Microbiome and gut-brain axis affecting stress behavior

Abstract

In context to the neurological system, the function and evolution of host physiology as influenced by intestinal microbiota are of great interest. It has long been understood how crucial the gut-brain axis is in controlling reactions to stress. More recently, the microbiota has become a crucial component in this gut-brain regulation, particularly under stressful circumstances brought on by actual or perceived homeostatic strain. The gut microbiota seems to have an impact on the growth of emotional behavior, stress- and pain-modulation systems, and brain neurotransmitter systems, according to studies employing mice raised in a germ-free environment. Current evidence suggests that multiple mechanisms, including neural pathways and immune signaling, may be involved in gut microbiota–to–brain signaling and that the brain can in turn alter microbial composition and behavior via the autonomic nervous system. The gut microbiota has been implicated in a variety of stress-related conditions including anxiety, depression, and irritable bowel syndrome, although this is largely based on animal studies or correlative analysis in patient populations. Additional research in humans is sorely needed to reveal the relative impact and causal contribution of the microbiome to stress-related disorders. We will briefly explore the crucial aspect of this axis in this review, as well as the methodological issues that have been raised in previous attempts to define normal microbiota and chronicle its temporal development.