Protein and lipid utilization during long-term fasting in emperor penguins

1988 ◽  
Vol 254 (1) ◽  
pp. R61-R68 ◽  
Author(s):  
J. P. Robin ◽  
M. Frain ◽  
C. Sardet ◽  
R. Groscolas ◽  
Y. Le Maho
Keyword(s):  
Uric Acid ◽  
Mass Loss ◽  
Body Mass ◽  
Phase Ii ◽  
Plasma Concentrations ◽  
The Body ◽  
Phase Iii ◽  
Body Mass Loss ◽  
Emperor Penguins

The body mass of male emperor penguins is approximately 38 kg at the beginning of the 4-mo winter fast connected with breeding, and it is an estimated approximately 18 kg in leanest birds at time of spontaneous refeeding. For a 38- to 18-kg range, we investigated the changes in the rate of body mass loss, body composition, and plasma concentrations of uric acid and urea. After the first few days (phase I) a steady state (phase II) was reached in the proportions of the energy derived from proteins and lipids with proteins accounting for a constant 4%, and the remaining 96% being from lipids. The same proportions were maintained until body mass had decreased to 24 kg. Below this value the proportion of energy derived from proteins increased progressively (phase III), being 14 times higher at 18 kg than during phase II. Rate of body mass loss and plasma uric acid and urea concentrations closely reflected the changes in protein utilization: being at a low and steady value throughout phase II and increasing during phase III. Emperor penguins also fast during the spring, but for periods of only 2-3 wk. We found a 2.5 times higher value for rate of body mass loss, uric acid, and urea during spring phase II, suggesting lower effectiveness in protein sparing at that time. It may be attributed to the lower initial lipid reserves of spring birds. Would these findings be generalized to the wide variety of birds and mammals that spontaneously fast under natural conditions?(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral changes in fasting emperor penguins: evidence for a “refeeding signal” linked to a metabolic shift

1998 ◽  
Vol 274 (3) ◽  
pp. R746-R753 ◽  
Author(s):  
Jean-Patrice Robin ◽  
Laurent Boucontet ◽  
Pascal Chillet ◽  
René Groscolas
Keyword(s):  
Uric Acid ◽  
Locomotor Activity ◽  
Mass Loss ◽  
Body Mass ◽  
Plasma Levels ◽  
Escape Behavior ◽  
Phase Iii ◽  
Body Mass Loss ◽  
Body Protein ◽  
Emperor Penguins

This study examines the relationships between metabolic status and behavior in spontaneously fasting birds in the context of long-term regulation of body mass and feeding. Locomotor activity, escape behavior, display songs, body mass, and metabolic and endocrine status of captive male emperor penguins were recorded during a breeding fast. We also examined whether body mass at the end of the fast affected further survival. The major part of the fast ( phase II) was characterized by the maintenance of a very low level of locomotor activity, with almost no attempt to escape, by an almost constant rate of body mass loss, and by steady plasma levels of uric acid, β-hydroxybutyrate, and corticosterone. This indicates behavioral and metabolic adjustments directed toward sparing energy and body protein. Below a body mass of ∼24 kg ( phase III), spontaneous locomotor activity and attempts to escape increased by up to 8- and 15-fold, respectively, and display songs were resumed. This probably reflected an increase in the drive to refeed. Simultaneously, daily body mass loss and plasma levels of uric acid and corticosterone increased, whereas plasma levels of β-hydroxybutyrate decreased. Some experimental birds were seen again in following years. These findings suggest that at a threshold of body mass, a metabolic and endocrine shift, possibly related to a limited availability of fat stores, acts as a “refeeding signal” that improves the survival of penguins to fasting.

Lipolytic and metabolic response to glucagon in fasting king penguins: phase II vs. phase III

2003 ◽  
Vol 284 (2) ◽  
pp. R444-R454 ◽  
Author(s):  
Servane F. Bernard ◽  
Marie-Anne Thil ◽  
René Groscolas
Keyword(s):  
Uric Acid ◽  
Plasma Concentration ◽  
Phase Ii ◽  
Metabolic Response ◽  
Plasma Concentrations ◽  
Phase Iii ◽  
Nonesterified Fatty Acids ◽  
Fourfold Increase

This study aims to determine how glucagon intervenes in the regulation of fuel metabolism, especially lipolysis, at two stages of a spontaneous long-term fast characterized by marked differences in lipid and protein availability and/or utilization (phases II and III). Changes in the plasma concentration of various metabolites and hormones, and in lipolytic fluxes as determined by continuous infusion of [2-3H]glycerol and [1-14C]palmitate, were examined in vivo in a subantarctic bird (king penguin) before, during, and after a 2-h glucagon infusion. In the two fasting phases, glucagon infusion at a rate of 0.025 μg · kg−1 · min−1induced a three- to fourfold increase in the plasma concentration and in the rate of appearance (Ra) of glycerol and nonesterified fatty acids, the percentage of primary reesterification remaining unchanged. Infusion of glucagon also resulted in a progressive elevation of the plasma concentration of glucose and β-hydroxybutyrate and in a twofold higher insulinemia. These changes were not significantly different between the two phases. The plasma concentrations of triacylglycerols and uric acid were unaffected by glucagon infusion, except for a 40% increase in plasma uric acid in phase II birds. Altogether, these results indicate that glucagon in a long-term fasting bird is highly lipolytic, hyperglycemic, ketogenic, and insulinogenic, these effects, however, being similar in phases II and III. The maintenance of the sensitivity of adipose tissue lipolysis to glucagon could suggest that the major role of the increase in basal glucagonemia observed in phase III is to stimulate gluconeogenesis rather than fatty acid delivery.

scholarly journals Activation of the central melanocortin system in rats persistently reduces body and fat mass independently of caloric reduction

2018 ◽  
Vol 96 (3) ◽  
pp. 308-312 ◽  
Author(s):  
Isabelle Côté ◽  
Sara M. Green ◽  
Drake Morgan ◽  
Christy S. Carter ◽  
Nihal Tümer ◽  
...  
Keyword(s):  
Food Intake ◽  
Mass Loss ◽  
Body Mass ◽  
Fat Mass ◽  
Control Level ◽  
Mass Ratio ◽  
Melanocortin System ◽  
Body Mass Loss ◽  
Fat Mass Ratio

Recent evidence indicate that melanotan II (MTII) reduces body mass independently of caloric reduction. Because MTII induces a transient hypophagia, caloric reduction is still considered a primary mechanism for MTII-mediated body mass loss. To examine the contribution of caloric reduction to long-term body mass loss in response to MTII, we centrally infused MTII or vehicle in ad libitum fed (MTII and Control) animals in comparison with a group of animals that were pair-fed (PF) to the MTII group. Food intake and body mass were recorded daily, and body composition was assessed biweekly. The present study demonstrates that central MTII-mediated body mass loss is only partially mediated by caloric restriction, and the long-term body mass loss is independent of the initial hypophagia. More importantly, central MTII administration induced a rapid but sustained fat mass loss, independently of caloric reduction. MTII-treated animals preserved their lean/fat mass ratio throughout the study, whereas PF animals underwent a transient reduction of lean/fat mass ratio that was only normalized when food intake returned to Control level. In summary, it can be concluded that activation of the central melanocortin system in rats persistently reduces body and fat mass independently of caloric reduction.

Five months of fasting in king penguin chicks: body mass loss and fuel metabolism

1985 ◽  
Vol 249 (4) ◽  
pp. R387-R392 ◽  
Author(s):  
Y. Cherel ◽  
Y. Le Maho
Keyword(s):  
Uric Acid ◽  
Body Mass ◽  
Plasma Concentrations ◽  
Progressive Increase ◽  
King Penguin ◽  
Body Mass Loss ◽  
Protein Utilization ◽  
Fuel Metabolism ◽  
Protein Sparing ◽  
Beta Hydroxybutyrate

When king penguin chicks are 3–4 mo old, they enter a season of interrupted growth due to long periods of fasting, because they are irregularly fed in winter. Nine captive chicks [mean initial body mass (m) = 12.5 kg] had fasted an average of 5 mo at the end of the experiment; m was then 4.0 kg, a 68% decrease. They probably could have fasted longer, since chicks of parents delayed in the return to the colony die from starvation at an m of 3.0 kg. The long fast could be divided into three periods based on the changes in rate of decrease of m. The remarkable resistance of king penguin chicks to starvation may be partly explained by their ability to maintain protein sparing for as much as 4 mo, the duration of period II; plasma concentrations of uric acid, urea, and alanine were then minimum, 0.1, 0.4, and 0.4 mmol X l–1 respectively. Particular changes during this period, i.e., progressive increase of beta-hydroxybutyrate and decrease of glucose concentrations, might contribute to the efficiency of protein sparing. Period III was marked by a rise in protein utilization, plasma concentrations of uric acid, urea, and alanine increasing to 0.7, 1.5, and 0.8 mmol X l–1, respectively.

scholarly journals Symposium on ‘Performance, exercise and health’ Hydration, fluids and performance

2008 ◽  
Vol 68 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Susan M. Shirreffs
Keyword(s):  
Mass Loss ◽  
Body Mass ◽  
Endurance Exercise ◽  
Exercise Performance ◽  
Team Sports ◽  
Endurance Performance ◽  
The Body ◽  
Dietary Recommendations ◽  
Mental Performance ◽  
Body Mass Loss

Sweat evaporation can be a key thermoregulatory mechanism and it causes a loss of water from all compartments of the body. Hypohydration can also develop with restricted fluid intake or with intake of diuretics. Hypohydration can affect physical and/or mental performance and/or have implications for dietary recommendations. A variety of different types and modes of exercise performance can be influenced by hydration state. Reviews of the published literature are currently most conclusive for endurance exercise. Dehydration equivalent to 2% body mass loss during exercise in a hot environment (31–32°C) impairs endurance performance, but when the exercise is performed in a temperate environment (20–21°C) a 2% body mass loss appears to have a lesser and inconsequential effect. In cold environments a body mass loss >2% may be tolerable for endurance exercise. There is a less conclusive picture as to the effects of hypohydration on other types of physical performance, including strength and power activities, team sports and the skills component of many sports, and for mental performance. A number of physiological mechanisms are responsible for the effects observed. Fluid consumption can be used to attenuate the development of a water deficit or to correct it. The composition and temperature of a drink and the volume and rate of its consumption can all influence the physiological responses to ingestion and can impact on exercise performance.

Fasting in king penguin. I. Hormonal and metabolic changes during breeding

1988 ◽  
Vol 254 (2) ◽  
pp. R170-R177 ◽  
Author(s):  
Y. Cherel ◽  
J. P. Robin ◽  
O. Walch ◽  
H. Karmann ◽  
P. Netchitailo ◽  
...  
Keyword(s):  
Uric Acid ◽  
Mass Loss ◽  
Phase Ii ◽  
Plasma Corticosterone ◽  
Phase Iii ◽  
Plasma Glucagon ◽  
Protein Utilization ◽  
Plasma Uric Acid ◽  
Low Levels ◽  
Beta Hydroxybutyrate

During long-term fasting in birds and mammals, protein utilization initially decreases (phase I), is thereafter maintained at a low value (phase II), and then further increases (phase III). To delineate hormonal and biochemical changes responsible for these modifications, the effect of food deprivation for 50 days was studied in 6 male king penguins captured at the beginning of their natural breeding fast. During phase II, both rate of mass loss and plasma uric acid concentration remained at low levels, whereas plasma beta-hydroxybutyrate concentration increased. In phase III there was by contrast a 2.5-fold increase in the rate of mass loss, an eightfold increase in plasma uric acid, and an 80% drop in plasma beta-hydroxybutyrate. Plasma corticosterone was low and steady in phase II and increased three times in phase III. During the overall fast, there were no significant variations in plasma insulin, but there was a fourfold increase in plasma glucagon and a decrease in plasma thyroxine and triiodothyronine. These findings suggest that protein sparing (phase II) requires low levels of corticosterone, insulin, and thyroid hormones, whereas the further increase in protein utilization (phase III) is due to an increase in plasma corticosterone. The high plasma glucagon concentration in phase III is presumably responsible for a transient increase in plasma glucose observed at this stage; such increase in glucagon could enhance gluconeogenesis from amino acids.

scholarly journals Effect of Fourteen Days of Acclimatization on Athletic Performance in Tropical Climate

2002 ◽  
Vol 27 (6) ◽  
pp. 551-562 ◽  
Author(s):  
Bruno Voltaire ◽  
Olivier Galy ◽  
Olivier Coste ◽  
Sébastien Racinais ◽  
André Callis ◽  
...  
Keyword(s):  
Mass Loss ◽  
Body Mass ◽  
Sweat Rate ◽  
Tropical Climate ◽  
The Body ◽  
Tympanic Temperature ◽  
Body Mass Loss ◽  
Tropical Conditions ◽  
The Mean ◽  
And Performance

In order to study the acclimatization process over 14 days of exposure to tropical climate, 9 triathletes performed 4 outdoor indirect continuous multistage tests in both thermoneutral and tropical conditions. The thermoneutral test (TN, 14 °C, 45% rh) was performed before traveling to the tropical area (Martinique, FWI). The tropical tests were performed 2, 8, and 14 days after arrival (32.9 °C, 78% rh). During each trial, we measured tympanic temperature, sweat rate, body mass loss, heart rate (HR), and performance. The results showed that 1) the mean tympanic temperature was greater in T2 (P < .001), T8 (P < .01) and T14 (P < .01) than in TN and significantly lower in T14 than in T2 (P < .05); 2) the mean sweat rate was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 3) the body mass loss after trials was significantly greater (P < .001) in T2, T8 and T14 than in TN and significantly greater (P < .05) in T8 and T14 than in T2; 4) the mean HR and HR at rest were significantly higher (P < .005) in T2 than in TN, T8, T14 and the mean HR was significantly lower (P < .05) in T14 than in the other trials; and 5) the performance time was significantly lower in T2 (P < 0.02), T8 (P < 0.03) and T14 (P < 0.05) than in TN. We concluded that 14 days of exposure to tropical climate led to changes in physiological parameters but were still insufficient to ensure complete acclimatization in well-trained athletes. The hot/wet climate induced impairment of physiological responses and performance that were still evident on the 14th day. Keywords: triathletes, aerobic performance, jet lag, dehydration, hyperthermia

scholarly journals Sauna-induced body mass loss in physically inactive young women and men

2016 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Robert Podstawski ◽  
Tomasz Boraczyński ◽  
Michał Boraczyński ◽  
Dariusz Choszcz ◽  
Stefan Mańkowski ◽  
...  
Keyword(s):  
Mass Loss ◽  
Body Mass ◽  
Young Women ◽  
Body Height ◽  
The Body ◽  
Regression Equations ◽  
Full Time ◽  
Body Mass Loss ◽  
Increased Risk ◽  
Physically Inactive

SummaryStudy aim: The aim of this study was to evaluate the relationship between basic somatic features (body mass and height) and body mass loss in physically inactive young women and men exposed to thermal stress in a dry sauna.Materials and methods: The research was conducted in 2015 on 685 first-year full-time students (333 women, 352 men), aged 19–20 years old. Nude body mass was measured after the students dried off before and after using the sauna.Results: An analysis of regression equations indicated that an increase in the body mass of women and men leads to a significant increase in sauna-induced body mass loss. On the other hand, body mass loss decreased with an increase in height in women and men, but to a smaller extent. From among the tested somatic features, body height and body mass, body mass had a decisive influence on body mass loss. Body height had a minimal and statistically non-significant impact on body mass loss.Conclusions: The results of this study indicate that heavier individuals have an increased risk of dehydration and hyperthermia. Therefore, they should pay close attention to replenishing fluids lost in the sauna. The determination of body mass loss values after a visit to a dry sauna has practical significance because it supports the estimation of the fluid volume required for the maintenance of correct water balance.

scholarly journals Does the stress response predict the ability of wild birds to adjust to short-term captivity? A study of the rock pigeon ( Columbia livia )

2016 ◽  
Vol 3 (12) ◽  
pp. 160840 ◽  
Author(s):  
Frédéric Angelier ◽  
Charline Parenteau ◽  
Colette Trouvé ◽  
Nicole Angelier
Keyword(s):  
Stress Response ◽  
Mass Loss ◽  
Body Mass ◽  
Stress Hormones ◽  
Short Term ◽  
Body Mass Loss ◽  
Lower Ability ◽  
Columbia Livia ◽  
Confined Environment

Although the transfer of wild animals to captivity is crucial for conservation purposes, this process is often challenging because some species or individuals do not adjust well to captive conditions. Chronic stress has been identified as a major concern for animals held on long-term captivity. Surprisingly, the first hours or days of captivity have been relatively overlooked. However, they are certainly very stressful, because individuals are being transferred to a totally novel and confined environment. To ensure the success of conservation programmes, it appears crucial to better understand the proximate causes of interspecific and interindividual variability in the sensitivity to these first hours of captivity. In that respect, the study of stress hormones is relevant, because the hormonal stress response may help to assess whether specific individuals or species adjust, or not, to such captive conditions (‘the stress response-adjustment to captivity hypothesis’). We tested this hypothesis in rock pigeons by measuring their corticosterone stress response and their ability to adjust to short-term captivity (body mass loss and circulating corticosterone levels after a day of captivity). We showed that an increased corticosterone stress response is associated with a lower ability to adjust to short-term captivity (i.e. higher body mass loss and circulating corticosterone levels). Our study suggests, therefore, that a low physiological sensitivity to stress may be beneficial for adjusting to captivity. Future studies should now explore whether the stress response can be useful to predict the ability of individuals from different populations or species to not only adjust to short-term but also long-term captivity.

Glycerol and NEFA kinetics in long-term fasting king penguins: phase IIversusphase III

2002 ◽  
Vol 205 (17) ◽  
pp. 2745-2754 ◽  
Author(s):  
S. F. Bernard ◽  
C. Fayolle ◽  
J.-P. Robin ◽  
R. Groscolas
Keyword(s):  
Body Mass ◽  
Phase Ii ◽  
Fat Mass ◽  
Feeding Behaviour ◽  
Fold Increase ◽  
Phase Iii ◽  
Protein Catabolism ◽  
Body Protein ◽  
Fat Stores

SUMMARYIn spontaneously fasting birds such as penguins, below a body mass threshold corresponding to the phase II—phase III transition, a metabolic and hormonal shift occurs and feeding behaviour is stimulated(`refeeding signal'). The major aim of this study was to determine whether a decrease in non-esterified fatty acid (NEFA) release from adipose tissue could be a component of this signal. Lipolytic fluxes and primary triacylglycerol:fatty acid (TAG:FA) cycling were determined in vivoin breeding, fasting king penguins (Aptenodytes patagonicus) using continuous infusions of 2-[3H]glycerol and 1-[14C]palmitate under field conditions. In phase II (after approximately 8 days of fasting, large fat stores, body protein spared, N=8), the rate of appearance (Ra) of glycerol and of NEFA were 5.7±0.8 and 10.5±0.4 μmol kg-1min-1, respectively, and the percentage of primary TAG:FA cycling was 41±7%. In phase III (after approximately 25 days of fasting, fat stores reduced by fourfold, increased body protein catabolism, N=9), Ra glycerol kg-1 body mass remained unchanged,whereas Ra glycerol kg-1 fat mass and Ra NEFA kg-1 body mass were increased by 2.8-fold and 1.5-fold, respectively. Increased Ra glycerol kg-1 fat mass was possibly the result of a 3.5-fold increase in circulating glucagon, the increased Ra NEFA kg-1 body mass being attributable to decreased primary TAG:FA cycling. Thus, triggering of the refeeding signal that redirects the behavior of fasting, incubating penguins from incubation towards the search for food after entrance into phase III cannot be ascribed to a reduction in lipolytic fluxes and NEFA availability.

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