5-HT receptors Guide, Meaning , Facts, Information and Description
In the field of neurochemistry, 5-HT receptors are a class of receptors with the neurotransmitter 5-HT, also known as serotonin, as endogenous ligand.The pharmacology of 5-HT is extremely complex, with its actions being mediated by a large and diverse range of 5-HT receptors - many of which have poorly characterised physiological functions.
- 5-HT1 receptors are Gi/Go coupled, mediating cellular effects through decreasing cellular levels of cyclic adenosine monophosphate (cAMP).
- 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-HT2, 5-HT2, 5-HT2 and the
- The 5-HT3 receptor is a ligand-gated Na+ and K+ cation channel, resulting in a direct plasma membrane depolarization.
- The 5-HT4 receptor is Gs coupled, mediating cellular effects through increasing cellular levels of cAMP.
- The 5-HT7 receptors is Gs coupled, mediating cellular effects through increasing cellular levels of cAMP.
Characterised 5-HT receptors
Within these general classes of 5-HT receptors, a number of specific types have been characterized:
| Summary of characterised 5-HT receptors, with selected agonist/antagonist agents | |||
| receptor | actions | agonists | antagonistss |
| 5-HT1A | CNS: neuronal inhibition, behavioural effects (sleep, feeding, thermoregulation, anxiety) | 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; smooth muscle: contraction, vasoconstriction/dilatation; platelets: aggregation | α-methyl-5-HT, LSD (CNS) | ketanserin, cyproheptadine, pizotifen, LSD (PNS) |
| 5-HT2B | stomach: contraction | α-methyl-5-HT, LSD (CNS) | yohimbine, LSD (PNS) |
| 5-HT2C | CNS, choroid plexus: cerebrospinal fluid (CSF) secretion | α-methyl-5-HT, LSD (CNS) | mesulergine, LSD (PNS) |
| 5-HT3 | CNS, PNS: neuronal excitation, anxiety, emesis | 2-methyl-5-HT | metoclopramide (high doses), renzapride, ondansetron, tropisetron, granisetron |
| 5-HT4 | GIT, CNS: neuronal excitation, gastrointestinal motility | 5-methoxytryptamine, metoclopramide, renzapride | GR113808 |
| 5-ht5 | CNS: unknown | unknown | unknown |
| 5-ht6 | CNS: unknown | unknown | unknown |
| 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 characterised, it was found to have more in common with the 5-HT2 family of receptors and was redesignated as the 5-HT2C receptor.
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