Effects of dietary lipid sources on hepatic nutritive contents, fatty acid composition and proteome of Nile tilapia (Oreochromis niloticus)

Dietary oils of varying fatty acid composition have been used in tilapia feeds; nevertheless, investigation of their effects on metabolism and physiological processes has been limited. Therefore, in this study, using proteomic technology, the effects of different dietary lipids (DLs) on hepatic lipid metabolism and physiological processes were investigaed in Nile tilapia (Oreochromis niloticus). Fish were fed with different DL, which included palm oil (PO), linseed oil (LO) and soybean oil (SBO) for 90 days. Growth performance appeared to be similar among the dietary group. Hepatic FA contents were reflected by DL. Dietary PO (source of saturated fatty acids; SFA) led to an increase in the hepatosomatic index as well as lipid and protein contents in liver. Dietary SBO (source of n-6 polyunsaturated fatty acids; n-6 PUFAs) increased hepatic carbohydrate contents, but decreased the hepatic protein. The proteomic analysis showed that these nutritive changes in the liver were mediated by several proteins involved in lipid, carbohydrate, and amino acid metabolism. Dietary SBO showed an increased accumulation in proteins related to oxidative stress, immune and inflammatory processes. Dietary LO (source of n-3 PUFAs) increased abundance of cytoskeleton-related proteins. qRT-PCR was performed to provide supportive information for the result of proteomic study. Similar effects of DLs on mRNA levels were observed for atp5b, krt18, and selenbp1. Combined together, dietary SFA could supply as energy reservoir for regular activites. Dietary n-3 and n-6 PUFAs led to induce vital metabolic and physiologic processes which would contribute to maintaining normal health and/or providing health-related benefits. Significance: Dietary SBO increased hepatic carbohydrate contents, but decreased the hepatic protein. Different dietary lipid led to alter the abundance of several proteins (i.e., DHRS1, ATP5B, PLA2G12B, APO, AMY2A, GRP78, PRSS1, FAH, and PRSS36) involved in lipid, carbohydrate, and amino acid metabolism. Dietary SBO showed an increased accumulation in proteins (i.e., QDPR, CABC1, and PRDX6) that respond to oxidative stress, suggesting that n-6 PUFAs induce oxidative conditions. Dietary SBO led to increase the accumulation of proteins (i.e., NITR26, NCCRP1, and LCN) involved in immune and inflammatory processes. Dietary LO increased the abundant levels of cytoskeleton-related proteins (i.e., ACTB, AHNAK, ERC2, KRT18, and RILP1). Other proteins (i.e., SELENBP1, FAM46C, and ANC1) involved in other physiological processes were also modulated by DL. qRT-PCR was performed to provide supportive information of proteomic study. Similar effects of DLs on mRNA levels were observed for atp5b, krt18, and selenbp1.