National Demonstration Center on Experiment Teaching of Fisheries Science, Shanghai Ocean University, Shanghai, 201306, China; Guangxi Key Laboratory of Marine Natural Products and Combinatorial Biosynthesis Chemistry, Guangxi Beibu Gulf Marine Research Center, Guangxi Academy of Sciences, Nanning, 530007, China; Research Centre of the Agriculture Ministry on Environmental Ecology and Fish Nutrition, Shanghai Ocean University, Shanghai, 20136, China; Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai, 201306, China.
National Demonstration Center on Experiment Teaching of Fisheries Science, Shanghai Ocean University, Shanghai, 201306, China.
Fish Shellfish Immunol. 2020 May;100:109-116. doi: 10.1016/j.fsi.2020.03.015. Epub 2020 Mar 7.
The present study was conducted to explore the influence of dietary carbohydrate on antioxidant capacity and non-specific immunity of hybrid grouper, which would contribute to determine the tolerable dietary carbohydrate content. Seven diets with grade levels of carbohydrate (5.27, 8.95, 11.49, 14.37, 17.78, 20.82 and 23.65%) were fed to triplicate groups of fish for 10 weeks. Results showed that the inclusion of carbohydrate above 11.49% produced significant increased content of hydrogen peroxide (HO) in liver and malondialdehyde (MDA) in both serum and liver. The specific activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (Gpx) and total antioxidative capacity (T-AOC) were significantly elevated with the increase of dietary carbohydrate from 8.95 to 23.65%, which may be associated with the reduced hepatic soluble protein content. However, opposite variation was observed in the expression of antioxidant related genes (SOD1 and Gpx), which was partly caused by the activation of NF-E2-related factor 2 (Nrf2) and inhibition of Kelch-like-ECH-associated protein 1 (Keap1) at the transcriptional level. The immunoglobulin M (lgM) content and activity of lysozyme and CCP in serum significantly depressed when dietary carbohydrate was above 11.49%. The expression of pro-inflammatory cytokines (TNF-α, IL-1β and IL-8) was significantly increased with the increase of dietary carbohydrate from 5.27 to 8.95% and thereafter significantly reduced, which was consistent with the changed expression of toll-like receptor 2 (TLR2) and nuclear factor κΒ (NF-κΒ). In above, high dietary carbohydrate significantly impaired the antioxidant capacity and reduced the non-specific immunity of hybrid grouper, and the tolerable dietary carbohydrate content should not exceed 11.49%.
本研究旨在探讨饲料碳水化合物对杂交石斑鱼抗氧化能力和非特异性免疫的影响，为确定其可耐受的饲料碳水化合物含量提供参考。试验配制了 7 种等氮等能但碳水化合物梯度水平（5.27%、8.95%、11.49%、14.37%、17.78%、20.82%和 23.65%）的实验饲料，连续投喂杂交石斑鱼 10 周。结果表明，饲料中碳水化合物含量超过 11.49%时，鱼肝脏中过氧化氢（HO）和血清及肝脏中丙二醛（MDA）的含量显著增加。随着饲料中碳水化合物从 8.95%增加到 23.65%，肝组织中过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（Gpx）和总抗氧化能力（T-AOC）的比活力显著升高，这可能与肝可溶性蛋白含量降低有关。然而，抗氧化相关基因（SOD1 和 Gpx）的表达却出现相反的变化，这部分是由于转录水平 NF-E2 相关因子 2（Nrf2）的激活和 Kelch 样 ECH 相关蛋白 1（Keap1）的抑制。血清中免疫球蛋白 M（lgM）含量和溶菌酶、C 型凝集素相关蛋白酶（CCP）的活性在饲料碳水化合物含量超过 11.49%时显著降低。随着饲料中碳水化合物从 5.27%增加到 8.95%，促炎细胞因子（TNF-α、IL-1β 和 IL-8）的表达显著增加，此后显著降低，这与 Toll 样受体 2（TLR2）和核因子 κB（NF-κB）表达的变化一致。综上所述，高碳水化合物饲料显著损害了杂交石斑鱼的抗氧化能力，降低了其非特异性免疫力，其可耐受的饲料碳水化合物含量不应超过 11.49%。
