Fuel metabolism in Canada geese: effects of glucagon on glucose kinetics

Vaillancourt, Eric; Weber, Jean‐Michel

doi:10.1152/ajpregu.00080.2015

Cited by 3 publications

(2 citation statements)

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“…During fasting, they can stand colder conditions better than any other bird, while maintaining their usual body temperature [ 6 ] thanks to the huddling behaviour [ 7 , 8 ]. Birds can undertake strenuous efforts during long distance migration, while flying hundreds of kilometres without food or drink [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

et al. 2020

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In recent years a revival of interest has emerged in the health benefits of intermittent fasting and long-term fasting, as well as of other related nutritional strategies. In addition to meal size and composition a new focus on time and frequency of meals has gained attention. The present review will investigate the effects of the main forms of fasting, activating the metabolic switch from glucose to fat and ketones (G-to-K), starting 12-16 h after cessation or strong reduction of food intake. During fasting the deactivation of mTOR regulated nutrient signalling pathways and activation of the AMP protein kinase trigger cell repair and inhibit anabolic processes. Clinical and animal studies have clearly indicated that modulating diet and meal frequency, as well as application of fasting patterns, e.g. intermittent fasting, periodic fasting, or long-term fasting are part of a new lifestyle approach leading to increased life and health span, enhanced intrinsic defences against oxidative and metabolic stresses, improved cognition, as well as a decrease in cardiovascular risk in both obese and non-obese subjects. Finally, in order to better understand the mechanisms beyond fasting-related changes, human studies as well as non-human models closer to human physiology may offer useful clues. KEY-MESSAGES 1. Biochemical changes during fasting are characterised by a glucose to ketone switch, leading to a rise of ketones, advantageously used for brain energy, with consequent improved cognition. 2. Ketones reduce appetite and help maintain effective fasting. 3. Application of fasting patterns increases healthy life span and defences against oxidative and metabolic stresses. 4. Today's strategies for the use of therapeutic fasting are based on different protocols, generally relying on intermittent fasting, of different duration and calorie intake. 5. Long-term fasting, with durations between 5 and 21 days can be successfully repeated in the course of a year.

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Section: Introductionmentioning

confidence: 99%

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

et al. 2020

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“…A replenishment of glycogen stores during fasting has been observed in several taxa ( [99]; reviewed in [100]). The endogenous carbon sources needed for gluconeogenesis to replenish glycogen stores are likely GLYC and gluconeogenic amino acids [101][102][103]. Consistently, both GLYC and UA do not decrease before landing.…”

Section: Changes Of Fuel Supply During Nocturnal Migratory Endurance ...mentioning

confidence: 99%

Energy supply during nocturnal endurance flight of migrant birds: effect of energy stores and flight behaviour

Jenni-Eiermann,

Liechti,

Briedis

et al. 2024

Mov Ecol

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Background Migrating birds fly non-stop for hours or even for days. They rely mainly on fat as fuel complemented by a certain amount of protein. Studies on homing pigeons and birds flying in a wind-tunnel suggest that the shares of fat and protein on total energy expenditure vary with flight duration and body fat stores. Also, flight behaviour, such as descending flight, is expected to affect metabolism. However, studies on free flying migrant birds under natural conditions are lacking. Methods On a Swiss Alpine pass, we caught three species of nocturnal migrant passerines out of their natural migratory flight. Since most night migrants start soon after dusk, we used time since dusk as a measure of flight duration. We used plasma concentrations of metabolites of the fat, protein, and carbohydrate metabolism as indicators of relative fuel use. We used flight altitudes of birds tracked with radar and with atmospheric pressure loggers to characterize flight behaviour. Results The indicators of fat catabolism (triglycerides, very low-density lipoproteins, glycerol) were positively correlated with body energy stores, supporting earlier findings that birds with high fat stores have a higher fat catabolism. As expected, plasma levels of triglycerides, very low-density lipoproteins, glycerol and ß-hydroxy-butyrate increased at the beginning of the night, indicating that nocturnal migrants increased their fat metabolism directly after take-off. Surprisingly, fat catabolism as well as glucose levels decreased in the second half of the night. Data from radar observations showed that the number of birds aloft, their mean height above ground and vertical flight speed decreased after midnight. Together with the findings from atmospheric pressure-loggers put on three species, this shows that nocturnal migrants migrating over continental Europe descend slowly during about 1.5 h before final landfall at night, which results in 11–30% energy savings according to current flight models. Conclusions We suggest that this slow descent reduces energy demands to an extent which is noticeable in the plasma concentration of lipid, protein, and carbohydrate metabolites. The slow descent may facilitate the search for a suitable resting habitat and serve to refill glycogen stores needed for foraging and predator escape when landed.

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Endocrine mechanisms controlling the migratory disposition in birds

Tsvey

2023

Proceedings ZIN

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On Earth, billions of birds make seasonal migrations every year. Some species fly thousands of kilometers, overcoming seas, mountains and deserts on their way. For migration to be successful, birds must have perfect mechanisms for controlling its beginning, duration and termination. On the way, birds have to make many decisions: how much in energy reserves to accumulate; when to depart, how long and in which direction to fly; how to select optimal weather conditions for flight; and, finally, when and where to terminate migration. Prior to migration, birds develop a migratory disposition – a suite of changes in physiology and behavior (e.g. migratory fattening and expression of nocturnal migratory activity) which are typical for this important life-history stage. Such physiological changes and migratory behavior are the subject of hormonal regulation. The central structure that controls activity of various hormonal systems and development of migratory disposition is the hypothalamic-pituitary system. The hypothalamus controls the secretion of regulatory hormones by the pituitary gland and these hormones, in turn, regulate the activity of downstream endocrine glands. It has been established that spring migratory disposition is triggered by an increasing photoperiod, which stimulates the production of testosterone, prolactin and modulates the signaling of thyroid hormones. In contrast, it is practically unknown how autumn migratory disposition develops when the photoperiod decreases and does not stimulate release of the abovementioned hormones. While in migratory disposition, the endocrine control of behavior on the smaller temporal scales (for example, the level of fuel accumulation, or decision to depart from a migratory stopover) is associated with the combined action of melatonin, corticosterone, insulin, glucagon, adipokines, and other hormones and neurotransmitters. In this review, I will describe the role of these hormones in the control of migratory traits, highlight the existing inconsistencies, and present possible ways to progress in this area of research. A knowledge of endocrine regulation of migratory behavior will help to predict the limits of species adaptability, explain current population trends, and inform conservation actions, which is especially important in the light of modern climate change and anthropogenic transformation of landscapes.

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Fuel metabolism in Canada geese: effects of glucagon on glucose kinetics

Cited by 3 publications

References 50 publications

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

Unravelling the health effects of fasting: a long road from obesity treatment to healthy life span increase and improved cognition

Energy supply during nocturnal endurance flight of migrant birds: effect of energy stores and flight behaviour

Endocrine mechanisms controlling the migratory disposition in birds

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