Journal Article Seminar for Feb 6 2020

Journal Article:                 The Microbiota Regulate Neuronal Function and Fear Extinction Learning

Chu, C., Murdock, M. H., Jing, D., Won, T. H., Chung, H., Kressel, A. M., … & Bessman, N. J.

                                                Nature574(7779), 543-548.

Synopsis by :   Echo Geronca

We often disregard gut feeling as nothing more than a product of our irrational subconscious. However, a recent paper by Chu, et al. might leave you questioning your next decision. In humans, studies have shown that the microbiota, which consists of a complex consortium of viruses, bacteria, fungi, and parasites, can influence the host’s behaviour. However, the mechanisms by which the microbiota influence the host’s neuronal activity and physiology are still poorly understood. Chu, et al. hypothesized that manipulation of the microbiota in mice would lead to significant deficits in neural activity and fear extinction learning.

They performed four experiments using antibiotic-treated, germ-free, and control cohorts. The mice were trained to associate and dissociate a tone with a foot shock.  Their results show that fear association developed normally on all three groups; however, only the control group was able to return to homeostasis after the stressor was removed. In vivo imaging of the pre-frontal cortex was also performed and results showed that the antibiotic-treated and germ-free mice had more dendritic spine elimination. They also sequenced RNAs from single cells in the same brain region and found that microbiota deletion had a more pronounced effect on excitatory neurons compared to inhibitory neurons. Lastly, they profiled gut metabolites and identified four metabolites that were significantly less abundant in antibiotic-treated and germ-free mice.

Chu and colleagues’ results suggest that the microbiota is needed by mice for normal neural activity and fear extinction learning. They also showed that changes in the microbiota lead to altered gene expression in microglia, neurons, and dendritic-spine maintenance. Most importantly, their work provides better understanding of the gut-brain axis and opens up the discussion on the possibility of targeting the gut microbiota and its metabolites as a strategy for the treatment of individuals with post-traumatic stress disorder.

Keywords: Microbiota, Fear responses, Neurobiology

References:

Chu, C., Murdock, M. H., Jing, D., Won, T. H., Chung, H., Kressel, A. M., … & Bessman, N. J. (2019). The microbiota regulate neuronal function and fear extinction learning. Nature574(7779), 543-548.

Kiraly, D. D. (2019). Gut microbes regulate neurons to help mice forget their fear.