Gut Microbes and Behavior

Ian Carroll, Ph.D.
Assistant Professor of Medicine at UNC-Chapel Hill

Dr. Carroll’s research studies how intestinal microbes influence gut physiology and behaviors. Dr. Carroll also uses high throughput sequencing of bacterial genes to characterize the enteric microbiota in human subjects with gastrointestinal disease and mouse models of intestinal inflammation. His goal is to develop enteric microbial-based therapies for the treatment of gut diseases.

In germ free conditions, mice have enlarged cecums, blunted villi, and less weight gain per calories consumed. These changes reverse after inoculation. Microbiota influences emotional state in a complex fashion and germ free mice have higher stress and lower anxiety. Stress increases or decreases depending on the species of bacteria added. Emotional changes after inoculation of germ free mice are not observed when the vagus is severed.
In starvation states, as seen in anorexia, microbiota diversity decreases and the relative proportions of species change. These changes appear to perpetuate symptoms in anorexia. A single case study showed fecal transplant leading to weight gain in a human subject and such interventions might have therapeutic potential in the future.