The mGlu5 receptor agonist CHPG stimulates striatal glutamate release: possible involvement of A2A receptors

The intrastriatal perfusion of the selective metabotropic glutamate (mGlu)5 receptor agonist (RS)-2-chloro-5-hydroxy-phenylglycine (CHPG, 1000 microM) significantly increased (approximately + 100%, p < 0.05) glutamate extracellular levels with respect to basal values. The potentiating effect of CHPG was prevented by the selective mGlu5 receptor antagonist 2-methyl-6(phenyl-ethynyl)-pyridine (MPEP, 250 microM)) and by the adenosine A2A receptor antagonist SCH 58261 (2 mg/kg, i.p.). The results show that mGlu5 receptors are involved in the regulation of striatal glutamate release and suggest an involvement of adenosine A2A receptors in mGlu5 receptor-mediated effects.