A group of researchers from the Alimentary Pharmabiotic Centre at University College Cork have found that stomach bacteria play an integral role in regulating levels of serotonin, the neurotransmitter primarily responsible for happiness.

Anti-depressant drugs work by increasing the effective concentration of serotonin in our brains in order to lift mood, but bacteria keep the neurotransmitter levels balanced. Using mice as models, scientists showed that an absence of stomach bacteria during development dramatically affected serotonin levels in the mice’s brains. These effects were found to be irreversible: re-introducing bacteria in adulthood could not undo the changes.

The exact biochemical details of this fascinating phenomenon have not yet been explored, but the researchers are very excited about their discovery. They say that the finding opens up new doors towards understanding the gut-brain dynamic, and  offers opportunities for novel treatments of brain disorders.

Source: Science Daily