title: Chronic use of pravastatin reduces insulin exocytosis and increases β-cell death in hypercholesterolemic mice.
abstract: We have previously demonstrated that hypercholesterolemic LDL receptor knockout (LDLr(-/-)) mice secrete less insulin than wild-type mice. Removing cholesterol from isolated islets using methyl-beta-cyclodextrin reversed this defect. In this study, we hypothesized that in vivo treatment of LDLr(-/-) mice with the HMGCoA reductase inhibitor pravastatin would improve glucose-stimulated insulin secretion. Female LDLr(-/-) mice were treated with pravastatin (400mg/L) for 1-3 months. Isolated pancreatic islets were assayed for insulin secretion rates, intracellular calcium oscillations, cholesterol levels, NAD(P)H and SNARE protein levels, apoptosis indicators and lipidomic profile. Two months pravastatin treatment reduced cholesterol levels in plasma, liver and islets by 35%, 25% and 50%, respectively. Contrary to our hypothesis, pravastatin treatment increased fasting and fed plasma levels of glucose and decreased markedly (40%) fed plasma levels of insulin. In addition, ex vivo glucose stimulated insulin secretion was significantly reduced after two and three months (36-48%, p<0.05) of pravastatin treatment. Although reducing insulin secretion and insulinemia, two months pravastatin treatment did not affect glucose tolerance because it improved global insulin sensitivity. Pravastatin induced islet dysfunction was associated with marked reductions of exocytosis-related SNARE proteins (SNAP25, Syntaxin 1A, VAMP2) and increased apoptosis markers (Bax/Bcl2 protein ratio, cleaved caspase-3 and lower NAD(P)H production rates) observed in pancreatic islets from treated mice. In addition, several oxidized phospholipids, tri- and diacylglycerols and the proapoptotic lipid molecule ceramide were identified as markers of pravastatin-treated islets. Cell death and oxidative stress (H2O2 production) were confirmed in insulin secreting INS-1E cells treated with pravastatin. These results indicate that chronic treatment with pravastatin impairs the insulin exocytosis machinery and increases β-cell death. These findings suggest that prolonged use of statins may have a diabetogenic effect.
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Estela
authors.initials: E
authors.lastname: Lorza-Gil
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Alessandro G
authors.initials: AG
authors.lastname: Salerno
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Amarylis C B A
authors.initials: AC
authors.lastname: Wanschel
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Jean F
authors.initials: JF
authors.lastname: Vettorazzi
authors.affiliation: Department of Clinical Pathology, Faculty of Medical Sciences, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Mônica S
authors.initials: MS
authors.lastname: Ferreira
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Thiago
authors.initials: T
authors.lastname: Rentz
authors.affiliation: Department of Clinical Pathology, Faculty of Medical Sciences, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Rodrigo R
authors.initials: RR
authors.lastname: Catharino
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil. Electronic address: ho98@unicamp.br.
authors.forename: Helena C F
authors.initials: HC
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D004334:Drug Administration Schedule; D005089:Exocytosis / Q000187:drug effects* / Q000502:physiology; D005260:Female; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000633:toxicity*; D006937:Hypercholesterolemia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017035:Pravastatin / Q000633:toxicity*; D011973:Receptors, LDL / Q000172:deficiency / Q000235:genetics
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007328:Insulin; D011973:Receptors, LDL; D017035:Pravastatin
keywords: Cholesterol; Diabetes; Insulin secretion; LDL receptor; SNARE proteins; Statins