ARS | Publication request: Chronic leucine supplementation of a low protein diet increases protein synthesis in skeletal muscle and visceral tissues of neonatal pigs through mTOR signaling

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 21, 2011
Publication Date: March 17, 2011
Citation: Suryawan, A., Murgas-Torrazza, R., Nguyen, H.V., Almonaci, R.D., Gazzaneo, M.C., El-Kadi, S.W., Orellana, R.A., Davis, T.A. 2011. Chronic leucine supplementation of a low protein diet increases protein synthesis in skeletal muscle and visceral tissues of neonatal pigs through mTOR signaling [abstract]. In: Proceedings of the Federation of American Societies for Experimental Biology Conference, Session: Animal research models for macronutrient metabolism, April 07-13, 2011, Washington, D.C. 25:109.5.

Technical Abstract: Leucine acutely stimulates protein synthesis by activating the mammalian target of rapamycin (mTOR) signaling pathway. We hypothesized that leucine supplementation of a low protein diet will enhance protein synthesis and mTOR signaling in the neonate for prolonged periods. Fasted 5-d-old pigs (n=6–8/group) were gavage fed every 4 h either: 1) a low protein diet (LP), 2) a LP supplemented with leucine (LP+L) to equal a high protein diet (HP), or a HP diet. Fractional protein synthesis rates and indices of mTOR signaling activation were examined after 24 h. Protein synthesis rates in the gastrocnemius and masseter muscles, heart, liver, pancreas, and jejunum, but not the kidney were greater in the LP+L than in the LP group (P<0.05) and were further increased in the HP group (P < 0.05). S6K1 phosphorylation in all tissues was higher in the LP+L than in the LP group (P<0.05), and was greater in the HP than in the LP+L and LP groups (P<0.05). These results suggest that while leucine supplementation of a low protein diet increases protein synthesis in most tissues for prolonged periods by enhancing the activation of mTOR, a high protein diet is most effective.