Fig. 1. Absence of microbiota leads to antianxiety- and antidepressant-like phenotypes, and E. coli lipopolysaccharide (LPS) treatment leads to an antidepressant-like phenotype.

a–d The total distance a and the percentage of center distance b in the open field test (OFT), the immobility time c in the forced swim test (FST), and the latency to feed d in the novelty suppressed feeding test (NSFT) of germ-free (GF) (n = 19) and specific pathogen-free (SPF) (n = 20) mice. e–g The total distance e and the percentage of center distance f in the OFT, and the immobility time g in the FST of E. coli LPS-treated mice (n = 13) and control mice (n = 13). Data represent the mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001