| With the acceleration of large-scale breeding,animal intestinal inflammatory diseases and antibiotic resistance have brought great challenges to the poultry industry,and it is urgent to find"replacement"drugs.Astragalus Polysaccharide(APS)has anti-inflammatory,anti-tumor and immune enhancement effects,and can protect intestinal health.In response to the current frequent occurrence of bacterial enteritis in the poultry industry and the arrival of the era of"restricted resistance".In this study,by observing the effects of APS on the pathology and mucosal immunity of the small intestine of the chicks with enteritis,the effect of APS on the prevention of enteritis in the chicks was evaluated.First of all,this study took SPF chicks as the research object.15 14-day-old SPF chicks were randomly divided into 3 groups,namely the control group(C group),the low-dose lipopolysacharide(Lipopolysacharide,LPS)model group(D_Lgroup)and the high-dose lipopolysaccharide(Lipopolysacharide,LPS)model group(D_Hgroup).In the lipopolysaccharide model group(D_Hgroup),the rats were treated with normal saline,1 mg/kg BW LPS and 2 mg/kg BW LPS respectively.After 3 days of continuous treatment,blood was collected from the heart and sacrificed.The small intestine tissues of the chicks were taken.The HE staining method and q PCR method were used to observe the pathological changes of the intestinal mucosa of the chicks and to detect the changes in the expression of interleukin 1β(IL-1β)and tumor necrosis factorα(TNF-α)in the chicks.The results showed that:Compared with group C,chicks in D_Lgroup were mentally depressed,intestinal mucosal hemorrhage,IL-1βand TNF-αexpression increased significantly(P<0.05),and obvious pathological changes of enteritis appeared;with the increase of LPS dose,The indexes of the chicks in the D_Hgroup were significantly higher than those in the D_Lgroup,suggesting that the chicks were stimulated by oral administration of 2 mg/kg BW LPS,and even the chicks died.Therefore,combining the results of indicators such as chick mental state,small intestine histopathology,and inflammatory factor m RNA expression,it is finally determined that chicks take 1 mg/kg BW LPS orally to establish an enteritis model.Based on the successful establishment of a chick enteritis model,this study further evaluated the effect of APS on the prevention of chick enteritis from the perspective of small intestinal mucosal immunity.Twenty SPF chicks were randomly divided into 4 groups,namely control group(C group),LPS group(L group),APS group(A group)and APS inhibited LPS group(A+L group).In group C,normal saline was taken orally,and the chicks of group A and A+L were fed with APS with drinking water;the chicks of group L and A+L were established intestinal inflammation model.Three days after oral administration of LPS,the patients were weighed,blood was collected from the heart,and the thymus,spleen,bursa of fabric and small intestine tissues were collected.Observe and record the mental status,body weight and immune organ index changes of the chicks in each group;use HE,PAS and toluidine blue staining methods and q PCR methods to observe the pathological changes of the chicks small intestine,the changes in the number of goblet cells and mast cells,and tight junction protein(Occludin-1,Claudin-1 and ZO-1)and SIg A m RNA expression changes.The results showed that the chicks in the A+L group were in better mental state than the L group,and the body weight and immune organ index increased significantly(P<0.05).The chickens in the A group were better than other groups in various indicators.Compared with the L group,the chicks in the A+L group had less intestinal mucosal damage,decreased intestinal epithelial bleeding points,and significantly increased intestinal villi height,crypt depth and V/C ratio(P<0.05).The number of small intestinal goblet cells and mast cells in the A+L group was significantly higher than that in the L group(P<0.05),and the expression of small intestinal tight junction protein and SIg A m RNA were significantly increased(P<0.05).Compared with other groups,the number of goblet cells and mast cells in group A chickens increased significantly,and the expression of tight junction protein and SIg A also increased significantly.The results showed that APS can increase the body weight and immune organ index of the chicks,thereby promoting the development of the immune organs of the chicks;it can protect the integrity of the intestinal mucosa structure,increase the number of goblet cells and mast cells in the small intestine,and promote the expression of tight junction protein and SIg A to enhance the chicks Intestinal mucosal immune function.In summary,the pathological changes of the small intestine and the detection results of the index of goblet cells,tight junction protein and SIg A expression fully prove that APS has a significant effect in preventing chick enteritis.In this experiment,the LPS-induced chick enteritis model was constructed to comprehensively evaluate the application effect of APS in the prevention and control of chick enteritis from the perspective of intestinal mucosal immunity.It not only provides an important experimental basis for the research of poultry inflammation-related diseases,but also clinical"replacement"drugs.Screening and evaluation of the prognosis of poultry intestinal inflammation-related diseases have very important application value. |
