title: Gut microbiota of mice putatively modifies amino acid metabolism in the host brain.
abstract: Recently, it has been found that the gut microbiota influences functions of the host brain by affecting monoamine metabolism. The present study focused on the relationship between the gut microbiota and the brain amino acids. Specific pathogen-free (SPF) and germ-free (GF) mice were used as experimental models. Plasma and brain regions were sampled from mice at 7 and 16 weeks of age, and analysed for free d- and l-amino acids, which are believed to affect many physiological functions. At 7 weeks of age, plasma concentrations of d-aspartic acid (d-Asp), l-alanine (l-Ala), l-glutamine (l-Gln) and taurine were higher in SPF mice than in GF mice, but no differences were found at 16 weeks of age. Similar patterns were observed for the concentrations of l-Asp in striatum, cerebral cortex and hippocampus, and l-arginine (l-Arg), l-Ala and l-valine (l-Val) in striatum. In addition, the concentrations of l-Asp, d-Ala, l-histidine, l-isoleucine (l-Ile), l-leucine (l-Leu), l-phenylalanine and l-Val were significantly higher in plasma of SPF mice when compared with those of GF mice. The concentrations of l-Arg, l-Gln, l-Ile and l-Leu were significantly higher in SPF than in GF mice, but those of d-Asp, d-serine and l-serine were higher in some brain regions of GF mice than in those of SPF mice. In conclusion, the concentration of amino acids in the host brain seems to be dependent on presence of the gut microbiota. Amino acid metabolism in the host brain may be modified by manipulating microbiota communities.
authors.affiliation: 1Laboratory of Regulation in Metabolism and Behavior,Graduate School of Bioresource and Bioenvironmental Sciences,Kyushu University,Fukuoka 812-8581,Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kawase
authors.affiliation: 1Laboratory of Regulation in Metabolism and Behavior,Graduate School of Bioresource and Bioenvironmental Sciences,Kyushu University,Fukuoka 812-8581,Japan.
authors.forename: Mao
authors.initials: M
authors.lastname: Nagasawa
authors.affiliation: 1Laboratory of Regulation in Metabolism and Behavior,Graduate School of Bioresource and Bioenvironmental Sciences,Kyushu University,Fukuoka 812-8581,Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: 1Laboratory of Regulation in Metabolism and Behavior,Graduate School of Bioresource and Bioenvironmental Sciences,Kyushu University,Fukuoka 812-8581,Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Yasuo
authors.affiliation: 2Laboratory for Infectious Diseases,School of Medicine,Tokai University,Kanagawa 259-1193,Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Koga
authors.affiliation: 1Laboratory of Regulation in Metabolism and Behavior,Graduate School of Bioresource and Bioenvironmental Sciences,Kyushu University,Fukuoka 812-8581,Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Furuse
mesh_terms: D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D000069196:Gastrointestinal Microbiome; D008807:Mice, Inbred BALB C; D018377:Neurotransmitter Agents / Q000378:metabolism
chemical_list: D000596:Amino Acids; D018377:Neurotransmitter Agents
keywords: 
                 D-Amino acids; 
                 L-Amino acids;  Ala alanine;  Arg arginine;  Asp aspartic acid;  GABA 
                    γ-aminobutyric acid;  GF germ free;  Gln glutamine;  His histidine;  Ile isoleucine;  Leu leucine;  Phe phenylalanine;  SPF specific pathogen free;  Ser serine;  Tau taurine;  Tyr tyrosine;  UPLC ultra-performance liquid chromatography;  Val valine; Ageing; Brain; Germ-free mice; Gut microbiota