MPEP is a selective and systemically active antagonist of metabotropic glutamate receptor subtype 5 (mGlu5 receptor) with IC50 value of 36nM [1].

MPEP is an antagonist of mGlu5 receptor. It is used as a valuable pharmacological tool to explore the function of its target receptor due to its high selectivity. In L (tk-) cells expressing human mGlu1b receptors, MPEP completely inhibits quisqualate-induced PI hydrolysis with IC50 value of 36nM. MPEP shows no effect in CHO-K1 cells expressing mGlu1b receptor or in L (tk-) mGlu5a cell line. In addition, 100μM MPEP also has no effect on group II and III mGlu receptor subtypes. Moreover, MPEP inhibits the DHPG induced PI hydrolysis in hippocampal, striatal and cortical slices with IC50 values of 8nM, 20.5nM and 17.9nM, respectively. Furthermore, microiontophoretical delivery of MPEP reduces DHPG-induced excitations in vivo. MPEP also shows anxiolytic-or antidepressant-like effects in the Vogel test in rats and in the tail suspension test in mice [1, 2].

References:
[1] Gasparini F, Lingenhohl K, Stoehr N, et al. 2-Methyl-6-(phenylethynyl)-pyridine (MPEP), a potent, selective and systemically active mGlu5 receptor antagonist. Neuropharmacology, 1999, 38(10): 1493-1503.
[2] Tatarczyńska E, Klodzińska A, Chojnacka-Wójcik E, et al. Potential anxiolytic-and antidepressant-like effects of MPEP, a potent, selective and systemically active mGlu5 receptor antagonist. British journal of pharmacology, 2001, 132(7): 1423-1430.