Sensitivity to low temperature in hibernating rodents

Lyman, Charles P.; O'Brien, RC

doi:10.1152/ajplegacy.1972.222.4.864

Cited by 41 publications

(6 citation statements)

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“…The length of the hibernation cycle of hamster is 80-100 h. Torpor lasts for approximately 70 h during which time the whole body MR of the hamster is approximately 2.5% of cenothermic cold adapted RMR [2,3,26]. In torpor, small changes in MR can be performed to defend the reduced body temperature against fluctuations in the low ambient temperature [29,30]. Arousal from hibernation (rectal and brain temperature 4-5°C) to CEN (35-37°C) takes 3-3.5 h at an ambient temperature of 4°C and, on the basis of physiological parameters it can be divided into early, middle and late arousal phases.…”

Section: Animals and Housingmentioning

confidence: 99%

Determination In Vivo of Newly Synthesized Gene Expression in Hamsters During Phases of the Hibernation Cycle

Osborne

Gao

Hashimoto

2004

JJP

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Hibernation is a circannual adaptation and within the hibernation season, the hibernation cycle of a 'classic' hibernator, such as the Syrian hamster, can be divided into six distinct physiological phases. An entrance phase, when metabolism is inhibited and body temperature decreases [1]. A long period of torpor when metabolic rate (MR) is approximately 2.5% of resting metabolic rate (RMR) [2, 3]. This is followed by an arousal period of three phases: an early arousal phase during which the animal warms anterior crucial organs by non-shivering thermogenesis; a middle arousal phase when shivering thermogenesis is recruited to heat the anterior body to cenothermia (CEN) and a late arousal phase when posterior organs attain CEN and the animal rests or sleeps. An inter-bout arousal phase, of hours to days, during which time the hibernator maintains CEN body temperature before the initiation of another hibernation cycle. At present the onset of the hibernation cycle cannot be predicted. (Cenothermia is the IUPS term replacing euthermia [4]).Molecularly orientated studies have searched for up-or-down regulation of gene expression in a small number of organs from torpid animals in an attempt to demonstrate molecular changes that are consistent with the enormous physiological changes occurring across the hibernation cycle [5]. Early investigations used radioactively labeled precursors to measure in vivo transcription in brains [6,7], translation in liver [8,9], and more recently translation in brain and heart 14 C]-leucine. In torpor, RNA synthesis was 5-25% of CEN levels depending upon tissue. In brain and heart mRNA was not preferentially synthesized. Protein was synthesized at low, tissue specific levels during torpor. Initiation of arousal and the warming of anterior organs via non-shivering thermogenesis during the early arousal occurred without measurable synthesis of RNA or proteins. Tissue specific levels of RNA and protein synthesis occurred later after shivering thermogenesis had been recruited and was strongly influenced by thermal gradients in the body. In the middle arousal phase, protein synthesis is most active in the brain despite modest synthesis of RNA and mRNA. The majority of molecular processing required for the induction and maintenance of torpor and the arousal from torpor up until the onset of shivering thermogenesis occurs during the cenothermic period before the hamster initiates the hibernation cycle. [The Japanese Journal of Physiology 54: [295][296][297][298][299][300][301][302][303][304][305] 2004]

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Section: Animals and Housingmentioning

confidence: 99%

Determination In Vivo of Newly Synthesized Gene Expression in Hamsters During Phases of the Hibernation Cycle

Osborne

Gao

Hashimoto

2004

JJP

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“…It seems clear that thermoreceptivity of CNS persists during hibernation. Hibernating animals increased oxygen consumption and maintained body temperature without arousal in response to cold stimulation (Lyman and O'Brien, 1972;Mills and South, 1972;Hammel et al, 1973;Heller and Colliver, 1974;Weidler et al, 1974). Whether NST contributes to temperature control during the maintenance stage of hibernation is unknown.…”

Section: Cns Control Of Nst During Hibernationmentioning

confidence: 99%

Arousal from hibernation and BAT thermogenesis against cold: central mechanism and molecular basis

Hashimoto

Gao

Kikuchi-Utsumi

et al. 2002

Journal of Thermal Biology

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“…However, cortical silence associated with lowered body temperature does not pose a threat to the survival of the animal because important thermoregulatory centers are subcortical. Lyman and O'Brien (11) concluded that peripheral temperature receptors in C. tridecemlineatus and C. lateralis are not involved in temperature regulation during hibernation, and that accurate sensing of decrlines in brain temperature allows the hibernator to arouse from lethal cold.…”

Section: Days Inmentioning

confidence: 99%