Histamine is the contributing factor in some common allergic reactions and other bodily functions. The release of histamine leads to an inflammatory response by the body and also leads to the constriction of smooth muscle surrounding the airways. It can also cause common allergy symptoms, such as nasal congestion, sneezing, and the production of gastric acid.
Various types of cells within the human body produce this molecule. This includes mast cells and basophils, a type of white blood cell. Histamine produced by mast cells is typically found in areas such as the nasal passages, mouth, and blood vessels. Basophil produced histamines are most commonly found in various tissues of the human body, where its main role is to serve as a neurotransmitter. Histamine is also found in the skin and gastrointestinal tract.
Four different receptors exist in the body, and each is responsible for a different reaction when the molecule binds to them. The H1 receptors are located in smooth muscle and are responsible for allergic response, while H2 receptors are located in the parietal cells of the gastrointestinal tract and are responsible for gastric acid secretion. H3 is responsible for neurotransmission in the central nervous system, and H4 is responsible for the immune response of mast cells.
When exposed to an allergen, a person may experience an allergic reaction. Typical reactions include hives and itchy skin. This reaction is due to the binding of the molecule to tissue mast cells.
More severe allergic reactions can occur when the molecule binds to H1 receptors. Leading to the contraction of smooth muscle located in the airways, histamine can cause difficulty breathing and possibly death. When this occurs, immediate medical attention is needed to control the allergic reaction and counteract the effect of histamine’s release on the body.
Other allergy symptoms are also attributed to the release of the molecule during an immune response. This includes the swelling of the nasal passages and production of nasal congestion. Sneezing is another allergy symptom attributed to the molecule’s release.
Beyond the immune responses attributed to it, other bodily functions depend on the molecule for proper functioning. This includes the function of histamine in the brain. Research indicates that the molecule is important in alertness and cognitive function. Another function of the molecule includes secretion of gastric acid in the stomach.
Medications can be used to handle the various responses. Antihistamines are commonly prescribed or recommended for allergic reactions. Antagonists to prohibit the binding of histamine to H2 receptors and limit gastric acid production are also available.