A possible basis for periodic arousals during hibernation: Accumulation of ketone bodies

Baumber, Joan; South, Frank E.; Ferren, L.G.; Zatzman, Marvin L.

doi:10.1016/0024-3205(71)90308-0

Cited by 24 publications

(15 citation statements)

References 2 publications

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“…Although this metabolite increased significantly, its concentration remained extremely low when compared to other species undergoing similar duration fasts Baumber et al, 1971) and was also lower than observed in fasting elephant seal pups and lactating females. Plasma β-HBA concentration increases through the first 50 days of fasting in both elephant seal (Castellini and Costa, 1990;Champagne et al, 2005) and grey seal (Halichoerus grypus; Nordøy and Blix, 1991) weanlings.…”

Section: Discussionmentioning

confidence: 52%

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Crocker

Ortiz

Houser

et al. 2012

Comparative Biochemistry and Physiology Part A: Molecular &

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We measured metabolic hormones and several key metabolites in breeding adult male northern elephant seals to examine the regulation of fuel metabolism during extended natural fasts of over 3 months associated with high levels of energy expenditure. Males were sampled twice, early and late in the fast, losing an average of 23% of body mass and 47% of adipose stores between measurements. Males exhibited metabolic homeostasis over the breeding fast with no changes in glucose, non-esterified fatty acids, or blood urea nitrogen. Ketoacids increased over the fast but were very low when compared to other fasting species. Changes within individuals in total triiodothyronine (tT 3 ) were positively related to daily energy expenditure (DEE) and protein catabolism. Differences in levels of thyroid hormones relative to that observed in weaned pups and females suggest a greater deiodination of T 4 to support the high DEE of breeding males. Relative levels of leptin and ghrelin were consistent with the suppression of appetite but a significant reduction in growth hormone across the fast was contrary to expectation in fasting mammals. The lack of the increase in cortisol during fasting found in conspecific weaned pups and lactating females may contribute to the ability of breeding males to spare protein despite high levels of energy expenditure. Together these findings reveal significant differences with conspecifics under varying nutrient demands, suggesting metabolic adaptation to extended high energy fasts.

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Section: Discussionmentioning

confidence: 52%

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Crocker

Ortiz

Houser

et al. 2012

Comparative Biochemistry and Physiology Part A: Molecular &

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“…In the past, many of the hypotheses proposed to explain periodic arousals of bats from torpor related the phenomenon to processes correlated with MR (Galster and Morrison, 1970;Baumber et al, 1971). As we found no correlation between MR and TBL, regardless of ambient humidity, we could test the relationship between TBL and TEWL while keeping other confounding variables such as T a and MR constant.…”

Section: Discussionmentioning

confidence: 99%

“…Many different hypotheses attempting to explain periodic arousals have been proposed (Strumwasser, 1959;Galster and Morrison, 1970;Baumber et al, 1971;Daan et al, 1991;Thomas and Cloutier, 1992;Németh et al, 2010), as reviewed by Thomas and Geiser (Thomas and Geiser, 1997). One hypothesis proposes that during hibernation there is an accumulation of metabolic wastes, such as ketone bodies, and a need to replenish energy-rich substrates (Galster and Morrison, 1970;Baumber et al, 1971).…”

Section: Introductionmentioning

confidence: 99%

“…One hypothesis proposes that during hibernation there is an accumulation of metabolic wastes, such as ketone bodies, and a need to replenish energy-rich substrates (Galster and Morrison, 1970;Baumber et al, 1971). Another suggests that bats arouse to restore body water and electrolyte balance (Thomas and Cloutier, 1992;Thomas and Geiser, 1997;Németh et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats

Ben-Hamo

Muñoz‐Garcia

Williams

et al. 2013

Journal of Experimental Biology

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SUMMARYBats hibernate to cope with low ambient temperatures (T a ) and low food availability during winter. However, hibernation is frequently interrupted by arousals, when bats increase body temperature (T b ) and metabolic rate (MR) to normothermic levels. Arousals account for more than 85% of a batʼs winter energy expenditure. This has been associated with variation in T b , T a or both, leading to a single testable prediction, i.e. that torpor bout length (TBL) is negatively correlated with T a and T b . T a and T b were both found to be correlated with TBL, but correlations alone cannot establish a causal link between arousal and T b or T a . Because hydration state has also been implicated in arousals from hibernation, we hypothesized that water loss during hibernation creates the need in bats to arouse to drink. We measured TBL of bats (Pipistrellus kuhlii) at the same T a but under different conditions of humidity, and found an inverse relationship between TBL and total evaporative water loss, independent of metabolic rate, which directly supports the hypothesis that hydration state is a cue to arousal in bats.

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“…First, a metabolism theory proposes that the reduction of energy substrates or the accumulation of metabolic wastes forces animals to arouse to re-establish homeostatic conditions (Baumer et al 1971;Mrosovsky 1971;Galster & Morrison 1972). Because metabolic rate decreases as T a and T b decline to the lowest level that is not metabolically defended (T set ), this theory predicts that the duration of torpor bouts should increase with declining T a and T b .…”

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confidence: 99%

Periodic arousals in hibernating mammals: is evaporative water loss involved?

1997

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IntroductionWinter presents a severe metabolic challenge to homeotherms. Just as food availability drops to its annual minimum, low ambient temperatures (T a ) increase energy requirements. Many mammals escape this energy bottleneck by hibernating, whereby they reduce body temperature (T b ) usually below 10°C and metabolic rate to a fraction of that of normothermic individuals. The suppression of metabolic rate through torpor has a clear adaptive value when feeding opportunities are sporadic or non-existent and fat reserves are limited. Hibernators, however, do not exploit the energy savings of torpor to the maximum; all hibernators studied to date arouse periodically (Lyman et al. 1982). Although they account for > 75% of the total energy requirement for hibernation (Kayser 1953;Wang 1978;Thomas, Dorais & Bergeron 1990), arousals remain among the least understood of hibernation phenomena.Although numerous factors have been proposed to account for the occurrence and frequency of arousals, these can be broadly grouped under three principal Summary 1. Using existing data on the rate of cutaneous and pulmonary evaporative water loss (EWL) for hibernating Little Brown Bats (Myotis lucifugus) and on the duration of torpor bouts, body temperature (T b ) and oxygen uptake (V O 2 ) of Golden-mantled Ground Squirrels (Spermophilus saturatus), the rate of EWL was modelled for ground squirrels hibernating at ambient temperatures (T a ) of -2, 2, 4 and 8°C. 2. Total EWL showed a curvilinear response to T a , being lowest at 2°C and increasing with both increasing and decreasing T a . EWL at -2°C was about equal to that at 4°C. The duration of torpor bouts showed the same curvilinear response to T a and torpor bout duration at -2°C was similar to that at 4°C (8·5 vs 8·3 days, respectively). 3. At T a ≥ 2°C, where T b of torpid S. saturatus is not metabolically defended, torpor bout duration is significantly related to T b , V O 2 and EWL, with the three variables having similar r 2 values. 4. Using the regression equations generated at T a ≥ 2°C to predict torpor bout durations at -2°C, where T b is metabolically defended, shows that the three variables do not have equivalent predictive abilities. T b and V O 2 predicted torpor bout durations of 15·2 and -40·4 days, respectively, compared with observed durations of 8·5 days at -2°C. EWL predicted torpor bout durations of 8·4 days or only 0·1 days less than that observed at -2°C. 5. The relation between torpor bout duration and total EWL was insensitive to major variations in cutaneous EWL. Over T a ranging from -2°C to 8°C, a stepwise multiple regression including T b , V O 2 and EWL as independent variables identified EWL as the only variable significantly correlated with torpor bout duration. 6. Our analyses suggest that torpor bout duration may be influenced by EWL, indicating that animals may need to obtain free water when they arouse. An analysis of the structural and temperature characteristics of ground squirrel hibernacula suggests that they may function as a biolog...

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A possible basis for periodic arousals during hibernation: Accumulation of ketone bodies

Cited by 24 publications

References 2 publications

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Hormone and metabolite changes associated with extended breeding fasts in male northern elephant seals (Mirounga angustirostris)

Waking to drink: rates of evaporative water loss determine arousal frequency in hibernating bats

Periodic arousals in hibernating mammals: is evaporative water loss involved?

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