Serotonin receptor 5-HT3 subtype (5-HT3 receptor)

The Serotonin receptor 5‑HT3 subtype is a ligand-gated ion channel belonging to the Cys-loop superfamily. Unlike other serotonin receptors that are G protein-coupled, the 5‑HT3 receptor forms a pentameric structure around a central pore permeable primarily to cations. Functional channels can be homopentamers composed solely of 5‑HT3A subunits or heteropentamers including other subunits such as 5‑HT3B–E. The receptor is widely expressed throughout both central and peripheral nervous systems, mediating rapid excitatory synaptic transmission. It plays key roles in emesis pathways—making it an important therapeutic target for antiemetic drugs—as well as modulating anxiety and possibly seizure susceptibility. Its antagonists are clinically used mainly for prevention of chemotherapy-induced nausea and vomiting but may have additional neuropsychiatric applications. Safety concerns include cardiac arrhythmias due to QT prolongation with certain drugs targeting this molecule.

Other names

5-hydroxytryptamine receptor 3HTR3Serotonin-gated ion channel5-HT₃ (common abbreviation in literature)

Antagonists block serotonin binding, preventing activation of the ion channel, thereby inhibiting fast excitatory neurotransmission associated with nausea/vomiting centers in the brainstem. Agonists open the cation-selective ion channel, leading to neuronal excitation.