表达Ⅰ型耐热肠毒素的重组大肠杆菌对7日龄仔猪小肠功能的影响

试验旨在研究表达Ⅰ型耐热肠毒素(STa)的重组大肠杆菌对7日龄仔猪小肠功能的影响。选取24头7日龄仔猪,随机分为4个处理组,分别为对照组、STa组、LMG194组和K88组。整个试验期间均以人工乳饲喂,预饲期4d,试验第5天进行攻毒,STa组、LMG194组及K88组分别在早晚两次口服灌喂2×109 CFU大肠杆菌LMG194-pBAD-STa、LMG194和K88,对照组灌服等量生理盐水,试验第7天早上各组灌服D-木糖并采血,屠宰并取空肠、回肠组织样品,测量仔猪血常规指标、血浆D-木糖含量及二胺氧化酶(DAO)活力,以及吸收与转运相关基因与蛋白表达量。结果显示,与对照组相比,STa组仔猪血液中中性粒细胞、中性粒细胞比率显著降低(P<0.05),淋巴细胞比率显著升高(P<0.05),LMG194组与K88组仔猪血液中中性粒细胞比率显著降低(P<0.05),淋巴细胞比率显著升高(P<0.05);STa组与K88组仔猪血浆D-木糖含量显著降低(P<0.05);STa组、LMG194组及K88组血浆DAO活力显著升高(P<0.05);STa组与LMG194组空肠AQP8、AQP10、KCNJ13和b0,+AT基因表达量均显著降低(P<0.05),K88组空肠AQP8、AQP10基因表达量显著升高(P<0.05);STa组回肠AQP8基因表达量显著降低(P<0.05),AQP10、SGLT-1基因表达量显著升高(P<0.05),LMG194组、K88组AQP8基因表达量显著升高(P<0.05),K88组AQP10、KCNJ13、b0,+AT、SGLT-1基因表达量显著降低(P<0.05);STa组、LMG194组及K88组空肠HSP70蛋白的表达量显著升高(P<0.05)。以上结果表明,表达Ⅰ型耐热肠毒素的重组大肠杆菌可导致7日龄仔猪小肠产生炎症,吸收与转运能力下降。

Effects of Recombinant E.coli Expressing Heat-stable Enterotoxin on Small Intestinal Function in 7 Days Old Piglets

This experiment was aimed to investigate the effects of recombinant E.coli expressing heat-stable enterotoxin(STa) on small intestinal function in 7 days old piglets.Twenty-four 7 days old piglets were randomly divided into four treatments of control,STa,LMG194 and K88 groups,which were fed with artificial milk throughout the experiment.Pre-feeding period was 4 d.STa,LMG194 and K88 groups were orally administered with 2×10⁹ CFU E.coli LMG194-pBAD-STa,LMG194 and K88 twice in the morning and evening on the 5th day,respectively.The control group was given the same amount of normal saline.On the 7th morning of the experiment,each group was given D-xylose and blood was collected.Then they were slaughtered and the samples of jejunum and ileum tissue were collected,blood routine indicators,the content of plasma D-xylose,the activity of diamine oxidase (DAO),and the expression of absorption and transport related genes and protein were measured.The results showed that compared with control group,the neutrophils and neutrophil ratio were significantly decreased in blood,the lymphocyte ratio was significantly increased in STa group (P<0.05),the neutrophil ratio was significantly decreased in blood,the lymphocyte ratio was significantly increased in LMG194 and K88 groups (P<0.05);The content of D-xylose in plasma was significantly decreased in STa and K88 groups (P<0.05);The activity of DAO in plasma was significantly increased in STa,LMG194 and K88 groups (P<0.05).In jejunum,compared with control group,the expression levels of AQP8, AQP10,KCNJ13 and b^0,+AT genes were significantly reduced in STa and LMG194 groups (P<0.05),the expression levels of AQP8 and AQP10 genes were significantly increased in K88 group (P<0.05).In ileum,the expression level of AQP8 gene was significantly reduced,the expression levels of AQP10 and SGLT-1 genes were significantly increased in STa group (P<0.05).The expression level of AQP8 gene was significantly increased in LMG194 and K88 groups (P<0.05),the expression levels of AQP10,KCNJ13,b^0,+AT and SGLT-1 genes were significantly reduced in K88 group (P<0.05).The relative expression level of HSP70 was significantly increased in STa,LMG194 and K88 groups (P<0.05).These results suggested that recombinant E.coli expressing STa could lead to inflammation in small intestinal,absorption and transfer capacity were decreased in 7 days old piglets.