Are long chain acyl CoAs responsible for suppression of mitochondrial metabolism in hibernating 13-lined ground squirrels?

Cooper, Alex N.; Brown, Jason C. L.; Staples, James F.

doi:10.1016/j.cbpb.2014.02.002

Cited by 9 publications

(6 citation statements)

References 71 publications

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“…Transport of succinate into liver mitochondria does not appear to be differentially regulated between torpor and IBE in 13-lined ground squirrels (67). Moreover, the apparent affinity for succinate oxidation by intact mitochondria does not differ between torpor and IBE (39).…”

Section: Turning Down Atp Productionmentioning

confidence: 97%

Metabolic Flexibility: Hibernation, Torpor, and Estivation

Staples

2016

Comprehensive Physiology

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Many environmental conditions can constrain the ability of animals to obtain sufficient food energy, or transform that food energy into useful chemical forms. To survive extended periods under such conditions animals must suppress metabolic rate to conserve energy, water, or oxygen. Amongst small endotherms, this metabolic suppression is accompanied by and, in some cases, facilitated by a decrease in core body temperature-hibernation or daily torpor-though significant metabolic suppression can be achieved even with only modest cooling. Within some ectotherms, winter metabolic suppression exceeds the passive effects of cooling. During dry seasons, estivating ectotherms can reduce metabolism without changes in body temperature, conserving energy reserves, and reducing gas exchange and its inevitable loss of water vapor. This overview explores the similarities and differences of metabolic suppression among these states within adult animals (excluding developmental diapause), and integrates levels of organization from the whole animal to the genome, where possible. Several similarities among these states are highlighted, including patterns and regulation of metabolic balance, fuel use, and mitochondrial metabolism. Differences among models are also apparent, particularly in whether the metabolic suppression is intrinsic to the tissue or depends on the whole-animal response. While in these hypometabolic states, tissues from many animals are tolerant of hypoxia/anoxia, ischemia/reperfusion, and disuse. These natural models may, therefore, serve as valuable and instructive models for biomedical research.

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Section: Turning Down Atp Productionmentioning

confidence: 97%

Metabolic Flexibility: Hibernation, Torpor, and Estivation

Staples

2016

Comprehensive Physiology

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136

116

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“…Temperature passively controls mitochondrial energy conversion through Q 10 effects, although there is evidence for additional active metabolic depression that persists in isolated mitochondria from hibernating artic and thirteen‐lined ground squirrels ( Spermophilus parryii ) and in torpid Djungarian hamsters ( Phodopus sungorus ) . Mitochondrial substrate oxidation is reduced during hibernation and this appears to be controlled by succinate dehydrogenase activity and possibly allosteric inhibition . The reduction in mitochondrial ATP production correlates with T b rather than metabolic rate per se .…”

Section: Cellular Biochemical and Molecular Adaptation During Torpormentioning

confidence: 99%

Seasonal Control of Mammalian Energy Balance: Recent Advances in the Understanding of Daily Torpor and Hibernation

Jastroch

Giroud

Barrett

et al. 2016

J Neuroendocrinology

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Endothermic mammals and birds require intensive energy turnover to sustain high body temperatures and metabolic rates. To cope with the energetic bottlenecks associated with the change of seasons, and to minimise energy expenditure, complex mechanisms and strategies are used, such as daily torpor and hibernation. During torpor, metabolic depression and low body temperatures save energy. However, these bouts of torpor, lasting for hours to weeks, are interrupted by active 'euthermic' phases with high body temperatures. These dynamic transitions require precise communication between the brain and peripheral tissues to defend rheostasis in energetics, body mass and body temperature. The hypothalamus appears to be the major control centre in the brain, coordinating energy metabolism and body temperature. The sympathetic nervous system controls body temperature by adjustments of shivering and nonshivering thermogenesis, with the latter being primarily executed by brown adipose tissue. Over the last decade, comparative physiologists have put forward integrative studies on the ecophysiology, biochemistry and molecular regulation of energy balance in response to seasonal challenges, food availability and ambient temperature. Mammals coping with such environments comprise excellent model organisms for studying the dynamic regulation of energy metabolism. Beyond the understanding of how animals survive in nature, these studies also uncover general mechanisms of mammalian energy homeostasis. This research will benefit efforts of translational medicine aiming to combat emerging human metabolic disorders. The present review focuses on recent advances in the understanding of energy balance and its neuronal and endocrine control during the most extreme metabolic fluctuations in nature: daily torpor and hibernation.

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“…101;Supplemental Table S1 and Refs. 3,16,19,20,23,25,26,37,40,51,53,83,99). Investigation of other tissues, like the brain, may provide insight into the overall metabolic mechanisms of ground squirrels and hibernators in general.…”

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confidence: 99%

Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation

Ballinger

Schwartz

Andrews

2017

American Journal of Physiology-Regulatory, Integrative and Comp

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During hibernation, thirteen-lined ground squirrels () regularly cycle between bouts of torpor and interbout arousal (IBA). Most of the brain is electrically quiescent during torpor but regains activity quickly upon arousal to IBA, resulting in extreme oscillations in energy demand during hibernation. We predicted increased functional capacity of brain mitochondria during hibernation compared with spring to accommodate the variable energy demands of hibernation. To address this hypothesis, we examined mitochondrial bioenergetics in the ground squirrel brain across three time points: spring (SP), torpor (TOR), and IBA. Respiration rates of isolated brain mitochondria through complex I of the electron transport chain were more than twofold higher in TOR and IBA than in SP ( < 0.05). We also found a 10% increase in membrane potential between hibernation and spring ( < 0.05), and that proton leak was lower in TOR and IBA than in SP. Finally, there was a 30% increase in calcium loading in SP brain mitochondria compared with TOR and IBA ( < 0.01). To analyze brain mitochondrial abundance between spring and hibernation, we measured the ratio of copy number in a mitochondrial gene () vs. a nuclear gene () in frozen cerebral cortex samples. No significant differences were observed in DNA copies between SP and IBA. These data show that brain mitochondrial bioenergetics are not static across the year and suggest that brain mitochondria function more effectively during the hibernation season, allowing for rapid production of energy to meet demand when extreme physiological changes are occurring.

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Are long chain acyl CoAs responsible for suppression of mitochondrial metabolism in hibernating 13-lined ground squirrels?

Cited by 9 publications

References 71 publications

Metabolic Flexibility: Hibernation, Torpor, and Estivation

Metabolic Flexibility: Hibernation, Torpor, and Estivation

Seasonal Control of Mammalian Energy Balance: Recent Advances in the Understanding of Daily Torpor and Hibernation

Enhanced oxidative capacity of ground squirrel brain mitochondria during hibernation

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