Insulin resistance in aged man: Relationship between impaired glucose tolerance and decreased insulin activity on branched-chain amino acids

Marchesini, Giulio; Cassarani, S.; Checchia, Giovanni Antonio; Bianchi, Giampaolo; Bua, Vincenzo; Zoli, Marco; Pisi, E

doi:10.1016/0026-0495(87)90032-1

Cited by 16 publications

(11 citation statements)

References 24 publications

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“…Significant differences were described between the plasma concentration of several amino acids in young adult males and females (13). Similarly, data from small numbers of elderly individuals suggest that the age-related decline in insulin responsiveness may cause an elevation in the plasma branched-chain amino acid concentration via a mechanism similar to that observed in obese subjects (14)(15)(16)(17).…”

Section: Introductionmentioning

confidence: 78%

Plasma amino acid concentrations in healthy elderly men and women

Caballero

Gleason

Wurtman

1991

The American Journal of Clinical Nutrition

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Postabsorptive plasma concentrations of the large neutral amino acids (LNAAs) were measured in 74 elderly (age 71 +/- 8 y) and 138 young (age 26 +/- 5 y) healthy subjects. Plasma concentrations of valine, leucine, and isoleucine were significantly lower in young females than in young males. This gender-related difference was not observed among elderly subjects because aging was associated with a significant rise in plasma LNAAs in females but not in males. Multiple-regression analysis of plasma amino acid concentrations from female subjects revealed a significant and positive effect of age on plasma valine, leucine, isoleucine, phenylalanine, and tyrosine but not on plasma tryptophan or methionine. Tryptophan was the only amino acid to exhibit a significant response to age in males, consisting of a 14% decline in the elderly subjects. Percentile ranges are presented for young and elderly females and males for each of the amino acids.

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Section: Introductionmentioning

confidence: 78%

Plasma amino acid concentrations in healthy elderly men and women

Caballero

Gleason

Wurtman

1991

The American Journal of Clinical Nutrition

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“…Second, there was a dramatic fall in plasma amino acid concentrations at every insulin levels that was not prevented by amino acid replacement. The question of insulin resistance for protein metabolism has been indirectly raised by analyzing the changes in amino acid concentrations during an oral load of glucose (35). Third, we wanted to check for the first time whether gender may have affected the response to insulin.…”

Section: Discussionmentioning

confidence: 99%

“…As baseline amino acid maintenance is critical for the interpretation of the results in protein metabolism studies (10,31), this may partly explain some of the differences we found. By measuring amino acid concentrations during OGTT, Marchesini et al have shown that this decline was of lesser magnitude in elderly subjects, suggesting less inhibition of protein breakdown (35). Recent data indicate that gender differences in leucine metabolism may be present at baseline in a young population (17).…”

Section: Discussionmentioning

confidence: 99%

Differential Insulin Sensitivities of Glucose, Amino Acid, and Albumin Metabolism in Elderly Men and Women

Boirie‌

Gachon

Cordat

et al. 2001

The Journal of Clinical Endocrinology & Metabolism

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Regulation of glucose homeostasis by insulin is modified during aging, but whether this alteration is associated with changes in protein metabolism is less defined. Insulin dose responses of whole body glucose, leucine, and albumin metabolism have been investigated using isotopic dilution of D-[6, 6-(2)H(2)]glucose and L-[1-(13)C]leucine in 14 young (Y; 24.0 +/- 0.9 yr; mean +/- SEM, 20.5 +/- 0.4 kg/m(2)) and 12 healthy elderly subjects (E; 69.4 +/- 0.6 yr; 24.6 +/- 0.8 kg/m(2)) using a euglycemic and euaminoacidemic hyperinsulinemic clamp at two insulin infusion rates of 0.2 and 0.5 mU/kg.min (CL1 and CL2, respectively). Despite significantly higher plasma insulin in E than in Y, the glucose disposal rate was lower in E than in Y at both insulin levels, whereas glucose production was normally suppressed. Whole body protein breakdown was less inhibited by insulin in E than in Y at CL1 (-13.5 +/- 1.4% vs. -8.8 +/- 1.3%, Y vs. E, P < 0.05), but not significantly at CL2 (-22.0 +/- 1.4% vs. -18.8 +/- 1.7%, Y vs. E, P = NS). The albumin synthesis rate was identical and stimulated to the same extent by insulin in groups Y and E. Gender affected basal leucine metabolism, but the response to insulin was similar in both groups. In conclusion, decreased insulin action on glucose disposal is associated with a reduced insulin sensitivity for protein breakdown in healthy elderly subjects at low insulin concentrations. Higher insulin levels compensate for a reduced insulin action on protein metabolism in elderly subjects.

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“…Likely, impaired insulin sensitivity would prevent increases in protein synthesis by inhibiting or blunting activation of PKB/Akt-P and mTOR (Reviewed in Figure 1). Insulin insensitivity is also linked to insufficient utilization of BCAAs (Marchesini et al, 1987), of which leucine would be a primary concern.…”

Section: Discussionmentioning

confidence: 99%

“…This is especially significant when considering the BCAAs are important to muscle synthesis. If postprandial plasma levels of BCAAs are not decreasing as much, one can assume that they are not being used for protein metabolism as much (Marchesini et al, 1987). In summary, age related insulin changes significantly influence muscle and protein metabolism.…”

Section: Insulin Insensitivity In Agingmentioning

confidence: 99%

The Effects of Aging on Muscle Loss and Nuclear Factor Kappa-B Levels in Rats Fed a Diet Containing Suboptimal Leucine Levels

Kohlen¹

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Insulin resistance in aged man: Relationship between impaired glucose tolerance and decreased insulin activity on branched-chain amino acids

Cited by 16 publications

References 24 publications

Plasma amino acid concentrations in healthy elderly men and women

Plasma amino acid concentrations in healthy elderly men and women

Differential Insulin Sensitivities of Glucose, Amino Acid, and Albumin Metabolism in Elderly Men and Women

The Effects of Aging on Muscle Loss and Nuclear Factor Kappa-B Levels in Rats Fed a Diet Containing Suboptimal Leucine Levels

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