Distinct Dendritic Morphological Changes in the Nucleus Accumbens of Microbiota-deficient Male Mice

The gut microbiota has been shown to be an important regulator of brain and behaviour. Germ-free rodents are a key model to study the microbiome-gut-brain axis to reveal the microbial underpinnings of diseases, including those related to psychiatric illnesses. The present study evaluated whether the absence of gut microbiota could alter the morphological development of the nucleus accumbens, a brain region located in the ventral striatum involved in stress, mood and addiction. In germ-free mice, there was dendritic hypertrophy of medium spiny neurons in the shell and dendritic elongation in the core. This led to an increase in the number of stubby dendritic spines within the shell and an increase in both stubby and thin spines in the core. Taken together, these results indicate that the gut microbiota is essential for the normal development of the dendritic structure of medium spiny neurons in the nucleus accumbens and that altered remodelling may contribute to maladaptive psychiatric disorders. ### Competing Interest Statement The authors have declared no competing interest.