Histamine receptor

The histamine receptors are a class of G protein–coupled receptors with histamine as their endogenous ligand.

There are four known histamine receptors:

• H₁ receptor
• H₂ receptor
• H₃ receptor
• H₄ receptor

Comparison

Histamine receptors

Receptor	Mechanism	Function	Antagonists
H1	Gq	ileum contraction modulate circadian cycle itching systemic vasodilatation bronchoconstriction (allergy-induced asthma)	H1-receptor antagonists Diphenhydramine Loratadine Cetirizine Fexofenadine Clemastine
H2	Gs ↑ Ca2+	speed up sinus rhythm Stimulation of gastric acid secretion Smooth muscle relaxation Inhibit antibody synthesis, T-cell proliferation and cytokine production	H2-receptor antagonists Ranitidine Cimetidine Famotidine Nizatidine
H3	Gi	Decrease Acetylcholine, Serotonin and Norepinephrine Neurotransmitter release in CNS Presynaptic autoreceptors	H3-receptor antagonists ABT-239 Ciproxifan Clobenpropit Thioperamide
H4	Gi	mediate mast cell chemotaxis.	H4-receptor antagonists Thioperamide JNJ 7777120

There are several splice variants of H₃ present in various species. Though all of the receptors are 7-transmembrane g protein coupled receptors, H₁ and H₂ are quite different from H₃ and H₄ in their activities. H₁ causes an increase in PIP₂ hydrolysis, H2 stimulates gastric acid secretion, and H3 mediates feedback inhibition of histamine.

External links

• Holger Stark: Histamine Receptors, BIOTREND Reviews No. 01, November 2007
• The Histamine Receptor
• Histamine Receptor at the US National Library of Medicine Medical Subject Headings (MeSH)