Background & Aims: Non-alcoholic fatty liver disease accompanies obesity and is independently associated with cardiovascular disease. Omega-3 fatty acids, such as docosahexaenoic (DHA) and eicosapentaenoic (EPA) acid, reduce the risk of cardiovascular disease due to their anti-inflammatory and hypolipidemic effects. Recent data suggested that metabolic effects of EPA/DHA as marine phospholipids could be stronger than triglycerides (fish oil). We characterised the mechanisms underlying beneficial effects of EPA/DHA phospholipids alone or in combination with antidiabetic drugs on hepatosteatosis in dietary obese mice. Methods: Male C57BL/6N mice were fed for 7 weeks a corn oil-based high-fat diet (cHF) or subjected to cHF-based interventions: (i) cHF with DHA/EPA as phosphatidylcholine-rich concentrate replacing ~10 % of dietary lipids (PC); ii) cHF with a low-dose of thiazolidinedione rosiglitazone (10 mg/kg diet), which retains some of the beneficial effects but also potentiates hepatic lipid accumulation (R); and iii) PC+R. Metabolic profiling together with hepatic gene expression and lipidomic analyses were performed.
Results: PC and PC+R prevented weight gain and glucose intolerance induced by cHF, while all interventions reduced abdominal fat and plasma triglycerides. In contrast to R, PC and PC+R lowered hepatic and plasma cholesterol and eliminated hepatosteatosis. Hepatic microarray analysis primarily revealed a complex downregulation of lipogenic and cholesterol biosynthesis pathways by PC. Lipidomic analysis identified arachidonic acid, DHA and EPA in hepatic phosphatidylcholine and phosphatidylethanolamine fractions as the most important variables. Importantly, down-regulation of genes within these pathways was enlarged by phospholipid versus triglyceride forms of EPA/DHA in an independent experiment. Conclusions: Obesity-associated hepatosteatosis and hypercholesterolemia were ameliorated by marine phospholipids in association with a complex inhibition of biosynthetic pathways in liver. Stronger effects of phospholipids versus triglyceride form of EPA/DHA suggest their preferential use in the prevention and possible treatment of obesity-associated metabolic hepatic dysfunctions.