Allergic to Dogs and Allergies in Dogs Resource

Histamine and Allergies

What is Histamine?

Even people who do not suffer from allergies will more than likely have come across the term antihistamines and associate it with treating hay fever and bee or wasp stings. As the term suggests, an anti-histamine counteracts the action of histamine, but what is the chemical histamine and how does it play a role in allergies?

Histamine is one of several inflammatory chemical mediators involved in an allergy response.

Histamine and Allergies

With regard to the article, Allergy Response – Sequence of Events of an Allergy Reaction, the following relates specifically to histamine:

  • Following the production of sensitized cells, subsequent exposure to the allergen leads to specialized cells (mast and basophiles) releasing the chemical histamine (degranulation). The neurotransmitter histamine is stored in the mast and basophile cells having been manufactured as a result of enzymes (histidine decarboxylase) reacting with the amino acid histidine.
  • Histamine can then bind with 4 potential receptors H1 through to H4.
    In particular, H1 receptors are found throughout the body (central nervous system, endothelium, smooth muscle) and are associated with many of the symptoms and inflammatory aspects observed in an allergic reaction, such as:
    • Allergic rhinitis and cold-like symptoms such as sneezing, stuffy or runny nose and excessive mucus production in the nasal region.
    • Constricting the smooth bronchial tube muscles which contribute to the manifestations of asthma symptoms.
    • Dilation of small blood vessels allowing fluid leakage resulting in itchy skin and hives.
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