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A 56-day feeding trial was conducted to investigate the effects of genistein on growth, lipid metabolism, antioxidant capacity, and immunity of common carp fed with high-carbohydrate or high-fat diets. Five diets were used to feed fish: control diet (5% fat; CO), high-fat diet (11% fat; HF), high-carbohydrate diet (45% carbohydrate; HC), and HF or HC diet with 500 mg/kg genistein (FG or CG). Results showed that final body weight (FW) and specific growth rate (SGR) were significantly reduced, but the supplementation with genistein resulted in higher values of FW and SGR than the HF or HC group. Both high carbohydrate and high fat belong to high-energy diets, which may promote lipid deposition. Genistein obviously decreased liver triglyceride (TG) content and alleviated hepatic fat vacuolation in the HF and HC groups. The expression of lipid metabolism genes (cpt-1 and atgl) was markedly higher in the FG group than in the HF group. The lipid synthesis-related genes (fas, acc, and pparγ) were elevated in high-energy diets but recovered to the control level or reduced after genistein treatments. With respect to fatty acid transporter genes, fatp increased in the FG group, and cd36 increased in the CG group. Furthermore, the antioxidant and immune indexes, such as total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), acid phosphatase (ACP), and lysozyme (LZM) activities, were decreased, while malonate aldehyde (MDA) content, activities of alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were enhanced in the HF and HC groups. The antioxidant and immunity values could be ameliorated by treatment with genistein. Moreover, the transcript levels of antioxidant-related genes (cat, gr, and nrf2) in the liver and anti-inflammatory factors (tgf-β and il-10) and lyz in the head kidney tissue were promoted, although the expression levels of proinflammatory factors (tnf-α and il-6) declined in the genistein supplementation group, which confirmed the antioxidant and immune-enhancing effects of genistein. Therefore, 500 mg/kg genistein could ameliorate the negative effects of high-energy diets on immunity. [ABSTRACT FROM AUTHOR]

This experiment was performed to determine the effect of dietary genistein on the growth, antioxidation, immunity, as well as lipid metabolism of common carp (Cyprinus carpio.L). Six experimental feeds containing 0 (control group), 25, 50, 100, 500 or 1000 mg/kg of genistein were respectively formulated. The feeds were randomly assigned to triplicate tanks with 30 fish (initial weight (20.59 ± 0.69) g) for 8 weeks. All the growth parameters were significantly improved by supplementation with 100 and 500 mg/kg genistein. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were reduced, but the acid phosphatase (ACP) activity was increased in serum of the 100 mg/kg genistein group. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) levels were significantly increased in serum when the feed was supplemented with 500 mg/kg of genistein. The total cholesterol (TC), triglyceride (TG), and low–-density lipoprotein cholesterol (LDL-C) levels in serum were reduced in the genistein (100 and 500 mg/kg) supplement groups. The mRNA expression levels of the pro-inflammatory cytokines, such as interleukin 1 (il-1) , the nuclear factor kb (nf-kb) , and il-8 were reduced, but the expressions of anti-inflammatory cytokines, such as transforming growth factor-b (tgf-b) and il-10 were enhanced in the head kidney and spleen tissues after genistein supplementation. Furthermore, the immune enhancement of genistein was confirmed by increasing the survival rate of common carp to Aeromonas hydrophila challenge. In addition, the fatty acids profile in the liver and muscle of common carp indicated that an increase of muscle total PUFA, especially n-3 PUFA and HUFA levels in 100 or 500 mg/kg genistein supplement groups. Meanwhile, after the feeding trial, the amount of total PUFA in the liver was significantly elevated in the 500 mg/kg genistein group. As the acsl6 and elovl5 mRNA expressions in the liver were enhanced after genistein treatment, the biosynthesis ability of endogenous HUFA may be enhanced. Moreover, lipogenesis-related genes in the liver were down-regulated after genistein treatment. Therefore, 100 and 500 mg/kg of genistein can significantly improve growth, body composition and lipid metabolism, enhance the antioxidant and immunity of common carp. • Common carp fed 100 or 500 mg/kg genistein showed a reduction of lipid level and improved the muscle fatty acid compositions. • Dietary 100 or 500 mg/kg genistein up-regulated hepatic lipolysis gene, while down-regulated lipid synthesis gene expression. • Dietary 100 or 500 mg/kg genistein reduced the pro-inflammatory cytokines, but enhanced anti-inflammatory cytokines levels. • Dietary 100 or 500 mg/kg genistein enhanced the antioxidant capacity and resistance to Aeromonas hydrophila of common carp. [ABSTRACT FROM AUTHOR]