Effects of ferulic acid on muscle development and intestinal microbiota of zebrafish.

Ferulic acid (FA) is one of a common ingredients in Chinese herbal medicine. FA has the interesting property of promoting growth and improving meat quality in livestock, but the mechanism is not understood. This study evaluated both safety and mechanism of efficacy in zebrafish model. At 15 µg/mL or above, FA led to pericardial oedema and delayed growth in zebrafish embryos. Dietary FA promoted growth and feed assimilation in male adult zebrafish. Genes related to myogenic development (myod1, myog and myf5) were significantly upregulated by FA and muscle fibre width in skeletal muscle was increased. At 20 µg/g, FA significantly increased number of goblet cells in zebrafish intestinal tissue, and gut microbiota composition also changed. Based on 16s rRNA gene sequences, 20 µg/g FA decreased Firmicutes and increased Bacteroides. 20 µg/g FA also stimulated the expression of PPAR-α, a gene associated with fat metabolism, and decreased the expression of PPAR-ß and PPAR-γ. These gene expression changes were beneficial to fatty acid synthesis and metabolism and decreased fat deposition. Our overall results indicated that FA can be a safe growth promotor in fish particularly in skeletal muscles.

Influence of dietary linseed oil as substitution of fish oil on whole fish fatty acid composition, lipid metabolism and oxidative status of juvenile Manchurian trout, Brachymystax lenok.

In this study, juvenile Manchurian trout, Brachymystax lenok (initial weight: 6.43 ± 0.02 g, mean ± SE) were received for nine weeks with five types of diets prepared by gradually replacing the proportion of fish oil (FO) with linseed oil (LO) from 0% (LO0) to 25% (LO25), 50% (LO50), 75% (LO75), and 100% (LO100). The eicosapentaenoic (EPA) and docosahexaenoic (DHA) composition decreased with increasing inclusion level of LO (P < 0.05). With increasing LO inclusion level, triglyceride (TAG) content of serum increased significantly, however, there was a decrease in high-density lipoprotein cholesterol (HDL) (P < 0.05). LO substitution of FO up-regulated the gene expression level of lipid metabolism-related genes Fatty Acid Desaturases 6 (FAD6), Acetyl-Coa Carboxylase (ACCα), Sterol Regulatory Element Binding Protein 1 (SREBP-1), and Sterol O- Acyl Transferase 2 (SOAT2), and down-regulated the gene expression level of Peroxisome Proliferator-Activated Receptor a (PPARα) (P < 0.05). The SOD activities of both serum and liver in LO100 were significantly lower than in LO25 (P < 0.05). The CAT activity of the liver in LO100 was significantly lower than in LO0 and LO25 (P < 0.05). This study indicates that the Manchurian trout may have the ability to synthesize LC-PUFAs from ALA, and an appropriate LO in substitution of FO (<75%) could improve both the lipid metabolism and the oxidation resistance.

Ameliorative effect of vitamin E on hepatic oxidative stress and hypoimmunity induced by high-fat diet in turbot (Scophthalmus maximus).

This study was conducted to examine the effects of vitamin E on growth performance, oxidative stress and non-specific immunity of turbot (Scophthalmus maximus) fed with high-fat diet. Results showed that high-fat diet significantly increased hepatosomatic index, viscerosomatic index, hepatic malondialdehyde level and decreased catalase and superoxide dismutase activities, whereas final weight, specific growth rate and survival rate remained unchanged. Meanwhile, nitro blue tetrazolium positive leucocytes of head kidney, respiratory burst activity in head-kidney macrophage, phagocytic index and serum lysozyme activity were significantly reduced after feeding with high-fat diet. Furthermore, fish fed with high-fat diet promoted higher expression of heat shock protein (hsp70, hsp90), and inhibited expression of complement component 3 (c3) in the liver and tumor necrosis factor-α (tnf-α), interleukine 1ß (il-1ß), toll like receptor 22 (tlr-22) in the spleen and head-kidney, respectively. However, simultaneous supplementation with 480 mg kg-1 vitamin E protected turbot against high-fat diet-induced hepatic oxidative stress, hypoimmunity through attenuating lipid peroxidation, renewing antioxidant enzymes activities and nonspecific immune responses, and modulating the expression of stress protein (hsp70, hsp90) and immune-related genes (c3, tnf-α, il-1ß, tlr-22). In conclusion, the obtained results indicate the vitamin E as a wildly used functional feed additive contributes potentially to alleviate high-fat diet-induced hepatic oxidative stress and hypoimmunity, maintain the health, and improve the broodstock management for turbot.

Effect of dietary vitamin E on the growth performance and nonspecific immunity in sub-adult turbot (Scophthalmus maximus).

This study investigated the growth performance and non-specific immunity in sub-adult turbot fed with graded levels of vitamin E (0, 120, 240, 480 and 960 mg kg(-1)) for 15 weeks. Results showed that the final weight, specific growth rate, nitro blue tetrazolium positive leucocytes of head kidney, phagocytic index, serum lysozyme activity and superoxide dismutase activity significantly increased with increasing vitamin E levels. The highest values were recorded in the diet with 480 mg kg(-1) vitamin E. However, no significant differences in the hepatosomatic index, viscerosomatic index and survival rate were found among all dietary treatment. Furthermore, the expression levels of complement component 3 (C3), tumor necrosis factor-α (TNF-α) and interleukine 1ß (IL-1ß) were significantly upregulated in the fish feed with the vitamin E-supplemented diets. Compared with the basal diet, the diet supplemented with 480 mg kg(-1) vitamin E significantly augmented the mRNA expression of IL-1ß, TNF-α in the spleen and head-kidney, C3 in the liver, respectively. In conclusion, the obtained results indicate the basal diet supplemented with moderate dietary vitamin E (480 mg kg(-1)) increased the growth, nonspecific immune responses, and expression levels of some immune-related genes in sub-adult turbot. These observations suggest that optimal dietary vitamin E can promote the growth, maintain the health and improve the broodstock management for turbot.