抗生素早期慢暴露对大鼠成年后肠-脑轴的影响

Effects of Early Exposure to Antibiotics on Puberty Gut-brain Axis in Rats

目的观察大鼠生命早期抗生素暴露对其成年后肠-脑轴的影响。方法选取出生后第21天的(PND21)雄性SD大鼠,随机分为对照组(Con)和抗生素组(Abx),日常饮用水分别给予无菌水和含有盐酸四环素(3周,2 g·L^(-1))、罗红霉素(1周,0.005 g·L^(-1))和盐酸环丙沙星(6周,0.1 g·L^(-1))的无菌水。第10周后采用Morris水迷宫实验观察SD大鼠认知行为变化;16SrDNA测序技术检测肠道菌群变化;ELISA法检测血清中肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-6、IL^(-1)β的水平;HE染色观察海马形态学改变。结果与Con组相比,Abx组大鼠逃逸潜伏期延长(P<0.05);Abx组肠道菌群Chao1指数、Shannon指数和Simpson指数均降低(P均<0.01);在门水平上:Abx组厚壁菌门(Firmicutes)减少,疣微菌门(Verrucomicrobia)增多(P均<0.01);在属水平上:Abx组乳杆菌属(Lactobacillus)、Ruminococcaceae_UCG-005减少,艾克曼菌属(Akkermansia)、拟杆菌属(Bacteroides)增多(P均<0.01);Abx组大鼠血清中炎性因子TNF-α、IL-6、IL^(-1)β水平均升高(P均<0.01);形态学观察发现Abx组大鼠海马齿状回闩区新生神经元疏松分布,排列不规则,细胞核固缩。结论SD大鼠幼年抗生素慢性暴露,可引起成年后肠道菌群结构紊乱,成年后空间学习记忆能力减弱,破坏肠-脑轴功能稳态。

Objective To observe the effects of antibiotics exposure on gut-axis in rats.Methods Male SD rats on the 21st day after birth(PND21)were randomly divided into control group(Con)and antibiotics group(Abx).The Abx rats were treated with antibiotics in drinking water successively,using tetracycline hydrochloride(3 weeks,2 g·L^(-1)),roxithromycin(1 week,0.005 g·L^(-1))and ciprofloxacin hydrochloride(6 weeks,0.1 g·L^(-1)),the Con rats were treated with equal water.10 weeks later,morris water maze test was used to observe the spacial cognitive behavior.The intestinal flora were detected by 16S rDNA sequencing.ELISA was used to detect the levels of tumor necrosis factor-α(TNF-α),interleukin-6(IL-6)and interleukin-1β(IL^(-1)β)in serum.The morphology of hippocampus were observed by HE staining.Results The results showed that the escape latency of rats in Abx group was significantly longer than that in Con group(P<0.05).The index of chao1,Shannon and Simpson of intestinal flora in Abx group were significantly decreased(P all<0.01).At the phylum level,Firmicutes were decreased(P<0.01),Verrucicrobia were increased(P<0.01)in Abx rats;At the genus level,both Lactobacillus and Ruminococcaceae_UCG-005 were decreased(P all<0.01).Akkermansia and Bacteroides were increased(P all<0.01)in Abx rats.The levels of TNF-α,IL^(-1)βand IL-6 in serum in Abx group were significantly increased(P all<0.01).The morphology showed that the new neurons in dentate gyrus of hippocampus in Abx group were disordered and loose arrangement,and pyknotic nuclei.Conclussion These results suggest that exposure to antibiotics in early life can induce intestinal flora disorder and spatial learning and memory impairment in adulthood,which may be related to the imbalance of gut-brain axis.