Effects of Dietary Vegetable Oils Replacing Fish Oil on Fatty Acid Composition, Lipid Metabolism and Inflammatory Response in Adipose Tissue of Large Yellow Croaker (<i>Larimichthys crocea</i>)

The present study was conducted to investigate the effects of dietary vegetable oils (VOs) replacing fish oil (FO) on fatty acid composition, lipid metabolism and inflammatory response in adipose tissue (AT) of large yellow croaker (<i>Larimichthys crocea</i>). The initial body weight of a large yellow croaker was 10.07 ± 0.13 g. Three iso-nitrogenous and iso-lipidic diets were formulated by replacing FO with 0% (the control group), 100% soybean oil (SO) and 100% linseed oil (LO). Results showed that the contents of C18:2n-6 and C18:3n-3 were significantly increased in AT of fish fed the SO and LO diets compared with the FO diet, respectively. The proportion of n-6 polyunsaturated fatty acid (PUFA) was increased in SO and LO diets, while the proportions of saturated fatty acid and n-3 LC-PUFA were decreased. Moreover, dietary SO and LO significantly induced excess fat accumulation of AT by increasing the triglyceride content and the hypertrophy of adipocytes. Dietary SO and LO significantly increased lipogenesis-related gene expressions (<i>dagt2</i>, <i>fabp10</i>, <i>srebp1</i>, <i>cebpα</i> and <i>pparγ</i>), while decreasing the gene expression of <i>lpl</i>. Meanwhile, dietary SO increased the expression of genes related to fatty acid β-oxidation (<i>cpt1</i> and <i>aco</i>), while LO showed no differences. Furthermore, dietary SO and LO increased the pro-inflammatory gene expressions and decreased the anti-inflammatory gene <i>il10</i> expression. The phosphorylation levels of p38 MAPK and NF-κB were significantly upregulated by dietary SO and LO. In addition, there was a significant increase in macrophage infiltration and M1 polarization in AT of fish fed SO and LO diets. In conclusion, the present study revealed that dietary SO and LO replacing FO affected fatty acid composition and induced lipid dysmetabolism and inflammatory response in the adipose tissue of large yellow croaker.