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

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