Summary: Gut microbes that metabolize tryptophan release indoles that promote the generation of new neurons in the adult brain, with implications for memory, aging and repair after injury.
Source: Singhealth
Researchers from an international consortium have identified a direct biochemical link between gut microbes and the birth of new nerve cells in the adult brain. The team found that bacteria in the gut that break down tryptophan, an essential amino acid obtained from the diet, produce small signaling molecules called indoles. These indoles trigger molecular pathways that encourage neural stem cells in the hippocampus to differentiate into new neurons.
Led by Professor Sven Pettersson of the National Neuroscience Institute, Singapore, who is also a Visiting Professor at the Lee Kong Chian School of Medicine, Nanyang Technological University, and affiliated with Sunway University in Malaysia, the study provides a clearer mechanistic picture of how the microbiome can influence brain plasticity. The researchers demonstrated that indole-mediated signals activate key regulatory factors known to be essential for adult neurogenesis, especially in the hippocampus, a brain region central to memory formation and learning.
Adult neurogenesis in the hippocampus is associated with cognitive resilience and memory retention. Because memory decline is commonly linked to aging and is an early feature of neurodegenerative conditions such as Alzheimer’s disease, the discovery that gut-derived indoles can promote hippocampal neuron formation opens potential avenues for treatments aimed at preserving memory and restoring neural function after injury.
The research appears in the Proceedings of the National Academy of Sciences (PNAS) and combines molecular biology, neuroscience, microbiology and translational research. The authors emphasize that the indole signals not only stimulate the production of new neurons but also engage regulatory networks known to influence the survival and integration of these neurons into existing hippocampal circuits—factors that are crucial for meaningful cognitive benefit.
“This finding is significant because it provides a mechanistic explanation of how gut-brain communication can result in brain cell renewal,” said Professor Pettersson. “Understanding that gut microbe–produced indoles can stimulate new neuron formation in the adult brain brings us closer to developing interventions that slow age-related memory decline or help replace neurons lost to stroke or spinal cord injury.”
Potential clinical implications discussed by the team include designing drugs that mimic indole activity to promote neurogenesis, developing dietary strategies or functional foods enriched with indole-producing components to support brain health, and exploring targeted microbiome therapies that enhance the population of bacteria capable of beneficial tryptophan metabolism. The researchers stress that these are future directions that will require rigorous testing in clinical studies.
The collaborative study drew expertise from multiple institutions worldwide, reflecting its multidisciplinary nature. Participating institutions included:
- UK Dementia Research Institute at Imperial College London, UK
- Karolinska Institute, Sweden
- NTU Lee Kong Chian School of Medicine, Singapore
- Murdoch University, Australia
- National Neuroscience Institute, Singapore
- Pennsylvania State University, USA
- University of Toronto, Canada
- Sunway University, Malaysia
Co-author Professor Paul Matthews, Centre Director at the UK Dementia Research Institute at Imperial College London and Head of the Department of Brain Sciences, commented on the broader context: “There is growing public and scientific interest in how the microbiome affects brain health. This study adds an important piece to that puzzle and highlights how lifestyle and diet may influence processes related to dementia. It also points to new opportunities for therapies targeting diseases that cause cognitive decline.”
Professor Pettersson added that ongoing work is probing whether indoles influence neuronal development during earlier stages of brain maturation and whether the same signaling pathways could be harnessed to drive neuron generation after acute injuries such as stroke or spinal cord damage. These lines of investigation aim to translate the basic mechanistic insights into interventions that can improve recovery and cognitive function.
About this microbiome and neurogenesis research news
Source: Singhealth
Contact: Margaret Perry – Singhealth
Image: The image is in the public domain
Original Research: The study will appear in PNAS