Adenosine A₂ receptor-mediated modulation of contralateral rotation induced by metabotropic glutamate receptor activation

Systemic pretreatment with the adenosine receptor antagonist theophylline significantly decreases contralateral rotation induced by unilateral intrastriatal 1-aminocyclopentane-1S,3R-dicarboxylic acid (1S,3R-ACPD). Intrastriatal or intrasubthalamic nucleus coadminstration of theophylline and 1S,3R-ACPD significantly decreases contralateral rotation suggesting that metabotropic glutamate (mGlu) receptors and adenosine receptors interact locally. These appear to be adenosine A₂ receptor effects as the adenosine A₂ receptor antagonist 8-(3-chlorostyryl)caffeine (CSC) also decreases contralateral rotation induced by unilateral intrastriatal and intrasubthalamic nucleus administration of 1S,3R-ACPD, while the adenosine A₁ receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) has no effect. Pretreatment with the adenosine A₂ receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5′-N-ethylcarboxamido adenosine hydrochloride (CGS 21680) potentiates contralateral rotation induced by unilateral striatal 1S,3R-ACPD, whereas pretreatment with the adenosine A₁ receptor agonist N⁶-cyclopentyl-adenosine (CPA) has no effect. These results suggest that mGlu receptor effects may be due, in part, to modulation of adenosine action.