title: Differential effects of hyperlipidemia on insulin secretion in islets of langerhans from hyperglycemic versus normoglycemic rats.
abstract: Chronic elevations in plasma levels of fatty acids (FAs) adversely affect pancreatic beta-cell function in type 2 diabetes. In vitro, we have previously shown that deleterious effects of prolonged exposure of isolated islets to FAs were dependent on the presence of elevated glucose concentration. This led us to hypothesize that both hyperlipidemia and hyperglycemia must be present simultaneously for FAs to affect beta-cell function. To test this hypothesis in vivo, we administered a high-fat diet for 6 weeks to Goto-Kakizaki (GK) rats. High-fat feeding had no effect on insulin secretion, insulin content, or insulin mRNA levels in islets from normoglycemic Wistar rats. In contrast, high-fat feeding markedly impaired glucose-induced insulin secretion in islets from GK rats. High-fat feeding did not affect triglyceride (TG) content or the rate of glucose oxidation in islets. It was, however, accompanied by a twofold increase in uncoupling protein (UCP)-2 levels in GK rat islets. Insulin treatment completely normalized glucose-induced insulin secretion and prevented the increase in UCP-2 expression in islets from high-fat-fed GK rats. We conclude that hyperlipidemia induced by high-fat feeding affects insulin secretion in islets from hyperglycemic GK rats only, by a mechanism which may involve, at least in part, modulation of UCP-2 expression.
authors.affiliation: Pacific Northwest Research Institute, Seattle, Washington 98122, USA.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Briaud
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Kelpe
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Johnson
authors.forename: Phuong Oanh T
authors.initials: PO
authors.lastname: Tran
authors.forename: Vincent
authors.initials: V
authors.lastname: Poitout
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D004041:Dietary Fats / Q000008:administration & dosage; D005227:Fatty Acids / Q000097:blood; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D005985:Glyceraldehyde / Q000494:pharmacology; D006943:Hyperglycemia / Q000503:physiopathology*; D006949:Hyperlipidemias / Q000209:etiology / Q000503:physiopathology*; D007328:Insulin / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D000078790:Insulin Secretion; D007473:Ion Channels; D007515:Islets of Langerhans / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D010084:Oxidation-Reduction; D011189:Potassium Chloride / Q000494:pharmacology; D011506:Proteins / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013386:Succinates / Q000494:pharmacology; D014280:Triglycerides / Q000032:analysis; D000071246:Uncoupling Protein 2
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D005227:Fatty Acids; D007328:Insulin; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D012333:RNA, Messenger; D013386:Succinates; D014280:Triglycerides; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2; D005985:Glyceraldehyde; D011189:Potassium Chloride; D005947:Glucose; C041105:monomethyl succinate