title: Circulating lipids are lowered but pancreatic islet lipid metabolism and insulin secretion are unaltered in exercise-trained female rats.
abstract: Deteriorating islet beta-cell function is key in the progression of an impaired glucose tolerance state to overt type 2 diabetes (T2D), a transition that can be delayed by exercise. We have previously shown that trained rats are protected from heart ischemia-reperfusion injury in correlation with an increase in cardiac tissue fatty-acid oxidation. This trained metabolic phenotype, if induced in the islet, could also prevent beta-cell failure in the pathogenesis of T2D. To assess the effect of training on islet lipid metabolism and insulin secretion, female Sprague-Dawley rats were exercised on a treadmill for 90 min/d, 4 d/week, for 10 weeks. Islet fatty-acid oxidation, the expression of key lipid metabolism genes, and glucose-stimulated insulin secretion were determined in freshly isolated islets from trained and sedentary control rats after a 48 h rest period from the last exercise. Although this moderate training reduced plasma glycerol, free fatty acids, and triglyceride levels by about 40%, consistent with reduced lipolysis from adipose tissue, it did not alter islet fatty-acid oxidation, nor the islet expression of key transcription factors and enzymes of lipid metabolism. The training also had no effect on glucose-stimulated insulin secretion or its amplification by free fatty acids. In summary, chronic exercise training did not cause an intrinsic change in islet lipid metabolism. Training did, however, substantially reduce the exposure of islets to exogenous lipid, thereby providing a potential mechanism by which exercise can prevent islet beta-cell failure leading to T2D.
authors.affiliation: Molecular Nutrition Unit and the Montreal Diabetes Research Center, Université de Montréal and the Centre Hospitalier de l'Université de Montréal, Montreal, QC H2L 4M1, Canada.
authors.forename: Julien
authors.initials: J
authors.lastname: Lamontagne
authors.forename: Pellegrino
authors.initials: P
authors.lastname: Masiello
authors.forename: Mariannick
authors.initials: M
authors.lastname: Marcil
authors.forename: Viviane
authors.initials: V
authors.lastname: Delghingaro-Augusto
authors.forename: Yan
authors.initials: Y
authors.lastname: Burelle
authors.forename: Marc
authors.initials: M
authors.lastname: Prentki
authors.forename: Christopher James
authors.initials: CJ
authors.lastname: Nolan
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics*; D000704:Analysis of Variance; D000818:Animals; D005230:Fatty Acids, Nonesterified; D005260:Female; D007328:Insulin / Q000097:blood*; D007515:Islets of Langerhans / Q000378:metabolism*; D050356:Lipid Metabolism / Q000235:genetics*; D008055:Lipids / Q000097:blood*; D008969:Molecular Sequence Data; D010805:Physical Conditioning, Animal; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids