The role of microbiota-gut-brain axis in neurodegenerative diseases: biochemical and therapeutic aspects

The enteric nervous system (ENS) is considered by some authors as the second human brain, given its fundamental role in the regulation process of the central nervous system (CNS). Recent data from scientific literature have shown the existence of close bidirectional communication between the gut microbiota and the CNS, influencing physiological and biochemical changes related to cognition, emotion, behavior, anxiety, depressive symptoms, and stress. Furthermore, the existence of mediators in the connection between intestinal microorganisms and the CNS is evident, which includes neural networks, signaling, immune, and endocrine responses. However, the mechanisms underlying the effects of gut microbiota on brain processes still need to be determined. Therefore, understanding the relationship between the gut and neurodegenerative diseases (NDs) is essential for developing effective prophylactic alternatives and disease-modifying drugs that can prevent or slow the progression of such diseases. Herein, this short review aimed to present the most recent data from the scientific literature associated with the physiological, biochemical, and cellular aspects involved in the interrelationship between the gut-brain axis and NDs, discussing the role of the intestinal microbiota, and its relationship with CNS disorders.