5-Hydroxytryptamine receptor 3AB (5-HT3AB) (5-HT3AB)

The 5-hydroxytryptamine receptor 3AB (5-HT3AB) is a heteromeric ligand-gated ion channel belonging to the Cys-loop superfamily (IUPHAR/BPS Guide to PHARMACOLOGY). It is uniquely distinguished from other serotonin receptors by its function as a non-selective cation channel rather than a G protein-coupled receptor (UniProt P46098). The receptor is composed of 5-HT3A and 5-HT3B subunits, a configuration that significantly increases single-channel conductance and alters pharmacological sensitivity compared to homomeric 5-HT3A receptors (PubMed: 10359340). It is highly expressed in the area postrema of the brainstem and on vagal nerve terminals in the gastrointestinal tract, where it plays a pivotal role in the emetic reflex and gut motility (StatPearls: 5HT3 Antagonists). Clinically, 5-HT3AB is a primary target for antiemetic drugs, particularly for patients undergoing chemotherapy or surgery (PubMed: 25108303). Antagonists of this receptor, such as alosetron, are also utilized in the management of diarrhea-predominant irritable bowel syndrome due to their ability to slow colonic transit and reduce visceral pain (PubMed: 15184693). Genetic variations in the HTR3B subunit have been linked to differences in patient response to antiemetic therapy, highlighting its importance in personalized medicine (PubMed: 19116922). Safety concerns for drugs targeting this receptor include potential QT interval prolongation and gastrointestinal complications like ischemic colitis (FDA: Lotronex Label).

Other names

Serotonin receptor 3AB5-HT3AB receptorHTR3A/HTR3B heteromeric receptor5-hydroxytryptamine receptor subunit 3A/3B complex

Competitive antagonism of the 5-HT3 receptor complex, which inhibits the opening of the non-selective cation channel, thereby preventing depolarization of neurons in the chemoreceptor trigger zone and vagal afferents (StatPearls: 5HT3 Antagonists).