title: Endurance training activates AMP-activated protein kinase, increases expression of uncoupling protein 2 and reduces insulin secretion from rat pancreatic islets.
abstract: Endurance exercise is known to enhance peripheral insulin sensitivity and reduce insulin secretion. However, it is unknown whether the latter effect is due to the reduction in plasma substrate availability or alterations in β-cell secretory machinery. Here, we tested the hypothesis that endurance exercise reduces insulin secretion by altering the intracellular energy-sensitive AMP-activated kinase (AMPK) signaling pathway. Male Wistar rats were submitted to endurance protocol training one, three, or five times per week, over 8 weeks. After that, pancreatic islets were isolated, and glucose-induced insulin secretion (GIIS), glucose transporter 2 (GLUT2) protein content, total and phosphorylated calmodulin kinase kinase (CaMKII), and AMPK levels as well as peroxisome proliferator-activated receptor-γ coactivator-1-α (PGC-1α) and uncoupling protein 2 (UCP2) content were measured. After 8 weeks, chronic endurance exercise reduced GIIS in a dose-response manner proportionally to weekly exercise frequency. Contrariwise, increases in GLUT2 protein content, CaMKII and AMPK phosphorylation levels were observed. These alterations were accompanied by an increase in UCP2 content, probably mediated by an enhancement in PGC-1α protein expression. In conclusion, chronic endurance exercise induces adaptations in β-cells leading to a reduction in GIIS, probably by activating the AMPK signaling pathway.
authors.affiliation: Endocrine Pancreas and Metabolism Laboratory, Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, CEP: 13083-865, Brazil. claudiozoppi@hotmail.com
authors.forename: Vivian Cristine
authors.initials: VC
authors.lastname: Calegari
authors.forename: Claudio Cesar
authors.initials: CC
authors.lastname: Zoppi
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: Rezende
authors.forename: Leonardo Reis
authors.initials: LR
authors.lastname: Silveira
authors.forename: Everardo Magalhães
authors.initials: EM
authors.lastname: Carneiro
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Boschero
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D051273:Glucose Transporter Type 2 / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007473:Ion Channels / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D024101:Mitochondrial Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D016601:RNA-Binding Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000378:metabolism; D000071246:Uncoupling Protein 2
chemical_list: D051273:Glucose Transporter Type 2; D007328:Insulin; D007473:Ion Channels; D024101:Mitochondrial Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D055372:AMP-Activated Protein Kinases