昼夜节律紊乱对大鼠肠道菌群及肠道屏障的影响

目的 研究昼夜节律紊乱对机体肠道菌群和肠道屏障的影响，为预防和干预昼夜节律紊乱引发机体健康问题提供理论依据。方法 30只SD雄性大鼠，随机分为对照组和昼夜节律紊乱组（下文简称紊乱组），对照组大鼠用正常光周期暴露（12 h光照/12 h黑暗周期），紊乱组大鼠用轮回颠倒的光照周期暴露（12 h光照/12 h黑暗周期，每3 d颠倒一次，共计5个轮回）。采用16S rRNA测序技术测定分析大鼠结肠肠道菌群的物种组成和群落结构变化，利用苏木精-伊红染色法（HE）观察结肠组织学变化，采用Western blot方法检测大鼠结肠Occludin、Claudin1、Claudin3和ZO - 1紧密连接蛋白表达。结果 与对照组比较，紊乱组大鼠肠道菌群多样性降低和构成发生改变。门水平上，紊乱组大鼠肠道拟杆菌门（t = 2.672, P = 0.028）的丰度增加，而厚壁菌门（t = 2.732, P = 0.024）和放线菌门（t = 2.717, P = 0.026）的丰度减少。属水平上，紊乱组大鼠肠道毛螺菌（t = 4.468, P = 0.002）、瘤胃球菌（t = 4.096, P = 0.007）、梭状杆菌（t = 2.619, P = 0.038）和嗜木聚糖真杆菌（t = 2.500, P = 0.041）丰度减少。结肠粘膜下层轻度水肿但粘膜上皮没有发生明显损伤。大鼠结肠紧密连接蛋白Occludin（t = 7.283, P＜0.001）、Claudin1（t = 13.660, P＜0.001）、Claudin3（t = 10.596, P＜0.001）和ZO - 1（t = 6.919, P＜0.001）表达均降低。结论 长期昼夜节律紊乱导致大鼠肠道菌群组成和结构发生改变。长期昼夜节律紊乱还可通过破坏肠道紧密连接而损害肠道上皮屏障的完整性，进而增加肠道通透性。

Effect of circadian misalignment on gut microbes and gut barrier in rats

Objective To investigate the effect of circadian misalignment on the intestinal system, and to provide the theoretical basis for the prevention and intervention of body health problems caused by circadian misalignment. Methods Thirty SD male rats were randomly divided into control group and circadian reversal group (reversal group). The rats of control group were exposed at the normal photoperiod (12:12 light/dark cycle) and the rats of circadian reversal group were exposed at the reversed photoperiod (12:12 light/dark cycle with inverting every three days, a total of five cycles). The changes of species composition and community structure in the rat colonic gut flora were analyzed by using 16S rRNA sequencing and analysis. The histological changes of colon intestinal were observed by using hematoxylin-eosin staining (HE). The expression of tight junction protein for Occludin, Occludin1, Occludin3 and ZO-1 in the rat intestine were examined by Western blot. Results Compared with control group, the diversity of gut microbiota was reduced and the composition of intestinal microbiota were altered in the reversal group. At the phylum level, the abundance of gut Bacterioides (t=2.672, P=0.028) increased in the reversal group, whereas the abundance of Firmicutes (t=2.732, P=0.024) and Actinobacteria (t=2.717, P=0.026) decreased in the reversal group. At the genus level, the abundance of Lachnospiraceae (t=4.468, P=0.002), Ruminococcus (t=4.096, P=0.007), Clostridium (t=2.619, P=0.038), and Eubacterium_xylanophilum (t=2.500, P=0.041) decreased in the reversal group. Mild edema occurred in the colonic submucosa, but no significant damage to the mucosal epithelium occurred. The expression of tight junction protein for Occludin (t=7.283, P<0.001), Claudin1 (t=13.660, P<0.001), Claudin3 (t=10.596, P<0.001) and ZO-1 (t=6.919, P<0.001) reduced in the reversal group. Conclusion Chronic circadian misalignment caused change of composition and structure in intestinal gut microbiota community. Chronic circadian misalignment might also disrupt the intestinal tight junctions and impair the integrity of the intestinal epithelial barrier, which in turn increased intestinal permeability.