No difference in insulin sensitivity between healthy postmenopausal women with or without sarcopenia: a pilot study

Insulin plays a pivotal role in skeletal muscle protein metabolism and its action decreases with age. A loss of muscle mass, termed sarcopenia, also occurs with age. The age-associated decline in insulin sensitivity (IS) may negatively alter muscle protein metabolism and, therefore, be implicated in the aetiology of sarcopenia. However, no studies have yet compared the level of IS between older individuals with or without sarcopenia. Thus, in this study, we compared the IS of 20 class I sarcopenics (CIS), 8 class II sarcopeniscs (CIIS), and 16 non-sarcopenics (NS), among a group of otherwise healthy, non-obese, postmenopausal women. IS was estimated with the quantitative IS check index (QUICKI). Muscle mass index (MMI), which was used to determine sarcopenia, was calculated as follows: (appendicular muscle mass × 1.19) – 1.01/h2, where h = height. Fat-free mass (FFM), fat mass (FM), and trunk FM (TFM) were measured by dual-energy X-ray absorptiometry. Accelerometry and indirect calorimetry were used to estimate resting (REE), daily (DEE), and physical activity (PAEE) energy expenditure. A 3 d food record was used to determine total energy, protein (animal and vegetal), and carbohydrate intakes. As expected, MMI and FFM differed significantly among groups. However, no significant differences were found among groups for IS, FM, TFM, REE, DEE, PAEE, or total energy, protein (both animal and vegetable), and carbohydrate intakes. Using QUICKI, a surrogate measure of IS, the present results suggest that the action of insulin does not play an important role in the development and maintenance of sarcopenia in healthy, non-obese, postmenopausal women.

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Insulin sensitivity, hormonal levels and skeletal muscle protein metabolism in tumour-bearing exercising rats

European Journal of Cancer ◽

10.1016/0959-8049(94)00344-5 ◽

1995 ◽

Vol 31 (1) ◽

pp. 97-103 ◽

Cited By ~ 16

Author(s):

P. Daneryd ◽

L. Hafström ◽

E. Svanberg ◽

I. Karlberg

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Protein Metabolism ◽

Muscle Protein ◽

Skeletal Muscle Protein ◽

Tumour Bearing ◽

Muscle Protein Metabolism ◽

Hormonal Levels

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Age and aerobic exercise training effects on whole body and muscle protein metabolism

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00366.2003 ◽

2004 ◽

Vol 286 (1) ◽

pp. E92-E101 ◽

Cited By ~ 263

Author(s):

Kevin R. Short ◽

Janet L. Vittone ◽

Maureen L. Bigelow ◽

David N. Proctor ◽

K. Sreekumaran Nair

Keyword(s):

Protein Synthesis ◽

Exercise Training ◽

Protein Metabolism ◽

Protein Turnover ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Fat Free Mass ◽

Whole Body ◽

Men And Women ◽

Muscle Protein Metabolism

Aging in humans is associated with loss of lean body mass, but the causes are incompletely defined. Lean tissue mass and function depend on continuous rebuilding of proteins. We tested the hypotheses that whole body and mixed muscle protein metabolism declines with age in men and women and that aerobic exercise training would partly reverse this decline. Seventy-eight healthy, previously untrained men and women aged 19-87 yr were studied before and after 4 mo of bicycle training (up to 45 min at 80% peak heart rate, 3-4 days/wk) or control (flexibility) activity. At the whole body level, protein breakdown (measured as [13C]leucine and [15N]phenylalanine flux), Leu oxidation, and protein synthesis (nonoxidative Leu disposal) declined with age at a rate of 4-5% per decade ( P < 0.001). Fat-free mass was closely correlated with protein turnover and declined 3% per decade ( P < 0.001), but even after covariate adjustment for fat-free mass, the decline in protein turnover with age remained significant. There were no differences between men and women after adjustment for fat-free mass. Mixed muscle protein synthesis also declined with age 3.5% per decade ( P < 0.05). Exercise training improved aerobic capacity 9% overall ( P < 0.01), and mixed muscle protein synthesis increased 22% ( P < 0.05), with no effect of age on the training response for either variable. Fat-free mass, whole body protein turnover, and resting metabolic rate were unchanged by training. We conclude that rates of whole body and muscle protein metabolism decline with age in men and women, thus indicating that there is a progressive decline in the body's remodeling processes with aging. This study also demonstrates that aerobic exercise can enhance muscle protein synthesis irrespective of age.

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Muscle protein metabolism responds similarly to exogenous amino acids in healthy younger and older adults during NO-induced hyperemia

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00211.2011 ◽

2011 ◽

Vol 301 (5) ◽

pp. R1408-R1417 ◽

Cited By ~ 27

Author(s):

E. Lichar Dillon ◽

Shanon L. Casperson ◽

William J. Durham ◽

Kathleen M. Randolph ◽

Randall J. Urban ◽

...

Keyword(s):

Older Adults ◽

Skeletal Muscle ◽

Blood Flow ◽

Protein Metabolism ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Older Individuals ◽

Skeletal Muscle Protein ◽

Age Related ◽

Muscle Protein Metabolism

The combination of increasing blood flow and amino acid (AA) availability provides an anabolic stimulus to the skeletal muscle of healthy young adults by optimizing both AA delivery and utilization. However, aging is associated with a blunted response to anabolic stimuli and may involve impairments in endothelial function. We investigated whether age-related differences exist in the muscle protein anabolic response to AAs between younger (30 ± 2 yr) and older (67 ± 2 yr) adults when macrovascular and microvascular leg blood flow were similarly increased with the nitric oxide (NO) donor, sodium nitroprusside (SNP). Regardless of age, SNP+AA induced similar increases above baseline ( P ≤ 0.05) in macrovascular flow (4.3 vs. 4.4 ml·min−1·100 ml leg−1 measured using indocyanine green dye dilution), microvascular flow (1.4 vs. 0.8 video intensity/s measured using contrast-enhanced ultrasound), phenylalanine net balance (59 vs. 68 nmol·min−1·100 ml·leg−1), fractional synthetic rate (0.02 vs. 0.02%/h), and model-derived muscle protein synthesis (62 vs. 49 nmol·min−1·100 ml·leg−1) in both younger vs. older individuals, respectively. Provision of AAs during NO-induced local skeletal muscle hyperemia stimulates skeletal muscle protein metabolism in older adults to a similar extent as in younger adults. Our results suggest that the aging vasculature is responsive to exogenous NO and that there is no age-related difference per se in AA-induced anabolism under such hyperemic conditions.

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Phenotypic regulation of animal skeletal muscle protein metabolism

Ukrainian Journal of Ecology ◽

10.15421/2019_804 ◽

2019 ◽

Vol 9 (4) ◽

pp. 651-656 ◽

Cited By ~ 2

Author(s):

K. T. Erimbetov ◽

O. V. Obvintseva ◽

A. V. Fedorova ◽

R. A. Zemlyanoy ◽

A. G. Solovieva

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Signaling Pathways ◽

Muscle Mass ◽

Protein Metabolism ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Mrna Translation ◽

Mtorc1 Signaling ◽

Muscle Protein Metabolism

This review highlights the current state of phenotypic mechanisms of regulation of muscle protein metabolism in animals. Since the skeletal muscle represents 40–50% of body mass in mammals it is a critical regulator of overall metabolism. Therefore, an understanding of the processes involved in the postnatal increase in muscle mass, with associated accumulation of protein, is fundamental. Throughout life, a delicate balance exists between protein synthesis and degradation that is essential for growth and normal health of humans and animals. Signaling pathways coordinate muscle protein balance. Anabolic and catabolic stimuli are integrated through the PKB/Akt-mTORC1 signaling to regulate mechanisms that control muscle protein synthesis and breakdown. At an early periods of intensive growth, muscle mass is stimulated by an increase in protein synthesis at the level of mRNA translation. Throughout the life, proteolytic processes including autophagy lysosomal system, ubiquitin proteasome pathway, calcium-dependent calpains and cysteine protease caspase enzyme cascade influence the growth of muscle mass. Several signal transmission networks direct and coordinate these processes along with quality control mechanisms to maintain protein homeostasis (proteostasis). Genetic factors, hormones, amino acids, phytoecdysteroids, and rhodanines affect the protein metabolism via signaling pathways, changing the ability and / or efficiency of muscle growth.

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Insulin sensitivity of muscle protein metabolism is altered in patients with chronic kidney disease and metabolic acidosis

Kidney International ◽

10.1038/ki.2015.247 ◽

2015 ◽

Vol 88 (6) ◽

pp. 1419-1426 ◽

Cited By ~ 23

Author(s):

Giacomo Garibotto ◽

Antonella Sofia ◽

Rodolfo Russo ◽

Ernesto Paoletti ◽

Alice Bonanni ◽

...

Keyword(s):

Chronic Kidney Disease ◽

Metabolic Acidosis ◽

Insulin Sensitivity ◽

Kidney Disease ◽

Protein Metabolism ◽

Muscle Protein ◽

Muscle Protein Metabolism

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Long-Term Habitual Exercise and Combination of β-hydroxy-β-methylbutyrate Plus Black Ginger Maintain Muscle Health in SAMP8 Mice

10.20944/preprints202008.0118.v1 ◽

2020 ◽

Author(s):

Kai Aoki ◽

Masaki Konno ◽

Katsuyuki Tokinoya ◽

Katsunari Honda ◽

Takuya Abe ◽

...

Keyword(s):

Oxidative Stress ◽

Muscle Mass ◽

Mitochondrial Function ◽

Protein Metabolism ◽

Muscle Protein ◽

Muscle Aging ◽

Habitual Exercise ◽

Muscle Protein Metabolism ◽

Muscle Health ◽

Samp8 Mice

Muscle mass and strength decrease with aging, but habitual exercise can maintain muscle health. β-Hydroxy-β-methyl butyrate calcium (HMB) and black ginger (BG) are anti-oxidants that have been reported to improve muscle protein metabolism and energy production; these molecules may have synergistic effects. The senescence-accelerated mouse-prone 8 (SAMP8) model is a useful model of muscle aging. Therefore, in this study, we explored how the combination of habitual exercise, HMB, and BG affected muscle aging. We used 28-week-old SAMP8 mice divided into five groups: control, exercise (Ex), Ex+BG, Ex+HMB, and Ex+BG+HMB (Ex+Comb). Mice were required to run on a treadmill for 16 weeks at 5 days per week. In 44-week-old mice, grip strength tests and dissection were conducted. Muscle weight was measured, and the gastrocnemius muscle was subjected to quantitative polymerase chain reaction and immunoblotting. Muscle mass and strength were preserved in the Ex+Comb group, and mitochondrial function was preserved through suppressing oxidative stress. Muscle protein synthesis signaling was improved in the Ex+Comb group. Autophagy and the ubiquitin system were normalized by Ex+Comb treatment. Overall, habitual exercise and HMB plus BG treatment maintained muscle health by suppressing oxidative stress, preserving mitochondrial function, and maintaining muscle protein metabolism in SAMP8 mice.

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