Reference Number: 75
Neurodevelopment is a complex process governed by both intrinsic and extrinsic signals. While historically studied by researching the brain, inputs from the periphery impact many neurological conditions. Indeed, emerging data suggests communication between the gut and the brain in anxiety, depression, cognition and autism spectrum disorder (ASD). The development of a healthy, functional brain depends on key pre- and post-natal events that integrate environmental cues, such as molecular signals from the gut. These cues largely originate from the microbiome, the consortium of symbiotic bacteria that reside within all animals. Research over the past few years reveals that the gut microbiome plays a role in basic neurogenerative processes such as the formation of the blood-brain-barrier, myelination, neurogenesis, and microglia maturation, and also modulates many aspects of animal behavior. Herein, we discuss the biological intersection of neurodevelopment and the microbiome, and explore the hypothesis that gut bacteria are integral contributors to development and function of the nervous system, and the balance between mental health and disease.
SIGNIFICANCE OF THIS STUDY
The microbiome plays a significant role in the well-being of its host. While much of the research on this topic to date has demonstrated that different bacterial populations are associated with certain clinical conditions, it is unclear for the most part whether these differences are causative, promote and/or enhance disease, or instead are a consequence of otherwise unrelated pathophysiology. Future research should tackle this challenging question in order to understand the intricate interaction between mammals (or any other host) and their associated microbial community. We must not continue exercises in simply cataloging bacterial populations. Rather, we must extend this foundational research approach to test the functional and ecological roles that a given microbial population plays, as well as decipher the physiological effects individual bacteria or consortia of bacteria have on their animal hosts. It is of importance to address questions of cause and effect: are changes in the microbiome underlying the pathophysiology or are they a result thereof? Are the effects on behavior direct, or a result of other fundamental physiological changes? Are there defined microbial features that are necessary and sufficient to support proper neurodevelopment and prevent neurodegeneration? The use of animal models is a great tool for studying basic processes in health and disease. However, we must use caution in extrapolating results to the human condition, and strive to use preclinical findings as one of several approaches to inform human health and disease.While research on the gut-brain axis is still in relative infancy, certain basic rules have begun to emerge. It appears as though specific neurological pathways evolved to respond to the effect of microbial population, while others are unaffected by microbiome “instruction” and subject to purely genomic or other environmental cues. Interaction with host-associated microbial communities, either directly via microbial metabolites or indirectly by the immune, metabolic or endocrine systems, can supply the nervous system with real-time information about the environment. These cues converge to control basic developmental processes in the brain such as barrier function, immune surveillance, and neurogenesis. The mechanistic understanding of how different microbial populations, beneficial or pathogenic, govern these and other functions related to health and disease holds promise in the diagnosis, treatment, and prevention of specific neuropathologies. Determining how a microbiome, changing with Westernization and other environmental factors, impacts a human population with growing rates of neurodevelopmental disorders and increasing life expectancy represents an urgent challenge to biomedical research, and to society.