Sesamin Supplementation Increases White Muscle Docosahexaenoic Acid (DHA) Levels in Rainbow Trout (Oncorhynchus mykiss) Fed High Alpha-Linolenic Acid (ALA) Containing Vegetable Oil: Metabolic Actions

The effects of including an equi-mixture of sesamin and episesamin in fish diets based on vegetable oils of different fatty acid composition were examined. Sesamin/episesamin (hereafter named sesamin) was included at 0.58 g/100 g diet. The oil used in the feed was either a mixture of linseed and sunflower oils (6:4, by vol) or 100% linseed oil. Addition of sesamin increased the percentages of docosahexaenoic acid (DHA) in white muscle phospholipid and triacylglycerol fraction by up to 37% but the fatty acids in red muscle and liver were not affected. The expression of the peroxisome proliferator-activated receptor PPAR alpha was significantly down regulated in the liver of the fish fed sesamin and mixed oil diet (P < 0.05). Sesamin and episesamin were detected in liver and muscle tissues of the fish that had been fed sesamin. Fish fed sesamin had elevated levels of total cytochrome P450 (CYP) enzymes and EROD activity in the liver, indicating an induction of CYP1A in this tissue. Our conclusion was that supplementation of fish feed with sesamin increased the proportions of DHA in the white muscle.