Ampakines or AMPAkines are a subgroup of AMPA receptor positive allosteric modulators with a benzamide or closely related chemical structure. They are also known as "CX compounds". Ampakines take their name from the AMPA receptor (AMPAR), a type of ionotropic glutamate receptor with which the ampakines interact and act as positive allosteric modulators (PAMs) of. Although all ampakines are AMPAR PAMs, not all AMPAR PAMs are ampakines.
The metabotropic glutamate receptors, or mGluRs, are a type of glutamate receptor that are active through an indirect metabotropic process. They are members of the group C family of G-protein-coupled receptors, or GPCRs. Like all glutamate receptors, mGluRs bind with glutamate, an amino acid that functions as an excitatory neurotransmitter.
Glutamate receptors are synaptic and non synaptic receptors located primarily on the membranes of neuronal and glial cells. Glutamate is abundant in the human body, but particularly in the nervous system and especially prominent in the human brain where it is the body's most prominent neurotransmitter, the brain's main excitatory neurotransmitter, and also the precursor for GABA, the brain's main inhibitory neurotransmitter. Glutamate receptors are responsible for the glutamate-mediated postsynaptic excitation of neural cells, and are important for neural communication, memory formation, learning, and regulation.
Fenobam is an imidazole derivative developed by McNeil Laboratories in the late 1970s as a novel anxiolytic drug with an at-the-time-unidentified molecular target in the brain. Subsequently, it was determined that fenobam acts as a potent and selective negative allosteric modulator of the metabotropic glutamate receptor subtype mGluR5, and it has been used as a lead compound for the development of a range of newer mGluR5 antagonists.
Metabotropic glutamate receptor 2 (mGluR2) is a protein that, in humans, is encoded by the GRM2 gene. mGluR2 is a G protein-coupled receptor (GPCR) that couples with the Gi alpha subunit. The receptor functions as an autoreceptor for glutamate, that upon activation, inhibits the emptying of vesicular contents at the presynaptic terminal of glutamatergic neurons.
Metabotropic glutamate receptor 3 (mGluR3) is an inhibitory Gi/G0-coupled G-protein coupled receptor (GPCR) generally localized to presynaptic sites of neurons in classical circuits. However, in higher cortical circuits in primates, mGluR3 are localized post-synaptically, where they strengthen rather than weaken synaptic connectivity. In humans, mGluR3 is encoded by the GRM3 gene. Deficits in mGluR3 signaling have been linked to impaired cognition in humans, and to increased risk of schizophrenia, consistent with their expanding role in cortical evolution.
Metabotropic glutamate receptor 4 is a protein that in humans is encoded by the GRM4 gene.
Metabotropic glutamate receptor 5 is an excitatory Gq-coupled G protein-coupled receptor predominantly expressed on the postsynaptic sites of neurons. In humans, it is encoded by the GRM5 gene.
Biphenylindanone A is a research agent which acts as a potent and selective positive allosteric modulator for the group II metabotropic glutamate receptor subtype mGluR2.
PHCCC is a research drug which acts as a glutamate receptor ligand, particularly being a positive allosteric modulator at the mGluR4 subtype, as well as an agonist at mGluR6. It has anxiolytic effects in animal studies. PHCCC and similar drugs have been suggested as novel treatments for Parkinson's disease.
Pomaglumetad (LY-404,039) is an amino acid analog drug that acts as a highly selective agonist for the metabotropic glutamate receptor group II subtypes mGluR2 and mGluR3. Pharmacological research has focused on its potential antipsychotic and anxiolytic effects. Pomaglumetad is intended as a treatment for schizophrenia and other psychotic and anxiety disorders by modulating glutamatergic activity and reducing presynaptic release of glutamate at synapses in limbic and forebrain areas relevant to these disorders. Human studies investigating therapeutic use of pomaglumetad have focused on the prodrug LY-2140023, a methionine amide of pomaglumetad (also called pomaglumetad methionil) since pomaglumetad exhibits low oral absorption and bioavailability in humans.
CDPPB is a drug used in scientific research which acts as a positive allosteric modulator selective for the metabotropic glutamate receptor subtype mGluR5. It has antipsychotic effects in animal models, and mGluR5 modulators are under investigation as potential drugs for the treatment of schizophrenia, as well as other applications.
Ro01-6128 is a drug used in scientific research, which acts as a selective positive allosteric modulator for the metabotropic glutamate receptor subtype mGluR1. It was derived by modification of a lead compound found via high-throughput screening, and was further developed to give the improved compound Ro67-4853.
LY-487,379 is a drug used in scientific research that acts as a selective positive allosteric modulator for the metabotropic glutamate receptor group II subtype mGluR2. It is used to study the structure and function of this receptor subtype, and LY-487,379 along with various other mGluR2/3 agonists and positive modulators are being investigated as possible antipsychotic and anxiolytic drugs.
GRN-529 is a drug that was developed by Wyeth as a negative allosteric modulator of the metabotropic glutamate receptor 5 (mGluR5).
ADX-71149, also known as JNJ-40411813 and JNJ-mGluR2-PAM, is a selective positive allosteric modulator of the mGlu2 receptor. It is being studied by Addex Therapeutics and Janssen Pharmaceuticals for the treatment of schizophrenia. It was also researched by these companies for the treatment of anxious depression, but although some efficacy was observed in clinical trials, it was not enough to warrant further development for this indication. As of 2015, ADX-71149 is in phase II clinical trials for schizophrenia.
Zuranolone is an investigational drug which is under development by SAGE Therapeutics for the treatment of depressive disorders and a variety of other indications. An orally active inhibitory pregnane neurosteroid, zuranolone acts as a positive allosteric modulator of the GABAA receptor. The drug was developed as an improvement on the intravenously administered neurosteroid brexanolone, with high oral bioavailability and a biological half-life suitable for once-daily administration. Its half-life is around 16 to 23 hours, compared to approximately 9 hours for brexanolone.
ADX71743 is a drug which acts as a potent and selective negative allosteric modulator of the metabotropic glutamate receptor 7. Few selective ligands are available for this receptor, and so ADX71743 has played an important role into scientific research into the role of this receptor in various processes such as memory formation, nociception, absence seizures and psychosis.
Mevidalen (developmental code name LY-3154207) is a dopaminergic drug which is under development for the treatment of Lewy body disease, including those with Parkinson's disease. It acts as a selective positive allosteric modulator (PAM) of the dopamine D1 receptor. The drug is orally active and crosses the blood–brain barrier. It is a tetrahydroisoquinoline and is a close analogue of DETQ, another D1 receptor PAM. Mevidalen has been found to have wakefulness-promoting effects in sleep-deprived humans. Side effects of mevidalen have been reported to include increased heart rate and blood pressure, insomnia, dizziness, nausea, vomiting, anxiety, nervousness, fatigue, headaches, palpitations, and contact dermatitis, as well as falls in those with dementia. As of March 2022, mevidalen is in phase 2 clinical trials for the treatment of Lewy body disease. Besides for movement disorders and dementia, D1 receptor PAMs like mevidalen might have value in the treatment of certain neuropsychiatric disorders, such as depression, excessive somnolence, and attention deficit hyperactivity disorder.
AZ-12216052 is a drug which acts as a potent and selective positive allosteric modulator of the metabotropic glutamate receptor 8, and is used for research into the role of this receptor subtype in various processes including anxiety and neuropathic pain.
