cAMP Assays (GPCR)
Monitoring levels of cAMP, a second messenger produced in response to activation of adenylate cyclase, is one of the most common ways to screen for agonists and antagonists of Gi/Gs protein-coupled receptors. cAMP levels can be monitored using fluorescent molecules that bind to cAMP and are detected using a fluorescence plate reader.
Here are a few application notes on cAMP assays (GPCR) you may find of interest: