Gut Bacteria found to be a Cause of Stress Disorder

Americans, these days are the most stressful people in the world, that is, 55% of the adults. Researchers have come up with a new study related to gut bacteria in stressful situations. It was found that the way people respond to their daily life stressful situations may depend on the health of their immune system as well.

The findings appeared in the journal Nature on 23 October 2019. What researchers did was, through electric shocks, they made mice learn a tone that they could link with the reaction of humans on receiving a new text.

Researchers were led by David Artis at Cornell University. He made the mice rest in a chamber where they were exposed to the tone for 30 seconds. As soon as the tone got finished, they were given electric shocks by means of the floor.

Researchers grouped the mice into two; one of them was the control group, while the other one was given antibiotics. Antibiotics affected the strength of gut bacteria in the mice.
To observe the effect of gut microbiota on the time taken to adapt a response, they again rang that tone, but now without giving an electric shock. Mice who had a poor quality of gut microbiota or had a lesser number of gut bacteria took a longer time to get back into their senses.

On the other hand, mice in the control group quickly adapted to the learned tone. According to the author, “In mammals, changes in the composition of the microbiota can influence many physiologic processes (including development, metabolism and immune cell function) and are associated with susceptibility to multiple diseases.”

As soon as the mice heard the tone, they all started panicking because of the Pavlovian conditioning. However, the group having lower gut bacteria even panicked after the shocks stopped.

The analysis of the results showed that the mice who took a long time to get back to their normal state had a low number of metabolic products of gut bacteria in the lymph surrounding the brain. At first, they began the research with the vagus nerve.

“Alterations in the microbiota can also modulate host behaviors—such as social activity, stress, and anxiety-related responses—that are linked to diverse neuropsychiatric disorders,” says the author.

As per the research, two of these four metabolites are responsible for initiating autism and schizophrenia in children and adults.

Researchers explained the main cause of the link by saying, “[O]ur findings offer one compelling explanation for the notable deficits in fear extinction learning in [antibiotic-treated mice]… and suggest that alterations in microbiota-derived metabolites contribute to altered neuronal activity and behavior.” Lower gut bacteria affect gene expression in the brain to a large extent. Two important parts of the brain, the amygdala and medial prefrontal cortex responsible for detecting fear showed impairment due to the low quality of gut bacteria.

The research shows a deep link between emotional wellbeing and gut health. This is how the immune system, endocrine organs, and autonomic nervous system are linked.

This recent discovery may later help with useful applications like in treating post-traumatic stress disorder (PTSD). The research gives a broader axis to understand depression, anxiety, and stress.

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