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The objective of the present research was to assess the influence of inositol supplementation on growth performance, histological morphology of liver, immunity and expression of immune-related genes in juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu). Hybrid grouper (initial weight 6.76 ± 0.34 g) were fed isonitrogenous and isolipidic diets (16%) with various inositol levels of 0.17 g/kg (J1, the control group), 0.62 g/kg (J2), 1.03 g/kg (J3), 1.78 g/kg (J4), 3.43 g/kg (J5), 6.59 g/kg (J6), respectively. The growth experiment lasted for 8 weeks. The results indicated that dietary inositol had a significant promoting effect on final mean body weight of the J5 and J6 groups and specific growth rate (SGR) of the J3, J4, J5 and J6 groups (P < 0.05). In the serum, superoxide dismutase (SOD) of the J4 group became significantly active compared with that of the control group (P < 0.05), while aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (AKP) activities in the inositol-treated groups showed distinctly decreased compared with those of the control group (P < 0.05). In the liver, dietary inositol could significantly increase the activities of SOD, catalase (CAT), lysozyme (LYZ) and the contents of total antioxidative capacity (T-AOC) and immunoglobulin M (IgM) (P < 0.05), and distinctly reduce the content of malondialdehyde (MDA) as well as reactive oxygen species (ROS) (P < 0.05). Compared with the control group, the damaged histological morphology of the liver was relieved and even returned to normal after an inositol increase (0.4–3.2 g/kg). In the liver, the remarkable up-regulation of SOD, CAT, glutathione peroxidase (GPX), heat shock protein70 (HSP70) and heat shock protein90 (HSP90) expression levels were stimulated by supply of inositol, while interleukin 6 (IL6), interleukin 8 (IL8) and transforming growth factor β (TGF-β) expression levels were down-regulated by supply of inositol. In head kidney, the mRNA of toll-like receptor 22 (TLR22), myeloid differentiation factor 88 (MyD88) and interleukin 1β (IL1β) expression levels were significantly down-regulated (P < 0.05), which could further lead to remarkable down-regulation of IL6 and tumor necrosis factor α (TNF-α) expression (P < 0.05). These results indicated that high-lipid diets with supply of inositol promoted growth, increased the antioxidant capacity, and suppressed the inflammation of the liver and head kidney by inhibiting the expression of pro-inflammation factors (IL6, IL8, TGF-β and TNF-α). In conclusion, these results indicated that dietary inositol promoted growth, improved antioxidant capacity and immunity of hybrid grouper fed high-lipid diets. Based on SGR, broken-line regression analysis showed that 1.66 g/kg inositol supply was recommended in high-lipid diets of juvenile grouper. • Dietary inositol promoted the growth performance of hybrid grouper. • Dietary inositol improved abnormal liver morphology caused by high-lipid diets. • Dietary inositol improved the antioxidant capacity of the liver in fish fed high-lipid diets. • Dietary inositol alleviated inflammation induced by high-lipid diets in the liver and head kidney. • Dietary inositol exhibits great potential to be an effective additive in the grouper high-lipid diets, to alleviate the adverse effects of the diets. [ABSTRACT FROM AUTHOR]

The experiment was conducted to investigate the effects of vitamin E (VE) on growth, oxidative stress and immunity for hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) fed high-lipid diet. Six groups of iso-protein (50.23%) and iso-lipidic high-lipid (15.36%) experimental diets were prepared by adding 0 (basic diet control), 0.01%, 0.02%, 0.03%, 0.04%, 0.05% α-tocopherol respectively in basic diet. Each treatment consisted of 3 replicates and 30 fish (10.20 ± 0.02 g) in each replicate for 8 weeks. The results showed that: 1) compared with the control group, the growth performance of grouper was not affected by the addition of VE in high-lipid diet, but the specific growth rate (SGR) in high VE dose (0.6%) group were significantly decreased compared with 0.02% and 0.03% groups. 2) Adding VE to high-lipid diet can alleviate the hepatic oxidative damage caused by high-lipid diet, and significantly improve the serum and liver antioxidant enzyme activity. 3) Compared with the control group, appropriate VE significantly increased the expression of liver anti-inflammatory factors TGF-β and IL10 , and significantly decreased the expression of proinflammatory factors IL8 and IL6. In conclusion, adding appropriate amount of VE into high-lipid diet can improve antioxidant capacity and immunity of grouper, we speculated that VE may alleviate lipid peroxidation by improving antioxidant capacity to reduce the inflammatory response. In combination with the results of the current study, we recommend an additional dose of 0.02%–0.03% of α-tocopherol in this experiment under high-lipid conditions. [Display omitted] • High lipid diet would not only induce excessive accumulation of liver lipid, but also affect physiological, biochemical and immune indexes. • VE in high-lipid diets can alleviate oxidative stress and inflammatory responses of grouper. • VE in high-lipid diets might upregulate anti-inflammatory factors and downregulate pro-inflammatory factors to diminishing oxidative damage and enhancing immunity. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of dietary choline levels on growth performance, liver histology, nonspecific immunity and related gene expression of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus) fed with high-lipid diets. The fish (initial body weight 6.86 ± 0.01 g) were fed diets containing different choline levels (0, 5, 10, 15, and 20 g/kg, named D1, D2, D3, D4, and D5, respectively) for 8 weeks. The results showed that:(1) dietary choline levels had no significant effect on final body weight (FBW), feed conversion rate (FCR), visceral somatic index(VSI) and condition factor (CF) compared with the control group (P > 0.05). However, the hepato somatic index (HSI) in the D2 group was significantly lower than that in the control group and the survival rate (SR) in the D5 group was significantly lower (P < 0.05). (2) with dietary choline level increasing, alkaline phosphatase (AKP) and superoxide dismutase (SOD) of serum showed a tendency to increase and then decrease, and the maximum values were obtained in the D3 group, but the contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) decreased significantly (P < 0.05). (3) Immunoglobulin M (IgM), lysozyme (LYZ), catalase (CAT), total antioxidative capacity (T-AOC), and SOD in the liver all showed a trend of first increase and then decrease with the dietary choline level increased, and all of them achieved the maximum value at D4 group (P < 0.05), while reactive oxygen species (ROS) and malondialdehyde (MDA) in the liver decreased significantly (P < 0.05). (4) results from liver sections suggest that appropriate levels of choline can improve cell structure, compared with the control group, the damaged histological morphology of the liver was relieved and even returned to normal in D3 group. (5) in the D3 group, choline significantly upregulated the expression of hepatic sod and cat mRNA, whereas the expression of cat in the D5 group was significantly lower than that in the control group (P < 0.05); And the supply of choline stimulated a significant down-regulation of interleukin 6 (il6), myeloid differentiation factor 8 (myd88), toll-like receptor 22 (tlr22) mRNA expression levels in liver, while the expression of cellular tumor antigen p53 (p53) and interleukin 10 (il10) showed an upward and then downward trend (P < 0.05). In general, choline can improve the immunity of hybrid grouper by regulating non-specific immune-related enzyme activity and gene expression and reducing oxidative stress induced by high-lipid diet. • Choline can significantly affect the biochemical indicators and enzyme activities related to non-specific immunity in hybrid grouper ( ♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu). • Choline significantly up-regulated the expression of anti-inflammatory genes p53 , il10 and antioxidant genes cat and sod , and inhibited the expression of pro-inflammatory genes il6 , myd88 and tlr22 in hybrid grouper. • Choline significantly improved cell structure of hybrid grouper. [ABSTRACT FROM AUTHOR]