刊登在國際雜志Sci Transl Med上的一篇在小鼠中進行的一項新的研究報道中指出，胃分流術會改變腸道的微生物構成,，而這些變化可能是手術后病人體重快速下降的原因,。探索胃分流術后造成體重喪失的基礎機制可能會幫助研究人員找出替代該手術的非外科療法。Alice Liou及其同事觀察到在手術后人類及大鼠腸道中2組微生物豐度的改變,，即像大腸桿菌這樣的變形桿菌及疣微菌目的改變,。這些細菌在正常人和嚙齒動物中通常有著相對較低的水平。
研究人員對手術會如此快而且強力地改變腸道微生物（這些變化僅在手術后1周就被觀察到）以及這些效應在小鼠,、大鼠及人類中如此一致地出現(xiàn)而感到驚奇,。微生物群落的改變出現(xiàn)在整個胃腸道，特別是會在遠離手術位置的遠端腸道中出現(xiàn),。此外,，在無菌小鼠體內(nèi)植入從那些接受過手術的動物體內(nèi)獲取的微生物會使這些無菌小鼠的體重下降且脂肪組織減少。
文章的作者并不完全知道為什么這些腸道微生物的變化會促使體重下降,，但一個可能的機制也許是手術后小鼠體內(nèi)產(chǎn)生的短鏈脂肪酸類型發(fā)生了變化,。這些結果表明，腸道菌群的改變不是由體重減輕或熱卡受限引起的,，而是由胃分流術本身所引起的獨特變化造成的,。（生物谷Bioon.com）
doi:10.1126/scitranslmed.3005687
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Conserved Shifts in the Gut Microbiota Due to Gastric Bypass Reduce Host Weight and Adiposity
Alice P. Liou1, Melissa Paziuk1, Jesus-Mario Luevano Jr.2, Sriram Machineni1, Peter J. Turnbaugh2,* and Lee M. Kaplan1,*
Roux-en-Y gastric bypass (RYGB) results in rapid weight loss, reduced adiposity, and improved glucose metabolism. These effects are not simply attributable to decreased caloric intake or absorption, but the mechanisms linking rearrangement of the gastrointestinal tract to these metabolic outcomes are largely unknown. Studies in humans and rats have shown that RYGB restructures the gut microbiota, prompting the hypothesis that some of the effects of RYGB are caused by altered host-microbial interactions. To test this hypothesis, we used a mouse model of RYGB that recapitulates many of the metabolic outcomes in humans. 16S ribosomal RNA gene sequencing of murine fecal samples collected after RYGB surgery, sham surgery, or sham surgery coupled to caloric restriction revealed that alterations to the gut microbiota after RYGB are conserved among humans, rats, and mice, resulting in a rapid and sustained increase in the relative abundance of Gammaproteobacteria (Escherichia) and Verrucomicrobia (Akkermansia). These changes were independent of weight change and caloric restriction, were detectable throughout the length of the gastrointestinal tract, and were most evident in the distal gut, downstream of the surgical manipulation site. Transfer of the gut microbiota from RYGB-treated mice to nonoperated, germ-free mice resulted in weight loss and decreased fat mass in the recipient animals relative to recipients of microbiota induced by sham surgery, potentially due to altered microbial production of short-chain fatty acids. These findings provide the first empirical support for the claim that changes in the gut microbiota contribute to reduced host weight and adiposity after RYGB surgery.
