Mammalian Hibernation: An Escape from the Cold

Wang, Lawrence C.H.

doi:10.1007/978-3-642-73375-8_1

Cited by 33 publications

(13 citation statements)

References 133 publications

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“…The maintenance of pH 7.4 during hibernation involves a pronounced respiratory acidosis compared to the euthermic state since the neutrality of water increases from approximately 6.90 at 37°C to pH 7.40 at 5°C (Ma lan, 1986;Reeves, 1977). This acidosis may be a factor contributing to suppression of the metabolic rate during hibernation (Wang, 1988).…”

Section: Depression Of Cellular Functions In Hypothermia and Hibernatmentioning

confidence: 99%

“…Our own data, as well as those of earlier re ports, suggest that entrance into hibernation is an actively controlled process. Moreover, ground squirrels undergo profound circannual physiolog ical changes in a variety of systems, including en docrine and reproductive functions (for reviews see Lyman and Chatfield, 1955;Wang, 1988;Neder gaard and Cannon, 1990;Storey and Storey, 1990). These long-term changes, however, are not essen tial for hibernation, which is indicated by spontane ous "nonseasonal" hibernation.…”

Section: Cns Ischemiamentioning

confidence: 99%

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Local Cerebral Blood Flow during Hibernation, a Model of Natural Tolerance to “Cerebral Ischemia”

Frerichs¹,

Kennedy

Sokoloff

et al. 1994

J Cereb Blood Flow Metab

220

194

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The breakdown of cellular homeostasis and progressive neuronal destruction in cerebral ischemia appears to be mediated by a complex network of causes that are intricately interrelated. We have investigated a physiological state existing normally in nature in which mammals appear to tolerate the ordinarily detrimental effects of ischemia with reduced oxygen availability and to resist activation of self-destructive processes, i.e., mammalian hibernation. Ground squirrels (Spermophilus tridecemlineatus) were chronically implanted with arterial and venous catheters and telemetry devices for electroencephalography, electrocardiography, and monitoring of body temperature. The animals were placed in an environmental chamber at an ambient temperature of 5 degrees C. Entrance into hibernation was characterized by a drop in heart rate followed by a gradual decline in body temperature and an isoelectric electroencephalogram. Cold-adapted active animals that were not hibernating served as controls. Cerebral blood flow (CBF) was measured in both groups with the autoradiographic [14C]iodoantipyrine method. Mean (+/- SD) mass-weighted CBF in the brain was 62 +/- 18 ml 100 g(-1) min (-1) (n = 4) in the control group but was reduced to ischemic levels, 7 +/- 4 ml 100 g(-1) min (-1) (n = 4), in the hibernating animals (p < 0.001) [corrected]. No neuropathological changes were found in similarly hibernating animals aroused from hibernation. Hibernation appears to be actively regulated, and hormonal factors may be involved. The identification and characterization of such factors and of the mechanisms used by hibernating species to increase ischemic tolerance and to blunt the destructive effects of ischemia may enable us to prevent or minimize the loss of homeostatic control during and after cerebral ischemia in other species.

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Section: Depression Of Cellular Functions In Hypothermia and Hibernatmentioning

confidence: 99%

Section: Cns Ischemiamentioning

confidence: 99%

Local Cerebral Blood Flow during Hibernation, a Model of Natural Tolerance to “Cerebral Ischemia”

Frerichs¹,

Kennedy

Sokoloff

et al. 1994

J Cereb Blood Flow Metab

220

194

View full text Add to dashboard Cite

show abstract

“…Hibernation stages with their natural rhythm are recapitulated in the laboratory in a number of ground squirrel species, which provide excellent model organisms for hibernation research (Lyman et al 1982; Wang 1988). Several attributes of natural mammalian hibernation are of particular interest for potential applications in medicine, including: an inherent resistance to ischemia-reperfusion damage; muscle, bone and intestinal preservation in spite of disuse; and reversible metabolic depression (reviewed in Andrews 2007; Carey et al 2003; Drew et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Extensive use of torpor in 13-lined ground squirrels in the fall prior to cold exposure

et al. 2010

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Mammalian hibernation is characterized by profound reductions in body temperature (Tb) and metabolic, heart and respiratory rates. These reductions are characteristic of torpor, which is temporally confined to winter. Hibernators including ground squirrels are heterothermic in winter, cycling between multiday periods of torpor with low Tb and brief periods of rewarming. In contrast, ground squirrels remain homeothermic during summer, like non-hibernating mammals. The transition between the homeothermic and heterothermic phases of the circannual rhythm of hibernation is often overlooked in hibernation studies. Here, we examined the use of torpor throughout the fall transition in laboratory-housed 13-lined ground squirrels by recording core body temperature with an implanted data logger. As is typical of laboratory-based hibernation studies, animals were kept in standard housing prior to being moved into a cold, dark room to simulate natural hibernation conditions. Significantly, the vast majority of both male and female ground squirrels expressed torpor in the fall while still housed conventionally and prior to cold exposure. The expression of torpor was not predicted by body weight or age, rather it appears to be preprogrammed in a time-dependent manner that is independent of, yet enhanced by, environmental cues. The timing and duration of these torpor bouts occurring prior to cold exposure were also remarkably sporadic. Thus it is not possible to know with certainty which animals are torpor-naïve before cold exposure in the absence of continuous measurement of body temperature. We conclude that fall animals encompass variable points in the transition between summer and winter phases of the circannual cycle of hibernation, thereby confounding studies in which they are used as non-hibernating controls. Conversely, these fall transition animals offer unique opportunities to define the molecular changes that accompany and enable hibernation.

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“…1994Frerichs et aI. , 1995Wang, 1988) and temperature-independent resistance of hippocampal slices to glucose and oxygen deprivation in vitro (Frerichs and Hallenbeck, 1997) in addition to their tolerance of deep hypothermia.…”

mentioning

confidence: 99%

“…There is abundant evidence that induction and main tenance of the hibernating state involves specific cellular regulation rather than being a simple suspension of tem perature control or "reversion to primitive poikilo thermy" (Wang, 1988). Biochemical and molecular mechanisms of homeostatic regulation permit cells of hibernating animals to survive severe reduction in nutri ent perfusion and oxygen availability under extreme hy pothermic conditions.…”

mentioning

confidence: 99%

Stimulation of Tyrosine Phosphorylation of a Brain Protein by Hibernation

Ohtsuki

Jaffe

Brenner

et al. 1998

J Cereb Blood Flow Metab

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Summary: Mammalian hibernation is a state of natural toler ance to severely decreased brain blood flow, As protein tyro sine phosphorylation is believed to be involved in the devel opment of resistance to potentially cell-damaging insults, we used immunoblotting for the phosphotyrosine moiety to ana lyze extracts from various tissues of hibernating and nonhiber nating ground squirrels. A single, hibernation-specific phos phoprotein was detected in the brain, but not in any other tissue tested. This protein, designated pp98 to reflect its apparent molecular weight, is distributed throughout the brain, and is associated with the cellular membrane fraction. The presence of the protein is tightly linked to the hibernation state; it is notThe pathophysiology of progressive brain damage and neuronal death during stroke are multifactorial, interwo ven, and complex (Hallenbeck and Frerichs, 1993). Ex perimental therapies that are aimed at counteracting one or another of the many mediators of neuronal damage and death often have worked in animal stroke models that are sensitive to small effects; however, they have tended to perform weakly in clinical trials of acute ce rebral infarction (Dorman et aI., 1996;Hallenbeck and Dutka, 1990). It is difficult to design a new therapeutic approach that accounts for the many factors that partici pate in progressive ischemic brain injury which may act as a constellation of minor causes. Natural states of tol-

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Mammalian Hibernation: An Escape from the Cold

Cited by 33 publications

References 133 publications

Local Cerebral Blood Flow during Hibernation, a Model of Natural Tolerance to “Cerebral Ischemia”

Local Cerebral Blood Flow during Hibernation, a Model of Natural Tolerance to “Cerebral Ischemia”

Extensive use of torpor in 13-lined ground squirrels in the fall prior to cold exposure

Stimulation of Tyrosine Phosphorylation of a Brain Protein by Hibernation

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