title: Glucagon-like peptide 1 receptor signaling influences topography of islet cells in mice.
abstract: Glucagon-like peptide 1 (GLP-1) amplifies glucose-induced insulin release in vivo and in vitro. Activation of GLP-1 receptor (GLP-1R) signaling leads to differentiation of exocrine cells towards a beta-cell phenotype in vitro and stimulation of islet cell proliferation in vitro and in vivo, suggesting a potential role for GLP-1 in the modulation of islet growth and differentiation. To determine whether basal levels of GLP-1R signaling are essential for islet development, we examined islet cell composition and topography in GLP-1R-/- mice. Total beta-cell volume and number are not altered, but the topography of beta cells is markedly different in GLP-1R-/- mice compared with GLP-1R+/+ controls. The distribution of beta cells is shifted from large to small and medium-sized islets in the absence of GLP-1R signaling (large islets: 50 +/- 3% in GLP-1R+/+ vs 28 +/- 4% in GLP- 1R-/-, P < 0.01 and medium islets: 32 +/- 2% in GLP- 1R+/+ vs 48 +/- 3% in GLP-1R-/-, P < 0.001). Furthermore, GLP-1R-/- islets exhibit abnormalities in cell topography, with two to threefold more centrally located alpha cells detected in GLP-1R-/- islets. These alterations in alpha- and beta-cell topography indicate that basal levels of GLP-1 signaling in the normal rodent are involved in the normal cellular organization of the endocrine pancreas.
authors.affiliation: Diabetes Research Center, Faculty of Medicine, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium. zling@mebo.vub.ac.be
authors.forename: Z
authors.initials: Z
authors.lastname: Ling
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Zambre
authors.forename: D
authors.initials: D
authors.lastname: Flamez
authors.forename: D J
authors.initials: DJ
authors.lastname: Drucker
authors.forename: D G
authors.initials: DG
authors.lastname: Pipeleers
authors.forename: F C
authors.initials: FC
authors.lastname: Schuit
mesh_terms: D000818:Animals; D002452:Cell Count; D005934:Glucagon / Q000378:metabolism*; D052216:Glucagon-Like Peptide 1; D007091:Image Processing, Computer-Assisted; D007124:Immunoenzyme Techniques; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D010446:Peptide Fragments / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D015398:Signal Transduction; D013047:Specific Pathogen-Free Organisms; D014018:Tissue Distribution
chemical_list: D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D052216:Glucagon-Like Peptide 1; D005934:Glucagon