Source of happiness may lie in your gut

Brain levels of serotonin, the ‘happiness hormone’ linked to normal functioning of adult brain, are regulated by the amount of bugs in your gut during early life, says a new study.

Serotonin, the major chemical involved in the regulation of mood and emotion, is altered in times of stress, anxiety and depression, and most clinically effective antidepressant drugs work by targeting this neurochemical.

Scientists at the Alimentary Pharmabiotic Centre at the University College Cork, Ireland, used a germ-free mouse model to show that the absence of bugs during early life significantly affected serotonin concentrations in the brain in adulthood, the journal Molecular Psychiatry reports.

The research also highlighted that the influence is sex dependent, with more marked effects in male compared with female rodents, according to a University College statement.

When the scientists colonised the rodents with bacteria prior to adulthood, they found that many of the central nervous system changes, especially those related to serotonin, could not be reversed - indicating a permanent imprinting of the effects of absence of gut flora on brain function.

“As a neuroscientist, I find these findings fascinating as they highlight the important role that gut bacteria play in the bi-directional communication between the gut and the brain, and opens up the intriguing opportunity of developing unique microbial-based strategies for treatment for brain disorders,” said John F. Cryan, professor of neuroscience and senior study author at Cork.