【作者】 李晓芳；

【导师】 唐立；

【作者基本信息】 大连医科大学 ， 病原生物学， 2009， 硕士

【摘要】 目的:1.以肠道十四种优势菌群变化情况为依据,建立轻度菌群失衡和重度菌群失衡小鼠模型。2.研究肠道菌群失衡对小鼠肠粘膜机械屏障的影响,探讨优势菌群与肠道粘膜屏障的相互作用机制。方法:1.采用抗生素头孢曲松钠灌胃的方式建立小鼠肠道菌群失衡模型。以头孢曲松钠终浓度5g/kg/d的剂量,连续8天,取盲肠内容物进行肠道菌群分析,建立小鼠轻度菌群失衡模型;以头孢曲松钠终浓度8g/kg/d的剂量,连续8天,分析肠道菌群,建立小鼠重度菌群失衡模型。2.利用HE染色及电镜技术观察正常组、轻度菌群失衡组、重度菌群失衡组小鼠肠道粘膜绒毛形态变化,用ELISA法检测肠粘膜分泌性免疫球蛋白SIgA分泌量变化,RT-PCR技术及免疫组化法检测肠粘膜粘液素Mucin2、Mucin3,防御素含量的变化。结果:1.头孢曲松钠5g/kg/d,连续8天灌胃,肠道优势菌群显著下降,建立轻度菌群失衡小鼠模型;头孢曲松钠8g/kg/d,连续8天灌胃,肠道优势菌群的数量几乎降至零,建立重度菌群失衡小鼠模型。2.菌群失衡小鼠肠粘膜绒毛出现肿胀、断裂,绒毛顶端肠上皮细胞坏死、脱落,细胞间间隙增宽,胞浆内出现空泡结构,粘膜及粘膜下层有淋巴细胞浸润,重度菌群失衡与轻度菌群失衡小鼠相比较绒毛结构受损加重。3.菌群失衡小鼠小肠段肠粘膜分泌性免疫球蛋白SIgA分泌水平下降,重度菌群失衡组与正常组比较下降呈显著变化(P<0.05),与轻度菌群失衡组相比下降明显。4.菌群失衡小鼠粘液层中的粘液素Mucin2、Mucin3、防御素在mRNA水平的表达与正常小鼠相比明显增强,在杯状细胞胞浆内Mucin2蛋白阳性表达增强,且重度菌群失衡组与轻度菌群失衡组小鼠比较,粘液素Mucin2、Mucin3、防御素增强明显。结论:抗生素干扰肠道优势菌群,建立肠道菌群失衡模型。菌群失衡可导致肠道机械屏障粘膜绒毛结构受损,肠粘膜免疫水平下降,SIgA分泌量随菌群失衡程度呈下降趋势,同时引起粘液层中粘液素和防御素分泌量增加。更多还原

【Abstract】 Objective:1. Establish different dysbacteria mice model based on intestinal dominant flora changes.2. Observe the changes of intestinal physical barrier of dysbacteria mice, to explore the interaction of intestinal dominant flora and intestinal mucosal immunity.Methods:1. Mice were dealed by intragastic administration of ceftriaxone sodium, according to the analysis of cecum flora, 5g/kg/d doses, 8 days to establish light-dysbacteria model ; 8g/kg/d doses, 8 days to establish heavy-dysbacteria model.2. Morphological changes of gastrointestinal mucosa were observed by optical microscope and transmission electron microscope, secreted IgA in intestinal mucosa were detected by ELISA, mucin2、mucin3 and defensin was detected by RT-PCR and immunohistochemical method.Results:1. In light-dysbacteria mice, intestinal dominant flora were decreased significantly, and in heavy-dysbacteria mice, intestinal dominant flora were almost dropped to naught.2. In dysbacteria mice, intestinal mucosal villus were damaged, villus were swell and breakage, the gaps of intestinal epithelial cells were wider, cells showed necrosis and vacuoles, lymph cells infiltrated mucosa layer, heavy-dysbacteria mice were damaged much better than light-dysbacteria mice. 3. Compared with normal mice, mucosal SIgA level was decreased in dysbacteria mice, the heavy-dysbacteria mice SIgA level were lower than light-dysbacteria mice.4. Compared with normal mice, the levels of mucin2, mucin3 and defensin were higher in dysbacteria mice, the heavy-dysbacteria mice higher than light-dysbacteria mice.Conclusion: Antibiotics of ceftriaxone sodium can inhibit and kill intestinal dominant flora; In dysbacteria mice, intestinal villus were damaged, the level of intestinal mucosal immunity was decreased, SIgA secretory volume was downtrend followed by dysbacteria degree; intestinal mucin and defensin levels were increased.更多还原