| Changes of small intestinal mucosal immune of rabbit colibacillosis and comparison oftreatment efficiency were studied. Forty healthy weaning rabbits divided into4groups.Control group was established by intraperitoneal injection of2ml saline. Escherichia coliinfection group was established by intraperitoneal injection of2ml E.coli. Gentamicintreatment group was established by intraperitoneal injection of2ml E.coli, the day after theinjection of bacteria intramuscular injection of gentamicin0.5ml/only for three consecutivedays. Lactobacillus treatment group was established by intraperitoneal injection of2ml E.coli,symptoms after oral lactobacillus1for three consecutive days. The rabbits in each group werekilled every other day, endotoxin was detected, the distribution and change of IEL,somatostatin(SS)-positive cells,5-HT-positive cells, mast cells and goblet cells in duodenumand jejunum of rabbits were studied.H.E staining method was adopted to study the change of mucosa thickness, crypt depthand villus length in rabbit small intestinal. The result showed that the mucosa thickness, villuslength and ratio of villus length and crypt depth in Escherichia coli infection group smallintestinal were notable decreased at3day. Under the SEM, intestinal villi, microvillus and theepithelial cells were appeared clutter. Lactobacillus treatment group and Gentamicin treatmentgroup were lighter.H.E staining method was used to study the change of IEL in rabbit small intestinal. Theresult showed that the rabbit intestinal IEL increase after injection of E.coli. The number ofIEL cells in Escherichia coli infection group was increased very significantly（P<0.01）compared to control group, comparing to gentamicin treatment group and lactobacillustreatment group the number of IEL cells in Escherichia coli infection group was increasednotably（P<0.05）, the number of IEL cells in gentamicin treatment group and lactobacillustreatment group was increased notably（P<0.05）compared to control group at3day. At5day,the number of IEL cells in duodenum of Escherichia coli infection group was increasednotably（P<0.05）compared to control group, comparing to control group the number of IEL cells in gentamicin treatment group and lactobacillus treatment group was no significantdifference（P>0.05）.The changes of the number of SS-positive cells in rabbit small intestinal were studied bySABC immunohistochemistry. The result showed that the rabbit intestinal SS-positive cellsincrease after injection of E.coli. At3day, the number of SS-positive cells in Escherichia coliinfection group was increased very significantly（P<0.01） compared to control group, thenumber of SS-positive cells in duodenum of Escherichia coli infection group was increasednotably（P<0.05）compared to gentamicin treatment group and lactobacillus treatment group,the number of SS-positive cells in jejunum of Escherichia coli infection group was increasednotably（P<0.05）compared to lactobacillus treatment group. The number of SS-positive cellsin duodenum of Escherichia coli infection group was increased notably（P<0.05）compared tocontrol group, comparing to control group the number of SS-positive cells in gentamicintreatment group and lactobacillus treatment group was no significant difference（P>0.05） at5day.The changes of the number of5-HT-positive cells in rabbit small intestinal were studiedby SABC immunohistochemistry. At3day, the number of5-HT-positive cells in Escherichiacoli infection group was increased notably（P<0.05）compared to control group, the number of5-HT-positive cells in duodenum of Escherichia coli infection group was increased notably（P<0.05）compared to gentamicin treatment group and lactobacillus treatment group, thenumber of5-HT-positive cells in jejunum of Escherichia coli infection group was increasednotably（P<0.05）compared to lactobacillus treatment group, the number of5-HT-positivecells in gentamicin treatment group was increased notabl（yP<0.05）compared to control group.The number of5-HT-positive cells in each group was no significant difference（P>0.05）at5day.Toluidine blue staining method was used to study the change of mast cells number inrabbit small intestinal. The result showed that the number of mast cells in Escherichia coliinfection group was reduced very significantly （P<0.01） compared to control group,comparing to control group the number of mast cells in gentamicin treatment group andlactobacillus treatment group was reduced notably（P<0.05）at3day. At5day, the number ofmast cells in Escherichia coli infection group was reduced notably（P<0.05）compared to control group, the number of mast cells in duodenum of Escherichia coli infection group wasreduced notably（P<0.05）compared to gentamicin treatment group and lactobacillus treatmentgroup, comparing to control group the number of mast cells in gentamicin treatment groupand lactobacillus treatment group was no significant difference（P>0.05）.The changes of the number of goblet cells in rabbit small intestinal were studied by PAS.The result showed that the number of goblet cells in duodenum of Escherichia coli infectiongroup was increased notably（P<0.05）compared to control group at1day. At3day,comparing to control group the number of goblet cells in Escherichia coli infection group wasincreased very significantly（P<0.01）, the number of goblet cells in duodenum of Escherichiacoli infection group was increased notably（P<0.05）compared to gentamicin treatment groupand lactobacillus treatment group, comparing to control group the number of goblet cells ingentamicin treatment group was increased notably（P<0.05）. the number of goblet cells induodenum of Escherichia coli infection group was increased notably（P<0.05）compared tocontrol group, the number of goblet cells in gentamicin treatment group and lactobacillustreatment group was no significant difference（P>0.05）at5day.The changes of endotoxin in rabbit blood were studied by endpoint chromogenicsubstrate method. The result showed that endotoxin in rabbit blood of Escherichia coliinfection group was increased compared to control group after injection of E.coli at1day, at5day reached a peak, returned to normal levels at7day.The results suggested that the changes of IEL, goblet cells, mast cells,5-HT positivecells and SS positive cells in the small intestine can be caused by intraperitoneal injection ofE.coli. causing muscocal immunity. Structural changes of the small intestinal mucosa and theformation of toxemia can be caused by E.coli, with morphology and structure of the intestinalvilli length and mucosa thickness increased rabbit recovered gradually.Lactolin andgentamicin can significantly preventive rabbit diarrhea infected by E.coli, the effect oflactobacillus treatment group was better than gentamicin treatment group in the clinicalsymptoms were improved. |
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