Acupuncture and Hormone Balance
Chapter 5: Histamine
Histamine is a biogenic amine involved in local immune responses as well as the regulation of many other physiological functions. It may also act as a neurotransmitter, a chemical transmitting information from one neuron to another, but the evidence for histamine serving as a neurotransmitter is still controversial. Histamine can be made from histidine. After histamine is produced, it is either stored or broken down quickly. If the enzymes responsible for deactivating histamine do not function well, it can acumulate in the body, causing allergic reactions such as runny noses, itchy eyes, hives, and diarrhea.
There are four types of histamine receptors, proteins on the surfaces of cell membranes that modulate the bioactivities of cells. The H1 receptor causes blood vessel dilation, bronchoconstriction, contraction of stomach and intestinal muscles, pain, itchiness, and redness and leads to allergic rhinitis and motion sickness. The H2 receptor is mainly involved in gastric acid secretion. Finally, the H3 receptor regulates the release of neurotransmitters such as norepinephrine, histamine, acetylcholine, and serotonin.
If food such as fish is not fresh, histidine from the spoiled food can be converted into histamine, causing severe reactions such as diarrhea, vomiting, and nausea. Most histamine in body tissues is found in the granules of mast cells, which are located in the nose, mouth, feet, internal body surfaces, blood vessels, and basophils (one type of white blood cells). Histamine can also be found in the brain where it may function as a neurotransmitter and in the stomach where it triggers acid release. When a certain type of antibody, IgE, combines with the receptors on mast cells, the mast cells release histamine. Certain drugs such as morphine and tubocurarine can also lead to histamine release from mast cells.
Functions of Histamine
1. Dilating blood vessels to brings more blood flow to local areas, which causes rashes, redness, heat, and pain. This process can help the body clear up damaged tissues or can lead to chronic inflammation or allergies if too much histamine is released for too long. An allergy is an abnormal, acquired sensitivity to certain substances including pollen, drugs, and numerous environmental triggers. Type I hypersensitivity is characterised by the excessive activation of mast cells and basophils by IgE, triggering a systemic inflammatory response that can result in symptoms as benign as a runny nose or as life-threatening as anaphylactic shock and death.
2. Drawing white blood cells to the area of a local injury to clear away damaged tissues and bacteria...