Human Histamine H1 receptor (H1 receptor)

The Histamine H1 receptor is a member of the rhodopsin-like G protein-coupled receptor family, encoded by the HRH1 gene. It is activated by the endogenous biogenic amine histamine and is expressed in smooth muscle, vascular endothelium, cardiac tissue, and the central nervous system. Its activation leads to Gq protein recruitment, triggering phospholipase C signaling and downstream effects implicated in inflammation, vasodilation, wakefulness, and allergic reactions. Therapeutically, it is targeted by antihistamines for allergy relief and has a role in modulating inflammatory transcription factor NF-κB. Recent studies also suggest a role as an alternative entry point for SARS-CoV-2, highlighting evolving physiological and therapeutic relevance.

Other names

HRH1H1RHistamine receptor H1Histamine H1-R

Antihistamines act as antagonists or inverse agonists, blocking the binding of histamine to the receptor and thereby inhibiting the activation of Gq protein-mediated downstream signaling; most block movement of key toggle switch residues in the binding pocket to stabilize the inactive conformation. Competitive inhibition of histamine binding. Inhibition of phospholipase C and downstream inositol triphosphate signaling pathways.