表达耐热肠毒素的重组大肠杆菌对7日龄仔猪肠道形态结构及抗氧化功能的影响

试验旨在研究表达耐热肠毒素（STa）的重组大肠杆菌对7日龄仔猪肠道形态结构及抗氧化功能的影响。选取24头7日龄仔猪，随机分在4个日粮处理组，分别为对照组（人工乳），STa组（人工乳+2×10⁹ CFU重组菌LMG194-pBAD-STa），LMG194组（人工乳+2×10⁹ CFU大肠杆菌LMG194），K88组（人工乳+2×10⁹ CFU大肠杆菌K88）。试验第5天进行攻毒，第7天屠宰取样，测量小肠黏膜的绒毛高度和隐窝深度，检测空肠、回肠、结肠及血清中的过氧化氢酶（CAT）、总一氧化氮合成酶（TNOS）与诱导型一氧化氮合酶（iNOS）的活力及血清中丙二醛（MDA）与过氧化氢（H₂O₂）的含量。试验结果表明，与对照组相比，STa组仔猪各肠段绒毛高度均显著降低（P<0.05），十二指肠隐窝深度及绒毛高度与隐窝深度的比值显著降低（P<0.05），十二指肠、空肠、回肠绒毛表面积显著降低（P<0.05）；同时，STa组回肠、结肠CAT活力显著降低，血清、空肠、回肠和结肠中的TNOS活力显著降低（P<0.05），STa组结肠iNOS活力显著降低（P<0.05），STa组血清中的MDA与H₂O₂含量显著提高（P<0.05）。结果显示，表达STa的重组大肠杆菌可导致7日龄仔猪肠道结构损伤和抗氧化能力下降。

Effects of Recombinant E. coli Expressing Heat-stable Enterotoxin on Intestinal Morphology and Antioxidant Capacity in Seven Days old Piglets

This experiment was conducted to investigate the effects of recombinant E.coli expressing heat-stable enterotoxin(STa) on intestinal absorption and barrier function, intestinal morphology and antioxidant capacity of 7 days old piglets. Twenty-four 7 days old piglets were allotted to four treatments:control group (artificial milk), STa group (artificial milk +2×10⁹ CFU E.coli LMG194-pBAD-STa), LMG194 group (artificial milk +2×10⁹ CFU E.coli LMG194), and K88 group (artificial milk +2×10⁹ CFU E.coli K88).The pigs were treated with E.coli on the 5th day and slaughtered on the 7th day. The results showed that, compared with the control group, villus height in jejunum, ileum and duodenum, crypt depth and villus height/crypt depth in duodenum, and small intestine villi surface area were significantly decreased in STa group (P<0.05). The activities of catalase (CAT) in ileum and colon, total nitric oxide synthase (TNOS) in serum, ileum, jejunum and colon, inducible nitric oxide synthase (iNOS) in colon were significantly decreased in STa group (P<0.05). STa group also had a higher levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in serum (P<0.05). These results suggested that recombinant E.coli expressing STa could lead to intestinal injury and oxidative stress of 7 days old piglets.