Effect of feeding a high-protein diet following an 18-hour period of feed withholding on mammalian target of rapamycin-dependent signaling in skeletal muscle of mature horses

Kristine L. Urschel, Jeffery Escobar, L. Jill McCutcheon, Raymond J. Geor

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Objective - To determine the effect of refeeding following an 18-hour period of feed withholding on the phosphorylation of translation initiation factors in the skeletal muscle of mature horses. Animals - 8 adult horses. Procedures - Following an 18-hour period of feed withholding, horses either continued to have feed withheld (postabsorptive state) or were fed 2 g/kg of a high-protein feed (33% crude protein) at time 0 and 30 minutes (postprandial state). Blood samples were taken throughout the experimental period. At 90 minutes, a biopsy specimen was taken from the middle gluteal muscle to measure the phosphorylation of translation initiation factors and tissue amino acid concentrations. Plasma glucose, insulin, and amino acid concentrations were also measured. Results - Horses in the postprandial state had significantly higher plasma insulin, glucose, and amino acid concentrations than did those in the postabsorptive state at the time of biopsy. Refeeding significantly increased the phosphorylation state of riboprotein S6 and eukaryotic initiation factor 4E binding protein 1. Conclusions and Clinical Relevance - In mature horses, feeding resulted in increased mammalian target of rapamycin signaling and the mechanism appeared to be independent of an increase in Akt phosphorylation at Ser473. Results indicate that adult horses may be able to increase rates of muscle protein synthesis in response to feeding and that dietary amino acids appear to be the main mediators of this effect.

Original languageEnglish
Pages (from-to)248-255
Number of pages8
JournalAmerican Journal of Veterinary Research
Volume72
Issue number2
DOIs
StatePublished - Feb 2011

ASJC Scopus subject areas

  • General Veterinary

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