Effects of the adenosine A1 antagonist DPCPX in combination with 0.1 mg/kg haloperidol. (A) Mean (±S.E.M.) number of lever presses after treatment with vehicle or haloperidol plus various doses of DPCPX are shown. (B) Mean (±S.E.M.) intake of lab chow (in grams) after treatment with vehicle or haloperidol plus various doses of DPCPX are shown. Veh/Veh (vehicle plus vehicle), HP/Veh (0.1 mg/kg haloperidol plus vehicle), HP/DPC 0.187 (0.1 mg/kg haloperidol plus 0.1875 mg/kg DPCPX), HP/DPC 0.37 (0.1 mg/kg haloperidol plus 0.375 mg/kg DPCPX), HP/PDC 0.75 (0.1 mg/kg haloperidol plus 0.75 mg/kg DPCPX). #p < 0.01, haloperidol different from vehicle/vehicle, planned comparison.