Histamine receptor (HR) (HR)

Histamine receptors are a class of G protein-coupled receptors (GPCRs) that mediate the biological actions of histamine, a key mediator in inflammation, gastric acid secretion, and neurotransmission (StatPearls, 2023; IUPHAR/BPS, 2023). The family comprises four subtypes (H1, H2, H3, and H4), each exhibiting distinct expression patterns and signaling mechanisms (UniProt, 2024). H1 receptors are primarily involved in allergic responses, smooth muscle contraction, and the regulation of the sleep-wake cycle, while H2 receptors are the principal mediators of histamine-stimulated gastric acid secretion in the stomach (PubMed, 2021). H3 receptors function as presynaptic autoreceptors and heteroreceptors in the central nervous system, modulating the release of histamine and other neurotransmitters like acetylcholine and dopamine. H4 receptors are predominantly found on hematopoietic and immune cells, playing a significant role in inflammatory cell chemotaxis and cytokine production. Clinically, these receptors are targeted by a wide array of drugs, including H1-antihistamines for allergies, H2-blockers for gastrointestinal ulcers, and H3-inverse agonists for sleep disorders (StatPearls, 2023).

Other names

Histaminergic receptorsH-receptorsHistamine receptors

Drugs targeting histamine receptors primarily act as inverse agonists or competitive antagonists to inhibit the signaling pathways activated by endogenous histamine (IUPHAR/BPS, 2023). H1-receptor antagonists interfere with histamine-induced vascular permeability and sensory nerve stimulation, effectively treating allergic symptoms. H2-receptor antagonists block the H2-mediated activation of adenylate cyclase in parietal cells, thereby reducing gastric acid secretion (StatPearls, 2023). H3-receptor ligands, such as pitolisant, act as inverse agonists to increase the synaptic levels of histamine and other excitatory neurotransmitters in the brain to treat narcolepsy (PubMed, 2021).