L-glutamate is the major excitatory neurotransmitter in the central nervous system and activates both ionotropic and metabotropic glutamate receptors. Glutamatergic neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions. The metabotropic glutamate receptors are a family of G protein-coupled receptors, that have been divided into 3 groups on the basis of sequence homology, putative signal transduction mechanisms, and pharmacologic properties. Group I includes GRM1 and GRM5 and these receptors have been shown to activate phospholipase C. Group II includes GRM2 (this receptor) and GRM3 while Group III includes GRM4, GRM6, GRM7 and GRM8. Group II and III receptors are linked to the inhibition of the cyclic AMP cascade but differ in their agonist selectivities.[2]
Role in hallucinogenesis
Many psychedelic drugs (e.g. LSD-25) produce their effects by binding to the oligomerized complexes of the 5HT2A and mGlu2 receptors.[3][4]Lisuride acts preferentially or exclusively on the non-heteromerized 5HT2A receptors, which are not capable of inducing psychedelic effects. Due to this, lisuride is capable of reducing the hallucinogenic effects of these drugs through competitive agonistic activity (producing the effect of a silent-agonist in the presence of these drugs).
Strong agonists for either subunit of the 5HT2A-mGlu2R heterocomplex suppress signaling through the partner subunit and inverse agonists for either subunit potentiate the signaling through the partner subunit.
Ligands
The development of subtype-2-selective positive allosteric modulators (PAMs) experienced steady advance in recent years.[5] mGluR2 potentiation is a new approach for the treatment of schizophrenia.[6][7] On the other hand, antagonists and negative allosteric modulators of mGluR2/3 have potential as antidepressant drugs.[8][9][10][11]
LY-487,379:[22][23][24] devoid of orthosteric activity; along with related 3-pyridylmethylsulfonamides[25][26] the first subtype-2-selective potentiator published (2003).
The metabotropic glutamate receptor 2 is able to form a heteromeric complex with its isoform mGluR4. This heteromer exhibits a pharmacological profile distinct from the parent receptor monomers.[30]
↑Flor PJ, Lindauer K, Püttner I, Rüegg D, Lukic S, Knöpfel T, Kuhn R (April 1995). "Molecular cloning, functional expression and pharmacological characterization of the human metabotropic glutamate receptor type 2". The European Journal of Neuroscience. 7 (4): 622–9. doi:10.1111/j.1460-9568.1995.tb00666.x. PMID7620613.
↑Moreno JL, Miranda-Azpiazu P, García-Bea A, Younkin J, Cui M, Kozlenkov A, Ben-Ezra A, Voloudakis G, Fakira AK, Baki L, Ge Y, Georgakopoulos A, Morón JA, Milligan G, López-Giménez JF, Robakis NK, Logothetis DE, Meana JJ, González-Maeso J (2016). "Allosteric signaling through an mGlu2 and 5-HT2A heteromeric receptor complex and its potential contribution to schizophrenia". Science Signaling. 9 (410): ra5. doi:10.1126/scisignal.aab0467. PMID26758213.
↑Baki L, Fribourg M, Younkin J, Eltit JM, Moreno JL, Park G, Vysotskaya Z, Narahari A, Sealfon SC, Gonzalez-Maeso J, Logothetis DE (January 2016). "Cross-signaling in metabotropic glutamate 2 and serotonin 2A receptor heteromers in mammalian cells". Pflugers Archiv. 468: 775–93. doi:10.1007/s00424-015-1780-7. PMID26780666.
↑Fraley ME (September 2009). "Positive allosteric modulators of the metabotropic glutamate receptor 2 for the treatment of schizophrenia". Expert Opinion on Therapeutic Patents. 19 (9): 1259–75. doi:10.1517/13543770903045009. PMID19552508.
↑Muguruza, Carolina; Meana, J. Javier; Callado, Luis F. (2016). "Group II Metabotropic Glutamate Receptors as Targets for Novel Antipsychotic Drugs". Frontiers in Pharmacology. 7. doi:10.3389/fphar.2016.00130. ISSN1663-9812.
↑Kawashima N, Karasawa J, Shimazaki T, Chaki S, Okuyama S, Yasuhara A, Nakazato A (April 2005). "Neuropharmacological profiles of antagonists of group II metabotropic glutamate receptors". Neuroscience Letters. 378 (3): 131–4. doi:10.1016/j.neulet.2004.12.021. PMID15781145.
↑Bespalov AY, van Gaalen MM, Sukhotina IA, Wicke K, Mezler M, Schoemaker H, Gross G (September 2008). "Behavioral characterization of the mGlu group II/III receptor antagonist, LY-341495, in animal models of anxiety and depression". European Journal of Pharmacology. 592 (1–3): 96–102. doi:10.1016/j.ejphar.2008.06.089. PMID18634781.
↑Koike H, Fukumoto K, Iijima M, Chaki S (February 2013). "Role of BDNF/TrkB signaling in antidepressant-like effects of a group II metabotropic glutamate receptor antagonist in animal models of depression". Behavioural Brain Research. 238: 48–52. doi:10.1016/j.bbr.2012.10.023. PMID23098797.
↑Huynh TH, Erichsen MN, Tora AS, Goudet C, Sagot E, Assaf Z, Thomsen C, Brodbeck R, Stensbøl TB, Bjørn-Yoshimoto WE, Nielsen B, Pin JP, Gefflaut T, Bunch L (2016). "New 4-Functionalized Glutamate Analogues Are Selective Agonists at Metabotropic Glutamate Receptor Subtype 2 or Selective Agonists at Metabotropic Glutamate Receptor Group III". J. Med. Chem. 59 (3): 914–24. doi:10.1021/acs.jmedchem.5b01333. PMID26814576.
↑Cid JM, Tresadern G, Vega JA, de Lucas AI, Del Cerro A, Matesanz E, Linares ML, García A, Iturrino L, Pérez-Benito L, Macdonald GJ, Oehlrich D, Lavreysen H, Peeters L, Ceusters M, Ahnaou A, Drinkenburg W, Mackie C, Somers M, Trabanco AA (2016). "Discovery of 8-Trifluoromethyl-3-cyclopropylmethyl-7-[(4-(2,4-difluorophenyl)-1-piperazinyl)methyl]-1,2,4-triazolo[4,3-a]pyridine (JNJ-46356479), a Selective and Orally Bioavailable mGlu2 receptor Positive Allosteric Modulator (PAM)". J. Med. Chem. 59: 8495–507. doi:10.1021/acs.jmedchem.6b00913. PMID27579727.
↑D'Alessandro PL, Corti C, Roth A, Ugolini A, Sava A, Montanari D, Bianchi F, Garland SL, Powney B, Koppe EL, Rocheville M, Osborne G, Perez P, de la Fuente J, De Los Frailes M, Smith PW, Branch C, Nash D, Watson SP (January 2010). "The identification of structurally novel, selective, orally bioavailable positive modulators of mGluR2". Bioorganic & Medicinal Chemistry Letters. 20 (2): 759–62. doi:10.1016/j.bmcl.2009.11.032. PMID20005096.
↑Tresadern G, Cid JM, Macdonald GJ, Vega JA, de Lucas AI, García A, Matesanz E, Linares ML, Oehlrich D, Lavreysen H, Biesmans I, Trabanco AA (January 2010). "Scaffold hopping from pyridones to imidazo[1,2-a]pyridines. New positive allosteric modulators of metabotropic glutamate 2 receptor". Bioorganic & Medicinal Chemistry Letters. 20 (1): 175–9. doi:10.1016/j.bmcl.2009.11.008. PMID19932615.
↑Zhang L, Rogers BN, Duplantier AJ, McHardy SF, Efremov I, Berke H, Qian W, Zhang AQ, Maklad N, Candler J, Doran AC, Lazzaro JT, Ganong AH (October 2008). "3-(Imidazolyl methyl)-3-aza-bicyclo[3.1.0]hexan-6-yl)methyl ethers: a novel series of mGluR2 positive allosteric modulators". Bioorganic & Medicinal Chemistry Letters. 18 (20): 5493–6. doi:10.1016/j.bmcl.2008.09.026. PMID18812259.
↑Galici R, Jones CK, Hemstapat K, Nong Y, Echemendia NG, Williams LC, de Paulis T, Conn PJ (July 2006). "Biphenyl-indanone A, a positive allosteric modulator of the metabotropic glutamate receptor subtype 2, has antipsychotic- and anxiolytic-like effects in mice". The Journal of Pharmacology and Experimental Therapeutics. 318 (1): 173–85. doi:10.1124/jpet.106.102046. PMID16608916.
↑Schaffhauser H, Rowe BA, Morales S, Chavez-Noriega LE, Yin R, Jachec C, Rao SP, Bain G, Pinkerton AB, Vernier JM, Bristow LJ, Varney MA, Daggett LP (October 2003). "Pharmacological characterization and identification of amino acids involved in the positive modulation of metabotropic glutamate receptor subtype 2". Molecular Pharmacology. 64 (4): 798–810. doi:10.1124/mol.64.4.798. PMID14500736.
↑Barda DA, Wang ZQ, Britton TC, Henry SS, Jagdmann GE, Coleman DS, Johnson MP, Andis SL, Schoepp DD (June 2004). "SAR study of a subtype selective allosteric potentiator of metabotropic glutamate 2 receptor, N-(4-phenoxyphenyl)-N-(3-pyridinylmethyl)ethanesulfonamide". Bioorganic & Medicinal Chemistry Letters. 14 (12): 3099–102. doi:10.1016/j.bmcl.2004.04.017. PMID15149652.
↑Pinkerton AB, Vernier JM, Schaffhauser H, Rowe BA, Campbell UC, Rodriguez DE, Lorrain DS, Baccei CS, Daggett LP, Bristow LJ (August 2004). "Phenyl-tetrazolyl acetophenones: discovery of positive allosteric potentiatiors for the metabotropic glutamate 2 receptor". Journal of Medicinal Chemistry. 47 (18): 4595–9. doi:10.1021/jm040088h. PMID15317469.
↑Hemstapat K, Da Costa H, Nong Y, Brady AE, Luo Q, Niswender CM, Tamagnan GD, Conn PJ (July 2007). "A novel family of potent negative allosteric modulators of group II metabotropic glutamate receptors". The Journal of Pharmacology and Experimental Therapeutics. 322 (1): 254–64. doi:10.1124/jpet.106.117093. PMID17416742.
↑Campo B, Kalinichev M, Lambeng N, El Yacoubi M, Royer-Urios I, Schneider M, Legrand C, Parron D, Girard F, Bessif A, Poli S, Vaugeois JM, Le Poul E, Celanire S (December 2011). "Characterization of an mGluR2/3 negative allosteric modulator in rodent models of depression". Journal of Neurogenetics. 25 (4): 152–66. doi:10.3109/01677063.2011.627485. PMID22091727.