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.
Histamine is an organic nitrogenous compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter.
Terfenadine ((±)-Terfenadine) is a potent open-channel blocker of hERG with an IC50 of 204 nM. Terfenadine, an H1 histamine receptor antagonist, acts as a potent apoptosis inducer in melanoma cells through modulation of Ca2+ homeostasis. Terfenadine induces ROS-dependent apoptosis, simultaneously activates Caspase-4, -2, -9.
Carebastine is the active metabolite of Ebastine. Carebastine is a histamine H1 receptor antagonist. Carebastine inhibits VEGF-induced HUVEC and HPAEC proliferation, migration and angiogenesis in a dose-dependent manner. Carebastine suppresses the expression of macrophage migration inhibitory factor.
LML134 (compound 18b) is an orally active and high selective Histamine 3 receptor (H3R) inverse agonist with Kis of 0.3 nM and 12 nM for hH3R cAMP and hH3R bdg. LML134 penetrates the brain rapidly, leading to high H3R occupancy, and disengages its target with a fast kinetic profile. LML134 is for the treatment of excessive sleep disorders.
Levocetirizine dihydrochloride ((R)-Cetirizine dihydrochloride) is a third-generation peripheral H1-receptor antagonist. Levocetirizine dihydrochloride is an antihistaminic agent which is the R-enantiomer of Cetirizine. Levocetirizine dihydrochloride has a higher affinity for the histamine H1-receptor than (S)-Cetirizine and can effectively treat allergic rhinitis and chronic idiopathic urticaria.
Fexofenadine hydrochloride (MDL-16455 hydrochloride), a H1R antagonist, is an anti-allergic agent used in seasonal allergic rhinitis and chronic idiopathic urticarial (person aged ≥16 years).
Latrepirdine dihydrochloride is a neuroactive compound with antagonist activity at histaminergic, α-adrenergic, and serotonergic receptors. Latrepirdine stimulates amyloid precursor protein (APP) catabolism and amyloid-β (Aβ) secretion.
Cetirizine dihydrochloride, a second-generation antihistamine, is a major metabolite of hydroxyzine, and a racemic selective H1 receptor inverse agonist used in the treatment of allergies, hay fever, angioedema, and urticaria.
Mepyramine maleate, a first generation antihistamine, is an antagonist of histamine H1 receptor, with Kds of 0.8 nM, 5200 nM and >3000 nM for H1, H2, and H3 receptor, respectively, and a pKd of 9.4 for H1 receptor.
Perphenazine is a typical antipsychotic drug, inhibits 5-HT2Areceptor, Alpha-1A adrenergic receptor, Dopamine receptor D2/D3, D2L receptor, and Histamine H1 receptor, with Ki values of 5.6, 10, 0.765/0.13, 3.4, and 8 nM, respectively.
