Microglia express proglucagon mRNA and express and secrete GLP-1. GLP-1-positive cells in A, tissue sections from the murine cortex, and B, primary glial cell cultures, GLP-1-positive (green, top right panel) microglia (red, top left panel). Cells positive for GLP-1 are also positive for the microglia marker CD11b (bottom left panel), whereas the remaining glial cells in the culture (indicated by blue DAPI staining in the bottom right panel) are positive for neither GLP-1 nor CD11b. White arrows indicate cells double-positive for CD11b and GLP-1. C. BV-2 cells secrete GLP-1, and this secretion is stimulated in response to a 2-h treatment with 10 μM of the adenylyl cyclase activator forskolin. GLP-1 secretion was measured as pM and presented as percent of control. D. Expression of proglucagon is increased in response to a 2-h treatment with 10 μM forskolin. Proglucagon mRNA expression was normalized to mRNA expression of GAPDH, which was used as an internal control. Bars represent mean ± SEM, n = 3-4, in triplicates. * P < 0.05 for a chance difference vs. untreated controls. Statistical analysis was performed using Student’s t-test.