Systematic (IUPAC) name
Clinical data
Legal status
CAS number  N
ATC code ?
IUPHAR ligand
ChemSpider  YesY
Chemical data
Formula C14H11N 
Mol. mass 193.243 g/mol

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.[1] 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,[2][3] and as a positive allosteric modulator of another subtype mGlu4,[4] and there is also evidence for a functional interaction between mGluR5 and NMDA receptors in the same populations of neurons.[5] It was also shown to produce antidepressant[6][7][8] and anxiolytic effects in animals,[9][10][11] and to reduce the effects of morphine withdrawal,[12] most likely due to direct interaction between mGluR5 and the μ-opioid receptor.[13]

The main significance of MPEP has been as a lead compound to develop more potent and selective mGluR5 antagonists such as MTEP,[14] but research using MPEP itself continues, and recently it was shown to reduce self-administration of nicotine,[15][16] cocaine,[17][18] ketamine and heroin in animals,[19] possibly through an MPEP-induced potentiation of the rewarding effect of the self-administered drug,[20] and MPEP was also shown to possess weak reinforcing effects by itself.[21]


  1. ^ Micheli, F (2000). "Methylphenylethynylpyridine (MPEP) Novartis". Current opinion in investigational drugs (London, England : 2000) 1 (3): 355–9.  
  2. ^ O'Leary, DM; Movsesyan, V; Vicini, S; Faden, AI (2000). "Selective mGluR5 antagonists MPEP and SIB-1893 decrease NMDA or glutamate-mediated neuronal toxicity through actions that reflect NMDA receptor antagonism".  
  3. ^ Movsesyan, VA; O'Leary, DM; Fan, L; Bao, W; Mullins, PG; Knoblach, SM; Faden, AI (2001). "MGluR5 antagonists 2-methyl-6-(phenylethynyl)-pyridine and (E)-2-methyl-6-(2-phenylethenyl)-pyridine reduce traumatic neuronal injury in vitro and in vivo by antagonizing N-methyl-D-aspartate receptors". The Journal of Pharmacology and Experimental Therapeutics 296 (1): 41–7.  
  4. ^ Mathiesen, JM; Svendsen, N; Bräuner-Osborne, H; Thomsen, C; Ramirez, MT (2003). "Positive allosteric modulation of the human metabotropic glutamate receptor 4 (hmGluR4) by SIB-1893 and MPEP". British Journal of Pharmacology 138 (6): 1026–30.  
  5. ^ Pisani, A; Gubellini, P; Bonsi, P; Conquet, F; Picconi, B; Centonze, D; Bernardi, G; Calabresi, P (2001). "Metabotropic glutamate receptor 5 mediates the potentiation of N-methyl-D-aspartate responses in medium spiny striatal neurons". Neuroscience 106 (3): 579–87.  
  6. ^ Li, X; Need, AB; Baez, M; Witkin, JM (2006). "Metabotropic glutamate 5 receptor antagonism is associated with antidepressant-like effects in mice". The Journal of Pharmacology and Experimental Therapeutics 319 (1): 254–9.  
  7. ^ Tatarczyńska, E; Klodzińska, A; Chojnacka-Wójcik, E; Palucha, A; Gasparini, F; Kuhn, R; Pilc, A (2001). "Potential anxiolytic- and antidepressant-like effects of MPEP, a potent, selective and systemically active mGlu5 receptor antagonist". British Journal of Pharmacology 132 (7): 1423–30.  
  8. ^ Pilc, A; Kłodzińska, A; Brański, P; Nowak, G; Pałucha, A; Szewczyk, B; Tatarczyńska, E; Chojnacka-Wójcik, E; Wierońska, JM (2002). "Multiple MPEP administrations evoke anxiolytic- and antidepressant-like effects in rats". Neuropharmacology 43 (2): 181–7.  
  9. ^ Kłodzińska, A; Tatarczyńska, E; Chojnacka-Wójcik, E; Pilc, A (2000). "Anxiolytic-like effects of group I metabotropic glutamate antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) in rats". Polish journal of pharmacology 52 (6): 463–6.  
  10. ^ Ballard, TM; Woolley, ML; Prinssen, E; Huwyler, J; Porter, R; Spooren, W (2005). "The effect of the mGlu5 receptor antagonist MPEP in rodent tests of anxiety and cognition: a comparison". Psychopharmacology 179 (1): 218–29.  
  11. ^ Varty, G. B.; Grilli, M.; Forlani, A.; Fredduzzi, S.; Grzelak, M. E.; Guthrie, D. H.; Hodgson, R. A.; Lu, S. X.; Nicolussi, E.; Pond, A. J.; Parker, E. M.; Hunter, J. C.; Higgins, G. A.; Reggiani, A.; Bertorelli, R. (2005). "The antinociceptive and anxiolytic-like effects of the metabotropic glutamate receptor 5 (mGluR5) antagonists, MPEP and MTEP, and the mGluR1 antagonist, LY456236, in rodents: A comparison of efficacy and side-effect profiles". Psychopharmacology 179 (1): 207–217.  
  12. ^ Rasmussen, K; Martin, H; Berger, JE; Seager, MA (2005). "The mGlu5 receptor antagonists MPEP and MTEP attenuate behavioral signs of morphine withdrawal and morphine-withdrawal-induced activation of locus coeruleus neurons in rats". Neuropharmacology 48 (2): 173–80.  
  13. ^ Schröder, H; Wu, DF; Seifert, A; Rankovic, M; Schulz, S; Höllt, V; Koch, T (2009). "Allosteric modulation of metabotropic glutamate receptor 5 affects phosphorylation, internalization, and desensitization of the micro-opioid receptor". Neuropharmacology 56 (4): 768–78.  
  14. ^ Lea Pm, 4th; Faden, AI (2006). "Metabotropic glutamate receptor subtype 5 antagonists MPEP and MTEP". CNS Drug Reviews 12 (2): 149–66.  
  15. ^ Paterson, NE; Semenova, S; Gasparini, F; Markou, A (2003). "The mGluR5 antagonist MPEP decreased nicotine self-administration in rats and mice". Psychopharmacology 167 (3): 257–64.  
  16. ^ Bespalov, AY; Dravolina, OA; Sukhanov, I; Zakharova, E; Blokhina, E; Zvartau, E; Danysz, W; Van Heeke, G; Markou, A (2005). "Metabotropic glutamate receptor (mGluR5) antagonist MPEP attenuated cue- and schedule-induced reinstatement of nicotine self-administration behavior in rats". Neuropharmacology. 49 Suppl 1: 167–78.  
  17. ^ Tessari, M; Pilla, M; Andreoli, M; Hutcheson, DM; Heidbreder, CA (2004). "Antagonism at metabotropic glutamate 5 receptors inhibits nicotine- and cocaine-taking behaviours and prevents nicotine-triggered relapse to nicotine-seeking". European Journal of Pharmacology 499 (1–2): 121–33.  
  18. ^ Paterson, NE; Markou, A (2005). "The metabotropic glutamate receptor 5 antagonist MPEP decreased break points for nicotine, cocaine and food in rats". Psychopharmacology 179 (1): 255–61.  
  19. ^ Van Der Kam, EL; De Vry, J; Tzschentke, TM (2007). "Effect of 2-methyl-6-(phenylethynyl) pyridine on intravenous self-administration of ketamine and heroin in the rat". Behavioural Pharmacology 18 (8): 717–24.  
  20. ^ Van Der Kam, EL; De Vry, J; Tzschentke, TM (2009). "2-Methyl-6-(phenylethynyl)-pyridine (MPEP) potentiates ketamine and heroin reward as assessed by acquisition, extinction, and reinstatement of conditioned place preference in the rat". European Journal of Pharmacology 606 (1–3): 94–101.  
  21. ^ Van Der Kam, EL; De Vry, J; Tzschentke, TM (2009). "The mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) supports intravenous self-administration and induces conditioned place preference in the rat". European Journal of Pharmacology 607 (1–3): 114–20.