Physiology of Hibernation in Mammals

Lyman, Charles P.; Chatfield, Paul O.

doi:10.1152/physrev.1955.35.2.403

Cited by 329 publications

(67 citation statements)

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“…Infusion of various drugs confirmed the view (Lyman and Chatfield, 1955) that the differential rewarming was caused by vasoconstriction. Hibernating ground squirrels were infused with P -TMlO 9.…”

Section: Arousal From Hibernationsupporting

confidence: 67%

“…We have emphasized previously that subcutaneous injections during hibernation cannot be sufficiently controlled to justify conclusions because response to physical stimulation is so variable. It is only during the acute process of arousal that experiments have been carried out which are sufficiently discrete to justify some conclusions (Lyman and Chatfield, 1955).…”

Section: Section 5 Discussionmentioning

confidence: 99%

“…Until recently, investigations of the entrance into hibernation and the hibernating state were perforce descriptive, for any physical disturbance of the animal usually started the process of arousal. During arousal various physiological manipulations could be carried out and the effects noted, so that this phase of the hibernating cycle is moderately well documented (Lyman and Chatfield, 1955). From these data it has been postulated that the sympathetic nervous system is importantly involved in the process of arousal.…”

Section: Noticesmentioning

confidence: 99%

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Autonomic Control of Circulation During the Hibernating Cycle in Ground Squirrels

Lyman¹,

O'Brien²

1963

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Section: Arousal From Hibernationsupporting

confidence: 67%

Section: Section 5 Discussionmentioning

confidence: 99%

Section: Noticesmentioning

confidence: 99%

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Autonomic Control of Circulation During the Hibernating Cycle in Ground Squirrels

Lyman¹,

O'Brien²

1963

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“…H ibernation is a highly regulated physiological response to adverse environmental conditions characterized by hypothermia and drastic reductions of metabolic rate (1). Hibernating species can adapt to anticipated scarcity in food supply and decreases in ambient temperature by storing food and increasing food intake for several weeks before winter starts (2).…”

mentioning

confidence: 99%

Rapid and reversible changes in intrahippocampal connectivity during the course of hibernation in European hamsters

Magariños

McEwen

Saboureau

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

124

102

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The hippocampal formation is a highly plastic brain structure that undergoes structural remodeling in response to internal and external challenges such as metabolic imbalance and repeated stress. We investigated whether the extreme alterations in metabolic status that occur during the course of hibernation in European hamsters cause structural changes in the dendritic arborizations of the CA3 pyramidal neurons and their main excitatory afferents, the mossy fiber terminals (MFT), that originate in the dentate gyrus. We report that apical, but not basal, dendritic trees of Golgiimpregnated CA3 principal neurons are significantly shorter, less branched, and less spiny in hypothermic hamsters compared with active animals. After the induction of arousal from torpor, within 2 h, the apical dendritic lengths, branching patterns, and spine density estimations returned to levels found in active, euthermic hamsters. The ultrastructure of MFT in hibernating hamsters showed a significant reduction in synaptic vesicle density and in the percentage of MFT area covered by spine profiles. Awakened hamsters showed restoration of MFT morphology to that seen in active animals. MFT of torpid animals also showed a significant increase in the percentage area of mitochondrial profiles that remained higher 3 h after induced arousal from hibernation compared with euthermic controls. Thus, the torpid/awakening cycle of the hibernating European hamster causes a rapid and reversible morphological reorganization of intrahippocampal subregions involved in information processing. The reported reductions in morphological connectivity between the dentate gyrus and the CA3 subregions could underlie the cessation of exploratory activity and spatial navigation skills during hibernation.CA3 region ͉ hippocampus ͉ mossy fibers ͉ spines ͉ Golgi impregnation H ibernation is a highly regulated physiological response to adverse environmental conditions characterized by hypothermia and drastic reductions of metabolic rate (1). Hibernating species can adapt to anticipated scarcity in food supply and decreases in ambient temperature by storing food and increasing food intake for several weeks before winter starts (2). Once the animals enter into hibernation, they develop an energy conserving behavior and undergo deep bouts of hypothermia (or torpor) alternated with short euthermic intervals termed periodic arousals (3). By using fat stores as their primary source of energy and reducing carbohydrate metabolism, hibernating mammals sustain vital functions during prolonged periods without feeding and support periodic rewarming during interbout arousals (4).The physiological mechanisms triggering hibernation are very complex and far from being well known. Its seasonal occurrence is primarily regulated by the annual photoperiodic variations, and the neuroendocrine and neural mechanisms involved have been partly identified (5-8). The hippocampus, a target brain region for stressful challenges and adrenal steroids (9), has been postulated as a key structure in th...

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“…It is known that hibernators can be aroused by mechanical stimuli (Lyman, 1955). In an assessment of the effects of a winter detonation, the limits of mechanical concussion tolerable without arousal, as well as the effects of winter arousal should be known.…”

Section: Discussionmentioning

confidence: 99%

TERRESTRIAL MAMMAL INVESTIGATIONS, OGOTORUK CREEK, CAPE THOMPSON AND VICINITY. Phase III, Progress Report

Pruitt¹,

Lent²,

Carl³

et al. 1961

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Physiology of Hibernation in Mammals

Cited by 329 publications

References 0 publications

Autonomic Control of Circulation During the Hibernating Cycle in Ground Squirrels

Autonomic Control of Circulation During the Hibernating Cycle in Ground Squirrels

Rapid and reversible changes in intrahippocampal connectivity during the course of hibernation in European hamsters

TERRESTRIAL MAMMAL INVESTIGATIONS, OGOTORUK CREEK, CAPE THOMPSON AND VICINITY. Phase III, Progress Report

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