Young-Donor Gut Microbes Restored Visual Plasticity in Older Mice After Eye-Covering Test

Older mice that received a faecal microbiome transplant from younger donors regained the ability to rewire visual circuits after one eye was covered for three days, a response normally limited to early life. 730811. Researchers first gave 21-day-old mice a high dose of broad-spectrum antibiotics dissolved in water every day for 10 days.

These animals showed substantial changes to their gut microbiomes, including reduced levels of bacterial families such as Lachnospiraceae. After antibiotic treatment, each mouse had one eye sealed for three days. Control mice that had not received antibiotics showed evidence of neuroplasticity, with their brains responding more to stimulation of the eye that had stayed open.

Mice given antibiotics did not show the same response. RNA sequencing revealed more than 1000 genes were differently expressed in the visual cortex of antibiotic-treated mice compared with controls. Differentially expressed genes included those related to myelination and blood-brain barrier permeability.

The team then transplanted faecal microbiota from approximately 30-day-old mice into 4-month-old adult mice. A control group of 4-month-old mice received faecal transplants from other adult mice. Only the recipients of the young microbiota demonstrated neuroplasticity in response to the eye-shutting experiment.

“This study suggests that microbial communities may help regulate critical periods of brain development by defining when developmental windows of heightened plasticity open and close,” said Parisa Gazerani at Oslo Metropolitan University. Harriët Schellekens at University College Cork stated that the microbiome might be targeted later in life to enhance learning, recovery after injury, or resilience in ageing and neurological disease.