NUTRITIONAL REGULATION OF CELL AND ORGAN GROWTH, DIFFERENTIATION, AND DEVELOPMENT
Location: Children Nutrition Research Center (Houston, Tx)
Title: Stimulation of whole body protein synthesis by insulin in neonates is dependent on the pattern of amino acids available
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: February 7, 2007
Publication Date: April 28, 2007
Citation: Orellana, R.A., Fiorotto, M.L., Jahoor, F., Burrin, D.G., Nguyen, H.V., Suryawan, A., Davis, T.A. 2007. Stimulation of whole body protein synthesis by insulin in neonates is dependent on the pattern of amino acids available [abstract]. The Federation of American Societies for Experimental Biology Journal. 21(5):A162.
Insulin stimulates muscle protein synthesis in neonatal pigs. To determine insulin's effects on whole body protein turnover, (13)C-leucine was infused for 4 hr during hyperinsulinemic (0, 30, 100, 1000 ng/(kg(0.66)/min))-euglycemic-euaminoacidemic clamps in fasted 7-d-old pigs (n=5/dose). Trophamine was used to clamp amino acids (AA). Plasma insulin levels were 2, 10, 30, and 800 µU/ml. Plasma glucose and essential (E) AA were maintained at fasting levels, but some nonessential (NE) AA decreased. Insulin increased flux (P<.002), reduced proteolysis (P<.02), increased AA oxidation (P<.001), but had no effect on protein synthesis. To determine if the fall in NEAA limited protein synthesis, a new balanced AA mix was developed; protein turnover was determined during hyperinsulinemic (0 vs. 100 ng/(kg(0.66)/min))-euglycemic-euaminoacidemic clamps with either Trophamine or a new AA mix. In contrast to Trophamine, when both plasma EAA and NEAA were maintained at fasting levels with the new AA mix, insulin increased protein synthesis (P<.008). Insulin reduced proteolysis (P<.05) and increased flux and oxidation (P<.05) with both AA mixes, but insulin-stimulated-AA oxidation was less when AA were clamped with the new AA mix (P<.005). The results suggest that the effect of insulin on whole body protein synthesis in neonates depends on the availability of a balanced pattern of EAA and NEAA.