Esophagus: serotoninerdgic regulation

: Serotonin (5-hydroxytryptamine, 5-HT) is a regulatory neurotransmitter and a hormone in the CNS and hole organs, the esophagus including. It is known that serotonin, activating its own receptors, stimulates contractile activity of the esophageal muscles. However, role of different type receptors in the 5-HT induced contractile activity of the esophagus is insufficiently known. The aim : — to determine which type of 5-HT receptors mediate serotonin dependent contractile activity of the esophagus. Material and methods : This is a electromyography study of rat esophagus contractile activity under serotonin stimulation of 5-HT3,4 and 5-HT2,1 receptors separately modulated. The role of different serotonin receptors in the 5-HT induced contractile activity of the esophagus was evaluated by measuring the amplitude and frequency of the slow wave electromyogram (EMG) by the noninvasive microelectrodes imposed on the adventitial layer of the esophagus. Results : Administration of the 5-HT3,4 receptors inhibitors excluded caused by serotonin the increment of EMG activity of the contractile activity of the esophagus. Administration of the 5-HT1,2 receptors inhibitors blocked the serotonin enhanced EMG activity of the esophagus. Conclusion : Our results indicate that serotonin is the important player in the regulation of the rat's esophagus contractility; 5-HT enhancing effect on contraction of the esophageal smooth muscles is mediated through the activation of 5-HT1,2 receptors expressed on the smooth muscle cells, and by activation of 5-HT3,4 receptors expressed on the ganglion neurons.