INTERACTION OF THE SYMBIOTIC MICROBIOTA OF THE GASTRO-INTESTINAL TRACT WITH THE NERVOUS SYSTEM OF THE HOST ORGANISM

Abstract

Symbiotic microorganisms inhabit a wide variety of niches in the human organism. Of paramount importance is the microbiota of the gastro-intestinal (GI) tract, especially of its distal part (the colon). Bidirectional signal exchange proceeds within the microbiota-host system, and diverse microbial metabolites modify the functions of the nervous system via metabolic, genetic, and neuroendocrine pathways. Increasing attention is currently given to the role of the GI microbiota in terms of the host's physical and mental health; therefore, it has been suggested to replace the widely used term gut-brain axis with the new term microbiota-gut-brain axis. The GI microbiota directly interacts with the enteric nervous system (ENS) that represents a partly autonomous subdivision of the nervous system. An important role is also played by the GI tract-innervating vagus nerve. In addition, the influence of the microbiota on the nervous system can be mediated by the immune system. The microbiota impact on the nervous system of the host results in significant alterations in the host's behavior, mood, and even taste. In the literature, there is evidence that neurological and psychological diseases are linked to microecological disorders (dysbioses) in the GI tract. In particular, dysbioses with manifest GI symptoms are often accompanied by serious brain problems.