Muscle and liver protein synthesis adapt efficiently to food deprivation and refeeding in 12-month-old rats

Our aim was to analyze mechanisms involved in the adaptation of protein metabolism to food deprivation and refeeding in adult rats. Twelve-month-old rats, which had been food-deprived for 113 h and refed for 6 h, were injected subcutaneously with a flooding dose of valine (with 50% [1-13C]-L-valine)...

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Published in:The Journal of nutrition 1996-02, Vol.126 (2), p.516-522
Main Authors: MOSONI, L, MALMEZAT, T, VALLUY, M.-C, HOULIER, M.-L, PATUREAU IRAND, P
Format: Article
Language:English
Subjects:
Aging - metabolism
Animals
Biological and medical sciences
Body Weight - physiology
Eating - physiology
Feeding. Feeding behavior
Food Deprivation - physiology
Fundamental and applied biological sciences. Psychology
Liver
Liver - chemistry
Liver - metabolism
Male
Metabolism
Muscle Proteins - analysis
Muscle Proteins - biosynthesis
Muscle Proteins - genetics
Muscle, Skeletal - chemistry
Muscle, Skeletal - metabolism
Nutrition
Organ Size - physiology
Protein Biosynthesis
Proteins
Proteins - analysis
Proteins - genetics
Rats
Rats, Sprague-Dawley
RNA - analysis
RNA - genetics
RNA - metabolism
Rodents
Time Factors
Valine - analysis
Valine - metabolism
Valine - pharmacology
Vertebrates: anatomy and physiology, studies on body, several organs or systems
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Summary:Our aim was to analyze mechanisms involved in the adaptation of protein metabolism to food deprivation and refeeding in adult rats. Twelve-month-old rats, which had been food-deprived for 113 h and refed for 6 h, were injected subcutaneously with a flooding dose of valine (with 50% [1-13C]-L-valine) to measure in vivo protein synthesis in tibialis anterior, soleus and liver. Protein and RNA contents were also measured. In both muscles, protein mass was maintained during food deprivation. Due to a drop in protein synthetic capacity (Cs), total and myofibrillar protein synthesis rates were reduced in food-deprived rats and were not stimulated by a 6-h refeeding. In contrast, protein levels were maintained lower than RNA levels in liver during food deprivation, and Cs was higher than in fed rats. Protein synthesis rates and ribosomal efficiency were reduced in food-deprived rats. Due to maintenance of protein synthetic capacity, there was a rapid stimulation of liver protein synthesis with refeeding, which induced a significant rise in protein mass (also related to an inhibition of protein degradation). In conclusion, coordinated responses of liver and muscles allowed a sparing of muscle proteins during food deprivation and a rapid recovery of liver proteins during refeeding. Control of ribosome quantity could play a critical role in these adaptations in tissue protein synthesis in adult rats.
ISSN:0022-3166
1541-6100
DOI:10.1093/jn/126.2.516