Phd in CLINICAL EXPERIMENTAL NEUROSCIENCE AND PSYCHIATRY

Thesis title: Environmental enrichment modifies gut microbiome and metabolome

The intestinal microbiota composed of both microorganisms and their products influences both behavior and brain functions; however, the improvement of synaptic plasticity and cognitive functions have been demonstrated with an accommodation in an enriched environment with sensory, motor and social stimuli. To study gut-brain communication and provide missing parts of the effects of the environment on the host, we hypothesized that environmental enrichment could modulate both microbial and metabolomic composition. Metagenomic and metabolomic analyses of mice housed in standard or enriched environment, highlight environment-specific microbial community, and metabolic profiles. We observed that mice housed in an enriched environment showed a reduction of gut microbial richness and diversity indexes and were characterized by a metabolomic fingerprint with the increase of two short chain fatty acids (SCFA) formate and acetate and the decrease of bile salts. Furthermore, we have shown that animals treated with a mix of format and acetate improved hippocampal neurogenesis, the expression of neurotrophins, as well as the cognitive response. These data showed us that SCFAs could be molecular effectors of enriched environment in the brain.