Targeting the Microbiota-Gut-Brain Axis: Emerging Nanomedicine Approaches for Neurodegenerative Diseases

The microbiota-gut-brain axis (MGBA) is a bidirectional relationship between the gut microbiota (GM) and the brain, where the GM affects the gastrointestinal tract (GIT) and the central nervous system (CNS), and vice versa. Microbiotas are important for several vital body processes, including metabolism, immunity, and homeostasis. The MGBA has three main pathways: the vagal nerve mechanism, the immune-related mechanism, and the neuroendocrine mechanism. GM imbalance, known as dysbiosis, affects the GIT, the brain, and the CNS. Furthermore, dysbiosis is linked to several neurological disorders such as Alzheimer's (AD), Parkinson's (PD), depression, autism spectrum disorder (ASD), and multiple sclerosis (MS). Studying MGBA gives researchers new therapeutic ideas using microbiota. Using special diets rich in fiber and probiotics, in addition to fecal microbiota transplantation (FMT), is being studied as a new therapy for MGBA. From the point of view that these therapeutic interventions maintain microbiota imbalance, which in turn will affect the brain and can relieve the neurological disorders caused by dysbiosis and MGBA.