5-HT receptors
5-HT receptors are a class of receptors with 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 protein-coupled, mediating cellular effects through decreasing cellular levels of cyclic adenosine monophosphate (cAMP).
5-HT2 receptors are Gs protein-coupled, mediating cellular effects through increasing cellular levels of inositol trisphosphate (IP3 ) and diacylglycerol (DAG).
5-HT3 receptors are ligand-gated ion channels , mediating cellular effects through increasing intracellular sodium and potassium cations .
5-HT4 receptors are Gs protein-coupled, mediating cellular effects through increasing cellular levels of cAMP.
5-HT7 receptors are Gs protein-coupled, mediating cellular effects through increasing cellular levels of cAMP.
Summary of characterised 5-HT receptors, with selected agonist/antagonist agents
receptor
actions
agonists
antagonists
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,
