Although insulin per se has been shown to stimulate wholebody
protein synthesis in several mammalian species (Davis et al.
2002; O’Connor et al. 2003), insulin sensitivity may also have a
significant role. Recent studies in neonatal piglets (Bergeron et al.
2007) and steers (Gingras et al. 2007) have shown that protein
anabolism is upregulated via enhanced insulin sensitivity in
animals fed dietary long-chain n-3 polyunsaturated fatty acids.
In both studies, the increase in whole-body protein accretion was
suggested to be the result of a decrease in protein breakdown, with
no alteration in its synthesis. In addition, studies in rodents have
shown an amino acid-enhanced sensitivity of skeletal muscle
protein synthesis to insulin, allowing for maximal rates of protein
synthesis to be achieved at lower insulin concentrations when
amino acids are infused concurrently (Garlick and Grant 1988).
Taken together, these above studies suggest a dynamic role for
insulin, insulin sensitivity and amino acids and collectively they
may act synergistically to stimulate protein synthesis.
Although insulin per se has been shown to stimulate wholebodyprotein synthesis in several mammalian species (Davis et al.2002; O’Connor et al. 2003), insulin sensitivity may also have asignificant role. Recent studies in neonatal piglets (Bergeron et al.2007) and steers (Gingras et al. 2007) have shown that proteinanabolism is upregulated via enhanced insulin sensitivity inanimals fed dietary long-chain n-3 polyunsaturated fatty acids.In both studies, the increase in whole-body protein accretion wassuggested to be the result of a decrease in protein breakdown, withno alteration in its synthesis. In addition, studies in rodents haveshown an amino acid-enhanced sensitivity of skeletal muscleprotein synthesis to insulin, allowing for maximal rates of proteinsynthesis to be achieved at lower insulin concentrations whenamino acids are infused concurrently (Garlick and Grant 1988).Taken together, these above studies suggest a dynamic role forinsulin, insulin sensitivity and amino acids and collectively theymay act synergistically to stimulate protein synthesis.
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