Abstract: Background　Recent rapid development of sequencing technology improves the understanding of the close association between gut floras and an increasing number of diseases. The relationship of gut floras with diabetes，a primary disease threatening human health，has attracted extensively attention. Objective　To explore the changes of gut floras in a rat model with elevated blood glucose due to partial pancreatectomy and the possible mechanism. Methods　Forty male SD rats were equally randomized into four groups：group A（no interventions），group B（treated with open total splenectomy），group C（treated with open total splenectomy and partial pancreatectomy），and group D〔treated with open total splenectomy，partial pancreatectomy，and administration of insulin glargine injection（0.1 U/kg），once daily at one week after the surgery〕. The oral glucose tolerance test was performed in all groups at the first and fourth weeks after the initiation of the study to test the blood glucose. The rats were sacrificed at the end of the fourth week of study，and the ileal tissues were taken out for pathologically examining morphological changes. The NF-κB p65 expression 〔expressed as average optical density（AOD）〕 in ileal tissues was detected using immunohistochemistry. Gut floras in fecal specimens were assessed by sequencing the 16S rRNA V3-V4 variable regions using the Illumina MiSeq （PE300） sequencing platform. The changes in gut microbiota were analyzed comparatively. Results　The rat model of stable hyperglycemic was successfully created by using partial pancreatectomy. Dark brown staining was seen in the mucosal，submucosal，and muscular layers of the ileal intestine in group C under microscopy. The AOD value of NF-κB p65 expression in group C was more elevated than that of group A or B （P<0.05）. Sequencing of gut floras of four groups of rats found that the relative distribution of the gut flora of each group at the phylum level was significantly different. Group C had decreased abundance of Firmicutes，increased number of Bacteroides and increased abundance of Proteus compared with groups A and B，and so did group D. The α-diversity expressed by dilution curve showed that the order of species richness from low to high was：group A<group D<group B<group C. The community distribution was relatively concentrated in each group，indicating that the group's specimen repeatability was good and stable. The species composition of groups A and B were the most similar，which were located in the same quadrant. The specimens of groups C and D were clustered in the other two quadrants，respectively. Conclusion　Elevated blood glucose may activate the NF-κB signaling pathway，leading to inflammatory changes in the intestines，which would result in intestinal flora disorders，mainly presented as significantly decreased abundance of Firmicutes，and considerably increased abundance of Bacteroides and Proteus at the phylum level.

Key words: Hyperglycemia, NF-kappa B, Gastrointestinal microbiome, Intestinal flora, 16S rRNA, Rats

摘要： 背景　随着近年来肠道菌群测序技术的迅速发展，越来越多的疾病被发现与肠道菌群存在密切关系。糖尿病作为威胁人类健康的一大疾病，其与肠道菌群的关系受到广泛关注。目的　探讨血糖升高后肠道菌群的变化及可能机制。方法　将40只雄性SD大鼠采用简单随机化分组法分为正常组（n=10，A组）、假手术组（n=10，B组，只开腹切除脾脏）、实验组（n=10，C组，开腹切除脾脏及部分胰腺）和实验+干预组〔n=10，D组，在C组基础上，术后1周开始给予胰岛素干预（甘精胰岛素注射液，0.1 U/kg，1次/d）〕。术后1、4周四组大鼠行口服葡萄糖耐量试验（OGTT），观察各组大鼠血糖变化。术后4周处死大鼠，留取回肠组织，观察肠道组织形态变化并行免疫组化测定各组核因子（NF）-κB p65表达变化〔以平均光密度值（AOD值）表示〕；留取粪便并使用测序平台Illumina MiSeq PE300对肠道菌群的16S rRNA V3~V4可变区进行测序，并分析四组大鼠肠道菌群的变化。结果　胰腺部分切除术成功复制较为稳定的高血糖大鼠模型。显微镜下C组回肠肠道黏膜层、黏膜下层、肌层均可见棕色深染，C组AOD值高于A、B组（P<0.001）。各组肠道菌群在门水平的相对分布情况存在差异，与A、B组比较，C组和D组厚壁菌门丰度降低，而拟杆菌数目和变形杆菌丰度增加。α多样性稀释曲线显示，按物种丰富程度从低到高排序依次为：A组<D组<B组<C组。各组内群落分布较为聚集，说明组内标本重复性较好，较为稳定。A组与B组间物种组成最相似，基本位于同一象限；C组和D组物种分别聚集于另外两个象限。结论　血糖升高可激活NF-κB信号通路导致肠道发生炎性改变，从而造成肠道菌群紊乱，主要门水平表现为厚壁菌门丰度明显降低，而拟杆菌门和变形菌门的丰度显著增加。

关键词: 高血糖；核因子-&kappa, B；胃肠道微生物组；肠道菌群；16S rRNA；大鼠