Functional Assay: Chinese Hamster Ovary recombinant cells expressing the human NK-3 receptor and a construct that encodes the photoprotein apoaequorin were used for this assay. The antagonist activity of compounds of the invention is measured following pre-incubation (3 minutes) of the compound (at various concentrations) with the cells, followed by addition of the reference agonist (NKA) at a final concentration equivalent to the EC80 (3 nM) and recording of emitted light (FDSS 6000 Hamamatsu) over the subsequent 90-second period. The intensity of the emitted light is integrated using the reader software. Compound antagonist activity is measured based on the concentration-dependent inhibition of the luminescence response to the addition of Neurokinin A.
Competitive Binding Assay: The affinity of compounds of the invention for the human NK-3 receptor was determined by measuring the ability of compounds of the invention to competitively and reversibly displace a well-characterized NK-3 radioligand in a concentration-dependent manner.3H-SB222200 Binding Competition Assay with Human NK-3 ReceptorThe ability of compounds of the invention to inhibit the binding of the NK-3 receptor selective antagonist 3H-SB222200 was assessed by an in vitro radioligand binding assay. Membranes were prepared from Chinese hamster ovary recombinant cells stably expressing the human NK-3 receptor. The membranes were incubated with 5 nM 3H-SB222200 (ARC) in a HEPES 25 mM/NaCl 0.1M/CaCl2 1 mM/MgCl2 5 mM/BSA 0.5%/Saponin 10 μg/ml buffer at pH 7.4 and various concentrations of compounds of the invention. The amount of 3H-SB222200 bound to the receptor was determined after filtration by the quantification of membrane associated radioactivity using the TopCount-NXT reader (Packard).
Binding Assay: The affinity of compounds of the invention for the NK-1 receptor was evaluated in CHO recombinant cells which express the human NK-1 receptor. Membrane suspensions were prepared from these cells. The following radioligand: [3H] substance P (PerkinElmer Cat#NET111520) was used in this assay. Binding assays were performed in a 50 mM Tris/5 mM MnCl2/150 mM NaCl/0.1% BSA at pH 7.4. Binding assays consisted of 25 μl of membrane suspension (approximately 5 μg of protein/well in a 96 well plate), 50 μl of compound or reference ligand (Substance P) at increasing concentrations (diluted in assay buffer) and 2 nM [3H] substance P. The plate was incubated 60 min at 25° C. in a water bath and then filtered over GF/C filters (Perkin Elmer, 6005174, presoaked in 0.5% PEI for 2 h at room temperature) with a Filtration unit (Perkin Elmer). The radioactivity retained on the filters was measured by using the TopCount-NXT reader (Packard).
Binding Assay: The affinity of compounds of the invention for the NK-2 receptor was evaluated in CHO recombinant cells which express the human NK-2 receptor. Membrane suspensions were prepared from these cells. The following radioligand [125I]-Neurokinin A (PerkinElmer Cat#NEX252) was used in this assay. Binding assays were performed in a 25 mM HEPES/1 mM CaCl2/5 mM MgCl2/0.5% BSA/10 μg/ml saponin, at pH 7.4. Binding assays consisted of 25 μl of membrane suspension (approximately 3.75 μg of protein/well in a 96 well plate), 50 μl of compound or reference ligand (Neurokinin A) at increasing concentrations (diluted in assay buffer) and 0.1 nM [125I]-Neurokinin A. The plate was incubated 60 min at 25° C. in a water bath and then filtered over GF/C filters (Perkin Elmer, 6005174, presoaked in assay buffer without saponine for 2 h at room temperature) with a Filtration unit (Perkin Elmer). The radioactivity retained on the filters was measured by using the TopCount-NXT reader (Packard).
Inhibition Assay: The hERG inhibition study aims at quantifying the in vitro effects of compounds of the invention on the potassium-selective IKr current generated in normoxic conditions in stably transfected HEK 293 cells with the human ether-a-go-go-related gene (hERG). Whole-cell currents (acquisition by manual patch-clamp) elicited during a voltage pulse were recorded in baseline conditions and following application of tested compounds (5 minutes of exposure). The concentrations of tested compounds (0.3 μM; 3 μM; 10 μM; 30 μM) reflect a range believed to exceed the concentrations at expected efficacy doses in preclinical models. The pulses protocol applied is described as follow: the holding potential (every 3 seconds) was stepped from −80 mV to a maximum value of +40 mV, starting with −40 mV, in eight increments of +10 mV, for a period of 1 second. The membrane potential was then returned to −55 mV, after each of these incremented steps, for 1 second and finally repolarized to −80 mV for 1 second.