New Scientist
Could younger gut bacteria help an ageing brain learn like it’s young again? New research suggests it could be possible.
Microbiome influences brain plasticity
Author: Chris Simms
A FAECAL microbiome transplant (FMT) could make an older brain as adaptable as a young one. For the first time, a study has shown that older mice given the gut microbiomes of younger ones via an FMT experience improved brain plasticity.
Neuroplasticity, the brain’s ability to remodel itself, peaks at a young age, decreasing as our brains naturally prune unused connections during adolescence.
This means that certain conditions like amblyopia, also known as lazy eye, are typically only successfully treated in childhood. This is done by covering the stronger eye, forcing the brain to forge new connections to the weaker eye.
Paola Tognini at the Sant’Anna School of Advanced Studies in Pisa, Italy, and her colleagues wanted to see whether the gut microbiome is involved in brain plasticity and could be manipulated to boost it in adulthood.
It suggests the microbiome might be targeted later in life to enhance learning
First, they gave 21-day-old mice a high dose of broad-spectrum antibiotics for 10 days, and found substantial changes to their gut microbiomes compared with a control group. This included reduced levels of bacterial families such as Lachnospiraceae, which is thought to be neuroprotective.
Each mouse then had one eye sealed for three days. The researchers then imaged the neural responses to the stimulation of each eye. They found that only the control mice showed evidence of neuroplasticity, with their brains responding more to stimulation of the eye that had stayed open.
To investigate further, the team did RNA sequencing to reveal which genes were switched on in the mice’s visual cortex. “We found dramatic alterations in the animals receiving the antibiotic cocktail,” says Tognini. More than 1000 genes were differently expressed compared with the control group. These included genes related to the process of myelination, when nerves get wrapped in a protective sheath, and the permeability of the blood-brain barrier.
Finally, the team transplanted the faecal microbiota of mice aged around 30 days old into 4-month-old adult mice, while a control group got transplants from other adults. Only the brains of the mice receiving the young microbiota demonstrated neuroplasticity in response to the eye-shutting experiment.
If the same applies to people, the implications could be huge, says Harriët Schellekens at University College Cork in Ireland. “It would suggest that the microbiome is not only important for early-life brain development, but might also be targeted later in life to enhance learning, recovery after injury, or resilience in ageing and neurological disease.”
However, direct extrapolation to people is premature, says Parisa Gazerani at Oslo Metropolitan University in Norway, primarily because our brains are more complex and our microbiomes are influenced by our diet and lifestyles.
The study also raises questions about the potential long-term effects of early-life antibiotic exposure, says Gazerani.
Credits: TCA, LLC.