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Critical Windows of Microbial Influence on Brain Development?

18 Aug 2023
Caoimhe Lynch and Caitlin Cowan of APC

New research from APC Microbiome Ireland at University College Cork (UCC) highlights the importance of the gut microbiota in shaping brain development. Published in Brain, Behavior and Immunity, a leading international scientific journal, the study shows that disturbing gut microbes early in life has long-lasting impacts on the immune system and the brain.

Our bodies are incredibly complex, and they take time to grow and mature. While growing, our brain rapidly soaks up information about the world around us. This makes children (and young animals) fast learners, but also leaves them vulnerable when things don’t go to plan. The microbes within us also start small, but quickly grow into a complex and diverse community with specialised roles that support the health of our bodies and brains. In the Microbiota-Gut-Brain axis lab of neuroscientist Prof. John Cryan, researchers are interested in the links between the microbiota, the brain, and behaviour. In this mouse study, PhD student Caoimhe Lynch and Marie Curie Postdoctoral Fellow Dr. Caitlin Cowan used antibiotics to wipe out the microbiota at different key stages of early life. The effects on the microbiota were dramatic: it was less diverse, there were blooms of potentially pathogenic bacteria, and decreased levels of short-chain fatty acid producers, which are key messengers in gut-to-brain signalling. Antibiotic-exposed mice also showed changes in immune cells and brain physiology in adolescence, alongside subtle sex- and timing-dependent changes in anxiety-like behaviour.


“When we’re growing, our brains expect to receive certain stimulation, whether that’s the love of a caregiver, the sounds of our native language, or the colours and patterns of the visual world,” says Dr. Cowan. “If we miss out on those signals when we’re young, it can dramatically change the way our brains work. So it makes sense that gut microbes, which we know send signals to the brain, also have this power to change the course of development.”


Overall, these results provide several insights into the importance of the gut microbiota during critical windows of development and the subtle but long-term effects that microbiota perturbations can have on brain physiology and behaviour. However, the researchers caution that it is still early days, and more research is warranted to fully understand the mechanisms behind these effects, how these findings translate to humans and the therapeutic potential of targeting critical windows of microbiota gut-brain axis signalling.


Original publication available here:

This study was funded by SFI Research Centre grant to APC Microbiome Ireland and by a European Union Marie Skłodowska-Curie Individual Fellowship.

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