Diverse effects of insulin-like growth factor I on glucose, lipid, and amino acid metabolism.
The metabolic effects of recombinant human insulin-like growth factor I (rhIGF-I) on glucose, amino acid, and free fatty acid (FFA) metabolism were examined in nine healthy nonobese subjects. Each received a 3-h primed continuous infusion of rhIGF-I (20 micrograms/kg bolus, 0.4 microgram.kg-1.min-1) while maintaining euglycemia using an exogenous glucose infusion. Total IGF-I levels increased from 125 +/- 11 to 444 +/- 22 ng/ml, and free IGF-I levels rose from undetectable to 73 +/- 5 ng/ml. Insulin levels fell from 95 +/- 9 to 64 +/- 8 pM, and C-peptide fell from 453 +/- 48 to 206 +/- 29 pM; circulating glucagon levels also declined from 72 +/- 9 to 42 +/- 4 pg/ml, rhIGF-I produced a two- to threefold increase in glucose uptake as measured by [3H] glucose (from 10.3 +/- 0.6 to 27.4 +/- 3 mumol.kg-1.m-1), and, despite the fall in insulin secretion, there was a marked 60-70% inhibition of hepatic glucose production. Furthermore, FFA and branched-chain amino acids declined by 40-60% (411 +/- 58 to 165 +/- 36 and 406 +/- 23 to 219 +/- 14 microM, respectively). Our data demonstrate that rhIGF-I has potent effects on glucose (hepatic and peripheral), lipid, and amino acid metabolism in normal humans. The scope of the actions of rhIGF-I closely resemble those of insulin, despite a concomitant inhibitory effect on insulin secretion.
Boulware
S D
SD
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510.
Tamborlane
W V
WV
Matthews
L S
LS
Sherwin
R S
RS
D000328:Adult; D000596:Amino Acids / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism; D008297:Male; D011994:Recombinant Proteins
D000596:Amino Acids; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D005947:Glucose