title: Endurance exercise training increases insulin responsiveness in isolated adipocytes through IRS/PI3-kinase/Akt pathway.
abstract: Endurance exercise training promotes important metabolic adaptations, and the adipose tissue is particularly affected. The aim of this study was to investigate how endurance exercise training modulates some aspects of insulin action in isolated adipocytes and in intact adipose tissue. Male Wistar rats were submitted to daily treadmill running (1 h/day) for 7 wk. Sedentary age-matched rats were used as controls. Final body weight, body weight gain, and epididymal fat pad weight did not show any statistical differences between groups. Adipocytes from trained rats were smaller than those from sedentary rats (205 +/- 16.8 vs. 286 +/- 26.4 pl; P < 0.05). Trained rats showed decreased plasma glucose (4.9 +/- 0.13 vs. 5.3 +/- 0.07 mM; P < 0.05) and insulin levels (0.24 +/- 0.012 vs. 0.41 +/- 0.049 mM; P < 0.05) and increased insulin-stimulated glucose uptake (23.1 +/- 3.1 vs. 12.1 +/- 2.9 pmol/cm(2); P < 0.05) compared with sedentary rats. The number of insulin receptors and the insulin-induced tyrosine phosphorylation of insulin receptor-beta subunit did not change between groups. Insulin-induced tyrosine phosphorylation insulin receptor substrates (IRS)-1 and -2 increased significantly (1.57- and 2.38-fold, respectively) in trained rats. Insulin-induced IRS-1/phosphatidylinositol 3 (PI3)-kinase (but not IRS-2/PI3-kinase) association and serine Akt phosphorylation also increased (2.06- and 3.15-fold, respectively) after training. The protein content of insulin receptor-beta subunit, IRS-1 and -2, did not differ between groups. Taken together, these data support the hypothesis that the increased adipocyte responsiveness to insulin observed after endurance exercise training is modulated by IRS/PI3-kinase/Akt pathway.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, 05508-900, Sao Paulo, Brazil.
authors.forename: Sidney B
authors.initials: SB
authors.lastname: Peres
authors.forename: Solange M Franzói
authors.initials: SM
authors.lastname: de Moraes
authors.forename: Cecilia E M
authors.initials: CE
authors.lastname: Costa
authors.forename: Luciana C
authors.initials: LC
authors.lastname: Brito
authors.forename: Julie
authors.initials: J
authors.lastname: Takada
authors.forename: Sandra
authors.initials: S
authors.lastname: Andreotti
authors.forename: Magaly A
authors.initials: MA
authors.lastname: Machado
authors.forename: Maria Isabel C
authors.initials: MI
authors.lastname: Alonso-Vale
authors.forename: Cristina N
authors.initials: CN
authors.lastname: Borges-Silva
authors.forename: Fabio B
authors.initials: FB
authors.lastname: Lima
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D005080:Exercise Test; D007328:Insulin / Q000008:administration & dosage / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000379:methods; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C526296:Irs1 protein, rat; C494920:Akt1 protein, rat