Interactions between gut microorganisms and brain

Intestinal microbiota communicates with brain via various cooperating pathways including neuronal, endocrine and immune. Pathogenic and commensal bacteria produce great amounts of neurotransmitters and various other metabolites which can interact with brain. Presence of bacteria can also induce immune system response which can influence brain through cytokines and other mediators. Last but not least the communication can be mediated through nerves, especially the vagus nerve. The brain can influence the intestines through sympathic and parasympathic efferent nerves and through hormones. Gut colonization by nonpathogenic commensal bacteria is crucial for proper brain development. If this doesn't happen in certain period psychiatric disorders such as depression or autism can occur later in life. Various pathological conditions might be ameliorated or fully reversed by administration of probiotic bacteria. Aim of this thesis is to briefly review factors influencing gut microbiota, its influence on the brain development and the role of probiotics in the therapy of intestinal and psychiatric diseases. Keywords: gut microbiome, brain, neuroendocrine regulation, probiotic, neurotransmitte