Thehistamine receptors are a class ofG protein–coupled receptors which bindhistamine as their primaryendogenousligand.[1][2] Histamine is aneurotransmitter involved in various physiological processes. There are four main types of histamine receptors: H1, H2, H3, and H4. H1 receptors are linked to allergic responses, H2 to gastric acid regulation, H3 to neurotransmitter release modulation, and H4 to immune system function.
There are four known histamine receptors:
H1 receptor – Primarily located onsmooth muscle cells, endothelial cells, and neurons. Activation of H1 receptors mediates various responses, including smooth muscle contraction (leading to bronchoconstriction, intestinal cramping), increased vascular permeability (resulting inedema), and stimulation of sensory nerve endings (causing itching and pain). H1 antagonists, commonly known as antihistamines, are used to alleviate symptoms of allergies and allergic reactions.[3]
H2 receptor – Found mainly in the stomach lining (parietal cells), H2 receptors regulate gastric acid secretion by stimulating the production of hydrochloric acid. H2 antagonists (H2 blockers) are used to reduce stomach acid production and treat conditions likegastroesophageal reflux disease (GERD) and peptic ulcers.[3]
H3 receptor – Predominantly located in the central nervous system (CNS), particularly in regions associated with neurotransmitter release and modulation. H3 receptors act as presynaptic autoreceptors and heteroreceptors, regulating the release of neurotransmitters such as dopamine, serotonin,norepinephrine, and acetylcholine. Modulation of H3 receptors is being explored as a potential target for various neurological and psychiatric disorders.[4]
H4 receptor – Initially discovered on immune cells, particularly mast cells, eosinophils, and T cells, H4 receptors are involved in immune responses, includingchemotaxis (cellular movement in response to chemical signals) and cytokine production. These receptors play a role in inflammation and allergic reactions. Research on H4 receptors is ongoing to better understand their involvement in immune-related disorders and to develop potential therapeutic interventions.[5]
^Ravhe IS, Krishnan A, Manoj N (January 2021). "Evolutionary history of histamine receptors: Early vertebrate origin and expansion of the H3-H4 subtypes".Molecular Phylogenetics and Evolution.154 106989.doi:10.1016/j.ympev.2020.106989.PMID33059072.
^abSimons FE (November 2004). "Advances in H1-antihistamines".The New England Journal of Medicine.351 (21):2203–2217.doi:10.1056/NEJMra033121.PMID15548781.S
^Haas H, Panula P (February 2003). "The role of histamine and the tuberomamillary nucleus in the nervous system".Nature Reviews. Neuroscience.4 (2):121–130.doi:10.1038/nrn1034.PMID12563283.
