Autacoids Serotonin

The autacoids comprise histamine, serotonin, angiotensin, neurotensin, NO (nitric oxide), kinins, platelet-activating factor, endothelins and the four families of traditional eicosanoids - the leukotrienes and three types of prostanoids i.e. prostaglandins, prostacyclins, and thromboxanes. Several other natural occurring molecules are sometimes called eicos-anoid, including the hepoxilins, resolvins, isofurans, isoprostanes, lipoxins, epoxyeicosatrienoic acids (EETs) and some endocannabinoids. However, not... 

In fact, a medley of substances (autacoids), kinins, prostaglandins, leukotrienes, histamine, endorphins, serotonin, vasopressin, has been implicated. In endotoxic shock, the toxin also induces synthesis of nitric oxide, the endogenous vasodilator, in several types of cells other than the endothelial cells which are normally its main source. 

Histamine acts as a local hormone (autacoid) similarly to serotonin or prostaglandins, i.e. it acts within the immediate vicinity of its site of release. In the context of gastric secretion, for example, stimulation of receptors on the histamine-containing cell causes release of histamine which in turn acts on receptors on parietal cells which then secrete hydrogen ions (see Gastric secretion, Ch. 31). 

Serotonin (5-hydroxytryptamine, 5HT) is an autacoid synthesized and stored in GI cells and neurons and in platelets. Metabolized by MAO type A, its metabolite 5-hydroxyinolacetic acid (5HIAA) is a marker for carcinoid. 

Autacoids Endogenous substances with compiex physioiogic and pathophysioiogic functions commoniy interpreted to inciude histamine, serotonin, prostagiandins, and vasoactive peptides... 

Autacoids are endogenous molecules with powerful pharmacologic effects but poorly defined physiologic roles. Histamine and serotonin (5-hydroxytryptamine 5-HT) are two of the most important autacoids. Both are synthesized in the body from amino acid precursors and then eliminated by amine oxidation the pathways of synthesis and metabolism are very similar to those used for catecholamine synthesis and metabolism. The ergot alkaloids are a heterogeneous group of drugs that interact with serotonin receptors, dopamine receptors, and alpha receptors. They are included in this chapter because of their effects on serotonin receptors and on smooth muscle. 

Melmon, K. L., 1981, The endocrinologic function of selected autacoids Catecholamines, acetylcholine, serotonin, and histamine, in Textbook of Endocrinology (R. H. Williams, ed.), pp. 514-588, W. B. Saunders, Philadelphia. 

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