Animal Nutrition Institute, Sichuan Agricultural University, Chengdu611130, People's Republic of China.
Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu611130, People's Republic of China.
Br J Nutr. 2020 Apr 14;123(7):737-755. doi: 10.1017/S0007114519003295. Epub 2019 Dec 13.
The present study investigated the effects of condensed tannins (CT) on intestinal immune function in on-growing grass carp (Ctenopharyngodon idella). A total of 540 healthy grass carp were fed six diets containing different levels of CT (0, 10·00, 20·00, 30·00, 40·00 and 50·00 g/kg diet) for 70 d and then challenged with Aeromonas hydrophila for 14 d. The results showed that, compared with the control group, dietary CT (1) induced intestinal histopathological lesions and aggravated enteritis; (2) decreased lysozyme and acid phosphatase activities, complement 3 (C3), C4 and IgM contents and down-regulated the Hepcidin, liver-expressed antimicrobial peptide (LEAP)-2A, LEAP-2B, Mucin2 and β-defensin-1 mRNA levels in the proximal intestine (PI), mid intestine (MI) and distal intestine (DI) (P < 0·05); (3) down-regulated the mRNA levels of anti-inflammatory cytokines transforming growth factor (TGF)-β1, TGF-β2 (not in MI and DI), IL-4/13A (not IL-4/13B), IL-10 and IL-11 partly correlated with target of rapamycin (TOR) signalling; and (4) up-regulated the mRNA levels of pro-inflammatory cytokines interferon-γ2, IL-1β, IL-6, IL-8 (not in PI), IL-12p35, IL-12p40, IL-15 and IL-17D partly related to NF-κB signalling in the intestine of on-growing grass carp. Overall, the results indicated that CT could impair the intestinal immune function, and its potential regulation mechanisms were partly associated with the TOR and NF-κB signalling pathways. Finally, based on the percentage weight gain and enteritis morbidity, the maximum allowable levels of CT for on-growing grass carp (232·22-890·11 g) were estimated to be 18·6 and 17·4 g/kg diet, respectively.
本研究探讨了单宁（CT）对生长草鱼（Ctenopharyngodon idella）肠道免疫功能的影响。将 540 条健康草鱼分别投喂 6 种含不同水平 CT（0、10.00、20.00、30.00、40.00 和 50.00 g/kg 饲料）的饲料 70 d，然后用嗜水气单胞菌攻毒 14 d。结果表明，与对照组相比，饲粮 CT（1）导致肠道组织病理学病变，肠炎加重；（2）降低了溶菌酶和酸性磷酸酶活性、补体 3（C3）、C4 和 IgM 含量，并下调了近端肠（PI）、中肠（MI）和远端肠（DI）中 Hepcidin、肝表达抗菌肽（LEAP）-2A、LEAP-2B、Mucin2 和β-防御素-1 mRNA 水平（P<0.05）；（3）下调部分与雷帕霉素靶蛋白（TOR）信号相关的抗炎细胞因子转化生长因子（TGF）-β1、TGF-β2（MI 和 DI 中无）、IL-4/13A（不是 IL-4/13B）、IL-10 和 IL-11 mRNA 水平；（4）上调部分与 NF-κB 信号相关的促炎细胞因子干扰素-γ2、IL-1β、IL-6、IL-8（PI 中无）、IL-12p35、IL-12p40、IL-15 和 IL-17D mRNA 水平。总之，CT 可损害草鱼肠道免疫功能，其潜在调控机制部分与 TOR 和 NF-κB 信号通路相关。最后，基于增重百分率和肠炎发病率，估计生长草鱼 CT 的最大允许水平（232.22-890.11 g）分别为 18.6 和 17.4 g/kg 饲料。
