Serotonergic mechanisms of regulation of the systemic circulation vessels lumen
Review is devoted to the assessment of the serotonergic mechanisms role in the hemodynamics regulation. The special attention is given to the role of various serotonin receptors involved in the gastrointestinal tract motility regulation, in particular located in the digestive system vessel walls. It is known that serotonin has a dual effect on the vessel lumen, due to the heterogeneity of serotonin receptors, which are part of the vascular wall, and different sensitivity of serotonin receptors. Mechanisms at various levels, from central to local, are able to participate in the serotonergic regulation of the vascular lumen, as well as in motility control. According to our data, in the regulation of the upper gastrointestinal tract motor activity participate 5-HT1B- and 5-HT3-receptors located in the stomach and intestines autonomic ganglia, 5-HT2B-receptors localized on stomach plexus neurons and on small and large intestine smooth muscles; 5-HT4-receptors located on stomach wall smooth muscles and intraorgan intestinal plexus neurons. According to the literature, vascular wall 5-HT2B- and 5-HT7-receptors provide vasodilation, whereas the 5-HT1B/1D-, 5-HT2A- and 5-HT2B-receptors - vasoconstriction. Significance of plasma free serotonin level for hemodynamic, serotonergic mechanisms for the different types vessels diameter changing, the interaction of serotonin receptors with sympathetic nervous system and their possible role in the vascular tone regulation are described, particularly the role of presynaptic 5-HT1B/1D-receptors, which prevent the catecholamines release by vegetative nerves endings, is established. Different points of view on the serotoninergic regulation issue, existing contradictions, as well as areas for further fundamental and practical research are presented.