Impact of Reduced Dietary Levels of Eicosapentaenoic Acid and Docosahexaenoic Acid on the Composition of Skin Membrane Lipids in Atlantic Salmon (Salmo salar L.)

Membrane lipids, including sphingolipids and glycerol-phospholipids, are essential in maintaining skin barrier function in mammals, but their composition in fish skin and their response to diets have not been evaluated. This study investigated the impacts of reducing dietary EPA and DHA on membrane lipids in skin of Atlantic salmon, through a 26-week feeding regime supplying different levels (0%‒2.0% of drymass) of EPA/DHA. Ceramide, glucosylceramide, sphingomyelin, sphingosine, and sphinganine in salmon skin were analyzed for the first time. Higher concentrations of glucosylceramide and sphingomyelin, and higher ratios of glucosylceramide:ceramide and sphingomyelin:ceramide, were detected in the deficient group, indicating interruptions in sphingolipidomics. Changes in the glycerol-phospholipid profile in fish skin caused by reducing dietary EPA and DHA were observed. There were no dietary impacts on epidermal thickness and mucus cell density, but the changes in phospholipid profile suggest that low diet...