Effect of insulin on human skeletal muscle protein synthesis is modulated by insulin-induced changes in muscle blood flow and amino acid availability

Fujita, Satoshi; Rasmussen, Blake B.; Cadenas, Jerson G.; Grady, James J.; Volpi, Elena

doi:10.1152/ajpendo.00271.2005

Cited by 211 publications

(179 citation statements)

References 58 publications

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“…Therefore, the proanabolic capabilities of insulin are predominantly driven by its ability to attenuate skeletal MPB, rather than any positive effect on MPS. This finding is in agreement with assessments from other researchers [16,29].…”

Section: Discussionsupporting

confidence: 94%

“…Meta-analysis of study characteristics A total of 13 articles [16,[19][20][21][24][25][26][27][28][29][30][31][32], containing 25 experimental studies using different insulin concentrations, were identified for inclusion in the meta-analysis (Table 1); all analysed the effect of insulin on both MPS and MPB (Table 1). A total of 173 individuals were included in these studies.…”

Section: Resultsmentioning

confidence: 99%

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Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis

et al. 2015

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Aims/hypothesis We aimed to investigate the role of insulin in regulating human skeletal muscle metabolism in health and diabetes. Methods We conducted a systematic review and metaanalysis of published data that examined changes in skeletal muscle protein synthesis (MPS) and/or muscle protein breakdown (MPB) in response to insulin infusion. Random-effects models were used to calculate weighted mean differences (WMDs), 95% CIs and corresponding p values. Both MPS and MPB are reported in units of nmol (100 ml leg vol.)Results A total of 104 articles were examined in detail. Of these, 44 and 25 studies (including a total of 173 individuals) were included in the systematic review and meta-analysis, respectively. In the overall estimate, insulin did not affect MPS 8.55], p=0.71), but significantly reduced MPB .18], p<0.001). Overall, insulin significantly increased net balance protein acquisition (WMD 20.09 [95% CI 15.93,24.26], p<0.001). Subgroup analysis of the effect of insulin on MPS according to amino acid (AA) delivery was performed using meta-regression analysis. The estimate size (WMD) was significantly different between subgroups based on AA availability (p=0.001). An increase in MPS was observed when AA availability increased (WMD 13.44 [95% CI 4.07,22.81], p<0.01), but not when AA availability was reduced or unchanged. In individuals with diabetes and in the presence of maintained delivery of AA, there was a significant reduction in MPS in response to insulin (WMD −6.67 [95% CI −12.29, −0.66], p<0.05). Conclusions/interpretation This study demonstrates the complex role of insulin in regulating skeletal muscle metabolism. Insulin appears to have a permissive role in MPS in the presence of elevated AAs, and plays a clear role in reducing MPB independent of AA availability.

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Section: Discussionsupporting

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis

et al. 2015

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“…These data suggest that vasodilation and nutrient flow to the muscle are important regulators of the muscle anabolic response during hyperinsulinemia [29] and during feeding [13]. This hypothesis is further supported by recent data obtained in young individuals where various levels of physiological hyperinsulinemia were induced in the absence of amino acid replacement [31]. In this experiment, the muscle protein anabolic response was mainly related to insulin-induced changes in blood flow and amino acid delivery to the muscle, rather than the absolute insulin level.…”

Section: Nutrient Intake On Amino Acid Metabolism In Agingsupporting

confidence: 79%

Amino acid metabolism and regulatory effects in aging

Timmerman

Volpi²

2008

Current Opinion in Clinical Nutrition and Metabolic Care

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Purpose of review-To examine recent discoveries related to the amino acid metabolism and regulatory effects in aging, focusing on the development and treatment of age-related muscle loss (sarcopenia).Recent findings-While basal amino acid metabolism may be unaffected by age, elderly subjects appear to have a decreased ability to respond to anabolic stimuli such as insulin and, to a lesser extent, amino acids. Specifically, compared to young subjects, the stimulation of muscle protein synthesis is attenuated in elderly subjects following the administration of mixed meals due to insulin resistance. In addition, the anabolic effect of amino acids appears blunted at low doses. Recent studies, however, have highlighted that these age-related alterations in amino acid metabolism may be overcome by provision of excess leucine, changes in the daily protein intake pattern or exercise, which improve activation of translation initiation and muscle protein synthesis.Summary-Muscle loss with aging is associated with significant changes in amino acid metabolism, which can be acutely reversed using nutritional manipulations and exercise. Longterm, large clinical trials are, however, needed to determine the clinical significance of these findings in the elderly population, and to establish if nutritional and exercise interventions can help prevent and treat sarcopenia.

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“…4). This result is consistent with previous conclusions that in muscle the effect of INS on protein metabolism depends on AA availability (12)(13)(14)(15)(16)(17)(18). Protein synthesis requires sufficient AA supply.…”

Section: Discussionsupporting

confidence: 93%

Amino Acid Availability Regulates the Effect of Hyperinsulinemia on Skin Protein Metabolism in Pigs

Tuvdendorj¹,

Børsheim²,

Sharp

et al. 2015

Journal of Biological Chemistry

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Background: Insulin is known as an anabolic agent; however, its effect on skin protein metabolism is not well understood. Results: Hyperaminoacidemia alters the effect of hyperinsulinemia on skin protein metabolism in pigs. Conclusion: Hyperinsulinemia itself was not anabolic but rather affected skin amino acid cycling. Significance: Knowing the effect of hyperinsulinemia on skin protein metabolism will help with understanding the pathophysiology of skin conditions.

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Effect of insulin on human skeletal muscle protein synthesis is modulated by insulin-induced changes in muscle blood flow and amino acid availability

Abstract: . Effect of insulin on human skeletal muscle protein synthesis is modulated by insulin-induced changes in muscle blood flow and amino acid availability.

Cited by 211 publications

References 58 publications

Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis

Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis

Amino acid metabolism and regulatory effects in aging

Amino Acid Availability Regulates the Effect of Hyperinsulinemia on Skin Protein Metabolism in Pigs

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