title: DPP-4 inhibition improves glucose tolerance and increases insulin and GLP-1 responses to gastric glucose in association with normalized islet topography in mice with beta-cell-specific overexpression of human islet amyloid polypeptide.
abstract: Inhibition of dipeptidyl peptidase-4 (DPP-4) is currently explored as a novel therapy of type 2 diabetes. The strategy has been shown to improve glycemia in most, but not all, rodent forms of glucose intolerance. In this study, we explored the effects of DPP-4 inhibition in mice with beta-cell overexpression of human islet amyloid polypeptide (IAPP). We therefore administered the orally active and highly selective DPP-4 inhibitor, vildagliptin (3 micromol/mouse daily) to female mice with beta-cell overexpression of human IAPP. Controls were given plain water, and a series of untreated wildtype mice was also included. After five weeks, an intravenous glucose tolerance test showed improved glucose disposal and a markedly enhanced insulin response in mice treated with vildagliptin. After eight weeks, a gastric tolerance test showed that vildagliptin improved glucose tolerance and markedly (approximately ten-fold) augmented the insulin response in association with augmented (approximately five-fold) levels of intact glucagon-like peptide-1 (GLP-1). Furthermore, after nine weeks, islets were isolated. Islets from vildagliptin-treated mice showed augmented glucose-stimulated insulin response and a normalization of the islet insulin content, which was reduced by approximately 50% in transgenic controls versus wildtype animals. Double immunostaining of pancreatic islets for insulin and glucagon revealed that transgenic islets displayed severely disturbed intra-islet topography with frequently observed centrally located alpha-cells. Treatment with vildagliptin restored the islet topography. We therefore conclude that DPP-4 inhibition improves islet function and islet topography in mice with beta-cell specific transgenic overexpression of human IAPP.
authors.affiliation: Department of Clinical Sciences, Lund University, Lund, Sweden. Bo.Ahren@med.lu.se
authors.forename: Bo
authors.initials: B
authors.lastname: Ahrén
authors.forename: Maria Sörhede
authors.initials: MS
authors.lastname: Winzell
authors.forename: Nils
authors.initials: N
authors.lastname: Wierup
authors.forename: Frank
authors.initials: F
authors.lastname: Sundler
authors.forename: Bryan
authors.initials: B
authors.lastname: Burkey
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hughes
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology; D000682:Amyloid / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D054873:Dipeptidyl-Peptidase IV Inhibitors; D005260:Female; D052216:Glucagon-Like Peptide 1 / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000494:pharmacology*; D050417:Insulin-Secreting Cells / Q000378:metabolism; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009570:Nitriles / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D000077597:Vildagliptin
chemical_list: D000682:Amyloid; D054873:Dipeptidyl-Peptidase IV Inhibitors; D007328:Insulin; D058228:Islet Amyloid Polypeptide; D009570:Nitriles; D011759:Pyrrolidines; D052216:Glucagon-Like Peptide 1; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4; D000077597:Vildagliptin; D005947:Glucose; D000218:Adamantane