Effects Of Salmonella On Proliferation And Apoptosis Of Chicken EGCs And Intervention Of Probiotics

Objective:Salmonellosis is a kind of infectious disease caused by different species of Salmonella infection,among which the infection of chicks is the most serious,bringing serious economic losses to the poultry industry every year.Salmonella invades the intestinal tract of chickens and causes damage to intestinal and small intestinal villi.While probiotics for the body,have a variety of probiotic function,such as increase the thickness of intestinal mucus layer,inhibit the invasion of pathogens into the intestinal tract,etc.The aim of this study was to investigate the effects of Salmonella infection on the proliferation and apoptosis of enteric glial cells(EGCs)in chicks,and the inhibitory effect of probiotics on Salmonella,so as to provide reference for the prevention of salmonellosis in chicks.Methods:A total of 150 healthy one-day-old chicks were random Ly divided into 3 groups,with 50 chicks in each group,which were divided into control group,probiotics group and infection group.The control group was fed the basal diet.In the probiotic group,probiotics(1g/kg diet)was added to the diet until three-day-old,and 1m L salmonella solution(1×10~8CFU/m L)was given to each chick until ten-day-old.When the chicks in the infection group were raised to ten-day-old,they were fed with Salmonella solution(1×10~8CFU/m L,1m L).On the 1st and 5th day after more than half of the chicks in the infection group had diarrhea and other clinical symptoms,five chicks in each group were random Ly selected and slaughtered to take small intestinal tissue samples for Holzer staining,ELISA test and immunohistochemistry test.Results:1.The results of Holzer staining showed that EGCs in the control group and probiotic group were evenly distributed in the mucosa layer and submucosa layer,while those in the infection group were mainly distributed in the submucosa layer,linearly distributed in the lamina propria of the mucosa,and sporadically distributed in the muscular layer.The number of EGCs in duodenum,jejunum and ileum of infected chicks was significantly lower than that of probiotic group and control group(P<0.05);The number of EGCs in the control group was higher than that in the probiotic group(P<0.05).2.ELISA results showed that the content of NGF in the small intestine of infected chicks was significantly higher than that of control group and probiotic group(P<0.05);The content of NGF in probiotic group was higher than that in control group(P<0.05).The content of Caspase-3 in the small intestine of infected chicks was significantly higher than that of control group and probiotic group(P<0.05);The content of Caspase-3 in probiotic group was significantly higher than that in control group(P<0.05).3.The results of immunohistochemistry showed that Brd U was mainly expressed in the top of intestinal villi and submucosa layer in the small intestine of control chicks;In the probiotic group,Brd U was mainly expressed in the lamina propria of intestinal villi,intestinal gland,mucosal epithelium and submucosa layer;In the infection group,Brd U was mainly expressed in mucosal epithelium,intestinal crypt and lamina propria of intestinal villi;The average optical density of the infected group was significantly lower than that of the other two groups(P<0.05).In the small intestine of the control group,Caspase-3 was mainly expressed in the lamina propria of intestinal villi,intestinal gland and mucosal epithelium;In the probiotic group,Caspase-3 was mainly expressed in the lamina propria of intestinal villi,intestinal crypt,mucosal epithelium and submucosa layer;In the infection group,Caspase-3 was mainly expressed in submucosa layer,intestinal crypt and lamina propria of intestinal villi;The average optical density of the infected group was significantly higher than that of the other two groups(P<0.05).Conclusion:Salmonella causes diarrhea in chicks,which leads to pathological changes in the mucosal structure of the small intestine,intestinal villi injury,and inflammation.Compound probiotics can strengthen the resistance to Salmonella by regulating the intestinal flora.Salmonella infection leads to the increase of NGF secreted by EGCs in the small intestine of chicks and the expression of a large number of apoptotic proteins,which inhibits the proliferation of intestinal cells.Probiotics can protect EGCs,reduce the secretion of NGF,and inhibit the abnormal apoptosis of intestinal cells to a certain extent.