The Role of Gut Microbiota and Gut-Brain Interplay in Selected Diseases of the Central Nervous System

Abstract

The gut microbiome has attracted increasing attention from researchers in recent years. The microbiota can have a specific and complex cross-talk with the host, particularly with the central nervous system (CNS), creating the so-called "gut-brain axis". Communication between the gut, intestinal microbiota, and the brain involves the secretion of various metabolites such as short-chain fatty acids (SCFAs), structural components of bacteria, and signaling molecules. Moreover, an imbalance in the gut microbiota composition modulates the immune system and function of tissue barriers such as the blood-brain barrier (BBB). Therefore, the aim of this literature review is to describe how the gut-brain interplay may contribute to the development of various neurological disorders, combining the fields of gastroenterology and neuroscience. We present recent findings concerning the effect of the altered microbiota on neurodegeneration and neuroinflammation, including Alzheimer's and Parkinson's diseases, as well as multiple sclerosis. Moreover, the impact of the pathological shift in the microbiome on selected neuropsychological disorders, i.e., major depressive disorders (MDD) and autism spectrum disorder (ASD), is also discussed. Future research on the effect of balanced gut microbiota composition on the gut-brain axis would help to identify new potential opportunities for therapeutic interventions in the presented diseases.

Keywords: central nervous system; dysbiosis; enteric nervous system; gut microbiota; gut–brain axis; neurodegeneration; neuroinflammation; neuropsychiatric disorders.

Figure 1

Pathways between the intestines and the central nervous system (CNS). Figure illustrates how the gut microbiota can interact with CNS through several pathways. Firstly, through produced metabolites such as short-chain fatty acids (SCFAs) [38]; secondly, directly with neurotransmitters for example dopamine and serotonin [39,40,41]; and lastly, indirectly influencing the release of enteric hormones [44,45,46].

Figure 2

Schematic description of disturbances in the intestinal microbiota and diseases of the CNS. The figure depicts major factors, such as stress [29], diet [21], infections, and antibiotic intake [28], which can promote dysbiosis in the gut microbiota. Changes in the composition of the microbiome lead to gut permeability, influencing systemic inflammation and, as a result, may induce diseases of the CNS.