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What Are the Functions of Histamine?

Histamine is a biological amine such as serotonin, tryptamine or acetylcholine. This amine triggers pathways to the brain by binding with histamine receptors H1, H2, H3 and H4, which belong to the receptor family which is coupled with G proteins. Expressions of the H1-H4 receptors include endothelial, epithelial and mesodermal cells. Histamine has various physiological functions within the human body.

  1. Inflammatory Response

    • The inflammatory response of histamine is what causes allergic reactions such as swelling. Allergies are a response from the immune system to innocuous substances such as pollen and dust. Here the immune system calls on an immunoglobulin molecule which binds with antigen and triggers a mast cell reaction. The mast cell reaction is to release histamine, which then directly causes an inflammatory reaction by increasing the permeability of blood vessels near the site of the mast cell activity. Blood fluids then come into the area and cause swelling.

      When histamine is released and increases the permeability of blood cells, it also affects the function of some leukocytes in the area where the mast cell was triggered. What histamine does to the leukocytes is cause them to release cytokines, which is an inflammatory mediator to help control the swelling. This is an indirect inflammatory reaction to histamine. Both direct and indirect inflammatory responses are your body's way of fighting off innocuous substances.

    Smooth Muscle Constriction

    • Smooth muscle constriction is one of the most dangerous allergic reactions. Asthma patients and people who have allergic reactions to certain foods, insect bites or bee stings may have smooth muscle constrictions up to and including the complete closure of the trachea. This is caused by a chemical reaction which arises from the mixture of histamine and other chemicals in your body.

      Despite the life-threatening seriousness of this histamine reaction, constriction of the smooth muscles, particularly in the respiratory system, is a way for your lungs to defend themselves from taking in the potentially dangerous substances which have caused the allergic reaction. Taking antihistamine medications helps reduce and/or control histamine effects such as inflammatory response and smooth muscle constrictions.

    Organogenesis

    • Organogenesis is what scientists call the development of organs. Histamine has been shown to be involved in the creation of certain organs such as the brain, breasts and kidneys. Though the function of histamine in organogenesis is not completely known, it has been shown that histamine levels are drastically changed throughout the reproductive stages of pregnancy, according to Farhad Vesuna and Venu Raman of the Department of Radiology at John Hopkins University.

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