title: Dietary tryptophan modulates intestinal immune response, barrier function, antioxidant status and gene expression of TOR and Nrf2 in young grass carp (Ctenopharyngodon idella).
abstract: The present research evaluated the effects of dietary tryptophan (Trp) on growth performance, intestinal mucosal immune, barrier function and antioxidant capacity and gene expression of young grass carp (Ctenopharyngodon idella). Fish were fed six different experimental diets containing graded levels of Trp at 0.7(control), 1.7, 3.1, 4.0, 5.2 and 6.1 g kg(-1) diet for 8 weeks. The results showed that Trp supplementation significantly enhanced the percent weight gain (PWG), feed intake and feed efficiency (P < 0.05), and decreased the plasma ammonia content (PAC) (P < 0.05). After the 8-week feeding trail, an environmental copper exposure trail was conducted for 4 days. Results from the copper exposure trail showed that dietary Trp enhanced the lysozyme, acid phosphatase activities and complement 3 contents in the intestine of young grass carp (P < 0.05). In addition, Trp supplementation increased the copper/zinc superoxide dismutase (SOD1), glutathione peroxidase (GPx) activities and glutathione contents (P < 0.05), and decreased the protein carbonyl and malondialdehyde contents (P < 0.05). Furthermore, the relative gene expression levels of interleukin 10, transforming growth factor-β1, occludin, zonula occludens 1, claudin-b, -c, and -3, SOD1, GPx and NF-E2-related factor 2 in the intestine were significantly up-regulated with increasing of dietary Trp up to a certain level (P < 0.05). Conversely, the mRNA levels of tumor necrosis factor α, interleukin 8, target of rapamycin, Kelch-like-ECH-associated protein 1, claudin-12 and -15a in the intestine were significantly down-regulated by Trp (P < 0.05). Collectively, appropriate dietary Trp level improves fish growth, intestinal immune response, barrier function and antioxidant status, and regulated the mRNA levels of related signal molecules of young grass carp. Based on the quadratic regression analysis of the PWG and PAC, the dietary Trp requirement of young grass carp (287-699 g) was estimated to be 3.81 g kg(-1) diet (12.7 g kg(-1) protein) and 3.89 g kg(-1) diet (13.0 g kg(-1) protein), respectively.
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China.
authors.forename: Hailang
authors.initials: H
authors.lastname: Wen
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Sichuan, Chengdu 611130, China. Electronic address: fenglin@sicau.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Feng
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Sichuan, Chengdu 611130, China.
authors.forename: Weidan
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Sichuan, Chengdu 611130, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Sichuan, Chengdu 611130, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Li
authors.affiliation: Animal Nutrition Institute, Sichuan Academy of Animal Science, Chengdu 610066, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tang
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Yongan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Animal Nutrition Institute, Sichuan Academy of Animal Science, Chengdu 610066, China.
authors.forename: Shengyao
authors.initials: S
authors.lastname: Kuang
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Sichuan, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Sichuan, Chengdu 611130, China. Electronic address: xqzhouqq@tom.com.
authors.forename: Xiaoqiu
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002347:Carps / Q000235:genetics* / Q000276:immunology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects; D007422:Intestines / Q000187:drug effects / Q000276:immunology; D008969:Molecular Sequence Data; D051267:NF-E2-Related Factor 2 / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D058570:TOR Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D014364:Tryptophan / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D029941:Fish Proteins; D051267:NF-E2-Related Factor 2; D014364:Tryptophan; D058570:TOR Serine-Threonine Kinases
keywords: Antioxidant status; Immune response; Nrf2; Tight junction protein; Tryptophan