Acute IGF-I infusion stimulates protein synthesis in skeletal muscle and other tissues of neonatal pigs
| Autor: | Philip R. Beckett, Rhonda C. Vann, Douglas G. Burrin, Peter J. Reeds, Teresa A. Davis, Hanh V. Nguyen, Marta L. Fiorotto, Jill A. Bush |
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| Rok vydání: | 2002 |
| Předmět: |
Blood Glucose
medicine.medical_specialty Swine Physiology Endocrinology Diabetes and Metabolism medicine.medical_treatment Stimulation Biology Pregnancy Physiology (medical) Internal medicine medicine Protein biosynthesis Animals Insulin Insulin-Like Growth Factor I Muscle Skeletal Pancreatic hormone chemistry.chemical_classification Insulin blood Age Factors Cardiac muscle Skeletal muscle Amino acid Insulin-Like Growth Factor Binding Protein 3 Endocrinology medicine.anatomical_structure Animals Newborn chemistry Protein Biosynthesis Animal Nutritional Physiological Phenomena Female Amino Acids Essential |
| Zdroj: | American Journal of Physiology-Endocrinology and Metabolism. 283:E638-E647 |
| ISSN: | 1522-1555 0193-1849 |
| DOI: | 10.1152/ajpendo.00081.2002 |
| Popis: | 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 ofl-[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. |
| Databáze: | OpenAIRE |
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