Research published in the journal Molecular Psychiatry
has found that bacteria present in the gut during the early stages of our development influence levels of serotonin in the brain in adult life.
Serotonin is the hormone associated with regulation of mood and emotion. Levels of serotonin are affected by stress, anxiety and depression, and for this reason it is often the target of antidepressant treatments.
Scientists from the Alimentary Pharmabiotic Centre at University College Cork (UCC) have shown, using a germ-free mouse model, that concentrations of serotonin in adult brains were affected considerably by the absence of gut bacteria in young individuals.
"As a neuroscientist these findings are fascinating as they highlight the important role that gut bacteria play in the bidirectional communication between the gut and the brain, and open up the intriguing opportunity of developing unique microbial-based strategies for treatment for brain disorders", remarked Professor John F Cryan, a senior author on the paper and Head of the Department of Anatomy and Neuroscience at UCC.
Previous work by the UCC team and others has suggested that a microbiome-gut-brain axis is responsible for maintaining all sorts of chemical and neurochemical balances in the body. When bacteria were introduced to the guts of animals before they reached adulthood, the nervous system changes wreaked could not be reversed, especially those associated with serotonin.
It was also noted that the phenomena was sex-dependent, with males being more heavily influenced than females by the presence (or absence) of the bacteria. Many implications for areas such as antibiotics, diet and the handling of infection could stem from the research.
"We’re really excited by these findings," stated lead author Dr Gerard Clarke. "Although we always believed that the microbiota was essential for our general health, our results also highlight how important our tiny friends are for our mental wellbeing."