Reduction of metabolic rate and thermoregulation during daily torpor

Song, Xuehang; Körtner, Gerhard; Geiser, Fritz

doi:10.1007/bf00367312

Cited by 82 publications

(34 citation statements)

References 23 publications

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“…Marsupial BMRs were measured in this study except for those for S. macroura and T. vulpecula, where literature values were used [2,29]. For eutherians, except Me.…”

Section: Methodsmentioning

confidence: 99%

Phylogenetic differences of mammalian basal metabolic rate are not explained by mitochondrial basal proton leak

et al. 2011

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Metabolic rates of mammals presumably increased during the evolution of endothermy, but molecular and cellular mechanisms underlying basal metabolic rate (BMR) are still not understood. It has been established that mitochondrial basal proton leak contributes significantly to BMR. Comparative studies among a diversity of eutherian mammals showed that BMR correlates with body mass and proton leak. Here, we studied BMR and mitochondrial basal proton leak in liver of various marsupial species. Surprisingly, we found that the mitochondrial proton leak was greater in marsupials than in eutherians, although marsupials have lower BMRs. To verify our finding, we kept similar-sized individuals of a marsupial opossum (Monodelphis domestica) and a eutherian rodent (Mesocricetus auratus) species under identical conditions, and directly compared BMR and basal proton leak. We confirmed an approximately 40 per cent lower mass specific BMR in the opossum although its proton leak was significantly higher (approx. 60%). We demonstrate that the increase in BMR during eutherian evolution is not based on a general increase in the mitochondrial proton leak, although there is a similar allometric relationship of proton leak and BMR within mammalian groups. The difference in proton leak between endothermic groups may assist in elucidating distinct metabolic and habitat requirements that have evolved during mammalian divergence.

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“…Marsupial BMRs were measured in this study except for those for S. macroura and T. vulpecula, where literature values were used [2,29]. For eutherians, except Me.…”

Section: Methodsmentioning

confidence: 99%

Phylogenetic differences of mammalian basal metabolic rate are not explained by mitochondrial basal proton leak

et al. 2011

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“…5 The same treatment protocol was used with food-restricted and free-feeding mice: for three consecutive days, we gave to half of each group of mice, in random order, one of three doses (20,200 or 600) in two subcutaneous injections (about 4 h after the onset and offset of the daily light phase). The other half of each group was used as controls and received the same volume of the solvent (phosphatebuffered saline).…”

Section: Leptin-treatmentmentioning

confidence: 99%

“…10,11 There is, however, no generally applicable criterion for distinguishing between normal resting levels and torpid states, and no consensus about the physiological changes that have to occur to initiate a torpor bout. 10,11,19,20 We therefore simply evaluated the frequency with which the MR of our mice fell for at least 160 min (that is, 5 consecutive measurements) below two arbitrary levels: 10 and 5 Wakg. And although these are rather moderate decreases of MR in comparison to the full-blown torpor bouts occurring in more severely food-restricted mice at lower Ta, 10 the MR changes described here, resemble torpor in their diurnal organization and in ending with a sharp increase of MR (see Figure 1A and B).…”

Section: Leptin Effects On Energy Balancementioning

confidence: 99%

Leptin selectively increases energy expenditure of food-restricted lean mice

et al. 1998

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OBJECTIVE: To ®nd out whether leptin can attenuate hypometabolic torpor-like states of metabolic rate (MR) in adult lean animals, as it attenuates the morning suppression of thermoregulatory thermogenesis in suckling-age rat pups. DESIGN: Leptin effects on MR and food intake were studied in mice aged 4±7 months, in which a high incidence of exaggerated circadian reductions of MR had been induced by chronic food-restriction and, for comparison, in freefeeding mice. PROTOCOL: Continuous recordings of MR, for a group of seven mice maintained at an ambient temperature of 24 C, while they were repeatedly ± with pauses of at least six days ± treated for three consecutive days with either recombinant murine leptin (20, 200 or 600 pmol Á g 71 Á d 71 ) or saline. RESULTS: Leptin treatment caused dose-dependent 5±15% increases in energy expenditure by moderating the decreases in MR during the circadian minima, without affecting either the MR during the circadian maxima or food intake. Similar treatment of free-feeding mice caused dose-dependent decreases of food intake without changing MR. CONCLUSION: Leptin controls thermoregulatory energy expenditure when food supplies are scarce and changes food intake, rather than energy expenditure, when food is abundant.

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“…The large reduction in body temperature associated with torpor and hibernation (often greater than 30°C) results from a thermoregulated reduction in metabolic heat production, even though the fall in body temperature itself helps further reduce metabolic rate (Heller & Hammel, 1972;Heldmaier & Ruf, 1992;Song et al 1995;Zimmer & Milsom, 2001). The mechanism responsible for the much smaller variation in body temperature associated with circadian rhythmicity (rarely greater than 4°C) has not been investigated in detail.…”

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confidence: 99%

Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the Rat

Refinetti

2003

Experimental Physiology

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Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase‐advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase‐delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1% of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature.

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Reduction of metabolic rate and thermoregulation during daily torpor

Cited by 82 publications

References 23 publications

Phylogenetic differences of mammalian basal metabolic rate are not explained by mitochondrial basal proton leak

Phylogenetic differences of mammalian basal metabolic rate are not explained by mitochondrial basal proton leak

Leptin selectively increases energy expenditure of food-restricted lean mice

Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the Rat

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