Endocrine Properties of Microbiota

Microbiota and the macroorganism are in constant interaction with each other. Symbiotic microbiota is implicated in a number of important physiological, biochemical and neuroendocrine functions of the macroorganism. Metabolic activity of microbiota in the gastrointestinal tract (GIT) helps digest food, absorb nutrients, and extract energy. Gut microbiota is involved in the processes of protein, fat and carbohydrate metabolism, gluconeogenesis and glycogenolysis, and also influences the feelings of hunger and satiety. In addition, microbiota is often considered as a sort of metabolically active organ, as the power of gut microbiota metabolic reactions is comparable to that of the liver in the host organism. Microbiota produces autoinducers (quorum-sensing compounds), hormones, neurotransmitters, short-chain fatty acids (SCFA), secondary bile acids, growth factors, gaseous molecules, and many other active substances. Microbial metabolites provide the main communication between the host organism and its microbial community and are of great importance for the normal functioning of the macroorganism since its intrauterine development up to its aging. Moreover, changes in metabolic activity and/or the ratio of different types of microorganisms can lead to various metabolic disorders of the host organism, and vice versa, a metabolic disorder of the host organism can lead to a change in the species composition of the microbiota. This review describes the influence of the microbiota and its metabolites on the neuroendocrine functions of the macroorganism and mechanisms of this influence.