Kinase experiment:

Receptor binding is performed using membranes prepared from cells with recombinant expression of adenosine receptors as follows: human A2A and HEK 293, rat A2A and Chinese hamster ovary, human and rat A1 and Chinese hamster ovary, and human A3 and HEK 293. Radioligand competition binding assays are performed in 96-well plates in a total assay volume of 200 μL using a final test drug concentration range of between 0.1 and 3 μM. Membranes are diluted in assay buffer, pH 7.4 (A1 and A2A, Dulbecco's phosphate-buffered saline with 10 mM MgCl2; A3, 50 mM Tris-HCl, 120 mM NaCl, 10 mM MgCl2). To remove endogenous adenosine from the membrane preparations, 4 U/mL adenosine deaminase is added to the membranes, which are then incubated at room temperature for 15 min. Radioligand is added to a final concentration of 0.5 ([3H]SCH 58261, A2A), 1 ([3H]DPCPX, A1), or 0.25 ([125I]AB-MECA, A3) nM. Nonspecific binding is defined by adding 100 nM CGS 15923 (A2A), 100 nM NECA (A1), or 100 nM DPCPX (A3). Plates are incubated at room temperature with agitation for 1.5 h (A2A and A1) or 2 h (A3). Membranes are filtered onto Packard GF-B filter plates and washed in ice-cold assay buffer using a Brandel cell harvester to separate bound and free radioligand. The plates are dried before addition of 45 μL of Microscint 20 to each well. IC50 values are determining by fitting the displacement curves using an iterative curve-fitting program. Ki values are calculated using the Cheng-Prusoff equation[1].

Animal experiment:

Rats[1] Male CD rats weighing 200 to 240 g are used for catalepsy and hypolocomotion studies. Sch412348 is administered orally in 50% polyethylene glycol 400 at a dose volume of 3 to 5 mL/kg. Sch412348 is administered in a volume of 1 mL/kg s.c.

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[1].

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)[1].

[1]. Hodgson RA, et al. Characterization of the potent and highly selective A2A receptor antagonists preladenant and SCH 412348 [7-[2-[4-2,4-difluorophenyl]-1-piperazinyl]ethyl]-2-(2-furanyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] in rodent models of movement disorders and depression. J Pharmacol Exp Ther. 2009 Jul;330(1):294-303.