5-HT receptor



The serotonin receptors, also known as 5-hydroxytryptamine receptors or 5-HT receptors, are a group of G protein-coupled receptors (GPCRs) and ligand-gated ion channels (LGICs) found in the central and peripheral nervous systems. They mediate both excitatory and inhibitory neurotransmission. The serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand.

The serotonin receptors modulate the release of many neurotransmitters, including glutamate, GABA, dopamine, epinephrine / norepinephrine, and acetylcholine, as well as many hormones, including oxytocin, prolactin, vasopressin, cortisol, corticotropin, and substance P, among others. The serotonin receptors influence various biological and neurological processes such as aggression, anxiety, appetite, cognition, learning, memory, mood, nausea, sleep, and thermoregulation. The serotonin receptors are the target of a variety of pharmaceutical and illicit drugs, including many antidepressants, antipsychotics, anorectics, antiemetics, gastroprokinetic agents, antimigraine agents, hallucinogens, and entactogens.

Classification
With the exception of the 5-HT3 receptor, a ligand-gated ion channel, all other serotonin receptors are G protein-coupled receptors that activate an intracellular second messenger cascade to produce an excitatory or inhibitory response.

Subtypes
Within these general classes of serotonin receptors, a number of specific types have been characterized:

Note that there is no 5-HT1C receptor since, after the receptor was cloned and further characterized, it was found to have more in common with the 5-HT2 family of receptors and was redesignated as the 5-HT2C receptor. Note that there is also no 5-HT5B receptor, as it exists only in mice and rats and not in humans or monkeys.

Very nonselective agonists of 5-HT receptor subtypes include ergotamine (an antimigraine), which activates 5-HT1A, 5-HT1D, 5-HT1B, D2 and norepinephrine receptors. LSD (a psychedelic) is a 5-HT1A, 5-HT2A, 5-HT2C, 5-HT5A, 5-HT5, 5-HT6 agonist.