Serotonin (5HT) Receptors - Types/Subtypes of Serotonin (5HT) Receptors - Location of Serotonin (5HT) Receptors
Serotonin Receptors:
Serotonin is 5 hydroxytryptamine (5HT). Four families of Serotonin receptors, comprising of 14 subtypes have so far been recognized.
Types of Serotonin (5HT) Receptors:
- 5-HT1
- 5-HT2
- 5-HT3
- 5-HT4-7
Location and effects of 5-HT receptors;
5-HT1 receptors:
These are present in brain. most important location is raphe nuclei of brain stem and hippocampus, the anti anxiety drug buprione acts as a partial agonis of 5-HT1A receptor. other locations include
- substantia nigra
- basal ganglia
- cranial blood vessels ( cause contraction)
5HT1 receptors inhibit adenylyl cyclase and cause hyperpolarization of neurons and inhibit transmission.
5-HT2 Receptors:
There are three subtypes of 5-HT2 receptors,
- 5-HT2a,
- 5-HT2b,
- 5-HT2c,
these receptors are coupled to phospholipase C and act through generation of IP3 and GAG.
5HT2a is the most widely expressed postjunctional 5-HT receptor and located on vascular and viceral smooth muscles, platelets and cereberal neurones.
it mediates vasoconstriction, intestinal , uterine and bronchial contraction.
5HT2b is present in rats
5HT2c is located on vascular endothelium and elicit vasodilation through Nitrous oxide release.
5-HT3 Receptor.
It is excitatory, it rapidly depolarizes nerve endings by opening the cation channel located within it. Responsible for pain, itch, coronary chemoreflex transmissions.
5-HT4-7 Receptors:
present in the smooth muscles of gut, neuronal plexus of gut wall, increase intestinal secretions and peristalsis.
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