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Semi‐starvation alters myofibrillar mRNA concentrations to expedite rapid recovery of muscle protein stores following feeding
Author(s) -
Elisabeth Svanberg,
Arpna Kiri,
Jörgen Isgaard,
Geoffrey Goldspink
Publication year - 2000
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1046/j.1365-2362.2000.00701.x
Subject(s) - messenger rna , myosin , starvation , medicine , protein biosynthesis , skeletal muscle , endocrinology , rna , biology , postprandial , myofibril , gene expression , chemistry , biochemistry , gene , insulin
Background Protein synthesis in skeletal muscle is reduced following starvation and restored by feeding. The mediators and mechanisms are incompletely understood. The aim of this study was to evaluate whether prolongation of undernutrition induced changes in muscle gene expression at the level of mRNA and protein. Materials and methods The changes in myosin heavy‐chain 2X mRNA in adult partially starved (50% of ad libitum standard rodent chow intake for 4 or 7 days) C57BL mice or subsequently refed mice were studied. Ad libitum ‐fed mice were used as controls. Protein synthesis, total RNA and myosin heavy‐chain 2X mRNA concentrations were determined. Plasma concentrations of amino acids were measured by high‐performance liquid chromatography. Results Partial starvation of 4 and 7 days reduced body weight by 15.6 ± 1% and 17.1 ± 2.1% ( P ≤ 0.05) vs. ad libitum fed controls. Protein synthesis was reduced by 32 ± 9% and protein content by 20 ± 4% ( P ≤ 0.05) following 7 days of partial starvation. Plasma amino acid concentrations were increased (6297 ± 853) in refed animals vs. ad libitum ‐fed controls (3057 ± 141, P ≤ 0.05). Total RNA concentration (μg RNA μg −1 DNA) in skeletal muscle was unchanged. Myosin heavy‐chain 2X mRNA concentration did not change following 4 days of partial starvation but increased by 24 ± 5% ( P ≤ 0.05) following 7 days of partial starvation, hence suggesting that expression of myosin mRNA was nutritionally altered. Conclusion Postprandial stimulation of protein synthesis following starvation may thus be a combination of increased mRNA availability and increased translation. This effect may be activated by peak concentrations of amino acids in plasma following feeding.