The 5-HT receptors are a subfamily of the 5-HT serotonin receptors that bind to the endogenous neurotransmitter serotonin (also known as 5-hydroxytryptamine, or 5-HT). The 5-HT subfamily consists of five G protein-coupled receptors (GPCRs) that share 40% to 63% overall sequence homology, including 5-HT, 5-HT, 5-HT, 5-HT, and 5-HT. Receptors of the 5-HT type, specifically, the 5-HT and 5-HT receptor subtypes, are present on the cell bodies. Receptors of the 5-HT1 type, specifically, the 5-HT and 5-HT receptor subtypes, are also present on the nerve terminals. These receptors are broadly distributed throughout the brain and are recognized to play a significant part in regulating synaptic levels of 5-HT.
The receptor subfamily is coupled to G/G and mediate inhibitory neurotransmission by inhibiting the function of adenylate cyclase and modulating downstream ionic effects. This R-coupling to G/G proteins leads to a reduction in local concentrations of cAMP, proving that 5-HT are primarily inhibitory. There is no 5-HT receptor, as it was reclassified as the 5-HT receptor. For more information, please see the respective main articles of the individual subtypes: