5-HT receptor

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In the field of neurochemistry, 5-HT receptors are receptors for the neurotransmitter and peripheral signal mediator serotonin, also known as 5-hydroxytryptamine or 5-HT. 5-HT receptors are located on the cell membrane of nerve cells and other cell types including smooth muscle in animals, and mediate the effects of serotonin as the endogenous ligand and of a broad range of pharmaceutical and hallucinogenic drugs. All 5-HT receptors reduce cyclic adenosine monophosphate (cAMP). With the exception of the 5-HT3 receptor, a ligand gated ion channel, all other 5-HT receptors are G protein coupled seven transmembrane (or heptahelical) receptors that activate an intracellular second messenger cascade.

  • 5-HT2 receptors are Gq/G11 coupled, mediating cellular effects through increasing cellular levels of inositol trisphosphate (IP3) and diacylglycerol (DAG). Three subtypes exist, namely 5-HT2A, 5-HT2B, and 5-HT2C (formerly called 5-HT1C).
  • The 5-HT4 receptor is Gs coupled, mediating cellular effects through increasing cellular levels of cAMP.
  • The 5-HT5A receptor is G protein coupled; the primary coupling appears to be through Gi/o, inhibiting adenylate cyclase activity.[1] The 5-HT5B subtype exists, but has not been detected in humans.
  • The 5-HT7 receptor is Gs coupled, mediating cellular effects through increasing cellular levels of cAMP.

Contents

[edit] Characterized 5-HT receptors

Within these general classes of 5-HT receptors, a number of specific types have been characterized:

Summary of characterized 5-HT receptors, with selected agonist/antagonist agents
Receptor Actions Agonists Antagonists
5-HT1A CNS: neuronal inhibition, behavioural effects (sleep, feeding, thermoregulation, anxiety; abnormalities in this receptor contribute to SIDS, or sudden infant death syndrome[citation needed]) buspirone spiperone, methiothepin, ergotamine, yohimbine
5-HT1B CNS: presynaptic inhibition, behavioural effects; vascular: pulmonary vasoconstriction ergotamine, sumatriptan methiothepin, yohimbine, metergoline
5-HT1D CNS: locomotion; vascular: cerebral vasoconstriction sumatriptan methiothepin, yohimbine, metergoline, ergotamine
5-HT2A CNS: neuronal excitation, behavioural effects, learning; smooth muscle: contraction, vasoconstriction / dilatation; platelets: aggregation α-methyl-5-HT, LSD (CNS), DOI Nefazodone, trazodone, mirtazapine, ketanserin, cyproheptadine, pizotifen, LSD (PNS)
5-HT2B stomach: contraction α-methyl-5-HT, LSD (CNS), DOI yohimbine, LSD (PNS)
5-HT2C CNS, choroid plexus: cerebrospinal fluid (CSF) secretion α-methyl-5-HT, agomelatine, LSD (CNS), DOI mesulergine, agomelatine, LSD (PNS)
5-HT3 CNS, PNS: neuronal excitation, anxiety, emesis 2-methyl-5-HT metoclopramide(high doses), renzapride, ondansetron, alosetron, mirtazapine, memantine
5-HT4 GIT, CNS: neuronal excitation, gastrointestinal motility 5-methoxytryptamine, metoclopramide, renzapride, tegaserod GR113808
5-HT5A CNS (cortex, hippocampus, cerebellum): unknown 5-carboxytryptamine;
LSD (partial agonist)[1]		 unknown
5-HT6 CNS: unknown LSD SB271046[1]
5-HT7 CNS, GIT, blood vessels: unknown 5-carboxytryptamine, LSD methiothepin

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.

[edit] Therapeutic modulation

Various drugs are used to modulate the 5-HT system including some antidepressants, anxiolytics, and antiemetics.

[edit] References

  1. ^ a b D.L. Nelson (2004). "5-HT5 receptors". Curr. Drug Targets CNS Neurol. Disord. 3 (1): 53-58. PMID 14965244.

[edit] External links

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