SIGNAL-TRANSDUCTION PATHWAYS FOR SEROTONIN AS AN INTESTINAL SECRETAGOGUE

This review presents a signal transduction pathways for serotonin (5-h ydroxytryptamine, 5-HT) as an intestinal secretagogue and some recentl y published related findings. 5-HT is a secretagogue in the small and large intestine of all studied species including pig and man. 5-HT med iates intestinal secretion through activation of at least the epitheli al 5-HT2, and neuronal 5-HT3, and 5-HT4 receptors in the submucosal pl exus, including a reflex are. 5-HT activates both a cholinergic and a non cholinergic pathway in its secretory response. Intracellular media tors include at least eicosanoids (prostaglandin E-2), calcium, phosph oinositols (1,4,5-inositol trisphosphate) and maybe nitric oxide and c yclic nucleotides. Pig small intestine appears to be an appropriate mo del for the human small intestine with respect to the signal transduct ion pathways for 5-HT as an intestinal secretagogue. Species and segme ntal differences in the signal transduction pathways for 5-HT as an in testinal secretagogues are discussed together with related news on 5-H T receptors, 5-HT antagonists in clinical use, the enteric nervous sys tem, and intracellular mediators. (C) 1997 Elsevier Science Inc.