5-hydroxytryptamine 3A receptor (5-HT₃A receptor)

The **5-hydroxytryptamine 3A receptor** (5-HT₃A receptor) is a serotonin-gated ligand-gated ion channel, part of the Cys-loop superfamily, responsible for fast excitatory synaptic transmission in the central and peripheral nervous system. Unlike most serotonin receptors (which are G protein-coupled), the 5-HT₃A receptor forms a homopentameric or heteropentameric cation channel permeable to Na⁺ and K⁺ ions. Its activation by serotonin (5-hydroxytryptamine, 5-HT) causes neuronal depolarization, playing essential roles in processes like neurotransmission, emesis (vomiting), pain modulation, cognition, and gastrointestinal motility. The 5-HT₃A receptor is a major clinical target, with its antagonists ("setrons") used primarily as antiemetic agents during chemotherapy, radiotherapy, and surgery, and under study for use in neuropsychiatric and gastrointestinal disorders. Receptor dysfunction or polymorphisms are implicated in a variety of neuropsychiatric, pain, and digestive system disorders.

Other names

5-HT3A receptorSerotonin receptor 3AHTR3A5-HT3 receptor (specifically the A subunit or homopentameric form)Serotonin-gated ion channel

Competitive antagonism at the serotonin binding site; Inhibition of receptor-gated cation influx (Na⁺, K⁺); Inhibition of neuronal depolarization and neurotransmitter release; Allosteric modulation in some cases