5-hydroxytryptamine receptor 3 (5-HT3R) (5-HT3R)

The 5-hydroxytryptamine receptor 3 (5-HT3R) is the only member of the serotonin receptor family that functions as a ligand-gated ion channel rather than a G protein-coupled receptor (IUPHAR/BPS Guide to Pharmacology) [1]. It belongs to the Cys-loop superfamily of receptors, which also includes nicotinic acetylcholine and GABA-A receptors (Wikipedia) [2]. Upon binding serotonin, the 5-HT3R opens a non-selective cation channel, leading to rapid depolarization of the post-synaptic membrane (UniProt) [3]. These receptors are primarily located in the peripheral and central nervous systems, particularly in the area postrema and the gastrointestinal tract, where they play a critical role in the emetic reflex (StatPearls) [4]. Pharmacologically, 5-HT3R antagonists, known as "setrons," are widely used as potent antiemetic agents to manage nausea and vomiting associated with cancer chemotherapy and surgery (PubMed) [5]. Additionally, they are utilized in treating certain gastrointestinal disorders like irritable bowel syndrome (NIH) [6]. The receptor is a pentameric complex, most commonly composed of HTR3A and HTR3B subunits, which influence its conductance and pharmacological profile (NCBI) [7].

Other names

5-HT3 receptorSerotonin-gated ion channel5-HT3Serotonin receptor 35-hydroxytryptamine-3 receptor

Competitive antagonism of the ligand-gated ion channel, which inhibits the influx of cations (Na+, K+, Ca2+) and prevents the depolarization of neurons in the chemoreceptor trigger zone and the gastrointestinal tract.