5-hydroxytryptamine type 3 receptor (5-HT3 receptor)

The 5-hydroxytryptamine type 3 receptor (5-HT3 receptor) is a pentameric ligand-gated ion channel that mediates fast excitatory neurotransmission in the central and peripheral nervous systems in response to serotonin (5-hydroxytryptamine). Unlike other serotonin receptors, which are G protein-coupled, the 5-HT3 receptor is a cation-selective channel belonging to the Cys-loop superfamily, structurally related to the nicotinic acetylcholine receptor. Functional receptors are usually composed of five subunits (either all 5-HT3A or a mix of 5-HT3A with 5-HT3B, C, D, or E), arranged around a central ion-conducting pore. This receptor is widely distributed in areas implicated in emesis, pain, anxiety, reward, and gastrointestinal motility. Therapeutic antagonists, collectively known as setrons, are the mainstay for preventing and treating chemotherapy- and radiation-induced, as well as postoperative, nausea and vomiting. The 5-HT3 receptor is also a target for various investigational agents in pain and psychiatric disorders and is under study for its role in substance abuse and GI motility disturbances.

Other names

Serotonin type 3 receptor5-HT35-HT3A receptor (for the main functional subunit)HTR3A, HTR3B (gene/protein subunit names)Serotonin-gated ion channel

Antagonists: Competitively inhibit serotonin binding to the receptor, thereby blocking serotonin-induced opening of the ion channel and preventing the downstream effects such as emesis. Agonists: Bind and activate the receptor, leading to cation influx and neuronal depolarization. Modulators: Some drugs may act as allosteric modulators, altering receptor conformation and function.