The present invention relates generally to transgene constructs, transgenic non-human animals comprising transgene constructs, methods of making and methods of using the transgenic non-human animals comprising transgene constructs. An embodiment of the invention relates to methods of assaying the activation of GPCR ligands non-invasively in whole animals, tissue slices, or in native cells using a transgenic model containing a bioluminescent transgene reporter system that is responsive to pathway modulation following ligand binding of GPCR receptors.
