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Diets supplemented with Saccharina latissima influence the expression of genes related to lipid metabolism and oxidative stress modulating rainbow trout (Oncorhynchus mykiss) fillet composition

Ferreira, Mariana, Larsen, Bodil Katrine, Granby, Kit, Cunha, Sara C., Monteiro, Carolina, Fernandes, José O., Nunes, Maria L., Marques, António, Dias, Jorge, Cunha, Isabel, Castro, L. Filipe C., Valente, Luisa M.P.
Food and chemical toxicology 2020 v.140 pp. 111332
Oncorhynchus mykiss, Saccharina latissima, antioxidants, body weight, cholecalciferol, cholesterol, dietary supplements, fatty acids, fatty-acid synthase, fillets, fish, gene expression, genes, humans, iodine, lipemic effect, lipid metabolism, liver, macroalgae, messenger RNA, muscles, oxidative stress, toxicology, transcription (genetics)
This study aimed to evaluate the impact of diets including increasing amounts (1, 2 and 4%) of an iodine-rich macroalgae, Saccharina latissima, on gene expression and fillet composition of commercial-sized rainbow trout. Liver and muscle expression of genes related to growth, iodine, oxidative stress, and lipid metabolism, and the fillet content of fatty acids, cholesterol, and vitamin D₃ were assessed. The highest kelp inclusion led to lower final body weight and HSI, without significant differences in mRNA transcription of genes involved in growth (ghr1, ghr2 and igf1) or iodine metabolism (dio1, thra, and thrb). A significant downregulation of an oxidative stress marker, gpx1b2, was observed in fish fed 2% S. latissima, which might suggest the need for less endogenous antioxidants. Dietary inclusion of kelp impacted lipid metabolism, with a downregulation of fatty acid synthase, accompanied by a general decrease of fatty acids in fillet. The present study demonstrated that supplementation of diets with 1 or 2% S. latissima can be achieved without detrimental effects on rainbow trout final weight. Evidence suggest a lipid-lowering effect of diets that did not compromise fillet EPA and DHA concentrations, being 3.7 times above the recommended levels for human consumption.