Other Definitions
histamine (dict)
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HistamineHistamine is a monoamine chemical involved in local immune responses. Chemical properties Chemically, histamine is 2-(4-imidazolyl)ethylamine and has the formula C5H9N3. Histamine is synthesized by the decarboxylation of the amino acid histidine, a reaction catalyzed by the enzyme L-histidine decarboxylase. It is a hydrophilic vasoactive amine (thus the name). Some forms of food poisoning are due to conversion of histidine into histamine in spoiled foodstuffs, such as fish. Physiology Release of histamine is associated with allergic reactions, as it causes both an inflammatory response and a contraction of smooth muscle tissue. Histamine is released by mast cells primarily when they degranulate due to binding of allergens to IgE antibodies on the mast cell. Histamine also regulates gastric acid production. It may also may function as a neurotransmitter in the central nervous system. Histamine mediates its effects via histamine receptors, which are classified into types: See also
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