Negative allosteric modulator activity at rat mGlu5 receptor expressed in HEK293 cells assessed as effect on quisqualate-induced inositol phosphate accumulation incubated for 30 mins by florescence assay
Potency index, ratio of IC50 for MPEP to IC50 for test compound for negative allosteric modulator activity at rat mGlu5 receptor expressed in HEK293 cells
Antagonist activity at rat mGluR5 expressed in CHO cells assessed as inhibition of L-glutamate-induced inositol monophosphate accumulation after 1 hr by FRET assay
Binding Assay: Binding assays were performed as described in Schaffhauser H, Richards J G, Cartmell J, Chaboz S, Kemp J A, Klingelschmidt A, Messer J, Stadler H, Woltering T and Mutel V (1998) In vitro binding characteristics of a new selective group II metabotropic glutamate receptor radioligand, [3H]LY354740, in rat brain. Mol Pharmacol 53:228-233) at room temperature with slight modifications.
Metabotropic Glutamate Receptor Activity Assay: The utility of the compounds in accordance with the present invention as negative allosteric modulators of metabotropic glutamate receptor activity, in particular mGluR5 activity, can be demonstrated by methodology known in the art. Human embryonic kidney (HEK) cells transfected with rat or human mGluR5 were plated in clear bottom assay plates for assay in a Functional Drug Screening System (FDSS). The cells were loaded with a Ca2+-sensitive fluorescent dye (e.g., Fluo-4), and the plates were washed and placed in the FDSS instrument. Test compound was applied to cells 3 seconds after baseline readings were taken. Cells were incubated with the test compounds for 140 seconds and then stimulated with an EC20 concentration of an mGluR5 agonist (e.g., glutamate, 3,5-dihydroxyphenylglycine, or quisqualate); 60-80 seconds later an EC80 concentration of agonist was added and readings taken for an additional 40 seconds. Data were collected at 1 Hz. Negative allosteric modulation of the agonist.