The 5-HT 1A receptor
There are 7 different types of serotonin receptor (5-HT1–5-HT7) and the 5-HT1, 5-HT2 and 5-HT5 receptors are further classified into subtypes. The 5-HT1 receptors are classified into A, B and D subtypes, which are found in the central nervous system and blood in vessels. Coupled to inhibitory G-proteins, the 5-HT1A receptors have an inhibitory effect on neurotransmission when bound by an agonist.
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References
Other peripheral mediators: 5-hydroxytryptamine and purines. In: Pharmacology, 4th edition. Rang HP, Dale MM and Ritter JM. Edinburgh, UK: Harcourt Publishers Ltd, 2001:165–176.