Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
Fish Shellfish Immunol. 2018 Mar;74:459-473. doi: 10.1016/j.fsi.2018.01.015. Epub 2018 Jan 12.
The aim of this study was to assess the effects of dietary pyridoxine (PN) deficiency on intestinal antioxidant capacity, cell apoptosis and intercellular tight junction in young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp (231.85 ± 0.63 g) were fed six diets containing graded levels of PN (0.12-7.48 mg/kg diet) for 10 weeks. At the end of the feeding trial, the fish were challenged with Aeromonas hydrophila for 2 weeks. The results showed that compared with the optimal PN level, PN deficiency (1) increased the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl (PC), decreased the activities and mRNA levels of antioxidant enzymes such as copper, zinc superoxide dismutase (CuZnSOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) (P < .05); (2) up-regulated the mRNA levels of cysteinyl aspartic acid-protease-3 (caspase-3), caspase-7, caspase-8, caspase-9, Bcl-2 associated X protein (Bax), apoptotic protease activating factor-1 (Apaf-1) and Fas ligand (FasL), and down-regulated the mRNA levels of inhibitor of apoptosis proteins (IAP), B-cell lymphoma protein-2 (Bcl-2) and myeloid cell leukaemia-1 (Mcl-1) (P < .05); (3) down-regulated the mRNA levels of ZO-1, occludin [only in middle intestine (MI)], claudin-b, claudin-c, claudin-f, claudin-3c, claudin-7a, claudin-7b and claudin-11, and up-regulated the mRNA levels of claudin-12 and claudin-15a (P < .05), which might be partly linked to Kelch-like-ECH-associated protein 1a (Keap1a)/NF-E2-related factor 2 (Nrf2), p38 mitogen-activated protein kinase (p38MAPK) and myosin light chain kinase (MLCK) signalling in the intestines of fish. However, the activities and mRNA levels of MnSOD, the mRNA levels of Keap1b, c-Jun N-terminal protein kinase (JNK) and claudin-15b in three intestinal segments, and the mRNA levels of occludin in the proximal intestine (PI) and distal intestine (DI) were not affected by graded levels of PN. These data indicate that PN deficiency could disturb the intestinal physical barrier function of fish. Additionally, based on the quadratic regression analysis for MDA content and GST activity, the dietary PN requirements for young grass carp were estimated as 4.85 and 5.02 mg/kg diet, respectively.
本研究旨在评估日粮核黄素（PN）缺乏对草鱼幼鱼肠道抗氧化能力、细胞凋亡和细胞间紧密连接的影响。将 540 尾（231.85±0.63）g 的草鱼幼鱼分别投喂 6 种含有不同 PN 水平（0.12-7.48mg/kg 饲料）的饲料 10 周。在喂养试验结束时，用嗜水气单胞菌对鱼进行 2 周攻毒。结果表明：与最佳 PN 水平相比，PN 缺乏（1）增加了活性氧（ROS）、丙二醛（MDA）和蛋白质羰基（PC）的含量，降低了铜锌超氧化物歧化酶（CuZnSOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）、谷胱甘肽-S-转移酶（GST）和谷胱甘肽还原酶（GR）等抗氧化酶的活性和 mRNA 水平（P＜0.05）；（2）上调胱天蛋白酶-3（caspase-3）、caspase-7、caspase-8、caspase-9、Bcl-2 相关 X 蛋白（Bax）、凋亡蛋白酶激活因子-1（Apaf-1）和 Fas 配体（FasL）的 mRNA 水平，下调凋亡抑制蛋白（IAP）、B 细胞淋巴瘤蛋白-2（Bcl-2）和髓样细胞白血病-1（Mcl-1）的 mRNA 水平（P＜0.05）；（3）下调紧密连接蛋白-1（ZO-1）、occludin [仅在中肠（MI）]、claudin-b、claudin-c、claudin-f、claudin-3c、claudin-7a、claudin-7b 和 claudin-11 的 mRNA 水平，上调 claudin-12 和 claudin-15a 的 mRNA 水平（P＜0.05），这可能与肠道中的 Kelch-like-ECH-associated protein 1a（Keap1a）/NF-E2-related factor 2（Nrf2）、p38 丝裂原活化蛋白激酶（p38MAPK）和肌球蛋白轻链激酶（MLCK）信号通路有关。然而，三个肠段的 MnSOD 活性和 mRNA 水平、Keap1b、c-Jun N 末端蛋白激酶（JNK）和 claudin-15b 的 mRNA 水平以及近端肠（PI）和远端肠（DI）的 occludin 的 mRNA 水平不受日粮 PN 水平的影响。这些数据表明，PN 缺乏会干扰鱼类肠道的物理屏障功能。此外，基于 MDA 含量和 GST 活性的二次回归分析，估计草鱼幼鱼对 PN 的需要量分别为 4.85 和 5.02mg/kg 饲料。
