Lower recovery of muscle protein lost during starvation  in old rats despite a stimulation of protein synthesis

Mosoni, Laurent; Malmezat, T.; Valluy, Marie-Claude; Houlier, Marie-Louise; Attaix, Didier; Mirand, Philippe Patureau

doi:10.1152/ajpendo.1999.277.4.e608

Cited by 36 publications

(27 citation statements)

References 31 publications

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“…We have shown that standard nutrition led to increased protein mass and synthesis only in the liver and had no effect on the muscle. The lack of stimulation of muscle protein synthesis is in agreement with the only study, to our knowledge, performed on old, 10-day-starved rats in which refeeding with a standard diet showed no effect on the muscle protein synthesis rate (25).…”

Section: Discussionsupporting

confidence: 90%

Citrulline modulates muscle protein metabolism in old malnourished rats

Osowska

Duchemann²,

Walrand³

et al. 2006

American Journal of Physiology-Endocrinology and Metabolism

133

114

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Protein energy malnutrition is common in the elderly, especially in hospitalized patients. The development of strategies designed to correct such malnutrition is essential. Our working hypothesis was that poor response to nutrition with advancing age might be related to splanchnic sequestration of amino acids, which implies that fewer amino acids reach the systemic circulation. Administration of citrulline, which is not taken up by the liver, can offer a means of increasing whole body nitrogen availability and, hence, improve nutritional status. Thirty old (19 mo) rats were submitted to dietary restriction (50% of food intake) for 12 wk. They were randomized into three groups: 10 rats (R group) were killed and 20 others refed (90% of food intake) for 1 wk with a standard diet (NEAA group) or a citrulline-supplemented diet (Cit group). Before being killed, the rats were injected with [(13)C]valine, and the absolute protein synthesis rate (ASR) was measured in the tibialis using the flooding-dose method. When the rats were killed, the tibialis was removed for protein content analysis. Blood was sampled for amino acid and insulin analysis. The standard diet did not have any effect on protein synthesis or on the protein content in the muscle. Citrulline supplementation led to higher protein synthesis and protein content in muscle (117 +/- 9, 120 +/- 14, and 163 +/- 4 mg/organ for protein content in R, NEAA, and Cit groups, P < 0.05). The ASR were 0.30 +/- 0.04, 0.31 +/- 0.04, and 0.56 +/- 0.10 mg/h in the three groups, respectively (R and NEAA vs. Cit, P < 0.05). Insulinemia was significantly higher in the Cit group. For the first time, a realistic therapeutic approach is proposed to improve muscle protein content in muscle in frail state related to malnutrition in aging.

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Section: Discussionsupporting

confidence: 90%

Citrulline modulates muscle protein metabolism in old malnourished rats

Osowska

Duchemann²,

Walrand³

et al. 2006

American Journal of Physiology-Endocrinology and Metabolism

133

114

View full text Add to dashboard Cite

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“…We observed a two-to threefold increase in both atrogin-1 and MuRF1 mRNA in aged rats, which was associated with a concomitant stimulation of in vitro-determined proteasome activity. These data are consistent with the elevated rate of proteolysis observed in aged humans (87) and elevated rate of 3-methylhistidine excretion in rats (63). Although these data suggest sarcopenia may be due solely to an increase in proteolysis, as opposed to a decrease in protein synthesis, the assessment of protein metabolism was conducted in the postabsorptive state (ϳ3-5 h after removal of food), and aging has been shown to attenuate the anabolic response of muscle protein synthesis to nutrient stimulation (2,6).…”

Section: R892 Aging Alcohol and Muscle Protein Balancesupporting

confidence: 90%

Aging accentuates alcohol-induced decrease in protein synthesis in gastrocnemius

Korzick

Sharda

Pruznak

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

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The present study sought to determine whether the protein catabolic response in skeletal muscle produced by chronic alcohol feeding was exaggerated in aged rats. Adult (3 mo) and aged (18 mo) female F344 rats were fed a nutritionally complete liquid diet containing alcohol (36% of total calories) or an isocaloric isonitrogenous control diet for 20 wk. Muscle (gastrocnemius) protein synthesis, as well as mTOR and proteasome activity did not differ between control-fed adult and aged rats, despite the increased TNF-α and IL-6 mRNA and decreased IGF-I mRNA in muscle of aged rats. Compared with alcohol-fed adult rats, aged rats demonstrated an exaggerated alcohol-induced reduction in lean body mass and protein synthesis (both sarcoplasmic and myofibrillar) in gastrocnemius. Alcohol-fed aged rats had enhanced dephosphorylation of 4E-BP1, as well as enhanced binding of raptor with both mTOR and Deptor, and a decreased binding of raptor with 4E-BP1. Alcohol feeding of both adult and aged rats reduced RagA binding to raptor. The LKB1-AMPK-REDD1 pathway was upregulated in gastrocnemius from alcohol-fed aged rats. These exaggerated alcohol-induced effects in aged rats were associated with a greater decrease in muscle but not circulating IGF-I, but no further increase in inflammatory mediators. In contrast, alcohol did not exaggerate the age-induced increase in atrogin-1 and MuRF1 mRNA or the increased proteasome activity. Our results demonstrate that, compared with adult rats, the gastrocnemius from aged rats is more sensitive to the catabolic effects of alcohol on protein synthesis, but not protein degradation, and this exaggerated response may be AMPK-dependent.

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“…Evidently, myofibrillar proteins are initially spared during starvation. This fits with the observation that loss of muscle protein is initially prevented and only becomes prominent after longer food deprivation, whereas the liver and other viscera lose considerable protein during the first phase of starvation [19,20]. It is probably related to different phases of protein breakdown after various levels of metabolic stress.…”

Section: Mpb Versus Tpbsupporting

confidence: 86%

Measuring whole-body actin/myosin protein breakdown in mice using a primed constant stable isotope-infusion protocol

et al. 2003

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To measure actin/myosin protein breakdown, the 24 h excretion of N (tau)-methylhistidine (3MH) is used. However, in mice, this method is invalid. Therefore we have developed a liquid chromatography-MS technique to measure the tracer/tracee ratio and concentration of 3MH in plasma, enabling an in vivo primed constant infusion protocol with a deuterated stable isotope of 3MH. We tested this model by giving a primed constant infusion of L-[3-methyl-(2)H(3)]histidine, L-[phenyl-(2)H(5)]phenylalanine and L-[phenyl-(2)H(2)]tyrosine to three anaesthetized experimental groups: mice receiving saline intraperitoneally (i.p.) (CON), mice receiving saline i.p. and starved for 9 h (STA), and mice receiving lipopolysaccharide i.p. and starved for 9 h (STA+LPS). The contribution of myofibrillar to total protein breakdown was significantly lower in the STA group than the CON group (30+/-4% and 54+/-14% respectively; P <0.05), and was significantly higher in the STA+LPS group than the STA group (52+/-7% and 30+/-4% respectively; P <0.05). Whole-body myofibrillar protein breakdown, total protein breakdown, protein synthesis and net protein breakdown were not different between the groups. We conclude that this in vivo primed constant stable isotope-infusion protocol can give valuable information about the role of actin/myosin protein breakdown in mice.

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Lower recovery of muscle protein lost during starvation in old rats despite a stimulation of protein synthesis

Cited by 36 publications

References 31 publications

Citrulline modulates muscle protein metabolism in old malnourished rats

Citrulline modulates muscle protein metabolism in old malnourished rats

Aging accentuates alcohol-induced decrease in protein synthesis in gastrocnemius

Measuring whole-body actin/myosin protein breakdown in mice using a primed constant stable isotope-infusion protocol

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