Synonyms: serotonin receptor, 5-hydroxytryptamine receptor
German: 5-HT-Rezeptor, Serotoninrezeptor, 5-Hydroxytryptamin-Rezeptor
5-HT receptors, also known as serotonin receptors are receptors that are activated by serotonin. Almost all serotonin receptors are G protein–coupled receptors, with the exception of the 5-HT3 receptor subfamily which are ligand-gated ion channels.
Serotonin receptors are present in the central nervous system, as well as in the peripheral nervous system. They play important roles in various neuronal processes, including memory, mood, thermoregulation, appetite, cognition, and learning.
Serotonin receptors can be grouped into the following families and subfamilies:
Family | G protein | Mechanism of signal transduction | Function | Subtypes |
---|---|---|---|---|
5-HT1 receptor | Gi/G0 | Decreases intracellular cAMP concentration | Inhibitory | 1A, 1B, 1D, 1E, 1F |
5-HT2 receptor | Gq/11 | Increases intracellular IP3 and DAG concentration | Excitatory | 2A, 2B, 2C |
5-HT3 receptor | Ligand-gated Na+-/K+ channel | Depolarizes cell membrane | Excitatory | |
5-HT4 receptor | Gs | Increases intracellular cAMP concentration | Excitatory | |
5-HT5 receptor | Gi/G0 | Decreases intracellular cAMP concentration | Inhibitory | 5A, 5B |
5-HT6 receptor | Gs | Increases intracellular cAMP concentration | Excitatory | |
5-HT7 receptor | Gs | Increases intracellular cAMP concentration | Excitatory |
Except for 5-HT3 receptors, serotonin receptors are G protein-coupled receptors. 5-HT1A, 5-HT1B, 5-HT1D and 5-HT4 receptors inhibit the adenylyl cyclase protein. 5-HT1C and 5-HT2 receptors stimulate the transformation of inositol phosphates.
The activation of, for example, a 5-HT1 receptor in pyramid cells of the hippocampus opens potassium channels via a G protein, which in turn causes the inhibition of neuronal activity due to the resulting hyperpolarization.
The activation of a 5-HT2 receptor stimulates phospholipase C which results in the synthesis of the messenger substance IP3 which effects the release of calcium from intracellular reservoirs, triggering the contraction of smooth muscle.
The 5-HT3 receptor belongs to the group of ligand-gated ion channels and is a non-selective cation channel. The physiologically most relevant ions passing through the channel are sodium and potassium. After the channel opens, Na+ flows into the cell and K+ leaves the cell, along their respective electrochemical gradients. The result is an ion current that is directed into the cell and results in depolarization. Thus, 5-HT3 receptors are excitatory. So far, they have been found in the autonomic nervous system, sensory pain fibers, and in the brain. The activation of 5-HT3 receptors in the solitary nucleus causes vomiting.
Serotonin receptors are the target of multiple psychotropic drugs, including antidepressants. 5-HT3 receptor antagonists (e.g. Ondansetron or Granisetron) are used as antiemetic drugs, for example complementary to the use of cytostatic agents.
Tags: Biochemistry, Receptor, Serotonin
This page was last edited on 29 August 2017, at 09:10.
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