Category: Autacoids and their antagonists
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Prostaglandins:
They were named so because of their presumed origin from the prostate gland. Human seminalfluid is the richest known source, but they are also present in various tissues. Theprostaglandins are synthesized from polyunsaturated fatty acids at their sites of action. PG E2and PG F2 are the two main prostaglandins. They are released in the body…
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Hydroxytreptamine (Serotonin)
It is widely distributed in plants and animals. Highest concentration in mammals is found in thepineal gland, acting as a precursor for melatonin. It is synthesized from the amino acidtryptophan and acts on several types of receptors.Pharmacolocial Actions:5-HT causes constriction of renal, splanchnic, meningeal, and pulmonary arteries and veins andvenules, but dilatation of the blood…
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Histamine
It is a potent tissue amine widely distributed in plant and animal tissues and in the venoms ofbees. In man, it is formed by decarboxylation of histidine and major portion is stored in mastcells and basophils.Mechanisms of Action: It acts on 2 major types of receptorsa. Stimulation of H1 receptors results in smooth muscle contraction,…
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INTRODUCTION
“Autacoids” (Greek “self-remedy”) is a collective term for various endogenous peptides,prostaglandins, leukotrienes, and cytokines. These are sometimes also called local hormones.They play important roles in physiologic processes and also have several pharmacologicalsignificances.