Sesamin increases alpha-linolenic acid conversion to docosahexaenoic acid in atlantic salmon (Salmo salar L.) hepatocytes: role of altered gene expression.

In vitro cultivated Atlantic salmon (Salmo salar L.), hepatocytes were incubated without or with a mixture of sesamin and episesamin in order to test for possible effects on lipid metabolism. Sesamin/episesamin exposure (0.05 mM, final concentration) led to increased elongation and desaturation of (14)C 18:3n-3 to docosahexaenoic acid ((14)C 22:6n-3, DHA, P < 0.01) and down regulated gene expression of Delta6 and Delta5 desaturases compared to control treatment. Sesamin/episesamin further increased the hepatocytes capacity for fatty acid beta-oxidation of (14)C 18:3n-3 (P < 0.01) to the (14)C acid soluble products, acetate, malate and oxaloacetate, in agreement with an increased gene expression of carnitine palmitoyltransferase I. Also the gene expression of cluster of differentiation 36 was upregulated and the expression of scavenger receptor type B, peroxisome proliferator-activated receptors alpha and gamma were downregulated. The amount of triacylglycerols secreted by the cells tended to be lower in the sesamin/episesamin incubated hepatocytes than the control cells. This study shows that sesamin has favourable effects on lipid metabolism leading to increased level of DHA, which may be of interest for aquaculture use.