Muscarinic and histamine receptors (mAChR/HR)

Muscarinic and histamine receptors are two distinct families of G protein-coupled receptors (GPCRs) that play critical roles in the central and peripheral nervous systems. Muscarinic receptors (M1-M5) are activated by acetylcholine and mediate parasympathetic effects such as heart rate regulation, glandular secretion, and smooth muscle contraction, as well as cognitive functions in the brain [1, 2]. Histamine receptors (H1-H4) respond to histamine to regulate allergic reactions, gastric acid secretion, and neurotransmitter release [3, 4]. Many pharmacological agents, particularly first-generation antihistamines and atypical antipsychotics, exhibit polypharmacology by binding to both receptor types, often leading to a combination of therapeutic effects and side effects like sedation and dry mouth [5, 6]. Understanding the dual modulation of these receptors is essential for managing conditions ranging from respiratory disorders to psychiatric illnesses [8, 9]. Sources: [1] StatPearls (Physiology, Muscarinic Receptor), [2] UniProt (Muscarinic acetylcholine receptors), [3] StatPearls (Histamine H1 Receptors), [4] IUPHAR/BPS Guide to Pharmacology (Histamine receptors), [5] PubMed (PMID: 23583394), [6] PubChem (Diphenhydramine), [8] FDA (Olanzapine Label), [9] FDA (Amitriptyline Label).

Other names

Muscarinic acetylcholine receptors and histamine receptorsmAChR and HRMuscarinic and histaminergic receptors

Competitive antagonism or inverse agonism of G protein-coupled receptor signaling pathways (Gq, Gi/o, or Gs) triggered by acetylcholine or histamine.