Regulation of host stress response by gut microbiota

Gut microbiota have several beneficial effects on host physiological functions ; however, little is known about whether or not such microbes can affect the development of brain plasticity and a subsequent central nervous system response. Recently, accumulating evidence has shown that gut microbiota can affect host stress response and behavioral phenotype. Our previous works using gnotobiotic mice demonstrated that hypothalamic-pituitary-adrenal reaction to restraint stress was substantially higher in germ-free (GF) mice than in specific pathogen free (SPF) mice. Moreover, GF mice were more active and anxious than EX-GF mice of which microbiota had been reconstituted with normal SPF microbiota. These results thus support the idea that gut microbes affect postnatal development of host stress response and behavioral phenotype.