5-HT3D: Products5-HT3D belongs to the ligand-gated ion channel receptor superfamily. It encodes subunit D of the type 3 receptor for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a mitogen and a hormone. This hormone has been linked to neuropsychiatric disorders, including anxiety, depression, and migraine. Serotonin receptors cause fast and depolarizing responses in neurons following activation. Alternatively spliced transcript variants encoding different isoforms have been found for 5-HT3D.