as well as lipid-related enzyme activities and mRNA levels. The fatty acid composition of plasma and different tissues was also determined. This study shows that, compared to the corn oil control, EPA-EE and DHA-EE lowered plasma cholesterol level, whereas only EPA-EE lowered the amount of plasma triacylglycerol. In liver peroxisomes, both EE preparations increased fatty acyl-CoA oxidase FAO activities, and neither altered 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase activities. In liver microsomes, EPA-EE raised HMG-CoA reductase and acyl-CoAicholesterol acyltransferase activities, whereas DHA-EE lowered the former and did not affect the latter. Neither product altered mRNA levels for HMG-CoA reductase, low density lipoprotein-receptor, or low density lipoprotein-receptor related protein. EPA-EE lowered plasma triacylglycerol, reflecting lowered very low density lipoprotein secretion, thus the cholesterol lowering effect in EPA-EE-treated rats may be secondary to the hypotriacylglycerolemic effect. An inhibition of HMG-CoA reductase activity in DHA-EE treated rats may contribute to the hypocholesterolemic effect. The present study reports that 20:5n-3, and not 22:6n-3, is the fatty acid primarily responsible for the triacylglycerol lowering effect of fish oil. Finally, 20:5n-3 was not converted to 22:6n-3, whereas retroconversion of 22:6n-3 to 20:5n-3 was observed.

Production performance of pigs reared in different systems and fed increased energy content diets with or without green alfalfa

“…Obtained dependencies confirmed the theory that PUFA/MUFA in animal food has an influence on the lipid profile of animals' blood serum (i.e. an increase in HDL and decrease in LDL cholesterol levels precisely) (Froyland et al, 1996;Barowicz & Pietras, 1998). In addition, in the blood serum of the animals in Group 6, a statistically significant and higher level of HDL cholesterol was recorded compared with pigs of Group 3.…”

Effects of n–3 Supplementation on Plasma and Liver Phospholipid Fatty Acids Profile in Aged Wistar Rats

“…Both tretment decreased AA content and n-6/n-3 PUFA ratio in the membranes, withouht modifying the unsaturation index. 33 Froyland et al 34 clarified the effects of purified esters of EPA and DHA on lipid metabolism in rats. The animals were fed by orogastric intubation 1 g/kg/day for 3 months.…”

Effect of N3-Poliunsaturated Fatty Acids as Coadjuvant in the Antihypertensive Treatment in Spanish Postmenopausal Women

“…C18:3-6 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.07 ± 0.36 0.00 ± 0.00 C18:3-3 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 C20: Some previous surveys have demonstrated a diminution in the blood pressure as consequence of n3-PUFAs [22,28], but with dosages higher than 3 g/day. In this sense, surveys with animas and humans have demonstrated that EPA and DHA are incorporated in a different way in plasma [29], platelets, cellular membranes [6] and fatty tissue [30]. According to these reports, the diminution in the SBP experienced by the SG could be due to a progressive doby accumulation of n3-PUFAs during the supplementation period.…”