Dietary curcumin alleviates intestinal damage induced by ochratoxin A in juvenile grass carp(Ctenopharyngodon idella):Necroptosis and inflammatory responses

Ochratoxin A(OTA)is one of the most common pollutants in aquatic feed.As a first line of defense,intestinal barriers could be utilized against OTA in order to prevent disorders.Natural product supplementation is one of the most popular strategies to alleviate toxicity induced by mycotoxins,but there is a lack of knowledge about how it functions in the teleost intestine.In this study,720 juvenile grass carp of about 11 g were selected and four treatment groups(control group,OTA group,curcumin[Cur]group,and OTA+Cur group)were set up to conduct a 60-day growth test.After the test,the growth performance and intestinal health related indexes of grass carp were investigated.The addition of dietary Cur could have the following main results:(1)inhibit absorption and promote efflux transporters mRNA expression,reducing the residuals of OTA,(2)decrease oxidative stress by reducing oxidative damage and enhancing the expression of antioxidant enzymes,(3)promote mitochondrial fusion proteins to inhibit the expression of mitotic proteins and mitochondrial autophagy proteins and enhance mitochondrial function,(4)reduce necroptosis-related gene expression through inhibiting the tumor necrotic factor receptor-interacting protein kinase/mixed lineage kinase domain-like pathway,(5)reduce the expression of pro-inflammatory factors by inhibiting the Toll-like receptor 4/nuclear factor-κB signaling pathway to alleviate the intestinal inflammatory response.In summary,the results suggested that Cur could alleviate OTA-induced intestinal damage by enhancing antioxidant capacity and mitochondrial function as well as reducing necroptosis and inflammation in the grass carp intestine.This study provided a theoretical basis and production implications for dietary Cur that could improve growth performance and alleviate the intestinal damage induced by OTA in fish.

Dietary copper improves intestinal structural integrity in juvenile grass carp(Ctenopharyngodon idella)probably related to its increased intestinal antioxidant capacity and apical junction complex

This research evaluated the effects of copper(Cu)on intestinal antioxidant capacity and apical junctional complex(AJC)in juvenile grass carp.A total of 1080 healthy juvenile grass carp(11.16±0.01 g)were fed six diets including different dosages of Cu,namely 0,2,4,6,8 mg/kg(Cu citrate[CuCit]as Cu source)and 3 mg/kg(CuSO4·5H2O as Cu source).The trial lasted for 9 weeks.The findings revealed that dietary optimal Cu supplementation(2.2 to 4.1 mg/kg)promoted intestinal growth,including intestinal length,intestinal length index,intestinal weight,and intestinal somatic index(P 0.05).On the other hand,optimal Cu increased intestinal tight junction(TJ)proteins(except for claudin 15b)and adherens junction(AJ)proteins(E-cadherin,α-catenin,β-catenin,nectin and afadin)mRNA levels(P<0.05),which could be connected to the signaling pathway formed by the Ras homolog gene family,member A(RhoA),Rho-associated kinase(ROCK),and myosin light chain kinase(MLCK).Finally,based on serum indicator D-lactate and intestinal oxidative damage index(ROS),Cu requirement(CuCit as Cu source)for juvenile grass carp from initial weight to final weight(from 11 to 173 g)was determined to be 4.14 and 4.12 mg/kg diet,respectively.This work may provide a theoretical foundation for identifying putative Cu regulation pathways on fish intestinal health.