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https://www.readbyqxmd.com/read/29311303/pyruvate-induces-torpor-in-obese-mice
#1
Marion Soto, Lucie Orliaguet, Michelle L Reyzer, M Lisa Manier, Richard M Caprioli, C Ronald Kahn
Mice subjected to cold or caloric deprivation can reduce body temperature and metabolic rate and enter a state of torpor. Here we show that administration of pyruvate, an energy-rich metabolic intermediate, can induce torpor in mice with diet-induced or genetic obesity. This is associated with marked hypothermia, decreased activity, and decreased metabolic rate. The drop in body temperature correlates with the degree of obesity and is blunted by housing mice at thermoneutrality. Induction of torpor by pyruvate in obese mice relies on adenosine signaling and is accompanied by changes in brain levels of hexose bisphosphate and GABA as detected by mass spectroscopy-based imaging...
January 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29301689/2-deoxy-d-glucose-not-mercaptoacetate-induces-a-reversible-reduction-of-body-temperature-in-male-desert-hamsters-phodopus-roborovskii
#2
Qing-Sheng Chi, Xiu-Juan Li, De-Hua Wang
The initiation of torpor is supposed to be related to the availability of metabolic fuels. Studies on metabolic fuel inhibition of glucose by using 2-deoxy-D-glucose (2DG) or fatty acid by mercaptoacetate (MA) in heterothermic mammals produced mixed outcomes. To examine the roles of availability of glucose and fatty acid in the initiation of torpor in desert hamsters (Phodopus roborovskii), we intraperitoneally administrated 2DG and MA to summer-acclimated male hamsters while body temperature (Tb), metabolic rate (MR) and respiratory quotient (RQ) were simultaneously recorded to monitor their thermoregulatory response...
January 2018: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29299670/flexibility-is-the-key-metabolic-and-thermoregulatory-behaviour-in-a-small-endotherm
#3
Franz Langer, Nadine Havenstein, Joanna Fietz
Hibernation is the most effective way to reduce thermoregulatory costs during periods of unfavourable environmental conditions. In preparation to hibernation, fat-storing hibernators accumulate large quantities of body fat, which increases their locomotor costs and also the risk of predation. As a consequence, there should be a strong selective pressure to restrict pre-hibernation fattening to a short-time period before the onset of hibernation. The edible dormouse (Glis glis) is characterized by having adapted its whole life history to the irregularly occurring mast-seeding pattern of the European beech (Fagus sylvaticus)...
January 3, 2018: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/29260372/changes-in-neocortical-and-hippocampal-microglial-cells-during-hibernation
#4
Gonzalo León-Espinosa, Mamen Regalado-Reyes, Javier DeFelipe, Alberto Muñoz
Mammalian hibernation proceeds alongside a wide range of complex brain adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. Using immunofluorescence, confocal microscopy, quantitative analysis methods and intracellular injections, we have characterized microglia morphological changes that occur in the neocortex and hippocampus of the Syrian hamster during hibernation. In euthermic hamsters, microglial cells showed the typical ramified/resting morphology with multiple long, thin and highly-branched processes homogeneously immunostained for Iba-1...
December 19, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/29248591/strategies-of-biochemical-adaptation-for-hibernation-in-a-south-american-marsupial-dromiciops-gliroides-3-activation-of-pro-survival-response-pathways
#5
Bryan E Luu, Sanoji Wijenayake, Jing Zhang, Shannon N Tessier, Julian F Quintero-Galvis, Juan Diego Gaitán-Espitia, Roberto F Nespolo, Kenneth B Storey
The South American marsupial, monito del monte (Dromiciops gliroides) uses both daily torpor and multi-day hibernation to survive in its southern Chile native environment. The present study leverages multiplex technology to assess the contributions of key stress-inducible cell cycle regulators and heat shock proteins to hibernation in liver, heart, and brain of monito del monte in a comparison of control versus 4day hibernating conditions. The data indicate that MDM2, a stress-responsive ubiquitin ligase, plays a crucial role in marsupial hibernation since all three tissues showed statistically significant increases in MDM2 levels during torpor (1...
December 14, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
https://www.readbyqxmd.com/read/29247846/strategies-of-biochemical-adaptation-for-hibernation-in-a-south-american-marsupial-dromiciops-gliroides-2-control-of-the-akt-pathway-and-protein-translation-machinery
#6
Bryan E Luu, Sanoji Wijenayake, Jing Zhang, Shannon N Tessier, Julian F Quintero-Galvis, Juan Diego Gaitán-Espitia, Roberto F Nespolo, Kenneth B Storey
When faced with harsh environmental conditions, the South American marsupial, monito del monte (Dromiciops gliroides), reduces its body temperature and uses either daily torpor or multiday hibernation to survive. This study used ELISA and multiplex assays to characterize the responses to hibernation by three regulatory components of protein translation machinery [p-eIF2α(S51), p-eIF4E(S209), p-4EBP(Thr37/46)] and eight targets involved in upstream signaling control of translation [p-IGF-1R(Tyr1135/1136), PTEN(S380), p-Akt(S473), p-GSK-3α(S21), p-GSK-3β(S9), p-TSC2(S939), p-mTOR(S2448), and p70S6K(T412)]...
December 13, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
https://www.readbyqxmd.com/read/29247845/strategies-of-biochemical-adaptation-for-hibernation-in-a-south-american-marsupial-dromiciops-gliroides-1-mitogen-activated-protein-kinases-and-the-cell-stress-response
#7
Sanoji Wijenayake, Bryan E Luu, Jing Zhang, Shannon N Tessier, Julian F Quintero-Galvis, Juan Diego Gaitán-Espitia, Roberto F Nespolo, Kenneth B Storey
Hibernation is a period of torpor and heterothermy that is typically associated with a strong reduction in metabolic rate, global suppression of transcription and translation, and upregulation of various genes/proteins that are central to the cellular stress response such as protein kinases, antioxidants, and heat shock proteins. The current study examined cell signaling cascades in hibernating monito del monte, Dromiciops gliroides, a South American marsupial of the Order Microbiotheria. Responses to hibernation by members of the mitogen-activated protein kinase (MAPK) pathways, and their roles in coordinating hibernator metabolism were examined in liver, kidney, heart and brain of control and versus hibernating (4days continuous torpor) D...
December 13, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
https://www.readbyqxmd.com/read/29247844/strategies-of-biochemical-adaptation-for-hibernation-in-a-south-american-marsupial-dromiciops-gliroides-4-regulation-of-pyruvate-dehydrogenase-complex-and-metabolic-fuel-selection
#8
Sanoji Wijenayake, Bryan E Luu, Jing Zhang, Shannon N Tessier, Julian F Quintero-Galvis, Juan Diego Gaitán-Espitia, Roberto F Nespolo, Kenneth B Storey
Mammalian hibernation is characterized by extensive adjustments to metabolism that typically include suppression of carbohydrate catabolism and a switch to triglycerides as the primary fuel during torpor. A crucial locus of control in this process is the pyruvate dehydrogenase complex that gates carbohydrate entry into the tricarboxylic acid cycle. Within the complex, the E1 enzyme pyruvate dehydrogenase (PDH) is the main regulatory site and is subject to inhibitory phosphorylation at three serine residues (S232, S293, S300)...
December 13, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
https://www.readbyqxmd.com/read/29166160/sex-dependent-phenological-plasticity-in-an-arctic-hibernator
#9
Cory T Williams, C Loren Buck, Michael J Sheriff, Melanie M Richter, Jesse S Krause, Brian M Barnes
Hibernation provides a means of escaping the metabolic challenges associated with seasonality, yet the ability of mammals to prolong or reenter seasonal dormancy in response to extreme weather events is unclear. Here, we show that Arctic ground squirrels in northern Alaska exhibited sex-dependent plasticity in the physiology and phenology of hibernation in response to a series of late spring snowstorms in 2013 that resulted in the latest snowmelt on record. Females and nonreproductive males responded to the >1-month delay in snowmelt by extending heterothermy or reentering hibernation after several days of euthermy, leading to a >2-week delay in reproduction compared to surrounding years...
December 2017: American Naturalist
https://www.readbyqxmd.com/read/29163191/phoenix-from-the-ashes-fire-torpor-and-the-evolution-of-mammalian-endothermy
#10
Fritz Geiser, Clare Stawski, Chris B Wacker, Julia Nowack
No abstract text is available yet for this article.
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/29158126/physiological-and-behavioral-responses-of-an-arboreal-mammal-to-smoke-and-charcoal-ash-substrate
#11
Julia Nowack, Clare Stawski, Gerhard Körtner, Fritz Geiser
The recent observation that torpor plays a key role in post-fire survival has been mainly attributed to the reduced food resources after fires. However, some of these adjustments can be facilitated or amplified by environmental changes associated with fires, such as the presence of a charcoal-ash substrate. In a previous experiment on a small terrestrial mammal the presence of charcoal and ash linked to food restriction intensified torpor use. However, whether fire cues also act as a trigger of torpor use when food is available and whether they affect other species including arboreal mammals remains elusive...
November 17, 2017: Physiology & Behavior
https://www.readbyqxmd.com/read/29142044/thermoregulatory-role-of-insensible-evaporative-water-loss-constancy-in-a-heterothermic-marsupial
#12
Christine Elizabeth Cooper, Philip Carew Withers
'Insensible' evaporative water loss of mammals has been traditionally viewed as a passive process, but recent studies suggest that insensible water loss is under regulatory control, although the physiological role of this control is unclear. We test the hypothesis that regulation of insensible water loss has a thermoregulatory function by quantifying for the first time evaporative water loss control, along with metabolic rate and body temperature, of a heterothermic mammal during normothermia and torpor. Evaporative water loss was independent of ambient relative humidity at ambient temperatures of 20 and 30°C, but not at 25°C or during torpor at 20°C...
November 2017: Biology Letters
https://www.readbyqxmd.com/read/29133226/the-effect-of-dietary-neonicotinoid-pesticides-on-non-flight-thermogenesis-in-worker-bumble-bees-bombus-terrestris
#13
Robert Potts, Rebecca M Clarke, Sophie E Oldfield, Lisa K Wood, Natalie Hempel de Ibarra, James E Cresswell
For bumble bees (genus Bombus), the capacity for non-flight thermogenesis is essential for two fundamental processes undertaken by adult workers, namely recovery from torpor after chilling and brood incubation. Farmland bees can be widely exposed to dietary residues of neurotoxic neonicotinoid insecticides that appear in the nectar and pollen of treated bee-attractive crops, which may harm them. An earlier study shows that dietary neonicotinoids cause complex alterations to thermoregulation in honey bees, but their effects on the thermogenic capabilities of individual bumble bees has been untested previously...
November 10, 2017: Journal of Insect Physiology
https://www.readbyqxmd.com/read/29125496/consciousness-in-hibernation-and-synthetic-torpor
#14
Matteo Cerri
While human hibernation would provide many advantages for medical applications and space exploration, the intrinsic risks of the procedure itself, as well as those involved if the procedure were to be misused, need to be assessed. Moreover, the distinctive brain state that is present during a hibernation-like state raises questions regarding the state of consciousness of the subject. Since, in animal studies, the cortical activity of this state differs from that of sleep, coma, or even general anesthesia, and resembles a sort of "slowed wakefulness", it is uncertain whether residual consciousness may still be present...
November 7, 2017: Journal of Integrative Neuroscience
https://www.readbyqxmd.com/read/29113989/cold-hearted-bats-uncoupling-of-heart-rate-and-metabolism-during-torpor-at-subzero-temperatures
#15
Shannon E Currie, Clare Stawski, Fritz Geiser
Many hibernating animals thermoregulate during torpor and defend their body temperature (Tb) below 10°C by an increase in metabolic rate. Above a critical temperature (Tcrit) animals usually thermoconform. We investigated the physiological responses above and below Tcrit for a small tree dwelling bat (Chalinolobus gouldii, ∼14 g) that is often exposed to subzero temperatures during winter. Through simultaneous measurement of heart rate (HR) and oxygen consumption (V̇O2) we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures (Ta 5-20°C)...
November 7, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29108557/seasonal-energetics-and-torpor-use-in-north-american-flying-squirrels
#16
Megan N Olson, Jeff Bowman, Gary Burness
Seasonal cold temperatures require mammals to use morphological, behavioural, or physiological traits to survive periods of extreme cold and food shortage. Torpor is a physiological state that minimizes energy requirements by decreasing resting metabolic rate (MR) and body temperature (Tb). Many rodent species are capable of torpor, however, evidence in northern and southern flying squirrels (Glaucomys sabrinus and Glaucomys volans, respectively) has remained anecdotal. We experimentally attempted to induce torpor in wild-caught flying squirrels by lowering ambient temperature (Ta) and measuring MR using open-flow respirometry...
December 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29045417/effects-of-food-store-quality-on-hibernation-performance-in-common-hamsters
#17
Carina Siutz, Matthias Nemeth, Karl-Heinz Wagner, Ruth Quint, Thomas Ruf, Eva Millesi
Hibernating animals can adjust torpor expression according to available energy reserves. Besides the quantity, the quality of energy reserves could play an important role for overwintering strategies. Common hamsters are food-storing hibernators and show high individual variation in hibernation performance, which might be related to the quality of food hoards in the hibernacula. In this study, we tested the effects of food stores high in fat content, particularly polyunsaturated fatty acids (PUFAs), on hibernation patterns under laboratory conditions...
2017: PloS One
https://www.readbyqxmd.com/read/29038037/brain-inflammatory-cytokines-and-microglia-morphology-changes-throughout-hibernation-phases-in-syrian-hamster
#18
V Cogut, J J Bruintjes, B J L Eggen, E A van der Zee, R H Henning
Hibernators tolerate low metabolism, reduced cerebral blood flow and hypothermia during torpor without noticeable neuronal or synaptic dysfunction upon arousal. Previous studies found extensive changes in brain during torpor, including synaptic rearrangements, documented both morphologically and molecularly. As such adaptations may represent organ damage, we anticipated an inflammatory response in brain during specific hibernation phases. In this study, signs of inflammation in the brain were investigated in the Syrian hamster hippocampus (Mesocricetus Auratus) both during hibernation (torpor and arousal phases) and in summer and winter euthermic animals...
October 13, 2017: Brain, Behavior, and Immunity
https://www.readbyqxmd.com/read/29037383/regulation-of-pyruvate-dehydrogenase-pdh-in-the-hibernating-ground-squirrel-ictidomys-tridecemlineatus
#19
Sanoji Wijenayake, Shannon N Tessier, Kenneth B Storey
Pyruvate dehydrogenase (PDH) is a vital regulatory enzyme that catalyzes the conversion of pyruvate into acetyl-CoA and connects anaerobic glycolysis to aerobic TCA cycle. Post-translational inhibition of PDH activity via three serine phosphorylation sites (pS232, pS293, and pS300) regulate the metabolic flux through the TCA cycle, decrease glucose utilization, and facilitate lipid metabolism during times of nutrient deprivation. As metabolic readjustment is necessary to survive hibernation, the purpose of this study was to explore the post-translational regulation of pyruvate dehydrogenase and the expression levels of four mitochondrial serine/threonine kinases (PDHKs), during torpor-arousal cycles in liver, heart, and skeletal muscle of 13-lined ground squirrels...
October 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29023516/hypothalamic-control-systems-show-differential-gene-expression-during-spontaneous-daily-torpor-and-fasting-induced-torpor-in-the-djungarian-hamster-phodopus-sungorus
#20
Ceyda Cubuk, Hanna Markowsky, Annika Herwig
Djungarian hamsters are able to use spontaneous daily torpor (SDT) during the winter season as well as fasting-induced torpor (FIT) at any time of the year to cope with energetically challenging environmental conditions. Torpor is a state of severely reduced metabolism with a pronounced decrease in body temperature, which enables animals to decrease their individual energy requirements. Despite sharing common characteristics, such as reduced body mass before first torpor expression and depressed metabolism and body temperature during the torpid state, FIT and SDT differ in several physiological properties including torpor bout duration, minimal body temperature, fuel utilization and circadian organization...
2017: PloS One
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