Exercise training enhances rat pancreatic islets anaplerotic enzymes content despite reduced insulin secretion

• Published in: European journal of applied physiology 2011-09, Vol.111 (9), p.2369-2374
• Main Authors: Zoppi, Claudio C., Calegari, Vivian C., Silveira, Leonardo R., Carneiro, Everardo M., Boschero, Antonio C.
• Format: Article
• Language: English
• Subjects: Animals; ATP Citrate (pro-S)-Lyase - metabolism; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Dehydrogenases; Diabetes; Enzymes; Enzymes - analysis; Enzymes - metabolism; Exercise; Fitness training programs; Fundamental and applied biological sciences. Psychology; Glucose; Glucose - pharmacology; Glutamate Dehydrogenase - metabolism; Human Physiology; Hypotheses; Insulin; Insulin - metabolism; Insulin Secretion; Islets of Langerhans - drug effects; Islets of Langerhans - enzymology; Islets of Langerhans - metabolism; Kinases; Laboratory animals; Male; Metabolism; Musculoskeletal system; Occupational Medicine/Industrial Medicine; Physical Conditioning, Animal - adverse effects; Physical Conditioning, Animal - physiology; Physical Endurance - physiology; Protein Kinases - metabolism; Pyruvate Carboxylase - metabolism; Rats; Rats, Wistar; Secretory Pathway - drug effects; Short Communication; Sports Medicine; Up-Regulation - drug effects; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-011-1842-2

Endurance exercise has been shown to reduce pancreatic islets glucose-stimulated insulin secretion (GSIS). Anaplerotic/cataplerotic pathways are directly related to GSIS signaling. However, the effect of endurance training upon pancreatic islets anaplerotic enzymes is still unknown. In this sense, we tested the hypothesis that endurance exercise decreases GSIS by reducing anaplerotic/cataplerotic enzymes content. Male Wistar rats were randomly assigned to one of the four experimental groups as follows: control sedentary group (CTL), trained 1 day per week (TRE1×), trained 3 days per week (TRE3×) and trained 5 days per week (TRE5x) and submitted to an 8 weeks endurance-training protocol. After the training protocol, pancreatic islets were isolated and incubated with basal (2.8 mM) and stimulating (16.7 mM) glucose concentrations for GSIS measurement by radioimmunoassay. In addition, pyruvate carboxylase (PYC), pyruvate dehydrogenase (PDH), pyruvate dehydrogenase kinase 4 (PDK4), ATP-citrate lyase (ACL) and glutamate dehydrogenase (GDH) content were quantified by western blotting. Our data showed that 8 weeks of chronic endurance exercise reduced GSIS by 50% in a dose-response manner according to weekly exercise frequency. PYC showed significant twofold increase in TRE3×. PYC enhancement was even higher in TRE5× ( p