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Histamine and Serotonin


Inflammation and Fever 1995;Chapter 1.4.1

Histamine and serotonin

Viera Stvrtinova, Jan Jakubovsky, Ivan Hulin

The most important vasoactive mediators that are stored in mast cell and basophil granules are histamine in man, as well as serotonin or 5-hydroxytryptamine in rodents. They both are also present in human platelets. Histamine is stored in mast cells and basophils largely complexed to mucopolysaccharide (glycosaminoglycans) such as heparin. Histamine has diverse functions including primary, local dilation of small vessels; widespread arteriolar dilatation; local increased vascular permeability by contracting endothelial cells; the contraction of nonvascular smooth muscle; chemotaxis for eosinophils; and blocking T lymphocyte function. A number of different cells of the body have receptors for histamine. These can be of three types -- H1, H2, and H3. The H1 receptors mediate acute vascular effects together with smooth muscle constriction in the bronchi (histamine act as a ''spasmogen'') and the stimulation of eosinophil chemotaxis. In contrast, the H2 receptors mediate a number of anti-inflammatory effects, including the inhibition of eosinophil chemotaxis, but cause the vasodilatation. The H3 receptor is mainly involved in the control of histamine release by different producing cells.

Serotonin is also capable of increasing vascular permeability, dilating capillaries and producing contraction of nonvascular smooth muscle. Most serotonin is stored in the gastrointestinal tract and central nervous system but a large amount is also stored in the dense granules of platelets.

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