Leucine-isoleucine antagonism in the rat

Harper, A. E.; Benton, D. A.; Winje, M.E.; Elvehjem, C. A.

doi:10.1016/0003-9861(54)90509-3

Cited by 56 publications

(19 citation statements)

References 3 publications

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“…4). The fraction of isoleucine flux used for oxidation was similar during the saline and the amino acid infusion periods with median values of 30% (range 28-42) and 24% (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34), respectively (p > 0.05). Consequently, the nonoxidative portion of isoleucine flux, representing protein synthesis decreased similarly between the two periods, from a median of 206 nmol/kg bw/min (range 119-425) during the saline infusion to a median of 80 nmol/kg bw/min (range 56-120, p < 0.05) during the amino acid infusion, respectively.…”

Section: Resultsmentioning

confidence: 92%

Protein synthesis is severely diminished following a simulated upper GI bleed in patients with cirrhosis

Damink

Jalan

Deutz

et al. 2008

Journal of Hepatology

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Section: Resultsmentioning

confidence: 92%

Protein synthesis is severely diminished following a simulated upper GI bleed in patients with cirrhosis

Damink

Jalan

Deutz

et al. 2008

Journal of Hepatology

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“…The early work of Harper and colleagues (33,34) demonstrated adverse effects on growing animals of a low-protein diet containing an inordinately large amount of a single amino acid. These adverse effects included decreased food intake when norleucine or leucine was added directly to the chow.…”

Section: Resultsmentioning

confidence: 99%

Tissue-specific effects of chronic dietary leucine and norleucine supplementation on protein synthesis in rats

Lynch

Hutson

Patson

et al. 2002

American Journal of Physiology-Endocrinology and Metabolism

118

102

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Acute administration of leucine and norleucine activates the mammalian target of rapamycin (mTOR) cell-signaling pathway and increases rates of protein synthesis in a number of tissues in fasted rats. Although persistent stimulation of mTOR signaling is thought to increase protein synthetic capacity, little information is available concerning the effects of chronic administration of these agonists on protein synthesis, mTOR signal transduction, or leucine metabolism. Hence, we developed a model of chronic leucine/norleucine supplementation via drinking water and examined the effects of chronic (12 days) supplementation on protein synthesis in adipose tissue, kidney, heart, liver, and skeletal muscle from ad libitum-fed rats. The relative concentration of proteins involved in mTOR signaling and the two initial steps in leucine oxidation were also examined. Leucine or norleucine supplementation was accompanied by increased rates of protein synthesis in adipose tissue, liver, and skeletal muscle, but not in heart or kidney. Supplementation was not associated with increases in the anabolic hormones insulin or insulin-like growth factor I. Chronic supplementation did not cause apparent adaptation in either components of the mTOR cell-signaling pathway that respond to leucine (mTOR, ribosomal protein S6 kinase, and eukaryotic initiation factor 4E-binding protein-1) or the first two steps in leucine metabolism (the mitochondrial isoform of branched-chain amino acid transaminase, branched-chain keto acid dehydrogenase, and branched-chain keto acid dehydrogenase kinase), which may be involved in terminating the signal from leucine. These results suggest that provision of leucine or norleucine supplementation via the drinking water results in stimulation of postprandial protein synthesis in adipose tissue, skeletal muscle, and liver without notable adaptive changes in signaling proteins or metabolic enzymes.

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“…Harper et al [5] showed already in 1954 that feeding with a low-protein diet with excess of leucin prevents growth in rats. This was not the case when leucine was added to a diet less restricted in protein or when the low-protein diet was added isoleucine and valine, which suggested that leucine interfere with growth through mechanisms causing a defective utilization of BCAA.…”

Section: See Article Pages 726-731mentioning

confidence: 99%

Branched-chain amino acids antagonism in patients with cirrhosis and a simulated upper GI bleed

Larsen

2008

Journal of Hepatology

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The interorgan nitrogen exchange and the metabolism of amino acids are profoundly altered in patients with liver disease, which results in an imbalanced amino acid composition of the blood characterized by low levels of glutamate, branched-chain amino acids (BCAA), e.g., valine, isoleucine and leucine, while the concentrations of most other amino acids are elevated. This disturbance in protein and amino acid metabolism decreases both the clearance of toxic metabolites and the protein synthesis, which often results in a negative nitrogen balance. The prevalence of protein-energy malnutrition in patients with cirrhosis is high-reaching as much as 60-90%

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Leucine-isoleucine antagonism in the rat

Cited by 56 publications

References 3 publications

Protein synthesis is severely diminished following a simulated upper GI bleed in patients with cirrhosis

Protein synthesis is severely diminished following a simulated upper GI bleed in patients with cirrhosis

Tissue-specific effects of chronic dietary leucine and norleucine supplementation on protein synthesis in rats

Branched-chain amino acids antagonism in patients with cirrhosis and a simulated upper GI bleed

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