Histamine Receptor

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. The H1 receptor is a histamine receptor belonging to the family of Rhodopsin-like G-protein-coupled receptors. This receptor, which is activated by the biogenic amine histamine, is expressed throughout the body, to be specific, in smooth muscles, on vascular endothelial cells, in the heart, and in the central nervous system. H2 receptors are positively coupled to adenylate cyclase via Gs. It is a potent stimulant of cAMP production, which leads to activation of Protein Kinase A. Histamine H3 receptors are expressed in the central nervous system and to a lesser extent the peripheral nervous system, where they act asautoreceptors in presynaptic histaminergic neurons, and also control histamine turnover by feedback inhibition of histamine synthesis and release. The Histamine H4 receptor has been shown to be involved in mediating eosinophil shape change and mast cell chemotaxis.