Immunization against IGF-I prevents increases in protein synthesis in diabetic rats after resistance exercise.
These studies examined whether passive immunization against insulin-like growth factor I (IGF-I) would prevent increases in rates of protein synthesis in skeletal muscle of diabetic rats after resistance exercise. Male Sprague-Dawley rats were pancreatectomized and randomly assigned to either an exercise or a sedentary group. Animals in each of these groups received either an IGF-I antibody or a nonspecific IgG from a subcutaneous osmotic pump. Exercise did not change plasma or gastrocnemius IGF-I concentrations in nondiabetic rats. However, plasma and muscle IGF-I concentrations were higher in IgG-treated diabetic rats that exercised compared with respective sedentary groups (P < 0.05). Passively immunized diabetic rats did not exhibit the same exercise-induced increase in IGF-I concentrations. In nondiabetic rats, protein synthesis rates were higher after exercise in both control and immunized groups. In diabetic rats, exercise increased protein synthesis in the IgG-treated animals but not in those treated with IGF-I antibody. There was also a significant positive correlation between both plasma and gastrocnemius IGF-I concentrations and rates of protein synthesis in diabetic (P < 0.01), but not nondiabetic, rats. These results suggest that IGF-I is compensatory for insulin in hypoinsulinemic rats by facilitating an anabolic response after acute resistance exercise.
Fedele
M J
MJ
Noll Physiological Research Center, Pennsylvania State University, University Park, PA 16802, USA. mfedele@uic.edu
Lang
C H
CH
Farrell
P A
PA
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000503:physiopathology; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology; D007114:Immunization; D007074:Immunoglobulin G / Q000494:pharmacology; D007328:Insulin / Q000097:blood; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000276:immunology* / Q000378:metabolism*; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007074:Immunoglobulin G; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D009124:Muscle Proteins; D007334:Insulin-Like Growth Factor I