The effect of gut microbiome on hippocampal neurogenesis and behavior in a murine model for autism spectrum disorders

Autism spectrum disorders (ASD) is a neurodevelopmental disorder that features impairment of neurogenesis and changes in the composition of the individual`s gut microbiome. The gut microbiome interacts with the brain via several pathways, including immune modulation, and the secretion of various inflammatory mediators. We thus hypothesize that neurogenesis and behavior can be improved in a murine model for autism spectrum disorder, by altering the composition of the gut microbiome. We apply the murine model for ASD, induced by developmental exposure to valproic acid (VPA). Behavior and molecular analysis were performed for characterization of microbiome manipulation and QIIME2 analysis for gut microbiome composition. We observed that naïve microbiome transplantation decreased overall ASD score composed of social interaction, grooming and day three of the water T maze paradigm in both males and females following VPA exposure and improved early and advanced stages of neurogenesis. VPA exposure altered the beta diversity of the gut microbiome and changed the flora of bacteria in females. Serological analysis revealed a decrease of Th17-rlated cytokines mostly in females after exposure to VPA. Considering the results, we concluded that naïve microbiome transplantation alleviates general ASD symptoms and improves overall neurogenesis in both males and females. Immunomodulation is a key factor in the understanding the effect of the gut microbiome and ASD.