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.
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.
The glutamate receptor, metabotropic 1, also known as GRM1, is a human gene which encodes the metabotropic glutamate receptor 1 (mGluR1) protein.
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.
LY-341495 is a research drug developed by the pharmaceutical company Eli Lilly, which acts as a potent and selective orthosteric antagonist for the group II metabotropic glutamate receptors (mGluR2/3).
2-Methyl-6-(phenylethynyl)pyridine (MPEP) is a research drug which was one of the first compounds found to act as a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. After being originally patented as a liquid crystal for LCDs, it was developed by the pharmaceutical company Novartis in the late 1990s. It was found to produce neuroprotective effects following acute brain injury in animal studies, although it was unclear whether these results were purely from mGluR5 blockade as it also acts as a weak NMDA antagonist, and as a positive allosteric modulator of another subtype mGlu4, and there is also evidence for a functional interaction between mGluR5 and NMDA receptors in the same populations of neurons. It was also shown to produce antidepressant and anxiolytic effects in animals, and to reduce the effects of morphine withdrawal, most likely due to direct interaction between mGluR5 and the μ-opioid receptor.
3-( ethynyl)pyridine (MTEP) is a research drug that was developed by Merck & Co. as a selective allosteric antagonist of the metabotropic glutamate receptor subtype mGluR5. Identified through structure-activity relationship studies on an older mGluR5 antagonist MPEP, MTEP has subsequently itself acted as a lead compound for newer and even more improved drugs.
EGLU is a drug that is used in neuroscience research. It was one of the first compounds found that acts as a selective antagonist for the group II metabotropic glutamate receptors (mGluR2/3), and so has been useful in the characterization and study of this receptor subfamily.
LY-344,545 is a research drug developed by the pharmaceutical company Eli Lilly, which acts as an antagonist for the metabotropic glutamate receptor subtype mGluR5. It is an epimer of another metabotropic glutamate receptor antagonist, the mGluR2/3-selective LY-341,495.
SIB-1757 is a drug used in scientific research which was one of the first compounds developed that acts as a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. It has anti-hyperalgesia effects in animals. SIB-1757 along with other mGluR5 antagonists has been shown to have neuroprotective and hepatoprotective effects, and it is also used to study the role of the mGluR5 receptor in brain development.
SIB-1893 is a drug used in scientific research which was one of the first compounds developed that acts as a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. It has anticonvulsant and neuroprotective effects, and reduces glutamate release. It has also been found to act as a positive allosteric modulator of mGluR4.
CPCCOEt is a drug used in scientific research, which acts as a non-competitive antagonist at the metabotropic glutamate receptor subtype mGluR1, with high selectivity although only moderate binding affinity. It is used mainly in basic research into the function of the mGluR1 receptor, including the study of behavioural effects in animals including effects on memory and addiction.
DCG-IV is a research drug which acts as a group-selective agonist for the group II metabotropic glutamate receptors (mGluR2/3). It has potent neuroprotective and anticonvulsant effects in animal studies, as well as showing anti-Parkinsonian effects, but also impairs the formation of memories.
LY-379,268 is a drug that is used in neuroscience research, which acts as a potent and selective agonist for the group II metabotropic glutamate receptors (mGluR2/3).
L-AP4 (L-2-amino-4-phosphonobutyric acid) is a drug used in scientific research, which acts as a group-selective agonist for the group III metabotropic glutamate receptors (mGluR4/6/7/8). It was the first ligand found to act as an agonist selective for this group of mGlu receptors, but does not show selectivity between the different mGluR Group III subtypes. It is widely used in the study of this receptor family and their various functions.
CECXG (3'-ethyl-LY-341,495) is a research drug which acts as a potent and selective antagonist for the group II metabotropic glutamate receptors (mGluR2/3), with reasonable selectivity for mGluR3. While it is some five times less potent than LY-341,495 at mGluR3, it has 38x higher affinity for mGluR3 over mGluR2, making it one of the few ligands available that is able to distinguish between these two closely related receptor subtypes.
MGS-0039 is a drug that is used in neuroscientific research, which acts as a potent and selective antagonist for group II of the metabotropic glutamate receptors (mGluR2/3). It produces antidepressant and anxiolytic effects in animal studies, and has been shown to boost release of dopamine and serotonin in specific brain areas. Research has suggested this may occur through a similar mechanism as that suggested for the similarly glutamatergic drug ketamine.
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.
