5-HT receptors, 5-hydroxytryptamine receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels found in the central and peripheral nervous systems. They mediate both excitatory and inhibitory neurotransmission. The serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand.
Azapirones are a class of drugs used as anxiolytics, antidepressants, and antipsychotics. They are commonly used as add-ons to other antidepressants, such as selective serotonin reuptake inhibitors (SSRIs).
Buspirone, sold under the brand name Buspar, among others, is a medication primarily used to treat anxiety disorders, particularly generalized anxiety disorder. Benefits support its short-term use. It is taken by mouth, and it may take up to four weeks to have an effect.
The 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT2A receptor is a cell surface receptor. 5-HT is short for 5-hydroxy-tryptamine, which is serotonin. This is the main excitatory receptor subtype among the GPCRs for serotonin, although 5-HT2A may also have an inhibitory effect on certain areas such as the visual cortex and the orbitofrontal cortex. This receptor was first noted for its importance as a target of serotonergic psychedelic drugs such as LSD and psilocybin mushrooms. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones.
A serotonin receptor agonist is an agonist of one or more serotonin receptors. They activate serotonin receptors in a manner similar to that of serotonin, a neurotransmitter and hormone and the endogenous ligand of the serotonin receptors.
Neurokinin 1 (NK1) antagonists (-pitants) are a novel class of medications that possesses unique antidepressant, anxiolytic, and antiemetic properties. NK-1 antagonists boost the efficacy of 5-HT3 antagonists to prevent nausea and vomiting. The discovery of neurokinin 1 (NK1) receptor antagonists was a turning point in the prevention of nausea and vomiting associated with cancer chemotherapy.
The 5-HT3 antagonists, informally known as "setrons", are a class of drugs that act as receptor antagonists at the 5-HT3 receptor, a subtype of serotonin receptor found in terminals of the vagus nerve and in certain areas of the brain. With the notable exceptions of alosetron and cilansetron, which are used in the treatment of irritable bowel syndrome, all 5-HT3 antagonists are antiemetics, used in the prevention and treatment of nausea and vomiting. They are particularly effective in controlling the nausea and vomiting produced by cancer chemotherapy and are considered the gold standard for this purpose.
The 5HT6 receptor is a subtype of 5HT receptor that binds the endogenous neurotransmitter serotonin (5-hydroxytryptamine, 5HT). It is a G protein-coupled receptor (GPCR) that is coupled to Gs and mediates excitatory neurotransmission. HTR6 denotes the human gene encoding for the receptor.
The 5-HT7 receptor is a member of the GPCR superfamily of cell surface receptors and is activated by the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) The 5-HT7 receptor is coupled to Gs (stimulates the production of the intracellular signaling molecule cAMP) and is expressed in a variety of human tissues, particularly in the brain, the gastrointestinal tract, and in various blood vessels. This receptor has been a drug development target for the treatment of several clinical disorders. The 5-HT7 receptor is encoded by the HTR7 gene, which in humans is transcribed into 3 different splice variants.
Bemesetron (MDL-72222) is a drug which acts as an antagonist at the 5HT3 receptor. It has antiemetic effects comparable to metoclopramide, however it is not used clinically, instead its main application is in scientific research studying the involvement of the 5HT3 receptor in the actions of drugs of abuse.
SB-399885 is a drug which is used in scientific research. It acts as a potent, selective and orally active 5-HT6 receptor antagonist, with a Ki of 9.0nM. SB-399885 and other 5-HT6 antagonists show nootropic effects in animal studies, as well as antidepressant and anxiolytic effects which are comparable to and synergistic with drugs such as imipramine and diazepam, and have been proposed as potential novel treatments for cognitive disorders such as schizophrenia and Alzheimer's disease.
Naluzotan is a serotonergic drug of the phenylpiperazine class that was under investigation by EPIX Pharmaceuticals Inc for the treatment of generalized anxiety disorder and major depressive disorder. It acts as a selective and potent 5-HT1A receptor partial agonist, readily stimulating prolactin responses, though it has also been found to bind to and activate the σ receptor. Naluzotan was well tolerated in clinical trials, with more patients in the control group dropping out due to adverse effects than in the active group in one study. The most frequently reported side effect was headache in 15% of patients. In addition, naluzotan demonstrated significant antidepressant and anxiolytic effects as per the HAM-D and MADRS and the HAM-A, respectively, in some trials, but in others it did not. In the end it was not found to be significantly superior enough to placebo and development was stopped.
Volinanserin (INN) is a highly selective 5-HT2A receptor antagonist that is frequently used in scientific research to investigate the function of the 5-HT2A receptor. It was also tested in clinical trials as a potential antipsychotic, antidepressant, and treatment for insomnia but was never marketed.
Litoxetine (developmental code names SL 81-0385, IXA-001) is an antidepressant which was under clinical development for the treatment of depression in the early 1990s but was never marketed. It acts as a potent serotonin reuptake inhibitor (Ki for SERT = 7 nM) and modest 5-HT3 receptor antagonist (Ki = 315 nM). It has antiemetic activity, and unlike the selective serotonin reuptake inhibitors (SSRIs), appears to have a negligible incidence of nausea and vomiting. The drug is structurally related to indalpine. Development of litoxetine for depression was apparently ceased in the late 1990s. However, as of March 2017, development of litoxetine has been reinitiated and the drug is now in the phase II stage for the treatment of urinary incontinence.
Vortioxetine, sold under the brand names Trintellix and Brintellix among others, is a medication used to treat major depressive disorder. Effectiveness is viewed as similar to that of other antidepressants. In the United Kingdom, it is only recommended in people who have not improved sufficiently on two other antidepressants. It is taken by mouth.
Pruvanserin is a selective 5-HT2A receptor antagonist which was under development by Eli Lilly and Company for the treatment of insomnia. It was in phase II clinical trials in 2008 but appears to have been discontinued as it is no longer in the company's development pipeline. In addition to its sleep-improving properties, pruvanserin has also been shown to have antidepressant, anxiolytic, and working memory-enhancing effects in animal studies.
Tropanserin (INN; MDL-72,422) is a drug which acts as a potent and selective 5-HT3 receptor antagonist. It was investigated in clinical trials for the treatment of migraine in the 1980s but was never marketed.
5-HT2C receptor agonists are a class of drugs that activate 5-HT2C receptors. They have been investigated for the treatment of a number of conditions including obesity, psychiatric disorders, sexual dysfunction and urinary incontinence.
AVN-101, a close structural analogue of latrepirdine, is a selective 5-HT6 receptor antagonist which is under development by Avineuro Pharmaceuticals for the treatment of Alzheimer's disease and anxiety disorders. As of November 2013, it is in phase II clinical trials for these indications.
Amesergide is a serotonin receptor antagonist of the ergoline and lysergamide families related to methysergide which was under development by Eli Lilly and Company for the treatment of a variety of conditions including depression, anxiety, schizophrenia, male sexual dysfunction, migraine, and thrombosis but was never marketed. It reached phase II clinical trials for the treatment of depression, erectile dysfunction, and premature ejaculation prior to the discontinuation of its development.
