|
|
||||||||
United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030
Studies have shown that protein
synthesis in skeletal muscle of neonatal pigs is uniquely sensitive to
a physiological rise in both insulin and amino acids. Protein synthesis
in cardiac muscle, skin, and spleen is responsive to insulin but not
amino acid stimulation, whereas in the liver, protein synthesis
responds to amino acids but not insulin. To determine the response of
protein synthesis to insulin-like growth factor I (IGF-I) in this
model, overnight-fasted 7- and 26-day-old pigs were infused with IGF-I (0, 20, or 50 µg · kg
1 · h
1) to achieve
levels within the physiological range, while amino acids and glucose
were clamped at fasting levels. Because IGF-I infusion lowers
circulating insulin levels, an additional group of high-dose
IGF-I-infused pigs was also provided replacement insulin (10 ng · kg
0.66 · min
1). Tissue
protein synthesis was measured using a flooding dose of
L-[4-3H]phenylalanine. In 7-day-old pigs,
low-dose IGF-I increased protein synthesis by 25-60% in various
skeletal muscles as well as in cardiac muscle (+38%), skin (+24%),
and spleen (+32%). The higher dose of IGF-I elicited no further
increase in protein synthesis above that found with the low IGF-I dose.
Insulin replacement did not alter the response of protein synthesis to
IGF-I in any tissue. The IGF-I-induced increases in tissue protein
synthesis decreased with development. IGF-I infusion, with or without
insulin replacement, had no effect on protein synthesis in liver,
jejunum, pancreas, or kidney. Thus the magnitude, tissue specificity,
and developmental change in the response of protein synthesis to acute physiological increases in plasma IGF-I are similar to those previously observed for insulin. This study provides in vivo data indicating that
circulating IGF-I and insulin act on the same signaling components to
stimulate protein synthesis and that this response is highly sensitive
to stimulation in skeletal muscle of the neonate.
neonate; insulin action; nutrition; translation initiation; growth
This article has been cited by other articles:
![]() |
B. M. Cleveland, G. M. Weber, K. P. Blemings, and J. T. Silverstein Insulin-like growth factor-I and genetic effects on indexes of protein degradation in response to feed deprivation in rainbow trout (Oncorhynchus mykiss) Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2009; 297(5): R1332 - R1342. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. A. Wilson, A. Suryawan, R. A. Orellana, H. V. Nguyen, A. S. Jeyapalan, M. C. Gazzaneo, and T. A. Davis Fed levels of amino acids are required for the somatotropin-induced increase in muscle protein synthesis Am J Physiol Endocrinol Metab, October 1, 2008; 295(4): E876 - E883. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. A. Wilson, R. A. Orellana, A. Suryawan, H. V. Nguyen, A. S. Jeyapalan, J. Frank, and T. A. Davis Stimulation of muscle protein synthesis by somatotropin in pigs is independent of the somatotropin-induced increase in circulating insulin Am J Physiol Endocrinol Metab, July 1, 2008; 295(1): E187 - E194. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. S. Jeyapalan, R. A. Orellana, A. Suryawan, P. M. J. O'Connor, H. V. Nguyen, J. Escobar, J. W. Frank, and T. A. Davis Glucose stimulates protein synthesis in skeletal muscle of neonatal pigs through an AMPK- and mTOR-independent process Am J Physiol Endocrinol Metab, August 1, 2007; 293(2): E595 - E603. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. S. Lin and C. W. Hsu Differentially transcribed genes in skeletal muscle of Duroc and Taoyuan pigs J Anim Sci, September 1, 2005; 83(9): 2075 - 2086. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Castillo, M. Codina, M. L. Martinez, I. Navarro, and J. Gutierrez Metabolic and mitogenic effects of IGF-I and insulin on muscle cells of rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2004; 286(5): R935 - R941. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. A. Davis, J. A. Bush, R. C. Vann, A. Suryawan, S. R. Kimball, and D. G. Burrin Somatotropin regulation of protein metabolism in pigs J Anim Sci, January 1, 2004; 82(13_suppl): E207 - 213. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. A. J. Adegoke, M. I. McBurney, S. E. Samuels, and V. E. Baracos Modulation of intestinal protein synthesis and protease mRNA by luminal and systemic nutrients Am J Physiol Gastrointest Liver Physiol, June 1, 2003; 284(6): G1017 - G1026. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |