scholarly journals Oral bezafibrates induce long and spontaneous torpor bouts in mice

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Lisa Pei Chu ◽  
Steven John Swoap
Keyword(s):  
Torpor Bouts

Loss of circadian organization of sleep and wakefulness during hibernation

2002 ◽  
Vol 282 (4) ◽  
pp. R1086-R1095 ◽  
Author(s):  
Jennie E. Larkin ◽  
Paul Franken ◽  
H. Craig Heller
Keyword(s):  
Brain Temperature ◽  
Nrem Sleep ◽  
Wave Activity ◽  
Ground Squirrels ◽  
Ultradian Rhythm ◽  
Organization Of Sleep ◽  
Sleep Homeostasis ◽  
Circadian Organization ◽  
Frequency Components ◽  
Torpor Bouts

We investigated circadian and homeostatic regulation of nonrapid eye movement (NREM) sleep in golden-mantled ground squirrels during euthermic intervals between torpor bouts. Slow-wave activity (SWA; 1–4 Hz) and sigma activity (10–15 Hz) represent the two dominant electroencephalographic (EEG) frequency components of NREM sleep. EEG sigma activity has a strong circadian component in addition to a sleep homeostatic component, whereas SWA mainly reflects sleep homeostasis [Dijk DJ and Czeisler CA. J Neurosci 15: 3526–3538, 1995; Dijk DJ, Shanahan TL, Duffy JF, Ronda JM, and Czeisler CA. J Physiol (Lond) 505: 851–858, 1997]. Animals maintained under constant conditions continued to display circadian rhythms in both sigma activity and brain temperature throughout euthermic intervals, whereas sleep and wakefulness showed no circadian organization. Instead, sleep and wakefulness were distributed according to a 6-h ultradian rhythm. SWA, NREM sleep bout length, and sigma activity responded homeostatically to the ultradian sleep-wake pattern. We suggest that the loss of sleep-wake consolidation in ground squirrels during the hibernation season may be related to the greatly decreased locomotor activity during the hibernation season and may be necessary for maintenance of multiday torpor bouts characteristic of hibernating species.

Hypoglycemia and torpor in Siberian hamsters

1999 ◽  
Vol 276 (3) ◽  
pp. R776-R781 ◽  
Author(s):  
John Dark ◽  
Daniel A. Lewis ◽  
Irving Zucker
Keyword(s):  
Blood Glucose ◽  
Body Temperature ◽  
Body Mass ◽  
Air Temperature ◽  
Day Length ◽  
Siberian Hamsters ◽  
Long Day ◽  
Necessary And Sufficient ◽  
Blood Glucose Concentrations ◽  
Torpor Bouts

We tested whether reduced blood glucose concentrations are necessary and sufficient for initiation of torpor in Siberian hamsters. During spontaneous torpor bouts, body temperature (Tb) decreases from the euthermic value of 37 to <31°C. Among hamsters that displayed torpor during maintenance in a short-day length (10 h light/day) at an air temperature of 15°C, blood glucose concentrations decreased significantly by 28% as Tb fell from 37 to <31°C and increased during rewarming so that by the time Tb first was >36°C, glucose concentrations had returned to the value preceding torpor. Hamsters did not display torpor when maintained in a long-day length (16 h light/day) and injected with a range of insulin doses (1–50 U/kg body mass), some of which resulted in sustained, pronounced hypoglycemia. We conclude that changes in blood glucose concentrations may be a consequence rather than a cause of the torpid state and question whether induction of torpor by 2-deoxy-d-glucose is due to its general glucoprivic actions.

Accelerated reproductive development in juvenile male ground squirrels fed a high-fat diet

1992 ◽  
Vol 262 (4) ◽  
pp. R644-R650 ◽  
Author(s):  
J. Dark ◽  
N. F. Ruby ◽  
G. N. Wade ◽  
P. Licht ◽  
I. Zucker
Keyword(s):  
High Fat Diet ◽  
Average Duration ◽  
Reproductive Development ◽  
Ground Squirrels ◽  
Plasma Testosterone ◽  
Juvenile Male ◽  
High Fat ◽  
Reproductive Condition ◽  
Juvenile Males ◽  
Torpor Bouts

Male golden-mantled ground squirrels held at 23 degrees C were fed high-fat (HF) or standard (chow) diets. In December, ambient temperature was reduced to 6 degrees C, food was removed, and frequency and duration of torpor bouts were monitored continuously by radiotelemetry. Reproductive condition and body composition were assessed upon terminal arousal in the spring. Juvenile males fed the HF diet weighed more than chow-fed controls before and throughout the hibernation season and had significantly greater lipid masses at terminal arousal. Testes masses and plasma testosterone concentrations were substantially higher in HF than in chow-fed juveniles. The accelerated reproductive development of fatter squirrels was not contingent upon increases in the total number of days spent in torpor, number of torpor bouts, or the average duration of each arousal from torpor. Access to the HF diet had no effect on body mass, adiposity, or reproductive status of adult male ground squirrels in spring. Threshold levels of white adipose tissue and associated differences in availability of metabolic fuels may be permissive for testicular growth during the hibernation season. Juveniles exceed this threshold only when fed the HF diet.

scholarly journals Hibernation in a primate: does sleep occur?

2016 ◽  
Vol 3 (8) ◽  
pp. 160282 ◽  
Author(s):  
Marina B. Blanco ◽  
Kathrin H. Dausmann ◽  
Sheena L. Faherty ◽  
Peter Klopfer ◽  
Andrew D. Krystal ◽  
...  
Keyword(s):  
Rem Sleep ◽  
Low Voltage ◽  
Ground Squirrels ◽  
Cold Weather ◽  
Close Relative ◽  
Gradual Transition ◽  
Physiological Processes ◽  
Tropical Conditions ◽  
Eeg Recordings ◽  
Torpor Bouts

During hibernation, critical physiological processes are downregulated and thermogenically induced arousals are presumably needed periodically to fulfil those physiological demands. Among the processes incompatible with a hypome tabolic state is sleep. However, one hibernating primate, the dwarf lemur Cheirogaleus medius , experiences rapid eye movement (REM)-like states during hibernation, whenever passively reaching temperatures above 30°C, as occurs when it hibernates in poorly insulated tree hollows under tropical conditions. Here, we report electroencephalographic (EEG) recordings, temperature data and metabolic rates from two related species ( C. crossleyi and C. sibreei ), inhabiting high-altitude rainforests and hibernating underground, conditions that mirror, to some extent, those experienced by temperate hibernators. We compared the physiology of hibernation and spontaneous arousals in these animals to C. medius , as well as the much more distantly related non-primate hibernators, such as Arctic, golden-mantled and European ground squirrels. We observed a number of commonalities with non-primate temperate hibernators including: (i) monotonous ultra-low voltage EEG during torpor bouts in these relatively cold-weather hibernators, (ii) the absence of sleep during torpor bouts, (iii) the occurrence of spontaneous arousals out of torpor, during which sleep regularly occurred, (iv) relatively high early EEG non-REM during the arousal, and (v) a gradual transition to the torpid EEG state from non-REM sleep. Unlike C. medius , our study species did not display sleep-like states during torpor bouts, but instead exclusively exhibited them during arousals. During these short euthermic periods, non-REM as well as REM sleep-like stages were observed. Differences observed between these two species and their close relative, C. medius , for which data have been published, presumably reflect differences in hibernaculum temperature.

scholarly journals Breeding and hibernation of captive meadow jumping mice (Zapus hudsonius)

2020 ◽  
Author(s):  
Ethan A. Brem ◽  
Alyssa D. McNulty ◽  
William J. Israelsen
Keyword(s):  
Food Consumption ◽  
Generation Time ◽  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Captive Breeding ◽  
Laboratory Setting ◽  
Significant Excess ◽  
Short Generation Time ◽  
Potential Applications ◽  
Torpor Bouts

AbstractHibernating mammals exhibit unique metabolic and physiological phenotypes that have potential applications in medicine or spaceflight, yet our understanding of the genetic basis and molecular mechanisms of hibernation is limited. The meadow jumping mouse, a small North American hibernator, exhibits traits – including a short generation time – that would facilitate genetic approaches to hibernation research. Here we report the collection, captive breeding, and laboratory hibernation of meadow jumping mice. Captive breeders in our colony produced a statistically significant excess of male offspring and a large number of all-male and all-female litters. We confirmed that short photoperiod induced pre-hibernation fattening, and cold ambient temperature facilitated entry into hibernation. During pre-hibernation fattening, food consumption exhibited non-linear dependence on both body mass and temperature, such that food consumption was greatest in the heaviest animals at the coldest temperatures. Meadow jumping mice exhibited a strong circadian rhythm of nightly activity that was disrupted during the hibernation interval. We quantified the length and timing of torpor bouts and arousals obtained from an uninterrupted recording of a hibernating female. Over a 90.6 day hibernation interval, torpor bouts ranged from 2.1 to 12.8 days (mean 7.7 days), and arousal length was relatively constant with a mean length of 9.6 hours. We conclude that it is possible to study hibernation phenotypes using captive-bred meadow jumping mice in a laboratory setting.

Hibernation in the Eastern Pygmy Possum, Cercartetus-Nanus (Marsupialia, Burramyidae)

1993 ◽  
Vol 41 (1) ◽  
pp. 67 ◽  
Author(s):  
F Geiser
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Air Temperature ◽  
The Body ◽  
Daily Torpor ◽  
Rate Of Oxygen Consumption ◽  
The Mean ◽  
Cercartetus Nanus ◽  
Torpor Bouts

The pattern of torpor was examined in the eastern pygmy possum, Cercartetus nanus (21 g). Animals displayed torpor regularly in the laboratory, and the occurrence of torpor increased with decreasing air temperature (T(a)). At high T(a) (18-degrees-C) animals usually exhibited daily torpor, but torpor bouts of up to 2 days were observed occasionally. The duration of torpor bouts lengthened with a lowering of T(a) and the mean bout duration at T(a) = 5-degrees-C was 17.0 +/- 2.5 days. The minimum metabolic rate (measured as rate of oxygen consumption) of torpid individuals was 0.018 +/- 0.003 mL O2 g-1 h-1, which is less than 2% of the basal metabolic rate. The body temperature (T(b)) Of torpid animals fell to a minimum of 1.3 +/- 0.4-degrees-C. These results clearly demonstrate that Cercartetus nanus is a deep hibernator.

Hibernation in Free-Living Mountain Pygmy-Possums, Burramys Parvus (Marsupialia, Burramyidae)

1995 ◽  
Vol 43 (4) ◽  
pp. 373 ◽  
Author(s):  
LS Broome ◽  
F Geiser
Keyword(s):  
Temperature Sensitive ◽  
Free Living ◽  
Temperature Regimes ◽  
In The Wild ◽  
Males And Females ◽  
Torpor Bouts

The long-term pattern of hibernation was studied in free-living mountain pygmy-possums, Burramys parvus, using temperature-sensitive radio-collars. Most males and females began to hibernate in early June within one week of their release. Hibernation was interrupted by spontaneous arousals that were followed by short normothermic periods and re-entry into torpor. The duration of multiday torpor bouts averaged 8 . 0 days (range 3-17 days) and arousal periods averaged 19 . 1 h. Single-day torpor bouts were observed occasionally. The duration of torpor bouts lengthened with the progress of the hibernation season and normothermic periods became shorter. The pattern of hibernation in free-living B. parvus was similar to that of captive individuals maintained under temperature regimes that were similar to those in the wild.

AMP does not induce torpor

2007 ◽  
Vol 293 (1) ◽  
pp. R468-R473 ◽  
Author(s):  
Steven J. Swoap ◽  
Meaghan Rathvon ◽  
Margaret Gutilla
Keyword(s):  
Heart Rate ◽  
Adenosine Receptor ◽  
Maximum Rate ◽  
Adenine Nucleotides ◽  
Induced Hypothermia ◽  
Animal Kingdom ◽  
Fasted State ◽  
Severe Hypothermia ◽  
Hypothermic Effect ◽  
Torpor Bouts

Torpor, a state characterized by a well-orchestrated reduction of metabolic rate and body temperature (Tb), is employed for energetic savings by organisms throughout the animal kingdom. The nucleotide AMP has recently been purported to be a primary regulator of torpor in mice, as circulating AMP is elevated in the fasted state, and administration of AMP causes severe hypothermia. However, we have found that the characteristics and parameters of the hypothermia induced by AMP were dissimilar to those of fasting-induced torpor bouts in mice. Although administration of AMP induced hypothermia (minimum Tb = 25.2 ± 0.6°C) similar to the depth of fasting-induced torpor (24.9 ± 1.5°C), ADP and ATP were equally effective in lowering Tb (minimum Tb: 24.8 ± 0.9°C and 24.0 ± 0.5°C, respectively). The maximum rate of Tb fall into hypothermia was significantly faster with injection of adenine nucleotides (AMP: −0.24 ± 0.03; ADP: −0.24 ± 0.02; ATP: −0.25 ± 0.03°C/min) than during fasting-induced torpor (−0.13 ± 0.02°C/min). Heart rate decreased from 755 ± 15 to 268 ± 17 beats per minute (bpm) within 1 min of AMP administration, unlike that observed during torpor (from 646 ± 21 to 294 ± 19 bpm over 35 min). Finally, the hypothermic effect of AMP was blunted with preadministration of an adenosine receptor blocker, suggesting that AMP action on Tb is mediated via the adenosine receptor. These data suggest that injection of adenine nucleotides into mice induces a reversible hypothermic state that is unrelated to fasting-induced torpor.

Metabolic Physiology of Euthermic and Torpid Honey Possums, Tarsipes-Rostratus

1989 ◽  
Vol 37 (6) ◽  
pp. 685 ◽  
Author(s):  
PC Withers ◽  
KC Richardson ◽  
RD Wooller
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Oxygen Consumption Rate ◽  
Consumption Rate ◽  
Thermal Conductance ◽  
Short Term ◽  
Apparent Absence ◽  
Metabolic Physiology ◽  
Fat Stores ◽  
Torpor Bouts

Euthermic honey possums have a higher body temperature (Tb), basal metabolic rate and wet thermal conductance than other marsupials of similar mass. Honey possums enter torpor when cold-stressed and deprived of food. The pattern of decline in body temperature and oxygen consumption during torpor generally resembles that of other heterothermic endotherms. The duration of torpor bouts in honey possums was about 10 h; torpor bouts longer than one day were not observed. The Tb declined during torpor to within 1-2�C of ambient temperature (Ta>5�C) and oxygen consumption rate declined dramatically. The minimal body temperature (Tb,min) measured for torpid honey possums was about 5�C, because Tb was regulated at about 5�C by honey possums torpid at Ta<5�C, by an elevation of oxygen consumption rate. Previous studies of small marsupials have delineated two basic patterns of torpor: (1) shallow (Tb,min>10-15�C) and short-term torpor cycles (e.g. in dasyurids); (2) deep (Tb,min<10�C) and multi-day torpor cycles (e.g. in burramyids). Honey possums appear to have a third pattern of deep (Tb,min=5�C) but short-term torpor. The ecological reasons for this pattern of deep torpor and the apparent absence of multi-day torpor in honey possums may be related to their nectarivorous diet and lack of extensive fat stores.

Sign in / Sign up

Export Citation Format

Share Document