Sch412348 is a potent competitive antagonist of the human adenosine A2A receptor (Ki=0.6 nM) and has >1000-fold selectivity over all other adenosine receptors. Sch412348 (SCH 412348) also completely antagonizes cAMP in cells expressing the recombinant human A2A receptor. Sch412348 is determined to have KB values of 0.3 nM, respectively at the A2A receptor; the value are in good agreement with the Ki values determined in radioligand binding assays. A similar functional assay with A2B receptor-expressing cells is used to demonstrate selectivity over A2B receptors. In this assay, the KB value for Sch412348 is 273 nM, indicating that Sch412348 is 910-fold selective for the A2A receptor over the A2B receptor. Oral administration of Sch412348 (0.1-1 mg/kg) to rats potentiates 3,4-dihydroxy-L-phenylalanine (L-Dopa)-induced contralateral rotations after 6-hydroxydopamine lesions in the medial forebrain bundle and potently attenuates the cataleptic effects of haloperidol. Sch412348 (1 and 3 mg/kg) dose-dependently attenuates haloperidol-induced catalepsy 1 h [F(3,20)=3.9, p<0.05] and 4 h [F(3,20)=7.5, p<0.01] after dosing. Sch412348 [F(2,51) =10.6, p<0.01] (0.1-1 mg/kg) reduces immobility time in the mouse tail suspension test (TST) at 1 mg/kg. Sch412348 (SCH 412348) significantly increases activity levels in the mouse [F(4,27)=2.9, p<0.05]. Both the 0.3 and 3 mg/kg treatment groups are significantly more active than vehicle-treated mice. The 1 mg/kg group approached significance (p=0.052).