Fecal or bacterial transplantation in mice transfer environmentinduced brain plasticity and associated behavioral changes

Francesco Marrocco¹Rizwan Khan¹Alice Reccagni¹Xingzi Lin¹Mary Delli Carpini¹Valerio Iebba²Giuseppina D'Alessandro^1,3*Cristina Limatola^1,3*

• ¹Sapienza University of Rome, Rome, Italy
• ²Institut Gustave Roussy, Villejuif, Île-de-France, France
• ³Mediterranean Neurological Institute Neuromed (IRCCS), Pozzilli, Italy

Recent studies have shown that lifestyle factors, including diet and environmental stimuli, significantly alter the composition of gut microbiota and the metabolites they produce. Specifically, housing mice in an enriched environment (EE) enhances the production of short-chain fatty acids, which in part mediate the effects of EE on brain plasticity. In this study, we tested the hypothesis that the gut microbial composition of EE-exposed mice could be transplanted into mice housed in a standard environment (SE) to replicate the environmental effects on behavior, gene expression and neurogenesis. To test this, we transplanted either a specific bacterial mixture or fecal material from EE-housed mice into SE-housed mice. Our results show that both bacterial and fecal transplants reduce anxiety-like behaviors in mice. Additionally, we observed increased expression of hippocampal neurotrophins and enhanced neurogenesis. These findings support the idea that gut microbiota play a role in modulating brain functions, such as anxiety-like behavior. Further research is needed to better understand the underlying mechanisms. These results suggest that fecal microbiota transplantation (FMT) from individuals with healthy lifestyles could serve as a potential strategy for treating mood disorders.