5-Hydroxytryptamine (serotonin) receptor 5A, also known as HTR5A, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that in humans is encoded by the ''HTR5A''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Agonists An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agon ...

and

antagonist An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, ri ...

s for 5-HT receptors, as well as serotonin uptake inhibitors, present promnesic (memory-promoting) and/or anti-amnesic effects under different conditions, and 5-HT receptors are also associated with neural changes.

Function

The gene described in this record is a member of 5-hydroxytryptamine receptor family and encodes a multi-pass membrane protein that functions as a receptor for 5-hydroxytryptamine and couples to

G protein G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. Their a ...

s, negatively influencing cAMP levels via G_i and G_o. This protein has been shown to function in part through the regulation of intracellular Ca²⁺ mobilization. The 5-HT_5A receptor has been shown to be functional in a native expression system. Rodents have been shown to possess two functional 5-HT₅ receptor subtypes, 5-HT_5A and 5-HT_5B, however while humans possess a gene coding for the 5-HT_5B subtype, its coding sequence is interrupted by stop codons, making the gene non-functional, and so only the 5-HT_5A subtype is expressed in human brain. It also appears to serve as a presynaptic serotonin autoreceptor.

Clinical significance

The neurotransmitter

serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...

(5-hydroxytryptamine, 5-HT) has been implicated in a wide range of psychiatric conditions and also has vasoconstrictive and vasodilatory effects.

Selective ligands

Few highly selective ligands are commercially available for the 5-HT_5A receptor. When selective activation of this receptor is desired in scientific research, the non-selective serotonin receptor agonist

5-Carboxamidotryptamine 5-Carboxamidotryptamine (5-CT) is a tryptamine derivative closely related to the neurotransmitter serotonin. 5-CT acts as a non-selective, high-affinity full agonist at the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT5A, and 5-HT7 receptors, as well a ...

can be used in conjunction with selective antagonists for its other targets (principally 5-HT_1A, 5-HT_1B, 5-HT_1D, and 5-HT₇). Research in this area is ongoing.

Agonists

* LSD:(+)-lysergic acid, *

Lisuride Lisuride, sold under the brand name Dopergin among others, is a monoaminergic medication of the ergoline class which is used in the treatment of Parkinson's disease, migraine, and high prolactin levels. It is taken by mouth. Side effects of lis ...

, partial agonist. * 5-CT, full agonist. * Methylergometrine, full agonist. * Valerenic acid, a component of valerian, has been shown to act as a 5HT_5A partial agonist. *

Olanzapine Olanzapine (sold under the trade name Zyprexa among others) is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is t ...

, an

atypical antipsychotic The atypical antipsychotics (AAP), also known as second generation antipsychotics (SGAs) and serotonin–dopamine antagonists (SDAs), are a group of antipsychotic drugs (antipsychotic drugs in general are also known as major tranquilizers and ne ...

. *Psilocin * Another ligand that has been recently disclosed is shown below, claimed be a selective 5-HT_5A agonist with K_i = 124 nM.

Antagonists

* ASP-5736 * AS-2030680 * AS-2674723 * MS112, selective potent antangonist. * Latrepirdine (non-selective) *

Risperidone Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder. It is taken either by mouth or by injection (subcutaneous or intramuscular). The injectable versions ...

(non-selective), moderate 206 nM affinity. * SB-699,551

References

External links

* * {{DEFAULTSORT:5-Ht5a Receptor Serotonin receptors