NUTRITION – LEUCINE – RESULTS WHEN ABSENT FROM PROTEIN


1 RESEARCH ARTICLE


ABSENCE OF LEUCINE IN AN EAA SUPPLEMENT REDUCES mTORC1 SIGNALLING FOLLOWING RESISTANCE EXERCISE IN YOUNG FEMALES – 2013


Moberg M, Apró W, Ohlsson I, Pontén M, Villanueva A, Ekblom B, Blomstrand E
METHODS
– 8 young women performed leg press on 2 occasions; they received a solution of either:
(1) an aqueous solution of essential amino acids with leucine (EAA)
(2) or without leucine (EAA-Leu)
RESULTS
(1) Plasma and muscle concentrations of leucine rose 60%-140% with EAA and fell 35%-45% with the EAA-Leu supplement
(2) EAA-trial: plasma and muscle levels of tyrosine (not present in supplement) and sum of EAA were 15%-25% lower during recovery
(3) Phosphorylation of mTOR and p70S6k was elevated to a larger extent following 1 h of recovery with leucine in the supplement (120% vs. 49% and 59- vs. 8-fold for EAA and EAA-Leu, respectively)
(4) Levels of MAFbx and MuRF-1 mRNA and of corresponding proteins were not significantly altered after 3 h recovery from exercise
CONCLUSION
– Leucine enhances stimulatory effect on mTORC1 signalling and reduces level of tyrosine and sum of EAA in muscle and plasma
– This suggests stimulation of protein synthesis and (or) inhibition of breakdown, leading to improvement in net protein balance


 

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