ARS | Publication request: Prolonged stimulation of protein synthesis by leucine is dependent on amino acid availability

Submitted to: European Association of Animal Production Proceedings
Publication Type: Book / Chapter
Publication Acceptance Date: May 10, 2010
Publication Date: September 6, 2010
Citation: Davis, T.A., Suryawan, A., Wilson, F.A., Fiorotto, M.L., Gazzaneo, M.C., Orellana, R.A., Burrin, D.G. 2010. Prolonged stimulation of protein synthesis by leucine is dependent on amino acid availability. In: Crovetto, G.M. editor. Proceedings of the 3rd European Association of Animal Protection International Symposium on Energy and Protein Metabolism and Nutrition, Session 4: Systemic and local regulation mechanisms, an EAAP Publication, Wageningen Academic Publishers, The Netherlands, September 6-10, 2010, Parma, Italy, 127:253-254.

Technical Abstract: Leucine is unique among the amino acids in its ability to enhance protein synthesis by activating translation initiation (Kimball and Jefferson, 2005). Our laboratory has shown that raising leucine to postprandial levels, whilst keeping all other amino acids at the post absorptive, level acutely stimulates protein synthesis in skeletal muscle of neonatal pigs (Escobar "et al.", 2005). However, this response cannot be maintained unless the resulting leucine-induced fall in amino acids is prevented (Escobar "et al.", 2007). The leucine-induced stimulation of protein synthesis is mediated by activation of the mammalian target of rapamycin complex (mTORC1) pathway, but the mechanism by which amino acids activate mTORC1 is not understood. To assess the potential value of leucine supplementation to optimize the nutritional management of neonates, we examined the effect of prolonged leucine infusion on protein synthesis in skeletal muscles of different fiber types and in visceral tissues of the neonatal pig and the role of other amino acids in the response. We further examined the role of leucine in the activation of signalling components of translation.