Figure 2: Glucagon and GLP-1 production in mouse pancreatic islets. Pancreatic slices from C57BL/6 or NOD mice were costained with anti-glucagon (Cell Signaling Technology, Danvers, MA) (red) and anti-amidated GLP-17-36 (Abcam, Cambridge, MA) (green) antibodies. Nuclei staining (blue) was included to mark all of the cells. GLP-1 was readily detected in the islets from both types of mice, although there was some difference. Most notably, in the normal C57BL/6 mouse, GLP-1 was produced in some α-cells, but mostly co-expressed with glucagon (diamondhead arrows); while in NOD mice with insulitis, cells that express only GLP-1, not glucagon, became detectable (close-head arrows). Open-head arrows mark the examples of cells that produced only glucagon. Detection of glucagon only or GLP-1 only positive cells suggests the antibodies are specific to the corresponding cleaved products. The * marks the area with infiltrating lymphocytes (insulitis). Note: the lymphocytes excused α-cells (defined by proglucagon expression) on their infiltrating path, and some of these α-cells have switched to only produce GLP-1.