Link Between Anxiety and Gut Bacteria Explored


Scientists are learning more about the relationship between our gut bacteria (microbiome) and anxiety.

Recently, some researchers at the University College Cork discovered that a substantial number of microRNAs (miRNAs) were altered in the brains of mice reared in a germ-free bubble. These microbe-free mice typically demonstrated high anxiety, social and cognitive deficits, and a depressive manner.

“Gut microbes seem to influence miRNAs in the amygdala and the prefrontal cortex,” said study author Dr. Gerard Clarke. “This is important because these miRNAs may affect physiological processes that are fundamental to the functioning of the central nervous system and in brain regions…implicated in anxiety and depression.”

miRNAs are short nucleotide sequences (building blocks of DNA and RNA) that can control how genes express. Dysfunction in miRNAs is thought to be a factor in stress-related mental health disorders, including anxiety.

Treating psychiatric disorders by modulating miRNAs in the brain has so far involved looking for safe therapeutic compounds that can cross the blood-brain barrier. “Our study suggests that some of the hurdles that stand in the way of exploiting the therapeutic potential of miRNAs could be cleared by instead targeting the gut microbiome,” says Clarke.

The researchers found that levels of numerous miRNAS were different in the amygdala and prefrontal cortex of mice raised without gut bacteria (GF mice) compared to conventionally raised mice. Restoring the gut microbes later in life normalized some of the miRNA brain changes. This suggests healthy gut bacteria is a requirement for the optimal regulation of miRNAs in those two brain areas.

The investigators also observed that depleting the gut bacteria of adult rats using antibiotics altered some of their brains’ miRNAs in a way similar to the GF mice. This implies changes to the microbiome in adulthood can influence miRNAs in the brain associated with anxiety-like behaviors.

“This is early stage research but the possibility of achieving the desired impact on miRNAs in specific brain regions by targeting the gut microbiota - for example by using psychobiotics - is an appealing prospect,” said Clarke.

Source: Science Daily
Photo credit: IBM Research

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