ROLE OF ADENOSINE A(2A) RECEPTORS IN THE NUCLEUS-ACCUMBENS

1. Adult male mice were stereotaxically Implanted with permanent indwe lling guide cannulae for bilateral injections into the nucleus accumbe ns (ACB). 2. The effects on spontaneous locomotor activity of selectiv e agonists for adenosine receptor subtypes were examined following bil ateral injections into the ACB. 3. Intra-ACB injections of CGS 21680, a potent and selective agonist at striatal adenosine A(2a) receptors, elicited pronounced, dose-related reductions in locomotor activity wfi ereas similar bilateral dosages of CPA, a selective agonist at adenosi ne A(1) receptors, did not significantly affect locomotor activity. 4. The pronounced locomotor depression elicited by intra-ACB injections of CGS 21680 were completely blocked by I.P. pretreatment with DMPX, a n adenosine receptor antagonist exhibiting selectivity for striatal A( 2) receptors, at a dosage which alone had no significant effect on loc omotor activity. 5. Adenosine A(2a) receptors in the nucleus accumbens may selectively modulate dopamine-mediated mesolimbic behavioral circ uits involved in spontaneous locomotion.