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Glucoprivation counteracts effects of testosterone on daily torpor in Siberian hamsters
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 1996We tested whether 1) glucose availability is a signal for initiation of torpor in male hamsters and 2) glucoprivation can override the inhibitory effects of androgens on daily torpor. Male hamsters maintained at ambient temperatures of 8-16 degrees C were injected with 2-deoxy-D-glucose (2DG), a glucose analogue that interferes with cellular glucose ...
J, Dark +3 more
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THE TEMPORAL ORGANIZATION OF DAILY TORPOR AND HIBERNATION: CIRCADIAN AND CIRCANNUAL RHYTHMS
Chronobiology International, 2000Mammals and birds have evolved the ability to maintain a high and constant body temperature Tb over a wide range of ambient temperatures Ta using endogenous heat production. In many, especially small endotherms, cost for thermoregulatory heat production can exceed available energy; to overcome these energetic bottlenecks, they enter a state of torpor ...
G, Körtner, F, Geiser
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Djungarian Hamsters — Small Graminivores with Daily Torpor
2000The species of interest in this chapter, the Djungarian dwarf hamster (Phodopus sungorus), is sometimes also called the hairy-footed hamster. This name, which refers to fur covering even the soles of the feet in this species, indicates an adaptation to extremely harsh climatic conditions in its natural habitat, the subarid steppes of continental Asia ...
Thomas Ruf, Gerhard Heldmaier
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Central adenosine receptor signaling is necessary for daily torpor in mice
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2012When calorically restricted at cool ambient temperatures, mice conserve energy by entering torpor, during which metabolic rate (MR), body temperature (T b ), heart rate (HR), and locomotor activity (LMA) decrease. Treatment with exogenous adenosine produces a similar hypometabolic state.
Benjamin W, Iliff, Steven J, Swoap
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Tropical heterothermy is “cool”: The expression of daily torpor and hibernation in primates
Evolutionary Anthropology: Issues, News, and Reviews, 2018AbstractLiving nonhuman primates generally inhabit tropical forests, and torpor is regarded as a strategy employed by cold‐adapted organisms. Yet, some primates employ daily torpor or hibernation (heterothermy) under obligatory, temporary, or emergency circumstances. Though heterothermy is present in most mammalian lineages, there are only three extant
Marina B. Blanco +3 more
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Fasting-induced daily torpor in desert hamsters ( Phodopus roborovskii )
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2016Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters (Phodopus roborovskii, ~20g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted ...
Qing-Sheng, Chi +3 more
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Paraventricular nucleus ablation disrupts daily torpor in Siberian hamsters
Brain Research Bulletin, 1995Siberian hamsters were maintained in a short-day photoperiod (8 h light/day) at 15 degrees C; body temperature (Tb) was telemetrically monitored at 10-min intervals over the course of 4 months. Animals manifesting repeated torpor bouts (Tb < 30 degrees C) were subjected to lesions of the paraventricular nucleus (PVN) or a sham operation. In the 8 weeks
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Weather Patterns and Daily Torpor in Free-ranging Animals
2000Torpor was investigated in free-ranging tawny frogmouths (Podargus strigoides: Caprimulgiformes) and sugar gliders (Petaurus breviceps: Marsupialia) near Armidale, NSW, Australia. Both nocturnal species entered torpor regularly. Torpor was most frequent in June/July/August (frogmouth: 50.4%; sugar glider: 22.3%), the three coldest months of the year ...
Gerhard Körtner, Fritz Geiser
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Daily Torpor, Hibernation, and Heterothermy in Marsupials
2023Fritz Geiser, Christine E. Cooper
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Could daily torpor be modulated in response to environmental challenges?
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2009As ecosystems undergo global changes, there is an increasing interest on understanding how organisms respond to changing environments. In the tropics, climate change results in more extreme events. The induced food shortage may impact the energetic trade- off between metabolic demands.
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