Serotonin Receptor Signaling

Serotonin is a monoamine neurotransmitter synthesized in the CNS. It is an important modulator of sleep, body temperature and metabolism. Guanosine triphosphate cyclohydrolase I (GCH1) catalyzes the production of Tetrahydrobiopterin (BH4), a required cofactor in the conversion of L-tryptophan to 5-hydroxytryptophan which is then converted to serotonin. Serotonin is released at the synapse of the presynaptic neuron where it binds to its receptor on the postsynaptic neuron.

The 5-hydroxytryptamine (HT) receptors are serotonin receptors. All members of this family are GPCRs with the exception of 5-HT3 receptor which is a ligand gated ion channel. Serotonin acts via its receptor mainly to activate or inhibit adenylate cyclase thereby regulating vasoconstriction, opening/closing of channels and platelet aggregation.

Serotonin is targeted for inactivation via its transporter SERT. Monoamine oxidase catalyzes the oxidative deamination of serotonin (5-HT) to 5-hydroxyindoleacetic acid which is translocated to cerebrospinal fluid.