title: Insulin secretion defects of human type 2 diabetic islets are corrected in vitro by a new reactive oxygen species scavenger.
abstract: Oxidative stress is a putative mechanism leading to beta-cell damage in type 2 diabetes. We studied isolated human pancreatic islets from type 2 diabetic and non-diabetic subjects, matched for age and body mass index. Evidence of increased oxidative stress in diabetic islets was demonstrated by measuring nitrotyrosine concentration and by electron paramagnetic resonance. This was accompanied by reduced glucose-stimulated insulin secretion, as compared to non-diabetic islets (Stimulation Index, SI: 0.9 +/- 0.2 vs. 2.0 +/- 0.4, P<0.01), and by altered expression of insulin (approximately -60%), catalase (approximately +90%) and glutathione peroxidase (approximately +140%). When type 2 diabetic islets were pre-exposed for 24 h to the new antioxidant bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate di-hydrochloride, nitrotyrosine levels, glucose-stimulated insulin secretion (SI: 1.6+/-0.5) and gene expressions improved/normalized. These results support the concept that oxidative stress may play a role in type 2 diabetes beta-cell dysfunction; furthermore, it is proposed that therapy with antioxidants could be an interesting adjunctive pharmacological approach to the treatment of type 2 diabetes.
authors.affiliation: Dipartimento di Endocrinologia e Metabolismo, University of Pisa, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Lupi
authors.forename: S
authors.initials: S
authors.lastname: Del Guerra
authors.forename: R
authors.initials: R
authors.lastname: Mancarella
authors.forename: M
authors.initials: M
authors.lastname: Novelli
authors.forename: L
authors.initials: L
authors.lastname: Valgimigli
authors.forename: G F
authors.initials: GF
authors.lastname: Pedulli
authors.forename: M
authors.initials: M
authors.lastname: Paolini
authors.forename: A
authors.initials: A
authors.lastname: Soleti
authors.forename: F
authors.initials: F
authors.lastname: Filipponi
authors.forename: F
authors.initials: F
authors.lastname: Mosca
authors.forename: U
authors.initials: U
authors.lastname: Boggi
authors.forename: S
authors.initials: S
authors.lastname: Del Prato
authors.forename: P
authors.initials: P
authors.lastname: Masiello
authors.forename: P
authors.initials: P
authors.lastname: Marchetti
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism* / Q000503:physiopathology; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D000975:Antioxidants; D007328:Insulin; D017382:Reactive Oxygen Species; C002744:3-nitrotyrosine; D014443:Tyrosine; D005947:Glucose