| Deoxynivalenol(DON),also known as vomiting toxin,is widely present in grain-based foods and feeds and is one of the most widely distributed and most contaminated mycotoxins in the world.DON can cause animal growth and development inhibition,malnutrition,immune dysfunction,and even cause shock and death,which not only seriously harms human and animal health,but also brings huge economic losses to the breeding industry.In recent years,with the rapid development of rabbit breeding industrialization,wheat bran and corn by-products are widely used as raw materials in rabbit pellet feed,increasing the risk of DON pollution.Domestic and foreign researches on DON are mainly focused on pigs and poultry,but little research on rabbits,especially for weaning rabbits.Therefore,the purpose of this experiment is to explore the effects of different doses of DON on the metabolism,intestinal barrier and inflammatory factors of weaned rabbits.Forty-five weaned rabbits were selected in the experiment(no difference in initial weight,879.79±17.62g),randomly divided into 3 groups,namely group A(control group),group B(low-dose addition group,0.5mg/kg·BW DON)Group C(high-dose addition group,1.5mg/kg·BW DON),the total feeding period was 31 days,of which the pre-feeding period was 7 days.During the formal test period,the test rabbits were inoculated and ingested every two days,and a total of 12 infusions were performed.Six test rabbits were randomly selected from each group on the 8th,16 d and 24 d after the first exposure.Serums were collected from the ear vein continuously for 0h(before infusion)and 1h,2h,3h,4h and 6h after infusion.The content of blood in the young rabbits,and the serum biochemical indicators and inflammatory factors at 24 h 0h;during the test,the stool and urine samples of the rabbits were collected to detect the content of DON and DOM-1;after the feeding test,the test Samples of rabbit duodenum,jejunum and ileum,part of the sample was used for histomorphological observation,and the other part was used for the detection of mRNA and protein data.The test results show that:(1)Animal feeding test results show that,compared with group A,the average daily gain of ADG in group C is significantly reduced after DON infusion(P <0.05),and the feed weight ratio of group B and C is F/G Significantly increased(P<0.05).(2)Serum test results showed that the concentration of some biochemical indicators,inflammatory factors and immunoglobulins in the serum of the test rabbits changed significantly compared with the control group,and the degree of change in the DON high-dose group was the most significant.(3)The results of LC-MS/MS showed that the content of DON in the serum of test rabbits increased rapidly after DON was infused,and decreased after reaching the peak at 2h,and was close to the concentration before infusion at6h;The concentrations of DON and DOM-1 were significantly higher than those of the control group(P<0.05),and cumulative effects appeared with the extension of the test period.(4)Histomorphological observation results showed that compared with the control,the villi epithelium of each part of the small intestine in the test group fell off,the length of the villi decreased,the crypts thickened,the number of villi decreased,the branch hypoplasia,the density of goblet cells increased,and the microvilli atrophy of the small intestine Short,and the damage of intestinal tissue structure in the DON high-dose group was the most serious;(5)ELISA,qRT-PCR,WB and immunohistochemical results showed that IL-1β,IL-2,IL-6.The content of IL-8 in the small intestine(duodenum,jejunum and ileum),mRNA expression level,protein expression level and the distribution of immunopositive substances were significantly increased compared with the control group,(6)The main nodes of the signal pathway The protein research results show that the DON high and low dose groups of rabbits p38-ERK1/2 signaling pathway upstream signaling factors PKR,Hck mRNA in the small intestine(duodenum,jejunum and ileum)mRNA expression level,protein expression,And the expression levels of main node protein p38,ERK1/2 mRNA,protein expression and the distribution of immunopositive substances were significantly increased compared with the control group.In summary,DON is metabolized very quickly in the blood of weaned rabbits,and is mainly excreted with urine and feces.Ingestion of DON can destroy the integrity of theintestinal barrier of weaned rabbits,change the distribution and expression of some inflammatory factors,induce the expression of upstream signaling factors PKR and Hck,and activate p38 and ERK1/2 signaling pathways.Dose-dependent.The results of this study will provide a scientific basis for the clinical monitoring of DON and the study of its mechanism of action. |
