SB408124

356, 37

Male Wistar rats

SB-408124 is dissolved in saline.

SB-408124 binds hypocretin type 1 receptor (HcrtR1) with pKi values of 7.57. Calcium mobilization studies shows that SB-408124 is a functional antagonist of the OX1 receptor with a affinity of approximately 50-fold selectivity over the OX2 receptor. [1] A recent study indicates that pretreatment of primary cultures of rat astrocytes with SB-401824 before Orexin A administration significantly reduced the stimulatory action of Orexin A on both basal and forskolin-acivated cAMP production. [2]

Whole cell binding assays, After overnight culture in 96-well Packard Cultur plates, the medium is discarded and cells are incubated in buffer containing 150 mM NaCl, 20 mM HEPES and 0.5% bovine serum albumin (pH 7.4) for 60 minutes at 25 C. Saturation studies are carried out by incubating cells with a range of concentrations of [3H]SB-408124 (0.2–24 nM), the total assay volume is 250 uL. Protein content is assayed by lysing cells with 0.1M NaOH and using the Bradford method with bovine serum albumin (BSA) as a standard. Association kinetic studies are performed by measuring the specific binding of [3H]SB-408124 (3 nM) at 1–60 minutes after addition of [3H]SB-408124. All assays are terminated by washing the cells three times with 250uL ice-cold phosphate-buffered saline. A volume of 100 uL of Microscint 40 is added to each well and the plate is left at room temperature for 2 hours. Cell-associated radioactivity is then measured using a Packard Topcount, with a count time of 2 minute/well.

SB408124 is a non-peptide antagonist for OX1 receptor with Ki of 57 nM and 27 nM in both whole cell and membrane, respectively, exhibits 50-fold selectivity over OX2 receptor.