serotonin receptor subtypes 1, 5 and 7, member of the class A family of seven-transmembrane G protein-coupled receptors
This group includes serotonin receptor subtypes 1, 5, and 7 that are activated by the neurotransmitter serotonin. The 5-HT1 and 5-HT5 receptors mediate inhibitory neurotransmission by coupling to G proteins of the G(i/o) family. The 5-HT1 receptor subfamily includes 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F. There is no 5-HT1C receptor subtype, as it has been reclassified as 5-HT2C receptor. The 5-HT5A and 5-HT5B receptors have been cloned from rat and mouse, but only the 5-HT5A isoform has been identified in human because of the presence of premature stop codons in the human 5-HT5B gene, which prevents a functional receptor from being expressed. The 5-HT7 receptor is coupled to Gs, which positively stimulates adenylate cyclase activity, leading to increased intracellular cAMP formation and calcium influx. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.