哺乳期过度喂养对幼鼠肥胖和肠道菌群结构的影响

The effect of postnatal overfeeding on obesity and the gut microbiota composition in infant mice

目的研究哺乳期过度喂养对幼鼠肠道细菌组成的影响以及肠道细菌与哺乳期过度喂养导致的幼年肥胖的相关性。方法将正常出生体重的4日龄雄性ICR仔鼠分为正常喂养组(NF组,每8只由1只母鼠喂养)和哺乳期过度喂养组(OF组,每4只由1只母鼠喂养),哺乳至3周龄时,对仔鼠进行口服糖耐量试验(OGTT),称量体重、各种器官和脂肪组织的重量,用基于细菌16S rRNA基因的变性梯度凝胶电泳(DGGE)和实时定量PCR分析仔鼠的粪便细菌组成,对细菌类群数量与表型数据进行相关分析。结果 OF组仔鼠从10日龄起体重显著高于NF组,3周龄时附睾和肾周脂肪垫重量显著高于NF组,两组仔鼠的空腹血糖以及OGTT血糖曲线下面积比较差异无统计学意义。对DGGE图谱的主成分分析表明两组仔鼠的菌群结构比较差异有统计学意义。定量PCR显示,OF组仔鼠粪便中产生内毒素的肠杆菌科细菌和产生破坏肠屏障功能的H2S的硫酸盐还原菌的数量显著高于NF组,而双歧杆菌、乳杆菌和丁酸盐产生菌的数量在两组仔鼠之间差异无统计学意义。粪便硫酸盐还原菌的数量与内脏脂肪的重量显著正相关。结论哺乳期过度喂养增加了肠道中肠杆菌科细菌和硫酸盐还原菌的数量,这些细菌的增加与仔鼠幼年期肥胖相关。

Objective To investigate the effect of postnatal overfeeding on the composition of gut microbiota and the association of gut bacteria with obesity induced by postnatal overfeeding in infant mice. Methods 4-day-old male ICR mouse pups with normal birth weight were randomly assigned to either the normal feeding （NF, 8 pups were reared by one dam） or the overfeeding （OF, 4 pups were reared by one dam） group. At weaning age （3 weeks of age） , oral glucose tolerance test （OGTI＇） was performed on all the pups; body weight and the weights of organs and adipose tissues were measured, and bacterial 16S rRNA gene-based denaturing gradient gel electro- phoresis （DGGE） and real-time PCR were performed to analyze the fecal microbiota composition. Results OF mice had significantly higher body weight, more epididymal fat and perinephric fat, but there was no significant differences between two groups in the level of fasting glucose and area under curve of OGT＇F. Principle component analysis （PCA） of the DGGE profile showed that the composition of gut microbiota was significantly different between the two groups. Real-time PCR showed that postnatal overfeeding significantly increased the amount of fecal endotoxin-producing Enterobacteriaceae and gut barrier-impairing sulfate-reducing-bacteria （ SRB）, and did not change the amount of Bifidobacterium, LactobaciUus and butyrate-producing bacteria. Fecal SRB amount was significantly positively corre- lated with the weight of visceral fat according to spearman correlation analysis. Conclusion Postnatal overfeeding increases the amount of Enterobacteriaceae and SRB in the gut, and the overgrowth of these bacteria in the gut was associated with obesity and insulin resistance at the early stage of life.