Body reserve dynamics and energetics of barn owls during fasting in the cold

Thouzeau, Cécile; Robin, Jean-Paul; Maho, Yvon Le; Handrich, Yves

doi:10.1007/s003600050262

Cited by 21 publications

(16 citation statements)

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“…Skeletal muscles are also the main tissue involved in thermogenesis in birds (Duchamp and Barré, 1993;Bicudo et al, 2002). It emerges from the literature on birds fasting in the cold that such metabolic trade-offs between the need for protein breakdown to maintain plasma amino acid homeostasis and the need for protein conservation to maintain thermogenesis and locomotor activity would be resolved by different groups of skeletal muscles dedicated to different metabolic tasks Duchamp et al, 1991;Thouzeau et al, 1999). In agreement with this is the finding during the present study that pectoralis muscles were preferentially degraded during the fast.…”

Section: Discussionsupporting

confidence: 88%

“…found in cold-acclimated ducklings was 2-4 times higher than in adult birds fasting in the cold (Thouzeau et al, 1999;Mata et al, 2001;Bourgeon et al, 2010), and 10-11 times higher than the specific daily body mass loss of emperor penguins and winteracclimatized king penguin chicks, two avian species that tolerate a very long fast during winter (Cherel and Le Maho, 1985;Robin et al, 1988). These data suggest that cold-acclimated ducklings were less efficient in sparing their protein reserves during phase II.…”

Section: Discussionmentioning

confidence: 75%

“…These data suggest that cold-acclimated ducklings were less efficient in sparing their protein reserves during phase II. The initial adiposity and the energy cost imposed by cold exposure are among the main factors that may explain the limited fasting endurance of ducklings compared with winter-acclimatized king penguin chicks and other birds (Goodman et al, 1981;Cherel et al, 1992;Lindgård et al, 1992;Boismenu et al, 1992;Thouzeau et al, 1999). In accordance with this, it can be estimated from previously published data (Bénistant et al, 1998) that cold-acclimated ducklings had a very low adiposity, 2% of the initial body mass, compared with the pre-winter adiposity of 34% found in king penguin chicks (Cherel et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

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Skeletal muscle heterogeneity in fasting-induced mitochondrial oxidative phosphorylation flexibility in cold-acclimated ducklings

Monternier

Fongy

Hervant

et al. 2015

Journal of Experimental Biology

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Starvation is particularly challenging for endotherms that remain active in cold environments or during winter. The aim of this study was to determine whether fasting-induced mitochondrial coupling flexibility depends upon the phenotype of skeletal muscles. The rates of oxidative phosphorylation and mitochondrial efficiency were measured in pectoralis (glycolytic) and gastrocnemius (oxidative) muscles from cold-acclimated ducklings (Cairina moschata). Pyruvate and palmitoyl-L-carnitine were used in the presence of malate as respiratory substrates. Plasma metabolites, skeletal muscle concentrations of triglycerides, glycogen and total protein and mitochondrial levels of oxidative phosphorylation complexes were also quantified. Results from ad libitum fed ducklings were compared with those from ducklings that were fasted for 4 days. During the 4 days of nutritional treatment, birds remained in the cold, at 4°C. The 4 days of starvation preferentially affected the pectoralis muscles, inducing an up-regulation of mitochondrial efficiency, which was associated with a reduction of both total muscle and mitochondrial oxidative phosphorylation protein, and with an increase of intramuscular lipid concentration. By contrast, fasting decreased the activity of oxidative phosphorylation but did not alter the coupling efficiency and protein expression of mitochondria isolated from the gastrocnemius muscles. Hence, the adjustment of mitochondrial efficiency to fasting depends upon the muscle phenotype of cold-acclimated birds. Furthermore, these results suggest that the reduced cost of mitochondrial ATP production in pectoralis muscles may trigger lipid storage within this tissue and help to sustain an important metabolic homeostatic function of skeletal muscles, which is to maintain levels of amino acids in the circulation during the fast.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

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Skeletal muscle heterogeneity in fasting-induced mitochondrial oxidative phosphorylation flexibility in cold-acclimated ducklings

Monternier

Fongy

Hervant

et al. 2015

Journal of Experimental Biology

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“…16. However, in the case of cold-stressed birds, the results are contradictory, as Klaassen and Biebach (29) reported a similar increase in lipid and protein catabolism, whereas Thouzeau et al (47) concluded that there was an increase in lipid catabolism without significant change in protein catabolism. Complementary data are therefore required to specify this effect.…”

Section: Kinetics Of Lipid and Protein Depletionmentioning

confidence: 98%

“…The mass of minerals, generally measured by the mass of ashes after complete combustion, represents ϳ4% of body mass in fed individuals. Previous studies have shown that the mass of minerals varies only slightly during fasting (6,9,47). On the basis of these results, it will be assumed that the mass of minerals is constant during a fast and that it can be estimated by R ϭ r i M i , where M i is the initial body mass and r i is the proportion of minerals in initial body mass.…”

Section: Lipid and Protein Masses As A Function Of Adipositymentioning

confidence: 99%

Modeling of lipid and protein depletion during total starvation

Caloin¹

2004

American Journal of Physiology-Endocrinology and Metabolism

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Caloin, Michel. Modeling of lipid and protein depletion during total starvation. Am J Physiol Endocrinol Metab 287: E790 -E798, 2004. First published May 27, 2004 10.1152/ajpendo.00414.2003This study presents a model describing lipid and protein depletion of an individual facing total starvation. The model distinguishes two compartments of body mass: a metabolic compartment and a structural compartment. It is considered that the lipids and the proteins of the metabolic compartment ensure the totality of physiological functions. The main assumptions of the model lie in the definitions of lipid mass and protein mass of the metabolic compartment, which are related to total lipid mass and total body mass, respectively. Under these assumptions, for a given individual, the ratio of lipid and protein utilization rates is proportional to the adiposity. The model accounts for the protein sparing observed at high adiposity levels and enables us to discuss the individual's survival in relation to the levels of lipid and protein depletion. The time course of changes in lipid and protein depletion rates can be calculated by introducing the energy expenditure of the individual. In simulations, it was assumed that specific energy expenditure was constant during starvation and that mortality occurred at a critical level of protein depletion. The most characteristic results derived from these simulations concern the kinetics of protein depletion, which depend markedly on initial adiposity. Accordingly, in obese subjects, the rate of protein losses remains fairly constant during fasting, whereas it increases from the onset of the fast in lean subjects, in agreement with experimental observations. In the model, protein and lipid depletion rates are both proportional to energy expenditure, which needs to be confirmed from complementary data. body composition; protein sparing; energy expenditure DURING TOTAL STARVATION, the energy required to maintain physiological functions is derived from the oxidation of body lipids and proteins, because glycogen stores are exhausted at the onset of fasting (3). Lipids, however, represent the main energy source. They have a high energy density and can be almost entirely depleted to cover maintenance requirements (45,49). By contrast, proteins, which have a much lower energy density, can be only partly depleted due to their vital enzymatic, mechanical, and structural roles. Accordingly, their contribution to energy demand is rather modest (17,28,33,37). The result is that, conversely to lipid catabolism, protein catabolism is not clearly related to energy production and remains essentially unexplained (27). It could be attributed to gluconeogenesis, which converts proteins into glucose to meet the glucose requirements of the brain after the exhaustion of glycogen stores (2, 4). However, this hypothesis is unlikely, given the large variability in the rate of protein depletion among individuals (14,16,36). To better understand the physiological basis for protein catabolism and its consequences for ...

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Tissue-Specific Mass Changes During Fasting: The Protein Turnover Hypothesis

Bauchinger

McWilliams

2012

Comparative Physiology of Fasting, Starvation, and Food Limitation

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Body reserve dynamics and energetics of barn owls during fasting in the cold

Cited by 21 publications

References 0 publications

Skeletal muscle heterogeneity in fasting-induced mitochondrial oxidative phosphorylation flexibility in cold-acclimated ducklings

Skeletal muscle heterogeneity in fasting-induced mitochondrial oxidative phosphorylation flexibility in cold-acclimated ducklings

Modeling of lipid and protein depletion during total starvation

Tissue-Specific Mass Changes During Fasting: The Protein Turnover Hypothesis

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