Gut Microbiota: An Effective Factor in the Human Brain and Behavior

Microorganisms living in the form of symbiosis in the intestine are called gut microbiota. The gut microbiota consists of bacteria, archaea, and eukaryotes. Nonetheless, bacteria are the dominant population of the gut microbiota. The gut microbiota has a beneficial relationship with humans. About 1014 microorganisms inhabit in the intestine, which regulate many physiological functions. In addition to the microbiota effect on the digestive tract, these microorganisms can regulate the function of the brain and the central nervous system. The intestinal nervous system according to the being autonomous and similarity to the central nervous system is known as the second brain. The gut microbiota is an effective factor in the behavior and mood changes and it also prevents the development of the nervous system diseases, such as multiple sclerosis, autism, schizophrenia, Alzheimer, and Parkinson. The gut microbiota regulates the function of the central nervous system through the intestinal nervous system, the production of metabolites, the stimulation of enteroendocrine cells, and the immune system. Inappropriate nutrition, excessive use of antibiotics, stress, anxiety, and depression disturb the balance of microbiota (dysbiosis), which is an important factor in exacerbating the nervous system diseases.