南瓜多糖对大肠杆菌感染小鼠肠道损伤的保护作用及其机制研究

Protective Effects of Pumpkin Polysaccharide on Intestinal Injury of Mice Infected by Enterotoxigenic Escherichia coli and Its Mechanism

本试验旨在研究南瓜多糖(PP)对大肠杆菌(ETEC)感染小鼠肠道损伤的保护作用及其分子机制。选用40只无特定病原体(SPF)级雄性ICR小鼠,随机分为4组,分别为对照(C)组、ETEC组、PP组及ETEC+PP组,其中C组及ETEC组饲喂基础饲粮,PP组及PP+ETEC组饲喂试验饲粮。试验期共21 d,在第18~20天给小鼠灌服ETEC菌液以建立肠炎模型。试验测定各组小鼠疾病活动指数、脏器指数、血清生化指标、肝脏抗氧化指标、肠道与肝脏组织炎症因子的表达水平。结果表明:PP显著降低小鼠疾病活动指数(P<0.05),极显著降低了肝脏指数和脾脏指数(P<0.01),并抑制血清中谷丙转氨酶(ALT)及谷草转氨酶(AST)活性,但各组之间无显著性差异(P>0.05)。此外,PP极显著提高了小鼠血清中的过氧化氢酶(CAT)活性和总抗氧化能力(T-AOC)(P<0.01),其肝脏中的CAT活性和T-AOC相较于ETEC组无显著性差异(P>0.05)。PP显著降低小鼠肠道中的白细胞介素-6(IL-6)和白细胞介素-1β(IL-1β)的mRNA相对表达量(P<0.05),而对肿瘤坏死因子-α(TNF-α)的mRNA相对表达量无显著性影响(P>0.05);PP显著降低肝脏中IL-6、TNF-α和IL-1β的mRNA相对表达量(P<0.05)。以上结果表明,PP可通过提高小鼠抗氧化机能及抑制炎性反应从而减轻由ETEC肠道炎症引起的机体损伤。

The objective of this study was to investigate the protective effects of pumpkin polysaccharide(PP)on enterotoxigenic Escherichia coli(ETEC)infection in mice and its molecular mechanism.Firstly,40 SPF male ICR mice were randomly divided into 4 groups:control(C)group,ETEC group,PP group and ETEC+PP group,control group and ETEC group were fed a basal diet,and PP group and PP+ETEC group were fed an experimental diet.The experiment lasted for 21 days,and ETEC was administered to mice by gavage to establish the intestinal inflammation model on the 18th to 20th day of the trial period.The disease activity index,organ index,serum biochemical indexes,liver antioxidant activity,and the mRNA relative expression levels of inflammatory factors in intestinal and liver tissues were measured in each group.The results showed that PP significantly decreased the disease activity index(P<0.05)and liver index and spleen index of mice(P<0.01),and inhibited serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)activities,but there was no significant difference between groups(P>0.05).In addition,PP significantly increased the catalase(CAT)activity and total antioxidant capacity(T-AOC)in serum(P<0.01),while the CAT activity and T-AOC in liver had no significant difference between ETEC+PP group and ETEC group(P>0.05).PP significantly reduced the mRNA relative expression levels of interleukin-6(IL-6)and interleukin-1β (IL-1β) (P<0.05)in the intestinal tract of mice,while had no significant effect on the mRNA relative expression levels of tumor necrosis factor-α (TNF-α) (P>0.05);PP significantly reduced the mRNA relative expression levels of IL-6,TNF-α and IL-1β in the liver(P<0.05).The results indicate that PP can reduce the body damage caused by ETEC intestinal inflammation by improving antioxidant function and inhibiting inflammatory response.