Coordinate reduction of rat pancreatic islet glucokinase and proinsulin mRNA by exercise training.
Exercise training results not only in enhanced insulin sensitivity but also in a reduction in insulin secretion. In this study, we examined the effects of exercise training on the expression of genes potentially related to insulin synthesis and glucose-stimulated insulin release by measuring pancreatic islet proinsulin, glucose-transporter (GLUT2), and glucokinase mRNAs. Female Wistar rats were subjected to 100 min of running at 25 m.min-1 up a 15% incline for 90 min/day for 6 days/wk for 3 wk. Pancreatic mRNA was evaluated by Northern- and dot-blot analysis with [32P]cRNA probes. We found no change in the pancreatic content of GLUT2 mRNA but found marked decreases in the content of proinsulin mRNA (78%, P less than 0.005) and glucokinase mRNA (65%, P less than 0.001). These results suggest that exercise modulates both islet glucose metabolism and insulin synthesis at the level of gene expression. Furthermore, there was a significant correlation between the decreases in glucokinase and proinsulin mRNA concentrations (r = 0.95, P less than 0.001), suggesting that expression of these genes is regulated in parallel.
Koranyi
L I
LI
Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110.
Bourey
R E
RE
Slentz
C A
CA
Holloszy
J O
JO
Permutt
M A
MA
D000818:Animals; D004247:DNA / Q000032:analysis; D015342:DNA Probes; D005260:Female; D005786:Gene Expression Regulation; D005934:Glucagon / Q000032:analysis; D005941:Glucokinase / Q000235:genetics*; D007328:Insulin / Q000032:analysis; D007515:Islets of Langerhans / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D010179:Pancreas / Q000502:physiology; D010805:Physical Conditioning, Animal; D011384:Proinsulin / Q000235:genetics*; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D015342:DNA Probes; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D012313:RNA; D004247:DNA; D005934:Glucagon; D011384:Proinsulin; D005941:Glucokinase