title: Bile acid is a host factor that regulates the composition of the cecal microbiota in rats.
abstract: OBJECTIVE
  Alterations in the gastrointestinal microbiota have been associated with metabolic diseases. However, little is known about host factors that induce changes in gastrointestinal bacterial populations. We investigated the role of bile acids in this process because of their strong antimicrobial activities, specifically the effects of cholic acid administration on the composition of the gut microbiota in a rat model.
  
  
  METHODS
  Rats were fed diets supplemented with different concentrations of cholic acid for 10 days. We used 16S ribosomal RNA gene clone library sequencing and fluorescence in situ hybridization to characterize the composition of the cecal microbiota of the different diet groups. Bile acids in feces, organic acids in cecal contents, and some blood parameters were also analyzed.
  
  
  RESULTS
  Administration of cholic acid induced phylum-level alterations in the composition of the gut microbiota; Firmicutes predominated at the expense of Bacteroidetes. Cholic acid feeding simplified the composition of the microbiota, with outgrowth of several bacteria in the classes Clostridia and Erysipelotrichi. Externally administered cholic acid was efficiently transformed into deoxycholic acid by a bacterial 7α-dehydroxylation reaction. Serum levels of adiponectin decreased significantly in rats given the cholic acid diet.
  
  
  CONCLUSIONS
  Cholic acid regulates the composition of gut microbiota in rats, inducing similar changes to those induced by high-fat diets. These findings improve our understanding of the relationship between metabolic diseases and the composition of the gastrointestinal microbiota.
authors.affiliation: Laboratory of Microbial Physiology, Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
authors.forename: K B M Saiful
authors.initials: KB
authors.lastname: Islam
authors.forename: Satoru
authors.initials: S
authors.lastname: Fukiya
authors.forename: Masahito
authors.initials: M
authors.lastname: Hagio
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Fujii
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishizuka
authors.forename: Tadasuke
authors.initials: T
authors.lastname: Ooka
authors.forename: Yoshitoshi
authors.initials: Y
authors.lastname: Ogura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yokota
mesh_terms: D052242:Adiponectin / Q000097:blood; D000818:Animals; D001647:Bile Acids and Salts / Q000032:analysis / Q000378:metabolism*; D002432:Cecum / Q000382:microbiology*; D019826:Cholic Acid / Q000494:pharmacology; D003013:Clostridium / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D004305:Dose-Response Relationship, Drug; D004888:Erysipelothrix / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D008297:Male; D054892:Metagenome / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D023421:Models, Animal; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D052242:Adiponectin; D001647:Bile Acids and Salts; D012336:RNA, Ribosomal, 16S; D019826:Cholic Acid