Gut Microbiota Interaction with the Central Nervous System throughout Life

Abstract

During the last years, accumulating evidence has suggested that the gut microbiota plays a key role in the pathogenesis of neurodevelopmental and neurodegenerative diseases via the gut-brain axis. Moreover, current research has helped to elucidate different communication pathways between the gut microbiota and neural tissues (e.g., the vagus nerve, tryptophan production, extrinsic enteric-associated neurons, and short chain fatty acids). On the other hand, altering the composition of gut microbiota promotes a state known as dysbiosis, where the balance between helpful and pathogenic bacteria is disrupted, usually stimulating the last ones. Herein, we summarize selected findings of the recent literature concerning the gut microbiome on the onset and progression of neurodevelopmental and degenerative disorders, and the strategies to modulate its composition in the search for therapeutical approaches, focusing mainly on animal models studies. Readers are advised that this is a young field, based on early studies, that is rapidly growing and being updated as the field advances.

Keywords: dysbiosis; gut microbiota; neurodegeneration; neurodevelopment.

Figure 1

Gut microbiota in health and disease. The gut–brain communication contributes to maintaining a healthy status, which is mainly promoted by some of the factors mentioned on the left side (microbiome diversity and abundance, production of SCFAs, among others). The gut microbiota composition is affected during pathological conditions by some of events mentioned on the right side in red color (dysbiosis and gut produced cytokines, such as interleukin (IL)-17, among others). The relationship between the gut and the brain affects different functions in our body throughout life, such as cognition, neurogenesis, locomotor decline, and so on. The integrity of the gut is disrupted during pathological conditions, increasing intestinal permeability and recruitment of immune cells (right side). In the same line, the composition of dominant microbes during life varies. The use of probiotics, prebiotics, and FMT, among others, has been shown to modulate brain-gut communication, with an optimal time window during postnatal development. SCFAs: short-chain fatty acids, FMT: fecal microbiota transplantation.