Histamine H1 Receptor

Inflammation in the body, as a result of any allergen entering the human body, is known to be triggered by Histamine H1 receptor. The human body responds in the form of inflammation to foreign allergens by releasing histamines (histamine is derived from the amino acid histidine, and is synthesised in all tissues. However, it is particularly abundant in skin, lung and the gastrointestinal tract), which are captured by the histamine receptors. The histamines are received by the histamine receptors H1, H2, H3, or H4, and then cause appropriate and respective reactions (acute allergic inflammation, in case of histamine H1 receptor). Each histamine receptor has its own specific location and function; H2 receptors are located in gastric parietal cells, H3 receptors in the nervous system, and H4 receptors in the immune system.

The Histamine H1 receptor is a member of the G protein coupled receptors (protein receptors that sense molecules, activate signal transduction pathways that lead to cellular response) and are located throughout the human body. The Histamine H1 receptors are located specifically in smooth muscles (type of involuntary muscles) and vascular endothelial cells (cells which line the inner walls of blood and lymphatic vessels, and are in direct contact with the blood).

As stated earlier, Histamine H1 receptors are responsible for the acute allergic reaction taking place in the human body. By preventing the released histamine from binding with the Histamine H1 receptor, it is possible to stop the inflammation or allergic reaction. The substances and compounds used for this purpose are antihistamines or in the case of Histamine H1 receptors, Histamine H1 receptor antagonists. Histamine H1 receptor antagonists have been widely used in cold pills, asthma and many other chronic diseases, which are triggered due to allergic reactions. Histamine H1 receptor antagonists, in particular, have proved to be extremely effective in controlling sneezing, pruritus and rhinorrhea ; the symptoms associated with respiratory allergies and rhinitis.

Studying histamines gives an insight into how the human body reacts to when threatened by foreign allergens, how it regulates the immune system, modulates neurotransmission and secretes gastric acid.