Three differently generated salmon protein hydrolysates reveal opposite effects on hepatic lipid metabolism in mice fed a high-fat diet

This study investigates the effects of salmon peptide fractions, generated using different enzymatic hydrolyzation methods, on hepatic lipid metabolism. Four groups of mice were fed a high-fat diet with 20% casein (control group) or 15% casein and 5% of peptide fractions (treatment groups E1, E2 and E4) for 6 weeks. Weight gain was reduced in mice fed E1 and E4-diets compared to control, despite a similar feed intake. Reduced plasma and liver triacylglycerol levels in E1 and E4-mice were linked to reduced fatty acid synthase (FAS) activity and hepatic expression of lipogenic genes. By contrast, plasma and liver lipids increased in the E2 group, concomitant with increased hepatic FAS activity and Δ9 desaturase gene expression. Shotgun lipidomics showed that MUFAs were significantly reduced in the E1 and E4 groups, whereas PUFAs were increased, and the opposite was observed in the E2 group. In conclusion, bioactive peptides with distinctive properties could potentially be isolated from salmon hydrolysates.