关键词: 敌草快, 氧化损伤, Nrf2/HO-1信号通路, 炎症反应

Abstract:

The aim of this study was to establish a model of oxidative damage induced by diquat in broilers and to preliminarily reveal its molecular mechanism. A total of 160 1-day-old broilers were randomly divided into four groups: control group (C), low-dose group (T1), medium-dose group (T2) and high-dose group (T3), 4 replicates per group, 10 replicates each. Five chickens were sampled in each replicate at the 16^th(the first stage), and the remaining five chickens were sampled at 37^th (the second stage) day of age, broilers were weighed, the average body weight of each group was calculated, and diquat was injected intraperitoneally. The T1, T2 and T3 groups were intraperitoneally injected with 5, 10, and 20 mg·kg^-1 of diquat, respectively, and the control group was injected with the corresponding dose of normal saline. The day and the fifth day after the two injections, two broilers were randomly taken from each replicate and blood collection and sampling were conducted. The results showed that after two injections of diquat, compared with the control group, 1) The broilers in the experimental groups were depressed and drank less water and eaten less, 2 broilers in the T3 group died at 6 h after each injection, and the body weight of broilers in the experimental groups were extremely significant reduced at 72 h and 96 h after each injection (P < 0.01); 2) The serum activity of diamine oxidase (DAO), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the T2 and T3 groups were extremely significant increased (P < 0.01); 3) The serum activity of glutathione peroxidase (GSH-Px) in the T2 and T3 groups were extremely significant decreased (P < 0.01), and the serum levels of malondialdehyde (MDA) were extremely significant increased (P < 0.01). The serum activity of superoxide dismutase (SOD) in the T3 group after the second infection was significantly decreased (P < 0.05); 4) The serum contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in each experimental group were extremely significant increased (P < 0.01); 5) In the experimental groups, inflammatory cell infiltration was present, some hepatocytes were vacuolated, cytoplasmic was obvious laxity, and the villi loss of each intestinal segment was serious; Histological scores showed that the liver and small intestine scores in both the T2 and T3 groups were extremely significant higher than control group(P < 0.01), and except the histological score of duodenum at the second stage, there was no significant difference between the T1 group and the control group; 6) The mRNA expressions of ZO-1 and OCLDN in the liver and jejunum of broilers in each experimental group were extremely significant decreased(P < 0.01); 7) The mRNA expression of HO-1 in the liver of T2 group was significantly lower than T1 group (P < 0.05); The mRNA expressions of Nrf2 and HO-1 in jejunum of T2 and T3 groups were extremely significant lower than T1 group(P < 0.01). In summary, this study successfully established a model of oxidative damage induced by diquat in broilers, and the injection dose of 10 mg·kg^-1 was the most appropriate to establish the oxidative damage model, and it was found that diquat may induce the production of inflammation-related factors and inhibit the expression of antioxidant enzymes through the Nrf2/HO-1 signaling pathway, causing intestinal barrier damage in broilers, thereby causing inflammatory response in broilers.

Key words: diquat, oxidative damage, Nrf2/HO-1 signaling pathway, inflammatory response