Reagents to detect GLP1R in tissue include antibodies, reporter mice, and fluorescent ligands . Historically, studies with antibodies have been confounded by the use of non-specific antisera, which detect non-GLP1R targets . Two specific antibodies now exist and have been extensively validated, including in GLP1R knockout tissue, or cells heterologously expressing human GLP1R . However, the available antibodies do not perform well for immunofluorescent staining in the brain and cannot be used for live visualization of the GLP1R using microscopy. Reporter mice, where cells that express(ed) GLP1R are selectively labeled with high fidelity, have been used to address this limitation, demonstrating excellent concurrence with other approaches . However, reporter alleles neither visualize the receptor itself nor differentiate cells that once expressed GLP1R, but no longer do so (the cell will be indelibly marked). Fluorescent agonists bind the GLP1R orthosteric site in live tissue and can also be fixed to allow further immunohistochemical analysis . However, this approach is confounded by activation of GLP1R and as such the unstimulated fraction cannot be studied in live cells.