Fasting-induced rise in locomotor activity in rats coincides with increased protein utilization

Locomotion is crucial for the survival of living organisms, as it allows foraging, flight and mating behaviour. In response to environmental cues, many organisms switch between alternative forms of locomotion, referred to as gaits. The nematode Caenorhabditis elegans exhibits two gaits: swimming in liquids and crawling on dense gels. The kinematics and patterns of muscle activity differ between the two gaits, with swimming being less efficient than crawling. We found that C. elegans when grown on dietary restriction (DR) plates and then tested immediately for swimming activity exhibit an accelerated frequency of body-bending swimming compared with ad libitum-fed worms, resulting in an increased swimming speed. This response is independent of the presence or absence of food bacteria in the assay liquid. In contrast, the crawling speed of DR worms on assay agar plates is decreased and influenced by food availability. Because DR also attenuates the disturbed swimming activity of worms that are deficient in the presynaptic dopamine transporter DAT-1, our data link DR-induced alterations of the swimming gait to synaptic processes. This strongly suggests a biochemical rather than a biomechanical response to DR provoked by changes in the worm's body structure. We conclude that the increase in locomotor activity in response to DR is specific to the swimming gait and might represent a survival strategy, allowing food-deprived nematodes to exit unfavourable environments.

Section: Research Articlementioning

confidence: 98%

Section: Research Articlementioning

confidence: 99%

Section: Research Articlementioning

confidence: 99%

See 1 more Smart Citation

Gait-specific adaptation of locomotor activity in response to dietary restriction inCaenorhabditis elegans

Lüersen

Faust

Gottschling

et al. 2014

“…in ducks; Geiger et al, 2012), reaching the critical stage of PIII enhances oxidative respiration, allowing an individual to mobilize its last resources necessary to undertake foraging activities (Goodman et al, 1981;Groscolas and Robin, 2001). Increases in metabolic rate with the onset of PIII have indeed been observed in penguins (Cherel et al, 1994b;Groscolas and Robin, 2001;Groscolas et al, 2000) and rats (Koubi et al, 1991), and the transition from PII to PIII appears to be accompanied by an increase in oxidative damage (in ducks: Geiger et al, 2012;in rats: Wasselin et al, 2014).…”

Section: Beginningmentioning

confidence: 99%

The oxidative debt of fasting: evidence for short to medium-term costs of advanced fasting in adult king penguins

Schull

Viblanc

Stier

et al. 2016

In response to prolonged periods of fasting, animals have evolved metabolic adaptations helping to mobilize body reserves and/or reduce metabolic rate to ensure a longer usage of reserves. However, those metabolic changes can be associated with higher exposure to oxidative stress, raising the question of how species that naturally fast during their life cycle avoid an accumulation of oxidative damage over time. King penguins repeatedly cope with fasting periods of up to several weeks. Here, we investigated how adult male penguins deal with oxidative stress after an experimentally induced moderate fasting period (PII) or an advanced fasting period (PIII). After fasting in captivity, birds were released to forage at sea. We measured plasmatic oxidative stress on the same individuals at the start and end of the fasting period and when they returned from foraging at sea. We found an increase in activity of the antioxidant enzyme superoxide dismutase along with fasting. However, PIII individuals showed higher oxidative damage at the end of the fast compared with PII individuals. When they returned from re-feeding at sea, all birds had recovered their initial body mass and exhibited low levels of oxidative damage. Notably, levels of oxidative damage after the foraging trip were correlated to the rate of mass gain at sea in PIII individuals but not in PII individuals. Altogether, our results suggest that fasting induces a transitory exposure to oxidative stress and that effort to recover in body mass after an advanced fasting period may be a neglected carryover cost of fasting.

“…They facilitate the mobilisation of fat (Divertie et al, 1991;Djurhuus et al, 2002;Djurhuus et al, 2004;Samra et al, 1998) and/or protein reserves as gluconeogenic precursors (Darmaun et al, 1988;Legaspi et al, 1985;Simmons et al, 1984;Weiler et al, 1997). Increased GCs direct fuel utilisation towards an increased reliance on protein catabolism, and have been shown to promote food-seeking behaviour through appetite centres in the brain in rodents, humans, horses (Equus ferus caballus) penguins and bottlenose dolphins (Tursiops truncatus) (Challet et al, 1995;Chen and Romsos, 1996;Debons et al, 1986;Groscolas and Robin, 2001;Koubi et al, 1991;Reidarson and McBain, 1999;Robin et al, 1998). If GCs act in a similar way in grey seals [Halichoerus grypus (Fabricius 1791)], as they do in other animals, they may be involved in the control of fuel use during fasting and timing of departure from the colony.…”

Section: Introductionmentioning

confidence: 99%

The role of glucocorticoids in naturally fasting grey seal (Halichoerus grypus) pups: dexamethasone stimulates mass loss and protein utilisation, but not departure from the colony

Bennett

Fedak

Moss

et al. 2012

SUMMARYSeals must manage their energy reserves carefully while they fast on land to ensure that they go to sea with sufficient fuel to sustain them until they find food. Glucocorticoids (GCs) have been implicated in the control of fuel metabolism and termination of fasting in pinnipeds. Here we tested the hypothesis that dexamethasone, an artificial GC, increases fat and protein catabolism, and induces departure from the breeding colony in wild, fasting grey seal pups. A single intramuscular dose of dexamethasone completely suppressed cortisol production for 24-72h, demonstrating activation of GC receptors. In experiment 1, we compared the effects of a single dose of dexamethasone or saline administered 10days after weaning on fasting mass and body composition changes, cortisol, blood urea nitrogen (BUN) and glucose levels, and timing of departure from the colony. In experiment 2, we investigated the effects of dexamethasone on short-term (5days) changes in mass loss, body composition and BUN levels. In experiment 1, dexamethasone induced a short-lived increase in mass loss, but there was no difference in timing of departure between dexamethasone-and saline-treated pups (N=10). In experiment 2, dexamethasone increased protein and water loss and prevented a decrease in BUN levels (N=11). Our data suggest changes in cortisol contribute to regulation of protein catabolism in fasting seal pups, irrespective of the sex of the animal, but do not terminate fasting. By affecting the rate of protein depletion, lasting changes in cortisol levels could influence the amount of time seal pups have to find food, and thus may have important consequences for their survival.