Chronic aerobic exercise enhances components of the classical and novel insulin signalling cascades in Sprague-Dawley rat skeletal muscle.
OBJECTIVE
The aim of this study was to provide a more extensive evaluation of the effects of chronic aerobic exercise on various components of the insulin signalling cascade in normal rodent skeletal muscle because of the limited body of literature that exists in this area of investigation.


METHODS
Male Sprague-Dawley rats were assigned to either control (n = 7) or chronic aerobic exercise (n = 7) groups. Aerobic exercise animals were run 3 day week(1) for 45 min on a motor-driven treadmill (32 m min(1), 15% grade) for a 12 week period. Following the training period, all animals were subjected to hind limb perfusion in the presence of 500 microU mL(1) insulin to determine what effect chronic aerobic training had on various components of the insulin signalling cascade, c-Cbl protein concentration and c-Cbl phosphorylation.


RESULTS
Twelve weeks of aerobic training did not alter skeletal muscle Akt 1/2 protein concentration, Akt Ser 473 phosphorylation, Akt Thr 308 phosphorylation, Akt 1 activity, aPKC-zeta protein concentration, aPKC-lambda protein concentration or c-Cbl protein concentration. In contrast, chronic aerobic exercise increased insulin-stimulated phosphatidylinositol 3-kinase, Akt 2 kinase and aPKC-zeta/lambda kinase activities, as well as c-Cbl tyrosine phosphorylation, in a fibre type specific response to aerobic training. In addition, chronic aerobic exercise enhanced insulin-stimulated plasma membrane glucose transporter 4 (GLUT4) protein concentration.


CONCLUSIONS
Collectively, these findings suggest that chronic aerobic exercise enhances components of both the classical and novel insulin signalling cascades in normal rodent skeletal muscle, which may contribute to an increased insulin-stimulated plasma membrane GLUT4 protein concentration.
Bernard
J R
JR
Exercise Biochemistry Laboratory, Department of Kinesiology, College of Health and Human Development, California State University Northridge, 91330-8287, USA.
Crain
A M
AM
Rivas
D A
DA
Herr
H J
HJ
Reeder
D W
DW
Yaspelkis
B B
BB
D019325:3-O-Methylglucose / Q000378:metabolism; D000332:Aerobiosis / Q000502:physiology*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000097:blood; D009124:Muscle Proteins / Q000097:blood / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology
D019325:3-O-Methylglucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C526296:Irs1 protein, rat; C495694:Slc2a4 protein, rat; C494920:Akt1 protein, rat