Activity During Natural Hibernation in Three Species of Vespertilionid Bats

Daan, Serge

doi:10.1163/002829673x00193

Cited by 84 publications

(87 citation statements)

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“…Despite their substantial energetic cost (9,35,66), periodic arousals are ubiquitous among mammalian hibernators, and numerous hypotheses have been advanced to explain their functional significance (71). In most instances, arousals are viewed as emerging from constraints imposed on animals that sustain low T b s for extended intervals; the periodic normothermia is viewed as necessary for removal of this, as yet to be identified, constraint.…”

Section: Discussionmentioning

confidence: 99%

“…They sustain elevated T b s for Ͻ1 day, after which they return to hibernation (21,53,71). Up to 80% of a hibernating mammal's winter energy budget is consumed during these periodic arousals (9,35,66), and the consequent depletion of energy stores may contribute to overwinter mortality (71). The functional significance of periodic arousals has proven enigmatic: hypotheses that arousals are required to clear metabolic waste (16), replenish blood glucose (20), restore cellular electrolyte balance (17), regenerate the gonads (1), prevent muscular atrophy (68), or eliminate sleep debt (10,56) have been proposed.…”

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confidence: 99%

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Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels

Prendergast

Freeman²,

Zucker

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

208

187

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Golden-mantled ground squirrels (Spermophilus lateralis) undergo seasonal hibernation during which core body temperature (Tb) values are maintained 1-2°C above ambient temperature. Hibernation is not continuous. Squirrels arouse at ϳ7-day intervals, during which Tb increases to 37°C for ϳ16 h; thereafter, they return to hibernation and sustain low Tbs until the next arousal. Over the course of the hibernation season, arousals consume 60-80% of a squirrel's winter energy budget, but their functional significance is unknown and disputed. Host-defense mechanisms appear to be downregulated during the hibernation season and preclude normal immune responses. These experiments assessed immune function during hibernation and subsequent periodic arousals. The acute-phase response to bacterial lipopolysaccharide (LPS) was arrested during hibernation and fully restored on arousal to normothermia. LPS injection (ip) resulted in a 1-1.5°C fever in normothermic animals that was sustained for Ͼ8 h. LPS was without effect in hibernating squirrels, neither inducing fever nor provoking arousal, but a fever did develop several days later, when squirrels next aroused from hibernation; the duration of this arousal was increased sixfold above baseline values. Intracerebroventricular infusions of prostaglandin E2 provoked arousal from hibernation and induced fever, suggesting that neural signaling pathways that mediate febrile responses are functional during hibernation. Periodic arousals may activate a dormant immune system, which can then combat pathogens that may have been introduced immediately before or during hibernation. circannual rhythms; Spermophilus lateralis; neural-immune interactions MAINTENANCE OF IMMUNE FUNCTION requires considerable energy expenditure (42, 62) and may limit or constrain the extent to which animals engage in other energetically demanding activities (39,40,58). Large seasonal increases in energy expenditure associated with reproduction or low ambient temperatures (5) may compete with the day-to-day demands of host defense. Sustained regulated hypothermia, in the form of hibernation or daily torpor, has been adopted by some mammals to contend with seasonal changes in temperature and energy availability. Golden-mantled ground squirrels (Spermophilus lateralis) spend 5-6 mo each year in deep hibernation, during which core body temperature (T b ) is maintained at 1-2°C above ambient temperature (T a ). Many physiological systems, including brain and renal metabolism, respiration, cardiac function, digestion, and mitosis, are arrested or substantially reduced during a hibernation bout (12,29,31,51,54,70,74).Although immune function during hibernation has been little studied, robust cell-mediated and humoral immune responses to pathogens are thought to be compromised. Impaired immune function in hibernators has been inferred from in vitro splenocyte proliferation or reduced antibody production over the course of an entire hibernation season (4,7,15,32,46,48,60). We are unaware of any studies that have assesse...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels

Prendergast

Freeman²,

Zucker

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

208

187

View full text Add to dashboard Cite

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“…Within this temperature range energy accumulated in white adipose tissue is used at the slowest rate, suggesting that during hibernation in natural conditions, bats would actively search for optimal temperatures to minimise fat utilisation and to maximise the potential hibernation time. Many authors have reported a positive correlation between ambient temperature and the frequency of spontaneous arousals from torpor of hibernating bats (e.g., Ransome, 1971;Daan, 1973;Harmata, 1987;Harrje 1994). These arousals constitute ca.…”

Section: Introductionmentioning

confidence: 99%

Sex and Age Related Habitat Selection and Mass Dynamics of Daubenton's BatsMyotis daubentonii(Kuhl, 1817) Hibernating in Natural Conditions

Kokurewicz

2004

Acta Chiropterologica

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“…Bats often hibernate in open caves,¯y around during arousal episodes, may feed and drink, and even occasionally leave their hibernacula during winter (Daan 1973a). The European hamster (Waûmer 1998) and the pygmy possum (KoÈ rtner and Geiser 1998; KoÈ rtner et al 1998) have also been reported to leave their hibernaculum for above-ground activity.…”

Section: Circadian Timing Of Arousalsmentioning

confidence: 99%

Body temperature patterns before, during, and after semi-natural hibernation in the European ground squirrel

Daan

2002

Journal of Comparative Physiology B: Biochemical, Systemic, and

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Body temperature patterns before, during, and after semi-natural hibernation in the European ground squirrel Hut, Roelof; Barnes, B.M.; Daan, S.; Heldmaier, G. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract Ground squirrels undergo extreme body temperature¯uctuations during hibernation. The eect of low body temperatures on the mammalian circadian system is still under debate. Using implanted temperature loggers, we recorded body temperature patterns in European ground squirrels kept in an enclosure under natural conditions. Although hibernation onset was delayed, hibernation end corresponded closely to that measured in a ®eld population. Circadian body temperature¯uctuations were not detected during deep torpor, but indications of circadian timing of arousal episodes at higher temperatures were found at the beginning and end of hibernation. One male exhibited synchronised arousals to a relatively constant phase of the day throughout hibernation. All animals ®rst entered torpor in the afternoon. Daily body temperature¯uc-tuations were decreased or distorted during the ®rst days after hibernation. We hypothesise that hibernation may aect the circadian system by either decreasing the expression of the circadian oscillator, or by decreasing the amplitude of the circadian oscillator itself, possibly due to gradual, temperature dependent, internal desynchronisation. The latter mechanism may be bene®cial because it might facilitate post-hibernation re-entrainment rates.Keywords Circadian rhythmicity á Torpor á Euthermia á Arrhythmicity á Implantable temperature loggers Abbreviations DD continuous darkness á LD light-dark cycle á SCN suprachiasmatic nuclei

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Activity During Natural Hibernation in Three Species of Vespertilionid Bats

Abstract: Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Cited by 84 publications

References 29 publications

Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels

Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels

Sex and Age Related Habitat Selection and Mass Dynamics of Daubenton's BatsMyotis daubentonii(Kuhl, 1817) Hibernating in Natural Conditions

Body temperature patterns before, during, and after semi-natural hibernation in the European ground squirrel

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