Chlorogenic acid improves common carp (Cyprinus carpio) liver and intestinal health through Keap-1/Nrf2 and NF-κB signaling pathways: Growth performance, immune response and antioxidant capacity.

In this experiment, we investigated the effects of adding chlorogenic acid (CGA) to the diet on growth performance, immune function, inflammation response, antioxidant capacity and its related mechanisms of common carp (Cyprinus carpio). A total of 600 fish were selected and randomly divided into five treatment groups and fed with CGA containing 0 mg/kg (CK), 100 mg/kg (L100), 200 mg/kg (L200), 400 mg/kg (L400) and 800 mg/kg (L800) for 56 days. The results of the experiment were as follows: addition of CGA significantly increased the WGR, SGR, FER, and PER of common carp (P < 0.05). The addition of 400-800 mg/kg of CGA significantly increased the serum levels of LZM, AKP activity, C3 and C4 concentration, and increased immune function of common carp (P < 0.05). Regarding antioxidant enzyme activities, adding CGA significantly increased SOD, CAT, and GsH-Px activities, while decreasing MDA content (P < 0.05). Compared with the CK group, the mRNA expression levels of NF-κB, TNF-α, and IL-1ß were decreased. The IL-10 and TGF-ß were increased in the liver and intestines of the CGA supplemented group. Meanwhile, the addition of CGA also significantly up-regulated the mRNA expression levels of Nrf2, HO-1, SOD, CAT, and GPX (P < 0.05). CGA also positively contributed to the development of the carp intestinal tract, as demonstrated by decreased serum levels of DAO, D-LA, and ET-1. And the mucosal fold height was increased significantly with increasing levels of CGA. In conclusion, the addition of CGA in the feed can enhance the growth performance, immune function and antioxidant capacity of common carp, and improve the health of the intestine and liver. According to the results of this experiment, the optimal addition amount in common carp diets was 400 mg/kg.

Unlocking the potential of N-acetylcysteine: Improving hepatopancreas inflammation, antioxidant capacity and health in common carp (Cyprinus carpio) via the MAPK/NF-κB/Nrf2 signalling pathway.

N-acetylcysteine (NAC) positively contributes to enhancing animal health, regulating inflammation and reducing stress by participating in the synthesis of cysteine, glutathione, and taurine in the body. The present study aims to investigate the effects of dietary different levels of NAC on the morphology, function and physiological state of hepatopancreas in juvenile common carp (Cyprinus carpio). 450 common carps were randomly divided into 5 groups: N1 (basal diet), N2 (1.5 g/kg NAC diet), N3 (3.0 g/kg NAC diet), N4 (4.5 g/kg NAC diet) and N5 (6.0 g/kg NAC diet), and fed for 8 weeks. The results indicated that dietary 3.0-6.0 g/kg NAC reduced hepatopancreas lipid vacuoles and nuclear translocation, and inhibited apoptosis in common carp. Simultaneously, the activities of hepatopancreas alanine aminotransferase and aspartate aminotransferase progressively increased with rising dietary NAC levels. Dietary NAC enhanced the non-specific immune function of common carp, and exerted anti-inflammatory effects by inhibiting the MAPK/NF-κB signaling pathway. Additionally, dietary 3.0-6.0 g/kg NAC significantly improved the antioxidant capacity of common carp, which was associated with enhanced glutathione metabolism, clearance of ROS and the activation of Nrf2 signaling pathway. In summary, NAC has the potential to alleviate inflammation, mitigate oxidative stress and inhibit apoptosis via the MAPK/NF-κB/Nrf2 signaling pathway, thereby improving hepatopancreas function and health of common carp. The current findings provide a theoretical basis for promoting the application of NAC in aquaculture and ecological cultivation of aquatic animals.

Potential protective effects of sodium butyrate on glycinin-induced oxidative stress, inflammatory response, and growth inhibition in Cyprinus carpio.

Investigated mitigating effects of sodium butyrate (SB) on the inflammatory response, oxidative stress, and growth inhibition of common carp (Cyprinus carpio) (2.94 ± 0.2 g) are caused by glycinin. Six isonitrogenous and isoenergetic diets were prepared, in which the basal diet was the control diet and the Gly group diet contained 80 g/kg glycinin, while the remaining 4 diets were supplemented with 0.75, 1.50, 2.25, and 3.00 g/kg SB, respectively. The feeding trial lasted for 8 weeks, and the results indicated that supplementing the diet with 1.50-2.25 g/kg of SB significantly improved feed efficiency and alleviated the growth inhibition induced by glycinin. Hepatopancreas and intestinal protease activities and the content of muscle crude protein were significantly decreased by dietary glycinin, but supplement 1.50-2.25 g/kg SB partially reversed this result. SB (1.50-2.25 g/kg) increased the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the hepatopancreas and reduced the activities of AST and ALT in the serum. Glycinin significantly reduced immune and antioxidant enzyme activities, whereas 1.50-2.25 g/kg SB reversed these adverse effects. Furthermore, compared with the Gly group, supplement 1.50-2.25 g/kg SB eminently up-regulated the TGF-ß and IL-10 mRNA, and down-regulated the IL-1ß, TNF-α, and NF-κB mRNA in hepatopancreas, mid-intestine (MI), and distal intestine (DI). Meanwhile, supplement 1.50-2.25 g/kg SB activated the Keap1-Nrf2-ARE signaling pathway and upregulate CAT, SOD, and HO-1 mRNA expression in hepatopancreas, MI, and DI. Summarily, glycinin induced inflammatory response, and oxidative stress of common carp ultimately decreased the digestive function and growth performance. SB partially mitigated these adverse effects by activating the Keap1-Nrf2-ARE signaling pathway and inhibiting the NF-κB signaling pathway.

Alleviative effect of poly-ß-hydroxybutyrate on lipopolysaccharide-induced oxidative stress, inflammation and cell apoptosis in Cyprinus carpio.

In this study, the alleviative effects of poly-ß-hydroxybutyrate (PHB) in bioflocs on oxidative stress, inflammation and apoptosis of common carp (Cyprinus carpio) induced by lipopolysaccharide (LPS) were evaluated. Common carp were irregularity divided into 5 groups and fed five diets with 0 % (CK), 2 %, 4 %, 6 % and 8 % PHB. After 8-week feeding trial, LPS challenge was executed. Results showed that appropriate level of PHB enhanced serum immune function by reversing LPS-induced the decrease of C3, C4, IgM, AKP, ACP and LZM in serum, alleviated LPS-induced intestinal barrier dysfunction by decreasing the levels of 5-HT, D-LA, ET-1 and DAO in serum, increasing ZO-1, Occludin, Claudin-3 and Claudin-7 mRNA, improving intestinal morphology. Moreover, dietary PHB reversed LPS-induced the decrease of AST and ALT in hepatopancreas, while in serum exhibited the opposite trend. Suitable level of PHB reversed LPS-induced the reduction of GSH-PX, CAT, T-SOD and T-AOC in intestines and hepatopancreas, whereas MDA showed the opposite result. PHB alleviated LPS-induced the decrease of Nrf2, HO-1, CAT, SOD and GSH-PX mRNA, the increase of Keap1 mRNA. Appropriate level of PHB alleviated LPS-induced inflammation and apoptosis by up-regulating TGF-ß, IL-10 and Bcl-2 mRNA, down-regulating NF-κB, TNF-α, IL-6, Bax, Caspase-3, Caspase-8 and Caspase-9 mRNA. Furthermore, PHB inhibited activation of NLRP3 inflammasomes by reducing the levels of NLRP3, Caspase-1, ASC, IL-1ß and IL-18 mRNA and protein. In addition, the increases of dietary PHB linearly and quadratically affected LPS-induced adverse effects on common carp. Summary, this study suggested that appropriate level of dietary PHB alleviated LPS-induced oxidative stress, inflammation, apoptosis and the activation of NLRP3 inflammasome in common carp. And the appropriate level of PHB in common carp diets was 4 %.

A teleost interleukin-16 is implicated in peripheral blood leukocytes recruitment and anti-bacterial immunity.

Interleukin-16 (IL-16), as a lymphocyte chemoattractant cytokine, plays a crucial role in regulating cellular activities and anti-pathogen immunity. In teleost, the information about the antibacterial effect of IL-16 is scarce. In our study, we examined the immune functions of an IL-16 homologue (CsIL-16) from tongue sole Cynoglossus semilaevis. The CsIL-16 precursor (proCsIL-16) is comprised of 1181 amino acid residues, sharing 21.1%-67.3% identities with IL-16 precursor from invertebrate and vertebrate. The C-terminal proCsIL-16 containing two PDZ domains was designated as mature CsIL-16 which was released into the supernatant of peripheral blood leukocytes (PBLs). CsIL-16 was expressed in various tissues and regulated by bacterial invasion. Recombinant CsIL-16 (rCsIL-16), as a homodimer, was able to bind to the membrane of PBLs and played essential roles in regulating chemotaxis and activation of PBLs, which in vitro inhibited intracellular survival of E. tarda. Under in vivo condition, rCsIL-16 could dramatically regulate the induction of inflammatory genes, and suppress the bacterial dissemination in fish tissues. Collectively, our results reveal that CsIL-16 plays positive roles in antibacterial immunity, and provide insights into the immune function of CsIL-16.