Gut bacteria affect brain development
Bacteria in the gut acquired early in life could affect future brain development and behaviour, according to new research on mice.
Researchers compared behaviour and gene expression in mice raised with normal microorganisms to those that were 'germ-free'. The germ-free mice were more active and engaged in riskier activities than the normal mice.
Brain transmitters that play an important role in learning and memory also behaved differently in the two groups of mice. Similarly, the levels of proteins involved in communication in the central nervous system were different.
Gut bacteria colonise their hosts during pregnancy or shortly after birth. They play an important role in the health of the developing organism. Gut bacteria have been linked to the development of the liver, digestive tissue and blood vessels. Other harmful bacteria have been linked to neurological disorders such as autism and schizophrenia.
Researchers tested the differences in exploratory behaviour between normal mice and germ-free mice. They placed the mice in a light-dark box and a maze with elevated levels. Germ-free mice were found to spend more time in the light and in elevated areas, suggesting riskier behaviour and lower anxiety than normal mice.
The results suggest that the bacteria acquired early in life could contribute to psychiatric conditions. Germ-free mice were also infected with normal gut bacteria shortly after birth. They displayed similar behaviour to normal mice, suggesting that bacteria introduced early in life can still affect brain development.
Future research hopes to determine exactly which bacteria affect brain development and how they communicate with the brain.