Assay Method Information

Assay Name:  Metabotropic Glutamate Receptor Activity
Description:  The disclosed compounds and compositions can be evaluated for their ability to act as a potentiatior of metabotropic glutamate receptor activity, in particular mGluR4 activity, by any suitable known methodology known in the art. For example, Chinese Hamster Ovary (CHO) cells transfected with human mGluR4 or HEK cells co-transfected with rat mGluR4 and the G-protein regulated Inwardly Rectifying Potassium channel (GIRK) were plated in clear bottom assay plates for assay in a Hamamatsu FDSS Fluorometric Plate Reader. The cells were loaded with either a Ca2+-sensitive fluorescent dye or the thallium responsive dye and the plates were washed and placed into a suitable kinetic plate reader. For human mGluR4 assays, a fluorescence baseline was established for 3-5 seconds, the disclosed compounds were then added to the cells, and the response in cells was measured. Approximately two and a half minutes later, a concentration of mGluR4 orthosteric agonist (e.g. glutamate, L-AP4, or L-SOP) eliciting approximately 20% (EC20) of the maximal agonist response was added to the cells, and the response was measured. Two minutes later, a concentration of mGluR4 agonist (e.g. glutamate, L-AP4, or L-SOP) eliciting 80% (EC80) of the maximal agonist response was added to the cells, and the response was measured. For rat mGluR4/GIRK experiments, a baseline was established for approximately five seconds, disclosed compounds were added, and either an EC20 or EC80 concentration of agonist was added approximately two and one half minutes later. Potentiation or antagonism of the agonist response of mGluR4 by the disclosed compounds was observed as an increase or decrease in response to the EC20 concentration of agonist in the presence of compound compared to the response to agonist in the absence of compound. Similarly, potentiation or antagonism of the agonist response of mGluR4 by the disclosed compounds was observed as an increase or decrease in response to the EC80 concentration of agonist in the presence of compound compared to the response to agonist in the absence of compound.The above described assay operated in two modes. In the first mode, a range of concentrations of the disclosed compounds are added to cells, followed by a single fixed concentration of agonist. If the compound acts as a potentiatior, an EC50 value for potentiation and a maximum extent of potentiation by the compound at this concentration of agonist is determined by non-linear curve fitting. If the compound acts as an antagonist, an IC50 value is determined by non-linear curve fitting. In the second mode, several fixed concentrations of the disclosed compounds are added to various wells on a plate, followed by a range in concentrations of agonist for each concentration of disclosed compound. The EC50 values for the agonist at each concentration of compound are determined by non-linear curve fitting. A decrease in the EC50 value of the agonist with increasing concentrations of the sample compound (a leftward shift of the agonist concentration-response curve) is an indication of the degree of mGluR4 potentiation at a given concentration of the sample compound. A decrease in the maximal response of the agonist with increasing concentrations of the sample compounds, with or without a rightward shift in agonist potency, is an indication of the degree of antagonism at mGluR4. The second mode also indicates whether the sample compounds also affect the maximum response to mGluR4 to agonists.
Affinity data for this assay
 

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