肌醇对嗜水气单胞菌致生长期草鱼头肾和脾脏氧化损伤的保护作用

Protective effect of myo-inositol on oxidative damage of head kidney and spleen in juvenile grass carp (Ctenopharyngodon idella) induced by Aeromonas hydrophila

摘要:

本实验探索了肌醇对嗜水气单胞菌致生长期草鱼头肾和脾脏氧化损伤的保护作用。实验选取平均体质量（221.83±0.84） g的草鱼540尾，随机分为6组，每组3个重复，分别饲喂含不同水平肌醇[27.0（基础饲料组，未添加肌醇）、137.9、286.8、438.6、587.7和737.3 mg/kg]的饲料10周。随后经腹腔注射嗜水气单胞菌进行14 d攻毒实验。结果显示，嗜水气单胞菌注射后，与基础饲料（未添加肌醇）组相比，饲料中适宜水平肌醇组生长期草鱼头肾和脾脏活性氧（ROS）、丙二醛（MDA）和蛋白质羰基（PC）含量显著降低，而超氧化物歧化酶（SOD/CuZn-SOD和MnSOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx/GPx1a、GPx1b、GPx4a和GPx4b）、谷胱甘肽S-转移酶（GST/GSTP1、GSTP2、GSTO1和GSTO2）和谷胱甘肽还原酶（GR）活性及mRNA水平，谷胱甘肽（GSH）含量显著提高。此外，饲料中适宜水平肌醇上调了嗜水气单胞菌注射后生长期草鱼头肾和脾脏核因子E2相关因子2（Nrf2）mRNA和蛋白水平，下调了Kelch样环氧氯丙烷相关蛋白1（Keap1）a和b mRNA水平。研究表明，饲料中适宜水平肌醇可激活鱼类头肾和脾脏Nrf2信号途径，提高其抗氧化能力，增强抵抗嗜水气单胞菌致头肾和脾脏氧化损伤的能力。此外，以嗜水气单胞菌注射后生长期草鱼头肾和脾脏ROS含量为标识，生长期草鱼肌醇需要量分别为452.1和449.0 mg/kg。

Abstract:

This study investigated the protective effect of myo-inositol on oxidative damage of head kidney and spleen in juvenile grass carp (Ctenopharyngodon idella) induced by Aeromonas hydrophila. A total of 540 C. idella [(221.83±0.84) g] were fed six diets with graded levels of myo-inositol [27.0(unsupplemented), 137.9, 286.8, 438.6, 587.7, 737.3 mg/kg] for 10 weeks. Subsequently, a challenge test was conducted by injection of A. hydrophila and the survival rates recorded for 14 days. The results indicated that compared with myo-inositol deficiency (basal diet, unsupplemented), optimal myo-inositol supplementation decreased reactive oxygen species (ROS), malondialdehyde (MDA), and protein carbonyl contents, and increased the activities and mRNA levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferased and glutathione reductase, and contents of glutathione in the head kidney and spleen after injection of A. hydrophila. Meanwhile, compared with myo-inositol deficiency (basal diet, unsupplemented), optimal myo-inositol supplementation up-regulated NF-E2-related factor 2 (Nrf2) mRNA and protein levels, and down-regulated Kelch-like ECH-associated protein-1 (Keap1) a and b mRNA levels in the head kidney and spleen after injection of A. hydrophila. These results suggested that optimal myo-inositol supplementation could protect fish head kidney and spleen structural integrity through increased antioxidative ability after injection of A. hydrophila. Finally, based on the antioxidant indices ROS content in the head kidney and spleen after injection of A. hydrophila, the myo-inositol requirement for juvenile C. idella was estimated to be 452.1 and 449.0 mg/kg diet, respectively.