Assay Method Information
Assay Name:  Measurement of Orexin Type 2 Receptor Agonist Activity
Description:  Chinese hamster ovary (CHO) dhfr-cells forcibly expressing human orexin type 2 receptor (hOX2R) were seeded in each well of Black clear bottom plate (384 wells) (Becton, Dickinson and Company) by 10,000 cells, and cultured for 16 hr in an MEM-alpha (Nikken-Bio Co., Ltd.) medium containing 100 U/ml penicillin, 100 μg/ml streptomycin, 0.5 g/ml G418 (all above Invitrogen), and 10% fetal calf serum (Thermo), under the conditions of 37° C., 5% CO2. After removal of the medium, 30 μL of assay buffer 1 (0.1% bovine serum albumin (Wako Pure Chemical Industries, Ltd.), 1.25 mM probenecid, 10% B2-Quencher, 2.5 μg/mL Fluo-4AM, 10 mM HEPES (DOJINDO)) was added, and the cells were incubated for 60 min under the conditions of 37° C., 5% CO2. A test compound was dissolved in dimethyl sulfoxide to 10 mM, and then diluted with assay buffer 2 (20 mM HEPES, Hanks' balanced salt solution (Invitrogen), 0.1% bovine serum albumin). For the reaction, a test compound solution (10 μL) was added using Fluorescent Imaging Plate Reader TETRA (FLIPR TETRA; manufactured by Molecular Devices), a fluorescence value (excitation wavelength 488 nm, measurement wavelength 570 nm) of each well was measured every one second for 1 min, and the agonist activity was determined using the area of the fluorescence value as an indicator of intracellular Ca2+ concentration. The agonist activity of the test compound was calculated assuming that the fluorescence value of the well added with only the dilution buffer was 0% and the fluorescence value of the well added with 10 nM human orexin B (PEPTIDE INSTITUTE, INC.) buffer was 100%. The agonist activity values EC50 and Emax of each compound are shown below. As used herein, Emax indicates the value at 30 uM concentration when orexin B is converted to a full agonist (maximum value of agonist activity: 100%).
Affinity data for this assay
 
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